WorldWideScience

Sample records for cholesterol helical ribbons

  1. Dynamics of sandwich domain structure in Co-based amorphous ribbons with helical magnetic anisotropy: Part I

    International Nuclear Information System (INIS)

    Zhmetko, D.N.; Zhmetko, S.D.

    2009-01-01

    The distribution of axes of easy magnetization close to a homogeneous distribution is revealed in each half-thickness of a ribbon after annealing it in a helical magnetic field. The transition from magnetic reversal of a ribbon by the displacement of two domain walls formed near a middle plane of a ribbon to magnetic reversal of a ribbon by displacement of two domain walls formed near to the main surfaces of a ribbon is found out during each half-period of a magnetic reversal.

  2. Domain walls dynamics in the amorphous ribbon with a helical magnetic anisotropy

    International Nuclear Information System (INIS)

    Zhmetko, D.N.; Savin, V.V.; Lemish, P.V.; Troschenkov, Y.N.

    2006-01-01

    The damping mechanism for motion of domain walls, which form the sandwich structure and move from the middle plane of the ribbon to opposite surfaces during the dynamic magnetization reversal, have been investigated. The difference between the real and ideal sandwich domain structure, the actual distribution of the anisotropy easy directions through the ribbon thickness and the M-bar s deviation from local easy directions under the action of applied magnetic field have been taken into account. It was revealed that the maximum of the total damping coefficient β tot (x) near the half-way of the domain wall run is due to the influence of the magnetic stray fields. These fields have a character of irregular oscillations and are directed approximately perpendicular to the local easy direction of the ribbon layer through which the domain wall propagates. The damping coefficient β e.c. (x) determined by eddy-currents has the maximal value close to the ribbon middle and decreases linearly to zero when the domain wall approaches the ribbon surface

  3. Helical twisting in nemato-cholesteric systems based on cholesterol derivatives and photosensitive azoxy compounds

    Energy Technology Data Exchange (ETDEWEB)

    Serbina, M. I.; Kasian, N. A.; Lisetski, L. N., E-mail: lisetski@isma.kharkov.ua [NAS of Ukraine, Institute for Scintillation Materials, STC ' Institute for Single Crystals' (Ukraine)

    2013-01-15

    For cholesteric liquid crystal systems containing photosensitive nematic ZhK-440 and a mixture of cholesterol derivatives, changes in helical twisting induced by UV radiation were studied. The UV-induced shift of selective reflection maximum {lambda}{sub max} was shown to depend upon concentration of the nematic component. For low concentrations of ZhK-440, {lambda}{sub max} increases, which correlates with corresponding changes with increasing temperature. For higher concentrations, {lambda}{sub max} decreases, regardless of the temperature behavior of the system. A theoretical description of the available experimental data is proposed on the basis of development of molecular models of helical twisting, including an assumed possibility of ordered orientation of short molecular axes of cis-isomers formed as a result of UV irradiation, which is determined by the sense of the cholesteric helix already present in the system.

  4. Ribbon curling

    Science.gov (United States)

    Juel, Anne; Prior, Chris; Moussou, Julien; Chakrabarti, Buddhapriya; Jensen, Oliver

    The procedure of curling a ribbon by running it over a sharp blade is commonly used when wrapping presents. Despite its ubiquity, a quantitative explanation of this everyday phenomenon is still lacking. We address this using experiment and theory, examining the dependence of ribbon curvature on blade curvature, the longitudinal load imposed on the ribbon and the speed of pulling. Experiments in which a ribbon is drawn steadily over a blade under a fixed load show that the ribbon curvature is generated over a restricted range of loads, the curvature/load relationship can be non-monotonic, and faster pulling (under a constant imposed load) results in less tightly curled ribbons. We develop a theoretical model that captures these features, building on the concept that the ribbon under the imposed deformation undergoes differential plastic stretching across its thickness, resulting in a permanently curved shape. The model identifies factors that optimize curling and clarifies the physical mechanisms underlying the ribbon's nonlinear response to an apparently simple deformation.

  5. Amphipathic alpha-helices and putative cholesterol binding domains of the influenza virus matrix M1 protein are crucial for virion structure organisation.

    Science.gov (United States)

    Tsfasman, Tatyana; Kost, Vladimir; Markushin, Stanislav; Lotte, Vera; Koptiaeva, Irina; Bogacheva, Elena; Baratova, Ludmila; Radyukhin, Victor

    2015-12-02

    The influenza virus matrix M1 protein is an amphitropic membrane-associated protein, forming the matrix layer immediately beneath the virus raft membrane, thereby ensuring the proper structure of the influenza virion. The objective of this study was to elucidate M1 fine structural characteristics, which determine amphitropic properties and raft membrane activities of the protein, via 3D in silico modelling with subsequent mutational analysis. Computer simulations suggest the amphipathic nature of the M1 α-helices and the existence of putative cholesterol binding (CRAC) motifs on six amphipathic α-helices. Our finding explains for the first time many features of this protein, particularly the amphitropic properties and raft/cholesterol binding potential. To verify these results, we generated mutants of the A/WSN/33 strain via reverse genetics. The M1 mutations included F32Y in the CRAC of α-helix 2, W45Y and W45F in the CRAC of α-helix 3, Y100S in the CRAC of α-helix 6, M128A and M128S in the CRAC of α-helix 8 and a double L103I/L130I mutation in both a putative cholesterol consensus motif and the nuclear localisation signal. All mutations resulted in viruses with unusual filamentous morphology. Previous experimental data regarding the morphology of M1-gene mutant influenza viruses can now be explained in structural terms and are consistent with the pivotal role of the CRAC-domains and amphipathic α-helices in M1-lipid interactions. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Nonpolar interactions between trans-membrane helical EGF peptide and phosphatidylcholines, sphingomyelins and cholesterol. Molecular dynamics simulation studies

    NARCIS (Netherlands)

    Róg, T.; Murzyn, K.; Karttunen, M.E.J.; Pasenkiewicz-Gierula, M.

    2008-01-01

    A molecular dynamics simulation study of four lipid bilayers with inserted trans-membrane helical fragment of epithelial growth factor (EGF) receptor (EGF peptide) was performed. The lipid bilayers differ in their lipid composition and consist of (i) unsaturated phosphatidylcholine

  7. Elongation of Flare Ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman MT (United States); Cassak, Paul A. [Department of Physics and Astronomy, West Virginia University, Morgantown WV (United States); Priest, Eric R. [School of Mathematics and Statistics, University of St. Andrews, Fife KY16 9SS, Scotland (United Kingdom)

    2017-03-20

    We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s{sup −1}. The shear measured from conjugate footpoints is consistent with the measurement from flare loops, and both show the decrease of shear toward a potential field as a flare evolves and ribbons and loops spread along the PIL. Flares exhibiting fast bidirectional elongation appear to have a strong shear, which may indicate a large magnetic guide field relative to the reconnection field in the coronal current sheet. We discuss how the analysis of ribbon motion could help infer properties in the corona where reconnection takes place.

  8. Blue Ribbon Panel Report

    Science.gov (United States)

    An NCI Cancer Currents blog by the NCI acting director thanking the cancer community for contributing to the Cancer Moonshot Blue Ribbon Panel report, which was presented to the National Cancer Advisory Board on September 7.

  9. After the Ribbon Cutting

    DEFF Research Database (Denmark)

    Hodge, Graeme A.; Boulot, Emille; Duffield, Colin

    2017-01-01

    Much attention has gone towards ‘up-front’ processes when delivering infrastructure public–private partnerships (PPPs), but less on how to best govern after the ribbon is cut and the infrastructure built. This paper identifies the primary contractual and institutional governance challenges arising...

  10. What's Cholesterol?

    Science.gov (United States)

    ... LDL. Most cholesterol is LDL (low-density lipoprotein) cholesterol. LDL cholesterol is more likely to clog blood vessels because ... Here's a way to remember the difference: the LDL cholesterol is the bad kind, so call it "lousy" ...

  11. Baffles Promote Wider, Thinner Silicon Ribbons

    Science.gov (United States)

    Seidensticker, Raymond G.; Mchugh, James P.; Hundal, Rolv; Sprecace, Richard P.

    1989-01-01

    Set of baffles just below exit duct of silicon-ribbon-growing furnace reduces thermal stresses in ribbons so wider ribbons grown. Productivity of furnace increased. Diverts plume of hot gas from ribbon and allows cooler gas from top of furnace to flow around. Also shields ribbon from thermal radiation from hot growth assembly. Ribbon cooled to lower temperature before reaching cooler exit duct, avoiding abrupt drop in temperature as entering duct.

  12. Cholesterol (image)

    Science.gov (United States)

    Cholesterol is a soft, waxy substance that is present in all parts of the body including the ... and obtained from animal products in the diet. Cholesterol is manufactured in the liver and is needed ...

  13. Cholesterol Test

    Science.gov (United States)

    ... artery disease. Other names for a cholesterol test: Lipid profile, Lipid panel What is it used for? If you ... Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998-2017.Cholesterol Test: Overview; 2016 Jan 12 [ ...

  14. Helical filaments

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

    2014-06-30

    The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

  15. Amorphous metal matrix composite ribbons

    International Nuclear Information System (INIS)

    Barczy, P.; Szigeti, F.

    1998-01-01

    Composite ribbons with amorphous matrix and ceramic (SiC, WC, MoB) particles were produced by modified planar melt flow casting methods. Weldability, abrasive wear and wood sanding examinations were carried out in order to find optimal material and technology for elevated wear resistance and sanding durability. The correlation between structure and composite properties is discussed. (author)

  16. High blood cholesterol levels

    Science.gov (United States)

    Cholesterol - high; Lipid disorders; Hyperlipoproteinemia; Hyperlipidemia; Dyslipidemia; Hypercholesterolemia ... There are many types of cholesterol. The ones talked about most are: ... lipoprotein (HDL) cholesterol -- often called "good" cholesterol ...

  17. 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)

  18. Geothermal Technologies Program Blue Ribbon Panel Recommendations

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2011-06-17

    The Geothermal Technologies Program assembled a geothermal Blue Ribbon Panel on March 22-23, 2011 in Albuquerque, New Mexico for a guided discussion on the future of geothermal energy in the United States and the role of the DOE Program. The Geothermal Blue Ribbon Panel Report captures the discussions and recommendations of the experts. An addendum is available here: http://www.eere.energy.gov/geothermal/pdfs/gtp_blue_ribbon_panel_report_addendum10-2011.pdf

  19. Dislocation dynamics of web type silicon ribbon

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, Jr, O W; Tsai, C T; DeAngelis, R J

    1987-03-01

    Silicon ribbon grown by the dendritic web process passes through a rapidly changing thermal profile in the growth direction. This rapidly changing profile induces stresses which produce changes in the dislocation density in the ribbon. A viscoplastic material response function (Haasen-Sumino model) is used herein to calculate the stresses and the dislocation density at each point in the silicon ribbon. The residual stresses are also calculated.

  20. Numerical Simulation Of Silicon-Ribbon Growth

    Science.gov (United States)

    Woda, Ben K.; Kuo, Chin-Po; Utku, Senol; Ray, Sujit Kumar

    1987-01-01

    Mathematical model includes nonlinear effects. In development simulates growth of silicon ribbon from melt. Takes account of entire temperature and stress history of ribbon. Numerical simulations performed with new model helps in search for temperature distribution, pulling speed, and other conditions favoring growth of wide, flat, relatively defect-free silicon ribbons for solar photovoltaic cells at economically attractive, high production rates. Also applicable to materials other than silicon.

  1. 3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?

    Science.gov (United States)

    Verdini, Andrea; Grappin, Roland; Alexandrova, Olga; Lion, Sonny

    2018-01-01

    We study the anisotropy with respect to the local magnetic field of turbulent magnetic fluctuations at magnetofluid scales in the solar wind. Previous measurements in the fast solar wind obtained axisymmetric anisotropy, despite that the analysis method allows nonaxisymmetric structures. These results are probably contaminated by the wind expansion that introduces another symmetry axis, namely, the radial direction, as indicated by recent numerical simulations. These simulations also show that while the expansion is strong, the principal fluctuations are in the plane perpendicular to the radial direction. Using this property, we separate 11 yr of Wind spacecraft data into two subsets characterized by strong and weak expansion and determine the corresponding turbulence anisotropy. Under strong expansion, the small-scale anisotropy is consistent with the Goldreich & Sridhar critical balance. As in previous works, when the radial symmetry axis is not eliminated, the turbulent structures are field-aligned tubes. Under weak expansion, we find 3D anisotropy predicted by the Boldyrev model, that is, turbulent structures are ribbons and not tubes. However, the very basis of the Boldyrev phenomenology, namely, a cross-helicity increasing at small scales, is not observed in the solar wind: the origin of the ribbon formation is unknown.

  2. Cholesterol testing and results

    Science.gov (United States)

    ... your cholesterol is in this normal range. LDL (Bad) Cholesterol LDL cholesterol is sometimes called "bad" cholesterol. ... to 3.3 mmol/l) are desired. VLDL (Bad) Cholesterol VLDL contains the highest amount of triglycerides. ...

  3. What Is Cholesterol?

    Science.gov (United States)

    ... of Cholesterol There are two main types of cholesterol: LDL and HDL. The cholesterol blood test tells how much of each kind you have. Most cholesterol is LDL (low-density lipoprotein) cholesterol. This type is most ...

  4. Cholesterol Facts and Statistics

    Science.gov (United States)

    ... Managing High Cholesterol Cholesterol-lowering Medicine High Cholesterol Statistics and Maps High Cholesterol Facts High Cholesterol Maps ... Deo R, et al. Heart disease and stroke statistics—2017 update: a report from the American Heart ...

  5. Synaptic ribbon. Conveyor belt or safety belt?

    Science.gov (United States)

    Parsons, T D; Sterling, P

    2003-02-06

    The synaptic ribbon in neurons that release transmitter via graded potentials has been considered as a conveyor belt that actively moves vesicles toward their release sites. But evidence has accumulated to the contrary, and it now seems plausible that the ribbon serves instead as a safety belt to tether vesicles stably in mutual contact and thus facilitate multivesicular release by compound exocytosis.

  6. Helicity content and tokamak applications of helicity

    International Nuclear Information System (INIS)

    Boozer, A.H.

    1986-05-01

    Magnetic helicity is approximately conserved by the turbulence associated with resistive instabilities of plasmas. To generalize the application of the concept of helicity, the helicity content of an arbitrary bounded region of space will be defined. The definition has the virtues that both the helicity content and its time derivative have simple expressions in terms of the poloidal and toroidal magnetic fluxes, the average toroidal loop voltage and the electric potential on the bounding surface, and the volume integral of E-B. The application of the helicity concept to tokamak plasmas is illustrated by a discussion of so-called MHD current drive, an example of a stable tokamak q profile with q less than one in the center, and a discussion of the possibility of a natural steady-state tokamak due to the bootstrap current coupling to tearing instabilities

  7. Gas-Jet Meniscus Control in Ribbon Growth

    Science.gov (United States)

    Zoutendyk, J. A.; Vonroos, O.

    1983-01-01

    Gas jet used to control shape of meniscus and thus to regulate ribbon thickness in vertical silicon-ribbon growth. Gas jet also cools ribbon, increasing maximum possible pull speed for silicon, contact angle of 11 degrees plus or minus 1 degree required for constant thickness ribbon growth. Cooling effect of gas jet increases maximum possible pull speed.

  8. Carbon nanotube fiber spun from wetted ribbon

    Science.gov (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi

    2014-04-29

    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  9. Helical type vacuum container

    International Nuclear Information System (INIS)

    Owada, Kimio.

    1989-01-01

    Helical type vacuum containers in the prior art lack in considerations for thermal expansion stresses to helical coils, and there is a possibility of coil ruptures. The object of the present invention is to avoid the rupture of helical coils wound around the outer surface of a vacuum container against heat expansion if any. That is, bellows or heat expansion absorbing means are disposed to a cross section of a helical type vacuum container. With such a constitution, thermal expansion of helical coils per se due to temperature elevation of the coils during electric supply can be absorbed by expansion of the bellows or absorption of the heat expansion absorbing means. Further, this can be attained by arranging shear pins in the direction perpendicular to the bellows axis so that the bellows are not distorted when the helical coils are wound around the helical type vacuum container. (I.S.)

  10. LDL: The "Bad" Cholesterol

    Science.gov (United States)

    ... There are two main types of cholesterol: LDL (bad) cholesterol and HDL (good) cholesterol: LDL stands for low-density lipoproteins. It is called the "bad" cholesterol because a high LDL level leads to ...

  11. ON THE GEOMETRY OF THE IBEX RIBBON

    Energy Technology Data Exchange (ETDEWEB)

    Sylla, Adama; Fichtner, Horst [Institut für Theoretische Physik IV, Ruhr-Universität Bochum, D-44780 Bochum (Germany)

    2015-10-01

    The Energetic Neutral Atom (ENA) full-sky maps obtained with the Interstellar Boundary Explorer (IBEX) show an unexpected bright narrow band of increased intensity. This so-called ENA ribbon results from charge exchange of interstellar neutral atoms with protons in the outer heliosphere or beyond. Among other hypotheses it has been argued that this ribbon may be related to a neutral density enhancement, or H-wave, in the local interstellar medium. Here we quantitatively demonstrate, on the basis of an analytical model of the principal large-scale heliospheric structure, that this scenario for the ribbon formation leads to results that are fully consistent with the observed location of the ribbon in the full-sky maps at all energies detected with high-energy sensor IBEX-Hi.

  12. Transmembrane helices can induce domain formation in crowded model membranes

    NARCIS (Netherlands)

    Domanski, Jan; Marrink, Siewert J.; Schäfer, Lars V.

    We studied compositionally heterogeneous multi-component model membranes comprised of saturated lipids, unsaturated lipids, cholesterol, and a-helical TM protein models using coarse-grained molecular dynamics simulations. Reducing the mismatch between the length of the saturated and unsaturated

  13. Black Silicon Solar Cells with Black Ribbons

    DEFF Research Database (Denmark)

    Davidsen, Rasmus Schmidt; Tang, Peter Torben; Mizushima, Io

    2016-01-01

    We present the combination of mask-less reactive ion etch (RIE) texturing and blackened interconnecting ribbons as a method for obtaining all-black solar panels, while using conventional, front-contacted solar cells. Black silicon made by mask-less reactive ion etching has total, average...... in the range 15.7-16.3%. The KOH-textured reference cell had an efficiency of 17.9%. The combination of black Si and black interconnecting ribbons may result in aesthetic, all-black panels based on conventional, front-contacted silicon solar cells....... reflectance below 0.5% across a 156x156 mm2 silicon (Si) wafer. Black interconnecting ribbons were realized by oxidizing copper resulting in reflectance below 3% in the visible wavelength range. Screen-printed Si solar cells were realized on 156x156 mm2 black Si substrates with resulting efficiencies...

  14. Cholesterol IQ Quiz

    Science.gov (United States)

    ... Artery Disease Venous Thromboembolism Aortic Aneurysm More Cholesterol IQ Quiz Updated:Jul 5,2017 Begin the quiz ... What Your Cholesterol Levels Mean Common Misconceptions Cholesterol IQ Quiz • HDL, LDL, and Triglycerides • Causes of High ...

  15. Common Misconceptions about Cholesterol

    Science.gov (United States)

    ... Venous Thromboembolism Aortic Aneurysm More Common Misconceptions about Cholesterol Updated:Jan 29,2018 How much do you ... are some common misconceptions — and the truth. High cholesterol isn’t a concern for children. High cholesterol ...

  16. Supramolecular ribbons from amphiphilic trisamides self-assembly.

    Science.gov (United States)

    García, Fátima; Buendía, Julia; Sánchez, Luis

    2011-08-05

    Two amphiphilic C(3)-symmetric OPE-based trisamides have been synthesized and their self-assembling features investigated in solution and on surface. Variable-temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these trisamides that self-assemble by the operation of triple C═O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism at a concentration as low as 1 × 10(-4) M in acetonitrile. In the reported trisamides, the large hydrophobic aromatic core acts as a solvophobic module impeding the interaction between the polar TEG chains and the amide H-bonds. This strategy makes unnecessary the separation of the amide functional groups to the polar tri(ethylene glycol) chains by paraffinic fragments. Achiral trisamide 1 self-assembles into flat ribbon-like structures that experience an amplification of chirality by the addition of a small amount of chiral 2 that generates twisted stripes.

  17. A note on helicity

    International Nuclear Information System (INIS)

    Bialynicki-Birula, I.; Newmann, E.T.; Porter, J.; Winicour, J.; Lukacs, B.; Perjes, Z.; Sebestyen, A.

    1981-03-01

    The authors give a formal definition of the helicity operator for integral spin fields, which does not involve their momentum-space decomposition. The discussion is based upon a representation of the Pauli-Lubanski operator in terms of the action on tensor fields by the Killing vectors associated with the generators of the Poincare group. This leads to an identification of the helicity operator with the duality operator defined by the space-time alternating tensor. Helicity eigenstates then correspond to self-dual or anti-self-dual fields, in agreement with usage implicit in the literature. In addiition, the relationship between helicity eigenstates which are intrinsically non-classical, and states of right or left circular polarization in classical electrodynamics are discussed. (author)

  18. Helical CT defecography

    International Nuclear Information System (INIS)

    Ferrando, R.; Fiorini, G.; Beghello, A.; Cicio, G.R.; Derchi, L.E.; Consigliere, M.; Resasco, M.; Tornago, S.

    1999-01-01

    The purpose of this work is to investigate the possible role of Helical CT defecography in pelvic floor disorders by comparing the results of the investigations with those of conventional defecography. The series analyzed consisted of 90 patients, namely 62 women and 28 men, ranging in age 24-82 years. They were all submitted to conventional defecography, and 18 questionable cases were also studied with Helical CT defecography. The conventional examination was performed during the 4 standard phases of resting, squeezing, Valsalva and straining; it is used a remote-control unit. The parameters for Helical CT defecography were: 5 mm beam collimation, pitch 2, 120 KV, 250 m As and 18-20 degrees gantry inclination to acquire coronal images of the pelvic floor. The rectal ampulla was distended with a bolus of 300 mL nonionic iodinated contrast agent (dilution: 3g/cc). The patient wore a napkin and was seated on the table, except for those who could not hold the position and were thus examined supine. Twenty-second helical scans were performed at rest and during evacuation; multiplanar reconstructions were obtained especially on the sagittal plane for comparison with conventional defecographic images. Coronal Helical CT defecography images permitted to map the perineal floor muscles, while sagittal reconstructions provided information on the ampulla and the levator ani. To conclude, Helical CT defecography performed well in study of pelvic floor disorders and can follow conventional defecography especially in questionable cases [it

  19. Structure and magnetic properties of Alnico ribbons

    Science.gov (United States)

    Zhang, Ce; Li, Ying; Han, Xu-Hao; Du, Shuai-long; Sun, Ji-bing; Zhang, Ying

    2018-04-01

    Al-Ni-Co alloy has been widely applied in various industrial fields due to its excellent thermal and magnetic stability. In this paper, new Al-Ni-Co ribbons are prepared by simple processes combining melt-spinning with annealing, and their phase transition, microstructure and magnetic properties are studied. The results show that after as-spun ribbons are annealed, the grain size of ribbons increases from 1.1 ± 0.3 μm to 4.8 ± 0.8 μm, but still much smaller than that of the bulk Al-Ni-Co alloy manufactured by traditional technologies. In addition, some rod-like Al70Co20Ni10-type, Al9Co2-type and Fe2Nb-type phases are precipitated at grain boundaries; simultaneously, the distinct spinodal decomposition microstructure with periodic ingredient variation is thoroughly formed in all grains by the reaction of α → α1 + α2. Furthermore, the α1 and α2 distribute alternately like a maze, the Fe-Co-rich α1 phase holds 35.9-47.3 vol%, while the Al-Ni-rich α2 phase occupies the rest. Finally, the coercivity of annealed ribbons can reach to 485.3 ± 76.6 Oe. If the annealed ribbons are further aged at 560 °C, their Hc even increases to 738.1 ± 81.0 Oe. The coercivity mechanism is discussed by the combination of microstructure and domain structure.

  20. Helicity, Reconnection, and Dynamo Effects

    International Nuclear Information System (INIS)

    Ji, Hantao

    1998-01-01

    The inter-relationships between magnetic helicity, magnetic reconnection, and dynamo effects are discussed. In laboratory experiments, where two plasmas are driven to merge, the helicity content of each plasma strongly affects the reconnection rate, as well as the shape of the diffusion region. Conversely, magnetic reconnection events also strongly affect the global helicity, resulting in efficient helicity cancellation (but not dissipation) during counter-helicity reconnection and a finite helicity increase or decrease (but less efficiently than dissipation of magnetic energy) during co-helicity reconnection. Close relationships also exist between magnetic helicity and dynamo effects. The turbulent electromotive force along the mean magnetic field (alpha-effect), due to either electrostatic turbulence or the electron diamagnetic effect, transports mean-field helicity across space without dissipation. This has been supported by direct measurements of helicity flux in a laboratory plasma. When the dynamo effect is driven by electromagnetic turbulence, helicity in the turbulent field is converted to mean-field helicity. In all cases, however, dynamo processes conserve total helicity except for a small battery effect, consistent with the observation that the helicity is approximately conserved during magnetic relaxation

  1. Application Potential of Nanocrystalline Ribbons Still Pending

    Science.gov (United States)

    Butvin, Pavol; Butvinová, Beata; Švec, Peter; Sitek, Jozef

    2010-09-01

    Nanocrystalline soft-magnetic ribbons promised a wide-spread practical use when introduced at the beginning of nineties. After 20 years of extensive research there are still unclear material problems which are thought to be the principal reason why these materials show but marginal use. Poorly controllable magnetic anisotropy due to spontaneous intrinsic macroscopic stress that comes from an inevitable heterogeneity of the ribbon materials is pointed to in this work. Certain stress-based mechanisms are shown to induce the unintended anisotropy in the already familiar Finemets as well as in the newer Hitperms. Hysteresis loops, domain structure and power loss is used to reveal the anisotropy consequences and particular connected but still unanswered questions are pinpointed.

  2. Oxygen measurements in thin ribbon silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hyland, S L; Ast, D G; Baghdadi, A

    1987-03-01

    The oxygen content of thin silicon ribbons grown by the dendritic web technique was measured using a modification of the ASTM method based on Fourier transform infrared spectroscopy. Web silicon was found to have a high oxygen content, ranging from 13 to 19 ppma, calculated from the absorption peak associated with interstitial oxygen and using the new ASTM conversion coefficient. The oxygen concentration changed by about 10% along the growth direction of the ribbon. In some samples, a shoulder was detected on the absorption peak. A similar shoulder in Czochralski grown material has been variously interpreted in the literature as due to a complex of silicon, oxygen, and vacancies, or to a phase of SiO/sub 2/ developed along dislocations in the material. In the case of web silicon, it is not clear which is the correct interpretation.

  3. Pseudo ribbon metal ion beam source

    International Nuclear Information System (INIS)

    Stepanov, Igor B.; Ryabchikov, Alexander I.; Sivin, Denis O.; Verigin, Dan A.

    2014-01-01

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface

  4. Pseudo ribbon metal ion beam source.

    Science.gov (United States)

    Stepanov, Igor B; Ryabchikov, Alexander I; Sivin, Denis O; Verigin, Dan A

    2014-02-01

    The paper describes high broad metal ion source based on dc macroparticle filtered vacuum arc plasma generation with the dc ion-beam extraction. The possibility of formation of pseudo ribbon beam of metal ions with the parameters: ion beam length 0.6 m, ion current up to 0.2 A, accelerating voltage 40 kV, and ion energy up to 160 kV has been demonstrated. The pseudo ribbon ion beam is formed from dc vacuum arc plasma. The results of investigation of the vacuum arc evaporator ion-emission properties are presented. The influence of magnetic field strength near the cathode surface on the arc spot movement and ion-emission properties of vacuum-arc discharge for different cathode materials are determined. It was shown that vacuum-arc discharge stability can be reached when the magnetic field strength ranges from 40 to 70 G on the cathode surface.

  5. Helical-D pinch

    International Nuclear Information System (INIS)

    Schaffer, M.J.

    1997-08-01

    A stabilized pinch configuration is described, consisting of a D-shaped plasma cross section wrapped tightly around a guiding axis. The open-quotes helical-Dclose quotes geometry produces a very large axial (toroidal) transform of magnetic line direction that reverses the pitch of the magnetic lines without the need of azimuthal (poloidal) plasma current. Thus, there is no need of a open-quotes dynamoclose quotes process and its associated fluctuations. The resulting configuration has the high magnetic shear and pitch reversal of the reversed field pinch (RFP). (Pitch = P = qR, where R = major radius). A helical-D pinch might demonstrate good confinement at q << 1

  6. Are All Flare Ribbons Simply Connected to the Corona?

    Energy Technology Data Exchange (ETDEWEB)

    Judge, Philip G. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Paraschiv, Alin; Lacatus, Daniela; Donea, Alina [Monash Center for Astrophysics, School of Mathematical Science, Monash University, Victoria 3800 (Australia); Lindsey, Charlie, E-mail: judge@ucar.edu, E-mail: alina.donea@monash.edu, E-mail: alin.paraschiv@monash.edu, E-mail: daniela.lacatus@monash.edu, E-mail: indsey@cora.nwra.com [Northwest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301 (United States)

    2017-04-01

    We consider the observational basis for the belief that flare ribbons in the chromosphere result from energy transport from the overlying corona. We study ribbons of small flares using magnetic and intensity data from the Hinode , Solar Dynamics Observatory , and IRIS missions. While most ribbons appear connected to the corona and overlie regions of significant vertical magnetic field, we examine one ribbon with no clear evidence for such connections. Evolving horizontal magnetic fields seen with Hinode suggest that reconnection with preexisting fields below the corona can explain the data. The identification of just one, albeit small, ribbon, with no apparent connection to the corona, leads us to conclude that at least two mechanisms are responsible for the heating that leads to flare ribbon emission.

  7. Controlling Cholesterol with Statins

    Science.gov (United States)

    ... For Consumers Home For Consumers Consumer Updates Controlling Cholesterol with Statins Share Tweet Linkedin Pin it More ... not, the following tips can help keep your cholesterol in check: Talk with your healthcare provider about ...

  8. Cholesterol - drug treatment

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000314.htm Cholesterol - drug treatment To use the sharing features on ... treatment; Hardening of the arteries - statin Statins for Cholesterol Statins reduce your risk of heart disease, stroke, ...

  9. Plastic deformation of silicon dendritic web ribbons during the growth

    Science.gov (United States)

    Cheng, L. J.; Dumas, K. A.; Su, B. M.; Leipold, M. H.

    1984-01-01

    The distribution of slip dislocations in silicon dendritic web ribbons due to plastic deformation during the cooling phase of the growth was studied. The results show the existence of two distinguishable stress regions across the ribbon formed during the plastic deformation stage, namely, shear stress at the ribbon edges and tensile stress at the middle. In addition, slip dislocations caused by shear stress near the edges appear to originate at the twin plane.

  10. Review of the helicity formalism

    International Nuclear Information System (INIS)

    Barreiro, F.; Cerrada, M.; Fernandez, E.

    1972-01-01

    Our purpose in these notes has been to present a brief and general review of the helicity formalism. We begin by discussing Lorentz invariance, spin and helicity ideas, in section 1 . In section 2 we deal with the construction of relativistic states and scattering amplitudes in the helicity basis and we study their transformation properties under discrete symmetries. Finally we present some more sophisticated topics like kinematical singularities of helicity amplitudes, kinematical constraints and crossing relations 3, 4, 5 respectively. (Author) 8 refs

  11. Helical Confinement Concepts

    Energy Technology Data Exchange (ETDEWEB)

    Beidler, C; Brakel, R; Burhenn, R; Dinklage, A; Erckmann, V; Feng, Y; Geiger, J; Hartmann, D; Hirsch, M; Jaenicke, R; Koenig, R; Laqua, H P; Maassberg, H; Wagner, F; Weller, A; Wobig, H [Max-Planck Institut fuer Plasmaphysik, EURATOM Association, Greifswald (Germany)

    2012-09-15

    Stellarators, conceived 1951 by Lyman Spitzer in Princeton, are toroidal devices that confine a plasma in a magnetic field which originates from currents in coils outside the plasma. A plasma current driven by external means, for example by an ohmic transformer, is not required for confinement. Supplying the desired poloidal field component by external coils leads to a helically structured plasma topology. Thus stellarators - or helical confinement devices - are fully three-dimensional in contrast to the toroidal (rotational) symmetry of tokamaks. As stellarators can be free of an inductive current, whose radial distribution depends on the plasma parameters, their equilibrium must not be established via the evolving plasma itself, but to a first order already given by the vacuum magnetic field. They do not need an active control (like positional feedback) and therefore cannot suffer from its failure. The outstanding conceptual advantage of stellarators is the potential of steady state plasma operation without current drive. As there is no need for current drive, the recirculating power is expected to be smaller than in equivalent tokamaks. The lack of a net current avoids current driven instabilities; specifically, no disruptions, no resistive wall modes and no conventional or neoclassical tearing modes appear. Second order pressure-driven currents (Pfirsch-Schlueter, bootstrap) exist but they can be modified and even minimized by the magnetic design. The magnetic configuration of helical devices naturally possesses a separatrix, which allows the implementation of a helically structured divertor for exhaust and impurity control. (author)

  12. Ca(2+) influx and neurotransmitter release at ribbon synapses.

    Science.gov (United States)

    Cho, Soyoun; von Gersdorff, Henrique

    2012-01-01

    Ca(2+) influx through voltage-gated Ca(2+) channels triggers the release of neurotransmitters at presynaptic terminals. Some sensory receptor cells in the peripheral auditory and visual systems have specialized synapses that express an electron-dense organelle called a synaptic ribbon. Like conventional synapses, ribbon synapses exhibit SNARE-mediated exocytosis, clathrin-mediated endocytosis, and short-term plasticity. However, unlike non-ribbon synapses, voltage-gated L-type Ca(2+) channel opening at ribbon synapses triggers a form of multiquantal release that can be highly synchronous. Furthermore, ribbon synapses appear to be specialized for fast and high throughput exocytosis controlled by graded membrane potential changes. Here we will discuss some of the basic aspects of synaptic transmission at different types of ribbon synapses, and we will emphasize recent evidence that auditory and retinal ribbon synapses have marked differences. This will lead us to suggest that ribbon synapses are specialized for particular operating ranges and frequencies of stimulation. We propose that different types of ribbon synapses transfer diverse rates of sensory information by expressing a particular repertoire of critical components, and by placing them at precise and strategic locations, so that a continuous supply of primed vesicles and Ca(2+) influx leads to fast, accurate, and ongoing exocytosis. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Home-Use Tests - Cholesterol

    Science.gov (United States)

    ... Medical Procedures In Vitro Diagnostics Home Use Tests Cholesterol Share Tweet Linkedin Pin it More sharing options ... a home-use test kit to measure total cholesterol. What cholesterol is: Cholesterol is a fat (lipid) ...

  14. Scintillating ribbon x-ray detector

    International Nuclear Information System (INIS)

    Kinchen, B.E.; Rogers, A.

    1995-01-01

    A patent in the early 1970's by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University

  15. Coulomb double helical structure

    Science.gov (United States)

    Kamimura, Tetsuo; Ishihara, Osamu

    2012-01-01

    Structures of Coulomb clusters formed by dust particles in a plasma are studied by numerical simulation. Our study reveals the presence of various types of self-organized structures of a cluster confined in a prolate spheroidal electrostatic potential. The stable configurations depend on a prolateness parameter for the confining potential as well as on the number of dust particles in a cluster. One-dimensional string, two-dimensional zigzag structure and three-dimensional double helical structure are found as a result of the transition controlled by the prolateness parameter. The formation of stable double helical structures resulted from the transition associated with the instability of angular perturbations on double strings. Analytical perturbation study supports the findings of numerical simulations.

  16. Modeling of inter-ribbon tunneling in graphene

    OpenAIRE

    Van de Put, Maarten L.; Vandenberghe, William G.; Sorée, Bart; Magnus, Wim; Fischetti, Massimo

    2015-01-01

    The tunneling current between two crossed graphene ribbons is described invoking the empirical pseudopotential approximation and the Bardeen transfer Hamiltonian method. Results indicate that the density of states is the most important factor determining the tunneling current between small (nm) ribbons. The quasi-one dimensional nature of graphene nanoribbons is shown to result in resonant tunneling.

  17. Helically linked mirror arrangement

    International Nuclear Information System (INIS)

    Ranjan, P.

    1986-08-01

    A scheme is described for helical linking of mirror sections, which endeavors to combine the better features of toroidal and mirror devices by eliminating the longitudinal loss of mirror machines, having moderately high average β and steady state operation. This scheme is aimed at a device, with closed magnetic surfaces having rotational transform for equilibrium, one or more axisymmetric straight sections for reduced radial loss, a simple geometrical axis for the links and an overall positive magnetic well depth for stability. We start by describing several other attempts at linking of mirror sections, made both in the past and the present. Then a description of our helically linked mirror scheme is given. This example has three identical straight sections connected by three sections having helical geometric axes. A theoretical analysis of the magnetic field and single-particle orbits in them leads to the conclusion that most of the passing particles would be confined in the device and they would have orbits independent of pitch angle under certain conditions. Numerical results are presented, which agree well with the theoretical results as far as passing particle orbits are concerned

  18. Electrostatics-Driven Hierarchical Buckling of Charged Flexible Ribbons.

    Science.gov (United States)

    Yao, Zhenwei; Olvera de la Cruz, Monica

    2016-04-08

    We investigate the rich morphologies of an electrically charged flexible ribbon, which is a prototype for many beltlike structures in biology and nanomaterials. Long-range electrostatic repulsion is found to govern the hierarchical buckling of the ribbon from its initially flat shape to its undulated and out-of-plane twisted conformations. In this process, the screening length is the key controlling parameter, suggesting that a convenient way to manipulate the ribbon morphology is simply to change the salt concentration. We find that these shapes originate from the geometric effect of the electrostatic interaction, which fundamentally changes the metric over the ribbon surface. We also identify the basic modes by which the ribbon reshapes itself in order to lower the energy. The geometric effect of the physical interaction revealed in this Letter has implications for the shape design of extensive ribbonlike materials in nano- and biomaterials.

  19. Graphene ribbon growth on structured silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Stoehr, Alexander; Link, Stefan; Starke, Ulrich [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Baringhaus, Jens; Aprojanz, Johannes; Tegenkamp, Christoph [Institut fuer Festkoerperphysik, Leibniz Universitaet Hannover (Germany); Niu, Yuran [MAX IV Laboratory, Lund University (Sweden); present address: School of Physics and Astronomy, Cardiff University (United Kingdom); Zakharov, Alexei A. [MAX IV Laboratory, Lund University (Sweden); Chen, Chaoyu; Avila, Jose; Asensio, Maria C. [Synchrotron SOLEIL and Universite Paris-Saclay, Gif sur Yvette (France)

    2017-11-15

    Structured Silicon Carbide was proposed to be an ideal template for the production of arrays of edge specific graphene nanoribbons (GNRs), which could be used as a base material for graphene transistors. We prepared periodic arrays of nanoscaled stripe-mesas on SiC surfaces using electron beam lithography and reactive ion etching. Subsequent epitaxial graphene growth by annealing is differentiated between the basal-plane mesas and the faceting stripe walls as monitored by means of atomic force microscopy (AFM). Microscopic low energy electron diffraction (μ-LEED) revealed that the graphene ribbons on the facetted mesa side walls grow in epitaxial relation to the basal-plane graphene with an armchair orientation at the facet edges. The π-band system of the ribbons exhibits linear bands with a Dirac like shape corresponding to monolayer graphene as identified by angle-resolved photoemission spectroscopy (ARPES). (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. The ribbon microphone - an educational aid: use of a ribbon microphone to teach multi-discipline computer simulation skills

    CSIR Research Space (South Africa)

    Van Wyk, Marius

    2016-07-01

    Full Text Available The ribbon microphone serves as an excellent aid to learn computer simulation and computational skills. Simulation of this seemingly simple device is all but trivial. The ribbon microphone is an all-in-one example for simulations in acoustics...

  1. Observations and Numerical Modeling of the Jovian Ribbon

    Science.gov (United States)

    Cosentino, R. G.; Simon, A.; Morales-Juberias, R.; Sayanagi, K. M.

    2015-01-01

    Multiple wavelength observations made by the Hubble Space Telescope in early 2007 show the presence of a wavy, high-contrast feature in Jupiter's atmosphere near 30 degrees North. The "Jovian Ribbon," best seen at 410 nanometers, irregularly undulates in latitude and is time-variable in appearance. A meridional intensity gradient algorithm was applied to the observations to track the Ribbon's contour. Spectral analysis of the contour revealed that the Ribbon's structure is a combination of several wavenumbers ranging from k equals 8-40. The Ribbon is a dynamic structure that has been observed to have spectral power for dominant wavenumbers which vary over a time period of one month. The presence of the Ribbon correlates with periods when the velocity of the westward jet at the same location is highest. We conducted numerical simulations to investigate the stability of westward jets of varying speed, vertical shear, and background static stability to different perturbations. A Ribbon-like morphology was best reproduced with a 35 per millisecond westward jet that decreases in amplitude for pressures greater than 700 hectopascals and a background static stability of N equals 0.005 per second perturbed by heat pulses constrained to latitudes south of 30 degrees North. Additionally, the simulated feature had wavenumbers that qualitatively matched observations and evolved throughout the simulation reproducing the Jovian Ribbon's dynamic structure.

  2. Diagrammatic documentation for ribbon computing in Microsoft Office

    Directory of Open Access Journals (Sweden)

    Kaveh Farbeh-Tabrizi

    Full Text Available In 2007 Microsoft changed the graphical user interface of MS Office, and moved away from the long -established drop down menu approach to a ribbon graphical user interface. There have been mixed reactions to Microsoft\\'s ribbon interface. Ericson (2006 mentioned that even the experienced user might have difficulty adopting the interface, and Dostal (2010 concluded that the biggest issue with the Ribbon User Interface is to get accustomed to a redesigned user interface. Reaction to this change was negative among our new and current students. For years the students had tried to memorise how to apply the right commands in Microsoft Office applications by selecting the correct items from the dropdown menus of the WIMP (windows, icons, menus, pointer interface, and now that they were confronted with the new interface their confusion had begun to slow their progress down. The major effect in transition from the traditional WIMP interface to the Ribbon interface had created a difficulty for most students who had their original training with the older versions of MS Office software, as they were not able to locate the commands that they had learnt with the earlier versions of the MS Office in the new Ribbon interfaced version. The shrinking nature of the ribbon that would hide some commands on the ribbon when the resolution of the screen changes was also confusing for those students as they could not quickly locate the command they were looking for because the Ribbon had compacted them to save space. For both new students and also more experienced ones, the approach to learning the Ribbon Interface seemed to be difficult due to the fact that they had to memorise the hierarchy of tab names, group names and then the commands. This led us to enhance our current teaching methods to try to deal with this change.

  3. National Cholesterol Education Month

    Centers for Disease Control (CDC) Podcasts

    2009-09-01

    Do you know your cholesterol numbers? Your doctor can do a simple test to check your cholesterol levels and help you make choices that lower your risk for heart disease and stroke.  Created: 9/1/2009 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP).   Date Released: 9/9/2009.

  4. Cholesterol - what to ask your doctor

    Science.gov (United States)

    ... your doctor; What to ask your doctor about cholesterol ... What is my cholesterol level? What should my cholesterol level be? What are HDL ("good") cholesterol and LDL ("bad") cholesterol? Does my cholesterol ...

  5. Cholesterol-Binding Sites in GIRK Channels: The Devil is in the Details.

    Science.gov (United States)

    Rosenhouse-Dantsker, Avia

    2018-01-01

    In recent years, it has become evident that cholesterol plays a direct role in the modulation of a variety of ion channels. In most cases, cholesterol downregulates channel activity. In contrast, our earlier studies have demonstrated that atrial G protein inwardly rectifying potassium (GIRK) channels are upregulated by cholesterol. Recently, we have shown that hippocampal GIRK currents are also upregulated by cholesterol. A combined computational-experimental approach pointed to putative cholesterol-binding sites in the transmembrane domain of the GIRK2 channel, the primary subunit in hippocampal GIRK channels. In particular, the principal cholesterol-binding site was located in the center of the transmembrane domain in between the inner and outer α-helices of 2 adjacent subunits. Further studies pointed to a similar cholesterol-binding site in GIRK4, a major subunit in atrial GIRK channels. However, a close look at a sequence alignment of the transmembrane helices of the 2 channels reveals surprising differences among the residues that interact with the cholesterol molecule in these 2 channels. Here, we compare the residues that form putative cholesterol-binding sites in GIRK2 and GIRK4 and discuss the similarities and differences among them.

  6. Helical Tomotherapy Quality Assurance

    International Nuclear Information System (INIS)

    Balog, John; Soisson, Emilie

    2008-01-01

    Helical tomotherapy uses a dynamic delivery in which the gantry, treatment couch, and multileaf collimator leaves are all in motion during treatment. This results in highly conformal radiotherapy, but the complexity of the delivery is partially hidden from the end-user because of the extensive integration and automation of the tomotherapy control systems. This presents a challenge to the medical physicist who is expected to be both a system user and an expert, capable of verifying relevant aspects of treatment delivery. A related issue is that a clinical tomotherapy planning system arrives at a customer's site already commissioned by the manufacturer, not by the clinical physicist. The clinical physicist and the manufacturer's representative verify the commissioning at the customer site before acceptance. Theoretically, treatment could begin immediately after acceptance. However, the clinical physicist is responsible for the safe and proper use of the machine. In addition, the therapists and radiation oncologists need to understand the important machine characteristics before treatment can proceed. Typically, treatment begins about 2 weeks after acceptance. This report presents an overview of the tomotherapy system. Helical tomotherapy has unique dosimetry characteristics, and some of those features are emphasized. The integrated treatment planning, delivery, and patient-plan quality assurance process is described. A quality assurance protocol is proposed, with an emphasis on what a clinical medical physicist could and should check. Additionally, aspects of a tomotherapy quality assurance program that could be checked automatically and remotely because of its inherent imaging system and integrated database are discussed

  7. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are

  8. Bile acid sequestrants for cholesterol

    Science.gov (United States)

    ... ency/patientinstructions/000787.htm Bile acid sequestrants for cholesterol To use the sharing features on this page, ... are medicines that help lower your LDL (bad) cholesterol . Too much cholesterol in your blood can stick ...

  9. Magnetic and sensitive magnetoelastic properties of Finemet nanostructured ribbon

    International Nuclear Information System (INIS)

    Pham Duc Thang; Hoang Hai Duong; Nguyen Hoang Nghi

    2009-01-01

    Soft-magnetic Fe 73.5 Cu 1 Nb 3 Si 13.5 B 9 (Finemet) ribbon has been fabricated by using melt-spinning techniques. After annealing at suitable temperature the ribbon changes from an amorphous to crystalline state which related to the formation of Fe nanocrystallites. Study on the magnetic and magnetoelastic properties of the ribbon is presented. Furthermore, based on the fabricated ribbon stress sensors are simply constructed. The sensors showed high sensitivity of 3.8 mV/MPa as well as a wide working range up to 17 MPa. These sensors are potential for practical applications such as detecting small stress and movement in civil structures.

  10. Nanostructure and magnetic properties of Ni-substituted finemet ribbons

    International Nuclear Information System (INIS)

    Iturriza, N.; Fernandez, L.; Ipatov, M.; Vara, G.; Pierna, A.R.; Val, J.J. del; Chizhik, A.; Gonzalez, J.

    2007-01-01

    Magnetic anisotropy has been induced during the nanocrystallization process of Ni-rich amorphous ferromagnetic (Finemet) ribbons by means of the application of a constant stress during the annealing process. Magnetization measurements have evidenced the anisotropy of the treated samples. The main goal of this work was the analysis of the treated ribbons using X-ray Diffraction (XRD), Transmission Electronic Microscopy (TEM) and Atomic Force Microscopy (AFM). AFM measurements revealed in all the cases a strong nanocrystallisation of the surface without evidences of amorphous matrix, which contrast with XRD and TEM measurements that have shown a high content of amorphous phase in the bulk of the ribbons. Magneto-optical Kerr effect measurements show much higher coercive field values than in the bulk, indicating a complex magnetic behavior for the surface of the ribbons

  11. Analysis of stress-strain relationships in silicon ribbon

    Science.gov (United States)

    Dillon, O. W., Jr.

    1984-01-01

    An analysis of stress-strain relationships in silicon ribbon is presented. A model to present entire process, dynamical Transit Analysis is developed. It is found that knowledge of past-strain history is significant in modeling activities.

  12. Development of a magnetic measurement device for thin ribbon samples

    International Nuclear Information System (INIS)

    Sato, Yuta; Todaka, Takashi; Enokizono, Masato

    2008-01-01

    This paper presents a magnetic measurement device for thin ribbon samples, which are produced by rapid cooling technique. This device enables us to measure magnetic properties easily by only inserting a ribbon sample into a sample holder. The sample holder was made by bakelite to fix any width sample. A long solenoid coil was used to generate a uniform magnetic field and the sample holder was placed at the mid part of the solenoid. The magnetic field strength was measured using a shunt resistor and the magnetic flux density and magnetization in sample ribbons were evaluated by using search coils. The accuracy of measurement was verified with an amorphous metal ribbon sample. Next, we have measured magnetic properties of some magnetic shape memory alloys, which have different compositions. The measured results are compared and we clarified the effect of Sm contents on the magnetic properties

  13. Flexible helical yarn swimmers.

    Science.gov (United States)

    Zakharov, A P; Leshansky, A M; Pismen, L M

    2016-09-01

    We investigate the motion of a flexible Stokesian flagellar swimmer realised as a yarn made of two intertwined elastomer fibres, one active, that can reversibly change its length in response to a local excitation causing transition to the nematic state or swelling, and the other one, a passive isotropic elastomer with identical mechanical properties. A propagating chemical wave may provide an excitation mechanism ensuring a constant length of the excited region. Generally, the swimmer moves along a helical trajectory, and the propagation and rotation velocity are very sensitive to the ratio of the excited region to the pitch of the yarn, as well as to the size of a carried load. External excitation by a moving actuating beam is less effective, unless the direction of the beam is adjusted to rotation of the swimmer.

  14. LHD helical divertor

    International Nuclear Information System (INIS)

    Ohyabu, N.; Watanabe, T.; Ji Hantao

    1993-07-01

    The Large Helical Device (LHD) now under construction is a heliotron/torsatron device with a closed divertor system. The edge LHD magnetic structure has been studied in detail. A peculiar feature of the configuration is existence of edge surface layers, a complicated three dimensional magnetic structure which does not, however, seem to hamper the expected divertor functions. Two divertor operational modes are being considered for the LHD experiment, high density, cold radiative divertor operation as a safe heat removal scheme and high temperature divertor plasma operation. In the latter operation, a divertor plasma with temperature of a few kev, generated by efficient pumping, expects to lead to significant improvement in core plasma confinement. Conceptual designs of the LHD divertor components are under way. (author)

  15. Mechanism of allosteric regulation of β2-adrenergic receptor by cholesterol

    DEFF Research Database (Denmark)

    Manna, Moutusi; Niemelä, Miia; Tynkkynen, Joona

    2016-01-01

    ) - a prototypical G protein-coupled receptor - is modulated by cholesterol in an allosteric fashion. Extensive atomistic simulations show that cholesterol regulates b2AR by limiting its conformational variability. The mechanism of action is based on the binding of cholesterol at specific high-affinity sites located...... near the transmembrane helices 5-7 of the receptor. The alternative mechanism, where the β2AR conformation would be modulated by membrane-mediated interactions, plays only a minor role. Cholesterol analogues also bind to cholesterol binding sites and impede the structural flexibility of β2AR, however...... cholesterol generates the strongest effect. The results highlight the capacity of lipids to regulate the conformation of membrane receptors through specific interactions....

  16. How to Lower Cholesterol

    Science.gov (United States)

    ... includes high triglyceride levels, low HDL (good) cholesterol levels, and being overweight with a large waist measurement (more than 40 inches for men and more than 35 inches for women). Physical Activity. Everyone should get regular physical activity (30 minutes ...

  17. Cholesterol and Health

    Indian Academy of Sciences (India)

    fats and oil in the diet on the other hand. Gallstones result from ... such factors as high levels of estrogens, multiple pregnancies, obesity, genetic factors and certain ... protein with an inner core of cholesterol and triglycerides. Lipoproteins are ...

  18. Reference intervals for serum total cholesterol, HDL cholesterol and ...

    African Journals Online (AJOL)

    Reference intervals of total cholesterol, HDL cholesterol and non-HDL cholesterol concentrations were determined on 309 blood donors from an urban and peri-urban population of Botswana. Using non-parametric methods to establish 2.5th and 97.5th percentiles of the distribution, the intervals were: total cholesterol 2.16 ...

  19. Cholesterol in unusual places

    International Nuclear Information System (INIS)

    Kucerka, N; Nieh, M P; Marquardt, D; Harroun, T A; Wassail, S R; Katsaras, J

    2010-01-01

    Cholesterol is an essential component of mammalian cells, and is required for building and maintaining cell membranes, regulating their fluidity, and possibly acting as an antioxidant. Cholesterol has also been implicated in cell signaling processes, where it has been suggested that it triggers the formation of lipid rafts in the plasma membrane. Aside from cholesterol's physiological roles, what is also becoming clear is its poor affinity for lipids with unsaturated fatty acids as opposed to saturated lipids, such as sphingomyelin with which it forms rafts. We previously reported the location of cholesterol in membranes with varying degrees of acyl chain unsaturation as determined by neutron diffraction studies (Harroun et al 2006 Biochemistry 45, 1227; Harroun et al 2008 Biochemistry 47, 7090). In bilayers composed of phosphatidylcholine (PC) molecules with a saturated acyl chain at the sn-1 position or a monounsaturated acyl chain at both sn-1 and sn-2 positions, cholesterol was found in its much-accepted 'upright' position. However, in dipolyunsaturated 1,2-diarachidonyl phosphatidylcholine (20:4-20:4PC) membranes the molecule was found sequestered in the center of the bilayers. In further experiments, mixing l-palmitoyl-2-oleoyl phosphatidylcholine (16:0-18:1 PC) with 20:4-20:4PC resulted in cholesterol reverting to its upright orientation at approximately 40 mol% 16:0-18:1 PC. Interestingly, the same effect was achieved with only 5 mol% 1,2-dimyristoyl phosphatidylchoile (14:0-14:0PC).

  20. Cholesterol in unusual places

    Energy Technology Data Exchange (ETDEWEB)

    Kucerka, N; Nieh, M P; Marquardt, D; Harroun, T A; Wassail, S R; Katsaras, J, E-mail: John.Katsaras@nrc.gc.ca, E-mail: Norbert.Kucerka@nrc.gc.ca

    2010-11-01

    Cholesterol is an essential component of mammalian cells, and is required for building and maintaining cell membranes, regulating their fluidity, and possibly acting as an antioxidant. Cholesterol has also been implicated in cell signaling processes, where it has been suggested that it triggers the formation of lipid rafts in the plasma membrane. Aside from cholesterol's physiological roles, what is also becoming clear is its poor affinity for lipids with unsaturated fatty acids as opposed to saturated lipids, such as sphingomyelin with which it forms rafts. We previously reported the location of cholesterol in membranes with varying degrees of acyl chain unsaturation as determined by neutron diffraction studies (Harroun et al 2006 Biochemistry 45, 1227; Harroun et al 2008 Biochemistry 47, 7090). In bilayers composed of phosphatidylcholine (PC) molecules with a saturated acyl chain at the sn-1 position or a monounsaturated acyl chain at both sn-1 and sn-2 positions, cholesterol was found in its much-accepted 'upright' position. However, in dipolyunsaturated 1,2-diarachidonyl phosphatidylcholine (20:4-20:4PC) membranes the molecule was found sequestered in the center of the bilayers. In further experiments, mixing l-palmitoyl-2-oleoyl phosphatidylcholine (16:0-18:1 PC) with 20:4-20:4PC resulted in cholesterol reverting to its upright orientation at approximately 40 mol% 16:0-18:1 PC. Interestingly, the same effect was achieved with only 5 mol% 1,2-dimyristoyl phosphatidylchoile (14:0-14:0PC).

