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1

Radiation hardness of the LHCb Outer Tracker  

NASA Astrophysics Data System (ADS)

This paper presents results on the radiation hardness of the LHCb Outer Tracker (OT) during LHC operation in 2010 and 2011. Modules of the OT have shown to suffer from ageing effects that lead to gain loss, after irradiation in the laboratory. Under irradiation at moderate intensities an insulating layer is formed on the anode wire of the OT straw cells. This ageing effect is caused by contamination of the counting gas due to outgassing of the glue used in the construction of the OT modules. Two methods to monitor gain stability in the OT are presented: module scans with radioactive sources and the study of hit efficiency as a function of amplifier threshold. No gain loss is observed after receiving 1.3 fb-1 of integrated luminosity corresponding to an integrated charge of 0.055 C/cm in the hottest spot of the detector.

van Eijk, D.; Bachmann, S.; Bauer, Th.; Färber, Ch.; Bien, A.; Coco, V.; Deckenhoff, M.; Dettori, F.; Ekelhof, R.; Gersabeck, E.; Karbach, T. M.; Koopman, R.; Kozlinskiy, A.; Langenbruch, Ch.; Linn, Ch.; Merk, M.; Meissner, M.; Morawski, P.; Pellegrino, A.; Serra, N.; Seyfert, P.; Spaan, B.; Swientek, S.; Storaci, B.; Szczekowski, M.; Tuning, N.; Uwer, U.; Visser, E.; Wiedner, D.; Witek, M.

2012-09-01

2

Apparatus and methods for installing, removing and adjusting an inner turbine shell section relative to an outer turbine shell section  

DOEpatents

A turbine includes upper and lower inner shell sections mounting the nozzles and shrouds and which inner shell is supported by pins secured to a surrounding outer shell. To disassemble the turbine for access to the inner shell sections and rotor, an alignment fixture is secured to the lower outer shell section and has pins engaging the inner shell section. To disassemble the turbine, the inner shell weight is transferred to the lower outer shell section via the alignment fixture and cradle pins. Roller assemblies are inserted through access openings vacated by support pins to permit rotation of the lower inner shell section out of and into the lower outer shell section during disassembly and assembly. The alignment fixture includes adjusting rods for adjusting the inner shell axially, vertically, laterally and about a lateral axis. A roller over-cage is provided to rotate the inner shell and a dummy shell to facilitate assembly and disassembly in the field.

Leach, David (Niskayuna, NY); Bergendahl, Peter Allen (Scotia, NY); Waldo, Stuart Forrest (Salem, NC); Smith, Robert Leroy (Milford, OH); Phelps, Robert Kim (Milford, OH)

2001-01-01

3

Architecture in outer space. [multilayer shell systems filled with gas  

NASA Technical Reports Server (NTRS)

Mulilayer thin film structures consisting of systems of shells filled with gas at some pressure are recommended for outer space structures: Large mirrors to collect light and radio waves, protection against meteoric impact and damage, and for connectors between state space stations in the form of orbital rings. It is projected that individual orbital rings will multiply and completely seal a star trapping its high temperature radiation and transforming it into low temperature infrared and short wave radio emission; this radiation energy could be utilized for technological and biological processes.

Pokrovskiy, G. I.

1974-01-01

4

Acoustic destruction of a microcapsule having a hard plastic shell  

Microsoft Academic Search

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

Daisuke Koyama; Atsushi Osaki; Wataru Kiyan; Yoshiaki Watanabe

2006-01-01

5

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

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

6

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

NASA Astrophysics Data System (ADS)

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.

Amusia, Miron; Chernysheva, Larissa

2012-06-01

7

77 FR 7148 - Notice of Approval of Clean Air Act Outer Continental Shelf Permits Issued to Shell Gulf of...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Air Act Outer Continental Shelf Permits Issued to Shell Gulf of Mexico, Inc., and Shell Offshore, Inc. for the Discoverer Drillship AGENCY...Continental Shelf (OCS) permit applications, one from Shell Gulf of Mexico, Inc., for operation of the...

2012-02-10

8

DETECTING THE RAPIDLY EXPANDING OUTER SHELL OF THE CRAB NEBULA: WHERE TO LOOK  

SciTech Connect

We present a range of steady-state photoionization simulations, corresponding to different assumed shell geometries and compositions, of the unseen postulated rapidly expanding outer shell to the Crab Nebula. The properties of the shell are constrained by the mass that must lie within it, and by limits to the intensities of hydrogen recombination lines. In all cases the photoionization models predict very strong emissions from high ionization lines that will not be emitted by the Crab's filaments, alleviating problems with detecting these lines in the presence of light scattered from brighter parts of the Crab. The near-NIR [Ne VI] {lambda}7.652 {mu}m line is a particularly good case; it should be dramatically brighter than the optical lines commonly used in searches. The C IV {lambda}1549 doublet is predicted to be the strongest absorption line from the shell, which is in agreement with Hubble Space Telescope observations. We show that the cooling timescale for the outer shell is much longer than the age of the Crab, due to the low density. This means that the temperature of the shell will actually ''remember'' its initial conditions. However, the recombination time is much shorter than the age of the Crab, so the predicted level of ionization should approximate the real ionization. In any case, it is clear that IR observations present the best opportunity to detect the outer shell and so guide future models that will constrain early events in the original explosion.

Wang Xiang; Ferland, G. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Baldwin, J. A.; Loh, E. D.; Richardson, C. T., E-mail: xiang.wang@uky.edu [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-2320 (United States)

2013-09-10

9

Preliminary engineering studies for the support shell of the outer tracker of the SDC detector  

SciTech Connect

The Solenoidal Detector Collaboration (SDC) detector is in the conceptual design phase. ORNL is currently working with various sub-groups on the design of the outer tracker portion of the SDC detector. A major focus in the outer tracker design is the structure that mounts and supports the tracking elements. This structure must meet extreme requirements of alignment and stability while containing a minimum of material. This report describes the requirements, evaluations, and analyses that have been performed on the two options being explored; a cylindrical support shell and a modular support shell.

Vandergriff, D.H.; Mayhall, J.

1991-09-01

10

Electronic transport properties of inner and outer shells in near ohmic-contacted double-walled carbon nanotube transistors  

SciTech Connect

We investigate electronic transport properties of field-effect transistors based on double-walled carbon nanotubes, of which inner shells are metallic and outer shells are semiconducting. When both shells are turned on, electron-phonon scattering is found to be the dominant phenomenon. On the other hand, when outer semiconducting shells are turned off, a zero-bias anomaly emerges in the dependence of differential conductance on the bias voltage, which is characterized according to the Tomonaga-Luttinger liquid model describing tunneling into one-dimensional materials. We attribute these behaviors to different contact conditions for outer and inner shells of the double-walled carbon nanotubes. A simple model combining Luttinger liquid model for inner metallic shells and electron-phonon scattering in outer semiconducting shells is given here to explain our transport data at different temperatures.

Zhang, Yuchun; Zhou, Liyan; Zhao, Shangqian; Wang, Wenlong; Liang, Wenjie, E-mail: wjliang@iphy.ac.cn [Beijing National Laboratory For Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Enge [International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871 (China)

2014-06-14

11

Effect of magnesium stearate or calcium stearate as additives on dissolution profiles of diltiazem hydrochloride from press-coated tablets with hydroxypropylmethylcellulose acetate succinate in the outer shell.  

PubMed

Effect of magnesium stearate (MgSt) or calcium stearate (CaSt) on the dissolution profiles of diltiazem hydrochloride in the core of press-coated (PC) tablets with an outer shell composed of hydroxypropylmethylcellulose acetate succinate (HPMCAS) was evaluated by porosity and changes in IR spectra of tablets. In JP first fluid (pH 1.2), the lag time increased with decreasing porosity and was greatest by the addition of MgSt to HPMCAS. While, in JP second fluid (pH 6.8), it increased with decreasing porosity by the addition of CaSt, but hardly changed by the addition of MgSt. Thus, using tablets prepared with the same composition as the outer shell, the changes in IR spectra and uptake amount of the dissolution media after immersion in first fluid and second fluid were determined. The results suggested that some physicochemical interaction occur between MgSt and HPMCAS in tablets with HPMCAS and MgSt and the uptake increased markedly in each dissolution medium. These phenomena seem to cause a prolongation of lag time in first fluid but a shortening of it in second fluid in PC tablets with HPMCAS and MgSt. In contrast, CaSt and HPMCAS did not show such interactions and increased the hydrophobic properties of the outer shell. Consequently, the lag time was only slightly prolonged in first fluid, however, markedly prolonged in second fluid due to suppression of second fluid penetration into micro pores in the outer shell and HPMCAS gel formation on the surface in PC tablets with HPMCAS and CaSt. PMID:11274815

Fukui, E; Miyamura, N; Kobayashi, M

2001-03-23

12

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

PubMed

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

Nayeri, M; Zackrisson, M; Bergenholtz, J

2009-06-18

13

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

E-print Network

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

Sandwell, David T.

14

Prediction of the behavior for fullerene C20 inside the icosahedral outer shell of C240  

NASA Astrophysics Data System (ADS)

In this work, we study the behavioral regularity of fullerene C20 inside the icosahedral outer shell of fullerene C240. The feature of such two-shell fullerenes is that the internal fullerene will move at low temperatures in a certain way: between the potential wells. The aim of this work is to reveal the regularities for motion of small fullerenes in nanospace of large external icosahedral fullerene, including the identification of the spatial configuration for a multi-well potential of interaction between two objects and prediction of possible movement for the internal object between potential wells. For the fullerene C20 it was found twenty potential wells in the direction of the fifth order axes for icosahedron of fullerene C240 cage, thirty towards in the direction of the middle of the ribs and twenty potential wells towards centers of the faces of the icosahedron. The prediction of possible moving for the internal object between potential wells and the regularities of this movement were made based on the relief analysis of the interaction energy surface of fullerenes. The numerical simulation of C20 motion in the field of C240 was carried out to test the prediction of movement. As results of the experiment, it was found that the fullerene C20 is easy to jump between the potential wells even at low temperatures up to 300K. Molecular dynamics simulations confirmed our conclusions about regularities of C20 movement between potential wells. Thus, one can conclude that the analysis of the topology of the energy surface of van der Waals interaction between the components of nanoparticles gives a true predictive picture of the regularities of the internal molecule behavior. Probably, the phenomenon of fullerene C20 movement in a cell of another fullerene can be used in modern technologies, such as determining a local temperature by increase of jumping velocity.

Glukhova, O. E.; Kolesnikova, A. S.; Slepchenkov, M. M.; Shunaev, V. V.

2014-05-01

15

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

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.

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

16

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

Microsoft Academic Search

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

Eiji Fukui; Katsuji Uemura; Masao Kobayashi

2000-01-01

17

GSH 91.5+2-114: A large H i shell in the outer part of the Galaxy  

NASA Astrophysics Data System (ADS)

GSH 91.5+2-114 is a large H i shell located in the outer Galaxy at a kinematic distance of about 15 kpc. It was first identified in the Canadian Galactic Plane Survey (CGPS) by Pineault et al. (2002, ASP Conf. Ser., 276, 332) as being possibly associated with objects possessing infrared colors, which indicates strong stellar winds. The H i shell has no obvious continuum counterpart in the CGPS radio images at 408 and 1420 MHz or in the IRAS images. We found no evidence for early-type massive stars, most likely as a result of the large extinction that is expected for this large distance. An analysis of the energetics and of the main physical parameters of the H i shell shows that this shell is likely the result of the combined action of the stellar winds and supernova explosions of many stars. We investigate whether a number of slightly extended regions characterized by a thermal radio continuum and located near the periphery of the H i shell could be the result of star formation triggered by the expanding shell.

Cichowolski, S.; Pineault, S.

2011-01-01

18

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

PubMed

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

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

2014-01-01

19

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)

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.

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

2011-12-01

20

Preparation of magnetic spinel ferrite core\\/shell nanoparticles: Soft ferrites on hard ferrites and vice versa  

Microsoft Academic Search

Hard\\/soft CoFe2O4\\/ZnFe2O4 and soft\\/hard ZnFe2O4\\/CoFe2O4 core\\/shell nanoparticles were prepared by combining high-temperature thermolysis of metal oxide precursors with seed-mediated growth. Magnetic properties of the core\\/shell nanoparticles were compared to those of individual CoFe2O4 and ZnFe2O4 nanoparticles of similar size prepared by the same method. The structure of the core\\/shell materials was established using a combination of X-ray and neutron powder

Ombretta Masala; Darin Hoffman; Nalini Sundaram; Katharine Page; Thomas Proffen; Gavin Lawes; Ram Seshadri

2006-01-01

21

VideoLab: Holding on by a (Hard-Shell) Thread  

NSDL National Science Digital Library

Similar in concept to spider silk, mussels use a thread-like, acellular tissue called the byssus (or âÂÂbeardâÂÂ) to anchor themselves in turbulent aqueous environments. The movie shows the musselâÂÂs foot attaching to and detaching from a surface, leaving behind an adhesive pad and rope-like byssal thread that keeps the mussel affixed to the surface. A Perspective by P.B. Messersmith reports on recent study of the chemistry of byssal thread cuticles. It highlights the importance of the catecholic amino acid dopa, which coordinates with iron to fabricate the byssus' hard-shelled cuticles.

Phillip B. Messersmith (Northwestern University;Departments of Biomedical Engineering, Materials Science and Engineering, Chemical and Biological Engineering, Chemistry of Life Processes Institute, and Institute for Bionanotechnology in Medicine)

2010-04-09

22

Collision safety of a hard-shell low-mass vehicle  

SciTech Connect

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.

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

1994-06-01

23

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

PubMed

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 EuroSID1-dummy well below current injury tolerance criteria. PMID:8011053

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

1994-06-01

24

Wrinkle-assisted linear assembly of hard-core/soft-shell particles: impact of the soft shell on the local structure.  

PubMed

This article addresses wrinkle assisted assembly of core-shell particles with hard cores and soft poly-(N-isopropylacrylamide) shells. As core materials we chose silica as well as silver nanoparticles. The assembled structures show that the soft shells act as a separator between the inorganic cores. Anisotropic alignment is found on two length scales, macroscopically guided through the wrinkle structure and locally due to deformation of the polymer shell leading to smaller inter-core separations as compared to assembly on flat substrates without confinement. The structures were analysed by means of scanning electron microscopy. Radial distribution functions are shown, clearly highlighting the impact of confinement on nearest neighbour distances and symmetry. The observed ordering is directly compared to Monte-Carlo simulations for hard-core/soft-shell particles, showing that the observed symmetries are a consequence of the soft interaction potential and differ qualitatively from a hard-sphere situation. For the silver-poly-(N-isopropylacrylamide) particles, we show UV-vis absorbance measurements revealing optical anisotropy of the generated structures due to plasmon coupling. Furthermore, the high degree of order of the assembled structures on macroscopic areas is demonstrated by laser diffraction effects. PMID:22395669

Müller, Mareen; Karg, Matthias; Fortini, Andrea; Hellweg, Thomas; Fery, Andreas

2012-04-01

25

Flexural models of trench/outer rise topography of coronae on Venus with axisymmetric spherical shell elastic plates  

NASA Technical Reports Server (NTRS)

Magellan altimetry has revealed that many coronae on Venus have trenches or moats around their peripheries and rises outboard of the trenches. This trench/outer rise topographic signature is generally associated with the tectonic annulus of the corona. Sandwell and Schubert have interpreted the trench/outer rise topography and the associated tectonic annulus around coronae to be the result of elastic bending of the Venus lithosphere (though the tectonic structures are consequences of inelastic deformation of the lithosphere). They used two-dimensional elastic plate flexure theory to fit topographic profiles across a number of large coronae and inferred elastic lithosphere thicknesses between about 15 and 40 km, similar to inferred values of elastic thickness for the Earth's lithosphere at subduction zones around the Pacific Ocean. Here, we report the results of using axisymmetric elastic flexure theory for the deformation of thin spherical shell plates to interpret the trench/outer rise topography of the large coronae modeled by Sandwell and Schubert and of coronae as small as 250 km in diameter. In the case of a corona only a few hundred kilometers in diameter, the model accounts for the small planform radius of the moat and the nonradial orientation of altimetric traces across the corona. By fitting the flexural topography of coronae we determine the elastic thickness and loading necessary to account for the observed flexure. We calculate the associated bending moment and determine whether the corona interior topographic load can provide the required moment. We also calculate surface stresses and compare the stress distribution with the location of annular tectonic features.

Moore, W.; Schubert, Gerald; Sandwell, David T.

1992-01-01

26

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

PubMed

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

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

2013-07-15

27

Geochemical Constraints On The Thickness of An Outer Water-ice Shell and Core Radius of Europa  

NASA Astrophysics Data System (ADS)

Jupiter's satellite Europa has an intermediate position among the Galilean satellites. A remarkable characteristic of Europa is the potential existence of liquid water under thin, outer icy crust that could have led to the hypothetical occurrence of primitive extraterrestrial life. Our understanding of the origin and evolution of the Galilean satellites has been strongly linked to how we understand their chemical composition and internal structure. In this study, internally consistent five-(six)-layer models of the constitution of Europa based on geophysical (the mass and moment of inertia from recent Galileo gravity measurements), geochemical (the compositions of silicate fractions of chondritic meteorites), and thermodynamic (modeling of phase relations and physical properties) constraints are constructed. Geophysically admissible thicknesses of an outer water-ice shell are limited to less than or equal to 160 km and to greater than 110 km for any model of differentiated or undifferentiated chondritic matter. Both L/LL and CM chondrite compositions match the total mass and moment of inertia value of Europa. The L/LL chondritic models give mean densities of 3.475- 3.635 g cm-3 and moment of inertia values I*=0.378-0.389 for Europa's rock-iron core (rocky mantle + central Fe-FeS-core) that are closest to the currently accepted values for Io (=3.53 g cm-3, I/MR2 =0.371-0.385, Anderson et al. 1996), while carbonaceous chondritic models yield significantly higher values. It is therefore likely that Europa inherited a significantly higher proportion of material close to the moderately oxidized L/LL type chondrites rather than to the carbonaceous chondrites. Both types of ordinary chondrites could be considered as a reasonable analogue for Europa's rock- iron core whereas an icy component (a late H2O-rich veneer?) might have been added during the accretion of the satellite in the cooling circumjovian disk. Core radii are estimated to be 480-640 km for the L/LL chondritic models with central Fe-10 wt.%S core (6.0-13.2% of Europa's rock-iron core mass); the allowed thickness of an outer water-ice shell is estimated to be 110-140 km (6.5-8.2% of Europa's total mass).

Kuskov, O.; Kronrod, V.

28

Shell hardness and compressive strength of the Eastern oyster, Crassostrea virginica, and the Asian oyster, Crassostrea ariakensis.  

PubMed

The valves of oysters act as a physical barrier between tissues and the external environment, thereby protecting the oyster from environmental stress and predation. To better understand differences in shell properties and predation susceptibilities of two physiologically and morphologically similar oysters, Crassostrea virginica and Crassostrea ariakensis, we quantified and compared two mechanical properties of shells: hardness (resistance to irreversible deformation; GPa) and compressive strength (force necessary to produce a crack; N). We found no differences in the hardness values between foliated layers (innermost and outermost foliated layers), age class (C. virginica: 1, 4, 6, 9 years; C. ariakensis: 4, 6 years), or species. This suggests that the foliated layers have similar properties and are likely composed of the same material. The compressive force required to break wet and dry shells was also not different. However, the shells of both six- and nine-year-old C. virginica withstood higher compressive force than C. virginica shells aged either one or four, and the shells of C. ariakensis at both ages studied (4- and 6-years-old). Differences in ability to withstand compressive force are likely explained by differences in thickness and density between age classes and species. Further, we compared the compressive strength of differing ages of these two species to the crushing force of common oyster predators in the Chesapeake Bay. By studying the physical properties of shells, this work may contribute to a better understanding of the mechanical defenses of oysters as well as of their predation vulnerabilities. PMID:24445443

Lombardi, Sara A; Chon, Grace D; Lee, James Jin-Wu; Lane, Hillary A; Paynter, Kennedy T

2013-12-01

29

A DETAILED KINEMATIC MAP OF CASSIOPEIA A'S OPTICAL MAIN SHELL AND OUTER HIGH-VELOCITY EJECTA  

SciTech Connect

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 Degree-Sign with respect to the plane of the sky with a -4000 to +6000 km s{sup -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 {sup 56}Ni-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 Almost-Equal-To 40 Degree-Sign.

Milisavljevic, Dan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States); Fesen, Robert A., E-mail: dmilisav@cfa.harvard.edu [6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States)

2013-08-01

30

77 FR 27054 - Notice of Approval of Clean Air Act Outer Continental Shelf Permits Issued to Shell Offshore, Inc...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Shelf Permits Issued to Shell Offshore, Inc. for the Kulluk Conical Drilling Unit AGENCY: United States...operating permit to Shell Offshore, Inc. (``Shell...operation of the Kulluk conical drilling unit in the Beaufort...

2012-05-08

31

Imprinting on empty hard gelatin capsule shells containing titanium dioxide by application of the UV laser printing technique.  

PubMed

The purpose of this study was to examine the application of ultraviolet (UV) laser irradiation to printing hard gelatin capsule shells containing titanium dioxide (TiO2) and to clarify how the color strength of the printing by the laser could be controlled by the power of the irradiated laser. Hard gelatin capsule shells containing 3.5% TiO2 were used in this study. The capsules were irradiated with pulsed UV laser at a wavelength of 355 nm. The color strength of the printed capsule was determined by a spectrophotometer as total color difference (dE). The capsules could be printed gray by the UV laser. The formation of many black particles which were agglomerates of oxygen-defected TiO2 was associated with the printing. In the relationship between laser peak power of a pulse and dE, there were two inflection points. The lower point was the minimal laser peak power to form the black particles and was constant regardless of the dosage forms, for example film-coated tablets, soft gelatin capsules and hard gelatin capsules. The upper point was the minimal laser peak power to form micro-bubbles in the shells and was variable with the formulation. From the lower point to the upper point, the capsules were printed gray and the dE of the printing increased linearly with the laser peak power. Hard gelatin capsule shells containing TiO2 could be printed gray using the UV laser printing technique. The color strength of the printing could be controlled by regulating the laser energy between the two inflection points. PMID:23786207

Hosokawa, Akihiro; Kato, Yoshiteru; Terada, Katsuhide

2014-08-01

32

The development of a sensitive methodology to characterise hard shell capsule puncture by dry powder inhaler pins.  

PubMed

In order for hard-shell capsules to function effectively as drug reservoirs in dry powder inhalers, the capsule must be punctured with sharpened pins to release the powdered medicament upon inspiration. Capsule performance in this setting is poorly understood. This study aims to develop a methodology to characterise hard shell capsule penetration by needles from commercial dry powder inhalers, to determine whether changes to capsule materials impact on their performance. Two pin types from two commercial dry powder inhalers were mounted in a material-testing machine, equipped with a 500 N load cell. A stainless steel bush was used to secure a capsule directly below the steel pin. Hypromellose (n=10) and gelatin capsules (n=10) were conditioned in 'normal' or low humidity conditions and were subsequently punctured with both types of pin. Each puncture event was recorded on a load-displacement curve. The force required for puncture was 2.82±0.26 N for hypromellose capsules and 4.54±0.26 N for gelatin capsules, stored in normal humidity. Different capsule materials possessed distinguishable signature profiles but repeated force-displacement profiles were highly reproducible i.e. intra-individual variability was minimal. A rapid, robust yet sensitive methodology has therefore been developed that is able to characterise hard shell capsule materials based on the puncture performance. PMID:23965433

Torrisi, Barbara M; Birchall, James C; Jones, Brian E; Díez, Fernando; Coulman, Sion A

2013-11-18

33

77 FR 3771 - Notice of Issuance of Final Outer Continental Shelf Air Permit for Shell Offshore, Inc.  

Federal Register 2010, 2011, 2012, 2013, 2014

...Shelf Air Permit for Shell Offshore, Inc. AGENCY: Environmental...OCS) air permit for Shell Offshore, Inc. (Shell). This permit...from one of three deepwater drilling vessels (the Transocean Deepwater...vessels to conduct exploratory drilling for up to 150 days per...

2012-01-25

34

Migration of Salmonella Enteritidis PT 30 through almond hulls and shells  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of Salmonella to migrate from an external aqueous environment through the almond hull and shell, and to colonize the kernel, was evaluated in two ways. First, the outer surface of shell halves from five varieties of almonds that differed in shell hardness were placed in contact with a s...

35

On The Relationship Between Cross L-shell Pc5 ULF Wave Power and Relativistic Electron Flux Enhancements In The Outer Radiation Belt  

NASA Astrophysics Data System (ADS)

Recent research has highlighted the possibility that large-amplitude ULF pulsations may act as an acceleration mechanism for generating relativistic electron populations in the outer zone magnetosphere. We examine solar wind characteristics, Pc5 ULF wave power and outer magnetospheric measurements of high energy electron flux dur- ing the recurrent fast solar wind speed streams which occurred during the first half of 1995. We find a close correlation between extended intervals of significant pulsation power and GOES7 observations of enhanced relativistic (> 2 MeV) electron flux in the outer zone magnetosphere, suggesting that these two features may be causally re- lated. We demonstrate that significant electron flux increases at geosynchronous orbit are only observed in response to ULF wave power which is sustained at high lev- els over a number of days following storm onset. Further, using data from the STRV microsatellites, we examine the evolution of cross L-shell ULF wave power and rel- ativistic (> 750 keV) electron flux from L = 3.75 to L = 6.79. We find that for specific events, the fluxes in these fixed energy detectors can rise across the whole of this L-shell range. In contrast, ULF wave power increases with increasing L-shell, and is typically an order of magnitude higher at L = 6.6 than at L = 4. Our obser- vations suggest that ULF pulsations may play a role in the acceleration mechanism for generating MeV energy "killer" electrons in the magnetosphere, particularly at geosyncronous orbit. Further research should examine in detail the relationship be- tween ULF wave power and MeV energy electron flux rises in the heart of the outer radiation belts around L 4.

Mann, I. R.; Mathie, R. A.; Iles, R. H. A.; Fazakerley, A. N.

36

Thermodynamic functions and phase diagram of water and high-pressure ices: Implication to an outer water-ice shell of Ganymede  

NASA Astrophysics Data System (ADS)

Water and water ice are important components of many space objects. Astrophysical and spectroscopic research shows that Solar system giant planets' satellites (Europa, Ganymede, Callisto, Titan & Enceladus), small transneptunian planets, asteroids and comets contain considerable amount of water and ice. «Galileo» and «Cassini-Huygens» missions show that liquid water could possibly exist under outer ice shells of Jupiter and Saturn satellites. Water oceans also hypothetically exist on Triton, Pluton and icy objects of Kuiper belt. Phase composition numerical modeling is the main method of internal structure and chemical evolution research for mentioned objects. Available physicochemical models of icy satellites' internal structure are based on geophysical and geochemical data obtained by space missions on one hand, and on thermodynamic data and equations of state on considered minerals and water phases on the other. This research attempts to summarize experimental and theoretical data on water and ices Ih, II, III, V, VI, VII, VIII, X phase diagram and their thermodynamic properties. Based on mathematical processing of equations of state for high-pressure ices and experimental data on phase transitions in water-ices system, phase equilibrium is being modeled and thermodynamic functions values (Gibbs free energy, enthalpy, entropy and volume change) for most phase transitions are computed. Based on geophysical (mass and moment of inertia from recent Galileo gravity measurements), geochemical (composition of chondrites) and thermodynamic (phase diagram of water and ices) constraints internally consistent models of Ganymede constitution are built. Total thickness of an outer water-ice shell of Ganymede is estimated.

Antsyshkin, Dmitry; Dunaeva, Anna; Kuskov, Oleg

2010-05-01

37

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

USGS Publications Warehouse

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

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

1995-01-01

38

An in vitro investigation of the suitability of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) and hydrophobic additives in the outer shell for colon targeting.  

PubMed

To develop a new colon targeting formulation, which can suppress drug release completely during 12 h in the stomach and release the drug rapidly after a lag time of 3+/-1 h in the small intestine, the use of press-coated tablets with hydroxypropylmethylcellulose acetate succinate (HPMCAS) in the outer shell was investigated. The release of diltiazem hydrochloride (DIL) as a model drug contained in the core tablets in the 1st fluid (pH 1.2) was suppressed by preparing with higher compression force, but the lag time in the 2nd fluid (pH 6.8) could not exceed 1.5 h. Therefore, to improve the dissolution characteristics, the effects of addition of various hydrophobic additives to HPMCAS were examined. All of the additives examined suppressed the release rate in the 1st fluid, and prolonged the lag time in the 2nd fluid compared to HPMCAS alone. However, although none of the additives examined fulfilled all of the desired criteria, magnesium stearate (MgSt) and calcium stearate (CaSt) showed interesting effects; the former suppressed drug release completely in 1st fluid, while the latter markedly prolonged the lag time in 2nd fluid. To integrate the merits of each additive, press-coated tablets with a powder mixture of HPMCAS, MgSt and CaSt in the outer shell (HMC tablets) were prepared and in vitro tests were performed. The results indicated that HMC tablets with a mixing ratio of 80% HPMCAS, 5-15% MgSt and 15-5% CaSt in the outer shell met the desired criteria and the lag time in 2nd fluid could also be controlled from 2 to 9 h. At a mixing ratio of 80% HPMCAS, 10% MgSt and 10% CaSt, the dissolution profiles of DIL in 1st fluid and 2nd fluid were not remarkably affected by agitation intensity, and addition of bile salts, pretreatment time or anticipated higher pH except for pH 6.0, respectively. These results indicated the usefulness of HMC tablets with the desirable functions for colon-targeting formulations. PMID:11166411

Fukui, E; Miyamura, N; Kobayashi, M

2001-01-29

39

Torques on the Inner and Outer Spheres Induced by the Boussinesq Thermal Convection in a Rotating Spherical Shell  

NASA Astrophysics Data System (ADS)

We investigate the directions and amplitudes of torques on the inner and outer spheres induced by the stable finite-amplitude traveling wave solutions which bifurcate supercritically at the critical points and have four-fold symmetry in the azimuthal direction under the impermeable, no-slip and fixed-temperature boundary conditions. The ratio ratio of inner and outer radii ?=0.4 and the Prandtl number P=1, while the Taylor number is varied from 522 to 5002 and the Rayleigh number is from about Rc to 1.2-2Rc, where Rc is the critical Rayleigh number. It is shown that the direction of the torque on the inner sphere is prograde at small Taylor numbers, while it becomes retrograde at large Taylor numbers. Weakly nonlinear analyses show that the nonlinear term in the energy equation is most effective to generate the global distribution of mean zonal flows, however, the azimuthal component of the nonlinear term in the Navier--Stokes equation becomes most important for generation of the torque on the inner sphere at large Taylor numbers.

Kimura, Keiji; Takehiro, Shin-ichi; Yamada, Michio

2012-08-01

40

7 CFR 51.2289 - Shell.  

Code of Federal Regulations, 2013 CFR

...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...

2013-01-01

41

7 CFR 51.2289 - Shell.  

Code of Federal Regulations, 2014 CFR

...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...

2014-01-01

42

7 CFR 51.2289 - Shell.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

43

7 CFR 51.2289 - Shell.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

44

7 CFR 51.2289 - Shell.  

Code of Federal Regulations, 2010 CFR

...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...

2010-01-01

45

On The Relationship Between Cross L-shell Pc5 ULF Wave Power and Relativistic Electron Flux Enhancements In The Outer Radiation Belt  

Microsoft Academic Search

Recent research has highlighted the possibility that large-amplitude ULF pulsations may act as an acceleration mechanism for generating relativistic electron populations in the outer zone magnetosphere. We examine solar wind characteristics, Pc5 ULF wave power and outer magnetospheric measurements of high energy electron flux dur- ing the recurrent fast solar wind speed streams which occurred during the first half of

I. R. Mann; R. A. Mathie; R. H. A. Iles; A. N. Fazakerley

2002-01-01

46

Ocean acidification alters the material properties of Mytilus edulis shells.  

PubMed

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

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

2015-02-01

47

Anti-Inflammatory Activity and Mechanism of a Lipid Extract from Hard-Shelled Mussel (Mytilus Coruscus) on Chronic Arthritis in Rats  

PubMed Central

The present study was designed to investigate the anti-inflammatory activity and mechanism of a lipid extract from hard-shelled mussel (Mytilus coruscus) on adjuvant-induced (AIA) and collagen-induced arthritis (CIA) in rats. AIA and CIA rats that received hard-shelled mussel lipid extract (HMLE group) at a dose of 100 mg/kg demonstrated significantly lower paw swelling and arthritic index, but higher body weight gain than those which received olive oil (control group). Similar results were found in arthritic rats that received New Zealand green-lipped mussel lipid extract (GMLE) at the same dosage. The levels of leukotriene B4 (LTB4), prostaglandin E2 (PGE2), thromboxane B2 (TXB2) in the serum, and interleukin-1? (IL-1?), IL-6, interferon-? (INF-?), tumor necrosis factor-? (TNF-?) in the ankle joint synovial fluids of HMLE group rats were significantly lower than those of control group. However, the levels of IL-4 and IL-10 in HMLE group rats were significantly higher than those in the control group. Decreased mRNA expressions of matrix metalloproteinase 1 (MMP1) and MMP13, but increased tissue inhibitor of metalloproteinase 1 (TIMP1) were observed in the knee joint synovium tissues of HMLE group rats when compared with the control group. No hepatotoxicity was observed in both HMLE and GMLE group rats. The present results indicated that HMLE had a similarly strong anti-inflammatory activity as GMLE. Such a strong efficacy could result from the suppression of inflammatory mediators (LTB4, PGE2, TXB2), pro-inflammatory cytokines (IL-1?, IL-6, INF-?, TNF-?) and MMPs (MMP1, MMP13), and the promotion of anti-inflammatory cytokines (IL-4, IL-10) and TIMPs (TIMP1) productions. PMID:24473164

Li, Guipu; Fu, Yuanqing; Zheng, Jusheng; Li, Duo

2014-01-01

48

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

PubMed Central

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

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

2015-01-01

49

Hard?to?cook phenomenon in legumes  

Microsoft Academic Search

Hard?to?cook legumes (HTCL) have been observed for centuries. Different types of HTCL are recognized in freshly harvested crops or are developed during storage. Two types of hard shell, which is due to seed coat impermeability to water, are identified: (1) the reversible hard shell that occurs in freshly harvested seeds and disappear during storage; (2) the other type is the

1992-01-01

50

Inner shell radial pin geometry and mounting arrangement  

DOEpatents

Circumferentially spaced arrays of support pins are disposed through access openings in an outer turbine shell and have projections received in recesses in forward and aft sections of an inner turbine shell supported from the outer shell. The projections have arcuate sides in a circumferential direction affording line contacts with the side walls of the recesses and are spaced from end faces of the recesses, enabling radial and axial expansion and contraction of the inner shell relative to the outer shell. All loads are taken up in a tangential direction by the outer shell with the support pins taking no radial loadings.

