Sample records for hard outer shell

  1. Exotic Behavior of the Outer Shell of Bimetallic Nanoalloys

    Microsoft Academic Search

    L. Delfour; J. Creuze; B. Legrand

    2009-01-01

    In order to build the phase diagram of Cu-Ag nanoalloys, segregation isotherms for the different sites of the outer shell of a 405-atom cluster have been obtained by means of Monte Carlo simulations using N-body interatomic potentials. A dynamical equilibrium in phase space is observed for the (001) facets as well as for the (111) facets of the truncated octahedron.

  2. Acoustic destruction of a microcapsule having a hard plastic shell

    Microsoft Academic Search

    Daisuke Koyama; Atsushi Osaki; Wataru Kiyan; Yoshiaki Watanabe

    2006-01-01

    Acoustic destruction of a microcapsule having a hard plastic shell is discussed. In an ultrasonic drug delivery system, microcapsules having thin elastic shells release drugs that are contained therein when the shell is destroyed. In this paper, two subjects related to capsule destruction are discussed: the driving pulse duration for capsule destruction and the frequency dependence of capsule destruction. Optical

  3. On the strong influence of inner shell resonances upon the outer shell photoionization of endohedral atoms

    NASA Astrophysics Data System (ADS)

    Amusia, M. Ya.; Chernysheva, L. V.

    2012-03-01

    It is demonstrated by the example of the Xe atom stuffed inside the C60 fullerene, i.e., the endohedral Xe@C60, that the so-called confinement resonances in 4 d subshell strongly affect the photoionization cross section of outer 5 p and subvalent 5 s electrons near the 4 d ionization threshold. It is a surprise that these narrow inner 4 d shell resonances are not smeared out in the outer shell photoionization cross section. On the contrary; the inner shell resonances affect the outer cross section by enhancing them enormously. Close to its own photoionization thresholds, 5 p and 5 s photoionization cross sections of Xe@C60 are dominated by their own confinement resonances greatly affected by the amplification of the incoming radiation intensity due to polarization by it of the C60 electron shell. Between 4 d and 5 p thresholds, the effect of 4 d is becoming stronger while own resonances of 5 p and 5 s are becoming much less important.

  4. Stagnant lid convection in the outer shell of icy moons

    NASA Astrophysics Data System (ADS)

    Yao, Chloe; Deschamps, Frédéric; Tackley, Paul; Lowman, Julian; Sanchez-Valle, Carmen

    2013-04-01

    In the past decade, from both theoretical studies and spacecraft missions measurements, the internal structure of large icy moons including a subsurface ocean has gained an increasing support. The exact thickness of subsurface ocean, if present, depends on the detailed thermal evolution of each moon, and on its primordial composition. A crucial process is the heat transfer through the outer ice I layer, which controls the cooling of the satelitte interior. Convection is the most likely and efficient way to transfer heat through this layer, but the regime of convection (and therefore the heat transfer) depends on the rheology of the fluid. The viscosity of ice is strongly temperature dependent and thermal convection in the outer ice shell follows a stagnant lid regime : it means that a conductive stagnant lid forms at the top of the system, and convection is confined in a sublayer. Previous numerical studies including strongly temperature-dependent viscosities have already been performed in 2D Cartesian geometry allowing the determination of scaling laws relating the mean temperature and heat flux to the vigor of convection (described by the Rayleigh number) and the ratio of the top to the bottom viscosity, but 3D spherical geometry may provide a more accurate description of convection within the outer ice layer of icy moons. In this work, we model the heat transfer in spherical shells for a strongly temperature-dependent viscosity fluid heated from below. We use StagYY to run simulations for different ratios of the inner to outer radii of the ice layer (f), Rayleigh number (Ra), and thermal viscosity contrast (??). The inversion of the results of more than 30 numerical experiments allows the determination of scaling laws for the temperature of the well-mixed interior and surface heat flux. In particular, we find that depending on the curvature, the stagnant lid regime does not appear for the same values of the Rayleigh number and the viscosity contrast. These parameterizations, combined to mineral physics data (including melting curves of water + volatile systems), may be used to model the evolution of the radial structure and thus the cooling of icy moons.

  5. Exotic behavior of the outer shell of bimetallic nanoalloys.

    PubMed

    Delfour, L; Creuze, J; Legrand, B

    2009-11-13

    In order to build the phase diagram of Cu-Ag nanoalloys, segregation isotherms for the different sites of the outer shell of a 405-atom cluster have been obtained by means of Monte Carlo simulations using N-body interatomic potentials. A dynamical equilibrium in phase space is observed for the (001) facets as well as for the (111) facets of the truncated octahedron. For the (001) facets, the bistability originates from a structural transition, the facets oscillating collectively between a Cu-rich square shape of coordinence 4 and an Ag-rich diamond shape of coordinence 6. For the (111) facets, the bistability is purely chemical and affects each facet individually. We thus predict the possible coexistence of Cu-pure and Ag-pure (111) facets within the same nanoparticle. PMID:20365993

  6. Inner shell resonances in the outer shell photoionization of Xe@C60

    NASA Astrophysics Data System (ADS)

    Amusia, Miron; Chernysheva, Larissa

    2012-06-01

    Fullerenes C60 can be stuffed by almost all atoms A or even simple molecules. It is demonstrated by the example of the 5p-subshell of the Xe atom stuffed inside the C60 fullerene, i.e. the endohedral Xe@C60 that the so-called confinement resonances in 4d subshell strongly affect the absolute and differential in the photoelectron emission angle cross-section of 5p electrons photoionization in the region of 4d ionization threshold. It is a sort of a surprise that the narrow inner shell resonances are not smeared out in the outer shell photoionization cross-section. Inner shell resonances affect the outer cross-section by enhancing this enormously and modifying 5p dipole and non-dipole angular anisotropy parameters. Close to its own photoionization threshold, 5p photoionization cross-section of Xe@C60 is dominated by its own confinement resonances greatly enhanced by the intensity of incoming radiation due to polarization of the C60 electron shell by the incoming photon beam. In between, the 4d and 5p thresholds, the effect of 4d is becoming stronger while own resonances of 5p are becoming less and less important.

  7. Electronegativities and hardnesses of open shell atoms

    Microsoft Academic Search

    José L. Gázquez; Elba Ortiz

    1984-01-01

    A Taylor series expansion of the energy of an atomic system around the neutral atom value, which introduces the first and second derivatives of the energy with respect to the number of electrons (electronegativity ?, and hardness &eegr;, respectively) is proposed. The relaxed first derivative and the unrelaxed second derivative of the X? and hyper-Hartree–Fock methods are used to relate

  8. On convection in ice I shells of outer Solar System bodies, with detailed application to Callisto

    Microsoft Academic Search

    William B. McKinnon

    2006-01-01

    It has been argued that the dominant non-Newtonian creep mechanisms of water ice make the ice shell above Callisto's ocean, and by inference all radiogenically heated ice I shells in the outer Solar System, stable against solid-state convective overturn. Conductive heat transport and internal melting (oceans) are therefore predicted to be, or have been, widespread among midsize and larger icy

  9. Elasticity of Interfacial Rafts of Hard Particles with Soft Shells

    E-print Network

    Sebastian Knoche; Jan Kierfeld

    2015-05-10

    We study an elasticity model for compressed protein monolayers or particle rafts at a liquid interface. Based on the microscopic view of hard-core particles with soft shells, a bead-spring model is formulated and analyzed in terms of continuum elasticity theory. The theory can be applied, for example, to hydrophobin-coated air-water interfaces or, more generally, to liquid interfaces coated with an adsorbed monolayer of interacting hard-core particles. We derive constitutive relations for such particle rafts and describe the buckling of compressed planar liquid interfaces as well as their apparent Poisson ratio. We also use the constitutive relations to obtain shape equations for pendant or buoyant capsules attached to a capillary, and to compute deflated shapes of such capsules. A comparison with capsules obeying the usual Hookean elasticity (without hard cores) reveals that the hard cores trigger capsule wrinkling. Furthermore, it is shown that a shape analysis of deflated capsules with hard-core/soft-shell elasticity gives apparent elastic moduli which can be much higher than the original values if Hookean elasticity is assumed.

  10. Outer-shell double photoionization of CH2Cl2

    NASA Astrophysics Data System (ADS)

    Alcantara, K. F.; Gomes, A. H. A.; Wolff, W.; Sigaud, L.; Santos, A. C. F.

    2014-01-01

    In this work the roles of the shake-off and knockout processes in the double photoionization of the CH2Cl2 molecule have been studied. The probabilities for both mechanisms accompanying valence-shell photoionization have been estimated as a function of incident photon energy using Samson's (1990) [5] and Thomas's (1994) [3] models, respectively. The experimental results are in qualitative accord with the models.

  11. Matrix Proteins in the Outer Shells of Molluscs

    Microsoft Academic Search

    Cen Zhang; Rongqing Zhang

    2006-01-01

    The shells of molluscs are composed mainly of calcium carbonate crystals, with small amounts of matrix proteins. For more\\u000a than 50 years, they have attracted attention for their unique mechanical and biological properties. Only recently, however,\\u000a have researchers begun to realize that it is the matrix proteins that control the formation of calcium carbonate crystals\\u000a and play key roles in

  12. Modulus, Fracture Strength, and Brittle vs. Plastic Response of the Outer Shell of Arc-grown

    E-print Network

    Modulus, Fracture Strength, and Brittle vs. Plastic Response of the Outer Shell of Arc-grown Multi March 2006 /Accepted: 25 May 2006 / Published online: 1 August 2006 # Society for Experimental Mechanics The MWCNT material was acquired from MER Corporation, and was prepared by the arc-discharge method. Arc

  13. Modulus, Fracture Strength, and Brittle vs. Plastic Response of the Outer Shell of Arc-grown

    E-print Network

    Modulus, Fracture Strength, and Brittle vs. Plastic Response of the Outer Shell of Arc-grown Multi March 2006 /Accepted: 25 May 2006 / Published online: 1 August 2006 # Society for Experimental Mechanics material was acquired from MER Corporation, and was prepared by the arc-discharge method. Arc-grown MWCNTs

  14. Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

    NASA Astrophysics Data System (ADS)

    López-Ortega, Alberto; Estrader, Marta; Salazar-Alvarez, German; Roca, Alejando G.; Nogués, Josep

    2015-02-01

    The applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the core/shell structural-morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.

  15. Mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme.

    PubMed

    Foo, Jee-Loon; Jackson, Colin J; Carr, Paul D; Kim, Hye-Kyung; Schenk, Gerhard; Gahan, Lawrence R; Ollis, David L

    2010-07-15

    The metal ion co-ordination sites of many metalloproteins have been characterized by a variety of spectroscopic techniques and small-molecule model systems, revealing many important insights into the structural determinants of metal ion co-ordination. However, our understanding of this fundamentally and practically important phenomenon remains frustratingly simplistic; in many proteins it is essentially impossible to predict metal ion specificity and the effects of remote 'outer-shell' residues on metal ion co-ordination strength are also poorly defined. This is exemplified by our inability to explain why metalloenzymes with identical metal ion co-ordination spheres, such as the closely related orthologues of bacterial PTE (phosphotriesterase) from Agrobacterium radiobacter and Pseudomonas diminuta, display different metal ion specificity and co-ordination strength. In the present study, we present a series of PTE variants that all possess identical metal ion co-ordination spheres, yet display large differences in their metal ion co-ordination strength. Using measurement of the rates of metal ion dissociation from the active site alongside analysis of structural data obtained through X-ray crystallography, we show that 'outer-shell' residues provide essential support for the metal ion ligands, in effect buttressing them in their optimal orientation. Remote mutations appear to modulate metal ion interactions by increasing or decreasing the stabilizing effects of these networks. The present study therefore provides a description of how the greater protein fold can be modified to 'tune' the strength of metal ion co-ordination and metal ion specificity, as well as reinforcing the concept of proteins as ensembles of conformational states with unique structures and biochemical properties. PMID:20459397

  16. Scattering functions of core-shell-structured hard spheres with Schulz-distributed radii.

    PubMed

    Nayeri, M; Zackrisson, M; Bergenholtz, J

    2009-06-18

    The scattering intensity of polydisperse systems of core-shell and layered hard spheres is considered. The Percus-Yevick solution for the partial structure factors is cast in a form suitable for numerical and analytical treatment. Closed-form, analytical expressions are given for an effective hard-sphere model of the scattering intensity of particles with an internal layered structure and a size polydispersity governed by a Schulz distribution. A similar model for polydisperse hard spheres of core-shell structure but with a monodisperse shell thickness is also presented. The models are tested against small-angle X-ray scattering experiments on a hard-sphere-like microemulsion system. PMID:19462945

  17. The original kinematic plate tectonic model proposed that the outer shell (lithosphere) of the Earth is divided into a small

    E-print Network

    Sandwell, David T.

    The original kinematic plate tectonic model proposed that the outer shell (lithosphere driver of plate tectonics and mantle convection, but much of the energy dissipation may be in this part rele- vant to plate tectonics. Here we have compiled a series of global maps that help to confirm

  18. Triple assembly of ZnO, large-scale hollow spherical shells with flower-like species consisting of rods grown on the outer surfaces of shells

    SciTech Connect

    Shang Yazhuo; Hu Jun [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China); Liu Honglai, E-mail: yazhuoshang@ecust.edu.c [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China); Hu Ying [Key Laboratory for Advanced Materials, East China University of Science and Technology, Shanghai, 200237 (China)

    2010-03-15

    Novel large-scale hollow ZnO spherical shells were synthesized by ionic liquids assisted hydrothermal oxidization of pure zinc powder without any catalyst at a relatively low temperature of 160 deg. C. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) patterns show that the shells are composed of ZnO and the structure of the shells is very unique. Textured flower-like ZnO consisting of ZnO rods is grown on the outer surfaces of shells forming a triple assembly. Room-temperature photoluminescence spectra of the oxidized material show a sharp peak at 379 nm and a wider broad peak centered at 498 nm. The possible growth mechanism of the triple assembly of ZnO is discussed in detail. - Graphical abstract: A proposed growth mechanism of large scale hollow ZnO. Bubbles provide the aggregation center for ionic liquids that leads to the formation of hollow Zn particle-dotted shells, buoyancy promotes shells to go upward, the breach occurs when shells are subjected to overpressure.

  19. The pollen tube: a soft shell with a hard core Hannes Vogler1

    E-print Network

    Kuhlemeier, Cris

    The pollen tube: a soft shell with a hard core Hannes Vogler1 , Christian Draeger1 , Alain Weber2 in-depth knowl- edge of cell wall mechanics. Pollen tubes are tip-growing cells that provide an ideal it was not easy to measure important mechanical parameters of pollen tubes, such as the elasticity of the cell

  20. The persistence of chronically accumulated hydrocarbons in the hard shell clam Mercenaria mercenaria

    Microsoft Academic Search

    P. D. Boehm; J. G. Quinn

    1977-01-01

    Hard shell clams, Mercenaria mercenaria, from the chronically polluted environment of the Providence River, USA, were transferred to a clean laboratory system located in lower Narragansett Bay, Rhode Island. The hydrocarbon contents of these transplanted clams were monitored for 120 days after transfer. After this period only slight depuration had occurred. A 41.9 µg g wet weight-1 average initial hydrocarbon

  1. Soft and hard shells in metallic nanocrystals D. Y. Sun,1,2

    E-print Network

    Gong, Xingao

    Soft and hard shells in metallic nanocrystals D. Y. Sun,1,2 X. G. Gong,1,2 and Xiao-Qian Wang2 1 nanocrystals are studied using semiempirical potentials for Au, Pb, Ag, and Cu. The enhanced low- and high s : 61.82.Rx, 68.35.Ja Unusual physical and chemical properties of nanocrystals are associated

  2. Studies on applicability of press-coated tablets using hydroxypropylcellulose (HPC) in the outer shell for timed-release preparations

    Microsoft Academic Search

    Eiji Fukui; Katsuji Uemura; Masao Kobayashi

    2000-01-01

    Press-coated tablets, containing diltiazem hydrochloride (DIL) in the core tablet and coated with hydroxypropylcellulose (HPC) as the outer shell, were examined for applicability as timed-release tablets with a predetermined lag time and subsequent rapid drug release phase. Various types of press-coated tablets were prepared using a rotary tabletting machine and their DIL dissolution behavior was evaluated by the JP paddle

  3. Outer electrospun polycaprolactone shell induces massive foreign body reaction and impairs axonal regeneration through 3D multichannel chitosan nerve guides.

    PubMed

    Duda, Sven; Dreyer, Lutz; Behrens, Peter; Wienecke, Soenke; Chakradeo, Tanmay; Glasmacher, Birgit; Haastert-Talini, Kirsten

    2014-01-01

    We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10 mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts. PMID:24818158

  4. Outer Electrospun Polycaprolactone Shell Induces Massive Foreign Body Reaction and Impairs Axonal Regeneration through 3D Multichannel Chitosan Nerve Guides

    PubMed Central

    Behrens, Peter; Wienecke, Soenke; Chakradeo, Tanmay; Glasmacher, Birgit

    2014-01-01

    We report on the performance of composite nerve grafts with an inner 3D multichannel porous chitosan core and an outer electrospun polycaprolactone shell. The inner chitosan core provided multiple guidance channels for regrowing axons. To analyze the in vivo properties of the bare chitosan cores, we separately implanted them into an epineural sheath. The effects of both graft types on structural and functional regeneration across a 10?mm rat sciatic nerve gap were compared to autologous nerve transplantation (ANT). The mechanical biomaterial properties and the immunological impact of the grafts were assessed with histological techniques before and after transplantation in vivo. Furthermore during a 13-week examination period functional tests and electrophysiological recordings were performed and supplemented by nerve morphometry. The sheathing of the chitosan core with a polycaprolactone shell induced massive foreign body reaction and impairment of nerve regeneration. Although the isolated novel chitosan core did allow regeneration of axons in a similar size distribution as the ANT, the ANT was superior in terms of functional regeneration. We conclude that an outer polycaprolactone shell should not be used for the purpose of bioartificial nerve grafting, while 3D multichannel porous chitosan cores could be candidate scaffolds for structured nerve grafts. PMID:24818158

  5. Building nanocomposite magnets by coating a hard magnetic core with a soft magnetic shell.

    PubMed

    Liu, Fei; Zhu, Jinghan; Yang, Wenlong; Dong, Yunhe; Hou, Yanglong; Zhang, Chenzhen; Yin, Han; Sun, Shouheng

    2014-02-17

    Controlling exchange coupling between hard magnetic and soft magnetic phases is the key to the fabrication of advanced magnets with tunable magnetism and high energy density. Using FePt as an example, control over the magnetism in exchange-coupled nanocomposites of hard magnetic face-centered tetragonal (fct) FePt and soft magnetic Co (or Ni, Fe2C) is shown. The dispersible hard magnetic fct-FePt nanoparticles are first prepared with their coercivity (Hc) reaching 33?kOe. Then core/shell fct-FePt/Co (or Ni, Fe2C) nanoparticles are synthesized by reductive thermal decomposition of the proper metal precursors in the presence of fct-FePt nanoparticles. These core/shell nanoparticles are strongly coupled by exchange interactions and their magnetic properties can be rationally tuned by the shell thickness of the soft phase. This work provides an ideal model system for the study of exchange coupling at the nanoscale, which will be essential for building superstrong magnets for various permanent magnet applications in the future. PMID:24453167

  6. Equatorial symmetry of Boussinesq convective solutions in a rotating spherical shell allowing rotation of the inner and outer spheres

    SciTech Connect

    Kimura, Keiji; Takehiro, Shin-ichi; Yamada, Michio [Research Institute for Mathematical Sciences, Kyoto University, Kyoto 606-8502 (Japan)

    2014-08-15

    We investigate properties of convective solutions of the Boussinesq thermal convection in a moderately rotating spherical shell allowing the respective rotation of the inner and outer spheres due to the viscous torque of the fluid. The ratio of the inner and outer radii of the spheres, the Prandtl number, and the Taylor number are fixed to 0.4, 1, and 500{sup 2}, respectively. The Rayleigh number is varied from 2.6 × 10{sup 4} to 3.4 × 10{sup 4}. In this parameter range, the behaviours of obtained asymptotic convective solutions are almost similar to those in the system whose inner and outer spheres are restricted to rotate with the same constant angular velocity, although the difference is found in the transition process to chaotic solutions. The convective solution changes from an equatorially symmetric quasi-periodic one to an equatorially symmetric chaotic one, and further to an equatorially asymmetric chaotic one, as the Rayleigh number is increased. This is in contrast to the transition in the system whose inner and outer spheres are assumed to rotate with the same constant angular velocity, where the convective solution changes from an equatorially symmetric quasi-periodic one, to an equatorially asymmetric quasi-periodic one, and to equatorially asymmetric chaotic one. The inner sphere rotates in the retrograde direction on average in the parameter range; however, it sometimes undergoes the prograde rotation when the convective solution becomes chaotic.

  7. Effects of an outer stably stratified layer on equatorial surface flows induced by thermal convection in a rotating spherical shell

    NASA Astrophysics Data System (ADS)

    Takehiro, S.; Yamada, M.; Hayashi, Y.

    2011-12-01

    In order to explain the equatorial superrotation states observed in Jupiter, Saturn and the sun, possible roles of thermal convection in rotating spherical shells have been investigated. Most of the studies on thermal convection in rotating spherical shells consider situations in which the entire layer is thermally unstable. However, the actual planetary atmospheres may not consist of entirely unstable layers. There exist stable stratospheres and possibly moderately stable cloud layers. Below the cloud layer, the Galileo spacecraft observed a stable layer between depths of 5 and 16 bars in the Jovian atmosphere. If such a stable layer exists near the outer boundary, the generation of surface prograde mean zonal flows caused by the angular momentum transport due to the tilting of columnar convection cells might not operate. Therefore, in the present study, we perform systematic numerical experiments of finite amplitude thermal convection in a rotating spherical shell with an outer stably stratified layer. The Ekman number, the Prandtl number, and the inner/outer radius ratio of the shell are fixed to 10-3, 1, and 0.4, respectively. The Rayleigh number is varied from a few times to approximately forty times the critical value. The temperature gradient in the stable layer is increased from 1 to 104 times that of the inner unstable layer. The conditions at the boundaries are free-slip and fixed temperature. The time integrations are started from the state of rest accompanied by a point-like temperature disturbance, and continue until the kinetic energy becomes almost stationary. The results show that the existence of a strongly stratified upper layer enhances the generation of equatorial surface retrograde flows when he Rayleigh number is approximately ten times larger than the critical value. These retrograde flows are not associated with the homogenization of angular momentum. It could be explained by change of an effective outer boundary condition operating on the convective motion in the inner layer. The existence of the stable layer causes the bottom of the stable layer to behave as a virtual boundary for the convective motion underneath. Its effective dynamic condition varies from the free-slip condition to the no-slip condition as the Rayleigh number increases. The Reynolds stress of the convective vortices beneath the stable layer is weakened and is dominated by the transport of the planetary angular momentum. As a result, the latitudinal temperature gradient produced at the bottom of the stable layer induces the equatorial retrograde flow. This diffuses through the stable layer by viscosity and produces the equatorial surface retrograde flow.

  8. Collision safety of a hard-shell low-mass vehicle

    SciTech Connect

    Kaeser, R.; Walz, F.H.; Brunner, A.

    1994-06-01

    Low-mass vehicles and in particular low-mass electric vehicles as produced today in very small quantities are in general not designed for crashworthiness in collisions. Particular problems of compact low-mass cars are: reduced length of the car front, low mass compared to other vehicles, and heavy batteries in the case of an electric car. With the intention of studying design improvements, three frontal crash tests were run last year: the first one with a commercial, lightweight electric car; the second with a reinforced version of the same car; and the last one with a car based on a different structural design with a `hard-shell` car body. Crash tests showed that the latter solution made better use of the small zone available for continuous energy absorption. The paper discusses further the problem of frontal collisions between vehicles of different weight and, in particular, the side collision. A side-collision test was run with the hard-shell vehicle following the ECE lateral-impact test procedure at 50 km/h and led to results for the EuroSIDI-dummy well below current injury tolerance criteria.

  9. Environmental salinity modulates the effects of elevated CO2 levels on juvenile hard-shell clams, Mercenaria mercenaria.

    PubMed

    Dickinson, Gary H; Matoo, Omera B; Tourek, Robert T; Sokolova, Inna M; Beniash, Elia

    2013-07-15

    Ocean acidification due to increasing atmospheric CO2 concentrations results in a decrease in seawater pH and shifts in the carbonate chemistry that can negatively affect marine organisms. Marine bivalves such as the hard-shell clam, Mercenaria mercenaria, serve as ecosystem engineers in estuaries and coastal zones of the western Atlantic and, as for many marine calcifiers, are sensitive to the impacts of ocean acidification. In estuaries, the effects of ocean acidification can be exacerbated by low buffering capacity of brackish waters, acidic inputs from freshwaters and land, and/or the negative effects of salinity on the physiology of organisms. We determined the interactive effects of 21 weeks of exposure to different levels of CO2 (~395, 800 and 1500 ?atm corresponding to pH of 8.2, 8.1 and 7.7, respectively) and salinity (32 versus 16) on biomineralization, shell properties and energy metabolism of juvenile hard-shell clams. Low salinity had profound effects on survival, energy metabolism and biomineralization of hard-shell clams and modulated their responses to elevated PCO2. Negative effects of low salinity in juvenile clams were mostly due to the strongly elevated basal energy demand, indicating energy deficiency, that led to reduced growth, elevated mortality and impaired shell maintenance (evidenced by the extensive damage to the periostracum). The effects of elevated PCO2 on physiology and biomineralization of hard-shell clams were more complex. Elevated PCO2 (~800-1500 ?atm) had no significant effects on standard metabolic rates (indicative of the basal energy demand), but affected growth and shell mechanical properties in juvenile clams. Moderate hypercapnia (~800 ?atm PCO2) increased shell and tissue growth and reduced mortality of juvenile clams in high salinity exposures; however, these effects were abolished under the low salinity conditions or at high PCO2 (~1500 ?atm). Mechanical properties of the shell (measured as microhardness and fracture toughness of the shells) were negatively affected by elevated CO2 alone or in combination with low salinity, which may have important implications for protection against predators or environmental stressors. Our data indicate that environmental salinity can strongly modulate responses to ocean acidification in hard-shell clams and thus should be taken into account when predicting the effects of ocean acidification on estuarine bivalves. PMID:23531824

  10. A Detailed Kinematic Map of Cassiopeia A's Optical Main Shell and Outer High-velocity Ejecta

    NASA Astrophysics Data System (ADS)

    Milisavljevic, Dan; Fesen, Robert A.

    2013-08-01

    We present three-dimensional (3D) kinematic reconstructions of optically emitting material in the young Galactic supernova remnant Cassiopeia A (Cas A). These Doppler maps have the highest spectral and spatial resolutions of any previous survey of Cas A and represent the most complete catalog of its optically emitting material to date. We confirm that the bulk of Cas A's optically bright ejecta populate a torus-like geometry tilted approximately 30° with respect to the plane of the sky with a -4000 to +6000 km s-1 radial velocity asymmetry. Near-tangent viewing angle effects and an inhomogeneous surrounding circumstellar material/interstellar medium environment suggest that this geometry and velocity asymmetry may not be faithfully representative of the remnant's true 3D structure or the kinematic properties of the original explosion. The majority of the optical ejecta are arranged in several well-defined and nearly circular ring-like structures with diameters between approximately 30'' (0.5 pc) and 2' (2 pc). These ejecta rings appear to be a common phenomenon of young core-collapse remnants and may be associated with post-explosion input of energy from plumes of radioactive 56Ni-rich ejecta that rise, expand, and compress non-radioactive material. Our optical survey encompasses Cas A's faint outlying ejecta knots and exceptionally high-velocity NE and SW streams of S-rich debris often referred to as "jets." These outer knots, which exhibit a chemical make-up suggestive of an origin deep within the progenitor star, appear to be arranged in opposing and wide-angle outflows with opening half-angles of ?40°.

  11. Dynamical behavior caused by numerical dynamo simulations in a rotating spherical shell with the heterogeneous outer boundary

    NASA Astrophysics Data System (ADS)

    Nakagawa, T.; Aubert, J.

    2013-12-01

    We use numerical dynamo simulations in a rotating spherical shell to investigate the thermal structure in the core influenced by the heterogeneous top boundary. The experimental study in a rotating hemispherical shell with huge anomalous heterogeneous outer boundary suggested that the ';front' structure caused by huge amplitude of thermal anomalies at the top boundary but not checked in the various dynamo regimes [Sumita and Olson, 2002], which predicted that the major physical mechanism for the ';front' structure could be understood by the thermal wind balance. Aurnou and Aubert [2011] suggested that there would be several regimes when the heterogeneous condition at the top boundary was imposed in numerical dynamo simulations but not investigated thermal structure in the core to check the experimental consequences as well as the regime transition between convective and boundary modulated dynamo regimes. Here we use two Ekman number (10^-4 and 3x10^-5) and fixed magnetic and thermal Prandtl number (the unity) with varying various Rayleigh number defined the amplitude of lateral variation of heat flux across the top boundary. The pattern of heterogeneous boundary condition is used as (l,m)=(2,2). The two or more ';fronts' are found in imposed heterogeneous boundary at least. These fronts are very small time-dependence for their positions with large lateral temperature variations near fronts. This means that the ';front' structure could be found in the MHD dynamo system as well as non-magnetic cases shown in Sumita and Olson [2002] because the Lorentz force contribution to thermal wind balance seems to be very weak compared to the buoyancy flux to balance the Coriolis effect. More information will be provided in the presentation.

  12. Immunocytochemistry suggests that the prevalence of a sub-type of beta-proteins determines the hardness in the epidermis of the hard-shelled turtle.

    PubMed

    Alibardi, Lorenzo

    2014-01-01

    The corneous layer of the epidermis in hard-shelled turtles largely derives from the accumulation of beta-proteins as indicated by microscopic, in situ hybridization, and immunocytochemical and Western blotting analysis. The expression of mRNAs of one of the most common type of beta-proteins shows higher expression in upper spinosus and pre-corneous keratinocytes of growing scutes. Two beta-proteins of 14-16?kDa, indicated as Tu2 and Tu17 and representing two subtypes of beta-proteins co-accumulate in the thick corneous layer of the epidermis in hard-shelled turtle. The two beta-proteins apparently mix in differentiating and mature corneocytes although Tu2 appears more prevalent than Tu17. The specific role of the different subtypes in the formation of the hard corneous material of the carapace and plastron is not clear. It is hypothesized that the relative amount of beta-proteins belonging to the two subclasses in relation to the alpha-keratin meshwork present in keratinocytes contributes to the formation of a variably resistant and inflexible corneous layer. Tu17 may have a more globular structure than Tu2 and is likely present in denser areas of the corneous layer containing also alpha-keratin. The increase of cysteine-glycine-rich beta-proteins in the matrix located among alpha-keratin filaments may allow the formation of a hard corneous material, probably through increase of cross-bridge formation and hydrophobicity. PMID:24254963

  13. Bubble generation and venous air filtration by hard-shell venous reservoirs: a comparative study.

    PubMed

    Mitchell, S J; Willcox, T; Gorman, D F

    1997-09-01

    We have previously shown significant bubble formation in Medtronic Maxima hard-shell venous reservoirs (HSVRs). In the present study, we not only investigated the mechanism of this bubble formation, but also the extent of bubble clearance by membrane oxygenators and arterial line filters. In addition, we also compared the performance of five HSVRs with respect to bubble formation and venous air filtration. Salvaged clinical CPB circuits containing different HSVRs were studied by downstream Doppler monitoring under fixed flow-decreasing volume, fixed volume-increasing flow, and entrained venous air conditions. Bubbles formed in the Medtronic Maxima top entry HSVR at volumes below 800 ml and flows above 3.5 l min-1, and were incompletely removed by a membrane oxygenator and arterial line filter. Decreased bubbling was seen when the reservoir atmosphere was flushed with CO2, suggesting that these bubbles formed in a fountain at the venous inflow. The Medtronic Maxima Forte HSVR formed significantly fewer bubbles at low volumes, and filtered venous air effectively. Negligible bubble formation occurred in the Sorin, Terumo, or Baxter reservoirs. The minimum recommended operating volume for the Medtronic Maxima top entry reservoir should be reset at 600 ml and this device should always be used with an arterial filter. Bubble formation is substantially reduced in the new Medtronic Maxima Forte HSVR and this device is a good filter for venous air. PMID:9300478

  14. The Effect of Diet on Weight Gain, Shell Hardness, and Flavor of New-Shell American Lobster, Homarus americanus

    Microsoft Academic Search

    Darrell W. Donahue; Robert C. Bayer; Therese M. Work; John G. Riley

    1997-01-01

    Harvested newly-shed American lobsters, Homants americanus, placed in pounds for long-term storage are prone to damage resulting from high-density confinement. It is beneficial for the new shell to harden as soon as possible after shedding. Artificial diets offer the potential for adding supplements to increase weight, muscle gain, and shell hardening. In this study, lobsters were fed 5 different diets:

  15. Effect of gamma irradiation on shelf life and bacterial and viral loads in hard-shelled clams (Mercenaria mercenaria).

    PubMed Central

    Harewood, P; Rippey, S; Montesalvo, M

    1994-01-01

    The feasibility of using 60Co gamma irradiation to inactivate total coliforms, fecal coliforms, Escherichia coli, Clostridium perfringens, and F-coliphage in hard-shelled clams, Mercenaria mercenaria, was investigated. The results of three trials indicated average D10 values of 1.32 kGy for total coliforms, 1.39 kGy for fecal coliforms, 1.54 kGy for E. coli, 2.71 kGy for C. perfringens, and 13.50 kGy for F-coliphage. Irradiation doses of > 0.5 kGy were significantly lethal to the shellfish. PMID:8074539

  16. Stratigraphy and paleoenvironments of the Shell 410-1 well, Georges Bank Basin, US North Atlantic outer continental shelf

    USGS Publications Warehouse

    Poppe, L.J.; Poag, C.W.; Swift, B.A.

    1995-01-01

    The Shell 410-1 well is the most downdip (seaward) hydrocarbon exploratory well in the Georges Bank Basin. It was drilled to a total depth of 4745 m RKB, and penetrated a section composed of Middle Jurassic to Quaternary sedimentary rocks. The lithostratigraphy of the section is described. The strata penetrated by the Shell 410-1 well are more marine than rocks at the updip (landward) COST G-1, Exxon 975-1, COST G-2, and Conoco 145-1 well sites. Limestones and calcareous mudstones dominate at the Shell 410-1 site. Dolomite and anhydrite are much more abundant in the Bajocian-Callovian strata of the Shell 410-1 well, which is evidence that the carbonate-bank palaeoenvironments recorded in the Iroquois and Abenaki Formations were more restricted (less marine) here than 47 km to the west-northwest at the Mobil 312-1 well site near the edge of the Jurassic carbonate platform. -from Authors

  17. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...FRUITS, VEGETABLES AND OTHER PRODUCTS 1,2 (INSPECTION, CERTIFICATION, AND STANDARDS) United States Standards for Shelled English Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody...

  18. A simplified analytical expression for the first shell of the hard-sphere fluid radial distribution function

    Microsoft Academic Search

    J. Largo; J. R. Solana

    2000-01-01

    An analytical expression for the first coordination cell of the radial distribution function (RDF) of the hard-sphere fluid is derived. It is based on a series expansion of the analytical expression of the Percus–Yevick solution of the RDF of the hard-sphere fluid derived by Chang and Sandler [J. Chang, S.I. Sandler, Mol. Phys. 81 (1994) 745.]. The expansion is carried

  19. Ocean acidification alters the material properties of Mytilus edulis shells.

    PubMed

    Fitzer, Susan C; Zhu, Wenzhong; Tanner, K Elizabeth; Phoenix, Vernon R; Kamenos, Nicholas A; Cusack, Maggie

    2015-02-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  20. Thermally activated coercivity in core-shell permanent magnets

    NASA Astrophysics Data System (ADS)

    Bance, S.; Fischbacher, J.; Schrefl, T.

    2015-05-01

    Finite element micromagnetic simulations are used to compute the temperature-dependent hysteresis properties of Nd2Fe14B permanent magnets in order to assess the influence of a hard (Dy,Nd)2Fe14B shell. The simulations show that the 4 nm thick shell cancels out the reduction in coercivity from an outer defect layer, which is known to exist at the grain boundaries in NdFeB permanent magnets. Activation volumes are computed and shown to depend on the structure's configuration as well as the temperature.

  1. Material with core-shell structure

    DOEpatents

    Luhrs, Claudia (Rio Rancho, NM); Richard, Monique N. (Ann Arbor, MI); Dehne, Aaron (Maumee, OH); Phillips, Jonathan (Rio Rancho, NM); Stamm, Kimber L. (Ann Arbor, MI); Fanson, Paul T. (Brighton, MI)

    2011-11-15

    Disclosed is a material having a composite particle, the composite particle including an outer shell and a core. The core is made from a lithium alloying material and the outer shell has an inner volume that is greater in size than the core of the lithium alloying material. In some instances, the outer mean diameter of the outer shell is less than 500 nanometers and the core occupies between 5 and 99% of the inner volume. In addition, the outer shell can have an average wall thickness of less than 100 nanometers.

  2. Lipid Extract from Hard-Shelled Mussel (Mytilus coruscus) Improves Clinical Conditions of Patients with Rheumatoid Arthritis: A Randomized Controlled Trial

    PubMed Central

    Fu, Yuanqing; Li, Guipu; Zhang, Xinhua; Xing, Gengyan; Hu, Xiaojie; Yang, Lifeng; Li, Duo

    2015-01-01

    Studies have suggested a lipid extract from hard-shelled mussel (Mytilus coruscus) (HMLE) possessed strong anti-inflammatory activity in arthritis model of rats. This study investigated whether HMLE could improve clinical conditions of rheumatoid arthritis patients. Fifty rheumatoid arthritis patients (28–75 years) were randomly assigned to receive HMLE capsules or receive placebo capsules for 6 months. Forty-two subjects and 50 subjects were included in per-protocol and intention-to-treat analysis, respectively. Significant differences in changes on disease activity score (DAS28) and clinical disease activity index (CDAI) after 6-month intervention (p < 0.01) were observed in both analyses with more evident efficacy shown in per-protocol population (?DAS28 = 0.47; ?CDAI = 4.17), which favored the benefits of the HMLE group. TNF-? (tumor necrosis factor ?), interleukin (IL)-1? and PGE2 (prostaglandin E2) but not IL-6, were significantly decreased in both groups, and the decrements were much larger in the HMLE group for TNF-? and PGE2 after 6 months from baseline (p < 0.05). IL-10 was significantly increased in both groups and the change was much more evident in the HMLE group (p < 0.05). In conclusion, HMLE exhibited benefits for the clinical conditions of rheumatoid patients in relation to improvement in the balance between pro- and anti-inflammatory factors, which indicated its potential to serve as adjunctive treatment for rheumatoid arthritis. (ClinicalTrials.gov NCT02173587). PMID:25602164

  3. Outer-shell photodetachment of the metastable Be{sup -} 1s{sup 2}2s2p{sup 2} {sup 4}P{sup e} state

    SciTech Connect

    Sanz-Vicario, Jose Luis; Lindroth, Eva [GFAM, Instituto de Fisica, Universidad de Antioquia, Calle 67 No. 53-108, AA 1226, Medellin, (Colombia); Atomic Physics, Stockholms Centrum Foer Fysik, Astronomi och Bioteknik (SCFAB), Stockholm University, S-106 91 Stockholm, (Sweden)

    2003-07-01

    We report calculated photodetachment cross sections from the metastable Be{sup -} 1s{sup 2}2s2p{sup 2} {sup 4}P{sup e} state in the photon energy range 0-10 eV. Outer-shell photodetachment takes place in this energy range, which includes the double-ionization threshold Be{sup +}({sup 2}S{sup e}) at {approx}7 eV as well as doubly excited thresholds of the residual atom up to the Be(1s{sup 2}2p4f) threshold at {approx}10 eV. Therefore, triply excited states of Be{sup -} are reached within the selected photon energy. We have implemented the complex scaled configuration interaction method along with a model potential for the 1s{sup 2} core to uncover the first series of Be{sup -} {sup 4}L{sup o} resonant states. In this work, four {sup 4}P{sup o}, seven {sup 4}D{sup o}, and two {sup 4}S{sup o} resonances are reported and we compare our cross section with other previous theoretical calculations, that reported none or, at most, two resonances.

  4. 46 CFR 154.170 - Outer hull steel plating.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Outer hull steel plating. 154.170 Section 154.170 Shipping...Structure § 154.170 Outer hull steel plating. (a) Except as required in paragraph...of this section, the outer hull steel plating, including the shell and deck...

  5. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 2 2014-01-01 2014-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations...Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition...

  6. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Agriculture 2 2011-01-01 2011-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations...Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition...

  7. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 2 2013-01-01 2013-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations...Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition...

  8. 7 CFR 51.2289 - Shell.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 2 2012-01-01 2012-01-01 false Shell. 51.2289 Section 51.2289 Agriculture Regulations...Walnuts (Juglans Regia) Definitions § 51.2289 Shell. Shell means the outer shell and/or the woody partition...

  9. Shell forming system

    NASA Technical Reports Server (NTRS)

    Kendall, Jr., James M. (Inventor); Wang, Taylor G. (Inventor); Elleman, Daniel D. (Inventor)

    1990-01-01

    Hollow shells of high uniformity are formed by emitting liquid through an outer nozzle and gas through an inner nozzle, to form a hollow extrusion, by flowing the gas at a velocity between about 1.3 and 10 times the liquid velocity. The natural breakup rate of the extrusion can be increased to decrease shell size by applying periodic perturbations to one of the materials prior to exiting the nozzles, to a nozzle, or to the extrusion.

  10. Optimum rotationally symmetric shells for flywheel rotors

    DOEpatents

    Blake, Henry W. (Oak Ridge, TN)

    2000-01-01

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  11. Optimum rotationally symmetric shells for flywheel rotors

    SciTech Connect

    Blake, H.W.

    2000-04-04

    A flywheel rim support formed from two shell halves. Each of the shell halves has a disc connected to the central shaft. A first shell element connects to the disc at an interface. A second shell element connects to the first shell element. The second shell element has a plurality of meridional slits. A cylindrical shell element connects to the second shell element. The cylindrical shell element connects to the inner surface of the flywheel rim. A flywheel rim support having a disc connected an outer diameter of a shaft. Two optimally shaped shell elements connect to the optimally shaped disc at an interface. The interface defines a discontinuity in a meridional slope of said support. A cylindrical shell element connects to the two shell elements. The cylindrical shell element has an outer surface for connecting to the inner surface of the flywheel rim. A flywheel rim casing includes an annular shell connected to the central shaft. The annular shell connects to the flywheel rim. A composite shell surrounds the shaft, annular shell and flywheel rim.

  12. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, Charles D. (Livermore, CA)

    1985-01-01

    Large, uniform hollow spherical shells are produced by forming uniform size drops of heat decomposable or vaporizable material, evaporating the drops to form dried particles, coating the dried particles with a layer of shell forming material, and heating the composite particles to melt the outer layer and decompose or vaporize the inner particle to form an expanding inner gas bubble which expands the outer layer. By cycling the temperature and pressure on the hollow shells, spherical shells with uniform walls are produced.

  13. 75 FR 54369 - BOEMRE Information Collection Activity: 1010-NEW, Upcoming Projects Considering the Use of Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-07

    ...Outer Continental Shelf Sand, Gravel, and Shell Resources for Coastal Restoration and...BOEMRE to obtain OCS sand, gravel, and shell resources for use in shore protection and...procedures for obtaining sand, gravel, and shell resources can be found on the BOEMRE...

  14. Outer Planet Flagship Mission

    Microsoft Academic Search

    James Cutts; C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton

    2008-01-01

    Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEm and LaPlace, which focused on

  15. Outer Planet Flagship Missions

    Microsoft Academic Search

    C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton; J. A. Cutts

    2008-01-01

    Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEM and LaPlace, which focused on

  16. Fragmentation of Shells

    NASA Astrophysics Data System (ADS)

    Wittel, F.; Kun, F.; Herrmann, H. J.; Kröplin, B. H.

    2004-07-01

    We present a theoretical and experimental study of the fragmentation of closed thin shells made of a disordered brittle material. Experiments were performed on brown and white hen egg shells under two different loading conditions: impact with a hard wall and explosion by a combustible mixture. Both give rise to power law fragment size distributions. A three-dimensional discrete element model of shells is worked out. Based on simulations of the model, we give evidence that power law fragment mass distributions arise due to an underlying phase transition which proved to be abrupt for explosion and continuous for impact. We demonstrate that the fragmentation of closed shells defines a new universality class of fragmentation phenomena.

  17. Diffusion, sedimentation, and rheology of concentrated suspensions of core-shell particles

    NASA Astrophysics Data System (ADS)

    Abade, Gustavo C.; Cichocki, Bogdan; Ekiel-Je?ewska, Maria L.; Nägele, Gerhard; Wajnryb, Eligiusz

    2012-03-01

    Short-time dynamic properties of concentrated suspensions of colloidal core-shell particles are studied using a precise force multipole method which accounts for many-particle hydrodynamic interactions. A core-shell particle is composed of a rigid, spherical dry core of radius a surrounded by a uniformly permeable shell of outer radius b and hydrodynamic penetration depth ?-1. The solvent flow inside the permeable shell is described by the Brinkman-Debye-Bueche equation, and outside the particles by the Stokes equation. The particles are assumed to interact non-hydrodynamically by a hard-sphere no-overlap potential of radius b. Numerical results are presented for the high-frequency shear viscosity, ??, sedimentation coefficient, K, and the short-time translational and rotational self-diffusion coefficients, Dt and Dr. The simulation results cover the full three-parametric fluid-phase space of the composite particle model, with the volume fraction extending up to 0.45, and the whole range of values for ?b, and a/b. Many-particle hydrodynamic interaction effects on the transport properties are explored, and the hydrodynamic influence of the core in concentrated systems is discussed. Our simulation results show that for thin or hardly permeable shells, the core-shell systems can be approximated neither by no-shell nor by no-core models. However, one of our findings is that for ?(b - a) ? 5, the core is practically not sensed any more by the weakly penetrating fluid. This result is explained using an asymptotic analysis of the scattering coefficients entering into the multipole method of solving the Stokes equations. We show that in most cases, the influence of the core grows only weakly with increasing concentration.

  18. Different shells

    NSDL National Science Digital Library

    N/A N/A (None; )

    2007-08-22

    Snails can live in many different shells. The shells can be large or small, depending on the size of the snail and what kind it is. The shell can also be of a variety of colors. Other animals can also live in shells.

  19. Outer planet satellites

    SciTech Connect

    Schenk, P.M. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon. 210 refs.

  20. Method of fabricating nested shells and resulting product

    DOEpatents

    Henderson, Timothy M. (Ann Arbor, MI); Kool, Lawrence B. (Ann Arbor, MI)

    1982-01-01

    A multiple shell structure and a method of manufacturing such structure wherein a hollow glass microsphere is surface treated in an organosilane solution so as to render the shell outer surface hydrophobic. The surface treated glass shell is then suspended in the oil phase of an oil-aqueous phase dispersion. The oil phase includes an organic film-forming monomer, a polymerization initiator and a blowing agent. A polymeric film forms at each phase boundary of the dispersion and is then expanded in a blowing operation so as to form an outer homogeneously integral monocellular substantially spherical thermoplastic shell encapsulating an inner glass shell of lesser diameter.

  1. DIFFUSION OF PROTONS IN THE OUTER RADIATION BELT

    Microsoft Academic Search

    M. P. Nakada; G. D. Mead

    1965-01-01

    The diffusion of protons in the outer radiation belt due to violation of the third adiabatic invariant has been examined. The particular mechanism studied is one in which variations in the intensity of the solar wind produce magnetic disturbances causing motion of particles between L shells. A Fokker-Planck diffusion equation is used with terms describing Coulomb energy degradation and charge-exchange

  2. 34Modeling a Planetary Nebula Planetary nebula are the outer

    E-print Network

    34Modeling a Planetary Nebula Planetary nebula are the outer atmospheres of dying stars ejected into space. Astronomers model these nebulae to learn about the total mass they contain, and the details of how they were ejected. The image is of a rare, spherical-shell planetary nebula, Abell 38

  3. Shell rendering

    Microsoft Academic Search

    Jayaram K. Udupa; Dewey Odhner

    1993-01-01

    A structure model for volume rendering, called a shell, is introduced. Roughly, a shell consists of a set of voxels in the vicinity of the structure boundary together with a number of attributes associated with the voxels in this set. By carefully choosing the attributes and storing the shell in a special data structure that allows random access to the

  4. Law in Outer Space.

    ERIC Educational Resources Information Center

    Schmidt, William G.

    1997-01-01

    Provides an overview of the current practice and fascinating future of legal issues involved in outer space exploration and colonization. Current space law, by necessity, addresses broad principles rather than specific incidents. Nonetheless, it covers a variety of issues including commercial development, rescue agreements, object registration,…

  5. Mining outer space

    Microsoft Academic Search

    M. J. Gaffey; T. B. McCord

    1977-01-01

    The need to develop new mineral resources as terrestrial supplies are depleted could lead to mining efforts in outer space, where other bodies can be found with materials similar to those of the earth. The high cost of direct sampling requires that earth-based observations be made first, followed by unmanned flights and landing missions. The surface composition of over 100

  6. Two-frequency shell-model calculations for p-shell nuclei

    Microsoft Academic Search

    L. Coraggio; A. Covello; A. Gargano; N. Itaco; T. T. S. Kuo

    2001-01-01

    We have studied p-shell nuclei using a two-frequency shell-model approach with an effective interaction derived from the Bonn-A nucleon-nucleon potential by means of a G-matrix folded-diagram method. Shell-model wavefunctions of two different oscillator constants, &plank;omegain and &plank;omegaout, are employed, one for the inner 0s core orbit and the other for the outer valence orbits, respectively. The binding energies, energy spectra

  7. Role of shell crossing on the existence and stability of trapped matter shells in spherical inhomogeneous {Lambda}-CDM models

    SciTech Connect

    Le Delliou, Morgan; Mena, Filipe C.; Mimoso, Jose P. [Instituto de Fisica Teorica UAM/CSIC, Facultad de Ciencias, C-XI, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Centro de Matematica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Departamento de Fisica, Faculdade de Ciencias da Universidade de Lisboa, Centro de Astronomia e Astrofisica, Universidade de Lisboa, Campo Grande, Edificio C8 P-1749-016, Lisboa (Portugal)

    2011-05-15

    We analyze the dynamics of trapped matter shells in spherically symmetric inhomogeneous {Lambda}-CDM models. The investigation uses a generalized Lemaitre-Tolman-Bondi description with initial conditions subject to the constraints of having spatially asymptotic cosmological expansion, initial Hubble-type flow, and a regular initial density distribution. We discuss the effects of shell crossing and use a qualitative description of the local trapped matter shells to explore global properties of the models. Once shell crossing occurs, we find a splitting of the global shells separating expansion from collapse into, at most, two global shells: an inner and an outer limit trapped matter shell. In the case of expanding models, the outer limit trapped matter shell necessarily exists. We also study the role of shear in this process, compare our analysis with the Newtonian framework, and give concrete examples using density profile models of structure formation in cosmology.