  1. Common structural features of cholesterol binding sites in crystallized soluble proteins.

    Science.gov (United States)

    Bukiya, Anna N; Dopico, Alejandro M

    2017-06-01

    Cholesterol-protein interactions are essential for the architectural organization of cell membranes and for lipid metabolism. While cholesterol-sensing motifs in transmembrane proteins have been identified, little is known about cholesterol recognition by soluble proteins. We reviewed the structural characteristics of binding sites for cholesterol and cholesterol sulfate from crystallographic structures available in the Protein Data Bank. This analysis unveiled key features of cholesterol-binding sites that are present in either all or the majority of sites: i ) the cholesterol molecule is generally positioned between protein domains that have an organized secondary structure; ii ) the cholesterol hydroxyl/sulfo group is often partnered by Asn, Gln, and/or Tyr, while the hydrophobic part of cholesterol interacts with Leu, Ile, Val, and/or Phe; iii ) cholesterol hydrogen-bonding partners are often found on α-helices, while amino acids that interact with cholesterol's hydrophobic core have a slight preference for β-strands and secondary structure-lacking protein areas; iv ) the steroid's C21 and C26 constitute the "hot spots" most often seen for steroid-protein hydrophobic interactions; v ) common "cold spots" are C8-C10, C13, and C17, at which contacts with the proteins were not detected. Several common features we identified for soluble protein-steroid interaction appear evolutionarily conserved. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

  2. Theoretical aspects of magnetic helicity

    International Nuclear Information System (INIS)

    Hammer, J.H.

    1985-01-01

    The magnetic helicity, usually defined as K=integralA.Bdv, where A is the vector potential and B the magnetic field, measures the topological linkage of magnetic fluxes. Helicity manifests itself in the twistedness and knottedness of flux tubes. Its significance is that it is an ideal MHD invariant. While the helicity formalism has proven very useful in understanding reversed field pinch and spheromak behavior, some problems exist in applying the method consistently for complex (e.g., toroidal) conductor geometries or in situations where magnetic flux penetrates conducting walls. Recent work has attempted to generalize K to allow for all possible geometries

  3. Flare Ribbons Approach Observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ting; Zhang, Jun; Hou, Yijun, E-mail: liting@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2017-10-10

    We report flare ribbons approach (FRA) during a multiple-ribbon M-class flare on 2015 November 4 in NOAA AR 12443, obtained by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. The flare consisted of a pair of main ribbons and two pairs of secondary ribbons. The two pairs of secondary ribbons were formed later than the appearance of the main ribbons, with respective time delays of 15 and 19 minutes. The negative-polarity main ribbon spread outward faster than the first secondary ribbon with the same polarity in front of it, and thus the FRA was generated. Just before their encounter, the main ribbon was darkening drastically and its intensity decreased by about 70% in 2 minutes, implying the suppression of main-phase reconnection that produced two main ribbons. The FRA caused the deflection of the main ribbon to the direction of secondary ribbon with a deflection angle of about 60°. A post-approach arcade was formed about 2 minutes later and the downflows were detected along the new arcade with velocities of 35–40 km s{sup −1}, indicative of the magnetic restructuring during the process of FRA. We suggest that there are three topological domains with footpoints outlined by the three pairs of ribbons. Close proximity of these domains leads to deflection of the ribbons, which is in agreement with the magnetic field topology.

  4. Godbillon Vey Helicity and Magnetic Helicity in Magnetohydrodynamics

    Science.gov (United States)

    Webb, G. M.; Hu, Q.; Anco, S.; Zank, G. P.

    2017-12-01

    The Godbillon-Vey invariant arises in homology theory, and algebraic topology, where conditions for a layered family of 2D surfaces forms a 3D manifold were elucidated. The magnetic Godbillon-Vey helicity invariant in magnetohydrodynamics (MHD) is a helicity invariant that occurs for flows, in which the magnetic helicity density hm= A\\cdotB=0 where A is the magnetic vector potential and B is the magnetic induction. Our purpose is to elucidate the evolution of the magnetic Godbillon-Vey field η =A×B/|A|2 and the Godbillon-Vey helicity hgv}= η \\cdot∇ × η in general MHD flows in which the magnetic helicity hm≠q 0. It is shown that hm acts as a source term in the Godbillon-Vey helicity transport equation, in which hm is coupled to hgv via the shear tensor of the background flow. The transport equation for hgv depends on the electric field potential ψ , which is related to the gauge for A, which takes its simplest form for the advected A gauge in which ψ =A\\cdot u where u is the fluid velocity.

  5. Helicity multiplexed broadband metasurface holograms.

    Science.gov (United States)

    Wen, Dandan; Yue, Fuyong; Li, Guixin; Zheng, Guoxing; Chan, Kinlong; Chen, Shumei; Chen, Ming; Li, King Fai; Wong, Polis Wing Han; Cheah, Kok Wai; Pun, Edwin Yue Bun; Zhang, Shuang; Chen, Xianzhong

    2015-09-10

    Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

  6. Employing helicity amplitudes for resummation

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Amsterdam Univ.

    2015-08-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in 4- and d-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard matching coefficients, for pp → H+0,1,2 jets, pp → W/Z/γ+0,1,2 jets, and pp → 2,3 jets. These operator bases are completely crossing symmetric, so the results can easily be applied to processes with e + e - and e - p collisions.

  7. Wrinkles, loops, and topological defects in twisted ribbons

    Science.gov (United States)

    Chopin, Julien

    Nature abounds with elastic ribbon like shapes including double-stranded semiflexible polymers, graphene and metal oxide nanoribbons which are examples of elongated elastic structures with a strongly anisotropic cross-section. Due to this specific geometry, it is far from trivial to anticipate if a ribbon should be considered as a flat flexible filament or a narrow thin plate. We thus perform an experiment in which a thin elastic ribbon is loaded using a twisting and traction device coupled with a micro X-ray computed tomography machine allowing a full 3D shape reconstruction. A wealth of morphological behaviors can be observed including wrinkled helicoids, curled and looped configurations, and faceted ribbons. In this talk, I will show that most morphologies can be understood using a far-from-threshold approach and simple scaling arguments. Further, we find that the various shapes can be organized in a phase diagram using the twist, the tension, and the geometry of the ribbon as control parameters. Finally, I will discuss the spontaneous formation of topological defects with negatively-signed Gaussian charge at large twist and small but finite stretch.

  8. Cholesterol and myelin biogenesis.

    Science.gov (United States)

    Saher, Gesine; Simons, Mikael

    2010-01-01

    Myelin consists of several layers of tightly compacted membranes wrapped around axons in the nervous system. The main function of myelin is to provide electrical insulation around the axon to ensure the rapid propagation of nerve conduction. As the myelinating glia terminally differentiates, they begin to produce myelin membranes on a remarkable scale. This membrane is unique in its composition being highly enriched in lipids, in particular galactosylceramide and cholesterol. In this review we will summarize the role of cholesterol in myelin biogenesis in the central and peripheral nervous system.

  9. Biogenesis of plasma membrane cholesterol

    International Nuclear Information System (INIS)

    Lange, Y.

    1986-01-01

    A striking feature of the molecular organization of eukaryotic cells is the singular enrichment of their plasma membranes in sterols. The authors studies are directed at elucidating the mechanisms underlying this inhomogeneous disposition. Cholesterol oxidase catalyzes the oxidation of plasma membrane cholesterol in intact cells, leaving intracellular cholesterol pools untouched. With this technique, the plasma membrane was shown to contain 95% of the unesterified cholesterol of cultured human fibroblasts. Cholesterol synthesized from [ 3 H] acetate moved to the plasma membrane with a half-time of 1 h at 37 0 C. They used equilibrium gradient centrifugation of homogenates of biosynthetically labeled, cholesterol oxidase treated cells to examine the distribution of newly synthesized sterols among intracellular pools. Surprisingly, lanosterol, a major precursor of cholesterol, and intracellular cholesterol both peaked at much lower buoyant density than did 3-hydroxy-3-methylglutaryl-CoA reductase. This suggests that cholesterol biosynthesis is not taken to completion in the endoplasmic reticulum. The cholesterol in the buoyant fraction eventually moved to the plasma membrane. Digitonin treatment increased the density of the newly synthesized cholesterol fractions, indicating that nascent cholesterol in transit is associated with cholesterol-rich membranes. The authors are testing the hypothesis that the pathway of cholesterol biosynthesis is spatially organized in various intracellular membranes such that the sequence of biosynthetic steps both concentrates the sterol and conveys it to the plasma membrane

  10. A MAGNETIC RIBBON MODEL FOR STAR-FORMING FILAMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Auddy, Sayantan; Basu, Shantanu [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Kudoh, Takahiro, E-mail: sauddy3@uwo.ca, E-mail: basu@uwo.ca, E-mail: kudoh@nagasaki-u.ac.jp [Faculty of Education, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki 852-8521 (Japan)

    2016-11-01

    We develop a magnetic ribbon model for molecular cloud filaments. These result from turbulent compression in a molecular cloud in which the background magnetic field sets a preferred direction. We argue that this is a natural model for filaments and is based on the interplay between turbulence, strong magnetic fields, and gravitationally driven ambipolar diffusion, rather than pure gravity and thermal pressure. An analytic model for the formation of magnetic ribbons that is based on numerical simulations is used to derive a lateral width of a magnetic ribbon. This differs from the thickness along the magnetic field direction, which is essentially the Jeans scale. We use our model to calculate a synthetic observed relation between apparent width in projection versus observed column density. The relationship is relatively flat, similar to observations, and unlike the simple expectation based on a Jeans length argument.

  11. Piezoelectric ribbons printed onto rubber for flexible energy conversion.

    Science.gov (United States)

    Qi, Yi; Jafferis, Noah T; Lyons, Kenneth; Lee, Christine M; Ahmad, Habib; McAlpine, Michael C

    2010-02-10

    The development of a method for integrating highly efficient energy conversion materials onto stretchable, biocompatible rubbers could yield breakthroughs in implantable or wearable energy harvesting systems. Being electromechanically coupled, piezoelectric crystals represent a particularly interesting subset of smart materials that function as sensors/actuators, bioMEMS devices, and energy converters. Yet, the crystallization of these materials generally requires high temperatures for maximally efficient performance, rendering them incompatible with temperature-sensitive plastics and rubbers. Here, we overcome these limitations by presenting a scalable and parallel process for transferring crystalline piezoelectric nanothick ribbons of lead zirconate titanate from host substrates onto flexible rubbers over macroscopic areas. Fundamental characterization of the ribbons by piezo-force microscopy indicates that their electromechanical energy conversion metrics are among the highest reported on a flexible medium. The excellent performance of the piezo-ribbon assemblies coupled with stretchable, biocompatible rubber may enable a host of exciting avenues in fundamental research and novel applications.

  12. Inter-ribbon tunneling in graphene: An atomistic Bardeen approach

    Energy Technology Data Exchange (ETDEWEB)

    Van de Put, Maarten L., E-mail: maarten.vandeput@uantwerpen.be; Magnus, Wim [Department of Physics, Universiteit Antwerpen, B-2020 Antwerpen (Belgium); imec, B-3001 Heverlee (Belgium); Vandenberghe, William G.; Fischetti, Massimo V. [Department of Material Science, University of Texas at Dallas, Texas 75080 (United States); Sorée, Bart [Department of Physics, Universiteit Antwerpen, B-2020 Antwerpen (Belgium); imec, B-3001 Heverlee (Belgium); Department of Electrical Engineering, KU Leuven, B-3001 Leuven (Belgium)

    2016-06-07

    A weakly coupled system of two crossed graphene nanoribbons exhibits direct tunneling due to the overlap of the wavefunctions of both ribbons. We apply the Bardeen transfer Hamiltonian formalism, using atomistic band structure calculations to account for the effect of the atomic structure on the tunneling process. The strong quantum-size confinement of the nanoribbons is mirrored by the one-dimensional character of the electronic structure, resulting in properties that differ significantly from the case of inter-layer tunneling, where tunneling occurs between bulk two-dimensional graphene sheets. The current-voltage characteristics of the inter-ribbon tunneling structures exhibit resonance, as well as stepwise increases in current. Both features are caused by the energetic alignment of one-dimensional peaks in the density-of-states of the ribbons. Resonant tunneling occurs if the sign of the curvature of the coupled energy bands is equal, whereas a step-like increase in the current occurs if the signs are opposite. Changing the doping modulates the onset-voltage of the effects as well as their magnitude. Doping through electrostatic gating makes these structures promising for application towards steep slope switching devices. Using the atomistic empirical pseudopotentials based Bardeen transfer Hamiltonian method, inter-ribbon tunneling can be studied for the whole range of two-dimensional materials, such as transition metal dichalcogenides. The effects of resonance and of step-like increases in the current we observe in graphene ribbons are also expected in ribbons made from these alternative two-dimensional materials, because these effects are manifestations of the one-dimensional character of the density-of-states.

  13. Intestinal cholesterol transport: Measuring cholesterol absorption and its reverse

    NARCIS (Netherlands)

    Jakulj, L.

    2013-01-01

    Intestinal cholesterol transport might serve as an attractive future target for cardiovascular disease reduction, provided that underlying molecular mechanisms are more extensively elucidated, combined with improved techniques to measure changes in cholesterol fluxes and their possible

  14. Temperature distribution study in flash-annealed amorphous ribbons

    International Nuclear Information System (INIS)

    Moron, C.; Garcia, A.; Carracedo, M.T.

    2003-01-01

    Negative magnetrostrictive amorphous ribbons have been locally current annealed with currents from 1 to 8 A and annealing times from 14 ms to 200 s. In order to obtain information about the sample temperature during flash or current annealing, a study of the temperature dispersion during annealing in amorphous ribbons was made. The local temperature variation was obtained by measuring the local intensity of the infrared emission of the sample with a CCD liquid nitrogen cooled camera. A distribution of local temperature has been found in spite of the small dimension of the sample

  15. Variation of boron concentration in metallic glass ribbons

    International Nuclear Information System (INIS)

    Nagy, A.Z.; Vasvari, B.; Bakos, L.; Duwez, P.; Bogancs, J.; Nazarov, V.M.

    1980-01-01

    The boron concentration of Fe 40 Ni 40 P 14 B 6 , Fe 32 Ni 36 Cr 14 P 12 B 6 and Fe 40 Ni 40 B 20 metallic glasses is measured by neutron activation analysis on both surfaces of the ribbon samples. It is found that the boron concentration is always higher on the bright side of the ribbon than that on the dull side which is in contact with the cold surface of the wheel during the rapid quenching from the melt. A possible explanation is given in terms of the solid-liquid interface moving rapidly from the cooled surface to the free surface when preparing the samples. (author)

  16. Hydrostatic extrusion of Cu-Ag melt spun ribbon

    Science.gov (United States)

    Hill, Mary Ann; Bingert, John F.; Bingert, Sherri A.; Thoma, Dan J.

    1998-01-01

    The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

  17. Pulling Helices inside Bacteria: Imperfect Helices and Rings

    Science.gov (United States)

    Allard, Jun F.; Rutenberg, Andrew D.

    2009-04-01

    We study steady-state configurations of intrinsically-straight elastic filaments constrained within rod-shaped bacteria that have applied forces distributed along their length. Perfect steady-state helices result from axial or azimuthal forces applied at filament ends, however azimuthal forces are required for the small pitches observed for MreB filaments within bacteria. Helix-like configurations can result from distributed forces, including coexistence between rings and imperfect helices. Levels of expression and/or bundling of the polymeric protein could mediate this coexistence.

  18. Generation Mechanisms of Quasi-parallel and Quasi-circular Flare Ribbons in a Confined Flare

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Perez, Aaron; Thalmann, Julia K.; Veronig, Astrid M.; Dickson, Ewan C. [IGAM/Institute of Physics, University of Graz, A-8010 Graz (Austria); Su, Yang [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory Chinese Academy of Sciences, 2 West Beijing Road, 210008 Nanjing (China); Gömöry, Peter, E-mail: aaron.hernandez-perez@uni-graz.at [Astronomical Institute, Slovak Academy of Sciences, 05960 Tatranská Lomnica (Slovakia)

    2017-10-01

    We analyze a confined multiple-ribbon M2.1 flare (SOL2015-01-29T11:42) that originated from a fan-spine coronal magnetic field configuration, within active region NOAA 12268. The observed ribbons form in two steps. First, two primary ribbons form at the main flare site, followed by the formation of secondary ribbons at remote locations. We observe a number of plasma flows at extreme-ultraviolet temperatures during the early phase of the flare (as early as 15 minutes before the onset) propagating toward the formation site of the secondary ribbons. The secondary ribbon formation is co-temporal with the arrival of the pre-flare generated plasma flows. The primary ribbons are co-spatial with Ramaty High Energy Spectroscopic Imager ( RHESSI ) hard X-ray sources, whereas no enhanced X-ray emission is detected at the secondary ribbon sites. The (E)UV emission, associated with the secondary ribbons, peaks ∼1 minute after the last RHESSI hard X-ray enhancement. A nonlinear force-free model of the coronal magnetic field reveals that the secondary flare ribbons are not directly connected to the primary ribbons, but to regions nearby. Detailed analysis suggests that the secondary brightenings are produced due to dissipation of kinetic energy of the plasma flows (heating due to compression), and not due to non-thermal particles accelerated by magnetic reconnection, as is the case for the primary ribbons.

  19. Transport barrier in Helical system

    International Nuclear Information System (INIS)

    Ida, Katsumi

    1998-01-01

    Experiments on the transport barrier in Helical plasmas are reviewed. There are two mechanisms of transport improvement, that results in the formation of the transport barrier. One is the improvement of neoclassical transport by reducing the ripple loss with radial electric field, which exist only in helical plasma. The other is the improvement of anomalous transport due to the suppression of fluctuations associated with a radial electric field shear both in tokamak and helical plasma. The formation of the transport barrier can be triggered by the radial electric field shear associated with the transition of the radial electric field (L/H transition or ion-electron root transition) or the peaked density or the optimization of magnetic field shear. The mechanisms of transport barrier formation are also discussed. (author). 60 refs

  20. Generalized helicity and Beltrami fields

    Energy Technology Data Exchange (ETDEWEB)

    Buniy, Roman V., E-mail: roman.buniy@gmail.com [Schmid College of Science, Chapman University, Orange, CA 92866 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom); Kephart, Thomas W., E-mail: tom.kephart@gmail.com [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Isaac Newton Institute, University of Cambridge, Cambridge, CB3 0EH (United Kingdom)

    2014-05-15

    We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy–momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang–Mills action functional 1/4 ∫{sub Ω}trF{sub μν}F{sup μν}d{sup 4}x subject to the local constraint ε{sup μναβ}trF{sub μν}F{sub αβ}=0 satisfies the covariant non-abelian Beltrami equation. -- Highlights: •We introduce the covariant non-abelian helicity and Beltrami equation. •The Yang–Mills action and instanton term constraint lead to the Beltrami equation. •Solutions of the Beltrami equation conserve helicity.

  1. Generalized helicity and Beltrami fields

    International Nuclear Information System (INIS)

    Buniy, Roman V.; Kephart, Thomas W.

    2014-01-01

    We propose covariant and non-abelian generalizations of the magnetic helicity and Beltrami equation. The gauge invariance, variational principle, conserved current, energy–momentum tensor and choice of boundary conditions elucidate the subject. In particular, we prove that any extremal of the Yang–Mills action functional 1/4 ∫ Ω trF μν F μν d 4 x subject to the local constraint ε μναβ trF μν F αβ =0 satisfies the covariant non-abelian Beltrami equation. -- Highlights: •We introduce the covariant non-abelian helicity and Beltrami equation. •The Yang–Mills action and instanton term constraint lead to the Beltrami equation. •Solutions of the Beltrami equation conserve helicity

  2. Toroidal helical quartz forming machine

    International Nuclear Information System (INIS)

    Hanks, K.W.; Cole, T.R.

    1977-01-01

    The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed

  3. Helical axis stellarator equilibrium model

    International Nuclear Information System (INIS)

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift

  4. Resonant helical fields in tokamaks

    International Nuclear Information System (INIS)

    Okano, V.

    1990-01-01

    Poincare maps of magnetic field lines of a toroidal helical system were made. The magnetic field is a linear superposition of the magnetic fields produced by a toroidal plasma in equilibrium and by external helical currents. Analytical expression for the Poincare maps was no obtained since the magnetic field do not have symmetry. In order to obtain the maps, the equation minus derivative of l vector times B vector = 0 was numerically integrated. In the Poincare maps, the principal and the secondary magnetic island were observed. (author)

  5. Helical system. History and current state of helical research

    International Nuclear Information System (INIS)

    Yokoyama, Masayuki

    2017-01-01

    This paper described the following: (1) history of nuclear fusion research of Japan's original heliotron method, (2) worldwide development of nuclear fusion research based on helical system such as stellarator, and (3) worldwide meaning of large helical device (LHD) aiming to demonstrate the steady-state performance of heliotron type in the parameter area extrapolable to the core plasma, and research results of LHD. LHD demonstrated that the helical system is excellent in steady operation performance at the world's most advanced level. In an experiment using deuterium gas in 2017, LHD achieved to reach 120 million degrees of ion temperature, which is one index of nuclear fusion condition, demonstrated the realization of high-performance plasma capable of extrapolating to future nuclear fusion reactors, and established the foundation for full-scale research toward the realization of nuclear fusion reactor. Besides experimental research, this paper also described the helical-type stationary nuclear fusion prototype reactor, FFHR-d1, which was based on progress of large-scale simulation at the world's most advanced level. A large-scale superconducting stellarator experimental device, W7-X, with the same scale as LHD, started experiment in December 2015, whose current state is also touched on here. (A.O.)

  6. Helicity and evanescent waves. [Energy transport velocity, helicity, Lorentz transformation

    Energy Technology Data Exchange (ETDEWEB)

    Agudin, J L; Platzeck, A M [La Plata Univ. Nacional (Argentina); Albano, J R [Instituto de Astronomia y Fisica del Espacio, Buenos Aires, Argentina

    1978-02-20

    It is shown that the projection of the angular momentum of a circularly polarized electromagnetic evanescent wave along the mean velocity of energy transport (=helicity) can be reverted by a Lorentz transformation, in spite of the fact that this velocity is c.

  7. Transintestinal cholesterol excretion in humans

    NARCIS (Netherlands)

    Reeskamp, Laurens F.; Meessen, Emma C. E.; Groen, Albert K.

    2018-01-01

    Purpose of review To discuss recent insights into the measurement and cellular basis of transintestinal cholesterol excretion (TICE) in humans and to explore TICE as a therapeutic target for increasing reverse cholesterol transport. Recent findings TICE is the net effect of cholesterol excretion by

  8. Characterization of consolidated rapidly solidified Cu-Nb ribbons

    International Nuclear Information System (INIS)

    Ebrahimi, F.; Henne, M.L.C.

    1997-01-01

    Copper-niobium ribbons produced by melt-spinning were compacted by swaging and consolidated using HIPping. Final processing to obtain in-situ composites was done by swaging. The strength of the composite is discussed in terms of the composition and morphology of the niobium phase as evaluated using electron microscopy techniques

  9. 38 CFR 21.9700 - Yellow Ribbon Program.

    Science.gov (United States)

    2010-07-01

    ... Yellow Ribbon Program and the student maintains satisfactory progress, conduct, and attendance according...) Based on student status (i.e. , undergraduate, graduate, doctoral), or (ii) For each subelement of the institution (i.e., college or professional school). The maximum amount specified for each subelement of the...

  10. Dosimetry of wires and single ribbons of Iridium 192

    International Nuclear Information System (INIS)

    Mazzucco, L.D.

    1998-01-01

    The objective of this work is in order to present in table formats the dosimetry of wires and single ribbons of Iridium with lengths 1-12 cm for each one linear source along the bisector which is perpendicular at tissue sources (water) computed for linear activity 1 mCi/cm in the case of wires, and 1 mCi/seed for ribbons. The above tables are of direct use, adaptable at particular cases so they facilitate logarithmic graphics of doses in function of the distance for interpolation and use in the treatments planning. It was shown that for two sources with identical linear activity and total length, one of the equidistant seeds at 1 cm (ribbon) and one wire on the other hand, the differences in dose rates in near positions can be about the 15% so corroborating that it is not possible to use wire tables for seeds neither vice versa. Moreover it was elaborated tables of practical direct use for dose rate in water at c Gy/hr for wires and Ribbons 1-12 cm length and from 0.5-10 cm of distance in the perpendicular bisector at the Iridium implant. (Author)

  11. Experimental investigation of the ribbon-array ablation process

    International Nuclear Information System (INIS)

    Li Zhenghong; Xu Rongkun; Chu Yanyun; Yang Jianlun; Xu Zeping; Ye Fan; Chen Faxin; Xue Feibiao; Ning Jiamin; Qin Yi; Meng Shijian; Hu Qingyuan; Si Fenni; Feng Jinghua; Zhang Faqiang; Chen Jinchuan; Li Linbo; Chen Dingyang; Ding Ning; Zhou Xiuwen

    2013-01-01

    Ablation processes of ribbon-array loads, as well as wire-array loads for comparison, were investigated on Qiangguang-1 accelerator. The ultraviolet framing images indicate that the ribbon-array loads have stable passages of currents, which produce axially uniform ablated plasma. The end-on x-ray framing camera observed the azimuthally modulated distribution of the early ablated ribbon-array plasma and the shrink process of the x-ray radiation region. Magnetic probes measured the total and precursor currents of ribbon-array and wire-array loads, and there exists no evident difference between the precursor currents of the two types of loads. The proportion of the precursor current to the total current is 15% to 20%, and the start time of the precursor current is about 25 ns later than that of the total current. The melting time of the load material is about 16 ns, when the inward drift velocity of the ablated plasma is taken to be 1.5 × 10 7 cm/s.

  12. Magnetoimpedance of cobalt-based amorphous ribbons/polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Semirov, A.V., E-mail: semirov@mail.ru [Irkutsk State University, Irkutsk (Russian Federation); Derevyanko, M.S.; Bukreev, D.A.; Moiseev, A.A.; Kudryavtsev, V.O. [Irkutsk State University, Irkutsk (Russian Federation); Safronov, A.P. [Ural Federal University, Yekaterinburg (Russian Federation)

    2016-10-01

    The combined influence of the temperature, the elastic tensile stress and the external magnetic field on the total impedance and impedance components were studied for rapidly quenched amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons. Both as-cast amorphous ribbons and Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16}/polymer amorphous ribbon based composites were considered. Following polymer coverings were studied: modified rubber solution in o-xylene, solution of butyl methacrylate and methacrylic acid copolymer in isopropanol and solution of polymethylphenylsiloxane resin in toluene. All selected composites showed very good adhesion of the coverings and allowed to provide temperature measurements from 163 K up to 383 K under the applied deforming tensile force up to 30 N. The dependence of the modulus of the impedance and its components on the external magnetic field was influenced by the elastic tensile stresses and was affected by the temperature of the samples. It was shown that maximal sensitivity of the impedance and its components to the external magnetic field was observed at minimal temperature and maximal deforming force depended on the frequency of an alternating current. - Highlights: • Impedance and its components of amorphous Co{sub 75}Fe{sub 5}Si{sub 4}B{sub 16} ribbons were studied. • MI sensitivity to the magnetic field depends on a temperature and a deforming force. • Polymer covering can affect the functional properties of the composite.

  13. Flare Ribbon Expansion and Energy Release Ayumi Asai , Takaaki ...

    Indian Academy of Sciences (India)

    2001-04-10

    1Nobeyama Solar Radio Observatory, Minamisaku, Nagano, 384-1305, Japan. ... X2.3 solar flare which occurred on April 10, 2001. .... In the right panel of. Fig. 3, we show the temporal variation of the physical parameters, such as Bp, vf , ˙ , and S along a slit line. Here, we defined vf as the speed of the flare-ribbon ...

  14. Structural relaxation of Ni-Si-B amorphous ribbon

    NARCIS (Netherlands)

    Jurikova, A.; Csach, K.; Miskuf, J.; Ocelik, V.

    The structural relaxation of the Ni-Si-B amorphous ribbon was studied by means of differential scanning calorimetry and thermomechanical analysis. It was shown that considerable length changes associated with reversible structural relaxation were revealed after a previous creep applied at higher

  15. Graphene: powder, flakes, ribbons, and sheets.

    Science.gov (United States)

    James, Dustin K; Tour, James M

    2013-10-15

    Graphene's unique physical and electrical properties (high tensile strength, Young's modulus, electron mobility, and thermal conductivity) have led to its nickname of "super carbon." Graphene research involves the study of several different physical forms of the material: powders, flakes, ribbons, and sheets and others not yet named or imagined. Within those forms, graphene can include a single layer, two layers, or ≤10 sheets of sp² carbon atoms. The chemistry and applications available with graphene depend on both the physical form of the graphene and the number of layers in the material. Therefore the available permutations of graphene are numerous, and we will discuss a subset of this work, covering some of our research on the synthesis and use of many of the different physical and layered forms of graphene. Initially, we worked with commercially available graphite, with which we extended diazonium chemistry developed to functionalize single-walled carbon nanotubes to produce graphitic materials. These structures were soluble in common organic solvents and were better dispersed in composites. We developed an improved synthesis of graphene oxide (GO) and explored how the workup protocol for the synthesis of GO can change the electronic structure and chemical functionality of the GO product. We also developed a method to remove graphene layers one-by-one from flakes. These powders and sheets of GO can serve as fluid loss prevention additives in drilling fluids for the oil industry. Graphene nanoribbons (GNRs) combine small width with long length, producing valuable electronic and physical properties. We developed two complementary syntheses of GNRs from multiwalled carbon nanotubes: one simple oxidative method that produces GNRs with some defects and one reductive method that produces GNRs that are less defective and more electrically conductive. These GNRs can be used in low-loss, high permittivity composites, as conductive reinforcement coatings on Kevlar

  16. The status of silicon ribbon growth technology for high-efficiency silicon solar cells

    Science.gov (United States)

    Ciszek, T. F.

    1985-01-01

    More than a dozen methods have been applied to the growth of silicon ribbons, beginning as early as 1963. The ribbon geometry has been particularly intriguing for photovoltaic applications, because it might provide large area, damage free, nearly continuous substrates without the material loss or cost of ingot wafering. In general, the efficiency of silicon ribbon solar cells has been lower than that of ingot cells. The status of some ribbon growth techniques that have achieved laboratory efficiencies greater than 13.5% are reviewed, i.e., edge-defined, film-fed growth (EFG), edge-supported pulling (ESP), ribbon against a drop (RAD), and dendritic web growth (web).

  17. Parameterization and measurements of helical magnetic fields

    International Nuclear Information System (INIS)

    Fischer, W.; Okamura, M.

    1997-01-01

    Magnetic fields with helical symmetry can be parameterized using multipole coefficients (a n , b n ). We present a parameterization that gives the familiar multipole coefficients (a n , b n ) for straight magnets when the helical wavelength tends to infinity. To measure helical fields all methods used for straight magnets can be employed. We show how to convert the results of those measurements to obtain the desired helical multipole coefficients (a n , b n )

  18. Applications of 2D helical vortex dynamics

    DEFF Research Database (Denmark)

    Okulov, Valery; Sørensen, Jens Nørkær

    2010-01-01

    In the paper, we show how the assumption of helical symmetry in the context of 2D helical vortices can be exploited to analyse and to model various cases of rotating flows. From theory, examples of three basic applications of 2D dynamics of helical vortices embedded in flows with helical symmetry...... of the vorticity field are addressed. These included some of the problems related to vortex breakdown, instability of far wakes behind rotors and vortex theory of ideal rotors....

  19. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.; Murakami, M.; England, A.C.; Wilgen, J.B.; Jaeger, E.F.; Wang, C.; Batchelor, D.B.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7-AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  20. ICRF heating on helical devices

    International Nuclear Information System (INIS)

    Rasmussen, D.A.; Lyon, J.F.; Hoffman, D.J.

    1995-01-01

    Ion cyclotron range of frequency (ICRF) heating is currently in use on CHS and W7AS and is a major element of the heating planned for steady state helical devices. In helical devices, the lack of a toroidal current eliminates both disruptions and the need for ICRF current drive, simplifying the design of antenna structures as compared to tokamak applications. However the survivability of plasma facing components and steady state cooling issues are directly applicable to tokamak devices. Results from LHD steady state experiments should be available on a time scale to strongly influence the next generation of steady state tokamak experiments. The helical plasma geometry provides challenges not faced with tokamak ICRF heating, including the potential for enhanced fast ion losses, impurity accumulation, limited access for antenna structures, and open magnetic field lines in the plasma edge. The present results and near term plans provide the basis for steady state ICRF heating of larger helical devices. An approach which includes direct electron, mode conversion, ion minority and ion Bernstein wave heating addresses these issues

  1. The helical tomotherapy thread effect

    International Nuclear Information System (INIS)

    Kissick, M.W.; Fenwick, J.; James, J.A.; Jeraj, R.; Kapatoes, J.M.; Keller, H.; Mackie, T.R.; Olivera, G.; Soisson, E.T.

    2005-01-01

    Inherent to helical tomotherapy is a dose variation pattern that manifests as a 'ripple' (peak-to-trough relative to the average). This ripple is the result of helical beam junctioning, completely unique to helical tomotherapy. Pitch is defined as in helical CT, the couch travel distance for a complete gantry rotation relative to the axial beam width at the axis of rotation. Without scattering or beam divergence, an analytical posing of the problem as a simple integral predicts minima near a pitch of 1/n where n is an integer. A convolution-superposition dose calculator (TomoTherapy, Inc.) included all the physics needed to explore the ripple magnitude versus pitch and beam width. The results of the dose calculator and some benchmark measurements demonstrate that the ripple has sharp minima near p=0.86(1/n). The 0.86 factor is empirical and caused by a beam junctioning of the off-axis dose profiles which differ from the axial profiles as well as a long scatter tail of the profiles at depth. For very strong intensity modulation, the 0.86 factor may vary. The authors propose choosing particular minima pitches or using a second delivery that starts 180 deg off-phase from the first to reduce these ripples: 'Double threading'. For current typical pitches and beam widths, however, this effect is small and not clinically important for most situations. Certain extremely large field or high pitch cases, however, may benefit from mitigation of this effect

  2. Dosimetry of wires and single ribbons of Iridium 192; Dosimetria de alambres y ribbons individuales de Iridio-192

    Energy Technology Data Exchange (ETDEWEB)

    Mazzucco, L.D. [Centro Medico Nuclear S.R.L. San Juan (Argentina)

    1998-12-31

    The objective of this work is in order to present in table formats the dosimetry of wires and single ribbons of Iridium with lengths 1-12 cm for each one linear source along the bisector which is perpendicular at tissue sources (water) computed for linear activity 1 mCi/cm in the case of wires, and 1 mCi/seed for ribbons. The above tables are of direct use, adaptable at particular cases so they facilitate logarithmic graphics of doses in function of the distance for interpolation and use in the treatments planning. It was shown that for two sources with identical linear activity and total length, one of the equidistant seeds at 1 cm (ribbon) and one wire on the other hand, the differences in dose rates in near positions can be about the 15% so corroborating that it is not possible to use wire tables for seeds neither vice versa. Moreover it was elaborated tables of practical direct use for dose rate in water at c Gy/hr for wires and Ribbons 1-12 cm length and from 0.5-10 cm of distance in the perpendicular bisector at the Iridium implant. (Author)

  3. Generalized helicity and its time derivative

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Marklin, G.J.

    1985-01-01

    Spheromaks can be sustained against resistive decay by helicity injection because they tend to obey the minimum energy principle. This principle states that a plasma-laden magnetic configuration will relax to a state of minimum energy subject to the constraint that the magnetic helicity is conserved. Use of helicity as a constraint on the minimization of energy was first proposed by Woltjer in connection with astrophysical phenomena. Helicity does decay on the resistive diffusion time. However, if helicity is created and made to flow continuoiusly into a confinement geometry, these additional linked fluxes can relax and sustain the configuration indefinitely against the resistive decay. In this paper we will present an extension of the definition of helicity to include systems where B vector can penetrate the boundary and the penetration can be varying in time. We then discuss the sustainment of RFPs and spheromaks in terms of helicity injection

  4. A helical scintillating fiber hodoscope

    CERN Document Server

    Altmeier, M; Bisplinghoff, J; Bissel, T; Bollmann, R; Busch, M; Büsser, K; Colberg, T; Demiroers, L; Diehl, O; Dohrmann, F; Engelhardt, H P; Eversheim, P D; Felden, O; Gebel, R; Glende, M; Greiff, J; Gross, A; Gross-Hardt, R; Hinterberger, F; Jahn, R; Jeske, M; Jonas, E; Krause, H; Lahr, U; Langkau, R; Lindemann, T; Lindlein, J; Maier, R; Maschuw, R; Mayer-Kuckuck, T; Meinerzhagen, A; Naehle, O; Pfuff, M; Prasuhn, D; Rohdjess, H; Rosendaal, D; Von Rossen, P; Sanz, B; Schirm, N; Schulz-Rojahn, M; Schwarz, V; Scobel, W; Thomas, S; Trelle, H J; Weise, E; Wellinghausen, A; Wiedmann, W; Woller, K; Ziegler, R

    1999-01-01

    A novel scintillating fiber hodoscope in helically cylindric geometry has been developed for detection of low multiplicity events of fast protons and other light charged particles in the internal target experiment EDDA at the Cooler Synchrotron COSY. The hodoscope consists of 640 scintillating fibers (2.5 mm diameter), arranged in four layers surrounding the COSY beam pipe. The fibers are helically wound in opposing directions and read out individually using 16-channel photomultipliers connected to a modified commercial encoding system. The detector covers an angular range of 9 deg. <= THETA<=72 deg. and 0 deg. <=phi (cursive,open) Greek<=360 deg. in the lab frame. The detector length is 590 mm, the inner diameter 161 mm. Geometry and granularity of the hodoscope afford a position resolution of about 1.3 mm. The detector design took into consideration a maximum of reliability and a minimum of maintenance. An LED array may be used for monitoring purposes. (author)

  5. Helical CT of ureteral disease

    International Nuclear Information System (INIS)

    Cikman, Pablo; Bengio, Ruben; Bulacio, Javier; Zirulnik, Esteban; Garimaldi, Jorge

    2000-01-01

    Among the new applications of helical CT is the study of the ureteral pathology. The objective of this paper was to evaluate patients with suspected pathology of this organ and the repercussion in the therapeutic plans. We studied 23 patients with a helical CT protocol, without IV contrast injection and performed multiplanar reconstruction (MPR). We called this procedure Pielo CT. Thirteen ureteral stones were detected, 6 calculi, 2 urinary tract tumors, dilatation of the system in a patient with neo-bladder. In 2 patients, in whom ureteral pathology was ruled out, we found other alterations that explained the symptoms, (gallbladder stones, disk protrusion). The Pielo CT let decide a therapeutical approach in 20 or 21 patients with ureteral pathology. (author)

  6. Characterization of placental cholesterol transport

    DEFF Research Database (Denmark)

    Lindegaard, Marie L; Wassif, Christopher A; Vaisman, Boris

    2008-01-01

    Patients with Smith-Lemli-Opitz syndrome (SLOS) are born with multiple congenital abnormalities. Postnatal cholesterol supplementation is provided; however, it cannot correct developmental malformations due to in utero cholesterol deficit. Increased transport of cholesterol from maternal to fetal...... circulation might attenuate congenital malformations. The cholesterol transporters Abca1, Abcg1, and Sr-b1 are present in placenta; however, their potential role in placental transport remains undetermined. In mice, expression analyses showed that Abca1 and Abcg1 transcripts increased 2-3-fold between...... embryonic days 13.5 and 18.5 in placental tissue; whereas, Sr-b1 expression decreased. To examine the functional role of Abca1, Abcg1 and Sr-b1 we measured the maternal-fetal transfer of (14)C-cholesterol in corresponding mutant embryos. Disruption of either Abca1 or Sr-b1 decreased cholesterol transfer...

  7. Helicity formalism and spin effects

    International Nuclear Information System (INIS)

    Anselmino, M.; Caruso, F.; Piovano, U.

    1990-01-01

    The helicity formalism and the technique to compute amplitudes for interaction processes involving leptons, quarks, photons and gluons are reviewed. Explicit calculations and examples of exploitation of symmetry properties are shown. The formalism is then applied to the discussion of several hadronic processes and spin effects: the experimental data, when related to the properties of the elementary constituent interactions, show many not understood features. Also the nucleon spin problem is briefly reviewed. (author)

  8. Radiation characteristics of helical tomotherapy

    International Nuclear Information System (INIS)

    Jeraj, Robert; Mackie, Thomas R.; Balog, John; Olivera, Gustavo; Pearson, Dave; Kapatoes, Jeff; Ruchala, Ken; Reckwerdt, Paul

    2004-01-01

    Helical tomotherapy is a dedicated intensity modulated radiation therapy (IMRT) system with on-board imaging capability (MVCT) and therefore differs from conventional treatment units. Different design goals resulted in some distinctive radiation field characteristics. The most significant differences in the design are the lack of flattening filter, increased shielding of the collimators, treatment and imaging operation modes and narrow fan beam delivery. Radiation characteristics of the helical tomotherapy system, sensitivity studies of various incident electron beam parameters and radiation safety analyses are presented here. It was determined that the photon beam energy spectrum of helical tomotherapy is similar to that of more conventional radiation treatment units. The two operational modes of the system result in different nominal energies of the incident electron beam with approximately 6 MeV and 3.5 MeV in the treatment and imaging modes, respectively. The off-axis mean energy dependence is much lower than in conventional radiotherapy units with less than 5% variation across the field, which is the consequence of the absent flattening filter. For the same reason the transverse profile exhibits the characteristic conical shape resulting in a 2-fold increase of the beam intensity in the center. The radiation leakage outside the field was found to be negligible at less than 0.05% because of the increased shielding of the collimators. At this level the in-field scattering is a dominant source of the radiation outside the field and thus a narrow field treatment does not result in the increased leakage. The sensitivity studies showed increased sensitivity on the incident electron position because of the narrow fan beam delivery and high sensitivity on the incident electron energy, as common to other treatment systems. All in all, it was determined that helical tomotherapy is a system with some unique radiation characteristics, which have been to a large extent

  9. Sterol biosynthesis from acetate and the fate of dietary cholesterol and desmosterol in crabs

    International Nuclear Information System (INIS)

    Teshima, Shin-ichi; Kanazawa, Akio; Okamoto, Haruhito

    1976-01-01

    This paper deals with the sterol-synthesizing ability and the fate of dietary sterols, cholesterol and desmosterol, in the crabs, Sesarma dehaani and Helice tridens. Injected acetate-1- 14 C was not incorporated into either squalene or sterols in the above crabs. This suggested that the sterol-synthesizing ability from acetate is absent or weak in the crabs, S. dehaani and H. tridens. The apparent percentage absorptions of dietary cholesterol and desmosterol from the digestive tracts were 91.9 and 90.9, respectively. The ingested cholesterol and desmosterol were metabolized to steryl esters and polar compounds but only slightly to water-soluble sterols. Also, it was shown that the crab, S. dehaani, is capable of converting desmosterol to cholesterol. (auth.)

  10. Transverse magnetization and giant magnetoimpedance in amorphous ribbons

    International Nuclear Information System (INIS)

    Orue, I.; Garcia-Arribas, A.; Saad, A.; Cos, D. de; Barandiaran, J.M.

    2005-01-01

    In the classical approach giant magnetoimpedance (GMI) is driven by the transverse permeability of the sample, as excited by the current flowing through it. Transverse permeability is usually taken as a constant, while detailed magnetization processes are important for the interpretation of GMI data. In most cases the transverse permeability (or magnetization) is only guessed by looking at the longitudinal magnetization curve and direct determinations of such parameter are scarce in the literature. In this work we report on the operation of a simple setup which provides the transverse magnetization of amorphous ribbons as a function of the current intensity flowing through it, by means of the magnetooptical kerr effect (MOKE). The system has been tested on low magnetostriction amorphous ribbons of very soft character with both longitudinal and transverse anisotropy. The transverse magnetization as a function of both the current and a DC longitudinal field applied, was compared with magneto impedance measurements

  11. Device for investigation of magnetic flux jumps in ribbon superconductors

    International Nuclear Information System (INIS)

    Andrianov, A.V.; Bashkirov, Yu.A.; Kremlev, M.G.

    1986-01-01

    A device for simulation of magnetic flux jumps in superconductors of conducting magnet sandwich-type windings super-applyed of a ribbon conductor is described. A superconducting magnet with a measuring cassetter are the main elements of the device. An external magnetic field is generated by a two-sectional superconducting magnet permitting to simulate the shape of the magnetic field characteristic for sandwich-type windings. Maximum radial component of the magnetic field is 2 T. Jumps of the magnetic flux are recorded by induction transducers and the magnetic field-by Hall trasducer. The effect of coating of standard metal on magnetic flux jumps in Nb 3 Sn base superconducting ribbon is considered

  12. Variation of boron concentration in metallic glass ribbons

    International Nuclear Information System (INIS)

    Nagy, A.Z.; Vasvari, B.; Duwez, P.; Bakos, L.; Seres, Z.; Bogancs, J.; Nazarov, V.M.

    1979-12-01

    The surface boron concentration of Fe 40 Ni 40 P 14 B 6 , Fe 32 Ni 36 Cr 14 P 12 B 6 and Fe 40 Ni 40 B 20 metallic glasses was measured by neutron activation analysis on both sides of the ribbon samples. It was found that the boron concentration is always higher at the bright side of the ribbon than that at the dull side which is in contact with the cold surface of the wheel during the rapid quenching from the melt. A possible explanation is given in terms of the solid-liquid interface moving rapidly from the cooled surface to the free surface when preparing the samples. Range values of alpha-particles for some characteristic compositions of metallic glasses are tabulated. A mathematical technique for the deconvolution of experimental data is described and the listing of the Fortran program is enclosed. (author)

  13. Helical Antimicrobial Sulfono- {gamma} -AApeptides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaqiong; Wu, Haifan; Teng, Peng; Bai, Ge; Lin, Xiaoyang; Zuo, Xiaobing; Cao, Chuanhai; Cai, Jianfeng

    2015-06-11

    Host-defense peptides (HDPs) such as magainin 2 have emerged as potential therapeutic agents combating antibiotic resistance. Inspired by their structures and mechanism of action, herein we report the fi rst example of antimicrobial helical sulfono- γ - AApeptide foldamers. The lead molecule displays broad-spectrum and potent antimicrobial activity against multi-drug-resistant Gram- positive and Gram-negative bacterial pathogens. Time-kill studies and fl uorescence microscopy suggest that sulfono- γ -AApeptides eradicate bacteria by taking a mode of action analogous to that of HDPs. Clear structure - function relationships exist in the studied sequences. Longer sequences, presumably adopting more-de fi ned helical structures, are more potent than shorter ones. Interestingly, the sequence with less helical propensity in solution could be more selective than the stronger helix-forming sequences. Moreover, this class of antimicrobial agents are resistant to proteolytic degradation. These results may lead to the development of a new class of antimicrobial foldamers combating emerging antibiotic-resistant pathogens.

  14. HOOKED FLARE RIBBONS AND FLUX-ROPE-RELATED QSL FOOTPRINTS

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jie; Li, Hui [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, CAS, Nanjing 210008 (China); Gilchrist, Stuart A.; Aulanier, Guillaume; Schmieder, Brigitte; Pariat, Etienne, E-mail: nj.lihui@pmo.ac.cn [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris-Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, F-92195 Meudon (France)

    2016-05-20

    We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory /Atmospheric Imaging Assembly can be well reproduced from a Grad–Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surface currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad–Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.

  15. HOOKED FLARE RIBBONS AND FLUX-ROPE-RELATED QSL FOOTPRINTS

    International Nuclear Information System (INIS)

    Zhao, Jie; Li, Hui; Gilchrist, Stuart A.; Aulanier, Guillaume; Schmieder, Brigitte; Pariat, Etienne

    2016-01-01

    We studied the magnetic topology of active region 12158 on 2014 September 10 and compared it with the observations before and early in the flare that begins at 17:21 UT (SOL2014-09-10T17:45:00). Our results show that the sigmoidal structure and flare ribbons of this active region observed by the Solar Dynamics Observatory /Atmospheric Imaging Assembly can be well reproduced from a Grad–Rubin nonlinear force-free field extrapolation method. Various inverse-S- and inverse-J-shaped magnetic field lines, which surround a coronal flux rope, coincide with the sigmoid as observed in different extreme-ultraviolet wavelengths, including its multithreaded curved ends. Also, the observed distribution of surface currents in the magnetic polarity where it was not prescribed is well reproduced. This validates our numerical implementation and setup of the Grad–Rubin method. The modeled double inverse-J-shaped quasi-separatrix layer (QSL) footprints match the observed flare ribbons during the rising phase of the flare, including their hooked parts. The spiral-like shape of the latter may be related to a complex pre-eruptive flux rope with more than one turn of twist, as obtained in the model. These ribbon-associated flux-rope QSL footprints are consistent with the new standard flare model in 3D, with the presence of a hyperbolic flux tube located below an inverse-teardrop-shaped coronal QSL. This is a new step forward forecasting the locations of reconnection and ribbons in solar flares and the geometrical properties of eruptive flux ropes.

  16. Broadband magnetic losses of nanocrystalline ribbons and powder cores

    Energy Technology Data Exchange (ETDEWEB)

    Beatrice, Cinzia, E-mail: c.beatrice@inrim.it [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy); Dobák, Samuel [Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice (Slovakia); Ferrara, Enzo; Fiorillo, Fausto [Istituto Nazionale di Ricerca Metrologica, Nanoscience and Materials Division, Torino (Italy); Ragusa, Carlo [Politecnico di Torino, Energy Department, Torino (Italy); Füzer, Ján; Kollár, Peter [Institute of Physics, Faculty of Science, P.J. Šafárik University, Košice (Slovakia)

    2016-12-15

    Finemet type alloys have been investigated from DC to 1 GHz at different induction levels upon different treatments: as amorphous precursors, as ribbons nanocrystallized with and without an applied saturating field, as consolidated powders. The lowest energy losses at all frequencies and maximum Snoek's product are exhibited by the transversally field-annealed ribbons. This is understood in terms of rotation-dominated magnetization process in the low-anisotropy material. Intergrain eddy currents are responsible for the fast increase of the losses with frequency and for early permeability relaxation of the powder cores. Evidence for resonant phenomena at high frequencies and for the ensuing inadequate role of the static magnetic constitutive equation of the material in solving the magnetization dynamics via the Maxwell's diffusion equation of the electromagnetic field is provided. It is demonstrated that, by taking the Landau–Lifshitz–Gilbert equation as a constitutive relation, the excellent frequency response of the transverse anisotropy ribbons can be described by analytical method.

  17. Magnetic helicity and active filament configuration

    Science.gov (United States)

    Romano, P.; Zuccarello, F.; Poedts, S.; Soenen, A.; Zuccarello, F. P.

    2009-11-01

    Context: The role of magnetic helicity in active filament formation and destabilization is still under debate. Aims: Although active filaments usually show a sigmoid shape and a twisted configuration before and during their eruption, it is unclear which mechanism leads to these topologies. In order to provide an observational contribution to clarify these issues, we describe a filament evolution whose characteristics seem to be directly linked to the magnetic helicity transport in corona. Methods: We applied different methods to determine the helicity sign and the chirality of the filament magnetic field. We also computed the magnetic helicity transport rate at the filament footpoints. Results: All the observational signatures provided information on the positive helicity and sinistral chirality of the flux rope containing the filament material: its forward S shape, the orientation of its barbs, the bright and dark threads at 195 Å. Moreover, the magnetic helicity transport rate at the filament footpoints showed a clear accumulation of positive helicity. Conclusions: The study of this event showed a correspondence between several signatures of the sinistral chirality of the filament and several evidences of the positive magnetic helicity of the filament magnetic field. We also found that the magnetic helicity transported along the filament footpoints showed an increase just before the change of the filament shape observed in Hα images. We argued that the photospheric regions where the filament was rooted might be the preferential ways where the magnetic helicity was injected along the filament itself and where the conditions to trigger the eruption were yielded.

  18. Structure of N-Terminal Domain of NPC1 Reveals Distinct Subdomains for Binding and Transfer of Cholesterol

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyock Joo; Abi-Mosleh, Lina; Wang, Michael L.; Deisenhofer, Johann; Goldstein, Joseph L.; Brown, Michael S.; Infante, Rodney E.; (UTSMC)

    2010-09-21

    LDL delivers cholesterol to lysosomes by receptor-mediated endocytosis. Exit of cholesterol from lysosomes requires two proteins, membrane-bound Niemann-Pick C1 (NPC1) and soluble NPC2. NPC2 binds cholesterol with its isooctyl side chain buried and its 3{beta}-hydroxyl exposed. Here, we describe high-resolution structures of the N-terminal domain (NTD) of NPC1 and complexes with cholesterol and 25-hydroxycholesterol. NPC1(NTD) binds cholesterol in an orientation opposite to NPC2: 3{beta}-hydroxyl buried and isooctyl side chain exposed. Cholesterol transfer from NPC2 to NPC1(NTD) requires reorientation of a helical subdomain in NPC1(NTD), enlarging the opening for cholesterol entry. NPC1 with point mutations in this subdomain (distinct from the binding subdomain) cannot accept cholesterol from NPC2 and cannot restore cholesterol exit from lysosomes in NPC1-deficient cells. We propose a working model wherein after lysosomal hydrolysis of LDL-cholesteryl esters, cholesterol binds NPC2, which transfers it to NPC1(NTD), reversing its orientation and allowing insertion of its isooctyl side chain into the outer lysosomal membranes.

  19. New formulae for magnetic relative helicity and field line helicity

    Science.gov (United States)

    Aly, Jean-Jacques

    2018-01-01

    We consider a magnetic field {B} occupying the simply connected domain D and having all its field lines tied to the boundary S of D. We assume here that {B} has a simple topology, i.e., the mapping {M} from positive to negative polarity areas of S associating to each other the two footpoints of any magnetic line, is continuous. We first present new formulae for the helicity H of {B} relative to a reference field {{B}}r having the same normal component {B}n on S, and for its field line helicity h relative to a reference vector potential {{C}}r of {{B}}r. These formulae make immediately apparent the well known invariance of these quantities under all the ideal MHD deformations that preserve the positions of the footpoints on S. They express indeed h and H either in terms of {M} and {B}n, or in terms of the values on S of a pair of Euler potentials of {B}. We next show that, for a specific choice of {{C}}r, the field line helicity h of {B} fully characterizes the magnetic mapping {M} and then the topology of the lines. Finally, we give a formula that describes the rate of change of h in a situation where the plasma moves on the perfectly conducting boundary S without changing {B}n and/or non-ideal processes, described by an unspecified term {N} in Ohm’s law, are at work in some parts of D.

  20. HDL cholesterol: atherosclerosis and beyond

    NARCIS (Netherlands)

    Bochem, A.E.

    2013-01-01

    Cardiovascular disease (CVD) is the leading cause of death in the Western world. Myocardial infarction and stroke are the result of a compromised blood flow which may result from cholesterol accumulation in the vessel wall due to high plasma levels of LDL cholesterol. High plasma levels of HDL

  1. MHD stability analysis of helical system plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yuji

    2000-01-01

    Several topics of the MHD stability studies in helical system plasmas are reviewed with respect to the linear and ideal modes mainly. Difference of the method of the MHD stability analysis in helical system plasmas from that in tokamak plasmas is emphasized. Lack of the cyclic (symmetric) coordinate makes an analysis more difficult. Recent topic about TAE modes in a helical system is also described briefly. (author)

  2. Employing helicity amplitudes for resummation in SCET

    International Nuclear Information System (INIS)

    Moult, Ian; Stewart, Iain W.; Tackmann, Frank J.; Waalewijn, Wouter J.; Nikhef, Amsterdam

    2016-05-01

    Helicity amplitudes are the fundamental ingredients of many QCD calculations for multi-leg processes. We describe how these can seamlessly be combined with resummation in Soft-Collinear Effective Theory (SCET), by constructing a helicity operator basis for which the Wilson coefficients are directly given in terms of color-ordered helicity amplitudes. This basis is crossing symmetric and has simple transformation properties under discrete symmetries.

  3. Damping of the domain walls motion in Co-based amorphous ribbons with helical magnetic anisotropy: Part III

    International Nuclear Information System (INIS)

    Zhmetko, D.N.; Zhmetko, S.D.