Leach, David (Niskayuna, NY); Bergendahl, Peter Allen (Scotia, NY)

2002-01-01

51

Thick-shell nanocrystal quantum dots  

DOEpatents

Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

Hollingsworth, Jennifer A. (Los Alamos, NM); Chen, Yongfen (Eugene, OR); Klimov, Victor I. (Los Alamos, NM); Htoon, Han (Los Alamos, NM); Vela, Javier (Los Alamos, NM)

2011-05-03

52

Relativistic electron drift shell splitting  

Microsoft Academic Search

A survey of equatorial outer radiation belt relativistic electron pitch angle distributions measured on the Polar satellite shows anisotropies that are consistent with the effects of drift shell splitting. Simulations based on the observed radial intensity gradients and on drift shell calculations in a magnetospheric field model show that for low geomagnetic activity levels, the measured average anisotropies are similar

R. S. Selesnick; J. B. Blake

2002-01-01

53

The outer solar system.  

NASA Technical Reports Server (NTRS)

Review of approaches to exploration of the outer solar system beyond the asteroid belt as seen from reports of JPL scientific groups. The topics include the cosmogonic aspects of outer solar system exploration, the satellites of the outer planets, their atmospheres, dynamics and magnetism, and the outer solar wind.

Cameron, A. G. W.

1973-01-01

54

Removable inner turbine shell with bucket tip clearance control  

DOEpatents

A turbine includes a plurality of inner shell sections mounting first and second stage nozzle and shroud portions. The inner shell sections are pinned to an outer containment shell formed of sections to preclude circumferential movement of the inner shell relative to the outer shell and enable thermal expansion and contraction of the inner shell relative to the outer shell. Positive bucket tip clearance control is afforded by passing a thermal medium about the inner shell in heat transfer relation with the shrouds about the first and second stage bucket tips, the thermal medium being provided from a source of heating/cooling fluid independent of the turbine. Access is provided to the rotor and turbine buckets by removing the outer and inner shell sections.

Sexton, Brendan F. (Clifton Park, NY); Knuijt, Hans M. (Niskayuna, NY); Eldrid, Sacheverel Q. (Saratoga Springs, NY); Myers, Albert (Amsterdam, NY); Coneybeer, Kyle E. (Schenectady, NY); Johnson, David Martin (Ballston Lake, NY); Kellock, Iain R. (Clifton Park, NY)

2000-01-01

55

Inner and outer ear anatomy  

NSDL National Science Digital Library

Sounds are actually waves from vibrations. The outer ear catches these waves and funnels them down into the inner ear. The waves reach the eardrum and in turn make the eardrum vibrate. Three small bones receive these vibrations next, then a snail shell-shaped structure called the cochlea. The cochlea is filled with liquid, and this liquid stimulates hairs inside the inner ear. The hairs transmit the signal to the auditory nerve where the signal is taken to the brain and processed as sound.

Zina Deretsky (National Science Foundation; )

2006-10-23

56

Optimum rotationally symmetric shells for flywheel rotors  

DOEpatents

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.

Blake, Henry W. (Oak Ridge, TN)

2000-01-01

57

Bio-relevant dissolution testing of hard capsules prepared from different shell materials using the dynamic open flow through test apparatus.  

PubMed

Current compendial dissolution and disintegrating testing is unable to mimic physiological conditions affecting gastric drug release from immediate release dosage forms. In order to obtain more realistic data, a novel test setup was developed that we term a 'dynamic open flow through test apparatus'. It is based on the previously described dissolution stress test device and attempts to simulate the intra-gastric dissolution conditions pertinent to immediate release dosage forms administered under fasting conditions with respect to flow rates, intra-gastric temperature profiles and gastric motility. The concept of the dynamic open flow through test apparatus has been tested using five different types of hard capsules: conventional hard gelatin capsules (HGC), three hypromellose based capsules (Vcaps, Vcaps Plus and DRcaps) and pullulan based capsules (Plantcaps). These were of different sizes but all contained 100mg caffeine in each formulation, adjusted to avoid buoyancy by addition of excipient. When the capsules were stressed in the apparatus under the dynamic flow conditions applying mild pressure simulating gastric motility, release from release from Vcaps Plus, Vcaps and Plantcaps capsules was very well comparable to HGC. Capsules are usually swallowed with cold water and the temperature dependency of release from gelatin was noted as a significant factor, since heat exchange in the stomach is slow. PMID:24021609

Garbacz, Grzegorz; Cadé, Dominique; Benameur, Hassan; Weitschies, Werner

2014-06-16

58

Method to produce large, uniform hollow spherical shells  

DOEpatents

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.

Hendricks, Charles D. (Livermore, CA)

1985-01-01

59

Folding and buckling pathways in spherical shells with soft spots  

NASA Astrophysics Data System (ADS)

Thin elastic spherical shells subject to an external pressure undergo a buckling transition when the pressure reaches a critical value. Past the buckling instability, the shell typically takes on a shape with one or more inversions that focus the elastic deformation energy within narrow circular regions on the sphere. These inversions are associated with large volume changes and hysteresis, and their location is highly sensitive to very slight imperfections in the sphere. Recently, it has been demonstrated [1] that natural pollen grains have evolved soft sectors in their hard outer walls which guide them toward particular folding pathways when their internal volume is reduced due to dessication, thus avoiding sudden and uncontrolled changes in shape. Motivated by these results, we study the effect of circular soft spots on the buckling of otherwise uniform spherical shells. Through a combination of scaling arguments and numerical simulations, we demonstrate that the shell can be tuned to follow distinct buckling pathways by varying the size and stiffness of the soft spot. [1] E. Katifori et al, Proc. Natl. Acad. Sci. USA 107, 7635 (2010)

Paulose, Jayson; Nelson, David

2012-02-01

60

Outer planet satellites  

NASA Technical Reports Server (NTRS)

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.

Schenk, Paul M.

1991-01-01

61

Different shells  

NSDL National Science Digital Library

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.

N/A N/A (None; )

2007-08-22

62

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

PubMed

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, D(t) and D(r). 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. PMID:22423856

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

2012-03-14

63

Sound Transmission through Two Concentric Cylindrical Sandwich Shells  

NASA Technical Reports Server (NTRS)

This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

64

Outer planet satellites  

SciTech Connect

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.

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

1991-01-01

65

Method of fabricating nested shells and resulting product  

DOEpatents

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.

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

1982-01-01

66

hard-core 1st shell  

E-print Network

: unveiling the rules of collec7ve animal behavior A Cavagna, A Cimarelli, I Giardina, A Procaccini Arxiv preprint arXiv:0802.1674312008 Interac7on ruling animal collec7ve behavior, 1491-1510 Large-scale behaviour in animal groups A Cavagna, I Giardina

Turner, Matthew

67

? Carinae - The outer ejecta  

NASA Astrophysics Data System (ADS)

? Carinae is a unique object among the most massive evolved stars in the LBV phase. The central object(s) is(are) surrounded by a complex circumstellar nebula ejected during more than one eruption in the 19th century. Beyond the well-defined edges of its famous bipolar nebula, the Homunculus, are additional nebulous features referred to as the outer ejecta. The outer ejecta contains a large variety of structures of very different sizes and morphologies distributed in a region 0.67 pc in diameter. Individual features in the outer ejecta are moving extremely fast, up to 3200 km/s, in general the expansion velocities are between 400-900 km/s. A consequence of these high velocities is that structures in the outer ejecta interact with the surrounding medium and with each other. The strong shocks that arise from these interactions give rise to soft X-ray emission. The global expansion pattern of the outer ejecta reveals an overall bipolar distribution, giving a symmetric structure to its morphologically more irregular appearance. The long, highly collimated filaments, called strings, are particularly unusual. The material in the strings follows a Hubble-flow and appears to originate at the central object.

Weis, K.

2009-03-01

68

Large Ultrathin Shelled Drops Produced via Non-Confined Microfluidics.  

PubMed

We present a facile approach for producing large and monodisperse core-shell drops with ultrathin shells using a single-step process. A biphasic compound jet is introduced into a quiescent third (outer) phase that ruptures to form core-shell drops. Ultrathin shelled drops could only be produced within a certain range of surfactant concentrations and flow rates, highlighting the effect of interfacial tension in engulfing the core in a thin shell. An increase in surfactant concentrations initially resulted in drops with thinner shells. However, the drops with thinnest shells were obtained at an optimum surfactant concentration, and a further increase in the surfactant concentrations increased the shell thickness. Highly monodisperse (coefficient of variation smaller than 3?%) core-shell drops with diameter of ?200 ?m-2 mm with shell thickness as small as ?2 ?m were produced. The resulting drops were stable enough to undergo polymerisation and produce ultrathin shelled capsules. PMID:25382308

Chaurasia, Ankur S; Josephides, Dimitris N; Sajjadi, Shahriar

2015-02-01

69

Saturn's outer magnetosphere  

NASA Technical Reports Server (NTRS)

Similarities between the Saturnian and terrestrial outer magnetosphere are examined. Saturn, like Earth, has a fully developed magnetic tail, 80 to 100 RS in diameter. One major difference between the two outer magnetospheres is the hydrogen and nitrogen torus produced by Titan. This plasma is, in general, convected in the corotation direction at nearly the rigid corotation speed. Energies of magnetospheric particles extend to above 500 keV. In contrast, interplanetary protons and ions above 2 MeV have free access to the outer magnetosphere to distances well below the Stormer cutoff. This access presumably occurs through the magnetotail. In addition to the H+, H2+, and H3+ ions primarily of local origin, energetic He, C, N, and O ions are found with solar composition. Their flux can be substantially enhanced over that of interplanetary ions at energies of 0.2 to 0.4 MeV/nuc.

Schardt, A. W.; Behannon, K. W.; Carbary, J. F.; Eviatar, A.; Lepping, R. P.; Siscoe, G. L.

1983-01-01

70

Core-shell nanostructured catalysts.  

PubMed

Novel nanotechnologies have allowed great improvements in the syn-thesis of catalysts with well-controlled size, shape, and surface properties. Transition metal nanostructures with specific sizes and shapes, for instance, have shown great promise as catalysts with high selectivities and relative ease of recycling. Researchers have already demonstrated new selective catalysis with solution-dispersed or supported-metal nanocatalysts, in some cases applied to new types of reactions. Several challenges remain, however, particularly in improving the structural stability of the catalytic active phase. Core-shell nanostructures are nanoparticles encapsulated and protected by an outer shell that isolates the nanoparticles and prevents their migration and coalescence during the catalytic reactions. The synthesis and characterization of effective core-shell catalysts has been at the center of our research efforts and is the focus of this Account. Efficient core-shell catalysts require porous shells that allow free access of chemical species from the outside to the surface of nanocatalysts. For this purpose, we have developed a surface-protected etching process to prepare mesoporous silica and titania shells with controllable porosity. In certain cases, we can tune catalytic reaction rates by adjusting the porosity of the outer shell. We also designed and successfully applied a silica-protected calcination method to prepare crystalline shells with high surface area, using anatase titania as a model system. We achieved a high degree of control over the crystallinity and porosity of the anatase shells, allowing for the systematic optimization of their photocatalytic activity. Core-shell nanostructures also provide a great opportunity for controlling the interaction among the different components in ways that might boost structural stability or catalytic activity. For example, we fabricated a SiO?/Au/N-doped TiO? core-shell photocatalyst with a sandwich structure that showed excellent catalytic activity for the oxidation of organic compounds under UV, visible, and direct sunlight. The enhanced photocatalytic efficiency of this nanostructure resulted from an added interfacial nonmetal doping, which improved visible light absorption, and from plasmonic metal decoration that enhanced light harvesting and charge separation. In addition to our synthetic efforts, we have developed ways to evaluate the accessibility of reactants to the metal cores and to characterize the catalytic properties of the core-shell samples we have synthesized. We have adapted infrared absorption spectroscopy and titration experiments using carbon monoxide and other molecules as probes to study adsorption on the surface of metal cores in metal oxide-shell structures in situ in both gas and liquid phases. In particular, the experiments in solution have provided insights into the ease of diffusion of molecules of different sizes in and out of the shells in these catalysts. PMID:23268644

Zhang, Qiao; Lee, Ilkeun; Joo, Ji Bong; Zaera, Francisco; Yin, Yadong

2013-08-20

71

Active control of radiated noise from a cylindrical shell using external piezoelectric panels  

E-print Network

Control architectures and methodologies are developed for the reduction of radiated noise from a thick-walled cylindrical shell using external piezoelectric panels. The proposed approach is to cover the shell's outer surface ...

Song, Kyungyeol, 1972-

2002-01-01

72

DIFFUSION OF PROTONS IN THE OUTER RADIATION BELT  

Microsoft Academic Search

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

M. P. Nakada; G. D. Mead

1965-01-01

73

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

74

Turbine blade with spar and shell  

DOEpatents

A turbine blade with a spar and shell construction in which the spar and the shell are both secured within two platform halves. The spar and the shell each include outward extending ledges on the bottom ends that fit within grooves formed on the inner sides of the platform halves to secure the spar and the shell against radial movement when the two platform halves are joined. The shell is also secured to the spar by hooks extending from the shell that slide into grooves formed on the outer surface of the spar. The hooks form a serpentine flow cooling passage between the shell and the spar. The spar includes cooling holes on the lower end in the leading edge region to discharge cooling air supplied through the platform root and into the leading edge cooling channel.

Davies, Daniel O. (Palm City, FL); Peterson, Ross H. (Loxahatchee, FL)

2012-04-24

75

Outer Planet Icy Satellites  

NASA Technical Reports Server (NTRS)

An outer planet icy satellite is any one of the celestial bodies in orbit around Jupiter, Saturn, Uranus, Neptune, or Pluto. They range from large, planet-like geologically active worlds with significant atmospheres to tiny irregular objects tens of kilometers in diameter. These bodies are all believed to have some type of frozen volatile, existing alone or in combination with other volatiles.

Buratti, B.

1994-01-01

76

Lunch in Outer Space!  

NSDL National Science Digital Library

Students learn about the unique challenges astronauts face while eating in outer space. They explore different food choices and food packaging. Students learn about the engineering design process, and then, as NASA engineering teams, they design and build original model devices to help astronauts eat in a microgravity environment --- their own creative devices for food storage and meal preparation.

Integrated Teaching And Learning Program

77

Sound Radiation from a Finite FGM Cylindrical Shell Covered with a Compliant Layer  

Microsoft Academic Search

The characteristics of vibration and sound radiation from a finite FGM cylindrical shell with the outer shell coated with compliant layer are systematically studied. The shell's motion function is expressed by FGM shell motion, whereas the layer motion is described by means of the three-dimensional Navier equations whose displacement solutions are expressed by Taylor expansion along the layer thickness. The

Buqing Xu; Shaopu Yang; Haoyu Li

2008-01-01

78

Interior remodeling of the shell by a gastropod mollusc  

PubMed Central

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

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

1979-01-01

79

Outer Solar System Exploration  

E-print Network

are similar to Uranus and Neptune #12;Oh the Places we'll Go · The outer solar system is target-rich. We'd like to learn more about volcanoes on Io, storms on Titan, the rings around Uranus and whether Ariel ocean and how to access it in the future ­ Uranus orbiter, to study an ice giant in our own solar system

Rathbun, Julie A.

80

The leptospiral outer membrane.  

PubMed

The outer membraneOuter membrane (OM) is the front line of leptospiral interactions with their environment and the mammalian host. Unlike most invasive spirochetes, pathogenic leptospires must be able to survive in both free-living and host-adapted states. As organisms move from one set of environmental conditions to another, the OM must cope with a series of conflicting challenges. For example, the OM must be porous enough to allow nutrient uptake, yet robust enough to defend the cell against noxious substances. In the host, the OM presents a surface decorated with adhesins and receptors for attaching to, and acquiring, desirable host molecules such as the complement regulator, Factor H.Factor H. On the other hand, the OM must enable leptospires to evade detection by the host's immune system on their way from sites of invasion through the bloodstream to the protected niche of the proximal tubule. The picture that is emerging of the leptospiral OM is that, while it shares many of the characteristics of the OMs of spirochetes and Gram-negative bacteria, it is also unique and different in ways that make it of general interest to microbiologists. For example, unlike most other pathogenic spirochetes, the leptospiral OM is rich in lipopolysaccharideLipopolysaccharide (LPS). Leptospiral LPS is similar to that of Gram-negative bacteria but has a number of unique structural features that may explain why it is not recognized by the LPS-specific Toll-like receptor 4Toll-like receptor 4 of humans. As in other spirochetes, lipoproteins are major components of the leptospiral OM, though their roles are poorly understood. The functions of transmembrane outer membrane proteins (OMPs) in many cases are better understood, thanks to homologies with their Gram-negative counterparts and the emergence of improved genetic techniques. This chapter will review recent discoveries involving the leptospiral OM and its role in leptospiral physiology and pathogenesis. PMID:25388136

Haake, David A; Zückert, Wolfram R

2015-01-01

81

Outer Solar System Nomenclature  

NASA Technical Reports Server (NTRS)

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.

Owen, Tobias C.

1998-01-01

82

Outer planets satellites  

NASA Technical Reports Server (NTRS)

The present investigation takes into account the published literature on outer planet satellites for 1979-1982. It is pointed out that all but three (the moon and the two Martian satellites) of the known planetary satellites are found in the outer solar system. Most of these are associated with the three regular satellite systems of Jupiter, Saturn, and Uranus. The largest satellites are Titan in the Saturn system and Ganymede and Callisto in the Jupiter system. Intermediate in size between Mercury and Mars, each has a diameter of about 5000 km. Presumably each has an internal composition about 60 percent rock and 40 ice, and each is differentiated with a dense core extending out about 75 percent of the distance to the surface, with a mantle of high-pressure ice and a crust of ordinary ice perhaps 100 km thick. Attention is also given to Io, Europa, the icy satellites of Saturn, the satellites of Uranus, the small satellites of Jupiter and Saturn, Triton and the Pluto system, and plans for future studies.

Morrison, D.

1983-01-01

83

Snail Shell  

USGS Multimedia Gallery

Plant seems to be a Heliotropum sp. Huge snail shells litter the wetland around Asuncion Bay. Near 25°15’49’’S, 57°37’47’’W. La plantita detrás del caracol parece ser un Heliotropium sp., Boraginaceae....

84

Acoustic radiation from single and double ribbed circular cylindrical shells  

NASA Astrophysics Data System (ADS)

Measurements of the acoustic radiation from single and double ribbed circular cylindrical shells were made on the NUSC Transducer Calibration Platform (TCP) in Lake Seneca, NY. Six different types of mechanical drives were used at each of three locations inside the inner shell. Measurements of the shell vibration and acoustic radiation were made with and without outer shells installed around the inner shell structure. For two types of drives, measurements were made with a pressure release layer installed between the inner and outer shell surfaces. Acoustic radiation measurements were made as a function of frequency from 20 to 5,000 Hz and as a function of observation direction at several frequencies for each shell and drive measurement configuration. Measured acoustic radiation data as a function of frequency have been processed. Analysis of the processed data is presented and discussed. It is shown that the location of the drive had a significant effect on the acoustic radiation. The outer shell reduced the acoustic radiation at shell resonant frequencies, but had little effect on other frequencies. The pressure release layer in the double shell had little effect on the acoustic radiation.

Burroughs, C. B.; Hayek, S. I.; Hallander, J. E.; Bostian, D. A.

1984-03-01

85

Standard hardness conversion tables for metals relationship among brinell hardness, vickers hardness, rockwell hardness, superficial hardness, knoop hardness, and scleroscope hardness  

E-print Network

1.1 Conversion Table 1 presents data in the Rockwell C hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.2 Conversion Table 2 presents data in the Rockwell B hardness range on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, Knoop hardness, and Scleroscope hardness of non-austenitic steels including carbon, alloy, and tool steels in the as-forged, annealed, normalized, and quenched and tempered conditions provided that they are homogeneous. 1.3 Conversion Table 3 presents data on the relationship among Brinell hardness, Vickers hardness, Rockwell hardness, Rockwell superficial hardness, and Knoop hardness of nickel and high-nickel alloys (nickel content o...

American Society for Testing and Materials. Philadelphia

2007-01-01

86

Energetic particle drift motions in the outer dayside magnetosphere  

SciTech Connect

Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which mark the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs.

Buck, R.M.

1987-12-01

87

Nanostructured shells DOI: 10.1002/smll.200600098  

E-print Network

Nanostructured shells DOI: 10.1002/smll.200600098 SiC-Shell Nanostructures Fabricated by Replicating ZnO Nano-objects: A Technique for Producing Hollow Nanostructures of Desired Shape** Jun Zhou, Jin nanostructures have important applications due to their large outer and inner surfaces, as well as cavity

Wang, Zhong L.

88

Defect coalescence in spherical nematic shells.  

PubMed

We study coalescence of topological defects in nematic liquid crystals confined to spherical shells using both experiments and computer simulations. We observe that the four s=+1/2 defects that are present due to topological constraints imposed by the spherical geometry coalesce by pairs after changing the molecular orientation at the outer surface from tangential to perpendicular; the result is the formation of two single s=+1 defects. It is noteworthy that the speed of the coalescence process is peaked when the defects are at opposite points on the equator of the shell; this maximum results from the thickness inhomogeneity of the shells. PMID:23030858

Lopez-Leon, Teresa; Bates, Martin A; Fernandez-Nieves, Alberto

2012-09-01

89

Probabilistic Dynamic Buckling of Smart Composite Shells  

NASA Technical Reports Server (NTRS)

A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of intraply hybrid composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right next to the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

Chamis, Christos C.; Abumeri, Galib H.

2007-01-01

90

Probabilistic Dynamic Buckling of Smart Composite Shells  

NASA Technical Reports Server (NTRS)

A computational simulation method is presented to evaluate the deterministic and nondeterministic dynamic buckling of smart composite shells. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 10 percent at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load while uncertainties in the electric field strength and smart material volume fraction have moderate effects. For the specific shell considered in this evaluation, the use of smart composite material is not recommended because the shell buckling resistance can be improved by simply re-arranging the orientation of the outer plies, as shown in the dynamic buckling analysis results presented in this report.

Abumeri, Galib H.; Chamis, Christos C.

2003-01-01

91

Strategy for outer planets exploration  

NASA Technical Reports Server (NTRS)

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.

1975-01-01

92

Photochemistry of carbon-rich circumstellar shells  

Microsoft Academic Search

The effect of ambient ultraviolet photons on the chemical structure of carbon-rich, circumstellar envelopes is investigated with a simple formulation of the time-dependent, photochemical rate equations valid for optically thick shells. Molecules injected into the shielded inner envelope are broken down when they reach the outer regions where ambient ultraviolet photons can penetrate. A quantitative description of the abundance variations

P. J. Huggins; A. E. Glassgold

1982-01-01

93

CORNER OF SUBPILE ROOM: NORTH AND EAST SIDES. STEEL OUTER ...  

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

CORNER OF SUBPILE ROOM: NORTH AND EAST SIDES. STEEL OUTER SHELL HAS BEEN AFFIXED. SIGN SAYS "HERRICK IRON WORKS STEEL, OAKLAND, CALIFORNIA." NOTE CONDUIT FOR FUTURE INSTRUMENTATION. TOP OF STEEL CASE WILL BE LEVEL WITH BASEMENT CEILING. CAMERA FACES SOUTHEAST. INL NEGATIVE NO. 734. Unknown Photographer, 10/6/1950 - Idaho National Engineering Laboratory, Test Reactor Area, Materials & Engineering Test Reactors, Scoville, Butte County, ID

94

Synthesis of monodisperse hollow carbon nanocapsules by using protective silica shells.  

PubMed

Monodisperse hollow carbon nanocapsules (<200 nm) with mesoporous shells were synthesized by coating their outer shells with silica to prevent aggregation during their high-temperature annealing. Monodispersed silica nanoparticles were used as starting materials and octadecyltrimethoxysilane (C18TMS) was used as a carbon source to create core-shell nanostructures. These core-shell nanoparticles were coated with silica on their outer shell to form a second shell layer. This outer silica shell prevented aggregation during calcination. The samples were characterized by TEM, SEM, dynamic light scattering (DLS), UV/Vis spectroscopy, and by using the Brunauer-Emmett-Teller (BET) method. The as-synthesized hollow carbon nanoparticles exhibited a high surface area (1123 m(2) g(-1)) and formed stable dispersions in water after the pegylation process. The drug-loading and drug-release properties of these hollow carbon nanocapsules were also investigated. PMID:23345002

Quan, Bo; Nam, Gi-Eun; Choi, Hyuck Jae; Piao, Yuanzhe

2013-04-01

95

The microindentation behavior of several mollusk shells  

SciTech Connect

An investigation of the relationship between structure and mechanical behavior is reported for mollusk shells employing foliated, nacreous, and crossed-lamellar structures by microindentation in the Knoop and Vickers geometries. Indentation damage zones develop crack systems that reflect the micro-architecture. For the crosed-lamellar structure, the system of cracks about the indentation normally developed in a brittle material is suppressed. Previous reports that shells are harder than the corresponding minerals, calcite and aragonite, are confirmed, but it is found that this effect can be strongly dependent on orientation. This anomalous hardness is not an artifact of the indentation test technique, since scratch tests confirm the relative hardness of shell over the mineral. It is suggested that microstructural organization is of central importance in producing this hardness, as opposed to intrinsic properties of the mineral or matrix phases. 17 refs., 6 figs., 1 tab.

Laraia, V.J.; Heuer, A.H. (Case Western Reserve Univ., Cleveland, OH (USA). Dept. of Materials Science and Engineering)

1990-01-01

96

Vibration of Shells  

NASA Technical Reports Server (NTRS)

The vibrational characteristics and mechanical properties of shell structures are discussed. The subjects presented are: (1) fundamental equations of thin shell theory, (2) characteristics of thin circular cylindrical shells, (3) complicating effects in circular cylindrical shells, (4) noncircular cylindrical shell properties, (5) characteristics of spherical shells, and (6) solution of three-dimensional equations of motion for cylinders.

Leissa, A. W.

1973-01-01

97

Building Atoms Shell by Shell.  

ERIC Educational Resources Information Center

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…

Sussman, Beverly

1993-01-01

98

Turbine airfoil with outer wall thickness indicators  

DOEpatents

A turbine airfoil usable in a turbine engine and including a depth indicator for determining outer wall blade thickness. The airfoil may include an outer wall having a plurality of grooves in the outer surface of the outer wall. The grooves may have a depth that represents a desired outer surface and wall thickness of the outer wall. The material forming an outer surface of the outer wall may be removed to be flush with an innermost point in each groove, thereby reducing the wall thickness and increasing efficiency. The plurality of grooves may be positioned in a radially outer region of the airfoil proximate to the tip.

Marra, John J; James, Allister W; Merrill, Gary B

2013-08-06

99

Method to produce large, uniform hollow spherical shells  

DOEpatents

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.

Hendricks, C.D.

1983-09-26

100

Monte Carlo simulations of nematic and chiral nematic shells  

NASA Astrophysics Data System (ADS)

We present a systematic Monte Carlo simulation study of thin nematic and cholesteric shells with planar anchoring using an off-lattice model. The results obtained using the simple model correspond with previously published results for lattice-based systems, with the number, type, and position of defects observed dependent on the shell thickness with four half-strength defects in a tetrahedral arrangement found in very thin shells and a pair of defects in a bipolar (boojum) configuration observed in thicker shells. A third intermediate defect configuration is occasionally observed for intermediate thickness shells, which is stabilized in noncentrosymmetric shells of nonuniform thickness. Chiral nematic (cholesteric) shells are investigated by including a chiral term in the potential. Decreasing the pitch of the chiral nematic leads to a twisted bipolar (chiral boojum) configuration with the director twist increasing from the inner to the outer surface.

Wand, Charlie R.; Bates, Martin A.

2015-01-01

101

Thermoelectric Outer Planets Spacecraft (TOPS)  

NASA Technical Reports Server (NTRS)

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.

1973-01-01

102

Carbon nanotube core graphitic shell hybrid fibers.  

PubMed

A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

2013-12-23

103

Separating in shell pistachio nuts from kernels using impact vibration analysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

A sorting system has been developed for the separation of small in-shell pistachio nuts from kernels without shells on the basis of vibrations generated when moving samples strike a steel plate. Impacts between the steel plate and the hard shells, as measured using an accelerometer attached to the...

104

Theoretical and Numerical Studies of the Shell Equations of Bauer, Reiss and Keller, Part I: Mathematical Theory  

E-print Network

the buckling of a thin­walled spherical shell under a uniform axisymmetric external static pressure­walled spherical shell under a uniform axisymmetric external static pressure y 0 1 (t) = (š \\Gamma 1) cot(t)y 1 (t of the inner and outer surface of the spherical shell be given by r = R \\Upsilon h, where R is the radius

105

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

E-print Network

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.

I. Bierenbaum; J. Blümlein; S. Klein

2007-02-26

106

Structure of Earth's outer radiation belt inferred from long-term electron flux dynamics  

E-print Network

flux of 2­6 MeV electrons, je (t; L) log Je (t; L), at equally spaced L shells over the year 1993Structure of Earth's outer radiation belt inferred from long-term electron flux dynamics D September 2003; published 15 October 2003. [1] We map the spatial structure of the electron belts over

107

First Principles Study of Core-Shell Semiconductor Nanocrystals  

NASA Astrophysics Data System (ADS)

Core-shell nanocrystals composed of two different semiconductors have recently attracted considerable attention. These structures provide enhanced functionality and possess more degrees of freedom than single-component semiconductor nanocrystals and quantum dots. I present the results of ab initio density functional calculations for the structures, electronic densities of states, and optical absorption gaps of core-shell nanocrystals composed of group II-VI semiconductors, such as CdSe, CdTe, ZnSe, and ZnTe. The outer surfaces of the nanocrystals are passivated using partially charged hydrogen atoms. The calculations are performed for "traditional" core-shell nanocrystals, in which a core a narrow gap semiconductor is covered with a shell of a wide gap material, and "inverted" core-shell nanocrystals, in which a wide-gap core is enclosed in a narrow-gap shell.

Vasiliev, Igor

2011-03-01

108

Observations of outer planet satellites  

Microsoft Academic Search

A regular natural satellite observing program has been in operation at McDonald Observatory since late 1972. The observation type has been direct astrometric photography from which the positions of the satellites may be measured with respect to the background star field. Effort has been devoted to the satellite systems of Saturn, Uranus and Neptune as well as the faint outer

Peter J. Sheulus; Richard I. Abbot; J. Derral Mulholland

1975-01-01

109

Observations of Outer Planet Satellites  

Microsoft Academic Search

A regular natural satellite observing program has been in operation at McDonald Observatory since late 1972. The observation type has been direct astrometric photography from which the positions of the satellites may be measured with respect to the background star field. Effort has been devoted to the satellite systems of Saturn, Uranus and Neptune as well as the faint outer

Peter J. Sheulus; Richard I. Abbot; J. Derral Mulholland

1975-01-01

110

Slingshot to the Outer Planets  

NSDL National Science Digital Library

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.

Integrated Teaching And Learning Program

111

OUTER LOOP LANDFILL CASE STUDY  

EPA Science Inventory

This presentation will describe the interim data reaulting from a CRADA between USEPA and Waste Management, Inc. at the outer Loop Landfill Bioreactor research project located in Louisville, KY. Recently updated data will be presented covering landfill solids, gas being collecte...

112

Mussel Shell Evaluation as Bioindicator For Heavy Metals  

NASA Astrophysics Data System (ADS)

Recently, in Brazil, it has appeared a new and unusual "plague" in lazer and commercial fishing. It is caused by the parasitic larval phase of certain native bivalve mollusks of fresh water known as "Naiades" and its involves the presence of big bivalve of fresh water, mainly Anodontites trapesialis, in the tanks and dams of the fish creation. These bivalve mollusks belong to the Unionoida Order, Mycetopodidae Family. The objective of the present work was to analyze the shells of these mollusks to verify the possibility of use as bioindicators for heavy metals in freshwater. The mollusks shells were collected in a commercial fishing at Londrina-PR. A qualitative analysis was made to determine the chemical composition of the shells and verify a possible correlation with existent heavy metals in the aquatic environment. In the inner part of the shells were identified the elements Ca, P, Fe, Mn and Sr and in the outer part were identified Ca, P, Fe, Mn, Sr and Cu. The Ca ratio of the outer part by inner part of the analyzed shells is around of 1, as expected, because Ca is the main compound of mollusks shells. The ratio of P, Fe, Mn, and Sr to the Ca were constant in all analyzed shells, being close to 0.015. The ratio Cu/Ca varied among the shells, showing that this mollusk is sensitive to concentration of this element in the aquatic environment.

Andrello, Avacir Casanova; Lopes, Fábio; Galvão, Tiago Dutra

2010-05-01

113

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

PubMed

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

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

2014-12-01

114

Shell-armored wood cobbles as a potential criterion for detrital coal deposits  

SciTech Connect

Shell-armored wood cobbles occur on detrital-peat beaches along the seaward edge of the Mississippi Delta. Shell material consists exclusively of Mulinia lateralis, a dwarf surf clam. Soft, heavy, waterlogged wood fragments are abraded and become armored by hard shells in response to wave activity on the beach. Although their preservation potential is suspect, fossilized shell-armored wood clasts would probably be recognized as a type of coal ball and might indicate an allochthonous origin for the host coal.

DiMarco, M.J.; Nummedal, D.

1986-01-01

115

Turbine airfoil with a compliant outer wall  

DOEpatents

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.