  8. Interior remodeling of the shell by a gastropod mollusc

    PubMed Central

    Kohn, Alan J.; Myers, Elizabeth R.; Meenakshi, V. R.

    1979-01-01

    As the Conus shell grows by spiraling of the outer lip around the axis, profound internal shell dissolution thins the walls of the protected penultimate whorl from several millimeters to <50?m. Shell material is added to the inside of the spire and the anterior part of the columella. The resulting shell has a uniformly thick last whorl and thickened spire that enhance defense against crushing predators and a greatly expanded interior living space for the animal. Images PMID:16592680

  9. 75 FR 3915 - Environmental Documents Prepared in Support of Sand and Gravel Activities on the Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-25

    ...Environmental Documents Prepared in Support of Sand and Gravel Activities on the Outer Continental...prepared and/or adopted by the MMS for three sand and gravel activities proposed on the Outer...noncompetitive basis, the rights to OCS sand, gravel, or shell resources for...

  10. INNER-SHELL SPECTROSCOPY (ISS) BEAMLINE CHARACTERISTICS

    E-print Network

    Ohta, Shigemi

    INNER-SHELL SPECTROSCOPY (ISS) BEAMLINE CHARACTERISTICS Understand the interaction of Hg: Construction AVAILABLE TO USERS: Fall 2016 Inner Shell Spectroscopy (ISS) is a damping wiggler beamline soft X-ray spectroscopy. Since a hard X-ray probe is used, XELS is compatible with many in situ sample

  11. Outer Planet Auroras

    NASA Astrophysics Data System (ADS)

    McGrath, M.

    Remarkable progress has been made in the past 10 years in studies of auroral processes on the outer, gas-giant planets and their satellites via the dramatic imaging provided by ground-based observations in the infrared (e.g., Satoh and Connerney, 1999, Icarus, 141, 236); by the Hubble Space Telescope in the ultraviolet (e.g., Clarke et al. 2002, Nature, 415, 997); by the Galileo spacecraft at visible wavelengths (e.g., Vasavada et al. 1999, JGR, 104, 27133); and by the Chandra Xray Observatory in the xray (e.g., Gladstone et al. 2002, Nature, 415, 1000). This talk will provide a brief overview of the recent observations, the accompanying modeling, and a short discussion of the contrast between outer planet and Earth auroral processes.

  12. Ionic bonding of lanthanides, as influenced by d- and f-atomic orbitals, by core-shells and by relativity.

    PubMed

    Ji, Wen-Xin; Xu, Wei; Schwarz, W H Eugen; Wang, Shu-Guang

    2015-03-15

    Lanthanide trihalide molecules LnX3 (X = F, Cl, Br, I) were quantum chemically investigated, in particular detail for Ln = Lu (lutetium). We applied density functional theory (DFT) at the nonrelativistic and scalar and SO-coupled relativistic levels, and also the ab initio coupled cluster approach. The chemically active electron shells of the lanthanide atoms comprise the 5d and 6s (and 6p) valence atomic orbitals (AO) and also the filled inner 4f semivalence and outer 5p semicore shells. Four different frozen-core approximations for Lu were compared: the (1s(2) -4d(10) ) [Pd] medium core, the [Pd+5s(2) 5p(6) = Xe] and [Pd+4f(14) ] large cores, and the [Pd+4f(14) +5s(2) 5p(6) ] very large core. The errors of Lu?X bonding are more serious on freezing the 5p(6) shell than the 4f(14) shell, more serious upon core-freezing than on the effective-core-potential approximation. The Ln?X distances correlate linearly with the AO radii of the ionic outer shells, Ln(3+) -5p(6) and X(-) -np(6) , characteristic for dominantly ionic Ln(3+) -X(-) binding. The heavier halogen atoms also bind covalently with the Ln-5d shell. Scalar relativistic effects contract and destabilize the Lu?X bonds, spin orbit coupling hardly affects the geometries but the bond energies, owing to SO effects in the free atoms. The relativistic changes of bond energy BE, bond length Re , bond force k, and bond stretching frequency vs do not follow the simple rules of Badger and Gordy (Re ?BE?k?vs ). The so-called degeneracy-driven covalence, meaning strong mixing of accidentally near-degenerate, nearly nonoverlapping AOs without BE contribution is critically discussed. PMID:25565146

  13. MECHANICAL PROPERTY-MICROSTRUCTURAL RELATIONSHIPS IN ABALONE SHELL*

    E-print Network

    Aksay, Ilhan A.

    109 MECHANICAL PROPERTY-MICROSTRUCTURAL RELATIONSHIPS IN ABALONE SHELL* M. SARIKAYA, K. E. GUNNISON. This impressive combination of af andKIc values is attributed to the laminatedstructure of the shell with hard there are severaltougheningmechanisms operatingin the shell,fractographicstudiesidentified sliding of CaCO3 layers and bridgingby

  14. Outer Solar System Nomenclature

    NASA Technical Reports Server (NTRS)

    Owen, Tobias C.

    1998-01-01

    The Principal Investigator's responsibilities on this grant fell into two categories according to his participation. In the nomenclature work of the International Astronomical Union (IAU). Owen is chair of the Task Group for the Outer Solar System. He is also a member of the IAU's Working Group on Planetary and Satellite Nomenclature (WGPSN) which is composed of the chairs of the several Task Groups plus the presidents of two IAU Commissions and several outside consultants. The WGPSN is presided over by its President, Professor Kaare Aksnes from the Rosseland Institute for Theoretical Astrophysics in Oslo, Norway.

  15. Jupiter's outer atmosphere.

    NASA Technical Reports Server (NTRS)

    Brice, N. M.

    1973-01-01

    The current state of the theory of Jupiter's outer atmosphere is briefly reviewed. The similarities and dissimilarities between the terrestrial and Jovian upper atmospheres are discussed, including the interaction of the solar wind with the planetary magnetic fields. Estimates of Jovian parameters are given, including magnetosphere and auroral zone sizes, ionospheric conductivity, energy inputs, and solar wind parameters at Jupiter. The influence of the large centrifugal force on the cold plasma distribution is considered. The Jovian Van Allen belt is attributed to solar wind particles diffused in toward the planet by dynamo electric fields from ionospheric neutral winds, and the consequences of this theory are indicated.

  16. Biomineral repair of abalone shell apertures.

    PubMed

    Cusack, Maggie; Guo, Dujiao; Chung, Peter; Kamenos, Nicholas A

    2013-08-01

    The shell of the gastropod mollusc, abalone, is comprised of nacre with an outer prismatic layer that is composed of either calcite or aragonite or both, depending on the species. A striking characteristic of the abalone shell is the row of apertures along the dorsal margin. As the organism and shell grow, new apertures are formed and the preceding ones are filled in. Detailed investigations, using electron backscatter diffraction, of the infill in three species of abalone: Haliotis asinina, Haliotis gigantea and Haliotis rufescens reveals that, like the shell, the infill is composed mainly of nacre with an outer prismatic layer. The infill prismatic layer has identical mineralogy as the original shell prismatic layer. In H. asinina and H. gigantea, the prismatic layer of the shell and infill are made of aragonite while in H. rufescens both are composed of calcite. Abalone builds the infill material with the same high level of biological control, replicating the structure, mineralogy and crystallographic orientation as for the shell. The infill of abalone apertures presents us with insight into what is, effectively, shell repair. PMID:23707541

  17. Infestation of Haliotis rufescens shells by a sabellid polychaete

    Microsoft Academic Search

    Frank R. Oakes; Raymond C. Fields

    1996-01-01

    The shell of the California red abalone (Haliotis rufescens) can be host to a variety of organisms, including boring sponges, clams and polychaetes. These boring organisms usually do not seriously affect the growth of the abalone because they normally inhabit the outer portions of mature abalone shells. Abalone cultured in an aquaculture facility are marketed at a young age and

  18. Tides on Europa, and the thickness of Europa's icy shell

    Microsoft Academic Search

    J. M. Wahr; M. T. Zuber; D. E. Smith; J. I. Lunine

    2006-01-01

    It has been shown previously that measurements of tides on Jupiter's moon Europa can be used to determine whether there is a liquid ocean beneath this moon's icy outer shell. In this paper we examine the further possibility of constraining the thickness of the icy shell in the case where a liquid ocean exists, by combining measurements of tidal gravity

  19. BV photometry of five shell galaxies

    NASA Astrophysics Data System (ADS)

    Pierfederici, F.; Rampazzo, R.

    2004-06-01

    Current views consider shell structures as bona fide signatures of a recent minor/major merging event though also weak interaction models (WIM) could produce long lasting shells on host galaxies possessing a stellar thick disc. We present a B V band photometric study of a sample of 5 shell galaxies belonging to the Malin & Carter (1983) compilation. The structural properties and colors of the galaxies, as well as the colors of their shells are examined in detail. We did not find signatures of the presence of double nuclei. NGC 7585 is the only E galaxy in the sample and has a moderately boxy structure. The other galaxies have either a discy structure or are mixed E/S0 type galaxies. NGC 474 is a true lenticular. NGC 6776 shows a diffuse asymmetric outer structure and a system of tails of the the same color of the galaxy body; but not clear shells. In general, the color of the shells in our sample is similar or slightly redder than that of the host galaxy, whose color, in turn, is typical of the early-type morphological class. One of the outer shells of NGC 474 is significantly bluer than the body of the galaxy. Since NGC 474 appears to be interacting with NGC 470, the color of this one shell could be explained as result of a recent acquisition of material through tidal interaction. The WIM hypothesis could explain both the red and the blue shells of NGC 474, this latter acquired from the fly-by of the nearby companion NGC 470, but the lack of the constancy of shell surface brightness as a ratio of the underlying galaxy brightness argues against WIM. We speculate about evidence, which also comes from different observations, that suggests a merging/accretion origin of the shells. Based on observations obtained at the Observatoire de Haute Provence, CNRS, Saint Michel l'Observatoire, France and ESO, La Silla, Chile

  20. Strategy for outer planets exploration

    NASA Technical Reports Server (NTRS)

    1975-01-01

    NASA's Planetary Programs Office formed a number of scientific working groups to study in depth the potential scientific return from the various candidate missions to the outer solar system. The results of these working group studies were brought together in a series of symposia to evaluate the potential outer planet missions and to discuss strategies for exploration of the outer solar system that were consistent with fiscal constraints and with anticipated spacecraft and launch vehicle capabilities. A logical, scientifically sound, and cost effective approach to exploration of the outer solar system is presented.

  1. Shell-in-Shell TiO2 hollow microspheres and optimized application in light-trapping perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sun, Hongxia; Ruan, Peng; Bao, Zhongqiu; Chen, Lei; Zhou, Xingfu

    2015-02-01

    The shell-in-shell structured TiO2 hollow microspheres with enhanced light scattering ability were synthesized via a facile one step hydrothermal process. The diameter of the microsphere is about 1.5 ?m, the core of the unique shell-in-shell structure is composed of TiO2 nanoparticles with a diameter of about 15 nm, while the shell is constructed with ?50 nm TiO2 nanocubes. The hollow space between the outer shell and the inner shell is about 230 nm. The formation mechanism of the unique shell-in-shell structure is interpreted. The design and the optimized application of shell-in-shell structured TiO2 hollow microspheres in the light-trapping perovskite solar cells are also investigated. Owing to the light scattering properties of the shell-in-shell structure of the hollow microsphere, the optimized photoelectrode exhibits an enhanced photoelectric conversion efficiency of 4.29% using perovskite CH3NH3PbI3 as the sensitizer. The shell-in-shell hollow TiO2 microsphere shows a 21.2% increase in conversion efficiency when compared with P25 nanoparticels photoanode. The conversion efficiency enhancement is mainly attributed to the increase of short-current density induced by the light scattering effect.

  2. Must "Hard Problems" Be Hard?

    ERIC Educational Resources Information Center

    Kolata, Gina

    1985-01-01

    To determine how hard it is for computers to solve problems, researchers have classified groups of problems (polynomial hierarchy) according to how much time they seem to require for their solutions. A difficult and complex proof is offered which shows that a combinatorial approach (using Boolean circuits) may resolve the problem. (JN)

  3. Structures in the Outer Solar Atmosphere

    NASA Astrophysics Data System (ADS)

    Fletcher, L.; Cargill, P. J.; Antiochos, S. K.; Gudiksen, B. V.

    2015-05-01

    The structure and dynamics of the outer solar atmosphere are reviewed with emphasis on the role played by the magnetic field. Contemporary observations that focus on high resolution imaging over a range of temperatures, as well as UV, EUV and hard X-ray spectroscopy, demonstrate the presence of a vast range of temporal and spatial scales, mass motions, and particle energies present. By focusing on recent developments in the chromosphere, corona and solar wind, it is shown that small scale processes, in particular magnetic reconnection, play a central role in determining the large-scale structure and properties of all regions. This coupling of scales is central to understanding the atmosphere, yet poses formidable challenges for theoretical models.

  4. Method to produce large, uniform hollow spherical shells

    DOEpatents

    Hendricks, C.D.

    1983-09-26

    The invention is a method to produce large uniform hollow spherical shells by (1) forming uniform size drops of heat decomposable or vaporizable material, (2) evaporating the drops to form dried particles, (3) coating the dried particles with a layer of shell forming material and (4) heating the composite particles to melt the outer layer and to decompose or vaporize the inner particle to form an expanding inner gas bubble. The expanding gas bubble forms the molten outer layer into a shell of relatively large diameter. By cycling the temperature and pressure on the molten shell, nonuniformities in wall thickness can be reduced. The method of the invention is utilized to produce large uniform spherical shells, in the millimeter to centimeter diameter size range, from a variety of materials and of high quality, including sphericity, concentricity and surface smoothness, for use as laser fusion or other inertial confinement fusion targets as well as other applications.

  5. Thermoelectric Outer Planets Spacecraft (TOPS)

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The research and advanced development work is reported on a ballistic-mode, outer planet spacecraft using radioisotope thermoelectric generator (RTG) power. The Thermoelectric Outer Planet Spacecraft (TOPS) project was established to provide the advanced systems technology that would allow the realistic estimates of performance, cost, reliability, and scheduling that are required for an actual flight mission. A system design of the complete RTG-powered outer planet spacecraft was made; major technical innovations of certain hardware elements were designed, developed, and tested; and reliability and quality assurance concepts were developed for long-life requirements. At the conclusion of its active phase, the TOPS Project reached its principal objectives: a development and experience base was established for project definition, and for estimating cost, performance, and reliability; an understanding of system and subsystem capabilities for successful outer planets missions was achieved. The system design answered long-life requirements with massive redundancy, controlled by on-board analysis of spacecraft performance data.

  6. The Double Chooz Outer Veto

    NASA Astrophysics Data System (ADS)

    Conover, Emily

    2013-04-01

    Double Chooz is unique among reactor neutrino experiments for its Outer Veto -- a multi-layered plastic scintillator strip muon detector. The far detector Outer Veto covers 95,^2 on top of the main detector volumes and is composed of 44 modules, each made up of 64 scintillator strips outfitted with wavelength-shifting fibers coupled to a multi-anode PMT. The Outer Veto serves two purposes: first, as a veto, it reduces muon-induced backgrounds to the neutrino signal, in particular the fast neutron and stopping muon backgrounds; second, the high-quality muon tracking it provides allows for detailed studies of these backgrounds, as well as long-lived backgrounds, which cannot be vetoed, such as ^9Li and ^8He. I will describe the design of the Outer Veto, its performance, and some background studies.

  7. The 4 K outer cryostat for the CUORE experiment: construction and quality control

    E-print Network

    F. Alessandria; M. Biassoni; G. Ceruti; A. Chiarini; M. Clemenza; O. Cremonesi; V. Datskov; S. Dossena; M. Faverzani; E. Ferri; A. Nucciotti; M. Perego; E. Previtali; M. Sisti; L. Taffarello; F. Terranova

    2013-06-06

    The external shell of the CUORE cryostat is a large cryogen-free system designed to host the dilution refrigerator and the bolometers of the CUORE experiment in a low radioactivity environment. The three vessels that form the outer shell were produced and delivered to the Gran Sasso underground Laboratories in July 2012. In this paper, we describe the production techniques and the validation tests done at the production site in 2012.

  8. Building Atoms Shell by Shell.

    ERIC Educational Resources Information Center

    Sussman, Beverly

    1993-01-01

    Describes an atom-building activity where students construct three-dimensional models of atoms using a styrofoam ball as the nucleus and pom-poms, gum drops, minimarshmallows, or other small items of two different colors to represent protons and neutrons attached. Rings of various sizes with pom-poms attached represent electron shells and…

  9. Acoustic scattering by a rigid disk or annulus clamped to two concentric cylindrical elastic shells

    NASA Astrophysics Data System (ADS)

    Skelton, E. A.

    1995-04-01

    A plane sound wave is incident upon a system of two concentric cylindrical shells. Linking the shells in such a way that reaction forces and bending moments are transmitted to the shells is a disk or annulus which can undergo rigid body motion only, and which remains perpendicular to the shells at the point of attachment. The shells are surrounded by a compressible fluid, which may also occupy the region between the shells. The scattered pressure is investigated asymptotically for the cases when the exterior fluid provides heavy fluid loading on the outer shell with no fluid between the shells, and when the heavy fluid also occupies the region between the shells, in which case the additional limits of either large or small shell spacing are employed.

  10. SPAWNING CYCLE, FECUNDITY, AND RECRUITMENT IN A POPULATION OF SOFT-SHELL CLAM, MYA ARENARIA,

    E-print Network

    SPAWNING CYCLE, FECUNDITY, AND RECRUITMENT IN A POPULATION OF SOFT-SHELL CLAM, MYA ARENARIA, FROM unavailable. Laboratory methods for stripping eggs or inducing spawning in oysters and hard-shell clams in fecun- dity. Sex ratios ofM. arenaria 25-95 mm shell length did not differ significantly from 1:lover

  11. Outer Shock Interaction in Young Core-Collapse SNRs

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Joon

    2014-01-01

    Studying the environments in which core-collapse supernovae (SNe) explode and then subsequently evolve is essential to establish the nature of the mass loss and the explosion of the progenitor star. The spatial structure of the outer shock in young core-collapse SNRs provides an opportunity to study the nature of the medium into which the remnant has been expanding. We present our X-ray study of the outer shocks in young core-collapse SNRs in our Galaxy. For Cas A and G292.0+1.8, we find that both remnants have been likely interacting with dense red supergiant winds. For other remnants with bright thermal X-ray emission from the shell, we suggest that they are interacting with pre-existing circumstellar structure. We discuss the nature of the winds and the progenitor stars.

  12. Calculation of Massive 2-Loop Operator Matrix Elements with Outer Gluon Lines

    E-print Network

    I. Bierenbaum; J. Blümlein; S. Klein

    2007-02-26

    Massive on-shell operator matrix elements and self-energy diagrams with outer gluon lines are calculated analytically at $O(\\alpha_s^2)$, using Mellin-Barnes integrals and representations through generalized hypergeometric functions. This method allows for a direct evaluation without decomposing the integrals using the integration-by-parts method.

  13. Role of reactant transport in determining the properties of NIF shells made by interfacial polycondensation

    SciTech Connect

    Hamilton, K.E.; Letts, S.A.; Buckley, S.R.; Fearon, E.M.; Wilemski, G.; Cook, R.C. [Lawrence Livermore National Lab., CA (United States); Schroen-Carey, D. [W.J. Schafer and Associates, Livermore, CA (United States)

    1997-03-01

    Polymer shells up to 2 mm in diameter were prepared using an interfacial polycondensation / cross-linking reaction occurring at the surface of an oil drop. The oil phase is comprised of a solution (20 wt% or less) of isophthaloyl dichloride (IPC) dissolved in an organic solvent. An interfacial reaction is initiated when the IPC-loaded oil drop is submerged in an aqueous solution of poly(p-vinylphenol) (PVP), a poly(electrolyte) at elevated pH. Composition, structure, and surface finish for fully-formed dry shells were assessed using a number of techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), fourier-transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography (GC) mass spectroscopy (MS), microhardness measurements, gas permeability, and solvent permeability measurements. From deposition rate data, a reaction mechanism and key reaction parameters were identified. The deposition rate of shell membrane material was found to be a diffusion limited reaction of IPC through the forming membrane to the exterior shell interface (which is believed to be the reaction front). The final thickness of the film deposited at the interface and the rate of deposition were found to be strong functions of the IPC concentration and oil phase solvent. Films made with diethyl phthalate (DEP) were thinner and harder than films made using 1,6-dichlorohexane (DCH) as a solvent. Differences in solubility of the forming membrane in DCH and DEP appear to be able to account for the differences in deposition rate and the hardness (related to cross-linking density). The deposition can be thought of as a phase separation which is affected by both the poly(electrolyte) / ionomer transition and the amount of cross-linking. Finally, it was found that the choice of oil phase solvent profoundly affects the evolution of the outer surface roughness.

  14. Slingshot to the Outer Planets

    NSDL National Science Digital Library

    2014-09-18

    Students are introduced to the engineering challenges involved with interplanetary space travel. In particular, they learn about the gravity assist or "slingshot" maneuver often used by engineers to send spacecraft to the outer planets. Using magnets and ball bearings to simulate a planetary flyby, students investigate what factors influence the deflection angle of a gravity assist maneuver.

  15. IRAS results on outer galaxy star formation

    NASA Technical Reports Server (NTRS)

    Terebey, Susan; Fich, Michel

    1989-01-01

    An infrared defined (60 micron) sample of IRAS sources were systematically studied in order to investigate star formation in the outer Galaxy. Five percent of the sample are point sources with IRAS spectra that suggest the emission is from a dust shell surrounding a mature star. Ninety five percent have spectra where flux density strictly rises with wavelength. The sources are extended, and it is shown that Point Source Catalog fluxes seriously underestimate total fluxes. CO kinematic distances were reliably assigned to two thirds of the sources. Most of the infrared luminosities correspond to B spectral types. Six cm continuum emission were detected from all sources inferred to have spectral type B1 or earlier. The combined IRAS/CO/6 cm data show these sources are young, moderately massive stars that are embedded in interstellar clouds. The young embedded sources define a distinct band in an IRAS color-colar diagram. Normal IRAS galaxies fall in the same band, consistent with the interpretation that their infrared emission is due to star formation.

  16. Experimental identification of finite cylindrical shell vibration modes.

    PubMed

    Haumesser, Lionel; Décultot, Dominique; Léon, Fernand; Maze, Gérard

    2002-05-01

    Acoustic scattering from a finite air-filled elastic cylindrical shell, immersed in water, is investigated. The shell is made of stainless steel and has a thickness to outer radius ratio of 17%. The considered dimensionless frequency range extends over 7 < k1a < 22 (k1: wave number in water, a: outer radius). Bistatic measurements are carried out to identify vibration modes related to the phase matching of the first guided wave, T0, propagating on the shell. Both transducers, the emitter and the receiver, are positioned at the same angular distance with regard to the normal axis of the shell. The emitter transducer is fixed at a given position. In order to identify circumferential modes of vibration, the receiver transducer is made to rotate in the azimuthal plane, normal to the shell axis. Results obtained are plotted in functions of dimensionless frequency and azimuthal angle. Vibration modes along the shell's length are identified by moving the receiver transducer parallel to the shell axis. In this case, results are plotted in functions of dimensionless frequency and axial wave number. The experimental investigation is corroborated by theoretical results obtained from approximate calculations for thick finite cylindrical shells [Scot F. Morse et al., J. Acoust. Soc. Am. 103, 785-794 (1998)]. The evolution of the mode position with respect to the incidence angle is discussed so as to clarify peak patterns in backscattered resonance spectra. PMID:12051423

  17. Experimental identification of finite cylindrical shell vibration modes

    NASA Astrophysics Data System (ADS)

    Haumesser, Lionel; Décultot, Dominique; Léon, Fernand; Maze, Gérard

    2002-05-01

    Acoustic scattering from a finite air-filled elastic cylindrical shell, immersed in water, is investigated. The shell is made of stainless steel and has a thickness to outer radius ratio of 17%. The considered dimensionless frequency range extends over 7<=k1a<=22 (k1: wave number in water, a: outer radius). Bistatic measurements are carried out to identify vibration modes related to the phase matching of the first guided wave, T0, propagating on the shell. Both transducers, the emitter and the receiver, are positioned at the same angular distance with regard to the normal axis of the shell. The emitter transducer is fixed at a given position. In order to identify circumferential modes of vibration, the receiver transducer is made to rotate in the azimuthal plane, normal to the shell axis. Results obtained are plotted in functions of dimensionless frequency and azimuthal angle. Vibration modes along the shell's length are identified by moving the receiver transducer parallel to the shell axis. In this case, results are plotted in functions of dimensionless frequency and axial wave number. The experimental investigation is corroborated by theoretical results obtained from approximate calculations for thick finite cylindrical shells [Scot F. Morse et al., J. Acoust. Soc. Am. 103, 785-794 (1998)]. The evolution of the mode position with respect to the incidence angle is discussed so as to clarify peak patterns in backscattered resonance spectra.

  18. Turbine airfoil with a compliant outer wall

    DOEpatents

    Campbell, Christian X. (Oviedo, FL); Morrison, Jay A. (Oviedo, FL)

    2012-04-03

    A turbine airfoil usable in a turbine engine with a cooling system and a compliant dual wall configuration configured to enable thermal expansion between inner and outer layers while eliminating stress formation in the outer layer is disclosed. The compliant dual wall configuration may be formed a dual wall formed from inner and outer layers separated by a support structure. The outer layer may be a compliant layer configured such that the outer layer may thermally expand and thereby reduce the stress within the outer layer. The outer layer may be formed from a nonplanar surface configured to thermally expand. In another embodiment, the outer layer may be planar and include a plurality of slots enabling unrestricted thermal expansion in a direction aligned with the outer layer.

  19. Nanorod and nanoparticle shells in concentration gradient core-shell lithium oxides for rechargeable lithium batteries.

    PubMed

    Yoon, Sung-June; Myung, Seung-Taek; Noh, Hyung-Joo; Lu, Jun; Amine, Khalil; Sun, Yang-Kook

    2014-12-01

    The structure, electrochemistry, and thermal stability of concentration gradient core-shell (CGCS) particles with different shell morphologies were evaluated and compared. We modified the shell morphology from nanoparticles to nanorods, because nanorods can result in a reduced surface area of the shell such that the outer shell would have less contact with the corrosive electrolyte, resulting in improved electrochemical properties. Electron microscopy studies coupled with electron probe X-ray micro-analysis revealed the presence of a concentration gradient shell consisting of nanoparticles and nanorods before and after thermal lithiation at high temperature. Rietveld refinement of the X-ray diffraction data and the chemical analysis results showed no variations of the lattice parameters and chemical compositions of both produced CGCS particles except for the degree of cation mixing (or exchange) in Li and transition metal layers. As anticipated, the dense nanorods present in the shell gave rise to a high tap density (2.5 g?cm(-3) ) with a reduced pore volume and surface area. Intimate contact among the nanorods is likely to improve the resulting electric conductivity. As a result, the CGCS Li[Ni0.60 Co0.15 Mn0.25 ]O2 with the nanorod shell retained approximately 85.5% of its initial capacity over 150 cycles in the range of 2.7-4.5 V at 60?°C. The charged electrode consisting of Li0.16 [Ni0.60 Co0.15 Mn0.25 ]O2 CGCS particles with the nanorod shell also displayed a main exothermic reaction at 279.4?°C releasing 751.7?J?g(-1) of heat. Due to the presence of the nanorod shell in the CGCS particles, the electrochemical and thermal properties are substantially superior to those of the CGCS particles with the nanoparticle shell. PMID:25044175

  20. Wireless Transfer of Electricity in Outer Space

    E-print Network

    Alexander Bolonkin

    2008-05-07

    Author offers conclusions from his research of a revolutionary new idea - transferring electric energy in the hard vacuum of outer space wirelessly, using a plasma power cord as an electric cable (wire). He shows that a certain minimal electric currency creates a compressed force that supports the plasma cable in the compacted form. A large energy can be transferred hundreds of millions of kilometers by this method. The required mass of the plasma cable is only hundreds of grams. He computed the macroprojects: transference of hundreds kilowatts of energy to Earth Space Station, transferring energy to the Moon or back, transferring energy to a spaceship at distance 100 million of kilometers, the transfer energy to Mars when one is located at opposed side of the distant Sun, transfer colossal energy from one of Earth's continents to another continent (for example, between Europe-USA) wirelessly-using Earth ionosphere as cable, using Earth as gigantic storage of electric energy, using the plasma ring as huge MagSail for moving of spaceships. He also demonstrates that electric currency in a plasma cord can accelerate or brake spacecraft and space apparatus.

  1. BOOKSHELF Hard Disk Drive

    E-print Network

    Benmei, Chen

    » BOOKSHELF Hard Disk Drive Servo Systems, 2nd edition by B.M. CHEN, T.H. LEE, K. PENG, and V- widths ever higher as higher frequency disturbances become relevant. THE BOOK Hard Disk Drive Servo I of Hard Disk Drive Servo Systems briefly discusses the history of hard drive control and the disk

  2. Physics of the outer heliosphere

    SciTech Connect

    Gazis, P.R. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Major advances in the physics of the outer heliosphere are reviewed for the 1987-1990 time frame. Emphasis is placed on five broad topics: the detailed structure of the solar wind at large heliocentric distances, the global structure of the interplanetary field, latidudinal variations and meridional flows, radial and temporal variations, and the interaction of the solar wind with the local interstellar medium. 122 refs.

  3. Development and functions of the shell sculpture of the marine snail Ceratostoma foliatum

    Microsoft Academic Search

    T. M. Spight; A. Lyons

    1974-01-01

    The shell of the adult Ceratostoma foliatum (Gmelin) is characterized by three varices with foliations, and a tooth on the anterior portion of the outer lip. These features are derived gradually from the markedly different sculpture of shells of small juveniles (a network of fine axial and spiral cords). The sculpture changes as the thin, cord-like basic varix is elaborated,

  4. Transient temperatures in laminated composite conical shells due to aerodynamic heating

    Microsoft Academic Search

    B. Basava Raju; Ramesh Chandra; M. Subba Rao

    1978-01-01

    Transient temperatures in laminated composite conical shells, subjected to aerodynamic heating, were studied. One edge was at the prescribed temperature and the other edge was insulated. The outer surface of the conical sheel was subjected to linear heat transfer due to aerodynamic heating. Transient heat conduction equations for a laminated composite conical shell were formulated, and solved for axisymmetric heat

  5. Geometrical interpretation for the outer SU(3) outer multiplicity label

    NASA Technical Reports Server (NTRS)

    Draayer, Jerry P.; Troltenier, D.

    1995-01-01

    A geometrical interpretation for the outer multiplicity rho that occurs in a reduction of the product of two SU(3) representations, (lambda(sub pi), mu(sub pi)) x (lambda(sub nu), mu(sub nu)) approaches sigma(sub rho)(lambda, mu)(sub rho), is introduced. This coupling of proton (pi) and neutron (nu) representations arises, for example, in both boson and fermion descriptions of heavy deformed nuclei. Attributing a geometry to the coupling raises the possibility of introducing a simple interaction that provides a physically meaningful way for distinguishing multiple occurrences of (lambda, mu) values that can arise in such products.

  6. Magnetohydrodynamic Ekman and Stewartson Layers in a Rotating Spherical Shell

    Microsoft Academic Search

    Rainer Hollerbach

    1994-01-01

    I investigate numerically the flow of an electrically conducting fluid in a differentially rotating spherical shell, in the presence of an imposed magnetic field. For a very weak field the flow is seen to consist of an Ekman layer on the inner and outer spherical boundaries, and a Stewartson layer on the cylinder circumscribing the inner sphere and parallel to

  7. Scattering and active acoustic control from a submerged spherical shell

    NASA Astrophysics Data System (ADS)

    Scandrett, Clyde

    2002-02-01

    This paper is concerned with the scattering from a submerged (heavy fluid) bilaminate spherical shell composed of an outer layer of steel, and an inner layer of radially polarized piezoelectric material. The methodology used includes separation formulas for the stresses and displacements, which in turn are used (coupled with spherical harmonics) to reduce the governing equations to linear systems of ordinary differential equations. This technique uses the full equations of elasticity rather than any of the various thin-shell approximations in determining the axisymmetric scattering from a shell, normal modes of vibration for the shell, as well as voltages necessary for annihilation of a scattered pressure due to insonification of the shell by an incident plane wave.

  8. Endoliths in Lithophaga lithophaga shells - Variation in intensity of infestation and species occurrence.

    PubMed

    Peharda, Melita; Calcinai, Barbara; Puljas, Sanja; Golubi?, Stjepko; Arapov, Jasna; Thébault, Julien

    2015-07-01

    Pronounced differences with respect to the extent of infestation and the degree of Lithophaga lithophaga shell damage inflicted by euendolithic taxa at two sites in the Adriatic Sea representing different productivity conditions, are described. Shells collected from the eastern part of Kaštela Bay, which is characterized by higher primary productivity, have significantly more shell damage then the shell collected from a site on the outer coast of the island of ?iovo exposed to the oligotrophic Adriatic Sea. The presence of endoliths and their perforations were detected in different layers of the shell, including solidly mineralized parts of the skeleton and within the organic lamellae incorporated into the shell. Phototrophic endoliths were not observed in the specimens. The most serious damage to L. lithophaga shells was the boring clionaid sponge Pione vastifica, which was more common in shells collected from Kaštela. PMID:25982321

  9. Observations of the outer belt

    NASA Astrophysics Data System (ADS)

    Lagerkvist, C.-. I.; Moroz, L.; Karlsson, O.; Nathues, A.; Erikson, A.; Lahulla, F.; Dahlgren, M.; Davidsson, B.

    The outer belt consist of three major groups, the Cybeles, the Hildas and the Trojans. Taxonomic classification of the asteroids reveal a dependence with size. The largest bodies are C types followed by P types and D types. A possible explanation for this is an alternation of the surfaces over time leading to a reduced spectral slope. The D types is mostly collisional fragments and thus have the youngest and reddest surfaces. Although the Trojans, consisting of the two subgroups L_4 and L_5, is the most numerous group it is the least observed one.

  10. Hard thermal effective action in QCD through the thermal operator

    E-print Network

    Ashok Das; J. Frenkel

    2007-06-01

    Through the application of the thermal operator to the zero temperature retarded Green's functions, we derive in a simple way the well known hard thermal effective action in QCD. By relating these functions to forward scattering amplitudes for on-shell particles, this derivation also clarifies the origin of important properties of the hard thermal effective action, such as the manifest Lorentz and gauge invariance of its integrand.

  11. Global storm time depletion of the outer electron belt

    NASA Astrophysics Data System (ADS)

    Ukhorskiy, A. Y.; Sitnov, M. I.; Millan, R. M.; Kress, B. T.; Fennell, J. F.; Claudepierre, S. G.; Barnes, R. J.

    2015-04-01

    The outer radiation belt consists of relativistic (>0.5 MeV) electrons trapped on closed trajectories around Earth where the magnetic field is nearly dipolar. During increased geomagnetic activity, electron intensities in the belt can vary by orders of magnitude at different spatial and temporal scales. The main phase of geomagnetic storms often produces deep depletions of electron intensities over broad regions of the outer belt. Previous studies identified three possible processes that can contribute to the main-phase depletions: adiabatic inflation of electron drift orbits caused by the ring current growth, electron loss into the atmosphere, and electron escape through the magnetopause boundary. In this paper we investigate the relative importance of the adiabatic effect and magnetopause loss to the rapid depletion of the outer belt observed at the Van Allen Probes spacecraft during the main phase of 17 March 2013 storm. The intensities of >1 MeV electrons were depleted by more than an order of magnitude over the entire radial extent of the belt in less than 6 h after the sudden storm commencement. For the analysis we used three-dimensional test particle simulations of global evolution of the outer belt in the Tsyganenko-Sitnov (TS07D) magnetic field model with an inductive electric field. Comparison of the simulation results with electron measurements from the Magnetic Electron Ion Spectrometer experiment shows that magnetopause loss accounts for most of the observed depletion at L>5, while at lower L shells the depletion is adiabatic. Both magnetopause loss and the adiabatic effect are controlled by the change in global configuration of the magnetic field due to storm time development of the ring current; a simulation of electron evolution without a ring current produces a much weaker depletion.

  12. Hard-sphere-like dynamics in a non-hard-sphere liquid.

    PubMed

    Scopigno, T; Di Leonardo, R; Comez, L; Baron, A Q R; Fioretto, D; Ruocco, G

    2005-04-22

    The collective dynamics of liquid gallium close to the melting point has been studied using inelastic x-ray scattering to probe length scales smaller than the size of the first coordination shell. Although the structural properties of this partially covalent liquid strongly deviate from a simple hard-sphere model, the dynamics, as reflected in the quasielastic scattering, are beautifully described within the framework of the extended heat mode approximation of Enskog's kinetic theory, analytically derived for a hard-sphere system. The present work demonstrates, therefore, the applicability of Enskog's theory beyond simple liquids. PMID:15904154

  13. Hardness testing. 2nd edition

    SciTech Connect

    Chandler, H. [ed.

    1999-07-01

    This basic book provides a comprehensive overview of hardness testing, including the various methods and equipment used, testing applications, and the selection of testing methods. The revised and updated second edition features expanded information on microhardness testing, specialized hardness tests; and hardness testing standards. Contents include: introduction to hardness testing; brinell testing; rockwell hardness testing; vickers hardness testing; microhardness testing; scleroscope and leeb hardness testing; hardness testing applications; and selection of hardness testing methods.

  14. Wear of hard materials by hard particles

    SciTech Connect

    Hawk, Jeffrey A.

    2003-10-01

    Hard materials, such as WC-Co, boron carbide, titanium diboride and composite carbide made up of Mo2C and WC, have been tested in abrasion and erosion conditions. These hard materials showed negligible wear in abrasion against SiC particles and erosion using Al2O3 particles. The WC-Co materials have the highest wear rate of these hard materials and a very different material removal mechanism. Wear mechanisms for these materials were different for each material with the overall wear rate controlled by binder composition and content and material grain size.

  15. Outer Appearances Can Be Deceiving

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This graph shows the chemical composition of the rock at Gusev Crater dubbed 'Mazatzal' after it was brushed and ground by the Mars Exploration Rover Spirit's rock abrasion tool. The data, taken by the rover's alpha particle X-ray spectrometer over the last few sols, show that the amount of chlorine and sulfur tri-oxide in Mazatzal first increased after brushing, then diminished after grinding. The interior of the rock appears to have the same chemical make-up as other volcanic or basalt rocks studied in the Gusev Crater area ('Adirondack' and 'Humphrey'). Its outer coating or rind, on the other hand, appears to be of a different constitution. Scientists are still puzzling out the implications of these data.

    The larger symbols on the graph represent inferred rock compositions, while the smaller symbols are actual data points. Observations were made at the target dubbed 'New York' on Mazatzal.

  16. Chandra Peers Into Outer Space

    NSDL National Science Digital Library

    Payne, Laura X.

    NASA's newest space telescope, the Chandra X-ray Observatory, was launched into orbit only two months ago. Named for the late Indian-American Nobel laureate, Subrahmanyan Chandrasekhar, the Chandra Observatory is already providing scientists with the first "X-ray images and spectra of violent, high-temperature events and objects." In addition to their sheer mystique, these color images increase scientists's understanding of the structure and evolution of the universe. Managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, the Chandra X-Ray Observatory also serves as a unique tool for studying detailed physics "in a unique laboratory -- the universe itself." This week's In The News highlights the Chandra X-Ray Observatory; the nine sites listed offer background information, commentary, and recent images from outer space.

  17. Chemistry of the outer planets

    NASA Technical Reports Server (NTRS)

    Scattergood, Thomas W.

    1992-01-01

    Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

  18. Outer trapped surfaces are dense near MOTSs

    NASA Astrophysics Data System (ADS)

    Chru?ciel, Piotr T.; Galloway, Gregory J.

    2014-02-01

    We show that any vacuum initial data set containing a marginally outer trapped surface S and satisfying a ‘no KIDs’ condition can be perturbed near S so that S becomes strictly outer trapped in the new vacuum initial data set. This, together with the results in Eichmair et al (2012), gives a precise sense in which generic initial data containing marginally outer trapped surfaces lead to geodesically incomplete spacetimes.

  19. Double-shell defect experiments on Omega

    NASA Astrophysics Data System (ADS)

    Magelssen, G. R.; Fincke, J.; Lanier, N. E.; Batha, S. H.; Delamater, N. D.; Hueckstaedt, R. M.; Taccetti, J. M.; Parker, K. W.; Horsfield, C. J.; Rothman, S. D.

    2004-11-01

    Understanding the effect of defects for inertial confinement fusion (ICF) capsules is an important goal for the National Ignition Facility (NIF). As a result we have been doing defect experiments on the University of Rochester laser facility, OMEGA, to address a number of different issues. In this talk we describe our most recent experiments that study how a defect deformed shock created in an outer cylinder affects a uniform inner cylinder. The target configuration was two concentric cylinders with an epoxy ablator for the outer cylinder. CH foam was placed between the two cylinders and within the inner cylinder. The target was imploded using 50 laser beams. Experiments and simulations show that the defect deformed shock creates large perturbations on the inner shell. We will describe the experiments and our simulation results done with the AMR code RAGE.

  20. 76 FR 2919 - Outer Continental Shelf Official Protraction Diagram and Supplemental Official Outer Continental...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ...Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean Energy...Supplemental Official Outer Continental Shelf Block Diagrams...Diagram (OPD) and Supplemental Official OCS Block Diagrams (SOBDs) located in the...

  1. Non-uniform thickness in Europa's icy shell: implications for astrobiology mission design

    NASA Astrophysics Data System (ADS)

    Fairén, A.; Amils, R.

    The exploration of Europa's subsurface ocean is hardly constrained by the presence of an outer ice shell of unknown thickness: a somewhat thin crust would allow easier access to the ocean below. Current estimates for the thickness of Europa's icy surface range from a few km [1] to a few tens of km [2], the shell overlying a liquid water ocean up to 150 km thick [3,4,5]. The surface is believed to be young (mean age of 30-80 Myr [6]) and geologically active [7,8,9], as it is sparsely cratered. Here we report geological evidence indicating that the thickness of Europa's ice crust is actually a complex combination of thicker and thinner areas, highlighting the implications of such structure in the future exploration of the inner ocean. Detailed geologic mapping of impact craters, palimpsests and chaotic terrains distribution on Europa's surface, offers an initial approach to a comprehensive description of the thickness variation in the ice shell. Our analysis is based in: (1) Crater distribution, morphology, diameter and depth. Seminal work by Schenk [2] of transitions in crater shape/diameter suggested enhanced structural collapse of craters with diameter >27-33 km, that will consequently form multiring basins, due to weaker ice or a global ocean at depths >19-25 km. This being true, strictly can only be interpreted regionally: multiring basins indicate regions where the ice shell is thick; in those regions where the icy surface is thin, a bolide impact will breach the ice and leave neither crater nor multiring basin behind, but probably Ganymede's type palimpsests. (2) Palimpsest-type features distribution, indicating regions where the ice shell is too thin to support crater formation after big bolide impacts. In Ganymede, palimpsests are circular, low albedo and relief features formerly formed by impacts [10,11]. (3) Chaotic terrain distribution, considering features tens to hundreds of km across, that may be the evidence for very thin ice areas (from ˜ 2 km to zero shell thickness [12]) with liquid water at shallow depths [5], allowing for bolide penetration, diapirism and the extrusion of water to the surface. The heterogeneity in shell's thickness may be originated in spatial variations in tidal heating [13] and/or warm water upwellings from the silicate interior capable of melt-through the ice from below [12,14]. This thickness heterogeneity can be embedded in a general equatorward thickening trending, due to tidal dissipation and surface temperature variations [15]. A major constraint must be addressed at this point: the dynamism of ductile ice near the base of the shell may drive to decay in lateral thickness contrasts. But this effect has been examined both assuming ice as a Newtonian [16,17,18] and a non-Newtonian material [19], broadly reaching to similar conclusions: global shell thickness variations may survive for up to 100 Myr. In addition, lateral pressure gradients may not decay if they comprise only shallow depths [19]. Therefore, our results point to a dynamic non-uniform Europa's icy shell, displaying some regional and temporal heterogeneity in thickness. As thin/thick ice distribution is as time dependent as the surface ice features are (both are reshaped in periods ˜ 100 Myr), the analysis performed here offers an estimation of the current thickness distribution in the ice shell, estimation that cannot be extrapolated to ancient (e.g., >100 Myr) times. The astrobiological potential the shell and ocean below possess is highlighted by these results: a somewhere thin outer crust allows the possibility for some exogenous materials delivered by asteroids and comets to reach the inner liquid water ocean by breaching the brittle lithosphere [20], and so join to those generated in the interior of Europa via volcanic and hydrothermal activity [21]. In addition, pressure gradients driving the ductile ice at the base of the shell to flow laterally may help to redistribute such materials among the inner ice shell and/or ocean through time. Our results have a direct deal with the investigation of Eur

  2. DI in the outer Galaxy

    E-print Network

    Jayaram N. Chengalur; Robert Braun; W. Butler Burton

    1997-01-13

    We report on a deep search with the Westerbork Synthesis Radio Telescope towards the galactic anticenter for the 327 MHz hyperfine transition of DI. This is a favorable direction for a search because: (i) the HI optical depth is high due to velocity crowding; (ii) the observed molecular column density is low (implying that most of the deuterium would probably be in atomic form, rather than in HD); and (iii) the stellar reprocessing should be minimal. Our observations are about a factor of two more sensitive than previous searches for DI in this direction. We detect a low significance (about 4 sigma) feature, consistent in both amplitude and center frequency with an emission feature reported previously (Blitz & Heiles 1987). If this is the DI line, then the implied N_D/N_H of 3.9+/-1.0 x 10^-5 is comparable to the inferred pre-solar deuterium abundance. Our observation is consistent with the recent low measurements of D/H towards high-redshift Lyman-limit systems. On the other hand, if the reports of high DI abundance (about 24 x 10^-5) in such systems are confirmed, then our observations imply that even in regions of reduced star formation within the outer Galaxy, the DI abundance has been reduced by a factor of about 6 from the primordial abundance.

  3. How Hard is Chocolate?

    NSDL National Science Digital Library

    2007-12-20

    Hardness is probably a concept you are well familiar with. You already know that certain materials are harder than others; in fact, you prove it everyday when you chew your food and your teeth don’t break (because your teeth are harder than the foods you chew). Hardness can be defined as a material's ability to resist a change in shape. Modern hardness testers take a well-defined shape and press it into a material with a certain force, observing the indent it leaves in the material when it is removed. In this lesson, you will be performing hardness testing on different bars of chocolate.

  4. Ormosils of high hardness

    SciTech Connect

    Iwamoto, Takashi; Mackenzie, J.D. [Univ. of California, Los Angeles, CA (United States). Dept. of Materials Science and Engineering

    1994-12-31

    Organically modified silicates (ormosils) of high hardness were prepared by the reactions of tetraethoxysilane (TEOS) and polydimethylsiloxane (PDMS) aided by ultrasonic irradiation. The mechanisms leading to the hard ormosil formation were investigated by liquid state {sup 29}Si NMR spectroscopy. PDMS chains were found to be broken into shorter chains and/or 4-membered siloxane rings during the reaction and finally, all PDMS chains were chemically incorporated as short chains into silica networks. Vickers hardnesses of the hard ormosils were measured and compared with those of the hardest transparent plastics. Whereas the hardest transparent plastics have Vickers hardness values of less than 25 kg/mm{sup 2}, the hard ormosils have Vickers hardnesses tip to higher than 150 kg/mm{sup 2}. A theoretical model was developed for the calculation of Vickers hardnesses of the hard ormosils and agreed well with experimental results. Predictions based on this theory indicate that even harder ormosils can be made when Al{sub 2}O{sub 3}, ZrO{sub 2} and TiO{sub 2} are substituted for SiO{sub 2}. Results based on these new ormosils are also presented.

  5. Fluctuating shells under pressure

    PubMed Central

    Paulose, Jayson; Vliegenthart, Gerard A.; Gompper, Gerhard; Nelson, David R.

    2012-01-01

    Thermal fluctuations strongly modify the large length-scale elastic behavior of cross-linked membranes, giving rise to scale-dependent elastic moduli. Whereas thermal effects in flat membranes are well understood, many natural and artificial microstructures are modeled as thin elastic shells. Shells are distinguished from flat membranes by their nonzero curvature, which provides a size-dependent coupling between the in-plane stretching modes and the out-of-plane undulations. In addition, a shell can support a pressure difference between its interior and its exterior. Little is known about the effect of thermal fluctuations on the elastic properties of shells. Here, we study the statistical mechanics of shape fluctuations in a pressurized spherical shell, using perturbation theory and Monte Carlo computer simulations, explicitly including the effects of curvature and an inward pressure. We predict novel properties of fluctuating thin shells under point indentations and pressure-induced deformations. The contribution due to thermal fluctuations increases with increasing ratio of shell radius to thickness and dominates the response when the product of this ratio and the thermal energy becomes large compared with the bending rigidity of the shell. Thermal effects are enhanced when a large uniform inward pressure acts on the shell and diverge as this pressure approaches the classical buckling transition of the shell. Our results are relevant for the elasticity and osmotic collapse of microcapsules. PMID:23150558

  6. Manganese speciation in Diplodon chilensis patagonicus shells: a XANES study

    Microsoft Academic Search

    A. L. Soldati; V. Vicente-Vilas; J. Goettlicher; D. E. Jacob

    2009-01-01

    In addition to other types of climate archives, biogenic skeletons of a variety of different organisms (i.e. shells of bivalves, skeletal hard parts of corals or sponges) are increasingly used for high-resolution climate reconstructions. Bivalves are particularly suited for such analyses because they are geographically broadly distributed and have been shown to record climate and environmental information reliably and over

  7. Session: Hard Rock Penetration

    SciTech Connect

    Tennyson, George P. Jr.; Dunn, James C.; Drumheller, Douglas S.; Glowka, David A.; Lysne, Peter

    1992-01-01

    This session at the Geothermal Energy Program Review X: Geothermal Energy and the Utility Market consisted of five presentations: ''Hard Rock Penetration - Summary'' by George P. Tennyson, Jr.; ''Overview - Hard Rock Penetration'' by James C. Dunn; ''An Overview of Acoustic Telemetry'' by Douglas S. Drumheller; ''Lost Circulation Technology Development Status'' by David A. Glowka; ''Downhole Memory-Logging Tools'' by Peter Lysne.

