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Sample records for abc ring system

  1. Genome-wide comparative analysis of ABC systems in the Bdellovibrio-and-like organisms

    PubMed Central

    Li, Nan; Chen, Huan; Williams, Henry N.

    2015-01-01

    Bdellovibrio -and-like organisms (BALOs) are gram-negative, predatory bacteria with wide variations in genome sizes and GC content and ecological habitats. The ATP-binding cassette (ABC) systems have been identified in several prokaryotes, fungi and plants and have a role in transport of materials in and out of cells and in cellular processes. However, knowledge of the ABC systems of BALOs remains obscure. A total of 269 putative ABC proteins were identified in BALOs. The genes encoding these ABC systems occupy nearly 1.3% of the gene content in freshwater Bdellovibrio strains and about 0.7% in their saltwater counterparts. The proteins found belong to 25 ABC system families based on their structural characteristics and functions. Among these, 16 families function as importers, 6 as exporters and 3 are involved in various cellular processes. Eight of these 25 ABC system families were deduced to be the core set of ABC systems conserved in all BALOs. All Bacteriovorax strains have 28 or less ABC systems. On the contrary, the freshwater Bdellovibrio strains have more ABC systems, typically around 51. In the genome of Bdellovibrio exovorus JSS (CP003537.1), 53 putative ABC systems were detected, representing the highest number among all the BALO genomes examined in this study. Unexpected high numbers of ABC systems involved in cellular processes were found in all BALOs. Phylogenetic analysis suggests that the majority of ABC proteins can be assigned into many separate families with high bootstrap supports (>50%). In this study, a general framework of sequence–structure–function connections for the ABC systems in BALOs was revealed providing novel insights for future investigations. PMID:25707746

  2. Rings in the solar system

    SciTech Connect

    Pollack, J.B.; Cuzzi, J.N.

    1981-11-01

    Saturn, Jupiter, and Uranus have rings with different structure and composition. The rings consist of tiny masses in independent orbits. Photographs and data obtained by the Voyager project have aided in the understanding of Saturn's rings. Spokes have been found in B ring and boards, knots, and twist in F ring. Particles on the order of a micrometer in size are believed to occur in F, B, and A rings. The dominant component is water ice. The rings of Uranus are narrow and separated by broad empty regions. The technique used to study them has been stellar occulation. Nothing is known of particle size. The dominant component is believed to be silicates rich in compounds that absorb sunlight. Jupiter's rings consist of 3 main parts: a bright ring, a diffuse disk, and a halo. Use of Pioneer 10 data and other techniques have indicated particle sizes on the order of several micrometers and some at least a centimeter in diameter. The architecture of the ring system results from the interplay of a number of forces. These include gravitational forces due to moons outside the rings and moonlets embedded in them, electromagnetic forces due to the planet's rotating magnetic field, and even the gentle forces exerted by the dilute gaseous medium in which the rings rotate. Each of these forces is discussed. Several alternative explanations of how the rings arose are considered. The primary difference in these hypotheses is the account of the relationship between the ring particles of today and the primordial ring material. (SC)

  3. The Predicted ABC Transporter AbcEDCBA Is Required for Type IV Secretion System Expression and Lysosomal Evasion by Brucella ovis

    PubMed Central

    Silva, Teane M. A.; Mol, Juliana P. S.; Winter, Maria G.; Atluri, Vidya; Xavier, Mariana N.; Pires, Simone F.; Paixão, Tatiane A.; Andrade, Hélida M.; Santos, Renato L.; Tsolis, Renee M.

    2014-01-01

    Brucella ovis is a major cause of reproductive failure in rams and it is one of the few well-described Brucella species that is not zoonotic. Previous work showed that a B. ovis mutant lacking a species-specific ABC transporter (ΔabcBA) was attenuated in mice and was unable to survive in macrophages. The aim of this study was to evaluate the role of this ABC transporter during intracellular survival of B. ovis. In HeLa cells, B. ovis WT was able to survive and replicate at later time point (48 hpi), whereas an ΔabcBA mutant was attenuated at 24 hpi. The reduced survival of the ΔabcBA mutant was associated with a decreased ability to exclude the lysosomal marker LAMP1 from its vacuolar membrane, suggesting a failure to establish a replicative niche. The ΔabcBA mutant showed a reduced abundance of the Type IV secretion system (T4SS) proteins VirB8 and VirB11 in both rich and acid media, when compared to WT B. ovis. However, mRNA levels of virB1, virB8, hutC, and vjbR were similar in both strains. These results support the notion that the ABC transporter encoded by abcEDCBA or its transported substrate acts at a post-transcriptional level to promote the optimal expression of the B. ovis T4SS within infected host cells. PMID:25474545

  4. Reflex ring laser amplifier system

    DOEpatents

    Summers, Mark A.

    1985-01-01

    A laser pulse is injected into an unstable ring resonator-amplifier structure. Inside this resonator the laser pulse is amplified, spatially filtered and magnified. The laser pulse is recirculated in the resonator, being amplified, filtered and magnified on each pass. The magnification is chosen so that the beam passes through the amplifier in concentric non-overlapping regions similar to a single pass MOPA. After a number of passes around the ring resonator the laser pulse is spatially large enough to exit the ring resonator system by passing around an output mirror.

  5. New Main Ring control system

    SciTech Connect

    Seino, K.; Anderson, L.; Ducar, R.; Franck, A.; Gomilar, J.; Hendricks, B.; Smedinghoff, J.

    1990-03-01

    The Fermilab Main Ring control system has been operational for over sixteen years. Aging and obsolescence of the equipment make the maintenance difficult. Since the advent of the Tevatron, considerable upgrades have been made to the controls of all the Fermilab accelerators except the Main Ring. Modernization of the equipment and standardization of the hardware and software have thus become inevitable. The Tevatron CAMAC serial system has been chosen as a basic foundation in order to make the Main Ring control system compatible with the rest of the accelerator complex. New hardware pieces including intelligent CAMAC modules have been designed to satisfy unique requirements. Fiber optic cable and repeaters have been installed in order to accommodate new channel requirements onto the already saturated communication medium system. 8 refs., 2 figs.