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

2012-04-03

116

Strategy for exploration of the outer planets: 1986-1996  

NASA Technical Reports Server (NTRS)

Over the past decade COMPLEX has published three strategy reports which, taken together, encompass the entire planetary system and recommend a coherent program of planetary exploration. The highest priority for outer planet exploration during the next decade is intensive study of Saturn (the planet, satellites, rings, and magnetosphere) as a system. The Committee additionally recommends that NASA engage in the following supporting activities: increased support of laboratory and theoretical studies; pursuit of earth-based and earth-orbital observations; commitment to continued operation of productive spacecraft; implementation of the instrument development plan as appropriate for the outer solar system; studies of deep atmospheric probes; development of penetrators or other hard landers; development of radiation-hardened spacecraft; and development of low-thrust propulsion systems. Longer-term objectives include exploration and intensive study of: the Uranus and Neptune systems; planetology of the Galilean satellites and Titan; and the inner Jovian system.

1986-01-01

117

Modelling of the outer heliosphere  

NASA Technical Reports Server (NTRS)

The interaction of the outflowing solar wind with the local interstellar medium (LISM) is complicated by many factors--the solar wind itself is a highly dynamical medium, interstellar neutral atoms can interact with the heliospheric boundaries in a complex fashion and the solar wind can be decelerated via mass-loading associated with pick-up ions, for example. Anomalous and galactic cosmic rays besides being modulated by the solar wind, may react back on the heliospheric boundaries leading to possibly significant structural modifications. These and other factors suggest that the physics of the outer heliosphere is strongly influenced by the properties of the very LISM and is quite different from the physics of the inner heliosphere. In this talk, we will try to synthesize the many recent developments in modelling the outer heliosphere and boundaries, encompassing both local and global models. Special emphasis will be placed on identifying those aspects of the various models which have observational implications.

Zank, G. P.

1995-01-01

118

Origin of Outer Solar System  

NASA Technical Reports Server (NTRS)

We feel that at the present moment the available theoretical models of the Kuiper belt are still in advance of the data, and thus our main task has been to conduct observational work guided by theoretical motivations. Our efforts over the past year can be divided into four categories: A) Wide-field Searches for Kuiper Belt Objects; B) Pencil-beam Searches for Kuiper Belt Objects; C) Wide-field Searches for Moons of the Outer Planets; D) Pencil-beam Searches for Faint Uranian and Neptunian Moons; E) Recovery Observations. As of April 2002, we have conducted several searches for Kuiper belt objects using large-format mosaic CCD camera on 4-meter class telescopes. In May 1999, we used the Kitt Peak 4-meter with the NOAO Mosaic camera we attempted a search for KBOs at a range of ecliptic latitudes. In addition to our wide-field searches, we have conducted three 'pencil-beam' searches in the past year. In a pencil-beam search we take repeated integrations of the same field throughout a night. After preprocessing the resulting images we shift and recombine them along a range of rates and directions consistent with the motion of KBOs. Stationary objects then smear out, while objects moving at near the shift rate appear as point sources. In addition to our searches for Kuiper belt objects, we are completing the inventory of the outer solar system by search for faint satellites of the outer planets. In August 2001 we conducted pencil beam searches for faint Uranian and Neptunian satellites at CFHT and CTIO. These searches resulted in the discover of two Neptunian and four Uranian satellite candidates. The discovery of Kuiper belt objects and outer planet satellites is of little use if the discoveries are not followed by systematic, repeated astrometric observations that permit reliable estimates of their orbits.

Holman, Matthew J.; Boyce, J. (Technical Monitor)

2003-01-01

119

Physics of the outer heliosphere  

SciTech Connect

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.

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

1991-01-01

120

Single and dual-band multimode hard horn antennas with partly corrugated walls  

Microsoft Academic Search

We introduce a partly corrugated hard horn, consisting of a smooth-walled horn with an attached longitudinally corrugated outer section. This alleviates the problems with the manufacturing when the longitudinal corrugations extend into the throat of the horn. The transition between the inner smooth walled part and the outer corrugated part is abrupt. This is used and controlled to design better

Omid Sotoudeh; Per-Simon Kildal; Per Ingvarson; Sergei P. Skobelev

2006-01-01

121

Transient temperatures in laminated composite conical shells due to aerodynamic heating  

Microsoft Academic Search

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

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

1978-01-01

122

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

NASA Technical Reports Server (NTRS)

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.

Draayer, Jerry P.; Troltenier, D.

1995-01-01

123

Magnetic properties of core/shell nanoparticles with magnetic or nonmagnetic shells  

NASA Astrophysics Data System (ADS)

In a model presented here, the effects of interparticle exchange and random magnetocrystalline anisotropy are added to the previous models of magnetization reversal for core/shell nanostructures in order to achieve better agreement with experimental data. The results from this model are compared with ones from the Stoner-Wohlfarth model in order to help us to interpret the shell thickness dependence of the coercivity in FePt/Fe3O4 core/shell nanoparticles and describe the difference between the results from the Stoner-Wohlfarth model and experimental data arising as the shell thickness increases. For magnetic shells in the FePt/Fe3O4 core/shell system, the effective coupling between particles increases with increasing shell thickness, which leads to coercivity destruction for stronger couplings. The nucleation mode penetrates from the soft phase into the hard phase when the exchange energy density is able to compete against the random anisotropy. According to the boundary conditions, in the harder regions with higher exchange stiffness, the magnetization variation should be small and so the magnetization modes should become more localized. We discuss localized and delocalized modes. The nonlocalized modes propagating in the soft phase for the non-zero shell thickness can have an effect on the quality of particle exchange interactions. In the case of nonmagnetic shells in the FePt/SiO2 core/shell system, the same model predicts a coercivity increase with increasing shell thickness. The increase in coercivity is due to the weakening of the particle coupling with the increasingly nonmagnetic shell. We present a model for exchange bias in these systems in order to interpret the coupling effects for the core and shell in the core/shell system. Chemical intermixing at the interface leads to ‘spin glass-like’ behavior of the core/shell interface which affects the strength of coupling of the core and shell spins. In the random anisotropy model there is not so much of an effect when just high anisotropy cores and we do not expect a major difference between the superparamagnetic limits predicted by the Stoner-Wohlfarth and exchange models. Considering a bulging mode to occur in the core will have an effect on the results due to the magnetization reversal mechanisms.

Sebt, S. A.; Bakhshayeshi, A.; Abolhassani, M. R.

2012-09-01

124

Semiclassical approach to K shell ionization: hydrogenic wave functions  

Microsoft Academic Search

Proton induced K shell ionization cross sections in several elements were calculated. Semiclassical approximation with momentum space approach, hydrogenic wave functions and outer screening according to the prescription of Bethe was used. Comparison with other semiclassical and Dirac-Hartree-Slater [DHS] plane wave cross sections indicates that this type of screening — largely used in plane wave methods — implies a less

Ž. Šmit

1991-01-01

125

The photochemistry of carbon-rich circumstellar shells  

Microsoft Academic Search

The effect of ambient ultraviolet photons on the chemical structure of carbon-rich, circumstellar envelopes is investigated with a simple formulation of the time-dependent, photochemical rate equations valid for optically thick shells. Molecules injected into the shielded inner envelope are broken down when they reach the outer regions where ambient ultraviolet photons can penetrate. A quantitative description of the abundance variations

P. J. Huggins; A. E. Glassgold

1982-01-01

126

The Fabrication of Replicated Optics for Hard X-Ray Astronomy  

NASA Technical Reports Server (NTRS)

We describe the fabrication process for producing shallow-graze-angle mirrors for hard x-ray astronomy. This presentation includes the generation of the necessary super-polished mandrels, their metrology, and the subsequent mirror shell electroforming and testing.

Speegle, C. O.; Ramsey, B. D.; Engelhaupt, D.

2000-01-01

127

Magnetospheres of the outer planets  

SciTech Connect

The magnetospheres of the outer planets have been shown by Voyager explorations to strongly interact with the surfaces and atmospheres of their planetary satellites and rings. In the cases of Jupiter, Saturn and Uranus, the processes of charged particle sputtering, neutral gas cloud formation, and rapid plasma injection from the ionization of the neutral clouds, have important implications both for the magnetospheres as a whole and for the surfaces and atmospheres of their satellites. The general methodology employed in these researches has involved comparisons of the planetary magnetospheres in order to identify common physical processes. 16 references.

Cheng, A.F.

1986-12-01

128

Detailed diagnosis of a double-shell collision under realistic implosion conditions  

SciTech Connect

Double-shell implosions provide a noncryogenic path to inertial confinement fusion. In the double-shell target, the energy is absorbed in an outer shell that is accelerated inward and collides with an inner shell that implodes against the deuterium fuel. Symmetric collision of the shells requires that the shells be illuminated and built symmetrically. In reality, the targets are complicated and the construction is not symmetric, due to the seam that our current assembly method requires. Using the Omega laser [R. T. Boehly et al., Opt. Comm. 133, 495 (1997)], an illumination strategy was designed that uses 40 beams in an offset geometry, leaving 20 beams to perform radiography from two different directions. This places a significant nonsymmetric illumination challenge that may not exist in final targets shot on the National Ignition Facility. This paper presents a measurement of the time history of a collision of two shells in a double-shell capsule, briefly reviews the illumination geometry, gives the results of the measurements of the trajectory and symmetry of the outer and inner shells, shows the effect of a seam on the inner shell implosion, and compares the results with calculations. The measurement of such a collision in a spherical geometry is of great interest to the study of double-shell implosions as well as code validation.

Kyrala, G.A.; Gunderson, M.A.; Delamater, N.D.; Haynes, D.A.; Wilson, D.C.; Guzik, J.A.; Klare, K.A. [Los Alamos National Laboratory, P.O. Box 1663, MS E-526, Los Alamos, New Mexico 87544 (United States)

2006-05-15

129

Hollow Pollen Shells to Enhance Drug Delivery  

PubMed Central

Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

Diego-Taboada, Alberto; Beckett, Stephen T.; Atkin, Stephen L.; Mackenzie, Grahame

2014-01-01

130

Hollow pollen shells to enhance drug delivery.  

PubMed

Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell. PMID:24638098

Diego-Taboada, Alberto; Beckett, Stephen T; Atkin, Stephen L; Mackenzie, Grahame

2014-01-01

131

Relativistic shells: Dynamics, horizons, and shell crossing  

E-print Network

We consider the dynamics of timelike spherical thin matter shells in vacuum. A general formalism for thin shells matching two arbitrary spherical spacetimes is derived, and subsequently specialized to the vacuum case. We first examine the relative motion of two dust shells by focusing on the dynamics of the exterior shell, whereby the problem is reduced to that of a single shell with different active Schwarzschild masses on each side. We then examine the dynamics of shells with non-vanishing tangential pressure $p$, and show that there are no stable--stationary, or otherwise--solutions for configurations with a strictly linear barotropic equation of state, $p=\\alpha\\sigma$, where $\\sigma$ is the proper surface energy density and $\\alpha\\in(-1,1)$. For {\\em arbitrary} equations of state, we show that, provided the weak energy condition holds, the strong energy condition is necessary and sufficient for stability. We examine in detail the formation of trapped surfaces, and show explicitly that a thin boundary layer causes the apparent horizon to evolve discontinuously. Finally, we derive an analytical (necessary and sufficient) condition for neighboring shells to cross, and compare the discrete shell model with the well-known continuous Lema\\^{\\i}tre-Tolman-Bondi dust case.

Sergio M. C. V. Goncalves

2002-12-30

132

Electrochemical characterization of a bioceramic material: The shell of the Eastern oyster Crassostrea virginica.  

PubMed

The shell of the Eastern oyster (Crassostrea virginica) is composed of multiple incongruent mineralized layers. This bioceramic composite material was investigated to determine the effects of shell thickness, orientation and layer composition on its electrochemical behavior using electrochemical impedance spectroscopy, potentiodynamic polarization and scanning electron microscopy-energy dispersive spectroscopy. SEM-EDS analysis of the oyster shell revealed that the multilayered biocomposite material is composed of calcium carbonate (CaCO(3)). EIS measurements in 3.5wt.% NaCl indicated that the impedance of the whole oyster shell in the low frequency region exhibited high impedance values which exhibited a decreasing trend with increasing immersion time. In terms of overall shell thickness, limiting currents measured by potentiodynamic techniques through the shell were observed to increase when the outer layers of the shell were sequentially removed by grinding, thus decreasing the shell thickness. These limiting current values remained relatively constant when the inner layers of the shell were removed. The impedance values of the oyster shell material as measured by EIS were shown to decrease with decreasing shell thickness. These findings suggest that the prismatic (outermost) shell layer in combination with the soluble organic matrix between all shell layers may influence the ionic conductivity through the oyster shell. PMID:21550319

Yoon, Yuhchae; Mount, Andrew S; Hansen, Karolyn M; Hansen, Douglas C

2011-06-01

133

Monodisperse magnetic core/shell microspheres with Pd nanoparticles-incorporated-carbon shells.  

PubMed

This work reports a hard self-template method to synthesize core/shell like Fe3O4@C microparticles, in which the Pd nanocrystals can be alternatively incorporated into the carbon shells. The Fe3O4@polyaniline core/shell microspheres were first synthesized as the precursor by in situ polymerization of aniline onto the surface of the Fe3O4 microspheres. In a subsequent carbonization of the precursor under a vacuum oven, the Fe3O4 core was preserved and the polyaniline shell transferred into carbon shells enveloping the magnetic sphere, forming magnetic Fe3O4@C microspheres. The Pd ions could be impregnated into the polyaniline shell, and thus the obtained composites were transformed into Fe3O4@C/Pd microspheres under the same vacuum heating progress. The as-obtained system demonstrates superparamagnetic characteristics, which would benefit its potential application in nanocatalysts. This strategy provides an efficient approach for tailoring core/shell materials with desired functionalities and structures by adjusting the precursors and structure-directing agents. PMID:24323164

Fang, Qunling; Cheng, Qing; Xu, Huajian; Xuan, Shouhu

2014-02-14

134

Formation of Gaseous Shells  

NASA Astrophysics Data System (ADS)

HI observations have revealed in several shell galaxies the presence of gaseous shells slightly displaced from the stellar shells radially, in the outward direction. We propose a mechanism to form this gaseous shells, based on the well-known phase-wrapping process of the companion matter in a merger, with nearly radial orbits. The mechanism relies on the existence of a clumpy interstellar matter, and on dynamical friction experienced by the companion core.

Combes, F.; Charmandaris, V.

135

The outer valence orbital momentum profiles of thiophene by electron momentum spectroscopy  

NASA Astrophysics Data System (ADS)

We report here the first measurements of the complete valence shell binding energy spectra and the outer valence orbital momentum profiles of thiophene, using a high resolution binary (e, 2e) electron momentum spectrometer, at an impact energy of 1200 eV plus the binding energy and using symmetric non-coplanar kinematics. Binding energy spectra of the complete valence shell have been obtained. The summed experimental momentum profile of the HOMO 1a 2 and NHOMO 3b 1 is compared with the theoretical momentum distributions calculated using Hartree-Fock and density functional theory methods with various basis sets. The experimental measurement is well described by the calculations.

Zhang, S. F.; Ren, X. G.; Su, G. L.; Ning, C. G.; Zhou, H.; Li, B.; Huang, F.; Li, G. Q.; Deng, J. K.

2005-01-01

136

Manipulation of emission energy in GaAs/AlGaAs core-shell nanowires with radial heterostructure  

SciTech Connect

Photoluminescence was studied in GaAs/AlGaAs nanowires (NWs) with different radial heterostructures. We demonstrated that manipulation of the emission energy may be achieved by appropriate choice of the shell structure. The emission at highest energy is generated in the NWs with tunneling thin AlGaAs inner shell and thin GaAs outer shell due to recombination of the photoexcited electrons confined in the outer shell with the holes in the core. Lower energy emission was shown to occur in the NWs with thick outer shell grown in the form of a short-period GaAs/AlGaAs multiple quantum well structure. In this case, the tunneling probability through the multiple quantum wells controls the energy emitted by the NWs. The doping of core results in dominated low energy emission from the GaAs core.

Barbosa, B. G.; Arakaki, H.; Souza, C. A. de; Pusep, Yu. A. [Instituto de Fisica de São Carlos, Universidade de São Paulo, 13560-970 Sao Carlos, SP (Brazil)

2014-03-21

137

Chandra Peers Into Outer Space  

NSDL National Science Digital Library

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.

Payne, Laura X.

138

Chemistry of the outer planets  

NASA Technical Reports Server (NTRS)

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.

Scattergood, Thomas W.

1992-01-01

139

How Hard is Chocolate?  

NSDL National Science Digital Library

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.

2007-12-20

140

Session: Hard Rock Penetration  

SciTech Connect

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.

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

1992-01-01

141

Memory Hard Drive Peripherals  

E-print Network

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

Stojmenovic, Ivan

142

Fluctuating shells under pressure  

PubMed Central

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

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

2012-01-01

143

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

Microsoft Academic Search

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

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

2007-01-01

144

Claw morphology, prey size selection and foraging efficiency in generalist and specialist shell-breaking crabs  

Microsoft Academic Search

Claw morphology, and claw-closing forces of four species of intertidal crabs from San Juan Island, Washington were compared and related these findings were related to prey size selection, shell breaking times and total handling times on their snail prey, Littorina sitkana Philippi. Two functional groups of crabs emerged: generalists and specialists on hard-shelled prey. The generalist, Hemigrapsus nudus (Dana), has

Sylvia Behrens Yamada; Elizabeth G. Boulding

1998-01-01

145

A surface crack in shells under mixed-mode loading conditions  

NASA Technical Reports Server (NTRS)

The present consideration of a shallow shell's surface crack under general loading conditions notes that while the mode I state can be separated, modes II and III remain coupled. A line spring model is developed to formulate the part-through crack problem under mixed-mode conditions, and then to consider a shallow shell of arbitrary curvature having a part-through crack located on the outer or the inner surface of the shell; Reissner's transverse shear theory is used to formulate the problem under the assumption that the shell is subjected to all five moment and stress resultants.

Joseph, P. F.; Erdogan, F.

1988-01-01

146

The hard metal diseases  

SciTech Connect

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.66 references.

Cugell, D.W. (Department of Medicine, Northwestern University Medical School, Chicago, IL (United States))

1992-06-01

147

Physics Flashlets: The Outer Solar System  

NSDL National Science Digital Library

This animation shows the orbits of the outer planets in the Solar System. This model of the outer solar system includes Jupiter, Saturn, Uranus, and Neptune. The paths of the planets are plotted and traced, and the user can see their relative speeds and periods to complete a full revolution.

Fowler, Michael; Welch, Heather

2008-09-24

148

Discovery Collection: Oyster Shells  

NSDL National Science Digital Library

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.

Breslof, Lisa; Schiller, William

149

Can Shells be Biomonitor of Contaminants in the Environment: an Investigation Study of Perfluorinated Compounds in Bivalve Shells of China  

NASA Astrophysics Data System (ADS)

To assess the feasibility of using biominerals to biomonitor the extent of persistent contaminants in the environment, concentrations of perfluorinated compounds (PFCs), including perfluorinated carboxylic acids (PFCAs) and perfluorinated alkylsulfonates (PFASs), in the bivalve shells of clams, razor clams, oysters and mussels sampled from 8 sampling sites along China coast were analyzed. Concentrations of these contaminants in the waters and sediments of the sampling sites, as well as in the soft tissues of clams were also determined. Results show that though the concentrations of most PFCs in shells were lower than in soft tissues, the amount of contaminants in shells and soft tissues of bivalves are comparable, due to the larger dry-weight of shells than soft tissues of these animals. Concentrations of some PFCs in shells primarily correlate to concentrations in sediments, while concentrations in the soft tissues seems to be more related to those in water samples. We suggested that shells uptake PFCs by adsorption or passive deposition of the target chemicals to the shell organic matrix followed by a biomineralisation process. Therefore, contaminants bound to the organic matrix in the shell microstructure are sequestrated and hard to release. Like soft tissues, biominerals, e.g. shells, might also be considered as biomonitoring matrix for some contaminants in environments, because (i) the individual differences of contaminants concentrations among shell samples were smaller than soft tissue samples; (ii) secondary pollution is less likely to affect shell samples during sampling and transportation; and (iii) the shells was hypothesized to "record" past exposure to contaminants according to their annual growth ring. (This study was supported by National Science Foundation for Natural Science, China (No. 20807024) & Research Fund for the Doctoral Program of Higher Education of China (No. 200800551051))

Wang, Lei

2010-05-01

150

Folding of outer membrane proteins.  

PubMed

Outer membrane proteins (OMPs) represent a large group of ?-barrel proteins found both in the membranes of both bacteria and eukaryotes. Their general ease of expression and refolding and straightforward methods to monitor their degree of folding conspire to make OMPs excellent model systems to investigate how the membrane environment and other biological factors modulating the membrane insertion and folding of OMPs influence the folding pathway. This review attempts to provide an overview of how these proteins are studied in vitro and what kind of information can reliably be extracted. Numerous choices have to be made in setting the conditions for successful folding/unfolding, and here a major challenge remains to identify conditions that lead to completely reversible folding without any hysteresis. Recent progress indicates that this is possible through rigorous optimization, such as the use of relatively extreme pH and phospholipids with short chain lengths. OMPs are generally kinetically very stable, which means that they both fold and unfold very slowly. Many OMPs cannot even unfold when embedded in lipid vesicles, but recent work has demonstrated that surfactants can provide a useful alternative which can lead to a complete description of the kinetics of folding and unfolding of an OMP. The recent report of the first protein engineering study of an OMP has demonstrated that it may soon be possible to have almost atomic-level resolution of an OMP folding mechanism. Combining this insight with the biological complexity of the membrane environment constitutes an exciting new frontier in membrane protein science. PMID:23131493

Otzen, Daniel E; Andersen, Kell K

2013-03-01

151

Buckling and free vibration analysis of functionally graded cylindrical shells subjected to a temperature-specified boundary condition  

Microsoft Academic Search

Linear thermal buckling and free vibration analysis are presented for functionally graded cylindrical shells with clamped–clamped boundary condition based on temperature-dependent material properties. The material properties of functionally graded materials (FGM) shell are assumed to vary smoothly and continuously across the thickness. With high-temperature specified on the inner surface of the FGM shell and outer surface at ambient temperature, 1D

Ravikiran Kadoli; N. Ganesan

2006-01-01

152

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

SciTech Connect

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.

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

153

The Development of Hard-X-Ray Optics at MSFC  

NASA Technical Reports Server (NTRS)

We are fabricating optics for the hard-x-ray region using electroless nickel replication. The attraction of this process, which has been widely used elsewhere, is that the resulting full shell optics are inherently table and thus can have very good angular resolution. The challenge with this process is to develop lightweight optics (nickel has a relatively high density of 8.9 g / cu cm), and to keep down the costs of mandrel fabrication. We accomplished the former through the development of high-strength nickel alloys that permit very thin shells without fabrication- and handling-induced deformations. For the latter, we have utilized inexpensive grinding and diamond turning to figure the mandrels and then purpose-built polishing machines to finish the surface. In-house plating tanks and a simple water-bath separation system complete the process. To date we have built shells ranging in size from 5 cm diameter to 50 cm, and with thickness down to 100 micron. For our HERO (high energy replicated optics) balloon program, we are fabricating over 200 iridium-coated shells, 250 microns thick, for hard-x-ray imaging up to 75 keV. Early test results on these have indicated half-power-diameters of 15 arcsec. The status of these and other hard-x-ray optics will be reviewed.

Ramsey, Brian D.; Elsner, R. F.; Engelhaupt, D. E.; Kolodziejczak, J. J.; ODell, S. L.; Speegle, C. O.; Weisskopf, M. C.; Six, Frank (Technical Monitor)

2002-01-01

154

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

Microsoft Academic Search

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

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

155

Shell Cracking Strength in Almond (Prunus dulcis [Mill.] D.A. Webb.)and its implication in uses as a value-added product.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Researchers are currently developing new uses for almond shells, an abundant agricultural by-product. While almond varieties are classified by processing facilities as being either hard or soft shelled, shell morphological characteristics and compositional components contribute to the variability p...

156

Incorporation of squalene into rod outer segments  

SciTech Connect

We have reported previously that squalene is the major radiolabeled nonsaponifiable lipid product derived from ({sup 3}H)acetate in short term incubations of frog retinas. In the present study, we demonstrate that newly synthesized squalene is incorporated into rod outer segments under similar in vitro conditions. We show further that squalene is an endogenous constituent of frog rod outer segment membranes; its concentration is approximately 9.5 nmol/mumol of phospholipid or about 9% of the level of cholesterol. Pulse-chase experiments with radiolabeled precursors revealed no metabolism of outer segment squalene to sterols in up to 20 h of chase. Taken together with our previous absolute rate studies, these results suggest that most, if not all, of the squalene synthesized by the frog retina is transported to rod outer segments. Synthesis of protein is not required for squalene transport since puromycin had no effect on squalene incorporation into outer segments. Conversely, inhibition of isoprenoid synthesis with mevinolin had no effect on the incorporation of opsin into the outer segment. These latter results support the conclusion that the de novo synthesis and subsequent intracellular trafficking of opsin and isoprenoid lipids destined for the outer segment occur via independent mechanisms.

Keller, R.K.; Fliesler, S.J. (Univ. of South Florida College of Medicine, Tampa (USA))

1990-08-15

157

Outer planets and icy satellites  

NASA Technical Reports Server (NTRS)

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.

Drobyshevski, E. M.

1991-01-01

158

Appearance of hot spots due to deposits in the JET MKII-HD outer divertor  

NASA Astrophysics Data System (ADS)

Deposited layers in the JET MKII-HD outer divertor have been investigated on the basis of their transient heating. The Planck radiation in the 400-600 nm wavelength range and IR thermography data were analyzed to correlate the appearance of the layers with plasma conditions. Both methods yielded significantly different surface temperatures: typically >2000 K for the visible light spectroscopy and down to 800 K for the thermography. This is explained by the existence of high temperature emission areas as small as 1-2 mm 2. Analysis of the reoccurrence of hot spots in the outer divertor throughout the 2006 campaigns indicated that the formation is determined by the combination of the outer strike point location and the plasma stored energy. The observations did not indicate any changes in thermal properties nor cyclic formation and disintegration of the layers, i.e. it was stable and so-called hard layers.

van Rooij, G. J.; Brezinsek, S.; Coad, J. P.; Fundamenski, W.; Philipps, V.; Arnoux, G.; Stamp, M. F.; EFDA contributors, JET

2009-06-01

159

Assessment of the mechanism of elemental incorporation into bivalve shells (Arctica islandica) based on elemental distribution at the microstructural scale  

NASA Astrophysics Data System (ADS)

To address the mechanism of elemental incorporation into shells of the bivalve Arctica islandica, we performed two-dimensional elemental mapping of Sr, Mg, and S at a ˜3 ?m spatial resolution using electron microprobe. These elemental distributions were precisely compared to the shell microstructure. The Sr distribution was intimately linked to the S concentration and/or shell microstructure. Sr showed a clear annual pattern with higher values at the annual growth lines and lower values in annual growth increments. The Sr and S concentrations were higher near sub-annual growth lines than in the adjacent regions, which were dominated by acicular microstructure (middle shell layer) or homogeneous microstructure (outer shell layer). Furthermore, the Sr concentration was lower in the middle shell layer than in the outer shell layer, but there was no clear difference in the S concentration between the two layers. The observed elemental distribution in the shell can be reasonably explained by the hypothesis that the organic composition at the calcification site, i.e. in the extrapallial space, can facilitate the preferential elemental incorporation into calcium carbonate. The Sr/Ca ratio shows micrometer scale variation within the shell, suggesting that fine spatial resolution, comparable to the shell microstructure, is required for the analysis of elemental distribution to avoid time-averaging and to correctly evaluate the magnitude of the compositional variation in the shell for past environmental reconstruction.

Shirai, Kotaro; Schöne, Bernd R.; Miyaji, Tsuzumi; Radarmacher, Pascal; Krause, Richard A.; Tanabe, Kazushige

2014-02-01

160

SHELL METHOD DEMO GALLERY  

NSDL National Science Digital Library

This is a gallery of animations that can be used to illustrate the shell method for computing volumes of solids of revolution. The animations are designed to be used by the instructor in a classroom setting or by students as they acquire a visual background relating to solids of revolution and the steps of the shell method.

Roberts, Lila F.

2002-02-02

161

I Learned about Shells!  

NSDL National Science Digital Library

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.

Ryan, Kris

2012-06-26

162

Thin shell model revisited  

E-print Network

We reconsider some fundamental problems of the thin shell model. First, we point out that the "cut and paste" construction does not guarantee a well-defined manifold because there is no overlap of coordinates across the shell. When one requires that the spacetime metric across the thin shell is continuous, it also provides a way to specify the tangent space and the manifold. Other authors have shown that this specification leads to the conservation laws when shells collide. On the other hand, the well-known areal radius $r$ seems to be a perfect coordinate covering all regions of a spherically symmetric spacetime. However, we show by simple but rigorous arguments that $r$ fails to be a coordinate covering a neighborhood of the thin shell if the metric across the shell is continuous. When two spherical shells collide and merge into one, we show that it is possible that $r$ remains to be a good coordinate and the conservation laws hold. To make this happen, different spacetime regions divided by the shells must be glued in a specific way such that some constraints are satisfied. We compare our new construction with the old one by solving constraints numerically.

Sijie Gao; Xiaobao Wang

2014-12-26

163

Outer Billiards and the Pinwheel Map  

E-print Network

In this paper we establish a kind of bijection between the orbits of a polygonal outer billiards system and the orbits of a related (and simpler to analyze) system called the pinwheel map. One consequence of the result is that the outer billiards system has unbounded orbits if and only if the pinwheel map has unbounded orbits. As the pinwheel map is much easier to analyze directly, we think that this bijection will be helpful in attacking some of the main questions about polyonal outer billiards.

Schwartz, Richard Evan

2010-01-01

164

Cohesive Elements for Shells  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

165

The photochemistry of carbon-rich circumstellar shells  

NASA Technical Reports Server (NTRS)

The effect of ambient ultraviolet photons on the chemical structure of carbon-rich, circumstellar envelopes is investigated with a simple formulation of the time-dependent, photochemical rate equations valid for optically thick shells. Molecules injected into the shielded inner envelope are broken down when they reach the outer regions where ambient ultraviolet photons can penetrate. A quantitative description of the abundance variations is obtained for the case of uniform expansion by detailed consideration of the shielding of the radiation by the dust and molecules of the envelope. Representative results are presented to illustrate the role of shielding in defining the extent of molecular envelopes, the formation of C I and C II shells by photodestruction of carbon-bearing molecules, and the development of layered chemical structures from the photobreakup of polyatomic molecules. Photochemistry makes the outer parts of thick, carbon-rich envelopes into complex regions containing radicals, ions, and atoms which are of considerable observational and theoretical interest.

Huggins, P. J.; Glassgold, A. E.

1982-01-01

166

A simplified hartree-fock procedure for atoms with two electrons outside closed shells  

Microsoft Academic Search

The observed spectrum of Ca+ is used to construct an effective potential to represent the interaction of an outer electron with the closed-shell core. The effective potential is used to reduce the problem of calculating wave functions for the outer electrons of the netural calcium atom to a two-electron problem, which is then solved in the Hartree-Fock approximation for the

C. D. H. Chisholm; U. Öpik

1964-01-01

167

Shell microstructure of the late Carboniferous rostroconch mollusc Apotocardium lanterna (Branson, 1965)  

USGS Publications Warehouse

The Late Carboniferous bransoniid conocardioidean Apotocardium lanterna (Branson, 1965) had an entirely aragonitic shell with a finely prismatic outer shell layer, a predominantly crossed lamellar to complex crossed lamellar middle shell layer, and an "inner" shell layer of finely textured porcelaneous and/or matted structure. This "inner" layer is probably homologous with the inner part of the middle shell layer and the inner layer sensu stricto of bivalved molluscs. Shell morphological and microstructural convergences between conocardioids and living heart cockles suggest that at least some conocardioids may have farmed algal endosymbionts in their posterior mantle margins. This symbiosis may have helped conocardioids compete with the biomechanically more efficient bivalves during the latter part of the Paleozoic.

Rogalla, N.S.; Carter, J.G.; Pojeta, J., Jr.

2003-01-01

168

Is the Outer Solar System Really Chaotic?  

Microsoft Academic Search

The existence of chaos among the system of Jovian planets (Jupiter, Saturn, Uranus, and Neptune) is not yet firmly established. Although Laskar originally found no chaos in the outer Solar System, his \\

Wayne B. Hayes

2006-01-01

169

Radio Wave Emission from the Outer Planets  

E-print Network

Radio Wave Emission from the Outer Planets P. Zarka LESIA, Observatoire de Paris, Meudon #12;All properties of Auroral Radio Emissions : · very intense #12;[Zarka, 2000] Earth's ionospheric cutoff #12

Demoulin, Pascal

170

Outer Billiards and the Pinwheel Map  

Microsoft Academic Search

In this paper we establish a kind of bijection between the orbits of a\\u000apolygonal outer billiards system and the orbits of a related (and simpler to\\u000aanalyze) system called the pinwheel map. One consequence of the result is that\\u000athe outer billiards system has unbounded orbits if and only if the pinwheel map\\u000ahas unbounded orbits. As the pinwheel

Richard Evan Schwartz

2010-01-01

171

Planetary Aeronomy of the Outer Solar System  

NASA Astrophysics Data System (ADS)

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.