  8. Memory Hard Drive Peripherals

    E-print Network

    Stojmenovic, Ivan

    1! CSI3131 Topics CPU Memory Hard Drive Peripherals Computing Systems OS Overview StructureDeadlocks M em ory M anagem ent Basic Memory Managermtn Virtual Memory Storage and I/O File Systems Hard Drive Management Swap I/O Management 2 Module 7: Memory Management Reading: Chapter 8 § To provide a detailed

  9. Sclerochronological records of temperature and growth from shells of Mercenaria mercenaria from Narragansett Bay, Rhode Island

    Microsoft Academic Search

    D. S. Jones; M. A. Arthur; D. J. Allard

    1989-01-01

    Annual internal growth increments in shells of hard clams (Mercenaria mercenaria) provide an accurate record of both growth history and some types of environmental change. These increments were used to determine age and growth rate of hard clams collected in 1984–1985 from ten sites in Narragansett Bay, Rhode Island, USA, and to assess geographic variation in growth within the bay.

  10. The hard metal diseases.

    PubMed

    Cugell, D W

    1992-06-01

    Hard metal is a mixture of tungsten carbide and cobalt, to which small amounts of other metals may be added. It is widely used for industrial purposes whenever extreme hardness and high temperature resistance are needed, such as for cutting tools, oil well drilling bits, and jet engine exhaust ports. Cobalt is the component of hard metal that can be a health hazard. Respiratory diseases occur in workers exposed to cobalt--either in the production of hard metal, from machining hard metal parts, or from other sources. Adverse pulmonary reactions include asthma, hypersensitivity pneumonitis, and interstitial fibrosis. A peculiar, almost unique form of lung fibrosis, giant cell interstitial pneumonia, is closely linked with cobalt exposure. PMID:1511554

  11. Effect of milling time and CNT concentration on hardness of CNT/Al{sub 2024} composites produced by mechanical alloying

    SciTech Connect

    Perez-Bustamante, R. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Perez-Bustamante, F. [Universidad Autonoma de Chihuahua (UACH), Facultad de Ingenieria, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125, Chihuahua, Chih. (Mexico)] [Universidad Autonoma de Chihuahua (UACH), Facultad de Ingenieria, Circuito No. 1 Nuevo Campus Universitario, C.P. 31125, Chihuahua, Chih. (Mexico); Estrada-Guel, I. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Licea-Jimenez, L. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Unidad Mty, Autopista Monterrey-Aeropuerto Km 10, A. P. 43, C.P. 66600, Apodaca, N.L. (Mexico)] [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Unidad Mty, Autopista Monterrey-Aeropuerto Km 10, A. P. 43, C.P. 66600, Apodaca, N.L. (Mexico); Miki-Yoshida, M. [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)] [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico); Martinez-Sanchez, R., E-mail: roberto.martiez@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados (CIMAV), Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes No.120, C.P. 31109, Chihuahua, Chih. (Mexico)

    2013-01-15

    Carbon nanotube/2024 aluminum alloy (CNT/Al{sub 2024}) composites were fabricated with a combination of mechanical alloying (MA) and powder metallurgy routes. Composites were microstructurally and mechanically evaluated at sintering condition. A homogeneous dispersion of CNTs in the Al matrix was observed by a field emission scanning electron microscopy. High-resolution transmission electron microscopy confirmed not only the presence of well dispersed CNTs but also needle-like shape aluminum carbide (Al{sub 4}C{sub 3}) crystals in the Al matrix. The formation of Al{sub 4}C{sub 3} was suggested as the interaction between the outer shells of CNTs and the Al matrix during MA process in which crystallization took place after the sintering process. The mechanical behavior of composites was evaluated by Vickers microhardness measurements indicating a significant improvement in hardness as function of the CNT content. This improvement was associated to a homogeneous dispersion of CNTs and the presence of Al{sub 4}C{sub 3} in the aluminum alloy matrix. - Highlights: Black-Right-Pointing-Pointer The 2024 aluminum alloy was reinforced by CNTs by mechanical alloying process. Black-Right-Pointing-Pointer Composites were microstructural and mechanically evaluated after sintering condition. Black-Right-Pointing-Pointer The greater the CNT concentration, the greater the hardness of the composites. Black-Right-Pointing-Pointer Higher hardness in composites is achieved at 20 h of milling. Black-Right-Pointing-Pointer The formation of Al{sub 4}C{sub 3} does not present a direct relationship with the milling time.

  12. Discovery Collection: Oyster Shells

    NSDL National Science Digital Library

    Lisa Breslof

    Oyster Shells is one of the AMNH Education Department's many collections of specimens and artifacts gathered the world over by explorers and scientists. In its online Discovery Collection form, Oyster Shells includes photographs of 15 specimens with classification and distribution details, an interactive key that guides you through specimen identification, an activity where students select and identify a specimen photograph using the interactive identification key and an Educator's Guide with suggestions for how to use the Oyster Shells Discovery Collection in the classroom.

  13. Multifunctional core–shell nanoparticles: superparamagnetic, mesoporous, and thermosensitive

    Microsoft Academic Search

    Fei YeJian; Jian Qin; Muhammet S. Toprak; Mamoun Muhammed

    Multifunctional core–shell composite nanoparticles (NPs) have been developed by the combination of three functionalities into\\u000a one entity, which is composed of a single Fe3O4 NP as the magnetic core, mesoporous silica (mSiO2) with cavities as the sandwiched layer, and thermosensitive poly(N-isopropylacrylamide-co-acrylamide) (P(NIPAAm-co-AAm)) copolymer as the outer shell. The mSiO2-coated Fe3O4 NPs (Fe3O4@mSiO2) are monodisperse and the particle sizes were varied

  14. Outer planets and icy satellites

    NASA Technical Reports Server (NTRS)

    Drobyshevski, E. M.

    1991-01-01

    The resources offered by the outer bodies in the Solar System, starting with the main belt asteroids and Jovian System, are not only larger and more diverse but may even be easier to reach than, say, those of Mars. The use of their material, including water and organic matter, depends exclusively on the general strategy of exploration of the Solar System. Of major interest in this respect are the large ice satellites - Titan, Ganymede, and Callisto. Motion through the planetary magnetospheres excites in their ice envelopes megampere currents which, in the presence of rocky, etc., inclusions with electronic conduction should lead to the bulk electrolysis of ice and accumulation in it of 2H2 + O2 in the form of a solid solution. With the concentration of 2H2 + O2 reaching about 15 wt. percent, the solution becomes capable of detonation by a strong meteoritic impact. An explosion of Ganymede's ice envelope about 0.5 By ago could account for the formation of the Trojans and irregular satellites, all known differences between Ganymede and Callisto, and many other things. The explosion of a small icy planet with M approx less than 0.5 Moon created the asteroid belt. Two to three explosions occurred on Io, and two on Europa. The specific features of the longperiod comets close to Saturn's orbit permit dating Titan's envelope explosion as 10,000 yr ago, which produced its thick atmosphere, young Saturn's rings, as well as a reservoir of ice fragments saturated by 2H2 + O2, i.e., cometary nuclei between the orbits of Jupiter and Saturn. Thus these nuclei should contain, besides organic matter, also 2H2 + O2, which could be used for their transportation as well as for fuel for spaceships. Ices of such composition can reside deep inside Deimos, the Trojans, C-asteroids, etc. The danger of a future explosion of Callisto's electrolyzed ices, which would result in a catastrophic bombardment of the Earth by comets, may be high enough to warrant a revision of the priorities and strategy of space exploration.

  15. Outer median triangles Arpad Benyi1

    E-print Network

    Curgus, Branko

    Outer median triangles ´Arp´ad B´enyi1 Department of Mathematics Western Washington University 516 of Mathematics Western Washington University 516 High Street, Bellingham Washington 98225, USA Branko

  16. Production of Polymer Core-Shell Colloids with High Uniformity via Coaxial Electrospray

    NASA Astrophysics Data System (ADS)

    Hwang, Yoon Kyun; Jeong, Unyong

    2008-03-01

    Although nanofibers fabricated by electrospinning have been attracting wide interest, the production of colloids by electrospraying has not much studied so far. We have developed a simple method for the production of core-shell colloids with high uniformity by means of the coaxial electrospray. Contrary to usual coaxial setup, the inner nozzle was set to touch the inside wall of the outer nozzle for reproducible production. A polymer solution for the core was introduced through the outer nozzle and another solution for the shell was provided through the inner nozzle. The structure of the colloids was dependent on the polymer concentration, relative feed ratio between the polymer solutions. Especially, core-shell structured colloids are our primary interest due to their promising uses in drug-delivery systems, cosmetics, and food industries. This talk will present the production of core-shell colloids consisting of two polymer components.

  17. SAXS Analysis of Shell Formation During Nanocapsule Synthesis via Inverse Miniemulsion Periphery RAFT Polymerization.

    PubMed

    Utama, Robert H; Dulle, Martin; Förster, Stephan; Stenzel, Martina H; Zetterlund, Per B

    2015-07-01

    Currently available methods for synthesis of polymeric nanocapsules only offer limited control over the shell thickness, even though it is an important parameter for various applications. Furthermore, suitable methods to critically measure this parameter in a facile way are still nonexistent. Here, lab-scale small-angle X-ray scattering (SAXS) is utilized to in situ measure the evolution of shell thickness during nanocapsule synthesis via inverse miniemulsion periphery reversible addition-fragmentation chain transfer (RAFT) polymerization (IMEPP). The measured shell thickness is consistent with estimates from the commonly used transmission electron microscopy (TEM) technique. Moreover, the individual thicknesses of two concentric shells comprising different polymeric materials (the outer shell formed via IMEPP chain extension of the inner shell) can be determined, thus further demonstrating the versatility of this approach. PMID:25882373

  18. Shell to shell energy transfer in magnetohydrodynamic dynamo simulations

    E-print Network

    Pouquet, Annick

    Shell to shell energy transfer in magnetohydrodynamic dynamo simulations Pablo Mininni, Alexandros of magnetic fields in astronomical objects. In the magnetohydrodynamic (MHD) dynamo, an initially small

  19. Planetary Aeronomy of the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Strobel, Darrell

    2012-10-01

    This talk will give a historical tour of the highlights of my research on atmospheres in the outer solar system and their interaction with the magnetospheric plasma. Topics include atmospheric photochemistry, the Io plasma torus, the Galilean satellites, and the nitrogen atmospheres on Titan, Triton, and Pluto. The important role of observations combined with theory will be emphasized. The talk will finish with current research on the role that atmospheric escape plays on atmospheric structure in the outer solar system.

  20. Discrete Shells Origami

    Microsoft Academic Search

    Rob Burgoon; Zoë J. Wood; Eitan Grinspun

    2006-01-01

    We introduce a way of simulating the creation of simple Origami (paper folding). The Origami is created in a thin shell simulation that realistically models the behavior and physical properties of paper. We demonstrate how to fold and crease the simulated paper wherever the user desires. This work employs cutting- edge advances in the field of discrete shell modeling to

  1. I Learned about Shells!

    NSDL National Science Digital Library

    Kris Ryan

    2012-06-26

    Through the use of nonfiction text, students will be able to share their prior knowledge and schema of shells. Students will practice gathering information from a text, help create a KEL chart through class and small group discussions, and will use the information learned to create an informative writing about shell animals.

  2. Cohesive Elements for Shells

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Camanho, Pedro P.; Turon, Albert

    2007-01-01

    A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design.

  3. Elbow and knee joint for hard space suits

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.

    1986-01-01

    An elbow or knee joint for a hard space suit or similar usage is formed of three serially connected rigid sections which have truncated spherical configurations. The ends of each section form solid geometric angles, and the sections are interconnected by hermetically sealed ball bearings. The outer two sections are fixed together for rotation in a direction opposite to rotation of the center section. A preferred means to make the outer sections track each other in rotation comprises a rotatable continuous bead chain which engages sockets circumferentially spaced on the facing sides of the outer races of the bearings. The joint has a single pivot point and the bearing axes are always contained in a single plane for any articulation of the joint. Thus flexure of the joint simulates the coplanar flexure of the knee or elbow and is not susceptible to lockup.

  4. Organizing Your Hard Disk.

    ERIC Educational Resources Information Center

    Stocker, H. Robert; Hilton, Thomas S. E.

    1991-01-01

    Suggests strategies that make hard disk organization easy and efficient, such as making, changing, and removing directories; grouping files by subject; naming files effectively; backing up efficiently; and using PATH. (JOW)

  5. Replicated Nickel Optics for the Hard-X-Ray Region

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian

    2005-01-01

    Replicated nickel optics has been used extensively in x-ray astronomy, most notable for the XMM/Newton mission. Thc combination of relative ease of fabrication and the inherent stability of full shell optics, make them FIJI attractive approach for medium-resolution, high-throughput applications. MSFC has been developing these optics for use in the hard-x-ray region. Efforts at improving the resolution of these, particularly the very-thin shells required to meet thc weight budget of future missions, will be described together with the prospects for significant improvements down to the 5-arcsec level.

  6. Failure of Viral Shells

    NASA Astrophysics Data System (ADS)

    Klug, William S.; Bruinsma, Robijn F.; Michel, Jean-Philippe; Knobler, Charles M.; Ivanovska, Irena L.; Schmidt, Christoph F.; Wuite, Gijs J. L.

    2006-12-01

    We report a combined theoretical and experimental study of the structural failure of viral shells under mechanical stress. We find that discontinuities in the force-indentation curve associated with failure should appear when the so-called Föppl von Kármán (FvK) number exceeds a critical value. A nanoindentation study of a viral shell subject to a soft-mode instability, where the stiffness of the shell decreases with increasing pH, confirms the predicted onset of failure as a function of the FvK number.

  7. A rigid and weathered ice shell on Titan.

    PubMed

    Hemingway, D; Nimmo, F; Zebker, H; Iess, L

    2013-08-29

    Several lines of evidence suggest that Saturn's largest moon, Titan, has a global subsurface ocean beneath an outer ice shell 50 to 200?kilometres thick. If convection is occurring, the rigid portion of the shell is expected to be thin; similarly, a weak, isostatically compensated shell has been proposed to explain the observed topography. Here we report a strong inverse correlation between gravity and topography at long wavelengths that are not dominated by tides and rotation. We argue that negative gravity anomalies (mass deficits) produced by crustal thickening at the base of the ice shell overwhelm positive gravity anomalies (mass excesses) produced by the small surface topography, giving rise to this inverse correlation. We show that this situation requires a substantially rigid ice shell with an elastic thickness exceeding 40 kilometres, and hundreds of metres of surface erosion and deposition, consistent with recent estimates from local features. Our results are therefore not compatible with a geologically active, low-rigidity ice shell. After extrapolating to wavelengths that are controlled by tides and rotation, we suggest that Titan's moment of inertia may be even higher (that is, Titan may be even less centrally condensed) than is currently thought. PMID:23985871

  8. Dynamics of a suspension of interacting yolk-shell particles

    SciTech Connect

    Chen, Wei-Ren [ORNL; Sanchez-Diaz, Luis E [ORNL

    2014-01-01

    In this work we study the self-diusion properties of a liquid of hollow spherical particles (shells) bearing a smaller solid sphere in their interior (yolks). We model this system using purely repulsive hard-body interactions between all (shell and yolk) particles, but assume the presence of a background ideal solvent such that all the particles execute free Brownian motion between collisions, characterized by short-time self-diusion coecients D0 s for the shells and D0 y for the yolks. Using a softened version of these interparticle potentials we perform Brownian dynamics simulations to determine the mean squared displacement and intermediate scattering function of the yolk-shell complex. These results can be understood in terms of a set of eective Langevin equations for the N interacting shell particles, pre-averaged over the yolks' degrees of freedom, from which an approximate self-consistent description of the simulated self-diusion properties can be derived. Here we compare the theoretical and simulated results between them, and with the results for the same system in the absence of yolks. We nd that the yolks, which have no eect on the shell-shell static structure, in uence the dynamic properties in a predictable manner, fully captured by the theory.

  9. Improved Method of Design for Folding Inflatable Shells

    NASA Technical Reports Server (NTRS)

    Johnson, Christopher J.

    2009-01-01

    An improved method of designing complexly shaped inflatable shells to be assembled from gores was conceived for original application to the inflatable outer shell of a developmental habitable spacecraft module having a cylindrical mid-length section with toroidal end caps. The method is also applicable to inflatable shells of various shapes for terrestrial use. The method addresses problems associated with the assembly, folding, transport, and deployment of inflatable shells that may comprise multiple layers and have complex shapes that can include such doubly curved surfaces as toroids and spheres. One particularly difficult problem is that of mathematically defining fold lines on a gore pattern in a double- curvature region. Moreover, because the fold lines in a double-curvature region tend to be curved, there is a practical problem of how to implement the folds. Another problem is that of modifying the basic gore shapes and sizes for the various layers so that when they are folded as part of the integral structure, they do not mechanically interfere with each other at the fold lines. Heretofore, it has been a common practice to design an inflatable shell to be assembled in the deployed configuration, without regard for the need to fold it into compact form. Typically, the result has been that folding has been a difficult, time-consuming process resulting in a An improved method of designing complexly shaped inflatable shells to be assembled from gores was conceived for original application to the inflatable outer shell of a developmental habitable spacecraft module having a cylindrical mid-length section with toroidal end caps. The method is also applicable to inflatable shells of various shapes for terrestrial use. The method addresses problems associated with the assembly, folding, transport, and deployment of inflatable shells that may comprise multiple layers and have complex shapes that can include such doubly curved surfaces as toroids and spheres. One particularly difficult problem is that of mathematically defining fold lines on a gore pattern in a double- curvature region. Moreover, because the fold lines in a double-curvature region tend to be curved, there is a practical problem of how to implement the folds. Another problem is that of modifying the basic gore shapes and sizes for the various layers so that when they are folded as part of the integral structure, they do not mechanically interfere with each other at the fold lines. Heretofore, it has been a common practice to design an inflatable shell to be assembled in the deployed configuration, without regard for the need to fold it into compact form. Typically, the result has been that folding has been a difficult, time-consuming process resulting in a

  10. MHD processes in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.

    1984-01-01

    The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.

  11. Shock interactions in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.

    1991-01-01

    The results of recent simulations of the nonlinear evolution of the solar wind structures are reviewed, emphasizing theoretical development and the shock interactions model (SIM). Models which calculate jumps in flow properties across shocks without using exact Rankine-Hugoniot relations and models which do use them are addressed. The development of a computer code and some basic applications to the SIM are considered. Simulation results for the formation and propagation of forward-reverse shock pairs and the collision and merging of shocks are shown. Two studies which used the SIM to simulate nonlinear evolution of large-scale solar wind structures in the outer heliosphere are examined, and the SIM is then applied to study the heating of the solar wind in the outer heliosphere. The results support the hypothesis that shocks are mainly responsible for the heating of the solar wind plasma in the outer heliosphere at least up to 30 AU.

  12. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, Thomas P. (Belleville, MI)

    1991-01-01

    A process for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry.

  13. Hollow spherical shell manufacture

    DOEpatents

    O'Holleran, T.P.

    1991-11-26

    A process is disclosed for making a hollow spherical shell of silicate glass composition in which an aqueous suspension of silicate glass particles and an immiscible liquid blowing agent is placed within the hollow spherical cavity of a porous mold. The mold is spun to reduce effective gravity to zero and to center the blowing agent, while being heated so as to vaporize the immiscible liquid and urge the water carrier of the aqueous suspension to migrate into the body of the mold, leaving a green shell compact deposited around the mold cavity. The green shell compact is then removed from the cavity, and is sintered for a time and a temperature sufficient to form a silicate glass shell of substantially homogeneous composition and uniform geometry. 3 figures.

  14. Prey-induced changes to a predator's behaviour and morphology: Implications for shell–claw covariance in the northwest Atlantic

    Microsoft Academic Search

    Timothy C. Edgell; Rémy Rochette

    2009-01-01

    Whereas many plasticity studies demonstrate the importance of inducible defences among prey, far fewer investigate the potential role of inducible offences among predators. Here we ask if natural differences in a snail's shell hardness can induce developmental changes to a predatory crab's claw size. To do this, we fed Littorina obtusata snails from either thick- or thin-shelled populations to captive

  15. Silica-polypyrrole core-shell nanocomposites as active materials for dielectrophoretic displays.

    PubMed

    Miomandre, F; Audebert, P; Bonnett, J P; Brosseau, A; Perriat, P; Weisbuch, C; Wen, W; Sheng, P

    2008-09-01

    A direct route to silica-polypyrrole core-shell nanoparticles has been used to design new nanocomposites, in which the conducting part is then wrapped by an external silica shell in order to have finally neutral nanoparticles. The nanocomposites are characterized by TEM, spectroscopy, electrochemistry and thermal gravimetric analysis, demonstrating that the external silica shell actually insulates the conjugated polymer from the outer medium. Finally the electrorheological properties of these nanocomposites are checked in a dielectrophoretic device in which the motion of the particles induced by an external electric field can be used to monitor a switch of the light transmission properties. PMID:19049025

  16. The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting

    SciTech Connect

    Norouzi, Saeid [MAPNA GROUP Co (Iran, Islamic Republic of); Farhangi, Hassan [School of Metallurgy and Materials Engineering, University of Tehran (Iran, Islamic Republic of)

    2011-01-17

    The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: (1) the ductile region in the outer layer; and (2) the inner region of liquid embrittlement.

  17. The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting

    NASA Astrophysics Data System (ADS)

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-01

    The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: 1) the ductile region in the outer layer; and 2) the inner region of liquid embrittlement.

  18. Ptolemy's treatment of the outer planets

    NASA Astrophysics Data System (ADS)

    Duke, Dennis

    2005-01-01

    The purpose of this paper is to investigate whether for the outer planets Ptolemy followed his otherwise consistent custom of describing a scenario that did not happen as he says, or whether, at least for the outer planets, he left us a more accurate rendition of events. The detailed reconstructions of Ptolemy's calculations that follow show that, at least in the Almagest, Ptolemy is a writer with consistent habits when it comes to observations. We begin by reviewing, with minimal editorial comment, Ptolemy's calculations for each planet.

  19. Is the outer Solar System chaotic?

    E-print Network

    Wayne B. Hayes

    2007-02-07

    The existence of chaos in the system of Jovian planets has been in question for the past 15 years. Various investigators have found Lyapunov times ranging from about 5 millions years upwards to infinity, with no clear reason for the discrepancy. In this paper, we resolve the issue. The position of the outer planets is known to only a few parts in 10 million. We show that, within that observational uncertainty, there exist Lyapunov timescales in the full range listed above. Thus, the ``true'' Lyapunov timescale of the outer Solar System cannot be resolved using current observations.

  20. Drift Phase Structure as a Diagnostic of Outer Belt Radial Transport

    NASA Astrophysics Data System (ADS)

    OBrien, Paul; Mulligan Skov, Tamitha; Claudepierre, Seth; Roeder, James; Fennell, Joseph; Green, Janet

    2015-04-01

    In the outer radiation belt, quasilinear diffusive radial transport of electrons assumes a superposition of very many tiny radial displacements. Recent test particle simulations have called into question the appropriateness of the quasilinear approximation. Specifically, magnetic impulses and drift-resonant phenomena may not constitute very many, and probably do not constitute tiny, radial displacements. Quasilinear, impulsive, and drift resonant radial transport processes all have different signatures in the drift phase structure of electrons. We present an initial case study of examples of the different categories of drift phase structure, with the aim of eventually performing a statistical characterization: how significant is each kind of transport during a storm, and how does the type of solar wind driver affect the distribution of radial transport mechanisms? We use data from the SCATHA and GOES missions whose orbits provide 100% residence time on the drift shells through which electrons must travel to reach the outer zone from the plasma sheet.

  1. Commissioning of the 4 K Outer Cryostat for the CUORE Experiment

    NASA Astrophysics Data System (ADS)

    Ferri, E.; Alessandria, F.; Biassoni, M.; Bucci, C.; Ceruti, G.; Chiarini, A.; Clemenza, M.; Cremonesi, O.; Datskov, V.; Dossena, S.; Faverzani, M.; Franceschi, M. A.; Gaigher, R.; Gorla, P.; Guetti, M.; Ligi, C.; Napolitano, T.; Nucciotti, A.; Pelosi, A.; Perego, M.; Previtali, E.; Sisti, M.; Taffarello, L.; Terranova, F.

    2014-09-01

    The Cryogenic Underground Observatory for Rare Events (CUORE) is a 1-ton scale bolometric experiment. The CUORE detector is an array of 988 TeO crystals arranged in a cylindrical, compact, and granular structure of 19 towers. These detectors will need a base temperature lower than 10 mK in order to meet the performance specifications. To cool the CUORE detector, a large cryogen free cryostat with five pulse tubes and one custom designed high power dilution refrigerator has been designed. The three vessels that form the outer shell of the CUORE cryostat were produced in 2012 and are now assembled in the Gran Sasso National Laboratories (LNGS). We report here the detailed description of the 4 K outer cryostat for the CUORE experiment together with the results of the validation tests done at the production site in 2012 and of the first commissioning to 4 K at LNGS in 2013.

  2. Drift Phase Structure As a Diagnostic of Outer Belt Radial Transport

    NASA Astrophysics Data System (ADS)

    O'Brien, T. P., III; Mulligan, T. L.; Claudepierre, S. G.; Roeder, J. L.; Green, J. C.; Fennell, J.

    2014-12-01

    In the outer radiation belt, quasilinear diffusive radial transport of electrons assumes a superposition of very many tiny radial displacements. Recent test particle simulations have called into question the appropriateness of the quasilinear approximation. Specifically, magnetic impulses and drift-resonant phenomena may not constitute very many, and probably do not constitute tiny, radial displacements. Quasilinear, impulsive, and drift resonant radial transport processes all have different signatures in the drift phase structure of electrons. We present an initial case study of examples of the different categories of drift phase structure, with the aim of eventually performing a statistical characterization: how significant is each kind of transport during a storm, and how does the type of solar wind driver affect the distribution of radial transport mechanisms? We use data from the SCATHA and GOES missions whose orbits provide 100% residence time on the drift shells through which electrons must travel to reach the outer zone from the plasma sheet.

  3. Geographic variation of shell bionts in the deep-sea snail Gaza

    NASA Astrophysics Data System (ADS)

    Voight, Janet R.; Walker, Sally E.

    1995-08-01

    Recent studies of bathyal environments indicate that microhabitats contribute significantly to biodiversity. We suggest that microhabitats may also be useful in direct comparisons of biotic diversity patterns across large areas. Using a technique developed by palaeontologists, we document the diversity and abundance of taxa occurring on the hard substrate provided by gastropod shells of the bathyal (200 m) trochid gastropod Gaza. Because the shell surfaces are comparable, shell-associated biota and their diversity may be contrasted across basins with relatively few compounding variables. Animals found attached to the outside of the shells, epibionts, included folliculinids, encrusting bryozoans and foraminifera; within the shell, endobiontic spionid polychaetes had occupied the columella of the shell, apparently destroying both the protoconch and part of the shell's base. Both types of bionts were common on shells from continental margins of North and South America but were wholly absent on shells from the Lesser Antilles. Hypotheses that shell depth distributions (372-910 m) and shell age, biont dispersal potential and biotic interactions contribute to the large-scale differences in biont distribution are considered but rejected in favour of the hypothesis that terrigenous sediments and their associated nutrients are primary contributors to the observed geographic pattern.

  4. Prevention of the Outer Space Weaponization

    NASA Astrophysics Data System (ADS)

    Zhukov, Gennady P.

    2002-01-01

    9 states. The satellites of various functions (early warning, communication, data acquisition, reconnaissance and navigation) were actively used and continue to be used with the purposes of raising efficiency of ground armed forces, especially in fight against international terrorism. At the same time such satellites are not a weapon in the sense of that word since they do not create the threats of armed attack in outer space or from outer space. Moreover, they promote maintaining of stability in the international relations. For this reason the reconnaissance and data acquisition satellites used for the verification of observance by States of the arms limitation agreements are under international protection as national technical means of the control. Similar protection is enjoyed by the early warning satellites. With the help of space communication facilities the more reliable operative connection of the statesmen is organized in the strained situations. By this way the probability of making of the incorrect retaliatory decisions in critical political situations is reduced. At the same time it's necessary to take into consideration that the activities of such satellite systems are tightly connected with ground armed forces of the states. the earth, what from the point of view of international law may be qualified as establishing a partial demilitarization regime in outer space. After the prohibition of anti-satellite weapons (ASAT) and anti-satellite (ASAT) weapons it will be possible to speak about establishing of an international legal regime of complete demilitarization in outer space eliminating any kinds of weapon from outer space. in a peaceful time. weaponization.The main task of this paper is to analyze and to discuss the present binding regime of the outer space deweaponization and particular measures on consolidation and strengthening of this regime. agreements of the Russian Federation and the USA into multilateral Treaties. Such "immunity" would cover all operating space objects, irrespective of their military or civil designation. This approach is quite justified taking into consideration that military sattelites enhanced international peace and security and had broad advantages, such as treaty compliance and monitoring, the global positioning system, counter-terrorism and sanctions enforcement. Many examples of the last years demonstrate the tendency of engagement of military satellites into commercial space services. transparency on the pre-launch stage of space activity, including satellite inspection before ignition. Objects Flight Path Tracking. implemantation of a non-use of force and threat of force - a fundamental principle of modern international law. This implies the application of the menshened principle of international law by means of a treaty to the outer space activities with reference to the actions made in outer space, or directed from outer space against targets on the Earth as well as directed from the Earth against objects moving in outer space. to the possibility of conclusion in future of a multilateral arrangement on the prohibition of the space-based ABM. Accordingly, it is discussed the problem of an efficient international control over the prohibition of placement of the above mentioned weapons into outer space. to the challenges of the new millennium. 8

  5. Radial variations in modulus and hardness in SCS-6 silicon carbide fibers

    SciTech Connect

    Mann, A.B.; Weihs, T.P. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Materials Science and Engineering; Balooch, M.; Kinney, J.H. [Lawrence Livermore National Lab., CA (United States). Dept. of Chemistry and Materials Science

    1999-01-01

    The mechanical properties of SCS-6 SiC fibers were measured as a function of fiber radius using nanoindentation techniques. Hardness and Young`s modulus were characterized for the material in all of the major regions of these fibers: the carbon core, the graphitic core coating, the inner SiC sheath, and the outer SiC sheath. The carbon core of the fibers was determined to be uniform in properties but extremely compliant. Young`s modulus of 28 GPa and a hardness of 4.2 GPa were measured. The graphitic core coating was found to exhibit considerable anelasticity and to have both a low modulus (21 GPa) and a low hardness (1.7 GPa). The inner sheath of the fiber, which contained a varying chemistry, showed a sharp increase in stiffness and hardness from the inner core. Modulus and hardness increased by an order of magnitude over just 1 or 2 {micro}m when transversing radially away from the core into the SiC. This change in properties was pronounced and clearly defined. The outer sheath, which contained a uniform chemistry and microstructure, was consistently stiff and hard when transversing radially. The average modulus and hardness for the full fiber was 333 GPa. The values reported for Young`s modulus and hardness clearly showed that the mechanical properties of SCS SiC fibers exhibit dramatic changes across their diameters.

  6. Review of recovery and recolonization of hard substrate communities of the Outer Continental Shelf. Final report

    Microsoft Academic Search

    Lissner

    1988-01-01

    This report summarizes knowledge of how marine benthic communities off California respond to both natural and anthropogenic disturbances. The results from the study will aid the MMS in making environmental assessments and management decisions associated with potential oil and gas leasing, exploration, and development activities. The objectives of the report on recovery and recolonization are: (1) to review relevant recovery

  7. Mesh reconstruction of hearing aid shells from unorganized 3D point-cloud

    Microsoft Academic Search

    Gabriella Tognola; Marta Parazzini; Paolo Ravazzani; Ferdinando Grandori; Alessandro Pesatori; Michele Norgia; Cesare Svelto

    2005-01-01

    A novel system for 3D laser scanning and image reconstruction is applied to scan and reconstruct the surface of ear canal impressions, which are used by the current available technology to design silicon hearing aid shells (or earmolds). Earmolds couple the aid with the user's ear and must fit the subject's outer ear canal in order to assure good performance

  8. Scanning electron microscope studies of the egg shell in some anostraca (Crustacea: Branchiopoda)

    Microsoft Academic Search

    Barbara M. Gilchrist

    1978-01-01

    The tertiary shell of the eggs of anostracan crustaceans consists of two layers, an outer cortex and an inner alveolar layer. Scanning electron microscope studies show that, in most species, these layers are separated by a subcortical space which intercommunicates with spaces in the cortex and with the meshwork of the alveolar layer. No evidence was found for direct communication

  9. Singular layers for transmission problems in thin shallow shell theory: Rigid junction case

    Microsoft Academic Search

    Ismail Merabet; D. A. Chacha; S. Nicaise

    2010-01-01

    In this Note we study two-dimensional transmission problems for the linear Koiter's model of an elastic multi-structure composed of two thin shallow shells. This work enters in the framework of singular perturbation of problems depending on a small parameter ?. The formal limit problem fails to give a solution satisfying all boundary and transmission conditions; it gives only the outer

  10. Structural basis for outer membrane lipopolysaccharide insertion.

    PubMed

    Dong, Haohao; Xiang, Quanju; Gu, Yinghong; Wang, Zhongshan; Paterson, Neil G; Stansfeld, Phillip J; He, Chuan; Zhang, Yizheng; Wang, Wenjian; Dong, Changjiang

    2014-07-01

    Lipopolysaccharide (LPS) is essential for most Gram-negative bacteria and has crucial roles in protection of the bacteria from harsh environments and toxic compounds, including antibiotics. Seven LPS transport proteins (that is, LptA-LptG) form a trans-envelope protein complex responsible for the transport of LPS from the inner membrane to the outer membrane, the mechanism for which is poorly understood. Here we report the first crystal structure of the unique integral membrane LPS translocon LptD-LptE complex. LptD forms a novel 26-stranded ?-barrel, which is to our knowledge the largest ?-barrel reported so far. LptE adopts a roll-like structure located inside the barrel of LptD to form an unprecedented two-protein 'barrel and plug' architecture. The structure, molecular dynamics simulations and functional assays suggest that the hydrophilic O-antigen and the core oligosaccharide of the LPS may pass through the barrel and the lipid A of the LPS may be inserted into the outer leaflet of the outer membrane through a lateral opening between strands ?1 and ?26 of LptD. These findings not only help us to understand important aspects of bacterial outer membrane biogenesis, but also have significant potential for the development of novel drugs against multi-drug resistant pathogenic bacteria. PMID:24990744

  11. Outer Billiards on Kites Richard Evan Schwartz

    E-print Network

    Schwartz, Richard Evan

    -preserving actions. There is a lot left to learn about these kinds of dynamical systems, and a good un- derstanding proof uncovers some of the deep structure underlying outer billiards on kites, and relates the subject, Karen and Uri. 3 #12;Table of Contents 1. Introduction 6 Part I 16 2. The Arithmetic Graph 17 3

  12. The magnetospheres of the outer planets

    SciTech Connect

    Mcnutt, R.L., Jr. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Research on the magnetospheres of all of the outer planets including Jupiter, Uranus, Neptune, and Pluto is reviewed for the 1987-1990 time period. Particular attention is given to magnetospheric structure, plasma transport, Jovian aurora, Io and the plasma torus, Titan and its magnetospheric interactions, rings and dusty plasmas, magnetospheric convection, and satellite interactions.

  13. The Outer Continental Shelf Environmental Assessment Program

    Microsoft Academic Search

    David A. Hale

    1986-01-01

    The Outer Continental Shelf Environmental Assessment Program (OCSEAP) is a multidisciplinary program established to provide timely environmental information for decisions on offshore oil and gas development. One of OCSEAP's primary tasks is to provide information on the transport of pollutants in the marine environment. OCSEAP's science program is reviewed in relation to this task. Utilization of OCSEAP's extensive physical oceanographic

  14. The processing of materials in outer space

    NASA Technical Reports Server (NTRS)

    Gelles, S. H.; Colling, E. W.

    1977-01-01

    Zero-gravity environment may lead to fabrication of new and improved materials. According to comprehensive study of application of this promising technology to superconducting and electrical contact materials, outer space processing could improve microstructure and homogeneity of many single and multicomponent systems formed from solidification of fluid phases. New structures that are impossible to form terrestrially may also be accessible in space environment.

  15. The Outer Planets\\/Solar Probe Project

    Microsoft Academic Search

    R. W. Maddock; K. B. Clark; C. A. Henry; P. J. Hoffman

    1999-01-01

    As part of NASA's Origins program, the Outer Planets\\/Solar Probe Project was established in early 1998. This flight project is composed of three challenging and exciting missions which span the far reaches of the solar system. Europa Orbiter, with a planned launch in November of 2003, will travel to Jupiter's moon, Europa, in search of a subsurface liquid water ocean

  16. Physical Mechanisms and Scaling Laws of K-Shell Double Photoionization

    NASA Astrophysics Data System (ADS)

    Hoszowska, J.; Kheifets, A. K.; Dousse, J.-Cl.; Berset, M.; Bray, I.; Cao, W.; Fennane, K.; Kayser, Y.; Kav?i?, M.; Szlachetko, J.; Szlachetko, M.

    2009-02-01

    We report on the photon energy dependence of the K-shell double photoionization (DPI) of Mg, Al, and Si. The DPI cross sections were derived from high-resolution measurements of x-ray spectra following the radiative decay of the K-shell double vacancy states. Our data evince the relative importance of the final-state electron-electron interaction to the DPI. By comparing the double-to-single K-shell photoionization cross-section ratios for neutral atoms with convergent close-coupling calculations for He-like ions, the effect of outer shell electrons on the K-shell DPI process is assessed. Universal scaling of the DPI cross sections with the effective nuclear charge for neutral atoms is revealed.

  17. Work Hard. Be Nice

    ERIC Educational Resources Information Center

    Mathews, Jay

    2009-01-01

    In 1994, fresh from a two-year stint with Teach for America, Mike Feinberg and Dave Levin inaugurated the Knowledge Is Power Program (KIPP) in Houston with an enrollment of 49 5th graders. By this Fall, 75 KIPP schools will be up and running, setting children from poor and minority families on a path to college through a combination of hard work,…

  18. Soft Skills, Hard Science

    E-print Network

    Wu, Mingshen

    Soft Skills, Hard Science: A Program to Improve Job Placement of STEM Graduates with Disabilities 2013 Women & Science Conference1 Wednesday, May 22, 13 #12;Why focus on soft skills? What comes to mind rated recent grads on same skills Perception Reality 8 Wednesday, May 22, 13 #12;what are soft skills

  19. Hard (and Soft) Facts.

    ERIC Educational Resources Information Center

    Kennedy, Mike

    1999-01-01

    Provides guidelines to help schools maintain hard floors and carpets, including special areas in schools and colleges that need attention and the elements needed to have a successful carpet-maintenance program. The importance of using heavy equipment to lessen time and effort is explained as are the steps maintenance workers can take to make the…

  20. Quantitative Ray Methods for Scattering of Sound by Spherical Shells.

    NASA Astrophysics Data System (ADS)

    Kargl, Steven Gregory

    1990-01-01

    The application of ray methods to the scattering of high-frequency plane waves from evacuated elastic spherical shells is investigated. The investigation of ray methods for spherical shells is a precursor to the application of such methods to shells having more complicated shapes. The scattered pressure in the farfield of the shell is p _{sc} = p_{i}(a/2r)f( theta)exp(ikr) where p_{i } is the plane wave amplitude. The outer radius of the shell is a, h = a - b is the shell's thickness, and r is the distance to an observation point. Ray models are developed to synthesize the form function f( theta,ka) where k is the wavenumber of the incident wave and theta is the scattering angle. The forward scattering amplitude, f(theta = 0), is related to the extinction cross section, sigma_{e}, by the optical theorem. If the absorption by the scatterer is negligible, then sigma_{rm e} is equal to the scattering cross section sigma_{t}. A ray synthesis partitions f(theta = 0) into a component for ordinary forward diffraction about the shell, f_{FD}, and contributions from surface guided elastic waves. For high -frequency scattering, the relevant surface guided elastic waves are leaky Lamb waves. A similar ray synthesis of the backscattering amplitude f(theta=pi) contains a specular reflection component, f _{^}(theta=pi), and leaky Lamb wave contributions. A generalization of the geometrical theory of diffraction is employed to synthesize f_{l}(theta=0, {ka }) and f_{l}(theta= pi, {ka}) for the lth leaky Lamb wave contribution. The syntheses for forward and backwards scattering correctly describe the leaky Lamb wave contributions and are expressible in a Fabry-Perot resonator form. While the ray description of backscattering ordinarily accurately reproduces exact computations and experiments with tone burst, certain anomalies are discussed. A ray synthesis of f_{^} demonstrates a significant longitudinal resonance effect when k _{L}h = npi,n = 1, 2,..., where k_ {L} = omega/c _{L} is the longitudinal wavenumber within the shell. The analysis of f_{^ } is for an elastic material with vanishing shear velocity. The relevant range of ka is 7 <=q ka <=q 100. The shell is surrounded by water and is composed of 440c stainless steel with inner-to-outer radii ratio b/a = 0.838.

  1. Effect of shells on photoluminescence of aqueous CdTe quantum dots

    SciTech Connect

    Yuan, Zhimin; Yang, Ping, E-mail: mse_yangp@ujn.edu.cn

    2013-07-15

    Graphical abstract: Size-tunable CdTe coated with several shells using an aqueous solution synthesis. CdTe/CdS/ZnS quantum dots exhibited high PL efficiency up to 80% which implies the promising applications for biomedical labeling. - Highlights: • CdTe quantum dots were fabricated using an aqueous synthesis. • CdS, ZnS, and CdS/ZnS shells were subsequently deposited on CdTe cores. • Outer ZnS shells provide an efficient confinement of electron and hole inside the QDs. • Inside CdS shells can reduce the strain on the QDs. • Aqueous CdTe/CdS/ZnS QDs exhibited high stability and photoluminescence efficiency of 80%. - Abstract: CdTe cores with various sizes were fabricated in aqueous solutions. Inorganic shells including CdS, ZnS, and CdS/ZnS were subsequently deposited on the cores through a similar aqueous procedure to investigate the effect of shells on the photoluminescence properties of the cores. In the case of CdTe/CdS/ZnS quantum dots, the outer ZnS shell provides an efficient confinement of electron and hole wavefunctions inside the quantum dots, while the middle CdS shell sandwiched between the CdTe core and ZnS shell can be introduced to obviously reduce the strain on the quantum dots because the lattice parameters of CdS is situated at the intermediate-level between those of CdTe and ZnS. In comparison with CdTe/ZnS core–shell quantum dots, the as-prepared water-soluble CdTe/CdS/ZnS quantum dots in our case can exhibit high photochemical stability and photoluminescence efficiency up to 80% in an aqueous solution, which implies the promising applications in the field of biomedical labeling.

  2. Dyson shells: a retrospective

    NASA Astrophysics Data System (ADS)

    Bradbury, Robert J.

    2001-08-01

    More than 40 years have passed since Freeman Dyson suggested that advanced technological civilizations are likely to dismantle planets in their solar systems to harvest all of the energy their stars wastefully radiate into space. Clearly this was an idea that was ahead of its time. Since that time, dozens of SETI searches have been conducted and almost all of them have focused their attention on stars which by definition cannot be the advanced civilizations that Dyson envisioned. I will review the data that created the confusion between Dyson spheres and Dyson shells. The sources that disprove Dyson spheres while still allowing Dyson shells will be discussed. The use of outmoded ideas that have biased the few searches for Dyson Shells that have occurred will be pointed out. An update of the concept of Dyson shells to include our current knowledge of biotechnology, nanotechnology and computer science will be explored. Finally, an approach to setting limits on the abundance of Dyson shells in our galaxy using existing optical astronomical data and future optical satellites will be proposed.

  3. Convective motions in a spherical shell

    NASA Technical Reports Server (NTRS)

    Zebib, A.; Goyal, A. K.; Schubert, G.

    1985-01-01

    We compute the axisymmetric convective motions that exist in a spherical shell heated from below with inner to outer radius ratio equal to 0.5. The boundaries are stress-free and gravity is directly proportional to radius. Accurate solutions at large Rayleigh numbers, O(100000), are made feasible by a spectral method that employs diagonal-mode truncation. By examining the stability of axisymmetric motions it is inferred that the preferred form of convection varies dramatically according to the value of the Rayleigh number. While axisymmetric motions with different patterns may exist for modestly nonlinear convection, only a single motion persists at sufficiently large values of the Rayleigh number. This circulation is symmetric about the equator and has two meridional cells with rising motion at the poles. Instability of this single axisymmetric motion determines that the preferred pattern of three-dimensional convection has one azimuthal wave.

  4. Convection patterns in a spherical fluid shell.

    PubMed

    Feudel, F; Bergemann, K; Tuckerman, L S; Egbers, C; Futterer, B; Gellert, M; Hollerbach, R

    2011-04-01

    Symmetry-breaking bifurcations have been studied for convection in a nonrotating spherical shell whose outer radius is twice the inner radius, under the influence of an externally applied central force field with a radial dependence proportional to 1/r(5). This work is motivated by the GeoFlow experiment, which is performed under microgravity condition at the International Space Station where this particular central force can be generated. In order to predict the observable patterns, simulations together with path-following techniques and stability computations have been applied. Branches of axisymmetric, octahedral, and seven-cell solutions have been traced. The bifurcations producing them have been identified and their stability ranges determined. At higher Rayleigh numbers, time-periodic states with a complex spatiotemporal symmetry are found, which we call breathing patterns. PMID:21599292

  5. Statistical theory of correlations in random packings of hard particles.

    PubMed

    Jin, Yuliang; Puckett, James G; Makse, Hernán A

    2014-05-01

    A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the n-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom up. A progressive expansion into a shell of particles converges in the large layer limit under a Kirkwood-like approximation of higher-order correlations. We apply the formalism to hard disks and predict the density of two-dimensional random close packing (RCP), ?(rcp) = 0.85 ± 0.01, and random loose packing (RLP), ?(rlp) = 0.67 ± 0.01. Our theory also predicts a phase diagram and angular correlation functions that are in good agreement with experimental and numerical data. PMID:25353787

  6. An analysis of disk flutter in hard disk drives in aerodynamic simulations

    Microsoft Academic Search

    Masayuki Tatewaki; Naozumi Tsuda; Tsugito Maruyama

    2001-01-01

    In this paper, using aerodynamic numerical analysis, we investigate mechanisms causing disk flutter in hard disk drives. A computer simulation model of three stacked disks was calculated using the finite-difference method with the LES model of turbulence. As a result, secondary airflows were found to move upward and downward though a shroud gap around the outer edge of the disk.

  7. A dual-stage control design for high track per inch hard disk drives

    Microsoft Academic Search

    Guoxiao Guo; Qi Hao; Teck-Seng Low

    2001-01-01

    This paper proposes an optimization based control scheme for a dual-stage hard disk drive servo system to maximize the tracking accuracy given the actuator bandwidth limitations without knowing the mechanical disturbance model. We proposed to add an outer loop, selected based on optimization of the Youla parameters, to the usual dual-stage controller for tracking accuracy improvement. The Youla parameters are

  8. Co-electrospinning of core-shell fibers using a single-nozzle technique.

    PubMed

    Bazilevsky, Alexander V; Yarin, Alexander L; Megaridis, Constantine M

    2007-02-27

    Co-electrospinning is ideally suited for fabricating continuous fibers encasing materials within a polymer sleeve, but requires relatively complex coannular nozzles. A single-nozzle co-electrospinning technique is demonstrated using blends of poly(methyl methacrylate) (PMMA)/polyacrylonitrile (PAN) solutions in dimethylformamide (DMF). The as-spun fibers have outer diameters in the range of 0.5-5 microm and possess a core-shell structure similar to that attained via coannular nozzles. The technique relies on the precipitation of PMMA solution droplets, which become trapped at the base of the Taylor cone issuing the PAN solution jet from its tip. A theoretical analysis shows that the outer shell flow is sufficiently strong to stretch the inner droplet into the Taylor cone, thus forming a core-shell jet. The method seems attractive for technological applications involving macroscopically long and radially inhomogeneous or hollow nano/micro fibers. PMID:17266345

  9. 76 FR 63654 - Outer Continental Shelf Official Protraction Diagram, Lease Maps, and Supplemental Official Outer...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-13

    ...Supplemental Official Outer Continental Shelf Block Diagrams AGENCY: Bureau of Ocean Energy...Lease Maps, and Supplemental Official OCS Block Diagrams (SOBDs); Correction...Maps, and Supplemental Official OCS Shelf Block Diagrams'' that contained an...

  10. Sensational spherical shells

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Kendall, J. M., Jr.; Bahrami, P. A.; Wang, T. G.

    1986-01-01

    Fluid-dynamic and capillary forces can be used to form nearly perfect, very small spherical shells when a liquid that can solidify is passed through an annular die to form an annular jet. Gravity and certain properties of even the most ideal materials, however, can cause slight asymmetries. The primary objective of the present work is the control of this shell formation process in earth laboratories rather than space microgravity, through the development of facilities and methods that minimize the deleterious effects of gravity, aerodynamic drag, and uncontrolled cooling. The spherical shells thus produced can be used in insulation, recyclable filter materials, fire retardants, explosives, heat transport slurries, shock-absorbing armor, and solid rocket motors.

  11. Abundance Measurements in the Outer Galaxy

    NASA Astrophysics Data System (ADS)

    Rudolph, Alexander L.; Simpson, Janet P.; Erickson, Edwin F.; Haas, Michael R.; Fich, Michel

    1994-12-01

    We have observed far-infrared fine structure lines of N, O, and S in five H II regions in the far outer Galaxy (R > 15 kpc) using the Kuiper Airborne Observatory (KAO). These sources were selected from a radio continuum search we made with the VLA and Australia Telescope Compact Array. The far-infrared line observations, combined with the radio continuum fluxes from these regions, allow us to determine the abundances relative to hydrogen of these three elements in an extreme part of the Galaxy. These observations have extended, by almost a factor of 2, the range of galactocentric radius (R) over which abundances have been determined using this technique. Earlier studies of abundances in the Milky Way have indicated that there is a gradient in heavy element abundances between the Galactic center and the Solar circle, but the distribution in the outer Galaxy has been less certain (Shaver et al. 1983, MNRAS, 204, 53; Fich & Silkey 1991, ApJ, 366, 107); Simpson et al. 1995, ApJ, submitted), with one study indicating that the N abundance flattens out beyond the Solar circle (Fich & Silkey 1991). Our results seem to contradict this finding. Our abundance measurements are consistent with those found by Fich and Silkey for individual outer Galaxy HII regions. However, when they are combined with measurements made of inner Galaxy H II regions using the identical instruments and analysis techniques, our data suggest that the abundances in all three elements, N, O, and S, continue to fall in the outer Galaxy. For example, our results indicate that the abundance of N is 2--3 times lower in the outer Galaxy than at the Solar neighborhood, and is 10 times lower than in the inner Galaxy. This result, in addition to having important implications for models of Galactic chemical structure and evolution (see, e.g., Wilson and Matteucci 1992, A&AR, 4, 1), also confirms that the outer Galaxy is an ideal place to study a region of star-formation very different from the Solar neighborhood, but, unlike in other galaxies, close enough to allow detailed studies of individual star-forming regions.