    2009-01-01

    The damping of the motion of domain walls of a sandwich domain structure by the eddy currents magnetic fields, the stray fields and the hysteresis friction fields is investigated. The blocking of the motion of domain walls by the eddy currents magnetic fields is discovered.

  4. What Are High Blood Cholesterol and Triglycerides?

    Science.gov (United States)

    ... Reduction Cholesterol What Are High Blood Cholesterol and Triglycerides? Cholesterol travels to the body’s cells through the ... doctor about medicines that can help. What are triglycerides? Triglycerides are the most common type of fat ...

  5. A double perturbation method of postbuckling analysis in 2D curved beams for assembly of 3D ribbon-shaped structures

    Science.gov (United States)

    Fan, Zhichao; Hwang, Keh-Chih; Rogers, John A.; Huang, Yonggang; Zhang, Yihui

    2018-02-01

    Mechanically-guided 3D assembly based on controlled, compressive buckling represents a promising, emerging approach for forming complex 3D mesostructures in advanced materials. Due to the versatile applicability to a broad set of material types (including device-grade single-crystal silicon) over length scales from nanometers to centimeters, a wide range of novel applications have been demonstrated in soft electronic systems, interactive bio-interfaces as well as tunable electromagnetic devices. Previously reported 3D designs relied mainly on finite element analyses (FEA) as a guide, but the massive numerical simulations and computational efforts necessary to obtain the assembly parameters for a targeted 3D geometry prevent rapid exploration of engineering options. A systematic understanding of the relationship between a 3D shape and the associated parameters for assembly requires the development of a general theory for the postbuckling process. In this paper, a double perturbation method is established for the postbuckling analyses of planar curved beams, of direct relevance to the assembly of ribbon-shaped 3D mesostructures. By introducing two perturbation parameters related to the initial configuration and the deformation, the highly nonlinear governing equations can be transformed into a series of solvable, linear equations that give analytic solutions to the displacements and curvatures during postbuckling. Systematic analyses of postbuckling in three representative ribbon shapes (sinusoidal, polynomial and arc configurations) illustrate the validity of theoretical method, through comparisons to the results of experiment and FEA. These results shed light on the relationship between the important deformation quantities (e.g., mode ratio and maximum strain) and the assembly parameters (e.g., initial configuration and the applied strain). This double perturbation method provides an attractive route to the inverse design of ribbon-shaped 3D geometries, as

  6. C9/12 Ribbon-Like Structures in Hybrid Peptides Alternating α- and Thiazole-Based γ-Amino Acids.

    Science.gov (United States)

    Bonnel, Clément; Legrand, Baptiste; Simon, Matthieu; Martinez, Jean; Bantignies, Jean-Louis; Kang, Young Kee; Wenger, Emmanuel; Hoh, Francois; Masurier, Nicolas; Maillard, Ludovic T

    2017-12-11

    According to their restricted conformational freedom, heterocyclic γ-amino acids are usually considered to be related to Z-vinylogous γ-amino acids. In this context, oligomers alternating α-amino acids and thiazole-based γ-amino acids (ATCs) were expected to fold into a canonical 12-helical shape as described for α/γ-hybrid peptides composed of cis-α/β-unsaturated γ-amino acids. However, through a combination of X-ray crystallography, NMR spectroscopy, FTIR experiments, and DFT calculations, it was determined that the folding behavior of ATC-containing hybrid peptides is much more complex. The homochiral α/(S)-ATC sequences were unable to adopt a stable conformation, whereas the heterochiral α/(R)-ATC peptides displayed novel ribbon structures stabilized by unusual C 9/12 -bifurcated hydrogen bonds. These ribbon structures could be considered as a succession of pre-organized γ/α dipeptides and may provide the basis for designing original α-helix mimics. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Cholesterol Perturbs Lipid Bilayers Nonuniversally

    International Nuclear Information System (INIS)

    Pan Jianjun; Mills, Thalia T.; Tristram-Nagle, Stephanie; Nagle, John F.

    2008-01-01

    Cholesterol is well known to modulate the physical properties of biomembranes. Using modern x-ray scattering methods, we have studied the effects of cholesterol on the bending modulus K C , the thickness D HH , and the orientational order parameter S xray of lipid bilayers. We find that the effects are different for at least three classes of phospholipids characterized by different numbers of saturated hydrocarbon chains. Most strikingly, cholesterol strongly increases K C when both chains of the phospholipid are fully saturated but not at all when there are two monounsaturated chains

  8. Dietary and biliary cholesterol absorption in rats. Effect of dietary cholesterol level and cholesterol saturation of bile

    International Nuclear Information System (INIS)

    Wilson, M.D.

    1985-01-01

    The principal objective of this research was to determine if cholesterol introduced into the duodenum of rats in a micellar form as occurs with bile, is absorbed more efficiently than cholesterol presented in a nonmicellar form, as occurs with dietary cholesterol. Cholesterol absorption was measured during the constant intraduodenal infusion of liquid diets ([ 14 C] cholesterol) and artificial biles ([ 3 H] cholesterol) in thoracic lymph duct cannulated rats. Percentage absorption was calculated by dividing the rate of appearance of radiolabeled cholesterol in lymph by its rate of infusion when lymph cholesterol specific activity was constant. Results provide strong evidence that under certain conditions biliary cholesterol is more efficiently absorbed than is dietary cholesterol, and that this differential must be considered when evaluating the influence of diet or drug therapy on cholesterol absorption

  9. Random anisotropy studies in amorphous Co-Tb ribbons

    International Nuclear Information System (INIS)

    Hassanain, N.; Berrada, A.; Lassri, H.; Krishnan, R.

    1995-01-01

    Amorphous Co 1-x Tb x ribbons with x=0.45, 0.55 and 0.65 have been prepared by melt spinning technique. Magnetization measurements were carried out at 4.2 K, under magnetic fields up to 150 kOe. The Co moment is found to be very small and the Tb moment is 7.15μ B at 4.2 K, which indicates a speromagnetic spin structure. Using Chudnovsky's theory we have extracted some fundamental magnetic parameters. ((orig.))

  10. Random anisotropy studies in amorphous CoTb ribbons

    Science.gov (United States)

    Hassanain, N.; Berrada, A.; Lassri, H.; Krishnan, R.

    1995-02-01

    Amorphous Co 1- xTb x ribbons with x = 0.45, 0.55 and 0.65 have been prepared by melt spinning technique. Magnetization measurements were carried out at 4.2 K, under magnetic fields up to 150 kOe. The Co moment is found to be very small and the Tb moment is 7.15 μB at 4.2 K, which indicates a speromagnetic spin structure. Using Chudnovsky's theory we have extracted some fundamental magnetic parameters.

  11. The mechanics of Ribbons and Möbius bands

    CERN Document Server

    Fried, Eliot

    2016-01-01

    Recent developments in biology and nanotechnology have stimulated a rapidly growing interest in the mechanics of thin, flexible ribbons and Mobius bands. This edited volume contains English translations of four seminal papers on this topic, all originally written in German; of these, Michael A. Sadowsky published the first in 1929, followed by two others in 1930, and Walter Wunderlich published the last in 1962. The volume also contains invited, peer-reviewed, original research articles on related topics. Previously published in the Journal of Elasticity, Volume 119, Issue 1-2, 2015.

  12. Mammalian Cochlear Hair Cell Regeneration and Ribbon Synapse Reformation

    Directory of Open Access Journals (Sweden)

    Xiaoling Lu

    2016-01-01

    Full Text Available Hair cells (HCs are the sensory preceptor cells in the inner ear, which play an important role in hearing and balance. The HCs of organ of Corti are susceptible to noise, ototoxic drugs, and infections, thus resulting in permanent hearing loss. Recent approaches of HCs regeneration provide new directions for finding the treatment of sensor neural deafness. To have normal hearing function, the regenerated HCs must be reinnervated by nerve fibers and reform ribbon synapse with the dendrite of spiral ganglion neuron through nerve regeneration. In this review, we discuss the research progress in HC regeneration, the synaptic plasticity, and the reinnervation of new regenerated HCs in mammalian inner ear.

  13. Magnetoband structures of AB-stacked zigzag nanographite ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.P.; Chiu, C.W.; Shyu, F.L.; Chen, R.B.; Lin, M.F

    2002-12-30

    Magnetoband structures of AB-stacked zigzag nanographite ribbons are studied by the tight-binding model. The magnetic field changes band width, energy space, and energy dispersions (the produce of Landau subbands and Landau levels). It causes many zero energy points. Such points and corresponding localized states are studied in detail. There are certain important differences between localized states and edge states. Oscillation period of Landau subbands are determined by these points. The interribbon interactions also affect magnetoband structures, such as energy dispersions, band width, oscillation period of Landau subbands, and flux dependence of Hofstadter butterflies.

  14. Beta-helical polymers from isocyanopeptides

    NARCIS (Netherlands)

    Cornelissen, J.J.L.M.; Donners, J.J.J.M.; Gelder, de R.; Graswinckel, W.S.; Metselaar, G.A.; Rowan, A.E.; Sommerdijk, N.A.J.M.; Nolte, R.J.M.

    2001-01-01

    Polymerization of isocyanopeptides results in the formation of high molecular mass polymers that fold in a proteinlike fashion to give helical strands in which the peptide chains are arranged in ß-sheets. The ß-helical polymers retain their structure in water and unfold in a cooperative process at

  15. Magnetic islands created by resonant helical windings

    International Nuclear Information System (INIS)

    Fernandes, A.S.; Heller, M.V.; Caldas, I.L.

    1986-01-01

    The triggering of disruptive instabilities by resonant helical windings in large aspect-ratio tokamaks is associated to destruction of magnetic surfaces. The Chirikov condition is applied to estimate analytically the helical winding current thresholds for ergodization of the magnetic field lines. (Autor) [pt

  16. Helicity amplitudes for matter-coupled gravity

    International Nuclear Information System (INIS)

    Aldrovandi, R.; Novaes, S.F.; Spehler, D.

    1992-07-01

    The Weyl-van der Waerden spinor formalism is applied to the evaluation of helicity invariant amplitudes in the framework of linearized gravitation. The graviton couplings to spin-0, 1 - 2 , 1, and 3 - 2 particles are given, and, to exhibit the reach of this method, the helicity amplitudes for the process electron + positron → photon + graviton are obtained. (author)

  17. Stiffness versus architecture of single helical polyisocyanopeptides

    NARCIS (Netherlands)

    Buul, van A.M.; Schwartz, E.; Brocorens, P.; Koepf, M.; Beljonne, D.; Maan, J.C.; Christianen, P.C.M.; Kouwer, P.H.J.; Nolte, R.J.M.; Engelkamp, H.; Blank, K.; Rowan, A.E.

    2013-01-01

    Helical structures play a vital role in nature, offering mechanical rigidity, chirality and structural definition to biological systems. Little is known about the influence of the helical architecture on the intrinsic properties of polymers. Here, we offer an insight into the nano architecture of

  18. Dynamics of zonal flows in helical systems.

    Science.gov (United States)

    Sugama, H; Watanabe, T-H

    2005-03-25

    A theory for describing collisionless long-time behavior of zonal flows in helical systems is presented and its validity is verified by gyrokinetic-Vlasov simulation. It is shown that, under the influence of particles trapped in helical ripples, the response of zonal flows to a given source becomes weaker for lower radial wave numbers and deeper helical ripples while a high-level zonal-flow response, which is not affected by helical-ripple-trapped particles, can be maintained for a longer time by reducing their bounce-averaged radial drift velocity. This implies a possibility that helical configurations optimized for reducing neoclassical ripple transport can simultaneously enhance zonal flows which lower anomalous transport.

  19. Universal method for opnimal design main structural assemblies of steel structures stationary conveyor with hanging ribbon

    Directory of Open Access Journals (Sweden)

    Boslovyak P.V.

    2015-10-01

    Full Text Available The technique and the detailed algorithm for optimal design of steel structures hospitaltion of the conveyor with hang-ing ribbon. Developed a universal objective function together with the system-limited-subject to limits of main components of steel structures of stationary conveyor with hanging ribbon.

  20. The sandwich domain structure in a Fe-based amorphous ribbon with uniaxial magnetic anisotropy

    International Nuclear Information System (INIS)

    Zhmetko, D.N.; Matsura, A.V.; Troschenkov, Y.N.; Seidametov, S.V.

    2011-01-01

    The formation and motion of two domain walls parallel to the ribbon surface are discovered during its dynamic magnetic reversal. The domain walls form near by the middle plane of a ribbon and move to its opposite main surfaces with different velocities.

  1. Test results of Nb3Sn ribbons for the Princeton D coil test program

    International Nuclear Information System (INIS)

    Kaugerts, J.; File, J.; Willard, J.W.

    1974-10-01

    A previously described D coil test program was modified. Details of a smaller Nb 3 Sn D coil test program are described. Cusp coil tests were made with several Nb 3 Sn composite ribbons. Measurements of both the quench and recovery currents as a function of magnetic field component perpendicular to the wide edge of the ribbon are presented. (auth)

  2. 77 FR 32938 - Narrow Woven Ribbons With Woven Selvedge From Taiwan: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2012-06-04

    ... ribbons subject to the order include all narrow woven fabrics, tapes, and labels that fall within this... the manufacture of typewriter or printer ribbons; (5) Narrow woven labels and apparel tapes, cut-to... 1994 U.S.C.C.A.N. 4040, 4198-99. Furthermore, ``affirmative evidence of bad faith on the part of a...

  3. The ribbon microphone: A teaching aid for low frequency electromagnetic education

    CSIR Research Space (South Africa)

    Van Wyk, Marius S

    2017-09-01

    Full Text Available The ribbon microphone lends itself as a good example to use for education of multi-physics computer modeling and simulation. The value of the ribbon microphone as teaching aid can be extended by adding a transformer and electronic amplifier...

  4. 76 FR 38648 - Availability of the Geothermal Technologies Program Blue Ribbon Panel Report and Request for...

    Science.gov (United States)

    2011-07-01

    ....S. has lagged that of solar and wind energy. The purpose of the Blue Ribbon Panel meeting was to... Geothermal Technologies Program Blue Ribbon Panel Report and Request for Public Comment AGENCY: Office of... Panel (the Panel) on March 22/23, 2011 in Albuquerque, New Mexico for a guided discussion on the future...

  5. Imaging appearances of cholesterol pneumonia

    International Nuclear Information System (INIS)

    Miao Yanwei; Zhang Jingwen; Wu Jianlin; Zhou Yong; Li Mingwu; Lei Zhen; Shi Lifu

    2006-01-01

    Objection: To analyze the imaging appearances of cholesterol pneumonia. Methods We retrospectively analyzed the X-ray and CT findings of 3 patients with cholesterol pneumonia confirmed pathologically and reviewed correlative literature. Results: Lesions similar to mass were found in X-ray and CT imaging of three cases. Two of them appeared cavity with fluid-level and one showed multiple ring enhancement after CT contrast. The course of disease was very. long and it had no respond to antibiotic therapy. Amounts of foam cells rich in cholesterol crystal were detected in pathological examination. Conclusions: Cholesterol pneumonia is a rare chronic pulmonary idiopathic disease, and the radiological findings can do some help to its diagnosis. (authors)

  6. Beta-glucans and cholesterol

    Czech Academy of Sciences Publication Activity Database

    Šíma, Petr; Vannucci, Luca; Větvička, V.

    2017-01-01

    Roč. 41, č. 4 (2017), s. 1799-1808 ISSN 1107-3756 Institutional support: RVO:61388971 Keywords : cholesterol * beta-glucans * diet Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 2.341, year: 2016

  7. to HDL-cholesterol functionality

    Directory of Open Access Journals (Sweden)

    Malara Marzena

    2016-05-01

    Full Text Available The purpose of this study was to analyse the scientific evidence concerning the effects of two enzymes – paraoxonase 1 and myeloperoxidase – on the functions of HDL-cholesterol. It is well documented that disturbed circulating lipoproteins (a high total and high LDL-cholesterol, and low HDL-cholesterol bring about atherosclerosis and an increased risk of cardiovascular disease (CVD which is recognised as the main cause of death all around the world. In consequence, numerous studies have focused on procedures which will improve the plasma lipoproteins profile by decreasing the total cholesterol and the LDL-cholesterol (LDL-C and increasing the HDL-cholesterol (HDL-C. However, the anti-atherogenic role of HDL-C has been challenged in studies showing that genetically elevated HDL-cholesterol does not offer protection against CVD. Moreover, it has been found that raising the circulating HDL-cholesterol fails to reduce atherosclerosis. The doubts concerning the protective role of HDL-C have been supported by in vitro studies which indicate that the HDL-C from patients with atherosclerosis does not have a protective action, but does stimulate inflammation and free radical synthesis. The above data suggests that HDL-C, commonly recognised as protective against atherosclerosis, in some circumstances becomes pro-atherogenic, and is thus dysfunctional. Our review focuses on two enzymes – paraoxonase 1 (PON1 and myeloperoxidase (MPO – which markedly affect the properties of HDL-C and contribute to its anti – or pro-atherogenic activity. Moreover, the effects of the diet and physical activity on PON1 and MPO are summarised with respect to the HDL-C functionality.

  8. Metallurgical characterization of melt-spun ribbons of U-5.4 wt%Nb alloy

    Science.gov (United States)

    Ma, Rong; Ren, Zhiyong; Tang, Qingfu; Chen, Dong; Liu, Tingyi; Su, Bin; Wang, Zhenhong; Luo, Chao

    2018-06-01

    The microstructures and micro-mechanical properties of the melt-spun ribbons of U-5.4 wt%Nb alloy were characterized using optical microscopy, scanning electron microscopy, X-ray diffraction and nanoindentation. Observed variations in microstructures and properties are related to the changes in ribbon thicknesses and cooling rates. The microstructures of the melt-spun ribbon consist of fine-scale columnar grains (∼1 μm) adjacent to the chill surface and coarse cellular grains in the remainder of the ribbon. In addition, the formation of inclusions in the ribbon is suppressed kinetically due to the high cooling rate during melt spinning. Compared with the water-quenched specimen prepared by traditional gravity casting and solution heat treatment, the elastic modulus values of the U-5.4 wt%Nb alloy were examined to vary with grain size and exhibited diverse energy dissipation capacities.

  9. Electronic properties and mechanical strength of β-phosphorene nano-ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Swaroop, Ram; Bhatia, Pradeep; Kumar, Ashok, E-mail: ashok@cup.ac.in [Centre for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India-151001 (India)

    2016-05-06

    We have performed first principles calculations to find out the effect of mechanical strain on the electronic properties of zig-zag edged nano ribbons of β-phosphorene. It is found that electronic band-gap get opened-up to 2.61 eV by passivation of the edges of ribbons. Similarly, the mechanical strength is found to be increase from 1.75 GPa to 2.65 GPa on going from unpassivated nano ribbons to passivated ones along with the 2% increase in ultimate tensile strain. The band-gap value of passivated ribbon gets decreased to 0.43 eV on applying strain up to which the ribbon does not break. These tunable properties of β-phospherene with passivation with H-atom and applying mechanical strain offer its use in tunable nano electronics.

  10. Mena–GRASP65 interaction couples actin polymerization to Golgi ribbon linking

    Science.gov (United States)

    Tang, Danming; Zhang, Xiaoyan; Huang, Shijiao; Yuan, Hebao; Li, Jie; Wang, Yanzhuang

    2016-01-01

    In mammalian cells, the Golgi reassembly stacking protein 65 (GRASP65) has been implicated in both Golgi stacking and ribbon linking by forming trans-oligomers through the N-terminal GRASP domain. Because the GRASP domain is globular and relatively small, but the gaps between stacks are large and heterogeneous, it remains puzzling how GRASP65 physically links Golgi stacks into a ribbon. To explore the possibility that other proteins may help GRASP65 in ribbon linking, we used biochemical methods and identified the actin elongation factor Mena as a novel GRASP65-binding protein. Mena is recruited onto the Golgi membranes through interaction with GRASP65. Depleting Mena or disrupting actin polymerization resulted in Golgi fragmentation. In cells, Mena and actin were required for Golgi ribbon formation after nocodazole washout; in vitro, Mena and microfilaments enhanced GRASP65 oligomerization and Golgi membrane fusion. Thus Mena interacts with GRASP65 to promote local actin polymerization, which facilitates Golgi ribbon linking. PMID:26538023

  11. Topology of helical fluid flow

    DEFF Research Database (Denmark)

    Andersen, Morten; Brøns, Morten

    2014-01-01

    function for the topology of the streamline pattern in incompressible flows. On this basis, we perform a comprehensive study of the topology of the flow field generated by a helical vortex filament in an ideal fluid. The classical expression for the stream function obtained by Hardin (Hardin, J. C. 1982...... the zeroes of a single real function of one variable, and we show that three different flow topologies can occur, depending on a single dimensionless parameter. By including the self-induced velocity on the vortex filament by a localised induction approximation, the stream function is slightly modified...... and an extra parameter is introduced. In this setting two new flow topologies arise, but not more than two critical points occur for any combination of parameters....

  12. Helically coiled tube heat exchanger

    International Nuclear Information System (INIS)

    Harris, A.M.

    1981-01-01

    In a heat exchanger such as a steam generator for a nuclear reactor, two or more bundles of helically coiled tubes are arranged in series with the tubes in each bundle integrally continuing through the tube bundles arranged in series therewith. Pitch values for the tubing in any pair of tube bundles, taken transverse to the path of the reactor coolant flow about the tubes, are selected as a ratio of two unequal integers to permit efficient operation of each tube bundle while maintaining the various tube bundles of the heat exchanger within a compact envelope. Preferably, the helix angle and tube pitch parallel to the path of coolant flow are constant for all tubes in a single bundle so that the tubes are of approximately the same length within each bundle

  13. The quantum Hall effect helicity

    Energy Technology Data Exchange (ETDEWEB)

    Shrivastava, Keshav N., E-mail: keshav1001@yahoo.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); School of Physics, University of Hyderabad, Hyderabad 500046 (India)

    2015-04-16

    The quantum Hall effect in semiconductor heterostructures is explained by two signs in the angular momentum j=l±s and g=(2j+1)/(2l+1) along with the Landau factor (n+1/2). These modifications in the existing theories explain all of the fractional charges. The helicity which is the sign of the product of the linear momentum with the spin p.s plays an important role for the understanding of the data at high magnetic fields. In particular it is found that particles with positive sign in the spin move in one direction and those with negative sign move in another direction which explains the up and down stream motion of the particles.

  14. Cholesterol and related sterols autoxidation.

    Science.gov (United States)

    Zerbinati, Chiara; Iuliano, Luigi

    2017-10-01

    Cholesterol is a unique lipid molecule providing the building block for membranes, hormones, vitamin D and bile acid synthesis. Metabolism of cholesterol involves several enzymes acting on the sterol nucleus or the isooctyl tail. In the recent years, research interest has been focused on oxysterols, cholesterol derivatives generated by the addition of oxygen to the cholesterol backbone. Oxysterols can be produced enzymatically or by autoxidation. Autoxidation of cholesterol proceeds through type I or type II mechanisms. Type I autoxidation is initiated by free radical species, such as those arising from the superoxide/hydrogen peroxide/hydroxyl radical system. Type II autoxidation occurs stoichiometrically by non-radical highly reactive oxygen species such as singlet oxygen, HOCl, and ozone. The vulnerability of cholesterol towards high reactive species has raised considerable interest for mechanistic studies and for the potential biological activity of oxysterols, as well as for the use of oxysterols as biomarkers for the non-invasive study of oxidative stress in vivo. Copyright © 2017. Published by Elsevier Inc.

  15. Thermal Conductivity of Graphene-hBN Superlattice Ribbons.

    Science.gov (United States)

    Felix, Isaac M; Pereira, Luiz Felipe C

    2018-02-09

    Superlattices are ideal model systems for the realization and understanding of coherent (wave-like) and incoherent (particle-like) phonon thermal transport. Single layer heterostructures of graphene and hexagonal boron nitride have been produced recently with sharp edges and controlled domain sizes. In this study we employ nonequilibrium molecular dynamics simulations to investigate the thermal conductivity of superlattice nanoribbons with equal-sized domains of graphene and hexagonal boron nitride. We analyze the dependence of the conductivity with the domain sizes, and with the total length of the ribbons. We determine that the thermal conductivity reaches a minimum value of 89 W m -1 K -1 for ribbons with a superlattice period of 3.43 nm. The effective phonon mean free path is also determined and shows a minimum value of 32 nm for the same superlattice period. Our results also reveal that a crossover from coherent to incoherent phonon transport is present at room temperature for BNC nanoribbons, as the superlattice period becomes comparable to the phonon coherence length. Analyzing phonon populations relative to the smallest superlattice period, we attribute the minimum thermal conductivity to a reduction in the population of flexural phonons when the superlattice period equals 3.43 nm. The ability to manipulate thermal conductivity using superlattice-based two-dimensional materials, such as graphene-hBN nanoribbons, opens up opportunities for application in future nanostructured thermoelectric devices.

  16. Oxidation behaviour of ribbon shape carbon fibers and their composites

    International Nuclear Information System (INIS)

    Manocha, L.M.; Warrier, Ashish; Manocha, S.; Edie, D.D.; Ogale, A.A.

    2006-01-01

    Carbon fibers, though important constituent as reinforcements for high performance carbon/carbon composites, are shadowed by their oxidation in air at temperatures beginning 450 deg. C. Owing to tailorable properties of carbon fibers, efforts are underway to explore structural modification possibilities to improve the oxidation resistance of the fibers and their composites. The pitch based ribbon shape carbon fibers are found to have highly preferential oriented graphitic structure resulting in high mechanical properties and thermal conductivity. In the present work oxidation behaviour of ribbon shape carbon fibers and their composites heat treated to 1000-2700 deg. C has been studied. SEM examination of these composites exhibits development of graphitic texture and ordering within the fibers with increase in heat treatment temperature. Oxidation studies made by thermogravimetric analysis in air show that matrix has faster rate of oxidation and in the initial stages the matrix gets oxidized at faster rate with slower rate of oxidation of the fibers depending on processing conditions of fibers and composites

  17. 75 FR 41808 - Narrow Woven Ribbons With Woven Selvedge From the People's Republic of China: Final Determination...

    Science.gov (United States)

    2010-07-19

    ... Ribbon Company, Inc. (``Petitioner''); Yama; and Yangzhou Bestpak Gifts & Crafts Co., Ltd. (``Bestpak... liquid petroleum gas from the supplier to Yama's factory.\\10\\ \\10\\ See Final Analysis Memorandum for Yama... limited to gift bags, gift boxes and/ or other types of ribbon. Narrow woven ribbons subject to the...

  18. Evidence for Mixed Helicity in Erupting Filaments

    Science.gov (United States)

    Muglach, K.; Wang, Y.-M.; Kliem, B.

    2009-09-01

    Erupting filaments are sometimes observed to undergo a rotation about the vertical direction as they rise. This rotation of the filament axis is generally interpreted as a conversion of twist into writhe in a kink-unstable magnetic flux rope. Consistent with this interpretation, the rotation is usually found to be clockwise (as viewed from above) if the post-eruption arcade has right-handed helicity, but counterclockwise if it has left-handed helicity. Here, we describe two non-active-region filament events recorded with the Extreme-Ultraviolet Imaging Telescope on the Solar and Heliospheric Observatory in which the sense of rotation appears to be opposite to that expected from the helicity of the post-event arcade. Based on these observations, we suggest that the rotation of the filament axis is, in general, determined by the net helicity of the erupting system, and that the axially aligned core of the filament can have the opposite helicity sign to the surrounding field. In most cases, the surrounding field provides the main contribution to the net helicity. In the events reported here, however, the helicity associated with the filament "barbs" is opposite in sign to and dominates that of the overlying arcade.

  19. HEMISPHERIC HELICITY TREND FOR SOLAR CYCLE 24

    International Nuclear Information System (INIS)

    Hao Juan; Zhang Mei

    2011-01-01

    Using vector magnetograms obtained with the Spectro-polarimeter (SP) on board Hinode satellite, we studied two helicity parameters (local twist and current helicity) of 64 active regions that occurred in the descending phase of solar cycle 23 and the ascending phase of solar cycle 24. Our analysis gives the following results. (1) The 34 active regions of the solar cycle 24 follow the so-called hemispheric helicity rule, whereas the 30 active regions of the solar cycle 23 do not. (2) When combining all 64 active regions as one sample, they follow the hemispheric helicity sign rule as in most other observations. (3) Despite the so-far most accurate measurement of vector magnetic field given by SP/Hinode, the rule is still weak with large scatters. (4) The data show evidence of different helicity signs between strong and weak fields, confirming previous result from a large sample of ground-based observations. (5) With two example sunspots we show that the helicity parameters change sign from the inner umbra to the outer penumbra, where the sign of penumbra agrees with the sign of the active region as a whole. From these results, we speculate that both the Σ-effect (turbulent convection) and the dynamo have contributed in the generation of helicity, whereas in both cases turbulence in the convection zone has played a significant role.

  20. High Cholesterol in Children and Teens

    Science.gov (United States)

    ... dairy products. The body needs some cholesterol to work properly. But if your child or teen has high cholesterol (too much cholesterol in the blood), he or she has a higher risk of coronary artery disease and other heart diseases. What causes high cholesterol in children and teens? Three main ...

  1. Cholesterol Medicines: MedlinePlus Health Topic

    Science.gov (United States)

    ... heart diseases . There are two main types of cholesterol. LDL is the "bad" cholesterol. A high LDL level leads to a buildup of cholesterol in ... 75 years old, you have diabetes, and your LDL cholesterol level is 70 mg/dL or higher You ...

  2. Niacin to Boost Your HDL "Good" Cholesterol

    Science.gov (United States)

    Niacin can boost 'good' cholesterol Niacin is a B vitamin that may raise your HDL ("good") cholesterol. But side effects might outweigh benefits for most ... been used to increase high-density lipoprotein (HDL) cholesterol — the "good" cholesterol that helps remove low-density ...

  3. Polymorphic transformation of helical flagella of bacteria

    Science.gov (United States)

    Lim, Sookkyung; Howard Berg Collaboration; William Ko Collaboration; Yongsam Kim Collaboration; Wanho Lee Collaboration; Charles Peskin Collaboration

    2016-11-01

    Bacteria such as E. coli swim in an aqueous environment by utilizing the rotation of flagellar motors and alternate two modes of motility, runs and tumbles. Runs are steady forward swimming driven by bundles of flagellar filaments whose motors are turning CCW; tumbles involve a reorientation of the direction of swimming triggered by motor reversals. During tumbling, the helical flagellum undergoes polymorphic transformations, which is a local change in helical pitch, helical radius, and handedness. In this work, we investigate the underlying mechanism of structural conformation and how this polymorphic transition plays a role in bacterial swimming. National Science Foundation.

  4. Modelling simple helically delivered dose distributions

    International Nuclear Information System (INIS)

    Fenwick, John D; Tome, Wolfgang A; Kissick, Michael W; Mackie, T Rock

    2005-01-01

    In a previous paper, we described quality assurance procedures for Hi-Art helical tomotherapy machines. Here, we develop further some ideas discussed briefly in that paper. Simple helically generated dose distributions are modelled, and relationships between these dose distributions and underlying characteristics of Hi-Art treatment systems are elucidated. In particular, we describe the dependence of dose levels along the central axis of a cylinder aligned coaxially with a Hi-Art machine on fan beam width, couch velocity and helical delivery lengths. The impact on these dose levels of angular variations in gantry speed or output per linear accelerator pulse is also explored

  5. Ezetimibe Increases Endogenous Cholesterol Excretion in Humans.

    Science.gov (United States)

    Lin, Xiaobo; Racette, Susan B; Ma, Lina; Wallendorf, Michael; Ostlund, Richard E

    2017-05-01

    Ezetimibe improves cardiovascular outcomes when added to optimum statin treatment. It lowers low-density lipoprotein cholesterol and percent intestinal cholesterol absorption, but the exact cardioprotective mechanism is unknown. We tested the hypothesis that the dominant effect of ezetimibe is to increase the reverse transport of cholesterol from rapidly mixing endogenous cholesterol pool into the stool. In a randomized, placebo-controlled, double-blind parallel trial in 24 healthy subjects with low-density lipoprotein cholesterol 100 to 200 mg/dL, we measured cholesterol metabolism before and after a 6-week treatment period with ezetimibe 10 mg/d or placebo. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d 7 in a lipid emulsion and dietary cholesterol with cholesterol-d 5 and sitostanol-d 4 solubilized in oil. Plasma and stool samples collected during a cholesterol- and phytosterol-controlled metabolic kitchen diet were analyzed by mass spectrometry. Ezetimibe reduced intestinal cholesterol absorption efficiency 30±4.3% (SE, P <0.0001) and low-density lipoprotein cholesterol 19.8±1.9% ( P =0.0001). Body cholesterol pool size was unchanged, but fecal endogenous cholesterol excretion increased 66.6±12.2% ( P <0.0001) and percent cholesterol excretion from body pools into the stool increased 74.7±14.3% ( P <0.0001), whereas plasma cholesterol turnover rose 26.2±3.6% ( P =0.0096). Fecal bile acids were unchanged. Ezetimibe increased the efficiency of reverse cholesterol transport from rapidly mixing plasma and tissue pools into the stool. Further work is needed to examine the potential relation of reverse cholesterol transport and whole body cholesterol metabolism to coronary events and the treatment of atherosclerosis. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603758. © 2017 American Heart Association, Inc.

  6. Cholesterol Depletion from a Ceramide/Cholesterol Mixed Monolayer: A Brewster Angle Microscope Study

    KAUST Repository

    Mandal, Pritam; Noutsi, Bakiza Kamal; Chaieb, Saharoui

    2016-01-01

    to deplete cholesterol (Chol) from biomembranes. Here, we focus on the depletion of cholesterol from a C16 ceramide/cholesterol (C16-Cer/Chol) mixed monolayer using MβCD. While the removal of cholesterol by MβCD depends on the cholesterol concentration

  7. Plasmoid behavior in helical plasmas

    International Nuclear Information System (INIS)

    Ishizaki, R.; Nakajima, N.

    2009-01-01

    Full text: It is well known that an ablation cloud; a high density and low temperature plasmoid, drifts to the lower field side in tokamak plasmas, which leads to a good performance on fueling in tokamak. Such a good performance, however, has not been obtained yet in the planar axis heliotron; Large Helical Device (LHD) experiments, even if a pellet has been injected from the high field side. The purpose of the study is to clarify the difference on the plasmoid motion between tokamak and LHD plasmas by using the MHD simulation including ablation processes. It is found in tokamaks that the drift motion is induced by a tire tube force and 1/R force in the major radius direction, and that the pressure and density of the plasmoid have oscillation due to fast compressional Alfven wave. On the other hand, the upper and lower portions surrounding the plasmoid center drift to the higher field side, because 1/R force by magnetic field becomes negative in the major radius direction since the magnetic field surrounding the plasmoid is accumulated by the extremely large ablation pressure and the magnetic pressure perturbation becomes positive. It is also found that the plasmoid does not drift when the perturbation of the plasmoid is small. In addition, the motion of the plasmoid is investigated in LHD plasmas in four cases that the plasmoids are initially located at the inner and outer sides of the torus on the vertically and horizontally elongated poloidal cross sections. The plasmoids drift to the lower field sides in all cases. However, in the case that it is located at the inner side of the torus on the horizontally elongated poloidal cross section, it is found that the plasmoid drifts in the negative direction of the major radius and subsequently drifts in the positive direction of it. In other words, the plasmoid finally drifts in the positive direction of the major radius the same as the plasmoid located at the outer side of the torus. This fact might be one of the

  8. Peptide design using alpha,beta-dehydro amino acids: from beta-turns to helical hairpins.

    Science.gov (United States)

    Mathur, Puniti; Ramakumar, S; Chauhan, V S

    2004-01-01

    Incorporation of alpha,beta-dehydrophenylalanine (DeltaPhe) residue in peptides induces folded conformations: beta-turns in short peptides and 3(10)-helices in larger ones. A few exceptions-namely, alpha-helix or flat beta-bend ribbon structures-have also been reported in a few cases. The most favorable conformation of DeltaPhe residues are (phi,psi) approximately (-60 degrees, -30 degrees ), (-60 degrees, 150 degrees ), (80 degrees, 0 degrees ) or their enantiomers. DeltaPhe is an achiral and planar residue. These features have been exploited in designing DeltaPhe zippers and helix-turn-helix motifs. DeltaPhe can be incorporated in both right and left-handed helices. In fact, consecutive occurrence of three or more DeltaPhe amino acids induce left-handed screw sense in peptides containing L-amino acids. Weak interactions involving the DeltaPhe residue play an important role in molecular association. The C--H.O==C hydrogen bond between the DeltaPhe side-chain and backbone carboxyl moiety, pi-pi stacking interactions between DeltaPhe side chains belonging to enantiomeric helices have shown to stabilize folding. The unusual capability of a DeltaPhe ring to form the hub of multicentered interactions namely, a donor in aromatic C--H.pi and C--H.O==C and an acceptor in a CH(3).pi interaction suggests its exploitation in introducing long-range interactions in the folding of supersecondary structures. Copyright 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004

  9. Helicity and Filament Channels? The Straight Twist!

    Science.gov (United States)

    Antiochos, Spiro K.

    2010-01-01

    One of the most important and most puzzling features of the coronal magnetic field is that it appears to have smooth magnetic structure with little evidence for non-potentiality except at special locations, photospheric polarity inversions lines where the non-potentiality is observed as a filament channel. This characteristic feature of the closed-field corona is highly unexpected given that photospheric motions continuously tangle its magnetic field. Although reconnection can eliminate some of the injected structure, it cannot destroy the helicity, which should build up to produce observable complexity. We propose that an inverse cascade process transports the injected helicity from the interior of closed flux regions to their boundaries, polarity inversion lines, creating filament channels. We describe how the helicity is injected and transported and calculate the relevant rates. We argue that one process, helicity transport, can explain both the observed lack and presence of structure in the coronal magnetic field.

  10. Spin versus helicity in processes involving transversity

    CERN Document Server

    Mekhfi, Mustapha

    2011-01-01

    We construct the spin formalism in order to deal in a direct and natural way with processes involving transversity which are now of increasing popularity. The helicity formalism which is more appropriate for collision processes of definite helicity has been so far used also to manage processes with transversity, but at the price of computing numerous helicity amplitudes generally involving unnecessary kinematical variables.In a second step we work out the correspondence between both formalisms and retrieve in another way all results of the helicity formalism but in simpler forms.We then compute certain processes for comparison.A special process:the quark dipole magnetic moment is shown to be exclusively treated within the spin formalism as it is directly related to the transverse spin of the quark inside the baryon.

  11. Helical magnetized wiggler for synchrotron radiation laser

    International Nuclear Information System (INIS)

    Wang Mei; Park, S.Y.; Hirshfield, J.L.

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude

  12. Helical magnetized wiggler for synchrotron radiation laser

    CERN Document Server

    Wang Mei; Hirshfield, J L

    1999-01-01

    A helical magnetized iron wiggler has been built for a novel infrared synchrotron radiation laser (SRL) experiment. The wiggler consists of four periods of helical iron structure immersed in a solenoid field. This wiggler is to impart transverse velocity to a prebunched 6 MeV electron beam, and thus to obtain a desired high orbit pitch ratio for the SRL. Field tapering at beam entrance is considered and tested on a similar wiggler. Analytic and simulated characteristics of wigglers of this type are discussed and the performance of the fabricated wigglers is demonstrated experimentally. A 4.7 kG peak field was measured for a 6.4 mm air gap and a 5.4 cm wiggler period at a 20 kG solenoid field. The measured helical fields compare favorably with the analytical solution. This type of helical iron wigglers has the potential to be scaled to small periods with strong field amplitude.

  13. Using helical compressors for coke gas condensation

    Energy Technology Data Exchange (ETDEWEB)

    Privalov, V E; Rezunenko, Yu I; Lelyanov, N V; Zarnitzkii, G Eh; Gordienko, A A; Derebenko, I F; Venzhega, A G; Leonov, N P; Gorokhov, N N

    1982-08-01

    Coke oven gas compression is discussed. Presently used multilevel piston compressors are criticized. The paper recommends using helical machines which combine advantages of using volume condensing compressors and compact high-efficiency centrifugal machines. Two kinds of helical compressors are evaluated: dry and oil-filled; their productivities and coke oven gas chemical composition are analyzed. Experiments using helical compressors were undertaken at the Yasinovskii plant. Flowsheet of the installation is shown. Performance results are given in a table. For all operating conditions content of insolubles in oil compounds is found to be lower than the acceptable value (0.08%). Compressor productivity measurements with variable manifold pressure are evaluated. Figures obtained show that efficient condensation of raw coke oven gas is possible. Increasing oil-filled compressor productivity is recommended by decreasing amount of oil injected and simultaneously increasing rotation speed. The dry helical compressor with water seal is found to be most promising for raw coke oven gas condensation. (10 refs.)

  14. Nanocrystallization in amorphous Fe40Ni40(Si+B)19Mo1-2 ribbons

    International Nuclear Information System (INIS)

    Saiseng, S.; Winotai, P.; Nilpairuch, S.; Limsuwan, P.; Tang, I.M.

    2004-01-01

    Cut Fe 40 Ni 40 (Si+B) 19 Mo 1-2 ribbons were annealed for 2 h at various temperatures between 350 deg. C and 600 deg. C. XRD and Mossbauer effect spectroscopy (ME) measurements were then performed on all of the ribbons. The magnetic properties of several ribbons were measured using a vibrating sample magnetometer (VSM). A differential thermal analysis scan (over the range 20-800 deg. C) of the as-cast ribbon showed two phase transitions; the first at 454 deg. C and the second at 525 deg. C. Both the XRD and ME spectra of the as cast, the 350 deg. C and 400 deg. C annealed ribbons showed that they were amorphous. The ME spectra of the 450 deg. C, 475 deg. C and 500 deg. C annealed ribbons showed that these ribbons contained α-Fe, α-Fe(Si) and t-Fe 2 B nanocrystallites. For the ribbons annealed above 550 deg. C, crystallites of t-Fe 2 B, t-Fe 3 B, t-Fe 5 SiB 2 and FCC-FeNi appeared, with the α-Fe and α-Fe(Si) crystallites disappearing. The sextets of all of the Fe compounds appeared in the ME spectra of the 525 deg. C annealed ribbon. The VSM measurements supported the picture of a two-stage phase transitions; amorphous phase→a nanocrystalline phase (Fe-containing nanocrystallites in an amorphous matrix) at 454 deg. C and then a second transition, the nanocrystalline phase→a disordered alloy containing Fe-B and Fe-Ni crystallites at 525 deg. C

  15. Helicity evolution at small x

    International Nuclear Information System (INIS)

    Kovchegov, Yuri V.; Pitonyak, Daniel; Sievert, Matthew D.

    2016-01-01

    We construct small-x evolution equations which can be used to calculate quark and anti-quark helicity TMDs and PDFs, along with the g 1 structure function. These evolution equations resum powers of α s ln 2  (1/x) in the polarization-dependent evolution along with the powers of α s ln (1/x) in the unpolarized evolution which includes saturation effects. The equations are written in an operator form in terms of polarization-dependent Wilson line-like operators. While the equations do not close in general, they become closed and self-contained systems of non-linear equations in the large-N c and large-N c   N f limits. As a cross-check, in the ladder approximation, our equations map onto the same ladder limit of the infrared evolution equations for the g 1 structure function derived previously by Bartels, Ermolaev and Ryskin http://dx.doi.org/10.1007/s002880050285.

  16. Dynamics of helicity transport and Taylor relaxation

    International Nuclear Information System (INIS)

    Diamond, P.H.; Malkov, M.

    2003-01-01

    A simple model of the dynamics of Taylor relaxation is derived using symmetry principles alone. No statistical closure approximations are invoked or detailed plasma model properties assumed. Notably, the model predicts several classes of nondiffusive helicity transport phenomena, including traveling nonlinear waves and superdiffusive turbulent pulses. A universal expression for the scaling of the effective magnetic Reynolds number of a system undergoing Taylor relaxation is derived. Some basic properties of intermittency in helicity transport are examined

  17. Multiple helical modes of vortex breakdown

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; Naumov, I. V.; Okulov, Valery

    2011-01-01

    Experimental observations of vortex breakdown in a rotating lid-driven cavity are presented. The results show that vortex breakdown for cavities with high aspect ratios is associated with the appearance of stable helical vortex multiplets. By using results from stability theory generalizing Kelvi......’s problem on vortex polygon stability, and systematically exploring the cavity flow, we succeeded in identifying two new stable vortex breakdown states consisting of triple and quadruple helical multiplets....

  18. Small Scales Structure of MHD Turbulence, Tubes or Ribbons?

    Science.gov (United States)

    Verdini, A.; Grappin, R.; Alexandrova, O.; Lion, S.

    2017-12-01

    Observations in the solar wind indicate that turbulent eddies change their anisotropy with scales [1]. At large scales eddies are elongated in direction perpendicular to the mean-field axis. This is the result of solar wind expansion that affects both the anisotropy and single-spacecraft measurments [2,3]. At small scales one recovers the anisotropy expected in strong MHD turbulence and constrained by the so-called critical balance: eddies are elongated along the mean-field axis. However, the actual eddy shape is intermediate between tubes and ribbons, preventing us to discriminate between two concurrent theories that predict 2D axysimmetric anisotropy [4] or full 3D anisotropy [5]. We analyse 10 years of WIND data and apply a numerically-derived criterion to select intervals in which solar wind expansion is expected to be negligible. By computing the anisotropy of structure functions with respect to the local mean field we obtain for the first time scaling relations that are in agreement with full 3D anisotropy, i.e. ribbons-like structures. However, we cannot obtain the expected scaling relations for the alignment angle which, according to the theory, is physically responsible for the departure from axisymmetry. In addition, a further change of anisotropy occurs well above the proton scales. We discuss the implication of our findings and how numerical simulations can help interpreting the observed spectral anisotropy. [1] Chen et al., ApJ, 768:120, 2012 [2] Verdini & Grappin, ApJL, 808:L34, 2015 [3] Vech & Chen, ApJL, 832:L16, 2016 [4] Goldreich & Shridar, ApJ, 438:763, 1995 [5] Boldyrev, ApJL, 626:L37, 2005

  19. Regulation of biliary cholesterol secretion and reverse cholesterol transport

    NARCIS (Netherlands)

    Dikkers, Arne

    2016-01-01

    According to the World Health Organization the number one cause of death throughout the world is cardiovascular disease. Therefore, there is an urgent need for new therapeutic strategies to prevent and treat cardiovascular disease. One possible way is to target the HDL-driven reverse cholesterol

  20. On the helicity of open magnetic fields

    International Nuclear Information System (INIS)

    Prior, C.; Yeates, A. R.

    2014-01-01

    We reconsider the topological interpretation of magnetic helicity for magnetic fields in open domains, and relate this to the relative helicity. Specifically, our domains stretch between two parallel planes, and each of these ends may be magnetically open. It is demonstrated that, while the magnetic helicity is gauge-dependent, its value in any gauge may be physically interpreted as the average winding number among all pairs of field lines with respect to some orthonormal frame field. In fact, the choice of gauge is equivalent to the choice of reference field in the relative helicity, meaning that the magnetic helicity is no less physically meaningful. We prove that a particular gauge always measures the winding with respect to a fixed frame, and propose that this is normally the best choice. For periodic fields, this choice is equivalent to measuring relative helicity with respect to a potential reference field. However, for aperiodic fields, we show that the potential field can be twisted. We prove by construction that there always exists a possible untwisted reference field.

  1. Cholesterol Levels: What You Need to Know: MedlinePlus Health Topic

    Science.gov (United States)

    ... lipoprotein ( LDL ) cholesterol and high-density lipoprotein ( HDL ) cholesterol. LDL (bad) cholesterol - the main source of cholesterol buildup ... Teens How to Lower Cholesterol How to Lower Cholesterol with Diet LDL: The "Bad" Cholesterol Nutrition Statins Triglycerides VLDL Cholesterol ...

  2. Diffusion in a tokamak with helical magnetic cells

    International Nuclear Information System (INIS)

    Wakatani, Masahiro

    1975-05-01

    In a tokamak with helical magnetic cells produced by a resonant helical magnetic field, diffusion in the collisional regime is studied. The diffusion coefficient is greatly enhanced near the resonant surface even for a weak helical magnetic field. A theoretical model for disruptive instabilities based on the enhanced transport due to helical magnetic cells is discussed. This may explain experiments of the tokamak with resonant helical fields qualitatively. (author)

  3. Remnant cholesterol and ischemic heart disease

    DEFF Research Database (Denmark)

    Varbo, Anette; Nordestgaard, Børge G

    2014-01-01

    PURPOSE OF REVIEW: To review recent advances in the field of remnant cholesterol as a contributor to the development of ischemic heart disease (IHD). RECENT FINDINGS: Epidemiologic, mechanistic, and genetic studies all support a role for elevated remnant cholesterol (=cholesterol in triglyceride......-rich lipoproteins) as a contributor to the development of atherosclerosis and IHD. Observational studies show association between elevated remnant cholesterol and IHD, and mechanistic studies show remnant cholesterol accumulation in the arterial wall like LDL-cholesterol (LDL-C) accumulation. Furthermore, large...... genetic studies show evidence of remnant cholesterol as a causal risk factor for IHD independent of HDL-cholesterol levels. Genetic studies also show that elevated remnant cholesterol is associated with low-grade inflammation, whereas elevated LDL-C is not. There are several pharmacologic ways of lowering...

  4. The Drosophila DHR96 nuclear receptor binds cholesterol and regulates cholesterol homeostasis

    OpenAIRE

    Horner, Michael A.; Pardee, Keith; Liu, Suya; King-Jones, Kirst; Lajoie, Gilles; Edwards, Aled; Krause, Henry M.; Thummel, Carl S.

    2009-01-01

    Cholesterol homeostasis is required to maintain normal cellular function and avoid the deleterious effects of hypercholesterolemia. Here we show that the Drosophila DHR96 nuclear receptor binds cholesterol and is required for the coordinate transcriptional response of genes that are regulated by cholesterol and involved in cholesterol uptake, trafficking, and storage. DHR96 mutants die when grown on low levels of cholesterol and accumulate excess cholesterol when maintained on a high-choleste...

  5. Self-Assembling Biological Springs Force Transducers on the Micron Nanoscale

    Energy Technology Data Exchange (ETDEWEB)

    Benedek, George [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Casparay, Alfred H. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2016-08-19

    In this project, we are developing a new system for measuring forces within and between nanoscale biological molecules based on mesoscopic springs made of cholesterol helical ribbons. These ribbons self-assemble in a wide variety of complex fluids containing sterol, a mixture of surfactants and water [1] and have spring constants in the range from 0.5 to 500 pN/nm [2-4]. By the end of this project, we have demonstrated that the cholesterol helical ribbons can be used for measuring forces between biological objects and for mapping the strain fields in hydrogels.

  6. Lecithin intake and serum cholesterol.

    NARCIS (Netherlands)

    Knuiman, J.T.; Beynen, A.C.; Katan, M.B.

    1989-01-01

    To find out whether the consumption of lecithin has a more beneficial effect on serum cholesterol than does the consumption of equivalent amounts of polyunsaturated oils, we scrutinized 24 studies on the effect of supplementary lecithin intakes ranging from 1 to 54 mg/d. Most of the studies lacked

  7. The ABC of cholesterol transport

    NARCIS (Netherlands)

    Plösch, Torsten

    2004-01-01

    Cholesterol fulfills an indispensable role in mammalian physiology. It is an important constituent of all cell membranes. Furthermore, it is the precursor of steroid hormones, which regulate a variety of physiological functions, and of bile salts, which are necessary for the generation of bile flow

  8. Membrane Cholesterol Modulates Superwarfarin Toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Marangoni, M. Natalia; Martynowycz, Michael W.; Kuzmenko, Ivan; Braun, David; Polak, Paul E.; Weinberg, Guy; Rubinstein, Israel; Gidalevitz, David; Feinstein, Douglas L.

    2016-04-26

    Superwarfarins are modified analogs of warfarin with additional lipophilic aromatic rings, up to 100-fold greater potency, and longer biological half-lives. We hypothesized that increased hydrophobicity allowed interactions with amphiphilic membranes and modulation of biological responses. We find that superwarfarins brodifacoum and difenacoum increase lactate production and cell death in neuroblastoma cells. In contrast, neither causes changes in glioma cells that have higher cholesterol content. After choleterol depletion, lactate production was increased and cell viability was reduced. Drug-membrane interactions were examined by surface X-ray scattering using Langmuir monolayers of dipalmitoylphosphatidylcholine and/or cholesterol. Specular X-ray reflectivity data revealed that superwarfarins, but not warfarin, intercalate between dipalmitoylphosphatidylcholine molecules, whereas grazing incidence X-ray diffraction demonstrated changes in lateral crystalline order of the film. Neither agent showed significant interactions with monolayers containing >20% cholesterol. These findings demonstrate an affinity of superwarfarins to biomembranes and suggest that cellular responses to these agents are regulated by cholesterol content.

  9. Electronic, magnetic and transport properties of graphene ribbons terminated by nanotubes

    International Nuclear Information System (INIS)

    Akhukov, M A; Yuan Shengjun; Fasolino, A; Katsnelson, M I

    2012-01-01

    We study, by density functional and large-scale tight-binding transport calculations, the electronic structure, magnetism and transport properties of the recently proposed graphene ribbons with edges rolled to form nanotubes. Edges with armchair nanotubes present magnetic moments localized either in the tube or the ribbon and of metallic or half-metallic character, depending on the symmetry of the junction. These properties have potential for spin valve and spin filter devices with advantages over other proposed systems. Edges with zigzag nanotubes are either metallic or semiconducting without affecting the intrinsic mobility of the ribbon. Varying the type and size of the nanotubes and ribbons offers the possibility to tailor the magnetic and transport properties, making these systems very promising for applications. (paper)

  10. A micromagnetic study of the oscillations of pinned domain walls in magnetic ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Alejos, Oscar [Dpto. Electricidad y Electronica, Universidad de Valladolid, 47071 Valladolid (Spain)]. E-mail: oscaral@ee.uva.es; Torres, Carlos [Dpto. Electricidad y Electronica, Universidad de Valladolid, 47071 Valladolid (Spain); Hernandez-Gomez, Pablo [Dpto. Electricidad y Electronica, Universidad de Valladolid, 47071 Valladolid (Spain); Lopez-Diaz, Luis [Dpto. Fisica Aplicada, Universidad de Salamanca, 37071 Salamanca (Spain); Torres, Luis [Dpto. Fisica Aplicada, Universidad de Salamanca, 37071 Salamanca (Spain); Martinez, Eduardo [Dpto. Ingenieria Electromecanica, Universidad de Burgos, 09001 Burgos (Spain)

    2007-09-15

    The work studies the dynamics of domain walls in magnetic ribbons with thicknesses of the order of magnitude of the permalloy exchange length (5.7 nm) by means of micromagnetic simulations. Two small defects are symmetrically placed on both edges of the ribbon, one on each edge, occupying the whole ribbon thickness. One transverse domain wall is pinned by the defects, in a head-to-head configuration. A free wall oscillation is forced by applying a static external magnetic field in the direction of the large axis until the wall reaches a new equilibrium position (elongation), and then removed. Three dynamic regimes are observed depending on the size of the cross ribbon section.

  11. A micromagnetic study of the oscillations of pinned domain walls in magnetic ribbons

    International Nuclear Information System (INIS)

    Alejos, Oscar; Torres, Carlos; Hernandez-Gomez, Pablo; Lopez-Diaz, Luis; Torres, Luis; Martinez, Eduardo

    2007-01-01

    The work studies the dynamics of domain walls in magnetic ribbons with thicknesses of the order of magnitude of the permalloy exchange length (5.7 nm) by means of micromagnetic simulations. Two small defects are symmetrically placed on both edges of the ribbon, one on each edge, occupying the whole ribbon thickness. One transverse domain wall is pinned by the defects, in a head-to-head configuration. A free wall oscillation is forced by applying a static external magnetic field in the direction of the large axis until the wall reaches a new equilibrium position (elongation), and then removed. Three dynamic regimes are observed depending on the size of the cross ribbon section

  12. Cholesterol autoxidation in phospholipid membrane bilayers

    International Nuclear Information System (INIS)

    Sevanian, A.; McLeod, L.L.