  6. A PhoPQ-Regulated ABC Transporter System Exports Tetracycline in Pseudomonas aeruginosa.

    PubMed

    Chen, Lin; Duan, Kangmin

    2016-05-01

    Pseudomonas aeruginosa is an important human pathogen whose infections are difficult to treat due to its high intrinsic resistance to many antibiotics. Here, we show that the disruption of PA4456, encoding the ATP binding component of a putative ATP-binding cassette (ABC) transporter, increased the bacterium's susceptible to tetracycline and other antibiotics or toxic chemicals. Fluorescence spectroscopy and antibiotic accumulation tests showed that the interruption of the ABC transporter caused increased intracellular accumulation of tetracycline, demonstrating a role of the ABC transporter in tetracycline expulsion. Site-directed mutagenesis proved that the conserved residues of E170 in the Walker B motif and H203 in the H-loop, which are important for ATP hydrolysis, were essential for the function of PA4456. Through a genome-wide search, the PhoPQ two-component system was identified as a regulator of the computationally predicted PA4456-4452 operon that encodes the ABC transporter system. A >5-fold increase of the expression of this operon was observed in the phoQ mutant. The results obtained also show that the expression of the phzA1B1C1D1E1 operon and the production of pyocyanin were significantly higher in the ABC transporter mutant, signifying a connection between the ABC transporter and pyocyanin production. These results indicated that the PhoPQ-regulated ABC transporter is associated with intrinsic resistance to antibiotics and other adverse compounds in P. aeruginosa, probably by extruding them out of the cell. PMID:26953208

  7. APS storage ring vacuum system

    SciTech Connect

    Niemann, R.C.; Benaroya, R.; Choi, M.; Dortwegt, R.J.; Goeppner, G.A.; Gonczy, J.; Krieger, C.; Howell, J.; Nielsen, R.W.; Roop, B.; Wehrle, R.B.

    1990-01-01

    The Advanced Photon Source synchrotron radiation facility, under construction at the Argonne National Laboratory, incorporates a large ring for the storage of 7 GeV positrons for the generation of photon beams for the facility's experimental program. The Storage Ring's 1104 m circumference is divided into 40 functional sectors. The sectors include vacuum, beam transport, control, acceleration and insertion device components. The vacuum system, which is designed to operate at a pressure of 1 n Torr, consists of 240 connected sections, the majority of which are fabricated from an aluminum alloy extrusion. The sections are equipped with distributed NeG pumping, photon absorbers with lumped pumping, beam position monitors, vacuum diagnostics and valving. The details of the vacuum system design, selected results of the development program and general construction plans are presented. 11 refs., 6 figs., 3 tabs.

  8. Reflex ring laser amplifier system

    SciTech Connect

    Summers, M.A.

    1983-08-31

    The invention is a method and apparatus for providing a reflex ring laser system for amplifying an input laser pulse. The invention is particularly useful in laser fusion experiments where efficient production of high-energy and high power laser pulses is required. The invention comprises a large aperture laser amplifier in an unstable ring resonator which includes a combination spatial filter and beam expander having a magnification greater than unity. An input pulse is injected into the resonator, e.g., through an aperture in an input mirror. The injected pulse passes through the amplifier and spatial filter/expander components on each pass around the ring. The unstable resonator is designed to permit only a predetermined number of passes before the amplified pulse exits the resonator. On the first pass through the amplifier, the beam fills only a small central region of the gain medium. On each successive pass, the beam has been expanded to fill the next concentric non-overlapping region of the gain medium.

  9. Comments on collision mechanics in ring systems. [planetary rings

    NASA Technical Reports Server (NTRS)

    Hartmann, W. K.

    1982-01-01

    Collisions within planetary ring systems, especially Saturn's, are discussed. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Collisions do not cause catastrophic fragmentation of the particles, although minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt. Models suggest that the fractional number of projectile masses dislodged when solid (or solid-core) projectiles strike solid ice or granular surface layers does not exceed the order of 10 to the minus 7th to minus 9th power. Even at this rate, the half life of ring particles would be less than the age of the solar system in crowded ring regions unless there was very efficient reaccretion. A plausible ring particle model involves solid ice cores with granular surface layers that exchange material by slow erosion and efficient reaccretion; the granular layers protect the cores from rapid erosion.

  10. Wear reduction systems liquid piston ring

    SciTech Connect

    Raymond, R.J.; Chen, T.N.; DiNanno, L.

    1990-09-01

    The overall objective of the program was to demonstrate the technical feasibility of achieving an acceptable wear rate for the cylinder liner, piston, and piston rings in a coal/water-slurry-fueled engine that utilized the concept of a liquid piston ring above the conventional piston rings and to identify technical barriers and required research and development. The study included analytical modeling of the system, a bench study of the fluid motion in the liquid piston ring, and a single-cylinder test rig for wear comparison. A system analysis made on the different variations of the liquid supply system showed the desirability of the once-through version from the standpoint of system simplicity. The dynamics of the liquid ring were modeled to determine the important design parameters that influence the pressure fluctuation in the liquid ring during a complete engine cycle and the integrity of the liquid ring. This analysis indicated the importance of controlling heat transfer to the liquid ring through piston and liner to avoid boiling the liquid. A conceptual piston design for minimizing heat transfer is presented in this report. Results showed that the liquid piston ring effectively reduced the solid particles on the wall by scrubbing, especially in the case where a surfactant was added to the water. The wear rates were reduced by a factor of 2 with the liquid ring. However, leakage of the contaminated liquid ring material past the top ring limited the effectiveness of the liquid ring concept. 8 refs., 33 figs., 1 tab.

  11. As Easy as ABC: Re-engineering the Cost Accounting System.

    ERIC Educational Resources Information Center

    Trussel, John M.; Bitner, Larry N.

    1996-01-01

    To be useful for management decision making, the college or university's cost accounting system must capture and measure improvements. Activity-based costing (ABC), which determines more accurately the full costs of services and products, tracks improvements and should proceed alongside reengineering of institutional accounting. Guidelines are…

  12. Proteoglycans in the central nervous system: plasticity, regeneration and their stimulation with chondroitinase ABC.

    PubMed

    Kwok, Jessica C F; Afshari, Fardad; García-Alías, Guillermo; Fawcett, James W

    2008-01-01

    After injury to the mammalian central nervous system (CNS), neurons are not able to regenerate their axons and recovery is limited by restricted plasticity. Axon regeneration is inhibited by the presence of the various inhibitory molecules, including chondroitin sulfate proteoglycans (CSPGs) which are upregulated around the injury site. Plasticity after the end of critical periods is restricted by extracellular matrix changes, particularly the formation of CSPG-containing perineuronal nets. Enzymatic removal of chondroitin sulfate (CS) chains with chondroitinase ABC promotes axon regeneration and reactivates plasticity. This review details the structures and properties of the different CSPGs in the normal and damaged CNS, the use of the enzyme chondroitinase ABC to promote neural regeneration and plasticity, and discusses mechanisms of action and possible therapeutic uses of this enzyme.

  13. ABC transporters: bacterial exporters.

    PubMed Central

    Fath, M J; Kolter, R

    1993-01-01

    The ABC transporters (also called traffic ATPases) make up a large superfamily of proteins which share a common function and a common ATP-binding domain. ABC transporters are classified into three major groups: bacterial importers (the periplasmic permeases), eukaryotic transporters, and bacterial exporters. We present a comprehensive review of the bacterial ABC exporter group, which currently includes over 40 systems. The bacterial ABC exporter systems are functionally subdivided on the basis of the type of substrate that each translocates. We describe three main groups: protein exporters, peptide exporters, and systems that transport nonprotein substrates. Prototype exporters from each group are described in detail to illustrate our current understanding of this protein family. The prototype systems include the alpha-hemolysin, colicin V, and capsular polysaccharide exporters from Escherichia coli, the protease exporter from Erwinia chrysanthemi, and the glucan exporters from Agrobacterium tumefaciens and Rhizobium meliloti. Phylogenetic analysis of the ATP-binding domains from 29 bacterial ABC exporters indicates that the bacterial ABC exporters can be divided into two primary branches. One branch contains the transport systems where the ATP-binding domain and the membrane-spanning domain are present on the same polypeptide, and the other branch contains the systems where these domains are found on separate polypeptides. Differences in substrate specificity do not correlate with evolutionary relatedness. A complete survey of the known and putative bacterial ABC exporters is included at the end of the review. PMID:8302219

  14. Recent observations of Jupiter's ring system

    NASA Astrophysics Data System (ADS)

    Showalter, M.; Burns, J.; de Pater, I.; Hamilton, D.; Horanyi, M.

