WorldWideScience

Sample records for nuclear spirals feeding

  1. Nuclear spirals in galaxies

    OpenAIRE

    Maciejewski, Witold

    2006-01-01

    Recent high-resolution observations indicate that nuclear spirals are often present in the innermost few hundred parsecs of disc galaxies. My models show that nuclear spirals form naturally as a gas response to non-axisymmetry in the gravitational potential. Some nuclear spirals take the form of spiral shocks, resulting in streaming motions in the gas, and in inflow comparable to the accretion rates needed to power local Active Galactic Nuclei. Recently streaming motions of amplitude expected...

  2. Nuclear spirals as feeding channels to the Supermassive Black Hole: the case of the galaxy NGC 6951

    CERN Document Server

    Storchi-Bergmann, Thaisa; Riffel, Rogemar A; Fathi, Kambiz; Axon, David J; Robinson, Andrew; Marconi, Alessandro; Ostlin, Goran

    2007-01-01

    We report the discovery of gas streaming motions along nuclear spiral arms towards the LINER nucleus of the galaxy NGC 6951. The observations, obtained using the GMOS integral field spectrograph on the Gemini North telescope, yielded maps of the flux distributions and gas kinematics in the Halpha, [NII]6584 and [SII]6717,31 emission lines of the inner 7x5 arcsec^2 of the galaxy. This region includes a circumnuclear star-forming ring with radius 500pc, a nuclear spiral inside the ring and the LINER nucleus. The kinematics of the ionized gas is dominated by rotation, but subtraction of a kinematic model of a rotating exponential disk reveals deviations from circular rotation within the nuclear ring which can be attributed to (1) streaming motions along the nuclear spiral arms and (2) a bipolar outflow which seems to be associated to a nuclear jet. On the basis of the observed streaming velocities and geometry of the spiral arms we estimate a mass inflow rate of ionized gas of 3x10^(-4) Msun/yr, which is of the ...

  3. A new planar feed for slot spiral antennas

    Science.gov (United States)

    Nurnberger, M. W.; Volakis, J. L.

    1995-01-01

    This report presents a new planar, wideband feed network for a slot spiral antenna, and the subsequent design and performance of a VHF antenna utilizing this feed design. Both input impedance and radiation pattern measurements are presented to demonstrate the performance and usefulness of this feed. Almost all previous designs have utilized wire spirals, requiring bulky, non-planar feeds with separate baluns, and large absorbing cavities. The presented slot spiral antenna feed integrates the balun into the structure of the slot spiral antenna, making the antenna and feed planar. This greatly simplifies the design and construction of the antenna, in addition to providing repeatable accuracy. It also allows the use of a very shallow reflecting cavity for conformal applications. Finally, this feeding approach now makes many of the known miniaturization techniques viable options.

  4. Nuclear spirals in the inner Milky Way

    Science.gov (United States)

    Ridley, Matthew G. L.; Sormani, Mattia C.; Treß, Robin G.; Magorrian, John; Klessen, Ralf S.

    2017-08-01

    We use hydrodynamical simulations to construct a new coherent picture for the gas flow in the Central Molecular Zone (CMZ), the region of our Galaxy within R ≲ 500 pc. We relate connected structures observed in (l, b, v) data cubes of molecular tracers to nuclear spiral arms. These arise naturally in hydrodynamical simulations of barred galaxies, and are similar to those that can be seen in external galaxies such as NGC 4303 or NGC 1097. We discuss a face-on view of the CMZ, including the positions of several prominent molecular clouds, such as Sgr B2, the 20 and 50 km s-1 clouds, the polar arc, Bania Clump 2 and Sgr C. Our model is also consistent with the larger scale gas flow, up to R ≃ 3 kpc, thus providing a consistent picture of the entire Galactic bar region.

  5. Subcontinental Nuclear Instability: The Spiralling Nightmare

    Directory of Open Access Journals (Sweden)

    Vijay Shankar

    2015-07-01

    Full Text Available The scheme that carved world order during the Cold War was a pitched battle for 'containment' against burgeoning communism. In turn, rationality gave way to the threat of catastrophic nuclear force as the basis of stability. If at all there is a historical lesson to be learned from that experience then it is that stability begins with serious and sustained dialogue between leadership; the alternative being what Kennedy termed "the peace of the grave." An appraisal of the contemporary global state of nuclear affairs will suggest that the three pillars of nuclear stability, namely, non-proliferation, control of fissile material production, and transparency of nuclear arsenals are wobbly for lack of foundational support. In the truancy of global foundational support the answer may well lie in reconstituting a framework for détente. In the Subcontinental context there looms a very real nuclear nightmare. It takes the form of a hair-trigger, opaque nuclear arsenal that has embraced tactical use under decentralized military control, is steered by an ambiguous doctrine, and guided by a military strategy that carouses with non-state actors. The effect of an weakened civilian leadership in Pakistan that is incapable of action to remove the military finger from the nuclear trigger can do little to dispel the nightmare. A singular feature of the deterrent relationship in the region is its tri-polar character. As is well known today, it is the collusive nature of the Sino-Pak nuclear relationship which created and sustains the Pakistan nuclear weapons program. This in stark contrast to the Indian nuclear doctrine that went public in 2003. The unleashing of Islamic radicals in the wake of US withdrawal from the Af-Pak region and their mounting internalization in the Pakistan military and political establishments brings into question the state and motivation of the nuclear command and control structures there. Stability in this context would suggest the

  6. Effects of Spiral Arms on Star Formation in Nuclear Rings of Barred-spiral Galaxies

    CERN Document Server

    Seo, Woo-Young

    2014-01-01

    We use hydrodynamic simulations to study the effect of spiral arms on the star formation rate (SFR) occurring in nuclear rings of barred-spiral galaxies. We find that spiral arms can be an efficient means of gas transport from the outskirts to the central parts, provided that the arms are rotating slower than the bar. While the ring star formation in models with no-arm or corotating arms is active only during about the bar growth phase, arm-driven gas accretion makes the ring star formation both enhanced and prolonged significantly in models with slow-rotating arms. The arm-enhanced SFR is larger by a factor of ~ 3-20 than in the no-arm model, with larger values corresponding to stronger and slower arms. Arm-induced mass inflows also make dust lanes stronger. Nuclear rings in slow-arm models are ~ 45% larger than in the no-arm counterparts. Star clusters that form in a nuclear ring exhibit an age gradient in the azimuthal direction only when the SFR is small, whereas no noticeable age gradient is found in the...

  7. Feeding and development of Nephaspis Oculata (Coleoptera: Coccinellidae) on rugose spiraling whitefly

    Science.gov (United States)

    Nephaspis oculata (Blatchley, 1917) is a whitefly predatory lady beetle which has been studied for its biological control effect on different whiteflies. Here, we studied the feeding rate and development of this beetle on rugose spiraling whitefly (RSW), Aleurodicus rugioperculatus Martin 2004, an i...

  8. Development and characterization of 3D-printed feed spacers for spiral wound membrane systems

    KAUST Repository

    Siddiqui, Amber Siddiqui Shahnawaz

    2016-01-02

    Feed spacers are important for the impact of biofouling on the performance of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane systems. The objective of this study was to propose a strategy for developing, characterizing, and testing of feed spacers by numerical modeling, three-dimensional (3D) printing of feed spacers and experimental membrane fouling simulator (MFS) studies. The results of numerical modeling on the hydraulic behavior of various feed spacer geometries suggested that the impact of spacers on hydraulics and biofouling can be improved. A good agreement was found for the modeled and measured relationship between linear flow velocity and pressure drop for feed spacers with the same geometry, indicating that modeling can serve as first step in spacer characterization. An experimental comparison study of a feed spacer currently applied in practice and a 3D printed feed spacer with the same geometry showed (i) similar hydraulic behavior, (ii) similar pressure drop development with time and (iii) similar biomass accumulation during MFS biofouling studies, indicating that 3D printing technology is an alternative strategy for development of thin feed spacers with a complex geometry. Based on the numerical modeling results, a modified feed spacer with low pressure drop was selected for 3D printing. The comparison study of the feed spacer from practice and the modified geometry 3D printed feed spacer established that the 3D printed spacer had (i) a lower pressure drop during hydraulic testing, (ii) a lower pressure drop increase in time with the same accumulated biomass amount, indicating that modifying feed spacer geometries can reduce the impact of accumulated biomass on membrane performance. The combination of numerical modeling of feed spacers and experimental testing of 3D printed feed spacers is a promising strategy (rapid, low cost and representative) to develop advanced feed spacers aiming to reduce the impact of biofilm formation on

  9. Development and characterization of 3D-printed feed spacers for spiral wound membrane systems.

    Science.gov (United States)

    Siddiqui, Amber; Farhat, Nadia; Bucs, Szilárd S; Linares, Rodrigo Valladares; Picioreanu, Cristian; Kruithof, Joop C; van Loosdrecht, Mark C M; Kidwell, James; Vrouwenvelder, Johannes S

    2016-03-15

    Feed spacers are important for the impact of biofouling on the performance of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane systems. The objective of this study was to propose a strategy for developing, characterizing, and testing of feed spacers by numerical modeling, three-dimensional (3D) printing of feed spacers and experimental membrane fouling simulator (MFS) studies. The results of numerical modeling on the hydrodynamic behavior of various feed spacer geometries suggested that the impact of spacers on hydrodynamics and biofouling can be improved. A good agreement was found for the modeled and measured relationship between linear flow velocity and pressure drop for feed spacers with the same geometry, indicating that modeling can serve as the first step in spacer characterization. An experimental comparison study of a feed spacer currently applied in practice and a 3D printed feed spacer with the same geometry showed (i) similar hydrodynamic behavior, (ii) similar pressure drop development with time and (iii) similar biomass accumulation during MFS biofouling studies, indicating that 3D printing technology is an alternative strategy for development of thin feed spacers with a complex geometry. Based on the numerical modeling results, a modified feed spacer with low pressure drop was selected for 3D printing. The comparison study of the feed spacer from practice and the modified geometry 3D printed feed spacer established that the 3D printed spacer had (i) a lower pressure drop during hydrodynamic testing, (ii) a lower pressure drop increase in time with the same accumulated biomass amount, indicating that modifying feed spacer geometries can reduce the impact of accumulated biomass on membrane performance. The combination of numerical modeling of feed spacers and experimental testing of 3D printed feed spacers is a promising strategy (rapid, low cost and representative) to develop advanced feed spacers aiming to reduce the impact of

  10. Spacer geometry and particle deposition in spiral wound membrane feed channels

    KAUST Repository

    Radu, A.I.

    2014-11-01

    Deposition of microspheres mimicking bacterial cells was studied experimentally and with a numerical model in feed spacer membrane channels, as used in spiral wound nanofiltration (NF) and reverse osmosis (RO) membrane systems. In-situ microscopic observations in membrane fouling simulators revealed formation of specific particle deposition patterns for different diamond and ladder feed spacer orientations. A three-dimensional numerical model combining fluid flow with a Lagrangian approach for particle trajectory calculations could describe very well the in-situ observations on particle deposition in flow cells. Feed spacer geometry, positioning and cross-flow velocity sensitively influenced the particle transport and deposition patterns. The deposition patterns were not influenced by permeate production. This combined experimental-modeling approach could be used for feed spacer geometry optimization studies for reduced (bio)fouling. © 2014 Elsevier Ltd.

  11. A Numerical Simulation of Star Formation in Nuclear Rings of Barred-Spiral Galaxies

    Science.gov (United States)

    Seo, Woo-Young; Kim, W.

    2014-01-01

    We use grid-based hydrodynamic simulations to study star formation history in nuclear rings of barred-spiral galaxies. We assume infinitesimally thin, isothermal, and unmagnetized gaseous disk. To investigate effects of spiral arm potential, we calculate both models with and without spiral. We find that star formation rate (SFR) in a nuclear ring is determined by the mass inflow rate to the ring rather than the total gas mass in the ring. In case of models without spiral arms, the SFR shows a strong primary burst at early time, and declines to small values after after that. The primary burst is caused by the rapid gas infall to the ring due to the bar growth. On the other hand, models with spiral arms show multiple star bursts at late time caused by additional gas inflow from outside bar region. When the SFR is low, ages of young star clusters exhibit a bipolar azimuthal gradient along the ring since star formation occurs near the contact points between dust lanes and the nuclear ring. When the SFR is large, there are no age gradient of star clusters since star formation sites are widely distributed throughout the whole ring region.

  12. Biofouling Control in Spiral-Wound Membrane Systems: Impact of Feed Spacer Modification and Biocides

    KAUST Repository

    Siddiqui, Amber

    2016-12-01

    High-quality drinking water can be produced with membrane-based filtration processes like reverse osmosis and nanofiltration. One of the major problems in these membrane systems is biofouling that reduces the membrane performance, increasing operational costs. Current biofouling control strategies such as pre-treatment, membrane modification, and chemical cleaning are not sufficient in all cases. Feed spacers are thin (0.8 mm), complex geometry meshes that separate membranes in a module. The main objective of this research was to evaluate whether feed spacer modification is a suitable strategy to control biofouling. Membrane fouling simulator studies with six feed spacers showed differences in biofouled spacer performance, concluding that (i) spacer geometry influences biofouling impact and (ii) biofouling studies are essential for evaluation of spacer biofouling impact. Computed tomography (CT) was found as a suitable technique to obtain three-dimensional (3D) measurements of spacers, enabling more representative mathematical modeling of hydraulic behavior of spacers in membrane systems. A strategy for developing, characterizing, and testing of spacers by numerical modeling, 3D printing of spacers and experimental membrane fouling simulator studies was developed. The combination of modeling and experimental testing of 3D printed spacers is a promising strategy to develop advanced spacers aiming to reduce the impact of biofilm formation on membrane performance and to improve the cleanability of spiral-wound membrane systems.

  13. Investigating the nuclear activity of barred spiral galaxies: the case of NGC 1672

    CERN Document Server

    Jenkins, L P; Colbert, E J M; Koribalski, B; Kuntz, K D; Levan, A J; Ojha, R; Roberts, T P; Ward, M J; Zezas, A

    2011-01-01

    We have performed an X-ray study of the nearby barred spiral galaxy NGC1672, primarily to ascertain the effect of the bar on its nuclear activity. We use both Chandra and XMM-Newton observations to investigate its X-ray properties, together with supporting high-resolution optical imaging data from the Hubble Space Telescope (HST), infrared imaging from the Spitzer Space Telescope, and ATCA ground-based radio data. We detect 28 X-ray sources within the D25 area of the galaxy, many of which correlate spatially with star-formation in the bar and spiral arms, while two are identified as background galaxies in the HST images. Nine of the X-ray sources are ULXs, with the three brightest (LX > 5E39 erg/s) located at the ends of the bar. With the spatial resolution of Chandra, we are able to show for the first time that NGC1672 possesses a hard (Gamma~1.5) nuclear X-ray source with a 2-10 keV luminosity of 4E38 erg/s. This is surrounded by an X-ray bright circumnuclear star-forming ring, comprised of point sources an...

  14. Clues to Nuclear Star Cluster Formation from Edge-on Spirals

    CERN Document Server

    Seth, A C; Hodge, P W; Debattista, V P; Seth, Anil C.; Dalcanton, Julianne J.; Hodge, Paul W.; Debattista, Victor P.

    2006-01-01

    We find 9 nuclear cluster candidates in a sample of 14 edge-on, late-type galaxies observed with HST/ACS. These clusters have magnitudes (M_I ~ -11) and sizes (r_eff ~ 3pc) similar to those found in previous studies of face-on, late-type spirals and dE galaxies. However, three of the nuclear clusters are significantly flattened and show evidence for multiple, coincident structural components. The elongations of these three clusters are aligned to within 10 degrees of the galaxies' major axes. Structurally, the flattened clusters are well fit by a combination of a spheroid and a disk or ring. The nuclear cluster disks/rings have F606W-F814W (~V-I) colors 0.3-0.6 magnitudes bluer than the spheroid components, suggesting that the stars in these components have ages < 1 Gyr. In NGC 4244, the nearest of the nuclear clusters, we further constrain the stellar populations and provide a lower limit on the dynamical mass via spectroscopy. We also present tentative evidence that another of the nuclear clusters (in NG...

  15. A close nuclear black-hole pair in the spiral galaxy NGC 3393.

    Science.gov (United States)

    Fabbiano, G; Wang, Junfeng; Elvis, M; Risaliti, G

    2011-08-31

    The current picture of galaxy evolution advocates co-evolution of galaxies and their nuclear massive black holes, through accretion and galactic merging. Pairs of quasars, each with a massive black hole at the centre of its galaxy, have separations of 6,000 to 300,000 light years (refs 2 and 3; 1 parsec = 3.26 light years) and exemplify the first stages of this gravitational interaction. The final stages of the black-hole merging process, through binary black holes and final collapse into a single black hole with gravitational wave emission, are consistent with the sub-light-year separation inferred from the optical spectra and light-variability of two such quasars. The double active nuclei of a few nearby galaxies with disrupted morphology and intense star formation (such as NGC 6240 with a separation of about 2,600 light years and Mrk 463 with a separation of about 13,000 light years between the nuclei) demonstrate the importance of major mergers of equal-mass spiral galaxies in this evolution; such mergers lead to an elliptical galaxy, as in the case of the double-radio-nucleus elliptical galaxy 0402+379 (with a separation of about 24 light years between the nuclei). Minor mergers of a spiral galaxy with a smaller companion should be a more common occurrence, evolving into spiral galaxies with active massive black-hole pairs, but have hitherto not been seen. Here we report the presence of two active massive black holes, separated by about 490 light years, in the Seyfert galaxy NGC 3393 (50 Mpc, about 160 million light years). The regular spiral morphology and predominantly old circum-nuclear stellar population of this galaxy, and the closeness of the black holes embedded in the bulge, provide a hitherto missing observational point to the study of galaxy/black hole evolution. Comparison of our observations with current theoretical models of mergers suggests that they are the result of minor merger evolution.

  16. Upgrade of the SPIRAL identification station for high-precision measurements of nuclear β decay

    Energy Technology Data Exchange (ETDEWEB)

    Grinyer, G.F., E-mail: grinyer@ganil.fr [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Thomas, J.C. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Blank, B. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1, UMR 5797, CNRS/IN2P3, Chemin de Solarium, BP 120, 33175 Gradignan (France); Bouzomita, H. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Austin, R.A.E. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia, Canada B3H 3C3 (Canada); Ball, G.C. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 2A3 (Canada); Bucaille, F.; Delahaye, P. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Finlay, P. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Frémont, G. [Grand Accélérateur National d' Ions Lourds (GANIL), CEA/DSM-CNRS/IN2P3, Bvd Henri Becquerel, 14076 Caen (France); Gibelin, J. [LPC-Caen, ENSICAEN, Université de Caen, CNRS/IN2P3, Caen (France); Giovinazzo, J. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1, UMR 5797, CNRS/IN2P3, Chemin de Solarium, BP 120, 33175 Gradignan (France); and others

    2014-03-21

    The low-energy identification station at SPIRAL (Système de Production d'Ions Radioactifs Accélérés en Ligne) has been upgraded for studying the β decays of short-lived radioactive isotopes and to perform high-precision half-life and branching-ratio measurements for superallowed Fermi and isospin T=1/2 mirror β decays. These new capabilities, combined with an existing Paul trap setup for measurements of β–ν angular-correlation coefficients, provide a powerful facility for investigating fundamental properties of the electroweak interaction through nuclear β decays. A detailed description of the design study, construction, and first results obtained from an in-beam commissioning experiment on the β{sup +} decays {sup 14} O and {sup 17}F are presented.

  17. Kinematics and excitation of the nuclear spiral in the active galaxy Arp 102B

    CERN Document Server

    Couto, Guilherme S; Axon, David J; Robinson, Andrew; Kharb, Preeti; Riffel, Rogemar A

    2013-01-01

    We present a two-dimensional analysis of the gaseous excitation and kinematics of the inner 2.5 x 1.7 kpc^2 of the LINER/Seyfert 1 galaxy Arp 102B, from optical spectra obtained with the GMOS integral field spectrograph on the Gemini North telescope at a spatial resolution of 250 pc. Emission-line flux maps show the same two-armed nuclear spiral we have discovered in previous observations with the HST-ACS camera. One arm reaches 1 kpc to the east and the other 500 pc to the west, with a 8.4 GHz VLA bent radio jet correlating with the former. The gas density is highest (500 - 900 cm^(-3)) at the nucleus and in the northern border of the east arm, at a region where the radio jet seems to be deflected. Channel maps show blueshifts but also some redshifts at the eastern arm and jet location which can be interpreted as originated in the front and back walls of an outflow pushed by the radio jet, suggesting also that the outflow is launched close to the plane of the sky. We estimate a mass outflow rate along the ea...

  18. Deep repository for spent nuclear fuel. Facility description - Layout E. Spiral ramp with one operational area

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Stig [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Forsgren, Ebbe [SwedPower AB, Stockholm (Sweden); Lange, Fritz [Lange Art AB, Stockholm (Sweden)

    2002-04-01

    This report documents a proposal for the design of the deep repository for spent nuclear fuel. The proposal is based on the principles that were formulated in the original KBS-3 study, but has been supplemented by investigations and experience to reflect current knowledge. The purpose of the report is to provide an integrated picture of the deep repository, as a basis for SKB's other work, e.g. environmental impact assessments, transport systems, safety issues and alternative locations, and to provide a co-ordinated account of the conditions and requirements concerning all of the necessary functions in the deep repository in order to have a well functioning facility. In addition, it should be possible to use the report as: a tool in the task of achieving a co-ordinated, safe and accepted design for the facility, a basis for further planning and costing, a basis for adaptation to geographic and other conditions for the particular location, a basis for information material, both within SKB and for interested parties outside, such as public authorities, municipalities and the general public. The capacity of the deep repository has been chosen on the basis of 40 years of operation of the Swedish nuclear power reactors, which will produce approximately 9,000 tons of uranium, equivalent to approximately 4,500 canisters. The design outlined is based on theoretical analyses of functions, safety requirements, procedures etc. that can be identified during the various phases of the construction and operation of the repository. In addition, preliminary organisation and staffing plans have been drawn up, for use as the basis for planning the necessary buildings. The report gives a vision of the overall layout and function of the facility, and a proposal for the design of all individual parts of the repository. The relationships between the various parts of the repository are described, both above and below ground, as is the interplay between the part above ground and part

  19. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: a novel platform for eco-friendly biofouling mitigation.

    Science.gov (United States)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R; Kemperman, Antoine J B; Ederth, Thomas; Nijmeijer, Kitty

    2015-03-15

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA), cationic (polyDMAEMA) and anionic (polySPMA) hydrogels have been successfully grafted onto polypropylene (PP) feed spacers via plasma-mediated UV-polymerization. These coatings maintained their chemical stability after 7 days incubation in neutral (pH 7), acidic (pH 5) and basic (pH 9) environments. Anti-biofouling properties of these coatings were evaluated by Escherichia coli attachment assay and nanofiltration experiments at a TMP of 600 kPag using tap water with additional nutrients as feed and by using optical coherence tomography. Especially the anionic polySPMA-coated PP feed spacer shows reduced attachment of E. coli and biofouling in the spacer-filled narrow channels resulting in delayed biofilm growth. Employing this highly hydrophilic coating during removal of biofouling by two-phase flow cleaning also showed enhanced cleaning efficiency, feed channel pressure drop and flux recoveries. The strong hydrophilic nature and the presence of negative charge on polySPMA are most probably responsible for the improved antifouling behavior. A combination of polySPMA-coated PP feed spacers and two-phase flow cleaning therefore is promising and an environmentally friendly approach to control biofouling in NF/RO systems employing spiral-wound membrane modules.

  20. CHANG-ES V: Nuclear Outflow in a Virgo Cluster Spiral after a Tidal Disruption Event

    Science.gov (United States)

    Irwin, Judith A.; Henriksen, Richard N.; Krause, Marita; Wang, Q. Daniel; Wiegert, Theresa; Murphy, Eric J.; Heald, George; Perlman, Eric

    2015-08-01

    We have observed the Virgo Cluster spiral galaxy, NGC 4845, at 1.6 and 6 GHz using the Karl G. Jansky Very Large Array, as part of the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES). The source consists of a bright unresolved core with a surrounding weak central disk (1.8 kpc diameter). The core is variable over the 6 month timescale of the CHANG-ES data and has increased by a factor of ≈6 since 1995. The wide bandwidths of CHANG-ES have allowed us to determine the spectral evolution of this core, which peaks between 1.6 and 6 GHz (it is a Gigahertz-peaked spectrum source). We show that the spectral turnover is dominated by synchrotron self-absorption and that the spectral evolution can be explained by adiabatic expansion (outflow), likely in the form of a jet or cone. The CHANG-ES observations serendipitously overlap in time with the hard X-ray light curve obtained by Nikolajuk & Walter (2013), which they interpret as due to a tidal disruption event (TDE) of a super-Jupiter mass object around a 105 M⊙ black hole. We outline a standard jet model, provide an explanation for the observed circular polarization, and quantitatively suggest a link between the peak radio and peak X-ray emission via inverse Compton upscattering of the photons emitted by the relativistic electrons. We predict that it should be possible to resolve a young radio jet via VLBI as a result of this nearby TDE.

  1. Discovery of ultra-compact nuclear rings in three spiral galaxies

    CERN Document Server

    Comerón, S; Beckman, J E; Shlosman, I

    2007-01-01

    Ring-shaped morphologies of nuclear star-forming regions within the central 40-200 pc of disk galaxies have been barely resolved so far in three composite Sy2 nuclei, the Sy2 Circinus galaxy and in three non-AGN galaxies. Such morphologies resemble those of the standard 1 kpc-size nuclear rings that lie in the inner Lindblad resonance regions of disk galaxies and, if they have a similar origin, represent recent radial gas inflows tantalisingly close to the central supermassive black holes. We aim to identify the population of such ultra-compact nuclear rings (UCNRs) and study their properties in relation to those of the host galaxies. From archival Hubble Space Telescope UV and Halpha images and from dust structure maps of the circumnuclear regions in nearby galaxies, we analyse the morphology of the star formation and dust, specifically searching for ring structures on the smallest observable scales. In a sample of 38 galaxies studied, we have detected a total of four new UCNRs, 30-130 pc in radius, in three...

  2. Spiraling dopaminergic circuitry from the ventral striatum to dorsal striatum is an effective feed-forward loop

    NARCIS (Netherlands)

    Ikeda, H.; Saigusa, T.; Kamei, J.; Koshikawa, N.; Cools, A.R.

    2013-01-01

    Central dopamine systems are key players in the cerebral organization of behavior and in various neurological and psychiatric diseases. We demonstrate the presence of a neurochemical feed-forward loop characterized by region-specific changes in dopamine efflux in serially connected striatal regions,

  3. Feed-forward transcriptional programming by nuclear receptors: regulatory principles and therapeutic implications.

    Science.gov (United States)

    Sasse, Sarah K; Gerber, Anthony N

    2015-01-01

    Nuclear receptors (NRs) are widely targeted to treat a range of human diseases. Feed-forward loops are an ancient mechanism through which single cell organisms organize transcriptional programming and modulate gene expression dynamics, but they have not been systematically studied as a regulatory paradigm for NR-mediated transcriptional responses. Here, we provide an overview of the basic properties of feed-forward loops as predicted by mathematical models and validated experimentally in single cell organisms. We review existing evidence implicating feed-forward loops as important in controlling clinically relevant transcriptional responses to estrogens, progestins, and glucocorticoids, among other NR ligands. We propose that feed-forward transcriptional circuits are a major mechanism through which NRs integrate signals, exert temporal control over gene regulation, and compartmentalize client transcriptomes into discrete subunits. Implications for the design and function of novel selective NR ligands are discussed.

  4. Development of novel on-chip, customer-design spiral biasing adaptor on for Si drift detectors and detector arrays for X-ray and nuclear physics experiments

    Science.gov (United States)

    Li, Zheng; Chen, Wei

    2014-11-01

    A novel on-chip, customer-design spiral biasing adaptor (SBA) has been developed. A single SBA is used for biasing a Si drift detector (SDD) and SDD array. The use of an SBA reduces the biasing current. This paper shows the calculation of the geometry of an SBA and an SDD to get the best drift field in the SDD and SDD array. Prototype SBAs have been fabricated to verify the concept. Electrical measurements on these SBAs are in agreement with the expectations. The new SDD array with an SBA can be used for X-ray detection and in nuclear physics experiments.

  5. Development of novel on-chip, customer-design spiral biasing adaptor on for Si drift detectors and detector arrays for X-ray and nuclear physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zheng, E-mail: lizheng@xtu.edu.cn [School of Materials, Optoelectronics and Physics, Xiangtan University, Xiangtan, Hunan 411105 (China); Chen, Wei [Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2014-11-21

    A novel on-chip, customer-design spiral biasing adaptor (SBA) has been developed. A single SBA is used for biasing a Si drift detector (SDD) and SDD array. The use of an SBA reduces the biasing current. This paper shows the calculation of the geometry of an SBA and an SDD to get the best drift field in the SDD and SDD array. Prototype SBAs have been fabricated to verify the concept. Electrical measurements on these SBAs are in agreement with the expectations. The new SDD array with an SBA can be used for X-ray detection and in nuclear physics experiments.

  6. Spiral symmetry

    CERN Document Server

    Hargittai, Istvan

    1992-01-01

    From the tiny twisted biological molecules to the gargantuan curling arms of many galaxies, the physical world contains a startling repetition of spiral patterns. Today, researchers have a keen interest in identifying, measuring, and defining these patterns in scientific terms. Spirals play an important role in the growth processes of many biological forms and organisms. Also, through time, humans have imitated spiral motifs in their art forms, and invented new and unusual spirals which have no counterparts in the natural world. Therefore, one goal of this multiauthored book is to stress the c

  7. Electrorefiner system for recovering purified metal from impure nuclear feed material

    Energy Technology Data Exchange (ETDEWEB)

    Berger, John F.; Williamson, Mark A.; Wiedmeyer, Stanley G.; Willit, James L.; Barnes, Laurel A.; Blaskovitz, Robert J.

    2015-10-06

    An electrorefiner system according to a non-limiting embodiment of the present invention may include a vessel configured to maintain a molten salt electrolyte and configured to receive a plurality of alternately arranged cathode and anode assemblies. The anode assemblies are configured to hold an impure nuclear feed material. Upon application of the power system, the impure nuclear feed material is anodically dissolved and a purified metal is deposited on the cathode rods of the cathode assemblies. A scraper is configured to dislodge the purified metal deposited on the cathode rods. A conveyor system is disposed at a bottom of the vessel and configured to remove the dislodged purified metal from the vessel.

  8. Plant parasitic nematode effectors target host defence and nuclear functions to establish feeding cells

    Directory of Open Access Journals (Sweden)

    Michaël eQuentin

    2013-03-01

    Full Text Available Plant parasitic nematodes are microscopic worms, the most damaging species of which have adopted a sedentary lifestyle within their hosts. These obligate endoparasites have a biotrophic relationship with plants, in which they induce the differentiation of root cells into hypertrophied, multinucleate feeding cells. Effectors synthesised in the oesophageal glands of the nematode are injected into the plant cells via the syringe-like stylet and play a key role in manipulating the host machinery. The establishment of specialized feeding cells requires these effectors to modulate many aspects of plant cell morphogenesis and physiology, including defence responses. This cell reprogramming requires changes to host nuclear processes. Some proteins encoded by parasitism genes target host nuclei. Several of these proteins were immunolocalised within feeding cell nuclei or shown to interact with host nuclear proteins. Comparative genomics and functional analyses are gradually revealing the roles of nematode effectors. We describe here these effectors and their hypothesised roles in the unique feeding behaviour of these pests.

  9. Conversion of nuclear waste to molten glass: Formation of porous amorphous alumina in a high-Al melter feed

    Science.gov (United States)

    Xu, Kai; Hrma, Pavel; Washton, Nancy; Schweiger, Michael J.; Kruger, Albert A.

    2017-01-01

    The transition of Al phases in a simulated high-Al high-level nuclear waste melter feed heated at 5 K min-1 to 700 °C was investigated with transmission electron microscopy, 27Al nuclear magnetic resonance spectroscopy, the Brunauer-Emmett-Teller method, and X-ray diffraction. At temperatures between 300 and 500 °C, porous amorphous alumina formed from the dehydration of gibbsite, resulting in increased specific surface area of the feed (∼8 m2 g-1). The high-surface-area amorphous alumina formed in this manner could potentially stop salt migration in the cold cap during nuclear waste vitrification.

  10. Conversion of nuclear waste to molten glass: Formation of porous amorphous alumina in a high-Al melter feed

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai; Hrma, Pavel R.; Washton, Nancy M.; Schweiger, Michael J.; Kruger, Albert A.

    2017-01-01

    The transition of Al phases in a simulated high-Al high-level nuclear waste melter feed heated at 5 K min-1 to 700°C was investigated with transmission electron microscopy, 27Al nuclear magnetic resonance spectroscopy, the Brunauer-Emmett-Teller method, and X-ray diffraction. At temperatures between 300 and 500°C, porous amorphous alumina formed from the dehydration of gibbsite, resulting in increased specific surface area of the feed (~8 m2 g-1). The high-surface-area amorphous alumina formed in this manner could potentially stop salt migration in the cold cap during nuclear waste vitrification.

  11. Model for the conversion of nuclear waste melter feed to glass

    Energy Technology Data Exchange (ETDEWEB)

    Pokorny, Richard [Inst. of Chemical Technology Prague (Czech Republic). Dept. of Chemical Engineering; Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pohang Univ. of Science and Technology, Pohang (Korea, Republic of). Division of Advanced Nuclear Engineering

    2014-02-01

    The rate of batch-to-glass conversion is a primary concern for the vitrification of nuclear waste, as it directly influences the life cycle of the cleanup process. This study describes the development of an advanced model of the cold cap, which augments the previous model by further developments on the structure and the dynamics of the foam layer. The foam layer on the bottom of the cold cap consists of the primary foam, cavities, and the secondary foam, and forms an interface through which the heat is transferred to the cold cap. Other model enhancements include the behavior of intermediate crystalline phases and the dissolution of quartz particles. The model relates the melting rate to feed properties and melter conditions, such as the molten glass temperature, foaminess of the feed, or the heat fraction supplied to the cold cap from the plenum space. The model correctly predicts a 25% increase in melting rate when changing the alumina source in the melter feed from Al(OH)3 to AlO(OH). It is expected that this model will be incorporated in the full glass melter model as its integral component.

  12. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    At the core of Heinz Werner’s concept of development is what he called “the genetic principle of spirality:” over the course of ontogenetic development, lower levels, processes, and functions do not disappear, and can even resurface again under specific conditions, normal and pathological. Werner...

  13. CHANG-ES V: Nuclear Radio Outflow in a Virgo Cluster Spiral after a Tidal Disruption Event

    CERN Document Server

    Irwin, Judith A; Krause, Marita; Wang, Q Daniel; Wiegert, Theresa; Murphy, Eric J; Heald, George; Perlman, Eric

    2015-01-01

    We have observed the Virgo Cluster spiral galaxy, NGC~4845, at 1.6 and 6 GHz using the Karl G. Jansky Very Large Array, as part of the `Continuum Halos in Nearby Galaxies -- an EVLA Survey' (CHANG-ES). The source consists of a bright unresolved core with a surrounding weak central disk (1.8 kpc diameter). The core is variable over the 6 month time scale of the CHANG-ES data and has increased by a factor of $\\approx$ 6 since 1995. The wide bandwidths of CHANG-ES have allowed us to determine the spectral evolution of this core which peaks {\\it between} 1.6 and 6 GHz (it is a GigaHertz-peaked spectrum source).We show that the spectral turnover is dominated by synchrotron self-absorption and that the spectral evolution can be explained by adiabatic expansion (outflow), likely in the form of a jet or cone. The CHANG-ES observations serendipitously overlap in time with the hard X-ray light curve obtained by Nikolajuk \\& Walter (2013) which they interpret as due to a tidal disruption event (TDE) of a super-Jupit...

  14. Observational Overview of the Feeding of Active Galactic Nuclei

    CERN Document Server

    Storchi-Bergmann, Thaisa

    2007-01-01

    I present an overview of the observational signatures of feeding of Active Galactic Nuclei, discussing briefly the role of interactions among galaxies on extragalactic scales, and of non-axisymmetric gravitational potentials -- such as bars -- on galactic scales. Then I discuss at larger length the feeding signatures on hundred of parsec scales, for which new results include: (1) recent star formation surrounding the active nucleus on tens of parsec scales; (2) excess of gas and dust in active galaxies relative to non-active ones, in the form of nuclear spirals and disks; (3) new kinematic signatures of gas inflow along nuclear spiral arms, which may be the long sought mechanism to bring gas from kiloparsec scales down to the nucleus to feed the supermassive black hole.

  15. Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies

    CERN Document Server

    Capelo, Pedro R

    2016-01-01

    We study the dynamics of galaxy mergers, with emphasis on the gas feeding of nuclear regions, using a suite of hydrodynamical simulations of galaxy encounters. The high spatial and temporal resolution of the simulations allows us to not only recover the standard picture of tidal-torque induced inflows, but also to detail another, important feeding path produced by ram pressure. The induced shocks effectively decouple the dynamics of the gas from that of the stars, greatly enhancing the loss of gas angular momentum and leading to increased central inflows. The ram-pressure shocks also cause, in many cases, the entire galactic gas disc of the smaller galaxy to abruptly change its direction of rotation, causing a complete "flip" and, several $10^8$ yr later, a subsequent "counter-flip". This phenomenon results in the existence of long-lived decoupled gas-stellar and stellar-stellar discs, which could hint at a new explanation for the origin of some of the observed kinematically decoupled cores/counter-rotating d...

  16. Shocks and angular momentum flips: a different path to feeding the nuclear regions of merging galaxies

    Science.gov (United States)

    Capelo, Pedro R.; Dotti, Massimo

    2017-03-01

    We study the dynamics of galaxy mergers, with emphasis on the gas feeding of nuclear regions, using a suite of hydrodynamical simulations of galaxy encounters. The high spatial and temporal resolution of the simulations allows us to not only recover the standard picture of tidal-torque-induced inflows, but also to detail another, important feeding path produced by ram pressure. The induced shocks effectively decouple the dynamics of the gas from that of the stars, greatly enhancing the loss of gas angular momentum and leading to increased central inflows. The ram-pressure shocks also cause, in many cases, the entire galactic gas disc of the smaller galaxy to abruptly change its direction of rotation, causing a complete 'flip' and, several 108 yr later, a subsequent 'counter-flip'. This phenomenon results in the existence of long-lived decoupled gas-stellar and stellar-stellar discs, which could hint at a new explanation for the origin of some of the observed kinematically decoupled cores/counter-rotating discs. Lastly, we speculate, in the case of non-coplanar mergers, on the possible existence of a new class of remnant systems similar to some of the observed X-shaped radio galaxies.

  17. Model for the conversion of nuclear waste melter feed to glass

    Science.gov (United States)

    Pokorny, Richard; Hrma, Pavel

    2014-02-01

    The rate of batch-to-glass conversion is a primary concern for the vitrification of nuclear waste, as it directly influences the life cycle of the cleanup process. This study describes the development of an advanced model of the cold cap, which augments the previous model by further developments on the structure and the dynamics of the foam layer. The foam layer on the bottom of the cold cap consists of the primary foam, cavities, and the secondary foam, and forms an interface through which the heat is transferred to the cold cap. Other model enhancements include the behavior of intermediate crystalline phases and the dissolution of quartz particles. The model relates the melting rate to feed properties and melter conditions, such as the molten glass temperature, foaminess of the melt, or the heat fraction supplied to the cold cap from the plenum space. The model correctly predicts a 25% increase in melting rate when changing the alumina source in the melter feed from Al(OH)3 to AlO(OH). It is expected that this model will be incorporated in the full glass melter model as its integral component.

  18. Spiral inflation

    Directory of Open Access Journals (Sweden)

    Gabriela Barenboim

    2015-02-01

    Full Text Available We propose a novel scenario of primordial inflation in which the inflaton goes through a spiral motion starting from around the top of a symmetry breaking potential. We show that, even though inflation takes place for a field value much smaller than Planck scale, it is possible to obtain relatively large tensor-to-scalar ratio (r∼0.1 without fine tuning. The inflationary observables perfectly match Planck data.

  19. The Structure of Nuclear Star Clusters in Nearby Late-type Spiral Galaxies from Hubble Space Telescope Wide Field Camera 3 Imaging

    CERN Document Server

    Carson, Daniel J; Seth, Anil C; Brok, Mark den; Cappelari, Michele; Greene, Jenny E; Ho, Luis C; Neumayer, Nadine

    2015-01-01

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters residing in late-type spiral galaxies, in seven bands that span the near-ultraviolet to the near-infrared. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties. For six of the ten clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population which is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer waveleng...

  20. Spiralling upward.

    Science.gov (United States)

    Schulgasser, Kalman; Witztum, Allan

    2004-09-21

    Thin vertical leaves often manifest twist. Perhaps the most prominent example of this is in Typha sp., but such twist is also apparent in Narcissus, Pancratium and many other genera. Such a blade is often referred to as a "spiral leaf". We will indicate the mechanical advantage afforded to the leaf by this arrangement, i.e. that it permits the leaf to achieve a greater height without losing stability, that is bending over due to its own weight. We quantify this gain and show how by a simple experiment it can be shown that the advantage is indeed utilized in nature. Typha domingensis is offered as an example.

  1. The spiral

    DEFF Research Database (Denmark)

    Bibace, Roger; Kharlamov, Nikita

    2013-01-01

    ’s work with Bernard Kaplan on symbol formation is a primer on this idea. This paper examines the idea of spirality and develops the notion of dynamic coexistence that can clarify the issue of directionality of development; that is, what is the general trajectory or ground plan that development assumes....... Directionality is discussed in terms of the organism-in-environment unfolding over time as the unit of developmental analysis. Thinking on this issue has proceeded from the nature–nurture debates, to recognition of the interaction of external and internal processes, to transactions between the organism...

  2. The Role of Nuclear Star Clusters in Enhancing Supermassive Black Hole Feeding Rates During Galaxy Mergers

    CERN Document Server

    Naiman, J P; Debuhr, J; Ma, C -P

    2014-01-01

    During galaxy mergers the gas falls to the center, triggers star formation, and feeds the rapid growth of supermassive black holes (SMBHs). SMBHs respond to this fueling by supplying energy back to the ambient gas. Numerical studies suggest that this feedback is necessary to explain why the properties of SMBHs and the formation of bulges are closely related. This intimate link between the SMBH's mass and the large scale dynamics and luminosity of the host has proven to be a difficult issue to tackle with simulations due to the inability to resolve all the relevant length scales simultaneously. In this paper we simulate SMBH growth at high-resolution with {\\it FLASH}, accounting for the gravitational focusing effects of nuclear star clusters (NSCs), which appear to be ubiquitous in galactic nuclei. In the simulations, the NSC core is resolved by a minimum cell size of about 0.001 pc or approximately $10^{-3}$ of the cluster's radius. We discuss the conditions required for effective gas funneling to occur, whic...

  3. Melter Feed Reactions at T ≤ 700°C for Nuclear Waste Vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hrma, Pavel R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rice, Jarrett A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schweiger, Michael J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Crum, Jarrod V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-07-23

    Batch reactions and phase transitions in a nuclear waste feed heated at 5 K min-1 up to 600°C were investigated by optical microscopy, scanning electron microscopy with energy dispersive X-ray spectrometer, and X-ray diffraction. Quenched samples were leached in deionized water at room temperature and 80°C to extract soluble salts and early glass-forming melt, respectively. To determine the content and composition of leachable phases, the leachates were analyzed by the inductively-coupled plasma spectroscopy. By ~400°C, gibbsite and borax lost water and converted to amorphous and intermediate crystalline phases. Between 400°C and 600°C, the sodium borate early glass-forming melt reacted with amorphous aluminum oxide and calcium oxide to form intermediate products containing Al and Ca. At ~600°C, half Na and B converted to the early glass-forming melt, and quartz began to dissolve in the melt.

  4. Quantum spirals

    CERN Document Server

    Yoshida, Z

    2016-01-01

    Quantum systems often exhibit fundamental incapability to entertain vortex. The Meissner effect, a complete expulsion of the magnetic field (the electromagnetic vorticity), for instance, is taken to be the defining attribute of the superconducting state. Superfluidity is another, close-parallel example; fluid vorticity can reside only on topological defects with a limited (quantized) amount. Recent developments in the Bose-Einstein condensates produced by particle traps further emphasize this characteristic. We show that the challenge of imparting vorticity to a quantum fluid can be met through a nonlinear mechanism operating in a hot fluid corresponding to a thermally modified Pauli-Schroedinger spinor field. In a simple field-free model, we show that the thermal effect, represented by a nonlinear, non-Hermitian Hamiltonian, in conjunction with spin vorticity, leads to new interesting quantum states; a spiral solution is explicitly worked out.

  5. Spiral tectonics

    Science.gov (United States)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  6. Spiral Inflector For Compact Cyclotron

    CERN Document Server

    Karamysheva, G A

    2004-01-01

    Compact cyclotron for explosives detection by nuclear resonance absorption of γ-rays in nitrogen is under development [1] Cyclotron will be equipped with the external ion source. The injection system consists of a double-drift beam bunching system, a spiral inflector, beam diagnostics, focusing and adjustment elements [2]. The spiral inflector for ion bending from axial to median plane is used. Computer model of spiral inflector for the Customs cyclotron is developed. 3D electrostatic field calculations of the designed inflector are performed. Calculated electric field map and magnetic field map of the cyclotron [3] are used for beam dynamic simulations. Numeric simulations are carried out for 500 particles using code for calculation of particle dynamics by integration of differential equations in Cartesian coordinate system written in MATLAB. Direct Coulomb particle-to-particle method is used to take into account space-charge effects.

  7. Hydrogel-coated feed spacers in two-phase flow cleaning in spiral wound membrane elements: A novel platform for eco-friendly biofouling mitigation

    NARCIS (Netherlands)

    Wibisono, Yusuf; Yandi, Wetra; Golabi, Mohsen; Nugraha, Roni; Cornelissen, Emile R.; Kemperman, Antoine J.B.; Ederth, Thomas; Nijmeijer, Kitty

    2015-01-01

    Biofouling is still a major challenge in the application of nanofiltration and reverse osmosis membranes. Here we present a platform approach for environmentally friendly biofouling control using a combination of a hydrogel-coated feed spacer and two-phase flow cleaning. Neutral (polyHEMA-co-PEG10MA

  8. 双螺旋喂入割前脱粒微型水稻联合收割机的设计%The Design of Double-Spiral-Feeding and Threshing Minitype Wheat Combine

    Institute of Scientific and Technical Information of China (English)

    张利娟; 耿令新; 师清翔; 卢秀丽

    2014-01-01

    A Double-Spiral-Feeding and threshing minitype rice combine is designed to meet demands of mechanized harvesting rice which grow in hilly and mountain area .The important characteristics are driving only the ears of rice along the tangential direction of roller into threshing mechanism and threshing seeds directly through threshing units before cut -ting the straws , finally the stalks are cut and laid on the ground .Overall power consumption is low due to without straw entering threshing mechanism .The combine is mainly made up of chassis , Feeding threshing device , conveyor cleaning device and cutting laying device .The first round of the prototype test indicated that Straws in the feeding entrance of threshing device are easy blocked up and seeds loss rate is higher .So in the second wheel design a collecting plate and preventing curtain are devised and structures of bearing and helical blade are optimized to resolve these problems .%为适应丘陵山区小地块水稻机械化收割的需要,设计了一种双螺旋喂入、纵置滚筒式割前脱粒水稻联合收割机,整机由履带底盘、双螺旋喂入装置、纵置式摘脱装置、输送清选装置和切割铺放装置等部件组成。其主要特点是采用割前脱粒收获方式,整机功耗低,体积小,总损失率小,对田间道路适应性强,非常适合丘陵山区小块水稻田的水稻收获。

  9. THE ROLE OF NUCLEAR STAR CLUSTERS IN ENHANCING SUPERMASSIVE BLACK HOLE FEEDING RATES DURING GALAXY MERGERS

    Energy Technology Data Exchange (ETDEWEB)

    Naiman, J. P. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Ramirez-Ruiz, E. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Debuhr, J. [Center for Research in Extreme Scale Technologies, Indiana University, Bloomington IN 47404 (United States); Ma, C.-P. [Department of Astronomy, University of California, Berkeley, CA 94720 (United States)

    2015-04-20

    During galaxy mergers the gas falls to the center, triggers star formation, and feeds the rapid growth of supermassive black holes (SMBHs). SMBHs respond to this fueling by supplying energy back to the ambient gas. Numerical studies suggest that this feedback is necessary to explain why the properties of SMBHs and the formation of bulges are closely related. This intimate link between the SMBH’s mass and the large scale dynamics and luminosity of the host has proven to be a difficult issue to tackle with simulations due to the inability to resolve all the relevant length scales simultaneously. In this paper we simulate SMBH growth at high-resolution with FLASH, accounting for the gravitational focusing effects of nuclear star clusters (NSCs), which appear to be ubiquitous in galactic nuclei. In the simulations, the NSC core is resolved by a minimum cell size of about 0.001 pc or approximately 10{sup −3} of the cluster’s radius. We discuss the conditions required for effective gas funneling to occur, which are mainly dominated by a relationship between NSC velocity dispersion and the local sound speed, and provide a sub-grid prescription for the augmentation of central SMBH accretion rates in the presence of NSCs. For the conditions expected to persist in the centers of merging galaxies, the resultant large central gas densities in NSCs should produce drastically enhanced embedded SMBH accretion rates—up to an order of magnitude increase can be achieved for gas properties resembling those in large-scale galaxy merger simulations. This will naturally result in faster black hole growth rates and higher luminosities than predicted by the commonly used Bondi–Hoyle–Lyttleton accretion formalism.

  10. 棒对星系核区恒星形成活动的影响%The Effect of Bar on Nuclear Star-forming Activities in Nearby Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    汪潋

    2009-01-01

    利用SDSS光谱,研究了IRAS卫星亮红外源星表中的盘状星系中的恒星形成性质,并着重探讨了棒对星系核区恒星形成活动的影响.利用星族合成的方法得到了每个样本星系核区的恒星组成性质、恒星形成活动的强度等信息,并比较了星系整体和核区恒星形成性质的差异.得到的结论:除去相互作用,样本中的棒星系显示出比非棒旋星系更强的核区恒星形成活动和更多的年轻星族成分.%By using SDSS spectra, we have studied nuclear star-forming properties of nearby spiral galaxies selected from Infrared Revised Bright Galaxy Sample, and try to find the effect of bar structure on star-forming activities in the nuclear regions of nearby galaxies. The composition of stellar population and the strength of star formation activities in the sample galaxies are acquired by using stellar population synthesis code ?STARLIGHT, and the star formation properties in nuclear regions are compared with that of the whole galaxies. We find that the star formation in barred spiral galaxies is more intensive than non-barred ones and barred spirals show much younger stellar populations.

  11. THE STRUCTURE OF NUCLEAR STAR CLUSTERS IN NEARBY LATE-TYPE SPIRAL GALAXIES FROM HUBBLE SPACE TELESCOPE WIDE FIELD CAMERA 3 IMAGING

    Energy Technology Data Exchange (ETDEWEB)

    Carson, Daniel J.; Barth, Aaron J. [Department of Physics and Astronomy, University of California Irvine, 4129 Frederick Reines Hall, Irvine, CA 92697 (United States); Seth, Anil C.; Brok, Mark den [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Cappellari, Michele [Sub-Department of Astrophysics, Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall—Ivy Lane, Princeton, NJ 08544 (United States); Ho, Luis C. [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Neumayer, Nadine [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)

    2015-05-15

    We obtained Hubble Space Telescope/Wide Field Camera 3 imaging of a sample of ten of the nearest and brightest nuclear clusters (NCs) residing in late-type spiral galaxies, in seven bands that span the near-UV to the near-IR. Structural properties of the clusters were measured by fitting two-dimensional surface brightness profiles to the images using GALFIT. The clusters exhibit a wide range of structural properties, with F814W absolute magnitudes that range from −11.2 to −15.1 mag and F814W effective radii that range from 1.4 to 8.3 pc. For 6 of the 10 clusters in our sample, we find changes in the effective radius with wavelength, suggesting radially varying stellar populations. In four of the objects, the effective radius increases with wavelength, indicating the presence of a younger population that is more concentrated than the bulk of the stars in the cluster. However, we find a general decrease in effective radius with wavelength in two of the objects in our sample, which may indicate extended, circumnuclear star formation. We also find a general trend of increasing roundness of the clusters at longer wavelengths, as well as a correlation between the axis ratios of the NCs and their host galaxies. These observations indicate that blue disks aligned with the host galaxy plane are a common feature of NCs in late-type galaxies, but are difficult to detect in galaxies that are close to face-on. In color–color diagrams spanning the near-UV through the near-IR, most of the clusters lie far from single-burst evolutionary tracks, showing evidence for multi-age populations. Most of the clusters have integrated colors consistent with a mix of an old population (>1 Gyr) and a young population (∼100–300 Myr). The wide wavelength coverage of our data provides a sensitivity to populations with a mix of ages that would not be possible to achieve with imaging in optical bands only. The surface brightness profiles presented in this work will be used for future

  12. 105-K Basin Material Design Basis Feed Description for Spent Nuclear Fuel (SNF) Project Facilities VOL 1 Fuel

    Energy Technology Data Exchange (ETDEWEB)

    PACKER, M.J.

    1999-11-04

    Metallic uranium Spent Nuclear Fuel (SNF) is currently stored within two water filled pools, 105-KE Basin (KE Basin) and 105-KW Basin (KW Basin), at the United States Department of Energy (U.S. DOE) Hanford Site, in southeastern Washington State. The Spent Nuclear Fuel Project (SNF Project) is responsible to DOE for operation of these fuel storage pools and for the 2100 metric tons of SNF materials that they contain. The SNF Project mission includes safe removal and transportation of all SNF from these storage basins to a new storage facility in the 200 East Area. To accomplish this mission, the SNF Project modifies the existing KE Basin and KW Basin facilities and constructs two new facilities: the 100 K Area Cold Vacuum Drying Facility (CVDF), which drains and dries the SNF; and the 200 East Area Canister Storage Building (CSB), which stores the SNF. The purpose of this document is to describe the design basis feed compositions for materials stored or processed by SNF Project facilities and activities. This document is not intended to replace the Hanford Spent Fuel Inventory Baseline (WHC 1994b), but only to supplement it by providing more detail on the chemical and radiological inventories in the fuel (this volume) and sludge. A variety of feed definitions is required to support evaluation of specific facility and process considerations during the development of these new facilities. Six separate feed types have been identified for development of new storage or processing facilities. The approach for using each feed during design evaluations is to calculate the proposed facility flowsheet assuming each feed. The process flowsheet would then provide a basis for material compositions and quantities which are used in follow-on calculations.

  13. Application of evolved gas analysis to cold-cap reactions of melter feeds for nuclear waste vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Kruger, Albert A.; Chun, Jaehun; Hrma, Pavel R.; Rodriguez, Carmen P.; Schweiger, Michael J.

    2014-04-30

    In the vitrification of nuclear wastes, the melter feed (a mixture of nuclear waste and glass-forming and modifying additives) experiences multiple gas-evolving reactions in an electrical glass-melting furnace. We employed the thermogravimetry-gas chromatography-mass spectrometry (TGA-GC-MS) combination to perform evolved gas analysis (EGA). Apart from identifying the gases evolved, we performed quantitative analysis relating the weighed sum of intensities of individual gases linearly proportional with the differential themogravimetry. The proportionality coefficients were obtained by three methods based on the stoichiometry, least squares, and calibration. The linearity was shown to be a good first-order approximation, in spite of the complicated overlapping reactions.