    1987-01-01

    Lipid peroxidation in unilamellar liposomes of known cholesterol-phospholipid composition was monitored under conditions of autoxidation or as induced by a superoxide radical generating system, gamma-irradiation or cumene hydroperoxide. Formation of cholesterol oxidation products was indexed to the level of lipid peroxidation. The major cholesterol oxidation products identified were 7-keto-cholesterol, isomeric cholesterol 5,6-epoxides, isomeric 7-hydroperoxides and isomeric 3,7-cholestane diols. Other commonly encountered products included 3,5-cholestadiene-7-one and cholestane-3 beta, 5 alpha, 6 beta-triol. Superoxide-dependent peroxidation required iron and produced a gradual increase in 7-keto-cholesterol and cholesterol epoxides. Cholesterol oxidation was greatest in liposomes containing high proportions of unsaturated phospholipid to cholesterol (4:1 molar ratio), intermediate with low phospholipid to cholesterol ratios (2:1) and least in liposomes prepared with dipalmitoylphosphatidylcholine and cholesterol. This relationship held regardless of the oxidizing conditions used. Cumene hydroperoxide-dependent lipid peroxidation and/or more prolonged oxidations with other oxidizing systems yielded a variety of products where cholesterol-5 beta,6 beta-epoxide, 7-ketocholesterol and the 7-hydroperoxides were most consistently elevated. Oxyradical initiation of lipid peroxidation produced a pattern of cholesterol oxidation products distinguishable from the pattern derived by cumene hydroperoxide-dependent peroxidation

  13. Manufacture of ribbon and solar cells of material of semiconductor grade

    International Nuclear Information System (INIS)

    1980-01-01

    A method is described of producing ribbon-like substantially monocrystalline bodies of silicon or other materials of semiconductor grade suitable for use in solar cells or other semiconductor devices. A tube of the material is made and a photovoltaic junction formed in it. The tube is then divided lengthwise into a number of ribbon-like bodies. The photovoltaic junction can be formed either by diffusion or by ion-implantation. (U.K.)

  14. Orthogonal ribbons for suspending test masses in interferometric gravitational wave detectors

    International Nuclear Information System (INIS)

    Lee, B.H.; Ju, L.; Blair, D.G.

    2005-01-01

    We show that a simple modification of proposed ribbon suspensions for laser interferometric gravitational wave detectors can substantially reduce the amplitude of violin modes at the expense of a small deterioration of suspension thermal noise. Using low loss fused silica, large amplitude peaks which cause dynamic range problems can be reduced by 21 dB. The total number of horizontal longitudinal direction violin modes below 5 kHz is reduced to less than half that expected with conventional ribbon suspensions

  15. Orthogonal ribbons for suspending test masses in interferometric gravitational wave detectors

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B.H. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)]. E-mail: bhl@physics.uwa.edu.au; Ju, L. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia); Blair, D.G. [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)

    2005-05-23

    We show that a simple modification of proposed ribbon suspensions for laser interferometric gravitational wave detectors can substantially reduce the amplitude of violin modes at the expense of a small deterioration of suspension thermal noise. Using low loss fused silica, large amplitude peaks which cause dynamic range problems can be reduced by 21 dB. The total number of horizontal longitudinal direction violin modes below 5 kHz is reduced to less than half that expected with conventional ribbon suspensions.

  16. Covalent immobilization of cholesterol esterase and cholesterol oxidase on polyaniline films for application to cholesterol biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Suman [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Solanki, Pratima R. [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Pandey, M.K. [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012 (India); Malhotra, B.D. [Biomolecular Electronics and Conducting Polymer Research Group, National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi-110012 (India)]. E-mail: bansi@mail.nplindia.ernet.in

    2006-05-24

    Cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) have been covalently immobilized on electrochemically prepared polyaniline (PANI) films. These PANI/ChEt/ChOx enzyme films have been characterized using UV-visible, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Electrochemical behavior of these films has been studied using cyclic voltammetry (CV) and amperometric techniques, respectively. The PANI/ChEt/ChOx enzyme films show broad oxidation peak from 0.2 to 0.5 V. These PANI/ChEt/ChOx biosensing electrodes have a response time of about 40 s, linearity from 50 to 500 mg/dl of cholesterol oleate concentration. These PANI/ChEt/ChOx films are thermally stable up to 46 deg. C. This polyaniline based cholesterol biosensor has optimum pH in the range of 6.5-7.5, sensitivity as 7.5 x 10{sup -4} nA/mg dl and a lifetime of about 6 weeks.

  17. Nanoscale Membrane Domain Formation Driven by Cholesterol

    DEFF Research Database (Denmark)

    Javanainen, Matti; Martinez-Seara, Hector; Vattulainen, Ilpo

    2017-01-01

    Biological membranes generate specific functions through compartmentalized regions such as cholesterol-enriched membrane nanodomains that host selected proteins. Despite the biological significance of nanodomains, details on their structure remain elusive. They cannot be observed via microscopic...... dipalmitoylphosphatidylcholine and cholesterol - the "minimal standard" for nanodomain formation. The simulations reveal how cholesterol drives the formation of fluid cholesterol-rich nanodomains hosting hexagonally packed cholesterol-poor lipid nanoclusters, both of which show registration between the membrane leaflets....... The complex nanodomain substructure forms when cholesterol positions itself in the domain boundary region. Here cholesterol can also readily flip-flop across the membrane. Most importantly, replacing cholesterol with a sterol characterized by a less asymmetric ring region impairs the emergence of nanodomains...

  18. Cholesterol, bile acid and triglyceride metabolism intertwined

    NARCIS (Netherlands)

    Schonewille, Marleen

    2016-01-01

    Hyperlipidemie wordt gekarakteriseerd door verhoogd plasma cholesterol en/of triglyceriden en sterk geassocieerd met het risico op cardiovasculaire aandoeningen. Dit proefschrift beschrijft onderzoek naar de regulatie van plasma cholesterol en triglyceriden concentraties en de achterliggende

  19. Cholesterol Level: Can It Be Too Low?

    Science.gov (United States)

    ... total cholesterol level has been associated with some health problems. Doctors are still trying to find out more about the connection between low cholesterol and health risks. There is no consensus on how to ...

  20. Cholesterol: the debate should be terminated.

    Science.gov (United States)

    Nathan, David G

    2017-07-01

    Here, I offer personal perspectives on cholesterol homeostasis that reflect my belief that certain aspects of the debate have been overstated.-Nathan, D. G. Cholesterol: the debate should be terminated. © FASEB.

  1. Effects of surface crystallization and oxidation in nanocrystalline FeNbCuSiB(P) ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Butvinová, B., E-mail: beata.butvinova@savba.sk [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Butvin, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Brzózka, K. [Department of Physics, University of Technology and Humanities in Radom, Krasickiego 54, 26-600 Radom (Poland); Kuzminski, M. [Institute of Physics PAS, Al. Lotnikow 36/42, 02-668 Warsaw (Poland); Maťko, I.; Švec Sr, P. [Institute of Physics SAS, Dúbravská cesta 9, 845 11 Bratislava (Slovakia); Chromčíková, M. [Institute of Inorg. Chem. SAS, Centrum VILA, Študentská 2, 911 50 Trenčín (Slovakia)

    2017-02-15

    Si-poor Fe{sub 74}Nb{sub 3}Cu{sub 1}Si{sub 8}B{sub 14−x}P{sub x}, (x=0, 3) nanocrystalline ribbon-form alloys often form surfaces, which exert in-plane force on underlying ribbon interior when nanocrystallized in even modest presence of oxygen. Mostly unwanted hard-ribbon-axis magnetic anisotropy is standard result. Essential sources of the surface-caused stress have been sought and influence of P instead of B substitution on this effect was studied too. Preferred surface crystallization (PSC) was found to be the major reason. However P substitution suppresses PSC and promotes Fe-oxide formation, which eases the stress, softens the surfaces and provides different annealing evolution of surface properties. - Highlights: • Ar anneal of low-Si FeNbCuBSi ribbons produce surfaces that stress ribbon interior. • The stress comes mainly from preferred crystallization of surfaces. • Partial substitution of B by P changes annealing evolution of surface properties. • Without P, more crystalline surfaces significantly reduce ribbon's elasticity. • P suppresses surface crystallinity, promotes oxides and reduces mutual stress.

  2. Martensitic transformation behavior and shape memory properties of Ti-Ni-Pt melt-spun ribbons

    International Nuclear Information System (INIS)

    Inamura, Tomonari; Takahashi, Yohei; Hosoda, Hideki; Wakashima, Kenji; Nagase, Takeshi; Nakano, Takayoshi; Umakoshi, Yukichi; Miyazaki, Shuichi

    2006-01-01

    Martensitic transformation behavior and shape memory properties of a Ti 50 Ni 40 Pt 10 (TiNiPt) melt-spun ribbon fabricated by a single roll melt-spinning technique were characterized. The constituent phases of the as-spun ribbon were B2 (parent phase) and B19 (martensite phase) at room temperature. The B2-B19 martensitic transformation temperatures of the as-spun ribbon were 100K higher than those of the bulk-material with the same chemical composition. The martensitic transformation temperatures of the as-spun ribbon were decreased with increasing the temperature of the heat-treatment made after the melt-spinning. The as-spun ribbon and the heat-treated ribbons exhibited shape recovery by heating and/or pseudoelasticity. The martensitic transformation temperatures determined from the temperature dependence of the 0.2% flow stress of the pseudoelastic deformation were in good agreement with those of B2-B19 martensitic transformation determined by DSC. It was confirmed that the observed shape recovery and pseudoelasticity are shape memory effect and superelasticity due to the B2-B19 martensitic transformation. Shape memory effect and superelasticity of melt-spun TiNiPt alloy were found to appear at higher temperatures compared to those of Bulk-material with the same composition. (author)

  3. Evolutionary analysis of a novel zinc ribbon in the N-terminal region of threonine synthase.

    Science.gov (United States)

    Kaur, Gurmeet; Subramanian, Srikrishna

    2017-10-18

    Threonine synthase (TS) catalyzes the terminal reaction in the biosynthetic pathway of threonine and requires pyridoxal phosphate as a cofactor. TSs share a common catalytic domain with other fold type II PALP dependent enzymes. TSs are broadly grouped into two classes based on their sequence, quaternary structure, and enzyme regulation. We report the presence of a novel zinc ribbon domain in the N-terminal region preceding the catalytic core in TS. The zinc ribbon domain is present in TSs belonging to both classes. Our sequence analysis reveals that archaeal TSs possess all zinc chelating residues to bind a metal ion that are lacking in the structurally characterized homologs. Phylogenetic analysis suggests that TSs with an N-terminal zinc ribbon likely represents the ancestral state of the enzyme while TSs without a zinc ribbon must have diverged later in specific lineages. The zinc ribbon and its N- and C-terminal extensions are important for enzyme stability, activity and regulation. It is likely that the zinc ribbon domain is involved in higher order oligomerization or mediating interactions with other biomolecules leading to formation of larger metabolic complexes.

  4. Dynamic helical CT mammography of breast cancer

    International Nuclear Information System (INIS)

    Yamamoto, Akira; Fukushima, Hitoshi; Okamura, Ryuji; Nakamura, Yoshiaki; Morimoto, Taisuke; Urata, Yoji; Mukaihara, Sumio; Hayakawa, Katsumi

    2006-01-01

    The purpose of this study was to determine whether dynamic helical computed tomography (CT)-mammography could assist in selecting the most appropriate surgical method in women with breast cancer. Preoperative contrast-enhanced helical CT scanning of the breast was performed on 133 female patients with suspicion of breast cancer at the same time as clinical, mammographic, and/or ultrasonographic examinations. The patients were scanned in the prone position with a specially designed CT-compatible device. A helical scan was made with rapid intravenous bolus injection (3 ml/s) of 100 ml of iodine contrast material. Three-dimensional maximum intensity projection (MIP) images were reconstructed, and CT findings were correlated with surgical and histopathological findings. Histopathological analysis revealed 84 malignant lesions and seven benign lesions. The sensitivity, specificity, and accuracy levels of the CT scanning were 94.6%, 58.6%, and 78.9%. Helical scanning alone revealed additional contralateral carcinomas in three of four patients and additional ipsilateral carcinomas in three of five patients. However, the technique gave false-positive readings in 24 patients. The preoperative CT-mammogram altered the surgical method in six patients. Dynamic helical CT-mammography in the prone position may be one of the choices of adjunct imaging in patients with suspected breast cancer scheduled for surgery. (author)

  5. Introduction to the m = 1 helicity source

    International Nuclear Information System (INIS)

    Platts, D.A.; Jarboe, T.R.; Wright, B.L.

    1985-01-01

    The m = 1 Helicity Source, formerly called the Kinked Z-pinch, was developed as part of the Electrode Studies program at Los Alamos. The Electrode Studies program was initiated to study the control of electrode erosion in long discharge duration spheromak sources. Erosion control is necessary to reduce plasma impurities and to obtain adequate electrode lifetimes. The first task of the Electrode Studies program is to determine, from among a variety of configurations including the coaxial one, a helicity source geometry with good prospects for erosion control. The more efficient the helicity source the easier it will be to control erosion, but the source most also be easy to diagnose and modify if it is to be a useful test bed. The various erosion control techniques which have been proposed will require extensive experimentation to evaluate and optimize. Proposed techniques include, using refractory metals, profiling of the electrodes and magnetic fields, and various gas injection schemes including porous electrodes. It is considered necessary to do these experiments on an optimized helicity source so that the electrode geometries and plasma properties will be relevant. Therefore the present Electrode Studies program is aimed at developing an improved helicity source design

  6. Phytosterol glycosides reduce cholesterol absorption in humans

    OpenAIRE

    Lin, Xiaobo; Ma, Lina; Racette, Susan B.; Anderson Spearie, Catherine L.; Ostlund, Richard E.

    2009-01-01

    Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series ...

  7. Capillary origami: superhydrophobic ribbon surfaces and liquid marbles

    Directory of Open Access Journals (Sweden)

    Glen McHale

    2011-03-01

    Full Text Available In the wetting of a solid by a liquid it is often assumed that the substrate is rigid. However, for an elastic substrate the rigidity depends on the cube of its thickness and so reduces rapidly as the substrate becomes thinner as it approaches becoming a thin sheet. In such circumstances, it has been shown that the capillary forces caused by a contacting droplet of a liquid can shape the solid rather than the solid shaping the liquid. A substrate can be bent and folded as a (pinned droplet evaporates or even instantaneously and spontaneously wrapped on contact with a droplet. When this effect is used to create three dimensional shapes from initially flat sheets, the effect is called capillary origami or droplet wrapping.In this work, we consider how the conditions for the spontaneous, capillary induced, folding of a thin ribbon substrate might be altered by a rigid surface structure that, for a rigid substrate, would be expected to create Cassie–Baxter and Wenzel effects. For smooth thin substrates, droplet wrapping can occur for all liquids, including those for which the Young’s law contact angle (defined by the interfacial tensions is greater than 90° and which would therefore normally be considered relatively hydrophobic. However, consideration of the balance between bending and interfacial energies suggests that the tendency for droplet wrapping can be suppressed for some liquids by providing the flexible solid surface with a rigid topographic structure. In general, it is known that when a liquid interacts with such a structure it can either fully penetrate the structure (the Wenzel case or it can bridge between the asperities of the structure (the Cassie–Baxter case.In this report, we show theoretically that droplet wrapping should occur with both types of solid–liquid contact. We also derive a condition for the transition between the Cassie–Baxter and Wenzel type droplet wrapping and relate it to the same transition condition

  8. Position of the IBEX ribbon as a key to understand its origin

    Science.gov (United States)

    Swaczyna, Pawel; Bzowski, Maciej; Sokół, Justyna M.; Christian, Eric R.; Funsten, Herbert O.; McComas, David J.; Schwadron, Nathan A.

    2017-04-01

    Observations of the energetic neutral atom (ENA) emission by the Interstellar Boundary Explorer (IBEX) allow for remote sensing of the plasma properties in heliosheath. The first IBEX results revealed an unexpected arc-like enhancement of the ENA flux in the sky, dubbed the IBEX ribbon. This discovery led to formulation of more than a dozen hypotheses on its origin. The emission source region proposed in these hypotheses span the heliospheric termination shock up to a hypothetical nearby interface between the Local Interstellar Cloud and a local bay in the Local Bubble. Among these hypotheses is the concept that the ribbon is produced by the secondary ENA mechanism, operating in the outer heliosheath. The observational strategy of IBEX allows observation of the same part of the sky from the opposite sides of the Sun every six months and thus provides parallax viewing with a baseline of 2 AU. After correcting the observations for the Compton-Getting effect and for gravitational deflection and radiation pressure, we use this parallax viewing to precisely determine the apparent position of the maximum flux associated with the ribbon. We find that the ribbon peak position differs semi-annually by an angle of 0.41±0.15 deg, which we interpret as the parallax effect. This angle corresponds to a distance of 140-38+84 AU, and thus suggests that most likely the ribbon's source is located just beyond the heliopause. Comparison of the IBEX ribbon position in five energy steps of IBEX-Hi shows a systematic shift, which changes the position of the ribbon center by ˜10 deg. We find that it can be explained using an analytic model of the secondary ENA mechanism with the neutralized supersonic solar wind as the source of the primary ENAs, which are ionized in the outer heliosheath, picked up by the ambient magnetic field, and eventually re-neutralized (as originally conceived, McComas et al. 2009). We use a realistic model of the solar wind evolution dependent on heliographic

  9. Intestinal cholesterol secretion: future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  10. Intestinal cholesterol secretion : future clinical implications

    NARCIS (Netherlands)

    Jakulj, L.; Besseling, J.; Stroes, E. S. G.; Groen, A. K.

    2013-01-01

    Together with the liver, the intestine serves as a homeostatic organ in cholesterol metabolism. Recent evidence has substantiated the pivotal role of the intestine in reverse cholesterol transport (RCT). RCT is a fundamental antiatherogenic pathway, mediating the removal of cholesterol from tissues

  11. Isolation of Cholesterol from an Egg Yolk

    Science.gov (United States)

    Taber, Douglass F.; Li, Rui; Anson, Cory M.

    2011-01-01

    A simple procedure for the isolation of the cholesterol, by hydrolysis and extraction followed by column chromatography, is described. The cholesterol can be further purified by complexation with oxalic acid. It can also be oxidized and conjugated to cholestenone. The source of the cholesterol is one egg yolk, which contains about 200 mg of…

  12. Topical cholesterol in clofazimine induced ichthyosis

    Directory of Open Access Journals (Sweden)

    Pandey S

    1994-01-01

    Full Text Available Topical application of 10% cholesterol in petrolatum significantly (P< 0.05 controlled the development of ichthyosis in 62 patients taking 100 mg clofazimine daily for a period of 3 months. However, topical cholesterol application did not affect the lowering of serum cholesterol induced by oral clofazimine. Probable mechanism of action is being discussed.

  13. Clinical application of helical CT colonography

    International Nuclear Information System (INIS)

    Zeng Huiliang; Zhu Xinjin; Liang Rujian; Liang Jianhao; Ou Weiqian; Wen Haomao

    2009-01-01

    Objective: To investigate the clinical value of 16-slice helical CT colonography in the diagnosis of colon tumor and polypus. Methods: 16-slice helical CT volumetric scanning was performed in 18 patients with colonic disease, including colonic tumor (n=16) and colonic polypus (n=2). 3D images, virtual endoscopy and multiplanar reformation were obtained in the AW4.1 workstation. CT appearances were compared with operation and fiberoptic colonoscopy. Results: Satisfied results were achieved from 18 patients, no difference found in results between CT colonography and operation in 16 patients with colonic tumor. Conclusion: 16-slice helical CT colonography is of great value in preoperative staging of colonic tumor and have a high value in clinical application. (authors)

  14. Helicity antenna showers for hadron colliders

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Nadine; Skands, Peter [Monash University, School of Physics and Astronomy, Clayton, VIC (Australia); Lifson, Andrew [Monash University, School of Physics and Astronomy, Clayton, VIC (Australia); ETH Zuerich, Zurich (Switzerland)

    2017-10-15

    We present a complete set of helicity-dependent 2 → 3 antenna functions for QCD initial- and final-state radiation. The functions are implemented in the Vincia shower Monte Carlo framework and are used to generate showers for hadron-collider processes in which helicities are explicitly sampled (and conserved) at each step of the evolution. Although not capturing the full effects of spin correlations, the explicit helicity sampling does permit a significantly faster evaluation of fixed-order matrix-element corrections. A further speed increase is achieved via the implementation of a new fast library of analytical MHV amplitudes, while matrix elements from Madgraph are used for non-MHV configurations. A few examples of applications to QCD 2 → 2 processes are given, comparing the newly released Vincia 2.200 to Pythia 8.226. (orig.)

  15. Manipulation of wavefront using helical metamaterials.

    Science.gov (United States)

    Yang, Zhenyu; Wang, Zhaokun; Tao, Huan; Zhao, Ming

    2016-08-08

    Helical metamaterials, a kind of 3-dimensional structure, has relatively strong coupling effect among the helical nano-wires. Therefore, it is expected to be a good candidate for generating phase shift and controlling wavefront with high efficiency. In this paper, using the finite-difference time-domain (FDTD) method, we studied the phase shift properties in the helical metamaterials. It is found that the phase shift occurs for both transmitted and reflected light waves. And the maximum of reflection coefficients can reach over 60%. In addition, the phase shift (φ) is dispersionless in the range of 600 nm to 860 nm, that is, it is only dominated by the initial angle (θ) of the helix. The relationship between them is φ = ± 2θ. Using Jones calculus we give a further explanation for these properties. Finally, by arranging the helixes in an array with a constant phase gradient, the phenomenon of anomalous refraction was also observed in a broad wavelength range.

  16. Helicity antenna showers for hadron colliders

    Science.gov (United States)

    Fischer, Nadine; Lifson, Andrew; Skands, Peter

    2017-10-01

    We present a complete set of helicity-dependent 2→ 3 antenna functions for QCD initial- and final-state radiation. The functions are implemented in the Vincia shower Monte Carlo framework and are used to generate showers for hadron-collider processes in which helicities are explicitly sampled (and conserved) at each step of the evolution. Although not capturing the full effects of spin correlations, the explicit helicity sampling does permit a significantly faster evaluation of fixed-order matrix-element corrections. A further speed increase is achieved via the implementation of a new fast library of analytical MHV amplitudes, while matrix elements from Madgraph are used for non-MHV configurations. A few examples of applications to QCD 2→ 2 processes are given, comparing the newly released Vincia 2.200 to Pythia 8.226.

  17. Neutrino's helicity in a gravitational field

    International Nuclear Information System (INIS)

    Pansart, J.P.

    1996-01-01

    By using approximated solutions of Dirac's equation, we show that there is no helicity reversal for light neutrinos in the Schwarzschild metric nor in an expanding universe. The actual coupling between a particle spin and the angular momentum of a heavy rotating body induces a possible helicity reversal but with an unobservable probability proportional to m 2 p / E 2 , where m p is the particle mass and E its energy. In these calculations, the helicity is defined through the spin orientation with respect to the current and not with respect to the linear momentum. This definition gives simple expressions and is equal to the usual definition in the case of a flat space. (N.T.)

  18. Single-superfield helical-phase inflation

    Energy Technology Data Exchange (ETDEWEB)

    Ketov, Sergei V., E-mail: ketov@tmu.ac.jp [Department of Physics, Tokyo Metropolitan University, Minami-ohsawa 1-1, Hachioji-shi, Tokyo 192-0397 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Chiba 277-8568 (Japan); Institute of Physics and Technology, Tomsk Polytechnic University, 30 Lenin Ave., Tomsk 634050 (Russian Federation); Terada, Takahiro, E-mail: takahiro@hep-th.phys.s.u-tokyo.ac.jp [Department of Physics, The University of Tokyo, Tokyo 113-0033 (Japan); Deutsches Elektronen-Synchrotron (DESY), 22607 Hamburg (Germany)

    2016-01-10

    Large-field inflation in supergravity requires the approximate global symmetry needed to protect flatness of the scalar potential. In helical-phase inflation, the U(1) symmetry of the Kähler potential is assumed, the phase part of the complex scalar of a chiral superfield plays the role of inflaton, and the radial part is strongly stabilized. The original model of helical phase inflation, proposed by Li, Li and Nanopoulos (LLN), employs an extra (stabilizer) superfield. We propose a more economical new class of the helical phase inflationary models without a stabilizer superfield. As the specific examples, the quadratic, the natural, and the Starobinsky-type inflationary models are studied in our approach.

  19. Resonant helical fields in the TBR tokamak

    International Nuclear Information System (INIS)

    Bender, O.W.

    1986-01-01

    The influence of external resonant helical fields (RHF) in the tokamak TBR plasma discharges was investigated. These fields were created by helical windings wounded on the TBR vessel with the same helicity of rational magnetic surfaces, producing resonant efects on these surfaces. The characteristics of the MHZ activity (amplitude, frequency and poloidal and toroidal wave numbers, m=2,3,4 and n=1, respectively) during the plasma discharges were modified by eletrical winding currents of the order of 2% of the plasma current. These characterisitics were measured for diferent discharges safety factors at the limiter (q) between 3 and 4, with and without the RHF, with the atenuation of the oscillation amplitudes and the increasing of their frequencies. The existente of expontaneous and induced magnetic islands were investigated. The data were compared with results obtained in other tokamaks. (author) [pt

  20. The helical structure of DNA facilitates binding

    International Nuclear Information System (INIS)

    Berg, Otto G; Mahmutovic, Anel; Marklund, Emil; Elf, Johan

    2016-01-01

    The helical structure of DNA imposes constraints on the rate of diffusion-limited protein binding. Here we solve the reaction–diffusion equations for DNA-like geometries and extend with simulations when necessary. We find that the helical structure can make binding to the DNA more than twice as fast compared to a case where DNA would be reactive only along one side. We also find that this rate advantage remains when the contributions from steric constraints and rotational diffusion of the DNA-binding protein are included. Furthermore, we find that the association rate is insensitive to changes in the steric constraints on the DNA in the helix geometry, while it is much more dependent on the steric constraints on the DNA-binding protein. We conclude that the helical structure of DNA facilitates the nonspecific binding of transcription factors and structural DNA-binding proteins in general. (paper)

  1. Peptide mediators of cholesterol efflux

    Energy Technology Data Exchange (ETDEWEB)

    Bielicki, John K.; Johansson, Jan

    2013-04-09

    The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABAC1 that parallels that of full-length apolipoproteins. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia and inflammation.

  2. Turbulent Helicity in the Atmospheric Boundary Layer

    Science.gov (United States)

    Chkhetiani, Otto G.; Kurgansky, Michael V.; Vazaeva, Natalia V.

    2018-05-01

    We consider the assumption postulated by Deusebio and Lindborg (J Fluid Mech 755:654-671, 2014) that the helicity injected into the Ekman boundary layer undergoes a cascade, with preservation of its sign (right- or alternatively left-handedness), which is a signature of the system rotation, from large to small scales, down to the Kolmogorov microscale of turbulence. At the same time, recent direct field measurements of turbulent helicity in the steppe region of southern Russia near Tsimlyansk Reservoir show the opposite sign of helicity from that expected. A possible explanation for this phenomenon may be the joint action of different scales of atmospheric flows within the boundary layer, including the sea-breeze circulation over the test site. In this regard, we consider a superposition of the classic Ekman spiral solution and Prandtl's jet-like slope-wind profile to describe the planetary boundary-layer wind structure. The latter solution mimics a hydrostatic shallow breeze circulation over a non-uniformly heated surface. A 180°-wide sector on the hodograph plane exists, within which the relative orientation of the Ekman and Prandtl velocity profiles favours the left rotation with height of the resulting wind velocity vector in the lowermost part of the boundary layer. This explains the negative (left-handed) helicity cascade toward small-scale turbulent motions, which agrees with the direct field measurements of turbulent helicity in Tsimlyansk. A simple turbulent relaxation model is proposed that explains the measured positive values of the relatively minor contribution to turbulent helicity from the vertical components of velocity and vorticity.

  3. THE NATURE OF FLARE RIBBONS IN CORONAL NULL-POINT TOPOLOGY

    International Nuclear Information System (INIS)

    Masson, S.; Aulanier, G.; Pariat, E.; Schrijver, C. J.

    2009-01-01

    Flare ribbons are commonly attributed to the low-altitude impact, along the footprints of separatrices or quasi-separatrix layers (QSLs), of particle beams accelerated through magnetic reconnection. If reconnection occurs at a three-dimensional coronal magnetic null point, the footprint of the dome-shaped fan surface would map a closed circular ribbon. This paper addresses the following issues: does the entire circular ribbon brighten simultaneously, as expected because all fan field lines pass through the null point? And since the spine separatrices are singular field lines, do spine-related ribbons look like compact kernels? What can we learn from these observations about current sheet formation and magnetic reconnection in a null-point topology? The present study addresses these questions by analyzing Transition Region and Coronal Explorer and Solar and Heliospheric Observatory/Michelson Doppler Imager observations of a confined flare presenting a circular ribbon. Using a potential field extrapolation, we linked the circular shape of the ribbon with the photospheric mapping of the fan field lines originating from a coronal null point. Observations show that the flare ribbon outlining the fan lines brightens sequentially along the counterclockwise direction and that the spine-related ribbons are elongated. Using the potential field extrapolation as initial condition, we conduct a low-β resistive magnetohydrodynamics simulation of this observed event. We drive the coronal evolution by line-tied diverging boundary motions, so as to emulate the observed photospheric flow pattern associated with some magnetic flux emergence. The numerical analysis allows us to explain several observed features of the confined flare. The vorticity induced in the fan by the prescribed motions causes the spines to tear apart along the fan. This leads to formation of a thin current sheet and induces null-point reconnection. We also find that the null point and its associated topological

  4. Cholesterol Depletion from a Ceramide/Cholesterol Mixed Monolayer: A Brewster Angle Microscope Study

    KAUST Repository

    Mandal, Pritam

    2016-06-01

    Cholesterol is crucial to the mechanical properties of cell membranes that are important to cells’ behavior. Its depletion from the cell membranes could be dramatic. Among cyclodextrins (CDs), methyl beta cyclodextrin (MβCD) is the most efficient to deplete cholesterol (Chol) from biomembranes. Here, we focus on the depletion of cholesterol from a C16 ceramide/cholesterol (C16-Cer/Chol) mixed monolayer using MβCD. While the removal of cholesterol by MβCD depends on the cholesterol concentration in most mixed lipid monolayers, it does not depend very much on the concentration of cholesterol in C16-Cer/Chol monolayers. The surface pressure decay during depletion were described by a stretched exponential that suggested that the cholesterol molecules are unable to diffuse laterally and behave like static traps for the MβCD molecules. Cholesterol depletion causes morphology changes of domains but these disrupted monolayers domains seem to reform even when cholesterol level was low.

  5. Relationship between plasma cholesterol levels and cholesterol esterification in isolated human mononuclear cells

    International Nuclear Information System (INIS)

    Dallongeville, J.; Davignon, J.; Lussier-Cacan, S.

    1990-01-01

    The authors studied the relationship between plasma lipoprotein concentrations and cholesterol esterification in freshly isolated human mononuclear cells from 27 normolipidemic and 32 hyperlipidemic individuals. Cells were either incubated for 5 hours with radiolabeled oleate immediately after isolation or were preincubated for 18 hours in the presence of exogenous cholesterol, and then incubated with [ 14 C]sodium-oleate-albumin complex. In the absence of exogenous cholesterol, control and hypercholesterolemic subjects had similarly low values of intracellular cholesterol esterification. In the presence of exogenous cholesterol, both hypertriglyceridemic and hypercholesterolemic subjects had higher cholesterol esterification than controls. There was a significant correlation between the rate of cholesterol esterification and plasma total cholesterol. These results suggest that plasma cholesterol levels may regulate mononuclear cell intra-cellular cholesterol esterification in humans

  6. Nonideal, helical, vortical magnetohydrodynamic steady states

    International Nuclear Information System (INIS)

    Agim, Y.Z.; Montgomery, D.

    1991-01-01

    The helically-deformed profiles of driven, dissipative magnetohydrodynamic equilibria are constructed through second order in helical amplitude. The resultant plasma configurations are presented in terms of contour plots of magnetic flux function, pressure, current flux function and the mass flux function, along with the stability boundary at which they are expected to appear. For the Wisconsin Phaedrus-T Tokamak, plasma profiles with significant m = 3, n = 1 perturbation seem feasible; for these, the plasma pressure peaks off-axis. For the smaller aspect ratio case, the configuration with m 1,n =1 is thought to be relevant to the density perturbation observed in JET after a pellet injection. (author)

  7. Equilibrium calculations for helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.

    1984-04-01

    An average method based on a vacuum flux coordinate system is presented. This average method permits the study of helical axis stellarators with toroidally dominated shifts. An ordering is introduced, and to lowest order the toroidally averaged equilibrium equations are reduced to a Grad-Shafranov equation. Also, to lowest order, a Poisson-type equation is obtained for the toroidally varying corrections to the equilibium. By including these corrections, systems that are toroidally dominated, but with significant helical distortion to the equilibrium, may be studied. Numerical solutions of the average method equations are shown to agree well with three-dimensional calculations

  8. Helical post stellarator. Part 1: Vacuum configuration

    International Nuclear Information System (INIS)

    Moroz, P.E.

    1997-08-01

    Results on a novel type of stellarator configuration, the Helical Post Stellarator (HPS), are presented. This configuration is different significantly from all previously known stellarators due to its unique geometrical characteristics and unique physical properties. Among those are: the magnetic field has only one toroidal period (M = 1), the plasma has an extremely low aspect ratio, A ∼ 1, and the variation of the magnetic field, B, along field lines features a helical ripple on the inside of the torus. Among the main advantages of a HPS for a fusion program are extremely compact, modular, and simple design compatible with significant rotational transform, large plasma volume, and improved particle transport characteristics

  9. Equilibrium studies of helical axis stellarators

    International Nuclear Information System (INIS)

    Hender, T.C.; Carreras, B.A.; Garcia, L.; Harris, J.H.; Rome, J.A.; Cantrell, J.L.; Lynch, V.E.

    1984-01-01

    The equilibrium properties of helical axis stellarators are studied with a 3-D equilibrium code and with an average method (2-D). The helical axis ATF is shown to have a toroidally dominated equilibrium shift and good equilibria up to at least 10% peak beta. Low aspect ratio heliacs, with relatively large toroidal shifts, are shown to have low equilibrium beta limits (approx. 5%). Increasing the aspect ratio and number of field periods proportionally is found to improve the equilibrium beta limit. Alternatively, increasing the number of field periods at fixed aspect ratio which raises and lowers the toroidal shift improves the equilibrium beta limit

  10. Conversion from mutual helicity to self-helicity observed with IRIS

    Science.gov (United States)

    Li, L. P.; Peter, H.; Chen, F.; Zhang, J.

    2014-10-01

    Context. In the upper atmosphere of the Sun observations show convincing evidence for crossing and twisted structures, which are interpreted as mutual helicity and self-helicity. Aims: We use observations with the new Interface Region Imaging Spectrograph (IRIS) to show the conversion of mutual helicity into self-helicity in coronal structures on the Sun. Methods: Using far UV spectra and slit-jaw images from IRIS and coronal images and magnetograms from SDO, we investigated the evolution of two crossing loops in an active region, in particular, the properties of the Si IV line profile in cool loops. Results: In the early stage two cool loops cross each other and accordingly have mutual helicity. The Doppler shifts in the loops indicate that they wind around each other. As a consequence, near the crossing point of the loops (interchange) reconnection sets in, which heats the plasma. This is consistent with the observed increase of the line width and of the appearance of the loops at higher temperatures. After this interaction, the two new loops run in parallel, and in one of them shows a clear spectral tilt of the Si IV line profile. This is indicative of a helical (twisting) motion, which is the same as to say that the loop has self-helicity. Conclusions: The high spatial and spectral resolution of IRIS allowed us to see the conversion of mutual helicity to self-helicity in the (interchange) reconnection of two loops. This is observational evidence for earlier theoretical speculations. Movie associated with Fig. 1 and Appendix A are available in electronic form at http://www.aanda.org

  11. Analysis of Cholesterol Trafficking with Fluorescent Probes

    DEFF Research Database (Denmark)

    Maxfield, Frederick R.; Wustner, Daniel

    2012-01-01

    Cholesterol plays an important role in determining the biophysical properties of biological membranes, and its concentration is tightly controlled by homeostatic processes. The intracellular transport of cholesterol among organelles is a key part of the homeostatic mechanism, but sterol transport...... that can bind to cholesterol to reveal its distribution in cells. We also discuss the use of intrinsically fluorescent sterols that closely mimic cholesterol, as well as some minimally modified fluorophore-labeled sterols. Methods for imaging these sterols by conventional fluorescence microscopy...... and by multiphoton microscopy are described. Some label-free methods for imaging cholesterol itself are also discussed briefly....

  12. Biliary cholesterol secretion : More than a simple ABC

    NARCIS (Netherlands)

    Dikkers, Arne; Tietge, Uwe J. F.

    2010-01-01

    Biliary cholesterol secretion is a process important for 2 major disease complexes, atherosclerotic cardiovascular disease and cholesterol gallstone disease With respect to cardiovascular disease, biliary cholesterol secretion is regarded as the final step for the elimination of cholesterol

  13. Intestinal Farnesoid X Receptor Controls Transintestinal Cholesterol Excretion in Mice

    NARCIS (Netherlands)

    Boer, J.F. de; Schonewille, M.; Boesjes, M.; Wolters, H.; Bloks, V.W.; Bos, T.; Dijk, T.H. van; Jurdzinski, A.; Boverhof, R.; Wolters, J.C.; Kuivenhoven, J.A.; Deursen, J.M.A. van; Elferink, R.P.; Moschetta, A.; Kremoser, C.; Verkade, H.J.; Kuipers, F.; Groen, A.K.

    2017-01-01

    BACKGROUND & AIMS: The role of the intestine in the maintenance of cholesterol homeostasis increasingly is recognized. Fecal excretion of cholesterol is the last step in the atheroprotective reverse cholesterol transport pathway, to which biliary and transintestinal cholesterol excretion (TICE)

  14. Intracellular transport of cholesterol in mammalian cells

    International Nuclear Information System (INIS)

    Brasaemle, D.L.

    1989-01-01

    The erythrocyte was selected as a simple cell for the study of transbilayer movement of cholesterol. Cholesterol oxidase was used to measure the distribution of [ 3 H]cholesterol across the erythrocyte membrane. Cholesterol oxidase was also used to estimate the rate of transport of low density lipoprotein (LDL) cholesterol to the plasma membrane of cultured Chinese hamster ovary (CHO) fibroblasts; the half-time of this process was 42 minutes. The rate of transport of LDL cholesterol to the plasma membrane was confirmed by a second procedure using amphotericin B. Amphotericin B was also used to estimate the rate of transport of endogenously synthesized cholesterol to the plasma membrane of CHO cells. New methodology was developed including improvements of the previously published cholesterol oxidase assay for plasma membrane cholesterol. A new method for detecting transport of cholesterol to the plasma membrane in cultured cells was developed using amphotericin B. Preliminary studies investigated the use of fluorescent polyenes, pimaricin and etruscomycin, as probes for plasma membrane cholesterol in transport studies. Finally, a modification of a previously published cell staining protocol yielded a simple, quantitative assay for cell growth

  15. Cholesterol

    Science.gov (United States)

    ... eating habits, such as eating lots of bad fats. One type, saturated fat, is found in some meats, dairy products, chocolate, ... goods, and deep-fried and processed foods. Another type, trans fat, is in some fried and processed foods. Eating ...

  16. Trapping crystal nucleation of cholesterol monohydrate

    DEFF Research Database (Denmark)

    Solomonov, I.; Weygand, M.J.; Kjær, K.

    2005-01-01

    Crystalline nucleation of cholesterol at the air-water interface has been studied via grazing incidence x-ray diffraction using synchrotron radiation. The various stages of cholesterol molecular assembly from monolayer to three bilayers incorporating interleaving hydrogen-bonded water layers......, at least initially, an intralayer cholesterol rearrangement in a single-crystal-to-single-crystal transition. The preferred nucleation of the monoclinic phase of cholesterol . H2O followed by transformation to the stable monohydrate phase may be associated with an energetically more stable cholesterol...... bilayer arrangement of the former and a more favorable hydrogen-bonding arrangement of the latter. The relevance of this nucleation process of cholesterol monohydrate to pathological crystallization of cholesterol from cell biomembranes is discussed....

  17. Development of variable width ribbon heating elements for liquid metal and gas-cooled fast breeder reactor fuel rod simulators

    International Nuclear Information System (INIS)

    McCulloch, R.W.; Lovell, R.T.; Post, D.W.; Snyder, S.D.

    1980-01-01

    Variable width ribbon heating elements have been fabricated which provide a chopped cosine, variable heat flux profile for fuel rod simulators used in test loops by the Breeder Reactor Program Thermal Hydraulic Out-of-Reactor Safety test facility and the Gas-Cooled Fast Breeder Reactor Core Flow Test Loop. Thermal, mechanical, and electrical design considerations result in the derivation of an analytical expression for the ribbon contours. From this, the ribbons are machined and wound on numerically controlled equipment. Postprocessing and inspection results in a wound, variable width ribbon with the precise dimensional, electrical, and mechanical properties needed for use in fuel pin simulators

  18. Silicon ribbon growth by a capillary action shaping technique. Annual report (Quarterly technical progress report No. 9)

    Energy Technology Data Exchange (ETDEWEB)

    Schwuttke, G.H.; Ciszek, T.F.; Kran, A.

    1977-10-01

    Progress on the technological and economical assessment of ribbon growth of silicon by a capillary action shaping technique is reported. Progress in scale-up of the process from 50 mm to 100 mm ribbon widths is presented, the use of vitreous carbon as a crucible material is analyzed, and preliminary tests of CVD Si/sub 3/N/sub 4/ as a potential die material are reported. Diffusion length measurements by SEM, equipment and procedure for defect display under MOS structure in silicon ribbon for lifetime interpretation, and an assessment of ribbon technology are discussed. (WHK)

  19. Dynamics and deformability of α-, 310- and π-helices

    Directory of Open Access Journals (Sweden)

    Narwani Tarun Jairaj

    2018-01-01

    Full Text Available Protein structures are often represented as seen in crystals as (i rigid macromolecules (ii with helices, sheets and coils. However, both definitions are partial because (i proteins are highly dynamic macromolecules and (ii the description of protein structures could be more precise. With regard to these two points, we analyzed and quantified the stability of helices by considering α-helices as well as 310- and π-helices. Molecular dynamic (MD simulations were performed on a large set of 169 representative protein domains. The local protein conformations were followed during each simulation and analyzed. The classical flexibility index (B-factor was confronted with the MD root mean square flexibility (RMSF index. Helical regions were classified according to their level of helicity from high to none. For the first time, a precise quantification showed the percentage of rigid and flexible helices that underlie unexpected behaviors. Only 76.4% of the residues associated with α-helices retain the conformation, while this tendency drops to 40.5% for 310-helices and is never observed for π-helices. α-helix residues that do not remain as an α-helix have a higher tendency to assume β-turn conformations than 310- or π-helices. The 310-helices that switch to the α-helix conformation have a higher B-factor and RMSF values than the average 310-helix but are associated with a lower accessibility. Rare π-helices assume a β-turn, bend and coil conformations, but not α- or 310-helices. The view on π-helices drastically changes with the new DSSP (Dictionary of Secondary Structure of Proteins assignment approach, leading to behavior similar to 310-helices, thus underlining the importance of secondary structure assignment methods.

  20. Review of the helicity formalism; Revision del formalismo de helicidad

    Energy Technology Data Exchange (ETDEWEB)

    Barreiro, F; Cerrada, M; Fernandez, E

    1972-07-01

    Our purpose in these notes has been to present a brief and general review of the helicity formalism. We begin by discussing Lorentz invariance, spin and helicity ideas, in section 1 . In section 2 we deal with the construction of relativistic states and scattering amplitudes in the helicity basis and we study their transformation properties under discrete symmetries. Finally we present some more sophisticated topics like kinematical singularities of helicity amplitudes, kinematical constraints and crossing relations 3, 4, 5 respectively. (Author) 8 refs.

  1. Exabyte helical scan devices at Fermilab

    International Nuclear Information System (INIS)

    Constanta-Fanourakis, P.; Kaczar, K.; Oleynik, G.; Petravick, D.; Votava, M.; White, V.; Hockney, G.; Bracker, S.; de Miranda, J.M.

    1989-05-01

    Exabyte 8mm helical scan storage devices are in use at Fermilab in a number of applications. These devices have the functionality of magnetic tape, but use media which is much more economical and much more dense than conventional 9 track tape. 6 refs., 3 figs

  2. Helical axial injection concept for cyclotrons

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, E.D.

    1981-01-01

    A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical.

  3. Helical axial injection concept for cyclotrons

    International Nuclear Information System (INIS)

    Hudson, E.D.

    1981-01-01

    A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical

  4. Electron image reconstruction of helical protein assemblies

    International Nuclear Information System (INIS)

    Cremers, A.F.M.

    1980-01-01

    The analysis of projections of large ordered biological systems obtained by electron microscopy of negatively stained specimens is described. The biological structures amenable to this approach are constructed from a large number of identical protein molecules, which are arranged according to helical symmetry. Electron images of these structures generally contain sufficient information in order to calculate a three-dimensional density map. (Auth.)

  5. Adaptive radiotherapy using helical tomotherapy system

    International Nuclear Information System (INIS)

    Jeswani, Sam; Ruchala, Kenneth; Olivera, Gustavo; Mackie, T.R.

    2008-01-01

    As commonly known in the field, adaptive radiation therapy (ART) is the use of feedback to modify a radiotherapy treatment. There are numerous ways in which this feedback can be received and used, and this presentation will discuss some of the implementations of ART being investigated with a helical TomoTherapy system

  6. Topological characteristics of helical repeat proteins

    NARCIS (Netherlands)

    Groves, M R; Barford, D

    The recent elucidation of protein structures based upon repeating amino acid motifs, including the armadillo motif, the HEAT motif and tetratricopeptide repeats, reveals that they belong to the class of helical repeat proteins. These proteins share the common property of being assembled from tandem

  7. A Prospective Evaluation of Helical Tomotherapy

    International Nuclear Information System (INIS)

    Bauman, Glenn; Yartsev, Slav; Rodrigues, George; Lewis, Craig; Venkatesan, Varagur M.; Yu, Edward; Hammond, Alex; Perera, Francisco; Ash, Robert; Dar, A. Rashid; Lock, Michael; Baily, Laura; Coad, Terry C; Trenka, Kris C.; Warr, Barbara; Kron, Tomas; Battista, Jerry; Van Dyk, Jake

    2007-01-01

    Purpose: To report results from two clinical trials evaluating helical tomotherapy (HT). Methods and Materials: Patients were enrolled in one of two prospective trials of HT (one for palliative and one for radical treatment). Both an HT plan and a companion three-dimensional conformal radiotherapy (3D-CRT) plan were generated. Pretreatment megavoltage computed tomography was used for daily image guidance. Results: From September 2004 to January 2006, a total of 61 sites in 60 patients were treated. In all but one case, a clinically acceptable tomotherapy plan for treatment was generated. Helical tomotherapy plans were subjectively equivalent or superior to 3D-CRT in 95% of plans. Helical tomotherapy was deemed equivalent or superior in two thirds of dose-volume point comparisons. In cases of inferiority, differences were either clinically insignificant and/or reflected deliberate tradeoffs to optimize the HT plan. Overall imaging and treatment time (median) was 27 min (range, 16-91 min). According to a patient questionnaire, 78% of patients were satisfied to very satisfied with the treatment process. Conclusions: Helical tomotherapy demonstrated clear advantages over conventional 3D-CRT in this diverse patient group. The prospective trials were helpful in deploying this technology in a busy clinical setting

  8. Helicity-flip in particle production on nuclei

    International Nuclear Information System (INIS)

    Faeldt, G.

    1977-01-01

    Coherent nuclear production processes are generally analyzed assuming helicity conserving production amplitudes. In view of the uncertainties of the actual helicity structure this could be a dangerous assumption. It is shown that helicity-flip contributions might be part of the explanation of the small effective (pππ)-nucleon cross sections observed in coherent production. (Auth.)

  9. A real-scale helical coil winding trial of the Large Helical Device

    International Nuclear Information System (INIS)

    Senba, T.; Yamamoto, T.; Tamaki, T.; Asano, K.; Suzuki, S.; Yamauchi, T.; Uchida, K.; Nakanishi, K.; Yamagiwa, T.; Suzuki, S.; Miyoshi, R.; Sasa, H.; Watanabe, S.; Tatemura, M.; Hatada, N.; Yamaguchi, S.; Imagawa, S.; Yanagi, N.; Satow, T.; Yamamoto, J.; Motojima, O.

    1995-01-01

    A real-scale helical coil winding trial of the Large Helical Device (LHD) has been conducted for a study of coil winding configuration and winding methods and for exhibiting the state of the art. It includes construction and test run of a specifically designed winding machine and development of various manufacturing methods for accurate coil winding. It has been carried out in Hitachi Works before in situ winding, and has provided much needed engineering data for construction of the LHD. (orig.)

  10. Mena-GRASP65 interaction couples actin polymerization to Golgi ribbon linking.

    Science.gov (United States)

    Tang, Danming; Zhang, Xiaoyan; Huang, Shijiao; Yuan, Hebao; Li, Jie; Wang, Yanzhuang

    2016-01-01

    In mammalian cells, the Golgi reassembly stacking protein 65 (GRASP65) has been implicated in both Golgi stacking and ribbon linking by forming trans-oligomers through the N-terminal GRASP domain. Because the GRASP domain is globular and relatively small, but the gaps between stacks are large and heterogeneous, it remains puzzling how GRASP65 physically links Golgi stacks into a ribbon. To explore the possibility that other proteins may help GRASP65 in ribbon linking, we used biochemical methods and identified the actin elongation factor Mena as a novel GRASP65-binding protein. Mena is recruited onto the Golgi membranes through interaction with GRASP65. Depleting Mena or disrupting actin polymerization resulted in Golgi fragmentation. In cells, Mena and actin were required for Golgi ribbon formation after nocodazole washout; in vitro, Mena and microfilaments enhanced GRASP65 oligomerization and Golgi membrane fusion. Thus Mena interacts with GRASP65 to promote local actin polymerization, which facilitates Golgi ribbon linking. © 2016 Tang et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  11. Intracellular Cholesterol Trafficking and Impact in Neurodegeneration

    Directory of Open Access Journals (Sweden)

    Fabian Arenas

    2017-11-01

    Full Text Available Cholesterol is a critical component of membrane bilayers where it plays key structural and functional roles by regulating the activity of diverse signaling platforms and pathways. Particularly enriched in brain, cholesterol homeostasis in this organ is singular with respect to other tissues and exhibits a heterogeneous regulation in distinct brain cell populations. Due to the key role of cholesterol in brain physiology and function, alterations in cholesterol homeostasis and levels have been linked to brain diseases and neurodegeneration. In the case of Alzheimer disease (AD, however, this association remains unclear with evidence indicating that either increased or decreased total brain cholesterol levels contribute to this major neurodegenerative disease. Here, rather than analyzing the role of total cholesterol levels in neurodegeneration, we focus on the contribution of intracellular cholesterol pools, particularly in endolysosomes and mitochondria through its trafficking via specialized membrane domains delineated by the contacts between endoplasmic reticulum and mitochondria, in the onset of prevalent neurodegenerative diseases such as AD, Parkinson disease, and Huntington disease as well as in lysosomal disorders like Niemann-Pick type C disease. We dissect molecular events associated with intracellular cholesterol accumulation, especially in mitochondria, an event that results in impaired mitochondrial antioxidant defense and function. A better understanding of the mechanisms involved in the distribution of cholesterol in intracellular compartments may shed light on the role of cholesterol homeostasis disruption in neurodegeneration and may pave the way for specific intervention opportunities.

  12. The cholesterol space of the rat

    International Nuclear Information System (INIS)

    Chevallier, F.

    1959-01-01

    The experiments consisted in feeding daily to rats the same mass of radioactive cholesterol, over variable time intervals. From the evolution of the specific radioactivity of cholesterol carbon-14 in the organs as a function of time, information relative to the transport of cholesterol in the organism may be obtained. 1) The cholesterol space, defined as the group of molecules capable of being transferred from the organs into the serum and vice versa, represents at the most 50 per cent of the total cholesterol of the adult rat. 2) The incessant interchange between the tissual and the serum cholesterol renews entirely or for the most part the cholesterol molecules contained in the following organs: spleen, heart, adipose tissue, suprarenal glands, lungs, bone marrow, liver, erythrocytes. For a second group of organs: skin, testicles, kidneys, colon, bones, muscles, only a fraction of their cholesterol is renewable by this process. No transfer can be detected at the level of the brain. 3) The relative speeds of the various means of appearance (absorption, synthesis) and disappearance (excretion, transformation) of the cholesterol from its space are such that a stationary isotopic state is established around the eighth day, when the animal absorbs 5 milligrams of radioactive cholesterol daily. (author) [fr

  13. Bearing capacity of helical pile foundation in peat soil from different, diameter and spacing of helical plates

    Science.gov (United States)

    Fatnanta, F.; Satibi, S.; Muhardi

    2018-03-01

    In an area dominated by thick peat soil layers, driven piles foundation is often used. These piles are generally skin friction piles where the pile tips do not reach hard stratum. Since the bearing capacity of the piles rely on the resistance of their smooth skin, the bearing capacity of the piles are generally low. One way to increase the bearing capacity of the piles is by installing helical plates around the pile tips. Many research has been performed on helical pile foundation. However, literature on the use of helical pile foundation on peat soil is still hardly found. This research focus on the study of axial bearing capacity of helical pile foundation in peat soil, especially in Riau Province. These full-scale tests on helical pile foundation were performed in a rectangular box partially embedded into the ground. The box is filled with peat soil, which was taken from Rimbo Panjang area in the district of Kampar, Riau Province. Several helical piles with different number, diameter and spacing of the helical plates have been tested and analysed. The tests result show that helical pile with three helical plates of uniform diameter has better bearing capacity compared to other helical piles with varying diameter and different number of helical plates. The bearing capacity of helical pile foundation is affected by the spacing between helical plates. It is found that the effective helical plates spacing for helical pile foundation with diameter of 15cm to 35cm is between 20cm to 30cm. This behaviour may be considered to apply to other type of helical pile foundations in peat soil.

  14. Pyrolysis of Helical Coordination Polymers for Metal-Sulfide-Based Helices with Broadband Chiroptical Activity.

    Science.gov (United States)

    Hirai, Kenji; Yeom, Bongjun; Sada, Kazuki

    2017-06-27

    Fabrication of chiroptical materials with broadband response in the visible light region is vital to fully realize their potential applications. One way to achieve broadband chiroptical activity is to fabricate chiral nanostructures from materials that exhibit broadband absorption in the visible light region. However, the compounds used for chiroptical materials have predominantly been limited to materials with narrowband spectral response. Here, we synthesize Ag 2 S-based nanohelices derived from helical coordination polymers. The right- and left-handed coordination helices used as precursors are prepared from l- and d-glutathione with Ag + and a small amount of Cu 2+ . The pyrolysis of the coordination helices yields right- and left-handed helices of Cu 0.12 Ag 1.94 S/C, which exhibit chiroptical activity spanning the entire visible light region. Finite element method simulations substantiate that the broadband chiroptical activity is attributed to synergistic broadband light absorption and light scattering. Furthermore, another series of Cu 0.10 Ag 1.90 S/C nanohelices are synthesized by choosing the l- or d-Glu-Cys as starting materials. The pitch length of nanohelicies is controlled by changing the peptides, which alters their chiroptical properties. The pyrolysis of coordination helices enables one to fabricate helical Ag 2 S-based materials that enable broadband chiroptical activity but have not been explored owing to the lack of synthetic routes.