    2003-04-01

    Jupiter's faint, dusty ring system has several distinct components: a thin main ring, an inner, vertically extended halo, and an outer, fainter pair of "gossamer" rings. This ring system illustrates the complex dynamics of dust after it is ejected from the local moons (Metis, Adrastea, Amalthea and Thebe) and/or embedded parent bodies, and then evolves orbitally under solar and electromagnetic perturbations. The ring system has been observed by four spacecraft (Voyagers 1 and 2, Galileo and Cassini), as well as from the Earth by ground-based observatories and the Hubble Space Telescope (HST). While each individual data set has very limited coverage and content, a complete description of the system is now emerging. This paper will provide a systematic overview of the ring system, based on the latest available data and dynamical models. In particular, the period December 2002 through February 2003 is providing a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while remaining nearly edge-on to the Earth. We will discuss the initial results of an observing program using HST in the visual and the Keck Telescope in the infrared. As the rings pass through opposition, the parent bodies surge in brightness while the dust grains do not; this should provide a new means to distinguish the two populations, better revealing their numbers and locations. Variations in halo thickness with wavelength will provide new information about the sizes and dynamics of the dust grains scattered by Jupiter's strong, inner magnetic field. We will also seek out structures near the outer edge of Amalthea's gossamer ring, hinted at in previous data, which illustrate the dynamics of these dust grains immediately after their initial ejection into the ring.

  15. APS storage ring vacuum system performance

    SciTech Connect

    Noonan, J.R.; Gagliano, J.; Goeppner, G.A.

    1997-06-01

    The Advanced Photon Source (APS) storage ring was designed to operated with 7-GeV, 100-mA positron beam with lifetimes > 20 hours. The lifetime is limited by residual gas scattering and Touschek scattering at this time. Photon-stimulated desorption and microwave power in the rf cavities are the main gas loads. Comparison of actual system gas loads and design calculations will be given. In addition, several special features of the storage ring vacuum system will be presented.

  16. Lectures on algebraic system theory: Linear systems over rings

    NASA Technical Reports Server (NTRS)

    Kamen, E. W.

    1978-01-01

    The presentation centers on four classes of systems that can be treated as linear systems over a ring. These are: (1) discrete-time systems over a ring of scalars such as the integers; (2) continuous-time systems containing time delays; (3) large-scale discrete-time systems; and (4) time-varying discrete-time systems.

  17. Centaur's ring system formation by close encounters

    NASA Astrophysics Data System (ADS)

    De Santana, Thamiris; Winter, Othon

    2016-10-01

    Rupture of small bodies due to close approach to a massive body is a frequent event in the Solar System. Some of these small bodies can just disintegrate completely or suffer a material loss.In this work we study the gravitational interaction between a giant planet and a small body in close encounters in order to simulate the formation of a planetary ring system around a centaur by the partial rupture of the small body.Considering the current Chariklo's body and a disk of particles around it, we simulated the system under close encounters with one of giant planets.Another motivation for the study is also the centaur Chiron, that is a candidate to have a ring system like Chariklo. The characteristics of the encounters are defined by the impact parameter and the velocity at infinity.The results are presented in terms of conditions that could lead to a rupture that could generate a ring like system.

  18. Control System of the Small Isochronous ring

    SciTech Connect

    Felix Marti; Eduard Pozdeyev

    2004-07-01

    The purpose of this paper is to describe the control system of the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Information about the electronics used and software written to control different injection line, ring and extraction line elements is included. Some of these elements are magnets, electrostatic quadrupoles, electric and magnetic correctors, scanning wires, emittance measurement system, chopper and a fast Faraday cup.

  19. RF SYSTEM FOR THE SNS ACCUMULATOR RING.

    SciTech Connect

    BLASKIEWICZ, M.; BRENNAN, J.M.; BRODOWSKI, J.; DELONG, J.; METH, M.; SMITH, K.; ZALTSMAN, A.

    2001-06-18

    During accumulation the RF beam current in the spallation neutron source ring rises from 0 to 50 amperes. A clean, 250 nanosecond gap is needed for the extraction kicker risetime. Large momentum spread and small peak current are needed to prevent instabilities and stopband related losses. A robust RF system meeting these requirements has been designed.

  20. Chariklo's ring system 1. Structure of the ring system from stellar occultations

    NASA Astrophysics Data System (ADS)

    Berard, Diane; Sicardy, Bruno; Braga-Ribas, Felipe; camargo, julio; Vieira-Martins, Roberto; Assafin, Marcelo; Sickafoose, Amanda A.; Colas, François; Dauvergne, Jean-Luc; Bath, Karl-Ludwig; Maquet, Lucie; Tancredi, Gonzalo; Richichi, Andrea; Puji, Irawati; Ivanov, Valentin; Bradshaw, Jonathan; Broughton, John; Meza, Erick; Ortiz, Jose-Luis; Duffard, Rene; Leiva, Rodrigo

    2016-10-01

    Two dense and narrow rings around Chariklo (the largest centaur object known to date) were discovered by stellar occultation on June 3, 2013 (Braga-Ribas et al., Nature 508, 72, 2014). The main and larger ring is called C1R, while the faintest one is called C2R.Here we report six others occultations by Chariklo's ring system observed on February 16, March 16, April 29, June 28, 2014 and April 26, May 12, 2015. They provide a total of fifteen ring profiles, among which are four resolved profiles of C1R.The latter exhibits a W-shape profile that is essentially opaque at the edges. Its width varies from 4.8 to 7.7 km over the available longitude range. Those caracteristics have been detected in Uranus elliptic rings. The equivalent width We (normal opacity x physical radial width) of C1R is 2 km with typical rms of 1 km, while C2R has We of 0.2 km (rms ~ 0.1 km). None of the rings exhibits variation of We with longitude.Assuming the rings are circular, we can exhibit a pole which is compatible with the two multi-chord ring detections (June 3, 2013 and April 29, 2014): αp=151.4° and δp=41.5°. We will then estimate an upper limit of a possible ring eccentricity based on those two observations.Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ ERC Grant Agreement n 669416 "LUCKY STAR").

  1. Active transporters as enzymes: an energetic framework applied to major facilitator superfamily and ABC importer systems.