Strobel, Darrell

2012-10-01

172

Outer Retinal Tubulation in Degenerative Retinal Disorders  

PubMed Central

Objective To demonstrate outer retinal tubulation (ORT) in various degenerative retinal disorders. Methods This was a retrospective review of the multimodal imaging of 29 eyes of 15 patients with various retinal dystrophies and inflammatory maculopathies manifesting ORT. The morphologic features of ORT and its evolution over time were analyzed using spectral-domain optical coherence tomography (SD-OCT) data. Results Outer retinal tubulation was identified as round or ovoid structures with hyper-reflective borders in pattern dystrophy (6 eyes), acute zonal occult outer retinopathy (5 eyes), retinitis pigmentosa (4 eyes), Stargardt disease (4 eyes), gyrate atrophy (2 eyes), choroideremia (2 eyes), and various other degenerative conditions. These structures appeared to develop from the invagination of photoreceptors at the junction of intact and atrophic outer retina. During follow-up, the number and distribution of ORT largely remained stable. As zones of atrophy enlarged, the frequency of ORT appeared to increase. The ORT structures were found in fewer than 10% of patients with retinitis pigmentosa, Stargardt, or pattern dystrophy. Conclusion Outer retinal tubulation is found in various degenerative retinal disorders that share in common damage to the outer retina and/or retinal pigment epithelium. The presence of ORT may be in an indicator of underlying disease stage and severity. PMID:23676993

Goldberg, Naomi R.; Greenberg, Jonathan P.; Laud, Ketan; Tsang, Stephen; Freund, K. Bailey

2013-01-01

173

Stable carbon isotopes in freshwater mussel shells: Environmental record or marker for metabolic activity?  

NASA Astrophysics Data System (ADS)

Mussel shells have been used in a number of paleoecological and environmental studies. The interpretation of stable carbon isotopic composition of shell material is still controversial. The carbon for shell carbonate precipitation can either be derived from ambient dissolved inorganic carbon (DIC), with shells recording environmental signals, or from metabolic CO 2, with the potential to disguise environmental signals. To gain insight into this question, we investigated four nearly 100-yr long-term records of aragonite shells from an extant freshwater bivalve species, the endangered freshwater pearl mussel ( Margaritifera margaritifera L.). Single growth increments of the outer prismatic and the inner nacreous zones were successfully and easily separated with a simple heat treatment for chronological analyses of ? 13C in single layers of each zone. Autocorrelation and semivariance statistical methods reveal that mussels show distinct individual signal patterns, which extend up to 25 yr. Signal patterns are reliably reproduced with replicate samples from defined layers within one shell and show similar patterns with a slight offset for inner nacreous and outer prismatic layers for individual animals. Mussels exposed to the same environmental conditions exhibit distinct and contradictory signature patterns, which do not match between individuals. This observation can only be explained by strong metabolic influences on shell precipitation. Environmental changes in pH, temperature, electric conductivity and atmospheric carbon signature had no or little (<5%) influence, whereas body tissue protein and body tissue ? 13C signatures negatively correlated with the youngest produced shell ? 13C signatures, indicating that respiration causes a preferential loss of light isotopes from body mass and an inverse enrichment in shell aragonite. Hence, the shells of the freshwater pearl mussel yield a long-term record of metabolic activity, whereas the use of ? 13C in these shells as recorder for environmental signals is questionable. This may also be true for shells from other species, for which metabolic carbon incorporation has been acknowledged.

Geist, Juergen; Auerswald, Karl; Boom, Arnoud

2005-07-01

174

Free volume distribution of nearly jammed hard sphere packings  

NASA Astrophysics Data System (ADS)

We calculate the free volume distributions of nearly jammed packings of monodisperse and bidisperse hard sphere configurations. These distributions differ qualitatively from those of the fluid, displaying a power law tail at large free volumes, which constitutes a distinct signature of nearly jammed configurations, persisting for moderate degrees of decompression. We reproduce and explain the observed distribution by considering the pair correlation function within the first coordination shell for jammed hard sphere configurations. We analyze features of the equation of state near jamming, and discuss the significance of observed asphericities of the free volumes to the equation of state.

Maiti, Moumita; Sastry, Srikanth

2014-07-01

175

Free volume distribution of nearly jammed hard sphere packings.  

PubMed

We calculate the free volume distributions of nearly jammed packings of monodisperse and bidisperse hard sphere configurations. These distributions differ qualitatively from those of the fluid, displaying a power law tail at large free volumes, which constitutes a distinct signature of nearly jammed configurations, persisting for moderate degrees of decompression. We reproduce and explain the observed distribution by considering the pair correlation function within the first coordination shell for jammed hard sphere configurations. We analyze features of the equation of state near jamming, and discuss the significance of observed asphericities of the free volumes to the equation of state. PMID:25084929

Maiti, Moumita; Sastry, Srikanth

2014-07-28

176

Free volume distribution of nearly jammed hard sphere packings  

E-print Network

We calculate the free volume distributions of nearly jammed packings of monodisperse and bidisperse hard sphere configurations. These distributions differ qualitatively from those of the fluid, displaying a power law tail at large free volumes, which constitutes a distinct signature of nearly jammed configurations, persisting for moderate degrees of decompression. We reproduce and explain the observed distribution by considering the pair correlation function within the first coordination shell for jammed hard sphere configurations. We analyze features of the equation of state near jamming, and discuss the significance of observed asphericities of the free volumes to the equation of state.

Moumita Maiti; Srikanth Sastry

2014-07-25

177

Thermoelastic vibration and damping analysis of double-walled carbon nanotubes based on shell theory  

Microsoft Academic Search

Thermoelastic vibration and damping of a double-walled carbon nanotube upon interlayer van der Waals (vdW) interaction and initial axial stresses are studied. The inner and outer carbon nanotubes are modeled as two individual elastic thin shells. The general thermoelastic coupled equations for cylindrical thin shells are presented and simulation results are demonstrated for double-walled carbon nanotubes (DWCNTs). Numerical results show

M. S. Hoseinzadeh; S. E. Khadem

2011-01-01

178

Study of short-wavelength perturbation growth for NIF double-shell ignition designs  

Microsoft Academic Search

The double-shell concept has been proposed as an alternative ignition design for the NIF due to its advantages over cryogenic targets [Amendt et al., PoP 9, 2221 (2002)]. Recent studies have concentrated on a design that optimizes the fall-line behavior to reduce sensitivity to mix on the unstable pusher-fuel interface. Intrinsic perturbations of the outer surface of the inner shell

Jose Milovich; Peter Amendt; Michael Marinak; Harry Robey

2002-01-01

179

Hard Probes at RHIC  

NASA Astrophysics Data System (ADS)

Measurements of jets and heavy ?avour, the so called hard probes, play a crucial role in understanding properties of hot and dense nuclear matter created in high energy heavy-ion collisions. The measurements at the Relativistic Heavy Ion Collider (RHIC) showed that in central Au+Au collisons at RHIC energy ( ?sNN = 200 GeV) the nuclear matter created has properties close to those of perfect liquid, manifests partonic degrees of freedom and is opaque to hard probes. In order to draw quantitative conclusions on properties of this hot and dense nuclear matter reference measurements in proton-proton collisions and d+Au collisions are essential to estimate cold nuclear matter effects. In this proceedings a review of recent results on hard probes measurements in p+p, d+Au and A+A collisions as well as of beam energy dependence of jet quenching from STAR and PHENIX experiments at RHIC is presented.

Biel?íková, Jana

2014-04-01

180

Dynamics of a suspension of interacting yolk-shell particles  

NASA Astrophysics Data System (ADS)

In this work we study the self-diffusion 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-diffusion coefficients D^0s for the shells and D^0y 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 effective 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-diffusion 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 find that the yolks, which have no effect on the shell-shell static structure, influence the dynamic properties in a predictable manner, fully captured by the theory.

Sánchez Díaz, L. E.; Cortes-Morales, E. C.; Li, X.; Chen, Wei-Ren; Medina-Noyola, M.

2014-12-01

181

Name That Shell  

NSDL National Science Digital Library

The way a firework shell is designed and assembled determines the shape and color of a firework display. Choose a video clip and try to identify each firework variety in this interactive activity from the NOVA Web site.

2004-01-29

182

Elastic Platonic Shells  

NASA Astrophysics Data System (ADS)

On microscopic scales, the crystallinity of flexible tethered or cross-linked membranes determines their mechanical response. We show that by controlling the type, number, and distribution of defects on a spherical elastic shell, it is possible to direct the morphology of these structures. Our numerical simulations show that by deflating a crystalline shell with defects, we can create elastic shell analogs of the classical platonic solids. These morphologies arise via a sharp buckling transition from the sphere which is strongly hysteretic in loading or unloading. We construct a minimal Landau theory for the transition using quadratic and cubic invariants of the spherical harmonic modes. Our approach suggests methods to engineer shape into soft spherical shells using a frozen defect topology.

Yong, Ee Hou; Nelson, David R.; Mahadevan, L.

2013-10-01

183

Hollow spherical shell manufacture  

DOEpatents

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.

O'Holleran, T.P.

1991-11-26

184

Hollow spherical shell manufacture  

DOEpatents

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.

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

1991-01-01

185

Shells and Patterns  

ERIC Educational Resources Information Center

"Shells and Patterns" was a project the author felt would easily put smiles on the faces of her fifth-graders, and teach them about unity and the use of watercolor pencils as well. It was thrilling to see the excitement in her students as they made their line drawings of shells come to life. For the most part, they quickly got the hang of…

Sutley, Jane

2009-01-01

186

Improved Method of Design for Folding Inflatable Shells  

NASA Technical Reports Server (NTRS)

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

Johnson, Christopher J.

2009-01-01

187

Morphogenesis of active shells.  

PubMed

We consider the active shell as a single-cell or epithelial sheet surface that, sharing basic properties of stretched elastic shells, is capable of active planar movement owing to recruiting of the new surface elements. As model examples of their morphogenesis, we consider the growth and differentiation of single-cell hairs (trichomes) in plants of the genus Draba, and the epiboly and formation of the dorsoventral polarity in loach. The essential feature of the active shell behavior at both cellular and supracellular levels is regular deviating from the spatially homogeneous form, which is a primary cause of originating of the active mechanical stresses inside the shell in addition to its passive stretching by the intrinsic forces. Analyzing the quantitative morphological data, we derive the equations in which the temporal self-oscillations and spatial differentiation are distinguishable only at the parametric level depending on the proportion of active to passive stresses. In contrast to the ordinary activator-inhibitor systems, the self-oscillation dynamics is principally non-local and, consequently, one-parametric, the shell surface curvature being an analog of the inhibitor, while its spatial variance being an analog of the activator of shaping. Analyzing variability and evolution of the hair cell branching, we argue that the linear ontogeny (succession of the developmental stages) is a secondary evolutionary phenomenon originating from cyclic self-organizing algorithms of the active shell shaping. PMID:22613513

Cherdantsev, Vladimir G; Grigorieva, Olga V

2012-09-01

188

CSI: Hard Drive  

ERIC Educational Resources Information Center

Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

Sturgeon, Julie

2008-01-01

189

Work Hard. Be Nice  

ERIC Educational Resources Information Center

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,…

Mathews, Jay

2009-01-01

190

Running in Hard Times  

ERIC Educational Resources Information Center

Roberta Stevens and Kent Oliver are campaigning hard for the presidency of the American Library Association (ALA). Stevens is outreach projects and partnerships officer at the Library of Congress. Oliver is executive director of the Stark County District Library in Canton, Ohio. They have debated, discussed, and posted web sites, Facebook pages,…

Berry, John N., III

2009-01-01

191

Hard Sphere Gas Model  

NSDL National Science Digital Library

The Ejs Hard Sphere Gas model displays a three-dimensional (ideal) gas made out of hard disks. Particles are initialized with a random speed and in a random direction and move with constant velocity until a collision occurs. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Hard Sphere Gas model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_newton_HardShpereGas.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for statistical mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Christian, Wolfgang

2008-07-06

192

Analytic expressions for bound-bound and bound-free dipole transition matrix elements of atomic inner shells  

NASA Astrophysics Data System (ADS)

Analytic expressions are obtained which well represent the nonrelativistic single-electron (nl,n'l') dipole transition rates in screened central potentials, not only when both states are inner shell in character, as had been previously achieved, but also when only one of the states has an inner-shell character. The key idea is to expand one of the screened bound-state wave functions (outer shell) in terms of an unbound negative-energy Coulomb wave function with the same energy shift as the screening shift of the inner-shell bound state. The expressions obtained are an analytic continuation (in photon energy) of corresponding bound-free matrix elements.

Wang, M. S.; Pratt, R. H.

1983-04-01

193

Iron Oxide Versus Fe Pt \\/Fe O : Improved Magnetic Properties of Core\\/Shell Nanoparticles for Biomedical Applications  

Microsoft Academic Search

In this paper, synthesis of the Fe55Pt45\\/Fe3O4 core\\/shell structured nanoparticles using the modified polyol process combined with the seed-mediated growth method is reported. Iron oxide shell thickness was tuned controlling the Fe(acac) 3\\/FePt seeds in the reaction medium. Annealing of the core\\/shell structure leads to iron-rich layer formation around the hard FePt phase in the nanoparticle core. However, the 2

L. C. Varanda; M. Imaizumi; F. J. Santos; M. Jafelicci Jr.

2008-01-01

194

Baseline Microstructural Characterization of Outer 3013 Containers  

SciTech Connect

Three DOE Standard 3013 outer storage containers were examined to characterize the microstructure of the type 316L stainless steel material of construction. Two of the containers were closure-welded yielding production-quality outer 3013 containers; the third examined container was not closed. Optical metallography and Knoop microhardness measurements were performed to establish a baseline characterization that will support future destructive examinations of 3013 outer containers in the storage inventory. Metallography revealed the microstructural features typical of this austenitic stainless steel as it is formed and welded. The grains were equiaxed with evident annealing twins. Flow lines were prominent in the forming directions of the cylindrical body and flat lids and bottom caps. No adverse indications were seen. Microhardness values, although widely varying, were consistent with annealed austenitic stainless steel. The data gathered as part of this characterization will be used as a baseline for the destructive examination of 3013 containers removed from the storage inventory.

Zapp, Phillip E.; Dunn, Kerry A

2005-07-31

195

Effects of alga polysaccharide capsule shells on in-vivo bioavailability and disintegration  

NASA Astrophysics Data System (ADS)

Gelatin has been used in hard capsule shells for more than a century, and some shortcomings have appeared, such as high moisture content and risk of transmitting diseases of animal origin to people. Based on available studies regarding gelatin and vegetable shells, we developed a new type of algal polysaccharide capsule (APPC) shells. To test whether our products can replace commercial gelatin shells, we measured in-vivo plasma concentration of 12 selected volunteers with a model drug, ibuprofen, using high performance liquid chromatography (HPLC), by calculating the relative bioavailability of APPC and Qualicaps® referenced to gelatin capsules and assessing bioequivalence of the three types of shells, and calculated pharmacokinetic parameters with the software DAS 2.0 (China). The results show that APPC shells possess bioequivalence with Qualicaps® and gelatin shells. Moreover, the disintegration behavior of four types of shells (APPC, Vegcaps®, Qualicaps® and gelatin shells) with the content of lactose and radioactive element (99mTc) was observed via gamma-scintigraphic images. The bioavailability and gamma-scintigraphic studies showed that APPC was not statistically different from other vegetable and gelatin capsule shells with respect to in-vivo behavior. Hence, it can be concluded that APPCs are exchangeable with other vegetable and gelatin shells.

Li, Ting; Guo, Shuju; Ma, Lin; Yuan, Yi; Han, Lijun

2012-01-01

196

Outer-planet probe/flyby missions  

NASA Technical Reports Server (NTRS)

Results are presented for preliminary studies of low-cost outer-planet probe/flyby missions. The scientific rationale for such missions is discussed, along with possible mission modes, spacecraft concepts, launch-vehicle options, and a recommended set of outer-planet missions. Descriptions are given for a 1990 Titan probe/flyby mission and a 1991 Saturn probe/flyby mission. Projected costs are analyzed for these two missions as well as for a 1992 Neptune probe/flyby mission, a 1994 Uranus probe/flyby mission, and a 2003 Pluto flyby mission.

Swenson, B. L.; Mascy, A. C.; Murphy, J. P.; Cuzzi, J. N.

1983-01-01

197

Ptolemy's treatment of the outer planets  

NASA Astrophysics Data System (ADS)

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.

Duke, Dennis

2005-01-01

198

Is the outer Solar System chaotic?  

E-print Network

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.

Wayne B. Hayes

2007-02-07

199

Commissioning of the 4 K Outer Cryostat for the CUORE Experiment  

NASA Astrophysics Data System (ADS)

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.

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

200

Sound Transmission through Cylindrical Shell Structures Excited by Boundary Layer Pressure Fluctuations  

NASA Technical Reports Server (NTRS)

This paper examines sound transmission into two concentric cylindrical sandwich shells subject to turbulent flow on the exterior surface of the outer shell. The interior of the shells is filled with fluid medium and there is an airgap between the shells in the annular space. The description of the pressure field is based on the cross-spectral density formulation of Corcos, Maestrello, and Efimtsov models of the turbulent boundary layer. The classical thin shell theory and the first-order shear deformation theory are applied for the inner and outer shells, respectively. Modal expansion and the Galerkin approach are used to obtain closed-form solutions for the shell displacements and the radiation and transmission pressures in the cavities including both the annular space and the interior. The average spectral density of the structural responses and the transmitted interior pressures are expressed explicitly in terms of the summation of the cross-spectral density of generalized force induced by the boundary layer turbulence. The effects of acoustic and hydrodynamic coincidences on the spectral density are observed. Numerical examples are presented to illustrate the method for both subsonic and supersonic flows.

Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

1996-01-01

201

Prevention of the Outer Space Weaponization  

NASA Astrophysics Data System (ADS)

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

Zhukov, Gennady P.

2002-01-01

202

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

Microsoft Academic Search

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

Barbara M. Gilchrist

1978-01-01

203

Proceedings of the 6th International Conference on Computation of Shell and Spatial Structures  

E-print Network

-elliptic toroidal shells. Stomata are the regulating valve in the seminal issue of water and carbon dioxide the constraints of physics, so this expansion is direct. As the tools of engineering evolve and mature, especially impervious outer surface. In many respects this is analogous to the thermal #12;6th International Conference

Rand, Richard H.

204

Statistical theory of correlations in random packings of hard particles.  

PubMed

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

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

2014-05-01

205

Statistical theory of correlations in random packings of hard particles  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

206

SUPER HARD SURFACED POLYMERS  

SciTech Connect

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.

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

207

Outer radiation belt variations during 1995  

Microsoft Academic Search

The dynamics of the relativistic electron flux in the earth's outer radiation belt measured by the Radiation Environment Monitor aborad the STRV-1B satellite is presented from August 1994 to end of April 1996. During this period the earth's magnetosphere was driven by recurrent fast solar wind streams which had periodically compressed the magnetosphere and caused large variations of the trapped

L. Desorgher; P. Bühler; A. Zehnder; E. Daly; L. Adams

1998-01-01

208

BIOREACTOR DESIGN - OUTER LOOP LANDFILL, LOUISVILLE, KY  

EPA Science Inventory

Bioreactor field demonstration projects are underway at the Outer Loop Landfill in Louisville, KY, USA. The research effort is a cooperative research effort between US EPA and Waste Management Inc. Two primary kinds of municipal waste bioreactors are under study at this site. ...

209

The Outer Planets\\/Solar Probe Project  

Microsoft Academic Search

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

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

1999-01-01

210

The processing of materials in outer space  

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

211

THE ORBITS OF THE OUTER URANIAN SATELLITES  

SciTech Connect

We report on the numerically integrated orbits for the nine outer Uranian satellites. The orbits are calculated based on fits to the astrometric observations for the period from 1984 to 2006. The results include the state vectors, post-fit residuals, and mean orbital elements. We also assess the accuracy of the orbital fits and discuss the need for future measurements.

Brozovic, M.; Jacobson, R. A. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)], E-mail: marina.brozovic@jpl.nasa.gov

2009-04-15

212

Ground Based Studies of the Outer Planets  

NASA Technical Reports Server (NTRS)

This report covers progress to date under this grant on our continuing program to conduct ground based studies of the outer solar system planets and satellites, with emphasis on spectroscopy and atmospheric phenomena. The research continues under our new PAST grant, NNG04G131G beginning 5/1/2004. The original period of performance of the subject grant was 3/1/2001 to 2/28/2004, but was extended one year at no cost. Although there is some overlap in the scientific projects conducted during the extended year with those of the new grant, this report is confined to the portion of the work funded under NAG5-10435. The primary goals for this grant period were a comparative study of outer planet thermospheres/ionospheres near solar maximum, extended to the mid-IR, and the investigation of molecular dimers in outer solar system atmospheres. This project supports NASA's planned space missions, Jupiter Polar Orbiter, outer Planet Microprobes, and the recent Cassini flyby of Jupiter. It also supports the OSS strategic plan themes, The Exploration of the Solar System and The Sun-Earth Connection/ Understanding comparative planetary space environments.

Trafton, Laurence M.

2005-01-01

213

The magnetospheres of the outer planets  

SciTech Connect

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.

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

1991-01-01

214

Sensational spherical shells  

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

215

Local hardness equalization and the principle of maximum hardness.  

PubMed

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

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

2013-06-01

216

Effect of shells on photoluminescence of aqueous CdTe quantum dots  

SciTech Connect

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.

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

2013-07-15

217

Biomechanics of Turtle Shells: How Whole Shells Fail in  

E-print Network

Biomechanics of Turtle Shells: How Whole Shells Fail in Compression PAUL M. MAGWENE1 AND JOHN J of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois The turtle shell serves an obvious function--protection. The defensive value of a wellossified system of plates surrounding soft tissues

Socha, Jake

218

Outer-shell excitation mechanisms and static-mode laser-fluorescence spectroscopy of sputtered atoms  

SciTech Connect

A review of the literature on atoms sputtered in electronically excited states is given together with a discussion of various mechanisms that have been proposed to account for the observations. The major observational features that have emerged from the older studies may be summarized as follows: (1) the kinetic energies of neutral atoms in highly excited electronic states are 1-2 orders of magnitude greater than E/sub b/, the surface binding energy; (2) relative yields show approximately exponential dependence on excitation energy with characteristic temperatures measured in thousands of degrees; (43) absolute yields are lower by 2-3 orders of magnitude than secondary ion yields which themselves are usually very small compared to total sputtering yields. In many cases, excited-state yields increase 1-2 orders of magnitude as a result of surface oxidation. 83 references.

Gruen, D.M.; Pellin, M.J.; Young, C.E.; Mendelsohn, M.H.; DeWald, A.B.

1982-01-01

219

Palaeoecology and evolution of marine hard substrate communities  

NASA Astrophysics Data System (ADS)

Marine organisms have occupied hard substrates since the Archaean. Shells, rocks, wood and sedimentary hardgrounds offer relatively stable habitats compared to unconsolidated sediments, but the plants and animals which inhabit them must develop means to gain and defend this premium attachment space. Hard substrate communities are formed by organisms with a variety of strategies for adhering to and/or excavating the substrates they inhabit. While mobile grazers, organically attached and even soft-bodied organisms may leave evidence of their former presence in ancient hard substrate communities, a superior fossil record is left by sessile encrusters with mineralised skeletons and by borers which leave trace fossils. Furthermore, encrusters and borers are preserved in situ, retaining their spatial relationships to one another and to the substrate. Spatial competition, ecological succession, oriented growth, and differential utilisation of exposed vs. hidden substrate surfaces can all be observed or inferred. Hard substrate communities are thus excellent systems with which to study community evolution over hundreds of millions of years. Here we review the research on modern and ancient hard substrate communities, and point to some changes that have affected them over geological time scales. Such changes include a general increase in bioerosion of hard substrates, particularly carbonate surfaces, through the Phanerozoic. This is, at least in part, analogous to the infaunalisation trends seen in soft substrate communities. Encrusting forms show an increase in skeletalisation from the Palaeozoic into the Mesozoic and Cenozoic, which may be a response to increasing levels of predation. Hard substrate communities, considering borers and encrusters together, show a rough increase in tiering through the Phanerozoic which again parallels trends seen in soft substrate communities. This extensive review of the literature on living and fossil hard substrate organisms shows that many opportunities remain for large-scale studies of trends through time at the community and clade levels. Palaeontologists will especially benefit by closer integration of their work with that of neontologists, particularly in aspects of ecology such as larval recruitment, competition and succession.

Taylor, P. D.; Wilson, M. A.

2003-07-01

220

Particle self-assembly on soft elastic shells  

E-print Network

We use numerical simulations to show how noninteracting hard particles binding to a deformable elastic shell may self-assemble into a variety of linear patterns. This is a result of the nontrivial elastic response to deformations of shells. The morphology of the patterns can be controlled by the mechanical properties of the surface, and can be fine-tuned by varying the binding energy of the particles. We also repeat our calculations for a fully flexible chain and find that the chain conformations follow patterns similar to those formed by the nanoparticles under analogous conditions. We propose a simple way of understanding and sorting the different structures and relate it to the underlying shape transition of the shell. Finally, we discuss the implications of our results.

Andela Šari?; Angelo Cacciuto

2010-10-12

221

Shell Creek Summers  

ERIC Educational Resources Information Center

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…

Seier, Mark; Goedeken, Suzy

2005-01-01

222

Agreement, Shells, and Focus.  

ERIC Educational Resources Information Center

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…

Simpson, Andrew; Wu, Zoe

2002-01-01

223

Snail Shell Science.  

ERIC Educational Resources Information Center

Presents three inquiry-based lessons to develop the science process skills of observation, identification, and classification. Activities use whelk eggs and snail shells as the focus of the students' inquiries. Provides a list of 19 facts about whelks and snails. (MDH)

Matthews, Catherine

1992-01-01

224

Design of multiple-shell gas nozzles for refurbished Z.  

SciTech Connect

This paper presents initial designs of multiple-shell gas puff imploding loads for the refurbished Z generator. The nozzle has three independent drivers for three independent plena. The outer and middle plena may be charged to 250psia whilst the central jet can be charged to 1000psia. 8-cm and 12-cm outer diameter nozzles have been built and tested on the bench. The unique valve design provides a very fast opening, hence the amount of stray gas outside the core nozzle flow is minimized. A similar 8-cm nozzle was characterized earlier using a fiber optic interferometer, but at lower pressures and without the central jet. Those data have been scaled to the higher pressures required for refurbished Z and used to estimate performance. The use of three independent plena allows variation of the pressure (hence mass distribution) in the nozzle flow, allowing optimization of implosion stability and the on-axis mass that most contributes to K-shell emission. Varying the outer/middle mass ratios influences the implosion time and should affect the details of the assembly on axis as well as the radiation physics. Varying the central jet pressure will have a minor effect on implosion dynamics, but a strong effect on pinch conditions and radiation physics. Optimum mass distributions for planned initial Ar shots on refurbished Z are described. Additional interferometer data including the central jet and at higher pressures will also be presented.

Giuliani, J. L. (Naval Research Laboratory, Washington DC); Waisman, Eduardo Mario; Velikovich, Aleksandr Lazarevich (Naval Research Laboratory, Washington DC); Madden, R. (Alameda Applied Sciences Corporation, San Leandro, CA); Thornhill, W. (Naval Research Laboratory, Washington DC); Ampleford, David J.; Krishnan, Mahadevan (Alameda Applied Sciences Corporation, San Leandro, CA); Coleman, P. L.; Cuneo, Michael Edward; Wilson Elliott, Kristi (Alameda Applied Sciences Corporation, San Leandro, CA); Coverdale, Christine Anne; Clark, R. (Naval Research Laboratory, Washington DC); Jones, Brent Manley

2010-06-01

225

Hard metal composition  

DOEpatents

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.

Sheinberg, H.

1983-07-26

226

Hard metal composition  

DOEpatents

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.

Sheinberg, Haskell (Los Alamos, NM)

1986-01-01

227

Hard physics in PHENIX  

E-print Network

We review recent results on hard observables in p+p, d+A and A+A collisions obtained by the PHENIX experiment. Emphasis is put on those measurements that provide insight into the properties of hot QCD media expected to be created in nucleus-nucleus collisions at RHIC energies. Direct photon spectra, jet properties and heavy quarks production measured in p+p and d+Au collisions are compared to the same observables extracted in heavy ion collisions to find modifications due to the presence of hot QCD matter.

D. Peressounko; for the PHENIX collaboration

2005-12-08

228

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.

2012-10-12

229

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2013 CFR

...2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the...

2013-01-01

230

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2010 CFR

...2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the...

2010-01-01

231

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2014 CFR

...2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the...

2014-01-01

232

7 CFR 51.2002 - Split shell.  

Code of Federal Regulations, 2011 CFR

...2002 Split shell. Split shell means a shell having any crack which is open and conspicuous for a distance of more than one-fourth the circumference of the shell, measured in the direction of the...

2011-01-01

233

Recent Advances in Shell Evolution with Shell-Model Calculations  

E-print Network

Shell evolution in exotic nuclei is investigated with large-scale shell-model calculations. After presenting that the central and tensor forces produce distinctive ways of shell evolution, we show several recent results: (i) evolution of single-particle-like levels in antimony and cupper isotopes, (ii) shape coexistence in nickel isotopes understood in terms of configuration-dependent shell structure, and (iii) prediction of the evolution of the recently established $N=34$ magic number towards smaller proton numbers. In any case, large-scale shell-model calculations play indispensable roles in describing the interplay between single-particle character and correlation.

Yutaka Utsuno; Takaharu Otsuka; Yusuke Tsunoda; Noritaka Shimizu; Michio Honma; Tomoaki Togashi; Takahiro Mizusaki

2014-09-16

234

Natural melting within a spherical shell  

NASA Technical Reports Server (NTRS)

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.

Bahrami, Parviz A.

1990-01-01

235

Outer radiation belt variations during 1995  

NASA Astrophysics Data System (ADS)

The dynamics of the relativistic electron flux in the earth's outer radiation belt measured by the Radiation Environment Monitor aboard the STRV-1B satellite is presented from August 1994 to end of April 1996. During this period the earth's magnetosphere was driven by recurrent fast solar wind streams which had periodically compressed the magnetosphere and caused large variations of the trapped particle fluxes in the outer radiation belt. The periodic variations are characterized by a rapid depletion, strong and rapid increase and a more steady phase. The flux level reached depends on the velocity of the interacting solar wind stream. The effectiveness of the solar wind - magnetosphere interaction shows a semiannual modulation with a maximum during the equinoxes.

Desorgher, L.; Bühler, P.; Zehnder, A.; Daly, E.; Adams, L.

236

Origins of outer-planet satellites  

NASA Technical Reports Server (NTRS)

Aspects of satellite origin and evolution which bear on the formation of the solar system are addressed, with emphasis on the chemical evidence contained in satellites concerning the modification of the interstellar material which went to form the solar system. New results on the tidal evolution of outer-planet satellite systems are presented. The gross physical and chemical properties of the satellite systems of the outer planets are outlined. Models for regular satellite formation are reviewed. Attention is given to the evolution of the satellites, with emphasis on tidal evolution, including a discussion of the dynamical origin of Triton. The volatile budgets of Titan, Triton, and Pluto/Charon are discussed, and models are presented for the origin of these budgets which tie them to the larger set of processes associated with solar system formation.

Lunine, Jonathan I.; Tittemore, William C.

1993-01-01

237

Performance of the LHCb Outer Tracker  

NASA Astrophysics Data System (ADS)

The LHCb Outer Tracker is a gaseous detector covering an area of 5 × 6 m2 with 12 double layers of straw tubes. The detector with its services are described together with the commissioning and calibration procedures. Based on data of the first LHC running period from 2010 to 2012, the performance of the readout electronics and the single hit resolution and efficiency are presented. The efficiency to detect a hit in the central half of the straw is estimated to be 99.2%, and the position resolution is determined to be approximately 200 ?m. The Outer Tracker received a dose in the hottest region corresponding to 0.12 C/cm, and no signs of gain deterioration or other ageing effects are observed.

2014-01-01

238

Dust Measurements in the Outer Solar System  

Microsoft Academic Search

Dust measurements in the outer solar system are reviewed. Only the plasma wave instrument on board Voyagers 1 and 2 recorded\\u000a impacts in the Edgeworth-Kuiper belt (EKB). Pioneers 10 and 11 measured a constant dust flux of 10-micron-sized particles\\u000a out to 20 AU. Dust detectors on board Ulysses and Galileo uniquely identified micron-sized interstellar grains passing through\\u000a the planetary system.

Eberhard Grün; Harald Krüger; Markus Landgraf

1993-01-01

239

Dust Measurements in the Outer Solar System  

Microsoft Academic Search

Dust measurements in the outer solar system are reviewed. Only the plasma wave instrument on board Voyagers 1 and 2 recorded impacts in the Edge- worth-Kuiper belt (EKB). Pioneers 10 and 11 measured a constant dust flux of 10- micron-sized particles out to 20 AU. Dust detectors on board Ulysses and Galileo uniquely identified micron-sized interstellar grains passing through the

Eberhard Grun; Harald Kruger; Markus Landgraf

1994-01-01

240

Environments in the Outer Solar System  

Microsoft Academic Search

The outer planets of our solar system Jupiter, Saturn, Uranus, and Neptune are fascinating objects on their own. Their intrinsic\\u000a magnetic fields form magnetic environments (so called magnetospheres) in which charged and neutral particles and dust are\\u000a produced, lost or being transported through the system. These magnetic environments of the gas giants can be envisaged as\\u000a huge plasma laboratories in

N. Krupp; K. K. Khurana; L. Iess; V. Lainey; T. A. Cassidy; M. Burger; C. Sotin; F. Neubauer

2010-01-01

241

Photopolarimetry team outer planets mission definition phase  

NASA Technical Reports Server (NTRS)

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.

1972-01-01

242

Spitzer Mapping of the Outer Galaxy (SMOG)  

Microsoft Academic Search

We propose mapping a 21 square degree area with IRAC and MIPS of a representative region of the outer Galaxy (l=102-109, b=0-3). From these data and previous and future surveys in the submillimeter and millimeter, the specifics (rate, IMF) of star formation of the survey region will be measured. This direct measurement of the star formation efficiency will then be

Sean Carey; Babar Ali; Bruce Berriman; Francois Boulanger; Chris Brunt; Roc Cutri; Nicolas Flagey; Steven Gibson; Mark Heyer; Joe Hora; Remy Indebetouw; Kathleen Kraemer; Thomas Kuchar; Bill Latter; Francine Marleau; Marc-Antoine Miville-Deschenes; Don Mizuno; Sergio Molinari; Alberto Noriega-Crespo; Deborah Padgett; Roberta Paladini; Stephan Price; Luisa Rebull; Lee Rottler; Sachin Shenoy; Russ Shipman; Leonardo Testi

2008-01-01

243

Planetary magnetism in the outer solar system.  

NASA Technical Reports Server (NTRS)

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.

Sonett, C. P.