  14. Breathing spiral waves in the chlorine dioxide-iodine-malonic acid reaction-diffusion system

    Science.gov (United States)

    Berenstein, Igal; Muñuzuri, Alberto P.; Yang, Lingfa; Dolnik, Milos; Zhabotinsky, Anatol M.; Epstein, Irving R.

    2008-08-01

    Breathing spiral waves are observed in the oscillatory chlorine dioxide-iodine-malonic acid reaction-diffusion system. The breathing develops within established patterns of multiple spiral waves after the concentration of polyvinyl alcohol in the feeding chamber of a continuously fed, unstirred reactor is increased. The breathing period is determined by the period of bulk oscillations in the feeding chamber. Similar behavior is obtained in the Lengyel-Epstein model of this system, where small amplitude parametric forcing of spiral waves near the spiral wave frequency leads to the formation of breathing spiral waves in which the period of breathing is equal to the period of forcing.

  15. A role for the canonical nuclear factor-κB pathway in coupling neurotrophin-induced differential survival of developing spiral ganglion neurons

    Directory of Open Access Journals (Sweden)

    Renaud eVandenbosch

    2013-11-01

    Full Text Available Neurotrophins are key players of neural development by controlling cell death programs. However, the signaling pathways that mediate their selective responses in different populations of neurons remain unclear. In the mammalian cochlea, sensory neurons differentiate perinatally into type I and type II population both expressing TrkB and TrkC, which bind respectively brain-derived neurotrophic factor (BDNF and neurotrophin-3 (NT3. How these two neuronal populations respond differentially to these two neurotrophins remains unknown. Here, we report in rat the segregation of the NFκB subunit p65 specifically within the type II population postnatally. Using dissociated cultures of embryonic and postnatal spiral ganglion neurons, we observed a specific requirement of NFκB for BDNF- but not NT3-dependent neuronal survival during a particular postnatal time window that corresponds to a period of neuronal cell death and hair cell innervation refinement in the developing cochlea. Consistently, postnatal p65 knockout mice showed a specific decreased number in type II spiral ganglion neurons. Taken together, these results identify NFκB as a type II neuron-specific factor that participates in the selective survival effects of BDNF and NT3 signaling on developing spiral ganglion neurons.

  16. Electromechanics of graphene spirals

    Directory of Open Access Journals (Sweden)

    Topi Korhonen

    2014-12-01

    Full Text Available Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  17. Electromechanics of graphene spirals

    Energy Technology Data Exchange (ETDEWEB)

    Korhonen, Topi; Koskinen, Pekka, E-mail: pekka.koskinen@iki.fi [NanoScience Center, Department of Physics, University of Jyväskylä, 40014 Jyväskylä (Finland)

    2014-12-15

    Among the most fascinating nanostructure morphologies are spirals, hybrids of somewhat obscure topology and dimensionality with technologically attractive properties. Here, we investigate mechanical and electromechanical properties of graphene spirals upon elongation by using density-functional tight-binding, continuum elasticity theory, and classical force field molecular dynamics. It turns out that electronic properties are governed by interlayer interactions as opposed to strain effects. The structural behavior is governed by van der Waals interaction: in its absence spirals unfold with equidistant layer spacings, ripple formation at spiral perimeter, and steadily increasing axial force; in its presence, on the contrary, spirals unfold via smooth local peeling, complex geometries, and nearly constant axial force. These electromechanical trends ought to provide useful guidelines not only for additional theoretical investigations but also for forthcoming experiments on graphene spirals.

  18. Spherical long spirals

    Science.gov (United States)

    Georgiev, G. H.; Dinkova, C. L.

    2013-10-01

    Long spirals in the Euclidean plane have been introduced by A. Kurnosenko five years ago. Using a natural map of the shape sphere into the extended Gaussian plane we study spherical curves that are pre-images of plane long spirals. Loxodromes and spherical spiral antennas are typical examples of such spherical long spirals. The set of all planar spirals leaves invariant under an arbitrary similarity transformation. This set is divided in two disjoint classes by A. Kirnosenko. The first class is consist of the so-called short spirals which are widely used in geometric modeling. The second class of planar long spirals contains well-known logarithmic spiral and Archimedean spirals which have many applications in mathematics, astrophysics and industry. The notion of simplicial shape space is due to D. Kendall. The most popular simplicial shape space of order (2,3) is the set of equivalence classes of similar triangles in the plane. The sphere of radius 1/2 centered at the origin can be considered as a model of this quotient space, so-called the shape sphere. F. Bookstein and J. Lester showed that the one-point extension of the Euclidean plane, so-called the extended Gaussian plane, is another model of the same simplicial shape space. The present paper gives a description of long spirals on the shape sphere by the use a natural conformal mapping between two models. First, we examine long spirals in the extended Gaussian plane. After that, we describe some differential geometric properties of the shape sphere. Finally, we discuss parameterizations of long spirals on the shape sphere.

  19. Design considerations for an archimedean slot spiral antenna

    Science.gov (United States)

    Nurnberger, Michael W.; Volakis, John L.

    1995-01-01

    The design goal is to develop a 118-157 MHz, vertically polarized, low-profile (or conformal) antenna as a replacement for VHF AM blade antennas on aircraft. This design is to be arrived at by scaling the dimensions of an antenna designed for a center frequency of 1.1 GHz. The design prior to scaling may have the following maximum dimensions: diameter less than 3.70 in. and thickness less than 0.50 in. Although a four-arm spiral design was originally suggested, a two-arm spiral may also be used, as both mode-1 and mode-2 (sum and difference) radiation patterns aren't required. While a four-arm spiral can easily be designed should both sum and difference patterns be required, the two-arm design will provide the required sum pattern and simplify the design problem somewhat: only one feed is required, and the feed area geometry is more straightforward. Polarization requirements dictate that a slot spiral be used, as opposed to a wire spiral. Two similar radiating structures were considered. The first is the standard archimedean spiral antenna. The second is a hollow archimedean spiral antenna, essentially a standard archimedean spiral with the inner portion removed.

  20. ALMA observations of feeding and feedback in nearby Seyfert galaxies: an AGN-driven outflow in NGC 1433

    CERN Document Server

    Combes, F; Casasola, V; Hunt, L; Krips, M; Baker, A J; Boone, F; Eckart, A; Marquez, I; Neri, R; Schinnerer, E; Tacconi, L J

    2013-01-01

    We report ALMA observations of CO(3-2) emission in the Seyfert 2 double-barred galaxy NGC1433, at the unprecedented spatial resolution of 0.5"=24 pc. Our aim is to probe AGN feeding and feedback phenomena through the morphology and dynamics of the gas inside the central kpc. The CO map, which covers the whole nuclear region (nuclear bar and ring), reveals a nuclear gaseous spiral structure, inside the nuclear ring encircling the nuclear stellar bar. This gaseous spiral is well correlated with the dusty spiral seen in Hubble Space Telescope images. The nuclear spiral winds up in a pseudo-ring at 200 pc radius, which might correspond to the inner ILR. Continuum emission is detected at 0.87 mm only at the very centre, and its origin is more likely thermal dust emission than non-thermal emission from the AGN. It might correspond to the molecular torus expected to exist in this Seyfert 2 galaxy. The HCN(4-3) and HCO+(4-3) lines were observed simultaneously, but only upper limits are derived, with a ratio to the CO...

  1. NURSING INTERVENTION THROUGH FAMILY PATHNERSHIP INCREASES BEHAVIOR IN PRACTICE OF FEEDING PATTERN ON INFANT OF AGE 6–24 MONTHS FOR NUCLEAR AND EXTENDED FAMILY

    Directory of Open Access Journals (Sweden)

    A. Aziz Alimul Hidayat

    2017-04-01

    Full Text Available Introduction: Nursing intervention is nursing action with a supportive and educative approach done by nurses cooperating with families in overcoming the problems of nursing family. The aim of the research was to explain the effect of nursing intervention through family pathnership toward behavior in practice of feeding pattern on infant of age 6–24 months for nuclear and extended family, including the breastfeeding (ASI, PASI, soft food, family food, snacks, and way of feeding. Method: The design of the research was experimental. The sample of the research was ninety six (96 samples, which was chosen with simple random sampling.The sample was then divided into two parts of family in Kenjeran District and Bulak Surabaya, namely nuclear family and extended family. The variables measured were breastfeeding, PASI, soft food, family food, and a way of feeding through interviewing and observation. The data analysis used was Mann Whitney U. Result: Result showed that effect of nursing interventions on the style of feeding containing of giving PASI (p = 0.003, soft food (p = 0.005, family food (p = 0.00, snacks (p = 0.034, and way of feeding (p = 0.00. Those effects can be shown with the increasing of frequency and way of feeding before and after intervention. Discussion: The conclusion is nursing intervention through the supportive and educative approach as the form of actions on families with problems on the pattern of feeding has the influence on the practice of feeding pattern. The increasing of feeding frequency shows the cognitive and behavioral change on the practice of feeding pattern which can possibly improve the status of infants nutrient.

  2. Application of evolved gas analysis to cold-cap reactions of melter feeds for nuclear waste vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Carmen P. [Pacific Northwest National Laboratory, 902 Battelle Blvd., P.O. Box 999, MSIN K6-24, Richland, WA 99352 (United States); Chun, Jaehun, E-mail: jaehun.chun@pnnl.gov [Pacific Northwest National Laboratory, 902 Battelle Blvd., P.O. Box 999, MSIN K6-24, Richland, WA 99352 (United States); Schweiger, Michael J. [Pacific Northwest National Laboratory, 902 Battelle Blvd., P.O. Box 999, MSIN K6-24, Richland, WA 99352 (United States); Kruger, Albert A. [U.S. Department of Energy Office of River Protection, Richland, WA 99352 (United States); Hrma, Pavel [Pacific Northwest National Laboratory, 902 Battelle Blvd., P.O. Box 999, MSIN K6-24, Richland, WA 99352 (United States); Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang (Korea, Republic of)

    2014-09-20

    Highlights: • We applied the TGA-GC–MS combination to perform EGA of glass batches. • We confirmed the proportionality between mass loss rate and gas evolution intensities. • Proportionality coefficients can be obtained via single-reaction calibration. • Quantitative EGA allows mass loss rates to be matched with evolution rates for gases. • Industrial and waste glass technology can benefit from quantitative EGA. - Abstract: In the vitrification of nuclear wastes, the melter feed (a mixture of nuclear waste and glass-forming and modifying additives) experiences multiple gas-evolving reactions in an electrical glass-melting furnace. We employed the thermogravimetry-gas chromatography–mass spectrometry (TGA-GC–MS) combination to perform evolved gas analysis (EGA). Along with identifying the gases evolved, we performed quantitative analysis relating the weighted sum of intensities of individual gases in linear proportion with the differential thermogravimetry. The proportionality coefficients were obtained by three methods based on the stoichiometry, least squares, and calibration. The linearity was shown to be a good first-order approximation, in spite of the complicated overlapping reactions.

  3. Spiral: a new equipment for exotic nuclei; Spiral: un nouvel equipement pour les noyaux exotiques

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-02-01

    This document presents the GANIL activities and more specially the SPIRAL project. The missions of the GANIL are to allow scientists fundamental researches in Nuclear Physics and to develop applications for heavy ions in other domains. Spiral is an european project, decided by NuPECC (NUclear Physics European Collaboration Committee). It is a first generation equipment allowing the production and the acceleration of light and moderately heavy nuclei at energy range of 2 to 25 MeV/nucleus. (A.L.B.)

  4. Genesis of spiral galaxies

    CERN Document Server

    Kiselev, Valery V

    2013-01-01

    Enigmatic spiral structure of many galaxies and its huge orbital momentum originated due to the capture of lightweight bare black hole by gravity of heavy primordial gas cloud at large impact parameter. The rotating of black hole caused the formation of accretion disc from the cloud and the transfer of orbital momentum to the disc, while during the fall to the center of mass, the spiral trace of black hole in the disc did create the spiral front line of sound waves in the gas, that further evolved into the stellar spiral arms. This mechanism opens the way to study features of spiral galaxy formation, say, an influence and a significance of dark matter in this process.

  5. Superluminous Spiral Galaxies

    CERN Document Server

    Ogle, Patrick M; Nader, Cyril; Helou, George

    2015-01-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L_r=8-14L* (4.3-7.5E44 erg/s). These super spiral galaxies are also giant and massive, with diameter D=57-134 kpc and stellar mass M_stars=0.3-3.4E11 M_sun. We find 53 super spirals out of a complete sample of 1,616 SDSS galaxies with redshift z8L*. The closest example is found at z=0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and WISE colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5-65 M_sun/yr place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers--a possible clue to their formation. We su...

  6. Spiral Countercurrent Chromatography

    Science.gov (United States)

    Ito, Yoichiro; Knight, Martha; Finn, Thomas M.

    2013-01-01

    For many years, high-speed countercurrent chromatography conducted in open tubing coils has been widely used for the separation of natural and synthetic compounds. In this method, the retention of the stationary phase is solely provided by the Archimedean screw effect by rotating the coiled column in the centrifugal force field. However, the system fails to retain enough of the stationary phase for polar solvent systems such as the aqueous–aqueous polymer phase systems. To address this problem, the geometry of the coiled channel was modified to a spiral configuration so that the system could utilize the radially acting centrifugal force. This successfully improved the retention of the stationary phase. Two different types of spiral columns were fabricated: the spiral disk assembly, made by stacking multiple plastic disks with single or four interwoven spiral channels connected in series, and the spiral tube assembly, made by inserting the tetrafluoroethylene tubing into a spiral frame (spiral tube support). The capabilities of these column assemblies were successfully demonstrated by separations of peptides and proteins with polar two-phase solvent systems whose stationary phases had not been well retained in the earlier multilayer coil separation column for high-speed countercurrent chromatography. PMID:23833207

  7. Design of a mixing system for simulated high-level nuclear waste melter feed slurries

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, M.E.; McCarthy, D.; Muhlstein, K.D.

    1986-03-01

    The Nuclear Waste Treatment Program development program consists of coordinated nonradioactive and radioactive testing combined with numerical modeling of the process to provide a complete basis for design and operation of a vitrification facility. The radioactive demonstration tests of equipment and processes are conducted before incorporation in radioactive pilot-scale melter systems for final demonstration. The mixing system evaluation described in this report was conducted as part of the nonradioactive testing. The format of this report follows the sequence in which the design of a large-scale mixing system is determined. The initial program activity was concerned with gaining an understanding of the theoretical foundation of non-Newtonian mixing systems. Section 3 of this report describes the classical rheological models that are used to describe non-Newtonian mixing systems. Since the results obtained here are only valid for the slurries utilized, Section 4, Preparation of Simulated Hanford and West Valley Slurries, describes how the slurries were prepared. The laboratory-scale viscometric and physical property information is summarized in Section 5, Laboratory Rheological Evaluations. The bench-scale mixing evaluations conducted to define the effects of the independent variables described above on the degree of mixing achieved with each slurry are described in Section 6. Bench-scale results are scaled-up to establish engineering design requirements for the full-scale mixing system in Section 7. 24 refs., 37 figs., 44 tabs.

  8. The Spiral of Euroscepticism

    DEFF Research Database (Denmark)

    Galpin, Charlotte; Trenz, Hans-Jörg

    2017-01-01

    of Euroscepticism’, taking media autonomy seriously to understand how media logics and selective devices contribute to the shaping of public discourse about the EU. We review the literature on the media and EU legitimacy to show how media frames and their amplification on social media can account for the salience......Media scholars have increasingly examined the effects of a negativity bias that applies to political news. In the ‘spiral of cynicism’, journalist preferences for negative news correspond to public demands for sensational news. We argue that this spiral of cynicism in EU news results in a ‘spiral...

  9. Galaxy Zoo: Passive Red Spirals

    CERN Document Server

    Masters, Karen L; Romer, A Kathy; Nichol, Robert C; Bamford, Steven P; Schawinski, Kevin; Lintott, Chris J; Andreescu, Dan; Campbell, Heather C; Crowcroft, Ben; Doyle, Isabelle; Edmondson, Edward M; Murray, Phil; Raddick, M Jordan; Slosar, Anze; Szalay, Alexander S; Vandenberg, Jan

    2009-01-01

    We study the spectroscopic properties and environments of red spiral galaxies found by the Galaxy Zoo project. By carefully selecting face-on, disk dominated spirals we construct a sample of truly passive disks (not dust reddened, nor dominated by old stellar populations in a bulge). As such, our red spirals represent an interesting set of possible transition objects between normal blue spirals and red early types. We use SDSS data to investigate the physical processes which could have turned these objects red without disturbing their morphology. Red spirals prefer intermediate density regimes, however there are no obvious correlations between red spiral properties and environment - environment alone is not sufficient to determine if a galaxy will become a red spiral. Red spirals are a small fraction of spirals at low masses, but dominate at large stellar masses - massive galaxies are red independent of morphology. We confirm that red spirals have older stellar populations and less recent star formation than ...

  10. Early non-destructive biofouling detection in spiral wound RO Membranes using a mobile earth's field NMR

    KAUST Repository

    Fridjonsson, E.O.

    2015-04-20

    We demonstrate the use of Earth\\'s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (signal relaxation parameters T1, T2 and the total NMR signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  11. SUPERLUMINOUS SPIRAL GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Ogle, Patrick M.; Lanz, Lauranne; Nader, Cyril; Helou, George, E-mail: ogle@ipac.caltech.edu [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States)

    2016-02-01

    We report the discovery of spiral galaxies that are as optically luminous as elliptical brightest cluster galaxies, with r-band monochromatic luminosity L{sub r} = 8–14L* (4.3–7.5 × 10{sup 44} erg s{sup −1}). These super spiral galaxies are also giant and massive, with diameter D = 57–134 kpc and stellar mass M{sub stars} = 0.3–3.4 × 10{sup 11}M{sub ⊙}. We find 53 super spirals out of a complete sample of 1616 SDSS galaxies with redshift z < 0.3 and L{sub r} > 8L*. The closest example is found at z = 0.089. We use existing photometry to estimate their stellar masses and star formation rates (SFRs). The SDSS and Wide-field Infrared Survey Explorer colors are consistent with normal star-forming spirals on the blue sequence. However, the extreme masses and rapid SFRs of 5–65 M{sub ⊙} yr{sup −1} place super spirals in a sparsely populated region of parameter space, above the star-forming main sequence of disk galaxies. Super spirals occupy a diverse range of environments, from isolation to cluster centers. We find four super spiral galaxy systems that are late-stage major mergers—a possible clue to their formation. We suggest that super spirals are a remnant population of unquenched, massive disk galaxies. They may eventually become massive lenticular galaxies after they are cut off from their gas supply and their disks fade.

  12. Spiral 2 Week

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The main goal of this meeting is to present and discuss the current status of the Spiral-2 project at GANIL in front of a large community of scientists and engineers. Different issues have been tackled particularly the equipment around Spiral-2 like injectors, cryo-modules or beam diagnostics, a workshop was devoted to other facilities dedicated to radioactive ion beam production. This document gathers only the slides of the presentations.

  13. Spiral Shell Collection

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    In 1988 Zheng Haigen, a seaman with the Towboat Company of the Shanghai Salvage Bureau, began collecting spiral shells. Today he has more than 600 in his collection. The most valuable are the rare parrot shell and a shell whose spirals wind counter-clockwise. In 1991 a miniature conch with a diameter of 0.31 millimeters that he found buried in tons of sand made the Guinness Book of World Records.

  14. Spiral 2 the scientific objectives

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-06-15

    The French ministry of research took the decision to build Spiral-2 in May 2005. Its construction costs are estimated to 130 million euros while its operating costs will near 8.5 million euros per year. The construction works will last 5 years. The Spiral-2 facility is based on a high power, superconducting driver Linac, which will deliver a high intensity, 40 MeV deuteron beam as well as a variety of heavy-ion beams with mass over charge ratio equal to 3 and energy up to 14.5 MeV/nucleon. Using a carbon converter, fast neutrons from the breakup of the 5 mA of deuterons impinging on a uranium carbide target will induce a rate of up to 10{sup 14} fissions/s. The radioactive ion beam intensities in the mass range from A = 60 to 140 will be of the order of 10{sup 6} to 10{sup 11} particles/s surpassing by one or two orders-of-magnitude any existing facility in the world. A direct irradiation of the UC{sub 2} target with {sup 3,4}He, {sup 6,7}Li or {sup 12}C may also be used. Different production targets will be used to produce high-intensity beams of light radioactive species with the Isol technique. The extracted radioactive ion beam will be accelerated to energies up to 20 MeV/nucleons by the existing Cime cyclotron. One of the most important features of the future Ganil accelerator complex will be the capability of delivering up to 5 stable or radioactive beams simultaneously in the energy range from the keV to several tens of MeV/nucleons. The document details also the future contribution of Spiral-2 concerning the structure of exotic nuclei, the thermodynamical aspects of nuclear matter, nucleosynthesis, the fundamental basic interactions, and the use of neutrons. (A.C.)

  15. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas; Arkansas Galaxy Evolution Survey

    2017-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code’s results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality’s error bars overlapped 2DFFT’s error bars for 26 of the 30 galaxies. The two methods’ agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies’ spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. We also analyze apparent spiral structure of three galaxies beyond z=2. The Spirality code package also includes GenSpiral, which produces FITS images of synthetic spirals, and SpiralArmCount, which uses a one-dimensional Fast Fourier Transform to count the spiral arms of a galaxy after its pitch is determined.

  16. Investigating Dwarf Spiral Galaxies

    Science.gov (United States)

    Weerasooriya, Sachithra; Dunn, Jacqueline M.

    2017-01-01

    Several studies have proposed that dwarf elliptical / spheroidal galaxies form through the transformation of dwarf irregular galaxies. Early and late type dwarfs resemble each other in terms of their observed colors and light distributions (each can often be represented by exponential disks), providing reason to propose an evolutionary link between the two types. The existence of dwarf spirals has been largely debated. However, more and more recent studies are using the designation of dwarf spiral to describe their targets of interest. This project seeks to explore where dwarf spirals fit into the above mentioned evolutionary sequence, if at all. Optical colors will be compared between a sample of dwarf irregular, dwarf elliptical, and dwarf spiral galaxies. The dwarf irregular and dwarf elliptical samples have previously been found to overlap in both optical color and surface brightness profile shape when limiting the samples to their fainter members. A preliminary comparison including the dwarf spiral sample will be presented here, along with a comparison of available ultraviolet and near-infrared data. Initial results indicate a potential evolutionary link that merits further investigation.

  17. Embracing the Spiral

    Directory of Open Access Journals (Sweden)

    Li Mao

    2016-12-01

    Full Text Available Critical research demands that we interrogate our own positionality and social location. Critical reflexivity is a form of researcher critical consciousness that is constant and dynamic in a complex spiral-like process starting within our own experiences as racialized, gendered, and classed beings embedded in particular sociopolitical contexts. Across diverse critical methodologies, a group of graduate students and their supervisor explored their own conceptualization of the reflexivity spiral by reflecting on how their research motivations and methodologies emerged from their racializing, colonizing, language-learning, parenting, and identity negotiating experiences. In this article, they present a spiral model of the critical reflexivity process, review the literature on reflexivity, and conclude with a description of critical reflexivity as a social practice within a supportive and collaborative graduate school experience.

  18. Plasmonic response of nanoscale spirals.

    Science.gov (United States)

    Ziegler, Jed I; Haglund, Richard F

    2010-08-11

    The Archimedean spiral geometry presents a platform for exploration of complex plasmonic mechanisms and applications. Here we show both through simulations and experiment that more complex plasmonic modes with unique near-field structure and larger mode volumes can be realized within a single, topologically robust structure. In the spiral, complex polarization response, resonant interactions and symmetry-breaking features are defined by the width and spacing of the spiral tracks and by the winding number of the spiral.

  19. Galactic Spiral Structure

    CERN Document Server

    Francis, Charles

    2009-01-01

    We describe the structure and composition of six major stellar streams in a population of 20 574 local stars in the New Hipparcos Reduction with known radial velocities. We find that, once fast moving stars are excluded, almost all stars belong to one of these streams. The results of our investigation have lead us to re-examine the hydrogen maps of the Milky Way, from which we identify the possibility of a symmetric two-armed spiral with half the conventionally accepted pitch angle. We describe a model of spiral arm motions which matches the observed velocities and composition of the six major streams, as well as the observed velocities of the Hyades and Praesepe clusters at the extreme of the Hyades stream. Stellar orbits are perturbed ellipses aligned at a focus in coordinates rotating at the rate of precession of pericentre. Stars join a spiral arm just before apocentre, follow the arm for more than half an orbit, and leave the arm soon after pericentre. Spiral pattern speed equals the mean rate of precess...

  20. Ferroelectricity in spiral magnets

    NARCIS (Netherlands)

    Mostovoy, M

    2006-01-01

    It was recently observed that the ferroelectrics showing the strongest sensitivity to an applied magnetic field are spiral magnets. We present a phenomenological theory of inhomogeneous ferroelectric magnets, which describes their thermodynamics and magnetic field behavior, e.g., dielectric suscepti

  1. Noise reduction of spiral ducts.

    Science.gov (United States)

    Lapka, Wojciech; Cempel, Czesław

    2007-01-01

    The paper presents noise reduction (NR) of spiral ducts as a result of computational modeling of acoustic wave propagation. Three-dimensional models were created with the finite element method in COMSOL Multiphysics version 3.3. Nine models of spiral ducts with 1-9 spiral leads were considered. Time-harmonic analysis was used to predict NR, which was shown in spectral and interval frequency bands. Spiral duct performance can be seen as a comparison of NR before and after a change from a circular to a spiral duct.

  2. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  3. Tracking Target and Spiral Waves

    DEFF Research Database (Denmark)

    Jensen, Flemming G.; Sporring, Jon; Nielsen, Mads;

    2002-01-01

    A new algorithm for analyzing the evolution of patterns of spiral and target waves in large aspect ratio chemical systems is introduced. The algorithm does not depend on finding the spiral tip but locates the center of the pattern by a new concept, called the spiral focus, which is defined...... by the evolutes of the actual spiral or target wave. With the use of Gaussian smoothing, a robust method is developed that permits the identification of targets and spirals foci independently of the wave profile. Examples of an analysis of long image sequences from experiments with the Belousov...

  4. Forming Spirals From Shadows

    Science.gov (United States)

    Kohler, Susanna

    2016-07-01

    What causes the large-scale spiral structures found in some protoplanetary disks? Most models assume theyre created by newly-forming planets, but a new study suggests that planets might have nothing to do with it.Perturbations from Planets?In some transition disks protoplanetary disks with gaps in their inner regions weve directly imaged large-scale spiral arms. Many theories currently attribute the formation of these structures to young planets: either the direct perturbations of a planet embedded in the disk cause the spirals, or theyre indirectly caused by the orbit of a planetary body outside of the arms.Another example of spiral arms detected in a protoplanetary disk, MWC 758. [NASA/ESA/ESO/M. Benisty et al.]But what if you could get spirals without any planets? A team of scientists led by Matas Montesinos (University of Chile) have recently published a study in which they examine what happens to a shadowed protoplanetary disk.Casting Shadows with WarpsIn the teams setup, they envision a protoplanetary disk that is warped: the inner region is slightly tilted relative to the outer region. As the central star casts light out over its protoplanetary disk, this disk warping would cause some regions of the disk to be shaded in a way that isnt axially symmetric with potentially interesting implications.Montesinos and collaborators ran 2D hydrodynamics simulations to determine what happens to the motion of particles within the disk when they pass in and out of the shadowed regions. Since the shadowed regions are significantly colder than the illuminated disk, the pressure in these regions is much lower. Particles are therefore accelerated and decelerated as they pass through these regions, and the lack of axial symmetry causes spiral density waves to form in the disk as a result.Initial profile for the stellar heating rate per unit area for one of the authors simulations. The regions shadowed as a result of the disk warp subtend 0.5 radians each (shown on the left

  5. Interactive Effects of Dietary Lipid and Phenotypic Feed Efficiency on the Expression of Nuclear and Mitochondrial Genes Involved in the Mitochondrial Electron Transport Chain in Rainbow Trout

    Directory of Open Access Journals (Sweden)

    Jonathan C. Eya

    2015-04-01

    Full Text Available A 2 × 3 factorial study was conducted to evaluate the effects of dietary lipid level on the expression of mitochondrial and nuclear genes involved in electron transport chain in all-female rainbow trout Oncorhynchus mykiss. Three practical diets with a fixed crude protein content of 40%, formulated to contain 10% (40/10, 20% (40/20 and 30% (40/30 dietary lipid, were fed to apparent satiety to triplicate groups of either low-feed efficient (F120; 217.66 ± 2.24 g initial average mass or high-feed efficient (F136; 205.47 ± 1.27 g full-sib families of fish, twice per day, for 90 days. At the end of the experiment, the results showed that there is an interactive effect of the dietary lipid levels and the phenotypic feed efficiency (growth rate and feed efficiency on the expression of the mitochondrial genes nd1 (NADH dehydrogenase subunit 1, cytb (Cytochrome b, cox1 (Cytochrome c oxidase subunits 1, cox2 (Cytochrome c oxidase subunits 2 and atp6 (ATP synthase subunit 6 and nuclear genes ucp2α (uncoupling proteins 2 alpha, ucp2β (uncoupling proteins 2 beta, pparα (peroxisome proliferator-activated receptor alpha, pparβ (peroxisome proliferatoractivated receptor beta and ppargc1α (proliferator-activated receptor gamma coactivator 1 alpha in fish liver, intestine and muscle, except on ppargc1α in the muscle which was affected by the diet and the family separately. Also, the results revealed that the expression of mitochondrial genes is associated with that of nuclear genes involved in electron transport chain in fish liver, intestine and muscle. Furthermore, this work showed that the expression of mitochondrial genes parallels with the expression of genes encoding uncoupling proteins (UCP in the liver and the intestine of rainbow trout. This study for the first time presents the molecular basis of the effects of dietary lipid level on mitochondrial and nuclear genes involved in mitochondrial electron transport chain in fish.

  6. Spiral 2 workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The accelerator and experimental facilities at GANIL will be transformed over the next 5-10 years. The centerpiece of the additions to the accelerator complex will be Spiral-2. This is the first phase of a new radioactive beam facility based on the ISOL principle. The main aim of Spiral-2 will be to produce intense, high quality beams of neutron-rich nuclei created in neutron-induced fission of heavy elements and accelerated by the existing CIME cyclotron. The principal aims of this workshop will be a) to publicize the new facilities, b) to discuss and define the science which might be carried out with them, c) to discuss the instrumentation and infrastructure required to exploit the new facilities and d) to help form collaborations of scientists wishing to design and construct the equipment needed to undertake the science programme. This document gathers most of the slides presented in the workshop.

  7. Spiral multicapillary columns

    Science.gov (United States)

    Efimenko, A. P.; Naumenko, I. I.; Soboleva, V. K.

    2008-08-01

    It was shown in a theoretical study and confirmed by experiment that a spiral multicapillary column had maximum efficiency if the bunch of capillaries was additionally coiled around its longitudinal axis to produce an integral number of coils. This technique made it possible to manufacture gas-chromatographic columns with performance as high as 12 to 16 thousand theoretical plates. These columns can find various applications, especially if quick separation is required.

  8. Interweaving Chiral Spirals

    CERN Document Server

    Kojo, Toru; Fukushima, Kenji; McLerran, Larry; Pisarski, Robert D

    2011-01-01

    We elaborate how to construct the interweaving chiral spirals in (2+1) dimensions, that is defined as a superposition of differently oriented chiral spirals. We divide the two-dimensional Fermi sea into distinct wedges characterized by the opening angle 2 Theta and the depth Q \\simeq pF, where pF is the Fermi momentum. Each wedge earns an energy gain by forming a single chiral spiral. The optimal values for Theta and Q are chosen by the balance between this energy gain and the energy costs from the deformed Fermi surface (dominant at large Theta) and patch-patch interactions (dominant at small Theta). We estimate these energy gains and costs by means of the expansions in terms of 1/Nc, Lambda_QCD/Q, and Theta using a non-local four-Fermi interaction model: At small 1/Nc the mass gap (chiral condensate) is large enough and the interaction among quarks and the condensate is local in momentum space thanks to the form factor in our non-local model. The fact that patch-patch interactions lie only near the patch bo...

  9. Satellites of spiral galaxies

    Science.gov (United States)

    Zaritsky, Dennis; Smith, Rodney; Frenk, Carlos; White, Simon D. M.

    1993-01-01

    We present a survey of satellites around a homogeneous set of late-type spirals with luminosity similar to that of the Milky Way. On average, we find fewer than 1.5 satellites per primary, but we argue that we can treat the survey as an ensemble and so derive the properties of the halo of a 'typical' isolated spiral. The projected density profile of the ensemble falls off approximately as 1/r. Within 50 kpc the azimuthal distribution of satellites shows some evidence for the 'Holmberg effect', an excess near the minor axis of the primary; however, at larger projected distances, the distribution appears isotropic. There is a weak but significant correlation between the size of a satellite and its distance from its primary, as expected if satellites are tidally truncated. Neither Hubble type nor spectral characteristics correlate with apparent separation. The ensemble of satellites appears to be rotating at about 30 km/s in the same direction as the galactic disk. Satellites on prograde orbits tend to be brighter than those on retrograde orbits. The typical velocity difference between a satellite and its primary shows no clear dependence either on apparent separation, or on the rotation speed of the primary. Thus our survey demonstrates that isolated spiral galaxies have massive halos that extend to many optical radii.

  10. Spirality: A Noval Way to Measure Spiral Arm Pitch Angle

    Science.gov (United States)

    Shields, Douglas W.; Boe, Benjamin; Henderson, Casey L.; Hartley, Matthew; Davis, Benjamin L.; Pour Imani, Hamed; Kennefick, Daniel; Kennefick, Julia D.

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. For a given pitch angle template, the mean pixel value is found along each of typically 1000 spiral axes. The fitting function, which shows a local maximum at the best-fit pitch angle, is the variance of these means. Error bars are found by varying the inner radius of the measurement annulus and finding the standard deviation of the best-fit pitches. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 128 synthetic spiral images of known pitch. These spirals varied in the number of spiral arms, pitch angle, degree of logarithmicity, radius, SNR, inclination angle, bar length, and bulge radius. A correct result is defined as a result that matches the true pitch within the error bars, with error bars no greater than ±7°. For the non-logarithmic spiral sample, the correct answer is similarly defined, with the mean pitch as function of radius in place of the true pitch. For all synthetic spirals, correct results were obtained so long as SNR > 0.25, the bar length was no more than 60% of the spiral's diameter (when the bar was included in the measurement), the input center of the spiral was no more than 6% of the spiral radius away from the true center, and the inclination angle was no more than 30°. The synthetic spirals were not deprojected prior to measurement. The code produced the correct result for all barred spirals when the measurement annulus was placed outside the bar. Additionally, we compared the code's results against 2DFFT results for 203 visually selected spiral galaxies in GOODS North and South. Among the entire sample, Spirality's error bars overlapped 2DFFT's error bars 64% of the time. For those galaxies in which Source code is available by email request from the primary author.

  11. Spirality: A Novel Way to Measure Spiral Arm Pitch Angle

    CERN Document Server

    Shields, Douglas W; Pfountz, Casey; Davis, Benjamin L; Hartley, Matthew; Imani, Hamed Pour; Slade, Zac; Kennefick, Daniel; Kennefick, Julia

    2015-01-01

    We present the MATLAB code Spirality, a novel method for measuring spiral arm pitch angles by fitting galaxy images to spiral templates of known pitch. Computation time is typically on the order of 2 minutes per galaxy, assuming at least 8 GB of working memory. We tested the code using 117 synthetic spiral images with known pitches, varying both the spiral properties and the input parameters. The code yielded correct results for all synthetic spirals with galaxy-like properties. We also compared the code's results to two-dimensional Fast Fourier Transform (2DFFT) measurements for the sample of nearby galaxies defined by DMS PPak. Spirality's error bars overlapped 2DFFT's error bars for 26 of the 30 galaxies. The two methods' agreement correlates strongly with galaxy radius in pixels and also with i-band magnitude, but not with redshift, a result that is consistent with at least some galaxies' spiral structure being fully formed by z=1.2, beyond which there are few galaxies in our sample. The Spirality code pa...

  12. Intermittency in spiral Poiseuille flow

    Energy Technology Data Exchange (ETDEWEB)

    Heise, M; Abshagen, J; Menck, A; Pflster, G [Institute of Experimental and Applied Physics, University of Kiel, 24098 Kiel (Germany)

    2005-01-01

    The results of an experimental study on intermittent spiral vortices observed in a counter-rotating Taylor-Couette system with an additional axial through flow, i.e. Spiral-Poiseuille flow, are presented. Convectively unstable upstream propagating spiral vortices appear in the laminar basic flow from an oscillatory instability and in general become absolutely unstable at higher inner cylinder Reynolds number. It is found that at Reynolds numbers above the absolute stability border the spiral vortices become unstable and a complex flow state showing intermittent bursts appears. The intermittent flow state is characterised by an irregular alternation between clearly distinguishable 'laminar' phases corresponding to up-and downstream propagating spiral vortices as well as propagating Taylor vortices. For a sufficiently high rate of axial through flow it is found that intermittency can occur directly from the convectively unstable regime of the upstream propagating spiral vortices.

  13. Star Formation in Spiral Arms

    CERN Document Server

    Elmegreen, Bruce G

    2011-01-01

    The origin and types of spiral arms are reviewed with an emphasis on the connections between these arms and star formation. Flocculent spiral arms are most likely the result of transient instabilities in the gas that promote dense cloud formation, star formation, and generate turbulence. Long irregular spiral arms are usually initiated by gravitational instabilities in the stars, with the gas contributing to and following these instabilities, and star formation in the gas. Global spiral arms triggered by global perturbations, such as a galaxy interaction, can be wavemodes with wave reflection in the inner regions. They might grow and dominate the disk for several rotations before degenerating into higher-order modes by non-linear effects. Interstellar gas flows through these global arms, and through the more transient stellar spiral arms as well, where it can reach a high density and low shear, thereby promoting self-gravitational instabilities. The result is the formation of giant spiral arm cloud complexes,...

  14. Effects of Dielectric Substrates and Ground Planes on Resonance Frequency of Archimedean Spirals.

    Science.gov (United States)

    Hooker, Jerris W; Ramaswamy, Vijaykumar; Arora, Rajendra K; Edison, Arthur S; Brey, William W

    2016-04-01

    Superconducting self-resonant spiral structures are of current interest for applications both in metamaterials and as probe coils for nuclear magnetic resonance (NMR) spectroscopy for high-sensitivity chemical analysis. Accurate spiral models are available in the literature for behavior of a spiral below and up to self-resonance. However, knowledge of the higher modes is also important. We present the relationships between the spiral parameters and the multiple mode frequencies of single sided spirals on dielectric substrates as modeled by method of moments simulation. In the absence of a ground plane, we find that the mode frequency has a linear though not necessarily harmonic dependence on the mode number. The effect of a thick substrate can be approximated by an effective dielectric constant. But when the thickness is less than 20% of the spiral trace width (router - rinner) this approximation is no longer accurate. We have developed a simple empirical formula to predict the higher modes.

  15. Formation of Nuclear Spirals in Barred Galaxies

    CERN Document Server

    Ann, H B; Thakur, Parijat

    2004-01-01

    We have performed smoothed particle hydrodynamics (SPH) simulations for the response of the gaseous disk to the imposed moderately strong non-axisymmetric potentials. The model galaxies are composed of the three stellar components (disk, bulge and bar) and two dark ones (supermassive black hole and halo) whose gravitational potentials are assumed to be invariant in time in the frame corotating with the bar. We found that the torques alone generated by the moderately strong bar that gives the maximum of tangential-to-radial force ratio as $(F_{Tan}/F_{Rad})_{max}= 0.3$ are not sufficient to drive the gas particles close to the center due to the barrier imposed by the inner Lindblad resonances (ILRs). In order to transport the gas particles towards the nucleus ($r<100$ pc), a central supermassive black hole (SMBH) and high sound speed of the gas are required to be present. The former is required to remove the inner inner Lindblad resonance (IILR) that prevents gas inflow close to the nucleus, while the latte...

  16. Galaxy Zoo: Dust in Spirals

    CERN Document Server

    Masters, Karen L; Bamford, Steven; Mosleh, Moein; Lintott, Chris J; Andreescu, Dan; Edmondson, Edward M; Keel, William C; Murray, Phil; Raddick, M Jordan; Schawinski, Kevin; Slosar, Anze; Szalay, Alexander S; Thomas, Daniel; Vandenberg, Jan

    2010-01-01

    We investigate the effect of dust on spiral galaxies by measuring the inclination-dependence of optical colours for 24,276 well-resolved SDSS galaxies visually classified in Galaxy Zoo. We find clear trends of reddening with inclination which imply a total extinction from face-on to edge-on of 0.7, 0.6, 0.5 and 0.4 magnitudes for the ugri passbands. We split the sample into "bulgy" (early-type) and "disky" (late-type) spirals using the SDSS fracdeV (or f_DeV) parameter and show that the average face-on colour of "bulgy" spirals is redder than the average edge-on colour of "disky" spirals. This shows that the observed optical colour of a spiral galaxy is determined almost equally by the spiral type (via the bulge-disk ratio and stellar populations), and reddening due to dust. We find that both luminosity and spiral type affect the total amount of extinction, with "disky" spirals at M_r ~ -21.5 mags having the most reddening. This decrease of reddening for the most luminous spirals has not been observed before ...

  17. Spiral Microstrip Antenna with Resistance

    Science.gov (United States)

    Shively, David G. (Inventor)

    1998-01-01

    A spiral microstrip antenna having resistor elements embedded in each of the spiral arms is provided. The antenna is constructed using a conductive back plane as a base. The back plane supports a dielectric slab having a thickness between one-sixteenth and one-quarter of an inch. A square spiral, having either two or four arms, is attached to the dielectric slab. Each arm of the spiral has resistor elements thereby dissipating an excess energy not already emitted through radiation. The entire configuration provides a thin, flat, high gain, wide bandwidth antenna which requires no underlying cavity. The configuration allows the antenna to be mounted conformably on an aircraft surface.

  18. Rebuilding Spiral Galaxies

    Science.gov (United States)

    2005-01-01

    Major Observing Programme Leads to New Theory of Galaxy Formation Summary Most present-day large galaxies are spirals, presenting a disc surrounding a central bulge. Famous examples are our own Milky Way or the Andromeda Galaxy. When and how did these spiral galaxies form? Why do a great majority of them present a massive central bulge? An international team of astronomers [1] presents new convincing answers to these fundamental questions. For this, they rely on an extensive dataset of observations of galaxies taken with several space- and ground-based telescopes. In particular, they used over a two-year period, several instruments on ESO's Very Large Telescope. Among others, their observations reveal that roughly half of the present-day stars were formed in the period between 8,000 million and 4,000 million years ago, mostly in episodic burst of intense star formation occurring in Luminous Infrared Galaxies. From this and other evidence, the astronomers devised an innovative scenario, dubbed the "spiral rebuilding". They claim that most present-day spiral galaxies are the results of one or several merger events. If confirmed, this new scenario could revolutionise the way astronomers think galaxies formed. PR Photo 02a/05: Luminosity - Oxygen Abundance Relation for Galaxies (VLT) PR Photo 02b/05: The Spiral Rebuilding Scenario A fleet of instruments How and when did galaxies form? How and when did stars form in these island universes? These questions are still posing a considerable challenge to present-day astronomers. Front-line observational results obtained with a fleet of ground- and space-based telescopes by an international team of astronomers [1] provide new insights into these fundamental issues. For this, they embarked on an ambitious long-term study at various wavelengths of 195 galaxies with a redshift [2] greater than 0.4, i.e. located more than 4000 million light-years away. These galaxies were studied using ESO's Very Large Telescope, as well as the

  19. A Twin Spiral Planar Antenna for UWB Medical Radars

    Directory of Open Access Journals (Sweden)

    Giuseppe A. Zito

    2013-01-01

    Full Text Available A planar-spiral antenna to be used in an ultrawideband (UWB radar system for heart activity monitoring is presented. The antenna, named “twin,” is constituted by two spiral dipoles in a compact structure. The reflection coefficient at the feed point of the dipoles is lower than −8 dB over the 3–12 GHz band, while the two-dipoles coupling is about −20 dB. The radiated beam is perpendicular to the plane of the spiral, so the antenna is wearable and it may be an optimal radiator for a medical UWB radar for heart rate detection. The designed antenna has been also used to check some hypotheses about the UWB radar heart activity detection mechanism. The radiation impedance variation, caused by the thorax vibrations associated with heart activity, seems to be the most likely explanation of the UWB radar operation.

  20. Quarkyonic Chiral Spirals

    CERN Document Server

    Kojo, Toru; McLerran, Larry; Pisarski, Robert D

    2009-01-01

    We consider the formation of chiral density waves in Quarkyonic matter, which is a phase where cold, dense quarks experience confining forces. We model confinement following Gribov and Zwanziger, taking the gluon propagator, in Coulomb gauge and momentum space, as 1/(p^2)^2. We assume that the number of colors, N, is large, and that the quark chemical potential, mu, is much larger than renormalization mass scale, Lambda_QCD. To leading order in 1/N and Lambda_QCD, a gauge theory with Nf flavors of massless quarks in 3+1 dimensions naturally reduces to a gauge theory in 1+1 dimensions, with an enlarged flavor symmetry of SU(2Nf). Through an anomalous chiral rotation, in two dimensions a Fermi sea of massless quarks maps directly onto the corresponding theory in vacuum. A chiral condensate forms locally, and varies with the spatial position, z, as . Following Schon and Thies, we term this two dimensional pion condensate a (Quarkyonic) chiral spiral. Massive quarks also exhibit chiral spirals, with the magnitude...

  1. The perfect shape spiral stories

    CERN Document Server

    Hammer, Øyvind

    2016-01-01

    This book uses the spiral shape as a key to a multitude of strange and seemingly disparate stories about art, nature, science, mathematics, and the human endeavour. In a way, the book is itself organized as a spiral, with almost disconnected chapters circling around and closing in on the common theme. A particular strength of the book is its extremely cross-disciplinary nature - everything is fun, and everything is connected! At the same time, the author puts great emphasis on mathematical and scientific correctness, in contrast, perhaps, with some earlier books on spirals. Subjects include the mathematical properties of spirals, sea shells, sun flowers, Greek architecture, air ships, the history of mathematics, spiral galaxies, the anatomy of the human hand, the art of prehistoric Europe, Alfred Hitchcock, and spider webs, to name a few.

  2. A Mock UF6 Feed and Withdrawal System for Testing Safeguards Monitoring Systems and Strategies Intended for Nuclear Fuel Enrichment and Processing Plants

    Energy Technology Data Exchange (ETDEWEB)

    Krichinsky, Alan M [ORNL; Bates, Bruce E [ORNL; Chesser, Joel B [ORNL; Koo, Sinsze [ORNL; Whitaker, J Michael [ORNL

    2009-12-01

    This report describes an engineering-scale, mock UF6 feed and withdrawal (F&W) system, its operation, and its intended uses. This system has been assembled to provide a test bed for evaluating and demonstrating new methodologies that can be used in remote, unattended, continuous monitoring of nuclear material process operations. These measures are being investigated to provide independent inspectors improved assurance that operations are being conducted within declared parameters, and to increase the overall effectiveness of safeguarding nuclear material. Testing applicable technologies on a mock F&W system, which uses water as a surrogate for UF6, enables thorough and cost-effective investigation of hardware, software, and operational strategies before their direct installation in an industrial nuclear material processing environment. Electronic scales used for continuous load-cell monitoring also are described as part of the basic mock F&W system description. Continuous monitoring components on the mock F&W system are linked to a data aggregation computer by a local network, which also is depicted. Data collection and storage systems are described only briefly in this report. The mock UF{sub 6} F&W system is economical to operate. It uses a simple process involving only a surge tank between feed tanks and product and withdrawal (or waste) tanks. The system uses water as the transfer fluid, thereby avoiding the use of hazardous UF{sub 6}. The system is not tethered to an operating industrial process involving nuclear materials, thereby allowing scenarios (e.g., material diversion) that cannot be conducted otherwise. These features facilitate conducting experiments that yield meaningful results with a minimum of expenditure and quick turnaround time. Technologies demonstrated on the engineering-scale system lead to field trials (described briefly in this report) for determining implementation issues and performance of the monitoring technologies under plant

  3. Spiral vane bioreactor

    Science.gov (United States)

    Morrison, Dennis R. (Inventor)

    1991-01-01

    A spiral vane bioreactor of a perfusion type is described in which a vertical chamber, intended for use in a microgravity condition, has a central rotating filter assembly and has flexible membranes disposed to rotate annularly about the filter assembly. The flexible members have end portions disposed angularly with respect to one another. A fluid replenishment medium is input from a closed loop liquid system to a completely liquid filled chamber containing microcarrier beads, cells and a fluid medium. Output of spent medium is to the closed loop. In the closed loop, the output and input parameters are sensed by sensors. A manifold permits recharging of the nutrients and pH adjustment. Oxygen is supplied and carbon dioxide and bubbles are removed and the system is monitored and controlled by a microprocessor.

  4. Reflections on love's spirals.

    Science.gov (United States)

    Kenny, Gerard

    2011-06-01

    This article seeks to explore how the experience of love and its expression might inform and guide reflection and inquiry into love. Despite the importance of love in our personal and professional lives, it remains a topic that has further scope for inquiry within nursing circles. The article takes as its catalyst an encounter that emerged out of a piece of research that was exploring individuals' experiences of becoming healers and the journey they undertook. One participant spoke deeply and profoundly of his experience of love, which generated for me a personal, experiential, and intellectual process of inquiry. The article seeks to try and create a synthesis between rational inquiry and subjective experience. It explores W. B. Yeats's notion of a gyre, a spiral, as an image and metaphor for integrating different conceptions and understandings of love. It seeks to illustrate how a more integrated understanding of love may open up spaces of inquiry that are more flexible, creative, and spontaneous.

  5. Spiral microfluidic nanoparticle separators

    Science.gov (United States)

    Bhagat, Ali Asgar S.; Kuntaegowdanahalli, Sathyakumar S.; Dionysiou, Dionysios D.; Papautsky, Ian

    2008-02-01

    Nanoparticles have potential applications in many areas such as consumer products, health care, electronics, energy and other industries. As the use of nanoparticles in manufacturing increases, we anticipate a growing need to detect and measure particles of nanometer scale dimensions in fluids to control emissions of possible toxic nanoparticles. At present most particle separation techniques are based on membrane assisted filtering schemes. Unfortunately their efficiency is limited by the membrane pore size, making them inefficient for separating a wide range of sizes. In this paper, we propose a passive spiral microfluidic geometry for momentum-based particle separations. The proposed design is versatile and is capable of separating particulate mixtures over a wide dynamic range and we expect it will enable a variety of environmental, medical, or manufacturing applications that involve rapid separation of nanoparticles in real-world samples with a wide range of particle components.

  6. The scientific objectives of the SPIRAL 2 Project

    Energy Technology Data Exchange (ETDEWEB)

    Ackermann, D.; Adoui, L.; Angelis, G. de [GANIL, Grand Accelerateur National d' Ions Lourds, BP 55027, 14076 Caen cedex 5 (France)] (and others)

    2006-06-15

    The construction of SPIRAL 2 at GANIL will open completely new possibilities for parallel beam operation of the whole facility. The whole GANIL/SPIRAL/SPIRAL2 accelerator complex will allow for the simultaneous use of up to 5 different radioactive and stable beams. Several combinations of different beams delivered in parallel for experiments at low (keV/u), medium (few MeV/u) and high (up to 100 MeV/u) energies will be possible. Presently the GANIL/SPIRAL facility delivers about 60 weeks per year of stable and radioactive beams (up to 3 simultaneous beams). Thanks to SPIRAL 2 and the construction of a new beam line connecting the CIME cyclotron and the G1 and G2 experimental rooms the available beam time for experiments may be extended up to about 120 (up to 5 simultaneous beams) weeks per year. The chapters which follow a general introduction deal with the detailed questions to be addressed by experiments with the beams from SPIRAL2. In chapter 2 the many unanswered questions related to the structure of exotic nuclei are posed and the role of SPIRAL2 in answering them outlined. Chapter 3 deals with the dynamics and thermodynamics of asymmetric nuclear systems. Chapter 4 is concerned with questions of nuclear astrophysics which are intimately related to the properties of exotic nuclei. Chapter 5 indicates how the atomic nucleus can act as a laboratory for tests of the Standard model of Particle Physics and Chapter 6 shows how the production of intense fluxes of neutrons at SPIRAL2 make it an excellent tool to address both questions related to damage in materials of importance in nuclear installations and to the s- and r-processes of nucleosynthesis. In chapter 7 we turn to the application, of the radioactive beams from SPIRAL2 and the radionuclides produced by it, to study condensed matter and radiobiology. Finally in the eight and last chapter the reader can find an account of the historical development of the SPIRAL2 facility and this is followed by an outline of

  7. Entoptic perceptions of spiral waves and rare inward spirals.

    Science.gov (United States)

    Pearce, Ida

    2015-06-01

    This report concerns Entoptic Rotating Spiral Waves as observed and documented by the author over a period of 46 years (1962-2008). The manifestations of these state-dependent, elusive rotating spiral entities were brief, emerging only during sleep-to-waking arousal epochs (in limbo). The images were seen only with closed lids in favorable ambient lighting-here, termed the umbral view. The clusters of rotating spiral entities emerge briefly to conscious view; their angular subtenses are estimated to be between 1° and 4°, and the rotations at ten-turns per second. Epochs of these activities commonly continued for about 20 s, with longevity of each visible entity up to 4 s. 90% of all observed entities were circular and outwardly levorotary; 5% were elliptical, appearing only as horizontal (prolate) entities. Overlapping units were rare, and were chiefly elliptical. Observations of twin spirals were also rare, seen in counter rotations, each twin inwardly rotating.

  8. A Method for Determining Bulk Density, Material Density, and Porosity of Melter Feed During Nuclear Waste Vitrification

    Energy Technology Data Exchange (ETDEWEB)

    Hilliard, Zachary J.; Hrma, Pavel R.

    2016-01-31

    Abstract Glass making efficiency largely depends on heat transfer to reacting glass batch (melter feed), which in turn is influenced by the bulk density (ρb) and porosity (Φ) as functions of temperature (T). Neither b(T) nor Φ(T) functions are readily accessible to direct measurement, but they can be determined based on monitoring the profile area of heated glass batch pellets and material density of batches quenched at various stages of conversion via pycnometry. For the determination of Φb, the bulk volume must be calculated as a function of temperature. This is done via a program constructed in MATLAB which takes an image of a pellet profile at a given temperature and calculates the volume of said pellet. The quenched density measured by pycnometry must be converted to the density at heat treatment temperature. This is done by taking into account the volume change due to thermal expansion/contraction.

  9. On-chip spiral spectrometer

    CERN Document Server

    Redding, Brandon; Bromberg, Yaron; Sarma, Raktim; Cao, Hui

    2016-01-01

    We designed an on-chip spectrometer based on an evanescently-coupled multimode spiral waveguide. Interference between the modes in the waveguide forms a wavelength-dependent speckle pattern which can be used as a fingerprint to identify the input wavelength after calibration. Evanescent coupling between neighboring arms of the spiral enhances the temporal spread of light propagating through the spiral, leading to a dramatic increase in the spectral resolution. Experimentally, we demonstrated that a 250 {\\mu}m radius spiral spectrometer provides a resolution of 0.01 nm at a wavelength of 1520 nm. Spectra containing 40 independent spectral channels can be recovered simultaneously and the operation bandwidth can be increased further when measuring sparse spectra.