  12. Oyster shell conveyor used to lift shells from the dock ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Oyster shell conveyor used to lift shells from the dock into the receiving room housed in the 1965 concrete block addition. - J.C. Lore Oyster House, 14430 Solomons Island Road, Solomons, Calvert County, MD

  13. Structure and mechanical properties of Saxidomus purpuratus biological shells.

    PubMed

    Yang, W; Zhang, G P; Zhu, X F; Li, X W; Meyers, M A

    2011-10-01

    The strength and fracture behavior of Saxidomus purpuratus shells were investigated and correlated with the structure. The shells show a crossed lamellar structure in the inner and middle layers and a fibrous/blocky and porous structure composed of nanoscaled particulates (~100 nm diameter) in the outer layer. It was found that the flexure strength and fracture mode are a function of lamellar organization and orientation. The crossed lamellar structure of this shell is composed of domains of parallel lamellae with approximate thickness of 200-600 nm. These domains have approximate lateral dimensions of 10-70 ?m with a minimum of two orientations of lamellae in the inner and middle layers. Neighboring domains are oriented at specific angles and thus the structure forms a crossed lamellar pattern. The microhardness across the thickness was lower in the outer layer because of the porosity and the absence of lamellae. The tensile (from flexure tests) and compressive strengths were analyzed by means of Weibull statistics. The mean tensile (flexure) strength at probability of 50%, 80-105 MPa, is on the same order as the compressive strength (~50-150 MPa) and the Weibull moduli vary from 3.0 to 7.6. These values are significantly lower than abalone nacre, in spite of having the same aragonite structure. The lower strength can be attributed to a smaller fraction of the organic interlayer. The fracture path in the specimens is dominated by the orientation of the domains and proceeds preferentially along lamella boundaries. It also correlates with the color changes in the cross section of the shell. The cracks tend to undergo a considerable change in orientation when the color changes abruptly. The distributions of strengths, cracking paths, and fracture surfaces indicate that the mechanical properties of the shell are anisotropic with a hierarchical nature. PMID:21783161

  14. NGC 2655: from Inner Polar Ring to Outer Shells and Tails

    NASA Astrophysics Data System (ADS)

    Sparke, Linda S.; van Moorsel, Gustaaf; Erwin, Peter; Wehner, Elizabeth M. H.

    2008-01-01

    NGC 2655, a nearby bright S0/a galaxy in a loose group, has strongly asymmetric central dust lanes and an extended disk of neutral hydrogen gas. Here we present deep optical images showing tidal arms and regions of diffuse starlight well beyond the main galaxy, suggestive of a recent merger. Our maps in the 21 cm line show a layer of neutral hydrogen extending to at least 7.5' or 40 kpc from the center, with a broken streamer of gas trailing off toward the small neighbor galaxy UGC 4714. The global profile has sloping "shoulders" of extreme-velocity gas, usually a sign of interaction. The diffuse stellar light corresponds generally but not in detail with the distribution of H I. In particular, the stellar light of the main tidal arm extends beyond the H I layer, which is limb-brightened as if it had been compressed from outside. The pattern of gas velocities is generally bisymmetric, but the H I layer is strongly warped; it does not share the kinematics of the stellar disk. The gas orbits twist by at least 90° between 1' and 3' of the center, as the H I layer appears to warp through edge-on. The complex optical tails and H I dynamics suggest that the galaxy has undergone multiple mergers. Both at small and at large radii, the gas layer twists in a trailing sense relative to its orbital motion. If the twist results from differential precession in the galaxy's gravitational potential, this would indicate that the dark halo is prolate, elongated along the rotation axis of the disk.

  15. The optoelectronic behaviour of carbon nanoparticles: evidence of the importance of the outer carbon shell

    NASA Astrophysics Data System (ADS)

    Marzari, Gabriela; Morales, Gustavo M.; Moreno, M. Sergio; Garcia-Gutierrez, D. I.; Fungo, Fernando

    2013-08-01

    The particular properties of carbon nanoparticles (CNPs) have generated great interest in biomedicine, bioanalysis and optoelectronics. However, an association between the CNPs' physicochemical properties with their molecular and morphological characteristics is, even today, a topic of discussion. In this work, we use a simple method of synthesis with the ultimate aim of elucidating the structural nature of the obtained CNPs and its relationship with their well-known fluorescent properties. The sample is studied by high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), nuclear magnetic resonance (NMR), UV-visible and IR spectroscopy, electrochemistry and electrogenerated chemiluminescence (ECL). The results showed that the nanoparticles are constituted by a graphitic core surrounded by an amorphous layer, which seems to be significant in the determination of the optical and electronic properties observed in the system under study.The particular properties of carbon nanoparticles (CNPs) have generated great interest in biomedicine, bioanalysis and optoelectronics. However, an association between the CNPs' physicochemical properties with their molecular and morphological characteristics is, even today, a topic of discussion. In this work, we use a simple method of synthesis with the ultimate aim of elucidating the structural nature of the obtained CNPs and its relationship with their well-known fluorescent properties. The sample is studied by high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS), nuclear magnetic resonance (NMR), UV-visible and IR spectroscopy, electrochemistry and electrogenerated chemiluminescence (ECL). The results showed that the nanoparticles are constituted by a graphitic core surrounded by an amorphous layer, which seems to be significant in the determination of the optical and electronic properties observed in the system under study. Electronic supplementary information (ESI) available: Experimental and characterization details. See DOI: 10.1039/c3nr01485a

  16. New surface-modified solid lipid nanoparticles using N-glutaryl phosphatidylethanolamine as the outer shell

    PubMed Central

    Kashanian, Soheila; Azandaryani, Abbas Hemati; Derakhshandeh, Katayoun

    2011-01-01

    Background Solid lipid nanoparticles (SLNs) are colloidal carrier systems which provide controlled-release profiles for many substances. In this study, we prepared aqueous dispersions of lipid nanoparticles using a modified, pH-sensitive derivative of phosphatidylethanolamine. Methods SLNs were prepared using polysorbate 80 as the surfactant and tripalmitin glyceride and N-glutaryl phosphatidylethanolamine as the lipid components. Particle size, polydispersity index, and zeta potential were examined by photon correlation spectroscopy. Morphological evaluation was performed using scanning electron microscopy, atomic force microscopy, and differential scanning calorimetry. Results Photon correlation spectroscopy revealed a particle hydrodynamic diameter of 165.8 nm and zeta potential of ?41.6.0 mV for the drug-loaded nanoparticles. Atomic force microscopy investigation showed the nanoparticles to be 50–600 nm in length and 66.5 nm in height. Differential scanning calorimetry indicated that the majority of SLNs possessed less ordered arrangements of crystals compared with corresponding bulk lipids, which is favorable for improving drug-loading capacity. Drug-loading capacity and drug entrapment efficiency values for the SLNs were 25.32% and 94.32%, respectively. Conclusion The SLNs prepared in this study were able to control the release of triamcinolone acetonide under acidic conditions. PMID:22114489

  17. SUPER HARD SURFACED POLYMERS

    SciTech Connect

    Mansur, Louis K [ORNL] [ORNL; Bhattacharya, R [UES, Incorporated, Dayton, OH] [UES, Incorporated, Dayton, OH; Blau, Peter Julian [ORNL] [ORNL; Clemons, Art [ORNL] [ORNL; Eberle, Cliff [ORNL] [ORNL; Evans, H B [UES, Incorporated, Dayton, OH] [UES, Incorporated, Dayton, OH; Janke, Christopher James [ORNL] [ORNL; Jolly, Brian C [ORNL] [ORNL; Lee, E H [Consultant, Milpitas, CA] [Consultant, Milpitas, CA; Leonard, Keith J [ORNL] [ORNL; Trejo, Rosa M [ORNL] [ORNL; Rivard, John D [ORNL] [ORNL

    2010-01-01

    High energy ion beam surface treatments were applied to a selected group of polymers. Of the six materials in the present study, four were thermoplastics (polycarbonate, polyethylene, polyethylene terephthalate, and polystyrene) and two were thermosets (epoxy and polyimide). The particular epoxy evaluated in this work is one of the resins used in formulating fiber reinforced composites for military helicopter blades. Measures of mechanical properties of the near surface regions were obtained by nanoindentation hardness and pin on disk wear. Attempts were also made to measure erosion resistance by particle impact. All materials were hardness tested. Pristine materials were very soft, having values in the range of approximately 0.1 to 0.5 GPa. Ion beam treatment increased hardness by up to 50 times compared to untreated materials. For reference, all materials were hardened to values higher than those typical of stainless steels. Wear tests were carried out on three of the materials, PET, PI and epoxy. On the ion beam treated epoxy no wear could be detected, whereas the untreated material showed significant wear.

  18. Local hardness equalization and the principle of maximum hardness.

    PubMed

    Gázquez, José L; Vela, Alberto; Chattaraj, Pratim K

    2013-06-01

    The chemical potential, hardness, and hyperhardnesses equalization principles are used to show that the leading term associated with charge transfer in the total interaction energy among the fragments in which a molecule is divided is directly proportional to minus the hardness of the molecule in its ground state, as established by the principle of maximum hardness. The additional terms in the interaction energy, associated with the changes in the external potential of the fragments, provide explanation for deviations between the point of maximum hardness and the point of minimum energy. It is also found that the dual descriptor plays a very important role in hardness equalization. PMID:23758354

  19. Cosmic ray gradients in the outer heliosphere

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Wake, B.; Ip, W.-H.; Axford, I.

    1983-01-01

    Launched in 1972 and 1973 respectively, the Pioneer 10 and 11 spacecraft are now probing the outer heliosphere on their final escape from the sun. The data in this paper extend for almost an entire solar cycle from launch to early 1983, when Pioneer 10 was at a heliocentric distance of 29 AU and Pioneer 11, 13 AU. The UCSD instruments on board were used to study the gradient, and to look at the time and spatial variations of the cosmic ray intensities.

  20. Photopolarimetry team outer planets mission definition phase

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The work is reported of the Photopolarimetry Team in identifying scientific objectives for photometer/polarimeter experiments for outer planet flyby missions. A discussion of the scientific objectives which can be attained with a photometer/polarimeter experiment, and summaries of the special studies which were performed for the Photopolarimetry Team are presented along with a description of the photometer/polarimeter design which was developed for the Meteoroid Detection Team.

  1. A photometric survey of outer belt asteroids

    NASA Technical Reports Server (NTRS)

    Dimartino, M.; Gonano-Beurer, M.; Mottola, Stefano; Neukum, G.

    1992-01-01

    Since 1989, we have been conducting a research program devoted to the study of the Trojans and outer belt asteroids (Hilda and Cybele groups), in order to characterize their rotational properties and shapes. As an outcome of several observational campaigns, we determined rotational periods and lightcurve amplitudes for 23 distant asteroids, using both CCD and photoelectric photometry. In this paper, we compare the rotational properties of main belt asteroids and Trojans, based on the preliminary results of this survey.

  2. Transport of iron across the outer membrane.

    PubMed

    Braun, V; Günter, K; Hantke, K

    1991-01-01

    The TonB protein is involved in energ-coupled receptor-dependent transport processes across the outer membrane. The TonB protein is anchored in the cytoplasmic membrane but exposed to the periplasmic space. To fulfill its function, it has to couple the energy-providing metabolism in the cytoplasmic membrane with regulation of outer membrane receptor activity. Ferrichrome and albomycin transport, uptake of colicin M, and infection by the phages T1 and phi 80 occur via the same receptor, the FhuA protein in the outer membrane. Therefore, this receptor is particularly suitable for the study of energy-coupled TonB-dependent transport across the outer membrane. Ferrichrome, albomycin and colicin M bind to the FhuA receptor but are not released into the periplasmic space of unenergized cells, or tonB mutants. In vivo interaction between FhuA and TonB is suggested by the restoration of activity of inactive FhuA proteins, bearing amino acid replacements in the TonB box, by TonB derivatives with single amino acid substitutions. Point mutations in the fhuA gene are suppressed by point mutations in the tonB gene. In addition, naturally occurring degradation of the TonB protein and its derivatives is preferentially prevented in vivo by FhuA and FhuA derivatives where functional interaction takes place. It is proposed that in the energized state, TonB induces a conformation in FhuA which leads to the release of the FhuA-bound compounds into the periplasmic space. Activation of FhuA by TonB depends on the ExbBD proteins in the cytoplasmic membrane. They can be partially replaced by the TolQR proteins which show strong sequence similarity to the ExbBD proteins.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1854585

  3. Planetary magnetism in the outer solar system.

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.

    1973-01-01

    A brief review of the salient considerations which apply to the existence of magnetic fields in connection with planetary and subplanetary objects in the outer solar system is given. Consideration is given to internal dynamo fields, fields which might originate from interaction with the solar wind or magnetospheres (externally driven dynamos) and lastly fossil magnetic fields such as have been discovered on the moon. Where possible, connection is made between magnetism, means of detection, and internal body properties.

  4. Differential Rotation within the Earth's Outer Core

    NASA Technical Reports Server (NTRS)

    Hide, R.; Boggs, D. H.; Dickey, J. O.

    1998-01-01

    Non-steady differential rotation drive by bouyancy forces within the Earth's liquid outer core (OC) plays a key role not only in the generation of the main geomagnetic field by the magnetohydrodynamic (MHD) dynamo process but also in the excitation of irregular fluctuations in the angular speed of rotation of the overlying solid mantle, as evidenced by changes in the length of the day (LOD) on decadal and longer timescales (1-8).

  5. Building a flagellum in biological outer space

    E-print Network

    Evans, Lewis D. B.; Hughes, Colin; Fraser, Gillian M.

    2014-01-25

    OPEN ACCESS | www.microbialcell.com 64 Microbial Cell | February 2014 | Vol. 1 No. 2 www.microbialcell.com Microreview Building a flagellum in biological outer space Lewis D. B. Evans, Colin Hughes and Gillian M. Fraser* Department... of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, United Kingdom. * Corresponding Author: G. M. Fraser, Department of Pathology, University of Cambridge, Tennis Court Road; Cambridge, CB2 1QP, United Kingdom; Tel: +44 (0...

  6. Heavy ions in the outer Kronian magnetosphere

    Microsoft Academic Search

    Aharon Eviatar; Ralph L. McNutt; George L. Siscoe; James D. Sullivan

    1983-01-01

    Data from the plasma science experiment on Voyager 1 show the existence of a cold heavy ion component in the plasma populating the outer Kronian magnetosphere (Lroughly-equal15). The mass resolution is not sufficient to determine unambiguously whether the ions are oxygen (O\\/sup +\\/ mass 16) or nitrogen (N\\/sup +\\/ mass 14). If the former, their most probable origin is sputtering

  7. Outer membrane proteins of pathogenic spirochetes

    PubMed Central

    Cullen, Paul A.; Haake, David A.; Adler, Ben

    2009-01-01

    Pathogenic spirochetes are the causative agents of several important diseases including syphilis, Lyme disease, leptospirosis, swine dysentery, periodontal disease and some forms of relapsing fever. Spirochetal bacteria possess two membranes and the proteins present in the outer membrane are at the site of interaction with host tissue and the immune system. This review describes the current knowledge in the field of spirochetal outer membrane protein (OMP) biology. What is known concerning biogenesis and structure of OMPs, with particular regard to the atypical signal peptide cleavage sites observed amongst the spirochetes, is discussed. We examine the functions that have been determined for several spirochetal OMPs including those that have been demonstrated to function as adhesins, porins or to have roles in complement resistance. A detailed description of the role of spirochetal OMPs in immunity, including those that stimulate protective immunity or that are involved in antigenic variation, is given. A final section is included which covers experimental considerations in spirochetal outer membrane biology. This section covers contentious issues concerning cellular localization of putative OMPs, including determination of surface exposure. A more detailed knowledge of spirochetal OMP biology will hopefully lead to the design of new vaccines and a better understanding of spirochetal pathogenesis. PMID:15449605

  8. Imaging of the outer planets and satellites.

    NASA Technical Reports Server (NTRS)

    Murray, B. C.

    1973-01-01

    Imaging is the most widely applicable single means of exploring the outer planets and their satellites and also complements other planet-oriented instruments. Photography of Jupiter from terrestrial telescopes has revealed features which were neither predictable or predicted. Close-up imaging from fly-bys and orbiters affords the opportunity for discovery of atmospheric phenomena on the outer planets forever beyond the reach of terrestrial laboratories and intuition. On the other hand, a large number of specific applications of close-up imaging to study the giant planets are suggested by experience in photography from Earth and Mars orbit, and by ground-based telescopic studies of Jupiter and Saturn. The satellites of the outer planets actually constitute three distinct classes: lunar-sized objects, asteroidal-sized objects, and particulate rings. Imaging promises to be the primary observational tool for each category with results that could impact scientific thinking in the late 70's and 80's as significantly as has close-up photography of Mars and the Moon in the last 10 yr.

  9. Involute, minimal, outer, and increasingly trapped spheres

    SciTech Connect

    Hayward, Sean A. [Center for Astrophysics, Shanghai Normal University, 100 Guilin Road, Shanghai 200234 (China)

    2010-01-15

    Seven different refinements of trapped surfaces are proposed, each intended as potential stability conditions. This article concerns spherical symmetry, but each condition can be generalized. Involute trapped spheres satisfy a similar condition to minimal trapped spheres, which are strictly minimal with respect to the Kodama vector. There is also a weaker version of involute trapped spheres. Outer trapped spheres have positive surface gravity. Increasingly (future, respectively, past) trapped spheres generate spheres which are more trapped in a (future, respectively, past) causal direction, with three types: in any such causal direction, along the dual Kodama vector, and in some such causal direction. Assuming the null energy condition, the seven conditions form a strict hierarchy, in the above order. In static space-times, they reduce to three inequivalent definitions, namely, minimal, outer, and increasingly trapped spheres. For a widely considered class of so-called nice (or nondirty) black holes, minimal trapped and outer trapped become equivalent. Reissner-Nordstroem black holes provide examples of this, and that the increasingly trapped differs. Examples where all three refinements differ are provided by a simple family of dirty black holes parametrized by mass and singularity area.

  10. Natural melting within a spherical shell

    NASA Technical Reports Server (NTRS)

    Bahrami, Parviz A.

    1990-01-01

    Fundamental heat transfer experiments were performed on the melting of a phase change medium in a spherical shell. Free expansion of the medium into a void space within the sphere was permitted. A step function temperature jump on the outer shell wall was imposed and the timewise evolution of the melting process and the position of the solid-liquid interface was photographically recorded. Numerical integration of the interface position data yielded information about the melted mass and the energy of melting. It was found that the rate of melting and the heat transfer were significantly affected by the movement of the solid medium to the base of the sphere due to gravity. The energy transfer associated with melting was substantially higher than that predicted by the conduction model. Furthermore, the radio of the measured values of sensible energy in the liquid melt to the energy of melting were nearly proportional to the Stefan number. The experimental results are in agreement with a theory set forth in an earlier paper.

  11. Rollable Thin-Shell Nanolaminate Mirrors

    NASA Technical Reports Server (NTRS)

    Hickey, Gregory; Lih, Shyh-Shiuh; Barbee, Troy, Jr.

    2003-01-01

    A class of lightweight, deployable, thin-shell, curved mirrors with built-in precise-shape-control actuators is being developed for high-resolution scientific imaging. This technology incorporates a combination of advanced design concepts in actuation and membrane optics that, heretofore, have been considered as separate innovations. These mirrors are conceived to be stowed compactly in a launch shroud and transported aboard spacecraft, then deployed in outer space to required precise shapes at much larger dimensions (diameters of the order of meters or tens of meters). A typical shell rollable mirror structure would include: (1) a flexible single- or multiple-layer face sheet that would include an integrated reflective surface layer that would constitute the mirror; (2) structural supports in the form of stiffeners made of a shape-memory alloy (SMA); and (3) piezoelectric actuators. The actuators, together with an electronic control subsystem, would implement a concept of hierarchical distributed control, in which (1) the SMA actuators would be used for global shape control and would generate the large deformations needed for the deployment process and (2) the piezoelectric actuators would generate smaller deformations and would be used primarily to effect fine local control of the shape of the mirror.

  12. Shell Creek Summers

    ERIC Educational Resources Information Center

    Seier, Mark; Goedeken, Suzy

    2005-01-01

    In 2002 Shell Creek Watershed Improvement Group turned to the Newman Grove Public Schools' science department to help educate the public on water quality in the watershed and to establish a monitoring system that would be used to improve surface and groundwater quality in the creek's watershed. Nebraska Department of Environmental Quality provided…

  13. Agreement, Shells, and Focus.

    ERIC Educational Resources Information Center

    Simpson, Andrew; Wu, Zoe

    2002-01-01

    Reconsiders development and licensing of agreement as a syntactic projection and argues for a productive developmental relation between agreement and the category of focus. Suggests that focus projections are initially selected by a variety of functional heads with real semantic content, then, over time decays into a simple concord shell. Upon…

  14. Adaptive meshes and shells

    Microsoft Academic Search

    M. Vasilescu; D. Terzopoulos

    1992-01-01

    2 Review of Adaptive Meshes Adaptive meshes are dynamic networks of nodal masses intercon-nected by adjustable springs. They are useful for nonuniformly sampling and reconstructing visual data. This paper extends the adaptive mesh model in the following ways: it (i) develops open adaptive meshes and closed adaptive shells based on triangular and rectangular elements, (ii) proposes a discontinuity detection and

  15. Egg shell strengh

    Microsoft Academic Search

    R. G. Wells

    1967-01-01

    The experiment was designed to provide more evidence of the reliability of laboratory tests used to assess shell strength by measuring their relationship to egg breakage in the field. It involved all eggs produced by 23 White Leghorn × Buff Rock pullets that were kept in battery cages for a period of 24 weeks.Samples of eggs from each hen were

  16. Thickness Constraints on the Icy Shells of the Galilean Satellites from a Comparison of Crater Shapes

    NASA Technical Reports Server (NTRS)

    Schenk, Paul M.

    2002-01-01

    A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-dependent estimates ranging from a few kilometers of depths of impact craters on Europa, Ganymede and Callisto that reveal two anomalous transitions in crater shape with diameter. The first transition is probably related to temperature-dependent ductility of the crust at shallow depths (7-8 km on Europa). The second transition is attributed to the influence of subsurface oceans on all three satellites, which constrains Europa's icy shell to be at least 19 km thick. The icy lithospheres of Ganymede and Callisto are equally ice-rich, but Europa's icy shell has a thermal structure about 0.25-0.5 times the thickness of Ganymede's or Callisto's shells, depending on epoch. The appearances of the craters on Europa are inconsistent with thin-ice-shell models and indicate that exchange of oceanic and surface material could be difficult.

  17. Thickness constraints on the icy shells of the galilean satellites from a comparison of crater shapes.

    PubMed

    Schenk, Paul M

    2002-05-23

    A thin outer ice shell on Jupiter's large moon Europa would imply easy exchange between the surface and any organic or biotic material in its putative subsurface ocean. The thickness of the outer ice shell is poorly constrained, however, with model-dependent estimates ranging from a few kilometres to ten or more kilometres. Here I present measurements of depths of impact craters on Europa, Ganymede and Callisto that reveal two anomalous transitions in crater shape with diameter. The first transition is probably related to temperature-dependent ductility of the crust at shallow depths (7 8 km on Europa). The second transition is attributed to the influence of subsurface oceans on all three satellites, which constrains Europa's icy shell to be at least 19 km thick. The icy lithospheres of Ganymede and Callisto are equally ice-rich, but Europa's icy shell has a thermal structure about 0.25 0.5 times the thicknesses of Ganymede's or Callisto's shells, depending on epoch. The appearances of the craters on Europa are inconsistent with thin-ice-shell models and indicate that exchange of oceanic and surface material could be difficult. PMID:12024207

  18. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Definitions —Outer burial receptacle. For purposes of this section, an outer burial receptacle means a graveliner, burial vault, or other similar type of container for a casket. (b) Purpose. This section provides for payment of a...

  19. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Definitions —Outer burial receptacle. For purposes of this section, an outer burial receptacle means a graveliner, burial vault, or other similar type of container for a casket. (b) Purpose. This section provides for payment of a...

  20. 38 CFR 38.629 - Outer Burial Receptacle Allowance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Definitions —Outer burial receptacle. For purposes of this section, an outer burial receptacle means a graveliner, burial vault, or other similar type of container for a casket. (b) Purpose. This section provides for payment of a...

  1. 9 CFR 108.10 - Outer premises and stables.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS FACILITY REQUIREMENTS FOR LICENSED ESTABLISHMENTS § 108.10 Outer premises and stables. (a) The outer...

  2. 9 CFR 108.10 - Outer premises and stables.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS FACILITY REQUIREMENTS FOR LICENSED ESTABLISHMENTS § 108.10 Outer premises and stables. (a) The outer...

  3. Stability of charged thin shells

    SciTech Connect

    Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio, C.C. 67, Suc. 28, 1428, Buenos Aires (Argentina); Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina); Simeone, Claudio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina); IFIBA, CONICET, Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina)

    2011-05-15

    In this article we study the mechanical stability of spherically symmetric thin shells with charge, in Einstein-Maxwell and Einstein-Born-Infeld theories. We analyze linearized perturbations preserving the symmetry, for shells around vacuum and shells surrounding noncharged black holes.

  4. Sea shells and blood cells

    NSDL National Science Digital Library

    American Association for the Advancement of Science (AAAS; )

    2004-04-09

    Scientists know that oysters make their shells from crystals but where the crystals are made is still a mystery. A new study in the 09 April 2004 issue of the journal Science suggests that these shell-building crystals are formed in a special class of blood cells that travel to the site of shell formation and unload their crystal cargo.

  5. Inner / Outer Leg Symmetry Of the Cornell Ranger

    E-print Network

    Ruina, Andy L.

    of the walking `cycle' of the Ranger is as follows ­ First, say, the inner leg is the pivot or stance leg, while the outer leg is swung forward, by the hip-motor and a push-off mechanism on the outer leg (actuated by the foot motor on the outer leg). After the foot on the outer leg lands, it is now the stance leg

  6. First Images from HERO: A Hard-X-Ray Focusing Telescope

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian D.; Alexander, Cheryl D.; Apple, Jeff A.; Benson, Carl M.; Dietz, Kurtis L.; Elsner, Ronald F.; Engelhaupt, Darell E.; Ghosh, Kajal K.; Kolodziejczak, Jeffery J.; ODell, Stephen L.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    We are developing a balloon-borne hard-x-ray telescope that utilizes grazing incidence optics. Termed HERO, for High-Energy Replicated Optics, the instrument will provide unprecented sensitivity in the hard-x-ray region and will achieve milliCrab-level sensitivity in a typical 3-hour balloon-flight observation and 50 microCrab sensitivity on ultra-long-duration flights. A recent proof-of-concept flight, featuring a small number of mirror shells captured the first focused hard-x-ray images of galactic x-ray sources. Full details of the payload, its expected future performance and its recent measurements are provided.

  7. Scientific Goals for Exploration of the Outer Solar System

    E-print Network

    Rathbun, Julie A.

    Scientific Goals for Exploration of the Outer Solar System Explore Diverse Worlds How did the outer planets mold the solar system and create habitable worlds? OPAG Report DRAFT 4 November 2014 #12;2 Outline of this document is to frame the science objectives for exploration of the outer solar system. It is consistent

  8. Scientific Goals for Exploration of the Outer Solar System

    E-print Network

    Rathbun, Julie A.

    Scientific Goals for Exploration of the Outer Solar System How did the outer planets mold the solar the science objectives for exploration of the outer solar system. It is consistent with Visions and Voyages but will be kept up-to-date as new discoveries are made, models evolve, our understanding of solar system processes

  9. Hard metal composition

    DOEpatents

    Sheinberg, Haskell (Los Alamos, NM)

    1986-01-01

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 weight percent boron carbide and the remainder a metal mixture comprising from 70 to 90 percent tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 to 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  10. Hardness of Materials- Introduction

    NSDL National Science Digital Library

    This lesson plan from Edmonds Community College will serve as an excellent introduction to the hardness of materials. The module illustrates the differences in properties between different materials. Students will determine property differences between different types of materials, observe property differences between materials of the same class, measure, record and report their results and observe differences in results due to operator error. Student, instructor and course evaluation questions are included. This document will serve as a framework for instructors and may be downloaded in PDF format.

  11. Hard metal composition

    DOEpatents

    Sheinberg, H.

    1983-07-26

    A composition of matter having a Rockwell A hardness of at least 85 is formed from a precursor mixture comprising between 3 and 10 wt % boron carbide and the remainder a metal mixture comprising from 70 to 90% tungsten or molybdenum, with the remainder of the metal mixture comprising nickel and iron or a mixture thereof. The composition has a relatively low density of between 7 and 14 g/cc. The precursor is preferably hot pressed to yield a composition having greater than 100% of theoretical density.

  12. Bioluminescent signals spatially amplified by wavelength-specific diffusion through the shell of a marine snail

    PubMed Central

    Deheyn, Dimitri D.; Wilson, Nerida G.

    2011-01-01

    Some living organisms produce visible light (bioluminescence) for intra- or interspecific visual communication. Here, we describe a remarkable bioluminescent adaptation in the marine snail Hinea brasiliana. This species produces a luminous display in response to mechanical stimulation caused by encounters with other motile organisms. The light is produced from discrete areas on the snail's body beneath the snail's shell, and must thus overcome this structural barrier to be viewed by an external receiver. The diffusion and transmission efficiency of the shell is greater than a commercial diffuser reference material. Most strikingly, the shell, although opaque and pigmented, selectively diffuses the blue-green wavelength of the species bioluminescence. This diffusion generates a luminous display that is enlarged relative to the original light source. This unusual shell thus allows spatially amplified outward transmission of light communication signals from the snail, while allowing the animal to remain safely inside its hard protective shell. PMID:21159673

  13. Shoulder and hip joints for hard space suits and the like

    NASA Technical Reports Server (NTRS)

    Vykukal, H. C.

    1986-01-01

    For use in hard space suits and the like, a joint between the torso covering and the upper arm covering (i.e., shoulder) or between the torso covering and upper leg covering (i.e., hip) is disclosed. Each joint has an outer covering and a inner covering. The outer covering has plural perferably truncated toroidal sections decreasing in size proceeding outwardly. In one embodiment at each joint there are two bearings, the first larger than the second. The outer race of the larger bearing is attached to the outer edge of the smaller end of each section and the inner race of the larger bearing is attached to the end wall. The inner race of the smaller bearing is attached to the end wall. The outer race of the smaller bearing is attached to the larger end of the next section. Each bearing hask appropriate seals. Between each section is a rubber ring for the comfort of the wearer. Such rubber rings have radial flanges attached to the inner races of two adjacent bearings. Matching semicircular grooves are formed in the abutting overlapping surfaces. Bellows-like inner walls are also provided for each section fixed at one end to an inner cylindrical flange and, at the opposite end, to an end wall. Each outer section may rotate 360 deg relative to the next outer section, whereas the bellows sections do not rotate, but rather expand or contract locally as the rigid sections rotate relative to each other.

  14. Evaluation of reef shell embankment

    NASA Astrophysics Data System (ADS)

    Melancon, J. L.; Bokun, S. G.

    1980-12-01

    A method of constructing an embankment over marshland soils by end-dumping reef shell directly onto the marshland with no other major subgrade preparation is discussed. The dumped reef shell is then spread out to form a 'floating' embankment over the soft marshland. The subsidence characteristics of a reef shell embankment are compared with those of a clam shell embankment to determine if such a reef shell embankment would provide adequate structural support for traffic. Results show it is physically and economically feasible to construct a reef shell embankment on soft organic marshland soils. A properly constructed reef shell embankment develops into a homogeneous floating slab of substantial stability and strength capable of supporting allowable traffic loads.

  15. Hard Metal Disease

    PubMed Central

    Bech, A. O.; Kipling, M. D.; Heather, J. C.

    1962-01-01

    In Great Britain there have been no published reports of respiratory disease occurring amongst workers in the hard metal (tungsten carbide) industry. In this paper the clinical and radiological findings in six cases and the pathological findings in one are described. In two cases physiological studies indicated mild alveolar diffusion defects. Histological examination in a fatal case revealed diffuse pulmonary interstitial fibrosis with marked peribronchial and perivascular fibrosis and bronchial epithelial hyperplasia and metaplasia. Radiological surveys revealed the sporadic occurrence and low incidence of the disease. The alterations in respiratory mechanics which occurred in two workers following a day's exposure to dust are described. Airborne dust concentrations are given. The industrial process is outlined and the literature is reviewed. The toxicity of the metals is discussed, and our findings are compared with those reported from Europe and the United States. We are of the opinion that the changes which we would describe as hard metal disease are caused by the inhalation of dust at work and that the component responsible may be cobalt. Images PMID:13970036

  16. Lunar and Planetary Science XXXV: Outer Solar System

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session 'Outer Solar System" inlcuded:Monte Carlo Modeling of [O I] 630 nm Auroral Emission on Io; The Detection of Iron Sulfide on Io; Io and Loki in 2003 as Seen from the Infrared Telescope Facility Using Mutual Satellite and Jupiter Occultations; Mapping of the Zamama-Thor Region of Io; First Solar System Results of the Spitzer Space Telescope; Mapping the Surface of Pluto with the Hubble Space Telescope; Experimental Study on Fischer-Tropsch Catalysis in the Circum-Saturnian Subnebula; New High-Pressure Phases of Ammonia Dihydrate; Gas Hydrate Stability at Low Temperatures and High Pressures with Applications to Mars and Europa; Laboratory UV Photolysis of Planetary Ice Analogs Containing H2O + CO2 (1:1); The OH Stretch Infrared Band of Water Ice and Its Temperature and Radiation Dependence; Band Position Variations in Reflectance Spectra of the Jovian Satellite Ganymede; Comparison of Porosity and Radar Models for Europa s Near Surface; Combined Effects of Diurnal and Nonsynchronous Surface Stresses on Europa; Europa s Northern Trailing Hemisphere: Lineament Stratigraphic Framework; Europa at the Highest Resolution: Implications for Surface Processes and Landing Sites; Comparison of Methods to Determine Furrow System Centers on Ganymede and Callisto; Resurfacing of Ganymede by Liquid-Water Volcanism; Layered Ejecta Craters on Ganymede: Comparisons with Martian Analogs; Evaluation of the Possible Presence of CO2-Clathrates in Europa s Icy Shell or Seafloor; Geosciences at Jupiter s Icy Moons: The Midas Touch; Planetary Remote Sensing Science Enabled by MIDAS (Multiple Instrument Distributed Aperture Sensor); and In Situ Surveying of Saturn s Rings.

  17. Outer atmospheres of giant and supergiant stars

    NASA Technical Reports Server (NTRS)

    Brown, A.

    1984-01-01

    The properties of the chromospheres, transition regions and coronas of cool evolved stars are reviewed based primarily on recent ultraviolet and X-ray studies. Determinations of mass loss rates using new observational techniques in the ultraviolet and radio spectral regions are discussed and observations indicating general atmospheric motions are considered. The techniques available for the quantitative modeling of these atmospheres are outlined and recent results discussed. Finally, the current rudimentary understanding of the evolution of these outer atmospheres and its causes are considered.

  18. Dishwasher For Earth Or Outer Space

    NASA Technical Reports Server (NTRS)

    Tromble, Jon D.

    1991-01-01

    Dishwashing machine cleans eating utensils in either Earth gravity or zero gravity of outer space. Cycle consists of three phases: filling, washing, and draining. Rotation of tub creates artificial gravity aiding recirculation of water during washing phase in absence of true gravity. Centrifugal air/water separator helps system function in zero gravity. Self-cleaning filter contains interdigitating blades catching solid debris when water flows between them. Later, blades moved back and forth in scissor-like manner to dislodge debris, removed by backflow of water.

  19. Dark matter in the outer solar system

    NASA Technical Reports Server (NTRS)

    Owen, T.; Cruikshank, D.; De Bergh, C.; Geballe, T.

    1994-01-01

    There are now a large number of small bodies in the outer solar system that are known to be covered with dark material. Attempts to identify that material have been thwarted by the absence of discrete absorption features in the reflection spectra of these planetesimals. An absorption at 2.2 micrometers that appeared to be present in several objects has not been confirmed by new observations. Three absorptions in the spectrum of the unusually red planetesimal 5145 Pholus are well-established, but their identity remains a mystery.

  20. Accretion in the Early Outer Solar System

    E-print Network

    Scott J. Kenyon; Jane X. Luu

    1999-06-08

    We describe calculations of the evolution of an ensemble of small planetesimals in the outer solar system. In a solar nebula with a mass of several times the Minimum Mass Solar Nebula, objects with radii of 100-1000 km can form on timescales of 10-100 Myr. Model luminosity functions derived from these calculations agree with current observations of bodies beyond the orbit of Neptune (Kuiper Belt objects). New surveys with current and planned instruments can place better constraints on the mass and dynamics of the solar nebula by measuring the luminosity function at red magnitudes of 28 or larger.

  1. Grinding tool for making hemispherical bores in hard materials

    DOEpatents

    Duran, E.L.

    1985-04-03

    A grinding tool for forming hemispherical bores in hard materials such as boron carbide. The tool comprises a hemicircular grinding bit, formed of a metal bond diamond matrix, which is mounted transversely on one end of a tubular tool shaft. The bit includes a spherically curved outer edge surface which is the active grinding surface of the tool. Two coolant fluid ports on opposite sides of the bit enable introduction of coolant fluid through the bore of the tool shaft so as to be emitted adjacent the opposite sides of the grinding bit, thereby providing optimum cooling of both the workpiece and the bit.

  2. Atmospheric entry probes for outer planet exploration. Outer planet entry probe technical summary

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The use of unmanned space probes for investigating the conditions existing on and around the outer planets of the solar system is discussed. The subjects included in the report are: (1) the design of a common entry probe for outer planet missions, (2) the significant trades related to the development of a common probe design, (3) the impact of bus selection on probe design, (4) the impact of probe requirements on bus modifications, and (5) the key technology elements recommended for advanced development. Drawings and illustrations of typical probes are included to show the components and systems used in the space probes.

  3. 2 -Le Shell Decouverte

    E-print Network

    Tichit, Laurent

    ^eme fonctionnalit´e. Substitution de commande. ´Ecriture d'une cha^ine `a l'´ecran. Car besoin de compatibilit commandes : le Shell L'interpr´eteur de commandes effectue les op´erations suivantes : Ecriture sur l'´ecran d'une invite de commande : le prompt. tichit@iml230:~$ Lecture au clavier d'une ligne tap´ee par l

  4. Controllable fabrication and magnetic properties of double-shell cobalt oxides hollow particles.

    PubMed

    Zhang, Dan; Zhu, Jianyu; Zhang, Ning; Liu, Tao; Chen, Limiao; Liu, Xiaohe; Ma, Renzhi; Zhang, Haitao; Qiu, Guanzhou

    2015-01-01

    Double-shell cobalt monoxide (CoO) hollow particles were successfully synthesized by a facile and effective one-pot solution-based synthetic route. The inner architecture and outer structure of the double-shell CoO hollow particles could be readily created through controlling experimental parameters. A possible formation mechanism was proposed based on the experimental results. The current synthetic strategy has good prospects for the future production of other transition-metal oxides particles with hollow interior. Furthermore, double-shell cobalt oxide (Co3O4) hollow particles could also be obtained through calcinating corresponding CoO hollow particles. The magnetic measurements revealed double-shell CoO and Co3O4 hollow particles exhibit ferromagnetic and antiferromagnetic behaviour, respectively. PMID:25736824

  5. Isolation and Characterization of 2-Nitroimidazole Produced by Streptomyces Species as an Inhibitor of Both Carbonic Anhydrase and Shell Formation in the Barnacle Balanus amphitrite

    Microsoft Academic Search

    Mari Fukushima; Noriaki Ozaki; Hiroyuki Ikeda; Keiko Furihata; Yoichi Hayakawa; Shohei Sakuda; Hiromichi Nagasawa

    2002-01-01

    Carbonic anhydrase is thought to be involved in the process of calcium carbonate deposition in calcified tissues of many organisms. Barnacles form hard calcified shells for protection against predation, and represent a class of marine-fouling animals. In order to inhibit barnacle growth by inhibiting shell formation, we searched for carbonic anhydrase inhibitors from microbial secondary metabolites. A simple assay for

  6. Planktonic foraminiferal shell weight reflects sea surface temperature over the past 150 years in Santa Barbara Basin, California

    NASA Astrophysics Data System (ADS)

    Pak, D. K.; Clayman, L.; Weaver, J.; Schimmelmann, A.; Hendy, I. L.

    2011-12-01

    Size-normalized foraminiferal shell weight has been used as a proxy for past carbonate ion concentration in seawater, assuming that reduced carbonate ion concentration and pH lead to lower calcification rates and lighter, thinner shells. Previous research suggested that the uptake of anthropogenic CO2 and ocean acidification over the last century has resulted in lower shell weight, but this has not yet been documented at high resolution. Here, we present an approximately annual record of size-normalized shell weight and Mg/Ca of the near-surface dwelling planktonic foraminifera Globigerina bulloides to investigate the relationship between shell weight and sea surface temperature in Santa Barbara Basin, California (34° 16.847' N, 120° 02.268' W), over the last 150 years. Results indicate that foraminiferal shell weight is inversely correlated with instrumental sea surface temperature since 1850. Foraminiferal shell weights were highest between 1900 and 1920, corresponding to the lowest instrumental and Mg/Ca-derived sea surface temperatures. Shell weights gradually decreased to their lowest values after the mid-1970s, coincident with northeast Pacific warming as the Pacific Decadal Oscillation shifted from cool to warm phase. G. bulloides Mg/Ca temperatures also gradually increased after 1970, from 13 ± 1°C to 14.5 ± 1°C. Scanning electron microscopy indicates that the lowest shell-weight foraminifera, those deposited since the mid-1970s shift, exhibit a distinctive smooth shell texture devoid of spine bases, in contrast with higher shell-weight foraminifera, which have numerous spine bases and large pores. The smooth-shell surface morphology is replicated in laboratory dissolution experiments, consistent with removal of an outer layer of calcite during shell thinning and partial dissolution of G. bulloides. These results suggest that G. bulloides calcification rates were related to sea surface temperatures over the last 150 years, and that shells deposited after 1970 were subjected to additional partial dissolution at the sediment-water interface, possibly due to ocean acidification.

  7. OSSOS: The Outer Solar System Origins Survey

    NASA Astrophysics Data System (ADS)

    Gladman, Brett; Bannister, Michele; Kavelaars, Jj; Petit, Jean-Marc; Gwyn, Stephen; Chen, Ying-Tung

    2014-11-01

    We present the first detection set from the Outer Solar System Origins Survey (OSSOS) which is a mammoth 560-hour CFHT Large Program over 4 years (finishing January 2017). This is likely to be the largest Kuiper Belt survey before LSST comes on line (in terms of the number of precise transneptunian object (TNO) orbits it provides).OSSOS studies gradually-slewing 21-square degree blocks of sky that are repeatedly imaged in many dark runs over two semesters. This strategy is designed to detect and track TNOs in order to provide extremely high-quality orbits in a short amount of time; in 16-18 month arcs we are obtaining fractional semimajor axis uncertainties in the range 0.01-0.1% and accuracies in the libration amplitudes of resonant objects better than 10 degrees, due to mean astrometric residuals routinely being of order 50-100 milliarcseconds.This talk will present the survey design and full detection sample for objects observed in the first half of 2013 and 2014. We will report how adding these detections to those from the Canada-France Ecliptic Plane Survey (CFEPS) modifies conclusions about the orbital and size distribution of main classical Kuiper Belt, as well as other non-resonant sub-populations. In particular, because OSSOS is sensitive to, and has detected objects, from 8 AU to beyond 60 AU, we will report on how the combined distance and magnitude distribution impact dicsussions of the absolute magnitude distribution of outer Solar System objects.

  8. Polyamines decrease Escherichia coli outer membrane permeability.

    PubMed Central

    Dela Vega, A L; Delcour, A H

    1996-01-01

    The permeability of the outer membranes of gram-negative bacteria to hydrophilic compounds is mostly due to the presence of porin channels. We tested the effects of four polyamines (putrescine, cadaverine, spermidine, and spermine) on two processes known to depend on intact porin function: fluxes of beta-lactam antibiotics in live cells and chemotaxis. In both cases, inhibition was observed. Measurements of the rate of permeation of cephaloridine and of chemotaxis in swarm plates and capillary assays were used to determine the concentration dependence of this modulation. The effective concentration ranges depended on the nature of the polyamine and varied from submillimolar for spermine to tens of millimolar for cadaverine. Both OmpC and OmpF porins were inhibited, although the effects on OmpC appeared to be milder. These results are in agreement with our observations that polyamines inhibit porin-mediated ion fluxes in electrophysiological experiments, and they suggest that a low-affinity polyamine binding site might exist in these porins. These results reveal the potential use of porins as targets for blocking agents and suggest that polyamines may act as endogenous modulators of outer membrane permeability. PMID:8682771

  9. Radio Emissions from the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.; Kurth, W. S.

    1996-01-01

    For nearly fifteen years the Voyager 1 and 2 spacecraft have been detecting an unusual radio emission in the outer heliosphere in the frequency range from about 2 to 3 kHz. Two major events have been observed, the first in 1983-84 and the second in 1992-93. In both cases the onset of the radio emission occurred about 400 days after a period of intense solar activity, the first in mid-July 1982, and the second in May-June 1991. These two periods of solar activity produced the two deepest cosmic ray Forbush decreases ever observed. Forbush decreases are indicative of a system of strong shocks and associated disturbances propagating outward through the heliosphere. The radio emission is believed to have been produced when this system of shocks and disturbances interacted with one of the outer boundaries of the heliosphere, most likely in the vicinity of the the heliopause. The emission is believed to be generated by the shock-driven Langmuir-wave mode conversion mechanism, which produces radiation at the plasma frequency (f(sub p)) and at twice the plasma frequency (2f(sub p)). From the 400-day travel time and the known speed of the shocks, the distance to the interaction region can be computed, and is estimated to be in the range from about 110 to 160 AU.

  10. Future exploration of the outer solar system

    NASA Astrophysics Data System (ADS)

    Johnson, T.

    Exploration of the outer solar system is constrained by vast distances, consequent communications and light time limitations, power, and long flight times. Early reconnaissance missions (Pioneer 10 and 11, Voyager 1 and 2) employed relatively fast trajectories resulting in very fast fly-bys. The next generation of exploration (Galileo and Cassini) has been characterized by spacecraft with large propellant systems and relatively slow (gravity assist) trajectories needed energetically to achieve orbit around Jupiter and Saturn. All of these spacecraft utilized radioisotope thermoelectric generators for reliable, but modest power. Future exploration priorities require highly capable spacecraft systems that go into orbit around the primary planet and then perform multiple tasks (e.g. orbiting individual moons and delivering surface and atmospheric scientific probes). To achieve major scientific advances will require significant increases in communication rates, improved instrumentation and high power available for experiments. Fission-powered nuclear electric propulsion is being studied to meet these requirements. A Jupiter Icy Moons Orbiter is proposed as the first of this class of new, highly capable missions. The paper will review the scientific rationale for the JIMO mission and prospects for applying these techniques to exploration of Saturn and the other outer planets.

  11. Outer core compositional layering and constraints on core liquid transport properties

    NASA Astrophysics Data System (ADS)

    Helffrich, George

    2014-05-01

    A variety of studies of the Earth's outer core report wave speeds near the top of the core slightly lower than reference models for core properties. One interpretation of the slower wavespeed profile is that it could represent a change in the core's light element concentration with depth in the core. I explore the consequences of this idea by interpreting the velocity profile as arising from diffusion gradients imposed in the outer core by various mechanisms. I also examine theories for transport properties of high pressure metallic liquids that are based on hard-sphere models. These theories predict core diffusivities on the order of 1 - 20 × 10-9 m2s-1. From the seismic wavespeed profile, an effective diffusivity may be obtained, which ranges from 0.1 - 10 × 10-7 m2s-1 depending on the particular boundary condition or initial condition chosen. The upper bound on the range is much higher than expected from high pressure experiments and models of diffusivity in liquid metals. The lower bound is within the uncertainty of theoretical predictions and experimental determinations given the range of expected outer core temperatures if diffusion involves low Z elements. Plausible agreement arises from a class of models that represent diffusion out of a compositionally different layer existing from the time of the formation of the Earth. If the wavespeed profile in the core is diffusive in nature, the data suggest that it is an original feature of the core.

  12. Outer core compositional layering and constraints on core liquid transport properties

    NASA Astrophysics Data System (ADS)

    Helffrich, George

    2014-04-01

    A variety of studies of the Earth's outer core report wave speeds near the top of the core slightly lower than reference models for core properties. One interpretation of the slower wavespeed profile is that it could represent a change in the core's light element concentration with depth in the core. I explore the consequences of this idea by interpreting the velocity profile as arising from diffusion gradients imposed in the outer core by various mechanisms. In order to estimate relative diffusion rates for light elements in liquid iron I also examine theories for transport properties of high pressure metallic liquids that are based on hard-sphere models. From the seismic wavespeed profile, an effective diffusivity may be obtained, which ranges from 0.1 to 10×10-7 m s depending on the particular boundary condition or initial condition chosen. The upper bound of the range is higher than expected from high pressure experiments and models of diffusivity in liquid metals for all elements except H. The lower bound is within the uncertainty of theoretical predictions and experimental determinations given the range of expected outer core temperatures if diffusion involves low Z elements. Plausible agreement arises from a class of models that represent diffusion out of a compositionally different layer existing from the time of the formation of the Earth. If the wavespeed profile in the core is diffusive in nature, the data suggest that it is an original feature of the core.

  13. Shell model calculations of 109Sb in the sdgh shell

    NASA Astrophysics Data System (ADS)

    Dikmen, E.; Novoselsky, A.; Vallieres, M.

    2001-12-01

    The energy spectra of the antimony isotope 109Sb in the sdgh shell are calculated in the nuclear shell model approach by using the CD-Bonn nucleon-nucleon interaction. The modified Drexel University parallel shell model code (DUPSM) was used for the calculations with maximum Hamiltonian dimension of 762 253 of 5.14% sparsity. The energy levels are compared to the recent experimental results. The calculations were done on the Cyborg Parallel Cluster System at Drexel University.