  15. The structure of SSO2064, the first representative of Pfam family PF01796, reveals a novel two-domain zinc-ribbon OB-fold architecture with a potential acyl-CoA-binding role

    International Nuclear Information System (INIS)

    Krishna, S. Sri; Aravind, L.; Bakolitsa, Constantina; Caruthers, Jonathan; Carlton, Dennis; Miller, Mitchell D.; Abdubek, Polat; Astakhova, Tamara; Axelrod, Herbert L; Chiu, Hsiu-Ju; Clayton, Thomas; Deller, Marc C.; Duan, Lian; Feuerhelm, Julie; Grant, Joanna C.; Han, Gye Won; Jaroszewski, Lukasz; Jin, Kevin K.; Klock, Heath E.; Knuth, Mark W.; Kumar, Abhinav; Marciano, David; McMullan, Daniel; Morse, Andrew T.; Nigoghossian, Edward; Okach, Linda; Reyes, Ron; Rife, Christopher L.; Bedem, Henry van den; Weekes, Dana; Xu, Qingping; Hodgson, Keith O.; Wooley, John; Elsliger, Marc-André; Deacon, Ashley M.; Godzik, Adam; Lesley, Scott A.; Wilson, Ian A.

    2010-01-01

    The crystal structure of SSO2064, the first structural representative of Pfam family PF01796 (DUF35), reveals a two-domain architecture comprising an N-terminal zinc-ribbon domain and a C-terminal OB-fold domain. Analysis of the domain architecture, operon organization and bacterial orthologs combined with the structural features of SSO2064 suggests a role involving acyl-CoA binding for this family of proteins. SSO2064 is the first structural representative of PF01796 (DUF35), a large prokaryotic family with a wide phylogenetic distribution. The structure reveals a novel two-domain architecture comprising an N-terminal, rubredoxin-like, zinc ribbon and a C-terminal, oligonucleotide/oligosaccharide-binding (OB) fold domain. Additional N-terminal helical segments may be involved in protein–protein interactions. Domain architectures, genomic context analysis and functional evidence from certain bacterial representatives of this family suggest that these proteins form a novel fatty-acid-binding component that is involved in the biosynthesis of lipids and polyketide antibiotics and that they possibly function as acyl-CoA-binding proteins. This structure has led to a re-evaluation of the DUF35 family, which has now been split into two entries in the latest Pfam release (v.24.0)

  16. Ion temperature gradient modes in toroidal helical systems

    Energy Technology Data Exchange (ETDEWEB)

    Kuroda, T. [Graduate University for Advanced Studies, Toki, Gifu (Japan); Sugama, H.; Kanno, R.; Okamoto, M.

    2000-04-01

    Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of {nabla}B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

  17. Ion temperature gradient modes in toroidal helical systems

    International Nuclear Information System (INIS)

    Kuroda, T.; Sugama, H.; Kanno, R.; Okamoto, M.

    2000-04-01

    Linear properties of ion temperature gradient (ITG) modes in helical systems are studied. The real frequency, growth rate, and eigenfunction are obtained for both stable and unstable cases by solving a kinetic integral equation with proper analytic continuation performed in the complex frequency plane. Based on the model magnetic configuration for toroidal helical systems like the Large Helical Device (LHD), dependences of the ITG mode properties on various plasma equilibrium parameters are investigated. Particularly, relative effects of ∇B-curvature drifts driven by the toroidicity and by the helical ripples are examined in order to compare the ITG modes in helical systems with those in tokamaks. (author)

  18. Raising HDL cholesterol in women

    Directory of Open Access Journals (Sweden)

    Danny J Eapen

    2009-11-01

    Full Text Available Danny J Eapen1, Girish L Kalra1, Luay Rifai1, Christina A Eapen2, Nadya Merchant1, Bobby V Khan11Emory University School of Medicine, Atlanta, GA, USA; 2University of South Florida School of Medicine, Tampa, FL, USAAbstract: High-density lipoprotein cholesterol (HDL-C concentration is essential in the determination of coronary heart disease (CHD risk in women. This is especially true in the postmenopausal state, where lipid profiles and CHD risk mimic that of age-matched men. Thus, interventions designed to reduce CHD risk by raising HDL-C levels may have particular significance during the transition to menopause. This review discusses HDL-C-raising therapies and the role of HDL in the primary prevention of CHD in women. Lifestyle-based interventions such as dietary change, aerobic exercise regimens, and smoking cessation are initial steps that are effective in raising HDL-C, and available data suggest women respond similarly to men with these interventions. When combined with pharmacotherapy, the effects of these lifestyle alterations are further amplified. Though studies demonstrating gender-specific differences in therapy are limited, niacin continues to be the most effective agent in raising HDL-C levels, especially when used in combination with fibrate or statin therapy. Emerging treatments such as HDL mimetic therapy show much promise in further raising HDL-C levels and improving cardiovascular outcomes.Keywords: high-density lipoprotein, HDL, women, cholesterol, heart disease

  19. Biot-Savart helicity versus physical helicity: A topological description of ideal flows

    Science.gov (United States)

    Sahihi, Taliya; Eshraghi, Homayoon

    2014-08-01

    For an isentropic (thus compressible) flow, fluid trajectories are considered as orbits of a family of one parameter, smooth, orientation-preserving, and nonsingular diffeomorphisms on a compact and smooth-boundary domain in the Euclidian 3-space which necessarily preserve a finite measure, later interpreted as the fluid mass. Under such diffeomorphisms the Biot-Savart helicity of the pushforward of a divergence-free and tangent to the boundary vector field is proved to be conserved and since these circumstances present an isentropic flow, the conservation of the "Biot-Savart helicity" is established for such flows. On the other hand, the well known helicity conservation in ideal flows which here we call it "physical helicity" is found to be an independent constant with respect to the Biot-Savart helicity. The difference between these two helicities reflects some topological features of the domain as well as the velocity and vorticity fields which is discussed and is shown for simply connected domains the two helicities coincide. The energy variation of the vorticity field is shown to be formally the same as for the incompressible flow obtained before. For fluid domains consisting of several disjoint solid tori, at each time, the harmonic knot subspace of smooth vector fields on the fluid domain is found to have two independent base sets with a special type of orthogonality between these two bases by which a topological description of the vortex and velocity fields depending on the helicity difference is achieved since this difference is shown to depend only on the harmonic knot parts of velocity, vorticity, and its Biot-Savart vector field. For an ideal magnetohydrodynamics (MHD) flow three independent constant helicities are reviewed while the helicity of magnetic potential is generalized for non-simply connected domains by inserting a special harmonic knot field in the dynamics of the magnetic potential. It is proved that the harmonic knot part of the vorticity

  20. Low-frequency magnetization processes in chemically etched Co-based amorphous ribbons

    International Nuclear Information System (INIS)

    Betancourt, I.; Martinez, L.A.; Valenzuela, R.

    2005-01-01

    In this report we present a study of the magnetization processes for Co-based amorphous ribbons at low frequencies (10 Hz-13 MHz) as a function of decreasing thicknesses attained by chemical etching. Reversible domain-wall bulging, characterized by initial permeability and relaxation frequency, was monitored by means of inductance measurements. The real part of inductance (proportional to initial permeability) exhibited a decreasing trend with diminishing ribbon thickness, together with an increasing tendency for the relaxation frequency. For high amplitude of the ac field (leading to domain-wall unpinning), reduced ribbon thickness showed a deleterious-enhancement effect on irreversible domain-wall displacement, which was observed for both real and imaginary inductance spectroscopic plots. Results are interpreted in terms of reduced domain-wall pinning distances resulting from thinner alloy samples

  1. Mechanical properties of metallic ribbons investigated by depth sensing indentation technique

    International Nuclear Information System (INIS)

    Pesek, Ladislav; Dobrzanski, Leszek A.; Zubko, Pavol; Konieczny, Jaroslaw

    2006-01-01

    The paper presents mechanical properties of two kinds of Co-based and one Fe-based metallic ribbons by the depth sensing indentation (DSI) technique. Investigations were carried out on two kinds ternary alloy Co 77 Si 11,5 B 11,5 and Fe 78 Si 13 B 9 and multicomponent Co 68 Fe 4 Mo 1 Si 13,5 B 13,5 , which are so-called 'zero-magnetostriction' materials. Metallic ribbons were investigated in amorphous state and partially crystallized state after annealing in 400deg. C in argon atmosphere. Heating of ribbons obtained by melt spinning technique was performed to check its effect on changes of mechanical properties

  2. ANALYSIS OF RIBBONING ON CONICAL YARN PACKAGE WOUND BY OPENEND SPINNING MACHINES

    Directory of Open Access Journals (Sweden)

    Resul FETTAHOV

    2001-03-01

    Full Text Available In this paper, Ribboning , one of the common faults in yarn packages, is mathematically analysed. If yarn is repeatly laid on top of or along the same path as the previously wound yarn, this duplication of yarn path on the package creates a defect known as ribboning. The number of turns of package (n per double traverse of yarn guide is calculated in two different way One is calculated the length of a coil on the package and total length of yarn in a double traverse; the other is considered transmission rate between drum and conical yarn package The result of two different approach is similar and the probable diameter of conical yarn package which ribboning is occurred is calculated and used on Schalafhorst-Autocore OE spinning machines.

  3. THE SURFACE STRUCTURAL AND MECHANICAL PROPERTIES OF THE AMORPHOUS CO22Y54AL24 RIBBON

    Directory of Open Access Journals (Sweden)

    Anna Bukowska

    2013-09-01

    Full Text Available The aim of this study was to manufacture amorphous Co22Y54Al24 alloy in a form of thin ribbons and to investigate their properties. The investigated ribbons were prepared by rapid solidification of molten metal on a rotating copper cylinder (melt-spinning. In order to obtain the material with amorphous structure, the cooling rate of the liquid alloy should vary in a range from 104 to 106 K/s. The microstructure studies were performed using X-ray diffractometery. The mechanical properties were investigated by metallographic studies, micro-hardness and tribological resistance tests moreover the surface roughness profile were analyzed. All studies were performed for two sides of tapes, since the differences in ribbons surface, related with manufacturing process, are clearly visible. The surface from the bottom (drum side was glossy and from the top side it was shiny.

  4. Deformation and transport of micro-fibers and helices in viscous flows

    Science.gov (United States)

    Lindner, Anke

    Fluid-structure interactions between flexible objects and viscous flows are, to a large extent, governed by the shape of the flexible object. Using microfabrication methods, we obtain complex ``particles'' in fiber and helix form with perfect control not only over the material properties, but also the particle geometry. We then perform an experimental study on the deformation and transport of these particles in microfluidic flows. Fibers are shown to drift laterally in confined flows due to the transport anisotropy of the elongated object. When these fibers interact with lateral walls, complex dynamics are observed, such as fiber oscillation. Fiber flexibility modifies these dynamics. Flexible microhelices are easily stretched by a viscous flow and we characterize the overall shape as a function of the frictional properties. The deformation of these helices is well-described by non-linear finite extensibility. Due to the non-uniform distribution of the pitch of a helix subject to viscous drag, linear and nonlinear behavior is identified along the contour length of a single helix. When a polymer solution is used for the viscous flow, an interesting multiscale problem arises and the typical polymer size needs to be compared not only to the global size of the helix, but also to the dimensions of the ribbon.

  5. Magnetic helicity balance in the Sustained Spheromak Plasma Experiment

    International Nuclear Information System (INIS)

    Stallard, B.W.; Hooper, E.B.; Woodruff, S.; Bulmer, R.H.; Hill, D.N.; McLean, H.S.; Wood, R.D.

    2003-01-01

    The magnetic helicity balance between the helicity input injected by a magnetized coaxial gun, the rate-of-change in plasma helicity content, and helicity dissipation in electrode sheaths and Ohmic losses have been examined in the Sustained Spheromak Plasma Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)]. Helicity is treated as a flux function in the mean-field approximation, allowing separation of helicity drive and losses between closed and open field volumes. For nearly sustained spheromak plasmas with low fluctuations, helicity balance analysis implies a decreasing transport of helicity from the gun input into the spheromak core at higher spheromak electron temperature. Long pulse discharges with continuously increasing helicity and larger fluctuations show higher helicity coupling from the edge to the spheromak core. The magnitude of the sheath voltage drop, inferred from cathode heating and a current threshold dependence of the gun voltage, shows that sheath losses are important and reduce the helicity injection efficiency in SSPX

  6. Cholesterol metabolism and serum non-cholesterol sterols: summary of 13 plant stanol ester interventions.

    Science.gov (United States)

    Hallikainen, Maarit; Simonen, Piia; Gylling, Helena

    2014-04-27

    The efficacy and safety of plant stanols added to food products as serum cholesterol lowering agents have been demonstrated convincingly, but their effects on cholesterol metabolism and on serum non-cholesterol sterols is less evaluated. The aim of this study was to assess the validity of serum non-cholesterol sterols and squalene as bioindices of cholesterol synthesis and absorption, and to examine how the individual serum non-cholesterol sterols respond to consumption of plant stanols. We collected all randomized, controlled plant stanol ester (STAEST) interventions in which serum cholestanol, plant sterols campesterol and sitosterol, and at least two serum cholesterol precursors had been analysed. According to these criteria, there was a total of 13 studies (total 868 subjects without lipid-lowering medication; plant stanol doses varied from 0.8 to 8.8 g/d added in esterified form; the duration of the studies varied from 4 to 52 weeks). Serum non-cholesterol sterols were assayed with gas-liquid chromatography, cholesterol synthesis with the sterol balance technique, and fractional cholesterol absorption with the dual continuous isotope feeding method. The results demonstrated that during the control and the STAEST periods, the serum plant sterol/cholesterol- and the cholestanol/cholesterol-ratios reflected fractional cholesterol absorption, and the precursor sterol/cholesterol-ratios reflected cholesterol synthesis. Plant sterol levels were dose-dependently reduced by STAEST so that 2 g of plant stanols reduced serum campesterol/cholesterol-ratio on average by 32%. Serum cholestanol/cholesterol-ratio was reduced less frequently than those of the plant sterols by STAEST, and the cholesterol precursor sterol ratios did not change consistently in the individual studies emphasizing the importance of monitoring more than one surrogate serum marker. Serum non-cholesterol sterols are valid markers of cholesterol absorption and synthesis even during cholesterol

  7. A new dental powder from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons

    International Nuclear Information System (INIS)

    Do-Minh, N.; Le-Thi, C.; Nguyen-Anh, S.

    2003-01-01

    A new non-gamma-two dental powder has been developed from nanocrystalline melt-spun Ag-Sn-Cu alloy ribbons. The amalgam made from this powder exhibits excellent properties for dental filling. The nanocrystalline microstructure was found for the first time in as-spun and heat treated Ag(27-28)Sn(9-32) Cu alloy ribbons, using X-ray diffraction, scanning electron microscopy and energy-dispersive spectroscopy. As-spun ribbons exhibited a multi-phase microstructure with preferred existence of β (Ag 4 Sn) phase formed during rapid solidification (RS) due to supersaturating of copper (Cu) atoms and homogenous nanostructure with subgrain size of about (40-50) nm, which seems to be developed during RS process and can be caused by eutectic reaction of the Ag 3 Sn/Ag 4 Sn-Cu 3 Sn system. In heat treated ribbons the clustering of Cu atoms was always favored and stable in an ageing temperature and time interval determined by Cu content. The heat treatment led to essential changes of subgrain morphology, resulted in the appearance of large-angle boundaries with fine Cu 3 Sn precipitates and forming typical recrystallization twins. Such a microstructure variation in melt-spun ribbons could eventually yield enhanced technological, clinical and physical properties of the dental products, controlled by the ADA Specification N deg 1 and reported before. Thus, using the rapid solidification technique a new non-gamma-two dental material of high quality, nanocrystalline ribbon powder, can be produced. Copyright (2003) AD-TECH - International Foundation for the Advancement of Technology Ltd

  8. OBSERVATIONS OF AN X-SHAPED RIBBON FLARE IN THE SUN AND ITS THREE-DIMENSIONAL MAGNETIC RECONNECTION

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.; Ding, M. D.; Yang, K. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Qiu, J.; Longcope, D. W., E-mail: yingli@nju.edu.cn [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2016-05-20

    We report evolution of an atypical X-shaped flare ribbon that provides novel observational evidence of three-dimensional (3D) magnetic reconnection at a separator. The flare occurred on 2014 November 9. High-resolution slit-jaw 1330 Å images from the Interface Region Imaging Spectrograph reveal four chromospheric flare ribbons that converge and form an X-shape. Flare brightening in the upper chromosphere spreads along the ribbons toward the center of the “X” (the X-point), and then spreads outward in a direction more perpendicular to the ribbons. These four ribbons are located in a quadrupolar magnetic field. Reconstruction of magnetic topology in the active region suggests the presence of a separator connecting to the X-point outlined by the ribbons. The inward motion of flare ribbons in the early stage therefore indicates 3D magnetic reconnection between two sets of non-coplanar loops that approach laterally, and reconnection proceeds downward along a section of vertical current sheet. Coronal loops are also observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory confirming the reconnection morphology illustrated by ribbon evolution.

  9. Cholesterol oxidation products and their biological importance

    DEFF Research Database (Denmark)

    Kulig, Waldemar; Cwiklik, Lukasz; Jurkiewicz, Piotr

    2016-01-01

    The main biological cause of oxysterols is the oxidation of cholesterol. They differ from cholesterol by the presence of additional polar groups that are typically hydroxyl, keto, hydroperoxy, epoxy, or carboxyl moieties. Under typical conditions, oxysterol concentration is maintained at a very low...... and precisely regulated level, with an excess of cholesterol. Like cholesterol, many oxysterols are hydrophobic and hence confined to cell membranes. However, small chemical differences between the sterols can significantly affect how they interact with other membrane components, and this in turn can have...

  10. FLARE RIBBON ENERGETICS IN THE EARLY PHASE OF AN SDO FLARE

    Energy Technology Data Exchange (ETDEWEB)

    Fletcher, L.; Hannah, I. G.; Hudson, H. S. [School of Physics and Astronomy, SUPA, University of Glasgow, Glasgow, G12 8QQ (United Kingdom); Innes, D. E. [Max Planck Institute for Solar System Research, Max-Planck-Strasse 2, D-37191 Katlenburg-Lindau (Germany)

    2013-07-10

    The sites of chromospheric excitation during solar flares are marked by extended extreme ultraviolet ribbons and hard X-ray (HXR) footpoints. The standard interpretation is that these are the result of heating and bremsstrahlung emission from non-thermal electrons precipitating from the corona. We examine this picture using multi-wavelength observations of the early phase of an M-class flare SOL2010-08-07T18:24. We aim to determine the properties of the heated plasma in the flare ribbons, and to understand the partition of the power input into radiative and conductive losses. Using GOES, SDO/EVE, SDO/AIA, and RHESSI, we measure the temperature, emission measure (EM), and differential emission measure of the flare ribbons, and deduce approximate density values. The non-thermal EM, and the collisional thick target energy input to the ribbons are obtained from RHESSI using standard methods. We deduce the existence of a substantial amount of plasma at 10 MK in the flare ribbons, during the pre-impulsive and early-impulsive phase of the flare. The average column EM of this hot component is a few times 10{sup 28} cm{sup -5}, and we can calculate that its predicted conductive losses dominate its measured radiative losses. If the power input to the hot ribbon plasma is due to collisional energy deposition by an electron beam from the corona then a low-energy cutoff of {approx}5 keV is necessary to balance the conductive losses, implying a very large electron energy content. Independent of the standard collisional thick-target electron beam interpretation, the observed non-thermal X-rays can be provided if one electron in 10{sup 3}-10{sup 4} in the 10 MK (1 keV) ribbon plasma has an energy above 10 keV. We speculate that this could arise if a non-thermal tail is generated in the ribbon plasma which is being heated by other means, for example, by waves or turbulence.

  11. Numerical Study of the influence of a ribbon geometry of experiment on measuring particle angular distributions

    International Nuclear Information System (INIS)

    Artemov, A.S.

    1996-01-01

    The values and nature of systematic errors in small-angle particle scattering experiments using ribbon-like beams are investigated by numerical simulation. As shown, the extent of the influence of a ribbon geometry of experiment on the result of measurement is significantly dependent on the shape of the measured angular distribution in an elementary act of interaction. The algorithm of experimental material treatment, obtained in measuring the widths at half maximum of the angular differential cross sections of secondary particles, is presented using an example of specific distributions and certain experimental setup. (author). 12 refs., 7 figs

  12. SPECTROSCOPIC OBSERVATIONS OF AN EVOLVING FLARE RIBBON SUBSTRUCTURE SUGGESTING ORIGIN IN CURRENT SHEET WAVES

    Energy Technology Data Exchange (ETDEWEB)

    Brannon, S. R.; Longcope, D. W.; Qiu, J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2015-09-01

    We present imaging and spectroscopic observations from the Interface Region Imaging Spectrograph of the evolution of the flare ribbon in the SOL2014-04-18T13:03 M-class flare event, at high spatial resolution and time cadence. These observations reveal small-scale substructure within the ribbon, which manifests as coherent quasi-periodic oscillations in both position and Doppler velocities. We consider various alternative explanations for these oscillations, including modulation of chromospheric evaporation flows. Among these, we find the best support for some form of wave localized to the coronal current sheet, such as a tearing mode or Kelvin–Helmholtz instability.

  13. Gettering effects in RAD polysilicon ribbons: An XPS/AES study

    Energy Technology Data Exchange (ETDEWEB)

    Amarray, E.; Deville, J.P.; Quesada, J.

    1987-03-01

    Evidence for gettering effects during the various heat treatments applied to RAD ribbons were investigated with surface analysis methods. These heat treatments occur either during the burning-off process of the carbon support or during the POCl/sub 3/ diffusion, and transport metallic impurities near the surface of the sample. Oxidation of clean silicon surfaces, cleaved either in air or ultra-high vacuum, has shown that the same metallic impurities are brought near the surface by this treatment alone. It is thus suggested that controlled oxidations and heat treatments can be used to improve the electrical properties of polysilicon, and especially of ribbons.

  14. The Blue Ribbon Commission and siting radioactive waste disposal facilities

    International Nuclear Information System (INIS)

    Pescatore, C.

    2010-01-01

    On 21 September 2010, the NEA Secretariat was invited to address the Blue Ribbon Commission on America's Nuclear Future. This paper is a summary of the remarks made. The successful siting of radioactive waste disposal facilities implies creating the conditions for continued ownership of the facility over time. Acceptance of the facility at a single point in time is not good enough. Continued ownership implies the creation of conscious, constructive and durable relationships between the (most affected) communities and the waste management facility. Being comfortable about the technical safety of the facility requires a degree of familiarity and control . Having peace of mind about the safety of the facility requires trust in the waste management system and its actors as well as some control over the decision making. Regulators are especially important players who need to be visible in the community. The ideal site selection process should be step- wise, combining procedures for excluding sites that do not meet pre-identified criteria with those for identifying sites where nearby and more distant residents are willing to discuss acceptance of the facility. The regional authorities are just as important as the local authorities. Before approaching a potential siting region or community, there should be clear results of national (and state) debates establishing the role of nuclear power in the energy mix, as well as information on the magnitude of the ensuing waste commitment and its management end-points, and the allocation of the financial and legal responsibilities until the closure of the project. Once the waste inventories and type of facilities have been decided upon, there should be agreement that all significant changes will require a new decision-making process. Any proposed project has a much better chance to move forward positively if the affected populations can participate in its definition, including, at the appropriate time, its technical details. A

  15. Large Area Silicon Sheet by EFG. [quality control and productivity of edge-defined film-fed growth of ribbons

    Science.gov (United States)

    1979-01-01

    Influences on ribbon quality which might be caused by various materials of construction which are used in the growth furnace were assessed. At the present level of ribbon quality, which has produced 8.5% to 9.5% efficient solar cells, no particular influence of any furnace part was detected. The experiments led to the suspicion that the general environment and the somewhat unoptimized materials handling procedures might be responsible for the current variations in ribbon quality and that, therefore, continuous work with this furnace under rather more stringent environmental conditions and operating procedures could perhaps improve materials quality to some extent. The work on the multiple furnace was continued with two multiple growth runs being performed. In these runs, the melt replenishment system performed poorly and extensive modifications to it were designed to make reliable melt feeding for five ribbon growth possible. Additional characterization techniques for wide ribbons, stress measurements, and growth dynamics experiments are reported.

  16. Helical CT of congenital ossicular anomalies

    International Nuclear Information System (INIS)

    Osada, Hisato; Machida, Kikuo; Honda, Norinari

    2001-01-01

    Since January 1996 to December 2000, 26 cases of congenital ossicular anomaly could be diagnosed with helical CT. All cases were unilateral. In 8 patients with malformation of the external ear, CT showed malleoincudal fixation (n=5), malleoincudal fixation and deformed incuts long process (n=1), deformed incus long process (n=1), and partial fusion of malleus neck and incus long process (n=1). In 18 patients with normal external ear, CT showed defect of the incus long process (n=5), defect of both the incus long process and stapes superstructure (n=8, 2 patients with congenital cholesteatoma, 1 with hypoplastic oval window), defect of the stapes superstructure (n=2, 1 patient with oval window absence), defect of the malleus manubrium (n=1), ossification of the stampede's tendon (n=1), and monopod stapes (n=1). Helical CT can evaluate the auditory ossicular chain in detail and is useful for diagnosing congenital ossicular anomaly. (author)

  17. Weaving Knotted Vector Fields with Tunable Helicity.

    Science.gov (United States)

    Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M

    2016-12-30

    We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

  18. Vacuum systems for the ILC helical undulator

    CERN Document Server

    Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A

    2007-01-01

    The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

  19. SUPERCONDUCTING HELICAL SNAKE MAGNETS: CONSTRUCTION AND MEASUREMENTS

    International Nuclear Information System (INIS)

    Mackay, W.W.; Anerella, M.; Courant, E.

    1999-01-01

    In order to collide polarized protons, the RHIC project will have two snakes in each ring and four rotators around each of two interaction regions. Two snakes on opposite sides of each ring can minimize depolarization during acceleration by keeping the spin tune at a half. Since the spin direction is normally along the vertical direction in a flat ring, spin rotators must be used around an interaction point to have longitudinal polarization in a collider experiment. Each snake or rotator will be composed of four helical dipoles to provide the required rotation of spin with minimal transverse orbit excursions in a compact length of 10m. The basic helical dipole is a superconducting magnet producing a transverse dipole field which is twisted about the magnet axis through 360 o in a length of 2.4 m. The design and construction of the magnets is described in this paper

  20. Buoyant Helical Twin-Axial Wire Antenna

    Science.gov (United States)

    2016-11-15

    February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300169 1 of 9 BUOYANT HELICAL TWIN-AXIAL WIRE ANTENNA CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0001] This application is a divisional...application and claims the benefit of the filing date of United States Patent Application No. 14/280,889; filed on May 19, 2014; and entitled “Twin-Axial

  1. Molecular Dynamics with Helical Periodic Boundary Conditions

    Czech Academy of Sciences Publication Activity Database

    Kessler, Jiří; Bouř, Petr

    2014-01-01

    Roč. 35, č. 21 (2014), s. 1552-1559 ISSN 0192-8651 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA AV ČR(CZ) M200551205; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : periodic boundary conditions * helical symmetry * molecular dynamics * protein structure * amyloid fibrils Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.589, year: 2014

  2. Simplification of the helical TEN2 laser

    Science.gov (United States)

    Krahn, K.-H.

    1980-04-01

    The observation that the helical TEN2 laser can effectively be simplified by giving up the use of decoupling elements as well as by abolishing the segmentation of the electrode structure is examined. Although, as a consequence of this simplification, the operating pressure range was slightly decreased, the output power could be improved by roughly 30%, a result which is attributed to the new electrode geometry exhibiting lower inductance and lower damping losses.

  3. Field of a helical Siberian Snake

    Energy Technology Data Exchange (ETDEWEB)

    Luccio, A. [Brookhaven National Lab., Upton, NY (United States)

    1995-02-01

    To preserve the spin polarization of a beam of high energy protons in a circular accelerator, magnets with periodic magnetic field, called Siberian Snakes are being used. Recently, it was proposed to build Siberian Snakes with superconducting helical dipoles. In a helical, or twisted dipole, the magnetic field is perpendicular to the axis of the helix and rotates around it as one proceeds along the magnet. In an engineering study of a 4 Tesla helical snake, the coil geometry is derived, by twisting, from the geometry of a cosine superconducting dipole. While waiting for magnetic measurement data on such a prototype, an analytical expression for the field of the helice is important, to calculate the particle trajectories and the spin precession in the helix. This model will also allow to determine the optical characteristics of the snake, as an insertion in the lattice of the accelerator. In particular, one can calculate the integrated multipoles through the magnet and the equivalent transfer matrix. An expression for the field in the helix body, i.e., excluding the fringe field was given in a classical paper. An alternate expression can be found by elaborating on the treatment of the field of a transverse wiggler obtained under the rather general conditions that the variables are separable. This expression exactly satisfies Maxwell`s div and curl equations for a stationary field, {del} {center_dot} B = 0, {del} x B = 0. This approach is useful in that it will allow one to use much of the work already done on the problem of inserting wigglers and undulators in the lattice of a circular accelerator.

  4. Overexpression of guanylate cyclase activating protein 2 in rod photoreceptors in vivo leads to morphological changes at the synaptic ribbon.

    Directory of Open Access Journals (Sweden)

    Natalia López-del Hoyo

    Full Text Available Guanylate cyclase activating proteins are EF-hand containing proteins that confer calcium sensitivity to retinal guanylate cyclase at the outer segment discs of photoreceptor cells. By making the rate of cGMP synthesis dependent on the free intracellular calcium levels set by illumination, GCAPs play a fundamental role in the recovery of the light response and light adaptation. The main isoforms GCAP1 and GCAP2 also localize to the synaptic terminal, where their function is not known. Based on the reported interaction of GCAP2 with Ribeye, the major component of synaptic ribbons, it was proposed that GCAP2 could mediate the synaptic ribbon dynamic changes that happen in response to light. We here present a thorough ultrastructural analysis of rod synaptic terminals in loss-of-function (GCAP1/GCAP2 double knockout and gain-of-function (transgenic overexpression mouse models of GCAP2. Rod synaptic ribbons in GCAPs-/- mice did not differ from wildtype ribbons when mice were raised in constant darkness, indicating that GCAPs are not required for ribbon early assembly or maturation. Transgenic overexpression of GCAP2 in rods led to a shortening of synaptic ribbons, and to a higher than normal percentage of club-shaped and spherical ribbon morphologies. Restoration of GCAP2 expression in the GCAPs-/- background (GCAP2 expression in the absence of endogenous GCAP1 had the striking result of shortening ribbon length to a much higher degree than overexpression of GCAP2 in the wildtype background, as well as reducing the thickness of the outer plexiform layer without affecting the number of rod photoreceptor cells. These results indicate that preservation of the GCAP1 to GCAP2 relative levels is relevant for maintaining the integrity of the synaptic terminal. Our demonstration of GCAP2 immunolocalization at synaptic ribbons at the ultrastructural level would support a role of GCAPs at mediating the effect of light on morphological remodeling changes of

  5. Helical waves in easy-plane antiferromagnets

    Science.gov (United States)

    Semenov, Yuriy G.; Li, Xi-Lai; Xu, Xinyi; Kim, Ki Wook

    2017-12-01

    Effective spin torques can generate the Néel vector oscillations in antiferromagnets (AFMs). Here, it is theoretically shown that these torques applied at one end of a normal AFM strip can excite a helical type of spin wave in the strip whose properties are drastically different from characteristic spin waves. An analysis based on both a Néel vector dynamical equation and the micromagnetic simulation identifies the direction of magnetic anisotropy and the damping factor as the two key parameters determining the dynamics. Helical wave propagation requires the hard axis of the easy-plane AFM to be aligned with the traveling direction, while the damping limits its spatial extent. If the damping is neglected, the calculation leads to a uniform periodic domain wall structure. On the other hand, finite damping decelerates the helical wave rotation around the hard axis, ultimately causing stoppage of its propagation along the strip. With the group velocity staying close to spin-wave velocity at the wave front, the wavelength becomes correspondingly longer away from the excitation point. In a sufficiently short strip, a steady-state oscillation can be established whose frequency is controlled by the waveguide length as well as the excitation energy or torque.

  6. Helical CT in acute lower gastrointestinal bleeding

    International Nuclear Information System (INIS)

    Ernst, Olivier; Leroy, Christophe; Sergent, Geraldine; Bulois, Philippe; Saint-Drenant, Sophie; Paris, Jean-Claude

    2003-01-01

    The purpose of this study was to assess the usefulness of helical CT in depicting the location of acute lower gastrointestinal bleeding. A three-phase helical CT of the abdomen was performed in 24 patients referred for acute lower gastrointestinal bleeding. The diagnosis of the bleeding site was established by CT when there was at least one of the following criteria: spontaneous hyperdensity of the peribowel fat; contrast enhancement of the bowel wall; vascular extravasation of the contrast medium; thickening of the bowel wall; polyp or tumor; or vascular dilation. Diverticula alone were not enough to locate the bleeding site. The results of CT were compared with the diagnosis obtained by colonoscopy, enteroscopy, or surgery. A definite diagnosis was made in 19 patients. The bleeding site was located in the small bowel in 5 patients and the colon in 14 patients. The CT correctly located 4 small bowel hemorrhages and 11 colonic hemorrhages. Diagnosis of the primary lesion responsible for the bleeding was made in 10 patients. Our results suggest that helical CT could be a good diagnostic tool in acute lower gastrointestinal bleeding to help the physician to diagnose the bleeding site. (orig.)

  7. Superconducting Helical Snake Magnet for the AGS

    CERN Document Server

    Willen, Erich; Escallier, John; Ganetis, George; Ghosh, Arup; Gupta, Ramesh C; Harrison, Michael; Jain, Animesh K; Luccio, Alfredo U; MacKay, William W; Marone, Andrew; Muratore, Joseph F; Okamura, Masahiro; Plate, Stephen R; Roser, Thomas; Tsoupas, Nicholaos; Wanderer, Peter

    2005-01-01

    A superconducting helical magnet has been built for polarized proton acceleration in the Brookhaven AGS. This "partial Snake" magnet will help to reduce the loss of polarization of the beam due to machine resonances. It is a 3 T magnet some 1940 mm in magnetic length in which the dipole field rotates with a pitch of 0.2053 degrees/mm for 1154 mm in the center and a pitch of 0.3920 degrees/mm for 393 mm in each end. The coil cross-section is made of two slotted cylinders containing superconductor. In order to minimize residual offsets and deflections of the beam on its orbit through the Snake, a careful balancing of the coil parameters was necessary. In addition to the main helical coils, a solenoid winding was built on the cold bore tube inside the main coils to compensate for the axial component of the field that is experienced by the beam when it is off-axis in this helical magnet. Also, two dipole corrector magnets were placed on the same tube with the solenoid. A low heat leak cryostat was built so that t...

  8. Total scalp irradiation using helical tomotherapy

    International Nuclear Information System (INIS)

    Orton, Nigel; Jaradat, Hazim; Welsh, James; Tome, Wolfgang

    2005-01-01

    Homogeneous irradiation of the scalp poses technical and dosimetric challenges due to the extensive, superficial, curved treatment volume. Conventional treatments on a linear accelerator use multiple matched electron fields or a combination of electron and photon fields. Problems with these techniques include dose heterogeneity in the target due to varying source-to-skin distance (SSD) and angle of beam incidence, significant dose to the brain, and the potential for overdose or underdose at match lines between the fields. Linac-based intensity-modulated radiation therapy (IMRT) plans have similar problems. This work presents treatment plans for total scalp irradiation on a helical tomotherapy machine. Helical tomotherapy is well-suited for scalp irradiation because it has the ability to deliver beamlets that are tangential to the scalp at all points. Helical tomotherapy also avoids problems associated with field matching and use of more than one modality. Tomotherapy treatment plans were generated and are compared to plans for treatment of the same patient on a linac. The resulting tomotherapy plans show more homogeneous target dose and improved critical structure dose when compared to state-of-the-art linac techniques. Target equivalent uniform dose (EUD) for the best tomotherapy plan was slightly higher than for the linac plan, while the volume of brain tissue receiving over 30 Gy was reduced by two thirds. Furthermore, the tomotherapy plan can be more reliably delivered than linac treatments, because the patient is aligned prior to each treatment based on megavoltage computed tomography (MVCT)

  9. THE EFFECTS OF SPATIAL SMOOTHING ON SOLAR MAGNETIC HELICITY PARAMETERS AND THE HEMISPHERIC HELICITY SIGN RULE

    Energy Technology Data Exchange (ETDEWEB)

    Ocker, Stella Koch [Department of Physics, Oberlin College, Oberlin, OH 44074 (United States); Petrie, Gordon, E-mail: socker@oberlin.edu, E-mail: gpetrie@nso.edu [National Solar Observatory, Boulder, CO 80303 (United States)

    2016-12-01

    The hemispheric preference for negative/positive helicity to occur in the northern/southern solar hemisphere provides clues to the causes of twisted, flaring magnetic fields. Previous studies on the hemisphere rule may have been affected by seeing from atmospheric turbulence. Using Hinode /SOT-SP data spanning 2006–2013, we studied the effects of two spatial smoothing tests that imitate atmospheric seeing: noise reduction by ignoring pixel values weaker than the estimated noise threshold, and Gaussian spatial smoothing. We studied in detail the effects of atmospheric seeing on the helicity distributions across various field strengths for active regions (ARs) NOAA 11158 and NOAA 11243, in addition to studying the average helicities of 179 ARs with and without smoothing. We found that, rather than changing trends in the helicity distributions, spatial smoothing modified existing trends by reducing random noise and by regressing outliers toward the mean, or removing them altogether. Furthermore, the average helicity parameter values of the 179 ARs did not conform to the hemisphere rule: independent of smoothing, the weak-vertical-field values tended to be negative in both hemispheres, and the strong-vertical-field values tended to be positive, especially in the south. We conclude that spatial smoothing does not significantly affect the overall statistics for space-based data, and thus seeing from atmospheric turbulence seems not to have significantly affected previous studies’ ground-based results on the hemisphere rule.

  10. Statins increase hepatic cholesterol synthesis and stimulate fecal cholesterol elimination in mice

    NARCIS (Netherlands)

    Schonewille, Marleen; de Boer, Jan Freark; Mele, Laura; Wolters, Henk; Bloks, Vincent W.; Wolters, Justina C.; Kuivenhoven, Jan A.; Tietge, Uwe J. F.; Brufau, Gemma; Groen, Albert K.

    Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Statins reduce plasma cholesterol levels, but whether this is actually caused by inhibition of de novo cholesterol synthesis has not been clearly established. Using three different statins, we

  11. Statins increase hepatic cholesterol synthesis and stimulate fecal cholesterol elimination in mice

    NARCIS (Netherlands)

    Schonewille, Marleen; de Boer, Jan Freark; Mele, Laura; Wolters, Henk; Bloks, Vincent W.; Wolters, Justina C.; Kuivenhoven, Jan A.; Tietge, Uwe J. F.; Brufau, Gemma; Groen, Albert K.

    2016-01-01

    Statins are competitive inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol synthesis. Statins reduce plasma cholesterol levels, but whether this is actually caused by inhibition of de novo cholesterol synthesis has not been clearly established. Using three different statins, we

  12. Dietary cholesterol and fats at a young age : do they influence cholesterol metabolism in adult life?

    NARCIS (Netherlands)

    Temmerman, A.M.; Vonk, R.J.; Niezen-Koning, K.; Berger, R.; Fernandes, J.

    1989-01-01

    The effects of dietary cholesterol and fats on cholesterol metabolism later in life were studied in Mongolian gerbils. Three groups were given a basic diet with soybean oil, palm kernel oil amounting to 8.75% (w/w), or the basic diet only. In three other groups, cholesterol (0.05%) was added to the

  13. From blood to gut: Direct secretion of cholesterol via transintestinal cholesterol efflux

    NARCIS (Netherlands)

    Vrins, Carlos L. J.

    2010-01-01

    The reverse cholesterol transport pathway (RCT) is the focus of many cholesterol lowering therapies By way of this pathway, excess cholesterol is collected from peripheral tissues and delivered back to the liver and gastrointestinal tract for excretion from the body For a long time this removal via

  14. Cholesterol Transport Revisited : A New Turbo Mechanism to Drive Cholesterol Excretion

    NARCIS (Netherlands)

    de Boer, Jan Freark; Kuipers, Folkert; Groen, Albert K.

    A fine-tuned balance between cholesterol uptake and excretion by the body is pivotal to maintain health and to remain free from the deleterious consequences of cholesterol accumulation such as cardiovascular disease. The pathways involved in intracellular and extracellular cholesterol transport are

  15. The cholesterol space of the rat; L'espace cholesterol du rat

    Energy Technology Data Exchange (ETDEWEB)

    Chevallier, F [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    The experiments consisted in feeding daily to rats the same mass of radioactive cholesterol, over variable time intervals. From the evolution of the specific radioactivity of cholesterol carbon-14 in the organs as a function of time, information relative to the transport of cholesterol in the organism may be obtained. 1) The cholesterol space, defined as the group of molecules capable of being transferred from the organs into the serum and vice versa, represents at the most 50 per cent of the total cholesterol of the adult rat. 2) The incessant interchange between the tissual and the serum cholesterol renews entirely or for the most part the cholesterol molecules contained in the following organs: spleen, heart, adipose tissue, suprarenal glands, lungs, bone marrow, liver, erythrocytes. For a second group of organs: skin, testicles, kidneys, colon, bones, muscles, only a fraction of their cholesterol is renewable by this process. No transfer can be detected at the level of the brain. 3) The relative speeds of the various means of appearance (absorption, synthesis) and disappearance (excretion, transformation) of the cholesterol from its space are such that a stationary isotopic state is established around the eighth day, when the animal absorbs 5 milligrams of radioactive cholesterol daily. (author) [French] Les experiences ont consiste a faire ingerer quotidiennement une meme masse de cholesterol radioactif a des rats, durant des laps de temps variables. L'evolution de la radioactivite specifique du carbone-14 du cholesterol des organes en fonction du temps permet d'obtenir des renseignements relatifs au transport du cholesterol dans l'organisme. 1) L'espace cholesterol defini comme l'ensemble des molecules susceptibles d'etre transferees des organes dans le serum, et vice-versa, represente au plus 50 pour cent du cholesterol total du rat adulte. 2) Le va et vient incessant entre le cholesterol tissulaire et le cholesterol serique renouvelle en totalite ou en

  16. Cryo-EM Structure Determination Using Segmented Helical Image Reconstruction.

    Science.gov (United States)

    Fromm, S A; Sachse, C

    2016-01-01

    Treating helices as single-particle-like segments followed by helical image reconstruction has become the method of choice for high-resolution structure determination of well-ordered helical viruses as well as flexible filaments. In this review, we will illustrate how the combination of latest hardware developments with optimized image processing routines have led to a series of near-atomic resolution structures of helical assemblies. Originally, the treatment of helices as a sequence of segments followed by Fourier-Bessel reconstruction revealed the potential to determine near-atomic resolution structures from helical specimens. In the meantime, real-space image processing of helices in a stack of single particles was developed and enabled the structure determination of specimens that resisted classical Fourier helical reconstruction and also facilitated high-resolution structure determination. Despite the progress in real-space analysis, the combination of Fourier and real-space processing is still commonly used to better estimate the symmetry parameters as the imposition of the correct helical symmetry is essential for high-resolution structure determination. Recent hardware advancement by the introduction of direct electron detectors has significantly enhanced the image quality and together with improved image processing procedures has made segmented helical reconstruction a very productive cryo-EM structure determination method. © 2016 Elsevier Inc. All rights reserved.

  17. Hydrodynamic studies of CNT nanofluids in helical coil heat exchanger

    Science.gov (United States)

    Babita; Sharma, S. K.; Mital Gupta, Shipra; Kumar, Arinjay

    2017-12-01

    Helical coils are extensively used in several industrial processes such as refrigeration systems, chemical reactors, recovery processes etc to accommodate a large heat transfer area within a smaller space. Nanofluids are getting great attention due to their enhanced heat transfer capability. In heat transfer equipments, pressure drop is one of the major factors of consideration for pumping power calculations. So, the present work is aimed to study hydrodynamics of CNT nanofluids in helical coils. In this study, pressure drop characteristics of CNT nanofluid flowing inside horizontal helical coils are investigated experimentally. The helical coil to tube diameter was varied from 11.71 to 27.34 keeping pitch of the helical coil constant. Double distilled water was used as basefluid. SDBS and GA surfactants were added to stablilize CNT nanofluids. The volumetric fraction of CNT nanofluid was varied from 0.003 vol% to 0.051 vol%. From the experimental data, it was analyzed that the friction factor in helical coils is greater than that of straight tubes. Concentration of CNT in nanofluids also has a significant influence on the pressure drop/friction factor of helical coils. At a constant concentration of CNT, decreasing helical coil to tube diameter from 27.24 to 11.71, fanning friction factor of helical coil; f c increases for a constant value of p/d t. This increase in the value of fanning friction factor can be attributed to the secondary flow of CNT nanofluid in helical coils.

  18. Phytosterol glycosides reduce cholesterol absorption in humans

    Science.gov (United States)

    Lin, Xiaobo; Ma, Lina; Racette, Susan B.; Anderson Spearie, Catherine L.; Ostlund, Richard E.

    2009-01-01

    Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received ∼300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4–5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6 ± 4.8% (P lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content. PMID:19246636

  19. Phytosterol glycosides reduce cholesterol absorption in humans.

    Science.gov (United States)

    Lin, Xiaobo; Ma, Lina; Racette, Susan B; Anderson Spearie, Catherine L; Ostlund, Richard E

    2009-04-01

    Dietary phytosterols inhibit intestinal cholesterol absorption and regulate whole body cholesterol excretion and balance. However, they are biochemically heterogeneous and a portion is glycosylated in some foods with unknown effects on biological activity. We tested the hypothesis that phytosterol glycosides reduce cholesterol absorption in humans. Phytosterol glycosides were extracted and purified from soy lecithin in a novel two-step process. Cholesterol absorption was measured in a series of three single-meal tests given at intervals of 2 wk to each of 11 healthy subjects. In a randomized crossover design, participants received approximately 300 mg of added phytosterols in the form of phytosterol glycosides or phytosterol esters, or placebo in a test breakfast also containing 30 mg cholesterol-d7. Cholesterol absorption was estimated by mass spectrometry of plasma cholesterol-d7 enrichment 4-5 days after each test. Compared with the placebo test, phytosterol glycosides reduced cholesterol absorption by 37.6+/-4.8% (Pphytosterol esters 30.6+/-3.9% (P=0.0001). These results suggest that natural phytosterol glycosides purified from lecithin are bioactive in humans and should be included in methods of phytosterol analysis and tables of food phytosterol content.

  20. Nuclear receptors in control of cholesterol transport

    NARCIS (Netherlands)

    van der Veen, Jelske Nynke

    2007-01-01

    Cholesterol is een structurele component van celmembranen en een grondstof voor de aanmaak van steroïde hormonen en galzouten en vervult dus een aantal essentiële fysiologische functies. Een goede balans van cholesterol opname, synthese, afbraak en uitscheiding is noodzakelijk, omdat verhoogde

  1. Cholesterol efflux is differentially regulated in neurons and astrocytes: implications for brain cholesterol homeostasis

    Science.gov (United States)

    Chen, Jing; Zhang, Xiaolu; Kusumo, Handojo; Costa, Lucio G.; Guizzetti, Marina

    2012-01-01

    Disruption of cholesterol homeostasis in the central nervous system (CNS) has been associated with neurological, neurodegenerative, and neurodevelopmental disorders. The CNS is a closed system with regard to cholesterol homeostasis, as cholesterol-delivering lipoproteins from the periphery cannot pass the blood-brain-barrier and enter the brain. Different cell types in the brain have different functions in the regulation of cholesterol homeostasis, with astrocytes producing and releasing apolipoprotein E and lipoproteins, and neurons metabolizing cholesterol to 24(S)-hydroxycholesterol. We present evidence that astrocytes and neurons adopt different mechanisms also in regulating cholesterol efflux. We found that in astrocytes cholesterol efflux is induced by both lipid-free apolipoproteins and lipoproteins, while cholesterol removal from neurons is triggered only by lipoproteins. The main pathway by which apolipoproteins induce cholesterol efflux is through ABCA1. By upregulating ABCA1 levels and by inhibiting its activity and silencing its expression, we show that ABCA1 is involved in cholesterol efflux from astrocytes but not from neurons. Furthermore, our results suggest that ABCG1 is involved in cholesterol efflux to apolipoproteins and lipoproteins from astrocytes but not from neurons, while ABCG4, whose expression is much higher in neurons than astrocytes, is involved in cholesterol efflux from neurons but not astrocytes. These results indicate that different mechanisms regulate cholesterol efflux from neurons and astrocytes, reflecting the different roles that these cell types play in brain cholesterol homeostasis. These results are important in understanding cellular targets of therapeutic drugs under development for the treatments of conditions associated with altered cholesterol homeostasis in the CNS. PMID:23010475

  2. Cholesterol Absorption and Synthesis in Vegetarians and Omnivores.

    Science.gov (United States)

    Lütjohann, Dieter; Meyer, Sven; von Bergmann, Klaus; Stellaard, Frans

    2018-03-01

    Vegetarian diets are considered health-promoting; however, a plasma cholesterol lowering effect is not always observed. We investigate the link between vegetarian-diet-induced alterations in cholesterol metabolism. We study male and female omnivores, lacto-ovo vegetarians, lacto vegetarians, and vegans. Cholesterol intake, absorption, and fecal sterol excretion are measured as well as plasma concentrations of cholesterol and noncholesterol sterols. These serve as markers for cholesterol absorption, synthesis, and catabolism. The biliary cholesterol secretion rate is estimated. Flux data are related to body weight. Individual vegetarian diet groups are statistically compared to the omnivore group. Lacto vegetarians absorb 44% less dietary cholesterol, synthesized 22% more cholesterol, and show no differences in plasma total and LDL cholesterol. Vegan subjects absorb 90% less dietary cholesterol, synthesized 35% more cholesterol, and have a similar plasma total cholesterol, but a 13% lower plasma LDL cholesterol. No diet-related differences in biliary cholesterol secretion and absorption are observed. Total cholesterol absorption is lower only in vegans. Total cholesterol input is similar under all vegetarian diets. Unaltered biliary cholesterol secretion and higher cholesterol synthesis blunt the lowered dietary cholesterol intake in vegetarians. LDL cholesterol is significantly lower only in vegans. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Helical muon beam cooling channel engineering design

    International Nuclear Information System (INIS)

    Johnson, Rolland

    2015-01-01

    The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet. The first phase of this project saw the development of a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb 3 Sn-based HS test section. Two very novel ideas are required to realize the design. The first idea is the use of dielectric inserts in the RF cavities to make them smaller for a given frequency so that the cavities and associated plumbing easily fit inside the magnet cryostat. Calculations indicate that heat loads will be tolerable, while RF breakdown of the dielectric inserts will be suppressed by the pressurized hydrogen gas. The second new idea is the use of a multi-layer Nb 3 Sn helical solenoid. The technology demonstrations for the two aforementioned key components of a 10T, 805 MHz HCC were begun in this project. The work load in the Fermilab Technical Division made it difficult to test a multi-layer Nb 3 Sn solenoid as originally planned. Instead, a complementary project was approved by the

  4. Helical muon beam cooling channel engineering design

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland [Muons, Inc., Batavia, IL (United States)

    2015-08-07

    The Helical Cooling Channel (HCC) achieves effective ionization cooling of the six-dimensional (6d) phase space of a muon beam by means of a series of 21st century inventions. In the HCC, hydrogen-pressurized RF cavities enable high RF gradients in strong external magnetic fields. The theory of the HCC, which requires a magnetic field with solenoid, helical dipole, and helical quadrupole components, demonstrates that dispersion in the gaseous hydrogen energy absorber provides effective emittance exchange to enable longitudinal ionization cooling. The 10-year development of a practical implementation of a muon-beam cooling device has involved a series of technical innovations and experiments that imply that an HCC of less than 300 m length can cool the 6d emittance of a muon beam by six orders of magnitude. We describe the design and construction plans for a prototype HCC module based on oxygen-doped hydrogen-pressurized RF cavities that are loaded with dielectric, fed by magnetrons, and operate in a superconducting helical solenoid magnet. The first phase of this project saw the development of a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn-based HS test section. Two very novel ideas are required to realize the design. The first idea is the use of dielectric inserts in the RF cavities to make them smaller for a given frequency so that the cavities and associated plumbing easily fit inside the magnet cryostat. Calculations indicate that heat loads will be tolerable, while RF breakdown of the dielectric inserts will be suppressed by the pressurized hydrogen gas. The second new idea is the use of a multi-layer Nb3Sn helical solenoid. The technology demonstrations for the two aforementioned key components of a 10T, 805 MHz HCC were begun in this project. The work load in the Fermilab Technical Division made it difficult to test a multi-layer Nb3Sn solenoid as originally planned. Instead, a complementary

  5. Cholesterol in myelin biogenesis and hypomyelinating disorders.

    Science.gov (United States)

    Saher, Gesine; Stumpf, Sina Kristin

    2015-08-01

    The largest pool of free cholesterol in mammals resides in myelin membranes. Myelin facilitates rapid saltatory impulse propagation by electrical insulation of axons. This function is achieved by ensheathing axons with a tightly compacted stack of membranes. Cholesterol influences myelination at many steps, from the differentiation of myelinating glial cells, over the process of myelin membrane biogenesis, to the functionality of mature myelin. Cholesterol emerged as the only integral myelin component that is essential and rate-limiting for the development of myelin in the central and peripheral nervous system. Moreover, disorders that interfere with sterol synthesis or intracellular trafficking of cholesterol and other lipids cause hypomyelination and neurodegeneration. This review summarizes recent results on the roles of cholesterol in CNS myelin biogenesis in normal development and under different pathological conditions. This article is part of a Special Issue entitled Brain Lipids. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. 78 FR 29703 - Narrow Woven Ribbons With Woven Selvedge From Taiwan: Preliminary Results of Antidumping Duty...

    Science.gov (United States)

    2013-05-21

    ... DEPARTMENT OF COMMERCE International Trade Administration [A-583-844] Narrow Woven Ribbons With... AGENCY: Import Administration, International Trade Administration, Department of Commerce. SUMMARY: The..., International Trade Administration, U.S. Department of Commerce, 14th Street and Constitution Avenue NW...

  7. ATRF Ribbon-Cutting Ceremony Coincides with Chamber of Commerce Centennial Gala | Poster

    Science.gov (United States)

    By Frank Blanchard, Staff Writer U.S. Rep. Roscoe Bartlett, NCI Deputy Director for Management John Czajkowski, and SAIC Corporate Chief Executive Officer (CEO) John Jumper were joined by representatives of the Frederick County Chamber of Commerce in cutting the ribbon for the National Cancer Institute’s Advanced Technology Research Facility (ATRF).

  8. Nanocrystallization in Co67Cr7Fe4Si8B14 Amorphous Alloy Ribbons

    Directory of Open Access Journals (Sweden)

    Zahra Jamili-Shirvan

    2013-12-01

    Full Text Available The nanocrystallization of Co67Fe4Cr7Si8B14 amorphous ribbons which prepared by planar flow melt spinning process (PFMS was investigated. Crystallization of the ribbons was studied by differential thermal analysis (DTA, X-ray diffraction (XRD and transmission electron microscopy (TEM. The DTA result of amorphous ribbon at heating rate of 10˚C/min showedoccurrence of phase transitions in two stages. The ribbons were isothermally annealed for 30 minutes in argon atmosphere at different temperatures between 300 and 650ºC with 25ºC steps. The magnetic properties of annealed samples were measured using a vibrating sample magnetometer (VSM. The VSM results revealed that optimum soft magnetic properties occurred at 400ºC. XRD patterns showed that the samples isothermally annealed up to 450ºC were amorphous, while TEM results at 400ºC indicated 7-8 nm mean size nanocrytallites in amorphous matrix and size of the nanocrystallites increased by increasing temperature. Also by X-ray diffraction pattern, precipitation of different phases at higher temperatures confirmed.