  10. Measuring with the spiral reader

    CERN Multimedia

    1974-01-01

    The spiral reader shown here was at the time, together with the Shivamatic scanning system, the basic equipment used for measuring bubble chamber pictures. Anne Anton sits at the table. (See Photo Archive 7408343.)

  11. Discovering Relationships Involving Baravelle Spirals

    Science.gov (United States)

    Wanko, Jeffrey J.

    2006-01-01

    This article details an exploration of Baravelle spirals as visual representations of infinite geometric series, focusing on a variety of strategies used by preservice teachers in discovering patterns and investigating relationships of variables.

  12. Analytical approximations for spiral waves

    Energy Technology Data Exchange (ETDEWEB)

    Löber, Jakob, E-mail: jakob@physik.tu-berlin.de; Engel, Harald [Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstrasse 36, EW 7-1, 10623 Berlin (Germany)

    2013-12-15

    We propose a non-perturbative attempt to solve the kinematic equations for spiral waves in excitable media. From the eikonal equation for the wave front we derive an implicit analytical relation between rotation frequency Ω and core radius R{sub 0}. For free, rigidly rotating spiral waves our analytical prediction is in good agreement with numerical solutions of the linear eikonal equation not only for very large but also for intermediate and small values of the core radius. An equivalent Ω(R{sub +}) dependence improves the result by Keener and Tyson for spiral waves pinned to a circular defect of radius R{sub +} with Neumann boundaries at the periphery. Simultaneously, analytical approximations for the shape of free and pinned spirals are given. We discuss the reasons why the ansatz fails to correctly describe the dependence of the rotation frequency on the excitability of the medium.

  13. Spiral-shaped disinfection reactors

    KAUST Repository

    Ghaffour, Noreddine

    2015-08-20

    This disclosure includes disinfection reactors and processes for the disinfection of water. Some disinfection reactors include a body that defines an inlet, an outlet, and a spiral flow path between the inlet and the outlet, in which the body is configured to receive water and a disinfectant at the inlet such that the water is exposed to the disinfectant as the water flows through the spiral flow path. Also disclosed are processes for disinfecting water in such disinfection reactors.

  14. Magnetic fields in spiral galaxies

    Science.gov (United States)

    Beck, Rainer

    2015-12-01

    Radio synchrotron emission, its polarization and Faraday rotation of the polarization angle are powerful tools to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30 \\upmu G) and in central starburst regions (50-100 \\upmu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15 \\upmu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the intergalactic medium.—Faraday rotation measures of the diffuse polarized radio emission from galaxy disks reveal large-scale spiral patterns that can be described by the superposition of azimuthal modes; these are signatures of regular fields generated by mean-field dynamos. "Magnetic arms" between gaseous spiral arms may also be products of dynamo action, but need a stable spiral pattern to develop. Helically twisted field loops winding around spiral arms were found in two galaxies so far. Large-scale field reversals, like the one found in the Milky Way, could not yet be detected in external galaxies. In radio halos around edge-on galaxies, ordered magnetic fields with X-shaped patterns are observed. The origin and evolution of cosmic magnetic fields, in particular their first occurrence in young galaxies and their dynamical importance during galaxy evolution, will be studied with

  15. Simulations of Normal Spiral Galaxies

    CERN Document Server

    Bottema, R

    2003-01-01

    Results are presented of numerical simulations of normal isolated late type spiral galaxies. Specifically the galaxy NGC 628 is used as a template. The method employs a TREESPH code including stellar particles, gas particles, cooling and heating of the gas, star formation according to a Jeans criterion, and Supernova feedback. A regular spiral disc can be generated as an equilibrium situation of two opposing actions. On the one hand cooling and dissipation of the gas, on the other hand gas heating by the FUV field of young stars and SN mechanical forcing. The disc exhibits small and medium scale spiral structure of which the multiplicity increases as a function of radius. The theory of swing amplification can explain, both qualitatively and quantitatively, the emerging spiral structure. In addition, swing amplification predicts that the existence of a grand design m=2 spiral is only possible if the disc is massive. The simulations show that the galaxy is then unstable to bar formation. A general criterion is ...

  16. Orientation decoding: Sense in spirals?

    Science.gov (United States)

    Clifford, Colin W G; Mannion, Damien J

    2015-04-15

    The orientation of a visual stimulus can be successfully decoded from the multivariate pattern of fMRI activity in human visual cortex. Whether this capacity requires coarse-scale orientation biases is controversial. We and others have advocated the use of spiral stimuli to eliminate a potential coarse-scale bias-the radial bias toward local orientations that are collinear with the centre of gaze-and hence narrow down the potential coarse-scale biases that could contribute to orientation decoding. The usefulness of this strategy is challenged by the computational simulations of Carlson (2014), who reported the ability to successfully decode spirals of opposite sense (opening clockwise or counter-clockwise) from the pooled output of purportedly unbiased orientation filters. Here, we elaborate the mathematical relationship between spirals of opposite sense to confirm that they cannot be discriminated on the basis of the pooled output of unbiased or radially biased orientation filters. We then demonstrate that Carlson's (2014) reported decoding ability is consistent with the presence of inadvertent biases in the set of orientation filters; biases introduced by their digital implementation and unrelated to the brain's processing of orientation. These analyses demonstrate that spirals must be processed with an orientation bias other than the radial bias for successful decoding of spiral sense.

  17. An evaluation of a two-stage spiral processing ultrafine bituminous coal

    Energy Technology Data Exchange (ETDEWEB)

    Matthew D. Benusa; Mark S. Klima [Penn State University, University Park, PA (United States). Energy and Mineral Engineering

    2008-10-15

    Testing was conducted to evaluate the performance of a multistage Multotec SX7 spiral concentrator treating ultrafine bituminous coal. This spiral mimics a two-stage separation in that the refuse is removed after four turns, and the clean coal and middlings are repulped (without water addition) and then separated in the final three turns. Feed samples were collected from the spiral circuit of a coal cleaning plant located in southwestern Pennsylvania. The samples consisted of undeslimed cyclone feed (nominal -0.15 mm) and deslimed spiral feed (nominal 0.15 x 0.053 mm). Testing was carried out to investigate the effects of slurry flow rate and solids concentration on spiral performance. Detailed size and ash analyses were performed on the spiral feed and product samples. For selected tests, float-sink and sulfur analyses were performed. In nearly all cases, ash reduction occurred down to approximately 0.025 mm, with some sulfur reduction occurring even in the -0.025 mm interval. The separation of the +0.025 mm material was not significantly affected by the presence of the -0.025 mm material when treating the undeslimed feed. The -0.025 mm material split in approximately the same ratio as the slurry, and the majority of the water traveled to the clean coal stream. This split ultimately increased the overall clean coal ash value. A statistical analysis determined that both flow rate and solids concentration affected the clean coal ash value and yield, though the flow rate had a greater effect on the separation. 23 refs.

  18. Three-dimensional spiral CT for neurosurgical planning

    Energy Technology Data Exchange (ETDEWEB)

    Klein, H.M. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Bertalanffy, H. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Mayfrank, L. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany)); Thron, A. (Dept. of Neuroradiology, Technical Univ., Aachen (Germany)); Guenther, R.W. (Dept. of Diagnostic Radiology, Technical Univ., Aachen (Germany)); Gilsbach, J.M. (Dept. of Neurosurgery, Technical Univ., Aachen (Germany))

    1994-08-01

    We carried out 22 examinations to determine the value of three-dimensional (3D) volumetric CT (spiral CT) for planning neurosurgical procedures. All examinations were carried out on a of the first generation spiral CT. A tube model was used to investigate the influence of different parameter settings. Bolus injection of nonionic contrast medium was used when vessels or strongly enhancing tumours were to be delineated. 3D reconstructions were carried out using the integrated 3D software of the scanner. We found a table feed of 3 mm/s with a slice thickness of 2 mm and an increment of 1 mm to be suitable for most purposes. For larger regions of interest a table feed of 5 mm was the maximum which could be used without blurring of the 3D images. Particular advantages of 3D reconstructed spiral scanning were seen in the planning of approaches to the lower clivus, acquired or congenital bony abnormalities and when the relationship between vessels, tumour and bone was important. (orig.)

  19. Transient spirals as superposed instabilities

    CERN Document Server

    Sellwood, J A

    2014-01-01

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the super-position of a few transient spiral modes. Each mode lasts between five and ten rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features, allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with l...

  20. Magnetic Fields in Spiral Galaxies

    CERN Document Server

    Beck, Rainer

    2015-01-01

    Radio synchrotron emission is a powerful tool to study the strength and structure of magnetic fields in galaxies. Unpolarized synchrotron emission traces isotropic turbulent fields which are strongest in spiral arms and bars (20-30\\mu G) and in central starburst regions (50-100\\mu G). Such fields are dynamically important; they affect gas flows and drive gas inflows in central regions. Polarized emission traces ordered fields, which can be regular or anisotropic turbulent, where the latter originates from isotropic turbulent fields by the action of compression or shear. The strongest ordered fields (10-15\\mu G) are generally found in interarm regions. In galaxies with strong density waves, ordered fields are also observed at the inner edges of spiral arms. Ordered fields with spiral patterns exist in grand-design, barred and flocculent galaxies, and in central regions. Ordered fields in interacting galaxies have asymmetric distributions and are a tracer of past interactions between galaxies or with the interg...

  1. Demonstration of beam steering via dipole-coupled plasmonic spiral antenna.

    Science.gov (United States)

    Rui, Guanghao; Abeysinghe, Don C; Nelson, Robert L; Zhan, Qiwen

    2013-01-01

    Optical antennas have been utilized to tailor the emission properties of nanoscale emitters in terms of the intensity, directivity and polarization. In this letter, we further explore the capability of beam steering via the use a spiral plasmonic structure as a transmitting antenna. According to both numerical simulation and experimental observations, the beaming direction can be steered through introducing a displacement of the feeding point to the spiral antenna from the geometrical center. For a 3-turn Archimedes' spiral antenna, experimental results show that steering angles of 3° and 7° are obtainable when the excitation location is transversally shifted from the center by a displacement of 200 nm and 500 nm, respectively. Furthermore, the emitted photons carry spin angular momentum determined by the chirality of the spiral optical antenna. A steerable nanoscale spin photon source may find important applications in single molecule sensing, quantum optical information processing and integrated photonic circuits.

  2. A Self-Complementary 1.2 to 40 GHz Spiral Antenna with Impedance Matching

    Directory of Open Access Journals (Sweden)

    M. Mazanek

    2006-09-01

    Full Text Available This paper describes a design of the Self- Complementary Spiral Antenna (SCSA which consists of a spiral antenna and a wideband impedance transformer. The spiral antenna and the transformer are designed separately due to computing demands. New knowledge about current distribution on the spiral antenna and influence of higher numbers of wavelength in circumference is presented. The novel transition between feeding and radiating antenna structure are optimized in the frequency range 1.2 to 40 GHz. The meaning of the transition in the paper includes the impedance as well as the geometry transforming of the structure. The antenna is suitable for wideband illuminating of a parabolic reflector due to relatively constant phase center and radiation pattern with frequency.

  3. Efficient Algorithm for Rectangular Spiral Search

    Science.gov (United States)

    Brugarolas, Paul; Breckenridge, William

    2008-01-01

    An algorithm generates grid coordinates for a computationally efficient spiral search pattern covering an uncertain rectangular area spanned by a coordinate grid. The algorithm does not require that the grid be fixed; the algorithm can search indefinitely, expanding the grid and spiral, as needed, until the target of the search is found. The algorithm also does not require memory of coordinates of previous points on the spiral to generate the current point on the spiral.

  4. Stellar Spirals in Triaxial Dark Matter Halos

    Science.gov (United States)

    Hu, Shaoran; Sijacki, Debora

    2017-03-01

    Two-armed grand-design spirals may form if the shape of its dark matter halo changes abruptly enough. The feasibility of such a mechanism is tested in realistic simulations. The interplay of such externally-driven spirals and self-induced transient spirals is then studied. Subhaloes are also found to lead to transient grand-design spiral structures when they impact the disk.

  5. Laser milling of martensitic stainless steels using spiral trajectories

    Science.gov (United States)

    Romoli, L.; Tantussi, F.; Fuso, F.

    2017-04-01

    A laser beam with sub-picosecond pulse duration was driven in spiral trajectories to perform micro-milling of martensitic stainless steel. The geometry of the machined micro-grooves channels was investigated by a specifically conceived Scanning Probe Microscopy instrument and linked to laser parameters by using an experimental approach combining the beam energy distribution profile and the absorption phenomena in the material. Preliminary analysis shows that, despite the numerous parameters involved in the process, layer removal obtained by spiral trajectories, varying the radial overlap, allows for a controllable depth of cut combined to a flattening effect of surface roughness. Combining the developed machining strategy to a feed motion of the work stage, could represent a method to obtain three-dimensional structures with a resolution of few microns, with an areal roughness Sa below 100 nm.

  6. Lopsided Spiral Galaxies

    CERN Document Server

    Jog, Chanda J

    2008-01-01

    The light distribution in the disks of many galaxies is non-axisymmetric or `lopsided' with a spatial extent much larger along one half of a galaxy than the other, as in M101. Recent near-IR observations show that lopsidedness is common. The stellar disks in nearly 30 % of galaxies have significant lopsidedness, greater than 10 % measured as the Fourier amplitude of the m=1 component normalized to the average value. This asymmetry is traced particularly well by the atomic hydrogen gas distribution lying in the outer parts. The lopsidedness also occurs in the nuclear regions, where the nucleus is offset with respect to the outer isophotes. The galaxies in a group environment show higher lopsidedness. The origin of lopsidedness could be due to the disk response to a tidally distorted halo, or via gas accretion. The lopsidedness has a large impact on the dynamics of the galaxy, its evolution, the star formation in it, and on the growth of the central black hole and on the nuclear fueling, merging of binary black...

  7. Inspired Spirals. Teaching Art with Art.

    Science.gov (United States)

    Hubbard, Guy

    2001-01-01

    Discusses spirals in nature, man-made objects, and art. Focuses on art that incorporates the spiral, including works by M. C. Escher and Frank Lloyd Wright, an African headdress, and a burial urn. Describes activities to help students make spirals of their own, such as constructing a coil clay pot. (CMK)

  8. Scale height determination of spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    计朝晖; 商朝晖; 彭秋和

    1997-01-01

    The method adopted here is based on the rigorous solution of Poison’s equation for logarithmic disturbance density within finite thickness galaxies. After their spiral arms are fitted directly with logarithmic spirals, the morphological parameters, scale heights and their relative errors for 32 spiral galaxies, such as NGC4814, are ob-tained.

  9. Solitons in spiraling Vogel lattices

    CERN Document Server

    Kartashov, Yaroslav V; Torner, Lluis

    2012-01-01

    We address light propagation in Vogel optical lattices and show that such lattices support a variety of stable soliton solutions in both self-focusing and self-defocusing media, whose propagation constants belong to domains resembling gaps in the spectrum of a truly periodic lattice. The azimuthally-rich structure of Vogel lattices allows generation of spiraling soliton motion.

  10. The enigma of auroral spirals

    Science.gov (United States)

    Haerendel, G.

    One of the most spectacular forms that the aurora borealis can assume is the large-scale spiral Spirals are dominantly observed along the poleward boundary of the auroral oval during active periods Two concepts have been pursued in explaining their origin and in particular the counterclockwise sense of rotation of the luminous structures when viewed along the magnetic field direction An essentially magnetostatic theory following Hallinan 1976 attributes the spiral pattern to the twisting of field-lines caused by a centrally located upward field-aligned current According to Oguti 1981 and followers a clockwise rotation of the plasma flow produces the anticlockwise structure There are observations seemingly confirming or contradicting either theory In this paper it is argued that both concepts are insufficient in that only parts of the underlying physics are considered Besides field-aligned currents and plasma flow one has to take into at least two further aspects The ionospheric conductivity modified by particle precipitation has an impact on the magnetospheric plasma dynamics Furthermore auroral arcs are not fixed entities subject to distortions by plasma flows or twisted field-lines but sites of transient releases of energy We suggest that auroral spirals are ports of entry or exit of plasma into or out of the auroral oval This way it can be understood why a clockwise plasma flow can create an anticlockwise luminous pattern

  11. On Generalized Euler Spirals in E^3

    OpenAIRE

    Saracoglu, Semra

    2012-01-01

    The Cornu spirals on plane are the curves whose curvatures are linear. Generalized planar cornu spirals and Euler spirals in E^3, the curves whose curvatures are linear are defined in [1,5]. In this study, these curves are presented as the ratio of two rational linear functions. Also here, generalized Euler spirals in E^3 has been defined and given their some various characterizations. The approach I used in this paper is useful in understanding the role of Euler spirals in E^3 in differentia...

  12. Interaction of multiarmed spirals in bistable media.

    Science.gov (United States)

    He, Ya-feng; Ai, Bao-quan; Liu, Fu-cheng

    2013-05-01

    We study the interaction of both dense and sparse multiarmed spirals in bistable media modeled by equations of the FitzHugh-Nagumo type. A dense one-armed spiral is characterized by its fixed tip. For dense multiarmed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect, and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multiarmed spirals are identical to that of corresponding one-armed spirals.

  13. Localized spirals in Taylor-Couette flow.

    Science.gov (United States)

    Heise, M; Abshagen, J; Küter, D; Hochstrate, K; Pfister, G; Hoffmann, Ch

    2008-02-01

    We present a type of spiral vortex state that appears from a supercritical Hopf bifurcation below the linear instability of circular Couette flow in a Taylor-Couette system with rigid end plates. These spirals have been found experimentally as well as numerically as "pure" states but also coexist with "classical" spirals (or axially standing waves for smaller systems) which typically appear from linear instability in counterrotating Taylor-Couette flow. These spiral states have an axial distribution of the strongly localized amplitude in the vicinity of the rigid end plates that confine the system in the axial direction. Furthermore, they show significantly different oscillation frequencies compared to the critical spiral frequencies. Despite the localization of the amplitude near the ends, the states appear as global states with spirals that propagate either toward the middle from each end of the system or vice versa. In contrast to classical spirals, these states exhibit a spatial or a spatiotemporal reflection symmetry.

  14. Dynamic analysis of the condensate and of the feed water in the Laguna Verde nuclear power station; Analisis dinamico del sistema de condensado y agua de alimentacion de la nucleoelectrica de Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Macedo Muth, Javier; Sandoval Pena, Ramon [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1988-12-31

    This article shows a non-lineal mathematical model for the condensate, and feed water systems and for feed water heater drains at the Laguna Verde Nuclear Power Station for its simulation in real time. The model allows the calculation of flows and pressures in all the piping system and equipment that integrate the systems. It was obtained by using the force unbalance in the fluid concept and is capable of reproducing its dynamic behavior through variations induced by the different operation modes and more common failures. The final model objective is to form part of the Laguna Verde simulator that will be used for operator training of this Nuclear Power Plant. [Espanol] En este articulo se muestra un modelo matematico no lineal de los sistemas de condensado, agua de alimentacion y drenes de calentadores de la central nuclear de Laguna Verde para su simulacion en tiempo real. El modelo permite calcular los flujos y las presiones en toda la red de tuberias y equipos que integran los sistemas. Se obtuvo utilizando el concepto de desbalance de fuerzas en el fluido, y es capaz de reproducir su comportamiento dinamico ante variaciones inducidas por los diversos modos de operacion y fallas mas comunes. El objetivo final del modelo es formar parte del simulador de Laguna Verde que se empleara para el adiestramiento de los operadores de dicha central nuclear.

  15. Spiral Galaxies as Chiral Objects?

    CERN Document Server

    Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra

    2005-01-01

    Spiral galaxies show axial symmetry and an intrinsic 2D-chirality. Environmental effects can influence the chirality of originally isolated stellar systems and a progressive loss of chirality can be recognised in the Hubble sequence. We point out a preferential modality for genetic galaxies as in microscopic systems like aminoacids, sugars or neutrinos. This feature could be the remnant of a primordial symmetry breaking characterizing systems at all scales.

  16. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  17. Transient spirals as superposed instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Sellwood, J. A. [Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States); Carlberg, R. G., E-mail: sellwood@physics.rutgers.edu, E-mail: carlberg@astro.utoronto.ca [Department of Astronomy and Astrophysics, University of Toronto, Toronto, ON M5S 3H4 (Canada)

    2014-04-20

    We present evidence that recurrent spiral activity, long manifested in simulations of disk galaxies, results from the superposition of a few transient spiral modes. Each mode lasts between 5 and 10 rotations at its corotation radius where its amplitude is greatest. The scattering of stars as each wave decays takes place over narrow ranges of angular momentum, causing abrupt changes to the impedance of the disk to subsequent traveling waves. Partial reflections of waves at these newly created features allows new standing-wave instabilities to appear that saturate and decay in their turn, scattering particles at new locations, creating a recurring cycle. The spiral activity causes the general level of random motion to rise, gradually decreasing the ability of the disk to support further activity unless the disk contains a dissipative gas component from which stars form on near-circular orbits. We also show that this interpretation is consistent with the behavior reported in other recent simulations with low-mass disks.

  18. Spiral modes and the Milky Way

    Science.gov (United States)

    Lin, C. C.

    Recent refinements of the density-wave theory of galactic spiral modes are reviewed, and their implications for models of the structure of the Milky Way are investigated. The quasi-stationary-spiral-structure hypothesis, the structure of D100, the WASER excitation mechanisms of pure trailing spirals and rudimentary barred spirals, and modal calculations are discussed. For the Milky Way, the finding of a one-armed spiral mode causing kinematical-distance asymmetry, and some observational verifications of the spiral-gravitational-field (SGF) model for the region within about 3 kpc of the sun are reported. The importance of constructing a plausible SGF model, rather than using a circular model, for the study of the outer regions of the Milky Way is stressed. The addition of a large halo or corona to the Galactic-mass-distribution model is found to imply only scale changes in the density-wave SGF model.

  19. RESEARCH AND IMPROVEMENT OF SPIRAL BUNKER

    Institute of Scientific and Technical Information of China (English)

    董正筑; 曹璎珞; 王启广

    1996-01-01

    A great attention has been paid to slowing the degradation of coal nowadays. The spiral bunker is the main measure to lower the degradation. In this paper the application and research of spiral bunker are introduced. And two non-normal spiral chutes are discussed. One is in the tangential direction of the inner wall of the bunker, another is in the direction of the diameter of the bunker. Mathematical models of the non-normal spiral chutes are set up to optimize the geometrical parameters of the spiral curved surface, which would ensure that coal travels smoothly to the bottom of the bunker. The results would be useful for designing and retrofitting the spiral bunker.

  20. Uncovering spiral structure in flocculent galaxies

    CERN Document Server

    Thornley, M D

    1996-01-01

    We present K'(2.1 micron) observations of four nearby flocculent spirals, which clearly show low-level spiral structure and suggest that kiloparsec-scale spiral structure is more prevalent in flocculent spirals than previously supposed. In particular, the prototypical flocculent spiral NGC 5055 is shown to have regular, two-arm spiral structure to a radius of 4 kpc in the near infrared, with an arm-interarm contrast of 1.3. The spiral structure in all four galaxies is weaker than that in grand design galaxies. Taken in unbarred galaxies with no large, nearby companions, these data are consistent with the modal theory of spiral density waves, which maintains that density waves are intrinsic to the disk. As an alternative, mechanisms for driving spiral structure with non-axisymmetric perturbers are also discussed. These observations highlight the importance of near infrared imaging for exploring the range of physical environments in which large-scale dynamical processes, such as density waves, are important.

  1. The DESIR Facility at SPIRAL2

    Indian Academy of Sciences (India)

    Bertram Blank; Desir

    2010-08-01

    The DESIR Collaboration proposes the construction of an experimental facility to exploit the low-energy beams from SPIRAL1, SPIRAL2 and S3. The high degree of purity required to push experiments towards the limits of stability will be achieved by the implementation in the SPIRAL2 production building of a high-efficiency RFQ cooler coupled to a high-resolution mass separator. Beams from the low-energy branch of the separator spectrometer S3 and from SPIRAL1 will allow complementary studies of refractory elements produced by means of fusion reactions as well as of light and intense exotic beams, respectively.

  2. Solvable Model of Spiral Wave Chimeras

    DEFF Research Database (Denmark)

    Martens, Erik Andreas; Laing, Carlo R.; Strogatz, Steven H.

    2010-01-01

    Spiral waves are ubiquitous in two-dimensional systems of chemical or biological oscillators coupled locally by diffusion. At the center of such spirals is a phase singularity, a topological defect where the oscillator amplitude drops to zero. But if the coupling is nonlocal, a new kind of spiral...... can occur, with a circular core consisting of desynchronized oscillators running at full amplitude. Here, we provide the first analytical description of such a spiral wave chimera and use perturbation theory to calculate its rotation speed and the size of its incoherent core....

  3. Type of spiral wave with trapped ions.

    Science.gov (United States)

    Li, Yuting; Li, Haihong; Zhu, Yun; Zhang, Mei; Yang, Junzhong

    2011-12-01

    Pattern formation in ultracold quantum systems has recently received a great deal of attention. In this work, we investigate a two-dimensional model system simulating the dynamics of trapped ions. We find a spiral wave that is rigidly rotating, but with a peculiar core region in which adjacent ions oscillate in antiphase. The formation of this spiral wave is ascribed to the excitability previously reported by Lee and Cross. The breakup of the spiral wave is probed and, especially, an extraordinary scenario of the disappearance of the spiral wave, caused by spontaneous expansion of the antiphase core, is unveiled.

  4. Scale heights of 84 northern spiral galaxies

    Institute of Scientific and Technical Information of China (English)

    马骏; 彭秋和

    1997-01-01

    Using the method proposed by Peng (1988) on the basis of density waves theory and the solution of three-dimensional Poisson s equation for a logarithmic disturbance of density,and analyzing the spiral patterns,the scale heights of 84 northern spiral galaxies,whose images are taken from the Digitized Sky Survey at Xinglong Observational Station of Beijing Observatory,are measured.The spiral arms of all these galaxies have been fitted on their photographs with some logarithmic spiral curves for getting their correct inclinations.

  5. Evolution of Spiral Waves in Excitable Systems

    Institute of Scientific and Technical Information of China (English)

    KEN Ji-Rong; ZHU Tao; MO Shu-Fan

    2009-01-01

    Spiral waves, whose rotation center can be regarded as a point defect, widely exist in various two-dimensional excitable systems. In this paper, by making use of Duan's topological current theory, we obtain the charge density of spiral waves and the topological inner structure of its topological charge. The evolution of spiral wave is also studied from the topological properties of a two-dimensional vector field. The spiral waves are found generating or annihilating at the limit points and encountering, splitting, or merging at the bifurcation points of the two-dimensional vector field. Some applications of our theory are also discussed.

  6. Neskinchenna spiral u seredovyshchi z vtratamy [The endless spiral in environment with losses

    Directory of Open Access Journals (Sweden)

    A. V. Talaluiev

    1998-09-01

    Full Text Available Found dispersion equation that describes the endless spiral of losses in the environment. The analytical expression for the wave resistance spiral, seen as a long line in lossy environment, and analytical expressions for the fields in cylindrical coordinates. The question of coordination sources of RF energy spiral.

  7. Elimination of Spiral Waves and Competition between Travelling Wave Impulses and Spiral Waves

    Institute of Scientific and Technical Information of China (English)

    YUAN Guo-Yong; ZHANG Guang-Cai; WANG Guang-Rui; CHEN Shi-Gang; SUN Peng

    2005-01-01

    @@ The interaction between travelling wave impulses and spiral waves is studied and the results of their competition are related to the exciting period. From the results, it is known that the formation and development of spiral waves in cardiac tissue depend on the period by which the travelling wave impulses are excited. A method is proposed to eliminate spiral waves, which is easily operated.

  8. Emergency Physicians Think in Spirals.

    Science.gov (United States)

    Renouf, Tia; Whalen, Desmond; Pollard, Megan; Dubrowski, Adam

    2015-11-17

    As adult learners, junior clerks on core rotations in emergency medicine (EM) are expected to "own" their patients and follow them from presentation to disposition in the Emergency Department (ED). Traditionally, we teach clerks to present an exhaustive linear list of symptoms and signs to their preceptors. This does not apply well to the fast-paced ED setting. Mnemonics have been developed to teach clerks how to present succinctly and cohesively. To address the need for continual patient reassessment throughout the patient's journey in the ED, we propose a complimentary approach called SPIRAL.

  9. Galactic Scale Flows and the Triggering of Star Formation in Spiral Galaxies

    Science.gov (United States)

    Ramón-Fox, F. G.; Bonnell, I. A.

    2016-06-01

    Galactic scale gas flows feed the growth of molecular clouds where stars form in high-density cores. Large scale flows also play a role in injecting the energy that drives the internal dynamics of these clouds, which affects their overall stability and star formation activity. The triggering of star formation involves a connection between large and small-scale dynamical processes in galaxies, which can be explored using high-resolution hydrodynamical simulations. We present results of current work in high-resolution N-body and Smoothed Particle Hydrodynamics simulations of a model spiral galaxy with a realistic spiral arm morphology. These simulations allow to study gas flows in a self-consistent galaxy and their role on molecular cloud formation and growth. They also provide a ground for studying molecular cloud properties in different environments of a galaxy, the effects of spiral arms on large scale flows and for understanding global star formation relations.

  10. Spiral density waves in M81. I. Stellar spiral density waves

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Chien-Chang; Lin, Lien-Hsuan; Wang, Hsiang-Hsu; Taam, Ronald E., E-mail: hhwang@asiaa.sinica.edu.tw [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan, R.O.C (China)

    2014-04-20

    Aside from the grand-design stellar spirals appearing in the disk of M81, a pair of stellar spiral arms situated well inside the bright bulge of M81 has been recently discovered by Kendall et al. The seemingly unrelated pairs of spirals pose a challenge to the theory of spiral density waves. To address this problem, we have constructed a three-component model for M81, including the contributions from a stellar disk, a bulge, and a dark matter halo subject to observational constraints. Given this basic state for M81, a modal approach is applied to search for the discrete unstable spiral modes that may provide an understanding for the existence of both spiral arms. It is found that the apparently separated inner and outer spirals can be interpreted as a single trailing spiral mode. In particular, these spirals share the same pattern speed 25.5 km s{sup –1} kpc{sup –1} with a corotation radius of 9.03 kpc. In addition to the good agreement between the calculated and the observed spiral pattern, the variation of the spiral amplitude can also be naturally reproduced.

  11. ANGULAR-MOMENTUM IN BINARY SPIRAL GALAXIES

    NARCIS (Netherlands)

    OOSTERLOO, T

    1993-01-01

    In order to investigate the relative orientations of spiral galaxies in pairs, the distribution of the angle between the spin-vectors for a new sample of 40 binary spiral galaxies is determined. From this distribution it is found, contrary to an earlier result obtained by Helou (1984), that there is

  12. QS Spiral: Visualizing Periodic Quantified Self Data

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Cuttone, Andrea; Jørgensen, Sune Lehmann

    2013-01-01

    In this paper we propose an interactive visualization technique QS Spiral that aims to capture the periodic properties of quantified self data and let the user explore those recurring patterns. The approach is based on time-series data visualized as a spiral structure. The interactivity includes ...

  13. Scaling effects in spiral capsule robots.

    Science.gov (United States)

    Liang, Liang; Hu, Rong; Chen, Bai; Tang, Yong; Xu, Yan

    2017-04-01

    Spiral capsule robots can be applied to human gastrointestinal tracts and blood vessels. Because of significant variations in the sizes of the inner diameters of the intestines as well as blood vessels, this research has been unable to meet the requirements for medical applications. By applying the fluid dynamic equations, using the computational fluid dynamics method, to a robot axial length ranging from 10(-5) to 10(-2) m, the operational performance indicators (axial driving force, load torque, and maximum fluid pressure on the pipe wall) of the spiral capsule robot and the fluid turbulent intensity around the robot spiral surfaces was numerically calculated in a straight rigid pipe filled with fluid. The reasonableness and validity of the calculation method adopted in this study were verified by the consistency of the calculated values by the computational fluid dynamics method and the experimental values from a relevant literature. The results show that the greater the fluid turbulent intensity, the greater the impact of the fluid turbulence on the driving performance of the spiral capsule robot and the higher the energy consumption of the robot. For the same level of size of the robot, the axial driving force, the load torque, and the maximum fluid pressure on the pipe wall of the outer spiral robot were larger than those of the inner spiral robot. For different requirements of the operating environment, we can choose a certain kind of spiral capsule robot. This study provides a theoretical foundation for spiral capsule robots.

  14. Tracing the spiral arms in IP Pegasi

    NARCIS (Netherlands)

    Baptista, R.; Morales-Rueda, L.; Harlaftis, E.T.; Marsh, T.R.; Steeghs, D.

    2005-01-01

    We report the analysis of time-resolved spectroscopy of IP Pegasi in outburst with eclipse mapping techniques to investigate the location and geometry of the observed spiral structures. We were able to obtain an improved view of the spiral structures with the aid of light curves extracted in

  15. Quantitative analysis of spirality in elliptical galaxies

    CERN Document Server

    Dojcsak, Levente

    2013-01-01

    We use an automated galaxy morphology analysis method to quantitatively measure the spirality of galaxies classified manually as elliptical. The data set used for the analysis consists of 60,518 galaxy images with redshift obtained by the Sloan Digital Sky Survey (SDSS) and classified manually by Galaxy Zoo, as well as the RC3 and NA10 catalogues. We measure the spirality of the galaxies by using the Ganalyzer method, which transforms the galaxy image to its radial intensity plot to detect galaxy spirality that is in many cases difficult to notice by manual observation of the raw galaxy image. Experimental results using manually classified elliptical and S0 galaxies with redshift <0.3 suggest that galaxies classified manually as elliptical and S0 exhibit a nonzero signal for the spirality. These results suggest that the human eye observing the raw galaxy image might not always be the most effective way of detecting spirality and curves in the arms of galaxies.

  16. Termination of pinned spirals by local stimuli

    Science.gov (United States)

    Chen, Jiang-Xing; Guo, Ming-Ming; Ma, Jun

    2016-02-01

    The termination of pinned spirals on a defect by means of local stimuli is studied. On a completely unexcitable defect, the elimination process is discussed and its corresponding mechanism is presented. Especially, the mechanism of unpinning spirals on a partially unexcitable defect, which has not been investigated so far, is explored. With fixed pacing frequency ω L , there exists a maximal radius R max above which the pinned spiral cannot be removed. It is found that the value of R max does not increase as ω L in a dynamical regime, forming a platform in the R\\textit{max}\\text-ωL curves. Based on analyzing the dispersion relation on the spiral tip around the obstacle, the underlying mechanism is clarified. Also, it is found that when multiple spirals are pinned, the value of R max decreases on a partially unexcitable defect while the change is very slight on a completely unexcitable one.

  17. Illusory spirals and loops in crystal growth.

    Science.gov (United States)

    Shtukenberg, Alexander G; Zhu, Zina; An, Zhihua; Bhandari, Misha; Song, Pengcheng; Kahr, Bart; Ward, Michael D

    2013-10-22

    The theory of dislocation-controlled crystal growth identifies a continuous spiral step with an emergent lattice displacement on a crystal surface; a mechanistic corollary is that closely spaced, oppositely winding spirals merge to form concentric loops. In situ atomic force microscopy of step propagation on pathological L-cystine crystals did indeed show spirals and islands with step heights of one lattice displacement. We show by analysis of the rates of growth of smaller steps only one molecule high that the major morphological spirals and loops are actually consequences of the bunching of the smaller steps. The morphology of the bunched steps actually inverts the predictions of the theory: Spirals arise from pairs of dislocations, loops from single dislocations. Only through numerical simulation of the growth is it revealed how normal growth of anisotropic layers of molecules within the highly symmetrical crystals can conspire to create features in apparent violation of the classic theory.

  18. Practical nuclear medicine

    CERN Document Server

    Gemmell, Howard G; Sharp, Peter F

    2006-01-01

    Nuclear medicine plays a crucial role in patient care, and this book is an essential guide for all practitioners to the many techniques that inform clinical management. The first part covers the scientific basis of nuclear medicine, the rest of the book deals with clinical applications. Diagnostic imaging has an increasingly important role in patient management and, despite advances in other modalities (functional MRI and spiral CT), nuclear medicine continues to make its unique contribution by its ability to demonstrate physiological function. This book is also expanded by covering areas of d

  19. Solar Interactions on Spiral Petroglyphs

    Science.gov (United States)

    Davis, Brian F.; Preston, Robert A.

    2003-11-01

    Like most prehistoric cultures, the ancestors of the native Puebloan people of the Southwest were aware of the yearly cycle of the sun. This and other natural phenomena are fundamental for interpreting their world view, religion, and art. Some researchers have argued that rock art, particularly petroglyphs, displays this focus on the natural world through the distinctive interplay of sunlight on these carvings. However, the question of whether or not these interactions occur by intention or chance has hampered the acceptance of this evidence by the archaeological community. To address this question we have performed a detailed study of a complete sample of over 100 spiral petroglyphs within a limited area (less than 20 km^2) of central New Mexico. We have examined this sample on both solstices and equinoxes, and have observed well-defined and consistent sunlight interactions on about 80This work clearly demonstrates the reality and profusion of this ancient cultural tradition. Several examples will be presented.

  20. Experimental Study on Spiral Patterns in Dielectric Barrier Discharge System

    Institute of Scientific and Technical Information of China (English)

    LIU Shu-Hua; DONG Li-Fang; LIU Fu-Cheng; LI Shu-Feng; LI Xue-Chen; WANG Hong-Fang

    2006-01-01

    Spiral patterns are obtained in a dielectric barrier discharge system with water electrodes. The dynamics of spiral formation and transition is investigated. Wavelength characteristic of spiral patterns is also studied. Correlation measurements indicate that the wavelength of spiral pattern increases with the increasing gas gap width and oscillates with the increasing drive frequency.

  1. Spiral Wave Dynamics in a Response System Subjected to a Spiral Wave Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Zhao; CHEN Yong-Qi; TANG Guo-Ning; LIU Jun-Xian

    2011-01-01

    @@ Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered.The spiral wave in the response system is thus subjected to a spiral wave forcing.We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling.The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch.When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave.When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave.The generation of anti-target wave in coupled excitable media is observed for the first time.Furthermore, when the coupling strength is strong, the synchronization between two subsystems can be established.%Unidirectional linear error feedback coupling of two excitable medium systems displaying spiral waves is considered. The spiral wave in the response system is thus subjected to a spiral wave forcing. We find that the unidirectional feedback coupling can lead to richer behaviour than the mutual coupling. The spiral wave dynamics in the response system depends on the coupling strength and frequency mismatch. When the coupling strength is small, the feedback coupling induces the drift or meander of the forced spiral wave. When the coupling strength is large enough, the feedback coupling may lead to the transition from spiral wave to anti-target or target-like wave. The generation of anti-target wave in coupled excitable media is observed for the first time. Furthermore,when the coupling strength is strong, the synchronization between two subsystems can be established.

  2. Spatial analysis of IRAS observations of nearby spirals

    Science.gov (United States)

    Ball, Roger; Lo, R. Y.

    1990-01-01

    The unbiased survey of the infrared sky carried out by the Infrared Astronomy Satellite (IRAS) satellite has greatly accelerated advances in understanding the dust component of our own and external galaxies. However, most extragalactic studies to date have been based on the IRAS Point Source Catalog (PSC), which has two serious limitations. First, in sources where a significant fraction of the flux is extended, significant errors may result from using PSC fluxes in comparative studies, and these errors could be systematic if the tendency to be non-pointlike depends on physical properties of the galaxy. Additionally, use of PSC fluxes rules out any direct investigation of the spatial distribution of the IRAS emission from disks in external galaxies. Since work on the Galactic IRAS results has shown that very different physical processes can make varying contributions to the observed flux, it is important to look at a wide sample of galaxies with some spatial resolution to study the relative dominance of these processes under a variety of conditions. Here, researchers report on work they are doing to carry out this program for many nearby spirals, using an analysis package that was developed for this purpose. Researchers carried out analysis for a sample of 121 nearby spirals. The fraction of the flux contained in a point source varies from 0 to 1 across the sample, all of which are well resolved at their nominal optical diameters. There is no evidence that the galaxies of smaller angular size are less likely to be resolved by IRAS at this level. The program gives results which are quite repeatable from scan to scan; the fraction f (point source flux over total flux) at 60 microns has typical errors of 0.03 when different scans are combined. Approximately two-thirds of the sample have more flux in the extended than in the nuclear component. There is a tendency for earlier-type spirals to be less centrally concentrated, but this effect is slight and the degree of

  3. SPIRAL CONTACTOR FOR SOLVENT EXTRACTION COLUMN

    Science.gov (United States)

    Cooley, C.R.

    1961-06-13

    The patented extraction apparatus includes a column, perforated plates extending across the column, liquid pulse means connected to the column, and an imperforate spiral ribbon along the length of the column.

  4. Asymptotic theory for spiral wave reflections

    CERN Document Server

    Langham, Jacob; Barkley, Dwight

    2014-01-01

    Resonantly forced spiral waves in excitable media drift in straight-line paths, their rotation centers behaving as point-like objects moving along trajectories with a constant velocity. Interaction with medium boundaries alters this velocity and may often result in a reflection of the drift trajectory. Such reflections have diverse characteristics and are known to be highly non-specular in general. In this context we apply the theory of response functions, which via numerically computable integrals, reduces the reaction-diffusion equations governing the whole excitable medium to the dynamics of just the rotation center and rotation phase of a spiral wave. Spiral reflection trajectories are computed by this method for both small and large-core spiral waves. Such calculations provide insight into the process of reflection as well as explanations for differences in trajectories across parameters, including the effects of incidence angle and forcing amplitude. Qualitative aspects of these results are preserved fa...

  5. Featured Image: The Birth of Spiral Arms

    Science.gov (United States)

    Kohler, Susanna

    2017-01-01

    In this figure, the top panels show three spiral galaxies in the Virgo cluster, imaged with the Sloan Digital Sky Survey. The bottom panels provide a comparison with three morphologically similar galaxies generated insimulations. The simulations run by Marcin Semczuk, Ewa okas, and Andrs del Pino (Nicolaus Copernicus Astronomical Center, Poland) were designed to examine how the spiral arms of galaxies like the Milky Way may have formed. In particular, the group exploredthe possibility that so-called grand-design spiral arms are caused by tidal effects as a Milky-Way-like galaxy orbits a cluster of galaxies. The authors show that the gravitational potential of the cluster can trigger the formation of two spiral arms each time the galaxy passes through the pericenter of its orbit around the cluster. Check out the original paper below for more information!CitationMarcin Semczuk et al 2017 ApJ 834 7. doi:10.3847/1538-4357/834/1/7

  6. THE BIRTH AND DEATH PROCESSES OF HYPERCYCLE SPIRALS

    OpenAIRE

    KAZUMASA OIDA

    2003-01-01

    The behavior of hypercycle spirals in a two-dimensional cellular automaton model is analyzed. Each spiral can be approximated by an Archimedean spiral with center, width, and phase change according to Brownian motion. A barrier exists between two spirals if the phase synchronization hypothesis is taken into account, and the occurrence rate of pair decay (simultaneous disappearance of two spirals) can be explained through a random walk simulation with the barrier. Simulation experiments show t...

  7. Simulations of dual morphology in spiral galaxies

    CERN Document Server

    Berman, S L

    2003-01-01

    Gas and stars in spiral galaxies are modelled with the DUAL code, using hydrodynamic and N-body techniques. The simulations reveal morphological differences mirroring the dual morphologies seen in B and K' band observations of many spiral galaxies. In particular, the gaseous images are more flocculent with lower pitch angles than the stellar images, and the stellar arm-interarm contrast correlates with the degree of morphological decoupling.

  8. On Three-Dimensional Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    LUO Xin-Lian; PENG Qiu-He; LONG Min; PENG Fang; ZOU Zhi-Gang

    2000-01-01

    Density waves in 3D spiral galaxies are studied. In order to eliminate the forbidden region near the corotation in the grand-design galaxies, we assume that the perturbation satisfies the stable condition Q(r) > 1 over all the disk except that at the corotation. Then, a new method is put forward here to determine some basic parameters of spiral galaxies. We apply it to our Galaxy, and the results are in good agreement with the previous results.

  9. View factors of cylindrical spiral surfaces

    Science.gov (United States)

    Lebedev, Vladimir A.; Solovjov, Vladimir P.

    2016-03-01

    Analytical expressions are presented for the view factors (radiative configuration factors) associated with the flat right cylindrical spiral surface. Such cylindrical spiral systems are widely applied as electrical resistance heating elements for lighting devices, electronic radio tubes, high-speed gas flow heaters, and other appliances used for scientific, industrial and domestic purposes. Derivation of the view factors is based on the invariant principles and the results presented in Lebedev (2000, 2003,1988) [1-3].

  10. Twisted Radiation by Electrons in Spiral Motion

    CERN Document Server

    Katoh, M; Mirian, N S; Konomi, T; Taira, Y; Kaneyasu, T; Hosaka, M; Yamamoto, N; Mochihashi, A; Takashima, Y; Kuroda, K; Miyamoto, A; Miyamoto, K; Sasaki, S

    2016-01-01

    We theoretically show that a single free electron in circular/spiral motion radiates an electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. We experimentally demonstrate it by double-slit diffraction on radiation from relativistic electrons in spiral motion. We show that twisted photons should be created naturally by cyclotron/synchrotron radiations or Compton scatterings in various situations in astrophysics. We propose promising laboratory vortex photon sources in various wavelengths ranging from radio wave to gamma-rays.

  11. The distribution of prime numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    Prime Numbers clearly accumulate on defined spiral graphs,which run through the Square Root Spiral. These spiral graphs can be assigned to different spiral-systems, in which all spiral-graphs have the same direction of rotation and the same -second difference- between the numbers, which lie on these spiral-graphs. A mathematical analysis shows, that these spiral graphs are caused exclusively by quadratic polynomials. For example the well known Euler Polynomial x2+x+41 appears on the Square Root Spiral in the form of three spiral-graphs, which are defined by three different quadratic polynomials. All natural numbers,divisible by a certain prime factor, also lie on defined spiral graphs on the Square Root Spiral (or Spiral of Theodorus, or Wurzelspirale). And the Square Numbers 4, 9, 16, 25, 36 even form a highly three-symmetrical system of three spiral graphs, which divides the square root spiral into three equal areas. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Wit...

  12. SIGNATURES OF LONG-LIVED SPIRAL PATTERNS

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Garcia, Eric E. [Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Aptdo. Postal 51 y 216, 72000 Puebla, Pue. (Mexico); Gonzalez-Lopezlira, Rosa A., E-mail: ericmartinez@inaoep.mx, E-mail: martinez@astro.unam.mx, E-mail: r.gonzalez@crya.unam.mx [Centro de Radioastronomia y Astrofisica, UNAM, Campus Morelia, Michoacan, C.P. 58089 (Mexico)

    2013-03-10

    Azimuthal age/color gradients across spiral arms are a signature of long-lived spirals. From a sample of 19 normal (or weakly barred) spirals where we have previously found azimuthal age/color gradient candidates, 13 objects were further selected if a two-armed grand-design pattern survived in a surface density stellar mass map. Mass maps were obtained from optical and near-infrared imaging, by comparison with a Monte Carlo library of stellar population synthesis models that allowed us to obtain the mass-to-light ratio in the J band, (M/L){sub J}, as a function of (g - i) versus (i - J) color. The selected spirals were analyzed with Fourier methods in search of other signatures of long-lived modes related to the gradients, such as the gradient divergence toward corotation, and the behavior of the phase angle of the two-armed spiral in different wavebands, as expected from theory. The results show additional signatures of long-lived spirals in at least 50% of the objects.

  13. Fast magnetohydrodynamic density waves in spiral galaxies

    Science.gov (United States)

    Lou, Yu-Qing; Han, J. L.; Fan, Zuhui

    1999-09-01

    The newly observed large-scale structures of a southern grand-design spiral galaxy NGC 2997 in total and polarized radio-continuum emission together with their overall correlations with the known optical spiral structure are physically interpreted in terms of fast magnetohydrodynamic (MHD) density waves in contrast to slow MHD density waves in NGC 6946. The global spiral pattern of such fast MHD density waves extends from the very centre, where the disc rotates almost rigidly within ~0.5arcmin, all the way to the outer disc with a more or less flat rotation curve. To strengthen the case, several known features of spiral galaxies M51 and IC 342 are referred to and their pattern identifications discussed. It is emphasized that the nature of a magnetized spiral galaxy would be much better appreciated by examining large-scale structures in optical, atomic hydrogen Hi, total and polarized radio-continuum and infrared emission together. As various star-formation processes occur concurrently and/or sequentially in spiral arms of high gas concentration, relatively broad and fuzzy Hi arms, roughly coincident with optical arms in the inner disc, are expected to extend from the extremities of fading optical arms further into the outer gas disc. We predict that the south-east `magnetic arm', apparently isolated from any optical features, in total and polarized radio-continuum intensity maps of NGC 2997 should be associated with an Hi gas arm yet to be detected in 21-cm line emission.

  14. Arm & Interarm Star Formation in Spiral Galaxies

    CERN Document Server

    Foyle, Kelly; Walter, Fabian; Leroy, Adam

    2010-01-01

    We investigate the relationship between spiral arms and star formation in the grand-design spirals NGC 5194 and NGC 628 and in the flocculent spiral NGC 6946. Filtered maps of near-IR (3.6 micron) emission allow us to identify "arm regions" that should correspond to regions of stellar mass density enhancements. The two grand-design spirals show a clear two-armed structure, while NGC 6946 is more complex. We examine these arm and interarm regions, looking at maps that trace recent star formation - far-ultraviolet (GALEX NGS) and 24 micron emission (Spitzer, SINGS) - and cold gas - CO (Heracles) and HI (Things). We find the star formation tracers and CO more concentrated in the spiral arms than the stellar 3.6 micron flux. If we define the spiral arms as the 25% highest pixels in the filtered 3.6 micron images, we find that the majority (60%) of star formation tracers occurs in the interarm regions; this result persists qualitatively even when considering the potential impact of finite data resolution and diffu...

  15. Do Bars Drive Spiral Density Waves?

    CERN Document Server

    Buta, R J; Elmegreen, B G; Salo, H; Laurikainen, E; Elmegreen, D M; Puerari, I; Block, D L

    2009-01-01

    We present deep near-infrared K_s-band AAT IRIS2 observations of a selected sample of nearby barred spiral galaxies, including some with the strongest known bars. The sample covers a range of Hubble types from SB0- to SBc. The goal is to determine if the torque strengths of the spirals correlate with those of the bars, which might be expected if the bars actually drive the spirals as has been predicted by theoretical studies. This issue has implications for interpreting bar and spiral fractions at high redshift. Analysis of previous samples suggested that such a correlation exists in the near-infrared, where effects of extinction and star formation are less important. However, the earlier samples had only a few excessively strong bars. Our new sample largely confirms our previous studies, but still any correlation is relatively weak. We find two galaxies, NGC 7513 and UGC 10862, where there is a only a weak spiral in the presence of a very strong bar. We suggest that some spirals probably are driven by their ...

  16. Radial transport of dust in spiral galaxies

    CERN Document Server

    Vorobyov, E I; Shchekinov, Yu. A.

    2006-01-01

    Motivated by recent observations which detect dust at large galactocentric distances in the disks of spiral galaxies, we propose a mechanism of outward radial transport of dust by spiral stellar density waves. We consider spiral galaxies in which most of dust formation is localized inside the corotation radius. We show that in the disks of such spiral galaxies, the dust grains can travel over radial distances that exceed the corotation radius by roughly 25%. A fraction of the dust grains can be trapped on kidney-shaped stable orbits between the stellar spiral arms and thus can escape the destructive effect of supernova explosions. These grains form diffuse dusty spiral arms, which stretch 4-5 kpc from the sites of active star formation. About 10% of dust by mass injected inside corotation, can be transported over radial distances 3-4 kpc during approximately 1.0 Gyr. This is roughly an order of magnitude more efficient than can be provided by the turbulent motions.

  17. Spiral 2: preliminary design study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-11-15

    The scientific council of GANIL asked to perform a comparative study on the production methods based on gamma induced fission and rapid-neutron induced fission concerning the nature and the intensity of the neutron-rich products. The production rate expected should be around 10{sup 13} fissions per second. The study should include the implantation and the costs of the concerned accelerators. The scientific committee recommended also to study the possibility to re-inject the radioactive beams of SPIRAL-II in the cyclotrons available at GANIL in order to give access to an energy range from 1.7 to 100 MeV/nucleon. For that purpose, some study groups have been formed to evaluate the possibility of such a project in the different components: physics case, target-ion sources, drivers, post-acceleration and general infrastructure. The organization of the project study is given at the end of this report. The following report presents an overview of the study. Particularly the total costs have been assessed according to 3 options for the driver: 38.0*10{sup 6} euros for a 40 MeV deuteron linac, 18.7*10{sup 6} euros for a 45 MeV electron linac, and 29.1*10{sup 6} euros for a 80 MeV deuteron cyclotron.

  18. Factors Associated with Infant Feeding Methods after the Nuclear Power Plant Accident in Fukushima: Data from the Pregnancy and Birth Survey for the Fiscal Year 2011 Fukushima Health Management Survey.

    Science.gov (United States)

    Ishii, Kayoko; Goto, Aya; Ota, Misao; Yasumura, Seiji; Abe, Masafumi; Fujimori, Keiya

    2016-08-01

    Objectives The objective of this study was to assess the frequency of and factors associated with infant feeding methods after the Fukushima nuclear power plant accident using data from the Fukushima Health Management Survey. Methods We conducted an anonymous self-administered questionnaire survey of 16,001 women who gave birth around the time of the Great East Japan Earthquake and registered their pregnancies at Fukushima Prefecture municipal offices between August 1, 2010 and July 31, 2011. The responses of 8366 women were analyzed. Chi square tests and multiple logistic regression analysis were used to compare various factors between women who had formula-fed their children because of concern regarding radioactive contamination or other reasons and those who had breastfed exclusively. Results The percentage of women who had breastfed exclusively was 30.9 %. The percentage of women who had both breastfed and formula-fed or formula-fed exclusively was 69.1 %, of which 20.3 % formula-fed because of concern regarding radioactive contamination of breast milk. The use of formula feeding because of concern about radioactive contamination was significantly higher in women who had resided within the evacuation area and those whose regular antenatal care had been interrupted. The use of formula feeding for other reasons was significantly higher in women who had resided within the evacuation area and lower for those who had willingly switched to another medical institution. Conclusions for Practice Our results suggest the importance of providing breastfeeding support to women who are forced to evacuate or whose antenatal care is interrupted after a disaster.

  19. Six Decades of Spiral Density Wave Theory

    Science.gov (United States)

    Shu, Frank H.

    2016-09-01

    The theory of spiral density waves had its origin approximately six decades ago in an attempt to reconcile the winding dilemma of material spiral arms in flattened disk galaxies. We begin with the earliest calculations of linear and nonlinear spiral density waves in disk galaxies, in which the hypothesis of quasi-stationary spiral structure (QSSS) plays a central role. The earliest success was the prediction of the nonlinear compression of the interstellar medium and its embedded magnetic field; the earliest failure, seemingly, was not detecting color gradients associated with the migration of OB stars whose formation is triggered downstream from the spiral shock front. We give the reasons for this apparent failure with an update on the current status of the problem of OB star formation, including its relationship to the feathering substructure of galactic spiral arms. Infrared images can show two-armed, grand design spirals, even when the optical and UV images show flocculent structures. We suggest how the nonlinear response of the interstellar gas, coupled with overlapping subharmonic resonances, might introduce chaotic behavior in the dynamics of the interstellar medium and Population I objects, even though the underlying forces to which they are subject are regular. We then move to a discussion of resonantly forced spiral density waves in a planetary ring and their relationship to the ideas of disk truncation, and the shepherding of narrow rings by satellites orbiting nearby. The back reaction of the rings on the satellites led to the prediction of planet migration in protoplanetary disks, which has had widespread application in the exploding data sets concerning hot Jupiters and extrasolar planetary systems. We then return to the issue of global normal modes in the stellar disk of spiral galaxies and its relationship to the QSSS hypothesis, where the central theoretical concepts involve waves with negative and positive surface densities of energy and angular

  20. Spiral arms as cosmic ray source distributions

    Science.gov (United States)

    Werner, M.; Kissmann, R.; Strong, A. W.; Reimer, O.