  14. Can outer-to-outer diameter be used alone in diagnosing appendicitis on 128-slice MDCT?

    PubMed Central

    Yaqoob, Jamal; Idris, Muhammad; Alam, Muhammad Shahbaz; Kashif, Nazia

    2014-01-01

    AIM: To assess the frequency of visualization, position and diameter of normal appendix on 128-slice multidetector computed tomography (MDCT) in adult population. METHODS: Retrospective cross sectional study conducted at Radiology Department, Dallah Hospital, Riyadh, Saudi Arabia from March 2013 to October 2013. Non-enhanced computed tomography scans of abdomen and pelvis of 98 patients presenting with hematuria (not associated with abdominal pain, fever or colonic disease) were reviewed by two radiologists, blinded to patient history. The study group included 55 females and 43 males with overall mean age of 54.7 years (range 21 to 94 years). The coronal reformatted images were reviewed in addition to the axial images. The frequency of visualization of appendix was recorded with assessment of position, diameter and luminal contents. RESULTS: The appendix was recorded as definitely visualized in 99% of patients and mean outer-to-outer diameter of the appendix was 5.6 ± 1.3 mm (range 3.0-11.0 mm). CONCLUSION: MDCT with its multiplanar reformation display is extremely useful for visualization of normal appendix. The normal appendix is very variable in its position and diameter. In the absence of other signs, the diagnosis of acute appendix should not be made solely on outer-to-outer appendiceal diameter. PMID:25550996

  15. Numerical Modeling of Magnetohydrodynamic Convection in a Rapidly Rotating Spherical Shell: Weak and Strong Field Dynamo Action

    Microsoft Academic Search

    Weijia Kuang; Jeremy Bloxham

    1999-01-01

    In this paper we describe a numerical model for investigating magnetohydrodynamic (MHD) convective flow of a Boussinesq fluid in a rapidly rotating spherical shell, driven by the buoyancy forces arising from incoming buoyant flux at the inner core boundary. The model is designed to investigate the generation of magnetic field in the Earth's fluid outer core. Our model differs from

  16. Studies on shell formation. VII. The submicroscopic structure of the shell of the oyster Crassostrea virginica.

    PubMed

    TSUJII, T; SHARP, D G; WILBUR, K M

    1958-05-25

    The submicroscopic structure of the growing surface of the shell of the oyster, Crassostrea virginica, was studied by means of shadowed replicas. The outer edge of the prismatic region consists of a fine grained matrix enclosing crystals, the surfaces of which show a finely pebbled structure. Crystal size varies continously from 0.01 micro to 8 micro. The matrix surface shows no evidence of fibrous structure. The outer portions of the prismatic region exhibit a tile-like arrangement of large crystals separated by granular matrix 0.02 to 0.08 micro in thickness. The exposed crystal surfaces have indentations of varying form which appear as roughly parallel grooves spaced at intervals of approximately 0.3 micro. The final form of this region is believed to result from the random distribution of crystal seeds, which grow without orientation and through coalescence and growth come into contact, producing polygonal areas. The crystal arrangement of the nacreous region is one of overlapping rows of crystals in side to side contact, and with one end of each crystal free, permitting continued increase in length. Crystal angles and plane indices are presented. PMID:13549498

  17. Bathymetric records of marine shelled mollusca from the northeastern shelf of Yucatan, Mexico 

    E-print Network

    Treece, Granvil D

    1977-01-01

    . Microgaza rotella Dell, 1881 One shell, 5 mm in diameter, was found at 169 fathoms. It is very depressed with about 5 whorls. The suture on the outer whorl serves as a line for a row of nodules, while the deep umbilicus also has a crenulated spiral... line of nodules to spiral from the lower aperture to the upper. There are deep, squared sutures and heavy, off-set, radial ribs. The shells agree with the figure efven by Verrill (1882) and Rice and Kornicker (1965). TIIRBINIDAZ ~Beh t it 1ht*1...

  18. Instability localized at the inner surface of an imploding spherical shell

    SciTech Connect

    Han, S.J.

    1983-01-01

    It is shown that in an imploding spherical shell the surface instabilities are of two different types. The first, which occurs at the outer surfaces, is the Rayleigh-Taylor instability. The second instability occurs at the inner surface. This latter instability is not as disruptive as R-T modes, but it has three basic properties which differ considerably from those of the R-T instability: (1) it is oscillatory at early times; (2) it grows faster in the long wavelength modes; (3) it depends on the equation of state. It is further shown that this new instability is driven by amplified sound waves in the shell.

  19. A higher order dynamic theory for isotropic thermoelastic cylindrical shells. Part 2: Assessment

    NASA Astrophysics Data System (ADS)

    Birlik, G. A.; Mengi, Y.; Muneeb, A.-H.

    1995-02-01

    In this study the general approximate theory developed in Part 1 for dynamic behaviour of thermoelastic cylindrical shells is assessed by applying it to a coupled thermoelastic problem. The problem involves an infinitely long circular cylindrical shell (CCS) subjected radially to convective boundary conditions at its inner and outer surfaces. The time variations of radial and circumferential stresses and temperature predicted by exact and approximate theories are determined and compared. It is found that even the lowest order approximate theory is capable of predicting the essential thermoelastic response characteristics of the CCS. For the integration of exact and approximate equations a numerical algorithm based on the FFT is employed.

  20. Nuclear Electric Propulsion for Outer Space Missions

    NASA Technical Reports Server (NTRS)

    Barret, Chris

    2003-01-01

    Today we know of 66 moons in our very own Solar System, and many of these have atmospheres and oceans. In addition, the Hubble (optical) Space Telescope has helped us to discover a total of 100 extra-solar planets, i.e., planets going around other suns, including several solar systems. The Chandra (X-ray) Space Telescope has helped us to discover 33 Black Holes. There are some extremely fascinating things out there in our Universe to explore. In order to travel greater distances into our Universe, and to reach planetary bodies in our Solar System in much less time, new and innovative space propulsion systems must be developed. To this end NASA has created the Prometheus Program. When one considers space missions to the outer edges of our Solar System and far beyond, our Sun cannot be relied on to produce the required spacecraft (s/c) power. Solar energy diminishes as the square of the distance from the Sun. At Mars it is only 43% of that at Earth. At Jupiter, it falls off to only 3.6% of Earth's. By the time we get out to Pluto, solar energy is only .066% what it is on Earth. Therefore, beyond the orbit of Mars, it is not practical to depend on solar power for a s/c. However, the farther out we go the more power we need to heat the s/c and to transmit data back to Earth over the long distances. On Earth, knowledge is power. In the outer Solar System, power is knowledge. It is important that the public be made aware of the tremendous space benefits offered by Nuclear Electric Propulsion (NEP) and the minimal risk it poses to our environment. This paper presents an overview of the reasons for NEP systems, along with their basic components including the reactor, power conversion units (both static and dynamic), electric thrusters, and the launch safety of the NEP system.

  1. Maximum Chemical and Physical Hardness

    Microsoft Academic Search

    Ralph G. Pearson

    1999-01-01

    Density functional theory (DFT) is briefly reviewed, especially concepts such as the electronic chemical potential and the hardness of the electron density function. There is much evidence, and a mathematical proof, that this chemical hardness is a maximum for an equilibrium system. The proof is based on a combination of statistical mechanics, the fluctuation-dissipation theorem, and correlation functions. In MO

  2. Measuring the Hardness of Minerals

    ERIC Educational Resources Information Center

    Bushby, Jessica

    2005-01-01

    The author discusses Moh's hardness scale, a comparative scale for minerals, whereby the softest mineral (talc) is placed at 1 and the hardest mineral (diamond) is placed at 10, with all other minerals ordered in between, according to their hardness. Development history of the scale is outlined, as well as a description of how the scale is used…

  3. Subjective hardness of compliant materials

    Microsoft Academic Search

    Roland Harper; S. S. Stevens

    1964-01-01

    The apparent hardness and softness of nine samples of compliant materials were scaled by direct magnitude estimation and by cross-modal matches to the apparent force exerted on a hand dynamometer and a finger dynamometer, and to the loudness of a band of white noise. The physical hardness (force\\/indentation) of the compliant specimens covered a range of more than 100 to

  4. Discovery of Molecular Gas Shells around the Unusual Galaxy Centaurus A

    NASA Astrophysics Data System (ADS)

    2000-03-01

    Recent observations by an international team of astronomers [1] with the 15-metre Swedish-ESO Submillimetre Telescope at the La Silla observatory (Chile) have shown that the unusual, nearby galaxy Centaurus A is surrounded by shells in which carbon monoxide molecules are present. These new exciting results are the first of their kind. In addition to the intrinsic scientific value of this discovery, it also provides an instructive example of what will become possible for more distant galaxies with the projected Atacama Large Millimeter Array (ALMA) , now in the planning phase. Ellipticals and spirals Galaxies come in different shapes. Some of these take the form of more or less perfect spirals, some have the form of ellipsoids and still others have an irregular appearance. One of the major differences between elliptical and spiral galaxies is that the former do not possess extensive gaseous discs in which young stars can be formed. This is despite the fact that most elliptical galaxies are probably formed by the merger of two or more spiral galaxies. However, during such a process most of the gas in the spirals is either quickly turned into stars by massive bursts of star formation or is completely lost into the surrounding space. Shells around elliptical galaxies Most galaxies are members of groups. Once they have been formed, massive elliptical galaxies in these often behave like "cannibals" by swallowing one or more smaller companion galaxies. Some vestiges of such an event may remain visible for a certain time after the merger, normally in the form of weak structures in the otherwise smooth light distribution over the elliptical galaxy. These structures resemble the ripples or waves that develop on the water surface when you throw a small stone into a calm pond. While long-exposure photos show them as faint "rings" around the galaxy, they are in fact the projected images of three-dimensional structures and are often referred to as shells . By means of photometric and spectrographic studies of their light, it has been known since the early 1980's that such shells are made up of stars. It appears that they are quite common - about half of the nearby large elliptical galaxies have been found to be surrounded by stellar shells. More recently, in 1994, atomic hydrogen gas was discovered to be associated with some of the stellar shells. This discovery was a bit of a surprise, because the current theory predicts that when two galaxies merge, their gas and stars will behave very differently. While the individual stars hardly ever hit each other, the interstellar gas clouds collide violently. They will lose all their energy and the gas will fall towards the common centre where it is soon consumed in vigorous bursts of star formation. Why would there then be hydrogen gas in the outer shells of some elliptical galaxies? A possible origin of gaseous shells The astronomer team, headed by Vassilis Charmandaris [1] decided to look into this serious discrepancy between theory and observations. They believed that a possible explanation might be that this diffuse atomic gas is located, not in vast, very dilute clouds, but rather in smaller, much denser molecular clouds , such as these are known in our own galaxy, the Milky Way. Due to their relative compactness (more than 1000 molecules/cm 3 , i.e,. at least 100 times more than that of larger diffuse clouds), molecular clouds would behave more like the stars during the galaxy collision event. Indeed, realistic calculations showed that the dynamical behavior of such dense clouds would be intermediate between the stars and the diffuse hydrogen gas. Thus, while most of the gas would still end up in the centre of the remaining galaxy after a merger, a larger fraction of it would be able to survive at large distances from the nucleus. This would then be the origin of the observed hydrogen shells. During the merger, gas that originates from regions in the outskirts of the "cannibalized" galaxy - and farther out than most of the stars - would be liberated earlier

  5. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture...States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having...

  6. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Split shell. 51.2002 Section 51.2002 Agriculture...States Standards for Grades of Filberts in the Shell 1 Definitions § 51.2002 Split shell. Split shell means a shell having...

  7. Cyclic strength of hard metals

    SciTech Connect

    Sereda, N.N.; Gerikhanov, A.K.; Koval'chenko, M.S.; Pedanov, L.G.; Tsyban', V.A.

    1986-02-01

    The authors study the strength of hard-metal specimens and structural elements under conditions of cyclic loading since many elements of processing plants, equipment, and machines are made of hard metals. Fatigue tests were conducted on KTS-1N, KTSL-1, and KTNKh-70 materials, which are titanium carbide hard metals cemented with nickel-molybdenum, nickelcobalt-chromium, and nickel-chromium alloys, respectively. As a basis of comparison, the standard VK-15 (WC+15% Co) alloy was used. Some key physicomechanical characteristics of the materials investigated are presented. On time bases not exceeding 10/sup 6/ cycles, titanium carbide hard metals are comparable in fatigue resistance to the standard tungstencontaining hard metals.

  8. Separate fusion of outer and inner mitochondrial membranes

    PubMed Central

    Malka, Florence; Guillery, Olwenn; Cifuentes-Diaz, Carmen; Guillou, Emmanuelle; Belenguer, Pascale; Lombès, Anne; Rojo, Manuel

    2005-01-01

    Mitochondria are enveloped by two closely apposed boundary membranes with different properties and functions. It is known that they undergo fusion and fission, but it has remained unclear whether outer and inner membranes fuse simultaneously, coordinately or separately. We set up assays for the study of inner and outer membrane fusion in living human cells. Inner membrane fusion was more sensitive than outer membrane fusion to inhibition of glycolysis. Fusion of the inner membrane, but not of the outer membrane, was abolished by dissipation of the inner membrane potential with K+ (valinomycin) or H+ ionophores (cccp). In addition, outer and inner membrane fusion proceeded separately in the absence of any drug. The separate fusion of outer and inner membranes and the different requirements of these fusion reactions point to the existence of fusion machineries that can function separately. PMID:16113651

  9. Project EARTH-12-SHELL4: Shell Geoscience Laboratory

    E-print Network

    Henderson, Gideon

    Project EARTH-12-SHELL4: Shell Geoscience Laboratory Polygonal faults and de-watering of mudrocks (subject to contract) Polygonal faults are widely regarded as a response to dewatering during the earliest it is generally agreed that polygonal fault genesis is related to dewatering during the first few hundred metres

  10. Corrugated outer sheath gas-insulated transmission line

    DOEpatents

    Kemeny, George A. (Pittsburgh, PA); Cookson, Alan H. (Churchill Boro, PA)

    1981-01-01

    A gas-insulated transmission line includes two transmission line sections each of which are formed of a corrugated outer housing enclosing an inner high-voltage conductor disposed therein, with insulating support means supporting the inner conductor within the outer housing and an insulating gas providing electrical insulation therebetween. The outer housings in each section have smooth end sections at the longitudinal ends thereof which are joined together by joining means which provide for a sealing fixed joint.

  11. Off-Shell Supersymmetry

    E-print Network

    Chiu Man Ho; Nobuchika Okada

    2015-05-29

    Supersymmetry does not dictate the way we should quantize the fields in the supermultiplets, and so we have the freedom to quantize the Standard Model (SM) particles and their superpartners differently. We propose a generalized quantization scheme under which a particle can only appear off-shell, while its contributions to quantum corrections are exactly the same as those in the usual quantum field theory. We apply this quantization scheme solely to the sparticles in the $R$-parity preserving Minimal Supersymmetric Standard Model (MSSM). Thus sparticles can only appear off-shell. They could be light but would completely escape the direct detection at any experiments such as the LHC. However, our theory still retains the same desirable features of the usual MSSM at the quantum level. For instance, the gauge hierarchy problem is solved and the three MSSM gauge couplings are unified in the usual way. Although direct detection of sparticles is impossible, their existence can be revealed by precise measurements of some observables (such as the running QCD coupling) that may receive quantum corrections from them and have sizable deviations from the SM predictions. Also the experimental constraints from the indirect sparticle search are still applicable.

  12. Hi shells, supershells, shell-like objects, and ''worms''

    SciTech Connect

    Heiles, C.

    1984-08-01

    We present photographic representations of the combination of two Hi surveys, so as to eliminate the survey boundaries at Vertical BarbVertical Bar = 10/sup 0/. We also present high-contrast photographs for particular velocities to exhibit weak Hi features. All of these photographs were used to prepare a new list of Hi shells, supershells, and shell-like objects. We discuss the structure of three shell-like objects that are associated with high-velocity gas, and with gas at all velocities that is associated with radio continuum loops I, II, and III. We use spatial filtering to find wiggly gas filaments: ''worms'': crawling away from the galactic plane in the inner Galaxy. The ''worms'' are probably parts of shells that are open at the top; such shells should be good sources of hot gas for the galactic halo.

  13. Biogenesis of outer membranes in Gram-negative bacteria.

    PubMed

    Tokuda, Hajime

    2009-03-23

    The outer membrane, an essential organelle of Gram-negative bacteria, is composed of four major components: lipopolysaccharide, phospholipids, beta-barrel proteins, and lipoproteins. The mechanisms underlying the transport of these components to outer membranes are currently under extensive examination. Among them, the sorting of lipoproteins to the outer membrane of Escherichia coli has been clarified in detail. The Lol system, composed of five proteins, catalyzes outer membrane sorting of lipoproteins. Various Lpt proteins have recently been identified as factors involved in the transport of lipopolysaccharide to the outer membrane, although the mechanism remains largely unknown. Proteins with alpha-helical membrane spanning segments are found in the inner membrane, whereas amphipathic beta-barrel proteins span the outer membrane. These beta-barrel proteins are inserted into the outer membranes through a central core protein BamA (YaeT) with the help of four outer membrane lipoproteins. In contrast, little is known about how phospholipids are transported to the outer membrane. PMID:19270402

  14. Biomineralisation in Mollusc shells

    NASA Astrophysics Data System (ADS)

    Dauphin, Y.; Cuif, J. P.; Salomé, M.; Williams, C. T.

    2009-04-01

    The main components of Mollusc shells are carbonate minerals: calcite and aragonite. ACC is present in larval stages. Calcite and aragonite can be secreted simultaneously by the mantle. Despite the small number of varieties, the arrangement of the mineral components is diverse, and dependant upon the taxonomy. They are also associated with organic components much more diverse, the diversity of which reflects the large taxonomic diversity. From TGA analyses, the organic content (water included) is high (>5% in some layers). The biomineralisation process is not a passive precipitation process, but is strongly controlled by the organism. The biological-genetic control is shown by the constancy of the arrangement of the layers, the mineralogy and the microstructure in a given species. Microstructural units (i.e. tablets, prisms etc.) have shapes that do not occur in non-biogenic counterparts. Nacreous tablets, for example, are flattened on their crystallographic c axis, which is normally the axis of maximum growth rate for non-biogenic aragonite. Morever, their inner structure is species-specific: the arrangements of nacreous tablets in Gastropoda - Cephalopoda, and in Bivalvia differ, and the inner arrangement of the nacreous tablets is different in ectocochlear and endocochlear Cephalopoda. The organic-mineral ratios also differ in the various layers of a shell. Differences in chemical composition also demonstrates the biological-genetic control: for example, aragonite has a low Sr content unknown in non-biogenic samples; two aragonitic layers in a shell have different Sr and Mg contents, S is higher in calcitic layers. Decalcification releases soluble (SOM) and insoluble (IOM) organic components. Insoluble components form the main part of the intercrystalline membranes, and contain proteins, polysaccharides and lipids. Soluble phases are present within the crystals and the intercrystalline membranes. These phases are composed of more or less glycosylated proteins and polysaccharides, with a large range of molecular weights. Proteins are rich in acidic aminoacids (aspartic and glutamic acids). Sugars are usually sulphated, and very acidic. Several hundreds of proteins and sugars are present in the SOM. The compositions of IOM and SOM are characteristic for each layer present in a shell. Topographical relationships of mineral and organic components are visible at different scales of observation. SEM images of etched surfaces display the growth line rhythmicity and concordance between adjacent microstructural units. EPMA maps show similar chemical growth lines in various structures. Whatever the taxa, the average thickness of growth lines is about 2-3 µm, indicating an inner biological rhythm, not dependant on the environmental conditions. Such growth lines are observed in deep sea molluscs at depth where diurnal changes in light and temperature are absent. However, the role of the environment is shown by larger periodicities. Sulphur deserves a special interest, because it is associated with the organic matrices. Electrophoretic data have shown that acidic sulphated sugars are abundant in some layers. XANES analyses confirm these results. New microscopic techniques allow us to obtain images at a submicrometer scale. AFM images show that all the microstructural units (i.e. tablets, prisms etc.), calcite or aragonite, are composed of small sub-spherical granules with a diameter typically of about 50 nm. These granules are surrounded by a thin cortex (about 8 nm) of organic and/or amorphous material, and are organo-composite material as shown by phase images. They do not have crystalline shapes, despite the fact that the units they build are often monocrystalline. Molecular biology and genetic studies confirm that the control of the biomineralisation process is exerted at the scale of the whole organism: the expression of genes encoding major shell matrix proteins clearly indicates a regular separation of calcite and aragonite secretory activity. The main control on the structural and compositional features of mollusc she

  15. Hardness and fracture toughness of moissanite

    Microsoft Academic Search

    J. Qian; L. L. Daemen; Y. Zhao

    2005-01-01

    Disparities prevail among the reported hardness and fracture toughness values for hard and brittle materials. A better understanding of the physical nature of hardness and fracture toughness and a standardized technique for reliable measurements of these quantities is urgently needed. We strongly recommend the use of the measured hardness after the bend in the hardness versus load (H?FLoad) curve, when

  16. Biomechanics of turtle shells: how whole shells fail in compression.

    PubMed

    Magwene, Paul M; Socha, John J

    2013-02-01

    Turtle shells are a form of armor that provides varying degrees of protection against predation. Although this function of the shell as armor is widely appreciated, the mechanical limits of protection and the modes of failure when subjected to breaking stresses have not been well explored. We studied the mechanical properties of whole shells and of isolated bony tissues and sutures in four species of turtles (Trachemys scripta, Malaclemys terrapin, Chrysemys picta, and Terrapene carolina) using a combination of structural and mechanical tests. Structural properties were evaluated by subjecting whole shells to compressive and point loads in order to quantify maximum load, work to failure, and relative shell deformations. The mechanical properties of bone and sutures from the plastral region of the shell were evaluated using three-point bending experiments. Analysis of whole shell structural properties suggests that small shells undergo relatively greater deformations before failure than do large shells and similar amounts of energy are required to induce failure under both point and compressive loads. Location of failures occurred far more often at sulci than at sutures (representing the margins of the epidermal scutes and the underlying bones, respectively), suggesting that the small grooves in the bone created by the sulci introduce zones of weakness in the shell. Values for bending strength, ultimate bending strain, Young's modulus, and energy absorption, calculated from the three-point bending data, indicate that sutures are relatively weaker than the surrounding bone, but are able to absorb similar amounts of energy due to higher ultimate strain values. PMID:23203474

  17. HR Del remnant anatomy using 2D spectral data and 3D photoionization shell models

    NASA Astrophysics Data System (ADS)

    Moraes, M.; Diaz, M.

    The HR Del nova remnant was observed with the Gemini North's IFU-GMOS. The complete results were published in \\citep{MD09}. The kinematic, morphological and abundance analysis of the ejecta was made using spatially resolved spectral data cube. The line maps show a very clumpy shell with two main circular symmetric structures. The first one is the outer part of the shell seen in Halpha , that forms two circular rings projected in the sky plane. These circular structures correspond to projection of a closed hourglass shape in the sky plane. The equatorial emission enhancement, is not a equatorial ring. It is caused by the projection in the sky plane of two spherical structures superimposed in the line of sight. There is a second main structure, seen only in the [OIII] and [NII] maps, and located inside the circular ring structure. The data do not show any abundances gradients between the polar caps and equatorial region. But, there is an abundance decreasing of Carbon and Oxygen between outer part and the inner regions of the ejecta. The 2.5D photoionization modeling of the asymmetric ejecta shell was performed using the mass distribution obtained from the observations. The 3D clumpy models that include the aspherical illumination were able to reproduce the ionization gradients between polar and equatorial regions of the shell. The aspherical illumination can also explain the differences between shell axial ratios in different lines. A total shell mass of 9 x 10-4 M_? is derived from models. We estimate that the shell mass is contained in clumps are 50% to 70%.

  18. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and... Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a device made of glass or plastic...

  19. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and... Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a device made of glass or plastic...

  20. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and... Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a device made of glass or plastic...

  1. 21 CFR 886.3800 - Scleral shell.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Scleral shell. 886.3800 Section 886.3800 Food and... Prosthetic Devices § 886.3800 Scleral shell. (a) Identification. A scleral shell is a device made of glass or plastic...

  2. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT FRESH FRUITS...Split shell means a shell having any crack which is open and conspicuous for a...shell, measured in the direction of the...

  3. 7 CFR 51.2002 - Split shell.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...AGRICULTURAL MARKETING ACT OF 1946 AND THE EGG PRODUCTS INSPECTION ACT FRESH FRUITS...Split shell means a shell having any crack which is open and conspicuous for a...shell, measured in the direction of the...

  4. Improved Connector Shell for Cable Shields

    NASA Technical Reports Server (NTRS)

    Prisk, A. L.; Rotta, J. W., Jr.

    1983-01-01

    Cable connector shell improves electrostatic and electromagnetic shielding by electrically connecting cable braid around entire circumference. Connector cable braid is slipped over ferrule and sleeve is slipped over braid, clamping it tightly to shell. Connector shell completely shields cable conductors.

  5. Cylindrical thin-shell wormholes

    E-print Network

    Ernesto F. Eiroa; Claudio Simeone

    2004-04-12

    A general formalism for the dynamics of non rotating cylindrical thin-shell wormholes is developed. The time evolution of the throat is explicitly obtained for thin-shell wormholes whose metric has the form associated to local cosmic strings. It is found that the throat collapses to zero radius, remains static or expands forever, depending only on the sign of its initial velocity.

  6. Tuna Sea Shell Pasta Ingredients

    E-print Network

    Liskiewicz, Maciej

    Tuna Sea Shell Pasta Ingredients: 8 ounces pasta shells 12 ounces tuna in water, canned 1 onion 2. Cut the ends off of the onion, and peel off the brown layers. Run under water to remove any dirt. Cut the onion in half lengthwise, and place the flat side on the cutting board. Slice across the onion, from one

  7. Discrete Shells Origami Rob Burgoon

    E-print Network

    Discrete Shells Origami Rob Burgoon Graduate student Computer Science Calif. Polytechnic State Univ introduce a way of simulating the creation of simple Origami (paper folding). The Origami is created- edge advances in the field of discrete shell modeling to meet the challenge of simulating Origami. We

  8. Delamination Analysis of Layered Shells

    Microsoft Academic Search

    R. Babaei; M. Epstein; S. A. Lukasiewicz

    2001-01-01

    This article provides a theoretical and numerical treatment of delaminations in composite shells. A large deformation theory for layered shells of arbitrarily varying thickness, including interface delamination and transverse shear effects, is developed. Asystem of layer coordinates and conjugate coordinates is introduced which allows the results to be presented in a simple compact form analogous to the theory of monocoque

  9. Flow-induced instability of double-walled carbon nanotubes based on an elastic shell model

    Microsoft Academic Search

    Y. Yan; X. Q. He; L. X. Zhang; Q. Wang

    2007-01-01

    Double-walled carbon nanotubes (DWCNTs) are modeled based on Donnell's shell theory, and flow-induced instability that is induced when pressure-driven fluid goes through the inner tube at a steady flow velocity is studied. The van der Waals (vdW) interaction between the inner and outer walls is taken into account in the modeling. The numerical simulations show that the vdW interaction has

  10. Hardness, strength, and ductility of prefabricated titanium rods used in the manufacture of spark erosion crowns.

    PubMed

    Berg, E; Davik, G; Hegdahl, T; Gjerdet, N R

    1996-04-01

    Depending on the size of the prepared tooth spark eroded and milled, Procera crowns (Nobelpharma AB, Göteborg, Sweden) are manufactured from one of five diameters of pure titanium rods. In this study microindentation hardness tests were performed on the outer 400 microns and center of 10 samples for each type of rod. Five tensile samples were also machined for each of the diameters and tested in tension in a universal testing machine. Cast titanium samples were similarly prepared and tested. Some significant differences in hardness and considerable differences in strength and ductility were identified between the prefabricated rods. In comparison, cast titanium was significantly harder and stronger but less ductile. PMID:8642529

  11. Soft vesicles in the synthesis of hard materials.

    PubMed

    Dong, Renhao; Liu, Weimin; Hao, Jingcheng

    2012-04-17

    Vesicles of surfactants in aqueous solution have received considerable attention because of their use as simple model systems for biological membranes and their applications in various fields including colloids, pharmaceuticals, and materials. Because of their architecture, vesicles could prove useful as "soft" templates for the synthesis of "hard materials". The vesicle phase, however, has been challenging and difficult to work with in the construction of hard materials. In the solution-phase synthesis of various inorganic or macromolecular materials, templating methods provide a powerful strategy to control the size, morphology, and composition of the resulting micro- and nanostructures. In comparison with hard templates, soft templates are generally constructed using amphiphilic molecules, especially surfactants and amphiphilic polymers. These types of compounds offer advantages including the wide variety of available templates, simple fabrication processes under mild conditions, and easy removal of the templates with less damage to the final structures. Researchers have used many ordered molecular aggregates such as vesicles, micelles, liquid crystals, emulsion droplets, and lipid nanotubes as templates or structure-directing agents to control the synthesis or assembly hard micro- and nanomaterials composed from inorganic compounds or polymers. In addition to their range of sizes and morphologies, vesicles present unique structures that can simultaneously supply different microenvironments for the growth and assembly of hard materials: the inner chamber of vesicles, the outer surface of the vesicles, and the space between bilayers. Two main approaches for applying vesicles in the field of hard materials have been explored: (i) in situ synthesis of micro- or nanomaterials within a specific microenvironment by vesicle templating and (ii) the assembly or incorporation of guest materials during the formation of vesicles. This Account provides an in-depth look at the research concerning the association of soft vesicles with hard materials by our laboratory and others. We summarize three main principles of soft vesicle usage in the synthesis of hard materials and detailed procedures for vesicle templating and the characterization of the synthetic mechanisms. By use of these guiding principles, a variety of inorganic materials have been prepared, such as quantum dots, noble metal nanoparticles, mesoporous structures, and hollow capsules. Polymerization within the vesicle bilayers enhances vesicle stability, and this strategy has been developed to synthesize hollow polymer materials. Since 2004, our group has pursued a completely different strategy in the synthesis of micro- and nanomaterials using vesicles as reactive templates. In this method, the vesicles act not only as templates but also as reactive precursors. Because of the location of metal ions on the bilayer membranes, such reactions are restricted to the interface of the vesicle membrane and solution. Finally, using the perspective of soft matter chemistry, we stress some basic criteria for vesicle templating. PMID:22257298

  12. Bacterial outer membrane vesicles and vaccine applications.

    PubMed

    Acevedo, Reinaldo; Fernández, Sonsire; Zayas, Caridad; Acosta, Armando; Sarmiento, Maria Elena; Ferro, Valerie A; Rosenqvist, Einar; Campa, Concepcion; Cardoso, Daniel; Garcia, Luis; Perez, Jose Luis

    2014-01-01

    Vaccines based on outer membrane vesicles (OMV) were developed more than 20?years ago against Neisseria meningitidis serogroup B. These nano-sized structures exhibit remarkable potential for immunomodulation of immune responses and delivery of meningococcal antigens or unrelated antigens incorporated into the vesicle structure. This paper reviews different applications in OMV Research and Development (R&D) and provides examples of OMV developed and evaluated at the Finlay Institute in Cuba. A Good Manufacturing Practice (GMP) process was developed at the Finlay Institute to produce OMV from N. meningitidis serogroup B (dOMVB) using detergent extraction. Subsequently, OMV from N. meningitidis, serogroup A (dOMVA), serogroup W (dOMVW), and serogroup X (dOMVX) were obtained using this process. More recently, the extraction process has also been applied effectively for obtaining OMV on a research scale from Vibrio cholerae (dOMVC), Bordetella pertussis (dOMVBP), Mycobacterium smegmatis (dOMVSM), and BCG (dOMVBCG). The immunogenicity of the OMV has been evaluated for specific antibody induction, and together with functional bactericidal and challenge assays in mice has shown their protective potential. dOMVB has been evaluated with non-neisserial antigens, including with a herpes virus type 2 glycoprotein, ovalbumin, and allergens. In conclusion, OMV are proving to be more versatile than first conceived and remain an important technology for development of vaccine candidates. PMID:24715891

  13. Turbulent Mixing in the Outer Solar Nebula

    E-print Network

    N. J. Turner; K. Willacy; G. Bryden; H. W. Yorke

    2005-11-10

    The effects of turbulence on the mixing of gases and dust in the outer Solar nebula are examined using 3-D MHD calculations in the shearing-box approximation with vertical stratification. The turbulence is driven by the magneto-rotational instability. The magnetic and hydrodynamic stresses in the turbulence correspond to an accretion time at the midplane about equal to the lifetimes of T Tauri disks, while accretion in the surface layers is thirty times faster. The mixing resulting from the turbulence is also fastest in the surface layers. The mixing rate is similar to the rate of radial exchange of orbital angular momentum, so that the Schmidt number is near unity. The vertical spreading of a trace species is well-matched by solutions of a damped wave equation when the flow is horizontally-averaged. The damped wave description can be used to inexpensively treat mixing in 1-D chemical models. However, even in calculations reaching a statistical steady state, the concentration at any given time varies substantially over horizontal planes, due to fluctuations in the rate and direction of the transport. In addition to mixing species that are formed under widely varying conditions, the turbulence intermittently forces the nebula away from local chemical equilibrium. The different transport rates in the surface layers and interior may affect estimates of the grain evolution and molecular abundances during the formation of the Solar system.

  14. The Outer Heliosphere: The Next Frontier

    NASA Astrophysics Data System (ADS)

    Heber, B.; Zank, G. P.

    Only a few decades after the formulation of the concept of a continuous solar corpus- cular radiation by Ludwig Biermann and a solar wind by Eugene Parker, heliospheric physics has evolved into an important branch of astrophysical research. The solar wind forms a bubble, called the heliosphere, in the local interstellar medium, within which the solar system resides and whose size and properties are determined by the manner in which the solar wind and the partially ionized local interstellar medium are coupled. In the last decade, great progress has been made in our understanding of the physical processes thought to describe the outer heliosphere. Numerous spacecraft missions have increased our knowledge about the large-scale structure, the properties, and the character of the heliosphere tremendously. of these, the ageing spacecraft Voyager 1,2 might encounter the inner border of the heliospheric boundary region in the not too distant future. Now, at the beginning of a new millenium, it seems possible, by newly developed technologies to send an interstellar probe beyond the boundaries of the he- liosphere, in order to explore the local interstellar medium in situ. We shall review our basic understanding of global heliospheric structure, emphasizing the importance of the LISM-solar wind coupling, emphasizing the demands and constraints that this places on a mission to the edge of interstellar space.

  15. The Outer Heliosphere: The Next Frontiers

    NASA Astrophysics Data System (ADS)

    Scherer, K.; Fichtner, Horst; Fahr, Hans Jörg; Marsch, Eckart

    The 11th COSPAR Colloquium "The Outer Heliosphere: The Next Frontiers" was held in Potsdam, Germany, from July 24 to 28, 2000, and is the second dedicated to this subject after the first one held in Warsaw, Poland in 1989. Roughly a century has passed after the first ideas by Oliver Lodge, George Francis Fitzgerald and Kristan Birkeland about particle clouds emanating from the Sun and interacting with the Earth environment. Only a few decades after the formulation of the concepts of a continuous solar corpuscular radiation by Ludwig Bierman and a solar wind by Eugene Parker, heliospheric physics has evolved into an important branch of astrophysical research. Numerous spacecraft missions have increased the knowledge about the heliosphere tremendously. Now, at the beginning of a new millenium it seems possible, by newly developed propulasion technologies to send a spacecraft beyond the boundaries of the heliosphere. Such an Interstellar Proce will start the in-situ exploration of interstellar space and, thus, can be considered as the first true astrophysical spacecraft. The year 2000 appeared to be a highly welcome occassion to review the achievements since the last COSPAR Colloquia 11 years ago, to summarize the present developments and to give new impulse for future activities in heliospheric research.

  16. Bacterial Outer Membrane Vesicles and Vaccine Applications

    PubMed Central

    Acevedo, Reinaldo; Fernández, Sonsire; Zayas, Caridad; Acosta, Armando; Sarmiento, Maria Elena; Ferro, Valerie A.; Rosenqvist, Einar; Campa, Concepcion; Cardoso, Daniel; Garcia, Luis; Perez, Jose Luis

    2014-01-01

    Vaccines based on outer membrane vesicles (OMV) were developed more than 20?years ago against Neisseria meningitidis serogroup B. These nano-sized structures exhibit remarkable potential for immunomodulation of immune responses and delivery of meningococcal antigens or unrelated antigens incorporated into the vesicle structure. This paper reviews different applications in OMV Research and Development (R&D) and provides examples of OMV developed and evaluated at the Finlay Institute in Cuba. A Good Manufacturing Practice (GMP) process was developed at the Finlay Institute to produce OMV from N. meningitidis serogroup B (dOMVB) using detergent extraction. Subsequently, OMV from N. meningitidis, serogroup A (dOMVA), serogroup W (dOMVW), and serogroup X (dOMVX) were obtained using this process. More recently, the extraction process has also been applied effectively for obtaining OMV on a research scale from Vibrio cholerae (dOMVC), Bordetella pertussis (dOMVBP), Mycobacterium smegmatis (dOMVSM), and BCG (dOMVBCG). The immunogenicity of the OMV has been evaluated for specific antibody induction, and together with functional bactericidal and challenge assays in mice has shown their protective potential. dOMVB has been evaluated with non-neisserial antigens, including with a herpes virus type 2 glycoprotein, ovalbumin, and allergens. In conclusion, OMV are proving to be more versatile than first conceived and remain an important technology for development of vaccine candidates. PMID:24715891

  17. Controlled nanostructuring of multiphase core-shell nanowires by a template-assisted electrodeposition approach.

    PubMed

    Shi, Dawei; Chen, Junyang; Riaz, Saira; Zhou, Wenping; Han, Xiufeng

    2012-08-01

    Multiphase core-shell nanowires have been fabricated by controlling the ion transport processes of the microfluids in the nanochannels of the template. Both forced convection and pulsed potential induced migration can be applied to tune the morphologies of the nanostructures obtained by manipulating the ion transport during electrodeposition. The morphology and content of the core-shell structure were studied by field emission scanning electron microscope (FESEM) analysis, transmission electron microscope (TEM) analysis and energy dispersive spectrometry (EDS), respectively. The magnetic properties were analyzed by vibrating sample magnetometer (VSM) analysis. A magnetically hard core and soft shell constitutes the multiphase composite nanostructure. The unique magnetic hysteresis curve indicates the decoupled magnetic reversal processes of the two components. Our work provides deeper insights into the formation mechanisms of a new core-shell nanostructure, which may have potential applications in novel spintronics devices. PMID:22751156

  18. Analysis of toughening mechanisms in the Strombus gigas shell.

    PubMed

    DiPette, Scott; Ural, Ani; Santhanam, Sridhar

    2015-08-01

    A finite element analysis of the fracture mechanisms in the Strombus gigas conch shell is presented in this work. The S. gigas shell has a complex microarchitecture that consists of three main macroscopic layers of calcium carbonate: the inner, middle, and outer layers. Each layer is composed of lamellae of calcium carbonate, held together by a cohesive organic protein. As a result of this elaborate architecture, the S. gigas shell exhibits a much greater damage tolerance than the calcium carbonate by itself, with a work of fracture reported to be three magnitudes of order greater. The two main energy dissipating factors that contribute to this are multiple, parallel cracking along first-order interfaces in the inner and outer layers and crack bridging through the second-order interfaces of the middle layer. Finite element analysis was conducted to simulate and replicate flexural strength and work-of-fracture results obtained in the literature for both dry and wet physical bend test specimens. Several parameters were varied including protein strength and fracture toughness, initial protein damage, and the relative heights of macroscopic layers in order to create a model that predicted published, experimental results. The simulations indicate that having some initially weakened protein interfaces is key to matching the parallel cracking in the inner layer of the physical specimens. The wet models exhibit significantly higher work of fracture compared to the dry specimens in large part due to a crack growth resistance behavior in the middle layer, which was successfully modeled. The parametric studies that have been performed on the finite element models provide guidelines for manufacturing the ideal S. gigas-inspired, biomimetic composite. PMID:25955562

  19. The role of cholesterol in rod outer segment membranes

    Microsoft Academic Search

    Arlene D. Albert; Kathleen Boesze-Battaglia

    2005-01-01

    The photoreceptor rod outer segment (ROS) provides a unique system in which to investigate the role of cholesterol, an essential membrane constituent of most animal cells. The ROS is responsible for the initial events of vision at low light levels. It consists of a stack of disk membranes surrounded by the plasma membrane. Light capture occurs in the outer segment

  20. Propagation of Interplanetary Disturbances in the Outer Heliosphere

    NASA Technical Reports Server (NTRS)

    Wang, Chi

    2002-01-01

    Work finished during 2002 included: (1) Finished a multi-fluid solar wind model; (2) Determined the solar wind slowdown and interstellar neutral density; (3) Studied shock propagation and evolution in the outer heliosphere; (4) Investigated statistical properties of the solar wind in the outer heliosphere.

  1. Ces`aro Sum Approximation of Outer Functions

    E-print Network

    Pearce, Kent

    and Statistics Texas Tech University barnard@math.ttu.edu, pearce@math.ttu.edu J. Cima Department of Mathematics of these approximants. 2 Outer Functions Recall that an outer function is a function f in Hp of the form 2 #12;f(z) = ei

  2. Long-Lived Glass Mirrors For Outer Space

    NASA Technical Reports Server (NTRS)

    Bouquet, Frank L.; Maag, Carl R.; Heggen, Philip M.

    1988-01-01

    Paper summarizes available knowledge about glass mirrors for use in outer space. Strengths and weaknesses of various types of first and second reflective surfaces identified. Second-surface glass mirrors used in outer space designed to different criteria more stringent for terrestrial mirrors. Protons, electrons, cosmic rays, meteorites, and orbiting space debris affect longevities of components. Contamination also factor in space.

  3. Mitochondria and cell death: outer membrane permeabilization and beyond

    Microsoft Academic Search

    Stephen W. G. Tait; Douglas R. Green

    2010-01-01

    Mitochondrial outer membrane permeabilization (MOMP) is often required for activation of the caspase proteases that cause apoptotic cell death. Various intermembrane space (IMS) proteins, such as cytochrome c, promote caspase activation following their mitochondrial release. As a consequence, mitochondrial outer membrane integrity is highly controlled, primarily through interactions between pro- and anti-apoptotic members of the B cell lymphoma 2 (BCL-2)

  4. Newborns' Face Recognition: Role of Inner and Outer Facial Features

    Microsoft Academic Search

    Chiara Turati; Viola Macchi Cassia; Francesca Simion; Irene Leo

    2006-01-01

    Existing data indicate that newborns are able to recognize individual faces, but little is known about what perceptual cues drive this ability. The current study showed that either the inner or outer features of the face can act as sufficient cues for newborns' face recognition (Experiment 1), but the outer part of the face enjoys an advantage over the inner

  5. Is the outer Solar System chaotic? WAYNE B. HAYES

    E-print Network

    Loss, Daniel

    LETTERS Is the outer Solar System chaotic? WAYNE B. HAYES Computer Science Department, University. There exists both apparently unassailable evidence that the outer Solar System is chaotic1 development. The Solar System is known to be `practically stable', in the sense that none of the known planets

  6. Pc2 EMIC waves generated high off the equator in the dayside outer magnetosphere

    NASA Astrophysics Data System (ADS)

    Fraser, B. J.; Liu, Y.; Menk, F. W.

    2012-12-01

    It is generally accepted that electromagnetic ion cyclotron (EMIC) waves are generated around the equatorial regions and propagate toward the high latitude ionospheres in both hemispheres. Here we describe a prolonged EMIC wave event in the Pc2 (0.1-0.2 Hz) frequency band above the He+ cyclotron frequency detected by the four Cluster satellites as they traversed sunward from L~13 in the outer magnetosphere to the magnetopause, over 13 - 20 degrees magnetic latitude north of the equator and across the high latitude cusp region near local magnetic noon. Wave packet energy propagated dominantly along the geomagnetic field direction, confirming this was a traveling EMIC wave rather than a toroidal field line resonance. The energy packets propagated in alternating directions rather than uni-directionally from the equator, implying the wave source was located in a high latitude region away from the equator, where a minimum in the B field is located. The CIS-CODIF H+ ion data provided evidence that the waves were generated locally via the ion cyclotron instability. We believe the off-equatorial minimum magnetic field regions, associated with drift shell splitting and/or Shabansky orbits, may be important source regions for these waves in the outer magnetosphere.

  7. Core-shell-shell nanorods for controlled release of silver that can serve as a nanoheater for photothermal treatment on bacteria.

    PubMed

    Hu, Bo; Wang, Ning; Han, Lu; Chen, Ming-Li; Wang, Jian-Hua

    2015-01-01

    A novel bactericidal material comprising rod-shaped core-shell-shell Au-Ag-Au nanorods is constructed as a nanoheater in the near-infrared (NIR) region. The outer Au shell melts under laser irradiation and results in exposure of the inner Ag shell, facilitating the controlled release of the antibacterial Ag shell/layer or Ag(+). This results in the Au-Ag-Au nanorods having a favorable bactericidal ability as it combines the features of physical photothermal ablation sterilization of the outer Au shell and the antibacterial effect of the inner Ag shell or Ag(+) to the surrounding bacteria. The sterilizing ability of Au-Ag-Au nanorods is investigated with Escherichia coli O157:H7 as a model bacterial strain. Under low-power NIR laser irradiation (785 nm, 50 mW cm(-2)), the Au-Ag-Au nanoheater exhibits a higher photothermal conversion efficiency (with a solution temperature of 44°C) with respect to that for the Au-Ag nanorods (39°C). Meanwhile, a much improved stability with respect to Au-Ag nanorods is observed, i.e., 16 successive days of monitoring reveal virtually no change in the ultraviolet-visible spectrum of Au-Ag-Au nanorods, while a significant drop in absorption along with a 92 nm red shift of Localized Surface Plasmon Resonance is recorded for the Au-Ag nanorods. This brings an increasing bactericidal efficiency and long-term stability for the Au-Ag-Au nanorods. At a dosage of 10 ?g ml(-1), a killing rate of 100% is reached for the E. coli O157:H7 cells under 20 min of irradiation. The use of Au-Ag-Au nanorods avoids the abuse of broad-spectrum antibiotics and reduces the damage of tissues by alleviating the toxicity of silver under controlled release and by the use of low-power laser irradiation. These features could make the bimetallic core-shell-shell nanorods a favorable nanoheater for in vivo biomedical applications. PMID:25219350

  8. Easy Problems are Sometimes Hard

    Microsoft Academic Search

    Ian P. Gent; Toby Walsh

    1994-01-01

    We present a detailed experimental investigation of the easy-hard-easyphase transition for randomly generated instances of satisfiability problems.Problems in the hard part of the phase transition have been extensively usedfor benchmarking satisfiability algorithms. This study demonstrates thatproblem classes and regions of the phase transition previously thought tobe easy can sometimes be orders of magnitude more difficult than the worstproblems in problem

  9. Sintered titanium carbide hard alloys

    Microsoft Academic Search

    G. V. Samsonov; N. N. Sergeev; G. T. Dzodziev; V. K. Vitryanyuk; L. V. Latyaeva

    1971-01-01

    1.A study was made of the preparation of titanium carbide hard alloys with a nickel binder. It is shown that satisfactory mechanical properties (bend strength 107–115 kg\\/mm2, hardness 90–90.5 HRA) are exhibited by 80% TiC-20% Ni alloys produced from fine-milled mixtures by sintering in a vacuum of 5·10-3 mm Hg at a temperature of 1300‡C and an isothermal holding time

  10. Time of Formation and Chemical Alteration of Small Icy Objects in the Outer Solar System

    NASA Astrophysics Data System (ADS)

    Castillo-Rogez, Julie; Haw, M.; Vance, S.; Matson, D.; Johnson, T.

    2008-09-01

    We consider scenarios for the early chronology of outer solar system icy objects (e.g. satellites, dwarf planets) depending on the time at which these objects formed with respect to the production of calcium-aluminum inclusions. Recent models and observations indicate that the outer Solar system could have formed within a few My after the beginning of the Solar system. In such conditions meteorite parent bodies and icy objects (from planetesimals to large icy objects) could have had a similar early history. We investigate conditions that may drive hydrothermal activity in icy planetesimals, and the consequences of such activity for the early history of bigger objects. Early melting can be accompanied by hydrothermal circulation, resulting in aqueous alteration of the silicate interior and redistribution of major elements between the rock and volatile phases, as well as the destabilization of clathrates. These processes could have consequences on the long-term evolution of the larger bodies. For example, salts affect the melting temperature of icy shells and hydrated silicates affect heat transfer through a rocky core. We identify several classes of planetesimals based on size, time of formation, initial rock mass fraction and volatile composition. The smallest ones are not affected by short-lived radioisotope decay. The medium-sized planetesimals (in the 5-20 km range) are affected by partial melting while planetesimals several tens of km in radius could be fully differentiated before they accreted into larger objects. We explore the consequences of the potential diversity of early outer solar system planetesimal composition on the evolution of icy satellites and dwarf planets. Acknowledgements: This work has been conducted at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Copyright 2008 California Institute of Technology. Government sponsorship acknowledged.

  11. Transitions between turbulent and laminar superfluid vorticity states in the outer core of a neutron star

    E-print Network

    C. Peralta; A. Melatos; M. Giacobello; A. Ooi

    2006-07-08

    We investigate the global transition from a turbulent state of superfluid vorticity to a laminar state, and vice versa, in the outer core of a neutron star. By solving numerically the hydrodynamic Hall-Vinen-Bekarevich-Khalatnikov equations for a rotating superfluid in a differentially rotating spherical shell, we find that the meridional counterflow driven by Ekman pumping exceeds the Donnelly-Glaberson threshold throughout most of the outer core, exciting unstable Kelvin waves which disrupt the rectilinear vortex array, creating a vortex tangle. In the turbulent state, the torque exerted on the crust oscillates, and the crust-core coupling is weaker than in the laminar state. This leads to a new scenario for the rotational glitches observed in radio pulsars: a vortex tangle is sustained in the differentially rotating outer core by the meridional counterflow, a sudden spin-up event brings the crust and core into corotation, the vortex tangle relaxes back to a rectilinear vortex array, then the crust spins down electromagnetically until enough meridional counterflow builds up to reform a vortex tangle. The turbulent-laminar transition can occur uniformly or in patches; the associated time-scales are estimated from vortex filament theory. We calculate numerically the global structure of the flow with and without an inviscid superfluid component, for Hall-Vinen and Gorter-Mellink forms of the mutual friction. We also calculate the post-glitch evolution of the angular velocity of the crust and its time derivative, and compare the results with radio pulse timing data, predicting a correlation between glitch activity and Reynolds number.

  12. Crack problems in cylindrical and spherical shells

    NASA Technical Reports Server (NTRS)

    Erdogan, F.

    1976-01-01

    Standard plate or shell theories were used as a starting point to study the fracture problems in thin-walled cylindrical and spherical shells, assuming that the plane of the crack is perpendicular to the surface of the sheet. Since recent studies have shown that local shell curvatures may have a rather considerable effect on the stress intensity factor, the crack problem was considered in conjunction with a shell rather than a plate theory. The material was assumed to be isotropic and homogeneous, so that approximate solutions may be obtained by approximating the local shell crack geometry with an ideal shell which has a solution, namely a spherical shell with a meridional crack, a cylindrical shell with a circumferential crack, or a cylindrical shell with an axial crack. A method of solution for the specially orthotropic shells containing a crack was described; symmetric and skew-symmetric problems are considered in cylindrical shells with an axial crack.