    PubMed

    Shilton, Brian H

    2015-04-15

    Active membrane transporters are dynamic molecular machines that catalyse transport across a membrane by coupling solute movement to a source of energy such as ATP or a secondary ion gradient. A central question for many active transporters concerns the mechanism by which transport is coupled to a source of energy. The transport process and associated energetic coupling involve conformational changes in the transporter. For efficient transport, the conformational changes must be tightly regulated and they must link energy use to movement of the substrate across the membrane. The present review discusses active transport using the well-established energetic framework for enzyme-mediated catalysis. In particular, membrane transport systems can be viewed as ensembles consisting of low-energy and high-energy conformations. The transport process involves binding interactions that selectively stabilize the higher energy conformations, and in this way promote conformational changes in the system that are coupled to decreases in free energy and substrate translocation. The major facilitator superfamily of secondary active transporters is used to illustrate these ideas, which are then be expanded to primary active transport mediated by ABC (ATP-binding cassette) import systems, with a focus on the well-studied maltose transporter.

  2. A two-component system regulates the expression of an ABC transporter for xylo-oligosaccharides in Geobacillus stearothermophilus.

    PubMed

    Shulami, Smadar; Zaide, Galia; Zolotnitsky, Gennady; Langut, Yael; Feld, Geoff; Sonenshein, Abraham L; Shoham, Yuval

    2007-02-01

    Geobacillus stearothermophilus T-6 utilizes an extensive and highly regulated hemicellulolytic system. The genes comprising the xylanolytic system are clustered in a 39.7-kb chromosomal segment. This segment contains a 6-kb transcriptional unit (xynDCEFG) coding for a potential two-component system (xynDC) and an ATP-binding cassette (ABC) transport system (xynEFG). The xynD promoter region contains a 16-bp inverted repeat resembling the operator site for the xylose repressor, XylR. XylR was found to bind specifically to this sequence, and binding was efficiently prevented in vitro in the presence of xylose. The ABC transport system was shown to comprise an operon of three genes (xynEFG) that is transcribed from its own promoter. The nonphosphorylated fused response regulator, His6-XynC, bound to a 220-bp fragment corresponding to the xynE operator. DNase I footprinting analysis showed four protected zones that cover the -53 and the +34 regions and revealed direct repeat sequences of a GAAA-like motif. In vitro transcriptional assays and quantitative reverse transcription-PCR demonstrated that xynE transcription is activated 140-fold in the presence of 1.5 microM XynC. The His6-tagged sugar-binding lipoprotein (XynE) of the ABC transporter interacted with different xylosaccharides, as demonstrated by isothermal titration calorimetry. The change in the heat capacity of binding (DeltaCp) for XynE with xylotriose suggests a stacking interaction in the binding site that can be provided by a single Trp residue and a sugar moiety. Taken together, our data show that XynEFG constitutes an ABC transport system for xylo-oligosaccharides and that its transcription is negatively regulated by XylR and activated by the response regulator XynC, which is part of a two-component sensing system. PMID:17142383

  3. A Two-Component System Regulates the Expression of an ABC Transporter for Xylo-Oligosaccharides in Geobacillus stearothermophilus▿

    PubMed Central

    Shulami, Smadar; Zaide, Galia; Zolotnitsky, Gennady; Langut, Yael; Feld, Geoff; Sonenshein, Abraham L.; Shoham, Yuval

    2007-01-01

    Geobacillus stearothermophilus T-6 utilizes an extensive and highly regulated hemicellulolytic system. The genes comprising the xylanolytic system are clustered in a 39.7-kb chromosomal segment. This segment contains a 6-kb transcriptional unit (xynDCEFG) coding for a potential two-component system (xynDC) and an ATP-binding cassette (ABC) transport system (xynEFG). The xynD promoter region contains a 16-bp inverted repeat resembling the operator site for the xylose repressor, XylR. XylR was found to bind specifically to this sequence, and binding was efficiently prevented in vitro in the presence of xylose. The ABC transport system was shown to comprise an operon of three genes (xynEFG) that is transcribed from its own promoter. The nonphosphorylated fused response regulator, His6-XynC, bound to a 220-bp fragment corresponding to the xynE operator. DNase I footprinting analysis showed four protected zones that cover the −53 and the +34 regions and revealed direct repeat sequences of a GAAA-like motif. In vitro transcriptional assays and quantitative reverse transcription-PCR demonstrated that xynE transcription is activated 140-fold in the presence of 1.5 μM XynC. The His6-tagged sugar-binding lipoprotein (XynE) of the ABC transporter interacted with different xylosaccharides, as demonstrated by isothermal titration calorimetry. The change in the heat capacity of binding (ΔCp) for XynE with xylotriose suggests a stacking interaction in the binding site that can be provided by a single Trp residue and a sugar moiety. Taken together, our data show that XynEFG constitutes an ABC transport system for xylo-oligosaccharides and that its transcription is negatively regulated by XylR and activated by the response regulator XynC, which is part of a two-component sensing system. PMID:17142383

  4. The abcEDCBA-Encoded ABC Transporter and the virB Operon-Encoded Type IV Secretion System of Brucella ovis Are Critical for Intracellular Trafficking and Survival in Ovine Monocyte-Derived Macrophages.

    PubMed

    Macedo, Auricelio A; Silva, Ana P C; Mol, Juliana P S; Costa, Luciana F; Garcia, Luize N N; Araújo, Marcio S; Martins Filho, Olindo A; Paixão, Tatiane A; Santos, Renato L

    2015-01-01

    Brucella ovis infection is associated with epididymitis, orchitis and infertility in rams. Most of the information available on B. ovis and host cell interaction has been generated using murine macrophages or epithelial cell lines, but the interaction between B. ovis and primary ovine macrophages has not been studied. The aim of this study was to evaluate the role of the B. ovis abcEDCBA-encoded ABC transporter and the virB operon-encoded Type IV Secretion System (T4SS) during intracellular survival of B. ovis in ovine peripheral blood monocyte-derived macrophages. ΔabcBA and ΔvirB2 mutant strains were unable to survive in the intracellular environment when compared to the WT B. ovis at 48 hours post infection (hpi). In addition, these mutant strains cannot exclude the lysosomal marker LAMP1 from its vacuolar membrane, and their vacuoles do not acquire the endoplasmic reticulum marker calreticulin, which takes place in the WT B. ovis containing vacuole. Higher levels of nitric oxide production were observed in macrophages infected with WT B. ovis at 48 hpi when compared to macrophages infected with the ΔabcBA or ΔvirB2 mutant strains. Conversely, higher levels of reactive oxygen species were detected in macrophages infected with the ΔabcBA or ΔvirB2 mutant strains at 48 hpi when compared to macrophages infected with the WT strain. Our results demonstrate that B. ovis is able to persist and multiply in ovine macrophages, while ΔabcBA and ΔvirB2 mutations prevent intracellular multiplication, favor phagolysosome fusion, and impair maturation of the B. ovis vacuole towards an endoplasmic reticulum-derived compartment. PMID:26366863

  5. The abcEDCBA-Encoded ABC Transporter and the virB Operon-Encoded Type IV Secretion System of Brucella ovis Are Critical for Intracellular Trafficking and Survival in Ovine Monocyte-Derived Macrophages

    PubMed Central

    Macedo, Auricelio A.; Silva, Ana P. C.; Mol, Juliana P. S.; Costa, Luciana F.; Garcia, Luize N. N.; Araújo, Marcio S.; Martins Filho, Olindo A.; Paixão, Tatiane A.; Santos, Renato L.