1973-01-01

244

Fluxgate magnetometers for outer planets exploration  

Microsoft Academic Search

The exploration of the interplanetary medium and the magnetospheres of the outer planets requires the implementation of magnetic field measuring instrumentation with wide dynamic range, high stability, and reliability. The fluxgate magnetometers developed for the Pioneer 11 and Mariner-Jupiter-Saturn missions are presented. These instruments cover the range of .01 nT to2 times 10^{6}nT with optimum performance characteristics and low power

M. Acuna

1974-01-01

245

Imaging of the outer planets and satellites.  

NASA Technical Reports Server (NTRS)

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.

Murray, B. C.

1973-01-01

246

Electrodynamics of Outer-Gap Accelerator  

NASA Astrophysics Data System (ADS)

We investigate a stationary pair production cascade in the outer magnetosphere of a spinning neutron star. We first demonstrate that the Maxwell equation for the electrostatic potential prohibits our applying the original vacuum solution obtained by Cheng, Ho, and Ruderman (1986, ApJ 300, 500) to realistic non-vacuum outer-gap models conventionally considered. We then solve the Maxwell equation together with the Boltzmann equations for particles and gamma-rays and show that (1) the gap will not be quenched by the externally injected current at nearly Goldreich-Julian rate, (2) the gap position shifts as a function of the injected current, (3) the particle energy distribution cannot be expressed by a power-law, (4) the superposition of the curvature gamma-rays emitted at various points forms the observed power-law spectra of individual gamma-ray pulsars, (5) the gamma-ray luminosity is naturally proportional to the square root of the spin-down luminosity for young pulsars and will evolve to be proportional to the spin-down one for middle-aged or older pulsars, (6) the observed relationship between gamma-ray and spin-down luminosities merely reflects the unsaturated motion of the emitting particles and hence does not discriminate the gap position (whether in the outer or the inner magnetosphere).

Hirotani, K.; Harding, A. K.; Shibata, S.

2003-03-01

247

CLOSURE WELD DEVELOPMENT FOR 3013 OUTER CONTAINERS  

SciTech Connect

Excess plutonium materials in the DOE complex are packaged and stored in accordance with DOE-STD-3013. This standard specifies requirements for the stabilization of such materials and subsequent packaging in dual nested seal-welded containers. Austenitic stainless steels have been selected for container fabrication. The inner 3013 container provides contamination control while the outer 3013 container is the primary containment vessel and is the focus of this paper. Each packaging site chose a process for seal welding the outer 3013 containers in accordance with its needs and expertise. The two processes chosen for weld closure were laser beam welding (LBW) and gas tungsten arc welding (GTAW). Following development efforts, each system was qualified in accordance with DOE-STD-3013 prior to production use. The 3013 outer container closure weld joint was designed to accommodate the characteristics of a laser weld. This aspect of the joint design necessitated some innovative process and equipment considerations in the application of the GTAW process. Details of the weld requirements and the development processes are presented and several potential enhancements for the GTAW system are described.

Daugherty, W.; Howard, S.; Peterson, K.; Stokes, M.

2009-11-10

248

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

NASA Technical Reports Server (NTRS)

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.

Schenk, Paul M.

2002-01-01

249

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

PubMed

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

Schenk, Paul M

2002-05-23

250

Engineering Bacterial Microcompartment Shells: Chimeric Shell Proteins and Chimeric Carboxysome Shells.  

PubMed

Bacterial microcompartments (BMCs) are self-assembling organelles composed entirely of protein. Depending on the enzymes they encapsulate, BMCs function in either inorganic carbon fixation (carboxysomes) or organic carbon utilization (metabolosomes). The hallmark feature of all BMCs is a selectively permeable shell formed by multiple paralogous proteins, each proposed to confer specific flux characteristics. Gene clusters encoding diverse BMCs are distributed broadly across bacterial phyla, providing a rich variety of building blocks with a predicted range of permeability properties. In theory, shell permeability can be engineered by modifying residues flanking the pores (symmetry axes) of hexameric shell proteins or by combining shell proteins from different types of BMCs into chimeric shells. We undertook both approaches to altering shell properties using the carboxysome as a model system. There are two types of carboxysomes, ? and ?. In both, the predominant shell protein(s) contain a single copy of the BMC domain (pfam00936), but they are significantly different in primary structure. Indeed, phylogenetic analysis shows that the two types of carboxysome shell proteins are more similar to their counterparts in metabolosomes than to each other. We solved high resolution crystal structures of the major shell proteins, CsoS1 and CcmK2, and the presumed minor shell protein CcmK4, representing both types of cyanobacterial carboxysomes and then tested the interchangeability. The in vivo study presented here confirms that both engineering pores to mimic those of other shell proteins and the construction of chimeric shells is feasible. PMID:25117559

Cai, Fei; Sutter, Markus; Bernstein, Susan L; Kinney, James N; Kerfeld, Cheryl A

2014-08-27

251

The Shell Island Dilemma  

NSDL National Science Digital Library

The objective of this inquiry simulation is to investigate the issues concerning the fate of the Shell Island Resort, which is in danger of being destroyed by a migrating inlet, and then debate the future of this and other oceanfront structures threatened by coastal erosion. As students engage in their investigation, they are asked to identify the social, political, and scientific issues with which different stakeholders must deal. They will place themselves into the role of one of the stakeholders. The site lists the stakeholders and provides several sources of information for each. After reviewing the resources, students will prepare a statement to decide what should be the next course of action regarding the Shell Island Resort. Students then will present statements in a debate to decide the future of the resort.

252

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

PubMed Central

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

Deheyn, Dimitri D.; Wilson, Nerida G.

2011-01-01

253

Extending synchrotron-based atomic physics experiments into the hard X-ray region  

SciTech Connect

The high-brightness, hard x-ray beams available from third-generation synchrotron sources are opening new opportunities to study the deepest inner shells of atoms, an area where little work has been done and phenomena not observed in less tightly bound inner-shells are manifested. In addition scattering processes which are weak at lower energies become important, providing another tool to investigate atomic structure as well as an opportunity to study photon/atom interactions beyond photoabsorption. In this contribution the authors discuss some of the issues related to extending synchrotron-based atomic physics experiments into the hard x-ray region from the physical and the experimental point of view. They close with a discussion of a technique, resonant Raman scattering, that may prove invaluable in determining the spectra of the very highly-excited states resulting from the excitation of deep inner shells.

LeBrun, T. [Argonne National Lab., IL (United States). Physics Div.

1996-12-31

254

Thermomechanical Postbuckling of Shells  

NASA Technical Reports Server (NTRS)

A number of issues involving the postbuckling of doubly-curved panels exposed to a non-uniform temperature field and subjected to a system of mechanical loads are considered in this paper. Effects played by transverse shear, initial geometric imperfections, membrane and thickness-wise temperature gradient, tangential edge constraints, linear/non-linear elastic foundation are incorporated and their implications on the non-linear response behavior of shells are discussed. Issues related with the delay of the occurrence of the snap-through buckling, alleviation of its intensity and even with its removal are addressed and remarks on conditions rendering a curved panel insensitive to initial geometric imperfections are included. Results on small vibration of shells about sub- and post-critical ranges are provided and structural modeling issues playing a non-negligible role towards a reliable prediction of the postbuckling behavior of shells under complex loading conditions are discussed. Results on non-linear response of flat reinforced panels subjected to thermomechanical loads are also presented. Finally, problems not covered by this article are briefly indicated.

Librescu, Liviu

1998-01-01

255

Drift shells and aurora computed using the O8 magnetic field model for Neptune  

NASA Technical Reports Server (NTRS)

Charged particle drift shells are calculated using the O8 magnetic field model for Neptune. Inner drift shell morphologies differ significantly from dipolar drift shells for the parts of drift shells inward of r = 2 R(sub N). Outer drift shells (L approx. greater than 10), when traced down to Neptune's surface following magnetic field lines, are simple closed loops around magnetic poles. Inner drift shells (L approx. less than 4), on the other hand, when traced to the surface, are also single loops but stretched in a previously unknown way: sometimes with a cusp and sometimes into two joined loops. Inner drift shell footprints on R = 1 provide the basis for identifying precipitation L shells, interpreting observed aurora, and predicting additional emissions on that part of Neptune's surface unobserved by the Ultraviolet Spectrometer (UVS). Precipitation in a global magnetic anomaly, `ordinary' auroral precipitation near the south magnetic pole, and precipitation from field lines with no magnetic field minimum above Neptune's exobase collectively appear to account for all of the observed auroral emission regions at Neptune. To the extent that aurora can be understood in this model, it is suggested O8 may be reasonably accurate.

Paranicas, C.; Cheng, A. F.

1994-01-01

256

HST/ACS observations of shell galaxies: inner shells, shell colours and dust  

NASA Astrophysics Data System (ADS)

Context: Shells in Elliptical Galaxies are faint, sharp-edged features, believed to provide evidence for a merger event. Accurate photometry at high spatial resolution is needed to learn on presence of inner shells, population properties of shells, and dust in shell galaxies. Aims: Learn more about the origin of shells and dust in early type galaxies. Methods: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. Results: The ACS images reveal shells well within the effective radius in some galaxies (at 0.24 re = 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. Conclusions: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO9399 and GO9427. Appendices are only available in electronic form at http://www.aanda.org

Sikkema, G.; Carter, D.; Peletier, R. F.; Balcells, M.; Del Burgo, C.; Valentijn, E. A.

2007-06-01

257

33 CFR 117.323 - Outer Clam Bay.  

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false Outer Clam Bay. 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2013-07-01

258

33 CFR 117.323 - Outer Clam Bay  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Outer Clam Bay 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2012-07-01

259

33 CFR 117.323 - Outer Clam Bay  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Outer Clam Bay 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2010-07-01

260

33 CFR 117.323 - Outer Clam Bay  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Outer Clam Bay 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2011-07-01

261

33 CFR 117.323 - Outer Clam Bay.  

Code of Federal Regulations, 2014 CFR

...2014-07-01 2014-07-01 false Outer Clam Bay. 117.323 Section 117.323 Navigation...Specific Requirements Florida § 117.323 Outer Clam Bay. The drawspan of the Outer Clam Bay Boardwalk Drawbridge shall open on...

2014-07-01

262

Enzymatic properties and cholesterol content of mitochondrial outer mem-  

E-print Network

Enzymatic properties and cholesterol content of mitochondrial outer mem- branes in liver of obese and microsomes. Simultaneously microsomes were shown to be richer in cholesterol than mitochondrial outer, it was determined that outer membranes are extremely poor in cholesterol, far richer in to- tal fatty acids than

Boyer, Edmond

263

Scientific Goals for Exploration of the Outer Solar System  

E-print Network

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

Rathbun, Julie A.

264

Scientific Goals for Exploration of the Outer Solar System  

E-print Network

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

Rathbun, Julie A.

265

STELLAR POPULATIONS IN THE OUTER HALO OF THE MASSIVE ELLIPTICAL M49  

SciTech Connect

We use deep surface photometry of the giant elliptical M49 (NGC 4472), obtained as part of our survey for diffuse light in the Virgo Cluster, to study the stellar populations in its outer halo. Our data trace M49's stellar halo out to {approx}100 kpc (7r{sub e}), where we find that the shallow color gradient seen in the inner regions becomes dramatically steeper. The outer regions of the galaxy are quite blue (B - V {approx} 0.7); if this is purely a metallicity effect, it argues for extremely metal-poor stellar populations with [Fe/H] < -1. We also find that the extended accretion shells around M49 are distinctly redder than the galaxy's surrounding halo, suggesting that we are likely witnessing the buildup of both the stellar mass and metallicity in M49's outer halo due to late time accretion. While such growth of galaxy halos is predicted by models of hierarchical accretion, this growth is thought to be driven by more massive accretion events which have correspondingly higher mean metallicity than inferred for M49's halo. Thus the extremely metal-poor nature of M49's extended halo provides some tension against current models for elliptical galaxy formation.

Mihos, J. Christopher; Harding, Paul [Department of Astronomy, Case Western Reserve University, 10900 Euclid Ave, Cleveland, OH 44106 (United States); Rudick, Craig S. [Institute for Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland); Feldmeier, John J., E-mail: mihos@case.edu, E-mail: paul.harding@case.edu, E-mail: craig.rudick@phys.ethz.ch, E-mail: jjfeldmeier@ysu.edu [Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States)

2013-02-20

266

Three-dimensional structure of single-shelled bluetongue virus.  

PubMed Central

The three-dimensional structure of single-shelled bluetongue virus has been determined to a resolution of 3 nm by using electron cryomicroscopy and image-processing techniques. The single-shelled virion has a diameter of 69 nm. The three-dimensional structure of the virion has icosahedral symmetry with a triangulation number of 13 in a left-handed configuration. The three-dimensional structure can be described in terms of two concentric layers of density surrounding a central core density. Two distinctive features of the outer layer are the 260 knobby capsomeres located at all the local and strict threefold axes and the aqueous channels located at all the five- and six-coordinated positions. These protrusions extend outward from an inner radius of 28 nm. They are interconnected out to a radius of 30 nm by saddle-shaped densities across the local and strict twofold axes. The aqueous channels surrounded by these capsomeres are about 8 nm wide at the outer surface and 8 nm deep. Some of these channels extend inward, penetrating the inner layer. These channels may provide pathways for transporting the metabolites and mRNA during the transcriptase activity of the particles. The inner layer is a featureless smooth bed of density except for the indentations in register with the channels of the outer layer. We propose that the 260 capsomeres in the outer layer are made up of trimers of the major protein, VP7, and that the inner layer is composed of the second major protein, VP3. The density in the central portion of the structure at a radius of less than 21 nm is likely due to the minor proteins and the genomic RNA. Images PMID:1312624

Prasad, B V; Yamaguchi, S; Roy, P

1992-01-01

267

Dark matter in the outer solar system  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

268

Outer atmospheres of giant and supergiant stars  

NASA Technical Reports Server (NTRS)

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.

Brown, A.

1984-01-01

269

Marginally outer trapped surfaces in higher dimensions  

NASA Astrophysics Data System (ADS)

We review the basic setup of Kaluza-Klein theory, namely a five-dimensional vacuum with a cyclic isometry, which corresponds to Einstein-Maxwell-dilaton theory in four-dimensional spacetime. We first recall the behaviour of Killing horizons under bundle lift and projection. We then show that the property of compact surfaces of being (stably) marginally trapped is preserved under lift and projection provided the appropriate (‘Pauli’) conformal scaling is used for the spacetime metric. We also discuss and compare recently proven area inequalities for stable axially symmetric two-dimensional and three-dimensional marginally outer trapped surfaces.

Tim-Torben, Paetz; Simon, Walter

2013-12-01

270

Meridional plasma flow in the outer heliosphere  

NASA Technical Reports Server (NTRS)

Voyager 2 observations made in the outer heliosphere near 25 AU and within 2 deg of the heliographic equatorial plane show periodic variations in the meridional (North/South) flow velocities that are much more prominent than the East/West variations. An autocorrelation analysis shows that the flow variation has a period of about 25.5 days in the latter half of 1986, in approximate agreement with the solar rotation period. The results suggest that increased pressure in interaction regions remains the best candidate for the driver of the nonradial flows.

Lazarus, A. J.; Yedidia, B.; Villanueva, L.; Mcnutt, R. L., Jr.; Belcher, J. W.; Villante, U.; Burlaga, L. F.

1988-01-01

271

High energy-resolution electron energy-loss spectroscopy study of the dielectric properties of multi-shell nanoparticles.  

PubMed

Nanoparticles, which have multi-shell structure, are expected to be stable and high efficient for the light-emitting devices. The efficiency of luminescence is considered to be affected by the multi-shell structure. In order to understand the mechanism of high efficiency luminescence, it is necessary to evaluate the multi-shell structure and dielectric properties from each particle. High energy-resolution electron energy-loss spectroscopy (HR-EELS) based on TEM is a powerful tool for this purpose. By comparing between the experimental and the simulated results, it is possible to evaluate the effect of the size and physical property of each shell material on the dielectric properties of multi-shell nanoparticles. In this study, simulations of EELS spectra of multi-shell nanoparticle (core: CdSe, inner shell: CdS, outer shell: ZnS) and mono-shell nanoparticle (core: CdSe, shell: CdS) were conducted by the dielectric continuum theory[1].Figure 1 shows calculated EELS spectra of multi and mono shell nanoparticles. The spectra are calculated from dielectric functions of single CdSe, CdS and ZnS crystals, which were experimentally derived from HR-EELS spectra by using Kramers-Kronig analysis. The radius of 6.9 nm for the nanoparticle in the simulation corresponds to the average size of actual synthesized nanoparticles. Energy positions of arrows in the inset correspond to band gap energies of CdSe, CdS and ZnS[2]. In the spectrum of multi-shell nanoparticle, the intensity corresponding to interband transition near band gap of CdSe is suppressed comparing with that of the mono shell nanoparticle. This result indicates that ZnS outer shell affects the intensity profile of EELS spectrum near band gap. This effect should be sensitive for the thickness of the shells. Thus, there is a possibility that the effect of size and thickness of each core and shell on dielectric properties of multi-shell nanoparticles could be evaluated by using HR-EELS technique.jmicro;63/suppl_1/i18/DFU039F1F1DFU039F1Fig. 1.Calculated EELS spectra. PMID:25359810

Nakahigashi, Naoyuki; Sato, Yohei; Terauchi, Masami; Uehara, Masato

2014-11-01

272

Lunar and Planetary Science XXXV: Outer Solar System  

NASA Technical Reports Server (NTRS)

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.

2004-01-01

273

Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer  

PubMed Central

Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging. PMID:23962025

2013-01-01

274

Fabrication of bifunctional core-shell Fe3O4 particles coated with ultrathin phosphor layer  

NASA Astrophysics Data System (ADS)

Bifunctional monodispersed Fe3O4 particles coated with an ultrathin Y2O3:Tb3+ shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe3O4 core and outer Y2O3:Tb3+ shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging.

Atabaev, Timur Sh; Kim, Hyung-Kook; Hwang, Yoon-Hwae

2013-08-01

275

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

276

Measuring the Hardness of Minerals  

ERIC Educational Resources Information Center

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…

Bushby, Jessica

2005-01-01

277

Velocity moments in the outer nightside magnetodisk of Saturn  

NASA Astrophysics Data System (ADS)

Saturn has a huge rotating magnetosphere, fields and particles exhibit rotational periodicities in all plasma parameters, the periods depend on epoch, elevation, etc. The rotating plasma forms a magnetodisk in the vicinity of the equatorial plane. Studies by Andrews et al. [2012] and Provan et al. [2012] have shown that magnetic field modulation in the northern and southern lobe have distinct and different periods (the well known northern and southern periods), whereas in the magnetodisk both periods are present and changing smoothly with the distance from the equatorial plane; near the current sheet the magnetic field exhibits dual periodicities, roughly of equal amplitudes. The disk has a complex shape depending on local time, seasons of Saturn, and external forces (SW), and it is tilted, possibly due to currents. The non-rigid rotation of the tilted disk imitates flapping, that is a periodic vertical motion in the outer magnetosphere for an observer such as Cassini. Wherever the central line intersects the radial component of the magnetic field, the radial component is about zero, and the ion densities reach their peak values [Szego et al., 2011]. The results of recent numerical simulations [Jia and Kivelson, 2012] show that in the magnetodisk of Saturn fluctuating magnetic field perturbations are accompanied by other oscillatory phenomena. They investigated the magnetotail response for a dual periodicity driver in the case when the solar wind flow was perpendicular to the rotation axis. It was demonstrated that the components of the flow velocity extracted at different radial distances plotted versus time exhibit periodic modulation. We have investigated periodicities in the azimuthal and latitudinal component of the flow velocities using the numerical ion moments derived from the measurements of Cassini Plasma Spectrometer [Thomsen et al, 2010]. Ramer et al. [2012] investigated these periodicities in the inner magnetosphere near the equatorial plane. We have found that the azimuthal velocities show oscillatory behavior in the outer magnetosphere. It was found that the dense plasma near the magnetic equator rotates around the planet at high speed, while the dilute plasma of higher latitudes of the north and south hemispheres is rotating significantly slower. This observed latitudinal gradient in the azimuthal speed as a function of the distance from the equatorial plane can be a direct consequence of the sub-corotation of the plasma in the outer magnetosphere; highest speeds occurring on field lines at lowest latitudes mapping the rapidly rotating inner regions of the plasmasheet, and the speed falling as one approaches the lobe, where the field lines are connected to far away strongly subcorotating plasma. This suggests a picture of the magnetodisk, in which each L-shell rotates more or less rigidly, but the rotation speed is decreasing with L increasing. The dayside magnetodisk structure differs in many respects from the properties observed nightside. We shall point out some of these differences.

Nemeth, Z.; Szego, K.; Foldy, L.; Kivelson, M. G.; Jia, X.; Ramer, K. M.; Cowley, S. W. H.; Provan, G.; Thomsen, M.

2013-09-01

278

Wrinkling of Pressurized Elastic Shells  

NASA Astrophysics Data System (ADS)

We study the formation of localized structures formed by the point loading of an internally pressurized elastic shell. While unpressurized shells (such as a ping-pong ball) buckle into polygonal structures, we show that pressurized shells are subject to a wrinkling instability. We study wrinkling in depth, presenting scaling laws for the critical indentation at which wrinkling occurs and the number of wrinkles formed in terms of the internal pressurization and material properties of the shell. These results are validated by numerical simulations. We show that the evolution of the wrinkle length with increasing indentation can be understood for highly pressurized shells from membrane theory. These results suggest that the position and number of wrinkles may be used in combination to give simple methods for the estimation of the mechanical properties of highly pressurized shells.

Vella, Dominic; Ajdari, Amin; Vaziri, Ashkan; Boudaoud, Arezki

2011-10-01

279

Environments in the Outer Solar System  

NASA Astrophysics Data System (ADS)

The outer planets of our solar system Jupiter, Saturn, Uranus, and Neptune are fascinating objects on their own. Their intrinsic magnetic fields form magnetic environments (so called magnetospheres) in which charged and neutral particles and dust are produced, lost or being transported through the system. These magnetic environments of the gas giants can be envisaged as huge plasma laboratories in space in which electromagnetic waves, current systems, particle transport mechanisms, acceleration processes and other phenomena act and interact with the large number of moons in orbit around those massive planets. In general it is necessary to describe and study the global environments (magnetospheres) of the gas giants, its global configuration with its large-scale transport processes; and, in combination, to study the local environments of the moons as well, e.g. the interaction processes between the magnetospheric plasma and the exosphere/atmosphere/magnetosphere of the moon acting on time scales of seconds to days. These local exchange processes include also the gravity, shape, rotation, astrometric observations and orbital parameters of the icy moons in those huge systems. It is the purpose of this chapter of the book to describe the variety of the magnetic environments of the outer planets in a broad overview, globally and locally, and to show that those exchange processes can dramatically influence the surfaces and exospheres/atmospheres of the moons and they can also be used as a tool to study the overall physics of systems as a whole.

Krupp, N.; Khurana, K. K.; Iess, L.; Lainey, V.; Cassidy, T. A.; Burger, M.; Sotin, C.; Neubauer, F.

2010-06-01

280

Radio Emissions from the Outer Heliosphere  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

281

SDC conceptual design: Scintillating fiber outer tracker  

SciTech Connect

The authors propose an all-scintillating fiber detector for the purpose of outer tracking for the SDC. The objectives of this tracking system are to: (1) provide a first level trigger for {vert_bar}{eta}{vert_bar} < 2.3 with sharp p{sub T} threshold with the ability to resolve individual beam crossings; (2) provide pattern recognition capability and momentum resolution which complements and extends the capabilities of the inner silicon tracking system; (3) provide three dimensional linkage with outer detection systems including the shower maximum detector, muon detectors, and calorimetry; (4) provide robust tracking and track-triggering at the highest luminosities expected at the SSC. The many attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. This property is exploited in the construction of a level 1 trigger sensitive to individual beam crossings.

Adams, D. [Rice Univ., Houston, TX (United States); Baumbaugh, A. [Fermi National Accelerator Lab., Batavia, IL (United States); Bird, F. [ed.] [Superconducting Super Collider Lab., TX (United States)] [and others; SDC Collaboration

1992-01-22

282

Hubble Space Telescope Imaging of Bipolar Nuclear Shells in the Disturbed Virgo Cluster Galaxy NGC 4438  

E-print Network

We present broadband and narrowband Hubble Space Telescope images of the central region of the heavily disturbed Virgo cluster galaxy NGC 4438 (Arp120), whose nucleus has been described as a type 1 LINER or dwarf Seyfert. Narrowband H-alpha and [NII] HST images reveal striking bipolar shell features, 1 kpc in projected length from end-to-end, which are likely the result of an outflow from the nuclear region experiencing a strong interaction with the ISM. While these outflow shells share similarities with those in some other starburst or AGN galaxies, these in NGC 4438 are notable because NGC 4438 harbors neither a luminous circumnuclear starburst nor a luminous AGN. The shells appear to be closed at their outer ends, suggesting that the outflow in NGC 4438 is dynamically younger than those in some other galaxies. The radio continuum emission is strongly enhanced near the outer ends of the shells, suggesting working surfaces arising from collimated nuclear outflows which have impacted and shocked the surrounding ISM. The 2 shells are quite different, as the northwestern (NW) shell is luminous and compact, while the southeastern (SE) shell is 2.5 times longer and much fainter, in both optical emission lines and the non-thermal radio continuum. The differences between the 2 shells may be attributed to a difference in ISM density on the 2 sides of the nuclear disk. Such an ISM asymmetry exists on larger scales in this heavily disturbed galaxy. At the base of the outflow is a nuclear source, which is the highest surface brightness source in the galaxy at optical wavelengths, We discuss whether the outflow is powered by a low luminosity AGN or a compact nuclear starburst.

Jeffrey D. P. Kenney; Elizabeth E. Yale

2001-12-04

283

Shell Creek Summers  

NSDL National Science Digital Library

What would motivate high school students to donate valuable summer vacation time to do science research?--the opportunity to make a difference! The Shell Creek Watershed Improvement Group (SCWIG) was formed to identify and promote needed conservation practices within a local watershed, and turned to the high school 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. Since 2002, for the past three summers, in this ongoing project, students collect water quality data and report their findings to the three involved community organizations.

Mark Seier

2005-04-01

284

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

PubMed Central

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.

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

2014-01-01

285

The jump-off velocity of an impulsively loaded spherical shell  

SciTech Connect

We consider a constant temperature spherical shell of isotropic, homogeneous, linearly elastic material with density {rho} and Lame coefficients {lambda} and {mu}. The inner and outer radii of the shell are r{sub i} and r{sub o}, respectively. We assume that the inside of the shell is a void. On the outside of the shell, we apply a uniform, time-varying pressure p(t). We also assume that the shell is initially at rest. We want to compute the jump-off time and velocity of the pressure wave, which are the first time after t = 0 at which the pressure wave from the outer surface reaches the inner surface. This analysis computes the jump-off velocity and time for both compressible and incompressible materials. This differs substantially from [3], where only incompressible materials are considered. We will consider the behavior of an impulsively loaded, exponentially decaying pressure wave p(t) = P{sub 0{sup e}}{sup -{alpha}t}, where {alpha} {ge} 0. We notice that a constant pressure wave P(t) = P{sub 0} is a special case ({alpha} = 0) of a decaying pressure wave. Both of these boundary conditions are considered in [3].

Chabaud, Brandon M. [Los Alamos National Laboratory; Brock, Jerry S. [Los Alamos National Laboratory

2012-04-13

286

MISTIC: Radiation hard ECRIS  

NASA Astrophysics Data System (ADS)

The ISAC RIB facility at TRIUMF utilizes up to 100 ?A from the 500 MeV H - cyclotron to produce RIB using the isotopic separation on line (ISOL) method. In the moment, we are mainly using a hot surface ion source and a laser ion source to produce our RIB. A FEBIAD ion source has been recently tested at ISAC, but these ion sources are not suitable for gaseous elements like N, O, F, Ne, … , A new type of ion source is then necessary. By combining a high frequency electromagnetic wave and a magnetic confinement, the ECRIS [R. Geller, Electron Cyclotron Resonance Ion Source and ECR Plasmas, Institute of Physics Publishing, Bristol, 1996], [1] (electron cyclotron resonance ion source) can produce high energy electrons essential for efficient ionization of those elements. To this end, a prototype ECRIS called MISTIC (monocharged ion source for TRIUMF and ISAC complex) has been built at TRIUMF using a design similar to the one developed at GANIL [GANIL (Grand Accélérateur National d'Ions Lourds), www.ganil.fr], [2] The high level radiation caused by the proximity to the target prevented us to use a conventional ECRIS. To achieve a radiation hard ion source, we used coils instead of permanent magnets to produce the magnetic confinement. Each coil is supplied by 1000 A-15 V power supply. The RF generator cover a frequency range from 2 to 8 GHz giving us all the versatility we need to characterize the ionization of the following elements: He, Ne, Ar, Kr, Xe, C, O, N, F. Isotopes of these elements are involved in star thermonuclear cycles and, consequently, very important for researches in nuclear astrophysics. Measures of efficiency, emittance and ionization time will be performed for each of those elements. Preliminary tests show that MISTIC is very stable over a large range of frequency, magnetic field and pressure.

Labrecque, F.; Lecesne, N.; Bricault, P.

2008-10-01

287

Off-Shell Supersymmetry  

E-print Network

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 an unconventional quantization rule such that a particle can only appear off-shell, while its contributions to quantum corrections behave exactly the same as in the usual quantum field theory. We apply this quantization rule solely to the sparticles in the 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 current experimental constraints from the indirect sparticle search are still applicable.

Chiu Man Ho; Nobuchika Okada

2015-01-08

288

Observations of two types of Pc 1-2 pulsations in the outer dayside magnetosphere  

NASA Astrophysics Data System (ADS)

Analysis of high time resolution magnetometer data from the Polar satellite and from an array of high-latitude ground stations in Antarctica has identified 20 simultaneously observed Pc 1-2 wave events in the outer dayside magnetosphere during the first 17 months of Polar operations. In contrast to most earlier satellite studies of Pc 1-2 waves, based on data from equatorial satellites near apogee which moved only slowly across L shells if at all, the initial orbit of Polar allowed it to rapidly cross outer magnetospheric L shells, but significantly away from the magnetic equator. Consistent with several previous studies of outer magnetospheric Pc 1-2 waves, the majority of these events (75%) were associated with significant compressions of the magnetosphere. Seven of the events occurred simultaneously in satellite and ground data, with wave bursts temporally associated with compressions. These events, most at L values > 9, confirm the suggestion of [1993] that the outer dayside magnetosphere is often near marginal stability for electromagnetic ion cyclotron (EMIC) wave generation, so waves can be stimulated by even modest magnetospheric compressions. However, 10 of the wave events (five associated with compressions, and five not) were highly localized in L shell. In these "spatially localized" cases, continuous wave emissions were seen on the ground for extended periods of time, while in space waves were observed for only a few minutes and occurred only in radially narrow regions. The noncompressional events, all spatially localized, appear to be the first examples identified in space of the class of wave events known as Pc 1-2, sustained narrowband emissions which have durations at high-latitude ground stations of the order of 10 hours in the day and dusk local time sectors. All 10 of the spatially localized events, whether compressional or not, followed intervals of at least 12 hours of sustained very quiet magnetospheric conditions. Energetic ion observations from Polar confirm earlier suggestions that drifting plasma sheet ions are the source of dayside Pc 1-2 waves in the outer dayside magnetosphere, but they also show different particle configurations for the spatially localized and temporally ordered event categories. Events in both categories occurred within radially extended regions with ring-like, moderately anisotropic distributions of ?5 keV protons and with deep minima in the flux distributions at energies <5 keV. However, spatially localized wave events occurred only in association with radially localized regions that also contained highly anisotropic fluxes of ˜0.5-3 keV protons, at a considerable distance from the magnetospheric boundary. In contrast, no such radial structure was evident in any of the temporally ordered events, or in three "uncertain" events. The association of the spatially localized events with highly structured populations of plasma sheet protons of keV and higher energies indicates an important but unanticipated role for these protons in destabilizing plasma in the outer dayside magnetosphere, possibly through increasing the local plasma beta near the magnetic equator.

Engebretson, M. J.; Peterson, W. K.; Posch, J. L.; Klatt, M. R.; Anderson, B. J.; Russell, C. T.; Singer, H. J.; Arnoldy, R. L.; Fukunishi, H.

2002-12-01

289

Hardness variability in commercial technologies  

SciTech Connect

The radiation hardness of commercial Floating Gate 256K E{sup 2}PROMs from a single diffusion lot was observed to vary between 5 to 25 krad(Si) when irradiated at a low dose rate of 64 mrad(Si)/s. Additional variations in E{sup 2}PROM hardness were found to depend on bias condition and failure mode (i.e., inability to read or write the memory), as well as the foundry at which the part was manufactured. This variability is related to system requirements, and it is shown that hardness level and variability affect the allowable mode of operation for E{sup 2}PROMs in space applications. The radiation hardness of commercial 1-Mbit CMOS SRAMs from Micron, Hitachi, and Sony irradiated at 147 rad(Si)/s was approximately 12, 13, and 19 krad(Si), respectively. These failure levels appear to be related to increases in leakage current during irradiation. Hardness of SRAMs from each manufacturer varied by less than 20%, but differences between manufacturers are significant. The Qualified Manufacturer`s List approach to radiation hardness assurance is suggested as a way to reduce variability and to improve the hardness level of commercial technologies.

Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G. [Sandia National Labs., Albuquerque, NM (United States)] [Sandia National Labs., Albuquerque, NM (United States)

1994-12-01

290

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

SciTech Connect

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.

Heiles, C.