    2015-04-01

    The Milky Way is a spiral galaxy with (or without) a bar-like central structure. There is evidence that the distribution of suspected cosmic ray sources, such as supernova remnants, are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We investigate and measure how the propagation of Galactic cosmic rays is affected by a cosmic ray source distribution associated with spiral arm structures. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar finding have been obtained for low energy protons and electrons albeit at smaller magnitude. We find that even fractional contributions of a spiral arm component to the total cosmic ray source distribution influences the spectra on the Earth. This is apparent when compared to an axisymmetric radial source distribution as well as with respect to the Earth's position relative to the spiral arm structure. We demonstrate that the presence of a Galactic bar manifests itself as an overall excess of low energy electrons at the Earth. Using a spiral arm geometry as a cosmic ray source distributions offers a genuine new quality of modeling and is used to explain features in cosmic ray spectra at the Earth

  1. IR STAR FORMING KNOTS IN GRAND DESIGN SPIRAL GALAXIES: SPIRAL STRUCTURE STAR FORMATION CONNECTION

    Directory of Open Access Journals (Sweden)

    H. Dottori

    2009-01-01

    Full Text Available We are studying 46 Grand Design spirals widely spread in types, which have been imaged in the K-band with the ESO NTT telescope. Eleven objects show knots strongly associated to the m=2 Fourier component of the spiral structure. Corotation ressonance (CR for the two-armed pattern have been derived for ve galaxies.

  2. Scintigraphic examinations during pregnancy and in breast-feeding women: a survey of Belgian nuclear medicine physician's attitudes; Examens scintigraphiques durant la grossesse et chez les femmes en periode d'allaitement: enquete a propos des attitudes pratiques des nuclearistes belges

    Energy Technology Data Exchange (ETDEWEB)

    Tondeur, M.; Ham, H. [Centre Hospitalier Universitaire Saint Pierre, Bruxellex (Belgium); Sand, A. [CEDRI, Vilvoorde (Belgium)

    2003-05-01

    Radiation protection is of major importance in pregnant and breast feeding women. This work was undertaken to assess the practices of Belgian nuclear medicine physicians towards performing diagnostic tests during pregnancy and in breast feeding women. A questionnaire was sent to 201 Belgian nuclear medicine physicians; 82 answers (41 %) were received. 51 % of the responding physicians agree to perform lung perfusion scan during pregnancy provided a reduced dose is administered, 33% refuse to perform it during first three months and 24% refuse to perform it for pregnancies older than three months. For the Tc-99m ventilation scan 79% and 66% refuse to perform it before and after first three months. Better agreement was observed for other Tc-99m scintigraphies or tests using other radionuclides. In breast feeding women 89% agree to perform Tc-99m tests provided a breast feeding break; however, the duration of this break appears variable. The need for obtaining a written informed consent appears controversial. Given the variability of the attitudes of nuclear medicine physicians, official guidelines for nuclear medicine diagnostic tests during pregnancy is needed. (authors)

  3. Observational Confirmations of Spiral Density Wave Theory

    Science.gov (United States)

    Kennefick, Julia D.; Kennefick, Daniel; Shameer Abdeen, Mohamed; Berrier, Joel; Davis, Benjamin; Fusco, Michael; Pour Imani, Hamed; Shields, Doug; DMS, SINGS

    2017-01-01

    Using two techniques to reliably and accurately measure the pitch angles of spiral arms in late-type galaxies, we have compared pitch angles to directly measured black hole masses in local galaxies and demonstrated a strong correlation between them. Using the relation thus established we have developed a pitch angle distribution function of a statistically complete volume limited sample of nearby galaxies and developed a central black hole mass function for nearby spiral galaxies.We have further shown that density wave theory leads us to a three-way correlation between bulge mass, pitch angle, and disk gas density, and have used data from the Galaxy Disk Mass Survey to confirm this possible fundamental plane. Density wave theory also predicts that the pitch angle of spiral arms should change with observed waveband as each waveband is sampling a different stage in stellar population formation and evolution. We present evidence that this is indeed the case using a sample of galaxies from the Spitzer Infrared Nearby Galaxy Survey. Furthermore, the evolved spiral arms cross at the galaxy co-rotation radius. This gives a new method for determining the co-rotation radius of spiral galaxies that is found to agree with those found using previous methods.

  4. Spiral Arms as Cosmic Ray Source Distributions

    CERN Document Server

    Werner, M; Strong, A W; Reimer, O

    2014-01-01

    There is evidence that the distribution of suspected cosmic ray sources are associated with the spiral arm structure of galaxies. It is yet not clearly understood what effect such a cosmic ray source distribution has on the particle transport in our Galaxy. We use the PICARD code to perform high-resolution 3D simulations of electrons and protons in galactic propagation scenarios that include four-arm and two-arm logarithmic spiral cosmic ray source distributions with and without a central bar structure as well as the spiral arm configuration of the NE2001 model for the distribution of free electrons in the Milky Way. Results of these simulation are compared to an axisymmetric radial source distribution. Also, effects on the cosmic ray flux and spectra due to different positions of the Earth relative to the spiral structure are studied. We find that high energy electrons are strongly confined to their sources and the obtained spectra largely depend on the Earth's position relative to the spiral arms. Similar f...

  5. Mathematical Modeling of Spiral Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Probal Guha , Vaishnavi Unde

    2014-04-01

    Full Text Available Compact Heat Exchangers (CHEs are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat exchanger.The design considerations for spiral heat exchanger is that the flow within the spiral has been assumed as flow through a duct and by using Shah London empirical equation for Nusselt number design parameters are further optimized.This is accompanied by a detailed energy balance to generate a concise mathematical model

  6. Discontinuous spirals of stable periodic oscillations.

    Science.gov (United States)

    Sack, Achim; Freire, Joana G; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A C

    2013-11-27

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.

  7. Discontinuous Spirals of Stable Periodic Oscillations

    Science.gov (United States)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A. C.

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators. PMID:24284508

  8. Cloud and Star Formation in Spiral Arms

    CERN Document Server

    Dobbs, Clare

    2014-01-01

    We present the results from simulations of GMC formation in spiral galaxies. First we discuss cloud formation by cloud-cloud collisions, and gravitational instabilities, arguing that the former is prevalent at lower galactic surface densities and the latter at higher. Cloud masses are also limited by stellar feedback, which can be effective before clouds reach their maximum mass. We show other properties of clouds in simulations with different levels of feedback. With a moderate level of feedback, properties such as cloud rotations and virial parameters agree with observations. Without feedback, an unrealistic population of overly bound clouds develops. Spiral arms are not found to trigger star formation, they merely gather gas into more massive GMCs. We discuss in more detail interactions of clouds in the ISM, and argue that these are more complex than early ideas of cloud-cloud collisions. Finally we show ongoing work to determine whether the Milky Way is a flocculent or grand design spiral.

  9. How Different are Normal and Barred Spirals?

    CERN Document Server

    Bergh, Sidney van den

    2011-01-01

    No significant color differences are found between normal and barred spirals over the range of Hubble stages a - ab - b - bc. Furthermore, no significant difference is seen between the luminosity distributions of normal and barred galaxies over the same range of Hubble stages. However, SBc galaxies are found to be systematically fainter than Sc galaxies at 99% confidence. The observation that normal and barred spirals with Hubble stages a - ab - b - bc have indistinguishable intrinsic colors hints at the possibility that the bars in such spiral galaxies might be ephemeral structures. Finally, it is pointed out that lenticular galaxies of types S0 and SB0 are systematically fainter than are other early-type galaxies, suggesting that such galaxies are situated on evolutionary tracks that differ systematically from those of galaxies that lie along the E - Sa - Sb -Sc and E - SBa - SBb - SBc sequences.

  10. Circularly symmetric light scattering from nanoplasmonic spirals.

    Science.gov (United States)

    Trevino, Jacob; Cao, Hui; Dal Negro, Luca

    2011-05-11

    In this paper, we combine experimental dark-field imaging, scattering, and fluorescence spectroscopy with rigorous electrodynamics calculations in order to investigate light scattering from planar arrays of Au nanoparticles arranged in aperiodic spirals with diffuse, circularly symmetric Fourier space. In particular, by studying the three main types of Vogel's spirals fabricated by electron-beam lithography on quartz substrates, we demonstrate polarization-insensitive planar light diffraction in the visible spectral range. Moreover, by combining dark-field imaging with analytical multiparticle calculations in the framework of the generalized Mie theory, we show that plasmonic spirals support distinctive structural resonances with circular symmetry carrying orbital angular momentum. The engineering of light scattering phenomena in deterministic structures with circular Fourier space provides a novel strategy for the realization of optical devices that fully leverage on enhanced, polarization-insensitive light-matter coupling over planar surfaces, such as thin-film plasmonic solar cells, plasmonic polarization devices, and optical biosensors.

  11. The finite element modeling of spiral ropes

    Institute of Scientific and Technical Information of China (English)

    Juan Wu

    2014-01-01

    Accurate understanding the behavior of spiral rope is complicated due to their complex geometry and complex contact conditions between the wires. This study proposed the finite element models of spiral ropes subjected to tensile loads. The parametric equations developed in this paper were implemented for geometric modeling of ropes. The 3D geometric models with different twisting manner, equal diameters of wires were generated in details by using Pro/ENGINEER software. The results of the present finite element analysis were on an acceptable level of accuracy as compared with those of theoretical and experimental data. Further development is ongoing to analysis the equivalent stresses induced by twisting manner of cables. The twisting manner of wires was important to spiral ropes in the three wire layers and the outer twisting manner of wires should be contrary to that of the second layer, no matter what is the first twisting manner of wires.

  12. The neutrons for science facility at SPIRAL-2

    Science.gov (United States)

    Ledoux, X.; Aïche, M.; Avrigeanu, M.; Avrigeanu, V.; Balanzat, E.; Ban-d'Etat, B.; Ban, G.; Bauge, E.; Bélier, G.; Bém, P.; Borcea, C.; Caillaud, T.; Chatillon, A.; Czajkowski, S.; Dessagne, P.; Doré, D.; Fischer, U.; Frégeau, M. O.; Grinyer, J.; Guillous, S.; Gunsing, F.; Gustavsson, C.; Henning, G.; Jacquot, B.; Jansson, K.; Jurado, B.; Kerveno, M.; Klix, A.; Landoas, O.; Lecolley, F. R.; Lecouey, J. L.; Majerle, M.; Marie, N.; Materna, T.; Mrázek, J.; Negoita, F.; Novák, J.; Oberstedt, S.; Oberstedt, A.; Panebianco, S.; Perrot, L.; Plompen, A. J. M.; Pomp, S.; Prokofiev, A. V.; Ramillon, J. M.; Farget, F.; Ridikas, D.; Rossé, B.; Sérot, O.; Simakov, S. P.; Šimečková, E.; Štefánik, M.; Sublet, J. C.; Taïeb, J.; Tarrío, D.; Tassan-Got, L.; Thfoin, I.; Varignon, C.

    2017-09-01

    Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliable measurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS) is being built for this purpose on the GANIL site at Caen (France). NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40 MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented.

  13. The neutrons for science facility at SPIRAL-2

    Directory of Open Access Journals (Sweden)

    Ledoux X.

    2017-01-01

    Full Text Available Numerous domains, in fundamental research as well as in applications, require the study of reactions induced by neutrons with energies from few MeV up to few tens of MeV. Reliable measurements also are necessary to improve the evaluated databases used by nuclear transport codes. This energy range covers a large number of topics like transmutation of nuclear waste, design of future fission and fusion reactors, nuclear medicine or test and development of new detectors. A new facility called Neutrons For Science (NFS is being built for this purpose on the GANIL site at Caen (France. NFS is composed of a pulsed neutron beam for time-of-flight facility as well as irradiation stations for cross-section measurements. Neutrons will be produced by the interaction of deuteron and proton beams, delivered by the SPIRAL-2 linear accelerator, with thick or thin converters made of beryllium or lithium. Continuous and quasi-mono-energetic spectra will be available at NFS up to 40 MeV. In this fast energy region, the neutron flux is expected to be up to 2 orders of magnitude higher than at other existing time-of-flight facilities. In addition, irradiation stations for neutron-, proton- and deuteron-induced reactions will allow performing cross-section measurements by the activation technique. After a description of the facility and its characteristics, the experiments to be performed in the short and medium term will be presented.

  14. Inwardly rotating spirals in nonuniform excitable media.

    Science.gov (United States)

    Gao, Xiang; Feng, Xia; Cai, Mei-chun; Li, Bing-wei; Ying, He-ping; Zhang, Hong

    2012-01-01

    Inwardly rotating spirals (IRSs) have attracted great attention since their observation in an oscillatory reaction-diffusion system. However, IRSs have not yet been reported in planar excitable media. In the present work we investigate rotating waves in a nonuniform excitable medium, consisting of an inner disk part surrounded by an outer ring part with different excitabilities, by numerical simulations of a simple FitzHugh-Nagumo model. Depending on the excitability of the medium as well as the inhomogeneity, we find the occurrence of IRSs, of which the excitation propagates inwardly to the geometrical spiral tip.

  15. TRIGGERED STAR FORMATION IN SPIRAL ARMS

    Directory of Open Access Journals (Sweden)

    E. E. Martínez-García

    2009-01-01

    Full Text Available We present the status of our research, relative to the triggering of star formation by large-scale galactic shocks associated with spiral density waves. Around a third of the galaxies in our sample do not seem suitable for this kind of study, because they present an e ect, probably due to opacity, that is not well understood. The remaining objects seem to favor the idea of density wave triggering of star formation in the arms. The comparison with stellar population synthesis models, and the orbital resonance positions for these galaxies (derived by means of spiral pattern angular speeds corroborate this hypothesis.

  16. Beautiful math--aesthetic patterns based on logarithmic spirals.

    Science.gov (United States)

    Xinchang Wang; Peichang Ouyang

    2013-01-01

    A simple, fast method generates various visually appealing spiral patterns. The method is based on the concept that spiral patterns comprise a symmetry group of tilings. It employs invariant mappings and a dynamical system to create seamless colored patterns.

  17. Controlling spiral wave with target wave in oscillatory systems

    Institute of Scientific and Technical Information of China (English)

    Liu Fu-Cheng; Wang Xiao-Fei; Li Xue-Chen; Dong Li-Fang

    2007-01-01

    Spiral waves have been controlled by generating target waves with a localized inhomogeneity in the oscillatory medium. The competition between the spiral waves and target waves is discussed. The effect of the localized inhomogeneity size has also been studied.

  18. SPIRAL2 at GANIL: At the Dawn of a New Era

    Science.gov (United States)

    Gales, S.

    2010-04-01

    The exploration of unknown region of the nuclear mass chart, in particular, the neutron rich side, raised new and challenging physics issues in the understanding of nuclei far from stability. The physics of weakly bound systems, the appearance of shell quenching, the interface with astrophysical problems prompted the study of new generation of "Rad ioactive Beam Facilities" with high luminosity and the development of associated new experimental tools. GANIL presently offers unique opportunities in nuclear physics and many other fields. With the construction of SPIRAL2 over the next few years, GANIL is in a good position to retain its world-leading capability even though it faces strong competition from new and upgraded ISOL and fragmentation facilities. As selected by the ESFRI committee, the next generation of ISOL facility in Europe is represented by the SPIRAL2 project to be built at GANIL (Caen, France). SPIRAL2 is based on a high power, CW, superconducting LINAC, delivering 5 mA of deuteron beams at 40 MeV (200 KW) directed on a C converter+ Uranium target and producing therefore more 1013 fissions/s. The expected radioactive beams intensities in the mass range from A = 60 to A = 140, will surpass by two order of magnitude any existing facilities in the world. These unstable atoms will be available at energies between few KeV/n to 15 MeV/n. The same driver will accelerate high intensity (100* A to 1 mA), heavier ions (Ar up to Xe) at maximum energy of 14 MeV/n. In applied areas SPIRAL2 is considered as a powerful variable energy neutron source. The Neutrons For Science collaboration (NFS) is proposing a physics program on fission induced by fast neutrons as well as fusion studies on materials. Under the 7FP program of European Union called*Preparatory phase*, the SPIRAL2 project has been granted a budget of about 4 M€ to build up an international consortium around this new venture. Regarding the future physics program a call for Letter of intents has been

  19. Evolution of Spiral Waves under Modulated Electric Fields

    Institute of Scientific and Technical Information of China (English)

    MA Jun; YING He-Ping; PAN Guo-Wei; PU Zhong-Sheng

    2005-01-01

    @@ Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.

  20. A Non-invasive Method of Tracing Spiral Tips

    Institute of Scientific and Technical Information of China (English)

    王凯; 毛晓明; 欧阳颀

    2001-01-01

    A new method is developed to trace the tip of spiral waves in an excitable medium. The information of a spiraltip movement is obtained from only six probes. This method can trace the tip of a simple rotating spiral as wellas a complex spiral tip movement. More importantly, it can be used to distinguish between a spiral and a targetwave. The method is checked with data by experiments and numerical simulations, and found to be successful.

  1. Spiral Waves in Media with Spatial Period-2 Structure

    Institute of Scientific and Technical Information of China (English)

    YANG Jun-Zhong; ZHANG Mei

    2005-01-01

    @@ The spiral waves in a system of two-dimensional coupled oscillators with spatial period-2 structure are investigated.We find a sandwiched spiral wave where any adjacent oscillators are in anti-phase. We show that the propagation rate of the sandwiched spiral wave is insensitive to the change of the coupling constant. The influences of the local kinetics on the sandwiched spiral wave are also investigated.

  2. Short WSRT HI observations of spiral galaxies

    NARCIS (Netherlands)

    Rhee, MH; vanAlbada, TS

    1996-01-01

    We have obtained short HI observations of 60 late type spiral galaxies with the Westerbork Synthesis Radio Telescope (WSRT). Several HI properties are presented, including the radial surface density distribution of HI and a position-velocity map. When possible these are compared to those measured fr

  3. Spiral kicker for the beam abort system

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.L.

    1983-01-01

    A brief study was carried out to determine the feasibility of a special kicker to produce a damped spiral beam at the beam dump for the beam abort system. There appears to be no problem with realizing this concept at a reasonably low cost.

  4. How to make a spiral bacterium

    Science.gov (United States)

    Wolgemuth, Charles W.; Inclan, Yuki F.; Quan, Julie; Mukherjee, Sulav; Oster, George; Koehl, M. A. R.

    2005-09-01

    The motility of some kinds of bacteria depends on their spiral form, as does the virulence of certain pathogenic species. We propose a novel mechanism for the development of spiral shape in bacteria and the supercoiling of chains ('filaments') of many cells. Recently discovered actin-like proteins lying just under the cell wall form fibers that play a role in maintaining cell shape. Some species have a single actin-like fiber helically wrapped around the cell, while others have two fibers wrapped in the same direction. Here, we show that if these fibers elongate more slowly than growth lengthens the cell, the cell both twists and bends, taking on a spiral shape. We tested this mechanism using a mathematical model of expanding fiber-wound structures and via experiments that measure the shape changes of elongating physical models. Comparison of the model with in vivo experiments on stationary phase Caulobacter crescentus filaments provide the first evidence that mechanical stretching of cytoskeletal fibers influences cell morphology. Any hydraulic cylinder can spiral by this mechanism if it is reinforced by stretch-resistant fibers wrapped helically in the same direction, or shortened by contractile elements. This might be useful in the design of man-made actuators.

  5. Some optical properties of the spiral inflector

    CERN Document Server

    Toprek, D

    1999-01-01

    This paper compares some optical properties of different spiral inflectors using the program CASINO. The electric field distribution in the inflectors has been numerically calculated from an electric potential map produced by the program RELAX3D. The magnetic field is assumed to be constant. We have also made an effort to minimize the inflector fringe field using the RELAX3D program. (author)

  6. Maximum life spiral bevel reduction design

    Science.gov (United States)

    Savage, M.; Prasanna, M. G.; Coe, H. H.

    1992-07-01

    Optimization is applied to the design of a spiral bevel gear reduction for maximum life at a given size. A modified feasible directions search algorithm permits a wide variety of inequality constraints and exact design requirements to be met with low sensitivity to initial values. Gear tooth bending strength and minimum contact ratio under load are included in the active constraints. The optimal design of the spiral bevel gear reduction includes the selection of bearing and shaft proportions in addition to gear mesh parameters. System life is maximized subject to a fixed back-cone distance of the spiral bevel gear set for a specified speed ratio, shaft angle, input torque, and power. Significant parameters in the design are: the spiral angle, the pressure angle, the numbers of teeth on the pinion and gear, and the location and size of the four support bearings. Interpolated polynomials expand the discrete bearing properties and proportions into continuous variables for gradient optimization. After finding the continuous optimum, a designer can analyze near optimal designs for comparison and selection. Design examples show the influence of the bearing lives on the gear parameters in the optimal configurations. For a fixed back-cone distance, optimal designs with larger shaft angles have larger service lives.

  7. The handedness of historiated spiral columns.

    Science.gov (United States)

    Couzin, Robert

    2016-11-17

    Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.

  8. Arm Structure in Anemic Spiral Galaxies

    CERN Document Server

    Elmegreen, D M; Frogel, J A; Eskridge, P B; Pogge, R W; Gallagher, A; Iams, J; Elmegreen, Debra Meloy; Elmegreen, Bruce G.; Frogel, Jay A.; Eskridge, Paul B.; Pogge, Richard W.; Gallagher, Andrew; Iams, Joel

    2002-01-01

    Anemic galaxies have less prominent star formation than normal galaxies of the same Hubble type. Previous studies showed they are deficient in total atomic hydrogen but not in molecular hydrogen. Here we compare the combined surface densities of HI and H2 at mid-disk radii with the Kennicutt threshold for star formation. The anemic galaxies are below threshold, which explains their lack of prominent star formation, but they are not much different than other early type galaxies, which also tend to be below threshold. The spiral wave amplitudes of anemic and normal galaxies were also compared, using images in B and J passbands from the OSU Bright Spiral Galaxy Survey. Anemic galaxies have normal spiral wave properties too, with the same amplitudes and radial dependencies as other galaxies of the same arm class. Because of the lack of gas, spiral waves in early type galaxies and anemics do not have a continuous supply of stars with low velocity dispersions to maintain a marginally stable disk. As a result, they ...

  9. Investigation of Spiral and Sweeping Holes

    Science.gov (United States)

    Thurman, Douglas; Poinsatte, Philip; Ameri, Ali; Culley, Dennis; Raghu, Surya; Shyam, Vikram

    2015-01-01

    Surface infrared thermography, hotwire anemometry, and thermocouple surveys were performed on two new film cooling hole geometries: spiral/rifled holes and fluidic sweeping holes. The spiral holes attempt to induce large-scale vorticity to the film cooling jet as it exits the hole to prevent the formation of the kidney shaped vortices commonly associated with film cooling jets. The fluidic sweeping hole uses a passive in-hole geometry to induce jet sweeping at frequencies that scale with blowing ratios. The spiral hole performance is compared to that of round holes with and without compound angles. The fluidic hole is of the diffusion class of holes and is therefore compared to a 777 hole and Square holes. A patent-pending spiral hole design showed the highest potential of the non-diffusion type hole configurations. Velocity contours and flow temperature were acquired at discreet cross-sections of the downstream flow field. The passive fluidic sweeping hole shows the most uniform cooling distribution but suffers from low span-averaged effectiveness levels due to enhanced mixing. The data was taken at a Reynolds number of 11,000 based on hole diameter and freestream velocity. Infrared thermography was taken for blowing rations of 1.0, 1.5, 2.0, and 2.5 at a density ration of 1.05. The flow inside the fluidic sweeping hole was studied using 3D unsteady RANS.

  10. Colloidal spirals in nematic liquid crystals.

    Science.gov (United States)

    Senyuk, Bohdan; Pandey, Manoj B; Liu, Qingkun; Tasinkevych, Mykola; Smalyukh, Ivan I

    2015-12-07

    One of the central experimental efforts in nematic colloids research aims to explore how the interplay between the geometry of particles along with the accompanying nematic director deformations and defects around them can provide a means of guiding particle self-assembly and controlling the structure of particle-induced defects. In this work, we design, fabricate, and disperse low-symmetry colloidal particles with shapes of spirals, double spirals, and triple spirals in a nematic fluid. These spiral-shaped particles, which are controlled by varying their surface functionalization to provide tangential or perpendicular boundary conditions of the nematic molecular alignment, are found inducing director distortions and defect configurations with non-chiral or chiral symmetry. Colloidal particles also exhibit both stable and metastable multiple orientational states in the nematic host, with a large number of director configurations featuring both singular and solitonic nonsingular topological defects accompanying them, which can result in unusual forms of colloidal self-assembly. Our findings directly demonstrate how the symmetry of particle-generated director configurations can be further lowered, or not, as compared to the low point group symmetry of solid micro-inclusions, depending on the nature of induced defects while satisfying topological constraints. We show that achiral colloidal particles can cause chiral symmetry breaking of elastic distortions, which is driven by complex three-dimensional winding of induced topological line defects and solitons.

  11. Biofouling of spiral wound membrane systems

    NARCIS (Netherlands)

    Vrouwenvelder, J.S.

    2009-01-01

    Biofouling of spiral wound membrane systems High quality drinking water can be produced with membrane filtration processes like reverse osmosis (RO) and nanofiltration (NF). Because the global demand for fresh clean water is increasing, these membrane technologies will increase in importance in the

  12. Development of phantoms for spiral CT.

    Science.gov (United States)

    Goodenough, D J; Levy, J R; Kasales, C

    1998-01-01

    This paper reports on the development of a new phantom for spiral CT. The phantom meets the increased demands on phantom z-axis uniformity in order that objects from the CT slice, immediately above and below the CT slice of interest, do not contribute perturbing information to the reconstructed CT slice. The phantom depends on formulation of tissue-like materials that can be cast and produced in both geometric and anthropomorphic shapes with sufficient z-axis length to enable unperturbed CT slices of test objects of interest. These materials are then used to produce a series of test objects of CT image quality including low contrast samples that do not require volume averaging or mixing of solutions, and that can reflect sub-slice thickness test objects and supra-slice thickness test objects. The overall phantom and its individual test objects provides meaningful tests of spiral CT image quality including slice sensitivity, CT number linearity and tests of high and low contrast resolution. Schematic designs and actual CT scans are shown. The new spiral phantom appears to meet the increased demands of spiral CT on phantom design, particularly z-axis length, and requirements for low contrast resolution test objects.

  13. The Spiral Curriculum. Research into Practice

    Science.gov (United States)

    Johnston, Howard

    2012-01-01

    The Spiral Curriculum is predicated on cognitive theory advanced by Jerome Bruner (1960), who wrote, "We begin with the hypothesis that any subject can be taught in some intellectually honest form to any child at any stage of development." In other words, even the most complex material, if properly structured and presented, can be understood by…

  14. Curved spiral antennas for underwater biological applications

    Science.gov (United States)

    Llamas, Ruben

    We developed curved spiral antennas for use in underwater (freshwater) communications. Specifically, these antennas will be integrated in so-called mussel backpacks. Backpacks are compact electronics that incorporate sensors and a small radio that operate around 300 MHz. Researchers attach these backpacks in their freshwater mussel related research. The antennas must be small, lightweight, and form-fit the mussel. Additionally, since the mussel orientation is unknown, the antennas must have broad radiation patterns. Further, the electromagnetic environment changes significantly as the mussels burrow into the river bottom. Broadband antennas, such a spiral antennas, will perform better in this instance. While spiral antennas are well established, there has been little work on their performance in freshwater. Additionally, there has been some work on curved spiral antennas, but this work focused on curving in one dimension, namely curving around a cylinder. In this thesis we develop spiral antennas that curve in two dimensions in order to conform the contour of a mussel's shell. Our research has three components, namely (a) an investigation of the relevant theoretical underpinning of spiral antennas, (b) extensive computer simulations using state-of-the art computational electromagnetics (CEM) simulation software, and (c) experimental validation. The experimental validation was performed in a large tank in a laboratory setting. We also validated some designs in a pool (~300,000 liters of water and ~410 squared-meter dive pool) with the aid of a certified diver. To use CEM software and perform successful antenna-related experiments require careful attention to many details. The mathematical description of radiation from an antenna, antenna input impedance and so on, is inherently complex. Engineers often make simplifying assumptions such as assuming no reflections, or an isotropic propagation environment, or operation in the antenna far field, and so on. This makes

  15. Development of a surface micromachined spiral-channel viscous pump

    Science.gov (United States)

    Kilani, Mohammad Ibrahim

    This work introduces a new pump, called the spiral pump, which targets the surface micromachining technology. We demonstrate the possibility of realizing the spiral pump geometry in standard surface micromachining, lay out the theoretical foundation for its operation, and conduct an objective assessment for its practicality. The spiral pump is a shear-driven viscous pump, which works by rotating a disk with a spiral groove at a close proximity over a stationary plate. Fluid contained in the spiral groove between the stationary plate and the rotating disk, is subject to a net tangential viscous stress, which allows it to be transported against an imposed pressure difference. A number of spiral pumps were fabricated in 5 levels of polysilicon using Sandia's Ultraplanar Multilevel Surface Micromachining Technology, SUMMiT, and the fabricated micropump were tested in dry-run mode using electrostatic probing and optical microscopy. To achieve a more comprehensive understanding of the spiral micropump operation, an analytical model was developed for the flow field in the spiral channel of the pump using an approximation which replaces the spiral channel with an equivalent straight channel with appropriate dimensions and boundary conditions. An analytical solution for this model at the lubrication limit relates the flow rate, torque and power consumption of the spiral pump to the pressure difference and rotation rate. The model was validated using macroscale experiments conducted on a scaled up spiral pump model, which involved a quantitative characterization of the spiral pump performance. Those experiments validate the developed theory and help assess the practicality of the spiral pump concept. In addition to the spiral pump, two positive-displacement ring-gear pumps were designed and fabricated in this work. The feasibility of surface micromachined ring-gear pumps is briefly investigated in this work, and compare to that of the spiral micropump.

  16. Spiral CT for evaluation of chest trauma; Spiral-CT beim Thoraxtrauma

    Energy Technology Data Exchange (ETDEWEB)

    Roehnert, W. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik; Weise, R. [Universitaetsklinikum Dresden (Germany). Inst. und Poliklinik fuer Radiologische Diagnostik

    1997-07-01

    After implementation of spiral CT in our department, we carried out an analysis for determining anew the value of CT as a modality of chest trauma diagnosis in the emergency department. The retrospective study covers a period of 10 months and all emergency patients with chest trauma exmined by spiral CT. The major lesions of varying seriousness covered by this study are: pneumothorax, hematothorax, pulmonary contusion or laceration, mediastinal hematoma, rupture of a vessel, injury of the heart and pericardium. The various fractures are not included in this study. In many cases, spiral CT within relatively short time yields significant diagnostic findings, frequently saving additional angiography. A rigid diagnostic procedure cannot be formulated. Plain-film chest radiography still remains a diagnostic modality of high value. (Orig.) [Deutsch] Nach Einfuehrung der Spiral-CT in unserer Einrichtung versuchten wir, den Stellenwert der Computertomographie in der Notfalldiagnostik des Thoraxtraumas neu zu bestimmen. Dazu wurden retrospektiv ueber einen Zeitraum von 10 Monaten alle mittels Spiral-CT untersuchten Notfallpatienten mit Thoraxverletzungen ausgewertet. Im Vordergrund standen folgende Befunde unterschiedlichen Schweregrades: Pneumothorax, Haematothorax, Lungenkontusion/-lazeration, Mediastinalhaematom, Gefaessruptur, Herz- und Herzbeutelverletzung. Auf die unterschiedlichen Frakturen wird bewusst nicht naeher eingegangen. In vielen Faellen liefert die Spiral-CT mit relativ geringem Zeitaufwand wesentliche diagnostische Aussagen. Haeufig kann auf eine Angiographie verzichtet werden. Ein starres diagnostisches Stufenschema laesst sich nicht definieren. Die Thoraxuebersichtsaufnahme besitzt einen unveraendert hohen Stellenwert. (orig.)

  17. The Geometry of the Galaxy's Spiral Arms

    Science.gov (United States)

    Steiman-Cameron, Thomas Y.; Wolfire, M.; Hollenbach, D.

    2008-05-01

    We present a new model for the spiral structure of the Milky Way based upon an analysis of the essentially all-sky spectral data obtained by the Far Infrared Absolute Spectrophotometer (FIRAS) instrument of the Cosmic Background Explorer (COBE) satellite. The model provides the volume emissivities of the [C II] 128 µm and [N II] 205 µm lines, as a function of position within the Galaxy. These lines are important coolants of the interstellar medium and strong tracers of the spiral structure. Despite decades of work, there is still no full agreement on the number of spiral arms in the Milky Way, much less the details of their geometry. Motivated, in part, by this fact, we conducted a systematic search for 2-arm, 3-arm, and 4-arm models that maximize agreement with the COBE data. We find that only a four-arm model, with arms defined by logarithmic spiral forms and pitch angles ranging from 13.5 to 15.6 degrees, is consistent with the observations. The arms are neither evenly spaced nor identical in form. The resultant volume emissivity models for C+ and N+, when convolved with the FIRAS beam and integrated over the Galaxy, reproduce the COBE [C II] 128 µm and [N II] 205 µm intensity maps extremely well. We also examine all models for the Galaxy's spiral structure that have been proposed over the past half century in the context of the same COBE observations. A significant fraction of these models, including many recent ones, appear to be incompatible with the data. However, several four-arm models from the literature are consistent with the COBE observations.

  18. Safe Control for Spiral Recovery of Unmanned Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Chang-Jian Ru

    2014-01-01

    Full Text Available With unmanned aerial vehicles (UAVs widely used in both military and civilian fields, many events affecting their safe flying have emerged. That UAV’s entering into the spiral is such a typical safety issue. To solve this safety problem, a novel recovery control approach is proposed. First, the factors of spiral are analyzed. Then, based on control scheduling of state variables and nonlinear dynamic inversion control laws, the spiral recovery controller is designed to accomplish guidance and control of spiral recovery. Finally, the simulation results have illustrated that the proposed control method can ensure the UAV autonomous recovery from spiral effectively.

  19. Analysis of the spiral structure in a simulated galaxy

    CERN Document Server

    Mata-Chávez, Dolores; Puerari, Ivânio

    2014-01-01

    We analyze the spiral structure that results in a numerical simulation of a galactic disk with stellar and gaseous components evolving in a potential that includes an axisymmetric halo and bulge. We perform a second simulation without the gas component to observe how it affects the spiral structure in the disk. To quantify this, we use a Fourier analysis and obtain values for the pitch angle and the velocity of the self-excited spiral pattern of the disk. The results show a tighter spiral in the simulation with gaseous component. The spiral structure is consistent with a superposition of waves, each with a constant pattern velocity in given radial ranges.

  20. Oxygen and nitrogen abundances in Virgo and field spirals

    OpenAIRE

    Pilyugin, L. S.; Molla, Mercedes; Ferrini, Federico; Vilchez, Jose M.

    2001-01-01

    The oxygen and nitrogen abundances in the HII regions of the nine Virgo spirals of the sample from Skillman et al (1996) and in nine field spiral galaxies are re-determined with the recently suggested P - method. We confirm that there is an abundance segregation in the sample of Virgo spirals in the sense that the HI deficient Virgo spirals near the core of the cluster have higher oxygen abundances in comparison to the spirals at the periphery of the Virgo cluster. At the same time both the V...

  1. Breakup of Spiral Waves in Coupled Hindmarsh-Rose Neurons

    Institute of Scientific and Technical Information of China (English)

    MA Jun; JIA Ya; TANG Jun; YANG Li-Jian

    2008-01-01

    @@ Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported.Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gauesian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively.Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave.It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold.

  2. 核电厂电动主给水泵调速系统研究及改进%Research and Improvement of the Speed Regulation System of Motor Driven Main Feed Water Pump in Nuclear Power Plant

    Institute of Scientific and Technical Information of China (English)

    张冲; 王旭峰

    2015-01-01

    对核电厂电动主给水泵( APA)的调速系统进行了研究,并针对手动调速模式下给水泵转速调节幅度过大的工程问题进行了研究及验证. 研究及验证采用理论研究结合现场试验的方式. 理论研究主要集中在手动调速和自动调速两个可编程逻辑控制器( PLC)程序,再经过现场的实际操作进行结果验证,最终及时解决了以上问题.%The research on speed regulation system of motor driven main feed water pump in nuclear power plant is conducted, and the engineering problem of excessive adjusting amplitude for the speed in manual operating mode is researched and validated. The way of research and validation is theoretical research combining with field tests;theoretic research is mainly focused on controlling the PLC programs for manual regulation and automatic regulation of the speed, and then the results are validated through practical operation on site, finally above problem is resolved promptly.

  3. Spiral analysis-improved clinical utility with center detection.

    Science.gov (United States)

    Wang, Hongzhi; Yu, Qiping; Kurtis, Mónica M; Floyd, Alicia G; Smith, Whitney A; Pullman, Seth L

    2008-06-30

    Spiral analysis is a computerized method that measures human motor performance from handwritten Archimedean spirals. It quantifies normal motor activity, and detects early disease as well as dysfunction in patients with movement disorders. The clinical utility of spiral analysis is based on kinematic and dynamic indices derived from the original spiral trace, which must be detected and transformed into mathematical expressions with great precision. Accurately determining the center of the spiral and reducing spurious low frequency noise caused by center selection error is important to the analysis. Handwritten spirals do not all start at the same point, even when marked on paper, and drawing artifacts are not easily filtered without distortion of the spiral data and corruption of the performance indices. In this report, we describe a method for detecting the optimal spiral center and reducing the unwanted drawing artifacts. To demonstrate overall improvement to spiral analysis, we study the impact of the optimal spiral center detection in different frequency domains separately and find that it notably improves the clinical spiral measurement accuracy in low frequency domains.

  4. The formation of molecular clouds in spiral galaxies

    CERN Document Server

    Dobbs, C L

    2006-01-01

    We present Smoothed Particle Hydrodynamics (SPH) simulations of molecular cloud formation in spiral galaxies. These simulations model the response of a non-self-gravitating gaseous disk to a galactic potential. The formation of molecular gas occurs when cold ($T \\le 100$ K) gas is compressed during the passage of a spiral arm. The spiral arms display considerable structure and the molecular gas accumulates into dense clouds. We identify the formation of these structures as due to the dynamics of clumpy shocks, which perturb the orbits of particles passing through the spiral arm. In addition, the spiral shocks induce a large velocity dispersion in the spiral arms, comparable with the magnitude of the velocity dispersion observed in molecular clouds. The molecular clouds are largely confined to the spiral arms, since most molecular gas is photodissociated to atomic hydrogen upon leaving the arms. However a low photodissociation rate increases the amount of interarm molecular gas, and the possibility of molecula...

  5. Assessment of spiral CT pneumocolon in preoperative colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Can-Hui Sun; Zi-Ping Li; Quan-Fei Meng; Shen-Ping Yu; Da-Sheng Xu

    2005-01-01

    AIM: To investigate the value of spiral CT pneumocolon in preoperative colorectal carcinoma.METHODS: Spiral CT pneumocolon was performed prior to surgery in 64 patients with colorectal carcinoma. Spiral CT images were compared to specimens from the resected tumor.RESULTS: Spiral CT depicted the tumor in all patients.Comparison of spiral CT and histologic results showed that the sensitivity and specificity were 95.2%, 40.9% in detection of local invasion, and 75.0%, 90.9% in detection of lymph node metastasis. Compared to the Dukes classification,the disease was correctly staged as A in 6 of 18 patients,as B in 18 of 23, as C in 10 of 15, and as D in 7 of 8. Overall,spiral CT correctly staged 64.1% of patients.CONCLUSION: Spiral CT pneumocolon may be useful in the preoperative assessment of patients with colorectal carcinoma as a means for assisting surgical planning.

  6. Simulation of thin slot spirals and dual circular patch antennas using the finite element method with mixed elements

    Science.gov (United States)

    Gong, Jian; Volakis, John L.; Nurnberger, Michael W.

    1995-01-01

    This semi-annual report describes progress up to mid-January 1995. The report contains five sections all dealing with the modeling of spiral and patch antennas recessed in metallic platforms. Of significance is the development of decomposition schemes which separate the different regions of the antenna volume. Substantial effort was devoted to improving the feed model in the context of the finite element method (FEM). Finally, an innovative scheme for truncating finite element meshes is presented.

  7. Acute myocardial ischemia after aortic valve replacement: A comprehensive diagnostic evaluation using dynamic multislice spiral computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lembcke, Alexander [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)]. E-mail: alexander.lembcke@gmx.de; Hein, Patrick A. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Enzweiler, Christian N.H. [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Hoffmann, Udo [Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA (United States); Klessen, Christian [Department of Radiology, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany); Dohmen, Pascal M. [Department of Cardiovascular Surgery, Charite-Universitaetsmedizin Berlin, Freie Universitaet Berlin and Humboldt-Universitaet zu Berlin, Berlin (Germany)

    2006-03-15

    We describe the case of a 72-year-old man presenting with endocarditis and clinical signs of acute myocardial ischemia after biological aortic valve replacement. A comprehensive cardiac dynamic multislice spiral computed tomography demonstrated: (1) an endocarditic vegetation of the aortic valve; (2) a subvalvular leakage feeding a paravalvular pseudoaneurysm based on an aortic root abscess with subsequent compromise of the systolic blood flow in the left main coronary artery and the resulting myocardial perfusion deficit.

  8. Feeding the Monster

    Science.gov (United States)

    2005-10-01

    Near-infrared images of the active galaxy NGC 1097, obtained with the NACO adaptive optics instrument on ESO's Very Large Telescope, disclose with unprecedented detail a complex central network of filamentary structure spiralling down to the centre of the galaxy. These observations provide astronomers with new insights on how super-massive black holes lurking inside galaxies get fed. "This is possibly the first time that a detailed view of the channelling process of matter, from the main part of the galaxy down to the very end in the nucleus is released," says Almudena Prieto (Max-Planck Institute, Heidelberg, Germany), lead author of the paper describing these results. Located at a distance of about 45 million light-years in the southern constellation Fornax (the Furnace), NGC 1097 is a relatively bright, barred spiral galaxy seen face-on. At magnitude 9.5, and thus just 25 times fainter than the faintest object that can be seen with the unaided eye, it appears in small telescopes as a bright, circular disc. NGC 1097 is a very moderate example of an Active Galactic Nucleus (AGN), whose emission is thought to arise from matter (gas and stars) falling into oblivion in a central black hole. However, NGC 1097 possesses a comparatively faint nucleus only, and the black hole in its centre must be on a very strict "diet": only a small amount of gas and stars is apparently being swallowed by the black hole at any given moment. Astronomers have been trying to understand for a long time how the matter is "gulped" down towards the black hole. Watching directly the feeding process requires very high spatial resolution at the centre of galaxies. This can be achieved by means of interferometry as was done with the VLTI MIDI instrument on the central parts of another AGN, NGC 1068 (see ESO PR 17/03), or with adaptive optics [1]. Thus, astronomers [2] obtained images of NGC 1097 with the adaptive optics NACO instrument attached to Yepun, the fourth Unit Telescope of ESO's VLT

  9. UIT Ultraviolet Surface Photometry of the Spiral Galaxy M74

    Science.gov (United States)

    Cornett, R. H.; Greason, M. R.; Offenberg, J. D.; Bohlin, R. C.; Cheng, K. P.; O'Connell, R. W.; Roberts, M. R.; Smith, A. M.; Smith, E. P.; Angione, R. J.; Talbert, F. D.; Stecher, T. P.

    1993-05-01

    UV photometry from Ultraviolet Imaging Telescope (UIT) images at 1520 Angstroms (magnitudes mbone) and 2490 Angstroms (maone) of the spiral galaxy M74 (NGC628) is compared with ha, R, V, and B surface photometry and models. M74's surface brightness profiles have central peaks with exponential falloffs; the profiles' exponential scale lengths increase with decreasing continuum wavelength. The slope of the continuum-subtracted ha profile is between those of FUV and NUV profiles, consistent with related origins of ha and UV emission in extreme Population I material. M74's color profiles have small gradients, all becoming bluer with increasing radius. The UIT color (mbone-maone) averages near 0.0, the color of an A0 star, over the central 20 arcsec radius, and slopes from ~ -0.2 to ~ -0.4 from 20 to 200 arcsec. Spiral arms dominate surface photometry colors; interarm regions are slightly redder. In the UV, M74's nuclear region resembles disk/spiral arm material in color and morphology, unlike M81. (mbone-maone) colors and models of M74's central region clearly demonstrate that there are no O or B stars in the central 10 arcsec. M74's (mbone-maone) profile is similar to M33's but is ~ 0.5 mag redder. M74 is ~ 0.4 mag bluer than M81 in its outer disk. We investigate explanations for both the color profiles and the differences among the galaxies. M74's maone-V and mbone-V color profiles cannot be explained by a disk of uniform color behind a screen of dust with a known reddening function, distributed like the neutral gas with a fixed gas-to-dust ratio. Known abundance variations could produce the observed color gradient in M74; however, evolutionary cluster models show that sensible time parameters, including star formation start time and exponential decay rate, also produce the observed colors of M74, M33, and M81.

  10. Feeding Your Newborn

    Science.gov (United States)

    ... Old Feeding Your 1- to 2-Year-Old Feeding Your Newborn KidsHealth > For Parents > Feeding Your Newborn ... giving up the breast. previous continue About Formula Feeding Commercially prepared infant formula is a nutritious alternative ...

  11. Chemical milling of Zircaloy tubing to produce integral OD spiral finned tubes (AWBA development program)

    Energy Technology Data Exchange (ETDEWEB)

    Horwood, W.A.

    1982-02-01

    A detailed process description is provided for producing integral spiral fins on the outside surface of Zircaloy nuclear fuel cladding tubes by masking with pressure sensitive tape strips and then chemical milling (pickling) the tube wall between the tape strips to leave the fins in relief. Fins up to 0.020 inch high by 0.05 to 0.12 inch wide were consistently produced on tubes having wall thickness of 0.008 inch or greater after fin pickling. Wall thickness uniformity was excellent. Information is provided on tube surface preparation to maximize tape mask adhesion time during pickling, acid chemistry control to prevent local tube wall thinning near the fin, and pickling techniques to promote uniform material removal. Simple fixture designs are described for quickly and conveniently applying the tape strips to the tube wall in an accurate spiral. 13 figures, 4 tables.

  12. Threshold concentration of easily assimilable organic carton in feedwater for biofouling of spiral-wound membranes.

    Science.gov (United States)

    Hijnen, W A M; Biraud, D; Cornelissen, E R; van der Kooij, D

    2009-07-01

    One of the major impediments in the application of spiral-wound membranes in water treatment or desalination is clogging of the feed channel by biofouling which is induced by nutrients in the feedwater. Organic carbon is, under most conditions, limiting the microbial growth. The objective of this study is to assess the relationship between the concentration of an easily assimilable organic compound such as acetate in the feedwater and the pressure drop increase in the feed channel. For this purpose the membrane fouling simulator (MFS) was used as a model for the feed channel of a spiral-wound membrane. This MFS unit was supplied with drinking water enriched with acetate at concentrations ranging from 1 to 1000 microg C x L(-1). The pressure drop (PD) in the feed channel increased at all tested concentrations but not with the blank. The PD increase could be described by a first order process based on theoretical considerations concerning biofilm formation rate and porosity decline. The relationship between the first order fouling rate constant R(f) and the acetate concentration is described with a saturation function corresponding with the growth kinetics of bacteria. Under the applied conditions the maximum R(f) (0.555 d(-1)) was reached at 25 microg acetate-C x L(-1) and the half saturation constant k(f) was estimated at 15 microg acetate-C x L(-1). This value is higher than k(s) values for suspended bacteria grown on acetate, which is attributed to substrate limited growth conditions in the biofilm. The threshold concentration for biofouling of the feed channel is about 1 microg acetate-C x L(-1).

  13. ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566

    CERN Document Server

    Combes, F; Casasola, V; Hunt, L; Krips, M; Baker, A J; Boone, F; Eckart, A; Marquez, I; Neri, R; Schinnerer, E; Tacconi, L J

    2014-01-01

    We report ALMA observations of CO(3-2) emission in the Seyfert 1 galaxy NGC 1566, at a spatial resolution of 25 pc. Our aim is to investigate the morphology and dynamics of the gas inside the central kpc, and to probe nuclear fueling and feedback phenomena. NGC 1566 has a nuclear bar of 1.7 kpc radius and a conspicuous grand design spiral starting from this radius. The ALMA field of view, of diameter 0.9 kpc, lies well inside the nuclear bar and reveals a molecular trailing spiral structure of \\sim 100 pc in size, which is possibly fueling the nucleus. The spiral starts with a large pitch angle from the center and then winds up in a pseudo-ring at the inner Lindblad resonance (ILR) of the nuclear bar. This is the first time that a trailing spiral structure is clearly seen driving the gas inwards inside the ILR ring of the nuclear bar. This phenomenon shows that the massive central black hole has a significant dynamical influence on the gas, triggering its fueling. The gaseous spiral is well correlated with th...

  14. Status of the SPIRAL2 injector commissioning

    Energy Technology Data Exchange (ETDEWEB)

    Thuillier, T., E-mail: thuillier@lpsc.in2p3.fr; Angot, J.; Jacob, J.; Lamy, T.; Sole, P. [LPSC, Université Grenoble Alpes, CNRS/IN2P3, 53 rue des Martyrs, 38026 Grenoble Cedex (France); Barué, C.; Bertrand, P.; Canet, C.; Ferdinand, R.; Flambard, J.-L.; Jardin, P.; Lemagnen, F.; Maunoury, L.; Osmond, B. [GANIL, CNRS/IN2P3, Bvd Henri Becquerel, BP 55027, 14076 Caen Cedex 5 (France); Biarrotte, J. L. [IPN Orsay, Université Paris Sud, CNRS/IN2P3, 15 rue Georges Clémenceau, 91406 Orsay Cedex (France); Denis, J.-F.; Roger, A.; Touzery, R.; Tuske, O.; Uriot, D. [Irfu, CEA Saclay, DSM/Irfu/SACM, 91191 Gif Sur Yvette (France); and others

    2016-02-15

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ∼50. A status of its assembly is proposed.

  15. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    2013-01-01

    We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase...... orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy...... specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization...

  16. Modes Of The Spiral Clock Gong

    Science.gov (United States)

    Perrin, R.; Charnley, T.; Swallowe, G. M.; Banu, H.

    1993-03-01

    The modal frequencies of a spiral clock gong have been measured. The mode numbers and forms of vibrations have been identified by finite element modelling and photographic techniques; very good agreement between modelling and experiment was achieved. All modes were found to be either purely in-plane or out-of-plane. In both cases plots of log (2 n - 1) vs. log ƒ yielded curves with two distinct regions, the transition occurring where the wavelength corresponded to one turn of the spiral. Both sets of lower modes were very complex but the modal frequencies above n = 11 were found to fit a modified form of Chladni's law. It is suggested that the modified Chladni law may form the basis of many musical sounds.

  17. Spiral precipitation patterns in confined chemical gardens.

    Science.gov (United States)

    Haudin, Florence; Cartwright, Julyan H E; Brau, Fabian; De Wit, A

    2014-12-09

    Chemical gardens are mineral aggregates that grow in three dimensions with plant-like forms and share properties with self-assembled structures like nanoscale tubes, brinicles, or chimneys at hydrothermal vents. The analysis of their shapes remains a challenge, as their growth is influenced by osmosis, buoyancy, and reaction-diffusion processes. Here we show that chemical gardens grown by injection of one reactant into the other in confined conditions feature a wealth of new patterns including spirals, flowers, and filaments. The confinement decreases the influence of buoyancy, reduces the spatial degrees of freedom, and allows analysis of the patterns by tools classically used to analyze 2D patterns. Injection moreover allows the study in controlled conditions of the effects of variable concentrations on the selected morphology. We illustrate these innovative aspects by characterizing quantitatively, with a simple geometrical model, a new class of self-similar logarithmic spirals observed in a large zone of the parameter space.

  18. Spiral holographic imaging through quantum interference

    Science.gov (United States)

    Tang, Jie; Ming, Yang; Hu, Wei; Lu, Yan-qing

    2017-07-01

    Spiral holographic imaging in the Hong-Ou-Mandel interference scheme is introduced. Using spontaneous parametric down-conversion as a source of photon pairs, we analyze the joint orbital angular momentum spectrum of a reference photon and the photon encoding information of the object. The first-order interference of light beams in standard holographic imaging is replaced by the quantum interference of two-photon probability amplitudes. The difficulty in retrieving the amplitude and phase structure of an unknown photon is thereby avoided as classical interferometric techniques such as optical holography do not apply. Our results show that the full information of the object's transmission function can be recorded in the spiral hologram, which originates directly from the joint orbital angular momentum spectrum. This presents a lateral demonstration of compressive imaging and can potentially be used for remote sensing.

  19. Status of the SPIRAL2 injector commissioning

    Science.gov (United States)

    Thuillier, T.; Angot, J.; Barué, C.; Bertrand, P.; Biarrotte, J. L.; Canet, C.; Denis, J.-F.; Ferdinand, R.; Flambard, J.-L.; Jacob, J.; Jardin, P.; Lamy, T.; Lemagnen, F.; Maunoury, L.; Osmond, B.; Peaucelle, C.; Roger, A.; Sole, P.; Touzery, R.; Tuske, O.; Uriot, D.

    2016-02-01

    The SPIRAL2 injector, installed in its tunnel, is currently under commissioning at GANIL, Caen, France. The injector is composed of two low energy beam transport lines: one is dedicated to the light ion beam production, the other to the heavy ions. The first light ion beam, created by a 2.45 GHz electron cyclotron resonance ion source, has been successfully produced in December 2014. The first beam of the PHOENIX V2 18 GHz heavy ion source was analyzed on 10 July 2015. A status of the SPIRAL2 injector commissioning is given. An upgrade of the heavy ion source, named PHOENIX V3 aimed to replace the V2, is presented. The new version features a doubled plasma chamber volume and the high charge state beam intensity is expected to increase by a factor of 1.5 to 2 up to the mass ˜50. A status of its assembly is proposed.

  20. Modelling Neutral Hydrogen Discs of Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    林伟鹏; 洪碧海

    2002-01-01

    We present an analytical model of a neutral hydrogen disc in a spiral galaxy. The gas disc of the spiral galaxy isassumed to have an exponential surface density profile and to be ionized by the cosmic ultraviolet background.To compare with observations, we consider the disc position angle and inclination angle for a line of sight goingthrough the galaxy disc. The HI column densities depend on the strength of ionizing field and disc position andinclination. The model was applied to NGC 3198 and the results were compared with observational data. TheHI disc profile at large disc radii can be tested by further HI observations using radio telescopes with a largeraperture than the present facilities. This HI disc model can be used to predict quasar absorption line systems bygalaxy discs if quasar lines of sight go through the discs.