    2015-01-01

    Brucella ovis infection is associated with epididymitis, orchitis and infertility in rams. Most of the information available on B. ovis and host cell interaction has been generated using murine macrophages or epithelial cell lines, but the interaction between B. ovis and primary ovine macrophages has not been studied. The aim of this study was to evaluate the role of the B. ovis abcEDCBA-encoded ABC transporter and the virB operon-encoded Type IV Secretion System (T4SS) during intracellular survival of B. ovis in ovine peripheral blood monocyte-derived macrophages. ΔabcBA and ΔvirB2 mutant strains were unable to survive in the intracellular environment when compared to the WT B. ovis at 48 hours post infection (hpi). In addition, these mutant strains cannot exclude the lysosomal marker LAMP1 from its vacuolar membrane, and their vacuoles do not acquire the endoplasmic reticulum marker calreticulin, which takes place in the WT B. ovis containing vacuole. Higher levels of nitric oxide production were observed in macrophages infected with WT B. ovis at 48 hpi when compared to macrophages infected with the ΔabcBA or ΔvirB2 mutant strains. Conversely, higher levels of reactive oxygen species were detected in macrophages infected with the ΔabcBA or ΔvirB2 mutant strains at 48 hpi when compared to macrophages infected with the WT strain. Our results demonstrate that B. ovis is able to persist and multiply in ovine macrophages, while ΔabcBA and ΔvirB2 mutations prevent intracellular multiplication, favor phagolysosome fusion, and impair maturation of the B. ovis vacuole towards an endoplasmic reticulum-derived compartment. PMID:26366863

  6. Isolation and characterization of the ATP-binding cassette (ABC) transporter system genes from loofah witches' broom phytoplasma.

    PubMed

    Huang, Chun-Lin; Ho, Kuo-Chieh

    2007-10-01

    A clone containing a 3903 bp EcoRI-restriction fragment was obtained from a lambda(ZAP) genomic library of loofah witches' broom (LfWB) phytoplasma by plaque hybridization using a PCR fragment as a probe. Sequence analysis revealed that this fragment contained three open reading frames (ORFs). The deduced amino acid sequences of ORF 1 and ORF 2 showed a high homology with the ATP-binding proteins of the ABC transporter system genes of prokaryotes and eukaryotes, and encoded proteins with a molecular mass of 36 and 30 kDa, respectively. Based on amino acid sequence similarity, secondary structure, hydrophilicity and a signal peptide sequence at the N-terminus, we predicted that ORF 3 might encode a specific solute-binding prolipoprotein of the ABC transporter system with a molecular mass of 62 kDa. The cleavage site of this prolipoprotein signal peptide was similar to those of gram-positive bacteria. In addition to nutrient uptake, ABC transporter systems of bacteria also play a role in signal transduction, drug-resistance and perhaps virulence. The possible implications of the system to the survival and the pathogenesis of phytoplasma were discussed.

  7. AztD, a Periplasmic Zinc Metallochaperone to an ATP-binding Cassette (ABC) Transporter System in Paracoccus denitrificans.

    PubMed

    Handali, Melody; Roychowdhury, Hridindu; Neupane, Durga P; Yukl, Erik T

    2015-12-11

    Bacterial ATP-binding cassette (ABC) transporters of transition metals are essential for acquisition of necessary elements from the environment. A large number of Gram-negative bacteria, including human pathogens, have a fourth conserved gene of unknown function adjacent to the canonical permease, ATPase, and solute-binding protein (SBP) genes of the AztABC zinc transporter system. To assess the function of this putative accessory factor (AztD) from Paracoccus denitrificans, we have analyzed its transcriptional regulation, metal binding properties, and interaction with the SBP (AztC). Transcription of the aztD gene is significantly up-regulated under conditions of zinc starvation. Recombinantly expressed AztD purifies with slightly substoichiometric zinc from the periplasm of Escherichia coli and is capable of binding up to three zinc ions with high affinity. Size exclusion chromatography and a simple intrinsic fluorescence assay were used to determine that AztD as isolated is able to transfer bound zinc nearly quantitatively to apo-AztC. Transfer occurs through a direct, associative mechanism that prevents loss of metal to the solvent. These results indicate that AztD is a zinc chaperone to AztC and likely functions to maintain zinc homeostasis through interaction with the AztABC system. This work extends our understanding of periplasmic zinc trafficking and the function of chaperones in this process.

  8. MntABC and MntH Contribute to Systemic Staphylococcus aureus Infection by Competing with Calprotectin for Nutrient Manganese

    PubMed Central

    Kehl-Fie, Thomas E.; Zhang, Yaofang; Moore, Jessica L.; Farrand, Allison J.; Hood, M. Indriati; Rathi, Subodh; Chazin, Walter J.; Caprioli, Richard M.

    2013-01-01

    During infection, vertebrates limit access to manganese and zinc, starving invading pathogens, such as Staphylococcus aureus, of these essential metals in a process termed “nutritional immunity.” The manganese and zinc binding protein calprotectin is a key component of the nutrient-withholding response, and mice lacking this protein do not sequester manganese from S. aureus liver abscesses. One potential mechanism utilized by S. aureus to minimize host-imposed manganese and zinc starvation is the expression of the metal transporters MntABC and MntH. We performed transcriptional analyses of both mntA and mntH, which revealed increased expression of both systems in response to calprotectin treatment. MntABC and MntH compete with calprotectin for manganese, which enables S. aureus growth and retention of manganese-dependent superoxide dismutase activity. Loss of MntABC and MntH results in reduced staphylococcal burdens in the livers of wild-type but not calprotectin-deficient mice, suggesting that these systems promote manganese acquisition during infection. During the course of these studies, we observed that metal content and the importance of calprotectin varies between murine organs, and infection leads to profound changes in the anatomical distribution of manganese and zinc. In total, these studies provide insight into the mechanisms utilized by bacteria to evade host-imposed nutrient metal starvation and the critical importance of restricting manganese availability during infection. PMID:23817615

  9. Reliable Fiber Sensor System with Star-Ring-Bus Architecture

    PubMed Central

    Peng, Peng-Chun; Wang, Jun-Bo; Huang, Kuan-Yan

    2010-01-01

    This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems. PMID:22399876

  10. Reliable fiber sensor system with star-ring-bus architecture.

    PubMed

    Peng, Peng-Chun; Wang, Jun-Bo; Huang, Kuan-Yan

    2010-01-01

    This work presents a novel star-ring-bus sensor system and demonstrates its effectiveness. The main trunk of the proposed sensor system is a star topology and the sensing branches comprise a series of bus subnets. Any weakness in the reliability of the sensor system is overcome by adding remote nodes and switches to the ring and bus subnets. To construct the proposed star-ring-bus sensor system, a fiber ring laser scheme is used to improve the signal-to-noise ratio of the sensor system. The proposed system increases the reliability and capacity of fiber sensor systems.