1984-08-01

291

Managing Feedwater Heater Shell Thinning  

SciTech Connect

Thinning of feedwater heater (FWH) shells has become an important issue throughout the U.S. nuclear industry. The thinning occurs primarily in the vicinity of the extraction steam and drain inlet nozzles where two-phase steam/water mixtures enter the heater. The thinning can be general wall thinning over a large area or highly localized thinning in a limited area. Eventually, shell repairs become necessary to ensure integrity of the pressure boundary and personnel safety, and to restore compliance with the ASME pressure vessel code. Ideally, long-term monitoring of the thickness of FWH shells would allow for timely repairs before the wall thickness decreases below the ASME Code minimum wall thickness. However, since most plants did not start inspecting FWH shells until recently, the initial inspection may find shells that are thinned to near or below the ASME Code minimum wall thickness. Because the cost and manpower requirements for shell repairs can be significant, it is imperative that shell repairs provide a long-term solution and that they be implemented as a planned outage evolution. Accordingly, the approach to managing FWH shell thinning must provide sufficient advance warning of the need for repairs while ensuring safe operation until the permanent repair can be implemented. The approach outlined in this paper does both. Establish acceptance criteria to ensure safe, interim operation with thinned shells until a permanent repair can be implemented. Develop contingency plans for interim repairs should the inspections identify thinning below the interim acceptance criteria. Inspect FWH shells during a refueling outage or possibly during planned system outages or power reductions. If necessary, perform interim repairs to ensure safe operation until the next refueling outage. Develop and implement permanent repairs that will prevent shell thinning. (authors)

Simons, John W.; Keating, Robert B. [MPR Associates Inc., 140 Mustang Circle, Simpsonville, SC 29681 (United States)

2002-07-01

292

Development of polyvinyl alcohol shells overcoated with polystyrene layer for inertial confinement fusion experiments  

SciTech Connect

In inertial fusion experiments, the use of polymer shells provides more efficient ablative implosion and significantly reduced radiation preheat compared with the glass shells currently used. We have developed a method of fabricating polyvinyl alcohol (PVA) shells overcoated with a polystyrene (PS) layer. The method utilizes the emulsion technique previously developed by us, and employs three different liquid phases. A 5 wt. % aqueous PVA solution is mixed with a 7 wt. % PS solution in dichloromethane while stirring. The mixture is then poured into a 1 wt. % PS solution in cidhloromethane while stirring. The mixture is then poured into a 1 wt. % aqueous gelatin solution. The resulting emulsion is heated to evaporate the dichloromethane, resulting in solid PS shells encapsulating the PVA solution. The PS shells are subsequently washed and dried in vacuum to drive off the remaining water. As a result, a PVA shell is formed inside an overcoating PS shell which exhibits a good surface quality in the outer diameter and wall thickness regime currently desired by inertial confinement fusion experimenters.

Kubo, U.; Tsubakihara, H.

1987-07-01

293

Outer Hair Cell Electromotility in vivo  

NASA Astrophysics Data System (ADS)

The effectiveness of outer hair cell (OHC) electro-motility in vivo has been challenged by the expected low-pass filtering of the transmembrane potential due to the cell's own capacitance. The OHC electromotility is characterized here by an electromechanical ratio defined as the ratio of the OHC contraction to the transmembrane potential. This ratio has been measured in isolated cells to be approximately 26 nm/mV. We estimate the OHC electromechanical ratio in vivo from the recently measured displacements of the reticular lamina and the basilar membrane near the 19 kHz characteristic frequency in the basal region of guinea pig cochlea. Our analysis strongly suggests OHC electromotility process is effective for cochlear amplification in vivo at least around the characteristic frequency of the basal location in spite of the low-pass filtering.

Ramamoorthy, Sripriya; Nuttall, Alfred L.

2011-11-01

294

In Outer Space without a Space Suit?  

E-print Network

The author proposes and investigates his old idea - a living human in space without the encumbrance of a complex space suit. Only in this condition can biological humanity seriously attempt to colonize space because all planets of Solar system (except the Earth) do not have suitable atmospheres. Aside from the issue of temperature, a suitable partial pressure of oxygen is lacking. In this case the main problem is how to satiate human blood with oxygen and delete carbonic acid gas (carbon dioxide). The proposed system would enable a person to function in outer space without a space suit and, for a long time, without food. That is useful also in the Earth for sustaining working men in an otherwise deadly atmosphere laden with lethal particulates (in case of nuclear, chemical or biological war), in underground confined spaces without fresh air, under water or a top high mountains above a height that can sustain respiration.

Alexander Bolonkin

2008-06-24

295

Microbial biosynthesis of designer outer membrane vesicles.  

PubMed

Outer membrane vesicles (OMVs) are nanoscale proteoliposomes that are ubiquitously secreted by Gram-negative bacteria. Interest in these bioparticles has escalated over the years, leading to discoveries regarding their composition, production, and vaccine potential. Given that many steps in vesicle biogenesis are 'engineerable,' it is now possible to tailor OMVs for specific applications. Such tailoring involves modifying the OMV-producing bacterium through protein, pathway, or genome engineering in a manner that specifically alters the final OMV product. For example, targeted deletion or upregulation of genes associated with the cell envelope can modulate vesicle production or remodel the composition of vesicle components such as lipopolysaccharide. Likewise, bacteria can be reprogrammed to incorporate heterologously expressed proteins into either the membrane or lumenal compartment of OMVs. We anticipate that further research in the field of OMV engineering will enable continued design and biosynthesis of specialized vesicles for numerous biotechnological purposes ranging from the delivery of vaccines to the deconstruction of cellulosic substrates. PMID:24667098

Baker, Jenny L; Chen, Linxiao; Rosenthal, Joseph A; Putnam, David; DeLisa, Matthew P

2014-10-01

296

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

PubMed

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

Magwene, Paul M; Socha, John J

2013-02-01

297

Lateral interactions in the outer retina  

PubMed Central

Lateral interactions in the outer retina, particularly negative feedback from horizontal cells to cones and direct feed-forward input from horizontal cells to bipolar cells, play a number of important roles in early visual processing, such as generating center-surround receptive fields that enhance spatial discrimination. These circuits may also contribute to post-receptoral light adaptation and the generation of color opponency. In this review, we examine the contributions of horizontal cell feedback and feed-forward pathways to early visual processing. We begin by reviewing the properties of bipolar cell receptive fields, especially with respect to modulation of the bipolar receptive field surround by the ambient light level and to the contribution of horizontal cells to the surround. We then review evidence for and against three proposed mechanisms for negative feedback from horizontal cells to cones: 1) GABA release by horizontal cells, 2) ephaptic modulation of the cone pedicle membrane potential generated by currents flowing through hemigap junctions in horizontal cell dendrites, and 3) modulation of cone calcium currents (ICa) by changes in synaptic cleft proton levels. We also consider evidence for the presence of direct horizontal cell feed-forward input to bipolar cells and discuss a possible role for GABA at this synapse. We summarize proposed functions of horizontal cell feedback and feed-forward pathways. Finally, we examine the mechanisms and functions of two other forms of lateral interaction in the outer retina: negative feedback from horizontal cells to rods and positive feedback from horizontal cells to cones. PMID:22580106

Thoreson, Wallace B.; Mangel, Stuart C.

2012-01-01

298

Nuclear Electric Propulsion for Outer Space Missions  

NASA Technical Reports Server (NTRS)

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.

Barret, Chris

2003-01-01

299

Outer Planet Mission Studies Neptune Aerocapture  

NASA Technical Reports Server (NTRS)

Current and previous studies of orbiter missions to the outer planets have clearly identified high-energy aerocapture as a critical and enabling technology. Aerocapture involves the use of aerodynamic lift to fly a trajectory through a planet's atmosphere to sufficiently decelerate an entry vehicle to capture into planetary orbit. In the past, numerous studies of different configurations of lifting entry vehicles were studied for various planetary orbiter missions which identified aerocapture as a feasible concept yet complex and technically challenging. In order to determine the feasibility of high-speed aerocapture at the outer planets, an accurate trajectory simulation of the flight vehicle is the critical first step in the proposed research. Vehicle response to aerodynamic loading must be predicted accurately in the trajectory simulations. For several Neptune orbiter missions currently under study at the Jet Propulsion Laboratory (JPL), entry velocities relative to the rotating atmosphere ranging from 25 to 30 km/sec, are to be expected. Preliminary trajectory analysis has identified the various flow regimes the entry vehicle is expected to fly in the 8 1% H2 and 19% He atmosphere of Neptune. The size and mass of the vehicle are also determined by the launch vehicle constraints and orbiter spacecraft requirements. For a given baseline arrival conditions of an inertial entry velocity of 28 km/sec and an entry mass of 400 kg, a medium lift (L/D = 1), axisymmetric biconic shaped vehicle was selected in order to satisfy entry corridor width requirements expected for Neptune aerocapture. The analysis summarized in this study indicates that a biconic entry vehicle is a feasible concept for a Neptune aerocapture orbiter mission. The preliminary entry trajectory simulations has demonstrated adequate entry corridor control authority. Furthermore, estimates of the stagnation point heating environment has enabled the preliminary selection of candidate lightweight ceramic TPS materials.

Wercinski, Paul F.; Langhoff, Steven R. (Technical Monitor)

1997-01-01

300

The Outer Planetary Mission Design Project  

NASA Astrophysics Data System (ADS)

With the recent focus from the planetary science community on the outer planets of the solar system, The University of Alabama in Huntsville Integrated Product Team program is embarking on a new challenge to develop an outer planetary mission for the academic year 2010-2011. Currently four bodies are of interest for this mission: Titan, Europa, Triton, and Enceledus, with one body being chosen by the instructors by the beginning of the fall semester. This project will use the 2010 Discovery Announcement of Opportunity as its Request for Proposal (RFP). All of the teams competing in this project will use the AO to respond with a proposal to the instructors for their proposed mission and spacecraft concept. The project employs the two-semester design sequence of the IPT program to provide a framework for the development of this mission. This sequence is divided into four phases. Phase 1 - Requirements Development - focuses on the development of both the scientific and engineering requirements of the mission. During this phase the teams work very closely with the PI organization, represented by the College of Charleston. Phase 2 - Team Formation and Architecture Development - concentrates on the assessment of the overall mission architecture from the launch vehicle to the ground operations of the proposed spacecraft. Phase 3 - System Definition - provides for spacecraft subsystem trade studies and further refinement of the specific spacecraft to meet the scientific requirements and objectives developed in Phase 1. Phase 4 - Design - is the phase where the engineers provide the spacecraft design that is required for the mission of interest. At the conclusion of Phases 2 and 4, an external review board evaluates the proposed designs and chooses one winner of the competition.

Benfield, Michael; Turner, M. W.

2010-10-01

301

Shell Observations of Classical Novae  

NASA Astrophysics Data System (ADS)

We present shell observations of some classical novae from the Turkish National Observatory. We reobserved them to image their faint shells a long time after their outbursts. We revise the old findings with the new data and we call attention to narrow band pass observations.

Esenoglu, H. H.; Saygac, A. T.

2014-12-01

302

Tuna Sea Shell Pasta Ingredients  

E-print Network

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

Liskiewicz, Maciej

303

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2011-01-01

304

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...NUTS), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2013-01-01

305

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...NUTS), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2014-01-01

306

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2012-01-01

307

7 CFR 983.29 - Shelled pistachios.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Shelled pistachios. 983.29 Section 983.29 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE PISTACHIOS GROWN IN CALIFORNIA, ARIZONA, AND... Definitions § 983.29 Shelled pistachios. Shelled pistachios means...

2010-01-01

308

21 CFR 886.3800 - Scleral shell.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 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...

2010-04-01

309

STP Hard Disks Metropolis Program  

NSDL National Science Digital Library

The STP Hard Disks Metropolis program is a Monte Carlo simulation of hard disks in two dimensions. The default initial condition is a rectangular configuration of N=64 particles in a box of length L = 40. You can slowly increase the density of the gas (by setting the minimum scale length between centers to a value slightly less than 1) to explore phase transitions. STP HardDisksMetropolis is part of a suite of Open Source Physics programs that model aspects of Statistical and Thermal Physics (STP). The program is distributed as a ready-to-run (compiled) Java archive. Double-clicking the stp_HardDisksMetropolis.jar file will run the program if Java is installed on your computer. Additional programs can be found by searching ComPADRE for Open Source Physics, STP, or Statistical and Thermal Physics.

Gould, Harvey; Tobochnik, Jan; Christian, Wolfgang; Cox, Anne

2009-03-06

310

Hard Spheres Monte Carlo Model  

NSDL National Science Digital Library

The Hard Sphere Monte Carlo Model performs canonical Monte Carlo simulations of 256 or 500 hard spheres covering the fluid and solid states. The results are analysed through the radial distributions functions from which the equation of state (EOS) is estimated. This is done by fitting a polynomial to the radial distribution functions in order to exrapolate them to the hard spheres distance of contact. The consistency of the simulations is assessed by the errors of the predicted compressibility factors relatively to the accurate EOS reported by Wu and Sadus. The Hard Sphere Monte Carlo Model was developed using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the jar file will run the program if Java is installed. You can modify this simulation if you have EJS installed by right-clicking within the map and selecting "Open Ejs Model" from the pop-up menu item.

Fernandes, Fernando S.; Freitas, Filomena

2013-02-20

311

Confined Hard Disk System Model  

NSDL National Science Digital Library

The Confined Hard Disk System is an idealized statistical mechanics model that simulates a two-dimensional system of hard disks confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the time evolution of the kinetic energy K per particle, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Hard Disk System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-12-27

312

Shell tile thermal protection system  

NASA Technical Reports Server (NTRS)

A reusable, externally applied thermal protection system for use on aerospace vehicles subject to high thermal and mechanical stresses utilizes a shell tile structure which effectively separates its primary functions as an insulator and load absorber. The tile consists of structurally strong upper and lower metallic shells manufactured from materials meeting the thermal and structural requirements incident to tile placement on the spacecraft. A lightweight, high temperature package of insulation is utilized in the upper shell while a lightweight, low temperature insulation is utilized in the lower shell. Assembly of the tile which is facilitated by a self-locking mechanism, may occur subsequent to installation of the lower shell on the spacecraft structural skin.

Macconochie, I. O.; Lawson, A. G.; Kelly, H. N. (inventors)

1984-01-01

313

Dynamic centering of liquid shells  

NASA Technical Reports Server (NTRS)

The moderate-amplitude axisymmetric oscillations of an inviscid liquid shell surrounding an incompressible gas bubble are calculated by a multiple-time-scale expansion for initial deformations composed of two-lobed perturbations of the shell and a displacement of the bubble from the center of mass of the liquid. Two types of small-amplitude motion are identified and lead to very different nonlinear dynamic interactions, as described by the results valid up to second order in the amplitude of the initial deformation. In the 'bubble mode', the oscillations of the captive bubble and the liquid shell are exactly in phase and the bubble vibrates about its initial eccentric location. The bubble moves toward the center of the drop when the shell is perturbed into a 'sloshing mode' of oscillation where both interfaces move out of phase. These results explain the centering of liquid shells observed in several experiments.

Tsamopoulos, John A.; Brown, Robert A.

1987-01-01

314

Composite shell spacecraft seat  

NASA Technical Reports Server (NTRS)

A two-part seat (10) providing full body support that is specific for each crew member (30) on an individual basis. The two-part construction for the seat (10) can accommodate many sizes and shapes for crewmembers (30) because it is reconfigurable and therefore reusable for subsequent flights. The first component of the two-part seat construction is a composite shell (12) that surrounds the crewmember's entire body and is generically fitted to their general size in height and weight. The second component of the two-part seat (10) is a cushion (20) that conforms exactly to the specific crewmember's entire body and gives total body support in more complex environment.

Barackman, Victor J. (Inventor); Pulley, John K. (Inventor); Simon, Xavier D. (Inventor); McKee, Sandra D. (Inventor)

2008-01-01

315

Recent progress in the ground calibration of the ASTRO-H Hard X-ray telescope (HXT-2)  

NASA Astrophysics Data System (ADS)

The 6th Japanese X-ray satellite, ASTRO-H, equips two Hard X-ray Telescopes (HXTs) to perform imaging spectroscopy up to 70 keV. The 2nd flight module (HXT-2) had been completed in July, 2013. After some environmental tests were passed, the X-ray performance of the HXT-2 was measured at the SPring-8 BL20B2, 3rd generation synchrotron facility. The angular resolution defined with a Half Power Diameter (HPD) was 1:'9 at 30 keV and 1:'8 at 50 keV. This small energy dependence is considered to be caused by the difference in image quality of each foil; the inner mirror shells have better quality than outer ones. The effective area was found to be 178 cm2 at 30 keV and 82 cm2 at 50 keV, both of which exceed the requirement. Furthermore, the detailed energy dependence of the effective area was examined for a limited aperture in the 30{70 keV band with a pitch of 1 keV. We also measured the off-axis dependence of the effective area at 50 keV, and then determined the optical axis. The field of view of the HXT-2 was found to be 5:'6 (FWHM of the vignetting function), consistent with the simulation. In this paper, we also report the detailed analysis of the ground calibration data, which will be used for image reconstruction by a ray-tracing simulator.

Mori, Hideyuki; Kuroda, Yuji; Miyazawa, Takuya; Awaki, Hisamitsu; Babazaki, Yasunori; Furuzawa, Akihiro; Hibino, Tatsuya; Iizuka, Ryo; Ishibashi, Kazunori; Iwase, Toshihiro; Kunieda, Hideyo; Kurihara, Daichi; Matsumoto, Hironori; Miyata, Yusuke; Saji, Shigetaka; Sugita, Satoshi; Suzuki, Yoshio; Tachibana, Sasagu; Tamura, Keisuke; Tawara, Yuzuru; Uesugi, Kentaro

2014-07-01

316

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

NASA Astrophysics Data System (ADS)

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%.

Moraes, M.; Diaz, M.

317

In situ lyophilisation of nifedipine directly in hard gelatine capsules.  

PubMed

Hydrophobic drugs present a challenge due to: (i) adhesion and agglomeration; hence the choice of the suitable processing technique to have the drugs into orally administered dosage forms is critical. (ii) Poor dissolution and poor aqueous solubility; hence poor bioavailability. A novel method which is in situ lyophilisation directly in hard gelatin capsule shells was used in this research to enhance the dissolution of nifedipine (a model hydrophobic drug) in the presence of co-povidone, Pluronic(®)F-127 and inulin as enhancement excipients (to the best of our knowledge those excipients have not been previously used with nifedipine in lyophilised forms). Solutions of nifedipine and excipients in a range of concentrations (0.5, 1, 5 and 10%w/v) were prepared using a co-solvent system of tert- butyl alcohol/water mixture. These solutions were filled directly into bodies of size 000 hard gelatin capsule shells and freeze dried. Pure drug and all formulations were characterised by solubility, wetting studies and in vitro dissolution. Also, conformational integrity and thermal characteristics of nifedipine formulations were investigated using FT-IR spectroscopy and differential scanning calorimetry (DSC), respectively. The in situ lyophilisation of nifedipine with excipients, looks a promising method not only to improve the hydrophobic drug dissolution but also to be cost effective. PMID:22992055

Crum, Matthew; Elkordy, Amal Ali; Zarara, Moataz; Elkordy, Eman Ali

2013-01-01

318

Some asymptotic results concerning the buckling of a spherical shell of arbitrary thickness  

Microsoft Academic Search

For a spherical shell of arbitrary thickness which is subjected to an external hydrostatic pressure, symmetrical buckling takes place at a value of ?1 which depends on A1A2 and the mode number, where A1 and A2 are the undeformed inner and outer radii, and ?1 is the ratio of the deformed inner radius to the undeformed inner radius. In the

Yibin Fu

1998-01-01

319

Oceans, Ice Shells, and Life on Europa  

NASA Technical Reports Server (NTRS)

The four large satellites of Jupiter are famous for their planet-like diversity and complexity, but none more so than ice-covered Europa. Since the provocative Voyager images of Europa in 1979, evidence has been mounting that a vast liquid water ocean may lurk beneath the moon's icy surface. Europa has since been the target of increasing and sometimes reckless speculation regarding the possibility that giant squid and other creatures may be swimming its purported cold, dark ocean. No wonder Europa tops everyone's list for future exploration in the outer solar system (after the very first reconnaissance of Pluto and the Kuiper belt, of course). Europa may be the smallest of the Galilean moons (so-called because they were discovered by Galileo Galilei in the early 17th century) but more than makes up for its diminutive size with a crazed, alien landscape. The surface is covered with ridges hundreds of meters high, domes tens of kilometers across, and large areas of broken and disrupted crust called chaos. Some of the geologic features seen on Europa resemble ice rafts floating in polar seas here on Earth-reinforcing the idea that an ice shell is floating over an ocean on this Moon-size satellite. However, such features do not prove that an ocean exists or ever did. Warm ice is unusually soft and will flow under its own weight. If the ice shell is thick enough, the warm bottom of the shell will flow, as do terrestrial glaciers. This could produce all the observed surface features on Europa through a variety of processes, the most important of which is convection. (Convection is the vertical overturn of a layer due to heating or density differences-think of porridge or sauce boiling on the stove.) Rising blobs from the base of the crust would then create the oval domes dotting Europa's surface. The strongest evidence for a hidden ocean beneath Europa's surface comes from the Galileo spacecraft's onboard magnetometer, which detected fluctuations in Jupiter's magnetic field consistent with a conductor inside Europa. The most likely conductor: a somewhat salty ocean.

Schenk, Paul

2002-01-01

320

Core-shell-shell and hollow double-shell microgels with advanced temperature responsiveness.  

PubMed

Unique doubly temperature-responsive hollow microgels are presented. These consist of two concentric thermoresponsive polymer shells made of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-isopropylmethacrylamide) (PNIPMAM), respectively. The hollow particles are derived from silica-PNIPAM-PNIPMAM core-shell-shell (CSS) particles by dissolution of the silica core. Light scattering measurements reveal the twofold volume phase transition behavior that occur in the PNIPAM and PNIPMAM regions of the CSS and the respective hollow particles. In the presence of the silica core, i.e., in case of the CSS particles, the swelling of the inner shell is tremendously restricted by the core. However, after the core is dissolved, the transition of the inner shell from the swollen to the collapsed state is highly pronounced. This versatile approach allows preparing hollow particles with individually tunable properties on the particle inside and outside for various applications as multifunctional smart materials. PMID:25354836

Dubbert, Janine; Nothdurft, Katja; Karg, Matthias; Richtering, Walter

2015-01-01

321

Hard-phase engineering in hard/soft nanocomposite magnets  

NASA Astrophysics Data System (ADS)

Bulk SmCo/Fe(Co) based hard/soft nanocomposite magnets with different hard phases (1:5, 2:17, 2:7 and 1:3 types) were fabricated by high-energy ball-milling followed by a warm compaction process. Microstructural studies revealed a homogeneous distribution of bcc-Fe(Co) phase in the matrix of hard magnetic Sm-Co phase with grain size ?20 nm after severe plastic deformation and compaction. The small grain size leads to effective inter-phase exchange coupling as shown by the single-phase-like demagnetization behavior with enhanced remanence and energy product. Among the different hard phases investigated, it was found that the Sm2Co7-based nanocomposites can incorporate a higher soft phase content, and thus a larger reduction in rare-earth content compared with the 2:17, 1:5 and 1:3 phase-based nanocomposite with similar properties. (BH)max up to 17.6 MGOe was obtained for isotropic Sm2Co7/FeCo nanocomposite magnets with 40 wt% of the soft phase which is about 300% higher than the single-phase counterpart prepared under the same conditions. The results show that hard-phase engineering in nanocomposite magnets is an alternative approach to fabrication of high-strength nanocomposite magnets with reduced rare-earth content.

Poudyal, Narayan; Rong, Chuanbing; Vuong Nguyen, Van; Liu, J. Ping

2014-03-01

322

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

PubMed

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

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

2012-08-01

323

Glass shell manufacturing in space  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

324

Stochastic Electron Acceleration in Shell-Type Supernova Remnants  

E-print Network

We study the stochastic electron acceleration by fast mode waves in the turbulent downstream of weakly magnetized collisionless astrophysical shocks. The acceleration is most efficient in a dissipative layer, and the model characteristics are determined by the shock speed, density, magnetic field, and turbulence decay length. The model explains observations of shell-type supernova remnants RX J1713.7-3946 and J0852.0-4622 and can be tested by observations in hard X-rays with the HXMT and NuSTAR or gamma-rays with the GLAST.

Siming Liu; Zhong-Hui Fan; Christopher L. Fryer; Jian-Min Wang; Hui Li

2008-07-14

325

Isotopic and chemical intra-shell variations in low-Mg calcite of rudist bivalves (Mollusca-Hippuritacea): disequilibrium fractionations and late Cretaceous seasonality  

Microsoft Academic Search

Isotopic (?13C, ?18O) and elemental (Mg, Sr, Mn, Fe) compositions were analysed in sclerochronological profiles of several shells of late Cretaceous\\u000a rudist bivalves from Greece, Turkey, Somalia and the Arabian Peninsula. The preservation of original compositions of low-Mg\\u000a calcite of outer shell layers is indicated by constant and high Sr, generally low Fe and Mn, and the preservation of fibrous-prismatic

T. Steuber

1999-01-01

326

Subsurface oceans and deep interiors of medium-sized outer planet satellites and large trans-neptunian objects  

NASA Astrophysics Data System (ADS)

The detection of induced magnetic fields in the vicinity of the jovian satellites Europa, Ganymede, and Callisto is one of the most surprising findings of the Galileo mission to Jupiter. The observed magnetic signature cannot be generated in solid ice or in silicate rock. It rather suggests the existence of electrically conducting reservoirs of liquid water beneath the satellites' outermost icy shells that may contain even more water than all terrestrial oceans combined. The maintenance of liquid water layers is closely related to the internal structure, composition, and thermal state of the corresponding satellite interior. In this study we investigate the possibility of subsurface oceans in the medium-sized icy satellites and the largest trans-neptunian objects (TNO's). Controlling parameters for subsurface ocean formation are the radiogenic heating rate of the silicate component and the effectiveness of the heat transfer to the surface. Furthermore, the melting temperature of ice will be significantly reduced by small amounts of salts and/or incorporated volatiles such as methane and ammonia that are highly abundant in the outer Solar System. Based on the assumption that the satellites are differentiated and using an equilibrium condition between the heat production rate in the rocky cores and the heat loss through the ice shell, we find that subsurface oceans are possible on Rhea, Titania, Oberon, Triton, and Pluto and on the largest TNO's 2003 UB 313, Sedna, and 2004 DW. Subsurface oceans can even exist if only small amounts of ammonia are available. The liquid subsurface reservoirs are located deeply underneath an ice-I shell of more than 100 km thickness. However, they may be indirectly detectable by their interaction with the surrounding magnetic fields and charged particles and by the magnitude of a satellite's response to tides exerted by the primary. The latter is strongly dependent on the occurrence of a subsurface ocean which provides greater flexibility to a satellite's rigid outer ice shell.

Hussmann, Hauke; Sohl, Frank; Spohn, Tilman

2006-11-01

327

Oxygen and carbon isotope records of cultured freshwater pearl mussel Hyriopsis sp. shell from Lake Kasumigaura, Japan  

NASA Astrophysics Data System (ADS)

We analyzed the relationship between oxygen and carbon isotope ratios and morphological structure to understand the biomineralization of cultured freshwater pearl mussel (Hyriopsis sp.: Unionidae) shells and pearls. The ?18O of the outer shell layer was mainly controlled by water temperature with minor contribution from a variation in ?18O of ambient water especially in rainy season. The constant values of ?13C values with ontogeny suggesting that both temperature and body size had no significant effect on ?13C of shell. We observed nine distinct disturbance rings on the outer surface of the shell. Five distinct disturbance rings coincided with every winter peaks of the ?18O profile. On the other hand, summer disturbance rings were not observed every year. Moreover, some summer rings had strong and multiple discontinuity in inner structure. The relationship between growth rings and ?18O profile suggest that winter growth cessation probably due to inactive growth at low water temperatures (below approximately 10°C) or reproduction, and summer growth cessation was not caused by cyclic event but occasional events, e.g. heavy rain. The ?18O profile and shell structures indicated shell aragonite was precipitated close to an equilibrium condition with respect to oxygen isotope composition of ambient water. The ?18O of a pearl indicated calcification occurred at temperature range of at least 13-23°C.

Yoshimura, T.; Nakashima, R.; Suzuki, A.; Kawahata, H.

2008-12-01

328

The Outer Heliosphere: The Next Frontier  

NASA Astrophysics Data System (ADS)

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.

Heber, B.; Zank, G. P.

329

The Outer Heliosphere: The Next Frontiers  

NASA Astrophysics Data System (ADS)

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.

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

330

Metric theory of nematoelastic shells  

NASA Astrophysics Data System (ADS)

We consider three-dimensional reshaping of a thin nematoelastic film upon nematic-isotropic transition in the field of a charge one topological defect, leading to either cone or anticone (d -cone) shells. The analysis is based on the relation between the shell metric and the tensor order parameter under the assumption of no elastic deformation and volume change. The shape of the shell can be modified by doping, creating cones with curved generatrices. Anticones necessarily have an even number of radial creases. The curvature singularity at the apex is resolved due to decay of the nematic order parameter at the defect core.

Pismen, L. M.

2014-12-01

331

MicroShell Minimalist Shell for Xilinx Microprocessors  

NASA Technical Reports Server (NTRS)

MicroShell is a lightweight shell environment for engineers and software developers working with embedded microprocessors in Xilinx FPGAs. (MicroShell has also been successfully ported to run on ARM Cortex-M1 microprocessors in Actel ProASIC3 FPGAs, but without project-integration support.) Micro Shell decreases the time spent performing initial tests of field-programmable gate array (FPGA) designs, simplifies running customizable one-time-only experiments, and provides a familiar-feeling command-line interface. The program comes with a collection of useful functions and enables the designer to add an unlimited number of custom commands, which are callable from the command-line. The commands are parameterizable (using the C-based command-line parameter idiom), so the designer can use one function to exercise hardware with different values. Also, since many hardware peripherals instantiated in FPGAs have reasonably simple register-mapped I/O interfaces, the engineer can edit and view hardware parameter settings at any time without stopping the processor. MicroShell comes with a set of support scripts that interface seamlessly with Xilinx's EDK tool. Adding an instance of MicroShell to a project is as simple as marking a check box in a library configuration dialog box and specifying a software project directory. The support scripts then examine the hardware design, build design-specific functions, conditionally include processor-specific functions, and complete the compilation process. For code-size constrained designs, most of the stock functionality can be excluded from the compiled library. When all of the configurable options are removed from the binary, MicroShell has an unoptimized memory footprint of about 4.8 kB and a size-optimized footprint of about 2.3 kB. Since MicroShell allows unfettered access to all processor-accessible memory locations, it is possible to perform live patching on a running system. This can be useful, for instance, if a bug is discovered in a routine but the system cannot be rebooted: Shell allows a skilled operator to directly edit the binary executable in memory. With some forethought, MicroShell code can be located in a different memory location from custom code, permitting the custom functionality to be overwritten at any time without stopping the controlling shell.

Werne, Thomas A.

2011-01-01

332

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

PubMed

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 (785nm, 50mWcm(-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 92nm 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?gml(-1), a killing rate of 100% is reached for the E. coli O157:H7 cells under 20min 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

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

2015-01-01

333

Electronic shells and shells of atoms in metallic clusters  

Microsoft Academic Search

Intensity anomalies (magic numbers) have been observed in the mass spectra of sodium clusters containing up to 22 000 atoms. For small clusters (Nan,n=1500) the anomalies appear to be due to the filling of electronic shells (groups of subshells having the same energy). The shells can be characterized rather well by a pseudoquantum-number, indicating the possible existence of a symmetry

T. P. Martin; T. Bergmann; H. Göhlich; T. Lange

1991-01-01

334

Cationic core-shell liponanoparticles for ocular gene delivery.  

PubMed

To achieve enhanced gene transfection efficiency with ocular eye-drop therapy, a cationic core-shell liponanoparticle (DLCS-NP) was designed by enveloping the plasmid-laden chitosan nanoparticle (CS-NP) into a cationic lipid shell. The cellular uptake of DLCS-NP was up to 1.25-fold and 5-fold higher than that of CS-NP and lipid-coated chitosan nanoparticles (LCS-NP), respectively. Further endocytosis inhibition investigation discovered that facilitated by the cationic outer lipid layer, several other distinct pathways (besides clathrin-mediated endocytosis) were involved in the endocytosis of DLCS-NP. Endolysosome trafficking experiment verified that cationic lipid coating could facilitate the endolysosome escape of DLCS-NP. Consequently, using enhanced green fluorescence protein (EGFP) as a reporter gene, DLCS-NP-treated human conjunctival epithelial cells exhibited 3.1- and 3.5-fold more intense EGFP expression than that of LCS-NP and CS-NP, respectively. Finally, in vivo transfection experiments on rabbits revealed that EGFP expression exhibited 2.52-fold increase in DLCS-NP group than that of CS-NP group. In summary, this type of cationic core-shell liponanoparticle, possessing multiple functions including better DNA protecting effect, superior cellular uptake efficiency, utilization of multiple endocytic pathways, and endolysosome escaping ability, may represent a promising strategy for ocular gene delivery. PMID:22789720

Jiang, Min; Gan, Li; Zhu, Chunliu; Dong, Yang; Liu, Jianping; Gan, Yong

2012-10-01

335

Prevelance and Distribution of QPX, Quahog Parasite Unknown, in Hard Clams Mercenaria Mercenaria in Virginia, USA  

NSDL National Science Digital Library

This Diseases of Aquatic Organisms abstract serves as the first documentation of QPX (Quahog Parasite Unknown, a parasite affecting hard shell clams) in the state of Virginia. It reports findings from a sampling program performed in 1996 and 1997 that showed light to moderate parasite intensity ranging from 4% to 48% of each sampling period. At the time this article was published, QPX had not had a significant impact on Virginia's hard clam fishery and aquaculture industry, but the authors recommend continued monitoring and research.

Burreson, Eugene M.; Ragone Calvo, Lisa M.; Walker, Juanita G.

2009-07-14

336

Radioisotope Reduction Using Solar Power for Outer Planetary Missions  

Microsoft Academic Search

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

James Fincannon

2008-01-01

337

Modeling of the outer electron belt during magnetic storms  

Microsoft Academic Search

The flux dropout of relativistic electrons in the earth’s outer radiation belt, during the main phase of the 26 March 1995 magnetic storm is examined. Outer belt measurements by the Radiation Environment Monitor, REM aboard the STRV-1b satellite are presented to characterize this dropout. In order to simulate the dynamics of the electron belt during the storm main phase a

L. Desorgher; P. Bühler; A. Zehnder; E. Daly; L. Adams

1999-01-01

338

Tectonics of the outer planet satellites Geoffrey C. Collins  

E-print Network

7 Tectonics of the outer planet satellites Geoffrey C. Collins Wheaton College, Norton William B. Schenk Lunar and Planetary Institute, Houston Summary Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre

Nimmo, Francis

339

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

ERIC Educational Resources Information Center

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…

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

2006-01-01

340

Outer hair cell active force generation in the cochlear environment  

E-print Network

Outer hair cell active force generation in the cochlear environment Zhijie Liao, Shengran Feng Outer hair cells are critical to the amplification and frequency selectivity of the mammalian ear acting hair cells are electromotile, and they are strategically located in the cochlea to generate an active

Popel, Aleksander S.