  1. Understanding the transformation of spirals to lenticulars

    CERN Document Server

    Johnston, Evelyn J; Merrifield, Michael R

    2014-01-01

    By studying the individual star-formation histories of the bulges and discs of lenticular (S0) galaxies, it is possible to build up a sequence of events that leads to the cessation of star formation and the consequent transformation from the progenitor spiral. In order to separate the bulge and disc stellar populations, we spectroscopically decomposed long-slit spectra of Virgo Cluster S0s into bulge and disc components. Analysis of the decomposed spectra shows that the most recent star formation activity in these galaxies occurred within the bulge regions, having been fuelled by residual gas from the disc. These results point towards a scenario where the star formation in the discs of spiral galaxies are quenched, followed by a final episode of star formation in the central regions from the gas that has been funnelled inwards through the disc.

  2. Determining the Co-Rotation Radius of Nearby Spiral Galaxies Using Spiral Arm Overlays

    Science.gov (United States)

    Shameer Abdeen, Mohamed; Kennefick, Daniel; Kennefick, Julia D.; Pour Imani, Hamed; Shields, Douglas W.; Eufrasio, Rafael; Berlanga Medina, Jazmin; Monson, Erik

    2017-01-01

    Density wave theory, originally proposed by C.C. Lin and Frank Shu (Lin & Shu 1964), views the spiral arm structures in spiral galaxies as density waves that propagates through the galactic disk. Resonances within orbits create standing wave patterns of density waves that we observe as spiral arms. The theory predicts the existence of a radius known as the co-rotation radius in which the spiral arm pattern speed matches the velocities of the stars within the disk. We introduce a novel way of determining the co-rotation radius, based on an image overlaying technique, which involves tracing the arms of spiral galaxies on images observed from different wavelengths. For the purpose of this study, 12 nearby galaxies were analyzed from four different wavelengths using pitch angle measurements from a previous study (Hamed et al. 2016). We used optical wavelength images (B-Band,440 nm), two infrared wavelength (Infrared; 3.6 µm and 8 µm) Spitzer Space Telescope images and ultraviolet images from GALEX. The results were verified by checking against results compiled from the literature.

  3. Self-Destructing Spiral Waves: Global Simulations of a Spiral Wave Instability in Accretion Disks

    CERN Document Server

    Bae, Jaehan; Hartmann, Lee; Richard, Samuel

    2016-01-01

    We present results from a suite of three-dimensional global hydrodynamic simulations which show that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break-down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport, and vertical mixing, at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter $\\alpha \\sim 5 \\times 10^{-4}$ in our reference model). The instability is found to operate in a wide-range of ...

  4. Mathematical Modeling of Spiral Heat Exchanger

    OpenAIRE

    Probal Guha , Vaishnavi Unde

    2014-01-01

    Compact Heat Exchangers (CHEs) are increasingly being used on small and medium scale industries. Due to their compact size and efficient design, they facilitate more efficient heat transfer. Better heat transfer would imply lesser fuel consumption for the operations of the plant, giving improvement to overall efficiency. This reduction in consumption of fuel is a step towards sustainable development. This report exclusively deals with the study the spiral heat ...

  5. A spiral antenna sandwiched by dielectric layers

    OpenAIRE

    Nakano, Hisamatsu; Ikeda, Masakazu; Hitosugi, Kazuo; Yamauchi, Junji

    2004-01-01

    An infinitesimally thin spiral antenna, sandwiched by bottom and top dielectric layers having the same relative permittivity, is analyzed under the condition that the dielectric layers are of finite extent and the antenna is backed by an infinite conducting plane. As the thickness of the top dielectric layer increases, the input impedance and axial ratio (AR) vary in an oscillatory fashion, with a period slightly larger than one-half of the guided wavelength of a wave propagating in an unboun...

  6. Spiral inflation with Coleman-Weinberg potential

    Science.gov (United States)

    Barenboim, Gabriela; Park, Wan-Il

    2015-03-01

    We apply the idea of spiral inflation to the Coleman-Weinberg potential and show that inflation matching our observations well is allowed for a symmetry-breaking scale ranging from an intermediate scale to a grand unified theory (GUT) scale even if the quartic coupling λ is of O (0.1 ). The tensor-to-scalar ratio can be of O (0.01 ) in the case of GUT-scale symmetry breaking.

  7. Spiral rainband in a numerically simulated tropical cyclone

    Institute of Scientific and Technical Information of China (English)

    ZHU Peijun; ZHENG Yongguang; WANG Hongqing; TAO Zuyu

    2005-01-01

    Spiral rainband is a prominent structure of tropical cyclone. Though its forming mechanism, vortex Rossby wave theory, has been widely recent in recent years, its internal structural features are still not well known. The spiral rainband in the severe tropical storm Kammuri (2002), which caused heavy rainfall in southeast China, is simulated using the mesoscale model MM5 (V3). Results show that the simulated spiral rainband propagates azimuthally at a speed close to that of vortex Rossby wave in theory, and is accom- panied with energy dispersion in the radial direction. The structural features of simulated spiral rainband are analyzed with the high-resolution model output including the full physical process. Positive vorticity, ascending motion, hori- zontal momentum and so on are highly concentrated in the spiral rainband. The convergent moisture of spiral rainband comes mostly from the planetary boundary layer under 1 km. Airflow from the outside of spiral rainband is convective instability, which can provide instability energy for convec- tion development. However, the atmospheric stratification in the inside of spiral rainband is neutral, implying that the instability energy has been released. There is a mesoscale strong wind band just near the spiral rainband in the outer side with a maximum wind speed exceeding 30 m/s, which results from the pressure force acceleration when the air flows into the spiral rainband along the gradient of pressure.

  8. Multiarm spirals in a two-dimensional cardiac substrate.

    Science.gov (United States)

    Bursac, Nenad; Aguel, Felipe; Tung, Leslie

    2004-10-26

    A variety of chemical and biological nonlinear excitable media, including heart tissue, can support stable, self-organized waves of activity in a form of rotating single-arm spirals. In particular, heart tissue can support stationary and meandering spirals of electrical excitation, which have been shown to underlie different forms of cardiac arrhythmias. In contrast to single-arm spirals, stable multiarm spirals (multiple spiral waves that rotate in the same direction around a common organizing center) have not been demonstrated and studied yet in living excitable tissues. Here, we show that persistent multiarm spirals of electrical activity can be induced in monolayer cultures of neonatal rat heart cells by a short, rapid train of electrical point stimuli applied during single-arm-spiral activity. Stable formation is accomplished only in monolayers that show a relatively broad and steep dependence of impulse wavelength and propagation velocity on rate of excitation. The resulting multiarm spirals emit waves of electrical activity at rates faster than for single-arm spirals and exhibit two distinct behaviors, namely "arm-switching" and "tip-switching." The phenomenon of rate acceleration due to an increase in the number of spiral arms possibly may underlie the acceleration of functional reentrant tachycardias paced by a clinician or an antitachycardia device.

  9. Characteristics of Left-Right Spiral Hollow Cylindrical Roller

    Institute of Scientific and Technical Information of China (English)

    Liming Lu; Qiping Chen; Yujiang Qin

    2015-01-01

    Based on new rolling⁃sliding compound bearings, the wear between the one⁃way spiral hollow cylindrical roller and the ribs of the inner and outer ring of rolling⁃sliding compound bearings is reduced by innovational structural design. A new left⁃right spiral hollow cylindrical roller is proposed to replace the one⁃way spiral hollow cylindrical roller. The finite element analysis models of ordinary cylindrical rollers, one⁃way spiral hollow cylindrical rollers and left⁃right spiral hollow cylindrical rollers are respectively established by ABAQUS. The axial displacement of their center mass and the stress distribution of left⁃right spiral hollow cylindrical rollers are compared and analyzed. Theoretical study results show that this new left⁃right spiral hollow cylindrical roller not only inherits the advantages of one⁃way spiral hollow cylindrical rollers, but also avoids the axial offset and the serious wear of the one⁃way spiral hollow cylindrical roller. And the theory research conclusion is verified by the experiment. The left⁃right spiral hollow cylindrical roller has the advantages to overcome boundary stress concentration like logarithmic convex roller. The rolling⁃sliding compound bearings equipped with the new rollers can be better to adapt to the impact of vibration load.

  10. Design of Compact Planar Diplexer Based on Novel Spiral-Based Resonators

    Directory of Open Access Journals (Sweden)

    Ke Lu

    2012-04-01

    Full Text Available A miniaturized planar diplexer utilizing the novel spiral-based resonators is proposed. The given cell which is initially proposed in this article is composed of two separated rectangular spirals which are asymmetrical to each other and thus, it is called as ‘asymmetrical separated spirals resonator’ (ASSR. ASSR has more superior transmission property than the previous prototype and extremely compact dimension is also achieved. It is demonstrated that ASSR can exhibit bandpass performance with high frequency selectivity and good transmission property within the relatively low frequency band. Based on the given characteristic, one planar diplexer composed of T-junction and two ASSRs is synthesized and the fabricated prototype with compact dimension is achieved, thanks to ASSRs explored. Simultaneously, the transversal dimension of each channel is extremely compact because ASSRs are completely embedded in the feed lines. Both the simulated and measured results indicate that satisfactory impedance matching and high isolation between two channels are achieved. Furthermore, the proposed diplexer is uniplanar and no defected ground structure is introduced.

  11. The Milky Way and other spiral galaxies

    Directory of Open Access Journals (Sweden)

    Wang J.L.

    2012-02-01

    Full Text Available Cosmologists have often considered the Milky Way as a typical spiral galaxy, and its properties have considerably influenced the current scheme of galaxy formation. Here we compare the general properties of the Milky Way disk and halo with those of galaxies selected from the SDSS. Assuming the recent measurements of its circular velocity results in the Milky Way being offset by ~2σ from the fundamental scaling relations. On the basis of their location in the (MK, Rd, Vflat volume, the fraction of SDSS spirals like the MilkyWay is only 1.2% in sharp contrast with M31, which appears to be quite typical. Comparison of the Milky Way with M31 and with other spirals is also discussed to investigate whether or not there is a fundamental discrepancy between their mass assembly histories. Possibly the Milky Way is one of the very few local galaxies that could be a direct descendant of very distant, z = 2-3 galaxies, thanks to its quiescent history since thick disk formation.

  12. Are spiral galaxies optically thin or thick?

    CERN Document Server

    Xilouris, E M; Kylafis, N D; Paleologou, E V; Papamastorakis, J

    1999-01-01

    The opacity of spiral galaxies is examined by modelling the dust and stellar content of individual galaxies. The model is applied to five late-type spiral galaxies (NGC 4013, IC 2531, UGC 1082, NGC 5529 and NGC 5907). Having analyzed a total of seven galaxies thus far, the five galaxies mentioned above plus UGC 2048 and NGC 891 presented in (Xilouris et al. 1997, 1998), we are able to draw some general conclusions, the most significant of which are: 1) The face-on central optical depth is less than one in all optical bands indicating that typical spiral galaxies like the ones that we have modelled would be completely transparent if they were to be seen face-on. 2) The dust scaleheight is about half that of the stars, which means that the dust is more concentrated near the plane of the disk. 3) The dust scalelength is about 1.4 times larger than that of the stars and the dust is more radially extended than the stars. 4) The dust mass is found to be about an order of a magnitude more than previously measured us...

  13. Spiraling Fermi arcs in Weyl materials

    Science.gov (United States)

    Li, Songci; Andreev, Anton

    In Weyl materials the valence and conduction electron bands touch at an even number of isolated points in the Brillouin zone. In the vicinity of these points the electron dispersion is linear and may be described by the massless Dirac equation. This results in nontrivial topology of Berry connection curvature. One of its consequences is the existence of peculiar surface electron states whose Fermi surfaces form arcs connecting projections of the Weyl points onto the surface plane. Band bending near the boundary of the crystal also produces surface states. We show that in Weyl materials band bending near the crystal surface gives rise to spiral structure of energy surfaces of arc states. The corresponding Fermi surface has the shape of a spiral that winds about the projection of the Weyl point onto the surface plane. The direction of the winding is determined by the helicity of the Weyl point and the sign of the band bending potential. For close valleys arc state morphology may be understood in terms of avoided crossing of oppositely winding spirals. This work is supported by the U.S. Department of Energy Office of Science, Basic Energy Sciences under Award Number DE-FG02-07ER46452.

  14. Spiral waves in accretion discs - observations

    CERN Document Server

    Steeghs, D

    2000-01-01

    I review the observational evidence for spiral structure in the accretion discs of cataclysmic variables (CVs). Doppler tomography is ideally suited to resolve and map such co-rotating patterns and allows a straightforward comparison with theory. The dwarf nova IP Pegasi presents the best studied case, carrying two spiral arms in a wide range of emission lines throughout its outbursts. Both arms appear at the locations where tidally driven spiral waves are expected, with the arm closest to the gas stream weaker in the lines compared to the arm closest to the companion. Eclipse data indicates sub-Keplerian velocities in the outer disc. The dramatic disc structure changes in dwarf novae on timescales of days to weeks, provide unique opportunities for our understanding of angular momentum transport and the role of density waves on the structure of accretion discs. I present an extension to the Doppler tomography technique that relaxes one of the basic assumptions of tomography, and is able to map modulated emiss...

  15. Spiral Galaxies - classical description of spiral arms and rotational velocity pattern - toy model

    CERN Document Server

    Lobodzinski, Bogdan

    2014-01-01

    We propose an explanation of features of spiral galaxies: spiral arms and observed flat rotation curves, without the presence of an exotic form of matter. The formalism is based on Boltzmanns transport equation for the collisional matter and the very-low-velocity post-Newtonian approximation of the general relativity equations expressed in the Maxwell-like form. The Maxwell-like formulation provides the base for the explanation of the above phenomena in the language of dynamically created gravitoelectromagnetic fields by the movement of mass streams in the plane of the galaxy disc. In the model we use radical simplifications expressed as neglect of the gravitational interaction between neighbors and approximation of the incompressible mass flow. In this frame we show that if the galaxy is fuelled constantly by mass from an external gas reservoir, then the amplification of the gravitomagnetic field can be large enough to create the rotational velocity pattern and spiral arms without the necessity of introducin...

  16. Multiplanar spiral CT enterography in patients with Crohn's disease using a negative oral contrast material: initial results of a noninvasive imaging approach

    Energy Technology Data Exchange (ETDEWEB)

    Reittner, Pia; Goritschnig, Toria; Doerfler, Otto [Department of Radiology, Karl Franzens Medical School and University Hospital Graz, Auenbruggerplatz 9, 8036 Graz (Austria); Petritsch, Wolfgang; Hinterleitner, Thomas [Department of Internal Medicine, Karl Franzens Medical School and University Hospital Graz, Auenbruggerplatz 9, 8036 Graz (Austria); Preidler, Klaus W.; Szolar, Dieter H. [Diagnostikum Graz Sued West, Weblinger Guertel 25, 8054 Graz (Austria)

    2002-09-01

    The aim of this study was to prospectively define the role of multiplanar spiral CT enterography with a new negative oral contrast material for noninvasive assessment of the small bowel in patients with Crohn's disease. Thirty patients with established Crohn's disease prospectively underwent spiral CT enterography at 45-60 min after distension of the small bowel with 1400 ml of a negative oral contrast material (Mucofalk water enema). Spiral CT scans were obtained 50 s after administration of intravenous contrast material with the following parameters: 5-mm collimation; 7.5-mm/s table feed; and 3-mm reconstruction interval. The adequacy of bowel opacification, luminal distension, and the contribution of two-dimensional multiplanar reformatted imaging were assessed by two observers. Spiral CT imaging findings were compared with results of enteroclysis as well as endoscopic and histological findings in all patients. Spiral CT enterography with Mucofalk water enema was well tolerated in 29 of 30 patients. Findings on spiral CT enterography were comparable with those of barium studies in 25 of 30 patients, superior to those on barium studies in 4 patients, and inferior in 1 patient (p<0.05). The addition of multiplanar reformatted images to axial spiral CT scans significantly improved observers' confidence in image interpretation (p<0.05) but did not reveal additional abnormalities. Multiplanar spiral CT enterography with Mucofalk excellently provides information in patients with Crohn's disease. This technique accurately depicts the level of small bowel obstruction and the extent of inflammatory small bowel disease and its extraluminal complications. (orig.)

  17. Spiral Density Waves in a Young Protoplanetary Disk

    CERN Document Server

    Pérez, Laura M; Andrews, Sean M; Ricci, Luca; Isella, Andrea; Linz, Hendrik; Sargent, Anneila I; Wilner, David J; Henning, Thomas; Deller, Adam T; Chandler, Claire J; Dullemond, Cornelis P; Lazio, Joseph; Menten, Karl M; Corder, Stuartt A; Storm, Shaye; Testi, Leonardo; Tazzari, Marco; Kwon, Woojin; Calvet, Nuria; Greaves, Jane S; Harris, Robert J; Mundy, Lee G

    2016-01-01

    Gravitational forces are expected to excite spiral density waves in protoplanetary disks, disks of gas and dust orbiting young stars. However, previous observations that showed spiral structure were not able to probe disk midplanes, where most of the mass is concentrated and where planet formation takes place. Using the Atacama Large Millimeter/submillimeter Array we detected a pair of trailing symmetric spiral arms in the protoplanetary disk surrounding the young star Elias 2-27. The arms extend to the disk outer regions and can be traced down to the midplane. These millimeter-wave observations also reveal an emission gap closer to the star than the spiral arms. We argue that the observed spirals trace shocks of spiral density waves in the midplane of this young disk.

  18. Self-Perpetuating Spiral Arms in Disk Galaxies

    CERN Document Server

    D'Onghia, Elena; Hernquist, Lars

    2012-01-01

    The precise nature of spiral structure in galaxies remains uncertain. Recent studies suggest that spiral arms result from interactions between disks and satellite galaxies. Instead, leaving aside the grand bisymmetric spirals, here we consider the possibility that the multi-armed spiral features originate from density inhomogeneities orbiting within disks. Using high-resolution N-body simulations, we follow the motions of stars under the influence of gravity, and show that mass concentrations with properties similar to those of giant molecular clouds can induce the development of spiral arms through a process termed swing amplification. However, unlike in earlier work, we demonstrate that the eventual response of the disk can be highly non-linear, significantly modifying the formation and longevity of the resulting patterns. Contrary to expectations, ragged spiral structures can survive at least in a statistical sense long after the original perturbing influence has been removed. Our findings thus motivate a ...

  19. Nonlinear dynamics of breathers in the spiral structures of magnets

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, V. V., E-mail: kiselev@imp.uran.ru; Raskovalov, A. A. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation)

    2016-06-15

    The structure and properties of pulsating solitons (breathers) in the spiral structures of magnets are analyzed within the sine-Gordon model. The breather core pulsations are shown to be accompanied by local shifts and oscillations of the spiral structure with the formation of “precursors” and “tails” in the moving soliton. The possibilities for the observation and excitation of breathers in the spiral structures of magnets and multiferroics are discussed.

  20. The lacet: A new type of the spiral wave behavior

    Energy Technology Data Exchange (ETDEWEB)

    Moskalenko, Andrey V. [Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation)], E-mail: cardio@avmoskalenko.ru; Elkin, Yury E. [Institute of Mathematical Problems of Biology, Russian Academy of Sciences, 142290 Pushchino, Moscow Region (Russian Federation) and Moscow State University, Pushchino Branch, 142290 Pushchino, Moscow Region (Russian Federation)

    2009-04-15

    We found a new type of spiral wave behavior in a homogeneous two-dimensional autowave medium. In this regime, the spiral wave tip motion transforms from a two-periodic meander into one-periodic circular rotation due to spontaneous deceleration of spiral wave drift. This discovery might be useful for insight into the nature of various phenomena and, in particular, some potentially life-threatening cardiac arrhythmias.

  1. Topological Constraints on Scroll and Spiral Waves in Excitable Media

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong; HU Bambi; LI Bing-Wei; DUAN Yi-Shi

    2007-01-01

    A conservation equation for topological charges of phase singularities (scroll and spiral waves) in excitable media is given. It provides some topological properties of scroll (spiral) waves: for example, the topological charge of the generated or annihilated spiral pair must be opposite. Additionally, we obtain another equation on scroll waves, which shows that singular filaments of scroll waves occur on a set of one-dimensional curves which may be either closed loops or infinite lines.

  2. Cochlea and other spiral forms in nature and art.

    Science.gov (United States)

    Marinković, Slobodan; Stanković, Predrag; Štrbac, Mile; Tomić, Irina; Ćetković, Mila

    2012-01-01

    The original appearance of the cochlea and the specific shape of a spiral are interesting for both the scientists and artists. Yet, a correlation between the cochlea and the spiral forms in nature and art has been very rarely mentioned. The aim of this study was to investigate the possible correlation between the cochlea and the other spiral objects in nature, as well as the artistic presentation of the spiral forms. We explored data related to many natural objects and examined 13,625 artworks created by 2049 artists. We also dissected 2 human cochleas and prepared histologic slices of a rat cochlea. The cochlea is a spiral, cone-shaped osseous structure that resembles certain other spiral forms in nature. It was noticed that parts of some plants are arranged in a spiral manner, often according to Fibonacci numbers. Certain animals, their parts, or their products also represent various types of spirals. Many of them, including the cochlea, belong to the logarithmic type. Nature created spiral forms in the living world to pack a larger number of structures in a limited space and also to improve their function. Because the cochlea and other spiral forms have a certain aesthetic value, many artists presented them in their works of art. There is a mathematical and geometric correlation between the cochlea and natural spiral objects, and the same functional reason for their formation. The artists' imagery added a new aspect to those domains. Obviously, the creativity of nature and Homo sapiens has no limits--like the infinite distal part of the spiral. Copyright © 2012 Elsevier Inc. All rights reserved.

  3. A Study of Spiral Tap with Large Diameter

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The design and manufacture of spiral tap yet are in r esearch stage at present. This paper mainly introduces how to calculate its geom etric parameters and scientific selection of them with vector method. In additio n, an empiric formula of the tool life of spiral tap with large diameter is esta blished by method of correlation. The practice of design, manufacture and applying proves the advantage of spiral tap by the comparison between the spiral tap and common tap with same size. In the application of...

  4. Topological Signatures in the Electronic Structure of Graphene Spirals

    DEFF Research Database (Denmark)

    Avdoshenko, Stas.M.; Koskinen, Pekka; Sevincli, Haldun

    2013-01-01

    constrained by space curvature, graphene spirals have topologically protected states due to time-reversal symmetry. In addition, we argue that the synthesis of such graphene spirals is feasible and can be achieved through advanced bottom-up experimental routes that we indicate in this work....... and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian...

  5. Algorithms for computing efficient, electric-propulsion, spiralling trajectories Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Develop techniques for rapidly designing many-revolution, electric-propulsion, spiralling trajectories, including the effects of shadowing, gravity harmonics, and...

  6. Influence of nanomechanical crystal properties on the comminution process of particulate solids in spiral jet mills.

    Science.gov (United States)

    Zügner, Sascha; Marquardt, Karin; Zimmermann, Ingfried

    2006-02-01

    Elastic-plastic properties of single crystals are supposed to influence the size reduction process of bulk materials during jet milling. According to Pahl [M.H. Pahl, Zerkleinerungstechnik 2. Auflage. Fachbuchverlag, Leipzig (1993)] and H. Rumpf: [Prinzipien der Prallzerkleinerung und ihre Anwendung bei der Strahlmahlung. Chem. Ing. Tech., 3(1960) 129-135.] fracture toughness, maximum strain or work of fracture for example are strongly dependent on mechanical parameters like hardness (H) and young's modulus of elasticity (E). In addition the dwell time of particles in a spiral jet mill proved to correlate with the hardness of the feed material [F. Rief: Ph. D. Thesis, University of Würzburg (2001)]. Therefore 'near-surface' properties have a direct influence on the effectiveness of the comminution process. The mean particle diameter as well as the size distribution of the ground product may vary significantly with the nanomechanical response of the material. Thus accurate measurement of crystals' hardness and modulus is essential to determine the ideal operational micronisation conditions of the spiral jet mill. The recently developed nanoindentation technique is applied to examine subsurface properties of pharmaceutical bulk materials, namely calcite, sodium ascorbate, lactose and sodium chloride. Pressing a small sized tip into the material while continuously recording load and displacement, characteristic diagrams are derived. The mathematical evaluation of the force-displacement-data allows for calculation of the hardness and the elastic modulus of the investigated material at penetration depths between 50-300 nm. Grinding experiments performed with a modified spiral jet mill (Type Fryma JMRS 80) indicate the strong impact of the elastic-plastic properties of a given substance on its breaking behaviour. The fineness of milled products produced at constant grinding conditions but with different crystalline powders varies significantly as it is dependent on the

  7. An Atlas of Hubble Space Telescope Spectra and Images of Nearby Spiral Galaxies

    Science.gov (United States)

    Hughes, M. A.; Alonso-Herrero, A.; Axon, D.; Scarlata, C.; Atkinson, J.; Batcheldor, D.; Binney, J.; Capetti, A.; Carollo, C. M.; Dressel, L.; Gerssen, J.; Macchetto, D.; Maciejewski, W.; Marconi, A.; Merrifield, M.; Ruiz, M.; Sparks, W.; Stiavelli, M.; Tsvetanov, Z.; van der Marel, R.

    2003-08-01

    We have observed 54 nearby spiral galaxies with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope to obtain optical long-slit spectra of nuclear gas disks and STIS optical (~R band) images of the central 5''×5'' of the galaxies. These spectra are being used to determine the velocity field of nuclear disks and hence to detect the presence of central massive black holes. Here we present the spectra for the successful observations. Dust obscuration can be significant at optical wavelengths, and so we also combine the STIS images with archival Near-Infrared Camera and Multi-Object Spectrometer H-band images to produce color maps to investigate the morphology of gas and dust in the central regions. We find a great variety in the different morphologies, from smooth distributions to well-defined nuclear spirals and dust lanes. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  8. Impact of biofilm accumulation on transmembrane and feed channel pressure drop: Effects of crossflow velocity, feed spacer and biodegradable nutrient

    KAUST Repository

    Dreszer, C.

    2014-03-01

    Biofilm formation causes performance loss in spiral-wound membrane systems. In this study a microfiltration membrane was used in experiments to simulate fouling in spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules without the influence of concentration polarization. The resistance of a microfiltration membrane is much lower than the intrinsic biofilm resistance, enabling the detection of biofilm accumulation in an early stage. The impact of biofilm accumulation on the transmembrane (biofilm) resistance and feed channel pressure drop as a function of the crossflow velocity (0.05 and 0.20ms-1) and feed spacer presence was studied in transparent membrane biofouling monitors operated at a permeate flux of 20Lm-2h-1. As biodegradable nutrient, acetate was dosed to the feed water (1.0 and 0.25mgL-1 carbon) to enhance biofilm accumulation in the monitors. The studies showed that biofilm formation caused an increased transmembrane resistance and feed channel pressure drop. The effect was strongest at the highest crossflow velocity (0.2ms-1) and in the presence of a feed spacer. Simulating conditions as currently applied in nanofiltration and reverse osmosis installations (crossflow velocity 0.2ms-1 and standard feed spacer) showed that the impact of biofilm formation on performance, in terms of transmembrane and feed channel pressure drop, was strong. This emphasized the importance of hydrodynamics and feed spacer design. Biomass accumulation was related to the nutrient load (nutrient concentration and linear flow velocity). Reducing the nutrient concentration of the feed water enabled the application of higher crossflow velocities. Pretreatment to remove biodegradable nutrient and removal of biomass from the membrane elements played an important part to prevent or restrict biofouling. © 2013 Elsevier Ltd.

  9. One-armed spiral instability in neutron star mergers and its detectability in gravitational waves

    Science.gov (United States)

    Radice, David; Bernuzzi, Sebastiano; Ott, Christian D.

    2016-09-01

    We study the development and saturation of the m =1 one-armed spiral instability in remnants of binary neutron star mergers by means of high-resolution long-term numerical relativity simulations. Our results suggest that this instability is a generic outcome of neutron star mergers in astrophysically relevant configurations, including both "stiff" and "soft" nuclear equations of state. We find that, once seeded at merger, the m =1 mode saturates within ˜10 ms and persists over secular time scales. Gravitational waves emitted by the m =1 instability have a peak frequency around 1-2 kHz and, if detected, they could be used to constrain the equation of state of neutron stars. We construct hybrid waveforms spanning the entire Advanced LIGO band by combining our high-resolution numerical data with state-of-the-art effective-one-body waveforms including tidal effects. We use the complete hybrid waveforms to study the detectability of the one-armed spiral instability for both Advanced LIGO and the Einstein Telescope. We conclude that the one-armed spiral instability is not an efficient gravitational wave emitter. Even under very optimistic assumptions, Advanced LIGO will only be able to detect the one-armed instability up to ˜3 Mpc , which corresponds to an event rate of 10-7 yr-1 to 10-4 yr-1 . Third-generation detectors or better will likely be required to observe the one-armed instability.

  10. A Unified Scaling Law in Spiral Galaxies.

    Science.gov (United States)

    Koda; Sofue; Wada

    2000-03-01

    We investigate the origin of a unified scaling relation in spiral galaxies. Observed spiral galaxies are spread on a plane in the three-dimensional logarithmic space of luminosity L, radius R, and rotation velocity V. The plane is expressed as L~&parl0;VR&parr0;alpha in the I passband, where alpha is a constant. On the plane, observed galaxies are distributed in an elongated region which looks like the shape of a surfboard. The well-known scaling relations L-V (Tully-Fisher [TF] relation), V-R (also the TF relation), and R-L (Freeman's law) can be understood as oblique projections of the surfboard-like plane into two-dimensional spaces. This unified interpretation of the known scaling relations should be a clue to understand the physical origin of all the relations consistently. Furthermore, this interpretation can also explain why previous studies could not find any correlation between TF residuals and radius. In order to clarify the origin of this plane, we simulate formation and evolution of spiral galaxies with the N-body/smoothed particle hydrodynamics method, including cooling, star formation, and stellar feedback. Initial conditions are set to 14 isolated spheres with two free parameters, such as mass and angular momentum. The cold dark matter (h=0.5, Omega0=1) cosmology is considered as a test case. The simulations provide the following two conclusions: (1) The slope of the plane is well reproduced but the zero point is not. This zero-point discrepancy could be solved in a low-density (Omega00.5) cosmology. (2) The surfboard-shaped plane can be explained by the control of galactic mass and angular momentum.

  11. The ordered distribution of natural numbers on the square root spiral

    CERN Document Server

    Hahn, Harry K

    2007-01-01

    Natural numbers divisible by the same prime factor lie on defined spiral graphs which are running through the Square Root Spiral (also named as the Spiral of Theodorus or Wurzel Spirale or Einstein Spiral). Prime Numbers also clearly accumulate on such spiral graphs. And the square numbers 4, 9, 16, 25, 36,... form a highly three-symmetrical system of three spiral graphs, which divides the square-root-spiral into three equal areas. A mathematical analysis shows that these spiral graphs are defined by quadratic polynomials. Fibonacci number sequences also play a part in the structure of the Square Root Spiral. Fibonacci Numbers divide the Square Root Spiral into areas and angle sectors with constant proportions. These proportions are linked to the golden mean (or golden section), which behaves as a self-avoiding-walk-constant in the lattice-like structure of the square root spiral.

  12. Spiral phase contrast imaging in microscopy.

    Science.gov (United States)

    Fürhapter, Severin; Jesacher, Alexander; Bernet, Stefan; Ritsch-Marte, Monika

    2005-02-07

    We demonstrate an optical method for edge contrast enhancement in light microscopy. The method is based on holographic Fourier plane filtering of the microscopic image with a spiral phase element (also called vortex phase or helical phase filter) displayed as an off-axis hologram at a computer controlled high resolution spatial light modulator (SLM) in the optical imaging pathway. The phase hologram imprints a helical phase term of the form exp(i phi) on the diffracted light field in its Fourier plane. In the image plane, this results in a strong and isotropic edge contrast enhancement for both amplitude and phase objects.

  13. SPIRAL2/DESIR high resolution mass separator

    Energy Technology Data Exchange (ETDEWEB)

    Kurtukian-Nieto, T., E-mail: kurtukia@cenbg.in2p3.fr [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Baartman, R. [TRIUMF, 4004 Wesbrook Mall, Vancouver B.C., V6T 2A3 (Canada); Blank, B.; Chiron, T. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Davids, C. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Delalee, F. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Duval, M. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); El Abbeir, S.; Fournier, A. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Lunney, D. [CSNSM-IN2P3-CNRS, Université de Paris Sud, F-91405 Orsay (France); Méot, F. [BNL, Upton, Long Island, New York (United States); Serani, L. [Centre d’Études Nucléaires de Bordeaux Gradignan, Université Bordeaux 1-CNRS/IN2P3, BP 120, F-33175 Gradignan Cedex (France); Stodel, M.-H.; Varenne, F. [GANIL, CEA/DSM-CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5 (France); and others

    2013-12-15

    DESIR is the low-energy part of the SPIRAL2 ISOL facility under construction at GANIL. DESIR includes a high-resolution mass separator (HRS) with a designed resolving power m/Δm of 31,000 for a 1 π-mm-mrad beam emittance, obtained using a high-intensity beam cooling device. The proposed design consists of two 90-degree magnetic dipoles, complemented by electrostatic quadrupoles, sextupoles, and a multipole, arranged in a symmetric configuration to minimize aberrations. A detailed description of the design and results of extensive simulations are given.

  14. Spin gap in a spiral staircase model

    Energy Technology Data Exchange (ETDEWEB)

    Kiselev, M.N. [Institut fuer Theoretische Physik und Astrophysik, Wuerzburg Universitaet, Am Hubland, D-97074 Wuerzburg (Germany)]. E-mail: kiselev@physik.uni-wuerzburg.de; Aristov, D.N. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Kikoin, K. [Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel)

    2005-04-30

    We investigate the formation of spin gap in one-dimensional models characterized by the groups with hidden symmetries. We introduce a new class of Hamiltonians for description of spin staircases-the spin systems intermediate between 2-leg ladders and S=1 spin chains. The spin exchange anisotropy along legs is described by the angle of spiral twist. The properties of a special case of spin rotator chain (SRC) corresponding to a flat 1-leg ladder is considered by means of fermionization approach based on Jordan-Wigner transformation. The influence of dynamical hidden symmetries on the scaling properties of the spin gap is discussed.

  15. Parity effects in 120° spin spirals.

    Science.gov (United States)

    Menzel, Matthias; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2014-01-31

    The magnetic ground state of biatomic Fe chains on the reconstructed (5×1)-Ir(001) surface is a cycloidal 120° spin spiral. Spin-resolved scanning tunneling microscopy reveals a striking variation of magnetic field dependences among the chains, which we attribute to parity effects resulting from finite lengths. Numerical simulations show that the chains are divided in three symmetry classes with the exact number of atoms in the chain determining the size and direction of their net magnetic moment. In contrast to antiferromagnetic systems, the three-atom periodicity causes the effective anisotropy to alternate between out of plane, in plane, and quenched.

  16. Spiral orbits and oscillations in historical dynamics

    CERN Document Server

    Cheon, Taksu

    2015-01-01

    We introduce the concept of metaasabiya, the second non-material resource, to the asabiya theory of historical dynamics. We find that the resulting three variable dynamical system has peculiar features such as repelling or attracting axes and spiralling orbits in the phase space. Depending on the initial state, the system can go through series of oscillatory rises and falls, mimicking the geopolitical evolution of real-world polities. These distinctive features, absent in conventional Lotka-Volterra type biological systems, reveal the hidden richness inherent in the asabiya theory.

  17. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    Kapilanjan Krishna

    2008-04-01

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions evolve towards unique distribution with increasing Rayleigh number that suggests power-law scaling for the dynamics in the limit of infinite system size. The techniques are generally applicable to patterns that are reducible to a binary representation.

  18. Strategies to preserve or regenerate spiral ganglion neurons.

    Science.gov (United States)

    Roehm, Pamela C; Hansen, Marlan R

    2005-10-01

    Degeneration of spiral ganglion neurons following hair cell loss carries critical implications for efforts to rehabilitate severe cases of hearing loss with cochlear implants or hair cell regeneration. This review considers recently identified neurotrophic factors and therapeutic strategies which promote spiral ganglion neuron survival and neurite growth. Replacement of these factors may help preserve or regenerate the auditory nerve in patients with extensive hair cell loss. Spiral ganglion neurons depend on neurotrophic factors supplied by hair cells and other targets for their development and continued survival. Loss of this trophic support leads to spiral ganglion neuron death via apoptosis. Hair cells support spiral ganglion neuron survival by producing several peptide neurotrophic factors such as neurotrophin-3 and glial derived neurotrophic factor. In addition, neurotransmitter release from the hair cells drives membrane electrical activity in spiral ganglion neurons which also supports their survival. In animal models, replacement of peptide neurotrophic factors or electrical stimulation with an implanted electrode attenuates spiral ganglion neuron degeneration following deafferentation. Cell death inhibitors can also preserve spiral ganglion neuron populations. Preliminary studies show that transfer of stem cells or neurons from other ganglia are two potential strategies to replace lost spiral ganglion neurons. Inducing the regrowth of spiral ganglion neuron peripheral processes to approximate or contact cochlear implant electrodes may help optimize signaling from a diminished population of neurons. Recent studies of spiral ganglion neuron development and survival have identified several trophic and neuritogenic factors which protect these specialized cells from degeneration following hair cell loss. While still preliminary, such strategies show promise for future clinical applications.

  19. Spiral wobbling beam illumination uniformity in HIF fuel target implosion

    Directory of Open Access Journals (Sweden)

    Kawata S.

    2013-11-01

    Full Text Available A few % wobbling-beam illumination nonuniformity is realized in heavy ion inertial confinement fusion (HIF throughout the heavy ion beam (HIB driver pulse by a newly introduced spiraling beam axis motion in the first two rotations. The wobbling HIB illumination was proposed to realize a uniform implosion in HIF. However, the initial imprint of the wobbling HIBs was a serious problem and introduces a large unacceptable energy deposition nonuniformity. In the wobbling HIBs illumination, the illumination nonuniformity oscillates in time and space. The oscillating-HIB energy deposition may produce a time-dependent implosion acceleration, which reduces the Rayleigh-Taylor (R-T growth [Laser Part. Beams 11, 757 (1993, Nuclear Inst. Methods in Phys. Res. A 606, 152 (2009, Phys. Plasmas 19, 024503 (2012] and the implosion nonuniformity. The wobbling HIBs can be generated in HIB accelerators and the oscillating frequency may be several 100 MHz ∼ 1 GHz [Phys. Rev. Lett. 104, 254801 (2010]. Three-dimensional HIBs illumination computations present that the few % wobbling HIBs illumination nonuniformity oscillates with the same wobbling HIBs frequency.

  20. Self-destructing Spiral Waves: Global Simulations of a Spiral-wave Instability in Accretion Disks

    Science.gov (United States)

    Bae, Jaehan; Nelson, Richard P.; Hartmann, Lee; Richard, Samuel

    2016-09-01

    We present results from a suite of three-dimensional global hydrodynamic simulations that shows that spiral density waves propagating in circumstellar disks are unstable to the growth of a parametric instability that leads to break down of the flow into turbulence. This spiral wave instability (SWI) arises from a resonant interaction between pairs of inertial waves, or inertial-gravity waves, and the background spiral wave. The development of the instability in the linear regime involves the growth of a broad spectrum of inertial modes, with growth rates on the order of the orbital time, and results in a nonlinear saturated state in which turbulent velocity perturbations are of a similar magnitude to those induced by the spiral wave. The turbulence induces angular momentum transport and vertical mixing at a rate that depends locally on the amplitude of the spiral wave (we obtain a stress parameter α ˜ 5 × 10-4 in our reference model). The instability is found to operate in a wide range of disk models, including those with isothermal or adiabatic equations of state, and in viscous disks where the dimensionless kinematic viscosity ν ≤ 10-5. This robustness suggests that the instability will have applications to a broad range of astrophysical disk-related phenomena, including those in close binary systems, planets embedded in protoplanetary disks (including Jupiter in our own solar system) and FU Orionis outburst models. Further work is required to determine the nature of the instability and to evaluate its observational consequences in physically more complete disk models than we have considered in this paper.

  1. Feeding tube insertion - gastrostomy

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002937.htm Feeding tube insertion - gastrostomy To use the sharing features on this page, please enable JavaScript. A gastrostomy feeding tube insertion is the placement of a feeding ...

  2. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... 1- to 2-Year-Old Breastfeeding vs. Formula Feeding KidsHealth > For Parents > Breastfeeding vs. Formula Feeding Print ... a lactation specialist. previous continue All About Formula Feeding Commercially prepared infant formulas are a nutritious alternative ...

  3. Animal Feeding Operations

    Science.gov (United States)

    ... What's this? Submit Button Healthy Water Home Animal Feeding Operations Recommend on Facebook Tweet Share Compartir On ... Concentrated Animal Feeding Operations (CAFOs) What are Animal Feeding Operations (AFOs)? According to the United States Environmental ...

  4. Breastfeeding vs. Formula Feeding

    Science.gov (United States)

    ... A What's in this article? All About Breastfeeding Breastfeeding Challenges All About Formula Feeding Formula Feeding Challenges Making a Choice en español Lactancia materna versus lactancia artificial Choosing whether to breastfeed or formula feed their ...

  5. Use of nuclear and related techniques to develop simple tannin assays for predicting and improving the safety and efficiency of feeding ruminants on tanniniferous tree foliage: Achievements, result implications, and future research

    Energy Technology Data Exchange (ETDEWEB)

    Makkar, H.P.S. [Animal Production and Health Section, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Vienna (Austria)]. E-mail: h.makkar@iaea.org

    2005-08-19

    The utilization of unconventional feed resources holds great relevance to developing countries, where the main constraint to livestock development is the scarcity and fluctuation of the quality and quantity of the year-around animal feed supply. There is a serious shortage in concentrated animal feeds such as soybean, cottonseed and groundnut meals, etc. In addition, the human population is increasingly rapidly and arable land is decreasing, due to solid degradation, urbanization and industrialization. Production of grain in developing countries is mostly for human consumption. Novel approaches through the utilization of tree leaves, agro-industrial by-products, aquatic sources are required to bridge the gap between supply and demand of feeds. As the demand for food rises, including that of animal origin, unconventional feed resources including tanninferous plants must play an increasingly important part in the diet of animals, in particular for ruminants in smallholder farming systems in developing countries.

  6. Controlling Spiral Dynamics in Excitable Media by a Weakly Localized Pacing

    Institute of Scientific and Technical Information of China (English)

    LI Bing-Wei; SUN Li-Li; CHEN Bin; YING He-Ping

    2007-01-01

    @@ Spiral dynamics controlled by a weakly localized pacing around the spiral tip is investigated. Numerical simulations show two distinct characteristics when the pacing is applied with the weak amplitude for suitable frequencies:for a rigidly rotating spiral, a transition from rigid rotation to meandering motion is observed, and for unstable spiral waves, spiral breakup can be prevented. Successfully preventing spiral breakup is relevant to the modulation of the tip trajectory induced by a localized pacing.

  7. Spiraling Into Gallstone Disease: A Physicist's Spin

    Science.gov (United States)

    Zastavker, Y. V.; Tilley, B. S.; Pratt, J. C.

    2005-10-01

    Scientists have been fascinated for decades with the ability of nature to form self-assembled structures of various configurations. One such configuration is a spiral or a helix. The (double) helical geometrical configuration is a well-known secondary structure of DNA; however, DNA is not the only biological system possessing this shape. Spirals have been found in a variety of biological and synthetic systems, one of which is bile in the gallbladder. In this system, helical ribbons appear as metastable intermediates in the process of cholesterol crystallization that leads to the formation of gallstones. The bile system is particularly interesting and unique due to the richness in variety of the helical structures formed. Understanding the mechanisms for nature's self-assembly of helical ribbons is crucial in both the prevention of gallstone disease and in developing potential technological and medical applications. We describe a model bile system, composed of three major components of native bile in water: a phospholipid, a fatty acid, and a sterol. This system behaves similarly to the native bile in terms of the kinetics of the formation and evolution of intermediate metastables, including helical ribbons. We further describe our experimental findings and phenomenological model explaining the geometrical shape, elastic properties, and behavior of helical ribbons in model bile systems. We also propose possible applications of these structures as drug delivery vehicles, metallization templates, and antifouling devices.

  8. Spiral-shaped reactor for water disinfection

    KAUST Repository

    Soukane, Sofiane

    2016-04-20

    Chlorine-based processes are still widely used for water disinfection. The disinfection process for municipal water consumption is usually carried out in large tanks, specifically designed to verify several hydraulic and disinfection criteria. The hydrodynamic behavior of contact tanks of different shapes, each with an approximate total volume of 50,000 m3, was analyzed by solving turbulent momentum transport equations with a computational fluid dynamics code, namely ANSYS fluent. Numerical experiments of a tracer pulse were performed for each design to generate flow through curves and investigate species residence time distribution for different inlet flow rates, ranging from 3 to 12 m3 s−1. A new nature-inspired Conch tank design whose shape follows an Archimedean spiral was then developed. The spiral design is shown to strongly outperform the other tanks’ designs for all the selected plug flow criteria with an enhancement in efficiency, less short circuiting, and an order of magnitude improvement in mixing and dispersion. Moreover, following the intensification philosophy, after 50% reduction in its size, the new design retains its properties and still gives far better results than the classical shapes.

  9. Spiral thickenings in the axial Parenchyma of Chrysobalanaceae

    NARCIS (Netherlands)

    Welle, ter B.J.H.

    1976-01-01

    Spiral thickenings in the axial parenchyma, seldom recorded in the secondary xylem of the dicotyledons so far, are described for a number of genera and/or species of Chrysobalanaceae. In 66 out of 99 samples investigated, representing most genera of the Chrysobalanaceae, spiral thickenings proved to

  10. On galaxy spiral arms' nature as revealed by rotation frequencies

    NARCIS (Netherlands)

    Roca-Fabrega, Santi; Valenzuela, Octavio; Figueras, Francesca; Romero-Gomez, Merce; Velazquez, Hector; Antoja Castelltort, Teresa; Pichardo, Barbara

    2013-01-01

    High-resolution N-body simulations using different codes and initial condition techniques reveal two different behaviours for the rotation frequency of transient spiral arms like structures. Whereas unbarred discs present spiral arms nearly corotating with disc particles, strong barred models (bulge

  11. Star formation in galaxies: the role of spiral arms

    CERN Document Server

    Dobbs, Clare

    2013-01-01

    Studying star formation in spiral arms tells us not only about the evolution of star formation, and molecular clouds, but can also tell us about the nature of spiral structure in galaxies. I will address both these topics using the results of recent simulations and observations. Galactic scale simulations are beginning to examine in detail the evolution of GMCs as they form in spiral arms, and then disperse by stellar feedback or shear. The overall timescale for this process appears comparable to the crossing time of the GMCs, a few Myrs for $10^5$ M$_{\\odot}$ clouds, 20 Myr or so for more massive GMCs. Both simulations and observations show that the massive clouds are found in the spiral arms, likely as a result of cloud-cloud collisions. Simulations including stars should also tell us about the stellar age distribution in GMCs, and across spiral arms. More generally, recent work on spiral galaxies suggests that the dynamics of gas flows in spiral arms are different in longlived and transient spiral arms, re...

  12. Analysis on Spiral Search Pattern for Moving Target

    Institute of Scientific and Technical Information of China (English)

    E Qun; MA Yuan-liang; ZHOU Zhou; WANG Ming-chen; WANG Lian-zhu

    2008-01-01

    The distribution function of the target moving in constant velocity and linear course and its meeting condition to the searcher are analyzed. Another proof method for spiral search pattern is presented and the mathematic model of the target possible position is established when performing the linear search. Base on them, the wrong idea about the spiral search pattern can be avoided.

  13. The cold interstellar medium - An HI view of spiral galaxies

    NARCIS (Netherlands)

    Sancisi, R; Bender, R; Davies, RL

    1996-01-01

    An HI view of spiral galaxies is presented. In the first part the standard picture of isolated, normal spiral galaxies is briefly reviewed. In the second part attention is drawn to all those phenomena, such as tidal interactions, accretion and mergers, that depend on the galaxy environment and seem

  14. Ray transfer matrix for a spiral phase plate.

    Science.gov (United States)

    Eggleston, M; Godat, T; Munro, E; Alonso, M A; Shi, H; Bhattacharya, M

    2013-12-01

    We present a ray transfer matrix for a spiral phase plate. Using this matrix we determine the stability of an optical resonator made of two spiral phase plates and trace stable ray orbits in the resonator. Our results should be relevant to laser physics, optical micromanipulation, quantum information, and optomechanics.

  15. Homoclinic (Heteroclinic) Orbit of Complex Dynamical System and Spiral Structure

    Institute of Scientific and Technical Information of China (English)

    FU Zun-Tao; LIU Shi-Da; LIU Shi-Kuo; LIANG Fu-Ming; XIN Guo-Jun

    2005-01-01

    Starting from iterated systems, it is shown that the homoclinic (heteroclinic) orbit is a kind of spiral structure. The emphasis is laid to show that there are homoclinic or heteroclinic orbits in complex discrete and continuous systems, and these homoclinic or heteroclinic orbits are some kind of spiral structure.

  16. A Systematic Study on Scaling Law of Spiral Waves

    Institute of Scientific and Technical Information of China (English)

    ShufengBAI; QiOUYANG

    1999-01-01

    The study of spiral waves in the Belousov-Zhabotinsky (BZ) reaction has generated fruitful results since the invention of the open spatial reactor.However,some theories are only unsubstantiated and need additional verifications.Our experimental results give a new scaling law of simple and quasi-periodic spiral waves,providing corroborations for some theories and challenge some others.

  17. Spiral Arm of the Perseus Is Closer than Thought

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ It is easy for us to observe the magnificent spiral galaxies outside the Milky Way with a telescope. Although our own galaxy is also believed to have similar spiral arms to those observed in the universe, astronomers have difficulties in rendering the structure because we are living inside it.

  18. Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity

    Science.gov (United States)

    2015-01-01

    1 Ekman Spiral in Horizontally Inhomogeneous Ocean with Varying Eddy Viscosity...Oceanography Naval Postgraduate School, Monterey, California, USA Manuscript Click here to download Manuscript: Ekman -chu-pageoph-rev.docx 1...currently valid OMB control number. 1. REPORT DATE 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Ekman Spiral

  19. Drift of Spiral Waves in Complex Ginzburg-Landau Equation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The spontaneous drift of the spiral wave in a finite domain in the complex Ginzburg-Landau equation is investigated numerically. By using the interactions between the spiral wave and its images, we propose a phenomenological theory to explain the observations.

  20. Nuclear Medicine

    Science.gov (United States)

    ... for Parents/Teachers Resource Links for Students Glossary Nuclear Medicine What is nuclear medicine? What are radioactive ... NIBIB-funded researchers advancing nuclear medicine? What is nuclear medicine? Nuclear medicine is a medical specialty that ...

  1. Effects of non Newtonian spiral blood flow through arterial stenosis

    Science.gov (United States)

    Hasan, Md. Mahmudul; Maruf, Mahbub Alam; Ali, Mohammad

    2016-07-01

    The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system. A numerical investigation is carried out to analyze the effect of spiral blood flow through an axisymmetric three dimensional artery having 75% stenosis at the center. Blood is assumed as a Non-Newtonian fluid. Standard k-ω model is used for the simulation with the Reynolds number of 1000. A parabolic velocity profile with spiral flow is used as inlet boundary condition. The peak values of all velocity components are found just after stenosis. But total pressure gradually decreases at downstream. Spiral flow of blood has significant effects on tangential component of velocity. However, the effect is mild for radial and axial velocity components. The peak value of wall shear stress is at the stenosis zone and decreases rapidly in downstream. The effect of spiral flow is significant for turbulent kinetic energy. Detailed investigation and relevant pathological issues are delineated throughout the paper.

  2. Scale Heights of Non-Edge-on Spiral Galaxies

    Institute of Scientific and Technical Information of China (English)

    Tao Hu; Qiu-He Peng; Ying-He Zhao

    2006-01-01

    We present a method of calculating the scale height of non-edge-on spiral galaxies, together with a formula for errors. The method is based on solving Poisson's equation for a logarithmic disturbance of matter density in spiral galaxies. We show that the spiral arms can not extend to inside the "forbidden radius" γ0, due to the effect of the finite thickness of the disk. The method is tested by re-calculating the scale heights of 71 northern spiral galaxies previously calculated by Ma, Peng & Gu.Our results differ from theirs by less than 9%. We also present the scale heights of a further 23 non-edge-on spiral galaxies.

  3. The Effects of Spiral Taping Treatment on Low Back Pain

    Directory of Open Access Journals (Sweden)

    Hwang Jae-Ok

    2006-02-01

    Full Text Available Objective : The purpose of this study is to estimate the effects of spiral taping treatment on low back pain. Methods : 420 low back pain patients were treated with spiral taping or spiral taping plus herbal medicine, and no other treatments such as acupuncture, herbal acupuncture, and chiropractic therapy were added. We evaluated the improvement by physical examination and pain. Results : 364 patients felt no pain or inconvenience of daily life and 43 patients showed improvement of pain or symptom after 1 month of treatment. 13 patients showed same pain with before treatment. Conclusions : These results suggest spiral taping treatments contribute to the improvement of low back pain. Further study is needed for the confirmation of this effect of spiral taping treatments on low back pain.

  4. A Photometrically and Spectroscopically Confirmed Population of Passive Spiral Galaxies

    CERN Document Server

    Fraser-McKelvie, Amelia; Pimbblet, Kevin A; Dolley, Tim; Crossett, Jacob P; Bonne, Nicolas J

    2016-01-01

    We have identified a population of passive spiral galaxies from photometry and integral field spectroscopy. We selected z<0.035 spiral galaxies that have WISE colours consistent with little mid-infrared emission from warm dust. Matched aperture photometry of 51 spiral galaxies in ultraviolet, optical and mid-infrared show these galaxies have colours consistent with passive galaxies. Six galaxies form a spectroscopic pilot study and were observed using the Wide-Field Spectrograph (WiFeS) to check for signs of nebular emission from star formation. We see no evidence of substantial nebular emission found in previous red spiral samples. These six galaxies possess absorption-line spectra with 4000\\AA\\ breaks consistent with an average luminosity-weighted age of 2.3 Gyr. Our photometric and IFU spectroscopic observations confirm the existence of a population of local passive spiral galaxies, implying that transformation into early-type morphologies is not required for the quenching of star formation.

  5. Spirals in protoplanetary disks from photon travel time

    CERN Document Server

    Kama, M; Heays, A N

    2016-01-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put foward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ${\\sim}1\\,$au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk.

  6. Self-perpetuating Spiral Arms in Disk Galaxies

    Science.gov (United States)

    D'Onghia, Elena; Vogelsberger, Mark; Hernquist, Lars

    2013-03-01

    The causes of spiral structure in galaxies remain uncertain. Leaving aside the grand bisymmetric spirals with their own well-known complications, here we consider the possibility that multi-armed spiral features originate from density inhomogeneities orbiting within disks. Using high-resolution N-body simulations, we follow the motions of stars under the influence of gravity, and show that mass concentrations with properties similar to those of giant molecular clouds can induce the development of spiral arms through a process termed swing amplification. However, unlike in earlier work, we demonstrate that the eventual response of the disk can be highly non-linear, significantly modifying the formation and longevity of the resulting patterns. Contrary to expectations, ragged spiral structures can thus survive at least in a statistical sense long after the original perturbing influence has been removed.

  7. Effect of Annular Slit Geometry on Characteristics of Spiral Jet

    Institute of Scientific and Technical Information of China (English)

    Shigeru Matsuo; Kwon-Hee Lee; Shinsuke Oda; Toshiaki Setoguchi; Heuy-Dong Kim

    2003-01-01

    A spiral flow using an annular slit connected to a conical cylinder does not need special device to generate a tangential velocity component of the flow and differs from swirling flows. Pressurized fluid is supplied to an annular chamber and injected into the convergent nozzle through the annular slit. The annular jet develops into the spiral flow. In the present study, a spiral jet discharged out of nozzle exit was obtained by using a convergent nozzle and an annular slit set in nozzle inlet, and the effect of annular slit geometry on characteristics of the spiral jet was investigated by using a Laser Doppler Velocimeter (LDV) experimentally. Furthermore, velocity distributions of the spiral jet were compared with those of a normal jet.