  11. Integrability of particle system around a ring source as the Newtonian limit of a black ring

    NASA Astrophysics Data System (ADS)

    Igata, Takahisa; Ishihara, Hideki; Yoshino, Hirotaka

    2015-04-01

    The geodesic equation in the five-dimensional singly rotating black ring is nonintegrable, unlike the case of the Myers-Perry black hole. In the Newtonian limit of the black ring, its geodesic equation agrees with the equation of motion of a particle in the Newtonian potential due to a homogeneous ring gravitational source. In this paper, we show that the Newtonian equation of motion allows the separation of variables in the spheroidal coordinates, providing a nontrivial constant of motion quadratic in momenta. This shows that the Newtonian limit of a black ring recovers the symmetry of its geodesic system, and the geodesic chaos is caused by relativistic effects.

  12. Modulation of Biotransformation Systems and ABC Transporters by Benznidazole in Rats

    PubMed Central

    Perdomo, Virginia G.; Rigalli, Juan P.; Villanueva, Silvina S. M.; Ruiz, María L.; Luquita, Marcelo G.; Echenique, Claudia G.

    2013-01-01

    The effect of antichagasic benznidazole (BZL; 100 mg/kg body weight/day, 3 consecutive days, intraperitoneally) on biotransformation systems and ABC transporters was evaluated in rats. Expression of cytochrome P-450 (CYP3A), UDP-glucuronosyltransferase (UGT1A), glutathione S-transferases (alpha glutathione S-transferase [GST-α], GST-μ, and GST-π), multidrug-resistance-associated protein 2 (Mrp2), and P glycoprotein (P-gp) in liver, small intestine, and kidney was estimated by Western blotting. Increases in hepatic CYP3A (30%) and GST-μ (40%) and in intestinal GST-α (72% in jejunum and 136% in ileum) were detected. Significant increases in Mrp2 (300%) and P-gp (500%) proteins in liver from BZL-treated rats were observed without changes in kidney. P-gp and Mrp2 were also increased by BZL in jejunum (170% and 120%, respectively). In ileum, only P-gp was increased by BZL (50%). The activities of GST, P-gp, and Mrp2 correlated well with the upregulation of proteins in liver and jejunum. Plasma decay of a test dose of BZL (5 mg/kg body weight) administered intraduodenally was faster (295%) and the area under the concentration-time curve (AUC) was lower (41%) for BZL-pretreated rats than for controls. The biliary excretion of BZL was higher (60%) in the BZL group, and urinary excretion of BZL did not show differences between groups. The amount of absorbed BZL in intestinal sacs was lower (25%) in pretreated rats than in controls. In conclusion, induction of biotransformation enzymes and/or transporters by BZL could increase the clearance and/or decrease the intestinal absorption of coadministered drugs that are substrates of these systems, including BZL itself. PMID:23877690

  13. Learning from each other: ABC transporter regulation by protein phosphorylation in plant and mammalian systems.

    PubMed

    Aryal, Bibek; Laurent, Christophe; Geisler, Markus

    2015-10-01

    The ABC (ATP-binding cassette) transporter family in higher plants is highly expanded compared with those of mammalians. Moreover, some members of the plant ABC subfamily B (ABCB) display very high substrate specificity compared with their mammalian counterparts that are often associated with multi-drug resistance phenomena. In this review, we highlight prominent functions of plant and mammalian ABC transporters and summarize our knowledge on their post-transcriptional regulation with a focus on protein phosphorylation. A deeper comparison of regulatory events of human cystic fibrosis transmembrane conductance regulator (CFTR) and ABCB1 from the model plant Arabidopsis reveals a surprisingly high degree of similarity. Both physically interact with orthologues of the FK506-binding proteins that chaperon both transporters to the plasma membrane in an action that seems to involve heat shock protein (Hsp)90. Further, both transporters are phosphorylated at regulatory domains that connect both nt-binding folds. Taken together, it appears that ABC transporters exhibit an evolutionary conserved but complex regulation by protein phosphorylation, which apparently is, at least in some cases, tightly connected with protein-protein interactions (PPI). PMID:26517911

  14. Cooling system for three hook ring segment

    SciTech Connect

    Campbell, Christian X.; Eng, Darryl; Lee, Ching-Pang; Patat, Harry

    2014-08-26

    A triple hook ring segment including forward, midsection and aft mounting hooks for engagement with respective hangers formed on a ring segment carrier for supporting a ring segment panel, and defining a forward high pressure chamber and an aft low pressure chamber on opposing sides of the midsection mounting hook. An isolation plate is provided on the aft side of the midsection mounting hook to form an isolation chamber between the aft low pressure chamber and the ring segment panel. High pressure air is supplied to the forward chamber and flows to the isolation chamber through crossover passages in the midsection hook. The isolation chamber provides convection cooling air to an aft portion of the ring segment panel and enables a reduction of air pressure in the aft low pressure chamber to reduce leakage flow of cooling air from the ring segment.

  15. Optimal Medical Equipment Maintenance Service Proposal Decision Support System combining Activity Based Costing (ABC) and the Analytic Hierarchy Process (AHP).

    PubMed

    da Rocha, Leticia; Sloane, Elliot; M Bassani, Jose

    2005-01-01

    This study describes a framework to support the choice of the maintenance service (in-house or third party contract) for each category of medical equipment based on: a) the real medical equipment maintenance management system currently used by the biomedical engineering group of the public health system of the Universidade Estadual de Campinas located in Brazil to control the medical equipment maintenance service, b) the Activity Based Costing (ABC) method, and c) the Analytic Hierarchy Process (AHP) method. Results show the cost and performance related to each type of maintenance service. Decision-makers can use these results to evaluate possible strategies for the categories of equipment.

  16. Optimal Medical Equipment Maintenance Service Proposal Decision Support System combining Activity Based Costing (ABC) and the Analytic Hierarchy Process (AHP).

    PubMed

    da Rocha, Leticia; Sloane, Elliot; M Bassani, Jose

    2005-01-01

    This study describes a framework to support the choice of the maintenance service (in-house or third party contract) for each category of medical equipment based on: a) the real medical equipment maintenance management system currently used by the biomedical engineering group of the public health system of the Universidade Estadual de Campinas located in Brazil to control the medical equipment maintenance service, b) the Activity Based Costing (ABC) method, and c) the Analytic Hierarchy Process (AHP) method. Results show the cost and performance related to each type of maintenance service. Decision-makers can use these results to evaluate possible strategies for the categories of equipment. PMID:17281912

  17. Collapsing ring model of the origin of the solar system

    SciTech Connect

    Schlenker, L.D.

    1988-12-01

    This paper discusses the following topics on the origin of the solar systems: derivation of candidate angular momentum transfer equations; dust ring identified; classic accretional problems in planetary formation; formation of the outer planets; outer solar system satellites; rock rings; comets; the asteroids; formation of the inner planets; meteoric formation processes; formation of the inner planetary satellites; the moon facilitated life on earth; origin of the sun; and residual evidence of the collapsing ring configuration.