  9. Temperature dependent evolution of wrinkled single-crystal silicon ribbons on shape memory polymers.

    Science.gov (United States)

    Wang, Yu; Yu, Kai; Qi, H Jerry; Xiao, Jianliang

    2017-10-25

    Shape memory polymers (SMPs) can remember two or more distinct shapes, and thus can have a lot of potential applications. This paper presents combined experimental and theoretical studies on the wrinkling of single-crystal Si ribbons on SMPs and the temperature dependent evolution. Using the shape memory effect of heat responsive SMPs, this study provides a method to build wavy forms of single-crystal silicon thin films on top of SMP substrates. Silicon ribbons obtained from a Si-on-insulator (SOI) wafer are released and transferred onto the surface of programmed SMPs. Then such bilayer systems are recovered at different temperatures, yielding well-defined, wavy profiles of Si ribbons. The wavy profiles are shown to evolve with time, and the evolution behavior strongly depends on the recovery temperature. At relatively low recovery temperatures, both wrinkle wavelength and amplitude increase with time as evolution progresses. Finite element analysis (FEA) accounting for the thermomechanical behavior of SMPs is conducted to study the wrinkling of Si ribbons on SMPs, which shows good agreement with experiment. Merging of wrinkles is observed in FEA, which could explain the increase of wrinkle wavelength observed in the experiment. This study can have important implications for smart stretchable electronics, wrinkling mechanics, stimuli-responsive surface engineering, and advanced manufacturing.

  10. Fish Marketing of Ribbon Fish (Trichiurus sp. in Nusantara Fishing Port (NFPat Palabuhanratu, West Java

    Directory of Open Access Journals (Sweden)

    Nur Bambang Azis

    2018-01-01

    Full Text Available The objective of this research is to study the marketing process of ribbon fish (Trichiurus sp., including the marketing margin, marketing agencies, traders and marketing channels The research was carried out for 3 mo in Nusantara Fishing Port (NFP, Palabuhanratu, Sukabumi, West Java. A case study was used in this research. A purposive sampling method was used to collect data from 55 respondents of fish marketing, consisting of fishermen, agents, traders, and retailers, who were involved in the marketing of ribbon fish in NFP Palabuhanratu. The result of the research showed that ribbon fish production in Palabuhanratu fluctuated from year to year. There are two types of ribbon fish marketing, i.e. type one is from fishermen to retailers, and type two is indirect marketing from fisherman to consumers through intermediate traders (exporters. The greatest marketing margin was obtained from the first type, while the smallest marketing margin was obtained from type two. The form of the market was considered to be oligopsony market. Fisherman’s share is greatest in the collectors and the smallest share is on retailers. Marketing process in traders is efficient due to its lowest margin and highest fisherman’s share.

  11. GMI effect in CuO coated Co-based amorphous ribbons

    International Nuclear Information System (INIS)

    Taysioglu, Asli Ayten; Peksoz, Ahmet; Kaya, Yunus; Derebasi, Naim; Irez, Gazi; Kaynak, Gokay

    2009-01-01

    A Copper oxide (CuO) film has been grown on a surface of Co-based amorphous ribbon using chemical successive ionic layer adsorption and reaction technique, at room temperature and atmosphere pressure. The influence of coating and width of ribbon on giant magneto impedance have been investigated over a frequency range from 0.1 to 3 MHz and under a static magnetic field between -8 and +8 kA/m. The results showed that Co-based amorphous ribbons, which are coated CuO film, have a significant effect on the magnitude and operation frequency for the giant magneto impedance effect as compared to the samples without coating. The highest giant magneto impedance effect was found to be 14.90 on 5 mm width coated ribbon, which is 60% higher than the sample without coating. A surface observation of these samples has been carried out by an atomic force microscope. The AFM images reveal the difference between surfaces of coated and as-cast sample.

  12. Growth behaviour of twisted ribbons of barium carbonate/silica self-assembled ceramics

    International Nuclear Information System (INIS)

    Garcia-Ruiz, J.M.; Moreno, A.

    1997-01-01

    Twisted ribbons of self-assembled crystal aggregates of barium carbonate, in the presence of silicate ions at pH 9.5 grow at constant rate between 20 and 50 mu m/min. The morphological behaviour depends on temperature, while it was demonstrated to be independent of the viscosity of the growth environment. (Author) 7 refs

  13. The identification of a sensitizing component used in the manufacturing of an ink ribbon

    Science.gov (United States)

    Anderson, Stacey E.; Tapp, Loren; Durgam, Srinivas; Meade, B. Jean; Jackson, Laurel G.; Cohen, David E.

    2015-01-01

    Skin diseases including dermatitis constitute ≈ 30% of all occupational illnesses, with a high incidence in the printing industry. An outbreak of contact dermatitis among employees at an ink ribbon manufacturing plant was investigated by scientists from the National Institute for Occupational Safety and Health (NIOSH). Employees in the process areas of the plant were exposed to numerous chemicals and many had experienced skin rashes, especially after the introduction of a new ink ribbon product. To identify the causative agent(s) of the occupational dermatitis, the murine local lymph node assay (LLNA) was used to identify the potential of the chemicals used in the manufacture of the ink ribbon to induce allergic contact dermatitis. Follow-up patch testing with the suspected allergens was conducted on exposed employees. Polyvinyl butyral, a chemical component used in the manufacture of the ink ribbon in question and other products, tested positive in the LLNA, with an EC3 of 3.6%, which identifies it as a potential sensitizer; however, no employees tested positive to this chemical during skin patch testing. This finding has implications beyond those described in this report because of occupational exposure to polyvinyl butyral outside of the printing industry. PMID:22375946

  14. Magnetic properties of nanocrystallized Fe-Pt-B melt-spun ribbons

    International Nuclear Information System (INIS)

    Yamamoto, Tokujiro; Omori, Akihiro; Kimura, Hisamichi; Inoue, Akihisa

    2007-01-01

    L1 0 FePt nanoparticles have been prepared by etching grain boundaries of heat-treated melt-spun Fe-19Pt-25B (at.%) alloy ribbons. It is revealed that an L1 0 FePt nanocrystalline phase is directly formed from the Fe-Pt-B amorphous ribbons by long-time heat treatment at low temperatures in the vicinity of 723 K. With increasing heat treatment time, dimensions of the nanocrystallized FePt grains increase, accompanied by a change from soft ferromagnetic to hard ferromagnetic. The ribbon crystallized at 723 K for 1.8 ks consists of only an FePt L1 0 phase and its coercivity is as low as 0.381 kA/m. However, it increases to 372 kA/m with increasing grain size of precipitated L1 0 phase to about 30 nm by heat treatment for 86.4 ks, while the saturation magnetic flux density remains constant at about 0.4 T. Etching boundaries in heat-treated ribbons has been performed to obtain ferromagnetic L1 0 FePt nanoparticles and several particles were observed by means of transmission electron microscopy

  15. GMI effect in CuO coated Co-based amorphous ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Taysioglu, Asli Ayten [Department of Physics, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey); Peksoz, Ahmet, E-mail: peksoz@uludag.edu.t [Department of Physics, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey); Kaya, Yunus [Department of Chemistry, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey); Derebasi, Naim [Department of Physics, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey); Irez, Gazi [Department of Chemistry, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey); Kaynak, Gokay [Department of Physics, Sciences and Arts Faculty, Uludag University, 16059 Gorukle, Bursa (Turkey)

    2009-11-13

    A Copper oxide (CuO) film has been grown on a surface of Co-based amorphous ribbon using chemical successive ionic layer adsorption and reaction technique, at room temperature and atmosphere pressure. The influence of coating and width of ribbon on giant magneto impedance have been investigated over a frequency range from 0.1 to 3 MHz and under a static magnetic field between -8 and +8 kA/m. The results showed that Co-based amorphous ribbons, which are coated CuO film, have a significant effect on the magnitude and operation frequency for the giant magneto impedance effect as compared to the samples without coating. The highest giant magneto impedance effect was found to be 14.90 on 5 mm width coated ribbon, which is 60% higher than the sample without coating. A surface observation of these samples has been carried out by an atomic force microscope. The AFM images reveal the difference between surfaces of coated and as-cast sample.

  16. 75 FR 11908 - Narrow Woven Ribbons With Woven Selvedge From China and Taiwan

    Science.gov (United States)

    2010-03-12

    ...)] Narrow Woven Ribbons With Woven Selvedge From China and Taiwan AGENCY: United States International Trade...(b) of the Act (19 U.S.C. 1673d(b)) to determine whether an industry in the United States is materially injured or threatened with material injury, or the establishment of an industry in the United...

  17. 75 FR 53711 - Narrow Woven Ribbons With Woven Selvedge From China and Taiwan

    Science.gov (United States)

    2010-09-01

    ... Woven Ribbons With Woven Selvedge From China and Taiwan Determinations On the basis of the record \\1... U.S.C. 1673d(b)) (the Act), that an industry in the United States is threatened with material injury... (19 U.S.C. 1673d(b)), that an industry in the United States is threatened with material injury by...

  18. Magnetic and surface properties of Fe-Nb (Mo, V)-Cu-B-Si ribbons

    International Nuclear Information System (INIS)

    Butvinova, B.; Butvin, P.; Svec, P. Sr.; Matko, I.; Svec, P.; Janickovic, D.; Kadlecikova, M.

    2014-01-01

    The rapidly quenched Finemet (FeNbCuBSi) ribbons prepared by planar flow casting of the melt are very variable to obtain very good soft-magnetic properties. An appropriate thermal treatment leading to ultra-fine grain structure enables to attain such properties as desired for practical use. Increasing Fe percentage to the detriment of non-magnetic components lifts saturation induction above 1.3 T, preserves low coercivity and makes the alloy even cheaper to suit its mass production for use in power electronics. Apart from the plenty of benefits the ribbons show some risks. One of them is macroscopic heterogeneity, which often manifests via differences between surfaces and interior of a ribbon [3]. The surfaces squeeze (by in-plane force) the interior of many such ribbons and if engaged in magnetoelastic interaction, the force affects the resulting magnetic anisotropy [4]. Current research shows that changes of hysteresis loop shape come rather from surface crystallization and not from oxides namely in positively magnetostrictive alloys FeNbCuBSi known as low- Si Finemets. The object of this work is to verify whether the substitution of another element instead of Nb (usually incorporated as the grain-growth blocker) can change surface properties and affects the resulting magnetic properties. We chose V and Mo instead of Nb. Oxides, oxyhydroxides and a possible squeezing layer was looked for after higher temperature annealing which ensures partially nanocrystalline structure. (authors)

  19. 75 FR 66766 - NIAID Blue Ribbon Panel Meeting on Adjuvant Discovery and Development

    Science.gov (United States)

    2010-10-29

    ..., identifies gaps in knowledge and capabilities, and defines NIAID's goals for the continued discovery...), will convene a Blue Ribbon Panel to provide expertise in developing a strategic plan and research... vaccines. NIAID has developed a draft Strategic Plan and Research Agenda for Adjuvant Discovery and...

  20. A Quantitative Examination of the Educational Technology Characteristics of Ohio Schools and Their Blue Ribbon Status

    Science.gov (United States)

    Goon, Dean A.

    2012-01-01

    The purpose of this study was to analyze data from Ohio schools and the frequency of use of educational technology, a teacher's comfort level using technology, and a teacher's beliefs about the effect of educational technology on teaching and learning based upon the school's Blue Ribbon award status. The study used an ex-post facto, quantitative…

  1. Magnetic properties, phase evolution, and microstructure of the Co–Zr–V ribbons

    International Nuclear Information System (INIS)

    Hou, Zhipeng; Su, Feng; Xu, Shifeng; Zhang, Jinbao; Wu, Chunji; Liu, Dan; Wei, Beipei; Wang, Wenquan

    2013-01-01

    The substitution of V for Zr significantly impeded the growth of grain in the Co 82 Zr 18 ribbons during melt spinning and the amorphous Co 82 Zr 13 V 5 melt-spun ribbons were successfully produced at a wheel speed of 40 m/s. The values of coercivity H c and maximum energy product (BH) max first increased, reaching maximum at 560 °C and then they decreased sharply with increasing the annealing temperature. The optimal magnetic properties of H c =4.0 kOe and (BH) max =5.0 MGOe were obtained in the amorphous ribbons annealed at 560 °C. A suitable grain size of Co 11 Zr 2 phase was considered to be the main reason for the increase in coercivity. - Highlights: • High performance was obtained in Co 82 Zr 13 V 5 amorphous ribbons annealed. • We proved the hard magnetic phase was Co 11 Zr 2 phase. • Suitable grain size of Co 11 Zr 2 phase was the main reason for increase in coercivity

  2. System assessment of helical reactors in comparison with tokamaks

    International Nuclear Information System (INIS)

    Yamazaki, K.; Imagawa, S.; Muroga, T.; Sagara, A.; Okamura, S.

    2002-10-01

    A comparative assessment of tokamak and helical reactors has been performed using equivalent physics/engineering model and common costing model. Higher-temperature plasma operation is required in tokamak reactors to increase bootstrap current fraction and to reduce current-drive (CD) power. In helical systems, lower-temperature operation is feasible and desirable to reduce helical ripple transport. The capital cost of helical reactor is rather high, however, the cost of electricity (COE) is almost same as that of tokamak reactor because of smaller re-circulation power (no CD power) and less-frequent blanket replacement (lower neutron wall loading). The standard LHD-type helical reactor with 5% beta value is economically equivalent to the standard tokamak with 3% beta. The COE of lower-aspect ratio helical reactor is on the same level of high-β N tokamak reactors. (author)

  3. Use of intraventricular ribbon gauze to reduce particulate emboli during aortic valve replacement

    Directory of Open Access Journals (Sweden)

    Loubani Mahmoud

    2006-11-01

    Full Text Available Abstract Background The incidence of cerebrovascular accidents following aortic valve surgery remains a devastating complication. The aim of this study was to determine the number of potential embolic material arising during aortic valve replacement and to examine the efficacy of using ribbon gauze in the left ventricle during removal of the native valve and decalcification of the aortic annulus. Methods Ribbon gauze was inserted into the left ventricular cavity prior to aortic valve excision in an unselected, prospectively studied series of 30 patients undergoing aortic valve replacement. A further 30 lengths of ribbon gauze were soaked in the pericardiotomy blood of the same patients and all were subjected to histological analysis. Results The median number of tissue fragments from the aortic valve replacement group was significantly higher than in the control group 5 (0–18 versus 0 (0–1 (p = 3.6 × 10-5. The size of tissue fragments varied between 0.1 and 9.0 mm with a mean of 0.61 ± 1.12 mm and a median of 0.2 mm. There was a significantly higher number of tissue fragments associated with patients having surgery for aortic stenosis when compared with patients who had aortic regurgitation with median of 5 (0–18 versus 0 (0–3 (p = 0.8 × 10-3. Conclusion Significant capture of particulate debris by the intraventricular ribbon gauze suggests that the technique of left ventricular ribbon gauze insertion during aortic valve excision has merit.

  4. A CIRCULAR-RIBBON SOLAR FLARE FOLLOWING AN ASYMMETRIC FILAMENT ERUPTION

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chang; Deng, Na; Lee, Jeongwoo; Wang, Haimin [Space Weather Research Laboratory, New Jersey Institute of Technology, University Heights, Newark, NJ 07102-1982 (United States); Liu, Rui [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei 230026 (China); Pariat, Étienne [LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universits, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, F-92190 Meudon (France); Wiegelmann, Thomas [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig Weg 3, D-37077 Göttingen (Germany); Liu, Yang [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States); Kleint, Lucia, E-mail: chang.liu@njit.edu [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland)

    2015-10-20

    The dynamic properties of flare ribbons and the often associated filament eruptions can provide crucial information on the flaring coronal magnetic field. This Letter analyzes the GOES-class X1.0 flare on 2014 March 29 (SOL2014-03-29T17:48), in which we found an asymmetric eruption of a sigmoidal filament and an ensuing circular flare ribbon. Initially both EUV images and a preflare nonlinear force-free field model show that the filament is embedded in magnetic fields with a fan-spine-like structure. In the first phase, which is defined by a weak but still increasing X-ray emission, the western portion of the sigmoidal filament arches upward and then remains quasi-static for about five minutes. The western fan-like and the outer spine-like fields display an ascending motion, and several associated ribbons begin to brighten. Also found is a bright EUV flow that streams down along the eastern fan-like field. In the second phase that includes the main peak of hard X-ray (HXR) emission, the filament erupts, leaving behind two major HXR sources formed around its central dip portion and a circular ribbon brightened sequentially. The expanding western fan-like field interacts intensively with the outer spine-like field, as clearly seen in running difference EUV images. We discuss these observations in favor of a scenario where the asymmetric eruption of the sigmoidal filament is initiated due to an MHD instability and further facilitated by reconnection at a quasi-null in corona; the latter is in turn enhanced by the filament eruption and subsequently produces the circular flare ribbon.

  5. Mucins and calcium phosphate precipitates additively stimulate cholesterol crystallization

    NARCIS (Netherlands)

    van den Berg, A. A.; van Buul, J. D.; Tytgat, G. N.; Groen, A. K.; Ostrow, J. D.

    1998-01-01

    Human biliary mucin and calcium binding protein (CBP) influence formation of both calcium salt precipitates and cholesterol crystals and colocalize in the center of cholesterol gallstones. We investigated how physiological concentrations of these proteins regulate cholesterol crystallization in

  6. Tuberculosis treatment raises total cholesterol level and restores ...

    African Journals Online (AJOL)

    aghomotsegin

    2013-10-09

    Oct 9, 2013 ... and restores high density lipoprotein cholesterol (HDL- ... cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG) were determined .... However, we found a strong negative correlation (r = - 0.96,.

  7. Endogenous cholesterol synthesis, fecal steroid excretion and serum lanosterol in subjects with high or low response of serum cholesterol to dietary cholesterol

    NARCIS (Netherlands)

    Beynen, A.C.; Katan, M.B.; Gent, van C.M.

    1986-01-01

    In this study we addressed the question whether hypo- and hyper-responders to dietary cholesterol differ with regard to the flexibility of endogenous cholesterol synthesis after changes in cholesterol intake. Whole-body cholesterol synthesis was measured as faecal excretion of neutral steroids and

  8. Alteration of helical vortex core without change in flow topology

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Okulov, Valery; Hansen, Martin Otto Laver

    2011-01-01

    topology. The helical symmetry as such is preserved, although the characteristic parameters of helical symmetry of the vortex core transfer from a smooth linear variation to a different trend under the influence of a non-uniform pressure gradient, causing an increase in helical pitch without changing its......The abrupt expansion of the slender vortex core with changes in flow topology is commonly known as vortex breakdown. We present new experimental observations of an alteration of the helical vortex core in wall bounded turbulent flow with abrupt growth in core size, but without change in flow...

  9. Helicity conservation under quantum reconnection of vortex rings.

    Science.gov (United States)

    Zuccher, Simone; Ricca, Renzo L

    2015-12-01

    Here we show that under quantum reconnection, simulated by using the three-dimensional Gross-Pitaevskii equation, self-helicity of a system of two interacting vortex rings remains conserved. By resolving the fine structure of the vortex cores, we demonstrate that the total length of the vortex system reaches a maximum at the reconnection time, while both writhe helicity and twist helicity remain separately unchanged throughout the process. Self-helicity is computed by two independent methods, and topological information is based on the extraction and analysis of geometric quantities such as writhe, total torsion, and intrinsic twist of the reconnecting vortex rings.

  10. Superposition of helical beams by using a Michelson interferometer.

    Science.gov (United States)

    Gao, Chunqing; Qi, Xiaoqing; Liu, Yidong; Weber, Horst

    2010-01-04

    Orbital angular momentum (OAM) of a helical beam is of great interests in the high density optical communication due to its infinite number of eigen-states. In this paper, an experimental setup is realized to the information encoding and decoding on the OAM eigen-states. A hologram designed by the iterative method is used to generate the helical beams, and a Michelson interferometer with two Porro prisms is used for the superposition of two helical beams. The experimental results of the collinear superposition of helical beams and their OAM eigen-states detection are presented.

  11. Interaction of pathogens with host cholesterol metabolism.

    Science.gov (United States)

    Sviridov, Dmitri; Bukrinsky, Michael

    2014-10-01

    Pathogens of different taxa, from prions to protozoa, target cellular cholesterol metabolism to advance their own development and to impair host immune responses, but also causing metabolic complications, for example, atherosclerosis. This review describes recent findings of how pathogens do it. A common theme in interaction between pathogens and host cholesterol metabolism is pathogens targeting lipid rafts of the host plasma membrane. Many intracellular pathogens use rafts as an entry gate, taking advantage of the endocytic machinery and high abundance of outward-looking molecules that can be used as receptors. At the same time, disruption of the rafts' functional capacity, achieved by the pathogens through a number of various means, impairs the ability of the host to generate immune response, thus helping pathogen to thrive. Pathogens cannot synthesize cholesterol, and salvaging host cholesterol helps pathogens build advanced cholesterol-containing membranes and assembly platforms. Impact on cholesterol metabolism is not limited to the infected cells; proteins and microRNAs secreted by infected cells affect lipid metabolism systemically. Given an essential role that host cholesterol metabolism plays in pathogen development, targeting this interaction may be a viable strategy to fight infections, as well as metabolic complications of the infections.

  12. Cholesterol esterase activity of human intestinal mucosa

    International Nuclear Information System (INIS)

    Ponz de Leon, M.; Carubbi, F.; Di Donato, P.; Carulli, N.

    1985-01-01

    It has been suggested that cholesterol absorption in humans is dependent on bile acid pool composition and that expansion of the cholic acid pool size is followed by an increase of the absorption values. Similar observations were reported in rats. In the present study, therefore, the authors investigated some general properties of human intestinal cholesterol esterase, with particular emphasis on the effect of bile acids on this enzymatic activity. Twenty-nine segments of small intestine were taken during operations; the enzymatic activity was studied by using mucosal homogenate as a source of enzyme and oleic acid, cholesterol, and 14 C-labeled cholesterol as substrates. The time-activity relationship was linear within the first two hours; optimal pH for esterification ranged between 5 and 6.2. There was little difference between the esterifying activity of the jejunal and ileal mucosa. Esterification of cholesterol was observed with all the investigated fatty acids but was maximal with oleic acid. Bile acids did not affect cholesterol esterase activity when present in the incubation mixture at 0.1 and 1.0 mM; the enzymatic activity, however, was significantly inhibited when bile acids were added at 20 mM. In conclusion, this study has shown that the human intestinal mucosa possesses a cholesterol esterase activity; at variance with the rat, however, the human enzyme does not seem to be stimulated by trihydroxy bile acids

  13. Cholesterol asymmetry in synaptic plasma membranes.

    Science.gov (United States)

    Wood, W Gibson; Igbavboa, Urule; Müller, Walter E; Eckert, Gunter P

    2011-03-01

    Lipids are essential for the structural and functional integrity of membranes. Membrane lipids are not randomly distributed but are localized in different domains. A common characteristic of these membrane domains is their association with cholesterol. Lipid rafts and caveolae are examples of cholesterol enriched domains, which have attracted keen interest. However, two other important cholesterol domains are the exofacial and cytofacial leaflets of the plasma membrane. The two leaflets that make up the bilayer differ in their fluidity, electrical charge, lipid distribution, and active sites of certain proteins. The synaptic plasma membrane (SPM) cytofacial leaflet contains over 85% of the total SPM cholesterol as compared with the exofacial leaflet. This asymmetric distribution of cholesterol is not fixed or immobile but can be modified by different conditions in vivo: (i) chronic ethanol consumption; (ii) statins; (iii) aging; and (iv) apoE isoform. Several potential candidates have been proposed as mechanisms involved in regulation of SPM cholesterol asymmetry: apoE, low-density lipoprotein receptor, sterol carrier protein-2, fatty acid binding proteins, polyunsaturated fatty acids, P-glycoprotein and caveolin-1. This review examines cholesterol asymmetry in SPM, potential mechanisms of regulation and impact on membrane structure and function. © 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.

  14. [Cholesterol reducing food certainly is useful].

    Science.gov (United States)

    Stalenhoef, A F

    1997-12-27

    The effect of a low-cholesterol diet in open intervention studies depends in the long run on motivation, knowledge and dedication. The mean decrease of the serum cholesterol level is 10% (range: 0-20). Epidemiological and cohort studies clearly prove a connection between the intake of saturated fat, the serum cholesterol level and the risk of coronary heart disease and death. High-fat food slows down the clearance of the degradation products rich in cholesterol which appear in the blood after a meal and which are highly atherogenic (these products are not found at a fasting cholesterol assay). Cholesterol-reducing nutrition has additional useful effects, for instance on the blood pressure and the coagulation. The recommendations for healthy, low-cholesterol nutrition for the population as a whole apply particularly to patients with a high risk of coronary heart disease. Although advice given to individuals often has a disappointing effect, influencing the life pattern should be included in the strategy to reduce the risk of coronary heart disease.

  15. Progress with helicity injection current drive

    International Nuclear Information System (INIS)

    Jarboe, T.R.; Raman, R.; Nelson, B.A.

    2003-01-01

    Coaxial Helicity Injection (CHI) experiments in the NSTX and HIT-II devices are reported. NSTX has produced toroidal currents of 0.4 MA and pulse lengths of up to 0.33 s. These discharges nearly fill the NSTX main chamber, and show the n=1 rotating distortion characteristic of high-performance CHI plasmas. CHI has been used in HIT-II to provide a closed flux startup plasma for inductive drive. The CHI startup method saves transformer volt-seconds and greatly improves reproducibility and reliability of inductively driven discharges, even in the presence of diminishing wall conditions. (author)

  16. Heat loss by helicity injection in spheromaks

    International Nuclear Information System (INIS)

    Fowler, T.K.

    1994-01-01

    A model is presented for spheromak buildup and decay including thermal diffusivity associated with magnetic turbulence during helicity injection. It is shown that heat loss by magnetic turbulence scales more favorably than gyroBohm transport. Thus gyroBohm scaling for the proposed ignition experiment would be the conservative choice, though present experiments may be dominated by magnetic turbulence. Because of a change in boundary conditions when the gun is turned off, the model may account for the observed increase in electron temperature in CTX after turnoff

  17. Rotation influence on the plasma helical instability

    International Nuclear Information System (INIS)

    Gutkin, T.I.; Tsypin, V.S.; Boleslavskaya, G.I.

    1980-01-01

    The influence of the rotation on helical instability of a plasma with the fixed boundaries (HIFB) is investigated taking into account the compressibility. A case of infinitely long cylinder with distributed current is considered. Cases when a rotating plasma is confined by current magnetic field are analytically considered. It is shown that in the case of the fixed boundary taking into account the compressibility in the HIFB increment increases and the picture of the rotation influence on HIFB considerably changes. Besides, it is shown that in the case of high plasma pressures HIFB can stabilize as a result of the rotation

  18. Effects of pre-deformation on the martensitic transformation and magnetocaloric property in Ni-Mn-Co-Sn ribbons

    International Nuclear Information System (INIS)

    Ma Sheng-Can; Xuan Hai-Cheng; Zhang Cheng-Liang; Wang Liao-Yu; Cao Qing-Qi; Wang Dun-Hui; Du You-Wei

    2010-01-01

    This paper investigates the martensitic transformation and magnetocaloric effect in pre-deformed Ni-Mn-Co-Sn ribbons. The experimental results show that the reverse martensitic transformation temperature T M increases with the increasing pre-pressure, suggesting that pre-deformation is another effective way to adjust T M in ferromagnetic shape memory alloys. Large magnetic entropy changes and refrigerant capacities are obtained in these ribbons as well. It also discusses the origin of the enhanced martensitic transformation temperature and magnetocaloric property in pre-deformed Ni-Mn-Co-Sn ribbons

  19. HYPOLIPEMIC THERAPY AND LOW SERUM CHOLESTEROL CONCENTRATION

    Directory of Open Access Journals (Sweden)

    Vladmila Bojanic

    2004-01-01

    Full Text Available Low concentration of plasma lipoproteins (hypolipoproteinemia presents decreasing concentrations of all or particular lipids components. Classification of hypolipoproteinemia (hypoLP divides them into: primary (hereditary and secondary. Primary hipoLP are rare diseases and their main characteristic is disorder of apolipoproteins synthesis, which leads to low serum cholesterol concentration. Secondary hipoLP are presented in many diseases. They have diagnostic, prognostic significance and present good therapeutic marker. However, modern therapeutic approaches for aggressive lipid lowering pointed out many questions about physiological limits for cholesterol lowering. These approaches, also, open many questions about consequences of low serum concentration of total cholesterol and triglicerides.

  20. Electronic transport in single-helical protein molecules: Effects of multiple charge conduction pathways and helical symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Sourav, E-mail: sourav.kunduphy@gmail.com; Karmakar, S.N.

    2016-07-15

    We propose a tight-binding model to investigate electronic transport properties of single helical protein molecules incorporating both the helical symmetry and the possibility of multiple charge transfer pathways. Our study reveals that due to existence of both the multiple charge transfer pathways and helical symmetry, the transport properties are quite rigid under influence of environmental fluctuations which indicates that these biomolecules can serve as better alternatives in nanoelectronic devices than its other biological counterparts e.g., single-stranded DNA.

  1. Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1*

    Science.gov (United States)

    Hsieh, Victar; Kim, Mi-Jurng; Gelissen, Ingrid C.; Brown, Andrew J.; Sandoval, Cecilia; Hallab, Jeannette C.; Kockx, Maaike; Traini, Mathew; Jessup, Wendy; Kritharides, Leonard

    2014-01-01

    The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes. PMID:24500716

  2. Triglycerides, total cholesterol, high density lipoprotein cholesterol and low density lipoprotein cholesterol in rats exposed to premium motor spirit fumes.

    Science.gov (United States)

    Aberare, Ogbevire L; Okuonghae, Patrick; Mukoro, Nathaniel; Dirisu, John O; Osazuwa, Favour; Odigie, Elvis; Omoregie, Richard

    2011-06-01

    Deliberate and regular exposure to premium motor spirit fumes is common and could be a risk factor for liver disease in those who are occupationally exposed. A possible association between premium motor spirit fumes and plasma levels of triglyceride, total cholesterol, high density lipoprotein cholesterol and low density lipoprotein cholesterol using a rodent model could provide new insights in the pathology of diseases where cellular dysfunction is an established risk factor. The aim of this study was to evaluate the possible effect of premium motor spirit fumes on lipids and lipoproteins in workers occupationally exposed to premium motor spirit fumes using rodent model. Twenty-five Wister albino rats (of both sexes) were used for this study between the 4(th) of August and 7(th) of September, 2010. The rats were divided into five groups of five rats each. Group 1 rats were not exposed to premium motor spirit fumes (control group), group 2 rats were exposed for 1 hour daily, group 3 for 3 hours daily, group 4 for 5 hours daily and group 5 for 7 hours daily. The experiment lasted for a period of 4 weeks. Blood samples obtained from all the groups after 4 weeks of exposure were used for the estimation of plasma levels of triglyceride, total cholesterol, high density lipoprotein- cholesterol and low density lipoprotein- cholesterol. Results showed significant increase in means of plasma total cholesterol and low density lipoprotein levels (P<0.05). The mean triglyceride and total body weight were significantly lower (P<0.05) in the exposed group when compared with the unexposed. The plasma level of high density lipoprotein, the ratio of low density lipoprotein to high density lipoprotein and the ratio of total cholesterol to high density lipoprotein did not differ significantly in exposed subjects when compared with the control group. These results showed that frequent exposure to petrol fumes may be highly deleterious to the liver cells.

  3. CURRENT AND KINETIC HELICITY OF LONG-LIVED ACTIVITY COMPLEXES

    International Nuclear Information System (INIS)

    Komm, Rudolf; Gosain, Sanjay

    2015-01-01

    We study long-lived activity complexes and their current helicity at the solar surface and their kinetic helicity below the surface. The current helicity has been determined from synoptic vector magnetograms from the NSO/SOLIS facility, and the kinetic helicity of subsurface flows has been determined with ring-diagram analysis applied to full-disk Dopplergrams from NSO/GONG and SDO/HMI. Current and kinetic helicity of activity complexes follow the hemispheric helicity rule with mainly positive values (78%; 78%, respectively, with a 95% confidence level of 31%) in the southern hemisphere and negative ones (80%; 93%, respectively, with a 95% confidence level of 22% and 14%, respectively) in the northern hemisphere. The locations with the dominant sign of kinetic helicity derived from Global Oscillation Network Group (GONG) and SDO/HMI data are more organized than those of the secondary sign even if they are not part of an activity complex, while locations with the secondary sign are more fragmented. This is the case for both hemispheres even for the northern one where it is not as obvious visually due to the large amount of magnetic activity present as compared to the southern hemisphere. The current helicity shows a similar behavior. The dominant sign of current helicity is the same as that of kinetic helicity for the majority of the activity complexes (83% with a 95% confidence level of 15%). During the 24 Carrington rotations analyzed here, there is at least one longitude in each hemisphere where activity complexes occur repeatedly throughout the epoch. These ''active'' longitudes are identifiable as locations of strong current and kinetic helicity of the same sign

  4. Neutrino helicity flips via electroweak interactions

    International Nuclear Information System (INIS)

    Gaemers, K.J.F.; Gandhi, R.; Lattimer, J.M.; Department of Earth and Space Sciences, State University of New York, Stony Brook, New York 11794)

    1989-01-01

    Electroweak mechanisms via which neutrinos may flip helicity are examined in detail. Exact and approximate expressions for a variety of flip processes relevant in astrophysics and cosmology, mediated by W, Z, and γ exchange, including their interference, are derived for both Dirac and Majorana neutrinos (with emphasis on the former). It is shown that in general flip and nonflip cross sections differ by more than just a multiplicative factor of m/sub ν/ 2 /4E/sub ν/ 2 contrary to what might be expected and that this additional dependence on helicities can be significant. It is also shown that within the context of the standard model with massive neutrinos, for νe yields νe scattering, σ/sub Z//sup flip//σ/sub γ//sup flip/ ∼ 10 4 , independent of particle masses and energies to a good approximation. As an application, using some general considerations and the fact that the observed bar nu/sub e/ burst from SN 1987A lasted several seconds, these weak-interaction flip cross sections are used to rule out μ and tau neutrino masses above 30 keV. Finally, some other consequences for astrophysics in general and supernovae in particular are briefly discussed

  5. Helical type thermonuclear device and control method

    International Nuclear Information System (INIS)

    Ishigaki, Yukio.

    1990-01-01

    In a conventional helical type thermonuclear device, electric current flows in the toroidal direction under magnetic fields of helical coils and vertical magnetic coils, by which a circulating electric field is caused. Therefore, there is a problem that electrons as a seed are generated by cosmic rays, etc., the electrons are confined in a magnetic field boundary, are accelerated by the circulating electric field, to reach a high energy level, collide against structures in a vacuum vessel and emit a great amount of X-rays. Then, compensation coils for offsetting the magnetic fields generated upon energization and deenergization of the vertical magnetic coils and the power source therefor are disposed at the positions opposing to each other on both sides of the vertical magnetic coils for controlling the variation coefficient rate of electric current upon energization and deenergization of the vertical magnetic coils. Since the compensation coils also offset the magnetic field generated upon energization and deenergization of the vertical magnetic field coils by this control, the circulating magnetic field is not caused in the vacuum vessel to reduce the X-ray radiation by electrons at high energy level. (N.H.)

  6. Determining How Magnetic Helicity Injection Really Works

    International Nuclear Information System (INIS)

    Paul M Bellan

    2001-01-01

    OAK-B135 The goal of the Caltech program is to determine how helicity injection works by investigating the actual dynamics and topological evolution associated with magnetic relaxation. A new coaxial helicity injection source has been constructed and brought into operation. The key feature of this source is that it has maximum geometric simplicity. Besides being important for fusion research, this work also has astrophysical implications. Photos obtained using high-speed cameras show a clear sequence of events in the formation process. In particular, they show initial merging/reconnection processes, jet-like expansion, kinking, and separation of the plasma from the source. Various diagnostics have been developed, including laser induced fluorescence and soft x-ray detection using high speed diodes. Gas valves have been improved and a patent disclosure relating to puffed gas valves has been filed. Presentations on this work have been given in the form of invited talks at several university physics departments that were previously unfamiliar with laboratory plasma experiments

  7. On the motion of multiple helical vortices

    Science.gov (United States)

    Wood, D. H.; Boersma, J.

    2001-11-01

    The analysis of the self-induced velocity of a single helical vortex (Boersma & Wood 1999) is extended to include equally spaced multiple vortices. This arrangement approximates the tip vortices in the far wake of multi-bladed wind turbines, propellers, or rotors in ascending, descending, or hovering flight. The problem is reduced to finding, from the Biot Savart law, the additional velocity of a helix due to an identical helix displaced azimuthally. The resulting Biot Savart integral is further reduced to a Mellin Barnes integral representation which allows the asymptotic expansions to be determined for small and for large pitch. The Biot Savart integral is also evaluated numerically for a total of two, three and four vortices over a range of pitch values. The previous finding that the self-induced velocity at small pitch is dominated by a term inversely proportional to the pitch carries over to multiple vortices. It is shown that a far wake dominated by helical tip vortices is consistent with the one-dimensional representation that leads to the Betz limit on the power output of wind turbines. The small-pitch approximation then allows the determination of the blade&s bound vorticity for optimum power extraction. The present analysis is shown to give reasonable estimates for the vortex circulation in experiments using a single hovering rotor and a four-bladed propeller.

  8. Perspectives on confinement in helical systems

    International Nuclear Information System (INIS)

    Itoh, Kimitaka; Itoh, Sanae

    1989-01-01

    A review on recent experimental results and theoretical models on anomalous transport and density limit in toroidal helical devices is presented. Importance of transport problems is discussed. Experiments on Heliotron-E, Wendelstein-VIIA and new devices, i.e., ATF, Wendelstein-VIIAS and CHS, are reviewed and an overview on confinement property is given. From recent experimental results one sees that there are anomalous transport, which increases with temperature, and density limit, and that they limit the energy confinement time as well as the attainable beta value. The confinement characteristics of the scrape off layer plasma and loss cone loss are discussed, and perspectives on the high temperature plasma are given. These anomalous transport and density limit will be difficult obstacles in realizing a reactor grade plasma in helical systems. It is an urgent task to draw a realistic picture of the confinement based on the present data base. The relevant knowledge now would be critically essential for the successful development of the research in 1990's. (author) 102 refs

  9. Neutrino helicity reversal and fundamental symmetries

    International Nuclear Information System (INIS)

    Jentschura, U D; Wundt, B J

    2014-01-01

    A rather elusive helicity reversal occurs in a gedanken experiment in which a massive left-handed Dirac neutrino, traveling at a velocity u < c, is overtaken on a highway by a speeding vehicle (traveling at velocity v with u < v < c). Namely, after passing the neutrino, looking back, one would see a right-handed neutrino (which has never been observed in nature). The Lorentz-invariant mass of the right-handed neutrino is still the same as before the passing. The gedanken experiment thus implies the existence of right-handed, light neutrinos, which are not completely sterile. Furthermore, overtaking a bunch of massive right-handed Dirac neutrinos leads to gradual de-sterilization. We discuss the helicity reversal and the concomitant sterilization and de-sterilization mechanisms by way of an illustrative example calculation, with a special emphasis on massive Dirac and Majorana neutrinos. We contrast the formalism with a modified Dirac neutrino described by a Dirac equation with a pseudoscalar mass term proportional to the fifth current. (paper)

  10. Quality assurance of a helical tomotherapy machine

    International Nuclear Information System (INIS)

    Fenwick, J D; Tome, W A; Jaradat, H A; Hui, S K; James, J A; Balog, J P; DeSouza, C N; Lucas, D B; Olivera, G H; Mackie, T R; Paliwal, B R

    2004-01-01

    Helical tomotherapy has been developed at the University of Wisconsin, and 'Hi-Art II' clinical machines are now commercially manufactured. At the core of each machine lies a ring-gantry-mounted short linear accelerator which generates x-rays that are collimated into a fan beam of intensity-modulated radiation by a binary multileaf, the modulation being variable with gantry angle. Patients are treated lying on a couch which is translated continuously through the bore of the machine as the gantry rotates. Highly conformal dose-distributions can be delivered using this technique, which is the therapy equivalent of spiral computed tomography. The approach requires synchrony of gantry rotation, couch translation, accelerator pulsing and the opening and closing of the leaves of the binary multileaf collimator used to modulate the radiation beam. In the course of clinically implementing helical tomotherapy, we have developed a quality assurance (QA) system for our machine. The system is analogous to that recommended for conventional clinical linear accelerator QA by AAPM Task Group 40 but contains some novel components, reflecting differences between the Hi-Art devices and conventional clinical accelerators. Here the design and dosimetric characteristics of Hi-Art machines are summarized and the QA system is set out along with experimental details of its implementation. Connections between this machine-based QA work, pre-treatment patient-specific delivery QA and fraction-by-fraction dose verification are discussed

  11. HDL (Good), LDL (Bad) Cholesterol and Triglycerides

    Science.gov (United States)

    ... Are Cholesterol-Lowering Medications? How Statins Work Medication Tracker Personal ... or Sudden Cardiac Arrest: How Are They Different? 7 Warning Signs of a Heart Attack 8 Low Blood Pressure - ...

  12. Overview of Cholesterol and Lipid Disorders

    Science.gov (United States)

    ... Professor of Medicine, Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version ... Cholesterol and triglycerides are important ...

  13. Biochemical characterization of cholesterol-reducing Eubacterium.

    OpenAIRE

    Mott, G E; Brinkley, A W; Mersinger, C L

    1980-01-01

    We characterized two isolates of cholesterol-reducing Eubacterium by conducting conventional biochemical tests and by testing various sterols and glycerolipids as potential growth factors. In media containing cholesterol and plasmenylethanolamine, the tests for nitrate reduction, indole production, and gelatin and starch hydrolyses were negative, and no acid was produced from any of 22 carbohydrates. Both isolates hydrolyzed esculin to esculetin, indicating beta-glycosidase activity. In addit...

  14. Impact of a public cholesterol screening program.

    Science.gov (United States)

    Fischer, P M; Guinan, K H; Burke, J J; Karp, W B; Richards, J W

    1990-12-01

    The National Cholesterol Education Program (NCEP) has endorsed physician case finding as the primary method to detect individuals with elevated cholesterol levels. Despite this recommendation, promotional and for-profit public screening programs have flourished. We surveyed participants of a mall-based cholesterol screening program 1 year after their screening. Sixty-four percent of those screened had not previously known their cholesterol levels. Those who were newly screened were less likely to benefit from this testing than the general public, since they were older (mean age, 55.3 years), more likely to be female (67.4%), and nonsmokers (88%). Screenees had excellent recall of their cholesterol level (mean absolute reporting error, 0.24 mmol/L [9 mg/dL]) and a good understanding of cholesterol as a coronary heart disease risk. Those with elevated cholesterol levels reported high distress from screening but no reduction in overall psychosocial well-being and an actual decrease in absenteeism. Only 53.7% of all who were advised to seek follow-up because of an elevated screening value had done so within the year following the screening program. However, of those with values greater than 6.2 mmol/L (240 mg/dL), 68% had sought follow-up. Many of those who participate in public screening programs have been previously tested, fall into low-benefit groups, or fail to comply with recommended follow-up. We therefore conclude that cholesterol screening programs of the type now commonly offered are unlikely to contribute greatly to the national efforts to further reduce coronary heart disease.

  15. Phytosterol and cholesterol precursor levels indicate increased cholesterol excretion and biosynthesis in gallstone disease.

    Science.gov (United States)

    Krawczyk, Marcin; Lütjohann, Dieter; Schirin-Sokhan, Ramin; Villarroel, Luis; Nervi, Flavio; Pimentel, Fernando; Lammert, Frank; Miquel, Juan Francisco

    2012-05-01

    In hepatocytes and enterocytes sterol uptake and secretion is mediated by Niemann-Pick C1-like 1 (NPC1L1) and ATP-binding cassette (ABC)G5/8 proteins, respectively. Whereas serum levels of phytosterols represent surrogate markers for intestinal cholesterol absorption, cholesterol precursors reflect cholesterol biosynthesis. Here we compare serum and biliary sterol levels in ethnically different populations of patients with gallstone disease (GSD) and stone-free controls to identify differences in cholesterol transport and synthesis between these groups. In this case-control study four cohorts were analyzed: 112 German patients with GSD and 152 controls; two distinct Chilean ethnic groups: Hispanics (100 GSD, 100 controls), and Amerindians (20 GSD, 20 controls); additionally an 8-year follow-up of 70 Hispanics was performed. Serum sterols were measured by gas chromatography / mass spectrometry. Gallbladder bile sterol levels were analyzed in cholesterol GSD and controls. Common ABCG5/8 variants were genotyped. Comparison of serum sterols showed lower levels of phytosterols and higher levels of cholesterol precursors in GSD patients than in controls. The ratios of phytosterols to cholesterol precursors were lower in GSD patients, whereas biliary phytosterol and cholesterol concentrations were elevated as compared with controls. In the follow-up study, serum phytosterol levels were significantly lower even before GSD was detectable by ultrasound. An ethnic gradient in the ratios of phytosterols to cholesterol precursors was apparent (Germans > Hispanics > Amerindians). ABCG5/8 variants did not fully explain the sterol metabolic trait of GSD in any of the cohorts. Individuals predisposed to GSD display increased biliary output of cholesterol in the setting of relatively low intestinal cholesterol absorption, indicating enhanced whole-body sterol clearance. This metabolic trait precedes gallstone formation and is a feature of ethnic groups at higher risk of cholesterol

  16. Properties of rapidly solidified Fe-Cr-Al ribbons for the use as automotive exhaust gas catalyst substrates

    International Nuclear Information System (INIS)

    Emmerich, K.

    1993-01-01

    Metallic honeycomb structures are used as catalyst substrates in automotive exhaust gas systems. This application requires an outstanding corrosion resistance at elevated temperatures of the substrate material. Technical improvements can be achieved by the use of rapid solidification technology for the production of the Fe-Cr-Al ribbons since the Al content can be substantially increased from about 5% Al in the conventionally rolled material to about 12% Al in the rapid solidified ribbon. As a result the lifetime of the ribbon in a higher-temperature corrosion environment is drastically increased. In addition the scale/metal adherance is improved. The impediment of recrystallization in the rapidly solidified ribbons prevents an embrittlement even in carbonizing atmospheres. (orig.)

  17. Cholesterol suppresses antimicrobial effect of statins

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Haeri

    2015-12-01

    Full Text Available Objective(s:Isoprenoid biosynthesis is a key metabolic pathway to produce a wide variety of biomolecules such as cholesterol and carotenoids, which target cell membranes. On the other hand, it has been reported that statins known as inhibitors of isoprenoid biosynthesis and cholesterol lowering agents, may have a direct antimicrobial effect on the some bacteria. The exact action of statins in microbial metabolism is not clearly understood. It is possible that statins inhibit synthesis or utilization of some sterol precursor necessary for bacterial membrane integrity. Accordingly, this study was designed in order to examine if statins inhibit the production of a compound, which can be used in the membrane, and whether cholesterol would replace it and rescue bacteria from toxic effects of statins. Materials and Methods: To examine the possibility we assessed antibacterial effect of statins with different classes; lovastatin, simvastatin, and atorvastatin, alone and in combination with cholesterol on two Gram-positive (Staphylococcus aureus and Enterococcus faecalis and two Gram-negative (Pseudomonas aeruginosa and Escherichia coli bacteria using gel diffusion assay. Results: Our results showed that all of the statins except for lovastatin had significant antibacterial property in S. aureus, E. coli, and Enter. faecalis. Surprisingly, cholesterol nullified the antimicrobial action of effective statins in statin-sensitive bacteria. Conclusion: It is concluded that statins may deprive bacteria from a metabolite responsible for membrane stability, which is effectively substituted by cholesterol.

  18. Energy fluxes in helical magnetohydrodynamics and dynamo action

    Indian Academy of Sciences (India)

    ... large-scale magnetic field arising due to non-helical interactions and (2) inverse energy flux of magnetic energy caused by helical interactions. Based on our flux results, a primitive model for galactic dynamo has been constructed. Our calculations yield dynamo time-scale for a typical galaxy to be of the order of 108 years.

  19. Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven ...

    Indian Academy of Sciences (India)

    tribpo

    Key words. Sun—dynamo, helicity, turbulent convection. Extended abstract. Recent numerical simulations lead to the result that turbulence is much more mag- netically driven than believed. ... positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicity which is negative ...

  20. Space vehicle electromechanical system and helical antenna winding fixture

    Science.gov (United States)

    Judd, Stephen; Dallmann, Nicholas; Guenther, David; Enemark, Donald; Seitz, Daniel; Martinez, John; Storms, Steven

    2017-12-26

    A space vehicle electromechanical system may employ an architecture that enables convenient and practical testing, reset, and retesting of solar panel and antenna deployment on the ground. A helical antenna winding fixture may facilitate winding and binding of the helical antenna.

  1. Low-energy properties of fractional helical Luttinger liquids

    NARCIS (Netherlands)

    Meng, T.; Fritz, L.|info:eu-repo/dai/nl/371569559; Schuricht, D.|info:eu-repo/dai/nl/369284690; Loss, D.

    2014-01-01

    We investigate the low-energy properties of (quasi) helical and fractional helical Luttinger liquids. In particular, we calculate the Drude peak of the optical conductivity, the density of states, as well as charge transport properties of the interacting system with and without attached Fermi liquid

  2. A helical naphthopyran dopant for photoresponsive cholesteric liquid crystals

    OpenAIRE

    Kim, Yuna; Frigoli, Michel; Vanthuyne, Nicolas; Tamaoki, Nobuyuki

    2017-01-01

    The first photoresponsive cholesteric liquid crystal comprising a photoisomerizable helical naphthopyran derivative dopant and a nematic liquid crystal is reported. An unprecedented helical twisting power switching ratio of over 90% allowed us to demonstrate multi-cycle rotational motion of micro-objects by UV light irradiation.

  3. Helical modes generate antimagnetic rotational spectra in nuclei

    Science.gov (United States)

    Malik, Sham S.

    2018-03-01

    A systematic analysis of the antimagnetic rotation band using r -helicity formalism is carried out for the first time. The observed octupole correlation in a nucleus is likely to play a role in establishing the antimagnetic spectrum. Such octupole correlations are explained within the helical orbits. In a rotating field, two identical fermions (generally protons) with paired spins generate these helical orbits in such a way that its positive (i.e., up) spin along the axis of quantization refers to one helicity (right-handedness) while negative (down) spin along the same quantization-axis decides another helicity (left-handedness). Since the helicity remains invariant under rotation, therefore, the quantum state of a fermion is represented by definite angular momentum and helicity. These helicity represented states support a pear-shaped structure of a rotating system having z axis as the symmetry axis. A combined operation of parity, time-reversal, and signature symmetries ensures an absence of one of the signature partner band from the observed antimagnetic spectrum. This formalism has also been tested for the recently observed negative parity Δ I =2 antimagnetic spectrum in odd-A 101Pd nucleus and explains nicely its energy spectrum as well as the B (E 2 ) values. Further, this formalism is found to be fully consistent with twin-shears mechanism popularly known for such type of rotational bands. It also provides significant clue for extending these experiments in various mass regions spread over the nuclear chart.

  4. Experimental investigation of solar powered diaphragm and helical pumps

    Science.gov (United States)

    For several years, many types of solar powered water pumping systems were evaluated, and in this paper, diaphragm and helical solar photovoltaic (PV) powered water pumping systems are discussed. Data were collected on diaphragm and helical pumps which were powered by different solar PV arrays at mul...

  5. Impaired cholesterol esterification in primary brain cultures of the lysosomal cholesterol storage disorder (LCSD) mouse mutant

    International Nuclear Information System (INIS)

    Patel, S.C.; Suresh, S.; Weintroub, H.; Brady, R.O.; Pentchev, P.G.

    1987-01-01

    Esterification of cholesterol was investigated in primary neuroglial cultures obtained from newborn lysosomal cholesterol storage disorder (LCSD) mouse mutants. An impairment in 3 H-oleic acid incorporation into cholesteryl esters was demonstrated in cultures of homozygous LCSD brain. Primary cultures derived from other phenotypically normal pups of the carrier breeders esterified cholesterol at normal levels or at levels which were intermediary between normal and deficient indicating a phenotypic expression of the LCSD heterozygote genotype. These observations on LCSD mutant brain cells indicate that the defect in cholesterol esterification is closely related to the primary genetic defect and is expressed in neuroglial cells in culture

  6. Controlling the microstructure and associated magnetic properties of Ni0.2Mn3.2Ga0.6 melt-spun ribbons by annealing

    Directory of Open Access Journals (Sweden)

    Mahmud Khan

    2017-05-01

    Full Text Available Here we report on the structural and magnetic properties of Ni0.2Mn3.2Ga0.6 melt-spun ribbons. The as-spun ribbons were found to exhibit mixed cubic phases that transform to non-cubic structure upon annealing. Additionally, an amorphous phase was found to co-exist in all ribbons. The SEM images show that minor grain formation occurs on the as-spun ribbons. However, the formation of extensive nano-grains was observed on the surfaces of the annealed ribbons. While the as-spun ribbons exhibit predominantly paramagnetic behavior, the ribbons annealed under various thermal conditions were found to be ferromagnetic with a Curie temperature of about 380 K. The ribbons annealed at 450 °C for 30 minutes exhibit a large coercive field of about 2500 Oe. The experimental results show that the microstructure and associated magnetic properties of the ribbons can be controlled by annealing techniques. The coercive fields and the shape of the magnetic hysteresis loops vary significantly with annealing conditions. Exchange bias effects have also been observed in the annealed ribbons.

  7. Study of a Large Helical Eruptive Prominence Associated with ...

    Indian Academy of Sciences (India)

    2001-04-21

    Apr 21, 2001 ... morphology of the event, energy budget of the prominence and associated. CMEs. ... magnetically driven and internally powered. Key words. ... Solar prominences are ribbons of cool (∼8000 K) dense gas (∼10. −11 gcm. −3. ) ...

  8. Variation of magnetic properties with mischmetal content in the resource saving magnets of MM-Fe-B ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhu-bai, E-mail: lzbgj@163.com [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Li-chen [Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Geng, Xiao-peng [Inner Mongolia Baotou Steel Rare Earth Magnetic Materials Co.Ltd, Baotou 014030 (China); Hu, Feng-xia; Sun, Ji-rong; Shen, Bao-gen [State Key Laboratory for Magnetism, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-03-15

    Magnetic materials of MM-Fe-B (MM=mischmetal) ribbons were prepared using melt spinning method by varying the content of MM. The ribbons contain minor phases besides the main phase of Re{sub 2}Fe{sub 14}B. X-ray techniques show that the diffraction peak intensities of the minor phase Fe{sub 3}B vary with the content of constituent elements, indicating that the amount of minor phase could be tunable. The squareness of hysteresis loop is the best in MM{sub 13}Fe{sub 80.5}B{sub 6.5} ribbons, which should mainly ascribe to the less amount of minor phase. Henkel plots verify the more uniform magnetization reversals in MM{sub 13}Fe{sub 80.5}B{sub 6.5} ribbons, and the energy product achieves to the maximum of 12.74 MGOe with the coercivity of 6.50 kOe. With the increase of MM content the coercivity increases monotonically, and reaches to 9.13 kOe in MM{sub 15}Fe{sub 77.5}B{sub 7.5} ribbons, which should be related with the nature of the defects in the main phase. These investigations show that optimizing the content of constituent elements and phase constitution could improve magnetic properties in the resource-saving magnets of MM-Fe-B ribbons. - Highlights: • MM-Fe-B (MM=mischmetal) ribbons contains the minor phases besides the main phase of Re{sub 2}Fe{sub 14}B. • The amount of minor phases varies with the content of constituent elements. • The energy product of 12.74 MGOe is obtained in MM{sub 13}Fe{sub 80.5}B{sub 6.5} ribbons by optimizing the phase constitution.

  9. Stimuli-Directed Helical Chirality Inversion and Bio-Applications

    Directory of Open Access Journals (Sweden)

    Ziyu Lv

    2016-08-01

    Full Text Available Helical structure is a sophisticated ubiquitous motif found in nature, in artificial polymers, and in supramolecular assemblies from microscopic to macroscopic points of view. Significant progress has been made in the synthesis and structural elucidation of helical polymers, nevertheless, a new direction for helical polymeric materials, is how to design smart systems with controllable helical chirality, and further use them to develop chiral functional materials and promote their applications in biology, biochemistry, medicine, and nanotechnology fields. This review summarizes the recent progress in the development of high-performance systems with tunable helical chirality on receiving external stimuli and discusses advances in their applications as drug delivery vesicles, sensors, molecular switches, and liquid crystals. Challenges and opportunities in this emerging area are also presented in the conclusion.