  8. Two-dimensional optical thermal ratchets based on Fibonacci spirals.

    Science.gov (United States)

    Xiao, Ke; Roichman, Yael; Grier, David G

    2011-07-01

    An ensemble of symmetric potential energy wells arranged at the vertices of a Fibonacci spiral can serve as the basis for an irreducibly two-dimensional thermal ratchet. Periodic rotation of the potential energy landscape through a three-step cycle drives trapped Brownian particles along spiral trajectories through the pattern. Which spiral is selected depends on the angular displacement at each step, with transitions between selected spirals arising at rational proportions of the golden angle. Fibonacci spiral ratchets therefore display an exceptionally rich range of transport properties, including inhomogeneous states in which different parts of the pattern induce motion in different directions. Both the radial and angular components of these trajectories can undergo flux reversal as a function of the scale of the pattern or the rate of rotation.

  9. Breakup of spiral wave under different boundary conditions

    Institute of Scientific and Technical Information of China (English)

    Zhao Ying-Kui; Wang Guang-Rui; Chen Shi-Gang

    2007-01-01

    In this paper, we investigate the breakup of spiral wave under no-flux, periodic and Dirichlet boundary conditions respectively. When the parameter ε is close to a critical value for Doppler-induced wave breakup, the instability of the system caused by the boundary effect occurs in the last two cases, resulting in the breakup of spiral wave near the boundary. With our defined average order measure of spiral wave (AOMSW), we quantify the degree of order of the system when the boundary-induced breakup of spiral wave happens. By analysing the AOMSW and outer diameter R of the spiral tip orbit, it is easy to find that this boundary effect is correlated with large values of R, especially under the Dirichlet boundary condition. This correlation is nonlinear, so the AOMSW sometimes oscillates with the variation of ε.

  10. Suppression of Spiral Wave in Modified Orengonator Model

    Institute of Scientific and Technical Information of China (English)

    MA Jun; JIN Wu-Yin; YI Ming; WANG Chun-Ni

    2008-01-01

    In this paper, a spatial perturbation scheme is proposed to suppress the spiral wave in the modified Orengonator model, which is used to describe the chemical reaction in the light-sensitive media. The controllable external illumination Φ is perturbed with a spatial linear function. In our numerical simulation, the scheme is investigated by imposing the external controllable illumination on the space continuously and/or intermittently. The numerical simulation results confirm that the stable rotating spiral wave still can be removed with the scheme proposed in this paper even if the controllable Φ changed vs. time and space synchronously. Then the scheme is also used to control the spiral wave and turbulence in the modified Fitzhugh-Nagumo model It is found that the scheme is effective to remove the sable rotating and meandering spiral wave but it costs long transient period and intensity of the gradient parameter to eliminate the spiral turbulence.

  11. Spiraling between qualitative and quantitative data on women's health behaviors: a double helix model for mixed methods.

    Science.gov (United States)

    Mendlinger, Sheryl; Cwikel, Julie

    2008-02-01

    A double helix spiral model is presented which demonstrates how to combine qualitative and quantitative methods of inquiry in an interactive fashion over time. Using findings on women's health behaviors (e.g., menstruation, breast-feeding, coping strategies), we show how qualitative and quantitative methods highlight the theory of knowledge acquisition in women's health decisions. A rich data set of 48 semistructured, in-depth ethnographic interviews with mother-daughter dyads from six ethnic groups (Israeli, European, North African, Former Soviet Union [FSU], American/Canadian, and Ethiopian), plus seven focus groups, provided the qualitative sources for analysis. This data set formed the basis of research questions used in a quantitative telephone survey of 302 Israeli women from the ages of 25 to 42 from four ethnic groups. We employed multiple cycles of data analysis from both data sets to produce a more detailed and multidimensional picture of women's health behavior decisions through a spiraling process.

  12. Gas velocity patterns in simulated galaxies: Observational diagnostics of spiral structure theories

    CERN Document Server

    Baba, Junichi; Miyamoto, Yusuke; Egusa, Fumi; Kuno, Nario

    2016-01-01

    There are two theories of stellar spiral arms in isolated disc galaxies that model stellar spiral arms with different longevities: quasi-stationary density wave theory, which characterises spirals as rigidly rotating, long-lived patterns (i.e. steady spirals), and dynamic spiral theory, which characterises spirals as differentially rotating, transient, recurrent patterns (i.e. dynamic spirals). In order to discriminate between these two spiral models observationally, we investigated the differences between the gas velocity patterns predicted by these two spiral models in hydrodynamic simulations. We found that the azimuthal phases of the velocity patterns relative to the gas density peaks (i.e. gaseous arms) differ between the two models, as do the gas flows; nevertheless, the velocity patterns themselves are similar for both models. Such similarity suggests that the mere existence of streaming motions does not conclusively confirm the steady spiral model. However, we found that the steady spiral model shows ...

  13. A spectroscopic method for determining the luminosities of spiral galaxies and estimating their stellar population

    Science.gov (United States)

    Cowley, A. P.; Crampton, D.; McClure, R. D.

    1982-12-01

    Spectra of the nuclei of 44 normal spiral galaxies have been obtained using the McGraw-Hill Observatory intensified Reticon scanner. A composite spectral index, Σ, has been formed which measures the strengths of Ca II, Hδ , CH, and Mg, all of which correlate with absolute magnitude of the nuclear bulge. It is found that this index can predict the magnitudes of normal galaxies with a dispersion of 0.5 mag. This index is used to show that many galaxies within 6° of the Virgo cluster center, normally assumed to be members, may not be at the mean cluster distance. Using the same instrument, we also obtained fluxed spectra of halo globular clusters and solar neighborhood stars of both Population I and II. These data were used to construct simple population models for the nuclei of late-type spiral galaxies. It was found that, except in the case of the ˜2" semistellar nucleus in M33, the line strengths of Sc galaxy nuclei fit well models constructed from globular cluster observations but could not be reproduced using only a Population I stellar mix. The reverse was true, on the other hand, for the semistellar nucleus of M33, where a good fit is obtained by using young star light plus a smaller contribution from an old metalpoor population. We interpret this to indicate that the predominant light from the amorphous nuclear bulges of late-type spiral nuclei is old, but some of these galaxies may have had recent bursts of star formation that affect the spectral characteristics of a central component of the nucleus.

  14. Energetic constraints to chemo-photometric evolution of spiral galaxies

    Science.gov (United States)

    Buzzoni, Alberto

    2011-08-01

    The problem of chemo-photometric evolution of late-type galaxies is dealt with relying on prime physical arguments of energetic self-consistency between chemical enhancement of galaxy mass, through nuclear processing inside stars, and luminosity evolution of the system. Our analysis makes use of the Buzzoni template galaxy models along the Hubble morphological sequence. The contribution of Type II and Ia SNe is also accounted for in our scenario. Chemical enhancement is assessed in terms of the so-called ‘yield metallicity’ (?), that is the metal abundance of processed mass inside stars, as constrained by the galaxy photometric history. For a Salpeter initial mass function (IMF), ? being nearly insensitive to the galaxy star formation history. The interstellar medium (ISM) metallicity can be set in terms of ?, and just modulated by the gas fraction and the net fraction of returned stellar mass (f). For the latter, a safe upper limit can be placed, such as f≲ 0.3 at any age. The comparison with the observed age-metallicity relation allows us to set a firm upper limit to the Galaxy birthrate, such as b≲ 0.5, and to the chemical enrichment ratio ΔY/ΔZ≲ 5. About four out of five stars in the solar vicinity are found to match the expected ? figure within a factor of 2, a feature that leads us to conclude that star formation in the Galaxy must have proceeded, all the time, in a highly contaminated environment where returned stellar mass is in fact the prevailing component to gas density. The possible implication of the Milky Way scenario for the more general picture of late-type galaxy evolution is discussed moving from three relevant relationships, as suggested by the observations. Namely (i) the down-sizing mechanism appears to govern star formation in the local Universe; (ii) the ‘delayed’ star formation among low-mass galaxies, as implied by the inverse b-Mgal dependence, naturally leads to a more copious gas fraction when moving from giant to dwarf

  15. Spiral CT venography in central venous obstruction

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Jin Wook; Park, Jae Hyung; Im, Jung Gi; Han, Moon Hee; Kim, In One; Chang, Kee Hyun; Yeon, Kyung Mo [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of); Song, Chi Sung [Boramae Hospital, Seoul (Korea, Republic of)

    1998-11-01

    To determine the clinical usefulness of spiral computed tomographic (CT) venography for the evaluation of central venous obstruction. The authors prospectively performed a total of 29 spiral CT venography procedures in 25 consecutive patients with suspected central venous obstrucion. Diluted contrast media were directly injected into the peripheral veins of the hand or the foot. Scan parameters were 3mm X-ray beam collimation, table speed of 4-6cm/sec, scan time of 32-40sec, and injection delay of 20 sec. Axial images were reconstructed at 2-mm intervals, and using shaded surface display(SSD), maximum intensity projection(MIP), and multiplanar reformation(MPR), 3-D reconstruction was performed. In all cases, ascending venograp-hy(n=3D13) and/or direct catheter venography (n=3D21) was performed within 2 days of CT venography. With regard to site, extent, extent, severity, and cause of obstruction and collateral circulation, we compared the results of CT and contrast venography. In 24 patients, a total of 56 sites of central venous obstruction or stenosis (>50%) were demonstrated. The causes of obstruction were venous thrombosis(n=3D6), malignant tumors(n=3D4), arteriovenous fistula for hemodialysis(n=3D5), extrinsic compression(n=3D2), coincidence of extrinsic compression and arteriovenous fistula(n=3D1), pacemaker(n=3D1), mediastinal inflammatory pseudotumor(n=3D1), spinal tuberculosis(n=3D1), membranous obstruction of the hepatic inferior vena cava(n=3D1), Behcet's disease(n=3D1), or unknown cause(n=3D1). When compared with ascending venography(n=3D13), CT venography was superior for evaluation of the extent and cause of obstruction and collateral circulation in two, four and one case(s), respectively. For the evaluation of site and severity of obstruction, CT venography was equal to ascending venography. In two cases, direct catheter venography (n=3D21) was superior to CT venography for evaluating the obstruction site, but in three, five and one case

  16. Simulation of Conformal Spiral Slot Antennas on Composite Platforms

    Science.gov (United States)

    Volakis, J. L.; Nurnberger, M. W.; Ozdemir,T.

    1998-01-01

    During the course of the grant, we wrote and distributed about 12 reports and an equal number of journal papers supported fully or in part by this grant. The list of reports (title & abstract) and papers are given in Appendices A and B. This grant has indeed been instrumental in developing a robust hybrid finite element method for the analysis of complex broadband antennas on doubly curved platforms. Previous to the grant, our capability was limited to simple printed patch antennas on mostly planar platforms. More specifically: (1) mixed element formulations were developed and new edge-based prisms were introduced; (2) these elements were important in permitting flexibility in geometry gridding for most antennas of interest; (3) new perfectly matched absorbers were introduced for mesh truncations associated with highly curved surfaces; (4) fast integral algorithms were introduced for boundary integral truncations reducing CPU time from O(N-2) down to O(N-1.5) or less; (5) frequency extrapolation schemes were developed for efficient broadband performance evaluations. This activity has been successfully continued by NASA researchers; (6) computer codes were developed and extensively tested for several broadband configurations. These include FEMA-CYL, FEMA-PRISM and FEMA-TETRA written by L. Kempel, T. Ozdemir and J. Gong, respectively; (7) a new infinite balun feed was designed nearly constant impedance over the 800-3000 MHz operational band; (8) a complete slot spiral antenna was developed, fabricated and tested at NASA Langley. This new design is a culmination of the projects goals and integrates the computational and experimental efforts. this antenna design resulted in a U.S. patent and was revised three times to achieve the desired bandwidth and gain requirements from 800-3000 MHz.

  17. Predicting the impact of feed spacer modification on biofouling by hydraulic characterization and biofouling studies in membrane fouling simulators

    KAUST Repository

    Siddiqui, A.

    2016-12-22

    Feed spacers are an essential part of spiral-wound reverse osmosis (RO) and nanofiltration (NF) membrane modules. Geometric modification of feed spacers is a potential option to reduce the impact of biofouling on the performance of membrane systems. The objective of this study was to evaluate the biofouling potential of two commercially available reference feed spacers and four modified feed spacers. The spacers were compared on hydraulic characterization and in biofouling studies with membrane fouling simulators (MFSs). The virgin feed spacer was characterized hydraulically by their resistance, measured in terms of feed channel pressure drop, performed by operating MFSs at varying feed water flow rates. Short-term (9 days) biofouling studies were carried out with nutrient dosage to the MFS feed water to accelerate the biofouling rate. Long-term (96 days) biofouling studies were done without nutrient dosage to the MFS feed water. Feed channel pressure drop was monitored and accumulation of active biomass was quantified by adenosine tri phosphate (ATP) determination. The six feed spacers were ranked on pressure drop (hydraulic characterization) and on biofouling impact (biofouling studies). Significantly different trends in hydraulic resistance and biofouling impact for the six feed spacers were observed. The same ranking for biofouling impact on the feed spacers was found for the (i) short-term biofouling study with nutrient dosage and the (ii) long-term biofouling study without nutrient dosage. The ranking for hydraulic resistance for six virgin feed spacers differed significantly from the ranking of the biofouling impact, indicating that hydraulic resistance of clean feed spacers does not predict the hydraulic resistance of biofouled feed spacers. Better geometric design of feed spacers can be a suitable approach to minimize impact of biofouling in spiral wound membrane systems.

  18. New insights into the X-ray properties of the nearby barred spiral galaxy NGC 1672

    CERN Document Server

    Jenkins, L P; Colbert, E J M; Levan, A J; Roberts, T P; Ward, M J; Zezas, A

    2008-01-01

    We present some preliminary results from new Chandra and XMM-Newton X-ray observations of the nearby barred spiral galaxy NGC1672. It shows dramatic nuclear and extra-nuclear star formation activity, including starburst regions located near each end of its strong bar, both of which host ultraluminous X-ray sources (ULXs). With the new high-spatial-resolution Chandra imaging, we show for the first time that NGC1672 possesses a faint ($L(X)~10^39 erg/s), hard central X-ray source surrounded by an X-ray bright circumnuclear starburst ring that dominates the X-ray emission in the region. The central source may represent low-level AGN activity, or alternatively the emission from X-ray binaries associated with star-formation in the nucleus.

  19. Digital spiral object identification using random light

    CERN Document Server

    Yang, Zhe; Mirhosseini, Mohammad; Zhou, Yiyu; Gao, Boshen; Gao, Lu; Rafsanjani, Seyed Mohammad Hashemi; Long, Guilu; Boyd, Robert W

    2016-01-01

    Photons that are entangled or correlated in orbital angular momentum have been extensively used for remote sensing, object identification and imaging. It has recently been demonstrated that intensity fluctuations give rise to the formation of correlations in the orbital angular momentum components and angular positions of random light. Here, we demonstrate that the spatial signatures and phase information of an object, with rotational symmetries, can be identified using classical orbital angular momentum correlations in random light. The Fourier components imprinted in the digital spiral spectrum of the object, measured through intensity correlations, unveil its spatial and phase information. Sharing similarities with conventional compressive sensing protocols that exploit sparsity to reduce the number of measurements required to reconstruct a signal, our technique allows sensing of an object with fewer measurements than other schemes that use pixel-by-pixel imaging. One remarkable advantage of our technique ...

  20. Spiral shocks and accretion in discs

    Energy Technology Data Exchange (ETDEWEB)

    Spruit, H.C.; Matsuda, T.; Inoue, M.; Sawada, K.

    1987-12-01

    Recent numerical and analytical results on disc-like accretion with shock waves as the only dissipation mechanism are compared. The global properties of the process are similar to those of the viscous (..cap alpha..) disc model, but precise values of the effective ..cap alpha.. value as a function of the accretion rate can be calculated. At low values of the ratio of specific heats (..gamma.. < 1.45) accretion is possible without radiative losses. Such adiabatic accretion can occur in practice at high accretion rates on to low mass objects and may be important in the formation of planets. Following previous authors, it is pointed out that non-axisymmetric perturbations in the outer parts of a disc increase in amplitude as they propagate in and cause spiral shocks more easily in a disc than perturbations originating in the inner parts.

  1. Characterizing spiral arm and interarm star formation

    CERN Document Server

    Kreckel, K; Schinnerer, E; Groves, B; Adamo, A; Hughes, A; Meidt, S

    2016-01-01

    Interarm star formation contributes significantly to a galaxy's star formation budget, and provides an opportunity to study stellar birthplaces unperturbed by spiral arm dynamics. Using optical integral field spectroscopy of the nearby galaxy NGC 628 with VLT/MUSE, we identify 391 HII regions at 35pc resolution over 12 kpc^2. Using tracers sensitive to the underlying gravitational potential, we associate HII regions with either arm (271) or interarm (120) environments. We find that most HII region physical properties (luminosity, size, metallicity, ionization parameter) are independent of environment. We calculate the fraction of Halpha luminosity due to the diffuse ionized gas (DIG) background contaminating each HII region, and find the DIG surface brightness to be higher within HII regions compared to the surroundings, and slightly higher within arm HII regions. Use of the temperature sensitive [SII]/Halpha line ratio map instead of the Halpha surface brightness to identify HII region boundaries does not ch...

  2. The spiral structure of our Milky Way Galaxy

    CERN Document Server

    Hou, L G; Shi, W B

    2009-01-01

    The spiral structure of our Milky Way Galaxy is not yet known. HII regions and Giant molecular clouds are the most prominent spiral tracers. The 2-, 3- and 4-arm models have previously been proposed to outline the structure of our Galaxy. Recently, new data of spiral tracers covering a larger region of the Galactic disk have been published in literature. We wish to obtain the updated spiral structure of the Milky way using all tracer data. We collected the spiral tracer data of our Milky Way from literature, namely, HII regions and giant molecular clouds (GMCs). With the weighting factors based on the excitation parameters of HII regions or the masses of GMCs, we fitted the distribution of these tracers with the models of two-, three-, four-spiral-arms or polynomial spiral arms. The distances of tracers, if not available from stellar or direct measurements, were estimated kinetically from the standard rotation curve of Brand & Blitz (1993) with R_0=8.5 kpc, and \\Theta_0 =220 km s^{-1} or the newly fitted ...

  3. The Nature of Red-Sequence Cluster Spiral Galaxies

    Science.gov (United States)

    Kashur, Lane; Barkhouse, Wayne; Sultanova, Madina; Kalawila Vithanage, Sandanuwa; Archer, Haylee; Foote, Gregory; Mathew, Elijah; Rude, Cody; Lopez-Cruz, Omar

    2017-01-01

    Preliminary analysis of the red-sequence galaxy population from a sample of 57 low-redshift galaxy clusters observed using the KPNO 0.9m telescope and 74 clusters from the WINGS dataset, indicates that a small fraction of red-sequence galaxies have a morphology consistent with spiral systems. For spiral galaxies to acquire the color of elliptical/S0s at a similar luminosity, they must either have been stripped of their star-forming gas at an earlier epoch, or contain a larger than normal fraction of dust. To test these ideas we have compiled a sample of red-sequence spiral galaxies and examined their infrared properties as measured by 2MASS, WISE, Spitzer, and Herschel. These IR data allows us to estimate the amount of dust in each of our red-sequence spiral galaxies. We compare the estimated dust mass in each of these red-sequence late-type galaxies with spiral galaxies located in the same cluster field but having colors inconsistent with the red-sequence. We thus provide a statistical measure to discriminate between purely passive spiral galaxy evolution and dusty spirals to explain the presence of these late-type systems in cluster red-sequences.

  4. Spiral Antenna-Coupled Microbridge Structures for THz Application.

    Science.gov (United States)

    Gou, Jun; Zhang, Tian; Wang, Jun; Jiang, Yadong

    2017-12-01

    Bolometer sensor is a good candidate for THz imaging due to its compact system, low cost, and wideband operation. Based on infrared microbolometer structures, two kinds of antenna-coupled microbridge structures are proposed with different spiral antennas: spiral antenna on support layer and spiral antenna with extended legs. Aiming at applications in detection and imaging, simulations are carried out mainly for optimized absorption at 2.52 THz, which is the radiation frequency of far-infrared CO2 lasers. The effects of rotation angle, line width, and spacing of the spiral antenna on THz wave absorption of microbridge structures are discussed. Spiral antenna, with extended legs, is a good solution for high absorption rate at low absorption frequency and can be used as electrode lead simultaneously for simplified manufacturing process. A spiral antenna-coupled microbridge structure with an absorption rate of more than 75% at 2.52 THz is achieved by optimizing the structure parameters. This research demonstrates the use of different spiral antennas for enhanced and tunable THz absorption of microbridge structures and provides an effective way to fabricate THz microbolometer detectors with great potential in the application of real-time THz imaging.

  5. Drift of rigidly rotating spirals under periodic and noisy illuminations.

    Science.gov (United States)

    Zhang, Hong; Wu, Ning-Jie; Ying, He-Ping; Hu, Gang; Hu, Bambi

    2004-10-15

    Under the weak deformation approximation, the motion of rigidly rotating spirals induced by periodic and noisy illuminations are investigated analytically. We derive an approximate but explicit formula of the spiral drift velocity directly from the original reaction-diffusion equation. With this formula we are able to explain the main features in the periodic and noisy illuminations induced spiral drift problems. Numerical computations of the Oregonator model are carried out as well, and they agree with the main qualitative conclusions of our analytical results.

  6. Fabrication of Meander and Spiral Type Micro Inductors

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    To obtain microstructure of magnetic devices, the thin film inductors were fabricated by the process such as thin film manufacturing, photolithography and wet etching. The freouency characteristics of these devices are measured at high frequency range. When the inductor sizes of the spiral and the meander type are same, the inductance and the quality factor of the spiral type inductor are larger than those of the meander type inductor, but the driving frequency of the spiral type inductor is lower than that of the meander type inductor.

  7. Spiral Magnetic Order in the One-Dimensional Kondo Lattice

    Institute of Scientific and Technical Information of China (English)

    LIU Zhen-Rong; LI Zheng-Zhong; SHEN Rui

    2001-01-01

    The effects of c-f (conduction-f electrons) hybridization on the spiral spin magnetism in the one dimensional Kondo lattice are studied. By using the mean-field approximation, a close set of equations of the Green's functions with arbitrary wave vector Q for the spiral ordering of spins is deduced. The magnetic phase boundary between the spiral magnetism and ferromagnetism has been calculated approximately. From our qualitative results, one can find that the ferromagnetic region is enlarged due to the c f hybridization. Moreover, some new results reflecting the Kondo effect, such as the modified dispersion relation and the weakening of the localized magnetic moments are also obtained.

  8. A Software Development Simulation Model of a Spiral Process

    Science.gov (United States)

    Mizell, Carolyn; Malone, Linda

    2007-01-01

    There is a need for simulation models of software development processes other than the waterfall because processes such as spiral development are becoming more and more popular. The use of a spiral process can make the inherently difficult job of cost and schedule estimation even more challenging due to its evolutionary nature, but this allows for a more flexible process that can better meet customers' needs. This paper will present a discrete event simulation model of spiral development that can be used to analyze cost and schedule effects of using such a process in comparison to a waterfall process.

  9. Measurements of the equivalent thicknesses of three-dimensional spiral galactic disks

    Institute of Scientific and Technical Information of China (English)

    Gang Li; Zhi-Quan Luo; Qiu-He Peng

    2009-01-01

    Spiral arms are fitted after the data from the latest spiral galactic images re-leased by the Sloan Digital Sky Survey are processed. Equivalent thicknesses of 42 spiral galactic disks are derived, which increase the foundational data for further research about spiral galaxies.

  10. Intrinsic inhomogeneities and the coexistence of spirals with different periods of rotation.

    Science.gov (United States)

    Tranquillo, Joseph; Howes, Meghan

    2008-11-01

    We propose a mechanism by which wave fronts emanating from a spiral may break far from the spiral core due to intrinsic spatial inhomogeneities. A series of computer simulations are presented to demonstrate how coupling domains, which on their own would not cause breakup, may cause a single spiral to break into many spirals.

  11. Feeding and feedback in radio galaxies of the local universe

    Science.gov (United States)

    Couto, Guilherme dos Santos

    2016-10-01

    We present integral field spectroscopic data covering the inner kiloparsecs of four radio galaxies of the local Universe (zGMOS-IFU instrument of the Gemini telescopes. We use these data to analyze the gas excitation and kinematics via two-dimensional maps. Using the flux distributions of the emission lines, we identify extended emission in ionized gas up to the edges of the observed field, which corresponds to 1.7 kpc x 2.5 kpc for Arp 102B, 2.5 kpc x 3.4 kpc for Pictor A, 4.0 kpc x 5.8 kpc for 3C 33 and 4.3 kpc x 6.2 kpc for 4C +29.30. The extended line emitting gas displays structures resembling rotating disks, spiral arms and bars. Line ratios indicate that both photons from the nuclear source and shocks originated in the interaction of the radio jet with circumnuclear gas are ionizing mechanisms of the gas. Line ratio values are typical of Seyfert galaxies for 3C 33 and 4C +29.30, while intermediate values between Seyferts and LINERs are observed in Arp 102B. Pictor A galaxy, however, shows low values of [NII]/Ha=0.15-0.25, expected for HII regions. We suggest that these values are observed due to the low gas metallicity (12+log(O/H)=8.39). Centroid velocity maps show that the gas kinematics is dominated by rotation only in Arp 102B and 3C 33. Outflows are observed in the galaxies Arp 102B, 3C 33 and 4C +29.30. We obtain mass outflow rates of 0.32-0.49 Msun per year, but the outflow kinetic power is small, ranging 0.04-0.07% of the AGN bolometric luminosity, indicating that the feedback has little impact in the host galaxies evolution. The high masses of ionized gas, ranging from 7.4E7 to 4.6E8 Msun, and the fact that these galaxies are early-type, suggest an external origin of the gas. Indeed, it is observed evidence of interaction with companion galaxies in Arp 102B, Pictor A and 4C +29.30. We suggest that the capture of mass has triggered the nuclear activity in these galaxies, with the high masses feeding not only the SMBH but also being a possible source

  12. Experimental and numerical characterization of the water flow in spacer-filled channels of spiral-wound membranes

    KAUST Repository

    Bucs, Szilard S.

    2015-09-25

    Micro-scale flow distribution in spacer-filled flow channels of spiral-wound membrane modules was determined with a particle image velocimetry system (PIV), aiming to elucidate the flow behaviour in spacer-filled flow channels. Two-dimensional water velocity fields were measured in a flow cell (representing the feed spacer-filled flow channel of a spiral wound reverse osmosis membrane module without permeate production) at several planes throughout the channel height. At linear flow velocities (volumetric flow rate per cross-section of the flow channel considering the channel porosity, also described as crossflow velocities) used in practice (0.074 and 0.163 m∙s-1) the recorded flow was laminar with only slight unsteadiness in the upper velocity limit. At higher linear flow velocity (0.3 m∙s-1) the flow was observed to be unsteady and with recirculation zones. Measurements made at different locations in the flow cell exhibited very similar flow patterns within all feed spacer mesh elements, thus revealing the same hydrodynamic conditions along the length of the flow channel. Three-dimensional (3-D) computational fluid dynamics simulations were performed using the same geometries and flow parameters as the experiments, based on steady laminar flow assumption. The numerical results were in good agreement (0.85-0.95 Bray-Curtis similarity) with the measured flow fields at linear velocities of 0.074 and 0.163 m∙s-1, thus supporting the use of model-based studies in the optimization of feed spacer geometries and operational conditions of spiral wound membrane systems.

  13. Pattern formation of coupled spiral waves in bilayer systems: rich dynamics and high-frequency dominance.

    Science.gov (United States)

    Nie, Haichun; Gao, Jihua; Zhan, Meng

    2011-11-01

    The interaction of two spiral waves with independent frequencies in a bilayer oscillatory medium (one spiral in each layer) and with a symmetric coupling e is studied. If the spirals have different frequencies, the faster spiral is unaffected by the slower one, and the slower can show a variety of behaviors, which depend on e and include, in order of increasing e, phase drifting, amplitude modulation, amplitude domination, and phase synchronization. This high-frequency dominance, the asymmetric driving-response effect under the condition of a symmetric coupling, is generic and independent of whether the coupled spiral waves are outwardly rotating or inwardly rotating spirals. If the spirals have identical frequencies, they may even show complete synchronization, parallel drift, or circular drift, depending on the relative rotation direction of the two spirals and their initial separation distance. Comparisons with coupled spirals in monolayer media, previous works on coupled spirals in bilayer systems, and coupled phase oscillators are made.

  14. DNA Taxonomy of Paranemertes (Nemertea: Hoplonemertea) with Spirally Fluted Stylets.

    Science.gov (United States)

    Hao, Yue; Kajihara, Hiroshi; Chernyshev, Alexei V; Okazaki, Robert K; Sun, Shi-Chun

    2015-12-01

    Of the 14 nominal species that are now or have ever been assigned to the genus Paranemertes Coe, 1901 , four have been reported to have stylets with a spirally fluted or braided appearance. Although differentiation in color patterns has been documented among species/populations, these nemerteans share similar external characters. Using the sequence datasets of mitochondrial cytochrome c oxidase subunit I (COI), 16S rRNA, and nuclear 28S rRNA genes of specimens from 14 localities of Canada, USA, Russia, Japan, and China, we analyzed the genetic differentiation and reconstructed the phylogenetic trees for these nemerteans. In conjunction with the external characters, we discuss their taxonomy and species delimitation. An analysis based on COI dataset showed high genetic variations among populations and even among worms from the same geographic area. The analyzed 111 individuals were assigned into seven networks by statistical parsimony analysis. The inter-network uncorrected p-distances ranged from 0.044 to 0.172 and the mean intra-network uncorrected p-distances varied from 0.001 to 0.005. With the exception of two networks that contain specimens from the East China Sea, all networks were well-supported by the results of Bayesian and neighbor-joining analyses on the COI data. Phylogenetic trees based on 16S rRNA and 28S rRNA datasets were basically similar to the COI trees, but specimens in some networks were merged into larger clades. Present molecular analyses support the validity of P. sanjuanensis and the synonymization of P. cylindracea with P. peregrina. Nemerteans previously recorded as P. peregrina may contain several species and sympatric speciation might have been occurred in this nemertean group.

  15. Left-handed compact MIMO antenna array based on wire spiral resonator for 5-GHz wireless applications

    Science.gov (United States)

    Alqadami, Abdulrahman Shueai Mohsen; Jamlos, Mohd Faizal; Soh, Ping Jack; Rahim, Sharul Kamal Abdul; Narbudowicz, Adam

    2017-01-01

    A compact coplanar waveguide-fed multiple-input multiple-output antenna array based on the left-handed wire loaded spiral resonators (SR) is presented. The proposed antenna consists of a 2 × 2 wire SR with two symmetrical microstrip feed lines, each line exciting a 1 × 2 wire SR. Left-handed metamaterial unit cells are placed on its reverse side and arranged in a 2 × 3 array. A reflection coefficient of less than -16 dB and mutual coupling of less than -28 dB are achieved at 5.15 GHz WLAN band.

  16. Effects of semiclassical spiral fluctuations on hole dynamics

    Science.gov (United States)

    Hamad, I. J.; Manuel, L. O.; Trumper, A. E.

    2012-01-01

    We investigate the dynamics of a single hole coupled to the spiral fluctuations related to the magnetic ground states of the antiferromagnetic J1-J2-J3 Heisenberg model on a square lattice. Using exact diagonalization on finite size clusters and the self-consistent Born approximation in the thermodynamic limit, we find, as a general feature, a strong reduction of the quasiparticle weight along the spiral phases of the magnetic phase diagram. For an important region of the Brillouin zone the hole spectral functions are completely incoherent, whereas at low energies the spectral weight is redistributed on several irregular peaks. We find a characteristic value of the spiral pitch Q=(0.7,0.7)π, for which the available phase space for hole scattering is maximum. We argue that this behavior is due to the nontrivial interference of the magnon-assisted and the free-hopping mechanism for hole motion, characteristic of a hole coupled to semiclassical spiral fluctuations.

  17. Spiral formation at microscale by μ-pyro-electrospinning

    Science.gov (United States)

    Mecozzi, L.; Gennari, O.; Rega, R.; Grilli, S.; Bhowmick, S.; Gioffrè, M. A.; Coppola, G.; Ferraro, P.

    2016-05-01

    Spiral shapes occur frequently in nature, such as in case of snail shells or in case of the so-called cochlea, namely the auditory portion of the inner ear. They also inspire many technological devices that take advantage of this geometry. Here we show that μ-pyro electrospinning is able to control the whipping instabilities in order to form polymeric spirals directly onto the target support and with true regularity at microscale. The results show that the polymer concentration plays a key role in producing reliable and long spirals. We investigate the cell response to these spiral templates that, thanks to their true regularity, would be useful for developing innovative cochlea regeneration scaffolds.

  18. Halpha Morphologies and Environmental Effects in Virgo Cluster Spiral Galaxies

    CERN Document Server

    Koopmann, R A

    2004-01-01

    We describe the various Halpha morphologies of Virgo Cluster and isolated spiral galaxies, and associate the Halpha morphologies with the types of environmental interactions which have altered the cluster galaxies. The spatial distributions of Halpha and R-band emission are used to divide the star formation morphologies of the 52 Virgo Cluster spirals into several categories: normal (37%), anemic (6%), enhanced (6%), and (spatially) truncated (52%). Truncated galaxies are further subdivided based on their inner star formation rates into truncated/normal (37%), truncated/compact (6%), truncated/anemic (8%), and truncated/enhanced (2%). The fraction of anemic galaxies is relatively small (6-13%) in both environments, suggesting that starvation is not a major factor in the reduced star formation rates of Virgo spirals. The majority of Virgo spiral galaxies have their Halpha disks truncated (52%), whereas truncated Halpha disks are rarer in isolated galaxies (12%). Most of the Halpha-truncated galaxies have relat...

  19. 'Reading' bubble chamber pictures with the Spiral Reader eyes.

    CERN Multimedia

    1974-01-01

    Interactive techniques were widely used to study bubble chamber pictures. After a visual scanning of the pictures and a vertex measurement on a Shivamatic, the Spiral Reader allowed the track polar coordinates to be easily measured. See photo 7408137X

  20. Topological signatures in the electronic structure of graphene spirals.

    Science.gov (United States)

    Avdoshenko, Stas M; Koskinen, Pekka; Sevinçli, Haldun; Popov, Alexey A; Rocha, Claudia G

    2013-01-01

    Topology is familiar mostly from mathematics, but also natural sciences have found its concepts useful. Those concepts have been used to explain several natural phenomena in biology and physics, and they are particularly relevant for the electronic structure description of topological insulators and graphene systems. Here, we introduce topologically distinct graphene forms - graphene spirals - and employ density-functional theory to investigate their geometric and electronic properties. We found that the spiral topology gives rise to an intrinsic Rashba spin-orbit splitting. Through a Hamiltonian constrained by space curvature, graphene spirals have topologically protected states due to time-reversal symmetry. In addition, we argue that the synthesis of such graphene spirals is feasible and can be achieved through advanced bottom-up experimental routes that we indicate in this work.

  1. CFD numerical simulation of Archimedes spiral inlet hydrocyclone

    Science.gov (United States)

    Zhang, L.; Wei, L.; Chang, B. H.; Xing, J. L.; Jia, K.

    2013-12-01

    For traditional linear type inlet, hydrocyclone has an unstable inner field, high turbulence intensity and low separation efficiency, this paper proposes an inlet mode that uses an Archimedes spiral hydrocyclone. A Mixture liquid-solid multiphase flow model combined with the kinetic theory of granular flow was used to simulate the high concentration water-sand-air three-phase flow in a hydrocyclone. We analyzed the pressure field, velocity field and turbulent kinetic energy and compared with traditional linear type inlet hydrocyclone inner field. The results show that Archimedes spiral inlet hydrocyclone's pressure field is evenly distributed. The Archimedes spiral inlet hydrocyclone can guide and accelerate the mixture flow and produce small forced vortex and less short circuit flow. The particles easily go to the outer vortex and are separated. The Archimedes spiral inlet hydrocyclone has effectively improved the stability of inner flow field and separation efficiency.

  2. Data Fusion Tool for Spiral Bevel Gear Condition Indicator Data

    Science.gov (United States)

    Dempsey, Paula J.; Antolick, Lance J.; Branning, Jeremy S.; Thomas, Josiah

    2014-01-01

    Tests were performed on two spiral bevel gear sets in the NASA Glenn Spiral Bevel Gear Fatigue Test Rig to simulate the fielded failures of spiral bevel gears installed in a helicopter. Gear sets were tested until damage initiated and progressed on two or more gear or pinion teeth. During testing, gear health monitoring data was collected with two different health monitoring systems. Operational parameters were measured with a third data acquisition system. Tooth damage progression was documented with photographs taken at inspection intervals throughout the test. A software tool was developed for fusing the operational data and the vibration based gear condition indicator (CI) data collected from the two health monitoring systems. Results of this study illustrate the benefits of combining the data from all three systems to indicate progression of damage for spiral bevel gears. The tool also enabled evaluation of the effectiveness of each CI with respect to operational conditions and fault mode.

  3. Cassini Discovers a Kinematic Spiral Ring around Saturn

    National Research Council Canada - National Science Library

    S. Charnoz; C. C. Porco; E. Déau; A. Brahic; J. N. Spitale; C. Bacques; K. Baillie

    2005-01-01

    .... New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least three times around Saturn...

  4. Cassini discovers a kinematic spiral ring around Saturn.

    Science.gov (United States)

    Charnoz, S; Porco, C C; Déau, E; Brahic, A; Spitale, J N; Bacques, G; Baillie, K

    2005-11-25

    Since the time of the Voyager flybys of Saturn in 1980-1981, Saturn's eccentric F ring has been known to be accompanied on either side by faint strands of material. New Cassini observations show that these strands, initially interpreted as concentric ring segments, are in fact connected and form a single one-arm trailing spiral winding at least three times around Saturn. The spiral rotates around Saturn with the orbital motion of its constituent particles. This structure is likely the result of differential orbital motion stretching an initial cloud of particles scattered from the dense core of the F ring. Different scenarios of formation, implying ringlet-satellite interactions, are explored. A recently discovered moon candidate, S/2004 S6, is on an orbit that crosses the F-ring core at the intersection of the spiral with the ring, which suggests a dynamical connection between S/2004 S6 and the spiral.

  5. The role of multislice spiral CT in clinical cardiology

    Energy Technology Data Exchange (ETDEWEB)

    Haberl, R.; Boehme, E.; Richartz, B.; Czernik, A.; Buck, J.; Steinbigler, P. [Medical Hospital I and Department of Radiology, Klinik Muenchen-Pasing, Munich (Germany)

    2004-05-01

    Multislice spiral CT provides diagnostic-quality images of native coronary arteries and bypasses. Indications include prognosis in asymptomatic individuals, detection of significant coronary stenosis, and follow-up after interventions or surgery.

  6. Resonance Related Spiral Substructure in a Galactic Gaseous Disk

    CERN Document Server

    Yáñez, Miguel A; Martos, Marco A; Hayes, John C

    2007-01-01

    We use high resolution 2D hydrodynamic simulations to study the formation of spiral substructure in the gaseous disk of a galaxy. The obtained gaseous response is driven by a self-consistent non-axisymmetric potential obtained from an imposed spiral mass distribution. We highlight the importance of ultraharmonic resonances in generating these features. The temporal evolution of the system is followed with the parallel ZEUS-MP code, and we follow the steepening of perturbations induced by the spiral potential until large-scale shocks emerge. These shocks exhibit bifurcations that protrude from the gaseous arms and continue to steepen until new shocks are formed. When the contribution from the spiral potential relative to the axisymmetric background is increased from our default value, spurs protrude from the main arms after several revolutions of the gaseous disk. Such spurs overlap on top of the aforementioned shocks. These results support the hypothesis that a complicated gaseous response can coexist with an...

  7. Effects of abnormal excitation on the dynamics of spiral waves

    Science.gov (United States)

    Min-Yi, Deng; Xue-Liang, Zhang; Jing-Yu, Dai

    2016-01-01

    The effect of physiological and pathological abnormal excitation of a myocyte on the spiral waves is investigated based on the cellular automaton model. When the excitability of the medium is high enough, the physiological abnormal excitation causes the spiral wave to meander irregularly and slowly. When the excitability of the medium is low enough, the physiological abnormal excitation leads to a new stable spiral wave. On the other hand, the pathological abnormal excitation destroys the spiral wave and results in the spatiotemporal chaos, which agrees with the clinical conclusion that the early after depolarization is the pro-arrhythmic mechanism of some anti-arrhythmic drugs. The mechanisms underlying these phenomena are analyzed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11365003 and 11165004).

  8. Nuclear Confidence

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The Fukushima nuclear accident provides valuable lessons for China national nuclear Corp.as it continues to expand its operations AS Japan’s Fukushima nuclear crisis sparks a global debate over nuclear safety,China National Nuclear Corp. (CNNC),the country’s largest nuclear plant operator, comes under the spotlight.

  9. Porosity of spacer-filled channels in spiral-wound membrane systems: Quantification methods and impact on hydraulic characterization

    KAUST Repository

    Siddiqui, A.

    2017-04-13

    The porosity of spacer-filled feed channels influences the hydrodynamics of spiral-wound membrane systems and impacts the overall performance of the system. Therefore, an exact measurement and a detailed understanding of the impact of the feed channel porosity is required to understand and improve the hydrodynamics of spiral-wound membrane systems applied for desalination and wastewater reuse. The objectives of this study were to assess the accuracy of porosity measurement techniques for feed spacers differing in geometry and thickness and the consequences of using an inaccurate method on hydrodynamic predictions, which may affect permeate production. Six techniques were applied to measure the porosity namely, three volumetric calculations based on spacer strand count together with cuboidal (SC), cylindrical (VCC) and ellipsoidal volume calculation (VCE) and three independent techniques based on volume displacement (VD), weight and density (WD) and computed tomography scanning (CT). The CT method was introduced as an alternative for the other five already existing and applied methods in practice.Six feed spacers used for the porosity measurement differed in filament thickness, angle between the filaments and mesh-size. The results of the studies showed differences between the porosities, measured by the six methods. The results of the microscopic techniques SC, VCC and VCE deviated significantly from measurements by VD, WD and CT, which showed similar porosity values for all spacer types.Depending on the maximum deviation of the porosity measurement techniques from –6% to +6%, (i) the linear velocity deviations were −5.6% and +6.4% respectively and (ii) the pressure drop deviations were –31% and +43% respectively, illustrating the importance of an accurate porosity measurement. Because of the accuracy and standard deviation, the VD and WD method should be applied for the porosity determination of spacer-filled channels, while the CT method is recommended for

  10. Gas Ejection from Spiral Galaxy Disks

    Science.gov (United States)

    Durelle, Jeremy

    We present the results of three proposed mechanisms for ejection of gas from a spiral arm into the halo. The mechanisms were modelled using magnetohydrodynamics (MHD) as a theoretical template. Each mechanism was run through simulations using a Fortran code: ZEUS-3D, an MHD equation solver. The first mechanism modelled the gas dynamics with a modified Hartmann flow which describes the fluid flow between two parallel plates. We initialized the problem based on observation of lagging halos; that is, that the rotational velocity falls to a zero at some height above the plane of the disk. When adopting a density profile which takes into account the various warm and cold H I and HII molecular clouds, the system evolves very strangely and does not reproduce the steady velocity gradient observed in edge-on galaxies. This density profile, adopted from Martos and Cox (1998), was used in the remaining models. However, when treating a system with a uniform density profile, a stable simulation can result. Next we considered supernova (SN) blasts as a possible mechanism for gas ejection. While a single SN was shown to be insufficient to promote vertical gas structures from the disk, multiple SN explosions proved to be enough to promote gas ejection from the disk. In these simulations, gas ejected to a height of 0.5 kpc at a velocity of 130 km s--1 from 500 supernovae, extending to an approximate maximum height of 1 kpc at a velocity of 6.7 x 103 km s--1 from 1500 supernovae after 0.15 Myr, the approximate time of propagation of a supernova shock wave. Finally, we simulated gas flowing into the spiral arm at such a speed to promote a jump in the disk gas, termed a hydraulic jump. The height of the jump was found to be slightly less than a kiloparsec with a flow velocity of 41 km s--1 into the halo after 167 Myr. The latter models proved to be effective mechanisms through which gas is ejected from the disk whereas the Hartmann flow (or toy model) mechanism remains unclear as the

  11. Rotation curves of 967 spiral galaxies: implications for dark matter.

    Science.gov (United States)

    Persic, M.; Salucci, P.; Stel, F.

    1996-02-01

    The authors present the rotation curves of 967 spiral galaxies, obtained by deprojecting and folding the raw Hα data published by Mathewson et al. (1992). Of these, 80 meet objective excellence criteria and are suitable for individual detailed mass modelling, while 820 are suitable for statistical studies. A preliminary analysis of their properties confirms that rotation curves are a universal function of luminosity and that the dark matter fraction in spirals increases with decreasing luminosity.

  12. Discovery of a low-luminosity spiral DRAGN

    Science.gov (United States)

    Mulcahy, D. D.; Mao, M. Y.; Mitsuishi, I.; Scaife, A. M. M.; Clarke, A. O.; Babazaki, Y.; Kobayashi, H.; Suganuma, R.; Matsumoto, H.; Tawara, Y.

    2016-11-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only 5 cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M⊙ yr-1, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of L1.4 GHz = 1.12 × 1022 W Hz-1, two orders of magnitude smaller than other known spiral DRAGNs. We suggest that this may indicate the existence of a previously unknown low-luminosity population of spiral DRAGNS. FITS cutout image of the observed spiral DRAGN MCG+07-47- 10 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/L8

  13. Spiral and Antispiral Waves in Reaction-Diffusion Systems

    Institute of Scientific and Technical Information of China (English)

    LIUYu-Fang; WUYan-Ning; XUHou-Ju; SUNJin-Feng

    2004-01-01

    Spiral waves are ubiquitous phenomena in nonlinear chemical, physical, and biological systems. But antispiral waves are infrequent to date. The transition between spiral and antispiral waves has been rarely explored. We have analyzed the extended Brusselator model and the extended Oregonator model by linear stability analysis. We have demonstrated that it is possible and plausible to realize the transition between them by control of diffusion coefficient of inactivator from theoretical analysis and numerical simulations.

  14. Anomalous drift of spiral waves in heterogeneous excitable media

    CERN Document Server

    Sridhar, S; Panfilov, Alexander V

    2009-01-01

    We study the drift of spiral waves in a simple model of heterogeneous excitable medium, having gradients in local excitability or cellular coupling. For the first time, we report the anomalous drift of spiral waves towards regions having higher excitability, in contrast to all earlier observations in reaction-diffusion models of excitable media. Such anomalous drift can promote the onset of complex spatio-temporal patterns, e.g., those responsible for life-threatening arrhythmias in the heart.

  15. Period tripling causes rotating spirals in agitated wet granular layers.

    Science.gov (United States)

    Huang, Kai; Rehberg, Ingo

    2011-07-08

    Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Rotating spirals with three arms, which correspond to the kinks between regions with different colliding phases, are the dominating pattern. This preferred number of arms corresponds to period tripling of the agitated granular layer, unlike predominantly subharmonic Faraday crispations in dry granular matter. The chirality of the spatiotemporal pattern corresponds to the rotation direction of the spirals.

  16. Mechanism of unpinning spirals by a series of stimuli.

    Science.gov (United States)

    Gao, Xiang; Zhang, Hong

    2014-06-01

    Antitachycardia pacing (ATP) is widely used to terminate tachycardia before it proceeds to lethal fibrillation. The important prerequisite for successful ATP is unpinning of the spirals anchored to the obstacle by a series of stimuli. Here, to understand the mechanism of unpinning spirals by ATP, we propose a theoretical explanation based on a nonlinear eikonal relation and a kinematical model. The theoretical results are quantitatively consistent with the numerical simulations in both weak and high excitabilities.

  17. Golden spirals as phyllotactic arrangements of optical patterns.

    Science.gov (United States)

    Haudin, F; Residori, S

    2013-02-01

    A nonlinear optical medium with nonlocal feedback is shown to have all the necessary ingredients to simulate a growthlike process that generates golden spirals and phyllotactic patterns. Elementary droplets of light are generated by the optical nonlinearity whereas the combination of rotation and translation in the feedback loop geometrically distributes them on spiraling patterns. The symmetry of the geometrical arrangements is described with the help of a simple replication algorithm.

  18. A Novel Class of Reconfigurable Spherical Fermat Spiral Multi-port Antennas

    Science.gov (United States)

    Caratelli, D.; Yarovoy, A.; Haider, N.

    Reconfigurability in antenna systems is a desired characteristic that has attracted attention in the past years. In this work, a novel class of spherical Fermat spiral multi-port antennas for next-generation wireless communications and radar applications is presented. The device modelling is carried out by using a computationally enhanced locally conformal finite-difference time-domain full-wave procedure. In this way, the circuital characteristics and radiation properties of the antennas are investigated accurately. The structure reconfigurability, in terms of frequency of operation and radiation efficiency, is technically performed by a suitable solid-state tuning circuitry adopted to properly change the feeding/loading conditions at the input ports of the antenna.

  19. Magnetic field evolution and reversals in spiral galaxies

    Science.gov (United States)

    Dobbs, C. L.; Price, D. J.; Pettitt, A. R.; Bate, M. R.; Tricco, T. S.

    2016-10-01

    We study the evolution of galactic magnetic fields using 3D smoothed particle magnetohydrodynamics (SPMHD) simulations of galaxies with an imposed spiral potential. We consider the appearance of reversals of the field, and amplification of the field. We find that magnetic field reversals occur when the velocity jump across the spiral shock is above ≈20 km s-1, occurring where the velocity change is highest, typically at the inner Lindblad resonance in our models. Reversals also occur at corotation, where the direction of the velocity field reverses in the corotating frame of a spiral arm. They occur earlier with a stronger amplitude spiral potential, and later or not at all with weaker or no spiral arms. The presence of a reversal at radii of around 4-6 kpc in our fiducial model is consistent with a reversal identified in the Milky Way, though we caution that alternative Galaxy models could give a similar reversal. We find that relatively high resolution, a few million particles in SPMHD, is required to produce consistent behaviour of the magnetic field. Amplification of the magnetic field occurs in the models, and while some may be genuinely attributable to differential rotation or spiral arms, some may be a numerical artefact. We check our results using ATHENA, finding reversals but less amplification of the field, suggesting that some of the amplification of the field with SPMHD is numerical.

  20. An investigation into the prominence of spiral galaxy bulges

    CERN Document Server

    Graham, A W

    2001-01-01

    From a diameter-limited sample of 86 `face-on' spiral galaxies, the bulge-to-disk size and luminosity ratios, and other quantitative measurements for the prominence of the bulge are derived. The bulge and disk parameters have been estimated using a seeing convolved Sersic r^(1/n) bulge and a seeing convolved exponential disk. In general, early-type spiral galaxy bulges have Sersic values of n>1, and late-type spiral galaxy bulges have values of n 3-sigma) for the early-type spirals than the late-type spirals. This apparent contradiction with the r_e/h values can be explained with an iceberg-like scenario, in which the bulges in late-type spiral galaxies are relatively submerged in their disk. This can be achieved by varying the relative bulge/disk stellar density while maintaining the same effective bulge-to-disk size ratio. The absolute bulge magnitude - log(n) diagram is used as a diagnostic tool for comparative studies with dwarf elliptical and ordinary elliptical galaxies. At least in the B-band, these ob...

  1. Galaxy Zoo: star formation versus spiral arm number

    Science.gov (United States)

    Hart, Ross E.; Bamford, Steven P.; Casteels, Kevin R. V.; Kruk, Sandor J.; Lintott, Chris J.; Masters, Karen L.

    2017-06-01

    Spiral arms are common features in low-redshift disc galaxies, and are prominent sites of star formation and dust obscuration. However, spiral structure can take many forms: from galaxies displaying two strong 'grand design' arms to those with many 'flocculent' arms. We investigate how these different arm types are related to a galaxy's star formation and gas properties by making use of visual spiral arm number measurements from Galaxy Zoo 2. We combine ultraviolet and mid-infrared (MIR) photometry from GALEX and WISE to measure the rates and relative fractions of obscured and unobscured star formation in a sample of low-redshift SDSS spirals. Total star formation rate has little dependence on spiral arm multiplicity, but two-armed spirals convert their gas to stars more efficiently. We find significant differences in the fraction of obscured star formation: an additional ˜10 per cent of star formation in two-armed galaxies is identified via MIR dust emission, compared to that in many-armed galaxies. The latter are also significantly offset below the IRX-β relation for low-redshift star-forming galaxies. We present several explanations for these differences versus arm number: variations in the spatial distribution, sizes or clearing time-scales of star-forming regions (i.e. molecular clouds), or contrasting recent star formation histories.

  2. IC3328 a "dwarf elliptical galaxy" with spiral structure

    CERN Document Server

    Jerjen, H; Binggeli, B; Jerjen, Helmut; Kalnajs, Agris; Binggeli, Bruno

    2000-01-01

    We present the 2-D photometric decomposition of the Virgo galaxy IC3328. The analysis of the global light distribution of this morphologically classified nucleated dwarf elliptical galaxy (dE1,N) reveals a tightly wound, bi-symmetric spiral structure with a diameter of 4.5 kpc, precisely centered on the nucleus of the dwarf. The amplitude of the spiral is only three percent of the dwarf's surface brightness making it the faintest and smallest spiral ever found in a galaxy. In terms of pitch angle and arm winding the spiral is similar to the intermediate-type galaxy M51, but it lacks the dust and prominent HII regions which signal the presence of gas. The visual evidence of a spiral pattern in an early-type dwarf galaxy reopens the question on whether these dwarfs are genuine rotationally supported or anisotropic stellar systems. In the case of IC3328, we argue for a nearly face-on disk (dS0) galaxy with an estimated maximum rotation velocity of v_c,max = 55kms-1. The faintness of the spiral and the small moti...

  3. Spiral structure in nearby galaxies II. comparative analysis and conclusions

    CERN Document Server

    Kendall, S; Kennicutt, R C

    2014-01-01

    This paper presents a detailed analysis of two-armed spiral structure in a sample of galax- ies from the Spitzer Infrared Nearby Galaxies Survey (SINGS), with particular focus on the relationships between the properties of the spiral pattern in the stellar disc and the global struc- ture and environment of the parent galaxies. Following Paper I we have used a combination of Spitzer Space Telescope mid-infrared imaging and visible multi-colour imaging to isolate the spiral pattern in the underlying stellar discs, and we examine the systematic behaviours of the observed amplitudes and shapes (pitch angles) of these spirals. In general, spiral morphology is found to correlate only weakly at best with morphological parameters such as stellar mass, gas fraction, disc/bulge ratio, and vflat. In contrast to weak correlations with galaxy structure a strong link is found between the strength of the spiral arms and tidal forcing from nearby companion galaxies. This appears to support the longstanding suggestion that ei...