341

Research paper Fast cochlear amplification with slow outer hair cells  

E-print Network

Research paper Fast cochlear amplification with slow outer hair cells Timothy K. Lu a,b , Serhii hair cells (OHCs) produce mechanical amplification over the entire audio-frequency range (up to 100 k reserved. Keywords: Cochlear amplifier; Outer hair cell; Receptor potential; Membrane time constant low

Sarpeshkar, Rahul

342

Spam Zombies from Outer Space John Aycock & Nathan Friess  

E-print Network

Spam Zombies from Outer Space John Aycock & Nathan Friess Department of Computer Science University-mail: {aycock,friessn}@cpsc.ucalgary.ca. Keywords Zombies, botnets, spam, spyware, email worms 15th Annual EICAR Conference "Security in the Mobile and Networked World" - 164 - #12;Spam Zombies from Outer Space Abstract

Aycock, John

343

Is the outer Solar System chaotic? WAYNE B. HAYES  

E-print Network

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

Loss, Daniel

344

Influence of algal and suspended sediment concentrations on the feeding physiology of the hard clam Mercenaria mercenaria  

Microsoft Academic Search

Short-term laboratory feeding experiments were conducted to determine the response of the hard clam Mercenaria mercenaria (L.) (32 mm in mean shell length) to increasing sediment concentrations. Clams were fed mixed suspensions of Pseudoisochrysis paradoxa (50 and 150 cells µl-1) and bottom sediments (0 to 44 mg l-1). Algal ingestion rate deelined with increasing sediment loads. This resulted primarily from

V. M. Bricelj; R. E. Malouf

1984-01-01

345

Electrospinning of artemisinin-loaded core-shell fibers for inhibiting drug re-crystallization.  

PubMed

The main aim of this study was to inhibit the re-crystallization of a potent antimalarial drug, artemisinin (ART), by encapsulating it in core-shell fibers via a coaxially electrospun method. The ART-infiltrated cellulose acetate (CA) solution as the core material and poly(vinyl pyrrolidone) (PVP) solution as the shell material were used to prepared ART-loaded core-shell fibers ([ART/CA]/PVP). Transmission electron microscopy images confirmed the core-shell structures of the coaxially electrospun fibers. The scanning electron microscope (SEM), X-ray diffraction, and differential scanning calorimetry were performed to characterize the physical states of ART in the fibers. It was observed that ART crystals were formed in the ART-loaded CA/PVP composite fibers (ART/CA/PVP) during the electrospinning process and increased during storage duration. While ART crystals hardly were observed in the fresh core-shell [ART/CA]/PVP fibers with high ART entrapped amount (20 wt.%) and a little was detected after 6-month storage. Fourier transform infrared spectroscopy (FTIR) results illustrated the hydrogen bonding interaction between ART and CA in the core-shell [ART/CA]/PVP fibers mainly contributed to the amorphous state of ART. Importantly, combination of the hydrophilic PVP shell and the amorphous ART in CA core, the core-shell [ART/CA]/PVP fibers provided a continued and stable ART release manner. Ex vivo permeation studies suggested the amorphous ART in the medicated core-shell fibers could permeate through the stratum corneum smoothly. Hence, the core-shell [ART/CA]/PVP fiber matrix could provide a potential application in transdermal patches. PMID:23565867

Shi, Yongli; Zhang, Jianhua; Xu, Shuxin; Dong, Anjie

2013-01-01

346

Advanced Metal Foam Structures for Outer Space  

NASA Technical Reports Server (NTRS)

A document discusses a proposal to use advanced materials especially bulk metallic glass (BMG) foams in structural components of spacecraft, lunar habitats, and the like. BMG foams, which are already used on Earth in some consumer products, are superior to conventional metal foams: BMG foams have exceptionally low mass densities and high strength-to-weight ratios and are more readily processable into strong, lightweight objects of various sizes and shapes. These and other attractive properties of BMG foams would be exploited, according to the proposal, to enable in situ processing of BMG foams for erecting and repairing panels, shells, containers, and other objects. The in situ processing could include (1) generation of BMG foams inside prefabricated deployable skins that would define the sizes and shapes of the objects thus formed and (2) thermoplastic deformation of BMG foams. Typically, the generation of BMG foams would involve mixtures of precursor chemicals that would be subjected to suitable pressure and temperature schedules. In addition to serving as structural components, objects containing or consisting of BMG foams could perform such functions as thermal management, shielding against radiation, and shielding against hypervelocity impacts of micrometeors and small debris particles.

Hanan, Jay; Johnson, William; Peker, Atakan

2005-01-01

347

Insulative laser shell coupler  

DOEpatents

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.

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

1994-01-01

348

Stability of elastic grid shells  

E-print Network

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 ...

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

2013-01-01

349

Intergalactic shells at large redshift  

NASA Technical Reports Server (NTRS)

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.

Shull, J. M.; Silk, J.

1981-01-01

350

Elastic stability of cylindrical shells with soft elastic cores: Biomimicking natural tubular structures  

NASA Astrophysics Data System (ADS)

Thin walled cylindrical shell structures are widespread in nature: examples include plant stems, porcupine quills, and hedgehog spines. All have an outer shell of almost fully dense material supported by a low density, cellular core. In nature, all are loaded in combination of axial compression and bending: failure is typically by buckling. Natural structures are often optimized. Here we have analyzed the elastic buckling of a thin cylindrical shell supported by an elastic core to show that this structural configuration achieves significant weight saving over a hollow cylinder. The results of the analysis are compared with data from an extensive experimental program on uniaxial compression and four point bending tests on silicone rubber shells with and without compliant foam cores. The analysis describes the results of the mechanical tests well. Characterization of the microstructures of several natural tubular structures with foamlike cores (plant stems, quills, and spines) revealed them to be close to the optimal configurations predicted by the analytical model. Biomimicking of natural cylindrical shell structures and evolutionary design processes may offer the potential to increase the mechanical efficiency of engineering cylindrical shells.

Karam, Gebran Nizar

1994-01-01

351

An Outer Galaxy Molecular Cloud Catalog  

NASA Astrophysics Data System (ADS)

We have generated a molecular cloud catalog from the Five College Radio Astronomy Observatory Outer Galaxy Survey of 12CO (J=1-0) emission using a two-phase object identification procedure. The first phase consists of grouping pixels into contiguous structures above a radiation temperature threshold of 0.8 K. The second phase decomposes the first-phase objects by an enhanced version of the CLUMPFIND algorithm, using dynamic thresholding, and again with a threshold of 0.8 K used for discrimination. A detailed comparison of our method with the CLUMPFIND algorithm is given, highlighting the advantages of the use of dynamic (rather than quantized) thresholding. Basic attributes of the clouds-coordinates, bounding boxes, integrated intensities, peak observed temperatures-are tabulated in the catalog. A two-dimensional elliptical Gaussian is fitted to the velocity-integrated map of each cloud; the major and minor axis sizes and major axis position angles thus derived are included in the catalog. To the spatially integrated emission line of each cloud, a Gaussian profile is fitted to measure the global linewidth. Model Gaussian clouds, truncated at 0.8 K, are examined to determine the effects of biases on measured quantities, induced by truncation. Coupled with detailed analysis of the cataloged clouds, statistical corrections for the effects of truncation on measured sizes, linewidths, and integrated intensities are derived and applied, along with corrections for the effects of finite resolution on the measured attributes. The cataloged emission accounts for 76.4% of the total emission in the Outer Galaxy Survey. The deficit is shown to arise mainly from low-intensity emission on the periphery of larger objects, rather than from a large number of small and/or low-intensity features. From the measured parameters, Gaussian reconstructions of the emission are carried out, and these compare favorably to the raw data. A detailed analysis of the decomposition in complex regions is performed, showing that severe truncation at levels much in excess of 0.8 K is countered by the operation of a ``thermostat,'' resulting in concatenation of emission into a larger object if severe blending is present, rather than the identification of a number of smaller, more heavily truncated objects. Two other tests are carried out: (1) an association test that examines the utility of using the decomposed 12CO (J=1-0) emission, in comparison to CS emission, to identify possible sites of star formation as traced by IRAS point sources; (2) a test comparison of 12CO and 13CO decompositions to gauge the effects of emission saturation and blending. Overall, the results of these two tests show that emission enhancements in 12CO (J=1-0) emission, induced by internal heating by embedded star formation, are in general usefully recorded in the decomposition, but that emission blending and saturation on scales of ~few arcminutes in complex regions can limit the precision to which associations with other tracers can be made. A statistical approach to source association that makes good use of the information contained in the catalog is developed and described. The new 12CO cloud catalog, as a concise description of the OGS data, will facilitate intercomparisons of molecular clouds with other ISM components, available at comparable resolution within the Canadian Galactic Plane Survey. The catalog covers the Galactic longitude range 102.5d to 141.5d, Galactic latitude range -3° to +5.4d, and lsr velocity range +20.8 to -120.2 km s-1 and contains 14,592 objects. Due to its size, and for ease of access, the catalog is made available in electronic form.

Brunt, Christopher M.; Kerton, C. R.; Pomerleau, Caroline

2003-01-01

352

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

NASA Astrophysics Data System (ADS)

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.

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

2000-06-01

353

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

PubMed

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

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

2000-06-29

354

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-shell clams, (MYA ARENARIA) The fact that small soft -shell clams can come up out of the soil, can move

355

How Many Under the Shell?  

NSDL National Science Digital Library

This interactive Flash applet helps students develop number sense and fluency with addition and subtraction facts within 10. Okta hides some bubbles under a shell, and then either adds more bubbles or takes some away. Students determine how many bubbles are left under the shell. Users can choose a specific one-digit starting number or let the applet choose randomly. Users can select addition, subtraction or both.

2000-01-01

356

Gravitational Tunnelling of Relativistic Shells  

E-print Network

Thin shells in general relativity have been used in the past as keystones to obtain realistic models of cosmological and astrophysical situations. A crucial role for these developments was played by the compact description of their dynamics in terms of Israel's junction conditions. Starting from this geometrical formulation we present a problem related to the WKB regime of shell dynamics and suggest a possible solution.

Stefano Ansoldi; Lorenzo Sindoni

2004-11-09

357

Sea Scallop Shell Lab Handout  

NSDL National Science Digital Library

Used in combination with the Sea Scallop Shell Lab teacher's guide, students will examine sea scallop shells to figure out as much as possible about the scallops living on the sea floor in one three important fishery grounds, Hudson Canyon, off New Bedford, MA, and George's Bank. The activity emphasizes observation, measurements, and basic calculations. The teacher's guide is available from the COSEE-NE OSEI resource site.

358

Nematic textures in spherical shells  

NASA Astrophysics Data System (ADS)

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.

Vitelli, V.; Nelson, D. R.

2006-08-01

359

Outer Retinal Structure in Patients with Acute Zonal Occult Outer Retinopathy  

PubMed Central

Purpose To correlate visual function with high-resolution images of retinal structure using adaptive optics scanning laser ophthalmoscopy (AOSLO) in 4 patients with acute zonal occult outer retinopathy (AZOOR). Design Observational case series. Methods Four women, aged 18–51, with acute focal loss of visual field or visual acuity, photopsia, and minimal funduscopic changes were studied with best-corrected visual acuity (BCVA), Goldmann kinetic and automated perimetry and fundus-guided microperimetry, full-field and multifocal electroretinography (ffERG and mfERG), spectral domain optical coherence tomography (SDOCT) and AOSLO imaging. Cone spacing was measured in four eyes and compared with 27 age-similar normal eyes. Additional functional testing in one patient suggested that cones were absent but rods remained. Serum from all patients was analyzed for anti-retinal antibody activity. Results In all patients vision loss was initially progressive, then stable. Symptoms were unilateral in 2 and bilateral but asymmetric in 2 patients. In each patient, loss of retinal function correlated with structural changes in the outer retina. AOSLO showed focal cone loss in most patients, although in one patient with central vision loss such change was absent. In another patient, structural and functional analyses suggested that cones had degenerated but rods remained. Anti-retinal antibody activity against a ~45kd antigen was detected in 1 of the patients; the other 3 patients showed no evidence of abnormal anti-retinal antibodies. Conclusions Focal abnormalities of retinal structure correlated with vision loss in patients with AZOOR. High-resolution imaging can localize and demonstrate the extent of outer retinal abnormality in AZOOR patients. PMID:22105799

Mkrtchyan, Marianna; Lujan, Brandon J.; Merino, David; Thirkill, Charles E.; Roorda, Austin; Duncan, Jacque L.

2011-01-01

360

Hard Work and Hard Data: Getting Our Message Out.  

ERIC Educational Resources Information Center

Unless questions about student performance and student retention can be answered and unless educators are proactive in finding and publicizing such information, basic writing programs cannot determine if what they are doing is working. Hard data, especially from underrepresented groups, is needed to support these programs. At Arizona State…

Glau, Gregory R.

361

Does rice ragged stunt virus lack the typical double shell of the Reoviridae?  

PubMed

In rice ragged stunt virus preparations negatively stained with uranyl acetate, particles corresponding to the B-spiked subviral particles (SPVs) but not the double-shelled virions of fijiviruses were seen. The B spikes were broader at the base than those of fijiviruses, but otherwise the particles were similar in size and shape to fijivirus SVPs. In thin sections of infected plants, large numbers of virus-like particles were seen; most resembled the SVPs of fijiviruses but some appeared intermediate between these and complete fijivirus particles. It seems likely that rice ragged stunt virus does not produce a regular outer shell as do the fijiviruses, although the broad-based B spikes may in some profiles have given the appearance of a continuous shell. PMID:7251337

Milne, R G

1980-01-01

362

The Electron Shell and Alpha Decay in Super-Heavy Nuclei  

NASA Astrophysics Data System (ADS)

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.

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

2015-11-01

363

Synthesis and magnetic characterization of Co-NiO-Ni core-shell nanotube arrays  

NASA Astrophysics Data System (ADS)

Well-aligned Ni and Co-NiO-Ni core-shell nanotube arrays with an average outer diameter of about 200 nm have been synthesized in a porous anodic aluminum oxide (AAO) template by the direct electro-deposition method. The result shows that the nanotubes were polycrystalline phase. Angular dependent coercivity Hc(?) indicates that the magnetization reversal mechanisms are mainly dominated by the "curling mode" for Ni nanotubes, while a transition from curling to transverse is observed in Co-NiO-Ni core-shell nanotubes at a large angle. A sharp increase in saturated magnetization (Ms) of Ni and Co-NiO-Ni core-shell nanotubes at 5 K was observed, due to dominance of the surface effect. Besides, the existed superparamagnetic nanoparticles also resulted in the increase of Ms for both cases. These structures have potential applications in the novel spintronics device, ultrasmall magnetic media, and other nanodevices.

Chen, J. Y.; Ahmad, N.; Shi, D. W.; Zhou, W. P.; Han, X. F.

2011-10-01

364

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

NASA Astrophysics Data System (ADS)

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.

Balazy, Piotr; Kuklinski, Piotr

2013-03-01

365

Characterization of core-shell calcium-alginate macrocapsules fabricated by electro-coextrusion.  

PubMed

Spherical macrocapsules, where calcium-alginate shell enclosed olive oil as a model core medium, were fabricated by electro-coextrusion. The effects of three key process factors, including alginate concentration in shell fluid (0.5-4.0%), shell-to-core flow rate ratio (4-12 at a fixed core flow rate of 0.05 mL/min), and applied voltage (0-10 kV), on the morphological and textural characteristics of the macrocapsules were analyzed using response surface methodology. The analysis showed that the diameter, shell thickness, hardness, and breaking energy of the macrocapsules were in the ranges of 0.89-1.61 mm, 17.4-66.4 ?m, 1.37-11.01 N, and 0.34-6.90 mJ, respectively, and strongly influenced by all the three factors, except that the surface appearance was only significantly affected by the shell-to-core flow rate ratio. The process factors were also optimized for the practically useful macrocapsules, having non-oily surface and hardness larger than 3 N, using a graphical optimization technique. PMID:24463268

Phawaphuthanon, Natthiya; Behnam, Shabnam; Koo, Song Yi; Pan, Cheol-Ho; Chung, Donghwa

2014-04-01

366

Comparison of aragonitic molluscan shell proteins.  

PubMed

Acidic macromolecules, as a nucleation factor for mollusc shell formation, are a major focus of research. It remains unclear, however, whether acidic macromolecules are present only in calcified shell organic matrices, and which acidic macromolecules are crucial for the nucleation process by binding to chitin as structural components. To clarify these questions, we applied 2D gel electrophoresis and amino acid analysis to soluble shell organic matrices from nacre shell, non-nacre aragonitic shell and non-calcified squid shells. The 2D gel electrophoresis results showed that the acidity of soluble proteins differs even between nacre shells, and some nacre (Haliotis gigantea) showed a basic protein migration pattern. Non-calcified shells also contained some moderately acidic proteins. The results did not support the correlation between the acidity of soluble shell proteins and shell structure. PMID:19932190

Furuhashi, Takeshi; Miksik, Ivan; Smrz, Miloslav; Germann, Bettina; Nebija, Dashnor; Lachmann, Bodo; Noe, Christian

2010-02-01

367

Biology of the hard clam Hard clams of the genus Mercenaria  

E-print Network

Biology of the hard clam Hard clams of the genus Mercenaria are found from the Gulf of St. Lawrence of the general- izations may apply to all hard clams. The hard clam is rarely found where salinities average less than 20 parts per thousand (ppt). Hard clams occu- py intertidal and subtidal habitats, where

Florida, University of

368

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

USGS Publications Warehouse

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.

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

2012-01-01

369

Hard X-ray latitude effect measured during a transatlantic balloon flight  

SciTech Connect

The hard X-ray latitude effect is reported in the range of McIlwain shell parameter L from 1.4 to 2.6 (earth radius units). The data were obtained with two X-ray scintillator detectors flown on board a transatlantic balloon launched from Trapani, Sicily. The data analysis method for measuring the flux from weak X-ray sources is also described.

Frontera, F. (CNR, Istituto Plasma Spazio, Frascati, Italy); Fuligni, F. (CNR, Istituto di Tecnologie e Studio delle Radiazioni Extraterrestri, Bologna, Italy)

1981-01-01

370

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

371

Hard scattering in ?p interactions  

NASA Astrophysics Data System (ADS)

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.

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

1992-12-01

372

Is Carbon Hard or Soft?  

NSDL National Science Digital Library

The representation shows differences in the arrangement of carbon atoms that make up diamonds and graphite. Through text and pictures, the resource describes the difference in arrangement of two different carbon allotropes. The text relates the differences in arrangements to differences in the hardness (properties) of the materials.

373

Hard and soft multifractal processes  

Microsoft Academic Search

We show that multifractal notions encompass a wider variety of phenomena than often believed. Ranked by increasing highest order of singularities we have geometric, then microcanonical and finally canonical multifractals. They are respectively localized and ``calm'', delocalized and ``calm'', and delocalized and ``wild''. Canonical multifractals may also involve rare violent (``hard'') singularities which cause high order statistical moments to diverge.

D. Schertzer; S. Lovejoy

1992-01-01

374

FATIGUE OF BIOMATERIALS: HARD TISSUES  

PubMed Central

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

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

2009-01-01

375

SN 1994W: an interacting supernova or two interacting shells?  

NASA Astrophysics Data System (ADS)

We present a multi-epoch quantitative spectroscopic analysis of the Type IIn supernova (Type IIn SN) 1994W, an event interpreted by Chugai et al. as stemming from the interaction between the ejecta of a SN and a 0.4Msolar circumstellar shell ejected 1.5yr before core collapse. During the brightening phase, our models suggest that the source of optical radiation is not unique, perhaps associated with an inner optically thick cold dense shell and outer optically thin shocked material. During the fading phase, our models support a single source of radiation, an hydrogen-rich optically thick layer with a near-constant temperature of ~7000K that recedes from a radius of 4.3 × 1015 at a peak to 2.3 × 1015cm 40 d later. We reproduce the hybrid narrow-core broad-wing line profile shapes of SN 1994W at all times, invoking an optically thick photosphere exclusively (i.e. without any external optically thick shell). In SN 1994W, slow expansion makes scattering with thermal electrons a key escape mechanism for photons trapped in optically thick line cores, and allows the resulting broad incoherent electron-scattering wings to be seen around narrow-line cores. In SNe with larger expansion velocities, the thermal broadening due to incoherent scattering is masked by the broad profile and the dominant frequency redshift occasioned by bulk motions. Given the absence of broad lines at all times and the very low 56Ni yields, we speculate whether SN 1994W could have resulted from an interaction between two ejected shells without core collapse. The high conversion efficiency of kinetic to thermal energy may not require a SN-like energy budget for SN1994W.

Dessart, Luc; Hillier, D. John; Gezari, Suvi; Basa, Stéphane; Matheson, Tom

2009-03-01

376

Europa's Icy Shell: A Bridge Between Its Surface and Ocean  

NASA Technical Reports Server (NTRS)

Europa, a Moon-sized, ice-covered satellite of Jupiter, is second only to Mars in its astrobiological potential. Beneath the icy surface, an ocean up to 150 km deep is thought to exist, providing a potential habitat for life,and a tempting target for future space missions. The Galileo mission to the Jovian system recently ended, but there are already long-range plans to send much more capable spacecraft,such as the proposed Jupiter Icy Moons Orbiter (JIMO), to take a closer look at Europa and her siblings, Ganymede and Callisto, some time in the next two decades. Europak outer icy shell is the only interface between this putative ocean and the surface, but many aspects of this shell are presently poorly understood; in particular, its composition, thickness, deformational history, and mechanical properties. To discuss the ice shell and our current understanding of it, 78 scientists from the terrestrial and planetary science communities in the United States and Europe gathered for a 3-day workshop hosted by the Lunar and Planetary Institute in Houston in February. A key goal was to bring researchers from disparate disciplines together to discuss the importance and limitations of available data on Europa with a post-Galileo perspective. The workshop featured 2 days of reviews and contributed talks on the composition, physical properties, stratigraphy, tectonics, and future exploration of the ice shell and underlying ocean. The final morning included an extended discussion period, moderated by a panel of noted experts, highlighting outstanding questions and areas requiring future research.

Schenk, Paul; Mimmo, Francis; Prockter, Louise

2004-01-01

377

Effect of low cost shell coatings and storage conditions on the raw and cooked qualities of shell egg Efecto de recubrimientos de cascara de bajo coste y de las condiciones de almacenaje sobre la calidad de huevos crudos y cocinados  

Microsoft Academic Search

The effect of shell coating materials (odorless petroleum jelly and paraffin wax) and storage conditions (ambient and refrigerated) on the internal quality such as the Haugh unit, yolk index, albumen pH, albumen soluble solids, and sensory qualities of boiled eggs (ease of peeling, surface smoothness and odor of hard-boiled and peeled eggs) were evaluated over 9 weeks of storage. Generally,

T. A. Shittu; O. Ogunjinmi

2011-01-01

378

The curse of physiology—challenges and opportunities in the interpretation of geochemical data from mollusk shells  

NASA Astrophysics Data System (ADS)

Physiology corrupts geochemical records of mollusk shells in many ways, e.g., by actively controlling the incorporation of trace elements in the skeleton. However, the effects of variable biomineralization rates and growth cessation have largely remained unconsidered. Mediated by endogenous timekeeping mechanisms, mollusks stop growing skeletal material on a regular basis ranging from ultradian to annual timescales. During growth cessation, the shells do not record environmental conditions. Shell growth also stops when environmental conditions are beyond the physiological tolerance of the organism, e.g., above and below genetically determined, species-specific thermal extremes where shell growth slows and eventually ceases. Such growth disruptions can occur at non-periodic time intervals. Due to growth retardations and halts, proxy records of mollusk shells are thus incomplete, and reconstructed environmental amplitudes prone to truncation. Furthermore, environmental records are biased toward the physiological optimum of the animal. Favorable environmental conditions increase shell growth, whereas adverse environmental conditions result in reduced shell production and lowered overall metabolism. Not least, the duration of the growing season and overall growth rate decrease as the mollusk grows older. Mathematical modeling approaches can significantly improve proxy records obtained from mollusk shells. For example, if the duration of growth cessation is known, it may be possible to model the missing environmental record. It is also fairly easy to account for age-related growth trends, or variable time-averaging in different portions of the shell. However, a major premise for a reliable interpretation of proxy records from a mollusk shell or other organisms secreting biogenic hard parts is a proper understanding of the physiology, and of course, a high-resolution record of the many different environmental factors that may influence physiology and shell growth. The present paper reviews examples from the literature, and unpublished data on how physiology influences geochemical proxy records from mollusk shells, and presents methods how to eliminate such adverse effects.

Schöne, Bernd R.

2008-10-01

379

Controlled synthesis and magnetic properties of bimagnetic spinel ferrite CoFe2O4 and MnFe2O4 nanocrystals with core-shell architecture.  

PubMed

A combination of hard phase CoFe(2)O(4) and soft phase MnFe(2)O(4) as the bimagnetic nanocrystals in a core-shell architecture has been synthesized, and their magnetic properties have been systematically studied. Both HRTEM and EDS results confirmed the formation of bimagnetic core-shell structured nanocrystals. On the basis of the systematic and comparative studies of the magnetic properties of a mechanical mixture of pure CoFe(2)O(4) and MnFe(2)O(4) nanocrystals, chemically mixed Co(1-x)Mn(x)Fe(2)O(4) nanocrystals, and bimagnetic core-shell CoFe(2)O(4)@MnFe(2)O(4) and MnFe(2)O(4)@CoFe(2)O(4) nanocrystals, the bimagnetic core-shell nanocrystals show very unique magnetic properties, such as the blocking temperature and coercivity. Our results show that the coercivity correlates with the volume fraction of the soft phase as the theoretical hard-soft phase model has suggested. Furthermore, switching the hard phase CoFe(2)O(4) from the core to the shell shows great changes in the coercivity of the nanocrystals. The bimagnetic core-shell nanocrystals evidently demonstrate the rational design capability to separately control the blocking temperature and the coercivity in magnetic nanocrystals by varying the materials, their combination, and the volume ratio between the core and the shell and by switching hard or soft phase materials between the core and shell. Such controls via a bimagnetic core-shell architecture are highly desirable for magnetic nanocrystals in various applications. PMID:22621435

Song, Qing; Zhang, Z John

2012-06-20

380

Outer packet sets and feature prediction of computer virus  

NASA Astrophysics Data System (ADS)

The packet sets model was proposed by Prof. Shi in 2008. A packet sets is a set pair composed of internal and outer packet sets, and it has dynamic characteristic. Using packet sets theory, this paper gives the feature prediction of computer virus based on outer packet sets. The concept of virus screening-filtering is given, furthermore, the virus screening-filtering order theorem, composite virus screening-filtering theorem and virus screening-filtering rule are presented. A prediction method of computer virus feature is given based on the results. The outer packet sets is a new tool in the research of the prediction of dynamic virus feature.

Zhang, Ling

2014-10-01

381

Self-sterilization of bodies during outer planet entry  

NASA Technical Reports Server (NTRS)

A body encountering the atmosphere of an outer planet is subjected to heat loads which could result in high temperature conditions that render terrestrial organisms on or within the body nonviable. To determine whether an irregularly shaped entering body, consisting of several different materials, would be sterilized during inadvertent entry at high velocity, the thermal response of a typical outer planet spacecraft instrument was studied. The results indicate that the Teflon insulated cable and electronic circuit boards may not experience sterilizing temperatures during a Jupiter, Saturn, or Titan entry. Another conclusion of the study is that small plastic particles entering Saturn from outer space have wider survival corridors than do those at Jupiter.

Hoffman, A. R.; Jaworski, W.; Taylor, D. M.

1974-01-01

382

Radioisotope Reduction Using Solar Power for Outer Planetary Missions  

NASA Technical Reports Server (NTRS)

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.

Fincannon, James

2008-01-01

383

Outer membrane translocons: structural insights into channel formation.  

PubMed

Gram-negative bacteria need to maintain the integrity of their outer membrane while also regulating the secretion of toxins and other macromolecules. A variety of dedicated outer membrane proteins (OMPs) facilitate this process. Recent structural work has shown that some of these proteins adopt classical ?-barrel transmembrane structures and rely on structural changes within the barrel lumen to allow passage of substrate proteins. Other secretion systems have OMP components which use transmembrane ?-helices and appear to function in a different way. Here we review a selection of recent structural studies which have major ramifications for our understanding of the passage of macromolecules across the outer membrane. PMID:21130656

Karuppiah, Vijaykumar; Berry, Jamie-Lee; Derrick, Jeremy P

2011-01-01

384

Comparison of two sensors for outer planet mission onboard navigation.  

NASA Technical Reports Server (NTRS)

Onboard instruments have been shown to be an effective aid to navigation on missions to the outer planets. The relationship of two possible candidate navigation instruments, an image tube (television) and a scanning photometer, with other systems such as data processing and attitude control is discussed. Certain key problem areas relating to the design of each sensor are considered, and the scientific uses of each sensor are examined. The navigational efficacy of both instruments is illustrated by some selected results from a navigation and guidance simulation of outer planet missions. It is concluded that both devices are viable alternatives for onboard outer planet navigation.

Malchow, H. L.; Sackett, L. L.

1972-01-01

385

Molluscan shell evolution with review of shell calcification hypothesis.  

PubMed

Biomineralization research on mollusc shells has mostly focused on nacre formation. Chitin, silk fibroin protein, and acidic macromolecules are important components for shell formation. Although the principle concept behind shell calcification was developed many years ago, the individual components have not been well scrutinized. Besides that, Mollusca are the second largest invertebrate phylum, but comprehensive biochemical research involving a comparison of different taxa is still rare. This study reconsiders the above three components with adding some biochemical data of aculiferans. The presence of chitin in polyplacophorans sclerites was confirmed by IR and pyrolysis GC/MS. DMMB staining data inferred that sulphated groups present in aplacophoran cuticle but not in polyplacophorans cuticle. These insight suggested importance of comparison between acuriferans and conchiferans. PMID:19665573

Furuhashi, Takeshi; Schwarzinger, Clemes; Miksik, Ivan; Smrz, Miloslav; Beran, Anton

2009-11-01

386

14C and ?13C in Mytilus californianus shells as a proxy of upwelling intensity  

NASA Astrophysics Data System (ADS)

Along the west coast of North America, climate and marine productivity is strongly affected by seasonal to interannual changes in coastal upwelling intensity. Our understanding of the variability of upwelling on these timescales in the past is limited by the short duration of instrumental records. Changes in upwelling intensity are expected to affect the ?13C and radiocarbon (14C) content of seawater dissolved inorganic carbonate (DIC) due to the variable mixing of old, upwelled seawater into surface waters. If these seasonal variations in the carbon isotope composition of seawater DIC are recorded in marine bivalve shells then they have the potential to provide valuable information about the extent of upwelling in these regions in the past. However, bivalve shell carbon isotope compositions are complicated by a number of factors including the contribution of metabolic carbon. To examine whether the carbon isotope compositions of California mussel (Mytilus californianus) shells could be used to produce records of upwelling intensity we collected living mussels from Newport Beach, CA. Sequential samples were generated from the outer calcite layer of these shells and analyzed for stable isotopes, trace elements and radiocarbon. These geochemical profiles are compared with instrumental records and a nearby timeseries of seawater DIC ?13C and 14C. We show that seasonal Mytilus californianus shell 14C values agree well with seawater DIC 14C measurements. Interpretation of ?13C is more problematic with shell ?13C lower than measured seawater DIC ?13C by up to 1 ‰, consistent with what might be expected due to incorporation of metabolic carbon. Results are also presented from Mytilus californianus shells, collected from Mexico to Oregon following the strong El Niño event of 1997-1998. This event caused a collapse of upwelling and provides an ideal opportunity to examine whether the carbon isotope composition of Mytilus californianus shells show evidence of the dramatic changes occurring within the California Current system at this time.

Ferguson, J. E.; Johnson, K. R.; Santos, G. M.; Meyer, L.; Acaylar, K.; Tripati, A. K.

2010-12-01

387

The Structure of Nova Shells  

NASA Astrophysics Data System (ADS)

Recent WFPC2 observations of the recurrent nova T Pyxidis show that the ejected material from the previous eruptions is neither uniform nor isotropic. Rather, the ejecta is distributed in hundreds of unresolved knots. If this result is the norm for all nova ejecta then all previous mass estimates and ejection models for nova shells are probably incorrect. Observationally determined masses of nova shells provide a very important test to the nova theory. We are proposing to use WFPC2 to determine if 1) all nova shells are in fact broken into knots, and, for the closest shells, 2) to determine the size distribution of these knots. In addition WFPC2 observations of T Pyxidis will enable us to determine whether the clumpy shell is expanding. Finally, we are asking for a reendorsement (granted in cycles 1 and 4) to observe the effects of the next eruption of T Pyx (once in a generation and now several years overdue) on its multitude of circumstellar knots.

Shara, Michael

1995-07-01

388

Semiclassical environment of collapsing shells  

SciTech Connect

We explore in detail the semiclassical environment of collapsing shells of matter, and determine the semiclassical flux measured by a variety of observers. This study is a preliminary step in a broader investigation of thermodynamic properties of the geometry of collapsing objects. Specifically, in this paper we consider spherically symmetric null and timelike collapsing shells which form an event horizon, and calculate the flux measured by observers both inside and outside the shell, and both inside and outside the event horizon, and find nontrivial results in most of the cases. Additionally, we also investigate the environment of a shell which collapses but does not form a horizon, halting at some radius larger than the Schwarzschild radius, and find that such an object generically gives rise to a pulse of radiation which is sharply peaked as it travels inwards and is reflected at the origin, and eventually emerges from the shell in a thermalized form. Our results have potential consequences in addressing questions pertaining, e.g. to black hole entropy and backreaction.