  13. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Downs, R. L.; Ebner, M. A.; Nolen, R. L., Jr.

    1981-01-01

    Highly-uniform, hollow glass spheres (shells), which are used for inertial confinement fusion targets, were formed from metal-organic gel powder feedstock in a vertical furnace. As a result of the rapid pyrolysis caused by the furnace, the gel is transformed to a shell in five distinct stages: (a) surface closure of the porous gel; (b) generation of a closed-cell foam structure in the gel; (c) spheridization of the gel and further expansion of the foam; (d) coalescence of the closed-cell foam to a single-void shell; and (e) fining of the glass shell. The heat transfer from the furnace to the falling gel particle was modeled to determine the effective heating rate of the gel. The model predicts the temperature history for a particle as a function of mass, dimensions, specific heat, and absorptance as well as furnace temperature profile and thermal conductivity of the furnace gas. A model was developed that predicts the gravity-induced degradation of shell concentricity in falling molten shells as a function of shell characteristics and time.

  14. On the Loss of Outer Radiation Belt Relativistic Electrons during Geomagnetic Storm Main Phases

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Reeves, G. D.; Friedel, R. H.; Cayton, T.; Hartinger, M.

    2006-12-01

    Understanding the loss of relativistic electrons in the Earth's outer radiation belt during geomagnetic storm main phases is of great significance for the development of space weather models. It is known that the possible loss mechanisms include relocation of particles due to changing magnetic configuration, precipitation into the atmosphere due to wave-particle interactions, and the encounters with the magnetopause boundary, so called "magnetopause shadowing". However, no quantitative relationship among the three mechanisms has been established yet. To solve this issue, we will perform a statistical study of the pitch angle resolved electron data from three LANL geosynchronous satellites (data duration ~190 days) and the SCATHA satellite (data duration ~10 years), which covers regions around and outside geosynchronous orbit. By transforming flux into density in phase space the adiabatic effects are removed first to identify the "real" losses. Then by studying the electron pitch angle distributions and locating the outermost closed drift shells, we should be able to differentiate the last two loss mechanisms. A recently developed fitting method is applied to study the pitch angle distribution statistically, and the outmost closed drift shell is traced in empirical magnetic models (e.g., the T01 storm model). This study will produce a statistical model quantitatively describing the loss of relativistic electrons due to each mechanism, as a function of radial position, local time, and storm intensities.

  15. Magnetic Fields of the Outer Planets

    NASA Astrophysics Data System (ADS)

    Russell, C. T.; Dougherty, M. K.

    2010-05-01

    The rapidly rotating giant planets of the outer solar system all possess strong dynamo-driven magnetic fields that carve a large cavity in the flowing magnetized solar wind. Each planet brings a unique facet to the study of planetary magnetism. Jupiter possesses the largest planetary magnetic moment, 1.55×1020 Tm3, 2×104 times larger than the terrestrial magnetic moment whose axis of symmetry is offset about 10° from the rotation axis, a tilt angle very similar to that of the Earth. Saturn has a dipole magnetic moment of 4.6×1018 Tm3 or 600 times that of the Earth, but unlike the Earth and Jupiter, the tilt of this magnetic moment is less than 1° to the rotation axis. The other two gas giants, Uranus and Neptune, have unusual magnetic fields as well, not only because of their tilts but also because of the harmonic content of their internal fields. Uranus has two anomalous tilts, of its rotation axis and of its dipole axis. Unlike the other planets, the rotation axis of Uranus is tilted 97.5° to the normal to its orbital plane. Its magnetic dipole moment of 3.9×1017 Tm3 is about 50 times the terrestrial moment with a tilt angle of close to 60° to the rotation axis of the planet. In contrast, Neptune with a more normal obliquity has a magnetic moment of 2.2×1017 Tm3 or slightly over 25 times the terrestrial moment. The tilt angle of this moment is 47°, smaller than that of Uranus but much larger than those of the Earth, Jupiter and Saturn. These two planets have such high harmonic content in their fields that the single flyby of Voyager was unable to resolve the higher degree coefficients accurately. The four gas giants have no apparent surface features that reflect the motion of the deep interior, so the magnetic field has been used to attempt to provide this information. This approach works very well at Jupiter where there is a significant tilt of the dipole and a long baseline of magnetic field measurements (Pioneer 10 to Galileo). The rotation rate is 870.536° per day corresponding to a (System III) period of 9 h 55 min 26.704 s. At Saturn, it has been much more difficult to determine the equivalent rotation period. The most probable rotation period of the interior is close to 10 h 33 min, but at this writing, the number is still uncertain. For Uranus and Neptune, the magnetic field is better suited for the determination of the planetary rotation period but the baseline is too short. While it is possible that the smaller planetary bodies of the outer solar system, too, have magnetic fields or once had, but the current missions to Vesta, Ceres and Pluto do not include magnetic measurements.

  16. Modelling the Diversity of Outer Planetary Systems

    NASA Technical Reports Server (NTRS)

    Lissauer, Jack J.; Levison, H. F.; Duncan, M. J.; DeVincenzi, Donald L. (Technical Monitor)

    1998-01-01

    The process of planetary growth is extremely complicated, involving a myriad of physical and chemical processes, many of which are poorly understood. The ultimate configuration that a planetary system attains depends upon the properties of the disk out of which it grew, of the star at the center of the disk and, at least in some cases, of the interstellar environment. In an effort to numerically survey the possible diversity of planetary systems, we have constructed synthetic systems of giant planets and integrated their orbits to determine the dynamical lifetimes and thus the viability of these systems. Our construction algorithm begins with 110 -- 180 planetesimals located between 4 and 40 AU from a one solar mass star; most initial planetesimals have masses several tenths that of Earth. We integrate the orbits of these bodies subject to mutual gravitational perturbations and -as drag for 10(exp 6) - 10(exp 7) years, merging any pair of planetesimals which pass within one-tenth of a Hill Sphere of one another and adding "gas" to embryos larger than 10 Earth masses. Use of such large planetesimal radii provided sufficient damping to prevent the system from excessive dynamical heating. Subsequently, systems were evolved without gas drag, either with the enlarged radii or with more realistic radii. Systems took from a few million years to greater than ten billion years to become stable (10(exp 9) years without mergers of ejections). Some of the systems produced with the enlarged radii closely resemble our outer Solar System. Many systems contained only Uranus-mass objects. Encounters in simulations using realistic radii resulted in ejections, typically leaving only a few planets per system, most of which were on very eccentric orbits. Some of the systems that we constructed were stable for at least a billion years despite undergoing macroscopic orbital changes on much shorter timescales.

  17. Synthesis of triple-layered Ag@Co@Ni core-shell nanoparticles for the catalytic dehydrogenation of ammonia borane.

    PubMed

    Qiu, Fangyuan; Liu, Guang; Li, Li; Wang, Ying; Xu, Changchang; An, Cuihua; Chen, Chengcheng; Xu, Yanan; Huang, Yanan; Wang, Yijing; Jiao, Lifang; Yuan, Huatang

    2014-01-01

    Triple-layered Ag@Co@Ni core-shell nanoparticles (NPs) containing a silver core, a cobalt inner shell, and a nickel outer shell were formed by an in situ chemical reduction method. The thickness of the double shells varied with different cobalt and nickel contents. Ag0.04 @Co0.48 @Ni0.48 showed the most distinct core-shell structure. Compared with its bimetallic core-shell counterparts, this catalyst showed higher catalytic activity for the hydrolysis of NH3 BH3 (AB). The synergetic interaction between Co and Ni in Ag0.04 @Co0.48 @Ni0.48 NPs may play a critical role in the enhanced catalytic activity. Furthermore, cobalt-nickel double shells surrounding the silver core in the special triple-layered core-shell structure provided increasing amounts of active sites on the surface to facilitate the catalytic reaction. These promising catalysts may lead to applications for AB in the field of fuel cells. PMID:24302541

  18. Comparative study of shell swab and shell crush methods for the recovery of Salmonella from shell eggs.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Swabbing (SW) is the standard methodology for the recovery of resident microorganisms from shell eggs in Japan. A comparative study of shell swab (SW) and a shell crush (CR) technique was performed to recover the laboratory-inoculated Salmonella from shell eggs. It was found that the recovery of ...

  19. Development of a Prototype Nickel Optic for the Constellation-X Hard-X-Ray Telescope

    NASA Technical Reports Server (NTRS)

    Basso, S.; Bruni, R. J.; Citerio, O.; Engelhaupt, D.; Ghigo, M.; Gorenstien, P.; Mazzoleni, F.; ODell, S. L.; Pareschi, G.; Ramsey, B. D.

    2003-01-01

    The Constellation-X mission, planned for launch in 2011, will feature an array of hard-x ray telescopes with a total collecting area goal of 1500 square centimeters at 40 keV. Various technologies are currently being investigated for the optics of these telescopes including multilayer-coated Eletroformed-Nickel-Replicated (ENR) shells. The attraction of the ENR process is that the resulting full-shell optics are inherently stable and offer the promise of good angular resolution and enhanced instrument sensitivity. The challenge for this process is to meet a relatively tight weight budget with a relatively dense material (rho nickel = 9 grams per cubic centimeters.) To demonstrate the viability of the ENR process we are fabricating a prototype HXT mirror module to be tested against a competing segmented-glass-shell optic. The ENR prototype will consist of 5 shells of diameters from 150 mm to 280 mm and of 426 mm total length. To meet the stringent weight budget for Con-X, the shells will be only 150 micron thick. The innermost of these will be coated with Iridium, while the remainder will be coated with graded-density multilayers. Mandrels for these shells are currently under fabrication (Jan 03), with the first shells scheduled for production in February 03. A tentative date of late Summer has been set for prototype testing. Issues currently being addressed are the control of stresses in the multiplayer coating and ways of mitigating their effects on the figure of the necessarily thin shells. Also, the fabrication, handling and mounting of these shells without inducing permanent figure distortions. A full status report on the prototype optic will be presented along with test results as available.

  20. Structural basis for the fracture toughness of the shell of the conch Strombus gigas

    NASA Astrophysics Data System (ADS)

    Kamat, S.; Su, X.; Ballarini, R.; Heuer, A. H.

    2000-06-01

    Natural composite materials are renowned for their mechanical strength and toughness: despite being highly mineralized, with the organic component constituting not more than a few per cent of the composite material, the fracture toughness exceeds that of single crystals of the pure mineral by two to three orders of magnitude. The judicious placement of the organic matrix, relative to the mineral phase, and the hierarchical structural architecture extending over several distinct length scales both play crucial roles in the mechanical response of natural composites to external loads. Here we use transmission electron microscopy studies and beam bending experiments to show that the resistance of the shell of the conch Strombus gigas to catastrophic fracture can be understood quantitatively by invoking two energy-dissipating mechanisms: multiple microcracking in the outer layers at low mechanical loads, and crack bridging in the shell's tougher middle layers at higher loads. Both mechanisms are intimately associated with the so-called crossed lamellar microarchitecture of the shell, which provides for `channel' cracking in the outer layers and uncracked structural features that bridge crack surfaces, thereby significantly increasing the work of fracture, and hence the toughness, of the material. Despite a high mineral content of about 99% (by volume) of aragonite, the shell of Strombus gigas can thus be considered a `ceramic plywood', and can guide the biomimetic design of tough, lightweight structures.

  1. Structural basis for the fracture toughness of the shell of the conch Strombus gigas.

    PubMed

    Kamat, S; Su, X; Ballarini, R; Heuer, A H

    2000-06-29

    Natural composite materials are renowned for their mechanical strength and toughness: despite being highly mineralized, with the organic component constituting not more than a few per cent of the composite material, the fracture toughness exceeds that of single crystals of the pure mineral by two to three orders of magnitude. The judicious placement of the organic matrix, relative to the mineral phase, and the hierarchical structural architecture extending over several distinct length scales both play crucial roles in the mechanical response of natural composites to external loads. Here we use transmission electron microscopy studies and beam bending experiments to show that the resistance of the shell of the conch Strombus gigas to catastrophic fracture can be understood quantitatively by invoking two energy-dissipating mechanisms: multiple microcracking in the outer layers at low mechanical loads, and crack bridging in the shell's tougher middle layers at higher loads. Both mechanisms are intimately associated with the so-called crossed lamellar microarchitecture of the shell, which provides for 'channel' cracking in the outer layers and uncracked structural features that bridge crack surfaces, thereby significantly increasing the work of fracture, and hence the toughness, of the material. Despite a high mineral content of about 99% (by volume) of aragonite, the shell of Strombus gigas can thus be considered a 'ceramic plywood' and can guide the biomimetic design of tough, lightweight structures. PMID:10890440

  2. Core-shell structured PEO-chitosan nanofibers by coaxial electrospinning.

    PubMed

    Pakravan, Mehdi; Heuzey, Marie-Claude; Ajji, Abdellah

    2012-02-13

    Core-shell structured PEO-chitosan nanofibers have been produced using a coaxial electrospinning setup. PEO and chitosan solutions, both in an aqueous acetic acid solvent, were used as the inner (core) and outer (shell) layer, respectively. Uniform-sized defect-free nanofibers of 150-190 nm diameter were produced. In addition, hollow nanofibers could be obtained subsequent to PEO washing of the membranes. The core-shell nanostructure and existence of chitosan on the shell layer were confirmed by TEM images obtained before and after washing the PEO content with water. The presence of chitosan on the surface of the composite nanofibers was further supported by XPS studies. The chitosan and PEO compositions in the nanofibrous mats were determined by TGA analysis, which were similar to their ratio in the feed solutions. The local compositional homogeneity of the membranes and the efficiency of the washing step to remove PEO were also verified by FTIR. In addition, DSC and XRD were used to characterize the crystalline structure and morphology of the co-electrospun nonwoven mats. The prepared coaxial nanofibers (hollow and solid) have several potential applications due to the presence of chitosan on their outer surfaces. PMID:22229633

  3. Experimental investigation of indirectly-driven, ignition-like double- shell implosions

    NASA Astrophysics Data System (ADS)

    Robey, H. F.; Amendt, P. A.; Park, H. S.; Tipton, R. E.; Louis, H.; Hibbard, R. L.; Bono, M. J.; Wallace, R. J.; Turner, R. E.; Milovich, J. L.; Rowley, D. P.; Glebov, V. Yu.; Marciante, J. R.

    2003-10-01

    An experimental campaign has recently been conducted on the Omega Laser to study the performance of indirectly-driven, ignition-like double-shell implosions. These targets are of interest as they provide a possible non-cryogenic path to ignition on the NIF. In particular, these capsules were designed to produce significantly more DD neutron yield from the compressional phase of the implosion as opposed to that generated at shock convergence alone. This goal imposes severe constraints on the capsule tolerances and the driving laser pulse shape, both of which have been optimized to minimize the effects of interfacial mix between the inner shell and the DD fuel. The capsules, which have an outer diameter of 550?, are assembled from a central DD-filled CH shell surrounded by a series of precision-machined hemispherical shells of 50mg/cc carbon foam and an outer ablator of Br-doped CH, all of which have dimensional tolerances of less than 5µm. The results of the experiments are described and compared with 2D integrated hohlraum simulations. The DD neutrons yields were observed to be remarkably consistent and were approximately 20 times the predicted yield due to shock convergence alone. Directions for further improvement in capsule performance are discussed.

  4. Shells in the C2 coma of Comet P/Halley

    NASA Technical Reports Server (NTRS)

    Schulz, Rita; A'Hearn, Michael F.

    1995-01-01

    We reanalyzed the CN images of Comet P/Halley, in which jets have been discovered for the first time, in search of shell structures. Shells were actually detected at the outer edges of the frames on those dates for which shells with radii small enough to be covered by the limited field of view of the CCD were predicted. The C2 images of the same data set were subjected to an analogous investigation which led to the discovery of shell structures in C2 as well. The morphology of the CN and the C2 shells is essentially equal on the same observational date. They have the same radii and show almost identical asymmetries which suggests that CN and C2 in the shells originate from the same general source. The comparison of the jets in both species before and after a two-dimensional continuum subtraction supports this supposition. The similar morphology of the jets indicates that both species are produced from the same bulk of precursor material which has been ejected in the form of jets from the same active area. However, similarly located and oriented jets in CN and C2 do not show similar relative intensities in most cases. These differences in the intensity distribution imply that the production rates of CN and C2 follow different laws.

  5. Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.

    PubMed

    Sun, Jing Ya; Wang, Zhi Kui; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau; Tran, Toan Trong; Lu, Xianmao

    2010-12-28

    The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Sto?ber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics. PMID:21087022

  6. Is the umbo matrix of bivalve shells (Laternula elliptica) a climate archive?

    PubMed

    Dick, D; Philipp, E; Kriews, M; Abele, D

    2007-10-30

    Heavy metal accumulation into bivalve soft tissues has received increasing interest in recent years with respect to biomonitoring of environmental change including pollution. To a lesser extent, accretion of elements from the environment into bivalve hard structures (shells) has been investigated, although the importance of the shells as environmental archives has been acknowledged. Here we report element distribution within consecutive growth bands in the shells of the Antarctic soft shell clam Laternula elliptica, which is currently exposed to vast environmental change in Antarctic Peninsula coastal environments that undergo rapid climate warming. We performed a high spatial resolution analysis for Al, Fe, Mn, Cu, Pb and U in the shell umbo, by means of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Element ratios within the umbo did not resemble either the ratios in the surrounding seawater, the sedimenting material in Potter Cove, or even the Earth's crust basal composition. Mn and Cu were preferentially incorporated into the umbo. A strong decrease of element accretion with time could be related to lifetime respiration mass (R) of the animals. This indicates element accretion into the umbo and shell matrix to be largely a function of animal ecophysiology and life history, and these effects need to be considered in the context of potential usefulness of L. elliptica shells as environmental archives. PMID:17727974

  7. Feshbach resonances in inner-shell photodetachment: The case of Te-

    NASA Astrophysics Data System (ADS)

    Kjeldsen, H.; Folkmann, F.; Jacobsen, T. S.; West, J. B.

    2004-05-01

    Bound 4d inner-shell excited states have been observed as 4 d10 5 s2 5 p5 ?4 d9 5 s2 5 p6 2D 5/2,3/2 Feshbach resonances in the photodetachment spectrum of Te- utilizing the merged-beam technique at the storage ring ASTRID. The strong binding of these core-excited levels, 2.95 and 1.47 eV respectively, is attributed to the extra stability of the full 5p shell. The role of the present data as a prototype spectrum for negative ions having an outer shell with a single vacancy in the initial state is discussed.

  8. Feshbach resonances in inner-shell photodetachment: The case of Te{sup -}

    SciTech Connect

    Kjeldsen, H.; Folkmann, F.; Jacobsen, T.S.; West, J.B. [Department of Physics and Astronomy, University of Aarhus, DK - 8000 Aarhus C (Denmark); Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)

    2004-05-01

    Bound 4d inner-shell excited states have been observed as 4d{sup 10}5s{sup 2}5p{sup 5}{yields}4d{sup 9}5s{sup 2}5p{sup 6} {sup 2}D{sub 5/2,3/2} Feshbach resonances in the photodetachment spectrum of Te{sup -} utilizing the merged-beam technique at the storage ring ASTRID. The strong binding of these core-excited levels, 2.95 and 1.47 eV respectively, is attributed to the extra stability of the full 5p shell. The role of the present data as a prototype spectrum for negative ions having an outer shell with a single vacancy in the initial state is discussed.

  9. CuGaS2 hollow spheres from Ga-CuS core-shell nanoparticles.

    PubMed

    Cha, Ji-Hyun; Jung, Duk-Young

    2014-05-01

    A liquid gallium emulsion was prepared as a starting material using ultrasound treatment in ethylene glycol. Core-shell particles of Ga@CuS were successfully synthesized by deposition of a CuS layer on gallium droplets through sonochemical deposition of copper ions and thiourea in an alcohol media. The core and shell of Ga@CuS products were composed of amorphous gallium metal and covellite phase CuS, which transformed into chalcopyrite CuGaS2 hollow spheres after sulfurization at 450°C, which was the lowest crystallization temperature. The formation of hollow nanostructures was ascribed to the Kirkendall mechanism, in which liquid gallium particles play an important role as reactive templates. In conclusion, we obtained CuGaS2 hollow spheres with a 430 nm outer diameter and 120 nm shell thickness that had the same crystal structure and electrical properties as bulk CuGaS2. PMID:24365224

  10. Synthesis of Various Metal/TiO2 Core/shell Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Zhu, Wei; Wang, Guan-zhong; Hong, Xun; Shen, Xiao-shuang

    2011-02-01

    We present a general approach to fabricate metal/TiO2 core/shell nanorod structures by two-step electrodeposition. Firstly, TiO2 nanotubes with uniform wall thickness are prepared in anodic aluminum oxide (AAO) membranes by electrodeposition. The wall thickness of the nanotubes could be easily controlled by modulating the deposition time, and their outer diameter and length are only limited by the channel diameter and the thickness of the AAO membranes, respectively. The nanotubes' tops prepared by this method are open, while the bottoms are connected directly with the Au film at the back of the AAO membranes. Secondly, Pd, Cu, and Fe elements are filled into the TiO2 nanotubes to form core/shell structures. The core/shell nanorods prepared by this two-step process are high density and free-standing, and their length is dependent on the deposition time.

  11. The Electron Shell and Alpha Decay in Super-Heavy Nuclei

    NASA Astrophysics Data System (ADS)

    Igashov, S. Yu.; Tchuvil'Sky, Yu. M.

    2015-11-01

    The influence of the electron shell on the characteristics of the alpha decay of the 294118 isotope, as an example of a super-heavy atom, is studied theoretically. The calculation is based on direct solution of the Schrödinger equation. The rigorous quantum-mechanical approach being developed makes possible the outer boundary condition of the alpha-particle diverging wave to be taken into account properly. The effect under discussion depends on the behavior of the function of electron density both in the classically-forbidden and the classically-allowed areas of alpha-particle motion. A principally new effect - increasing of the decay rate originated by the part of electron shell located in the classically-allowed area - is revealed in the chosen example. The influence of relativistic properties of inner electrons, scenario of penetration of the alpha-particle through the atomic shell and finite size of nucleus are also studied.

  12. Post-Transgressive and Modern Erosion on the New Jersey Outer Shelf

    NASA Astrophysics Data System (ADS)

    Goff, J. A.; Austin, J. A.; Gulick, S.; Nordfjord, S.; Christensen, B.; Sommerfield, C.; Olson, H.; Alexander, C.

    2004-12-01

    Recent erosion is evident on the outer New Jersey shelf (> 50 m water depth) based on analysis of multibeam bathymetry, backscatter, and chirp seismic reflection data, as well as grab samples and short cores. Truncation at the seafloor of the transgressive ravinement surface indicates that erosion occurred in the post-transgressive environment, i.e. after passage of the shoreline and development of the surficial sand sheet that caps the ravinement. Apparently moribund oblique sand ridges are also truncated by large, erosional swales oriented along the primary modern current direction, indicating that erosion likely post dates sand ridge evolution, which is known to persist to water depths of 40 m. Post-transgressive erosion has exposed a variety of strata at the seafloor, including: shallowly buried, fluvial channel systems, formed during or somewhat after the Last Glacial Maximum and filled during the transgression; the outer shelf wedge, likely deposited during falling sea level conditions; and a regional reflector, "R", that likely represents erosion during the last regression , i.e., exposing material >40 kyr. Depths of erosion range from a few meters to >10 m. A "ribbon" seafloor morphology marks much of the eroded regions. Ribbons are observed in the backscatter data as alternating bands of low and high backscatter elongated in the direction of bottom flow. Samples from the high backscatter regions are a mixture of shell hash, mud and sand; the latter exhibit populations of both abraded and unabraded grains. The shell hash is likely an erosional lag, perhaps remnants of the transgressive ravinement surface. The muds and unabraded grains are, because of negligible modern sediment input, evidence of newly eroded, previously undisturbed sediment. The lower-backscatter areas of the ribbon morphology consist of a well-sorted medium sand unit only a few tens of cm thick, overlying the shelly-muddy-sands. Well-rounded gravels and cobbles have been found in areas with very high backscatter; seismic data through one gravel mound indicates that it is likely derived from the base of an eroded fluvial/estuarine channel. Reworking of seafloor sediment in the post-transgressive regime appears to change from sand ridge evolution in inner to middle shelf depths to more predominantly erosional modification at outer shelf depths. We speculate that this change may be related to the reduction in the effectiveness of wave resuspension of sediment with increasing water depth.

  13. Bathymetry and acoustic backscatter-outer mainland shelf, eastern Santa Barbara Channel, California

    USGS Publications Warehouse

    Dartnell, Peter; Finlayson, David P.; Ritchie, Andrew C.; Cochrane, Guy R.; Erdey, Mercedes D.

    2012-01-01

    In 2010 and 2011, scientists from the U.S. Geological Survey (USGS), Pacific Coastal and Marine Science Center (PCMSC), acquired bathymetry and acoustic-backscatter data from the outer shelf region of the eastern Santa Barbara Channel, California. These surveys were conducted in cooperation with the Bureau of Ocean Energy Management (BOEM). BOEM is interested in maps of hard-bottom substrates, particularly natural outcrops that support reef communities in areas near oil and gas extraction activity. The surveys were conducted using the USGS R/V Parke Snavely, outfitted with an interferometric sidescan sonar for swath mapping and real-time kinematic navigation equipment. This report provides the bathymetry and backscatter data acquired during these surveys in several formats, a summary of the mapping mission, maps of bathymetry and backscatter, and Federal Geographic Data Committee (FGDC) metadata.

  14. Crack-tip fields in anisotropic shells

    Microsoft Academic Search

    F. G. YUAN; S. YANG

    2002-01-01

    Asymptotic crack-tip fields including the effect of transverse shear deformation in an anisotropic shell are presented. The material anisotropy is defined here as a monoclinic material with a plane symmetry at x3 = 0. In general, the shell geometry near the local crack tip region can be considered as a shallow shell. Based on Reissner shallow shell theory, an asymptotic

  15. Unix et Programmation Shell Philippe Langevin

    E-print Network

    Faccanoni, Gloria

    Programmation Shell Automne 2013 4 / 1 #12;shell unix origine naissance de unix Parmi de nombreux hackers deux Programmation Shell Automne 2013 5 / 1 #12;shell unix origine naissance de unix Parmi de nombreux hackers deux naissance de unix Parmi de nombreux hackers deux pionniers des Bell labs sont `a l'origine du syst`eme unix

  16. The Digital Library Shell Yael Dubinsky

    E-print Network

    Yehudai, Amiram

    The Digital Library Shell Yael Dubinsky University of Rome "La Sapienza" Department of Computer Libraries The Digital Library (DL) Shell The project of development the DL shell Demonstration Summary and future work #12;3 Agenda Digital Libraries The Digital Library (DL) Shell The project of development

  17. Intergalactic shells at large redshift

    NASA Technical Reports Server (NTRS)

    Shull, J. M.; Silk, J.

    1981-01-01

    The intergalactic shells produced by galactic explosions at large redshift, whose interiors cool by inverse Compton scattering off the cosmic background radiation, have a characteristic angular size of about 1 arcmin at peak brightness. At z values lower than 2, the shells typically have a radius of 0.5 Mpc, a velocity of about 50 km/sec, a metal abundance of about 0.0001 of cosmic values, and strong radiation in H I(Lyman-alpha), He II 304 A, and the IR fine-structure lines of C II and Si II. The predicted extragalactic background emission from many shells, strongly peaked toward the UV, sets an upper limit to the number of exploding sources at z values of about 10. Shell absorption lines of H I, C II, Si II, and Fe II, which may be seen at more recent epochs in quasar spectra, may probe otherwise invisible explosions in the early universe.

  18. Stability of elastic grid shells

    E-print Network

    Mesnil, Romain, M. Eng. Massachusetts Institute of Technology

    2013-01-01

    The elastic grid shell is a solution that combines double curvature and ease of mounting. This structural system, based on the deformation of an initially at grid without shear stiffness was invented more than fifty years ...

  19. Shell proteome of rhynchonelliform brachiopods.

    PubMed

    Immel, Françoise; Gaspard, Danièle; Marie, Arul; Guichard, Nathalie; Cusack, Maggie; Marin, Frédéric

    2015-06-01

    Brachiopods are a phylum of marine invertebrates that have an external bivalved shell to protect their living tissues. With few exceptions, this biomineralized structure is composed of calcite, mixed together with a minor organic fraction, comprising secreted proteins that become occluded in the shell structure, once formed. This organic matrix is thought to display several functions, in particular, to control mineral deposition and to regulate crystallite shapes. Thus, identifying the primary structure of matrix proteins is a prerequisite for generating bioinspired materials with tailored properties. In this study, we employed a proteomic approach to identify numerous peptides that constitute the shell proteins, in three rhynchonellid brachiopods from different localities. Our results suggest that the shell protein repertoires identified thus far, differ from that of better known calcifying metazoans, such as molluscs. PMID:25896726

  20. Nuclear Shell Structure Evolution Theory

    E-print Network

    Zhengda Wang; Xiaobin Wang; Xiaodong Zhang; Xiaochun Wang

    2012-02-29

    The Self-similar-structure shell model (SSM) comes from the evolution of the conventional shell model (SM) and keeps the energy level of SM single particle harmonic oscillation motion. In SM, single particle motion is the positive harmonic oscillation and in SSM, the single particle motion is the negative harmonic oscillation. In this paper a nuclear evolution equation (NEE) is proposed. NEE describes the nuclear evolution process from gas state to liquid state and reveals the relations among SM, SSM and liquid drop model (DM). Based upon SSM and NEE theory, we propose the solution to long-standing problem of nuclear shell model single particle spin-orbit interaction energy . We demonstrate that the single particle motion in normal nuclear ground state is the negative harmonic oscillation of SSM[1][2][3][4] Key words: negative harmonic oscillation, nuclear evolution equation, self-similar shell model

  1. Insulative laser shell coupler

    DOEpatents

    Arnold, Phillip A. (Livermore, CA); Anderson, Andrew T. (Livermore, CA); Alger, Terry W. (Tracy, CA)

    1994-01-01

    A segmented coaxial laser shell assembly having at least two water jacket sections, two pairs of interconnection half rings, a dialectric break ring, and a pair of threaded ring sections. Each water jacket section with an inner tubular section that defines an inner laser cavity with water paths adjacent to at least a portion of the exterior of the inner tubular section, and mating faces at the end of the water jacket section through which the inner laser cavity opens and which defines at least one water port therethrough in communication with the water jackets. The water paths also define in their external surface a circumferential notch set back from and in close proximity to the mating face. The dielectric break ring has selected thickness and is placed between, and in coaxial alignment with, the mating faces of two of the adjacent water jacket sections. The break ring also defines an inner laser cavity of the same size and shape as the inner laser cavity of the water jacket sections and at least one water passage through the break ring to communicate with at least one water port through the mating faces of the water jacket sections.

  2. The effects of laterally varying icy shell structure on the tidal response of Europa and Ganymede

    NASA Astrophysics Data System (ADS)

    Wahr, J. M.; A, G.; Zhong, S.

    2013-12-01

    One of the long-sought objectives of an icy moon orbiter or fly-by mission, has been to use tidal observations to help determine the existence of a liquid ocean and characteristics of the overlying icy shell. The radio science component of such a mission could be used to estimate the tidal potential Love number k2 for gravity. And if there is an on-board laser altimeter, it could be used to determine the radial displacement Love number h2. Knowledge of either of those Love numbers could provide information on the presence of an ocean beneath the icy outer shell, and the two Love numbers could be combined to place constraints on the thickness of the icy shell. Though if a subsurface ocean exists, complications could conceivably arise if the icy outer shell has significant lateral variations in elastic thickness or shear modulus, or if the ocean is not global in extent so that the icy shell is grounded in places but floating in others. In these cases, the tidal deformation pattern would not be represented as the sum of degree 2 harmonics, and so the results could not be characterized in terms of a single Love number. In this study, by solving a set of tidal loading problems with laterally variable icy shell structures (for which the existence of an ocean layer is assumed), we investigate how those structures might complicate the interpretation of the tide measurements, and we discuss how to extract information regarding the interior structure of Ganymede and Europa from measurements of their tidal response.

  3. Nematic textures in spherical shells

    NASA Astrophysics Data System (ADS)

    Vitelli, V.; Nelson, D. R.

    2006-08-01

    The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short (1)/(2) disclination lines but, as the thickness of the film increases, a three-dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.

  4. Nematic textures in spherical shells

    E-print Network

    Vincenzo Vitelli; David R. Nelson

    2006-04-12

    The equilibrium texture of nematic shells is studied as a function of their thickness. For ultrathin shells the ground state has four short 1/2 disclination lines but, as the thickness of the film increases, a three dimensional escaped configuration composed of two pairs of half-hedgehogs becomes energetically favorable. We derive an exact solution for the nematic ground state in the one Frank constant approximation and study the stability of the corresponding texture against thermal fluctuations.

  5. Bioavailability of oyster shell electrolysate

    Microsoft Academic Search

    Yoshio Yoshimoto; Tatsuo Tsukamoto; Masaaki Fukase; Yasuo Imai; Tadao Fujii; Masamichi Nakai; Akira Fujimori; Kyota Ohno; Kazuto Ikeda; Hajime Yamada; Masashi Nishikawa; Yoshihiro Yamamoto; Riko Kitazawa; Takuo Fujita

    1990-01-01

    Balance studies were conducted on 4 normal elderly subjects, 2 males and 2 females, ranging in age between 66 and 86 years\\u000a in order to compare the bioavailability of oyster shell electrolysate with that of calcium carbonate and calcium lactate,\\u000a in a crossover design. In each subject, 600 mg oyster shell electrolysate was more effective than calcium carbonate or calcium

  6. Geometric calculations of thin shells

    E-print Network

    Wright, William Dennis

    1967-01-01

    GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Submitted to the Graduate College of the Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 1967 Major Subject...: Computer Science GEOMETRIC CALCULATIONS OF THIN SHELLS A Thesis by WILLIAM DENNIS WRIGHT Approved as to style and content by: (Chairman of Committee) (Nember) August 1967 ACKNOWLEDGMENT I extend my sincerest appreciation to all of those who have...

  7. Imaging of detached shells around the carbon stars R Scl and U Ant through scattered stellar light

    E-print Network

    D. Gonzalez Delgado; H. Olofsson; H. E. Schwarz; K. Eriksson; B. Gustafsson

    2001-04-09

    We present the first optical images of scattered light from large, detached gas/dust shells around two carbon stars, R Scl and U Ant, obtained in narrow band filters centred on the resonance lines of neutral K and Na, and in a Str. b filter (only U Ant). They confirm results obtained in CO radio line observations, but also reveal new and interesting structures. Towards R Scl the scattering appears optically thick in both the K and Na filters, and both images outline almost perfectly circular disks with essentially uniform intensity out to a sharp outer radius of 21". These disks are larger -- by about a factor of two -- than the radius of the detached shell which has been marginally resolved in CO radio line data. In U Ant the scattering in the K filter appears to be, at least partially, optically thin, and the image is consistent with scattering in a geometrically thin (3") shell (radius 43") with an overall spherical symmetry. The size of this shell agrees very well with that of the detached shell seen in CO radio line emission. The scattering in the Na filter appears more optically thick, and the image suggests the presence of at least one, possibly two, shells inside the 43" shell. There is no evidence for such a multiple-shell structure in the CO data, but this can be due to considerably lower masses for these inner shells. Weak scattering appears also in a shell which is located outside the 43" shell. The present data do not allow us to conclusively identify the scattering agent, but we argue that most of the emission in the K and Na filter images is to due to resonance line scattering, and that there is also a weaker contribution from dust scattering in the U Ant data. Awaiting new observational data, our interpretation must be regarded as tentative.

  8. Mobile hard substrata - An additional biodiversity source in a high latitude shallow subtidal system

    NASA Astrophysics Data System (ADS)

    Balazy, Piotr; Kuklinski, Piotr

    2013-03-01

    This study demonstrates the importance of a hard mobile substratum (hermit crab shells) for Arctic biodiversity. Based on previous observations from other geographic regions we hypothesized that this niche at high latitudes would support a higher biodiversity of epifauna than might be predicted from similar substrata. We test whether the hermit crab epifauna is specific to that substratum providing unique biodiversity components to the local community. From four study sites in Isfjorden (78°N), West Spitsbergen and two study sites in Northern Norway (69°N) we collected approximately 50 each of hermit crabs, gastropods and pebbles, of visually similar surface area using SCUBA diving. Hermit crab shells were colonized by a larger number of epifaunal species than either gastropods or pebbles, even when they were of a larger size. Among 87 taxa found on all the three substrata, 22 occurred only on hermit crab shells. Except for two study sites hermit crab shells also supported more individuals. This study shows that the contribution of shells carried by hermit crabs to high-latitude, shallow-subtidal diversity is higher than might be predicted by their surface area alone and that hermit crabs modify, maintain and create a unique habitat. This is the result of a number of factors interacting positively on the presence of epifauna including shell surface heterogeneity and the complex influence of the crab host.

  9. Shell layer variation in trace element concentration for the freshwater bivalve Elliptio complanata

    NASA Astrophysics Data System (ADS)

    Carroll, Monica; Romanek, Christopher S.

    2008-10-01

    While the elemental chemistry of marine mollusk shells contains valuable environmental information, extending these interpretations to freshwater bivalve shells may be problematic, given the wide range of aqueous chemistries that exist in freshwater environments. To better understand the significance of these records, 20 bivalves were collected from four freshwater streams to determine the geochemical relationships that exist between the bivalve shell and their sources streams. The concentrations of manganese (Mn), copper (Cu), strontium (Sr), barium (Ba), and calcium (Ca) were analyzed by laser ablation inductively coupled plasma mass spectrometry across the inner (INL) and outer nacreous layer (ONL) of each shell for comparison to stream data collected over the period of shell growth. Within an individual shell, the content of Mn, Sr, and Ba were significantly higher in the INL than the ONL, while Cu concentrations were similar. Strontium and Ba concentrations co-varied between the two layers in 1:1 relationships, while Mn displayed a preferential enrichment in the INL that increased from 2:1 to 5:1 as the Mn content of the shell decreased. Each elemental profile can be correlated between shell layers, except for the trace element Cu, which appeared to be more closely related to the organic content of the shell. These results suggest that the major element geochemistry of the shell layers differentially reflect the aqueous chemistry of the water in which a bivalve lived, but that these records are most likely overprinted by physiological processes specific to the mantle tissue from which a particular shell layer is secreted. Distribution coefficients (shell M /Ca:water M /Ca, where M = trace element of interest) were calculated using the median molar elemental concentration for each shell (by layer), and the appropriate water concentration. Bivalves from a contaminated site were excluded from this analysis because their shells were anomalous in size and color. For the remaining 15 shells, distribution coefficients (INL and ONL) were: Mn (0.50 and 0.21), Sr (0.26 and 0.17), and Ba (0.05: INL only). Inner nacreous layer values were comparable to the upper end of published estimates for freshwater bivalves and fish otoliths, while the ONL values were comparable to the lower range of values. Inclusion of shells from the contaminated site resulted in the calculation of distribution coefficients that fell outside the range of published estimates. These results suggest that exposure to pollutants may have a bearing on the biological factors that control the elemental concentration of bivalve shells in freshwater environments. While researchers generally avoid sampling shell material from the INL because of the potential for shell dissolution, the similarity in elemental profile trends observed here suggests that both the INL and ONL record accurate geochemical information, but in distinct forms. An obvious advantage of INL analysis is the relative increase in elemental concentration, but this is afforded at the expense of spatial resolution. Considered collectively, these results suggest that valuable information can be gleaned from the elemental concentration of freshwater bivalve shells when care is taken in the choice of material from which these records are extracted.

  10. Selection for egg shell strength in laying hens using shell membrane characteristics

    Microsoft Academic Search

    K. Johansson; J. Örberg; M. Wilhelmson

    1996-01-01

    1. Divergent selection for attachment strength between the shell membrane and the calcium shell was performed in a White Leghorn strain. Multivariate analysis was used to estimate genetic parameters for shell membrane measurements and shell thickness. The aim was to investigate the possibility of improving shell strength in laying hens by selecting for increased attachment strength.2. A significant direct selection

  11. Radioisotope Reduction Using Solar Power for Outer Planetary Missions

    NASA Technical Reports Server (NTRS)

    Fincannon, James

    2008-01-01

    Radioisotope power systems have historically been (and still are) the power system of choice from a mass and size perspective for outer planetary missions. High demand for and limited availability of radioisotope fuel has made it necessary to investigate alternatives to this option. Low mass, high efficiency solar power systems have the potential for use at low outer planetary temperatures and illumination levels. This paper documents the impacts of using solar power systems instead of radioisotope power for all or part of the power needs of outer planetary spacecraft and illustrates the potential fuel savings of such an approach.

  12. Phospholipid composition of highly purified mitochondrial outer membranes of rat liver and Neurospora crassa. Is cardiolipin present in the mitochondrial outer membrane?

    Microsoft Academic Search

    Anton I. P. M de Kroon; Danièle Dolis; Andreas Mayer; Roland Lill; Ben de Kruijff

    1997-01-01

    Isolated mitochondrial outer membrane vesicles (OMV) are a suitable system for studying various functions of the mitochondrial outer membrane. For studies on mitochondrial lipid import as well as for studies on the role of lipids in processes occurring in the outer membrane, knowledge of the phospholipid composition of the outer membrane is indispensable. Recently, a mild subfractionation procedure was described

  13. Carbon isotopes in mollusk shell carbonates

    Microsoft Academic Search

    Ted A. McConnaughey; David Paul Gillikin

    2008-01-01

    Mollusk shells contain many isotopic clues about calcification physiology and environmental conditions at the time of shell\\u000a formation. In this review, we use both published and unpublished data to discuss carbon isotopes in both bivalve and gastropod\\u000a shell carbonates. Land snails construct their shells mainly from respired CO2, and shell ?13C reflects the local mix of C3 and C4 plants

  14. Why small hermit crabs have large shells

    Microsoft Academic Search

    Tom M. Spight

    1985-01-01

    Summary  Frequent shell exchanges among hermit crabs imply the enigmatic circumstance that large crabs frequently obtain large shells\\u000a from smaller crabs. This seeming anomaly is explored as a key to the shell resource system. It is hypothesized to reflect\\u000a how, where, and how often shells become available to the crabs. Shells become available infrequently, as snails die, and are\\u000a available to

  15. Universal Hard-Loop Actions

    E-print Network

    Czajka, Alina

    2015-01-01

    The effective actions of gauge bosons, fermions and scalars, which are obtained within the hard-loop approximation, are shown to have unique forms for a whole class of gauge theories including QED, scalar QED, super QED, pure Yang-Mills, QCD, super Yang-Mills. The universality occurs irrespective of a field content of each theory and of variety of specific interactions. Consequently, the long-wavelength or semiclassical features of plasma systems governed by these theories such as collective excitations are almost identical. An origin of the universality, which holds within the limits of applicability of the hard-loop approach, is discussed.

  16. Universal Hard-Loop Actions

    E-print Network

    Alina Czajka; Stanislaw Mrowczynski

    2015-05-29

    The effective actions of gauge bosons, fermions and scalars, which are obtained within the hard-loop approximation, are shown to have unique forms for a whole class of gauge theories including QED, scalar QED, super QED, pure Yang-Mills, QCD, super Yang-Mills. The universality occurs irrespective of a field content of each theory and of variety of specific interactions. Consequently, the long-wavelength or semiclassical features of plasma systems governed by these theories such as collective excitations are almost identical. An origin of the universality, which holds within the limits of applicability of the hard-loop approach, is discussed.

  17. Spiral density waves in the outer galactic gaseous discs

    E-print Network

    Khoperskov, S A

    2015-01-01

    Deep HI observations of the outer parts of disc galaxies demonstrate the frequent presence of extended, well-developed spiral arms far beyond the optical radius. To understand the nature and the origin of such outer spiral structure, we investigate the propagation in the outer gaseous disc of large-scale spiral waves excited in the bright optical disc. Using hydrodynamical simulations, we show that non-axisymmetric density waves, penetrating in the gas through the outer Lindblad resonance, can exhibit relatively regular spiral structures outside the bright optical stellar disc. For low-amplitude structures, the results of numerical simulations match the predictions of a simple WKB linear theory. The amplitude of spiral structure increases rapidly with radius. Beyond $\\approx 2$ optical radii, spirals become nonlinear (the linear theory becomes quantitatively and qualitatively inadequate) and unstable to Kelvin-Helmholtz instability. In numerical simulations, in models for which gas is available very far out, ...

  18. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Outer continental shelf pipelines. 195.9 Section 195.9 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  19. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Outer continental shelf pipelines. 195.9 Section 195.9 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  20. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Outer continental shelf pipelines. 195.9 Section 195.9 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  1. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...2011-10-01 false Outer continental shelf pipelines. 192.10 Section 192.10 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL...

  2. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 false Outer continental shelf pipelines. 192.10 Section 192.10 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL...

  3. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Outer continental shelf pipelines. 192.10 Section 192.10 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL...

  4. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 false Outer continental shelf pipelines. 195.9 Section 195.9 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  5. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...2010-10-01 false Outer continental shelf pipelines. 192.10 Section 192.10 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL...

  6. Jupiter Observation Campaign: Citizen Science at the Outer Planets

    Microsoft Academic Search

    J. H. Jones; A. S. Wessen; R. Pappalardo; S. Vance; P. Dyches; K. Beisser; J. Perry

    2011-01-01

    How can NASA Outreach help the citizen scientist? NASA Solar System Education and Public Outreach (EPO) may coordinate and disseminate a consistent process for receiving Jupiter and other outer planet observation data from citizen scientists.

  7. A Closer Look of the Inner and Outer Planets

    NSDL National Science Digital Library

    Vanessa Brewster

    2012-07-27

    In this lesson, students will research properties of the inner and outer planets in our Solar System. They will organize their research by creating a Solar System poster that displays a comparison between the planets.

  8. 6. OUTER BLAST DOOR, WEST REAR. Edwards Air Force ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. OUTER BLAST DOOR, WEST REAR. - Edwards Air Force Base, South Base Sled Track, Firing & Control Blockhouse for 10,000-foot Track, South of Sled Track at midpoint of 20,000-foot track, Lancaster, Los Angeles County, CA

  9. VOL. 87, NO. 3, JUNE 2014 185 Outer Median Triangles

    E-print Network

    Curgus, Branko

    VOL. 87, NO. 3, JUNE 2014 185 Outer Median Triangles ´ARPAD B ´ENYI Western Washington University Bellingham, WA 98225 Arpad.Benyi@wwu.edu BRANKO ´CURGUS Western Washington University Bellingham, WA 98225

  10. Radioisotope Electric Propulsion for Fast Outer Planetary Orbiters

    NASA Technical Reports Server (NTRS)

    Oleson, Steven; Benson, Scott; Gefert, Leon; Patterson, Michael; Schreiber, Jeffrey

    2002-01-01

    Recent interest in outer planetary targets by the Office of Space Science has spurred the search for technology options to enable relatively quick missions to outer planetary targets. Several options are being explored including solar electric propelled stages combined with aerocapture at the target and nuclear electric propulsion. Another option uses radioisotope powered electric thrusters to reach the outer planets. Past work looked at using this technology to provide faster flybys. A better use for this technology is for outer planet orbiters. Combined with medium class launch vehicles and a new direct trajectory these small, sub-kilowatt ion thrusters and Stirling radioisotope generators were found to allow missions as fast as 5 to 12 years for objects from Saturn to Pluto, respectively. Key to the development is light spacecraft and science payload technologies.

  11. 2. DETAIL, EAST ENTRANCE, SHOWING OUTER BLAST DOOR AND INNER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL, EAST ENTRANCE, SHOWING OUTER BLAST DOOR AND INNER DOORS. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Instrumentation & Control Building, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

  12. 49 CFR 195.9 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Outer continental shelf pipelines. 195.9 Section 195.9 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF...

  13. 49 CFR 192.10 - Outer continental shelf pipelines.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 false Outer continental shelf pipelines. 192.10 Section 192.10 Transportation...Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION...DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL...

  14. Decreasing Outer Hair Cell Membrane Cholesterol Increases Cochlear Electromechanics

    NASA Astrophysics Data System (ADS)

    Brownell, William E.; Jacob, Stefan; Hakizimana, Pierre; Ulfendahl, Mats; Fridberger, Anders

    2011-11-01

    The effect of decreasing membrane cholesterol on the mechanical response of the cochlea to acoustic and/or electrical stimulation was monitored using laser interferometry. In contrast to pharmacological interventions that typically decrease cochlear electromechanics, reducing membrane cholesterol increased the response. The electromechanical response in untreated preparations was asymmetric with greater displacements in response to positive currents and cholesterol depletion increased the asymmetry. The results confirm that outer hair cell electromotility is enhanced by low membrane cholesterol. The asymmetry of the response indicates the outer hair cell resting membrane potential is hyperpolarized relative to the voltage of maximum gain for the outer hair cell voltage-displacement function. The magnitude of the response increase suggests a non-uniform distribution of cholesterol along the lateral wall of normal adult outer hair cells.

  15. 75 FR 1076 - Outer Continental Shelf Civil Penalties

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-08

    ...Management Service Outer Continental Shelf Civil Penalties AGENCY: Minerals Management...summarizing review of the maximum daily civil penalty assessment...requires the MMS to review the maximum daily civil penalty assessment for violations of...

  16. Emerging communications technologies for outer-planet exploration

    NASA Technical Reports Server (NTRS)

    Stelzried, C.; Lesh, J.

    2001-01-01

    Communication over long free space distances is extremely difficult due to the inverse squared propagation losses associated with link distance. That makes communications particularly difficult from outer planet destinations.

  17. Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions

    SciTech Connect

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F. [College of Physics and Technology, Guangxi University, Nanning, Guangxi 530004 (China); Department of Physics and Institute for Nuclear Theory, Brooklyn College of the City University of New York, Brooklyn, New York 11210 (United States); Department of Physics, College of Staten Island of the City University of New York, Staten Island, New York 10314 (United States); Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2011-09-15

    Background: Proton-proton bremsstrahlung (pp{gamma}) is investigated both theoretically and experimentally. The pp{gamma} amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the pp{gamma} cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the pp{gamma} process. Method: Four different pp{gamma} amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for pp scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the pp{gamma} cross sections. Purpose: We verify the validity of the ROBE pp{gamma} amplitudes. We explore similarities between the four-on-shell-point ROBE and two-u-two-t special (TuTts) soft-photon pp{gamma} amplitudes and important differences with the one-on-shell-point ROBE and Low pp{gamma} amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the pp{gamma} cross section. Furthermore, we identify a general principle that governs the process. This general principle is also applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI pp{gamma} cross sections. (ii) The four-on-shell-point ROBE (or TuTts) amplitude describes the TRIUMF data better than does the one-on-shell-point ROBE (or Low) amplitude. (iii) The effect on the pp{gamma} cross section of using different on-shell-point conditions is significant in the hard-photon region, i.e., for small proton scattering angles {theta} (={theta}{sub 3}={theta}{sub 4}, symmetric scattering angles) far from the elastic limit ({theta}{yields}45 deg.); in contrast, the effect becomes insignificant in the vicinity of the elastic limit. Near the limit as {theta} tends to 45 deg. (or as the photon energy K approaches zero), the four-on-shell-point and one-on-shell-point amplitudes approach one another, a general principle applicable to all bremsstrahlung processes because only kinematics is involved. Conclusion: The four-on-shell-point ROBE amplitude provides a quantitative description of pp{gamma} cross sections. The anomalous magnetic moment is an important component of the photon emission mechanism. The four-on-shell-point property of the full ROBE amplitude is essential to properly describing the complete range of the precision KVI data and the TRIUMF data, although the one-on-shell-point ROBE amplitude is adequate in the region near the elastic limit.