  4. Error of Archimedes spiral when applied in linearity compensation

    Science.gov (United States)

    Liu, Ke; Chen, Xiuzheng; Song, Jincheng; Liang, Yajun

    2013-01-01

    The polar coordinates equation of Archimedes spiral is ρ = ρ0 + aθ , also known as uniform speed spiral. In a polar coordinate system, the polar radius ρ has linear relation with polar angle θ . This character could be used for linearity compensation in mechanical engineering, or metrical instrument. For example, it could be used for moment linearity compensation, the common configuration has a pivot axis on the pole, and a thin line wrap around the spiral on the turntable. The gravitation of a suspension used as constant pull, and the level polar radius as force arm, then it generates a liner moment when the Archimedes spiral rotating at uniform speed. But as the polar angle of tangent point on the plumb line changes at any moment, the polar radius on level direction isn't linear with polar angle anymore, and the small error influences the effect of linearity compensation configuration. This paper presented the application of Archimedes spiral in linearity compensation, analyzed the theory error, and deduced the error equation by Mathematic theory. Using computer emulator, educed the precise errors of some dispersed points in common use, and provided according error tabulation. In engineering applications, engineers could consult this error tabulation and correct the points on Archimedes spiral, to realize accurately linearity compensation.

  5. Feeding Your Baby

    Medline Plus

    Full Text Available ... Baby Feeding your baby Other Baby topics ') document.write(' Caring for your baby ') document.write('') } ') document.write(' Feeding your baby ') document.write('') } ') document. ...

  6. Feeding tube - infants

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007235.htm Feeding tube - infants To use the sharing features on this page, please enable JavaScript. A feeding tube is a small, soft, plastic tube placed ...

  7. Jejunostomy feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000181.htm Jejunostomy feeding tube To use the sharing features on this ... vomiting Your child's stomach is bloated Alternate Names Feeding - jejunostomy tube; G-J tube; J-tube; Jejunum ...

  8. Nasogastric feeding tube

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000182.htm Nasogastric feeding tube To use the sharing features on this ... the nose. It can be used for all feedings or for giving a person extra calories. It ...

  9. Feeding Your Newborn

    Science.gov (United States)

    ... for your child. These guidelines on breastfeeding and bottle feeding can help you make the decision that's right ... formula is a nutritious alternative to breast milk. Bottle feeding can offer more freedom and flexibility for moms, ...

  10. Analytical modeling of orthogonal spiral structures

    Science.gov (United States)

    Santos, Auteliano A.; Hobeck, Jared D.; Inman, Daniel J.

    2016-11-01

    This paper presents the analytical modeling of orthogonal spiral structures (OSS), a promising option for small-scale energy harvesting applications. This unique multi-beam structure is analyzed using a distributed parameter approach with Euler-Bernoulli assumptions. First, an aluminum substrate is evaluated to determine if the proposed design can be used to capture vibration energy in the desired frequency range using a twelve beam OSS. Finite element calculations are used to validate the analytical model. This model is then modified to include the electromechanical effects of a piezoelectric layer added to the aluminum substrate. Lastly, the effects of the beam width and the number of beams is analyzed for a particular surface area of the OSS. Results show that increasing the number of beams causes a reduction in the first natural frequency. From those results, it is possible to conclude that OSS can be used as an alternative to current energy harvesting systems for MEMS applications, allowing the capture of environmental energy in the frequency range of common mechanical systems.

  11. BVRI Surface Photometry of Isolated Spiral Galaxies

    CERN Document Server

    Hernandez-Toledo, H; Avila-Reese, V

    2007-01-01

    A release of multicolor broad band (BVRI) photometry for a subsample of 44 isolated spirals drawn from the Catalogue of Isolated Galaxies (CIG) is presented. Total magnitudes and colors at various circular apertures, as well as some global structural/morphological parameters are estimated. Morphology is reevaluated through optical and sharp/filtered R band images, (B-I) color index maps, and archive near-IR JHK images from the Two-Micron Survey. The CAS structural parameters (Concentration, Asymmetry, and Clumpiness) were calculated from the images in each one of the bands. The fraction of galaxies with well identified optical/near-IR bars (SB) is 63%, while a 17% more shows evidence of weak or suspected bars (SAB). The sample average value of the maximum bar ellipticity is 0.4. Half of the galaxies in the sample shows rings. We identify two candidates for isolated galaxies with disturbed morphology. The structural CAS parameters change with the observed band, and the tendencies they follow with the morpholog...

  12. Spiralizations and tropisms in Arabidopsis roots.

    Science.gov (United States)

    Migliaccio, F; Piconese, S

    2001-12-01

    When Arabidopsis seedlings are grown on a hard-agar plate, their primary roots show characteristic spiralling movements, apparent as waves, coils and torsions, together with a slanting toward the right-hand side. All these movements are believed to be the result of three different processes acting on the roots: circumnutation, positive gravitropism and negative thigmotropism. The basic movement of the roots is described as that of a growing right-handed helix, which, because of the root tip hitting the agar plate, is continuously switched from the right-hand to the left-hand of the growth direction, and vice versa. This movement also produces a slanting root-growth direction toward the right-hand because of the incomplete waves made by the right-handed root to the left-hand. By contrast, the torsions seen in the coils and waves are interpreted as artefacts that form as an adaptation of the three-dimensional root helix to the flat two-dimensional agar surface.

  13. Lopsided spiral galaxies: evidence for gas accretion

    CERN Document Server

    Bournaud, F; Jog, C J; Puerari, I

    2005-01-01

    We quantify the degree of lopsidedness for a sample of 149 galaxies observed in the near-infrared from the OSUBGS sample, and try to explain the physical origin for the observed disk lopsidedness. We confirm previous studies, but now for a larger sample, that a large fraction of galaxies show significant lopsidedness in their stellar disks, measured as the Fourier amplitude of the m=1 component, normalised to the average or m=0 component, in the surface density. Late-type galaxies are found to be more lopsided, while the presence of m=2 spiral arms and bars is correlated. The m=1 amplitude is found to be uncorrelated with the tidal forces acting on a galaxy via nearby companions. Numerical simulations are carried out to study the generation of m=1 via different processes: galaxy tidal encounters, galaxy mergers, and external gas accretion and subsequent star formation. The simulations show that galaxy interactions and mergers can trigger strong lopsidedness, but do not explain several independent statistical ...

  14. Patterning of Spiral Structure on Optical Fiber by Focused-Ion-Beam Etching

    Science.gov (United States)

    Mekaru, Harutaka; Yano, Takayuki

    2012-06-01

    We produce patterns on minute and curved surfaces of optical fibers, and develop a processing technology for fabricating sensors, antennas, electrical circuits, and other devices on such patterned surfaces by metallization. A three-dimensional processing technology can be used to fabricate a spiral coil on the surface of cylindrical quartz materials, and then the microcoils can also be applied to capillaries of micro-fluid devices, as well as to receiver coils connected to a catheter and an endoscope of nuclear magnetic resonance imaging (MRI) systems used in imaging blood vessels. To create a spiral line pattern with a small linewidth on a full-circumference surface of an optical fiber, focused-ion-beam (FIB) etching was employed. Here, a simple rotation stage comprising a dc motor and an LR3 battery was built. However, during the development of a prototype rotation stage before finalizing a large-scale remodelling of our FIB etching system, a technical problem was encountered where a spiral line could not be processed without running into breaks and notches in the features. It turned out that the problem was caused by axis blur resulting from an eccentric spinning (or wobbling) of the axis of the fiber caused by its unrestrained free end. The problem was solved by installing a rotation guide and an axis suppression device onto the rotation stage. Using this improved rotation stage. we succeeded in the seamless patterning of 1-µm-wide features on the full-circumference surface of a 250-µm-diameter quartz optical fiber (QOF) by FIB etching.

  15. Stellar Orbital Studies in Normal Spiral Galaxies II: Restrictions to Structural and Dynamical parameters on Spiral Arms

    CERN Document Server

    Pérez-Villegas, Angeles; Moreno, Edmundo

    2015-01-01

    Making use of a set of detailed potential models for normal spiral galaxies, we analyze the disk stellar orbital dynamics as the structural and dynamical parameters of the spiral arms (mass, pattern speed and pitch angle) are gradually modified. With this comprehensive study of ordered and chaotic behavior, we constructed an assemblage of orbitally supported galactic models and plausible parameters for orbitally self-consistent spiral arms models. We find that, to maintain orbital support for the spiral arms, the spiral arm mass, M$_{sp}$, must decrease with the increase of the pitch angle, $i$; if $i$ is smaller than $\\sim10\\deg$, M$_{sp}$ can be as large as $\\sim7\\%$, $\\sim6\\%$, $\\sim5\\%$ of the disk mass, for Sa, Sb, and Sc galaxies, respectively. If $i$ increases up to $\\sim25\\deg$, the maximum M$_{sp}$ is $\\sim1\\%$ of the disk mass independently in this case of morphological type. For values larger than these limits, spiral arms would likely act as transient features. Regarding the limits posed by extrem...

  16. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    Science.gov (United States)

    Egusa, Fumi; Mentuch Cooper, Erin; Koda, Jin; Baba, Junichi

    2017-02-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near-infrared images, while the gas mass distribution is obtained by high-resolution CO and H I data. For the inner region (r ≤ 150 arcsec), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower range of offset values, the weakness of stellar arms, and the smaller number of successful offset measurements. The results suggest that the nature of two inner spiral arms is different, which is likely due to an interaction with the companion galaxy.

  17. Staging of colorectal carcinoma by spiral CT with water enema : correlation with pathologic staging using new AJCC classification

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Jung; Lee, Dong Ho; Ko, Young Tae [Kyunghee Univ. Hospital, Seoul (Korea, Republic of)

    1999-05-01

    In cases of colorectal cancer, to correlate the spiral CT staging with water enema with the pathologic staging according to the new AJCC classification. Ninety four patients with pathologically proven carcinoma of the colon who had undergone spiral CT with water enema were evaluated. CT scans were obtained after enema involving about 600-1,200mL of water. Scanning was performed from the diaphragmatic dome to the symphysis pubis using 10mm collimation thickness, 12mm table feed, and 10mm reconstruction interval. The TNM stage, as seen on spiral CT, was determined without reference to the pathologic results. Staging was performed according to the new AJCC cancer staging manual(1997). The pathologic T-stage was T1 in four cases(4.3%), T2 in 11(11.7%), T3 in 72(76.6%), and T4 in seven(7.4%). The pathologic N-stage was N0 in 57 cases(60.6%), N1 in 25 cases(26.6%), and N2 in 12(12.8%). The pathologic M-stage was M0 in 90 cases(95.7%) and M1 in four(4.3%). The detection rate of colon cancer using spiral CT with water enema was 97.9%. At the T-stage, pathologic correlation was good in 68.1% of cases(64/94). Nine patients(9.6%) were overstaged and 21(22.3%) were understaged. At the N-stage, pathologic correlation was good in 54.3% of cases(51/94), with 27 patients(28.7%) overstaged and sixteen(17.0%) understaged. At the M-stage, pathologic correlation was good in 95.7% of cases(90/94). Four patients(4.3%) were overstaged. The accuracy of staging of colorectal carcinoma by spiral hydro-CT was 68.1% at the T-stage, 54.3% at the N-stage, and 95.7% at the M-stage. As seen on spiral CT with water enema, the T-stage tended to wards understaging and the N-stage towards overstaging.

  18. Nuclear safeguards; Salvaguardias nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Zurron, O.

    2015-07-01

    Safeguards control at the Juzbado Plant is implemented through the joint IAEA/EURATOM partnership approach in force within the European Union for all nuclear facilities. this verification agreement is designed to minimize burden on the operators whilst ensuring that both inspectorate achieve the objectives related to their respective safeguards regimes. This paper outlines the safeguards approaches followed by the inspectorate and the particularities of the Juzbado Plants nuclear material accountancy and control system. (Authors)

  19. Spiral structures and regularities in magnetic field variations and auroras

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    2012-02-01

    Full Text Available The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras.

    We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals.

    We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines currents (FACs a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral, and later in the nighttime-evening (N-spiral and morning (M-spiral sectors both in

  20. Breast-Feeding Twins: Making Feedings Manageable

    Science.gov (United States)

    ... more than one baby? Here's help breast-feeding twins or other multiples, from getting positioned and ensuring ... babies who are born prematurely, as are many twins and higher order multiples. Breast milk is easier ...

  1. Feed safety in the feed supply chain

    Directory of Open Access Journals (Sweden)

    Pinotti, L.

    2011-01-01

    Full Text Available A number of issues have weakened the public's confidence in the quality and wholesomeness of foods of animal origin. As a result farmers, nutritionists, industry and governments have been forced to pay serious attention to animal feedstuff production processes, thereby acknowledging that animal feed safety is an essential prerequisite for human food safety. Concerns about these issues have produced a number of important effects including the ban on the use of processed animal proteins, the ban on the addition of most antimicrobials to farm animals diets for growth‐promotion purposes, and the implementation of feed contaminant regulations in the EU. In this context it is essential to integrate knowledge on feed safety and feed supply. Consequently, purchase of new and more economic sources of energy and protein in animal diets, which is expected to conform to adequate quality, traceability, environmental sustainability and safety standards, is an emerging issue in livestock production system.

  2. Spiral Wave Generation in a Vortex Electric Field

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiao-Ping; CHEN Jiang-Xing; ZHAO Ye-Hua; LOU Qin; WANG Lu-Lu; SIIEN Qian

    2011-01-01

    The effect of a vortical electric field on nonlinear patterns in excitable media is studied. When an appropriate vortex electric field is applied, the system exhibits pattern transition from chemical turbulence to spiral waves, which possess the same chtality as the vortex electric field. The underlying mechanism of this is discussed. We also show the meandering behavior of a spiral under the taming of a vortex electric field. The results obtained here may contribute to control strategies of patterns on surface reaction.%The effect of a vortical electric field on nonlinear patterns in excitable media is studied.When an appropriate vortex electric field is applied,the system exhibits pattern transition from chemical turbulence to spiral waves,which possess the same chirality as the vortex electric field.The underlying mechanism of this is discussed.We also show the meandering behavior of a spiral under the taming of a vortex electric field.The results obtained here may contribute to control strategies of patterns on surface reaction.Spiral waves are one of the most common and widely studied patterns in nature.They appear in hydrodynamic systems,chemical reactions and a large variety of biological,chemical and physical systems.[1-5] Much attention has been paid to their rich nonlinear dynamics,as well as potential applications in various biological or physiological systems,since the emergence and instability of spirals usually lead to abnormal states,for example in cardiac arrythmia[6,7] and epilepsy[8].Much research has been carried out in studying pattern formations in catalytic CO oxidation on Pt(110),[9-11] because they provide practical utilization in industry.A rich variety of spatiotemporal patterns,including travelling pulses,standing waves,target patterns,spiral waves and chemical turbulence have been observed in this system.[12-16

  3. Unstable Dynamical Properties of Spiral Cloud Bands in Tropical Cyclones

    Institute of Scientific and Technical Information of China (English)

    HUANG Hong; ZHANG Ming

    2009-01-01

    A nondivergent barotropic model (Model 1) and a barotropic primitive equation vortex model (Model 2) are linearized respectively in this paper. Then their perturbation wave spectrums are computed with a normal mode approach to study the instability problem on an appointed tropical cyclone (TC)-like vortex, thereby, the dynamic instability properties of spiral cloud bands of TCs are discussed. The results show that the unstable mode of both models exhibits a spiral band-like structure that propagates away from the vortex outside the radius of maximum winds. The discrete modal instability of the pure vortex Rossby wave can account for the generation of the eyewall and the inner spiral band. The unstable mode in Model 2 has three parts, i.e., eyewall, inner and outer spiral bands. This mode can be interpreted as a mixed vortex Rossby-inertia gravitational wave. The unbalanced property of the wave outside the stagnation radius of the vortex Rossby wave is one of the important reasons for the formation of the outer spiral band in TCs. Accordingly, the outer spiral band can be identified to possess properties of an inertial-gravitational wave.When the formation of unstable inner and outer spiral bands is studied, a barotropic vortex model shall be used. In this model, the most unstable perturbation bears the attributes of either the vortex Rossby wave or the inertial-gravitational wave, depending on the vortex radius. So such perturbations shall be viewed as an unbalanced and unstable mixed wave of these two kinds of waves.

  4. Spiral-like star-forming patterns in CALIFA early-type galaxies

    CERN Document Server

    Gomes, J M; Vílchez, J M; Kehrig, C; Iglesias-Páramo, J; Breda, I; Lehnert, M D; Sánchez, S F; Ziegler, B; Reis, S N dos; Bland-Hawthorn, J; Galbany, L; Bomans, D J; Rosales-Ortega, F F; Walcher, C J; García-Benito, R; Márquez, I; del Olmo, A; Mollá, M; Marino, R A; Catalán-Torrecilla, C; Delgado, R M González; López-Sánchez, Á R

    2015-01-01

    Based on a combined analysis of SDSS imaging and CALIFA integral field spectroscopy data, we report on the detection of faint (24 < {\\mu}$_r$ mag/arcsec$^2$ < 26) star-forming spiral-arm-like features in the periphery of three nearby early-type galaxies (ETGs). These features are of considerable interest because they document the still ongoing inside-out growth of some local ETGs and may add valuable observational insight into the origin and evolution of spiral structure in triaxial stellar systems. A characteristic property of the nebular component in the studied ETGs, classified i+, is a two-radial-zone structure, with the inner zone that displays faint (EW(H\\alpha)$\\simeq$1{\\AA}) low-ionization nuclear emission-line region (LINER) properties, and the outer one (3{\\AA}

  5. The One-Armed Spiral Instability in Neutron Star Mergers and its Detectability in Gravitational Waves

    CERN Document Server

    Radice, David; Ott, Christian D

    2016-01-01

    We study the development and saturation of the $m=1$ one-armed spiral instability in remnants of binary neutron star mergers by means of high-resolution long-term numerical relativity simulations. Our results suggest that this instability is a generic outcome of neutron stars mergers in astrophysically relevant configurations; including both "stiff" and "soft" nuclear equations of state. We find that, once seeded at merger, the $m=1$ mode saturates within $\\sim 10\\ \\mathrm{ms}$ and persists over secular timescales. Gravitational waves emitted by the $m=1$ instability have a peak frequency around $1-2\\ \\mathrm{kHz}$ and, if detected, could be used to constrain the equation of state of neutron stars. We construct hybrid waveforms spanning the entire Advanced LIGO band by combining our high-resolution numerical data with state-of-the-art effective-one-body waveforms including tidal effects. We use the complete hybrid waveforms to study the detectability of the one-armed spiral instability for both Advanced LIGO ...

  6. Nuclear physics

    Energy Technology Data Exchange (ETDEWEB)

    Sang, David (Bishop Luffa Comprehensive School, Chichester (UK))

    1990-01-01

    Nuclear Physics covers the aspects of radioactivity and nuclear physics dealt with in the syllabuses of all the A-level examination boards; in particular, it provides detailed coverage of the Joint Matriculation Board option in nuclear physics. It deals with the discovery of the atomic nucleus, the physics of nuclear processes, and nuclear technology. (author).

  7. Negative spiral CT in acute pulmonary embolism

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, T.; Olausson, A. [Karolinska Hospital, Stockholm (Sweden). Dept. of Thoracic Radiology; Johnsson, H. [Karolinska Hospital, Stockholm (Sweden). Dept. of Internal Medicine; Nyman, U. [County Hospital, Trelleborg (Sweden). Dept. of Radiology; Aspelin, P. [Huddinge Univ. Hospital (Sweden). Dept. of Radiology

    2002-09-01

    Purpose: To retrospectively evaluate the clinical outcome of non-anticoagulated patients with clinically suspected acute pulmonary embolism (PE) and no symptoms or signs of deep venous thrombosis (DVT) following a negative contrast medium-enhanced spiral CT of the pulmonary arteries (s-CTPA). Material and Methods: During a 24-month period, 739 of 751 patients underwent s-CTPA with acceptable diagnostic quality for clinically suspected acute PE. All patients who had a CT study not positive for PE were followed up with a questionnaire, a telephone interview and review of all medical reports, including autopsies and death certificates for any episodes of venous thromboembolism (VTE) during a 3-month period. Results: PE was diagnosed in 158 patients. Of the remaining 581 patients with a negative s-CTPA, 45 patients were lost to follow-up. 88 patients were excluded because of anticoagulation treatment (cardiac disorder n=32, chronic VTE or acute symptomatic DVT n=31, PE diagnosed at pulmonary angiography n=1, thrombus prophylaxis during diagnostic work-up or other reasons than VTE n=24) and 7 patients undergoing lower extremity venous studies because of symptoms of DVT (all negative). Thus, 441 patients with a negative s-CTPA and no DVT symptoms, venous studies or anticoagulant treatment constituted the follow-up cohort. Four of these patients had proven VTE (all PE) during the 3-month follow-up period. Two of the PE episodes contributed to the patient's death. Conclusion: Patients with clinically suspected acute PE, no symptoms or signs of DVT and a negative single slice s-CTPA using 3-5 mm collimation, may safely be left without anticoagulation treatment unless they are critically ill, have a limited cardiopulmonary reserve and/or if a high clinical suspicion remains.

  8. Separating xylose from glucose using spiral wound nanofiltration membrane: Effect of cross-flow parameters on sugar rejection

    Science.gov (United States)

    Roli, N. F. M.; Yussof, H. W.; Seman, M. N. A.; Saufi, S. M.; Mohammad, A. W.

    2016-11-01

    A solution model consisted of two different monosaccharides namely xylose and glucose were separated using a pilot scale spiral wound cross-flow system. This system was equipped by a commercial spiral wound nanofiltration (NF) membrane, Desal-5 DK, having a molecular weight cut off (MWCO) of 150-300 g mol-1. The aim of this present work is to investigate the effect of the cross-flow parameters: the trans-membrane pressure (TMP) and the feed concentration (C0) on the xylose separation from glucose. The filtration experiments were carried out in total reflux mode with different feed concentration of 2, 5, and 10 g/L at different TMP of 5,8 and 10 bar. The performances of the NF membrane were evaluated by measuring the permeate flux and sugar rejection for each experiment. All the samples were quantified using a high performance liquid chromatography equipped by a fractive index detector. The experimental results indicated an increase in pressure from 5 to 10 bar which was a notable increase to the permeate fluxes from 2.66 × 10-3 to 4.14 × 10-3L m-2s-1. Meanwhile, an increase in the C0 increases the xylose rejection. At TMP of 10 bar and C0 of 5 g/L, the observed xylose rejection and glucose rejection were measured at 67.19% and 91.82%, respectively. The lower rejection in xylose than glucose suggested that larger glucose molecule were not able to easily pass through the membrane compared to the smaller xylose molecule. The results of this phenomena proved that NF with spiral wound configuration has the potential to separate xylose from glucose, which is valuable to the purification of xylose in xylose production as an alternative to chromatographic processes.

  9. Stabilization of spiral wave and turbulence in the excitable media using parameter perturbation scheme

    Institute of Scientific and Technical Information of China (English)

    Ma Jun; Wang Chun-Ni; Jin Wu-Yin; Li Yan-Long; Pu Zhong-Sheng

    2008-01-01

    This paper proposes a scheme of parameter perturbation to suppress the stable rotating spiral wave, meandering spiral wave and turbulence in the excitable media, which is described by the modified Fitzhugh-Nagumo (MFHN) model. The controllable parameter in the MFHN model is perturbed with a weak pulse and the pulse period is decided by the rotating period of the spiral wave approximatively. It is confirmed that the spiral wave and spiral turbulence can be suppressed greatly. Drift and instability of spiral wave can be observed in the numerical simulation tests before the whole media become homogeneous finally.

  10. Nuclear ventriculography

    Science.gov (United States)

    ... ventriculography (RNV); Multiple gate acquisition scan (MUGA); Nuclear cardiology; Cardiomyopathy - nuclear ventriculography ... 56. Udelson JE, Dilsizian V, Bonow RO. Nuclear cardiology. In: Bonow RO, Mann DL, Zipes DP, Libby ...

  11. Nuclear Medicine.

    Science.gov (United States)

    Badawi, Ramsey D.

    2001-01-01

    Describes the use of nuclear medicine techniques in diagnosis and therapy. Describes instrumentation in diagnostic nuclear medicine and predicts future trends in nuclear medicine imaging technology. (Author/MM)

  12. Ram-Pressure Stripping of Gas from Companions and Accretion onto a Spiral Galaxy A Gaseous Merger

    CERN Document Server

    Sofue, Y

    1993-01-01

    We simulated the behavior of interstellar gas clouds in a companion galaxy during a gas-dynamical interaction with the halo and disk of a spiral galaxy. By ram pressure, the gas clouds are stripped from the companion, and accreted to ward the disk of the spiral galaxy. If the companion's orbit is retrograde with respect to the rotation of the spiral galaxy, infalling clouds hit the nuclear region. Angular momentum transfer causes disruption of the inner gaseous disk, and makes a void of interstellar gas in the bulge. If the companion's orbit is either prograde or polar, infalling clouds are accreted by the outer disk, and form a rotating gas ring. We show that the ram-pressure stripping-and-accretion is one way from the companion to a gas-rich larger galaxy, which causes disposal of interstellar gas from the companion and effectively changes its galaxy type into earlier (redder). The ram-pressure process is significant durig merger of galaxies, in which interstellar gas is stripped and accreted prior to the s...

  13. Vibration damping using a spiral acoustic black hole.

    Science.gov (United States)

    Lee, Jae Yeon; Jeon, Wonju

    2017-03-01

    This study starts with a simple question: can the vibration of plates or beams be efficiently reduced using a lightweight structure that occupies a small space? As an efficient technique to damp vibration, the concept of an acoustic black hole (ABH) is adopted with a simple modification of the geometry. The original shape of an ABH is a straight wedge-type profile with power-law thickness, with the reduction of vibration in beams or plates increasing as the length of the ABH increases. However, in real-world applications, there exists an upper bound of the length of an ABH due to space limitations. Therefore, in this study, the authors propose a curvilinear shaped ABH using the simple mathematical geometry of an Archimedean spiral, which allows a uniform gap distance between adjacent baselines of the spiral. In numerical simulations, the damping performance increases as the arc length of the Archimedean spiral increases, regardless of the curvature of the spiral in the mid- and high-frequency ranges. Adding damping material to an ABH can also strongly enhance the damping performance while not significantly increasing the weight. In addition, the radiated sound power of a spiral ABH is similar to that of a standard ABH.

  14. The Onset of Spiral Structure in the Universe

    CERN Document Server

    Elmegreen, Debra Meloy

    2013-01-01

    The onset of spiral structure in galaxies appears to occur between redshifts 1.4 and 1.8 when disks have developed a cool stellar component, rotation dominates over turbulent motions in the gas, and massive clumps become less frequent. During the transition from clumpy to spiral disks, two unusual types of spirals are found in the Hubble Ultra Deep Field that are massive, clumpy and irregular like their predecessor clumpy disks, yet spiral-like or sheared like their descendants. One type is ``woolly'' with massive clumpy arms all over the disk and is brighter than other disk galaxies at the same redshift, while another type has irregular multiple arms with high pitch angles, star formation knots and no inner symmetry like today's multiple-arm galaxies. The common types of spirals seen locally are also present in a redshift range around z~1, namely grand design with two symmetric arms, multiple arm with symmetry in the inner parts and several long, thin arms in the outer parts, and flocculent, with short, irre...

  15. The local spiral structure of the Milky Way.

    Science.gov (United States)

    Xu, Ye; Reid, Mark; Dame, Thomas; Menten, Karl; Sakai, Nobuyuki; Li, Jingjing; Brunthaler, Andreas; Moscadelli, Luca; Zhang, Bo; Zheng, Xingwu

    2016-09-01

    The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy's major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branches between the Local and Sagittarius spiral arms.

  16. Branch, Spur, and Feather Formation in Spiral Galaxies

    CERN Document Server

    Chakrabarti, S; Shu, F H

    2003-01-01

    We use hydrodynamical simulations to investigate the response of geometrically thin, self-gravitating, singular isothermal disks of gas to imposed rigidly rotating spiral potentials. By minimizing reflection-induced feedback from boundaries, and by restricting our attention to models where the swing parameter $X sim 10$, we minimize the swing amplification of global normal modes even in models where Toomre's $Q_g sim 1-2$ in the gas disk. We perform two classes of simulations: short-term ones over a few galactic revolutions where the background spiral forcing is large, and long-term ones over many galactic revolutions where the spiral forcing is considerably smaller. In both classes of simulations, the initial response of the gas disk is smooth and mimics the driving spiral field. At late times, many of the models evince substructure akin to the so-called branches, spurs, and feathers observed in real spiral galaxies. We comment on the parts played respectively by ultraharmonic resonances, reflection off inte...

  17. Environment Dependence of Disk Morphology of Spiral Galaxies

    CERN Document Server

    Ann, H B

    2014-01-01

    We analyze the dependence of disk morphology (arm class, Hubble type, bar type) of nearby spiral galaxies on the galaxy environment by using local background density ($\\Sigma_{n}$), projected distance ($r_{p}$), and tidal index ($TI$) as measures of the environment. There is a strong dependence of arm class and Hubble type on the galaxy environment, while the bar type exhibits a weak dependence with a high frequency of SB galaxies in high density regions. Grand design fractions and early-type fractions increase with increasing $\\Sigma_{n}$, $1/r_{p}$, and $TI$, while fractions of flocculent spirals and late-type spirals decrease. Multiple-arm and intermediate-type spirals exhibit nearly constant fractions with weak trends similar to grand design and early-type spirals. While bar types show only a marginal dependence on $\\Sigma_{n}$, they show a fairly clear dependence on $r_{p}$ with a high frequency of SB galaxies at small $r_{p}$. The arm class also exhibits a stronger correlation with $r_{p}$ than $\\Sigma_...

  18. Influence of spiral framework on nonlinear optical materials.

    Science.gov (United States)

    Hu, Yang-Yang; Sun, Shi-Ling; Tian, Wen-Tao; Tian, Wei Quan; Xu, Hong-Liang; Su, Zhong-Min

    2014-04-04

    A series of spiral donor-π-acceptor frameworks (i.e. 2-2, 3-3, 4-4, and 5-5) based on 4-nitrophenyldiphenylamine with π-conjugated linear acenes (naphthalenes, anthracenes, tetracenes, and pentacenes) serving as the electron donor and nitro (NO2 ) groups serving as the electron acceptor were designed to investigate the relationships between the nonlinear optical (NLO) responses and the spirality in the frameworks. A parameter denoted as D was defined to describe the extent of the spiral framework. The D value reached its maximum if the number of NO2 groups was equal to the number of fused benzene rings contained in the linear acene. A longer 4-nitrophenyldiphenylamine chain led to a larger D value and, further, to a larger first hyperpolarizability. Different from traditional NLO materials with charge transfer occurring in the one-dimensional direction, charge transfer in 2-2, 3-3, 4-4, and 5-5 occur in three-dimensional directions due to the attractive spiral frameworks, and this is of great importance in the design of NLO materials. The origin of such an enhancement in the NLO properties of these spiral frameworks was explained with the aid of molecular orbital analysis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Dynamics of Non-Steady Spiral Arms in Disk Galaxies

    CERN Document Server

    Baba, Junichi; Wada, Keiichi

    2012-01-01

    In order to understand the physical mechanisms underlying non-steady stellar spiral arms in disk galaxies, we analyzed the growing and damping phases of their spiral arms using three-dimensional $N$-body simulations. We confirmed that the spiral arms are formed due to a swing amplification mechanism that reinforces density enhancement as a seeded wake. In the damping phase, the Coriolis force exerted on a portion of the arm surpasses the gravitational force that acts to shrink the portion. Consequently, the stars in the portion escape from the arm, and subsequently they form a new arm at a different location. The time-dependent nature of the spiral arms are originated in the continual repetition of this non-linear phenomenon. Since a spiral arm does not rigidly rotate, but follows the galactic differential rotation, the stars in the arm rotate at almost the same rate as the arm. In other words, every single position in the arm can be regarded as the co-rotation point. Due to interaction with their host arms, ...

  20. The Discovery of a Low-Luminosity SPIRAL DRAGN

    CERN Document Server

    Mulcahy, D D; Mitsuishi, I; Scaife, A M M; Clarke, A O; Babazaki, Y; Kobayashi, H; Suganuma, R; Matsumoto, H; Tawara, Y

    2016-01-01

    Standard galaxy formation models predict that large-scale double-lobed radio sources, known as DRAGNs, will always be hosted by elliptical galaxies. In spite of this, in recent years a small number of spiral galaxies have also been found to host such sources. These so-called spiral DRAGNs are still extremely rare, with only $\\sim 5$ cases being widely accepted. Here we report on the serendipitous discovery of a new spiral DRAGN in data from the Giant Metrewave Radio Telescope (GMRT) at 322 MHz. The host galaxy, MCG+07-47-10, is a face-on late-type Sbc galaxy with distinctive spiral arms and prominent bulge suggesting a high black hole mass. Using WISE infra-red and GALEX UV data we show that this galaxy has a star formation rate of 0.16-0.75 M$_{\\odot}$yr$^{-1}$, and that the radio luminosity is dominated by star-formation. We demonstrate that this spiral DRAGN has similar environmental properties to others of this class, but has a comparatively low radio luminosity of $L_{\\rm 1.4GHz}$ = 1.12$\\times$10$^{22}$...

  1. Spirals in protoplanetary disks from photon travel time

    Science.gov (United States)

    Kama, M.; Pinilla, P.; Heays, A. N.

    2016-09-01

    Spiral structures are a common feature in scattered-light images of protoplanetary disks, and of great interest as possible tracers of the presence of planets. However, other mechanisms have been put forward to explain them, including self-gravity, disk-envelope interactions, and dead zone boundaries. These mechanisms explain many spirals very well, but are unable to easily account for very loosely wound spirals and single spiral arms. We study the effect of light travel time on the shape of a shadow cast by a clump orbiting close (within ~ 1 au) of the central star, where there can be significant orbital motion during the light travel time from the clump to the outer disk and then to the sky plane. This delay in light rays reaching the sky plane gives rise to a variety of spiral- and arc-shaped shadows, which we describe with a general fitting formula for a flared, inclined disk. The three movies are available at http://www.aanda.org

  2. Magnetic field evolution and reversals in spiral galaxies

    CERN Document Server

    Dobbs, C L; Pettitt, A R; Bate, M R; Tricco, T

    2016-01-01

    We study the evolution of galactic magnetic fields using 3D smoothed particle magnetohydrodynamics (SPMHD) simulations of galaxies with an imposed spiral potential. We consider the appearance of reversals of the field, and amplification of the field. We find magnetic field reversals occur when the velocity jump across the spiral shock is above $\\approx$20km s$^{-1}$, occurring where the velocity change is highest, typically at the inner Lindblad resonance (ILR) in our models. Reversals also occur at corotation, where the direction of the velocity field reverses in the co-rotating frame of a spiral arm. They occur earlier with a stronger amplitude spiral potential, and later or not at all with weaker or no spiral arms. The presence of a reversal at a radii of around 4--6 kpc in our fiducial model is consistent with a reversal identified in the Milky Way, though we caution that alternative Galaxy models could give a similar reversal. We find that relatively high resolution, a few million particles in SPMHD, is ...

  3. Density-Wave Spiral Theories in the 1960s. I

    CERN Document Server

    Pasha, I I

    2004-01-01

    With the arrival of computers, plasma physics and several fresh investigators by the early 1960s, understanding the spiral structure of galaxies entered a new stage of unusually vigorous activity broadly grouped under the umbrella marked "density-wave theory". Paper I starts with acknowledging B. Lindblad, rightly regarded the main father of this whole subject, and then describes the early contributions by Lynden-Bell, Toomre, Hunter and Kalnajs, who had formulated and applied such notions as the stability of flat galaxies, the regenerative spiral phenomenon, the shearing density waves and the global spiral modes. But the foremost enthusiast and proponent of the density-wave picture was undoubtedly C.C. Lin whose 1964 and 1966 papers with Shu, written in support of his working hypothesis of the quasi-stationary wave-mode spiral structure, had a big and immediate impact upon astronomers, at least as a welcome sign that genuine understanding of the spiral phenomenon seemed in some sense to be just around the co...

  4. Guiding Spin Spirals by Local Uniaxial Strain Relief.

    Science.gov (United States)

    Hsu, Pin-Jui; Finco, Aurore; Schmidt, Lorenz; Kubetzka, André; von Bergmann, Kirsten; Wiesendanger, Roland

    2016-01-08

    We report on the influence of uniaxial strain relief on the spin spiral state in the Fe double layer grown on Ir(111). Scanning tunneling microscopy (STM) measurements reveal areas with reconstruction lines resulting from uniaxial strain relief due to the lattice mismatch of Fe and Ir atoms, as well as pseudomorphic strained areas. Magnetic field-dependent spin-polarized STM measurements of the reconstructed Fe double layer reveal cycloidal spin spirals with a period on the nm scale. Globally, the spin spiral wave fronts are guided along symmetry-equivalent [112̅] crystallographic directions of the fcc(111) substrate. On an atomic scale the spin spiral propagation direction is linked to the [001] direction of the bcc(110)-like Fe, leading to a zigzag shaped wave front. The isotropically strained pseudomorphic areas also exhibit a preferred magnetic periodicity on the nm scale but no long-range order. We find that already for local strain relief with a single set of reconstruction lines a strict guiding of the spin spiral is realized.

  5. Prominent spiral arms in the gaseous outer galaxy disks

    CERN Document Server

    Bertin, G

    2009-01-01

    Context: Several spiral galaxies, as beautifully exhibited by the case of NGC 6946, display a prominent large-scale spiral structure in their gaseous outer disk. Such structure is often thought to pose a dynamical puzzle, because grand-design spiral structure is traditionally interpreted as the result of density waves carried mostly in the stellar disk. Aims. Here we argue that the outer spiral arms in the cold gas outside the bright optical disk actually have a natural interpretation as the manifestation of the mechanism that excites grand-design spiral structure in the main, star-dominated body of the disk: the excitation is driven by angular momentum transport to the outer regions, through trailing density waves outside the corotation circle that can penetrate beyond the Outer Lindblad Resonance in the gaseous component of the disk. Methods: Because of conservation of the density wave action, these outgoing waves are likely to become more prominent in the outer disk and eventually reach non-linear amplitud...

  6. Grand Design Spiral Arms in A Young Forming Circumstellar Disk

    CERN Document Server

    Tomida, Kengo; Hosokawa, Takashi; Sakurai, Yuya; Lin, Chia Hui

    2016-01-01

    We study formation and long-term evolution of a circumstellar disk in a collapsing molecular cloud core using a resistive magnetohydrodynamic simulation. While the formed circumstellar disk is initially small, it grows as accretion continues and its radius becomes as large as 200 AUs toward the end of the Class-I phase. A pair of grand-design spiral arms form due to gravitational instability in the disk, and they transfer angular momentum in the highly resistive disk. Although the spiral arms disappear in a few rotations as expected in a classical theory, new spiral arms form recurrently as the disk soon becomes unstable again by gas accretion. Such recurrent spiral arms persist throughout the Class-0 and I phase. We then perform synthetic observations and compare our model with a recent high-resolution observation of a young stellar object Elias 2-27, whose circumstellar disk has grand design spiral arms. We find an excellent agreement between our theoretical model and the observation. Our model suggests tha...

  7. Is gastric sham feeding really sham feeding?

    Science.gov (United States)

    Sclafani, A; Nissenbaum, J W

    1985-03-01

    Rats were fitted with gastric cannulas, food deprived, and allowed to drink a sugar solution that drained out of the opened cannula; i.e., the rats sham-fed. Although this procedure is thought to prevent absorption of ingested food, it was found that the sham feeding of a 32% glucose or sucrose solution significantly elevated blood glucose levels. The addition of acarbose, a drug that inhibits the digestion of sucrose, to the 32% sucrose solution blocked the blood glucose rise, as did closing the pylorus with an inflatable pyloric cuff. Neither the drug nor the cuff, however, reduced the amount of sucrose solution consumed. These findings indicate that gastric sham feeding does not necessarily prevent the digestion and absorption of food, although absorption is not essential for the appearance of a vigorous sham-feeding response. Nevertheless the possibility that neural or hormonal feedback from the stomach contributes to the sham-feeding response cannot be excluded, and until this issue is resolved the results of gastric sham-feeding studies should be interpreted with caution.

  8. Complex Feeding Decisions

    Directory of Open Access Journals (Sweden)

    Anna Miles PhD

    2016-08-01

    Full Text Available Objective: Where swallowing difficulties are chronic or progressive, or a patient is palliative, tube feeding is often not deemed appropriate. Instead, patients continue to eat and drink despite the risks of pneumonia and death. There is currently little evidence to guide clinical practice in this field often termed “risk feeding.” This qualitative study investigated staff, patient, and family member perceptions of risk feeding practices in one New Zealand hospital. Method: Twenty-nine staff members and six patients and/or their family were interviewed. Results: Thematic analysis revealed four global themes: supporting practice, communication, complexity of feeding decisions, and patient and family-centered care. Staff described limited education and organizational policy around risk feeding decisions. Communication was considered a major factor in the success. Conclusion: Feeding decisions are complex in the hospital environment. The themes identified in this study provide a foundation for hospital guideline development and implementation.

  9. Post-pyloric feeding

    Institute of Scientific and Technical Information of China (English)

    Eva Niv; Zvi Fireman; Nachum Vaisman

    2009-01-01

    Postpyloric feeding is an important and promising alternative to parenteral nutrition. The indications for this kind of feeding are increasing and include a variety of clinical conditions, such as gastroparesis, acute pancreatitis, gastric outlet stenosis, hyperemesis (including gravida), recurrent aspiration, tracheoesophageal fistula and stenosis in gastroenterostomy. This review discusses the differences between pre- and postpyloric feeding, indications and contraindications, advantages and disadvantages, and provides an overview of the techniques of placement of various postpyloric devices.

  10. A Parallax-based Distance Estimator for Spiral Arm Sources

    CERN Document Server

    Reid, M J; Menten, K M; Brunthaler, A

    2016-01-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star forming regions with the BeSSeL Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VERA project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l,b,v) coordinates with respect to arm signatures seen in CO and HI surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  11. Study and Design of Spiral Bent Waveguide Configuration

    Institute of Scientific and Technical Information of China (English)

    ZENG Wen-hong; LIAO Yun; SHI Shuang-jin; QIU Qi; LI Wei

    2007-01-01

    A new version of the scalar transverse electric(TE) wave equation in the bent waveguide is introduced.Then,TE polarized field in curved single-mode waveguides is analyzed by using the finite-difference beam propagation method(FD-BPM).The bending loss in bent waveguides is gotten for the optical fields obtained from BPM and comparisons are made among losses of the waveguides with various curvature radiuses,refractive index differences and cross sections.Based on the results,the design of spiral bent waveguide configuration is proposed as follows:refractive index difference being of 0.007,both width and thickness of waveguides being of 6 μm,the curvature radius in the spiral centre being of 4 mm,and the bending loss coefficient of the designed spiral bent waveguide being of 0.302 3 dB/cm.

  12. Generation of speckle vortices by Archimedes' spiral micro-holes

    Science.gov (United States)

    Sun, Haibin; Liu, Tingting; Chen, Jun; Sun, Ping

    2016-10-01

    Speckle plays an important role in the optical field. Optical vortices which exist in random speckle fields usually contain useful phase information. The distribution of speckle field is determined by these optical vortices. In order to study speckle vortices quantitatively, we established a micro-holes array model based on the law of Archimedes' spiral arrangement. Speckle vortices can be generated by the random diffuse reflection points (spiral micro-holes). In the experiments, the gray image of Archimedes' spiral micro-holes are displayed on the screen of liquid crystal spatial light modulator (LC-SLM), and the output optical field is captured by a CCD camera. The numerical simulations and experimental results show that the model can be used to generate speckle vortices.

  13. Asymmetric propagation of electromagnetic waves through nanoscale spirals

    Science.gov (United States)

    Hu, Jingpei; Lin, Yu; Zhu, Aijiao; Zhao, Xiaonan; Wang, Chinhua

    2016-10-01

    In this paper, we report that normal incidence transmission of different circularly polarized waves through the 2D Archimedes' nanoscale spirals is asymmetric. The structures consist of raised spiral ridge and two layers metal film covered on the substrate and the ridge. The finite difference time domain method was used to design the structure and perform the simulation. The device can distinguish the different circularly polarized wave across the transmission intensity compare with the common Archimedes' nanoscale spirals which just exhibit the bright or dark modes in the light field. We confirmed that the device provide about 10% circular dichroism in 3.85um-6.0um broadband region. The circular dichroism in the wavelength 3.95 um can reach 13%. This ultracompact device could prove useful for remote sensing and advanced telecommunication applications.

  14. The rotation curve of spiral galaxies and its cosmological implications

    CERN Document Server

    Florido, E

    2000-01-01

    We review the topic of rotation curves of spiral galaxies emphasizing the standard interpretation as evidence for the existence of dark matter halos. Galaxies other than spirals and late-type dwarfs may also possess great amounts of dark matter, and therefore ellipticals, dwarf spirals, lenticulars and polar ring galaxies are also considered. Furthermore, other methods for determining galactic dark matter, such as those provided by binaries, satellites or globular clusters, have to be included. Cold dark matter hierarchical models constitute the standard way to explain rotation curves, and thus the problem becomes just one aspect of a more general theory explaining structure and galaxy formation. Alternative theories also are included. In the magnetic model, rotation curves could also be a particular aspect of the whole history of cosmic magnetism during different epochs of the Universe. Modifications of Newtonian Dynamics provide another interesting possibility which is discussed here.

  15. Simulation algorithm for spiral case structure in hydropower station

    Institute of Scientific and Technical Information of China (English)

    Xin-yong XU; Zhen-yue MA; Hong-zhan ZHANG

    2013-01-01

    In this study, the damage-plasticity model for concrete that was verified by the model experiment was used to calculate the damage to a spiral case structure based on the damage mechanics theory. The concrete structure surrounding the spiral case was simulated with a three-dimensional finite element model. Then, the distribution and evolution of the structural damage were studied. Based on investigation of the change of gap openings between the steel liner and concrete structure, the impact of the non-uniform variation of gaps on the load-bearing ratio between the steel liner and concrete structure was analyzed. The comparison of calculated results of the simplified and simulation algorithms shows that the simulation algorithm is a feasible option for the calculation of spiral case structures. In addition, the shell-spring model was introduced for optimization analysis, and the results were reasonable.

  16. The formation of spiral arms and rings in barred galaxies

    CERN Document Server

    Romero-Gomez, M; Masdemont, J J; García-Gomez, C

    2007-01-01

    We propose a new theory to explain the formation of spiral arms and of all types of outer rings in barred galaxies. We have extended and applied the technique used in celestial mechanics to compute transfer orbits. Thus, our theory is based on the chaotic orbital motion driven by the invariant manifolds associated to the periodic orbits around the hyperbolic equilibrium points. In particular, spiral arms and outer rings are related to the presence of heteroclinic or homoclinic orbits. Thus, R1 rings are associated to the presence of heteroclinic orbits, while R1R2 rings are associated to the presence of homoclinic orbits. Spiral arms and R2 rings, however, appear when there exist neither heteroclinic nor homoclinic orbits. We examine the parameter space of three realistic, yet simple, barred galaxy models and discuss the formation of the different morphologies according to the properties of the galaxy model. The different morphologies arise from differences in the dynamical parameters of the galaxy.

  17. Spiral density wave generation by vortices in Keplerian flows

    CERN Document Server

    Bodo, G; Murante, G; Tevzadze, A; Rossi, P; Ferrari, A

    2005-01-01

    We perform a detailed analytical and numerical study of the dynamics of perturbations (vortex/aperiodic mode, Rossby and spiral-density waves) in 2D compressible disks with a Keplerian law of rotation. We draw attention to the process of spiral-density wave generation from vortices, discussing, in particular, the initial, most peculiar stages of wave emission. We show that the linear phenomenon of wave generation by vortices in smooth (without inflection points) shear flows found by using the so-called non-modal approach, is directly applicable to the present case. After an analytical non-modal description of the physics and characteristics of the spiral-density wave generation/propagation in the local shearing-sheet model, we follow the process of wave generation by small amplitude coherent circular vortex structures, by direct global numerical simulation, describing the main features of the generated waves.

  18. Gas and stellar spiral arms and their offsets in the grand-design spiral galaxy M51

    CERN Document Server

    Egusa, Fumi; Koda, Jin; Baba, Junichi

    2016-01-01

    Theoretical studies on the response of interstellar gas to a gravitational potential disc with a quasi-stationary spiral arm pattern suggest that the gas experiences a sudden compression due to standing shock waves at spiral arms. This mechanism, called a galactic shock wave, predicts that gas spiral arms move from downstream to upstream of stellar arms with increasing radius inside a corotation radius. In order to investigate if this mechanism is at work in the grand-design spiral galaxy M51, we have measured azimuthal offsets between the peaks of stellar mass and gas mass distributions in its two spiral arms. The stellar mass distribution is created by the spatially resolved spectral energy distribution fitting to optical and near infrared images, while the gas mass distribution is obtained by high-resolution CO and HI data. For the inner region (r < 150"), we find that one arm is consistent with the galactic shock while the other is not. For the outer region, results are less certain due to the narrower...

  19. Nuclear Theory - Nuclear Power

    Science.gov (United States)

    Svenne, J. P.; Canton, L.; Kozier, K. S.

    2008-01-01

    The results from modern nuclear theory are accurate and reliable enough to be used for practical applications, in particular for scattering that involves few-nucleon systems of importance to nuclear power. Using well-established nucleon-nucleon (NN) interactions that fit well the NN scattering data, and the AGS form of the three-body theory, we have performed precise calculations of low-energy neutron-deuteron (n+d) scattering. We show that three-nucleon force effects that have impact on the low-energy vector analyzing powers have no practical effects on the angular distribution of the n+d cross-section. There appear to be problems for this scattering in the evaluated nuclear data file (ENDF) libraries, at the incident neutron energies less than 3.2 MeV. Supporting experimental data in this energy region are rather old (>25 years), sparse and often inconsistent. Our three-body results at low energies, 50 keV to 10.0 MeV, are compared to the ENDF/B-VII.0 and JENDL (Japanese Evaluated Nuclear Data Library) -3.3 evaluated angular distributions. The impact of these results on the calculated reactivity for various critical systems involving heavy water is shown.

  20. Infant feeding: formula, solids.

    Science.gov (United States)

    Barness, L A

    1985-04-01

    This article discusses and evaluates current formulas, traces their continual improvement (based largely on new information on breast milk composition), and then discusses the question of supplemental feedings.

  1. Danger of zooplankton feeding

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Jiang, H.; Colin, S.P.

    2010-01-01

    Zooplankton feed in any of three ways: they generate a feeding current while hovering, cruise through the water or are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly and ther......Zooplankton feed in any of three ways: they generate a feeding current while hovering, cruise through the water or are ambush feeders. Each mode generates different hydrodynamic disturbances and hence exposes the grazers differently to mechanosensory predators. Ambush feeders sink slowly...

  2. Tidal Origin of Spiral Arms in Galaxies Orbiting a Cluster

    Science.gov (United States)

    Semczuk, Marcin; Łokas, Ewa L.; del Pino, Andrés

    2017-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using N-body simulations we investigate the formation and evolution of spiral arms in a Milky-Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution are followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit; however, they wind up rather quickly and are disturbed by another pericenter passage. The arms on the most extended orbit, which we analyze in more detail, wind up slowly and survive for the longest time. Measurements of the pattern speed of the arms indicate that they are kinematic density waves. We attempt a comparison with observations by selecting grand-design spiral galaxies in the Virgo cluster. Among those, we find nine examples bearing no sign of recent interactions or the presence of companions. For three of them we present close structural analogues among our simulated spiral galaxies.

  3. Spiral Wound Reverse Osmosis Membranes for the Recovery of Phenol Compounds-Experimental and Parameter Estimation Studies

    Directory of Open Access Journals (Sweden)

    G. Srinivasan

    2010-01-01

    Full Text Available Problem statement: Reverse osmosis is increasingly used as a separation technique in chemical and environmental engineering for the removal of organics and organic pollutants present in waste water. The removal of an organic compound, namely phenol, using a polyamide membrane was investigated in this study. Waste water containing phenol present a serious environmental problem and increasing attention is being given for its removal using RO membranes. Objective of this study is to (i generate experimental data related to the removal of phenol using a spiral wound polyamide membrane (ii analyze the performance of the membrane using solution-diffusion model and validate the model with the experimental data. Approach: Experiments were conducted on a laboratory scale spiral wound polyamide RO module. The permeate concentrations and rejection coefficient values were measured for various feed inlet pressures and feed concentrations. The total feed flow rate, 3.33×10-4 m3 sec-1 (20 LPM was not varied. The transport of solvent and solute through the membranes were analyzed using solution-diffusion model taking concentration polarization into account. Results: By varying inlet pressures from 4-14 kgf cm-2 and feed concentrations of phenol from 200-1100 ppm, the rejection coefficients of the membrane were measured and found to vary from 64-91%. The solvent and solute transport parameters were determined by a graphical procedure using the experimental data and its values were 5.9×10-7 (m atm-1 and 6.54×10-7 (m sec-1 respectively. Conclusion: The model and the estimated parameter values were validated with the experimental data. The model was able to predict the rejection within 10% error. In view of the fact that not much information is available on the usage of spiral wound polyamide RO membrane modules for the removal of phenolic compounds, it may be concluded that the experimental results reported in this study is very significant in the scale up and

  4. Quantitative imaging of complex samples by spiral phase contrast microscopy.

    Science.gov (United States)

    Bernet, Stefan; Jesacher, Alexander; Fürhapter, Severin; Maurer, Christian; Ritsch-Marte, Monika

    2006-05-01

    Recently a spatial spiral phase filter in a Fourier plane of a microscopic imaging setup has been demonstrated to produce edge enhancement and relief-like shadow formation of amplitude and phase samples. Here we demonstrate that a sequence of at least 3 spatially filtered images, which are recorded with different rotational orientations of the spiral phase plate, can be used to obtain a quantitative reconstruction of both, amplitude and phase information of a complex microscopic sample, i.e. an object consisting of mixed absorptive and refractive components. The method is demonstrated using a calibrated phase sample, and an epithelial cheek cell.

  5. Rotation and mass in the Milky Way and spiral galaxies

    Science.gov (United States)

    Sofue, Yoshiaki

    2017-02-01

    Rotation curves are the basic tool for deriving the distribution of mass in spiral galaxies. In this review, we describe various methods to measure rotation curves in the Milky Way and spiral galaxies. We then describe two major methods to calculate the mass distribution using the rotation curve. By the direct method, the mass is calculated from rotation velocities without employing mass models. By the decomposition method, the rotation curve is deconvolved into multiple mass components by model fitting assuming a black hole, bulge, exponential disk, and dark halo. The decomposition is useful for statistical correlation analyses among the dynamical parameters of the mass components. We also review recent observations and derived results.

  6. Incommensurate Spiral Order from Double-Exchange Interactions

    Science.gov (United States)

    Azhar, Maria; Mostovoy, Maxim

    2017-01-01

    The double-exchange model describing interactions of itinerant electrons with localized spins is usually used to explain ferromagnetism in metals. We show that for a variety of crystal lattices of different dimensionalities and for a wide range of model parameters, the ferromagnetic state is unstable against a noncollinear spiral magnetic order. We revisit the phase diagram of the double-exchange model on a triangular lattice and show in a large part of the diagram the incommensurate spiral state has a lower energy than the previously discussed commensurate states. These results indicate that double-exchange systems are inherently frustrated and can host unconventional spin orders.

  7. Digital spiral-slit for bi-photon imaging

    Science.gov (United States)

    McLaren, Melanie; Forbes, Andrew

    2017-04-01

    Quantum ghost imaging using entangled photon pairs has become a popular field of investigation, highlighting the quantum correlation between the photon pairs. We introduce a technique using spatial light modulators encoded with digital holograms to recover both the amplitude and the phase of the digital object. Down-converted photon pairs are entangled in the orbital angular momentum basis, and are commonly measured using spiral phase holograms. Consequently, by encoding a spiral ring-slit hologram into the idler arm, and varying it radially we can simultaneously recover the phase and amplitude of the object in question. We demonstrate that a good correlation between the encoded field function and the reconstructed images exists.