  18. Correction: Learning from each other: ABC transporter regulation by protein phosphorylation in plant and mammalian systems.

    PubMed

    Aryal, Bibek; Laurent, Christophe; Geisler, Markus

    2016-04-15

    The ABC (ATP-binding cassette) transporter family in higher plants is highly expanded compared with those of mammalians. Moreover, some members of the plant ABCB subfamily display very high substrate specificity compared with their mammalian counterparts that are often associated with multidrug resistance (MDR) phenomena. In this review we highlight prominent functions of plant and mammalian ABC transporters and summarize our knowledge on their post-transcriptional regulation with a focus on protein phosphorylation. A deeper comparison of regulatory events of human cystic fibrosis transmembrane conductance regulator (CFTR) and ABCB1 from the model plantArabidopsisreveals a surprisingly high degree of similarity. Both physically interact with orthologues of the FK506-binding proteins (FKBPs) that chaperon both transporters to the plasma membrane in an action that seems to involve Hsp90. Further both transporters are phosphorylated at regulatory domains that connect both nucleotide-binding folds. Taken together it appears that ABC transporters exhibit an evolutionary conserved but complex regulation by protein phosphorylation, which apparently is, at least in some cases, tightly connected with protein-protein interactions (PPI). PMID:27068986

  19. Keck Observations of Dusty Rings in our Solar System

    NASA Astrophysics Data System (ADS)

    de Pater, Imke

    2007-08-01

    All four giant planets are surrounded by ring systems, which typically consist of a combination of large and small bodies, as well as fine dust. With the 10-m W.M. Keck telescope on Mauna Kea (Hawaii) we have focused on observing the dusty rings of these planets. In this review I will summarize our data sets. I will focus on our most recent results with regard to Jupiter and Uranus, both observed during ring plane crossings. Jupiter's ring system was observed in December 2002 and January 2003 at 2.2 micron, where we used both the facility near-infrared camera NIRC with a pixel size of 0.151" (˜500 km at Jupiter), and the adaptive optics camera NIRC2, with a pixelsize of 0.04" and 0.01". The images were "onion-peeled" to provide radial scans of the rings. We will compare results of the main ring with Galileo data, and comment on similarities and differences with respect to the location of parent material in the ring. The radial structure of the gossamer rings is very different than expected based upon the Burns et al (1999) formation scenarios. The rings are not sheets of material, but narrow rings located just interior to the orbits of Amalthea and Thebe. The Amalthea ring shows a structure analagous to the main ring. Its inner boundary is near the location of synchronous orbit. Radial variations in the Thebe ring suggest "sculpting" by Lorentz resonances. We will present images of Uranus "hot of the press"; we are scheduled to observe in July and August when the rings are edge-on.

  20. Wind turbine ring/shroud drive system

    DOEpatents

    Blakemore, Ralph W.

    2005-10-04

    A wind turbine capable of driving multiple electric generators having a ring or shroud structure for reducing blade root bending moments, hub loads, blade fastener loads and pitch bearing loads. The shroud may further incorporate a ring gear for driving an electric generator. In one embodiment, the electric generator may be cantilevered from the nacelle such that the gear on the generator drive shaft is contacted by the ring gear of the shroud. The shroud also provides protection for the gearing and aids in preventing gear lubricant contamination.

  1. Weak dynamical effects in the Uranian ring system

    NASA Technical Reports Server (NTRS)

    Freedman, A. P.; Tremaine, S.; Elliot, J. L.

    1983-01-01

    Published data on the orbits of the rings and satellites of Uranus are analyzed in terms of their dynamic interaction, in an attempt to explain discrepancies between current kinematic models of the ring system and recent, very accurate occultation observations. Apse precession, short-term perturbations, satellite resonance, and the movement of the planet and rings with respect to the barycenter of the planet-satellite system are investigated. It is found that the five known satellites could cause the observed ring residuals by shifting the barycenter, but not by direct or resonance effects. Hypothetical interring shepherd satellites of limited mass (such as about 10 to the 19th g for a shepherd between rings 4 and 5), possibly affected by known-satellite resonances, could influence the rings directly.

  2. Weak dynamical effects in the Uranian ring system

    NASA Astrophysics Data System (ADS)

    Freedman, A. P.; Tremaine, S.; Elliot, J. L.

    1983-07-01

    Published data on the orbits of the rings and satellites of Uranus are analyzed in terms of their dynamic interaction, in an attempt to explain discrepancies between current kinematic models of the ring system and recent, very accurate occultation observations. Apse precession, short-term perturbations, satellite resonance, and the movement of the planet and rings with respect to the barycenter of the planet-satellite system are investigated. It is found that the five known satellites could cause the observed ring residuals by shifting the barycenter, but not by direct or resonance effects. Hypothetical interring shepherd satellites of limited mass (such as about 10 to the 19th g for a shepherd between rings 4 and 5), possibly affected by known-satellite resonances, could influence the rings directly.

  3. Recent Hubble Observations of Jupiter's Ring System

    NASA Astrophysics Data System (ADS)

    Showalter, M. R.; Burns, J. A.; de Pater, I.; Hamilton, D. P.; Horanyi, M.

    2003-05-01

    The period December 2002 through February 2003 provided a rare opportunity to watch Jupiter sweep through its full range of Earth-based phase angles while the rings remained nearly edge-on to Earth. We used this period for a series of Jovian ring observations using the High Resolution Channel (HRC) of Hubble's new Advanced Camera for Surveys (ACS). Phase angles span 0.17o--10o. Our images showed the main ring, Adrastea and Metis with very high signal-to-noise ratios (SNR). Amalthea's gossamer ring was detected (and vertically resolved) in a small set of specially targeted images. Somewhat surprisingly, we have not yet been able to detect the halo in any of our images, perhaps because it is obscured by the scattered light from Jupiter's disk, positioned just 4'' outside the HRC's field of view. Preliminary results from this data set are as follows. (1) The ring is substantially less red than the moons, suggesting that fine dust represents a significant fraction of its backscattering intensity. (2) Neither the rings nor the embedded moons Metis and Adrastea have significant opposition surges. We were hoping to use the surge, which is characteristic of most macroscopic bodies but not dust, as an indicator of where any embedded ring parent bodies might reside. (3) Because our data are so sensitive to Metis (radius ˜ 20 km) and Adrastea ( ˜ 8 km), we believe that bodies as small as 3--4 km in radius should have been detected in the data. In an initial search, no additional bodies have been detected. (4) The Amalthea ring shows an enhancement in brightness in its outermost 15,000 km. This is consistent with what was seen in Galileo images at very high phase angles. Support for this work was provided by NASA through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy under NASA contract NAS5-26555.