  10. Helicity conservation and twisted Seifert surfaces for superfluid vortices.

    Science.gov (United States)

    Salman, Hayder

    2017-04-01

    Starting from the continuum definition of helicity, we derive from first principles its different contributions for superfluid vortices. Our analysis shows that an internal twist contribution emerges naturally from the mathematical derivation. This reveals that the spanwise vector that is used to characterize the twist contribution must point in the direction of a surface of constant velocity potential. An immediate consequence of the Seifert framing is that the continuum definition of helicity for a superfluid is trivially zero at all times. It follows that the Gauss-linking number is a more appropriate definition of helicity for superfluids. Despite this, we explain how a quasi-classical limit can arise in a superfluid in which the continuum definition for helicity can be used. This provides a clear connection between a microscopic and a macroscopic description of a superfluid as provided by the Hall-Vinen-Bekarevich-Khalatnikov equations. This leads to consistency with the definition of helicity used for classical vortices.

  11. High performance operational limits of tokamak and helical systems

    International Nuclear Information System (INIS)

    Yamazaki, Kozo; Kikuchi, Mitsuru

    2003-01-01

    The plasma operational boundaries of tokamak and helical systems are surveyed and compared with each other. Global confinement scaling laws are similar and gyro-Bohm like, however, local transport process is different due to sawtooth oscillations in tokamaks and ripple transport loss in helical systems. As for stability limits, achievable tokamak beta is explained by ideal or resistive MHD theories. On the other hand, beta values obtained so far in helical system are beyond ideal Mercier mode limits. Density limits in tokamak are often related to the coupling between radiation collapse and disruptive MHD instabilities, but the slow radiation collapse is dominant in the helical system. The pulse length of both tokamak and helical systems is on the order of hours in small machines, and the longer-pulsed good-confinement plasma operations compatible with radiative divertors are anticipated in both systems in the future. (author)

  12. On Helical Projection and Its Application in Screw Modeling

    Directory of Open Access Journals (Sweden)

    Riliang Liu

    2014-04-01

    Full Text Available As helical surfaces, in their many and varied forms, are finding more and more applications in engineering, new approaches to their efficient design and manufacture are desired. To that end, the helical projection method that uses curvilinear projection lines to map a space object to a plane is examined in this paper, focusing on its mathematical model and characteristics in terms of graphical representation of helical objects. A number of interesting projective properties are identified in regard to straight lines, curves, and planes, and then the method is further investigated with respect to screws. The result shows that the helical projection of a cylindrical screw turns out to be a Jordan curve, which is determined by the screw's axial profile and number of flights. Based on the projection theory, a practical approach to the modeling of screws and helical surfaces is proposed and illustrated with examples, and its possible application in screw manufacturing is discussed.

  13. Internal transport barrier physics in helical systems

    International Nuclear Information System (INIS)

    Yokoyama, M.; Minami, T.; Fujisawa, A.; Herranz, J.; Ida, K.; Yamagishi, O.; Yamada, H.; Maaberg, H.; Beidler, C.D.; Dinklage, A.; Estrada, T.; Castejon, F.; Murakami, S.

    2005-01-01

    The electron internal transport barrier (eITB) has been observed in wide range of helical systems, such as CHS [eg.,1], LHD [eg., 2], TJ-II [eg., 3] and W7-AS [eg., 4]. The eITB isA defined as highly peaked electron temperature (Te) profile with strongly positive radial electric field (Er) in the central region. These observations are reviewed in this paper to understand the device-independent common findings and also to draw the main differences. This is the first report from the International Stellarator Profile Database Activity. The formation of the strong central positive Er has been understood mainly as a result of the ambipolarity of neoclassical electron and ion fluxes, although some additional convective electron flux such as driven by ECRH is required in some situations. This 'neoclassical' physics peculiar to low collisional regime of helical plasmas provides the commonly observed existence of the ECRH power threshold (which is also depending on the density). This is contrastive characteristics to the ITB observed in tokamaks. The dependence of the ECRH power threshold on the magnetic configuration and on the heating scenario among these devices are currently being examined by taking the effective ripple and the trapped particle fraction as parameters to achieve the comprehensive understanding. The roles of low order rational surfaces on the onset of eITB formation and also on its radial size (location of the footpoint of the eITB) have been indicated in inward shifted configurations in LHD (depending on the relative locations of heating position and 2/1 island) and TJ-II (eITB becomes possible at higher density when 3/2 rational is introduced in the plasma core region). It is speculated that, for the latter case, the resonance causes an extra electron flux to trigger the positive Er. The interplay between low order rational surfaces and the formation of eITB still waits for the systematic experiment and theoretical analysis. The external controllability

  14. Patterns of uterine enhancement with helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, H.; Loyer, E.M.; Charnsangavej, C. [Department of Diagnostic Radiology, Box 57, The University of Texas, M.D. Anderson Cancer Center, 1515 Holcombe Blvd. Houston, TX 77030 (United States); Minami, M. [Department of Radiology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo 113 (Japan)

    1998-10-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  15. Patterns of uterine enhancement with helical CT

    International Nuclear Information System (INIS)

    Kaur, H.; Loyer, E.M.; Charnsangavej, C.; Minami, M.

    1998-01-01

    Objective: The purpose of this study was to evaluate the enhancement characteristics of the normal uterine body and cervix using dynamic contrast-enhanced helical CT. Methods: Thirty-eight women scheduled for pelvic CT for non-gynecologic malignancies underwent dynamic contrast-enhanced helical CT of the pelvis. Data acquisition was during the arterial phase (30-45 s after the start of injection), the parenchymal phase (90-120 s after the start of injection), and delayed phase (3-9 min after the start of injection). The images were evaluated by four radiologists for the pattern of myometrial and cervical enhancement. Correlation was made with the age and menstrual status of the patients. Results: In the uterine body, three types of enhancement were observed. Type 1 enhancement, seen in 16 patients (42%), was characterized by the visualization of a subendometrial zone of enhancement, 30-120 s after the start of injection. Eight of these patients also showed an enhancing zone in the outer myometrium. Both zones were transitory, and in all cases, the uterus became homogeneous in the delayed phase. This pattern was seen predominantly in premenopausal women with a mean age of 34 years. Type 2 enhancement, seen in 17 cases (45%), was defined by the absence of subendometrial enhancement in the early phase. Enhancement was either diffuse from the outset or originated in the outer myometrium. This pattern was seen nearly equally in premenopausal and postmenopausal women with a mean age of 40 years. Type 3 enhancement was seen in five postmenopausal patients (13%) with a mean age of 53 years and was characterized by faint diffuse enhancement. In the cervix, a zonal pattern of enhancement defining inner and outer stroma was seen in 23 patients (61%). Fifteen patients were premenopausal and eight were postmenopausal. Conclusion: In this study, we have shown a transitory zonal distribution of the contrast in the myometrium and cervix using dynamic contrast-enhanced helical CT

  16. Dairy products and plasma cholesterol levels

    Directory of Open Access Journals (Sweden)

    Lena Ohlsson

    2010-08-01

    Full Text Available Cholesterol synthesized in the body or ingested is an essential lipid component for human survival from our earliest life. Newborns ingest about 3–4 times the amount per body weight through mother's milk compared to the dietary intake of adults. A birth level of 1.7 mmol/L plasma total cholesterol will increase to 4–4.5 mmol/L during the nursing period and continue to increase from adulthood around 40% throughout life. Coronary artery disease and other metabolic disorders are strongly associated with low-density lipoprotein (LDL and high-density lipoprotein (HDL cholesterol as well as triacylglycerol concentration. Milk fat contains a broad range of fatty acids and some have a negative impact on the cholesterol rich lipoproteins. The saturated fatty acids (SFAs, such as palmitic acid (C16:0, myristic acid (C14:0, and lauric acid (C12:0, increase total plasma cholesterol, especially LDL, and constitute 11.3 g/L of bovine milk, which is 44.8% of total fatty acid in milk fat. Replacement of dairy SFA and trans-fatty acids with polyunsaturated fatty acids decreases plasma cholesterol, especially LDL cholesterol, and is associated with a reduced risk of cardiovascular disease. Available data shows different effects on lipoproteins for different dairy products and there is uncertainty as to the impact a reasonable intake amount of dairy items has on cardiovascular risk. The aim of this review is to elucidate the effect of milk components and dairy products on total cholesterol, LDL, HDL, and the LDL/HDL quotients. Based on eight recent randomized controlled trials of parallel or cross-over design and recent reviews it can be concluded that replacement of saturated fat mainly (but not exclusively derived from high-fat dairy products with low-fat dairy products lowers LDL/HDL cholesterol and total/HDL cholesterol ratios. Whey, dairy fractions enriched in polar lipids, and techniques such as fermentation, or fortification of cows feeding can be used

  17. Modeling the excitation of graphene plasmons in periodic grids of graphene ribbons: An analytical approach

    DEFF Research Database (Denmark)

    Gonçalves, P:A.D.; Dias, E. J. C.; Bludov, Yu V.

    2016-01-01

    We study electromagnetic scattering and subsequent plasmonic excitations in periodic grids of graphene ribbons. To address this problem, we develop an analytical method to describe the plasmon-assisted absorption of electromagnetic radiation by a periodic structure of graphene ribbons forming...... a diffraction grating for THz and mid-IR light. The major advantage of this method lies in its ability to accurately describe the excitation of graphene surface plasmons (GSPs) in one-dimensional (1D) graphene gratings without the use of both time-consuming, and computationally demanding full-wave numerical...... compare the theoretical data with spectra taken from experiments, for which we observe a very good agreement. These theoretical tools may therefore be applied to design new experiments and cutting-edge nanophotonic devices based on graphene plasmonics....

  18. Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons

    International Nuclear Information System (INIS)

    De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Quaresima, Claudio; Cricenti, Antonio; Olivieri, Bruno; Dávila, Maria E; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

    2013-01-01

    The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

  19. Laser assisted crystallization of ferromagnetic amorphous ribbons: A multimodal characterization and thermal model study

    Energy Technology Data Exchange (ETDEWEB)

    Katakam, Shravana; Santhanakrishnan, S.; Smith, Casey; Banerjee, Rajarshi; Dahotre, Narendra B. [Laboratory of Laser Materials Processing and Synthesis Department of Materials Science and Engineering University of North Texas, Denton, Texas 76207 (United States); Devaraj, Arun; Bowden, Mark; Thevuthasan, Suntharampillai [William R. Wiley Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States); Ramanujan, R. V. [Schhol of Materials Science and Engineering Nanyang Technological University, Singapore 639798 (Singapore)

    2013-11-14

    This paper focuses on laser-based de-vitrification of amorphous soft magnetic Fe-Si-B ribbons and its consequent influence on the magnetic properties. Laser processing resulted in a finer scale of crystallites due to rapid heating and cooling during laser annealing compared to conventional furnace annealing process. A significant increase in saturation magnetization is observed for laser-annealed ribbons compared to both as-received and furnace annealed samples coupled with an increase in coercivity compared to the as received samples. The combined effect of thermal histories and stresses developed during laser annealing results in the formation of nano-crystalline phase along the laser track. The phase evolution is studied by micro-XRD and TEM analysis. Solute partitioning and compositional variation within the phases are obtained by Local Electrode Atom probe analysis. The evolution of microstructure is rationalized using a Finite Element based heat transfer multi-physics model.

  20. Flat-plate solar array project. Volume 3: Silicon sheet: Wafers and ribbons

    Science.gov (United States)

    Briglio, A.; Dumas, K.; Leipold, M.; Morrison, A.

    1986-01-01

    The primary objective of the Silicon Sheet Task of the Flat-Plate Solar Array (FSA) Project was the development of one or more low cost technologies for producing silicon sheet suitable for processing into cost-competitive solar cells. Silicon sheet refers to high purity crystalline silicon of size and thickness for fabrication into solar cells. Areas covered in the project were ingot growth and casting, wafering, ribbon growth, and other sheet technologies. The task made and fostered significant improvements in silicon sheet including processing of both ingot and ribbon technologies. An additional important outcome was the vastly improved understanding of the characteristics associated with high quality sheet, and the control of the parameters required for higher efficiency solar cells. Although significant sheet cost reductions were made, the technology advancements required to meet the task cost goals were not achieved.

  1. Megalencephaly, polymicrogyria and ribbon-like band heterotopia: A new cortical malformation.

    Science.gov (United States)

    Kobayashi, Yu; Magara, Shinichi; Okazaki, Kenichi; Komatsubara, Takao; Saitsu, Hirotomo; Matsumoto, Naomichi; Kato, Mitsuhiro; Tohyama, Jun

    2016-11-01

    Megalencephalic polymicrogyria syndromes include megalencephaly-capillary malformation and megalencephaly-polymicrogyria-polydactyly-hydrocephalus. Recent genetic studies have identified that genes in the PI3K-AKT pathway are involved in the pathogenesis of these disorders. Herein, we report a patient who presented with developmental delay, epilepsy and peculiar neuroimaging findings of megalencephaly, polymicrogyria, and symmetrical band heterotopia in the periventricular region. The heterotopias exhibited inhomogeneous signals with undulatory mixtures of gray and white matter, resembling ribbon-like heterotopia, with a predominance in the temporal to occipital regions. These neuroradiological findings were not consistent with those in known megalencephalic polymicrogyria syndromes. No genetic abnormality was identified through whole-exome sequencing. The neuroimaging findings of this patient may represent a novel cortical malformation involving megalencephaly with polymicrogyria and ribbon-like band heterotopia. Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  2. Ribbon scanning confocal for high-speed high-resolution volume imaging of brain.

    Directory of Open Access Journals (Sweden)

    Alan M Watson

    Full Text Available Whole-brain imaging is becoming a fundamental means of experimental insight; however, achieving subcellular resolution imagery in a reasonable time window has not been possible. We describe the first application of multicolor ribbon scanning confocal methods to collect high-resolution volume images of chemically cleared brains. We demonstrate that ribbon scanning collects images over ten times faster than conventional high speed confocal systems but with equivalent spectral and spatial resolution. Further, using this technology, we reconstruct large volumes of mouse brain infected with encephalitic alphaviruses and demonstrate that regions of the brain with abundant viral replication were inaccessible to vascular perfusion. This reveals that the destruction or collapse of large regions of brain micro vasculature may contribute to the severe disease caused by Venezuelan equine encephalitis virus. Visualization of this fundamental impact of infection would not be possible without sampling at subcellular resolution within large brain volumes.

  3. Surface plasmon enhanced absorption and suppressed transmission in periodic arrays of graphene ribbons

    Science.gov (United States)

    Nikitin, A. Yu.; Guinea, F.; Garcia-Vidal, F. J.; Martin-Moreno, L.

    2012-02-01

    Resonance diffraction in the periodic array of graphene microribbons is theoretically studied following a recent experiment [L. Ju , Nature Nanotech.1748-338710.1038/nnano.2011.146 6, 630 (2011)]. Systematic studies over a wide range of parameters are presented. It is shown that a much richer resonant picture would be observable for higher relaxation times of charge carriers: More resonances appear and transmission can be totally suppressed. The comparison with the absorption cross-section of a single ribbon shows that the resonant features of the periodic array are associated with leaky plasmonic modes. The longest-wavelength resonance provides the highest visibility of the transmission dip and has the strongest spectral shift and broadening with respect to the single-ribbon resonance, due to collective effects.

  4. Effects of material non-linearity on the residual stresses in a dendritic silicon crystal ribbon

    Science.gov (United States)

    Ray, Sujit K.; Utku, Senol

    1990-01-01

    Thermal stresses developed in a dendritic silicon crystal ribbon have been shown to cause plastic deformation and residual stresses in the ribbon. This paper presents an implementation of a numerical model proposed for thermoelastoplastic behavior of a material. The model has been used to study the effects of plasticity of silicon on the residual stresses. The material properties required to implement this model are all assumed, and the response of the material to the variations in these assumed parameters of the constitutive law and in the finite element mesh is investigated. The steady state growth process is observed to be periodic with nonzero residual stresses. Numerical difficulties are also encountered in the computer solution process, resulting in sharp jumps and large oscillations in the stress responses.

  5. Mössbauer and Kerr microscopy investigation of crystallization in FeCoB ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, V. Raghavendra, E-mail: varimalla@yahoo.com, E-mail: vrreddy@csr.res.in; Hussain, Zaineb; Babu, Hari [UGC DAE Consortium for Scientific Research, University Campus, Kandhwa Road, Indore-452001 India (India); Shrivastava, Namrata [School of Physics, DAVV, Khandwa Road, Indore – 452001 India (India); Gupta, Ajay [Amity Centre for Spintronic Materials, Amity University, Noida 201303.India (India)

    2016-05-23

    The present work reports the crystallization study of amorphous FeCoB ribbons using x-ray diffraction, {sup 57}Fe Mössbauer spectroscopy in transmission mode and magneto-optical Kerr (MOKE) microscopy. Annealing at 673 K is found to result in crystallization. From the Mossbauer measurements it is observed that the Fe magnetic moments are in the plane of sample for as-cast ribbon; α-FeCo, (Fe{sub 0.5}Co{sub 0.5}){sub 2}B and Fe{sub 2}B phases are formed after crystallization. MOKE microscopy revealed that wide 180° domain walls & narrow fingerprint domains are observed before crystallization and fine domains are observed after crystallization. The results are explained in terms of the presence of internal stresses and their annealing with thermal heat treatment.

  6. Magnetic properties of fcc (Co95Fe5)1-xAlx ribbons

    International Nuclear Information System (INIS)

    Makhlouf, Salah A.; Parker, F.T.; Benameur, T.

    1999-01-01

    Rapidly quenched (Co 95 Fe 5 ) 1-x Al x ribbons are investigated by X-ray diffraction, magnetization, and Moessbauer effect measurements. A single fcc phase is obtained for all ribbons x ≤ 10 at.%. The lattice constant increases linearly with x and is discussed in connection with magnetic moment. The influence of Al substitution on both magnetization and Fe-atom hyperfine field (H) is studied. At 296 K, the magnetization decreases linearly while H drops nonlinearly as x increases. Al substitution leads to substantial differences in iron hyperfine fields in bcc and fcc systems. Fe moment is perturbed differently by Al substitution in fcc (Co 95 Fe 5 ) 1-x Al x and bcc Fe-Al systems

  7. Corrosion-resistant amorphous alloy ribbons for electromagnetic filtration of iron rusts from water

    International Nuclear Information System (INIS)

    Kawashima, Asahi; Asami, Katsuhiko; Sato, Takeaki; Hashimoto, Koji

    1985-01-01

    An attempt was made to use corrosion-resistant amorphous Fe-9Cr-13P-7C alloy ribbons as an electromagnetic filter material for trapping various iron rusts suspended in water at 40 0 C. The ferrimagnetic Fe 3 O 4 rust was trapped with the 100 % efficiency and paramagnetic rusts such as α-Fe 2 O 3 , α-FeOOH and amorphous ferric oxyhydroxide were trapped with certain efficiencies at the magnetic field strength of 0.5-10 kOe. The regeneration of the filter by back-washing was easy. The trapping capacity of electromagnetic filter was proportional to the edge length of the filter material where the high magnetic field strength existed. Therefore, melt-spun thin and narrow amorphous alloy ribbons having the high corrosion resistance have the potential utility as electromagnetic filter material. (author)

  8. Comparison of mechanical behavior between bulk and ribbon Cu-based metallic glasses

    International Nuclear Information System (INIS)

    Jiang, W.H.; Liu, F.X.; Wang, Y.D.; Zhang, H.F.; Choo, H.; Liaw, P.K.

    2006-01-01

    As-cast bulk and as-spun ribbon Cu 60 Zr 30 Ti 10 metallic glasses were characterized using differential-scanning calorimetry and instrumented nanoindentation. Two alloys show a significant difference in the amount of free volume, which is attributed to the difference in a cooling rate, while exhibiting a similar serrated plastic flow. Atomic-force-microscopy observations demonstrate the pile-ups containing shear bands around the indents in both alloys. The as-cast bulk alloy has higher hardness and elastic modulus than the as-spun ribbon alloy. The difference in the strengths of two alloys may be related to the different amount of free volume. The strength seems to be more sensitive to a cooling rate during solidification than the plastic-flow behavior in the Cu 60 Zr 30 Ti 10

  9. Manifold-splitting regularization, self-linking, twisting, writhing numbers of space-time ribbons

    International Nuclear Information System (INIS)

    Tze, C.H.

    1988-01-01

    The authors present an alternative formulation of Polyakov's regularization of Gauss' integral formula for a single closed Feynman path. A key element in his proof of the D = 3 fermi-bose transmutations induced by topological gauge fields, this regularization is linked here with the existence and properties of a nontrivial topological invariant for a closed space ribbon. This self-linking coefficient, an integer, is the sum of two differential characteristics of the ribbon, its twisting and writhing numbers. These invariants form the basis for a physical interpretation of our regularization. Their connection to Polyakov's spinorization is discussed. The authors further generalize their construction to the self-linking, twisting and writhing of higher dimensional d = eta(odd) submanifolds in D = (2eta + 1) space-time

  10. Fabrication of Fe-6.5wt%Si Ribbons by Melt Spinning Method on Large Scale

    Directory of Open Access Journals (Sweden)

    Y. F. Liang

    2015-01-01

    Full Text Available Melt spinning method has been widely applied for fabrication of Fe-based amorphous/nanocrystalline ribbons in industry. Compared with Fe-based amorphous/nanocrystalline alloys, Fe-6.5wt%Si high silicon steel is of low cost and has comparable excellent soft magnetic properties. Due to higher melting point and absence of supercooled liquid region, fabrication of Fe-6.5wt%Si ribbons is very hard and is only on lab scale. In this paper, we report that large scale fabrication of Fe-6.5wt%Si ribbons was successful and microstructures, ordered structures, and mechanical and soft magnetic properties of the ribbons were investigated. Due to rapid solidification rate, the ribbons were of ultrafine grains, and low degree of order and exhibited some extent of bending and tensile ductility. After heat treatment, excellent soft magnetic properties were obtained. Due to near-zero magnetostriction, the ribbons are promising to be used in electric devices with high frequencies where low noises are required.

  11. Surface and bulk magnetic properties of as-quenched FeNbB ribbons

    Czech Academy of Sciences Publication Activity Database

    Životský, O.; Postava, K.; Kraus, Luděk; Juraszek, J.; Jirásková, Yvonna; Teillet, J.; Barčová, K.; Švec, P.; Janičkovič, D.; Pištora, J.

    2008-01-01

    Roč. 320, č. 8 (2008), s. 1535-1540 ISSN 0304-8853 R&D Projects: GA ČR GA202/05/2111; GA AV ČR KAN400100653 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z10100520 Keywords : Surface nanocrystallization * Fe-based ribbon * depth profile Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.283, year: 2008

  12. Silicon ribbon technology assessment 1978-1986 - A computer-assisted analysis using PECAN

    Science.gov (United States)

    Kran, A.

    1978-01-01

    The paper presents a 1978-1986 economic outlook for silicon ribbon technology based on the capillary action shaping technique. The outlook is presented within the framework of two sets of scenarios, which develop strategy for approaching the 1986 national energy capacity cost objective of $0.50/WE peak. The PECAN (Photovoltaic Energy Conversion Analysis) simulation technique is used to develop a 1986 sheet material price ($50/sq m) which apparently can be attained without further scientific breakthrough.

  13. Morphdynamics of Beaches in the Tróia-Sines Littoral Ribbon (SW Portugal)

    OpenAIRE

    Gama, Cristina; Andrade, César; Taborda, Rui; Freitas, Conceição

    2006-01-01

    In the Tróia-Sines littoral ribbon five beaches were monitored in order to evaluate morphological and textural changes. The textural analysis reveals a southward coarsening trend that reflects an increase in the wave energy. The morphodynamic data indicate that the modal stages are intermediate to reflective, and that the available beach volume increases southwards. During storm periods the volumetric changes reach 15% to 82% of the beach envelope corresponding to magnitudes of 6x10 3 to 2x10...

  14. Magnetocaloric properties of rapidly solidified Dy{sub 3}Co alloy ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez Llamazares, J. L., E-mail: jose.sanchez@ipicyt.edu.mx; Flores-Zúñiga, H.; Sánchez-Valdés, C. F. [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055 Col. Lomas 4" a, San Luis Potosí, S.L.P. 78216 (Mexico); Álvarez-Alonso, Pablo [Departamento de Electricidad y Electrónica, UPV/EHU, 48940 Leioa (Spain); Lara Rodríguez, G. A. [Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, México, D. F. 04510 (Mexico); Fernández-Gubieda, M. L. [Departamento de Electricidad y Electrónica, UPV/EHU, 48940 Leioa (Spain); BC Materials, Camino de Ibaizabal, Edificio 500, Planta 1, Parque Científico y Tecnológico de Zamudio, 48160 Derio (Spain)

    2015-05-07

    The magnetic and magnetocaloric (MC) properties of melt-spun ribbons of the Dy{sub 3}Co intermetallic compound were investigated. Samples were fabricated in an Ar environment using a homemade melt spinner system at a linear speed of the rotating copper wheel of 40 ms{sup −1}. X-ray diffraction analysis shows that ribbons crystallize into a single-phase with the Fe{sub 3}C-type orthorhombic crystal structure. The M(T) curve measured at 5 mT reveals the occurrence of a transition at 32 K from a first to a second antiferromagnetic (AFM) state and an AFM-to-paramagnetic transition at T{sub N} = 43 K. Furthermore, a metamagnetic transition is observed below T{sub N}, but the magnetization change ΔM is well below the one reported for bulk alloys. Below 12 K, large inverse MC effect and hysteresis losses are observed. This behavior is related to the metamagnetic transition. For a magnetic field change of 5 T (2 T) applied along the ribbon length, the produced ribbons show a peak value of the magnetic entropy change ΔS{sub M}{sup peak} of −6.5 (− 2.1) Jkg{sup −1}K{sup −1} occurring close to T{sub N} with a full-width at half-maximum δT{sub FWHM} of 53 (37) K, and refrigerant capacity RC = 364 (83) Jkg{sup −1} (estimated from the product |ΔS{sub M}{sup peak}| × δT{sub FWHM})

  15. Microstructure, mechanical and functional properties of NiTi-based shape memory ribbons

    International Nuclear Information System (INIS)

    Mehrabi, K.; Bruncko, M.; Kneissl, A.C.

    2012-01-01

    Highlights: ► Melt-spun samples exhibited martensite structure and shape memory effects immediately after processing at room temperature. ► Using a new etchant and interference contrast, it is possible to reveal the fine microstructures and grain boundaries. ► The martensite structure in NiTi is very fine, and nano-sized twin boundaries could be revealed using TEM only. ► Two-way effects have been successfully introduced by different thermomechanical training methods in NiTi, NiTiCu and NiTiW alloys, which can be used for several applications, e.g. microsensors and microactuators. - Abstract: The present work has been aimed to study the microstructures, functional properties and the influence of different thermomechanical training methods on the two-way shape memory effect in NiTi-based melt-spun ribbons. In order to get small-dimensioned shape memory alloys (SMAs) with good functional and mechanical properties, a rapid solidification technique was employed. Their fracture and elasticity characteristics have been determined, as well as shape memory properties by thermomechanical cycling. The ribbons were trained under tensile and bending deformation by thermal cycling through the phase transformation temperature range. The results displayed that all different training methods were effective in developing a two-way shape memory effect (TWSME). The influence of copper (5–25 at.% Cu) and tungsten (2 at.% W) on the microstructure, and the functional and mechanical behavior of NiTi thin ribbons was also investigated. All samples show a shape memory effect immediately after processing without further heat treatment. The melt-spun ribbons were trained under constant strain (bending and tensile deformation) by thermal cycling through the phase transformation temperature range. The addition of copper was effective to narrow the transformation hysteresis. The W addition has improved the TWSME stability of the NiTi alloys and mechanical properties. Results about

  16. Adenine ribbon stabilized by Watson–Crick and Hoogsteen hydrogen Bonds: WFT and DFT study

    Czech Academy of Sciences Publication Activity Database

    Zierkiewicz, W.; Michalska, D.; Hobza, Pavel

    2010-01-01

    Roč. 12, č. 12 (2010), s. 2888-2894 ISSN 1463-9076 R&D Projects: GA MŠk LC512 Grant - others:Wroclaw University of Technology(PL) 343974/Z0304 Institutional research plan: CEZ:AV0Z40550506 Keywords : adenine ribbon * ab initio correlated calculations * self- organization Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.454, year: 2010

  17. Strain sensors for civil engineering application based on CoFeCrSiB amorphous ribbons

    Czech Academy of Sciences Publication Activity Database

    Bydžovský, J.; Kollár, M.; Jančárik, V.; Švec, P.; Kraus, Luděk

    2002-01-01

    Roč. 52, Suppl. A (2002), s. A117-A120 ISSN 0011-4626. [Czech and Slovak Conference on Magnetism. Košice, 20.08.2001-23.08.2001] Grant - others:NATO(XX) SfP973649; VEGA(XX) 1/7609/20 Institutional research plan: CEZ:AV0Z1010914 Keywords : magnetic amorphous ribbon * stress-induced anisotropy * strain sensor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.311, year: 2002

  18. Cholesterol and ocular pathologies: focus on the role of cholesterol-24S-hydroxylase in cholesterol homeostasis

    Directory of Open Access Journals (Sweden)

    Fourgeux Cynthia

    2015-03-01

    Full Text Available The retina is responsible for coding the light stimulus into a nervous signal that is transferred to the brain via the optic nerve. The retina is formed by the association of the neurosensory retina and the retinal pigment epithelium that is supported by Bruch’s membrane. Both the physical and metabolic associations between these partners are crucial for the functioning of the retina, by means of nutrient intake and removal of the cell and metabolic debris from the retina. Dysequilibrium are involved in the aging processes and pathologies such as age-related macular degeneration, the leading cause of visual loss after the age of 50 years in Western countries. The retina is composed of several populations of cells including glia that is involved in cholesterol biosynthesis. Cholesterol is the main sterol in the retina. It is present as free form in cells and as esters in Bruch’s membrane. Accumulation of cholesteryl esters has been associated with aging of the retina and impairment of the retinal function. Under dietary influence and in situ synthesized, the metabolism of cholesterol is regulated by cell interactions, including neurons and glia via cholesterol-24S-hydroxylase. Several pathophysiological associations with cholesterol and its metabolism can be suggested, especially in relation to glaucoma and age-related macular degeneration.

  19. Intracellular cholesterol-binding proteins enhance HDL-mediated cholesterol uptake in cultured primary mouse hepatocytes.

    Science.gov (United States)

    Storey, Stephen M; McIntosh, Avery L; Huang, Huan; Landrock, Kerstin K; Martin, Gregory G; Landrock, Danilo; Payne, H Ross; Atshaves, Barbara P; Kier, Ann B; Schroeder, Friedhelm

    2012-04-15

    A major gap in our knowledge of rapid hepatic HDL cholesterol clearance is the role of key intracellular factors that influence this process. Although the reverse cholesterol transport pathway targets HDL to the liver for net elimination of free cholesterol from the body, molecular details governing cholesterol uptake into hepatocytes are not completely understood. Therefore, the effects of sterol carrier protein (SCP)-2 and liver fatty acid-binding protein (L-FABP), high-affinity cholesterol-binding proteins present in hepatocyte cytosol, on HDL-mediated free cholesterol uptake were examined using gene-targeted mouse models, cultured primary hepatocytes, and 22-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)-amino]-23,24-bisnor-5-cholen-3β-ol (NBD-cholesterol). While SCP-2 overexpression enhanced NBD-cholesterol uptake, counterintuitively, SCP-2/SCP-x gene ablation also 1) enhanced the rapid molecular phase of free sterol uptake detectable in rate and maximal uptake of HDL free cholesterol and 2) differentially enhanced free cholesterol uptake mediated by the HDL3, rather than the HDL2, subfraction. The increased HDL free cholesterol uptake was not due to increased expression or distribution of the HDL receptor [scavenger receptor B1 (SRB1)], proteins regulating SRB1 [postsynaptic density protein (PSD-95)/Drosophila disk large tumor suppressor (dlg)/tight junction protein (ZO1) and 17-kDa membrane-associated protein], or other intracellular cholesterol trafficking proteins (steroidogenic acute response protein D, Niemann Pick C, and oxysterol-binding protein-related proteins). However, expression of L-FABP, the single most prevalent hepatic cytosolic protein that binds cholesterol, was upregulated twofold in SCP-2/SCP-x null hepatocytes. Double-immunogold electron microscopy detected L-FABP sufficiently close to SRB1 for direct interaction, similar to SCP-2. These data suggest a role for L-FABP in HDL cholesterol uptake, a finding confirmed with SCP-2/SCP-x/L-FABP null

  20. Taurine ameliorates cholesterol metabolism by stimulating bile acid production in high-cholesterol-fed rats.

    Science.gov (United States)

    Murakami, Shigeru; Fujita, Michiko; Nakamura, Masakazu; Sakono, Masanobu; Nishizono, Shoko; Sato, Masao; Imaizumi, Katsumi; Mori, Mari; Fukuda, Nobuhiro

    2016-03-01

    This study was designed to investigate the effects of dietary taurine on cholesterol metabolism in high-cholesterol-fed rats. Male Sprague-Dawley rats were randomly divided into two dietary groups (n = 6 in each group): a high-cholesterol diet containing 0.5% cholesterol and 0.15% sodium cholate, and a high-cholesterol diet with 5% (w/w) taurine. The experimental diets were given for 2 weeks. Taurine supplementation reduced the serum and hepatic cholesterol levels by 37% and 32%, respectively. Faecal excretion of bile acids was significantly increased in taurine-treated rats, compared with untreated rats. Biliary bile acid concentrations were also increased by taurine. Taurine supplementation increased taurine-conjugated bile acids by 61% and decreased glycine-conjugated bile acids by 53%, resulting in a significant decrease in the glycine/taurine (G/T) ratio. Among the taurine-conjugated bile acids, cholic acid and deoxycholic acid were significantly increased. In the liver, taurine supplementation increased the mRNA expression and enzymatic activity of hepatic cholesterol 7α-hydroxylase (CYP7A1), the rate-limiting enzyme for bile acid synthesis, by three- and two-fold, respectively. Taurine also decreased the enzymatic activity of acyl-CoA:cholesterol acyltransferase (ACAT) and microsomal triglyceride transfer protein (MTP). These observations suggest that taurine supplementation increases the synthesis and excretion of taurine-conjugated bile acids and stimulates the catabolism of cholesterol to bile acid by elevating the expression and activity of CYP7A1. This may reduce cholesterol esterification and lipoprotein assembly for very low density lipoprotein (VLDL) secretion, leading to reductions in the serum and hepatic cholesterol levels. © 2016 John Wiley & Sons Australia, Ltd.

  1. Chaotic coordinates for the Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Hudson, S. R., E-mail: shudson@pppl.gov [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States); Suzuki, Y. [National Institute for Natural Sciences, National Institute for Fusion Sciences, 322-6 Oroshi, Toki, 509-5292 (Japan)

    2014-10-15

    The theory of quadratic-flux-minimizing (QFM) surfaces is reviewed, and numerical techniques that allow high-order QFM surfaces to be efficiently constructed for experimentally relevant, non-integrable magnetic fields are described. As a practical example, the chaotic edge of the magnetic field in the Large Helical Device (LHD) is examined. A precise technique for finding the boundary surface is implemented, the hierarchy of partial barriers associated with the near-critical cantori is constructed, and a coordinate system, which we call chaotic coordinates, that is based on a selection of QFM surfaces is constructed that simplifies the description of the magnetic field, so that flux surfaces become “straight” and islands become “square.”.

  2. Helical spin rotators and snakes for RHIC

    International Nuclear Information System (INIS)

    Ptitsin, V.I.; Shatunov, Yu.M.; Peggs, S.

    1995-01-01

    The RHIC collider, now under construction at BNL, will have the possibility of polarized proton-proton collisions up to a beam energy of 250 Gev. Polarized proton beams of such high energy can be only obtained with the use of siberian snakes, a special kind of spin rotator that rotates the particle spin by 180 degree around an axis lying in the horizontal plane. Siberian snakes help to preserve the beam polarization while numerous spin depolarizing resonances are crossed, during acceleration. In order to collide longitudinally polarized beams, it is also planned to install spin rotators around two interaction regions. This paper discusses snake and spin rotator designs based on sequences of four helical magnets. The schemes that were chosen to be applied at RHIC are presented

  3. ATLAS helicity analyses in beauty hadron decays

    CERN Document Server

    Smizanska, M

    2000-01-01

    The ATLAS detector will allow a precise spatial reconstruction of the kinematics of B hadron decays. In combination with the efficient lepton identification applied already at trigger level, ATLAS is expected to provide large samples of exclusive decay channels cleanly separable from background. These data sets will allow spin-dependent analyses leading to the determination of production and decay parameters, which are not accessible if the helicity amplitudes are not separated. Measurement feasibility studies for decays B/sub s //sup 0/ to J/ psi phi and Lambda /sub b//sup 0/ to Lambda J/ psi , presented in this document, show the experimental precisions that can be achieved in determination of B/sub s//sup 0/ and Lambda /sub b //sup 0/ characteristics. (19 refs).

  4. Conditioner for a helically transported electron beam

    International Nuclear Information System (INIS)

    Wang, Changbiao.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically transported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value

  5. Conditioner for a helically transported electron beam

    International Nuclear Information System (INIS)

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value

  6. Microinstability Studies for the Large Helical Device

    International Nuclear Information System (INIS)

    Rewoldt, G.; Ku, L.-P.; Tang, W.M.; Sugama, H.; Nakajima, N.; Watanabe, K.Y.; Murakami, S.; Yamada, H.; Cooper, W.A.

    2002-01-01

    Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the Large Helical Device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc., for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared

  7. The Role of Macrophage Lipophagy in Reverse Cholesterol Transport

    Directory of Open Access Journals (Sweden)

    Se-Jin Jeong

    2017-03-01

    Full Text Available Macrophage cholesterol efflux is a central step in reverse cholesterol transport, which helps to maintain cholesterol homeostasis and to reduce atherosclerosis. Lipophagy has recently been identified as a new step in cholesterol ester hydrolysis that regulates cholesterol efflux, since it mobilizes cholesterol from lipid droplets of macrophages via autophagy and lysosomes. In this review, we briefly discuss recent advances regarding the mechanisms of the cholesterol efflux pathway in macrophage foam cells, and present lipophagy as a therapeutic target in the treatment of atherosclerosis.

  8. Enhanced piezoelectricity and stretchability in energy harvesting devices fabricated from buckled PZT ribbons.

    Science.gov (United States)

    Qi, Yi; Kim, Jihoon; Nguyen, Thanh D; Lisko, Bozhena; Purohit, Prashant K; McAlpine, Michael C

    2011-03-09

    The development of a method for integrating highly efficient energy conversion materials onto soft, biocompatible substrates could yield breakthroughs in implantable or wearable energy harvesting systems. Of particular interest are devices which can conform to irregular, curved surfaces, and operate in vital environments that may involve both flexing and stretching modes. Previous studies have shown significant advances in the integration of highly efficient piezoelectric nanocrystals on flexible and bendable substrates. Yet, such inorganic nanomaterials are mechanically incompatible with the extreme elasticity of elastomeric substrates. Here, we present a novel strategy for overcoming these limitations, by generating wavy piezoelectric ribbons on silicone rubber. Our results show that the amplitudes in the waves accommodate order-of-magnitude increases in maximum tensile strain without fracture. Further, local probing of the buckled ribbons reveals an enhancement in the piezoelectric effect of up to 70%, thus representing the highest reported piezoelectric response on a stretchable medium. These results allow for the integration of energy conversion devices which operate in stretching mode via reversible deformations in the wavy/buckled ribbons.

  9. Student Evaluation of the Yellow Ribbon Suicide Prevention Program in Midwest Schools

    Science.gov (United States)

    Flynn, Alexandra; Zackula, Rosalee; Klaus, Nicole M.; McGinness, Liz; Carr, Susan; Macaluso, Matthew

    2016-01-01

    Objective Yellow Ribbon is a gatekeeper-type suicide prevention program that is widely used in public schools. However, data on its effectiveness are limited. The purpose of our study was to evaluate self-reported changes in knowledge and comfort level communicating about suicide following Yellow Ribbon training for a large, representative sample of students from a public school system in the midwestern United States. Methods The program was administered to students within the same school district during 2006 through 2009. A pre-post survey using a 4-point Likert scale was administered to rate students’ knowledge of risk factors and available resources, comfort level communicating about suicide, estimate of friends at risk for suicide, and behavioral intent toward help-seeking. Results Aggregate responses from 3,257 students, aged 11 to 18 years, were collected by the schools; 51% were female, 33% were Hispanic, and 30% were white. Suicide-related knowledge of risk factors, where to go for help, and resources, along with comfort level in asking for help, all significantly improved following program participation (Cramer’s V = 0.243 to 0.376, P suicide prevention program appears to be beneficial for students in the midwestern United States. We observed significant improvement in knowledge, comfort level, and behavioral intent for help-seeking if suicidal thoughts occur. Findings also suggested that Yellow Ribbon training administered during middle school may be especially helpful for males. PMID:27733952

  10. Third nearest neighbor parameterized tight binding model for graphene nano-ribbons

    Directory of Open Access Journals (Sweden)

    Van-Truong Tran

    2017-07-01

    Full Text Available The existing tight binding models can very well reproduce the ab initio band structure of a 2D graphene sheet. For graphene nano-ribbons (GNRs, the current sets of tight binding parameters can successfully describe the semi-conducting behavior of all armchair GNRs. However, they are still failing in reproducing accurately the slope of the bands that is directly associated with the group velocity and the effective mass of electrons. In this work, both density functional theory and tight binding calculations were performed and a new set of tight binding parameters up to the third nearest neighbors including overlap terms is introduced. The results obtained with this model offer excellent agreement with the predictions of the density functional theory in most cases of ribbon structures, even in the high-energy region. Moreover, this set can induce electron-hole asymmetry as manifested in results from density functional theory. Relevant outcomes are also achieved for armchair ribbons of various widths as well as for zigzag structures, thus opening a route for multi-scale atomistic simulation of large systems that cannot be considered using density functional theory.

  11. Plasma immersion ion implantation of boron for ribbon silicon solar cells

    Directory of Open Access Journals (Sweden)

    Derbouz K.

    2013-09-01

    Full Text Available In this work, we report for the first time on the solar cell fabrication on n-type silicon RST (for Ribbon on Sacrificial Template using plasma immersion ion implantation. The experiments were also carried out on FZ silicon as a reference. Boron was implanted at energies from 10 to 15 kV and doses from 1015 to 1016 cm-2, then activated by a thermal annealing in a conventional furnace at 900 and 950 °C for 30 min. The n+ region acting as a back surface field was achieved by phosphorus spin-coating. The frontside boron emitter was passivated either by applying a 10 nm deposited SiOX plasma-enhanced chemical vapor deposition (PECVD or with a 10 nm grown thermal oxide. The anti-reflection coating layer formed a 60 nm thick SiNX layer. We show that energies less than 15 kV and doses around 5 × 1015 cm-2 are appropriate to achieve open circuit voltage higher than 590 mV and efficiency around 16.7% on FZ-Si. The photovoltaic performances on ribbon silicon are so far limited by the bulk quality of the material and by the quality of the junction through the presence of silicon carbide precipitates at the surface. Nevertheless, we demonstrate that plasma immersion ion implantation is very promising for solar cell fabrication on ultrathin silicon wafers such as ribbons.

  12. Forming three-dimensional closed shapes from two-dimensional soft ribbons by controlled buckling

    Science.gov (United States)

    Aoki, Michio; Juang, Jia-Yang

    2018-02-01

    Conventional manufacturing techniques-moulding, machining and casting-exist to produce three-dimensional (3D) shapes. However, these industrial processes are typically geared for mass production and are not directly applicable to residential settings, where inexpensive and versatile tools are desirable. Moreover, those techniques are, in general, not adequate to process soft elastic materials. Here, we introduce a new concept of forming 3D closed hollow shapes from two-dimensional (2D) elastic ribbons by controlled buckling. We numerically and experimentally characterize how the profile and thickness of the ribbon determine its buckled shape. We find a 2D master profile with which various elliptical 3D shapes can be formed. More complex natural and artificial hollow shapes, such as strawberry, hourglass and wheel, can also be achieved via strategic design and pattern engraving on the ribbons. The nonlinear response of the post-buckling regime is rationalized through finite-element analysis, which shows good quantitative agreement with experiments. This robust fabrication should complement conventional techniques and provide a rich arena for future studies on the mechanics and new applications of elastic hollow structures.

  13. Characterisation of melt spun Ni-Ti shape memory Ribbons' microstructure

    Science.gov (United States)

    Mehrabi, Kambiz; Brunčko, Mihael; Kneissl, Albert C.; Čolič, Miodrag; Stamenković, Dragoslav; Ferčec, Janko; Anžel, Ivan; Rudolf, Rebeka

    2012-06-01

    NiTi alloys are the most technologically important medical Shape Memory Alloys in a wide range of applications used in Orthopaedics, Neurology, Cardiology and interventional Radiology as guide-wires, self-expandable stents, stent grafts, inferior vena cava filters and clinical instruments. This paper discusses the use of rapid solidification by the melt spinning method for the preparation of thin NiTi ribbons for medical uses. Generally, the application of rapid solidification via melt-spinning can change the microstructure drastically, which improves ductility and shape memory characteristics and leads to samples with small dimensions. As the increase in the wheel speed led to a reduced ribbon thickness, the cooling rate increased and, therefore, the martensitic substructure became finer. Furthermore, no transition from the crystalline phase to the amorphous phase was obtained by increasing the cooling rate, even at a wheel speed of 30 m/s. Specimens for our metallographic investigation were cut from the longitudinal cross sections of melt-spun ribbons. Conventional TEM studies were carried out with an acceleration voltage of 120 kV. Additionally, the chemical composition of the samples was examined with a TEM equipped with an EDX analyser. The crystallographic structure was determined using Bragg-Brentano x-ray diffraction with Cu-Kα radiation at room temperature.

  14. Characteristic features of edge transport barrier formed in helical divertor configuration of the Large Helical Device

    International Nuclear Information System (INIS)

    Toi, K.; Ohdachi, S.; Watanabe, F.

    2006-10-01

    In a helical divertor configuration of the Large Helical Device (LHD), transport barrier was formed through low to high confinement (L-H) transition in the plasma edge region including ergodic field layer of which region is in the magnetic hill. The plasma stored energy or the averaged bulk plasma beta dia > (derived from diamagnetic measurement) starts to increase just after the transition. In the case that both dia > and line-averaged electron density e > at the transition are relatively high as dia >≥1.5% and e >≥2x10 19 m -3 , the increase is hampered by rapid growth of edge MHD modes and/or small ELM like activities just after the transition. On the other hand, the transition at lower e > (≤1.5x10 19 m -3 ) and dia > (<2%) leads to a continuous increase in the stored energy with a time scale longer than the global energy confinement time, without suffering from these MHD activities near the edge. The ETB typically formed in electron density profile extends into ergodic field layer defined in the vacuum field. The width of ETB is almost independent of the toroidal field strength from 0.5T to 1.5T and is much larger than the poloidal ion gyro-radius. When resonant helical field perturbations are applied to expand a magnetic island size at the rational surface of the rotational transform ι/2π=1 near the edge, the L-H transition is triggered at lower electron density compared with the case without the field perturbations. The application of large helical field perturbations also suppresses edge MHD modes and ELM like activities. (author)

  15. HDL cholesterol, very low levels of LDL cholesterol, and cardiovascular events

    NARCIS (Netherlands)

    Barter, Philip; Gotto, Antonio M.; LaRosa, John C.; Maroni, Jaman; Szarek, Michael; Grundy, Scott M.; Kastelein, John J. P.; Bittner, Vera; Fruchart, Jean-Charles

    2007-01-01

    BACKGROUND: High-density lipoprotein (HDL) cholesterol levels are a strong inverse predictor of cardiovascular events. However, it is not clear whether this association is maintained at very low levels of low-density lipoprotein (LDL) cholesterol. METHODS: A post hoc analysis of the recently

  16. Intestinal SR-BI does not impact cholesterol absorption or transintestinal cholesterol efflux in mice

    NARCIS (Netherlands)

    Bura, Kanwardeep S.; Lord, Caleb; Marshall, Stephanie; McDaniel, Allison; Thomas, Gwyn; Warrier, Manya; Zhang, Jun; Davis, Matthew A.; Sawyer, Janet K.; Shah, Ramesh; Wilson, Martha D.; Dikkers, Arne; Tietge, Uwe J. F.; Collet, Xavier; Rudel, Lawrence L.; Temel, Ryan E.; Brown, J. Mark

    Reverse cholesterol transport (RCT) can proceed through the classic hepatobiliary route or through the non-biliary transintestinal cholesterol efflux (TICE) pathway. Scavenger receptor class B type I (SR-BI) plays a critical role in the classic hepatobiliary route of RCT. However, the role of SR-BI

  17. Cholesterol: Its Regulation and Role in Central Nervous System Disorders

    OpenAIRE

    Matthias Orth; Stefano Bellosta

    2012-01-01

    Cholesterol is a major constituent of the human brain, and the brain is the most cholesterol-rich organ. Numerous lipoprotein receptors and apolipoproteins are expressed in the brain. Cholesterol is tightly regulated between the major brain cells and is essential for normal brain development. The metabolism of brain cholesterol differs markedly from that of other tissues. Brain cholesterol is primarily derived by de novo synthesis and the blood brain barrier prevents the uptake of lipoprotein...

  18. Melanocortin signaling in the CNS directly regulates circulating cholesterol

    OpenAIRE

    Perez-Tilve, Diego; Hofmann, Susanna M; Basford, Joshua; Nogueiras, Ruben; Pfluger, Paul T; Patterson, James T; Grant, Erin; Wilson-Perez, Hilary E; Granholm, Norman A; Arnold, Myrtha; Trevaskis, James L; Butler, Andrew A; Davidson, William S; Woods, Stephen C; Benoit, Stephen C

    2010-01-01

    Cholesterol circulates in the blood in association with triglycerides and other lipids, and elevated blood low-density lipoprotein cholesterol carries a risk for metabolic and cardiovascular disorders, whereas high-density lipoprotein (HDL) cholesterol in the blood is thought to be beneficial. Circulating cholesterol is the balance among dietary cholesterol absorption, hepatic synthesis and secretion, and the metabolism of lipoproteins by various tissues. We found that the CNS is also an impo...

  19. [Trans-intestinal cholesterol excretion (TICE): a new route for cholesterol excretion].

    Science.gov (United States)

    Blanchard, Claire; Moreau, François; Cariou, Bertrand; Le May, Cédric

    2014-10-01

    The small intestine plays a crucial role in dietary and biliary cholesterol absorption, as well as its lymphatic secretion as chylomicrons (lipoprotein exogenous way). Recently, a new metabolic pathway called TICE (trans-intestinal excretion of cholesterol) that plays a central role in cholesterol metabolism has emerged. TICE is an inducible way, complementary to the hepatobiliary pathway, allowing the elimination of the plasma cholesterol directly into the intestine lumen through the enterocytes. This pathway is poorly characterized but several molecular actors of TICE have been recently identified. Although it is a matter of debate, two independent studies suggest that TICE is involved in the anti-atherogenic reverse cholesterol transport pathway. Thus, TICE is an innovative drug target to reduce -cardiovascular diseases. © 2014 médecine/sciences – Inserm.

  20. General architecture of the alpha-helical globule.

    Science.gov (United States)

    Murzin, A G; Finkelstein, A V

    1988-12-05

    A model is presented for the arrangement of alpha-helices in globular proteins. In the model, helices are placed on certain ribs of "quasi-spherical" polyhedra. The polyhedra are chosen so as to allow the close packing of helices around a hydrophobic core and to stress the collective interactions of the individual helices. The model predicts a small set of stable architectures for alpha-helices in globular proteins and describes the geometries of the helix packings. Some of the predicted helix arrangements have already been observed in known protein structures; others are new. An analysis of the three-dimensional structures of all proteins for which co-ordinates are available shows that the model closely approximates the arrangements and packing of helices actually observed. The average deviations of the real helix axes from those in the model polyhedra is +/- 20 degrees in orientation and +/- 2 A in position (1 A = 0.1 nm). We also show that for proteins that are not homologous, but whose helix arrangements are described by the same polyhedron, the root-mean-square difference in the position of the C alpha atoms in the helices is 1.6 to 3.0 A.

  1. MAGNETIC HELICITY FLUX IN THE PRESENCE OF SHEAR

    International Nuclear Information System (INIS)

    Hubbard, Alexander; Brandenburg, Axel

    2011-01-01

    Magnetic helicity has risen to be a major player in dynamo theory, with the helicity of the small-scale field being linked to the dynamo saturation process for the large-scale field. It is a nearly conserved quantity, which allows its evolution equation to be written in terms of production and flux terms. The flux term can be decomposed in a variety of fashions. One particular contribution that has been expected to play a significant role in dynamos in the presence of mean shear was isolated by Vishniac and Cho. Magnetic helicity fluxes are explicitly gauge dependent however, and the correlations that have come to be called the Vishniac-Cho flux were determined in the Coulomb gauge, which turns out to be fraught with complications in shearing systems. While the fluxes of small-scale helicity are explicitly gauge dependent, their divergences can be gauge independent. We use this property to investigate magnetic helicity fluxes of the small-scale field through direct numerical simulations in a shearing-box system and find that in a numerically usable gauge the divergence of the small-scale helicity flux vanishes, while the divergence of the Vishniac-Cho flux remains finite. We attribute this seeming contradiction to the existence of horizontal fluxes of small-scale magnetic helicity with finite divergences.

  2. Magnetic Helicity Flux in the Presence of Shear

    Science.gov (United States)

    Hubbard, Alexander; Brandenburg, Axel

    2011-01-01

    Magnetic helicity has risen to be a major player in dynamo theory, with the helicity of the small-scale field being linked to the dynamo saturation process for the large-scale field. It is a nearly conserved quantity, which allows its evolution equation to be written in terms of production and flux terms. The flux term can be decomposed in a variety of fashions. One particular contribution that has been expected to play a significant role in dynamos in the presence of mean shear was isolated by Vishniac & Cho. Magnetic helicity fluxes are explicitly gauge dependent however, and the correlations that have come to be called the Vishniac-Cho flux were determined in the Coulomb gauge, which turns out to be fraught with complications in shearing systems. While the fluxes of small-scale helicity are explicitly gauge dependent, their divergences can be gauge independent. We use this property to investigate magnetic helicity fluxes of the small-scale field through direct numerical simulations in a shearing-box system and find that in a numerically usable gauge the divergence of the small-scale helicity flux vanishes, while the divergence of the Vishniac-Cho flux remains finite. We attribute this seeming contradiction to the existence of horizontal fluxes of small-scale magnetic helicity with finite divergences.

  3. Magnetic Helicities and Dynamo Action in Magneto-rotational Turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Bodo, G.; Rossi, P. [INAF/Osservatorio Astrofisico di Torino, Strada Osservatorio 20, I-10025 Pino Torinese (Italy); Cattaneo, F. [Department of Astronomy and Astrophysics, The University of Chicago, 5640 S. Ellis Avenue, Chicago IL 60637 (United States); Mignone, A., E-mail: bodo@oato.inaf.it [Dipartimento di Fisica, Università degli Studi di Torino, Via Pietro Giuria 1, 10125 Torino (Italy)

    2017-07-10

    We examine the relationship between magnetic flux generation, taken as an indicator of large-scale dynamo action, and magnetic helicity, computed as an integral over the dynamo volume, in a simple dynamo. We consider dynamo action driven by magneto-rotational turbulence (MRT) within the shearing-box approximation. We consider magnetically open boundary conditions that allow a flux of helicity in or out of the computational domain. We circumvent the problem of the lack of gauge invariance in open domains by choosing a particular gauge—the winding gauge—that provides a natural interpretation in terms of the average winding number of pairwise field lines. We use this gauge precisely to define and measure the helicity and the helicity flux for several realizations of dynamo action. We find in these cases that the system as a whole does not break reflectional symmetry and that the total helicity remains small even in cases when substantial magnetic flux is generated. We find no particular connection between the generation of magnetic flux and the helicity or the helicity flux through the boundaries. We suggest that this result may be due to the essentially nonlinear nature of the dynamo processes in MRT.