  18. Air cleaner shell noise analysis with plate and shell theory

    SciTech Connect

    White, J.A. Jr.

    1996-09-01

    Plate and shell theory is used to determine the force vibration response of large air cleaner surfaces for the air cleaner breathing modes of vibration. Plate equations are small and can be programmed into a hand held calculator for convenience. The eigenfunction method is used to solve the plate equation to obtain the plate vibration response. Surface reinforcements such as ribs, corrugation and surface curvature are included in the plate equation in terms of structural rigidity. Surface stiffness can be modified by simply changing the stiffener moment of inertia or by changing the number of stiffeners. The approximation technique was used to model a rectangular shallow shell. The predicted shell first natural frequency compared favorably to that of an exact solution to the shallow shell equation. Two air cleaner covers were modeled with the technique. One of the covers was flat and reinforced with ribs while the other was a shallow shell also reinforced with ribs. Forced vibration and frequency predictions of the air cleaner cover breathing mode compared well with experimental data.

  19. STAR FORMATION IN THE OUTER DISK OF SPIRAL GALAXIES

    SciTech Connect

    Barnes, Kate L.; Van Zee, Liese [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Cote, Stephanie [Canadian Gemini Office, Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria (Canada); Schade, David, E-mail: barneskl@astro.indiana.edu, E-mail: vanzee@astro.indiana.edu, E-mail: Stephanie.Cote@nrc-cnrc.gc.ca, E-mail: David.Schade@nrc-cnrc.gc.ca [Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria (Canada)

    2012-09-20

    We combine new deep and wide field of view H{alpha} imaging of a sample of eight nearby (d Almost-Equal-To 17 Mpc) spiral galaxies with new and archival H I and CO imaging to study the star formation and the star formation regulation in the outer disk. We find that, in agreement with previous studies, star formation in the outer disk has low covering fractions, and star formation is typically organized into spiral arms. The star formation in the outer disk is at extremely low levels, with typical star formation rate surface densities of {approx}10{sup -5} to 10{sup -6} M{sub Sun} yr{sup -1} kpc{sup -2}. We find that the ratio of the radial extent of detected H II regions to the radius of the H I disk is typically {approx}>85%. This implies that in order to further our understanding of the implications of extended star formation, we must further our understanding of the formation of extended H I disks. We measure the gravitational stability of the gas disk, and find that the outer gaseous disk is typically a factor of {approx}2 times more stable than the inner star-forming disk. We measure the surface density of outer disk H I arms, and find that the disk is closer to gravitational instability along these arms. Therefore, it seems that spiral arms are a necessary, but not sufficient, requirement for star formation in the outer disk. We use an estimation of the flaring of the outer gas disk to illustrate the effect of flaring on the Schmidt power-law index; we find that including flaring increases the agreement between the power-law indices of the inner and outer disks.

  20. The Ghost in the Shell Paradigm for Virtual Agents and Users in Collaborative Virtual Environments for Training

    E-print Network

    Paris-Sud XI, Université de

    / Informed virtual envi- ronments / Serious games for knowledge generation / Col- laborative Learning of the Shell as this knowledge is a crucial element for both collaboration and learning in the CVET context computing]: Human computer interaction - Col- laborative interaction Permission to make digital or hard

  1. An experimental and theoretical study of the valence shell photoelectron spectrum of tetrafluoromethane

    NASA Astrophysics Data System (ADS)

    Holland, D. M. P.; Potts, A. W.; Trofimov, A. B.; Breidbach, J.; Schirmer, J.; Feifel, R.; Richter, T.; Godehusen, K.; Martins, M.; Tutay, A.; Yalcinkaya, M.; Al-Hada, M.; Eriksson, S.; Karlsson, L.

    2005-01-01

    The complete valence shell photoelectron spectrum of tetrafluoromethane has been recorded using synchrotron radiation and the observed structure has been interpreted using ionisation energies and relative spectral intensities computed using the third-order algebraic-diagrammatic-construction (ADC(3)) scheme for the one-particle Green's function and the outer valence Green's function (OVGF) method. The ADC(3) calculations were performed using both the original variant based on the Dyson equation and the recently proposed non-Dyson scheme. The theoretical predictions for the single-hole ionic states due to outer valence shell ionisation agree satisfactorily with the experimental results. Ionisation from the inner valence 2t 2 and 3a 1 orbitals is strongly influenced by reorganisation effects and the intensity is spread amongst numerous satellites. Highly resolved spectra have been measured for the C˜2T2 and the D˜2A1 states, and the vibrational structure has been associated primarily with excitation of the ?1+(a1) mode. However, the analyses also provide evidence for excitation of the Jahn-Teller active ?2+(e) mode in the C˜2T2 state, and the ?3+(t2) mode in the D˜2A1 state. Excitation of this latter mode can be explained in terms of vibronic coupling between the C˜2T2 and the D˜2A1 states. Photoelectron angular distributions and branching ratios have been determined and demonstrate that shape resonances affect the outer valence shell photoionisation dynamics. The experimental results are compared with previous theoretical predictions but a consistent interpretation has not been obtained. The major difficulty concerns the uncertainty in the locations of valence shell transitions into the 5a 1 and the 5t 2 virtual orbitals.

  2. Comparative Proteome Analysis of Spontaneous Outer Membrane Vesicles and Purified Outer Membranes of Neisseria meningitidis

    PubMed Central

    Otto, Andreas; Becher, Dörte; Vogel, Ulrich

    2013-01-01

    Outer membrane vesicles (OMVs) of Gram-negative bacteria receive increasing attention because of various biological functions and their use as vaccines. However, the mechanisms of OMV release and selective sorting of proteins into OMVs remain unclear. Comprehensive quantitative proteome comparisons between spontaneous OMVs (SOMVs) and the outer membrane (OM) have not been conducted so far. Here, we established a protocol for metabolic labeling of neisserial proteins with 15N. SOMV and OM proteins labeled with 15N were used as an internal standard for proteomic comparison of the SOMVs and OMs of two different strains. This labeling approach, coupled with high-sensitivity mass spectrometry, allowed us to comprehensively unravel the proteome of the SOMVs and OMs. We quantified the relative distribution of 155 proteins between SOMVs and the OM. Complement regulatory proteins, autotransporters, proteins involved in iron and zinc acquisition, and a two-partner secretion system were enriched in SOMVs. The highly abundant porins PorA and PorB and proteins connecting the OM with peptidoglycan or the inner membrane, such as RmpM, MtrE, and PilQ, were depleted in SOMVs. Furthermore, the three lytic transglycosylases MltA, MltB, and Slt were less abundant in SOMVs. In conclusion, SOMVs are likely to be released from surface areas with a low local abundance of membrane-anchoring proteins and lytic transglycosylases. The enrichment of complement regulatory proteins, autotransporters, and trace metal binding and transport proteins needs to be explored in the context of the pathogenesis of meningococcal disease. PMID:23893116

  3. Imaging outer segment renewal in living human cone photoreceptors

    PubMed Central

    Jonnal, Ravi S.; Besecker, Jason R.; Derby, Jack C.; Kocaoglu, Omer P.; Cense, Barry; Gao, Weihua; Wang, Qiang; Miller, Donald T.

    2011-01-01

    In vertebrate eyes, vision begins when the photoreceptor's outer segment absorbs photons and generates a neural signal destined for the brain. The extreme optical and metabolic demands of this process of phototransduction necessitate continual renewal of the outer segment. Outer segment renewal has been long studied in post-mortem rods using autoradiography, but has been observed neither in living photoreceptors nor directly in cones. Using adaptive optics, which permits the resolution of cones, and temporally coherent illumination, which transforms the outer segment into a “biological interferometer,” we observed cone renewal in three subjects, manifesting as elongation of the cone outer segment, with rates ranging from 93 to 113 nm/hour (2.2 to 2.7 ?m/day). In one subject we observed renewal occurring over 24 hours, with small but significant changes in renewal rate over the day. We determined that this novel method is sensitive to changes in outer segment length of 139 nm, more than 20 times better than the axial resolution of ultra-high resolution optical coherence tomography, the best existing method for depth imaging of the living retina. PMID:20389538

  4. Forces involved in length changes of cochlear outer hair cells.

    PubMed

    Gitter, A H; Rudert, M; Zenner, H P

    1993-06-01

    Motion or force generation of outer hair cells may contribute to active modulation of cochlear mechanics. In order to determine the force involved in length changes of outer hair cells, a new in vitro method was used. In the first series of experiments, apical and basolateral extracellular spaces of outer hair cells of the guinea-pig cochlea were separated. Changes of the voltage between the two extracellular spaces induced reversible, proportional changes of the cell length of 4.4 nm/mV if the cell had a length of 80 microns. In the second series of experiments, cell elongations in response to negative pressure applied to the basal end of the cells were measured and corrected for frictional effects. From these data, the compliance of the longitudinal axis of the hair cells was calculated. It was 220 +/- 130 m/N (n = 25) and 240 +/- 170 m/N (n = 24) for cells of the third and fourth cochlear turns, respectively, if the water permeability of the cell membrane was neglected. If the water permeability was taken into account, the compliance was probably around 500 m/N [corrected]. Thus, a mechanism that changes the cell length by 1 microm must generate a static force of at least around 2 nN in an outer hair cell of the organ of Corti [corrected]. Electromotility of outer hair cells, induced by changes of the electrical potential difference across the outer hair cell, is a mechanism that generates this force. PMID:8351208

  5. Dissecting Escherichia coli Outer Membrane Biogenesis Using Differential Proteomics

    PubMed Central

    Martorana, Alessandra M.; Motta, Sara; Di Silvestre, Dario; Falchi, Federica; Dehò, Gianni; Mauri, Pierluigi; Sperandeo, Paola; Polissi, Alessandra

    2014-01-01

    The cell envelope of Gram-negative bacteria is a complex multi-layered structure comprising an inner cytoplasmic membrane and an additional asymmetric lipid bilayer, the outer membrane, which functions as a selective permeability barrier and is essential for viability. Lipopolysaccharide, an essential glycolipid located in the outer leaflet of the outer membrane, greatly contributes to the peculiar properties exhibited by the outer membrane. This complex molecule is transported to the cell surface by a molecular machine composed of seven essential proteins LptABCDEFG that form a transenvelope complex and function as a single device. While advances in understanding the mechanisms that govern the biogenesis of the cell envelope have been recently made, only few studies are available on how bacterial cells respond to severe envelope biogenesis defects on a global scale. Here we report the use of differential proteomics based on Multidimensional Protein Identification Technology (MudPIT) to investigate how Escherichia coli cells respond to a block of lipopolysaccharide transport to the outer membrane. We analysed the envelope proteome of a lptC conditional mutant grown under permissive and non permissive conditions and identified 123 proteins whose level is modulated upon LptC depletion. Most such proteins belong to pathways implicated in cell envelope biogenesis, peptidoglycan remodelling, cell division and protein folding. Overall these data contribute to our understanding on how E. coli cells respond to LPS transport defects to restore outer membrane functionality. PMID:24967819

  6. Covering Problems with Hard Capacities

    Microsoft Academic Search

    Julia Chuzhoy; Joseph Naor

    2002-01-01

    We consider the classical vertex cover and set cover problems with the addition of hard capacity constraints. This means that a set (vertex) can only cover a limited number of its elements (adjacent edges) and the number of available copies of each set (vertex) is bounded. This is a natural generalization of the classical problems that also captures resource limitations

  7. Hard scattering in gammap interactions

    Microsoft Academic Search

    T. Ahmed; V. Andreev; B. Andrieu; M. Arpagaus; A. Babayev; H. Bärwolff; J. Ban; P. Baranov; E. Barrelet; W. Bartel; U. Bassler; G. A. Beck; H. P. Beck; H.-J. Behrend; A. Belousov; Ch. Berger; H. Bergstein; G. Bernardi; R. Bernet; U. Berthon; G. Bertrand-Coremans; M. Besancon; P. Biddulph; E. Binder; J. C. Bizot; V. Blobel; K. Borras; P. C. Bosetti; V. Boudry; C. Bourdarios; F. Brasse; U. Braun; W. Braunschweig; V. Brisson; D. Bruncko; J. Bürger; F. W. Büsser; A. Buniatian; S. Burke; G. Buschhorn; A. J. Campbell; T. Carli; F. Charles; D. Clarke; A. B. Clegg; M. Colombo; J. A. Coughlan; A. Courau; C. Coutures; G. Cozzika; L. Criegee; J. Cvach; J. B. Dainton; M. Danilov; A. W. E. Dann; W. D. Dau; M. David; E. Deffur; B. Delcourt; L. Delbuono; M. Devel; A. Deroeck; P. Dingus; C. Dollfus; J. D. Dowell; H. B. Dreis; A. Drescher; J. Duboc; D. Düllmann; O. Dünger; H. Duhm; M. Eberle; J. Ebert; T. R. Ebert; G. Eckerlin; V. Efremenko; S. Egli; S. Eichenberger; R. Eichler; F. Eisele; E. Eisenhandler; N. N. Ellis; R. J. Ellison; E. Elsen; M. Erdmann; E. Evrard; L. Favart; A. Fedotov; D. Feeken; R. Felst; J. Feltesse; Y. Feng; I. F. Fensome; J. Ference; F. Ferrarotto; W. Flauger; M. Fleischer; G. Flügge; A. Fomenko; B. Fominykh; M. Forbush; J. Formanek; J. M. Foster; G. Franke; E. Fretwurst; P. Fuhrmann; E. Gabathuler; K. Gamerdinger; J. Garvey; J. Gayler; A. Gellrich; M. Gennis; U. Gensch; H. Genzel; R. Gerhards; D. Gillespie; L. Godfrey; U. Goerlach; L. Goerlich; M. Goldberg; A. M. Goodall; I. Gorelov; P. Goritchev; C. Grab; H. Grässler; T. Greenshaw; H. Greif; G. Grindhammer; C. Gruber; J. Haack; D. Haidt; L. Hajduk; O. Hamon; D. Handschuh; E. M. Hanlon; M. Hapke; J. Harjes; P. Hartz; R. Haydar; W. J. Haynes; J. Heatherington; V. Hedberg; R. Hedgecock; G. Heinzelmann; R. C. W. Henderson; H. Henschel; R. Herma; I. Herynek; W. Hildesheim; P. Hill; C. D. Hilton; J. Hladky; K. C. Hoeger; Ph. Huet; H. Hufnagel; N. Huot; M. Ibbotson; M. A. Jabiol; A. Jacholkowska; C. Jacobson; M. Jaffre; L. Jönsson; K. Johannsen; D. Johnson; L. Johnson; H. Jung; P. I. P. Kalmus; S. Kasarian; R. Kaschowitz; P. Kasselmann; U. Kathage; H. H. Kaufmann; I. R. Kenyon; S. Kermiche; C. Kiesling; M. Klein; C. Kleinwort; G. Knies; T. Köhler; H. Kolanoski; F. Kole; S. D. Kolya; V. Korbel; M. Korn; P. Kostka; S. K. Kotelnikov; M. W. Krasny; H. Krehbiel; D. Krücker; U. Krüger; J. P. Kubenka; H. Küster; M. Kuhlen; T. Kurca; J. Kurzhöfer; B. Kuznik; R. Lander; M. P. J. Landon; R. Langkau; P. Lanius; J. F. Laporte; A. Lebedev; U. Lenhardt; A. Leuschner; C. Leverenz; D. Levin; S. Levonian; Ch. Ley; G. Lindström; P. Loch; H. Lohmander; G. C. Lopez; D. Lüers; N. Magnussen; E. Malinovski; S. Mani; P. Marage; J. Marks; R. Marshall; J. Martens; R. Martin; H.-U. Martyn; J. Martyniak; S. Masson; A. Mavroidis; S. J. Maxfield; S. J. McMahon; A. Mehta; K. Meier; T. Merz; C. A. Meyer; H. Meyer; J. Meyer; S. Mikocki; V. Milone; E. Monnier; F. Moreau; J. Moreels; J. V. Morris; J. M. Morton; K. Müller; P. Murin; S. A. Murray; V. Nagovizin; B. Naroska; Th. Naumann; D. Newton; H. K. Nguyen; F. Niebergall; R. Nisius; G. Nowak; G. W. Noyes; M. Nyberg; H. Oberlack; U. Obrock; J. E. Olsson; S. Orenstein; F. Ould-Saada; C. Pascaud; G. D. Patel; E. Peppel; S. Peters; H. T. Phillips; J. P. Phillips; Ch. Pichler; W. Pilgram; D. Pitzl; R. Prosi; F. Raupach; K. Rauschnabel; P. Reimer; P. Ribarics; V. Riech; J. Riedlberger; M. Rietz; S. M. Robertson; P. Robmann; R. Roosen; A. Rostovtsev; C. Royon; M. Rudowicz; M. Ruffer; S. Rusakov; K. Rybicki; E. Ryseck; J. Sacton; N. Sahlmann; E. Sanchez; D. P. Sankey; M. Savitsky; P. Schacht; P. Schleper; W. von Schlippe; C. Schmidt; D. Schmidt; W. Schmitz; V. Schröder; M. Schulz; A. Schwind; W. Scobel; U. Seehausen; R. Sell; M. Seman; A. Semenov; V. Shekelyan; I. Sheviakov; H. Shooshtari; G. Siegmon; U. Siewert; Y. Sirois; I. O. Skillicorn; P. Smirnov; J. R. Smith; L. Smolik; Y. Soloviev; H. Spitzer; P. Staroba; M. Steenbock; P. Steffen; R. Steinberg; H. Steiner; B. Stella; K. Stephens; J. Strachota; U. Straumann; W. Struczinski; J. P. Sutton; R. E. Taylor; G. Thompson; R. J. Thompson; I. Tichomirov; C. Trenkel; P. Truöl; V. Tchernyshov; J. Turnau; J. Tutas; L. Urban; A. Usik; S. Valkar; A. Valkarova; C. Vallee; P. Vanesch; A. Vartapetian; J. Vasdik; M. Vecko; P. Verrecchia; R. Vick; G. Villet; E. Vogel; K. Wacker; I. W. Walker; A. Walther; G. Weber; D. Wegener; A. Wegner; H. P. Wellisch; S. Willard; M. Winde; G.-G. Winter; M. Th. Wolff; L. A. Womersley; A. E. Wright; N. Wulff; T. P. Yiou; J. Zacek; P. Zavada; C. Zeitnitz; H. Ziaeepour; M. Zimmer; W. Zimmermann; F. Zomer

    1992-01-01

    We report on the investigation of the final state in interactions of quasi-real photons with protons. The data were taken with the H1 detector at the HERA ep collider. Evidence for hard interactions is seen in both single particle spectra and jet formation. The data can best be described by inclusion of resolved photon processess as predicted by QCD.

  8. FATIGUE OF BIOMATERIALS: HARD TISSUES

    PubMed Central

    Arola, D.; Bajaj, D.; Ivancik, J.; Majd, H.; Zhang, D.

    2009-01-01

    The fatigue and fracture behavior of hard tissues are topics of considerable interest today. This special group of organic materials comprises the highly mineralized and load-bearing tissues of the human body, and includes bone, cementum, dentin and enamel. An understanding of their fatigue behavior and the influence of loading conditions and physiological factors (e.g. aging and disease) on the mechanisms of degradation are essential for achieving lifelong health. But there is much more to this topic than the immediate medical issues. There are many challenges to characterizing the fatigue behavior of hard tissues, much of which is attributed to size constraints and the complexity of their microstructure. The relative importance of the constituents on the type and distribution of defects, rate of coalescence, and their contributions to the initiation and growth of cracks, are formidable topics that have not reached maturity. Hard tissues also provide a medium for learning and a source of inspiration in the design of new microstructures for engineering materials. This article briefly reviews fatigue of hard tissues with shared emphasis on current understanding, the challenges and the unanswered questions. PMID:20563239

  9. Mineralogical characterization of pristine, bio-eroded and fossil bivalve shell material for the evaluation of a species-specific alteration potential

    NASA Astrophysics Data System (ADS)

    Hippler, Dorothee; Goetschl, Katja Elisabeth; Gerstmann, Brigitte Simone; Rafael Garcia-March, Jose; Dietzel, Martin

    2015-04-01

    Biogenic carbonates of marine calcifiers can provide a wealth of information for the reconstruction of modern and palaeo-environments. However, their composite carbonate shells are often prone to different alteration processes that might occur during their lifetime, post-mortem or during early diagenesis. In order to use these calcifiers as palaeo-archives or proxy carriers, it is thus of crucial importance to assess their alteration potential. Here, we present the mineral phase composition of four different Mediterranean bivalve species (Spondylus, Lithophaga, Arca, Glycymeris) using spatially selected, powder XRD analysis, as well as in-situ high-resolution Raman spectroscopy. The sample set thereby comprises pristine-modern, bioeroded-modern, Holocene and Pleistocene specimens of the same bivalve species in order to characterize and evaluate the species-specific susceptibility to bioerosion and diagenetic alteration. We reveal species-specific shell compositions that are validated by both analytical methods. Differences in shell mineralogy occur between the outermost (periostracum), the outer (ostracum) and inner (hypostracum) layer, with the outer layer mainly composed of calcite and the inner layers of aragonite with variable portions of calcite. Considerable species-specific changes in mineralogy of the respective shell layers with increasing geological age are not found. Our results indicate that the original shell mineralogy (calcite, aragonite and carbonate fluorapatite) as well as the composition, structure and thickness of the respective shell layers are important factors favouring or preventing alteration to occur. Moreover, our findings highlight the effect of bioerosion during the alteration process. The analysis of distinct areas of the shells hinting at microbial activity reveals slight changes in shell mineralogy. We thus postulate that processes related to shell taphonomy are crucial for the shell's alteration/preservational potential and thus subsequent for diagenesis. This is a contribution to the DFG research group CHARON.

  10. From shelled Ge nanowires to SiC nanotubes.

    PubMed

    Drínek, Vladislav; Subrt, Jan; Klementová, Mariana; Rieder, Milan; Fajgar, Radek

    2009-01-21

    Shelled germanium nanowires up to 100 nm in diameter and several micrometers in length were prepared by low pressure chemical vapor deposition (LPCVD) of tris(trimethylsilyl)germane (SiMe(3))(3)GeH. Vapors of the precursor were deposited on tantalum substrates in an oven at 365 degrees C. Subsequently, the products were annealed at 700 degrees C in vacuum. The wires consist of a crystalline Ge core surrounded by a two-layer jacket. The presence of hexagonal Ge in the core was documented in some of the nanowires. The inner jacket is formed by amorphous germanium, the outer part by an Si/C material. By annealing at 900 degrees C, germanium in the core is expelled and nanotubes formed by the Si/C material remain. The samples were studied by SEM, HRTEM, EDX, FTIR and Raman spectroscopy, and the XRD technique. PMID:19417301

  11. Control of the Helicity Content of a Gun-Generated Spheromak by Incorporating a Conducting Shell into a Magnetized Coaxial Plasma Gun

    NASA Astrophysics Data System (ADS)

    Matsumoto, Tadafumi; Sekiguchi, Jun'ichi; Asai, Tomohiko

    In the formation of magnetized plasmoid by a magnetized coaxial plasma gun (MCPG), the magnetic helicity content of the generated plasmoid is one of the critical parameters. Typically, the bias coil to generate a poloidal flux is mounted either on the outer electrode or inside the inner electrode. However, most of the flux generated in the conventional method spreads even radially outside of the formation region. Thus, only a fraction of the total magnetic flux is actually exploited for helicity generation in the plasmoid. In the proposed system, the plasma gun incorporates a copper shell mounted on the outer electrode. By changing the rise time of the discharge bias coil current and the geometrical structure of the shell, the magnetic field structure and its time evolution can be controlled. The effect of the copper shell has been numerically simulated for the actual gun structure, and experimentally confirmed. This may increase the magnetic helicity content results, through increased poloidal magnetic field.

  12. Dynamics of shear-thinning suspensions of core-shell structured latex particles.

    PubMed

    Nakamura, Hiroshi; Tachi, Kazuyuki

    2006-05-01

    The rheological behavior and microstructure of shear-thinning suspensions of core-shell structured carboxylated latex particles were examined. The steady shear viscosity of the suspension increased with increasing dissociation of the carboxyl groups or increasing particle concentration, however the critical shear stress sigma(c) and inter-particle distance xi of the microstructure did not change. With increasing particle diameter, sigma(c) increased and xi decreased. These results were consistent with a Brownian hard sphere model, in which competition exists between the bulk mass transfer due to the applied field and diffusion of the particles. We confirmed that sigma(c) depends on xi, as expressed by sigma(c) = 3kT/4pi xi3. This relationship is consistent with the dynamics of a Brownian hard sphere model with particle diameter xi. Thus the dynamics of shear-thinning suspensions of core-shell particles can be explained by a Brownian thermodynamic model. PMID:16289131

  13. Superluminous X-ray emission from the interaction of supernova ejecta with dense circumstellar shells

    NASA Astrophysics Data System (ADS)

    Pan, Tony; Patnaude, Daniel; Loeb, Abraham

    2013-07-01

    For supernova (SN) powered by the conversion of kinetic energy into radiation due to the interactions of the ejecta with a dense circumstellar shell, we show that there could be X-ray analogues of optically superluminous SNe with comparable luminosities and energetics. We consider X-ray emission from the forward shock of SN ejecta colliding into an optically thin circumstellar material (CSM) shell, derive simple expressions for the X-ray luminosity as a function of the circumstellar shell characteristics, and discuss the different regimes in which the shock will be radiative or adiabatic, and whether the emission will be dominated by free-free radiation or line cooling. We find that even with normal SN explosion energies of 1051 erg, there exist CSM shell configurations that can liberate a large fraction of the explosion energy in X-rays, producing unabsorbed X-ray luminosities approaching 1044 erg s-1 events lasting a few months, or even 1045 erg s-1 flashes lasting days. Although the large column density of the circumstellar shell can absorb most of the flux from the initial shock, the most luminous events produce hard X-rays that are less susceptible to photoelectric absorption, and can counteract such losses by completely ionizing the intervening material. Regardless, once the shock traverses the entire circumstellar shell, the full luminosity could be available to observers.

  14. Assessing the utility of elemental ratios as a paleotemperature proxy in shells of patelloid limpets

    NASA Astrophysics Data System (ADS)

    Graniero, Lauren; Surge, Donna; Gillikin, David

    2015-04-01

    Archaeological shell and fish middens are rich sources of paleoenvironmental proxy data. Carbonate hard part remains contained in such deposits have been used as archives of coastal marine climate and human-climate interactions. Oxygen isotope records from fast-growing limpet shells potentially capture summer and winter seasons, and thus, approach the full seasonal range of sea surface temperature (SST). Fast-growing shells are often short-lived, providing "snap-shots" of multi-year seasonal cycles. Patelloid limpet shells are common constituents in archaeological middens found along European, African, and South American coastlines. Oxygen isotope ratios of archaeological limpet shells from the genus, Patella, have been used to reconstruct seasonal SST and ocean circulation patterns during the Late Quaternary. Such studies depend on the ability to constrain the oxygen isotope ratio of seawater; therefore, alternative proxies are necessary for coastal localities where this is not possible. Elemental ratios (e.g., Sr/Ca, Mg/Ca) have been used as paleotemperature proxies in corals and foraminifera with varying degrees of success and appear problematic in bivalves. Here, we test whether such elemental ratios are useful as an alternative SST proxy in patelloid limpet shells.

  15. Dual shell pressure balanced vessel

    DOEpatents

    Fassbender, Alexander G. (West Richland, WA)

    1992-01-01

    A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

  16. Plastic buckling of cylindrical shells

    SciTech Connect

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Eckert, H. [USDOE, Germantown, MD (United States)

    1994-05-01

    Cylindrical shells exhibit buckling under axial loads at stresses much less than the respective theoretical critical stresses. This is due primarily to the presence of geometrical imperfections even through such imperfections could be very small (e.g., comparable to thickness). Under internal pressure, the shell regains some of its buckling strength. For a relatively large radius-to-tickness ratio and low internal pressure, the effect can be reasonably estimated by an elastic analysis. However, for low radius-to-thickness ratios and greater pressures, the elastic-plastic collapse controls the failure load. In order to quantify the elastic-plastic buckling capacity of cylindrical shells, an analysis program was carried out by use of the computer code BOSOR5 developed by Bushnell of Lockheed Missiles and Space company. The analysis was performed for various radius-to- thickness ratios and imperfection amplitudes. The analysis results are presented in this paper.

  17. Radio emission from nova shells

    NASA Technical Reports Server (NTRS)

    Hjellming, R. M.; Wade, C. M.; Vandenberg, N. R.; Newell, R. T.

    1979-01-01

    This paper presents data from multifrequency radio observations of the novae HR Del 1967 and FH Ser 1970 made from June 1970 to December 1978 and of V1500 Cyg 1975 made from September 1975 to December 1978. The data for FH Ser and V1500 Cyg constitute a complete history of the important phases of their radio 'light' curves, while all but the rising portion of the optically thick phase of an expanding nova shell is present for HR Del. A simple solution of the spherically symmetric equations of mass and momentum conservation for an isothermal gas, for which pressure gradients are effectively decoupled from the dynamics, is shown to fit the radio data for all three novae quite well. The main features of this model are strong density and velocity gradients that lead to long periods when the 'observable' shell evolves from an optically thick 'disk' to a completely optically thin shell.

  18. Tyrosinase localization in mollusc shells.

    PubMed

    Nagai, Kouhei; Yano, Masato; Morimoto, Koichi; Miyamoto, Hiroshi

    2007-02-01

    In molluscan shellfish, pigmentation is frequently observed in the calcified shell, but the molecular basis of this process is not understood. Here, we report two tyrosinase proteins (Pfty1 and Pfty2) found in the prismatic shell layer of the pearl oyster Pinctada fucata; this layer is recognized as the pigmented region in P. fucata. The protein sequences were deduced from the corresponding cDNAs and confirmed by MALDI-TOF/TOF analysis. The sequences suggest that both tyrosinases have two copper-binding sites in similar N-terminal domains that are homologous to tyrosinases of cephalopods and hemocyanins of gastropods. In turn, this suggests that bivalve tyrosinases are evolved from a common ancestral copper-binding protein in the mollusc. Pfty1 and Pfty2 were specifically expressed in the mantle, and their expression in the mantle is different from each other, suggesting that these tyrosinases have distinctive roles in melanogenesis in shells. PMID:17150393

  19. Shell model Monte Carlo methods

    SciTech Connect

    Koonin, S.E. [California Inst. of Tech., Pasadena, CA (United States). W.K. Kellogg Radiation Lab.; Dean, D.J. [Oak Ridge National Lab., TN (United States)

    1996-10-01

    We review quantum Monte Carlo methods for dealing with large shell model problems. These methods reduce the imaginary-time many-body evolution operator to a coherent superposition of one-body evolutions in fluctuating one-body fields; resultant path integral is evaluated stochastically. We first discuss the motivation, formalism, and implementation of such Shell Model Monte Carlo methods. There then follows a sampler of results and insights obtained from a number of applications. These include the ground state and thermal properties of pf-shell nuclei, thermal behavior of {gamma}-soft nuclei, and calculation of double beta-decay matrix elements. Finally, prospects for further progress in such calculations are discussed. 87 refs.

  20. Dusty shells surrounding the carbon variables S Scuti and RT Capricorni

    NASA Astrophysics Data System (ADS)

    Me?ina, M.; Kerschbaum, F.; Groenewegen, M. A. T.; Ottensamer, R.; Blommaert, J. A. D. L.; Mayer, A.; Decin, L.; Luntzer, A.; Vandenbussche, B.; Posch, Th.; Waelkens, C.

    2014-06-01

    For the Mass-loss of Evolved StarS (MESS) programme, the unprecedented spatial resolution of the PACS photometer on board the Herschel Space Observatory was employed to map the dusty environments of asymptotic giant branch (AGB) and red supergiant (RSG) stars. Among the morphologically heterogeneous sample, a small fraction of targets is enclosed by spherically symmetric detached envelopes. Based on observations in the 70 ?m and 160 ?m wavelength bands, we investigated the surroundings of the two carbon semiregular variables S Sct and RT Cap, which both show evidence for a history of highly variable mass-loss. S Sct exhibits a bright, spherically symmetric detached shell, 138? in diameter and co-spatial with an already known CO structure. Moreover, weak emission is detected at the outskirts, where the morphology seems indicative of a mild shaping by interaction of the wind with the interstellar medium, which is also supported by the stellar space motion. Two shells are found around RT Cap that were not known so far in either dust emission or from molecular line observations. The inner shell with a diameter of 188? shows an almost immaculate spherical symmetry, while the outer ~5' structure is more irregularly shaped. MoD, a modification of the DUSTY radiative transfer code, was used to model the detached shells. Dust temperatures, shell dust masses, and mass-loss rates are derived for both targets. Appendices are available in electronic form at http://www.aanda.org

  1. Optical properties of type-I PbSe/CdSe core/shell quantum dot

    NASA Astrophysics Data System (ADS)

    Saravanamoorthy, S. N.; John Peter, A.; Lee, Chang Woo

    2015-06-01

    Electronic properties and optical properties of exciton in a PbSe/CdSe core/shell quantum dot are investigated taking into account the spatial confinement effect. The present model is based on the PbSe/CdSe quantum dot for type-I confinement regime. The dielectric mismatch effect and the self polarization potential are taken into consideration in the PbSe/CdSe quantum dot nanostructure. Polarization charges are incorporated at the interface of the core/shell materials. Numerical calculations on the electronic and optical properties are found with the ratio of radius of inner and outer shell materials for various shell radii. The exciton binding energy and the interband optical transition energies are computed using variational formulism within the single band effective mass approximation. The oscillator strength and the recombination life time are determined with the ratio of radius of core to shell materials taking into account the dielectric mismatch between the materials. The nonlinear absorption coefficients and the changes of refractive index are computed for the ground and first excited state using compact density matrix method. The obtained results are found to be in good agreement with those reported by other investigators.

  2. Localization of phosphatidylcholine in outer envelope membrane of spinach chloroplasts

    PubMed Central

    1985-01-01

    We have examined the effects of phospholipase C from Bacillus cereus on the extent of phospholipid hydrolysis in envelope membrane vesicles and in intact chloroplasts. When isolated envelope vesicles were incubated in presence of phospholipase C, phosphatidylcholine and phosphatidylglycerol, but not phosphatidylinositol, were totally converted into diacylglycerol if they were available to the enzyme (i.e., when the vesicles were sonicated in presence of phospholipase C). These experiments demonstrate that phospholipase C can be used to probe the availability of phosphatidylcholine and phosphatidylglycerol in the cytosolic leaflet of the outer envelope membrane from spinach chloroplasts. When isolated, purified, intact chloroplasts were incubated with low amounts of phospholipase C (0.3 U/mg chlorophyll) under very mild conditions (12 degrees C for 1 min), greater than 80% of phosphatidylcholine molecules and almost none of phosphatidylglycerol molecules were hydrolyzed. Since we have also demonstrated, by using several different methods (phase-contrast and electron microscopy, immunochemical and electrophoretic analyses) that isolated spinach chloroplasts, and especially their outer envelope membrane, remained intact after mild treatment with phospholipase C, we can conclude that there is a marked asymmetric distribution of phospholipids across the outer envelope membrane of spinach chloroplasts. Phosphatidylcholine, the major polar lipid of the outer envelope membrane, is almost entirely accessible from the cytosolic side of the membrane and therefore is probably localized in the outer leaflet of the outer envelope bilayer. On the contrary, phosphatidylglycerol, the major polar lipid in the inner envelope membrane and the thylakoids, is probably not accessible to phospholipase C from the cytosol and therefore is probably localized mostly in the inner leaflet of the outer envelope membrane and in the other chloroplast membranes. PMID:3988805

  3. Charged Shells and Elementary Particles

    NASA Astrophysics Data System (ADS)

    Casadio, Roberto

    2013-07-01

    We review the General Relativistic model of a (quasi-)pointlike particle represented by a massive shell of electrically charged matter, which displays an ADM mass M equal to the electric charge |Q| in the small-volume limit. We employ the Israel-Darboux's junction equations to explicitly derive this result, and then study the modifications introduced by the existence of a minimum length scale ?. For ? of the order of the Planck length (or larger), we find that the ADM mass becomes equal to the bare mass m0 of the shell, like it occurs for the neutral case.

  4. Shelling in low dimensional manifolds

    E-print Network

    Murray, William Owen

    1974-01-01

    -manifolds. These results will include some extensions of a theorem by Treybig which states that every compact 3-manifold has a triangulation in which every 3-cell, which is the union of 3-simplexes of the tri- angulation, can be shelled, Also, a... triangulation of E will be con- 3 structed which has the property that certain 3-cells, which are the union of 3-simplexes of the triangulation, can be shelled. iv ACKNOWLEDGMENTS I would like to express my gratitude to the chairman of my committee, Dr. L...

  5. Shell may expand detergent alcohols

    SciTech Connect

    NONE

    1996-10-23

    Shell Chemical is studying plans to expand detergent alcohols capacity in the US, CW has learned. The company is considering adding capacity for about 80 million lbs/year. If the project is approved, it would be implemented at the company`s Geismar, LA site. Shell will make a final decision on whether to proceed with the project within six months. It has been rumored to be considering a capacity addition as a result of tightening supply of natural and synthetic detergent alcohols.

  6. Glass shell manufacturing in space

    NASA Technical Reports Server (NTRS)

    Nolen, R. L., Jr.; Ebner, M. A.; Downs, R. L.

    1980-01-01

    A heat transfer model was developed that mathematically describes the heating and calculates the thermal history of a gel particle in free-fall through the furnace. The model parameters that greatly affect the calculations were found to be gel particle mass, geometry, specific heat, and furnace gas. Empirical testing of the model has commenced. The code calculations and the initial empirical testing results both indicate that the gel-to-shell transformation occurs early and rapidly in the thermal history of the gel particle, and that for current work the heat transfer rate is not a limitation in shell production.

  7. Spectral and temporal fidelity of a hard x-ray weapons effects simulation test in a high-gain ICF (inertial confinement fusion) facility. Master's thesis

    Microsoft Academic Search

    1989-01-01

    The MORSE-CG Monte Carlo code was used to simulate the effects of hard X rays from a nuclear weapon. Facility will be an inertial confinement fusion facility for the testing of high-gain deuterium-tritium (DT) pellets, and will produce a pulse of hard X rays and neutrons over a very short time interval. A spherical shell for ⁶LiH with a thickness

  8. Tuning structure and mobility of solvation shells surrounding tracer additives

    E-print Network

    James Carmer; Avni Jain; Jonathan A. Bollinger; Frank van Swol; Thomas M. Truskett

    2015-02-05

    Molecular dynamics simulations and a stochastic Fokker-Planck equation based approach are used to illuminate how position-dependent solvent mobility near one or more tracer particle(s) is affected when tracer-solvent interactions are rationally modified to affect corresponding solvation structure. For tracers in a dense hard-sphere fluid, we compare two types of tracer-solvent interactions: (1) a hard-sphere-like interaction; and (2) a soft repulsion extending beyond the hard core designed via statistical mechanical theory to enhance tracer mobility at infinite dilution by suppressing coordination-shell structure (Carmer et al., Soft Matter 8 (2011)). For the latter case, we show that the mobility of surrounding solvent particles is also increased by addition of the soft repulsive interaction, which helps to rationalize the mechanism underlying the tracer's enhanced diffusivity. However, if multiple tracer surfaces are in closer proximity (as at higher tracer concentrations), similar interactions that disrupt local solvation structure instead suppress the position-dependent solvent dynamics.

  9. Investigation of Li\\/Ca variations in aragonitic shells of the ocean quahog Arctica islandica, northeast Iceland

    Microsoft Academic Search

    Julien Thébault; Bernd R. Schöne; Nadine Hallmann; Matthias Barth; Elizabeth V. Nunn

    2009-01-01

    Interannual and intra-annual variations in lithium-to-calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li\\/Cashell ranged between 7.00 and 11.12 ?mol mol?1 and presented well-marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive

  10. FOOD FISH FACTS (Paralithodes camtschatica)

    E-print Network

    equipped with pincers. The hard shell, or exoskeleton, limits the size of the crab and, in order to grow, it periodically sheds the hard outer covering after forming a new, soft exoskeleton. This process is called molt

  11. Agents that increase the permeability of the outer membrane.

    PubMed Central

    Vaara, M

    1992-01-01

    The outer membrane of gram-negative bacteria provides the cell with an effective permeability barrier against external noxious agents, including antibiotics, but is itself a target for antibacterial agents such as polycations and chelators. Both groups of agents weaken the molecular interactions of the lipopolysaccharide constituent of the outer membrane. Various polycations are able, at least under certain conditions, to bind to the anionic sites of lipopolysaccharide. Many of these disorganize and cross the outer membrane and render it permeable to drugs which permeate the intact membrane very poorly. These polycations include polymyxins and their derivatives, protamine, polymers of basic amino acids, compound 48/80, insect cecropins, reptilian magainins, various cationic leukocyte peptides (defensins, bactenecins, bactericidal/permeability-increasing protein, and others), aminoglycosides, and many more. However, the cationic character is not the sole determinant required for the permeabilizing activity, and therefore some of the agents are much more effective permeabilizers than others. They are useful tools in studies in which the poor permeability of the outer membrane poses problems. Some of them undoubtedly have a role as natural antibiotic substances, and they or their derivatives might have some potential as pharmaceutical agents in antibacterial therapy as well. Also, chelators (such as EDTA, nitrilotriacetic acid, and sodium hexametaphosphate), which disintegrate the outer membrane by removing Mg2+ and Ca2+, are effective and valuable permeabilizers. PMID:1406489

  12. An efficient depyrogenation method for recombinant bacterial outer membrane lipoproteins.

    PubMed

    Basto, Afonso P; Morais, Joana; Marcelino, Eduardo; Leitão, Alexandre; Santos, Dulce M

    2014-06-01

    Bacterial outer membrane lipoproteins are anchored in the outer membrane lipid layer in close association with lipopolysaccharides (LPS) and with other hydrophobic membrane proteins, making their purification technically challenging. We have previously shown that a thorough delipidation of outer membrane preparations from the Escherichia coli expression host is an important step to eliminate contaminant proteins when purifying recombinant antigens expressed in fusion with the Pseudomonas aeruginosa OprI lipoprotein. Here we report the cloning and expression of three antigens in fusion with OprI (ovalbumin, eGFP and BbPDI) and our efforts to deal with the variable LPS contamination levels observed in different batches of purified lipoproteins. The use of polymyxin B columns or endotoxin removal polycationic magnetic beads for depyrogenation of purified lipoproteins resulted in high protein losses and the use of Triton X-114 or sodium deoxycholate during the course of affinity chromatography showed to be ineffective to reduce LPS contamination. Instead, performing a hot phenol/water LPS extraction from outer membrane preparations prior to metal affinity chromatography allowed the purification of the recombinant fusion lipoproteins with LPS contents below 0.02EU/?g of protein. The purified recombinant lipoproteins retain their capacity to stimulate bone marrow-derived dendritic cells allowing for the study of their immunomodulatory properties through TLR2/1. This is a simple and easy to scale up method that can also be considered for the purification of other outer membrane lipoproteins. PMID:24631926

  13. Why Are Drugs So Hard to Quit?

    MedlinePLUS Videos and Cool Tools

    Video: Why Are Drugs So Hard to Quit? Your browser does not support inline frames or is currently configured not to display inline ... link under the video: In English: Why Are Drugs So Hard to Quit? En español: ¿Por Qué ...

  14. Impact of aging on radiation hardness

    SciTech Connect

    Shaneyfelt, M.R.; Winokur, P.S.; Fleetwood, D.M. [and others

    1997-07-01

    Burn-in effects are used to demonstrate the potential impact of thermally activated aging effects on functional and parametric radiation hardness. These results have implications on hardness assurance testing. Techniques for characterizing aging effects are proposed.

  15. Nanoindentations on conch shells of Gastropoda and Bivalvia molluscs reveal anisotropic evolution against external attacks.

    PubMed

    Bignardi, Cristina; Petraroli, Michele; Pugno, Nicola M

    2010-10-01

    Nanoindentation method has been used to explore, at the nanoscale, the mechanical properties of four different representative types of conch shells belonging to the two biggest classes of molluscs, Gastropoda and Bivalvia, in order to compare nanohardness and Young's modulus with respect to the microstructural anisotropic architectures. For the experimental tests a Nano Indenter XP (MTS Nano Instruments, Oak Ridge TN) has been used. The mechanical tests have been carried out on the inner and outer surfaces of the shells, as well as on their cross-section, near to the inner/outer surfaces and in the middle layer. The results confirm the three layered anisotropic architecture of the investigated conchs. On each of these 5 surfaces, 2 x 5 indentations have been performed at different maximum depth: from 250 nm to 4 microm, with a step of 250 nm, for a total of 3200 tests. The numerous observations have been analysed applying an ad hoc modification of the Weibull Statistics, suggesting a natural evolution of the shells against external attacks. PMID:21137746

  16. Atomic model of CPV reveals the mechanism used by this single-shelled virus to economically carry out functions conserved in multi-shelled reoviruses

    PubMed Central

    Yu, Xuekui; Ge, Peng; Jiang, Jiansen; Atanasov, Ivo; Zhou, Z. Hong

    2012-01-01

    Summary Unlike the multi-shelled viruses in the Reoviridae, cytoplasmic polyhedrosis virus (CPV) is single shelled, yet stable and fully capable of carrying out functions conserved within Reoviridae. Here, we report a 3.1-Å resolution cryo electron microscopy structure of CPV and derive its atomic model, consisting of 60 turret proteins (TP), 120 each of capsid shell proteins (CSP) and large protrusion proteins (LPP). Two unique segments of CSP contribute to CPV’s stability: an inserted protrusion domain interacting with neighboring proteins and an N-terminal anchor tying up CSPs together through strong interactions such as ?-sheet augmentation. Without the need to interact with outer shell proteins, LPP retains only the N-terminal two-third region containing a conserved helix-barrel core and interacts exclusively with CSP. TP is also simplified, containing only domains involved in RNA capping. Our results illustrate how CPV proteins have evolved in a coordinative manner to economically carry out their conserved functions. PMID:21565700

  17. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, M.S.; Schuster, G.J.; Skorpik, J.R.

    1997-07-08

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part. 12 figs.

  18. Hard Photodisintegration of 3He

    NASA Astrophysics Data System (ADS)

    Granados, Carlos

    2011-02-01

    Large angle photodisintegration of two nucleons from the 3He nucleus is studied within the framework of the hard rescattering model (HRM). In the HRM the incoming photon is absorbed by one nucleon's valence quark that then undergoes a hard rescattering reaction with a valence quark from the second nucleon producing two nucleons emerging at large transverse momentum . Parameter free cross sections for pp and pn break up channels are calculated through the input of experimental cross sections on pp and pn elastic scattering. The calculated cross section for pp breakup and its predicted energy dependency are in good agreement with recent experimental data. Predictions on spectator momentum distributions and helicity transfer are also presented.

  19. Ultrasonic material hardness depth measurement

    DOEpatents

    Good, Morris S. (Richland, WA); Schuster, George J. (Kennewick, WA); Skorpik, James R. (Kennewick, WA)

    1997-01-01

    The invention is an ultrasonic surface hardness depth measurement apparatus and method permitting rapid determination of hardness depth of shafts, rods, tubes and other cylindrical parts. The apparatus of the invention has a part handler, sensor, ultrasonic electronics component, computer, computer instruction sets, and may include a display screen. The part handler has a vessel filled with a couplant, and a part rotator for rotating a cylindrical metal part with respect to the sensor. The part handler further has a surface follower upon which the sensor is mounted, thereby maintaining a constant distance between the sensor and the exterior surface of the cylindrical metal part. The sensor is mounted so that a front surface of the sensor is within the vessel with couplant between the front surface of the sensor and the part.

  20. Past and future of grid shell structures

    E-print Network

    Paoli, Céline (Céline Aude)

    2007-01-01

    Because of their original organic shape and the column free space that they provide, the design of grid shell structures challenges architects and structural engineers in more than one way. Very few grid shell building ...

  1. Hard Determinism and the Moral "Ought"

    E-print Network

    Kuo, Lenore

    HARD DETERMINISM AND THE MORAL 'OUGHT' LENORE KUO The University of Nebraska at Omaha Philosophers from Aristotle to vanlnwagen 1 have questioned the possibility of preserving ethics if hard determinism is true. Thus it has been argued that we... must reject hard determinism because of the apparent "violence" it does to our basic conception of morality. For example, Howard Hintz maintains that: [Hard determinism) destroys the foundations of all prescriptive ethics except on the arbitrary...

  2. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...12 2012-10-01 2012-10-01 false Shell-height standard. 648.50 Section 648...the Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for...

  3. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...12 2014-10-01 2014-10-01 false Shell-height standard. 648.50 Section 648...the Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for...

  4. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...12 2013-10-01 2013-10-01 false Shell-height standard. 648.50 Section 648...the Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for...

  5. 50 CFR 648.50 - Shell-height standard.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...10 2011-10-01 2011-10-01 false Shell-height standard. 648.50 Section 648...the Atlantic Sea Scallop Fishery § 648.50 Shell-height standard. (a) Minimum shell height. The minimum shell height for...

  6. Lead behavior in abalone shell

    Microsoft Academic Search

    Yoshimitsu Hirao; Akikazu Matsumoto; Hiroshi Yamakawa; Masaru Maeda; Kan Kimura

    1994-01-01

    In order to gain information about the behavior of heavy metals in biological assimilation processes in a marine food chain and to investigate the possibility that lead pollution in a marine environment can be estimated by measurement of a small number of key materials from such a food chain, muscle and shell were analyzed from abalone ( Haliotis ) from

  7. Artificially soft and hard surfaces in electromagnetics

    Microsoft Academic Search

    Per-Simon Kildal

    1990-01-01

    A transversely corrugated surface as used in corrugated horn antennas represents a soft boundary. A hard boundary is made by using longitudinal corrugations filled with dielectric material. The concept of soft and hard surfaces is treated in detail, considering different geometries. It is shown that both the hard and soft boundaries have the advantage of a polarization-independent reflection coefficient for

  8. PROTEIN COMPOSITION AND GRAIN HARDNESS IN SORGHUM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain hardness is an important quality trait in sorghum. Grain hardness has been linked to milling and food quality as well as resistance to insects and mold. Despite the importance of grain hardness in sorghum, its biochemical basis is still not well understood. In sorghum, the grain is composed...