Banerjee, Kinjal; Paranjape, Aseem [IUCAA, Post Bag 4, Ganeshkhind, Pune-411 007 (India); Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai-400 005 (India)

2009-12-15

389

Eggstreme Mechanics of Thin Shells  

NASA Astrophysics Data System (ADS)

I will present a series of experimental explorations on the rich mechanical behavior of thin elastic shells, subject to different forms of loading. First, I will discuss the geometry-induced rigidity of non-spherical pressurized shells under indentation, that can be used for non-destructive testing. I will proceed by characterizing the emergence and evolution of point and linear-like loci of localization on thin shells indented well into the nonlinear regime. I will then present a new mechanism that utilizes the compression of a thin-shell/soft-core system for switchable and tunable wrinkling on curved surfaces, that can be exploited for active aerodynamic drag control. Finally, I shall introduce the framework for buckling-induced folding (or ``Buckligami'') that involves functional structural transformations of patterned shells that can be excited to achieve encapsulation, flexure and twist. The main common feature underlying these series of examples is the prominence of geometry in dictating the complex mechanical behavior of slender soft structures, thereby making our results relevant and applicable over a wide range of length scales. Moreover, our findings suggest that we rethink our relationship with mechanical instabilities which, rather than modes of failure, can be embraced as opportunities for functionality that are scalable, reversible, and robust.

Reis, Pedro

2013-03-01

390

Outer Solar System on the Edge of Chaos  

Microsoft Academic Search

The existence of chaos among the system of Jovian planets (Jupiter, Saturn, Uranus, and Neptune) is not yet firmly established. Although Laskar originally found no chaos in the outer Solar System, his \\

Wayne B. Hayes

2006-01-01

391

49 CFR 192.10 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

392

49 CFR 192.10 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

393

49 CFR 195.9 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

394

49 CFR 192.10 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

395

49 CFR 195.9 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2010 CFR

...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...

2010-10-01

396

49 CFR 192.10 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2011 CFR

...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...

2011-10-01

397

49 CFR 195.9 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2013 CFR

...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...

2013-10-01

398

49 CFR 195.9 - Outer continental shelf pipelines.  

Code of Federal Regulations, 2012 CFR

...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...

2012-10-01

399

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

400

Electron beam seals outer surfaces of porous bodies  

NASA Technical Reports Server (NTRS)

Porous tungsten plugs provide even airflow for frictionless bearings used in air bearing supported gyros. The plugs have their outer cylindrical surface sealed by an electron beam process to ensure unidirectional airflow through their exit ends.

Herz, W. H.; Kurtz, A. D.; Kurtz, R. A.

1966-01-01

401

Fault tolerant, radiation hard, high performance digital signal processor  

NASA Technical Reports Server (NTRS)

An architecture has been developed for a high-performance VLSI digital signal processor that is highly reliable, fault-tolerant, and radiation-hard. The signal processor, part of a spacecraft receiver designed to support uplink radio science experiments at the outer planets, organizes the connections between redundant arithmetic resources, register files, and memory through a shuffle exchange communication network. The configuration of the network and the state of the processor resources are all under microprogram control, which both maps the resources according to algorithmic needs and reconfigures the processing should a failure occur. In addition, the microprogram is reloadable through the uplink to accommodate changes in the science objectives throughout the course of the mission. The processor will be implemented with silicon compiler tools, and its design will be verified through silicon compilation simulation at all levels from the resources to full functionality. By blending reconfiguration with redundancy the processor implementation is fault-tolerant and reliable, and possesses the long expected lifetime needed for a spacecraft mission to the outer planets.

Holmann, Edgar; Linscott, Ivan R.; Maurer, Michael J.; Tyler, G. L.; Libby, Vibeke

1990-01-01

402

Fault tolerant, radiation hard, high performance digital signal processor  

NASA Astrophysics Data System (ADS)

An architecture has been developed for a high-performance VLSI digital signal processor that is highly reliable, fault-tolerant, and radiation-hard. The signal processor, part of a spacecraft receiver designed to support uplink radio science experiments at the outer planets, organizes the connections between redundant arithmetic resources, register files, and memory through a shuffle exchange communication network. The configuration of the network and the state of the processor resources are all under microprogram control, which both maps the resources according to algorithmic needs and reconfigures the processing should a failure occur. In addition, the microprogram is reloadable through the uplink to accommodate changes in the science objectives throughout the course of the mission. The processor will be implemented with silicon compiler tools, and its design will be verified through silicon compilation simulation at all levels from the resources to full functionality. By blending reconfiguration with redundancy the processor implementation is fault-tolerant and reliable, and possesses the long expected lifetime needed for a spacecraft mission to the outer planets.

Holmann, Edgar; Linscott, Ivan R.; Maurer, Michael J.; Tyler, G. L.; Libby, Vibeke

403

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

PubMed Central

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

Otto, Andreas; Becher, Dörte; Vogel, Ulrich

2013-01-01

404

Chaos in the Outer Solar System may be indeterminate  

Microsoft Academic Search

Consider a multi-hundred-million-year integration of the 5-body system consisting of the Sun, Jupiter, Saturn, Uranus, and Neptune. We term such an integration a long-term integration of the Outer Solar System. Such integrations have been performed repeatedly since the late 1980s and early 1990s, and many researchers performing such integrations have found that the isolated Outer Solar System is chaotic, with

W. B. Hayes

2005-01-01

405

OIL AND GAS LEASING ON THE OUTER CONTINENTAL SHELF  

E-print Network

OIL AND GAS LEASING ON THE OUTER CONTINENTAL SHELF M i n e r a l s M a n a g e m e n t S e r v i c e www.mms.gov #12;OIL AND GAS LEASING ON THE OUTER CONTINENTAL SHELF Background The Minerals.7 billion acres containing over 8,000 active leases in this federally owned offshore area, while protecting

Lotko, William

406

STAR FORMATION IN THE OUTER DISK OF SPIRAL GALAXIES  

SciTech Connect

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.

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

407

Chemical Analysis Of Beryllium Shells  

SciTech Connect

There is a need to understand the level of high-Z impurities in Beryllium shells prepared by sputter coating. The Ignition Point Design Requirements state the following: ''Except for allowed ingredients, as listed in the ablator composition entries, the ablator material in all layers shall contain sufficiently low impurity levels that the sum over all impurities of atom fraction*Z{sup 2} shall be less than or equal to 0.2''. This is a tight specification that requires careful materials analysis. Early in the first quarter of FY06, we undertook a study of Be shell impurities via ICP-MS{sup 2} and determined that the impurity levels in the sputtered shells are very close to the specification.

Gunther, J; Cook, R

2005-11-17

408

Lovelock Thin-Shell Wormholes  

E-print Network

We construct the asymptotically flat charged thin-shell wormholes of Lovelock gravity in seven dimensions by cut-and-paste technique, and apply the generalized junction conditions in order to calculate the energy-momentum tensor of these wormholes on the shell. We find that for negative second order and positive third order Lovelock coefficients, there are thin-shell wormholes that respect the weak energy condition. In this case, the amount of normal matter decreases as the third order Lovelock coefficient increases. For positive second and third order Lovelock coefficients, the weak energy condition is violated and the amount of exotic matter decreases as the charge increases. Finally, we perform a linear stability analysis against a symmetry preserving perturbation, and find that the wormholes are stable provided the derivative of surface pressure density with respect to surface energy density is negative and the throat radius is chosen suitable.

M. H. Dehghani; M. R. Mehdizadeh

2011-11-24

409

Dual shell pressure balanced vessel  

DOEpatents

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.

Fassbender, Alexander G. (West Richland, WA)

1992-01-01

410

Ultrasonic material hardness depth measurement  

DOEpatents

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.

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

1997-07-08

411

Weld cladding of hard surfaces  

NASA Astrophysics Data System (ADS)

A literature study about clad welding of hard surfaces on steel is performed. The purpose was to see what kind of methods are mainly used, and particular attention is paid to clad welding of rolls. The main impression from this study is that several methods are in use. Some of these must be considered as 'too exotic' for the aim of the program, such as laser build-up welding. However, clad welding of hard surfaces to rolls is widely used around the world, and there is no need for particularly advanced welding methods to perform the work. The welding consumables and the way the welding is carried out is of more important character. The report will give some comments to this, and hopefully will give a short review of the current technology in this field.

Habrekke, T.

1993-02-01

412

Imaging outer segment renewal in living human cone photoreceptors.  

PubMed

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 microm/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

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

2010-03-01

413

Imaging outer segment renewal in living human cone photoreceptors  

PubMed Central

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

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

2011-01-01

414

78 FR 40394 - Safety Zone; Outer Banks Bluegrass Festival; Shallowbag Bay, Manteo, NC  

Federal Register 2010, 2011, 2012, 2013, 2014

...Zone; Outer Banks Bluegrass Festival, Shallowbag Bay, Manteo...of the Outer Banks Bluegrass Festival. The temporary safety zone...of the Outer Banks Bluegrass Festival Fireworks Display. The fireworks...geographic coordinates are North American Datum 1983 (NAD 83)....

2013-07-05

415

Shell disturbances and butyltins burden in commercial bivalves collected from the Bizerta lagoon (northern Tunisia).  

PubMed

Shell disturbances and soft tissues butyltin burden were investigated in commercial bivalves Lithophaga lithophaga, Mytilus galloprovincialis, Solen marginatus and Crassostrea gigas from the Bizerta lagoon. Shell disturbances were found in all bivalves, being scarce in S. marginatus. In the internal valve of L. lithophaga, burrowing annelids and sipunculids living inside galleries were observed, while in the external valve, brown-blackish or white stains were found. In M. galloprovincialis, a yellowish mass located at the shell anterior side was found fixed firmly to the pearly layer by a hard brownish structure covering some annelid elliptic eggs. In the internal shell layer of some specimens collected in April, embryos belonging to tubiculous annelids at various developmental stages were observed. In C. gigas, shell thickening was revealed in some specimens corresponding to white doughy deposits at the internal valve and between shell layers. In S. marginatus, only one specimen showing a cavity at the posterior site was found. Total butyltin concentrations in the studied bivalves varied between 30 and 245 ng/g dry weight with tributyltin (TBT) being the predominant compound. The highest concentration was recorded in L. lithophaga collected from the Bizerta Bay and the lowest concentration in S. marginatus from Maghraoua. This study provided baseline data that could serve for long-term monitoring of TBT pollution in Tunisia, since legislation to reduce the use of TBT-based antifouling paints has not been introduced yet. PMID:22170157

Kefi, Ferdaous Jaafar; Lahbib, Youssef; Abdallah, Lamia Gargouri Ben; El Menif, Najoua Trigui

2012-11-01

416

Hard Disk PVT System Model  

NSDL National Science Digital Library

The Hard Disk PVT System simulates a two-dimensional system of particles confined between a thermal reservoir and a piston. This computer model is designed to study the equation of state for hard disks without other interactions. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. Users can set the initial particle energy, the initial particle separation, and the thermal reservoir temperature Tr. The thermal conductivity parameter ? determines the probability that a collision with the thermal wall will affect (thermalize) the colliding particle. If the conductivity is one, the particle velocity after a reservoir collision is set according to Maxwell-Boltzmann statistics. If the conductivity is zero, all reservoir collisions are elastic and the internal energy E of the system is conserved.   Particles in this model have unit mass and interact through contact forces. Collision times are computed analytically because particles and pistons move with constant velocity between collisions. The time evolution algorithm advances the particle and piston positions from collision to collision until the requested time step ?t is achieved. The time evolution is then paused, data is accumulated, and the screen is redrawn. The Hard Disk PVT model is a supplemental simulation for the article "Pressure Oscillations in Adiabatic Compression" by Roland Stout in The Physics Teacher 49(5), 280-281 (2011) and has been approved by the author and The Physics Teacher editor. The model was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_HardDiskPVTSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-03-12

417

Hardness of Electrodeposited Nano-Nickel Revisited  

NASA Astrophysics Data System (ADS)

In the past, hardness measurements on nanocrystalline metals were limited to Vickers microhardness and nano-indentation tests, mainly due to sample size/thickness limitations. On the other hand, most industries require hardness values on the Rockwell scale and make extensive use of hardness conversion relationships for various hardness scales. However, hardness conversions currently do not exist for nanocrystalline metals. With recent advances in electrodeposition technology, thicker specimens with a wide range of grain sizes can now be produced. In this study, the relationships between Vickers and Rockwell hardness scales have been developed for such materials. In addition, hardness indentations were used to gain further insight into the work hardening of nanocrystalline and polycrystalline nickel. Vickers microhardness and nano-indentation profiles below large Rockwell indentations showed that polycrystalline nickel exhibited considerable strain hardening, as expected. On the other hand, for nanocrystalline nickel the micro-Vickers and nano-indentations hardness profile showed low strain hardening capacity.

Tang, Bill Tsz Fai

418

Spherical-shell model for the van der Waals coefficients between fullerenes and/or nearly spherical nanoclusters.  

PubMed

Fullerene molecules such as C(60) are large nearly spherical shells of carbon atoms. Pairs of such molecules have a strong long-range van der Waals attraction that can produce scattering or binding into molecular crystals. A simplified classical-electrodynamics model for a fullerene is a spherical metal shell, with uniform electron density confined between outer and inner radii (just as a simplified model for a nearly spherical metallic nanocluster is a solid metal sphere or filled shell). For the spherical-shell model, the exact dynamic multipole polarizabilities are all known analytically. From them, we can derive exact analytic expressions for the van der Waals coefficients of all orders between two spherical metal shells. The shells can be identical or different, and hollow or filled. To connect the model to a real fullerene, we input the static dipole polarizability, valence electron number and estimated shell thickness t of the real molecule. Our prediction for the leading van der Waals coefficient C(6) between two C(60) molecules ((1.30 ± 0.22) × 10(5) hartree bohr(6)) agrees well with a prediction for the real molecule from time-dependent density functional theory. Our prediction is remarkably insensitive to t. Future work might include the prediction of higher-order (e.g. C(8) and C(10)) coefficients for C(60), applications to other fullerenes or nearly spherical metal clusters, etc. We also make general observations about the van der Waals coefficients. PMID:23032569

Perdew, John P; Tao, Jianmin; Hao, Pan; Ruzsinszky, Adrienn; Csonka, Gábor I; Pitarke, J M

2012-10-24

419

Facile and green synthesis of core-shell structured magnetic chitosan submicrospheres and their surface functionalization.  

PubMed

Submicrometer-sized magnetite colloid nanocrystal clusters (MCNCs) provide a new avenue for constructing uniformly sized and highly magnetic composite submicrospheres. Herein, a facile and eco-friendly method is described for the synthesis of Fe3O4@poly(acrylic acid) (PAA)/chitosan (CS) core-shell submicrospheres using MCNCs bearing carboxyl groups as the magnetic cores. It is based on the self-assembly of positively charged CS chains on the surface of the oppositely charged MCNCs dispersed in the aqueous solution containing acrylic acid (AA) and a cross-linker N,N'-methylenebis(acrylamide) (MBA), followed by radical induced cross-linking copolymerization of AA and MBA along the CS chains. The resulting polymer shell comprises a medium shell of cross-linked PAA/CS polyelectrolyte complexes and an outer shell of protonated CS chains. It was found that the shell thickness could be tuned by varying either the concentration of radical initiator or the molar ratio of AA to aminoglucoside units of CS. To the surface of thus obtained Fe3O4@PAA/CS particles, Au nanoparticles, a variety of functional groups such as fluorescein, carboxyl, quaternary ammonium, and aliphatic bromide, and even functional polymer chains were successfully introduced. Therefore, such Fe3O4@PAA/CS submicrospheres may be used as versatile magnetic functional scaffolds in biorelated areas like bioseparation and medical assay, considering the unique features of CS like nontoxicity and biocompatibility. PMID:23968226

Li, Yiya; Yuan, Dongying; Dong, Mingjie; Chai, Zhihua; Fu, Guoqi

2013-09-17

420

Dusty shells surrounding the carbon variables S Scuti and RT Capricorni  

NASA Astrophysics Data System (ADS)

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

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

421

7 CFR 201.57 - Hard seeds.  

Code of Federal Regulations, 2010 CFR

... 3 2010-01-01 2010-01-01 false Hard seeds. 201.57 Section 201.57 Agriculture...Tests in the Administration of the Act § 201.57 Hard seeds. Seeds which remain hard at the end of the prescribed test because they...

2010-01-01

422

30 CFR 57.15002 - Hard hats.  

Code of Federal Regulations, 2010 CFR

...1 2010-07-01 2010-07-01 false Hard hats. 57.15002 Section 57.15002 Mineral...Protection Surface and Underground § 57.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where...

2010-07-01

423

7 CFR 201.30 - Hard seed.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Hard seed. 201.30 Section 201.30 Agriculture...REGULATIONS Labeling Vegetable Seeds § 201.30 Hard seed. The label shall show the percentage of hard seed, if any is present, for any seed...

2010-01-01

424

7 CFR 201.21 - Hard seed.  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 2010-01-01 false Hard seed. 201.21 Section 201.21 Agriculture... Labeling Agricultural Seeds § 201.21 Hard seed. The label shall show the percentage of hard seed, if any is present, for any seed...

2010-01-01

425

30 CFR 56.15002 - Hard hats.  

Code of Federal Regulations, 2010 CFR

...1 2010-07-01 2010-07-01 false Hard hats. 56.15002 Section 56.15002 Mineral...MINES Personal Protection § 56.15002 Hard hats. All persons shall wear suitable hard hats when in or around a mine or plant where...

2010-07-01

426

Artificially soft and hard surfaces in electromagnetics  

Microsoft Academic Search

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

Per-Simon Kildal

1990-01-01

427

Online Diagnosis of Hard Faults in Microprocessors  

E-print Network

Online Diagnosis of Hard Faults in Microprocessors FRED A. BOWER Duke University and IBM Systems Paper: Fred A. Bower, Daniel J. Sorin, and Sule Ozev. "A Mechanism for Online Diagnosis of Hard Faults. Online diagnosis of hard faults in microprocessors. Architec. Code Optim. 4, 2, Article 8 (June 2007),

Sorin, Daniel J.

428

Warren G. Harding and the Press.  

ERIC Educational Resources Information Center

There are many parallels between the Richard M. Nixon administration and Warren G. Harding's term: both Republicans, both touched by scandal, and both having a unique relationship with the press. But in Harding's case the relationship was a positive one. One of Harding's first official acts as president was to restore the regular White House news…

Whitaker, W. Richard

429

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)

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.

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

430

Abrading increases oxygen and hardness of titanium surface.  

PubMed

CP Ti was mirror-polished and then abraded with waterproof SiC papers of two different grit sizes: 16 and 3 microm. As-polished and abraded surfaces were characterized by means of EPMA, XPS, XRD, and hardness test. Oxygen in the mirror-polished surface was uniformly distributed at the lowest level. Comparatively, abrading with SiC papers increased the surface oxygen amount and hardness. Owing to its excellent abrasivity, the coarse grit efficiently scratched the surface and hindered the regenerated oxide film from growing thick, but allowed only the metal-oxide interfacial gradient zone to extend. But, the fine grit merely rubbed the surface and allowed both the oxide film and interfacial zone to extend. Further, the surface appeared to be lightly yellow-colored, suggesting that the oxide film was thicker, probably within 10 nm, than the nominal one. When compared with the bulk, the interfacial zone was rich in oxygen and therefore subjected to high coherency strain, which was introduced to relieve the great lattice mismatch between the outer and inner layers of titanium substrate. Effects of solute oxygen hardening and strain hardening were speculated to be responsible for the surface hardening of both SiC-abraded surfaces. In conclusion, abrading with a coarse grit led to accumulation of a high, non-uniform strain in the titanium substrate, thereby hardening the surface further. PMID:16706291

Miyakawa, Osamu; Okawa, Seigo; Kobayashi, Masayoshi

2006-03-01

431

Alternative mechanisms of increased eggshell hardness of avian brood parasites relative to host species  

PubMed Central

Obligate brood parasitic birds lay their eggs in nests of other species and parasite eggs typically have evolved greater structural strength relative to host eggs. Increased mechanical strength of the parasite eggshell is an adaptation that can interfere with puncture ejection behaviours of discriminating hosts. We investigated whether hardness of eggshells is related to differences between physical and chemical traits from three different races of the parasitic common cuckoo Cuculus canorus, and their respective hosts. Using tools developed for materials science, we discovered a novel correlate of increased strength of parasite eggs: the common cuckoo's egg exhibits a greater microhardness, especially in the inner region of the shell matrix, relative to its host and sympatric non-host species. We then tested predictions of four potential mechanisms of shell strength: (i) increased relative thickness overall, (ii) greater proportion of the structurally harder shell layers, (iii) higher concentration of inorganic components in the shell matrix, and (iv) elevated deposition of a high density compound, MgCO3, in the shell matrix. We confirmed support only for hypothesis (i). Eggshell characteristics did not differ between parasite eggs sampled from different host nests in distant geographical sites, suggesting an evolutionarily shared microstructural mechanism of stronger parasite eggshells across diverse host-races of brood parasitic cuckoos. PMID:21561966

Igic, Branislav; Braganza, Kim; Hyland, Margaret M.; Silyn-Roberts, Heather; Cassey, Phillip; Grim, Tomas; Rutila, Jarkko; Moskát, Csaba; Hauber, Mark E.

2011-01-01

432

Anadara grandis - Shell Valve Internal View  

USGS Multimedia Gallery

Anadara grandis seashell, internal view, with scars of the anterior and posterior adductor muscles. The shell has El Rosario, Coxiguina, written in the interior of the shell. Photograph taken 2002 or earlier....

433

Structural Analysis Of General Shells (STAGS)  

NASA Technical Reports Server (NTRS)

STAGS models complex thin shell structures including separate shell branches or segments connected along their boundaries. Options include static stress and vibration, transient, and bifurcation buckling analysis. Also useful for submarine design.

Almroth, B. O.; Brogan, F. A.; Stanley, G. M.

1993-01-01

434

Insights from multiple structures of the shell proteins from the [beta]-carboxysome  

SciTech Connect

Carboxysomes are primitive bacterial organelles that function as a part of a carbon concentrating mechanism (CCM) under conditions where inorganic carbon is limiting. The carboxysome enhances the efficiency of cellular carbon fixation by encapsulating together carbonic anhydrase and the CO{sub 2}-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). The carboxysome has a roughly icosahedral shape with an outer shell between 800 and 1500 {angstrom} in diameter, which is constructed from a few thousand small protein subunits. In the cyanobacterium Synechocystis sp. PCC 6803, the previous structure determination of two homologous shell protein subunits, CcmK2 and CcmK4, elucidated how the outer shell is formed by the tight packing of CcmK hexamers into a molecular layer. Here we describe the crystal structure of the hexameric shell protein CcmK1, along with structures of mutants of both CcmK1 and CcmK2 lacking their sometimes flexible C-terminal tails. Variations in the way hexamers pack into layers are noted, while sulfate ions bound in pores through the layer provide further support for the hypothesis that the pores serve for transport of substrates and products into and out of the carboxysome. One of the new structures provides a high-resolution (1.3 {angstrom}) framework for subsequent computational studies of molecular transport through the pores. Crystal and solution studies of the C-terminal deletion mutants demonstrate the tendency of the terminal segments to participate in protein-protein interactions, thereby providing a clue as to which side of the molecular layer of hexameric shell proteins is likely to face toward the carboxysome interior.

Tanaka, S.; Sawaya, M.R.; Phillips, M.; Yeates, T.O.; (UCLA)

2009-03-02

435

Shell Centre for Mathematical Education  

NSDL National Science Digital Library

The Shell Centre for Mathematical Education, a centre for research and development within the School of Education at the University of Nottingham, offers WWW pages which includes a collection of information technologies used in the classroom, details of publications and research, as well as a Distractions Page "intended to contain entertaining items of varying degrees of educational value."

436

Finite element shell instability analysis  

NASA Technical Reports Server (NTRS)

Formulation procedures and the associated computer program for finite element thin shell instability analysis are discussed. Data cover: (1) formulation of basic element relationships, (2) construction of solution algorithms on both the conceptual and algorithmic levels, and (3) conduction of numerical analyses to verify the accuracy and efficiency of the theory and related programs therein are described.

1975-01-01

437

Shell structures for biogas plants  

SciTech Connect

The shell structures designed for biogas plants of the fixed-dome type by the Bremen Overseas Research and Development Association are described. Biogas digesters of the design described have been successfully tested in Rwanda and India without structural or contractural problems.

Sasse, L.

1982-01-01

438

Hard body amphiphiles at a hard wall JOSEPH M. BRADER1y  

E-print Network

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

Ott, Albrecht

439

Facile synthesis of yolk-shell magnetic mesoporous carbon microspheres for efficient enrichment of low abundance peptides.  

PubMed

Magnetic mesoporous carbon microspheres with a yolk-shell structure (YSMMCS) have been prepared via a new in situ carbon source strategy. The material was fabricated by two shells coated onto the Fe3O4 particles; the inner dense and thick silica shell could protect the magnetic core from harsh acidic solvents as well as induce the void between the core and the outer shell for the yolk-shell structure, while the outer organosilica shell was used as the template and carbon source for in situ preparation of a carbon shell with mesoporous structure. A C18-alkyl chain was incorporated in situ as the carbon precursor efficiently, avoiding the conventional infiltration step, which was very difficult to manipulate and time-consuming with the possibility of losing the carbon precursor. The resulting yolk-shell magnetic mesoporous carbon microspheres exhibited a high surface area (273.15 m(2) g(-1)), a large pore volume (0.31 cm(3) g(-1)), and a strong magnetic response (a saturation magnetization value of 34.57 emu g(-1)). As a result of the void between the core and the outer shell and the ?-? stacking effect, adsorption capacity reached 191.64 mg g(-1) by using Rhodamine B as a standard analyte, indicating the great potential application of the material as drug carriers. Owing to the inherent hydrophobicity and high surface area, the composite material showed better performance in the enrichment of peptides than a magnetic mesoporous silica material (Fe2O3@nSiO2@mSiO2). According to the LC-MS/MS results, about 51 and 29 nonredundant peptides were identified from tryptic digests of 5 nM BSA. Additionally, taking advantage of the mesoporous structure and strong magnetic response, the material was utilized to selectively extract low abundance endogenous peptides from human serum in the presence of high abundance proteins. Based on the LC-MS/MS results, 962 endogenous peptides were obtained by 2.5 mg YSMMCS relative to 539 endogenous peptides by 5 mg Fe2O3@nSiO2@mSiO2, confirming the outstanding performance of YSMMCS in peptidome analysis. PMID:24061763

Wan, Hao; Qin, Hongqiang; Xiong, Zhichao; Zhang, Weibing; Zou, Hanfa

2013-11-21

440

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

PubMed

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

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

2010-10-01

441

Electronic shell structure in large metallic clusters  

Microsoft Academic Search

The investigation of shell structure in the ground states of atoms is limited to values of the angular momentum quantum number l<=3. In atomic nuclei, shells with l<=6 can be observed. We present evidence for shell structure in the electronic states of metal clusters for l<=12.

H. Göhlich; T. Lange; T. Bergmann; T. P. Martin

1990-01-01

442

Developments in Cylindrical Shell Stability Analysis  

NASA Technical Reports Server (NTRS)

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.

Knight, Norman F., Jr.; Starnes, James H., Jr.

1998-01-01

443

7 CFR 996.19 - Shelled peanuts.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2013-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the...

2013-01-01

444

7 CFR 996.19 - Shelled peanuts.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the...

2014-01-01

445

7 CFR 996.19 - Shelled peanuts.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the...

2011-01-01

446

7 CFR 996.19 - Shelled peanuts.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the...

2012-01-01

447

7 CFR 996.19 - Shelled peanuts.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Shelled peanuts. 996.19 Section 996.19 Agriculture...HANDLING STANDARDS FOR DOMESTIC AND IMPORTED PEANUTS MARKETED IN THE UNITED STATES Definitions § 996.19 Shelled peanuts. Shelled peanuts means the...

2010-01-01

448

7 CFR 981.6 - Shelled almonds.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Shelled almonds. 981.6 Section 981.6 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE ALMONDS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 981.6 Shelled almonds. Shelled almonds mean raw or...

2010-01-01

449

7 CFR 984.10 - Shelled walnuts.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Shelled walnuts. 984.10 Section 984.10 Agriculture...Nuts), DEPARTMENT OF AGRICULTURE WALNUTS GROWN IN CALIFORNIA Order Regulating Handling Definitions § 984.10 Shelled walnuts. Shelled walnuts means walnut...

2010-01-01

450

Mon. Not. R. Astron. Soc. 313, 17 (2000) The triple-shell structure and collimated outflows of the planetary nebula  

E-print Network

of the planetary nebula NGC 6891 Martõ�n A. Guerrero,1,2 Luis F. Miranda,3 Arturo Manchado1,4 and Roberto Va�zquez3 spectroscopy of the planetary nebula NGC 6891 are presented. These observations show a great wealth of structures. The bright central nebula is surrounded by an attached shell and a detached outer halo. Both

Vázquez, Roberto

451

The Hard Problem of Cooperation  

PubMed Central

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

Eriksson, Kimmo; Strimling, Pontus

2012-01-01

452

Interplanetary dust flux to the outer planet atmospheres  

NASA Astrophysics Data System (ADS)

It is now well established that an influx of external material is depositing significant amounts of oxygen into the atmospheres of the giant planets and Titan, which in turn impacts the energy budget, photochemistry, and structure of each body's atmosphere. While other sources (ie. Enceladus and/or the main ring system at Saturn, cometary impacts, etc.) also contribute, interplanetary dust grains are a significant source of external material to the outer planet atmospheres. In this talk, we present results from an interplanetary dust dynamics model used to calculate the distribution(s) of dust grains in the outer solar system that arise from Edgeworth-Kuiper Belt objects, Jupiter-family comets, and Halley-type comets. We constrain the densities of these distributions using in-situ measurements by the Pioneer meteoroid detectors and the New Horizons Student Dust Counter. In turn, we calculate the total dust influx distribution to each outer planet atmosphere, including any temporal or compositional variability and spatial anisotropies. Finally, we compare our influx estimates with those derived from extrapolating dust fluxes at 1 AU to the outer solar system and discuss implications for the outer planet atmospheres.

Poppe, A. R.; Moses, J. I.

2013-12-01

453

Agents that increase the permeability of the outer membrane.  

PubMed Central

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

Vaara, M

1992-01-01

454

An efficient depyrogenation method for recombinant bacterial outer membrane lipoproteins.  

PubMed

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

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

2014-06-01

455

Hard Scattering Studies at Jlab  

SciTech Connect

We present current activities and future prospects for studies of hard scattering processes using the CLAS detector and the CEBAF polarized electron beam. Kinematic dependences of single and double spin asymmetries have been measured in a wide kinematic range at CLAS with a polarized NH{sub 3} and unpolarized liquid hydrogen targets. It has been shown that the data are consistent with factorization and observed target and beam asymmetries are in good agreement with measurements performed at higher energies, suggesting that the high energy-description of the semi-inclusive DIS process can be extended to the moderate energies of JLab measurements.

Harutyun Avagyan; Peter Bosted; Volker Burkert; Latifa Elouadrhiri

2005-09-01

456

Nucleation simulation using a model of hard/soft discs  

NASA Astrophysics Data System (ADS)

In this paper we present a computer study of the quantum dot (QD) nucleation probability with three possible models of particle interaction; Soft Core (SC), Hard Core (HC) and Hard Core/Soft Shell (HCSS) model. Computer analysis of the nucleation probability is performed on a 500 by 500 lattice with 2000 simulations per event. If a matrix is assumed to represent an SiO2 substrate in which a pure Si quantum dot can grow, it is demonstrated that nucleation centers are more easily distinguished and initially more likely to form in the SC and HCSS models rather than in the HC model. If particles are allowed to move, nucleation centers can appear even in the HC model independent of a preexisting local density. A low probability of nucleation in the HC model and a high probability of nucleation in the SC model are evident from the system entropy curve. The probability of nucleation, therefore, depends on the local density change, percolation probability and system entropy. Low probability of nucleation in the HC model is in accordance with a lower probability of percolating clusters forming in a given model.

Milanovi?, Željka; Pivac, Branko; Zulim, Ivan

2015-01-01

457

H+-ATPase of crude homogenate of the outer mantle epithelium of Anodonta cygnea.  

PubMed

The outer mantle epithelium of the freshwater bivalve, Anodonta cygnea, is responsible for the mineralisation of the shell. Under short circuit conditions, it generates a current that is due to the operation of an electrogenic proton pump located in the apical barrier of that epithelium. Bafilomycin A1 and Concanamycin A inhibited the short circuit current. The IC50 and maximum inhibition dose were 0.17 and 0.5 microM for Bafilomycin A1, and 0.7 and 5 microM for Concanamycin A. The present work was undertaken to further characterise V-type ATPase of the outer mantle cells. The V-ATPase enzymatic activity of crude homogenate, measured as the amount of inorganic phosphorous released, due to ATP hydrolysis, in the presence of Na2SO3 (200 mM) was found to be 4.6+/-1.1 micromol Pi/mg protein/h, at 27 degrees C, pH 7.0-7.4 and ATP 4.5-6.0 microM. Bafilomycin A1 and Concanamycin A inhibit the V-ATPase activity with an IC50 of 14 and 8 nmol mg(-1), respectively. Dicyclohexylcarbodiimide (DCCD; 100 mM) and NaNO3 (100 microM) inhibited the V-type ATPase in what it seems a non-specific manner and NEM (100 mM) was unable to do it. Bafilomycin A1 (10 microM) and Concanamycin A (10 microM), inhibited 50-60% of the total activity. PMID:15596387

Oliveira, P F; Lopes, I A; Barrias, C; Rebelo da Costa, A M

2004-12-01

458

Of Cabbages and Kings: Opening the Hard Shell of Science Curriculum Policy.  

ERIC Educational Resources Information Center

Explains a proposal for society to be the driver for scientific literacy and the need to understand the roots of persistent difficulty in incorporating useful knowledge into the secondary school curriculum. Discusses changes taking place in the economy, the idea of enlisting industry as an ally to legitimate alternative forms of knowledge, and…

Gaskell, Jim

2002-01-01

459