  8. Status of the SPIRAL I upgrade at GANIL

    Energy Technology Data Exchange (ETDEWEB)

    Jardin, P.; Bajeat, O.; Delahaye, P.; Dubois, M.; Feierstein, C.; Pellemoine, F.; Lecomte, P.; Leherissier, P.; Maunoury, L.; Saint-Laurent, M. G.; Traykov, E. [GANIL, Grand Accelerateur National d' Ions Lourds, CEA-DSM/CNRS-IN2P3, Blvd. H. Becquerel, BP 55027 14076 Caen Cedex 5 (France); Couratin, C. [LPC, Laboratoire de Physique Corpusculaire, CNRS-IN2P3/Universite de Caen Basse-Normandie/ENSICaen, Blvd. Marechal Juin, 14050 Caen Cedex (France)

    2012-02-15

    The upgrade of the ''Systeme de Production d'Ions Radioactifs en Ligne'' phase I (SPIRAL I) installed at the ''Grand Accelerateur National d'Ions Lourds'' (GANIL) situated at Caen, France, is in progress and should be ready by 2014. In parallel, the first part of SPIRAL II facility is currently under construction. The global status of the upgrade is presented: goal, radioactive ion production systems, modification of the production cave and impact of the current safety re-evaluation of GANIL.

  9. Effect of the silicon substrate structure on chip spiral inductor

    Institute of Scientific and Technical Information of China (English)

    Chunlai XUE; Fei YAO; Buwen CHENG; Qiming WANG

    2008-01-01

    In this paper, the effect of the substrate structure on the performance of the spiral inductor is investigated by the 3-D electromagnetic simulator, Ansoft high frequency structure simulator (HFSS). With variations in the substrate structure including substrate conductivity, permittivity and thickness of the dielectric layer, the performance of the inductors has been analyzed in detail. The simulation results and analyses indicate that the performance of the spiral inductor can be mostly improved by lowering the conductivity of the substrate, increasing the thickness of the dielectric layer and using the low K dielectric layer. In the mean time, some guidelines or "design rules" are summarized by the results of this study.

  10. Illuminating the Role of Spiral Waves in Circumstellar Disks

    Science.gov (United States)

    Bae, Jaehan; Hartmann, Lee W.

    2017-01-01

    The transport of angular momentum and mass, and the generation of turbulence, play a crucial role in the evolution of a variety of astrophysical disks. Spiral waves, driven for instance by companion bodies or instabilities, have long been recognized as an important means for the aforementioned two processes. In this dissertation talk, I will discuss an instability of spiral waves that I have recently come across. I will begin by presenting the results from a three-dimensional global hydrodynamic simulation which described the growth and saturation of the instability. The spiral wave instability (SWI) arises as inertial modes, natural oscillations in rotating systems, amplify when they resonantly couple to and extract energy from the background spiral waves. This leads to break down of the spiral waves into turbulence when the velocity perturbations caused by unstable inertial modes reach a similar magnitude to those induced by the spiral waves. As an implication of the instability, I will present numerical results and discuss the consequence of the SWI when it acts on the spiral waves driven by a Jupiter-mass planet in a protoplanetary disk. I find that the planet-driven spiral arms are destabilized via the SWI, generating hydrodynamic turbulence and sustained vertical flows that are associated with long wavelength inertial modes. The associated vertical diffusion rate measured from the simulations is such that solid particles with sizes up to a few centimeters are vertically mixed within the first scale height in a protosolar nebula-like disk. Since circumstellar disks are believed to remain laminar, and thus to induce no or very little particle stirring as suggested by recent magnetocentrifugal wind models, the results imply that the SWI can be the mechanism controlling the degree of vertical settling of solid particles in planet-hosting disks. In particular, if accretion of mm- to cm-sized pebbles dominates the growth of terrestrial bodies, the stirring of solid

  11. Eventful Evolution of Giant Molecular Clouds in Dynamically Evolving Spiral Arms

    CERN Document Server

    Baba, Junichi; Saitoh, Takayuki R

    2016-01-01

    The formation and evolution of giant molecular clouds (GMCs) in spiral galaxies have been investigated in the traditional framework of the combined quasi-stationary density wave and galactic shock model. However, our understanding of the dynamics of spiral arms is changing from the traditional spiral model to a dynamically evolving spiral model. In this study, we investigate the structure and evolution of GMCs in a dynamically evolving spiral arm using a three-dimensional N-body/hydrodynamic simulation of a barred spiral galaxy at parsec-scale resolution. This simulation incorporated self-gravity, molecular hydrogen formation, radiative cooling, heating due to interstellar far-ultraviolet radiation, and stellar feedback by both HII regions and Type-II supernovae. In contrast to a simple expectation based on the traditional spiral model, the GMCs exhibited no systematic evolutionary sequence across the spiral arm. Our simulation showed that the GMCs behaved as highly dynamic objects with eventful lives involvi...

  12. A spiral wave front beacon for underwater navigation: basic concept and modeling.

    Science.gov (United States)

    Hefner, Brian T; Dzikowicz, Benjamin R

    2011-06-01

    A spiral wave front source produces an acoustic field that has a phase that is proportional to the azimuthal angle about the source. The concept of a spiral wave front beacon is developed by combining this source with a reference source that has a phase that is constant with the angle. The phase difference between these sources contains information about the receiver's azimuthal angle relative to the beacon and can be used for underwater navigation. To produce the spiral wave front, two sources are considered: a "physical-spiral" source, which produces the appropriate phase by physically deforming the active element of the source into a spiral, and a "phased-spiral" source, which uses an array of active elements, each driven with the appropriate phase, to produce the spiral wave front. Using finite element techniques, the fields produced by these sources are examined in the context of the spiral wave front beacon, and the advantages of each source are discussed.

  13. Seismic cyclic loading test of SRC columns confined with 5-spirals

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Presented herein is an experimental study on seismic resistance of rectangular steel reinforced concrete (SRC) columns confined with a new type of multi-spiral cage. The multi-spiral cage is a device of five interconnected spirals, named "5-spirals", with a large spiral at the center and four small ones at the corners. The innovation of applying the 5-spirals to SRC column is to take its superiority in concrete confinement and efficiency in automatic production for the precast construction industry. Four full-scale SRC columns were tested under horizontal cyclic loading. All of the tested columns were capable of sustaining a drift angle up to 6% radians. The hysteresis loops observed from the cyclic loading tests indicated that the spirally confined SRC columns demonstrated excellent performances in both strength and ductility. The test results suggested that with significant saving of the confinement steel, the newly innovated 5-spirals can be successfully applied to the precast rectangular SRC columns.

  14. Formation and instability of spiral wave induced by Gaussian coloured noise

    Institute of Scientific and Technical Information of China (English)

    Gan Zheng-Ning; Ma Jun; Zhang Guo-Yong; Chen Yong

    2008-01-01

    In this paper,we studied the effect of Gauesian coloured noise on the formation and instability of spiral waves described by one class of modified FitzHugh-Nagumo equation.It was found that Gaussian coloured noise plays a constructive role in the formation,transition and instability of spiral wave.Too weak or too strong noise may act against the formation of spiral waves.At a certain noise level,spiral wave is maintained in a medium,in which spiral wave cannot be observed in the absence of the noise.It is difficult to make a stable spiral wave into unstable state by Gaussian coloured noise,unless the noise level is very high.The parameter regions of Gaussian coloured noise for spiral forming and spiral instability were given and discussed with numerical simulations.

  15. Spiral wave drift and complex-oscillatory spiral waves caused by heterogeneities in two-dimensional in vitro cardiac tissues

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Sung-Jae; Hong, Jin Hee; Kim, Tae Yun; Bae, Byung Wook; Lee, Kyoung J [CRI Center for Neurodynamics and Department of Physics, Korea University, Seoul 136-713 (Korea, Republic of)], E-mail: kyoung@nld.korea.ac.kr

    2008-01-15

    Understanding spiral reentry wave dynamics in cardiac systems is important since it underlies various cardiac arrhythmia including cardiac fibrillation. Primary cultures of dissociated cardiac cells have been a convenient and useful system for studying cardiac wave dynamics, since one can carry out systematic and quantitative studies with them under well-controlled environments. One key drawback of the dissociated cell culture is that, inevitably, some spatial inhomogeneities in terms of cell types and density, and/or the degree of gap junction connectivity, are introduced to the system during the preparation. These unintentional spatial inhomogeneities can cause some non-trivial wave dynamics, for example, the entrainment dynamics among different spiral waves and the generation of complex-oscillatory spiral waves. The aim of this paper is to quantify these general phenomena in an in vitro cardiac system and provide explanations for them with a simple physiological model having some realistic spatial inhomogeneities incorporated.

  16. Light-Gradient-Induced Spiral Wave Drifts in a Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ The dynamic behaviour of spiral tip in the light-sensitive Belousov-Zhabotinsky reaction under the influence of an externally applied light gradient was experimentally studied. The gradient causes different drifts for different spiral patterns. The centre of the spiral wave moved toward the region of lower light intensity. The direction of an additional perpendicular drift depended on the chirality of the spiral wave. The dependences of the drifting angle and the drifting velocity on light gradient have been measured.

  17. Selection of Feed Intake or Feed Efficiency

    DEFF Research Database (Denmark)

    Veerkamp, Roel F; Pryce, Jennie E; Spurlock, Diane

    2013-01-01

    . In February 2013, the co-authors discussed how information on DMI should be incorporated in the breeding decisions. The aim of this paper is to present the overall discussion and main positions taken by the group on four topics related to feed efficiency: i) breeding goal definition; ii) biological variation...

  18. Selection of Feed Intake or Feed Efficiency

    DEFF Research Database (Denmark)

    Veerkamp, Roel F; Pryce, Jennie E; Spurlock, Diane

    2013-01-01

    . In February 2013, the co-authors discussed how information on DMI should be incorporated in the breeding decisions. The aim of this paper is to present the overall discussion and main positions taken by the group on four topics related to feed efficiency: i) breeding goal definition; ii) biological variation...

  19. Feeding biology of Cerambycids

    Science.gov (United States)

    Robert A. Haack

    2017-01-01

    There are more than 36,000 species of Cerambycidae recognized throughout the world (see Chapter 1), occurring on all continents except Antarctica (Linsley 1959). Given such numbers, it is not surprising that cerambycids display great diversity in their feeding habits. Both adults and larvae are almost exclusively phytophagous. Some adults appear not to feed at all,...

  20. Creep Feeding Beef Calves

    OpenAIRE

    2005-01-01

    Creep feeding is the managerial practice of supplying supplemental feed (usually concentrates) to the nursing calf. Milk from a lactating beef cow furnishes only about 50 percent of the nutrients that a 3-4 month-old calf needs for maximum growth.

  1. Feeding Your Baby

    Medline Plus

    Full Text Available ... Baby Caring for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications ... write(' Feeding your baby ') document.write('') } ') document.write(' Common illnesses ') document.write('') } ') document.write(' Family health & safety ') ...

  2. Wideband Cavity Backed Spiral Antenna for Stepped Frequency Ground Penetrating Radar

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne; Lenler-Eriksen, Hans-Rudolph

    2005-01-01

    A 1.7 turn cavity backed coplanar waveguide to coplanar strip-fed logarithmic uniplanar spiral antenna is presented and compared to a 1.5 turn spiral antenna. The 1.7 turn spiral antenna has a wide beamwidth, are circular polarised and has a bandwidth with a return loss better than 6 d...

  3. Controlling Spiral Waves by Modulations Resonant with the Intrinsic System Mode

    Institute of Scientific and Technical Information of China (English)

    XIAO Jing-Hua; HU Gang; HU Bam-Bi

    2004-01-01

    We investigate the spiral wave control in the two-dimensional complex Ginzburg-Landau equation. External drivings which are not resonant with spiral waves but with intrinsic system modes are used to successfully annihilate spiral waves and direct the system to various target states. The novel control mechanism is intuitively explained and the richness and flexibility the control results are emphasized.

  4. Dynamics of the Spiral Tip in a Closed Belousov-Zhabotinsky Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui-Jie; WANG Peng-Ye; ZHAO Ying-Ying

    2005-01-01

    @@ Dynamics of spiral tip rotating in a closed system of the light sensitive Belousov-Zhabotinsky reaction is studied under a homogeneous and steady illumination. The time dependence of the kinematical parameters of meandering spiral is presented and the experimental evidence is obtained for self-synchronization of the spiral tip in a closed B-Z system without external feedback.

  5. Nuclear control

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Wan Kee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-02-01

    International cooperation in nuclear industries requires nuclear control as prerequisites. The concept of nuclear control is based on the Treaty on the Non-proliferation of Nuclear Weapon (NPT). The International Atomic Energy Agency (IAEA) plays central role in implementing nuclear control. Nuclear control consists of nuclear safeguards, physical protection, and export/import control. Each member state of NPT is subject to the IAEA`s safeguards by concluding safeguards agreements with the IAEA. IAEA recommends member states to implement physical protection on nuclear materials by `The Physical Protection of Nuclear Material` and `The Convention on the Physical Protection of Nuclear Material` of IAEA. Export/Import Control is to deter development of nuclear weapons by controlling international trade on nuclear materials, nuclear equipments and technology. Current status of domestic and foreign nuclear control implementation including recent induction of national inspection system in Korea is described and functions of recently set-up Technology Center for Nuclear Control (TCNC) under the Korea Atomic Energy Research Institute (KAERI) are also explained. 6 tabs., 11 refs. (Author).

  6. Phenotypic differentiation of neonatal rat cochlear spiral ganglion neurons following trypsin dissociation and culture

    Institute of Scientific and Technical Information of China (English)

    Dingjun Zha; Li Qiao; Lianjun Lu; Xue Gao; Tao Xue; Wenjuan Mi; Shunli Liu; Jianhua Qiu

    2008-01-01

    BACKGROUND: Under laboratory conditions, cochlear spiral ganglion neurons are commonly isolated and cultured by mechanical dissociation. However, these neurons are extremely fragile and survive for only a short time.OBJECTIVE: To establish a trypsin dissociation and culture method for studying neonatal rat cochlear spiral ganglion neurons. DESIGN: A single sample study. SETTING: Department of Otolaryngology, Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University of Chinese PLA.MATERIALS: This study was performed at the central laboratory for Department of Otolaryngology, Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University of Chinese PLA from February to May 2006. A total of 40 neonatal Sprague Dawley rats of either gender, aged 2-5 days, were provided by the Laboratory Animal Center of the Fourth Military Medical University of Chinese PLA. Trypsin and neuronal-specific nuclear protein (NeuN) monoclonal antibodies were purchased from Sigma Company, USA. Culture medium was synthesized using Dulbecco's modified Eagle's medium (DMEM)/F12 (Gibco Company, USA) supplemented with 10% fetal bovine serum (Sigma Company, USA), 100 000 U/L penicillin, and 1 mol/L NaOH. The following protocol was performed in accordance with ethical guidelines for the use and care of animals.METHODS: After anesthesia, rats were sacrificed by neck dislocation. A complete cochlear axis with spiral ganglion tissue was removed. The cochlear axis was rinsed three times in a culture dish with a diameter of 35 mm using Hank's balanced solution. After washings, the tissue was cut into pieces, digested with 0.25% trypsin for about 20 minutes, and incubated in a 37 ℃ water bath. The tissue was centrifuged, then mixed with serum-containing culture medium. Using a transfer pipette, the cell suspension was transferred to polylysine (0.1%)-treated culture dishes with a diameter of 35 mm. The culture dish was incubated at 37 ℃, with a 5% CO2-air environment. Once

  7. Challenges in measuring feed efficiency

    Science.gov (United States)

    The term feed efficiency is vague, and is defined differently by people. Historically, feed efficiency has been defined as the feed:gain (F:G) ratio or the inverse (G:F). Indexes have been developed to rank animals for feed efficiency. These indexes include residual feed intake (RFI) and residual...

  8. The potential of standard and modified feed spacers for biofouling control

    KAUST Repository

    Araújo, Paula A.

    2012-06-01

    The impact of feed spacers on initial feed channel pressure (FCP) drop, FCP increase and biomass accumulation has been studied in membrane fouling simulators using feed spacers applied in commercially available nanofiltration and reverse osmosis spiral wound membrane modules. All spacers had a similar geometry.Our studies showed that biofouling was not prevented by (i) variation of spacer thickness, (ii) feed spacer orientation, (iii) feed spacer coating with silver, copper or gold and (iv) using a biostatic feed spacer. At constant feed flow, a lower FCP and FCP increase were observed for a thicker feed spacer. At constant linear flow velocity, roughly the same FCP development and biomass accumulation were found irrespective of the feed spacer thickness: hydrodynamics and substrate load were more important for development and impact of biofouling than the thickness of currently applied spacers. Use of biostatic and metal coated spacers were not effective for biofouling control. The same small reduction of biofouling rate was observed with copper and silver coated spacers as well as uncoated 45° rotated spacers.The studied modified spacers were not effective for biofouling prevention and control. The impact of biofouling on FCP increase was reduced significantly by a lower linear flow velocity, while spacer orientation and spacer thickness in membrane modules had a smaller but still significant effect. © 2012 Elsevier B.V.

  9. Long term complications of the intraprostatic spiral. Case report

    DEFF Research Database (Denmark)

    Krogh, J

    1992-01-01

    A 76-year-old man had an intraprostatic spiral inserted to relieve bladder outlet obstruction that was caused by benign prostatic hypertrophy. After 30 months numerous complications had arisen including severe encrustations, urethral stricture, and sclerosis of the bladder neck. Regular replacement...

  10. Advanced Manufacture of Spiral Bevel and Hypoid Gears

    Directory of Open Access Journals (Sweden)

    Vilmos Simon

    2016-11-01

    Full Text Available In this study, an advanced method for the manufacture of spiral bevel and hypoid gears on CNC hypoid generators is proposed. The optmal head-cutter geometry and machine tool settings are determined to introduce the optimal tooth surface modifications into the teeth of spiral bevel and hypoid gears. The aim of these tooth surface modifications is to simultaneously reduce the tooth contact pressure and the transmission errors, to maximize the EHD load carrying capacity of the oil film, and to minimize power losses in the oil film. The proposed advanced method for the manufacture of spiral bevel and hypoid gears is based on machine tool setting variation on the cradle-type generator conducted by optimal polynomial functions and on the use of a CNC hypoid generator. An algorithm is developed for the execution of motions on the CNC hypoid generator using the optimal relations on the cradle-type machine. Effectiveness of the method was demonstrated by using spiral bevel and hypoid gear examples. Significant improvements in the operating characteristics of the gear pairs are achieved.

  11. Gas mass fractions and the evolution of spiral galaxies

    NARCIS (Netherlands)

    McGaugh, SS; DeBlok, WJG

    1997-01-01

    We show that the gas mass fraction of spiral galaxies is strongly correlated with luminosity and surface brightness. It is not correlated with linear size. Gas fraction varies with luminosity and surface brightness at the same rate, indicating evolution at fixed size. Dim galaxies are clearly less e

  12. Enhanced Abundances in Spiral Galaxies of the Pegasus I Cluster

    CERN Document Server

    Robertson, Paul; Blanc, Guillermo A

    2011-01-01

    We study the influence of cluster environment on the chemical evolution of spiral galaxies in the Pegasus I cluster. We determine the gas-phase heavy element abundances of six galaxies in Pegasus derived from H II region spectra obtained from integral-field spectroscopy. These abundances are analyzed in the context of Virgo, whose spirals are known to show increasing interstellar metallicity as a function of H I deficiency. The galaxies in the Pegasus cluster, despite its lower density and velocity dispersion, also display gas loss due to ISM-ICM interaction, albeit to a lesser degree. Based on the abundances of 3 H I deficient spirals and 2 H I normal spirals, we observe a heavy element abundance offset of +0.13\\pm0.07 dex for the H I deficient galaxies. This abundance differential is consistent with the differential observed in Virgo for galaxies with a similar H I deficiency, and we observe a correlation between log(O/H) and the H I deficiency parameter DEF for the two clusters analyzed together. Our resul...

  13. A Parallax-based Distance Estimator for Spiral Arm Sources

    Science.gov (United States)

    Reid, M. J.; Dame, T. M.; Menten, K. M.; Brunthaler, A.

    2016-06-01

    The spiral arms of the Milky Way are being accurately located for the first time via trigonometric parallaxes of massive star-forming regions with the Bar and Spiral Structure Legacy Survey, using the Very Long Baseline Array and the European VLBI Network, and with the Japanese VLBI Exploration of Radio Astrometry project. Here we describe a computer program that leverages these results to significantly improve the accuracy and reliability of distance estimates to other sources that are known to follow spiral structure. Using a Bayesian approach, sources are assigned to arms based on their (l, b, v) coordinates with respect to arm signatures seen in CO and H i surveys. A source's kinematic distance, displacement from the plane, and proximity to individual parallax sources are also considered in generating a full distance probability density function. Using this program to estimate distances to large numbers of star-forming regions, we generate a realistic visualization of the Milky Way's spiral structure as seen from the northern hemisphere.

  14. The local spiral structure of the Milky Way

    CERN Document Server

    Xu, Ye; Dame, Thomas; Menten, Karl; Sakai, Nobuyuki; Li, Jingjing; Brunthaler, Andreas; Moscadelli, Luca; Zhang, Bo; Zheng, Xingwu

    2016-01-01

    The nature of the spiral structure of the Milky Way has long been debated. Only in the last decade have astronomers been able to accurately measure distances to a substantial number of high-mass star-forming regions, the classic tracers of spiral structure in galaxies. We report distance measurements at radio wavelengths using the Very Long Baseline Array for eight regions of massive star formation near the Local spiral arm of the Milky Way. Combined with previous measurements, these observations reveal that the Local Arm is larger than previously thought, and both its pitch angle and star formation rate are comparable to those of the Galaxy's major spiral arms, such as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the Local Arm extend for a great distance along our line of sight and roughly along the solar orbit. Because of this orientation, these sources cluster both on the sky and in velocity to form the complex and long enigmatic Cygnus X region. We also identify a spur that branche...

  15. The observed spiral structure of the Milky Way

    CERN Document Server

    Hou, L G

    2014-01-01

    The spiral structure of the Milky Way is not yet well determined. The keys to understanding this structure are to increase the number of reliable spiral tracers and to determine their distances as accurately as possible. HII regions, giant molecular clouds (GMCs), and 6.7-GHz methanol masers are closely related to high mass star formation, and hence they are excellent spiral tracers. We update the catalogs of Galactic HII regions, GMCs, and 6.7-GHz methanol masers, and then outline the spiral structure of the Milky Way. We collected data for more than 2500 known HII regions, 1300 GMCs, and 900 6.7-GHz methanol masers. If the photometric or trigonometric distance was not yet available, we determined the kinematic distance using a Galaxy rotation curve with the current IAU standard, $R_0$ = 8.5 kpc and $\\Theta_0$ = 220 km s$^{-1}$, and the most recent updated values of $R_0$ = 8.3 kpc and $\\Theta_0$ = 239 km s$^{-1}$, after we modified the velocities of tracers with the adopted solar motions. With the weight fa...

  16. Tidal origin of spiral arms in galaxies orbiting a cluster

    CERN Document Server

    Semczuk, Marcin; del Pino, Andres

    2016-01-01

    One of the scenarios for the formation of grand-design spiral arms in disky galaxies involves their interactions with a satellite or another galaxy. Here we consider another possibility, where the perturbation is instead due to the potential of a galaxy cluster. Using $N$-body simulations we investigate the formation and evolution of spiral arms in a Milky Way-like galaxy orbiting a Virgo-like cluster. The galaxy is placed on a few orbits of different size but similar eccentricity and its evolution is followed for 10 Gyr. The tidally induced, two-armed, approximately logarithmic spiral structure forms on each of them during the pericenter passages. The spiral arms dissipate and wind up with time, to be triggered again at the next pericenter passage. We confirm this transient and recurrent nature of the arms by analyzing the time evolution of the pitch angle and the arm strength. We find that the strongest arms are formed on the tightest orbit, however they wind up rather quickly and are disturbed by another p...

  17. Spiral intensity patterns in the internally pumped optical parametric oscillator

    DEFF Research Database (Denmark)

    Lodahl, Peter; Bache, Morten; Saffman, Mark

    2001-01-01

    We describe a nonlinear optical system that supports spiral pattern solutions in the field intensity. This new spatial structure is found to bifurcate above a secondary instability in the internally pumped optical parametric oscillator. The analytical predictions of threshold and spatial scale...

  18. Scalable Automated Detection of Spiral Galaxy Arm Segments

    CERN Document Server

    Davis, Darren R

    2014-01-01

    Given an approximately centered image of a spiral galaxy, we describe an entirely automated method that finds, centers, and sizes the galaxy and then automatically extracts structural information about the spiral arms. For each arm segment found, we list the pixels in that segment and perform a least-squares fit of a logarithmic spiral arc to the pixels in the segment. The algorithm takes about 1 minute per galaxy, and can easily be scaled using parallelism. We have run it on all ~644,000 Sloan objects classified as "galaxy" and large enough to observe some structure. Our algorithm is stable in the sense that the statistics across a large sample of galaxies vary smoothly based on algorithmic parameters, although results for individual galaxies can sometimes vary in a non-smooth but easily understood manner. We find a very good correlation between our quantitative description of spiral structure and the qualitative description provided by humans via Galaxy Zoo. In addition, we find that pitch angle often varie...

  19. Vertically Conductive MoS2 Spiral Pyramid.

    Science.gov (United States)

    Ly, Thuc Hue; Zhao, Jiong; Kim, Hyun; Han, Gang Hee; Nam, Honggi; Lee, Young Hee

    2016-09-01

    MoS2 spirals grown by the chemical vapor deposition method, driven by a threading dislocation, has a peculiar rhombohedral-like structure. This threading dislocation can carry helical current in the vertical direction and greatly enhances the vertical conductance in the MoS2 multilayer samples.

  20. Outer Spiral Disks as Clues to Galaxy Formation and Evolution

    CERN Document Server

    Vlajić, Marija

    2010-01-01

    Recent studies of outer spiral disks have given rise to an abundance of new results. We discuss the observational and theoretical advances that have spurred the interest in disk outskirts, as well as where we currently stand in terms of our understanding of outer disk structure, ages and metallicities.

  1. Molecular Distribution in the Spiral Arm of M51

    CERN Document Server

    Watanabe, Yoshimasa; Sorai, Kazuo; Ueda, Junko; Yamamoto, Satoshi

    2016-01-01

    Molecular line images of 13CO, C18O, CN, CS, CH3OH, and HNCO are obtained toward the spiral arm of M51 at a 7" times 6" resolution with the Combined Array for Research in Millimeter-wave Astronomy (CARMA). Distributions of the molecules averaged over a 300 pc scale are found to be almost similar to one another and to essentially trace the spiral arm. However, the principal component analysis shows a slight difference of distributions among molecular species particularly for CH3OH and HNCO. These two species do not correlate well with star-formation rate, implying that they are not enhanced by local star-formation activities but by galactic-scale phenomena such as spiral shocks. Furthermore, the distribution of HNCO and CH3OH are found to be slightly different, whose origin deserves further investigation. The present results provide us with an important clue to understanding the 300 pc scale chemical composition in the spiral arm and its relation to galactic-scale dynamics.

  2. Spiral galaxy distance indicators based on near-infrared photometry

    NARCIS (Netherlands)

    Grijs, R. de; Peletier, R. F.

    1999-01-01

    We compare two methods of distance determination to spiral galaxies using optical/near-infrared (NIR) observations, the (I-K) versus M-K colour-absolute magnitude (CM) relation and the I- and K-band Tully-Fisher relation (TFR). Dust-free colours and NIR absolute magnitudes greatly enhance the

  3. Fingerprints of nucleosynthesis in the local spiral arm

    Science.gov (United States)

    Knoedlseder, J.; Bennett, K.; Bloemen, H.; Diehl, R.; Hermsen, W.; Oberlack, U.; Ryan, J.; Schoenfelder, V.; vonBallmoos, P.

    1997-01-01

    The local spiral arm with its inherent massive star population is a natural site of recent nucleosynthesis activity. The features found in 1.8 MeV observation of candidate Al-26 sources situated in this structure are discussed. The emphasis is on Loop 1, a nearby superbubble which is possibly the site of a recent supernova explosion.

  4. THE SURFACE BRIGHTNESS OF OUR GALAXY AND OTHER SPIRALS

    NARCIS (Netherlands)

    VANDERKRUIT, PC

    1990-01-01

    In this review I discuss some aspects of the luminosity distributions in our Galaxy and external spiral galaxies. The major conclusions are the following: (1) the radial scale length of the luminosity distribution in the disk of our Galaxy is 5.0 +/- 0.5 kpc, (2) on this basis the Hubble constant ne

  5. Elastic Sturmian spirals in the Lorentz-Minkowski plane

    Directory of Open Access Journals (Sweden)

    Uçum Ali

    2016-01-01

    Full Text Available In this paper we consider some elastic spacelike and timelike curves in the Lorentz-Minkowski plane and obtain the respective vectorial equations of their position vectors in explicit analytical form. We study in more details the generalized Sturmian spirals in the Lorentz-Minkowski plane which simultaneously are elastics in this space.

  6. Quintessence-like Dark Matter in Spiral Galaxies

    CERN Document Server

    Matos, T; Núñez, D; Ramírez, E

    2000-01-01

    Through the geodesic analysis of a static and axially symmetric space time,we present conditions over the state equation of an isotropic perfect fluid$p=\\omega d$, when it is considered as dark matter in spiral galaxies. The mainconclusion is that it can be an exotic fluid ($-1<\\omega <-1/3$) as it is foundfor Quintessence at cosmological scale.

  7. EM-wave absorption properties of hollow spiral iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenqiang, E-mail: zwqcau@gmail.com [College of Engineering, China Agricultural University, Beijing 100083 (China); Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China); Zhang, Deyuan [Bionic and Micro/Nano/Bio Manufacturing Technology Research Center, Beihang University, Beijing 100191 (China)

    2015-12-15

    Hollow iron spiral particles were fabricated successfully by thermal decomposition method, and they were heat-treated at different temperatures in N{sub 2} atmosphere. The electromagnetic wave absorption properties of hollow iron spiral particles were investigated ranging between 1 GHz and 18 GHz. The results indicated that the phase structures of the particles changed from amorphous to nanocrystal with the treating temperature rising, also causing the significant change in electromagnetic parameters and the reflection loss. The reflection loss could reach −33 dB at 16.2 GHz, indicating that the hollow iron spiral particles had the potential to be used in prepare the a high property EM-wave absorber. - Highlights: • Hollow iron spiral particles were fabricated by thermal decomposition method. • The particles changed from amorphous to nanocrystals with heat-treatment. • Particles’ EM-parameters have a great change after high temperature heat-treatment. • RL results show the particles have potential to be high property EM-wave absorber.

  8. Tuning magnetic spirals beyond room temperature with chemical disorder

    Science.gov (United States)

    Morin, Mickaël; Canévet, Emmanuel; Raynaud, Adrien; Bartkowiak, Marek; Sheptyakov, Denis; Ban, Voraksmy; Kenzelmann, Michel; Pomjakushina, Ekaterina; Conder, Kazimierz; Medarde, Marisa

    2016-12-01

    In the past years, magnetism-driven ferroelectricity and gigantic magnetoelectric effects have been reported for a number of frustrated magnets featuring ordered spiral magnetic phases. Such materials are of high-current interest due to their potential for spintronics and low-power magnetoelectric devices. However, their low-magnetic ordering temperatures (typically <100 K) greatly restrict their fields of application. Here we demonstrate that the onset temperature of the spiral phase in the perovskite YBaCuFeO5 can be increased by more than 150 K through a controlled manipulation of the Fe/Cu chemical disorder. Moreover, we show that this novel mechanism can stabilize the magnetic spiral state of YBaCuFeO5 above the symbolic value of 25 °C at zero magnetic field. Our findings demonstrate that the properties of magnetic spirals, including its wavelength and stability range, can be engineered through the control of chemical disorder, offering a great potential for the design of materials with magnetoelectric properties beyond room temperature.

  9. Ultra wideband coplanar waveguide fed spiral antenna for humanitarian demining

    DEFF Research Database (Denmark)

    Thaysen, Jesper; Jakobsen, Kaj Bjarne; Appel-Hansen, Jørgen

    2000-01-01

    to 1 bandwidth with a return loss better than 10 dB from 0.4 to 3.8 GHz is presented. A wideband balun covering the frequency range of the antenna was developed. The constructed spiral antenna is very useful in a stepped frequency ground penetrating radar for humanitarian demining due to the very...

  10. Spirals, chaos, and new mechanisms of wave propagation.

    Science.gov (United States)

    Chen, P S; Garfinkel, A; Weiss, J N; Karagueuzian, H S

    1997-02-01

    The chaos theory is based on the idea that phenomena that appear disordered and random may actually be produced by relatively simple deterministic mechanisms. The disordered (aperiodic) activation that characterizes a chaotic motion is reached through one of a few well-defined paths that are characteristic of nonlinear dynamical systems. Our group has been studying VF using computerized mapping techniques. We found that in electrically induced VF, reentrant wavefronts (spiral waves) are present both in the initial tachysystolic stage (resembling VT) and the later tremulous incoordination stage (true VF). The electrophysiological characteristics associated with the transition from VT to VF is compatible with the quasiperiodic route to chaos as described in the Ruelle-Takens theorem. We propose that specific restitution of action potential duration (APD) and conduction velocity properties can cause a spiral wave (the primary oscillator) to develop additional oscillatory modes that lead to spiral meander and breakup. When spiral waves begin to meander and are modulated by other oscillatory processes, the periodic activity is replaced by unstable quasiperiodic oscillation, which then undergoes transition to chaos, signaling the onset of VF. We conclude that VF is a form of deterministic chaos. The development of VF is compatible with quasiperiodic transition to chaos. These results indicate that both the prediction and the control of fibrillation are possible based on the chaos theory and with the advent of chaos control algorithms.

  11. Laboratory-Scale Simulation of Spiral Plumes in the Mantle

    CERN Document Server

    Sharifulin, A N

    2012-01-01

    On the basis of laboratory simulation a mechanism is established for the formation of the upper mantle convection spiral plumes from a hot point in the presence of a roll-type large-scale convective flow. The observed plume has horizontal sections near the upper limit, which may lead to the formation of chains of volcanic islands.

  12. Model for Simulating a Spiral Software-Development Process

    Science.gov (United States)

    Mizell, Carolyn; Curley, Charles; Nayak, Umanath

    2010-01-01

    A discrete-event simulation model, and a computer program that implements the model, have been developed as means of analyzing a spiral software-development process. This model can be tailored to specific development environments for use by software project managers in making quantitative cases for deciding among different software-development processes, courses of action, and cost estimates. A spiral process can be contrasted with a waterfall process, which is a traditional process that consists of a sequence of activities that include analysis of requirements, design, coding, testing, and support. A spiral process is an iterative process that can be regarded as a repeating modified waterfall process. Each iteration includes assessment of risk, analysis of requirements, design, coding, testing, delivery, and evaluation. A key difference between a spiral and a waterfall process is that a spiral process can accommodate changes in requirements at each iteration, whereas in a waterfall process, requirements are considered to be fixed from the beginning and, therefore, a waterfall process is not flexible enough for some projects, especially those in which requirements are not known at the beginning or may change during development. For a given project, a spiral process may cost more and take more time than does a waterfall process, but may better satisfy a customer's expectations and needs. Models for simulating various waterfall processes have been developed previously, but until now, there have been no models for simulating spiral processes. The present spiral-process-simulating model and the software that implements it were developed by extending a discrete-event simulation process model of the IEEE 12207 Software Development Process, which was built using commercially available software known as the Process Analysis Tradeoff Tool (PATT). Typical inputs to PATT models include industry-average values of product size (expressed as number of lines of code

  13. Planar Task Space Control of a Biarticular Manipulator Driven by Spiral Motors

    Directory of Open Access Journals (Sweden)

    Ahmad Zaki bin Hj Shukor

    2012-10-01

    Full Text Available This paper elaborates upon a musculoskeletal‐inspired robot manipulator using a prototype of the spiral motor developed in our laboratory. The spiral motors represent the antagonistic muscles due to the high forward/backward drivability without any gears or mechanisms. Modelling of the biarticular structure with spiral motor dynamics was presented and simulations were carried out to compare two control methods, Inverse Kinematics (IK and direct‐Cartesian control, between monoarticular only structures and biarticular structures using the spiral motor. The results show the feasibility of the control, especially in maintaining air gaps within the spiral motor.

  14. Anatomy of the bronchial arteries: imaging via spiral CT. Anatomie der Bronchialarterien - Darstellung mit der Spiral-CT

    Energy Technology Data Exchange (ETDEWEB)

    Schwickert, H.C. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Kauczor, H.U. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schweden, F. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie); Schild, H.H. (Universitaetskliniken, Mainz (Germany). Klinik mit Poliklinik fuer Radiologie)

    1994-06-01

    The purpose of our study was to evaluate the capability of spiral CT in detecting bronchial arteries and in classifying their anatomic variations. Patients and Methods: In 43 patients with different diseases routine spiral CTs of the chest were performed and evaluated retrospectively. Spiral CT was started with a delay of 30 seconds after contrast material application. Results: In 43 patients a total of 67 bronchial arteries were detected: 31 right, 35 left and one common trunk. 26 right bronchial arteries originated medially, 5 anteriorly from the descending aorta, 7 of them together with an intercostal artery. 25 right bronchial arteries passed dorsally, 6 ventrally to the oesophagus. On the left, all 35 bronchial arteries originated from the anterior aorta: 12 led ventrally through the aorticopulmonary window to the ventral wall of the main bronchus, 14 were directed caudally to the cranial and 9 laterally to the posterior aspect of the main bronchus. The discernible length varied between 15 and 90 mm on the right, and between 10 and 37 mm on the left side. Only in two cases did the proximal diameter measure more than 2 mm. Conclusion: Spiral CT offers the possibility to classify the anatomic course and pathologic changes of the bronchial arteries. (orig.)

  15. Fermented liquid feed for pigs

    OpenAIRE

    Missotten, Joris; Michiels, Joris; Ovyn, Anneke; De Smet, Stefaan; Dierick, Noël

    2010-01-01

    Since the announcement of the ban on the use of antibiotics as antimicrobial growth promoters in the feed of pigs in 2006 the investigation towards alternative feed additives has augmented considerably. Although fermented liquid feed is not an additive, but a feeding strategy, the experimental work examining its possible advantages also saw a rise. The use of fermented liquid feed (FLF) has two main advantages, namely that the simultaneous provision of feed and water may result in an alleviat...

  16. Quantification of the drawing of an Archimedes spiral through the analysis of its digitized picture.

    Science.gov (United States)

    Miralles, F; Tarongí, S; Espino, A

    2006-04-15

    We have developed a new quantitative analysis of spiral drawing that is able to evaluate any spiral execution and it has not temporal or spatial limitations in the obtaining of specimens. Thirty-one patients with action tremor and 24 control subjects were asked to draw an Archimedes spiral over a print template. Specimens were scanned and then treated through a semiautomatic computer program that reconstructs the temporal sequence of the spiral drawing by the subject. The spirals were first analysed by means of the cross-correlation coefficient with the spiral template. Secondly, the mean and the standard deviation of the distance between each point of the spiral drawing and the corresponding point of the spiral model were determined. Finally, the reconstructed spiral was analysed using the Fourier Transform. Its results were interpreted with the aid of a computer model of a tremulous spiral. The experimental variables were greater in the patients group respect to age-matched controls. There was also a high linear correlation between them and the clinical score given by three neurologists. Finally, Receiver Operating Characteristic (ROC) curves analysis shown that the method classified the spirals better than human ratters.

  17. Spiral- and bar-driven peculiar velocities in Milky Way-sized galaxy simulations

    Science.gov (United States)

    Grand, Robert J. J.; Bovy, Jo; Kawata, Daisuke; Hunt, Jason A. S.; Famaey, Benoit; Siebert, Arnaud; Monari, Giacomo; Cropper, Mark

    2015-10-01

    We investigate the kinematic signatures induced by spiral and bar structure in a set of simulations of Milky Way-sized spiral disc galaxies. The set includes test particle simulations that follow a quasi-stationary density wave-like scenario with rigidly rotating spiral arms, and N-body simulations that host a bar and transient, corotating spiral arms. From a location similar to that of the Sun, we calculate the radial, tangential and line-of-sight peculiar velocity fields of a patch of the disc and quantify the fluctuations by computing the power spectrum from a two-dimensional Fourier transform. We find that the peculiar velocity power spectrum of the simulation with a bar and transient, corotating spiral arms fits very well to that of APOGEE red clump star data, while the quasi-stationary density wave spiral model without a bar does not. We determine that the power spectrum is sensitive to the number of spiral arms, spiral arm pitch angle and position with respect to the spiral arm. However, it is necessary to go beyond the line-of-sight velocity field in order to distinguish fully between the various spiral models with this method. We compute the power spectrum for different regions of the spiral discs, and discuss the application of this analysis technique to external galaxies.

  18. Magnetostrictive hypersound generation by spiral magnets in the vicinity of magnetic field induced phase transition

    Science.gov (United States)

    Bychkov, Igor V.; Kuzmin, Dmitry A.; Kamantsev, Alexander P.; Koledov, Victor V.; Shavrov, Vladimir G.

    2016-11-01

    In present work we have investigated magnetostrictive ultrasound generation by spiral magnets in the vicinity of magnetic field induced phase transition from spiral to collinear state. We found that such magnets may generate transverse sound waves with the wavelength equal to the spiral period. We have examined two types of spiral magnetic structures: with inhomogeneous exchange and Dzyaloshinskii-Moriya interactions. Frequency of the waves from exchange-caused spiral magnetic structure may reach some THz, while in case of Dzyaloshinskii-Moriya interaction-caused spiral it may reach some GHz. These waves will be emitted like a sound pulses. Amplitude of the waves is strictly depends on the phase transition speed. Some aspects of microwaves to hypersound transformation by spiral magnets in the vicinity of phase transition have been investigated as well. Results of the work may be interesting for investigation of phase transition kinetics as well, as for various hypersound applications.

  19. MEASUREMENT OF GALACTIC LOGARITHMIC SPIRAL ARM PITCH ANGLE USING TWO-DIMENSIONAL FAST FOURIER TRANSFORM DECOMPOSITION

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Benjamin L.; Berrier, Joel C.; Shields, Douglas W.; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S.; Lacy, Claud H. S. [Arkansas Center for Space and Planetary Sciences, 202 Field House, University of Arkansas, Fayetteville, AR 72701 (United States); Puerari, Ivanio [Instituto Nacional de Astrofisica, Optica y Electronica, Calle Luis Enrique Erro 1, 72840 Santa Maria Tonantzintla, Puebla (Mexico)

    2012-04-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  20. Measurement of Galactic Logarithmic Spiral Arm Pitch Angle Using Two-Dimensional Fast Fourier Transform Decomposition

    CERN Document Server

    Davis, Benjamin L; Shields, Douglas W; Kennefick, Julia; Kennefick, Daniel; Seigar, Marc S; Lacy, Claud H S; Puerari, Ivânio

    2012-01-01

    A logarithmic spiral is a prominent feature appearing in a majority of observed galaxies. This feature has long been associated with the traditional Hubble classification scheme, but historical quotes of pitch angle of spiral galaxies have been almost exclusively qualitative. We have developed a methodology, utilizing two-dimensional fast Fourier transformations of images of spiral galaxies, in order to isolate and measure the pitch angles of their spiral arms. Our technique provides a quantitative way to measure this morphological feature. This will allow comparison of spiral galaxy pitch angle to other galactic parameters and test spiral arm genesis theories. In this work, we detail our image processing and analysis of spiral galaxy images and discuss the robustness of our analysis techniques.

  1. Nuclear Scans

    Science.gov (United States)

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  2. Nuclear Chemistry.

    Science.gov (United States)

    Chemical and Engineering News, 1979

    1979-01-01

    Provides a brief review of the latest developments in nuclear chemistry. Nuclear research today is directed toward increased activity in radiopharmaceuticals and formation of new isotopes by high-energy, heavy-ion collisions. (Author/BB)

  3. Feeding Your Baby

    Medline Plus

    Full Text Available ... sign in | my dashboard | sign out our cause health topics stories & media research & professionals get involved Search ... your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & premature ...

  4. Feeding Your Baby

    Medline Plus

    Full Text Available ... bond with her. Breast milk is the best food for your baby during the first year of ... feeding safe. And then get ready for solid foods ! In This Topic Breastfeeding help Breastfeeding is best ...

  5. Feeding Your Baby

    Medline Plus

    Full Text Available ... for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & premature birth The newborn intensive care unit (NICU) Birth defects & other health conditions Loss & ...

  6. Feeding Your Baby

    Medline Plus

    Full Text Available ... discomforts when breastfeeding Starting your baby on solid foods Using a breast pump Baby Feeding your ... health & safety ') document.write('') } Ask our experts! Have a question? ...

  7. Feeding Your Baby

    Medline Plus

    Full Text Available ... your baby Feeding your baby E-mail to a friend Please fill in all fields. Please enter ... hear about breakthroughs for babies and families. Ask a question Our health experts can answer questions about ...

  8. Feeding Your Baby

    Medline Plus

    Full Text Available ... bottle-feeding safe. And then get ready for solid foods ! In This Topic Breastfeeding help Breastfeeding is ... and discomforts when breastfeeding Starting your baby on solid foods Using a breast pump In This Topic ...

  9. Feeding Your Baby

    Medline Plus

    Full Text Available ... for your baby Feeding your baby Common illnesses Family health & safety Complications & Loss Pregnancy complications Preterm labor & ... health research Prematurity research centers For providers NICU Family Support® Prematurity Campaign Collaborative Info for your patients ...

  10. The origin of sigma-drops: mapping stellar kinematics and populations in spirals

    CERN Document Server

    Emsellem, E

    2006-01-01

    The link between nuclear activity and the host galaxy remains elusive. It seems now clear that the galactic environment is not the key, and that there is no significant apparent difference in terms of the presence of bars/spirals between active and non-active galaxies. Nuclear activity nevertheless requires a small central gas reservoir (10^4-10^7 Msun) which may be only partly consumed during the 10^6-10^7 yr AGN duty cycle. A possible route towards a better understanding of the involved physical processes is to directly probe the gravitational potential of the host galaxies, with the hope that the corresponding sensitive tracers (stars, gas) will deliver convincing evidence for a kinematic signature associated with the AGN. This is the motivation for an on-going survey of 50 galaxies, for which the two-dimensional kinematics of the (neutral, ionised and molecular) gas and stellar components are being obtained (see Dumas et al., this conference). With only 10 to 15% of Seyfert galaxies in the local Universe,...

  11. Nuclear weapons, nuclear effects, nuclear war

    Energy Technology Data Exchange (ETDEWEB)

    Bing, G.F.

    1991-08-20

    This paper provides a brief and mostly non-technical description of the militarily important features of nuclear weapons, of the physical phenomena associated with individual explosions, and of the expected or possible results of the use of many weapons in a nuclear war. Most emphasis is on the effects of so-called ``strategic exchanges.``

  12. Nuclear Ambitions

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    China will begin to build the world’s first third-generation nuclear power plant at the Sanmen Nuclear Power Project in Sanmen City, coastal Zhejiang Province, in March 2009, accord-ing to the State Nuclear Power Technology Corp.

  13. Nuclear structure

    CERN Document Server

    Nazarewicz, W

    1999-01-01

    Current developments in nuclear structure are discussed from a theoretical perspective. The studies of the nuclear many-body system provide us with invaluable information about the nature of the nuclear interaction, nucleonic correlations at various energy-distance scales, and the modes of the nucleonic matter.

  14. Breast feeding in IMD.

    Science.gov (United States)

    MacDonald, A; Depondt, E; Evans, S; Daly, A; Hendriksz, C; Chakrapani A, A; Saudubray, J-M

    2006-01-01

    Breast feeding has proven benefits for many infants with inherited metabolic disorders (IMDs) but, with the exception of phenylketonuria, there are few reports in other conditions. A questionnaire, completed by dietitians and clinicians from 27 IMD centres from 15 countries (caring for a total of over 8000 patients with IMDs on diet) identified breast feeding experience in IMD. Successful, demand breast feeding (in combination with an infant amino acid formula free of precursor amino acids) was reported in 17 infants with MSUD, 14 with tyrosinaemia type I, and 5 with homocystinuria. Eighty-nine per cent were still breast fed at 16 weeks. Fewer infants with organic acidaemias were demand breast fed (7 with propionic acidaemia; 6 with methylmalonic acidaemia and 13 with isovaleric acidaemia) (usually preceded by complementary feeds of a protein-free infant formula or infant amino acid formula free of precursor amino acids). Only 12 infants with urea cycle disorders were given demand breast feeds, but this was unsuccessful beyond 8 days in CPS deficiency. Further work is needed in developing guidelines for feeding and for clinical and biochemical monitoring for breast-fed infants with IMDs.

  15. Shadows and spirals in the protoplanetary disk HD 100453

    Science.gov (United States)

    Benisty, M.; Stolker, T.; Pohl, A.; de Boer, J.; Lesur, G.; Dominik, C.; Dullemond, C. P.; Langlois, M.; Min, M.; Wagner, K.; Henning, T.; Juhasz, A.; Pinilla, P.; Facchini, S.; Apai, D.; van Boekel, R.; Garufi, A.; Ginski, C.; Ménard, F.; Pinte, C.; Quanz, S. P.; Zurlo, A.; Boccaletti, A.; Bonnefoy, M.; Beuzit, J. L.; Chauvin, G.; Cudel, M.; Desidera, S.; Feldt, M.; Fontanive, C.; Gratton, R.; Kasper, M.; Lagrange, A.-M.; LeCoroller, H.; Mouillet, D.; Mesa, D.; Sissa, E.; Vigan, A.; Antichi, J.; Buey, T.; Fusco, T.; Gisler, D.; Llored, M.; Magnard, Y.; Moeller-Nilsson, O.; Pragt, J.; Roelfsema, R.; Sauvage, J.-F.; Wildi, F.

    2017-01-01

    Context. Understanding the diversity of planets requires studying the morphology and physical conditions in the protoplanetary disks in which they form. Aims: We aim to study the structure of the 10 Myr old protoplanetary disk HD 100453, to detect features that can trace disk evolution and to understand the mechanisms that drive these features. Methods: We observed HD 100453 in polarized scattered light with VLT/SPHERE at optical (0.6 μm, 0.8 μm) and near-infrared (1.2 μm) wavelengths, reaching an angular resolution of 0.02'', and an inner working angle of 0.09''. Results: We spatially resolve the disk around HD 100453, and detect polarized scattered light up to 0.42'' ( 48 au). We detect a cavity, a rim with azimuthal brightness variations at an inclination of 38° with respect to our line of sight, two shadows and two symmetric spiral arms. The spiral arms originate near the location of the shadows, close to the semi major axis. We detect a faint feature in the SW that can be interpreted as the scattering surface of the bottom side of the disk, if the disk is tidally truncated by the M-dwarf companion currently seen at a projected distance of 119 au. We construct a radiative transfer model that accounts for the main characteristics of the features with an inner and outer disk misaligned by 72°. The azimuthal brightness variations along the rim are well reproduced with the scattering phase function of the model. While spirals can be triggered by the tidal interaction with the companion, the close proximity of the spirals to the shadows suggests that the shadows could also play a role. The change in stellar illumination along the rim induces an azimuthal variation of the scale height that can contribute to the brightness variations. Conclusions: Dark regions in polarized images of transition disks are now detected in a handful of disks and often interpreted as shadows due to a misaligned inner disk. However, the origin of such a misalignment in HD 100453, and

  16. The distribution of natural numbers divisible by 2,3,5,11,13 and 17 on the Square Root Spiral

    CERN Document Server

    Hahn, Harry K

    2008-01-01

    The natural numbers divisible by the Prime Factors 2, 3, 5, 11, 13 and 17 lie on defined spiral graphs, which run through the Square Root Spiral. A mathematical analysis shows, that these spiral graphs are defined by specific quadratic polynomials. Basically all natural number which are divisible by the same prime factor lie on such spiral graphs. And these spiral graphs can be assigned to a certain number of Spiral Graph Systems, which have a defined spatial orientation to each other. This document represents a supplementation to my detailed introduction study to the Square Root Spiral, and it contains the missing diagrams and analyses, showing the distribution of the natural numbers divisible by 2, 3, 5, 11, 13 and 17 on the Square Root Spiral. My introduction study to the Square Root Spiral can be found in the arxiv-archive. The title of this study : The ordered distribution of the natural numbers on the Square Root Spiral.

  17. 31 CFR 540.317 - Uranium feed; natural uranium feed.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium feed; natural uranium feed... (Continued) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.317 Uranium feed; natural uranium feed....

  18. Feeding Versus Feedback in AGNs from Near-Infrared IFU Observations: The Case of Mrk79

    CERN Document Server

    Riffel, Rogemar A; Winge, Claudia

    2013-01-01

    We have mapped the gaseous kinematics and the emission-line flux distributions and ratios from the inner ~680pc radius of the Seyfert 1 galaxy Mrk79, using two-dimensional (2D) near-IR J- and Kl-band spectra obtained with the Gemini instrument NIFS at a spatial resolution of ~100pc and velocity resolution of ~40km/s. The molecular hydrogen flux distribution presents two spiral arms extending by ~700pc, one to the north and another to the south of the nucleus, with an excitation indicating heating by X-rays from the central source. The low velocity dispersion (sigma~50km/s) and rotation pattern supports a location of the H2 gas in the disk of the galaxy. Blueshifts observed along the spiral arm in the far side of the galaxy and redshifts in the spiral arm in the near side, suggest that the spiral arms are feeding channels of H2 to the inner 200pc. From channel maps along the H2 l2.1218um emission-line profile we estimate a mass inflow rate of ~4E-3 M_Sun/year, which is one order of magnitude smaller than the m...

  19. Nuclear spectroscopy

    CERN Document Server

    Ajzenberg-Selove, Fay

    1960-01-01

    Nuclear Spectroscopy, Part B focuses on the ways in which experimental data may be analyzed to furnish information about nuclear parameters and nuclear models in terms of which the data are interpreted.This book discusses the elastic and inelastic potential scattering amplitudes, role of beta decay in nuclear physics, and general selection rules for electromagnetic transitions. The nuclear shell model, fundamental coupling procedure, vibrational spectra, and empirical determination of the complex potential are also covered. This publication is suitable for graduate students preparing for exper

  20. Enhanced Microfluidic Mixing via a Tricritical Spiral Vortex Instability

    CERN Document Server

    Haward, Simon J; Alves, Manuel A; Oliveira, Paulo J; Goldenfeld, Nigel; Shen, Amy Q

    2015-01-01

    Experimental measurements and numerical simulations are made on fluid flow through cross-slot devices with a range of aspect (depth:width) ratios, 0.4 < alpha < 3.87. For low Reynolds numbers Re, the flow is symmetric and a sharp boundary exists between fluid streams entering the cross-slot from opposite directions. Above an alpha-dependent critical value Re_c, the flow undergoes a symmetry-breaking bifurcation (though remains steady and laminar) and a spiral vortex structure develops about the central axis of the outflow channel. An order parameter characterizing the instability grows according to a sixth-order Landau potential, and shows a progression from second order to first order transitions as alpha increases. A tricritical point occurs for alpha ~ 0.55. The spiral vortex acts as a mixing region in the flow field and this phenomenon can be used to drive enhanced mixing in microfluidic devices.