  9. Decreased ventilatory function in hard metal workers

    Microsoft Academic Search

    Y Kusaka; M Iki; S Kumagai; S Goto

    1996-01-01

    OBJECTIVES: To study individual effects on pulmonary function of exposure to hard metal including cobalt. METHODS: All of the workers in a hard metal company (583 men and 120 women) were examined for smoking, respiratory symptoms, ventilatory function, occupational history of exposure to hard metal, and present exposure to airborne cobalt. The ventilatory function indices (forced vital capacity (FVC), forced

  10. Surface Integrity Generated by Precision Hard Turning

    Microsoft Academic Search

    Y. Matsumoto; F. Hashimoto; G. Lahoti

    1999-01-01

    Rolling contact fatigue tests were conducted to find the effect of precision hard turning. The tests showed that hard turning provides as good a fatigue performance as grinding. Hard turning produces compressive residual stresses in a deep subsurface, which contribute to a long fatigue life. The effect of cutting parameters on residual stress was investigated in order to find why

  11. Department of Mechanical Engineering Spring 2011 Shell 2-Shell Eco-Marathon

    E-print Network

    Demirel, Melik C.

    PENNSTATE Department of Mechanical Engineering Spring 2011 Shell 2- Shell Eco-Marathon Overview functioned as intended The vehicle competed in the Shell Eco-marathon in Houston Texas 153 Mpg was achieved The project saw an increase in the official fuel economy at the Shell Eco-marathon from 142 to 153 mpg. #12;

  12. Knitted outer gloves in primary hip and knee arthroplasty.

    PubMed

    Tanner, J; Wraighte, P; Howard, P

    2006-01-01

    A randomised trial was carried out to determine the rate of perforation to inner gloves when comparing latex with knitted gloves during hip and knee arthroplasty. Members of the surgical team were randomised to wear either two pairs of latex gloves (standard double gloving) or a knitted glove on top of a latex glove. In addition, participants completed a visual analogue assessment of their overall satisfaction with the gloves. A total of 406 inner gloves were tested for perforations over a four-month period: 23% of inner gloves were perforated when latex outer gloves were used and 6% of inner gloves were perforated when knitted outer gloves were used. In total, there were 64 perforations to the inner gloves; only one of these perforations was detected by the glove wearer. Wearing knitted outer gloves during hip and knee arthroplasty statistically significantly reduces the risk of perforation to inner latex gloves (p<0.0001). PMID:19219780

  13. The outer filament of Centaurus A as seen by MUSE

    E-print Network

    Santoro, F; Morganti, R; Oosterloo, T A; Tremblay, G

    2015-01-01

    We investigate signatures of a jet-interstellar medium (ISM) interaction using optical integral-field observations of the so-called outer filament near Centaurus A, expanding on previous results obtained on a more limited area. Using the Multi Unit Spectroscopic Explorer (MUSE) on the VLT during science verification, we observed a significant fraction of the brighter emitting gas across the outer filament. The ionized gas shows complex morphology with compact blobs, arc-like structures and diffuse emission. Based on the kinematics, we identified three main components. The more collimated component is oriented along the direction of the radio jet. The other two components exhibit diffuse morphology together with arc-like structures also oriented along the radio jet direction. Furthermore, the ionization level of the gas is found to decrease from the more collimated component to the more diffuse components. The morphology and velocities of the more collimated component confirm our earlier results that the outer...

  14. Developments in Cylindrical Shell Stability Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Starnes, James H., Jr.

    1998-01-01

    Today high-performance computing systems and new analytical and numerical techniques enable engineers to explore the use of advanced materials for shell design. This paper reviews some of the historical developments of shell buckling analysis and design. The paper concludes by identifying key research directions for reliable and robust methods development in shell stability analysis and design.

  15. Thin-shell wormholes in dilaton gravity

    E-print Network

    Ernesto F. Eiroa; Claudio Simeone

    2005-06-02

    In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analysed.

  16. Shell Formation and Bone Strength Laying Hens

    E-print Network

    , Daidzein and Exogenous Estrogen Abstract In Sweden almost 3.8% of all eggs are ruined due to cracked was detected. An imbalance between estrogen receptor alpha (ER) and estrogen receptor beta (ER) in the shell and overview of egg formation 10 1.2.2 Calcium sources for shell formation 13 1.2.3 Shell gland and the process

  17. ON SENSITIVE SHELL UNDER DIFFERENT LOADINGS

    Microsoft Academic Search

    Ville Havu; Harri Hakula

    We consider the problem of a sensitive eliptic shell focusing into the membrane limit problem with zero thickness. As shown in earlier works, shells of this type can have a very small set of allowed loadings not even containing the set of test functions. Using Fourier techniques on an elliptic shell of revolution we can give an indirect classication of

  18. Thin-shell wormholes in dilaton gravity

    SciTech Connect

    Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio, C.C. 67, Suc. 28, 1428, Buenos Aires (Argentina); Simeone, Claudio [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pab. I, 1428, Buenos Aires (Argentina)

    2005-06-15

    In this work we construct charged thin-shell Lorentzian wormholes in dilaton gravity. The exotic matter required for the construction is localized in the shell and the energy conditions are satisfied outside the shell. The total amount of exotic matter is calculated and its dependence with the parameters of the model is analyzed.

  19. Are Hadrons Shell-Structured? Paolo Palazzi

    E-print Network

    Are Hadrons Shell-Structured? Paolo Palazzi particlez.org, PO Box 62, CH-1217 Meyrin 1, Switzerland pp@particlez.org Abstract. A stability analysis of the mass spectrum indicates that hadrons, like with a lower density, and only start at shell 3 with the nucleon. Keywords: hadron, shell model; mass

  20. MOVEMENTS OF SMALL SOFT-SHELL CLAMS

    E-print Network

    MOVEMENTS OF SMALL SOFT-SHELL CLAMS Marine Biological Labootory X, I B R A K Y JUL 21 l'db5 WOODS MOVEMENTS OF SMALL SOFT-SHELL CLAMS (MX^ MANARJAJ By Osgood R . Smith Fishery Research Biologist Special clams, (MYA ARENARIA) The fact that small soft -shell clams can come up out of the soil, can move

  1. Generation of a genetically encoded marker of rod photoreceptor outer segment growth and renewal

    E-print Network

    Generation of a genetically encoded marker of rod photoreceptor outer segment growth and renewal are still largely unknown. Unlike typical cilia, the outer segment is continuously regenerated or renewed outer segment growth. The process of outer segment renewal was discovered over forty years ago, but we

  2. Process for overcoming drug retention in hard gelatin inhalation capsules.

    PubMed

    Saim, Said; Horhota, Stephen T

    2002-07-01

    The quantity and consistency of drug delivery from dry powder inhalation devices that incorporate a pre-measured dose in a hard shell capsule of gelatin or other compatible material can be negatively affected by mold release lubricants used in capsule manufacturing. This paper describes a novel process employing supercritical CO2 for selective extraction of the fraction of lubricant responsible for the observed high and inconsistent drug retention in capsules and the ensuing lack of reproducibility of drug delivery. The process allows for lubricant removal from seemingly inaccessible interior surfaces of assembled capsule shells without altering the structural or chemical properties of the capsules. Diffusion limitations are overcome through repeated pressure increase and decrease to generate significant convective flow of dissolved lubricant out of the capsule. Drug retention is alleviated only if nearly all the retentive fraction of the lubricant is removed. The effect of extraction with supercritical CO2 on the structure of the internal surfaces of the capsules is investigated using scanning electron microscopy. Key performance parameters such as drug and carrier retention and fine particle mass are investigated using simulated inhalation tests. Laboratory and pilot scale extractions yielded similar results. PMID:12149956

  3. Outer synchronization of coupled discrete-time networks.

    PubMed

    Li, Changpin; Xu, Congxiang; Sun, Weigang; Xu, Jian; Kurths, Jürgen

    2009-03-01

    In this paper, synchronization between two discrete-time networks, called "outer synchronization" for brevity, is theoretically and numerically studied. First, a sufficient criterion for this outer synchronization between two coupled discrete-time networks which have the same connection topologies is derived analytically. Numerical examples are also given and they are in line with the theoretical analysis. Additionally, numerical investigations of two coupled networks which have different connection topologies are analyzed as well. The involved numerical results show that these coupled networks with different connection matrices can reach synchronization. PMID:19334970

  4. BIOCHEMISTRY: Getting Into and Through the Outer Membrane

    NSDL National Science Digital Library

    Jan Tommassen (Utrecht University; Department of Molecular Microbiology and the Institute of Biomembranes)

    2007-08-17

    Access to the article is free, however registration and sign-in are required. The structures of two related bacterial membrane proteins help to understand protein transport processes in the outer membranes of bacteria, mitochondria, and chloroplasts. Omp85, an evolutionary conserved protein, is the central component of the machine required for folding and inserting outer membrane proteins (OMPs). Moreover, some OMPs with sequence similarity to Omp85 are involved in transport processes such as protein secretion in bacteria and protein import into chloroplasts. In this issue, Kim et al. and Clantin et al. provide insights into the structures of members of this protein superfamily.

  5. Outer-layer manipulators for turbulent drag reduction

    NASA Technical Reports Server (NTRS)

    Anders, J. B., Jr.

    1990-01-01

    The last ten years have yielded intriguing research results on aerodynamic boundary outer-layer manipulators as local skin friction reduction devices at low Reynolds numbers; net drag reduction device systems for entire aerodynamic configurations are nevertheless noted to remain elusive. Evidence has emerged for dramatic alterations of the structure of a turbulent boundary layer which persist for long distances downstream and reduce wall shear as a results of any one of several theoretically possible mechanisms. Reduced effectiveness at high Reynolds numbers may, however, limit the applicability of outer-layer manipulators to practical aircraft drag reduction.

  6. Virial coefficients and equations of state for mixtures of hard discs, hard spheres and hard hyperspheres

    NASA Astrophysics Data System (ADS)

    Santos, A.; Yuste, S. B.; López de Haro, M.

    The composition-independent virial coefficients of a d-dimensional binary mixture of (additive) hard hyperspheres following from a recent proposal for the equation of state of the mixture (SANTOS, A., YUSTE, S. B., and LÓPEZ DE HARO, M., 1999, Molec. Phys., 96 , 1) are examined. Good agreement between theoretical estimates and available exact or numerical results is found for d = 2, 3, 4 and 5, except for mixtures whose components are very disparate in size. A slight modification that remedies this deficiency is introduced and the resummation of the associated virial series is carried out, leading to a new proposal for the equation of state. The case of binary hard sphere mixtures (d = 3) is analysed in some detail.

  7. Multi-scale convection in a geodynamo simulation with uniform heat flux along the outer boundary

    NASA Astrophysics Data System (ADS)

    King, E. M.; Matsui, H.; Buffett, B. A.

    2013-12-01

    Conducting fluids stirring within the Earth and other planets generate magnetic fields through a process known as dynamo action. Numerical simulations of dynamo action provide insight into this process, yet cannot replicate the extreme conditions of planetary turbulence, and so important physics may not be adequately captured. For example, it is generally expected that Earth's magnetic field, which is generated by convecting liquid metal within its core, will produce strong Lorentz forces that substantially alter that convection. In most dynamo models, however, Lorentz forces do very little to change convective flow, which is predominantly fine-scaled (Soderlund et al., 2012; King & Buffett, 2013). An important exception to this observation is in dynamo models that employ uniform heat flux boundary conditions, rather than the usual uniform temperature conditions, in which convection occurs on both small and large scales (Sakuraba & Roberts, 2009; Takahashi & Shimizu, 2012). How, exactly, thermal boundary conditions and magnetic field generation conspire to affect convection is not understood. We investigate the combined influence of thermal boundary conditions and magnetic fields using four simulations: two dynamos and two non-magnetic models, with either uniform temperature or heat flux fixed at the outer boundary. Of the four, only the fixed-heat-flux dynamo simulation produces multi-scale convective flow patterns. Comparison between the models suggests that the fixed-flux dynamo generates large patches of strong toroidal field that suppress convective motions near the outer boundary, giving rise to this observed change in convection scales. Strong toroidal field generation by this particular model is made possible by its relatively strong zonal flow, and its strong zonal flow is owed to a baroclinic response to meridional temperature gradients that persist in models with fixed heat flux boundary conditions. Thus, by allowing temperature to vary along the outer boundary, the fixed-flux dynamo generates stronger azimuthal flow and magnetic field, and the resulting Lorentz forces alter the nature of convective flow. References King, E.M., Buffett, B.A., Flow speeds and length scales in geodynamo models: the role of viscosity, Earth Planet. Sci. Lett., 2013, 371 156-162. Sakuraba, A., Roberts, P.H., Generation of a strong magnetic field using uniform heat flux at the surface of the core. Nature Geosci., 2009, 2 802-805. Soderlund, K.M., King, E.M., Aurnou, J.M., The weak influence of magnetic fields in planetary dynamo models. Earth Planet. Sci. Lett., 2012, 333. 9-20. Takahashi, F., Shimizu, H., A detailed analysis of a dynamo mechanism in a rapidly rotating spherical shell, J. Fluid Mech., 2012, 701, 228-250.

  8. Hard Questions 1 When Hard Questions are Asked: Evaluating Writing Centers

    E-print Network

    Northern British Columbia, University of

    Hard Questions 1 When Hard Questions are Asked: Evaluating Writing Centers James H. Bell University of Northern British Columbia 3333 University Way Prince George, BC Canada V2N 4Z9 RUNNING HEAD: Hard Questions Reading and Learning. Thank you to three reviewers for their revision suggestions. #12;Hard Questions 2

  9. Hard body amphiphiles at a hard wall JOSEPH M. BRADER1y

    E-print Network

    Ott, Albrecht

    Hard body amphiphiles at a hard wall JOSEPH M. BRADER1y , CHRISTIAN VON FERBER2 and MATTHIAS 2003) We investigate the structure of amphiphilic molecules exposed to a substrate that is modelled by a hard wall. Our simple model amphiphiles consist of a hard sphere head group to which a vanishingly thin

  10. Measurement of the sizes of circumstellar dust shells around evolved stars with high mass loss rates

    NASA Technical Reports Server (NTRS)

    Phillips, T. G.; Knapp, G. R.

    1992-01-01

    The research supported by the NASA ADP contract NAG5-1153 has been completed. The attached paper, which will be submitted for publication in the Astrophysical Journal in January 1992, presents the results of this work. Here is a summary of the project and its results. A set of computer programs was developed to process the raw 60 micron and 100 micron IRAS survey data. The programs were designed to detect faint extended emission surrounding a bright unresolved source. Candidate objects were chosen from a list of red giant stars and young planetary nebulae which have been detected in millimeter/submillimeter lines of CO. Of the 279 stars examined, 55 were resolved at 60 microns. The principle results of the study are given. The average age for the shells surrounding the 9 Mira-type stars which are extended is 6 x 10(exp 4) yr. This suggests that the period during which these stars lose mass lasts for approx 10(exp 5) yr. The oldest shell found surrounds U Ori, and the youngest surrounds Mira itself. Some shells appear to be detached from the central star. This phenomenon is more common among older stars, suggesting that the mass loss becomes more episodic as the star sheds its envelope. Although all 8 stars less distant than 200 pc are resolved in the IRAS 60 micron data, 29 stars within 500 pc were not. These stars probably have younger circumstellar shells than those which were resolved. Almost all the carbon stars with distances of 500 pc or less have resolved shells, while only 1/2 of the oxygen-rich stars do. The resolved carbon star shells also are older on average than the oxygen-rich ones. These facts imply that carbon stars have been losing mass for a longer period, on average, than oxygen-rich red giants. Large circumstellar shells tend to be found at large distances from the galactic plane, confirming that the ISM density limits the size to which a dust shell can grow. Surprisingly, even very large shells seem to be nearly spherical, and do not appear to be distorted by ram-pressure caused by the star's motion with respect to the ISM. Radiative transfer models and the value of I sub 60 microns/I sub 100 microns allow the average dust temperature in the outer regions of a circumstellar shell to be estimated. The typical value obtained in about 35 K.

  11. Doc.381, 'Nose flutes and shell trumpets'

    E-print Network

    Roth, George Kingsley

    of the triton shell or davui. First it is sounded clearly and well, but the other efforts are rather poor. Rakiraki, Kadavu, October 1955. Arranged recording [10.17-11.06] 6) Shell trumpet. Blowing of the triton shell or davui. Somosomo, Cakaudrove, June 1957... flutes and shell trumpets Translation of title Description (to be used in archive entry) Audio recording of nose flutes and shell trumpets, 15 min 51 seconds 1) Nose flute, fangofango - Copy of BBC recording (Library number 20468) made in December 1953...

  12. On growth and form of irregular coiled-shell of a terrestrial snail: Plectostoma concinnum (Fulton, 1901) (Mollusca: Caenogastropoda: Diplommatinidae)

    PubMed Central

    Kok, Annebelle C.M.; Schilthuizen, Menno; Urdy, Severine

    2014-01-01

    The molluscan shell can be viewed as a petrified representation of the organism’s ontogeny and thus can be used as a record of changes in form during growth. However, little empirical data is available on the actual growth and form of shells, as these are hard to quantify and examine simultaneously. To address these issues, we studied the growth and form of a land snail that has an irregularly coiled and heavily ornamented shell–Plectostoma concinnum. The growth data were collected in a natural growth experiment and the actual form changes of the aperture during shell ontogeny were quantified. We used an ontogeny axis that allows data of growth and form to be analysed simultaneously. Then, we examined the association between the growth and the form during three different whorl growing phases, namely, the regular coiled spire phase, the transitional constriction phase, and the distortedly-coiled tuba phase. In addition, we also explored the association between growth rate and the switching between whorl growing mode and rib growing mode. As a result, we show how the changes in the aperture ontogeny profiles in terms of aperture shape, size and growth trajectory, and the changes in growth rates, are associated with the different shell forms at different parts of the shell ontogeny. These associations suggest plausible constraints that underlie the three different shell ontogeny phases and the two different growth modes. We found that the mechanism behind the irregularly coiled-shell is the rotational changes of the animal’s body and mantle edge with respect to the previously secreted shell. Overall, we propose that future study should focus on the role of the mantle and the columellar muscular system in the determination of shell form. PMID:24883245

  13. Crystal Fabrics and Element Impurities (Sr, Mg, Ba) in Bivalve Shells - Implications for Paleoclimate Reconstructions

    NASA Astrophysics Data System (ADS)

    Schone, B. R.; Radermacher, P.; Zhang, Z.; Holland, H. A.

    2011-12-01

    Sr/Ca, Mg/Ca and Ba/Ca values are heterogeneously distributed in shells of the long-lived bivalve mollusk, Arctica islandica. These pattern are largely associated with crystal fabrics (size, habit and orientation of crystals) or the processes controlling them. The outer sublayer of the outer shell layer (oOSL; homogeneous and irregular simple prismatic crystal fabrics,) contained element/Ca values up to 62% higher than the inner sublayer (iOSL; crossed-acicular, crossed-lamellar, fine crossed-lamellar and irregular simple prismatic crystal fabrics). A gradual decrease in Sr/Ca and Mg/Ca values was observed from the outer portions of the oOSL toward the oOSL/iOSL transition zone. This chemical shift was accompanied by a gradual transition from homogeneous crystal fabrics into crossed-lamellar/acicular crystal fabrics. Near annual growth lines (irregular simple prisms), i.e., during periods of slow growth, Sr and Mg seemed to be deposited in equilibrium with the ambient environment because the Sr/Ca and Mg/Ca values approached values typical for seawater. During the remainder of the growing season, Sr/Ca and Mg/Ca remained far below values expected for thermodynamic equilibrium. Ba/Ca peaks, however, occurred erratically at different times of the year without any noticeable changes in crystal fabrics. Likely, the environmental information contained in these peaks was less severely filtered by vital effects than in Sr and Mg. The findings of the present study can help to develop new techniques with which extract environmental signals from the metal-to-calcium ratios of bivalve shells.

  14. 77 FR 3771 - Notice of Issuance of Final Outer Continental Shelf Air Permit for Shell Offshore, Inc.

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-25

    ...pollutant emissions from one of three deepwater drilling vessels (the Transocean Deepwater Nautilus, the Noble Bully I or the Noble Bully II) and support vessels to conduct exploratory drilling for up to 150 days per year over five to ten years...

  15. Synthesis of TiO{sub 2} core/RuO{sub 2} shell particles using multistep ultrasonic spray pyrolysis

    SciTech Connect

    Stopic, Srecko, E-mail: sstopic@ime-aachen.de [IME – Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestr. 3, D-52056 Aachen (Germany); Friedrich, Bernd [IME – Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestr. 3, D-52056 Aachen (Germany); Schroeder, Michael [IPC – Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52074 Aachen (Germany); Weirich, Thomas E. [GFE – Central Facility for Electron Microscopy, RWTH Aachen University, Ahornstr. 55, D-52074 Aachen (Germany); AIXTAL – Institute of Crystallography, RWTH Aachen University, Jägerstraße 17–19, D-52066 Aachen (Germany)

    2013-09-01

    Graphical abstract: - Highlights: • TiO{sub 2} core/RuO{sub 2} shell submicron-particles were prepared via a sequential spray pyrolysis. • Spherical particles have the mean particle diameters between 200 and 400 nm. • This method is promising for synthesis of core–shell and core–multishell materials. - Abstract: Spherical submicron-particles with TiO{sub 2} core–RuO{sub 2} shell structure have been synthesized by employing sequential ultrasonic spray pyrolysis. The particles have been investigated by X-ray powder diffraction, scanning electron microscopy and different transmission electron microscopy techniques. The quality of the core–shell structure of the particles has been confirmed by comparison of the experimental data with those generated on the basis of a hard sphere core–shell model. It has been found that the mixing of the Ru-containing aerosol with the TiO{sub 2} particle stream has a significant impact on the core–shell formation. The method introduced in this study can probably be applied for preparation of core–shell and core–multishell materials that are difficult to synthesize in a single step spray pyrolysis process.

  16. The Hard Problem of Cooperation

    PubMed Central

    Eriksson, Kimmo; Strimling, Pontus

    2012-01-01

    Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior. PMID:22792282

  17. Pressure Shell Approach to Integrated Environmental Protection

    NASA Technical Reports Server (NTRS)

    Kennedy, Kriss J.

    2011-01-01

    The next generation of exploration mission human systems will require environmental protection such as radiation protection that is effective and efficient. In order to continue human exploration, habitat systems will require special shells to protect astronauts from hostile environments. The Pressure Shell Approach to integrated environmental (radiation) protection is a multi-layer shell that can be used for multifunctional environmental protection. Self-healing, self-repairing nano technologies and sensors are incorporated into the shell. This shell consists of multiple layers that can be tailored for specific environmental protection needs. Mainly, this innovation focuses on protecting crew from exposure to micrometeorites, thermal, solar flares, and galactic cosmic ray (GCR) radiation. The Pressure Shell Approach consists of a micrometeoroid and secondary ejecta protection layer; a thin, composite shell placed in between two layers that is non-structural; an open cavity layer that can be filled with water, regolith, or polyethylene foam; a thicker composite shell that is a structural load bearing that is placed between two layers; and a bladder coating on the interior composite shell. This multi-layer shell creates an effective radiation protection system. Most of its layers can be designed with the materials necessary for specific environments. In situ materials such as water or regolith can be added to the shell design for supplemental radiation protection.

  18. The onset of time-dependent convection in spherical shells as a clue to chaotic convection in the earth's mantle

    NASA Technical Reports Server (NTRS)

    Machetel, Philippe; Yuen, David

    1986-01-01

    This work presents a detailed numerical study of the dynamical behavior of convection in a spherical shell, as applied to mantle convection. From both two-dimensional (120 radial and 360 tangential points) and three-dimensional (60 radial levels and spherical harmonics up to order and degree L = 33, m = 33), it is shown that for a spherical shell (with inner-to-outer radii ratio eta = 0.62) convection becomes time-dependent, with l = 2 dominating, at a Rayleigh number of about 31 times supercritical for a constant-viscosity, base-heated configuration. This secondary instability is characterized by oscillatory time dependence, with higher frequencies involved, at slightly higher Rayleigh numbers. In illustrating the onset of time dependence, the analysis is extended to show that the onset of weak turbulence in spherical-shell convection takes place at about 60 times the critical Rayleigh number via a quasi-periodic mode.

  19. Encapsulating Pd Nanoparticles in Double-Shelled Graphene@Carbon Hollow Spheres for Excellent Chemical Catalytic Property

    PubMed Central

    Zhang, Zheye; Xiao, Fei; Xi, Jiangbo; Sun, Tai; Xiao, Shuang; Wang, Hairong; Wang, Shuai; Liu, Yunqi

    2014-01-01

    Double-shelled hollow carbon spheres with reduced graphene oxide (RGO) as inner shell and carbon (C) layer as outer shell have been successfully designed and prepared. This tailor-making structure acts as an excellent capsule for encapsulating with ultrafine Pd nanoparticles (Pd NPs), which could effectively prevent Pd NPs from aggregation and leaching. As a result, the as-obtained RGO@Pd@C nanohybid exhibits superior and stable catalytic performance. With the aid of RGO@Pd@C, the reduction reaction of 4-nitrophenol (4-NP) to 4-aminophenol with NaBH4 as reducing agent can be finished within only 30?s, even the content of Pd is as low as 0.28 wt%. As far as we know, RGO@Pd@C is one of the most effective catalyst for 4-NP reducing reaction up to now. PMID:24514577

  20. Sampling hard to reach populations.

    PubMed

    Faugier, J; Sargeant, M

    1997-10-01

    Studies on 'hidden populations', such as homeless people, prostitutes and drug addicts, raise a number of specific methodological questions usually absent from research involving known populations and less sensitive subjects. This paper examines the advantages and limitations of nonrandom methods of data collection such as snowball sampling. It reviews the currently available literature on sampling hard to reach populations and highlights the dearth of material currently available on this subject. The paper also assesses the potential for using these methods in nursing research. The sampling methodology used by Faugier (1996) in her study of prostitutes, HIV and drugs is used as a current example within this context. PMID:9354993

  1. Outer Hair Cells and Prestin—A Moderated Discussion

    NASA Astrophysics Data System (ADS)

    Brownell, William E.; Gummer, Anthony W.

    2011-11-01

    A discussion moderated by the authors on the topic "Outer Hair Cells and Prestin" was held on 18 July 2011 at the 11th International Mechanics of Hearing Workshop in Williamstown, Massachusetts. The paper provides an edited transcript of the session.

  2. Outer Space: A Multi-Age, Integrated Subjects Curriculum Unit.

    ERIC Educational Resources Information Center

    Hall, William D.

    This multi-age integrated teaching unit on outer space was developed by 19 rural teachers (grades K-8) from 12 Gallatin County (Montana) districts to associate all school subjects with a common theme, promote teaching efficiency by focusing on more than one subject at the same time, and increase student excitement. Topics explored by each grade…

  3. Jupiter Observation Campaign: Citizen Science at the Outer Planets

    Microsoft Academic Search

    J. Houston. Jones; A. Wessen; Robert Pappalardo; Kerri Beisser; Preston Dyches

    2010-01-01

    NASA Solar System Education and Public Outreach (E\\/PO) will coordinate and disseminate a consistent process for receiving Jupiter observation data from citizen scientists. This may include a public repository or network matching scientists with citizen scientists who want to provide needed observations in a standard and consistent format. This will be a good Outer Planet mission contribution to the science

  4. An outer-approximation algorithm for generalized maximum entropy sampling

    Microsoft Academic Search

    Han-Lim Choi; Paul I. Barton

    2008-01-01

    This paper presents an outer-approximation algorithm to address a generalized maximum entropy sampling (GMES) problem that determines a set of measurement locations providing the largest entropy reduction. A new mixed- integer semidefinite program (MISDP) formulation is proposed to handle a GMES problem with a jointly Gaussian distribution over the search space. This formulation employs binary variables to indicate if the

  5. An outer ion coma model in two dimension

    NASA Technical Reports Server (NTRS)

    Ip, W.-H.; Huntress, W. T.

    1983-01-01

    A simple cometary outer ion coma model is constructed by adopting published results from numerical MHD computations. The ion composition and density distributions so derived are used to highlight some of the basic features of cometary plasma flows and the need for cometary ion observations with absolute brightness calibration.

  6. Mechanisms of protein import across the mitochondrial outer membrane

    Microsoft Academic Search

    Roland Lill; Walter Neupert

    1996-01-01

    Mitochondria import the majority of their proteins from the cytosol. At the mitochondrial outer membrane, import is initiated through a series of reactions, which include preprotein recognition, unfolding, insertion and translocation. These processes are facilitated by a multisubunit complex, the TOM complex. Specific roles can now be assigned to several components of this complex. Although the import machinery of the

  7. Aerocapture Technology Development Needs for Outer Planet Exploration

    NASA Technical Reports Server (NTRS)

    Wercinski, Paul; Munk, Michelle; Powell, Richard; Hall, Jeff; Graves, Claude; Partridge, Harry (Technical Monitor)

    2002-01-01

    The purpose of this white paper is to identify aerocapture technology and system level development needs to enable NASA future mission planning to support Outer Planet Exploration. Aerocapture is a flight maneuver that takes place at very high speeds within a planet's atmosphere that provides a change in velocity using aerodynamic forces (in contrast to propulsive thrust) for orbit insertion. Aerocapture is very much a system level technology where individual disciplines such as system analysis and integrated vehicle design, aerodynamics, aerothermal environments, thermal protection systems (TPS), guidance, navigation and control (GN&C) instrumentation need to be integrated and optimized to meet mission specific requirements. This paper identifies on-going activities, their relevance and potential benefit to outer planet aerocapture that include New Millennium ST7 Aerocapture concept definition study, Mars Exploration Program aeroassist project level support, and FY01 Aeroassist In-Space Guideline tasks. The challenges of performing aerocapture for outer planet missions such as Titan Explorer or Neptune Orbiter require investments to advance the technology readiness of the aerocapture technology disciplines for the unique application of outer planet aerocapture. This white paper will identify critical technology gaps (with emphasis on aeroshell concepts) and strategies for advancement.

  8. RMP Colloquia Sputtering of ices in the outer solar system

    E-print Network

    Johnson, Robert E.

    , University of Virginia, Charlottesville, Virginia 22903 Exploration of the outer solar system has led-solar-system phenomena: the sputter-produced plasma trapped in Saturn's magnetosphere; the O2 atmosphere on Europa; and optical absorption features such as SO2 in the surface of Europa and O2 and, possibly, O3 in the surface

  9. Virulent strain associated outer membrane proteins of Borrelia burgdorferi.

    PubMed Central

    Skare, J T; Shang, E S; Foley, D M; Blanco, D R; Champion, C I; Mirzabekov, T; Sokolov, Y; Kagan, B L; Miller, J N; Lovett, M A

    1995-01-01

    We have isolated and purified outer membrane vesicles (OMV) from Borrelia burgdorferi strain B31 based on methods developed for isolation of Treponema pallidum OMV. Purified OMV exhibited distinct porin activities with conductances of 0.6 and 12.6 nano-Siemen and had no detectable beta-NADH oxidase activity indicating their outer membrane origin and their lack of inner membrane contamination, respectively. Hydrophobic proteins were identified by phase partitioning with Triton X-114. Most of these hydrophobic membrane proteins were not acylated, suggesting that they are outer membrane-spanning proteins. Identification of palmitate-labeled lipoproteins revealed that several were enriched in the OMV, several were enriched in the protoplasmic cylinder inner membrane fraction, and others were found exclusively associated with the inner membrane. The protein composition of OMV changed significantly with successive in vitro cultivation of strain B31. Using antiserum with specificity for virulent strain B31, we identified OMV antigens on the surface of the spirochete and identified proteins whose presence in OMV could be correlated with virulence and protective immunity in the rabbit Lyme disease model. These virulent strain associated outer membrane-spanning proteins may provide new insight into the pathogenesis of Lyme disease. Images PMID:7593626

  10. OIL AND GAS LEASING ON THE OUTER CONTINENTAL SHELF

    E-print Network

    Lotko, William

    Management Service (MMS) is a bureau in the United States Department of the Interior that manages the Outer offshore renewable and traditional energy and mineral resources. The MMS also manages approximately 1 the human, marine, and coastal environments through advanced science and technology research

  11. Gravitational wave extraction and outer boundary conditions by perturbative matching

    E-print Network

    The Binary Black Hole Grand Challenge Alliance; :; A. M. Abrahams; L. Rezzolla; M. E. Rupright; A. Anderson; P. Anninos; T. W. Baumgarte; N. T. Bishop; S. R. Brandt; J. C. Browne; K. Camarda; M. W. Choptuik; G. B. Cook; C. R. Evans; L. S. Finn; G. Fox; R. Gomez; T. Haupt; M. F. Huq; L. E. Kidder; S. Klasky; P. Laguna; W. Landry; L. Lehner; J. Lenaghan; R. L. Marsa; J. Masso; R. A. Matzner; S. Mitra; P. Papadopoulos; M. Parashar; F. Saied; P. E. Saylor; M. A. Scheel; E. Seidel; S. L. Shapiro; D. Shoemaker; L. Smarr; B. Szilagyi; S. A. Teukolsky; M. H. P. M. van Putten; P. Walker; J. Winicour; J. W. York Jr

    1997-09-30

    We present a method for extracting gravitational radiation from a three-dimensional numerical relativity simulation and, using the extracted data, to provide outer boundary conditions. The method treats dynamical gravitational variables as nonspherical perturbations of Schwarzschild geometry. We discuss a code which implements this method and present results of tests which have been performed with a three dimensional numerical relativity code.

  12. Outer Plexiform Layer Receptive Fields As Underlying Factors Of The

    E-print Network

    Bargiela, Andrzej

    . Outer Plexiform Layer Receptive Fields As Underlying Factors Of The Hermann Grid Illusion Tran of retinal prostheses. Keywords: Hermann grid illusion, retina, receptive field. I. INTRODUCTION When people the optical illusions, the luminance and contrast illusions described via the Hermann grid have received

  13. Energetic outer zone electron loss timescales during low geomagnetic activity

    Microsoft Academic Search

    Nigel P. Meredith; Richard B. Horne; Sarah A. Glauert; Richard M. Thorne; Danny Summers; Jay M. Albert; Roger R. Anderson

    2006-01-01

    Following enhanced magnetic activity the fluxes of energetic electrons in the Earth's outer radiation belt gradually decay to quiet-time levels. We use CRRES observations to estimate the energetic electron loss timescales and to identify the principal loss mechanisms. Gradual loss of energetic electrons in the region 3.0 ? L ? 5.0 occurs during quiet periods (Kp 7), indicating that the

  14. The Origin of Chaos in the Outer Solar System

    E-print Network

    Murray, Norman

    responsible for the acceptance of Newton's theory of gravitation. Despite this, Newton doubted the longThe Origin of Chaos in the Outer Solar System N. Murray1 and M. Holman2 Classical analytic theories. This disagreement is resolved by a new analytic theory. The theory shows that the chaos among the jovian planets

  15. EOS Science Poster Series: AIR-Our Outer Atmosphere

    NSDL National Science Digital Library

    This poster depicts how NASA scientists are working to understand the outer atmosphere (air). Satellite images, graphs, and pictures complement the fact-filled information. The poster can be ordered from the Web site; this site also includes PowerPoint and PDF files with the poster information.

  16. Auroral radio emissions at the outer planets: Observations and theories

    Microsoft Academic Search

    Philippe Zarka

    1998-01-01

    We review both observational and theoretical aspects of the generation of auroral radio emissions at the outer planets, trying to organize the former in a coherent frame set by the latter. Important results have been obtained in the past few years on these radio emissions at the five magnetized planets, from the observations of Ulysses at Jupiter and of Wind

  17. Rhodopsin in the rod outer segment plasma membrane

    Microsoft Academic Search

    SCOTT BASINGER; DEAN BOK; MICHAEL HALL

    1976-01-01

    Isolated frog retinas were incubated in vitro with a 4-h pulse of (3H)leucine, then chased for 32 h with a nonradioactive amino acid mixture. At the end of the incubation, light and electron microscope autoradiograms were prepared from some of the retinas. The autoradiograms revealed: (a) intense radioactivity in the basal disks of the rod outer segments, (b) diffuse label

  18. Fields and plasmas in the outer solar system

    Microsoft Academic Search

    Edward J. Smith; John H. Wolfe

    1979-01-01

    The most significant information about fields and plasmas in the outer solar system, based on observations by Pioneer 10 and 11 investigations, is reviewed. The characteristic evolution of solar wind streams beyond 1 AU has been observed. The region within which the velocity increases continuously near 1 AU is replaced at larger distances by a thick interaction region with abrupt

  19. 3-D orbital evolution model of outer asteroid belt

    NASA Technical Reports Server (NTRS)

    Solovaya, Nina A.; Gerasimov, Igor A.; Pittich, Eduard M.

    1992-01-01

    The evolution of minor planets in the outer part of the asteroid belt is considered. In the framework of the semi-averaged elliptic restricted three-dimensional three-body model, the boundary of regions of the Hill's stability is found. As was shown in our work, the Jacobian integral exists.

  20. Identification of Pasteurella multocida CHAPS-soluble outer membrane proteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fowl cholera continues to be of concern to the poultry industry, especially for turkey growers. This disease costs the turkey industry millions of dollars annually. In order to gain a better understanding of Pasteurella multocida virulence factors involved in colonization and pathogenesis, the outer...

  1. Hydrocarbon geochemistry in surface sediments of Alaskan Outer Continental shelf

    Microsoft Academic Search

    M. I. Venkatesan; I. R. Kaplan; E. Ruth

    1983-01-01

    The Cââ+ hydrocarbons in 220 surface sediments from the outer continental shelf of Alaska were analyzed as part of an environmental survey supervised by National Oceanic and Atmospheric Administration and Bureau of Land Management. Gas chromatography and gas chromatography-mass spectrometry were employed for the identification of organic compounds in the bitumen extracts. Surface sediments from one station in southeastern Bering

  2. BIOREACTOR DESIGN - OUTER LOOP LANDFILL RESEARCH PROJECT, LOUISVILLE, KY

    EPA Science Inventory

    Bioreactor field demonstration projects are underway at the Outer Loop Landfill, Louisville, KY. The research effort is a cooperative research effort between USEPA and Waste Management, Inc. Two primary kinds of municipal waste bioreactors are under study at this site. First, new...

  3. Light elements in the Earth's outer core: A critical review

    Microsoft Academic Search

    Jean-Paul Poirier

    1994-01-01

    There is little doubt that densities for the Earth's outer core, inferred from seismology, require that it is constituted of an alloy of liquid iron and light elements. However, the nature of the light alloying elements is still uncertain as it depends in a large measure on the conditions of accretion of the Earth and formation of the core. The

  4. Fluid flow near the surface of earth's outer core

    Microsoft Academic Search

    Jeremy Bloxham; Andrew Jackson

    1991-01-01

    This review examines the recent attempts at extracting information on the pattern of fluid flow near the surface of the outer core from the geomagnetic secular variation. Maps of the fluid flow at the core surface are important as they may provide some insight into the process of the geodynamo and may place useful constraints on geodynamo models. In contrast

  5. VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING NORTH. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING NORTH. GRANITE COPING DEFINES THE SWAIN FAMILY PLOT, WHICH CONTAINS A CELTIC CROSS, ON WHICH THE CIRCLE REFERS TO ETERNAL LIFE, AND A RECLINING HUMAN FIGURE IN ETERNAL SLEEP - Woodlands Cemetery, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  6. Death from Outer Space, Did an Asteroid Impact Wipe out

    E-print Network

    Kammer, Thomas

    Death from Outer Space, Did an Asteroid Impact Wipe out the Dinosaurs? #12;#12;The asteroid Gaspra - 7x7x12 miles #12;A Gallery of Asteroids #12;Was it really an asteroid? We must have multiple working, Australia. Crater age is 142 Ma, but no mass extinction. #12;A 4 km wide asteroid hit America at the end

  7. Death from Outer Space, Did an Asteroid Impact Wipe out

    E-print Network

    Kammer, Thomas

    Death from Outer Space, Did an Asteroid Impact Wipe out the Dinosaurs? #12;#12;The asteroid Gaspra - 7x7x12 miles #12;A Gallery of Asteroids #12;Was it really an asteroid? We must have multiple working Bluff, Australia. Crater age is 142 Ma, but no mass extinction. #12;A 4 km wide asteroid hit America

  8. VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING SOUTHEAST. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF THE OUTER RING OF CENTER CIRCLE, LOOKING SOUTHEAST. THE MONUMENT AT CENTER-RIGHT, COMPRISED OF A CUBE OF RUSTICATED STONE SURMOUNTED BY A DOME AND STATUE, IS THE BURNS-DETRE TOMB (CA. 1882 - Woodlands Cemetery, 4000 Woodlands Avenue, Philadelphia, Philadelphia County, PA

  9. Magnetospheric convection and thermal ions in the dayside outer magnetosphere

    Microsoft Academic Search

    S.-H. Chen; T. E. Moore

    2006-01-01

    We have surveyed 3.5 years of Polar Thermal Ion Dynamics Experiment (TIDE) data between 1 January 2000 and 30 June 2003, when Polar apogee paths (sections of orbits with geocentric distances r > 5 RE) were in the dayside outer magnetosphere, to study the spatial distribution of thermal ions and the magnetospheric convection paths of the thermal ions, as a

  10. Applications Of Graphite Fluoride Fibers In Outer Space

    NASA Technical Reports Server (NTRS)

    Hung, Ching-Cheng; Long, Martin; Dever, Therese

    1993-01-01

    Report characterizes graphite fluoride fibers made from commercially available graphitized carbon fibers and discusses some potential applications of graphite fluoride fibers in outer space. Applications include heat-sinking printed-circuit boards, solar concentrators, and absorption of radar waves. Other applications based on exploitation of increased resistance to degradation by atomic oxygen, present in low orbits around Earth.

  11. Estimation of calcified tissues hardness via calcium and magnesium ionic to atomic line intensity ratio in laser induced breakdown spectra

    NASA Astrophysics Data System (ADS)

    Abdel-Salam, Z. A.; Galmed, A. H.; Tognoni, E.; Harith, M. A.

    2007-12-01

    Calcified tissues representing three different matrices, namely enamel of human teeth, shells and eggshell, have been studied via Laser Induced Breakdown Spectroscopy (LIBS) technique. The experimental CaII/CaI and MgII/MgI ratios have been measured, in view of the expected correlation between the extent of ionization caused by the laser induced shock wave (SW) and the hardness of the target. The ratio CaII/CaI between the ionic calcium line at 373.69 nm and the neutral line at 428.9 nm is obtained for enamel, shells and eggshell spectra, as well as the ratio MgII/MgI between the ionic magnesium line at 280.26 nm and the neutral line at 285.22 nm. The results show that such spectral lines intensities ratio differs for different matrices and is indeed related to the target materials hardness. It is also found that the MgII/MgI ratio is preferable as an indicator of hardness since these lines are less affected by self absorption. The SW front speed has been measured in the three cases and the obtained values confirm the proportionality to the target hardness. The results here obtained suggest the feasibility of the quantitative estimation of hardness for any other calcified tissues.

  12. Core-double-shell Fe3O4@carbon@poly(In(III)-carboxylate) microspheres: cycloaddition of CO2 and epoxides on coordination polymer shells constituted by imidazolium-derived Al(III)-Salen bifunctional catalysts.

    PubMed

    An, Qiao; Li, Zifeng; Graff, Robert; Guo, Jia; Gao, Haifeng; Wang, Changchun

    2015-03-01

    A hydrid microsphere Fe3O4@carbon@poly(In(III)-carboxylate) consisting of a cluster of Fe3O4 nanoparticles as the core, a carbon layer as the inner shell and a porous In(III)-carboxylate coordination polymer as the outer shell was prepared and applied as a recyclable catalyst for the cycloaddition reaction of CO2 and epoxides. Construction of this hybrid microsphere was achieved in the two steps, including (1) the one-pot solvothermal synthesis of Fe3O4@C particles with the abundant carboxylic groups on the carbon surface and (2) the subsequent growth of the outer shell polymers based on the precipitation coordination polymerization. Imidazolium-substituted Salen ligands were synthesized and chelated with the In(III) ions using the terminal carboxylic groups. The coordination polymer shell was formed on the Fe3O4@C particles, and the structures including shell thickness, surface area and porosity could be varied by tuning the feeding ratios of the In(III) ions and the ligands. The optimal structure of the coordination polymers showed a shell thickness of ca. 45 nm with ?5 nm of mesopore, 174.7 m(2)/g of surface area and 0.2175 cm(3)/g of pore volume. In light of gas uptake capability, catalytic activity and magnetic susceptibility, cycloaddition of CO2 with a series of epoxides were studied by using Al-complexed Fe3O4@C@In(III)-[IL-Salen] microspheres. The results validated that the self-supporting catalytic layer with high surface area was of remarkable advantages, which were attributed from great increment of effective active sites and combination of nucleophilic/electrophilic synergistic property and CO2 uptake capability. Therefore, these hybrid microspheres provided excellent catalytic activity, prominent selectivity to cyclic carbonates and outstanding recyclability with the assistance of an applied magnetic field. PMID:25674936

  13. Observation of shells in Coulomb explosions of rare-gas clusters

    SciTech Connect

    Erk, B.; Hoffmann, K.; Kandadai, N.; Helal, A.; Keto, J.; Ditmire, T. [Texas Center for High Intensity Laser Science, Department of Physics, University of Texas at Austin, Austin, Texas 78712 (United States)

    2011-04-15

    The explosions of noble gas clusters from argon and xenon irradiated by intense 35-fs infrared laser pulses have been studied. The kinetic energy spectra of ions produced in small clusters (<700 atoms) show a two-mode shell structure that is attributed to originating from a radial charge distribution. With a simple classical particle simulation of Coulomb explosions, the energy structure was reproduced using information on the arrangement of charge in the cluster. It was found that, during the explosion, the inner atoms of the clusters were less ionized than the outer atoms.

  14. Evaluation of discontinuity stresses in thick walled cylindrical shells by means of an embedded polariscope 

    E-print Network

    Cano, Narciso Ortiz

    1968-01-01

    section of a thick cylindrical shell. Each polarizing sheet consists of a film of Polaroid mated to a quarter-wave plate. The outer surfaces are coated with a thin film of acetate. If the sheets are arranged with the quarter-wave plates facing each... of the specimens were milled smooth to approximate conditions that would be found on the actual models. In preparing the plastic surfaces, the procedure used was as follows: 1. Lap the surface with a strip of silicon carbide (280 grit). Remove residue and wipe...

  15. Cryogenic target-implosion experiments on OMEGA D R Harding, D D Meyerhofer, T C Sangster, S J Loucks, R L McCrory, R Betti,

    E-print Network

    Cryogenic target-implosion experiments on OMEGA D R Harding, D D Meyerhofer, T C Sangster, S J imploded on OMEGA [2] are energy scaled from National Ignition Facility (NIF) ignition targets. The key. The direct-drive-target design The OMEGA ignition-scaled target is a spherical shell with a thin

  16. HARD CLAM, MERCENARIA MERCENARIA: SHELL GROWTH PATTERNS IN CHESAPEAKE BAyl,2

    E-print Network

    . One microgrowth increment in the prismatic layer was former! during each solar day of activity (growth of Marine Science, The College of William and Mary, Gloucester Point, Va.; Present address: Rutgers

  17. Spatio-kinematic modelling of the double-shelled PN Abell 65

    NASA Astrophysics Data System (ADS)

    Jones, D.; Huckvale, L.; Prouse, B.; Lloyd, M.; Pollacco, D.

    Abell 65 is one of the few planetary nebulae known to contain a binary central star, and as such represents an opportunity to investigate the effect of binarity on nebula formation and evolution. Deep imaging and high-resolution echelle spectroscopy, in conjunction with spatio-kinematic modelling, reveal the bipolar nature of Abell 65 and importantly a nebular inclination consistent with that of the central binary, indicating that the binary may have played a dominant role in the shaping of the nebula. Furthermore, the data reveal the presence of two nebular shells, each with similar morphologies and inclinations, but not co-eval in nature (with the outer-shell being kinematically older).

  18. Scanning electron microscope studies of the egg shell in some anostraca (Crustacea: Branchiopoda).

    PubMed

    Gilchrist, B M

    1978-10-17

    The tertiary shell of the eggs of anostracan crustaceans consists of two layers, an outer cortex and an inner alveolar layer. Scanning electron microscope studies show that, in most species, these layers are separated by a subcortical space which intercommunicates with spaces in the cortex and with the meshwork of the alveolar layer. No evidence was found for direct communication between pores on the surface of Branchipus stagnalis eggs and the subcortical space. No surface pores were found in the eggs of Branchinecta packardi, Chirocephalus diaphanus, Artemia salina, nor in eggs of the notostracan Triops cancriformis. Similarities in structure and possible functions of the egg shells of anostracan crustaceans and certain insects are discussed in relation to similarities in certain features of their environments. PMID:569018

  19. Critical stability of almost adiabatic convection in a rapidly rotating thick spherical shell

    SciTech Connect

    Starchenko, S. V., E-mail: sstarchenko@mail.ru [Russian Academy of Sciences, Institute of Terrestrial Magnetism, the Ionosphere, and Radiowave Propagation (Russian Federation); Kotelnikova, M. S. [Lavrentyev Institute of Hydrodynamics (Russian Federation)] [Lavrentyev Institute of Hydrodynamics (Russian Federation)

    2013-02-15

    In this work, the convection equations in the almost adiabatic approximation is studied for which the choice of physical parameters is primarily based on possible applications to the hydrodynamics of the deep interiors of the Earth and planets and moons of the terrestrial group. The initial system of partial differential equations (PDEs) was simplified to a single second-order ordinary differential equation for the pressure or vertical velocity component to investigate the linear stability of convection. The critical frequencies, modified Rayleigh numbers, and distributions of convection are obtained at various possible Prandtl numbers and in different thick fluid shells. An analytical WKB-type solution was obtained for the case when the inner radius of the shell is much smaller than the outer radius and convective sources are concentrated along the inner boundary.

  20. Shelling in low dimensional manifolds 

    E-print Network

    Murray, William Owen

    1974-01-01

    the style of the Proceedings of the American Mathematical Society. M and h n Bd(M) is an (n ? 1)-cell, then h is said to be free in M. Suppose S is a subset of M and T is a cellular decomposition of S. S can be shelled from M relative... to T if the elements of T can be given an ordering C , C . . . C such that C. is free in Cl[M? n i U C. ], i = 1, 2, . . . , n. Note if S = M, then S can be shelled j&i relative to T means there is an ordering Cl, C2, . . . , C of the ele- n ments of T so that C...