  4. Fin Ray Stiffness and Fin Morphology Control Ribbon-Fin-Based Propulsion.

    Science.gov (United States)

    Liu, Hanlin; Taylor, Bevan; Curet, Oscar M

    2017-06-01

    Ribbon-fin-based propulsion has rich locomotor capabilities that can enhance the mobility and performance of underwater vehicles navigating in complex environments. Bony fishes using this type of propulsion send one or multiple traveling waves along an elongated fin with the actuation of highly flexible rays that are interconnected by an elastic membrane. In this work, we study how the use of flexible rays and different morphology can affect the performance of ribbon-fin propulsion. We developed a physical model composed of 15 rays that are interconnected with an elastic membrane. We tested four different ray flexural stiffness and four aspect ratios. The robotic model was tested in a low-turbulence flume under two flow conditions ([Formula: see text] wavelength/s). In two experimental sets, we measured fin kinematics, net surge forces, and power consumption. Using these data, we perform a thrust and power analysis of the undulating fin. We present the thrust coefficient, power coefficient, and propulsive efficiency. We find that the thrust generation was linear with the enclosed area swept by the fin, and square of the relative velocity between the incoming flow and traveling wave. The thrust coefficient levels off around 0.5. In addition, for our parameter range, we find that the power consumption scales by the cube of the effective tangential velocity of the rays [Formula: see text] (A is the amplitude of the ray oscillating motion, and [Formula: see text] is the angular velocity). We show that a decay in stiffness decreases both thrust production and power consumption. However, for rays with high flexural stiffness, the difference in thrust compared with rigid rays is minimal. Moreover, our results show that flexible rays can improve the propulsive efficiency compared with a rigid counterpart. Finally, we find that the morphology of ribbon fin affects its propulsive efficiency. For the aspect ratio considered in our experiments, [Formula: see text] was the most

  5. Plasma cholesterol and endogenous cholesterol synthesis during refeeding in anorexia nervosa.

    Science.gov (United States)

    Feillet, F; Feillet-Coudray, C; Bard, J M; Parra, H J; Favre, E; Kabuth, B; Fruchart, J C; Vidailhet, M

    2000-04-01

    Normal or high levels of cholesterol have been measured in patients with anorexia nervosa (AN). Given that cholesterol intake in AN is usually very low, the reasons for this anomaly are not clearly understood. We studied lipid and lipoprotein profiles and endogenous cholesterol synthesis, estimated by serum lathosterol, in a population of 14 girls with AN, before and during a period of 30 days refeeding. The initial body mass index (BMI) of the patients was 13.41+/-1.62 kg/m(2). No changes were observed during refeeding in endocrine parameters (ACTH, cortisol and estradiol). At Day 0 the lipids data measured here showed normal levels of triglycerides, and total cholesterol at the upper limits of the normal range (5.44+/-1 mmol/l). At this time, total and LDL cholesterol were negatively correlated with transthyretin and BMI. Serum lathosterol (a precursor in cholesterol synthesis pathway) increased significantly (5.99+/-1.75 (Day 0) vs. 8.39+/-2.96 (Day 30); P=0.02) while there was a significant decrease in apo B (0.79+/-0.33 (Day 0) vs. 0. 60+/-0.17 g/l (Day 30), P=0.02) with refeeding. Thus, patients with initial high cholesterol levels have the worst nutritional status and high cholesterol levels are not related to a de novo synthesis. This profile returns to normal with refeeding. An increase of cellular cholesterol uptake may be responsible for this apparently paradoxical evolution with increase of cholesterol synthesis and decrease of apo B during renutrition.

  6. High-n helicity-induced shear Alfven eigenmodes

    International Nuclear Information System (INIS)

    Nakajima, N.; Cheng, C.Z.; Okamoto, M.

    1992-05-01

    The high-n Helicity-induced shear Alfven Eigenmodes (HAE) are considered both analytically and numerically for the straight helical magnetic system, where n is the toroidal mode number. The eigenmode equation for the high-n HAE modes is derived along the field line and with the aid of the averaging method is shown to reduce to the Mathieu equation asymptotically. The discrete HAE modes are shown to exist inside the continuum spectrum gaps. The continuous spectrum gaps appear around ω 2 = ω A 2 [N(lι-m)/2] 2 for N = 1,2,.., where ω A is the toroidal Alfven transit frequency, and l, m, and ι are the polarity of helical coils, the toroidal pitch number of helical coils, and the rotational transform, respectively. For the same ω A and ι, the frequency of the helical continuum gap is larger than that of the continuum gap in tokamak plasmas by |l-ι -1 m|. The polarity of helical coils l plays a crucial role in determining the spectrum gaps and the properties of the high-n HAE modes. The spectrum gaps near the magnetic axis are created by the helical ripple with circular flux surfaces for l = 1, and ≥ 3 helicals. For l = 2 helical systems, the spectrum gaps are created by the ellipticity of the flux surfaces. These analytical results for the continuum gaps and the existence of the high-n HAE modes in the continuum gaps are confirmed numerically for the l = 2 case, and we find that the HAE modes exist for mode structures with the even and the odd parities. (author)

  7. Free cholesterol and cholesterol esters in bovine oocytes: Implications in survival and membrane raft organization after cryopreservation.

    Directory of Open Access Journals (Sweden)

    Jorgelina Buschiazzo

    Full Text Available Part of the damage caused by cryopreservation of mammalian oocytes occurs at the plasma membrane. The addition of cholesterol to cell membranes as a strategy to make it more tolerant to cryopreservation has been little addressed in oocytes. In order to increase the survival of bovine oocytes after cryopreservation, we proposed not only to increase cholesterol level of oocyte membranes before vitrification but also to remove the added cholesterol after warming, thus recovering its original level. Results from our study showed that modulation of membrane cholesterol by methyl-β-cyclodextrin (MβCD did not affect the apoptotic status of oocytes and improved viability after vitrification yielding levels of apoptosis closer to those of fresh oocytes. Fluorometric measurements based on an enzyme-coupled reaction that detects both free cholesterol (membrane and cholesteryl esters (stored in lipid droplets, revealed that oocytes and cumulus cells present different levels of cholesterol depending on the seasonal period. Variations at membrane cholesterol level of oocytes were enough to account for the differences found in total cholesterol. Differences found in total cholesterol of cumulus cells were explained by the differences found in both the content of membrane cholesterol and of cholesterol esters. Cholesterol was incorporated into the oocyte plasma membrane as evidenced by comparative labeling of a fluorescent cholesterol. Oocytes and cumulus cells increased membrane cholesterol after incubation with MβCD/cholesterol and recovered their original level after cholesterol removal, regardless of the season. Finally, we evaluated the effect of vitrification on the putative raft molecule GM1. Cholesterol modulation also preserved membrane organization by maintaining ganglioside level at the plasma membrane. Results suggest a distinctive cholesterol metabolic status of cumulus-oocyte complexes (COCs among seasons and a dynamic organizational structure

  8. Ordering effects of cholesterol and its analogues

    DEFF Research Database (Denmark)

    Róg, Tomasz; Pasenkiewicz-Gierula, Marta; Vattulainen, Ilpo

    2009-01-01

    Without any exaggeration, cholesterol is one of the most important lipid species in eukaryotic cells. Its effects on cellular membranes and functions range from purely mechanistic to complex metabolic ones, besides which it is also a precursor of the sex hormones (steroids) and several vitamins....... In this review, we discuss the biophysical effects of cholesterol on the lipid bilayer, in particular the ordering and condensing effects, concentrating on the molecular level or inter-atomic interactions perspective, starting from two-component systems and proceeding to many-component ones e.g., modeling lipid...... rafts. Particular attention is paid to the roles of the methyl groups in the cholesterol ring system, and their possible biological function. Although our main research methodology is computer modeling, in this review we make extensive comparisons between experiments and different modeling approaches....

  9. Radiation Field of a Square, Helical Beam Antenna

    DEFF Research Database (Denmark)

    Knudsen, Hans Lottrup

    1952-01-01

    square helices are used. Further, in connection with corresponding rigorous formulas for the field from a circular, helical antenna with a uniformly progressing current wave of constant amplitude the present formulas may be used for an investigation of the magnitude of the error introduced in Kraus......' approximate calculation of the field from a circular, helical antenna by replacing this antenna with an ``equivalent'' square helix. This investigation is carried out by means of a numerical example. The investigation shows that Kraus' approximate method of calculation yields results in fair agreement...

  10. Theoretical modeling of transport barriers in helical plasmas

    International Nuclear Information System (INIS)

    Toda, S.; Itoh, K.; Ohyabu, N.

    2008-10-01

    A unified transport modelling to explain electron Internal Transport Barriers (e-ITB) in helical plasmas and Internal Diffusion Barriers (IDB) observed in Large Helical Device (LHD) is proposed. The e-ITB can be predicted with the effect of zonal flows to obtain the e-ITB in the low collisional regime when the radial variation of the particle anomalous diffusivity is included. Transport analysis in this article can newly show that the particle fuelling induces the IDB formation when this unified transport modelling is used in the high collisional regime. The density limit for the IDB in helical plasmas is also examined including the effect of the radiation loss. (author)

  11. Drift mode calculations for the Large Helical Device

    International Nuclear Information System (INIS)

    Rewoldt, G.; Ku, L.-P.; Tang, W.M.; Sugama, H.; Nakajima, N.; Watanabe, K.Y.; Murakami, S.; Yamada, H.; Cooper, W.A.

    2000-01-01

    A fully kinetic assessment of the stability properties of toroidal drift modes has been obtained for a case for the Large Helical Device (LHD) [A.Iiyoshi, et al., Plasma Physics and Controlled Nuclear Fusion Research, 1998, Nucl.Fusion 39, 1245 (1999)]. This calculation retains the important effects in the linearized gyrokinetic equation, using the lowest-order ''ballooning representation'' for high toroidal mode number instabilities in the electrostatic limit. Results for toroidal drift waves destabilized by trapped particle dynamics and ion temperature gradients are presented, using three-dimensional magnetohydrodynamics equilibria reconstructed from experimental measurements. The effects of helically-trapped particles and helical curvature are investigated

  12. Experimental Evidence of Helical Flow in Porous Media

    DEFF Research Database (Denmark)

    Ye, Yu; Chiogna, Gabriele; Cirpka, Olaf A.

    2015-01-01

    Helical flow leads to deformation of solute plumes and enhances transverse mixing in porous media. We present experiments in which macroscopic helical flow is created by arranging different materials to obtain an anisotropic macroscopic permeability tensor with spatially variable orientation....... The resulting helical flow entails twisting streamlines which cause a significant increase in lateral mass exchange and thus a large enhancement of plume dilution (up to 235%) compared to transport in homogenous media. The setup may be used to effectively mix solutes in parallel streams similarly to static...... mixers, but in porous media....

  13. Linear local stability of electrostatic drift modes in helical systems

    International Nuclear Information System (INIS)

    Yamagishi, O.; Nakajima, N.; Sugama, H.; Nakamura, Y.

    2003-01-01

    We investigate the stability of the drift wave in helical systems. For this purpose, we solve the linear local gyrokinetic-Poisson equation, in the electrostatic regime. As a model of helical plasmas, Large helical Device (LHD) is considered. The equation we apply is rather exact in the framework of linear gyrokinetic theory, where only the approximation is the ballooning representation. In this paper, we consider only collisionless cases. All the frequency regime can be naturally reated without any assumptions, and in such cases, ion temperature gradient modes (ITG), trapped electron modes (TEM), and electron temperature gradient modes (ETG) are expected to become unstable linearly independently. (orig.)

  14. Magnetic Helical Micro- and Nanorobots: Toward Their Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Famin Qiu

    2015-03-01

    Full Text Available Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub-micrometer precision under low-strength rotating magnetic fields (<10 mT. Since magnetic fields with low strengths are harmless to cells and tissues, magnetic helical micro/nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.

  15. Characteristics of human hypo- and hyperresponders to dietary cholesterol.

    Science.gov (United States)

    Katan, M B; Beynen, A C

    1987-03-01

    The characteristics of people whose serum cholesterol level is unusually susceptible to consumption of cholesterol were investigated. Thirty-two volunteers from the general population of Wageningen, the Netherlands, each participated in three controlled dietary trials in 1982. A low-cholesterol diet was fed during the first half and a high-cholesterol diet during the second half of each trial, and the change (response) of serum cholesterol was measured. The responses in the three trials were averaged to give each subject's mean responsiveness. Fecal excretion of cholesterol and its metabolites were measured in the second trial, and body cholesterol synthesis was calculated. Responsiveness showed a positive correlation with serum high density lipoprotein2 (HDL2) cholesterol (r = 0.41, p less than 0.05) and with serum total cholesterol level on a high-cholesterol diet (r = 0.31, p = 0.09). A negative relation was found with habitual cholesterol consumption (r = -0.62, p less than 0.01), with body mass index (r = -0.50, p less than 0.01), and with the rate of endogenous cholesterol synthesis (r = -0.40, p less than 0.05), but not with the reaction of endogenous cholesterol synthesis rate to an increased intake of cholesterol. No relation was found with age, sex, total caloric needs, or the ratio of primary to secondary fecal steroids. Upon multiple regression analysis, only habitual cholesterol intake and serum total and HDL2 cholesterol levels contributed significantly to the explanation of variance in responsiveness. Thus, a low habitual cholesterol intake, a high serum HDL2 cholesterol level, or a low body weight do not make one less susceptible to dietary cholesterol-induced hypercholesterolemia.

  16. [Screening and optimization of cholesterol conversion strain].

    Science.gov (United States)

    Fan, Dan; Xiong, Bingjian; Pang, Cuiping; Zhu, Xiangdong

    2014-10-04

    Bacterial strain SE-1 capable of transforming cholesterol was isolated from soil and characterized. The transformation products were identified. Fermentation conditions were optimized for conversion. Cholesterol was used as sole carbon source to isolate strain SE-1. Morphology, physiological and biochemical characteristics of strain SE-1 were studied. 16S rRNA gene was sequenced and subjected to phylogenetic analysis. Fermentation supernatants were extracted with chloroform, the transformation products were analyzed by silica gel thin layer chromatography and Sephadex LH20. Their structures were identified by 1H-NMR and 13C-NMR. Fermentation medium including carbon and nitrogen, methods of adding substrates and fermentation conditions for Strain SE-1 were optimized. Strain SE-1 was a Gram-negative bacterium, exhibiting the highest homologs to Burkholderia cepacia based on the physiological analysis. The sequence analysis of 16S rRNA gene of SE-1 strain and comparison with related Burkholderia show that SE-1 strain was very close to B. cepacia (Genbank No. U96927). The similarity was 99%. The result of silica gel thin layer chromatography shows that strain SE-1 transformed cholesterol to two products, 7beta-hydroxycholesterol and the minor product was 7-oxocholesterol. The optimum culture conditions were: molasses 5%, (NH4 )2SO4 0.3%, 4% of inoculation, pH 7.5 and 36 degrees C. Under the optimum culture condition, the conversion rate reached 34.4% when concentration of cholesterol-Tween 80 was 1 g/L. Cholesterol 7beta-hydroxylation conversion rate under optimal conditions was improved by 20.8%. Strain SE-1 isolated from soil is capable of converting cholesterol at lab-scale.

  17. Tympanomastoid cholesterol granulomas: Immunohistochemical evaluation of angiogenesis.

    Science.gov (United States)

    Iannella, Giannicola; Di Gioia, Cira; Carletti, Raffaella; Magliulo, Giuseppe

    2017-08-01

    This study investigates the immunohistochemical expression of vascular endothelial growth factor (VEGF) and CD34 in patients treated for middle ear and mastoid cholesterol granulomas to evaluate the angiogenesis and vascularization of this type of lesion. A correlation between the immunohistochemical data and the radiological and intraoperative evidence of temporal bone marrow invasion and blood source connection was performed to validate this hypothesis. Retrospective study. Immunohistochemical expression of VEGF and CD34 in a group of 16 patients surgically treated for cholesterol granuloma was examined. Middle ear cholesteatomas with normal middle ear mucosa and external auditory canal skin were used as the control groups. The radiological and intraoperative features of cholesterol granulomas were also examined. In endothelial cells, there was an increased expression of angiogenetic growth factor receptors in all the cholesterol granulomas in this study. The quantitative analysis of VEGF showed a mean value of 37.5, whereas the CD34 quantitative analysis gave a mean value of 6.8. Seven patients presented radiological or intraoperative evidence of bone marrow invasion, hematopoietic potentialities, or blood source connections that might support the bleeding theory. In all of these cases there was computed tomography or intraoperative evidence of bone erosion of the middle ear and/or temporal bone structures. The mean values of VEGF and CD34 were 41.1 and 7.7, respectively. High values of VEGF and CD34 are present in patients with cholesterol granulomas. Upregulation of VEGF and CD34 is indicative of a remarkable angiogenesis and a widespread vascular concentration in cholesterol granulomas. 3b. Laryngoscope, 127:E283-E290, 2017. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  18. The Interpretation of Cholesterol Balance Derived Synthesis Data and Surrogate Noncholesterol Plasma Markers for Cholesterol Synthesis under Lipid Lowering Therapies

    Directory of Open Access Journals (Sweden)

    Frans Stellaard

    2017-01-01

    Full Text Available The cholesterol balance procedure allows the calculation of cholesterol synthesis based on the assumption that loss of endogenous cholesterol via fecal excretion and bile acid synthesis is compensated by de novo synthesis. Under ezetimibe therapy hepatic cholesterol is diminished which can be compensated by hepatic de novo synthesis and hepatic extraction of plasma cholesterol. The plasma lathosterol concentration corrected for total cholesterol concentration (R_Lath as a marker of de novo cholesterol synthesis is increased during ezetimibe treatment but unchanged under treatment with ezetimibe and simvastatin. Cholesterol balance derived synthesis data increase during both therapies. We hypothesize the following. (1 The cholesterol balance data must be applied to the hepatobiliary cholesterol pool. (2 The calculated cholesterol synthesis value is the sum of hepatic de novo synthesis and the net plasma—liver cholesterol exchange rate. (3 The reduced rate of biliary cholesterol absorption is the major trigger for the regulation of hepatic cholesterol metabolism under ezetimibe treatment. Supportive experimental and literature data are presented that describe changes of cholesterol fluxes under ezetimibe, statin, and combined treatments in omnivores and vegans, link plasma R_Lath to liver function, and define hepatic de novo synthesis as target for regulation of synthesis. An ezetimibe dependent direct hepatic drug effect cannot be excluded.

  19. Lack of Abcg1 results in decreased plasma HDL cholesterol levels and increased biliary cholesterol secretion in mice fed a high cholesterol diet

    NARCIS (Netherlands)

    Wiersma, Harmen; Nijstad, Niels; de Boer, Jan Freark; Out, Ruud; Hogewerf, Wytse; Van Berkel, Theo J.; Kuipers, Folkert; Tietge, Uwe J. F.

    Objective: The ATP Binding Cassette transporter G1 (ABCG1) has been implicated in cholesterol efflux towards HDL and reverse cholesterol transport (RCT). Biliary cholesterol secretion is considered as an important step in RCT. The aim of the present study was to determine the consequences of Abcg1

  20. Dietary cholesterol from eggs increases the ratio of total cholesterol to high-density lipoprotein cholesterol in humans : a meta-analysis

    NARCIS (Netherlands)

    Weggemans, R.M.; Zock, P.L.; Katan, M.B.

    2001-01-01

    Several epidemiologic studies found no effect of egg consumption on the risk of coronary heart disease. It is possible that the adverse effect of eggs on LDL-cholesterol is offset by their favorable effect on HDL cholesterol. Objective: The objective was to review the effect of dietary cholesterol

  1. The cholesterol system of the swine

    International Nuclear Information System (INIS)

    Aigueperse, Jocelyne

    1979-01-01

    The purpose of this work was to characterize the dynamic system of adult female Large White swine. The content of this system and its relationships with both the external environment and between the different parts of the system were explained. The analysis of these results in terms of compared physiology showed that the structure of the cholesterol system was the same in man and in the swine. Consequently, the swine constitutes a good biological tool to study human cholesterol indirectly and to foresee the changes that might be induced in various physio-pathological cases. (author) [fr

  2. 2013 Cholesterol Guidelines Revisited: Percent LDL Cholesterol Reduction or Attained LDL Cholesterol Level or Both for Prognosis?

    NARCIS (Netherlands)

    Bangalore, Sripal; Fayyad, Rana; Kastelein, John J.; Laskey, Rachel; Amarenco, Pierre; Demicco, David A.; Waters, David D.

    2016-01-01

    The 2013 American College of Cardiology (ACC)/American Heart Association (AHA) guideline on the treatment of blood cholesterol recommends moderate- to high-intensity statins for patients with atherosclerotic cardiovascular disease but departs from the traditional treat-to-target approach. Whether

  3. Aspirin Increases the Solubility of Cholesterol in Lipid Membranes

    Science.gov (United States)

    Alsop, Richard; Barrett, Matthew; Zheng, Sonbo; Dies, Hannah; Rheinstadter, Maikel

    2014-03-01

    Aspirin (ASA) is often prescribed for patients with high levels of cholesterol for the secondary prevention of myocardial events, a regimen known as the Low-Dose Aspirin Therapy. We have recently shown that Aspirin partitions in lipid bilayers. However, a direct interplay between ASA and cholesterol has not been investigated. Cholesterol is known to insert itself into the membrane in a dispersed state at moderate concentrations (under ~37.5%) and decrease fluidity of membranes. We prepared model lipid membranes containing varying amounts of both ASA and cholesterol molecules. The structure of the bilayers as a function of ASA and cholesterol concentration was determined using high-resolution X-ray diffraction. At cholesterol levels of more than 40mol%, immiscible cholesterol plaques formed. Adding ASA to the membranes was found to dissolve the cholesterol plaques, leading to a fluid lipid bilayer structure. We present first direct evidence for an interaction between ASA and cholesterol on the level of the cell membrane.

  4. Survival of adult neurons lacking cholesterol synthesis in vivo.

    Science.gov (United States)

    Fünfschilling, Ursula; Saher, Gesine; Xiao, Le; Möbius, Wiebke; Nave, Klaus-Armin

    2007-01-02

    Cholesterol, an essential component of all mammalian plasma membranes, is highly enriched in the brain. Both during development and in the adult, brain cholesterol is derived from local cholesterol synthesis and not taken up from the circulation. However, the contribution of neurons and glial cells to total brain cholesterol metabolism is unknown. Using conditional gene inactivation in the mouse, we disrupted the squalene synthase gene (fdft1), which is critical for cholesterol synthesis, in cerebellar granule cells and some precerebellar nuclei. Mutant mice showed no histological signs of neuronal degeneration, displayed ultrastructurally normal synapses, and exhibited normal motor coordination. This revealed that these adult neurons do not require cell-autonomous cholesterol synthesis for survival or function. We conclude that at least some adult neurons no longer require endogenous cholesterol synthesis and can fully meet their cholesterol needs by uptake from their surrounding. Glia are a likely source of cholesterol in the central nervous system.

  5. Survival of adult neurons lacking cholesterol synthesis in vivo

    Directory of Open Access Journals (Sweden)

    Möbius Wiebke

    2007-01-01

    Full Text Available Abstract Background Cholesterol, an essential component of all mammalian plasma membranes, is highly enriched in the brain. Both during development and in the adult, brain cholesterol is derived from local cholesterol synthesis and not taken up from the circulation. However, the contribution of neurons and glial cells to total brain cholesterol metabolism is unknown. Results Using conditional gene inactivation in the mouse, we disrupted the squalene synthase gene (fdft1, which is critical for cholesterol synthesis, in cerebellar granule cells and some precerebellar nuclei. Mutant mice showed no histological signs of neuronal degeneration, displayed ultrastructurally normal synapses, and exhibited normal motor coordination. This revealed that these adult neurons do not require cell-autonomous cholesterol synthesis for survival or function. Conclusion We conclude that at least some adult neurons no longer require endogenous cholesterol synthesis and can fully meet their cholesterol needs by uptake from their surrounding. Glia are a likely source of cholesterol in the central nervous system.

  6. Elevated Remnant Cholesterol Causes Both Low-Grade Inflammation and Ischemic Heart Disease, Whereas Elevated Low-Density Lipoprotein Cholesterol Causes Ischemic Heart Disease Without Inflammation

    DEFF Research Database (Denmark)

    Varbo, Anette; Benn, Marianne; Tybjærg-Hansen, Anne

    2013-01-01

    Elevated nonfasting remnant cholesterol and low-density lipoprotein (LDL) cholesterol are causally associated with ischemic heart disease (IHD), but whether elevated nonfasting remnant cholesterol and LDL cholesterol both cause low-grade inflammation is currently unknown....

  7. Effect of Processing Methods on Cholesterol Contents and Cholesterol Oxides Formation in Some Dairy Products

    International Nuclear Information System (INIS)

    AlRowaily, Meshref A

    2008-01-01

    The effects of pasteurization, boiling, microwaving, processing and storage of milk and some locally produced dairy products on cholesterol contents and cholesterol oxides formation were studied and evaluated. The 7-ketocholesterol were not detected (ND) in all raw milk samples. On the contrary, heating of milk led to formation of cholesterol oxidation products (COPs), mostly, 7- ketocholesterol in different quantities. No significant effect of heating of milk on cholesterol level was observed with the exception of the ultra-high temperature (UHT) milk prepared from milk powder heated at 140 + - 1.0 degree C for 4 sec showed the highest value of 7-ketocholesterol (80.97 mgg-1), followed by microwave heated milk for 5 min (31.29 mgg-1), whereas the lowest value was in milk pasteurized at 85 + - 1.0 degree C for 16 sec (3.125 mgg-1). Commercial storage showed no significant effect on cholesterol and 7-ketocholestrol but lowered cholesterol concentration and increased 7-ketocholestrol level of UHT reconstituted milk. Cholesterol content of both yogurt and labaneh strained by centrifugal separator showed significant decrease while 7-ketochostrol level was increased significantly with refrigerated storage. The findings are discussed in the context with the results of previous similar studies. (author)

  8. Development and Evaluation of Die Materials for Use in the Growth of Silicon Ribbons by the Inverted Ribbon Growth Process. Task 2: LSSA Project

    Science.gov (United States)

    Duffy, M. T.; Berkman, S.; Moss, H. I.; Cullen, G. W.

    1978-01-01

    Several ribbon growth experiments were performed from V-shaped dies coated with CVD Si3N4. The most significant result was the ability to perform five consecutive growth runs from the same die without mechanical degradation of the die through temperature cycling. The die was made from vitreous carbon coated with CVD Si3N4. Silicon oxynitride, Si2N2O, was examined with respect to thermal stability in contact with molten silicon. The results of X-ray analysis indicate that this material is converted to both alpha - and beta-Si3N4 in the presence of molten silicon. Experiments on the stability of CVD SiOxNy shoe that this material can be maintained in contact with molten silicon (sessile drop test) for greater than 30 h at 1450 C without total decompositon. These layers are converted mainly to beta-Si3N4.

  9. Design study of a normal conducting helical snake for AGS

    CERN Document Server

    Takano, Junpei; Okamura, Masahiro; Roser, Thomas; MacKay, William W; Luccio, Alfredo U; Takano, Koji

    2004-01-01

    A new normal conducting snake magnet is being fabricated for the Alternate Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). In the Relativistic Heavy Ion Collider (RHIC) project, a superconducting type helical dipole magnets had been developed and it performed successfully in high-energy polarized proton acceleration. The new AGS helical snake has the same basic magnetic structure but is more complicated. To achieve no beam shift and no beam deflection in one magnetic device, helical pitches and rotating angles were carefully calculated. Compared to a superconducting magnet, a normal warm magnet must have a large cross- sectional area of conductors which make it difficult to design a magnet with large helical pitch. We developed a modified window frame structure to accommodate the large number of conductors. Its three dimensional magnetic field was simulated by using OPERA3D/TOSCA. 3 Refs.

  10. A 3D printed helical antenna with integrated lens

    KAUST Repository

    Farooqui, Muhammad Fahad; Shamim, Atif

    2015-01-01

    A novel antenna configuration comprising a helical antenna with an integrated lens is demonstrated in this work. The antenna is manufactured by a unique combination of 3D printing of plastic material (ABS) and inkjet printing of silver nano

  11. Particle orbit analysis for LHD helical axis configurations

    International Nuclear Information System (INIS)

    Guasp, J.; Yamazaki, K.; Motojima, O.

    1993-04-01

    Fast ion orbits for helical magnetic axis configurations in LHD (Large Helical Device) are analyzed and compared with the standard circular axis case. Boundaries between passing and helically trapped particle regions show clear differences: in the non-planar axis case the helically trapped region spreads, near the magnetic axis, over a much wider band across the 90deg pitch angle value and shows a very marked asymmetry. The locally trapped particle region is also wider than in the standard case. The differences in the loss cone boundaries of the two cases are rather small, however, the effects of re-entering criteria are very important in both cases. On the contrary, effects of finite coil size are not significant. (author)

  12. Metallic and 3D-printed dielectric helical terahertz waveguides.

    Science.gov (United States)

    Vogt, Dominik Walter; Anthony, Jessienta; Leonhardt, Rainer

    2015-12-28

    We investigate guidance of Terahertz (THz) radiation in metallic and 3D-printed dielectric helical waveguides in the frequency range from 0.2 to 1 THz. Our experimental results obtained from THz time-domain spectroscopy (THz-TDS) measurements are in very good agreement with finite-difference time-domain (FDTD) simulations. We observe single-mode, low loss and low dispersive propagation of THz radiation in metallic helical waveguides over a broad bandwidth. The 3D-printed dielectric helical waveguides have substantially extended the bandwidth of a low loss dielectric tube waveguide as observed from the experimental and simulation results. The high flexibility of the helical design allows an easy incorporation into bench top THz devices.

  13. Helical-axis stellarators with noninterlocking planar coils

    International Nuclear Information System (INIS)

    Reiman, A.; Boozer, A.

    1983-08-01

    The properties of helical axis stellarator fields generated by unlinked, planar coils are described. It is shown that such fields can have a magnetic well and large rotational transform, implying large equilibrium and stability beta limits

  14. Helical-axis stellarators with noninterlocking planar coils

    Energy Technology Data Exchange (ETDEWEB)

    Reiman, A.; Boozer, A.

    1983-08-01

    The properties of helical axis stellarator fields generated by unlinked, planar coils are described. It is shown that such fields can have a magnetic well and large rotational transform, implying large equilibrium and stability beta limits.

  15. Energy and helicity of magnetic torus knots and braids

    Science.gov (United States)

    Oberti, Chiara; Ricca, Renzo L.

    2018-02-01

    By considering steady magnetic fields in the shape of torus knots and unknots in ideal magnetohydrodynamics, we compute some fundamental geometric and physical properties to provide estimates for magnetic energy and helicity. By making use of an appropriate parametrization, we show that knots with dominant toroidal coils that are a good model for solar coronal loops have negligible total torsion contribution to magnetic helicity while writhing number provides a good proxy. Hence, by the algebraic definition of writhe based on crossing numbers, we show that the estimated values of writhe based on image analysis provide reliable information for the exact values of helicity. We also show that magnetic energy is linearly related to helicity, and the effect of the confinement of magnetic field can be expressed in terms of geometric information. These results can find useful application in solar and plasma physics, where braided structures are often present.

  16. Investigation into the heat transfer performance of helically ribbed surfaces

    International Nuclear Information System (INIS)

    Firth, R.J.

    1981-12-01

    The first part of an investigation into flow and heat transfer in annular channels and seven pin clusters is described. One of the main aims of the project is to improve cluster heat transfer prediction codes for helically ribbed surfaces. A study is made of the heat transfer and flow characteristics of a helically ribbed pin in an annular channel. It is shown that the swirling flow, which is induced by the helical ribs, gives rise to substantially enhanced diffusivity levels. This phenomenon had not been taken into account by previous analysis techniques. The methods for analysing heat transfer and pressure drop data from annular channels which were originally developed for non-swirling flow are generalised to accommodate swirling flow. The new methods are shown to be consistent with empirical data. Roughness parameter data is presented for helically ribbed surfaces with an axial rib pitch into height ratio of about 7. (author)

  17. Interaction of 18-residue peptides derived from amphipathic helical ...

    Indian Academy of Sciences (India)

    Madhsudhan

    interaction of proteins and peptides with membranes (Segrest ... favour surface activity have been described by Eisenberg et ... amphipathicity and propensity for α-helical conformation ..... Membrane destabilisation occurs due to electrostatic.

  18. Energy fluxes in helical magnetohydrodynamics and dynamo action

    Indian Academy of Sciences (India)

    Kinetic and magnetic helicities do not affect the renormalized parameters, ... Generation of magnetic field in plasma, usually referred to as 'dynamo', is one of the ..... energy fluxes for the inertial-range wave numbers where the same power.

  19. High Cholesterol/Low Cholesterol: Effects in Biological Membranes: A Review.

    Science.gov (United States)

    Subczynski, Witold K; Pasenkiewicz-Gierula, Marta; Widomska, Justyna; Mainali, Laxman; Raguz, Marija

    2017-12-01

    Lipid composition determines membrane properties, and cholesterol plays a major role in this determination as it regulates membrane fluidity and permeability, as well as induces the formation of coexisting phases and domains in the membrane. Biological membranes display a very diverse lipid composition, the lateral organization of which plays a crucial role in regulating a variety of membrane functions. We hypothesize that, during biological evolution, membranes with a particular cholesterol content were selected to perform certain functions in the cells of eukaryotic organisms. In this review, we discuss the major membrane properties induced by cholesterol, and their relationship to certain membrane functions.

  20. Cholesterol metabolism in blood cells of irradiated rats

    International Nuclear Information System (INIS)

    Novoselova, E.G.; Kulagina, T.P.; Potekhina, N.I.

    1985-01-01

    Cholesterol metabolism in blood erythrocytes and lymphocytes of irradiated rats has been investigated. It has been found that at all terms and doses of irradiation, a suppression of the synthesis of erythrocyte cholesterol is observed. The increase of cholesterol quantiy in erythrocytes upon total gamma irradiation in the 10 Gr dose possibly is the result of growth of cholesterol transfer from plasma into erythrocyte cells. The study of the cholesterol synthesis in suspension of lymphocytes elminated from peripheral blood of control and irradiated rats has shown that at irradiation doses of 4 and 10 Gr in an hour acivation of cholesterol synthesis in vitro takes places

  1. Acute pulmonary embolism in helical computed tomography

    International Nuclear Information System (INIS)

    Paslawski, M.

    2005-01-01

    Pulmonary embolism is a common condition in which diagnostic and therapeutic delays contribute to substantial morbidity and mortality. Clinical diagnosis is difficult because the signs and symptoms re unspecific, and a differential diagnosis is extensive, including pneumonia or bronchitis, asthma, myocardial infraction, pulmonary edema, anxiety, dissection of the aorta, pericardial tamponade, lung cancer, primary pulmonary hypertension, rib fracture, and pneumothorax. The purpose of the study was to present the use of CT in diagnosing acute pulmonary embolism. A group of 23 patients with clinically suspected pulmonary embolism underwent CT examination with a helical CT scanner (Somatom Emotion, Siemens) before and after administration of 150 ml of Ultravist. Pulmonary embolism was found in the CT examinations of 13 patients. In two of these it was a central filling defect. Amputation of the artery was found in one. Parietal filling defect in three patients formed an acute angle with the vessel walls. Saddle emboli appearing as filling defects in the contrast column that hung over vessel bifurcations was found in two patients. In five patients,emboli were found in small segmental arteries. CT provides information not only on the pulmonary arteries, but also on the lung parenchyma, hila, mediastinum, and the heart. Alternative findings may be identified by CT chest examination, stablishing alternative diagnoses, including pulmonary disorders (such as pneumonia or fibrosis), pleural abnormalities, and cardiovascular disease (such as aortic dissection or pericardial tamponade). Another advantage of the CT is its widespread availability.(author)

  2. Polymer dynamics driven by a helical filament

    Science.gov (United States)

    Balin, Andrew; Shendruk, Tyler; Zoettl, Andreas; Yeomans, Julia

    Microbial flagellates typically inhabit complex suspensions of extracellular polymeric material which can impact the swimming speed of motile microbes, filter-feeding of sessile cells, and the generation of biofilms. There is currently a need to better understand how the fundamental dynamics of polymers near active cells or flagella impacts these various phenomena. We study the hydrodynamic and steric influence of a rotating helical filament on suspended polymers using Stokesian Dynamics simulations. Our results show that as a stationary rotating helix pumps fluid along its long axis, nearby polymers migrate radially inwards and are elongated in the process. We observe that the actuation of the helix tends to increase the probability of finding polymeric material within its pervaded volume. At larger Weissenberg numbers, this accumulation of polymers within the vicinity of the helix is greater. Further, we have analysed the stochastic work performed by the helix on the polymers and we show that this quantity is positive on average and increases with polymer contour length. Our results provide a basis for understanding the microscopic interactions that govern cell dynamics in complex media. This work was supported through funding from the ERC Advanced Grant 291234 MiCE and we acknowledge EMBO funding to TNS (ALTF181-2013).

  3. Electronic Band Structure of Helical Polyisocyanides.

    Science.gov (United States)

    Champagne, Benoît; Liégeois, Vincent; Fripiat, Joseph G; Harris, Frank E

    2017-10-19

    Restricted Hartree-Fock computations are reported for a methyl isocyanide polymer (repeating unit -C═N-CH 3 ), whose most stable conformation is expected to be a helical chain. The computations used a standard contracted Gaussian orbital set at the computational levels STO-3G, 3-21G, 6-31G, and 6-31G**, and studies were made for two line-group configurations motivated by earlier work and by studies of space-filling molecular models: (1) A structure of line-group symmetry L9 5 , containing a 9-fold screw axis with atoms displaced in the axial direction by 5/9 times the lattice constant, and (2) a structure of symmetry L4 1 that had been proposed, containing a 4-fold screw axis with translation by 1/4 of the lattice constant. Full use of the line-group symmetry was employed to cause most of the computational complexity to depend only on the size of the asymmetric repeating unit. Data reported include computed bond properties, atomic charge distribution, longitudinal polarizability, band structure, and the convoluted density of states. Most features of the description were found to be insensitive to the level of computational approximation. The work also illustrates the importance of exploiting line-group symmetry to extend the range of polymer structural problems that can be treated computationally.

  4. Pulmonary artery aneurysm in Bechcet's disease: helical computed tomography study

    International Nuclear Information System (INIS)

    Munoz, J.; Caballero, P.; Olivera, M. J.; Cajal, M. L.; Caniego, J. L.

    2000-01-01

    Behcet's disease is a vasculitis of unknown etiology that affects arteries and veins of different sizes and can be associated with pulmonary artery aneurysms. We report the case of a patient with Behcet's disease and a pulmonary artery aneurysm who was studied by means of plain chest X ray, helical computed tomography and pulmonary arteriography. Helical computed tomography is a reliable technique for the diagnosis and follow-up of these patients. (Author) 9 refs

  5. ADDITIVE SELF-HELICITY AS A KINK MODE THRESHOLD

    International Nuclear Information System (INIS)

    Malanushenko, A.; Longcope, D. W.; Fan, Y.; Gibson, S. E.

    2009-01-01

    In this paper, we propose that additive self-helicity, introduced by Longcope and Malanushenko, plays a role in the kink instability for complex equilibria, similar to twist helicity for thin flux tubes. We support this hypothesis by a calculation of additive self-helicity of a twisted flux tube from the simulation of Fan and Gibson. As more twist gets introduced, the additive self-helicity increases, and the kink instability of the tube coincides with the drop of additive self-helicity, after the latter reaches the value of H A /Φ 2 ∼ 1.5 (where Φ is the flux of the tube and H A is the additive self-helicity). We compare the additive self-helicity to twist for a thin subportion of the tube to illustrate that H A /Φ 2 is equal to the twist number, studied by Berger and Field, when the thin flux tube approximation is applicable. We suggest that the quantity H A /Φ 2 could be treated as a generalization of a twist number, when the thin flux tube approximation is not applicable. A threshold on a generalized twist number might prove extremely useful studying complex equilibria, just as the twist number itself has proven useful studying idealized thin flux tubes. We explicitly describe a numerical method for calculating additive self-helicity, which includes an algorithm for identifying a domain occupied by a flux bundle and a method of calculating potential magnetic field confined to this domain. We also describe a numerical method to calculate twist of a thin flux tube, using a frame parallelly transported along the axis of the tube.

  6. Design windows and cost analysis on helical reactors

    International Nuclear Information System (INIS)

    Kozaki, Y.; Imagawa, S.; Sagara, A.

    2007-01-01

    The LHD type helical reactors are characterized by a large major radius but slender helical coil, which give us different approaches for power plants from tokamak reactors. For searching design windows of helical reactors and discussing their potential as power plants, we have developed a mass-cost estimating model linked with system design code (HeliCos), thorough studying the relationships between major plasma parameters and reactor parameters, and weight of major components. In regard to cost data we have much experience through preparing ITER construction. To compare the weight and cost of magnet systems between tokamak and helical reactors, we broke down magnet systems and cost factors, such as weights of super conducting strands, conduits, support structures, and winding unit costs, through estimating ITER cost data basis. Based on FFHR2m1 deign we considered a typical 3 GWth helical plant (LHD type) with the same magnet size, coil major radius Rc 14 m, magnetic energy 120 GJ, but increasing plasma densities. We evaluated the weight and cost of magnet systems of 3 GWth helical plant, the total magnet weights of 16,000ton and costs of 210 BYen, which are similar values of tokamak reactors (10,200 ton, 110 BYen in ITER 2002 report, and 21,900 ton, 275 BYen in ITER FDR1999). The costs of strands and winding occupy 70% of total magnet costs, and influence entire power plants economics. The design windows analysis and comparative economics studies to optimize the main reactor parameters have been carried out. Economics studies show that it is misunderstanding to consider helical coils are too large and too expensive to achieve power plants. But we should notice that the helical reactor design windows and economics are very sensitive to allowable blanket space (depend on ergodic layer conditions) and diverter configuration for decreasing heat loads. (orig.)

  7. Tokamak startup using point-source dc helicity injection.

    Science.gov (United States)

    Battaglia, D J; Bongard, M W; Fonck, R J; Redd, A J; Sontag, A C

    2009-06-05

    Startup of a 0.1 MA tokamak plasma is demonstrated on the ultralow aspect ratio Pegasus Toroidal Experiment using three localized, high-current density sources mounted near the outboard midplane. The injected open field current relaxes via helicity-conserving magnetic turbulence into a tokamaklike magnetic topology where the maximum sustained plasma current is determined by helicity balance and the requirements for magnetic relaxation.

  8. Comparison between helical computed tomography angiography and intraoperative findings

    Directory of Open Access Journals (Sweden)

    Abijit Shetty

    2014-01-01

    Conclusions: Helical CT is important in delineating the arterial, venous, and ureteral anatomy and can show the important incidental findings. Left renal donors and males have more variations in their renal anatomy. Technically challenging laparoscopic nephrectomy on the multiple-vessel-side donor is possible with the aid of helical CT. The importance of the CT in evaluating donor renal anatomy for a technically challenging laparoscopic donor nephrectomy is commendable.

  9. Scale Dependence of Magnetic Helicity in the Solar Wind

    Science.gov (United States)

    Brandenburg, Axel; Subramanian, Kandaswamy; Balogh, Andre; Goldstein, Melvyn L.

    2011-01-01

    We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is homogeneous. Because the solar wind speed is high, we follow the approach first pioneered by Matthaeus et al. by which, under the assumption of spatial homogeneity, one can use Fourier transforms of the magnetic field time series to construct one-dimensional spectra of the magnetic energy and magnetic helicity under the assumption that the Taylor frozen-in-flow hypothesis is valid. That is a well-satisfied assumption for the data used in this study. The magnetic helicity derives from the skew-symmetric terms of the three-dimensional magnetic correlation tensor, while the symmetric terms of the tensor are used to determine the magnetic energy spectrum. Our results show a sign change of magnetic helicity at wavenumber k approximately equal to 2AU(sup -1) (or frequency nu approximately equal to 2 microHz) at distances below 2.8AU and at k approximately equal to 30AU(sup -1) (or nu approximately equal to 25 microHz) at larger distances. At small scales the magnetic helicity is positive at northern heliographic latitudes and negative at southern latitudes. The positive magnetic helicity at small scales is argued to be the result of turbulent diffusion reversing the sign relative to what is seen at small scales at the solar surface. Furthermore, the magnetic helicity declines toward solar minimum in 1996. The magnetic helicity flux integrated separately over one hemisphere amounts to about 10(sup 45) Mx(sup 2) cycle(sup -1) at large scales and to a three times lower value at smaller scales.

  10. Concept and development of measurement method of time sensitivity profile (TSP) in X-ray CT. Comparison of non-helical, single-slice helical, and multi-slice helical scans

    International Nuclear Information System (INIS)

    Tsujioka, Katsumi; Ida, Yoshihiro; Ohtsubo, Hironori; Takahashi, Yasukata; Niwa, Masayoshi

    2000-01-01

    We focused on the time element contained in a single CT image, and devised the concept of a time-sensitivity profile (TSP) describing how the time element is translated into an image. We calculated the data collection time range when the helical pitch is changed in non helical scans, single slice helical scans, and multi slice helical scans. We then calculated the time sensitivity profile (TSP) from the weighting applied when the data collection time range is translated into an image. TSP was also measured for each scanning method using our self-made moving phantom. TSPs obtained from the calculation and the experiments were very close. TSP showed interesting characteristics with each scanning method, especially in the case of multi slice helical scanning, in which TSP became shorter as helical pitch increased. We referred to the TSP's FWHM as the effective scanning time. When we conducted multi slice helical scanning at helical pitch 3, the effective scanning time increased to about 24% longer than that of a non helical scan. When we conducted multi slice helical scanning at helical pitch 5 or 6, the effective scanning time was about half that of a non helical scan. The time sensitivity profile (TSP) is a totally new concept that we consider an important element in discussing the time resolution of a CT scanner. The results of this review will provide significant data in determining the scanning parameters when scanning a moving object. (author)

  11. Histone deacetylase inhibition decreases cholesterol levels in neuronal cells by modulating key genes in cholesterol synthesis, uptake and efflux.

    Directory of Open Access Journals (Sweden)

    Maria João Nunes

    Full Text Available Cholesterol is an essential component of the central nervous system and increasing evidence suggests an association between brain cholesterol metabolism dysfunction and the onset of neurodegenerative disorders. Interestingly, histone deacetylase inhibitors (HDACi such as trichostatin A (TSA are emerging as promising therapeutic approaches in neurodegenerative diseases, but their effect on brain cholesterol metabolism is poorly understood. We have previously demonstrated that HDACi up-regulate CYP46A1 gene transcription, a key enzyme in neuronal cholesterol homeostasis. In this study, TSA was shown to modulate the transcription of other genes involved in cholesterol metabolism in human neuroblastoma cells, namely by up-regulating genes that control cholesterol efflux and down-regulating genes involved in cholesterol synthesis and uptake, thus leading to an overall decrease in total cholesterol content. Furthermore, co-treatment with the amphipathic drug U18666A that can mimic the intracellular cholesterol accumulation observed in cells of Niemman-Pick type C patients, revealed that TSA can ameliorate the phenotype induced by pathological cholesterol accumulation, by restoring the expression of key genes involved in cholesterol synthesis, uptake and efflux and promoting lysosomal cholesterol redistribution. These results clarify the role of TSA in the modulation of neuronal cholesterol metabolism at the transcriptional level, and emphasize the idea of HDAC inhibition as a promising therapeutic tool in neurodegenerative disorders with impaired cholesterol metabolism.

  12. Combined effects of vertical and lateral confinement on the magnetic properties of MnAs micro and nano-ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Steren, L. B.; Tortarolo, M. [Centro Atómico Constituyentes CNEA, 1650 San Martín (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas, C1033AAJ Buenos Aires (Argentina); Fernandez Baldis, F.; Sirena, M. [Consejo Nacional de Investigaciones Científicas y Técnicas, C1033AAJ Buenos Aires (Argentina); Centro Atómico Bariloche and Instituto Balseiro, CNEA, 8400 S. C. de Bariloche (Argentina); Sacchi, M.; Eddrief, M. [Sorbonne Universités, UPMC Univ. Paris 06, UMR 7588, INSP, 4 place Jussieu, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, 4 place Jussieu, F-75005 Paris (France); Etgens, V. H. [Fédération Lavoisier Franklin, UVSQ, 78035 Versailles Cedex (France); Santos, B.; Mentes, T. O.; Locatelli, A. [Elettra-Sincrotrone Trieste S.C.p.A., 34149 Basovizza, Trieste (Italy)

    2016-09-07

    The micromagnetic domain structure of MnAs films gave place to an intense research activity in the last few years due to its potential application in magneto-electronic devices such as domain-wall track memories and logic circuits. These applications require a full knowledge of miniaturization effects on the magnetic properties of the material. In this work, X-ray photoemission electron microscopy has been used for imaging magnetic domains in lithographically fabricated MnAs ribbons, addressing the dependence of the domain configuration on film thickness and ribbon width. Our experiments show a transition from head-on to regular stripe domains below a critical width/thickness ratio w{sub c} ≈ 6. Micromagnetic simulations suggest that this transition is correlated to the magnetic structure of the surface plane. Depending on the ribbon width and thickness, the magnetic configuration is shown to evolve from flux-closure domain structure to a state of almost homogeneous magnetization, observed for narrower ribbons. The evolution of the domain structure, magnetic fraction, and magnetization with temperature has been studied across the ferromagnetic/paramagnetic transition. Our experiments show that the magnetic configuration in ribbons exhibits higher stability to temperature variations than in as-cast films.

  13. Large magnetic entropy change in melt-spun LaFe11.5Si1.5 ribbons

    International Nuclear Information System (INIS)

    Xie Kun; Song Xiaoping; Zhu Yaoming; Lv Weipeng; Sun Zhanbo

    2004-01-01

    The microstructure transformation and the magnetic entropy change of LaFe 11.5 Si 1.5 melt-spun ribbons were investigated. The melt-spun ribbons show a homogeneous distribution of elements, and the homogeneity develops further after 5 h annealing. XRD results show that the ribbons are composed of NaZn 13 -type LaFe 11.5 Si 1.5 compounds and an α-Fe phase. After annealing, the ribbons crystallize well in the NaZn 13 -type structure and exhibit a very large magnetic entropy change. A first-order magnetic transition is observed in the annealed ribbons, and this is believed to be the origin of the large magnetic entropy. These results suggest that NaZn 13 -type LaFe 11.5 Si 1.5 compounds with a large magnetic entropy change can be produced by melt-spinning, the annealing time can be shortened significantly and the production cost of the magnetic refrigerant will be cut down accordingly

  14. Combined effects of vertical and lateral confinement on the magnetic properties of MnAs micro and nano-ribbons

    International Nuclear Information System (INIS)

    Steren, L. B.; Tortarolo, M.; Fernandez Baldis, F.; Sirena, M.; Sacchi, M.; Eddrief, M.; Etgens, V. H.; Santos, B.; Mentes, T. O.; Locatelli, A.

    2016-01-01

    The micromagnetic domain structure of MnAs films gave place to an intense research activity in the last few years due to its potential application in magneto-electronic devices such as domain-wall track memories and logic circuits. These applications require a full knowledge of miniaturization effects on the magnetic properties of the material. In this work, X-ray photoemission electron microscopy has been used for imaging magnetic domains in lithographically fabricated MnAs ribbons, addressing the dependence of the domain configuration on film thickness and ribbon width. Our experiments show a transition from head-on to regular stripe domains below a critical width/thickness ratio w_c ≈ 6. Micromagnetic simulations suggest that this transition is correlated to the magnetic structure of the surface plane. Depending on the ribbon width and thickness, the magnetic configuration is shown to evolve from flux-closure domain structure to a state of almost homogeneous magnetization, observed for narrower ribbons. The evolution of the domain structure, magnetic fraction, and magnetization with temperature has been studied across the ferromagnetic/paramagnetic transition. Our experiments show that the magnetic configuration in ribbons exhibits higher stability to temperature variations than in as-cast films.

  15. Blood cholesterol : a public health perspective

    NARCIS (Netherlands)

    Verschuren, W.M.M.

    1995-01-01

    Changes in total cholesterol levels (TC) were studied using data from three epidemiological studies: about 30,000 men and women aged 37-43 were examined between 1974 and 1980 (CB Project), about 80,000 men aged 33-37 between 1981 and 1986 (RIFOH Project) and 42,000 men and women aged 20-59 from 1987

  16. The Success Story of LDL Cholesterol Lowering.

    Science.gov (United States)

    Pedersen, Terje R

    2016-02-19

    We can look back at >100 years of cholesterol research that has brought medicine to a stage where people at risk of severe or fatal coronary heart disease have a much better prognosis than before. This progress has not come about without resistance. Perhaps one of the most debated topics in medicine, the cholesterol controversy, could only be brought to rest through the development of new clinical research methods that were capable of taking advantage of the amazing achievements in basic and pharmacological science after the second World War. It was only after understanding the biochemistry and physiology of cholesterol synthesis, transport and clearance from the blood that medicine could take advantage of drugs and diets to reduce the risk of atherosclerotic diseases. This review points to the highlights of the history of low-density lipoprotein-cholesterol lowering, with the discovery of the low-density lipoprotein receptor and its physiology and not only the development of statins as the stellar moments but also the development of clinical trial methodology as an effective tool to provide scientifically convincing evidence. © 2016 American Heart Association, Inc.

  17. Cholesterol oxidation products and their biological importance

    Czech Academy of Sciences Publication Activity Database

    Kulig, W.; Cwiklik, Lukasz; Jurkiewicz, P.; Rog, T.; Vattulainen, I.

    2016-01-01

    Roč. 199, Sep (2016), s. 144-160 ISSN 0009-3084 R&D Projects: GA ČR(CZ) GBP208/12/G016 Institutional support: RVO:61388963 Keywords : cholesterol * oxidation * oxysterols * biological membranes * biophysical properties Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.361, year: 2016

  18. Resveratrol protects rabbits against cholesterol diet- induced ...

    African Journals Online (AJOL)

    ... groups compared to HFD group only. In conclusion, the findings indicated that Resveratrol may contain polar products able to lower plasma lipid concentrations and might be beneficial in treatment of hyperlipidemia and atherosclerosis. Keywords: Cholesterol diet, Lipidaemia, Rabbit; Resveratrol, LDL-c, HDL-c, TC, TG ...

  19. Biochemical characterization of cholesterol-reducing Eubacterium.

    Science.gov (United States)

    Mott, G E; Brinkley, A W; Mersinger, C L

    1980-12-01

    We characterized two isolates of cholesterol-reducing Eubacterium by conducting conventional biochemical tests and by testing various sterols and glycerolipids as potential growth factors. In media containing cholesterol and plasmenylethanolamine, the tests for nitrate reduction, indole production, and gelatin and starch hydrolyses were negative, and no acid was produced from any of 22 carbohydrates. Both isolates hydrolyzed esculin to esculetin, indicating beta-glycosidase activity. In addition to plasmenylethanolamine, five other lipids which contain an alkenyl ether residue supported growth of Eubacterium strain 403 in a lecithin-cholesterol base medium. Of six steroids tested, cholesterol, cholest-4-en-3-one, cholest-4-en-3 beta-ol (allocholesterol), and androst-5-en-3 beta-ol-17-one supported growth of Eubacterium strain 403. All four steroids were reduced to the 3 beta-ol, 5 beta-H products. The delta 5 steroids cholest-5-en-3 alpha-ol (epicholesterol) and 22,23-bisnor-5-cholenic acid-3-beta-ol were not reduced and did not support growth of the Eubacterium strain.

  20. Stroke secondary to multiple spontaneous cholesterol emboli.

    Science.gov (United States)

    Pascual, M; Baumgartner, J M; Bounameaux, H

    1991-01-01

    We describe one male, 49-year-old diabetic patient in whom regressive stroke with aphasia and right-sided hemiparesia was related to multiple small emboli in the left paraventricular cortex. Simultaneous presence of several cholesterol emboli in the left eye ground and detection of an atheromatous plaque at the homolateral carotid bifurcation let assume that the cerebral emboli originated from that plaque and also consisted of cholesterol crystals. The patient was discharged on low-dose aspirin (100 mg/day) after neurologic improvement. Follow-up at one year revealed clinical stability, recurrence of the cholesterol emboli at the eye ground examination and no change of the carotid plaque. Cholesterol embolization with renal failure, hypertension and peripheral arterial occlusions causing skin ulcerations is classical in case of atheromatous aortic disease but stroke has rarely been reported in this syndrome. However, more frequent use of invasive procedures (arteriography, transluminal angioplasty, vascular surgery) or thrombolytic treatment might increase its incidence in the near future.