  4. Ring-laser gyroscope system using dispersive element(s)

    NASA Technical Reports Server (NTRS)

    Smith, David D. (Inventor)

    2010-01-01

    A ring-laser gyroscope system includes a ring-laser gyroscope (RLG) and at least one dispersive element optically coupled to the RLG's ring-shaped optical path. Each dispersive element has a resonant frequency that is approximately equal to the RLG's lasing frequency. A group index of refraction defined collectively by the dispersive element(s) has (i) a real portion that is greater than zero and less than one, and (ii) an imaginary portion that is less than zero.

  5. Superfluid qubit systems with ring shaped optical lattices.

    PubMed

    Amico, Luigi; Aghamalyan, Davit; Auksztol, Filip; Crepaz, Herbert; Dumke, Rainer; Kwek, Leong Chuan

    2014-01-01

    We study an experimentally feasible qubit system employing neutral atomic currents. Our system is based on bosonic cold atoms trapped in ring-shaped optical lattice potentials. The lattice makes the system strictly one dimensional and it provides the infrastructure to realize a tunable ring-ring interaction. Our implementation combines the low decoherence rates of neutral cold atoms systems, overcoming single site addressing, with the robustness of topologically protected solid state Josephson flux qubits. Characteristic fluctuations in the magnetic fields affecting Josephson junction based flux qubits are expected to be minimized employing neutral atoms as flux carriers. By breaking the Galilean invariance we demonstrate how atomic currents through the lattice provide an implementation of a qubit. This is realized either by artificially creating a phase slip in a single ring, or by tunnel coupling of two homogeneous ring lattices. The single qubit infrastructure is experimentally investigated with tailored optical potentials. Indeed, we have experimentally realized scaled ring-lattice potentials that could host, in principle, n ~ 10 of such ring-qubits, arranged in a stack configuration, along the laser beam propagation axis. An experimentally viable scheme of the two-ring-qubit is discussed, as well. Based on our analysis, we provide protocols to initialize, address, and read-out the qubit.

  6. Inactivation of MuxABC-OpmB transporter system in Pseudomonas aeruginosa leads to increased ampicillin and carbenicillin resistance and decreased virulence.

    PubMed

    Yang, Liang; Chen, Lin; Shen, Lixin; Surette, Michael; Duan, Kangmin

    2011-02-01

    Resistance-Nodulation-Cell Division (RND) pumps play important roles in bacterial resistance to antibiotics. Pseudomonas aeruginosa is an important human pathogen which exhibits high level resistance to antibiotics. There are total of 12 RND pumps present in the P. aeruginosa PAOl genome. The recently characterized MuxABC-OpmB system has been shown to play a role in resistance to novobiocin, aztreonam, macrolides, and tetracycline in a multiple knockout mutation. In this study, we examined the expression levels of all the 12 RND pump gene clusters and tested the involvement of MuxABC-OpmB in pathogenicity. The results indicated that in addition to the four known constitutively expressed RND pumps, mexAB-oprM, mexGHI-opmD, mexVW, and mexXY, relatively high levels of expression were observed with mexJK and muxABC-opmB in the conditions tested. Inactivation of muxA in the muxABC-opmB operon resulted in elevated resistance to ampicillin and carbenicillin. The mutant also showed attenuated virulence in both Brassica rapa pekinensis and Drosophila melanogaster infection models. The decreased virulence at least in part was due to decreased twitching motility in the mutant. These results indicate that the RND pump MuxABC-OpmB is associated with ampicillin and carbenicillin susceptibility and also involved in pathogenesis in P. aeruginosa.

  7. The Yersinia pestis Siderophore, Yersiniabactin, and the ZnuABC system both contribute to Zinc acquisition and the development of lethal septicemic plague in mice

    PubMed Central

    Bobrov, Alexander G.; Kirillina, Olga; Fetherston, Jacqueline D.; Miller, M. Clarke; Burlison, Joseph A.; Perry, Robert D.

    2014-01-01

    Summary Bacterial pathogens must overcome host sequestration of zinc (Zn2+), an essential micronutrient, during the infectious disease process. While the mechanisms to acquire chelated Zn2+ by bacteria are largely undefined, many pathogens rely upon the ZnuABC family of ABC transporters. Here we show that in Yersinia pestis, irp2, a gene encoding the synthetase (HMWP2) for the siderophore yersiniabactin (Ybt) is required for growth under Zn2+-deficient conditions in a strain lacking ZnuABC. Moreover, growth stimulation with exogenous, purified apo-Ybt provides evidence that Ybt may serve as a zincophore for Zn2+ acquisition. Studies with the Zn2+-dependent transcriptional reporter znuA∷lacZ indicate that the ability to synthesize Ybt affects the levels of intracellular Zn2+. However, the outer membrane receptor Psn and TonB as well as the inner membrane (IM) ABC transporter YbtPQ, that are required for Fe3+ acquisition by Ybt, are not needed for Ybt-dependent Zn2+ uptake. In contrast, the predicted IM protein YbtX, a member of the Major Facilitator Superfamily, was essential for Ybt-dependent Zn2+ uptake. Finally, we show that the ZnuABC system and the Ybt synthetase HMWP2, presumably by Ybt synthesis, both contribute to the development of a lethal infection in a septicemic plague mouse model. PMID:24979062

  8. Two plant bacteria, S. meliloti and Ca. Liberibacter asiaticus, share functional znuABC homologues that encode for a high affinity Zinc uptake system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Znu system, encoded for by znuABC, can be found in multiple genera of bacteria and has been shown to be responsible for the import of zinc under low zinc conditions. Although this high-affinity uptake system is known to be important for both growth and/or pathogenesis in bacteria, it has not bee...

  9. Monitoring ABC-assisted deep inspiration breath hold for left-sided breast radiotherapy with an optical tracking system

    SciTech Connect

    Mittauer, Kathryn E.; Deraniyagala, Rohan; Li, Jonathan G.; Lu, Bo; Liu, Chihray; Samant, Sanjiv S.; Lightsey, Judith L.; Yan, Guanghua

    2015-01-15

    Purpose: Recent knowledge on the effects of cardiac toxicity warrants greater precision for left-sided breast radiotherapy. Different breath-hold (BH) maneuvers (abdominal vs thoracic breathing) can lead to chest wall positional variations, even though the patient’s tidal volume remains consistent. This study aims to investigate the feasibility of using optical tracking for real-time quality control of active breathing coordinator (ABC)-assisted deep inspiration BH (DIBH). Methods: An in-house optical tracking system (OTS) was used to monitor ABC-assisted DIBH. The stability and localization accuracy of the OTS were assessed with a ball-bearing phantom. Seven patients with left-sided breast cancer were included. A free-breathing (FB) computed tomography (CT) scan and an ABC-assisted BH CT scan were acquired for each patient. The OTS tracked an infrared (IR) marker affixed over the patient’s xiphoid process to measure the positional variation of each individual BH. Using the BH within which the CT scan was performed as the reference, the authors quantified intra- and interfraction BH variations for each patient. To estimate the dosimetric impact of BH variations, the authors studied the positional correlation between the marker and the left breast using the FB CT and BH CT scans. The positional variations of 860 BHs as measured by the OTS were retrospectively incorporated into the original treatment plans to evaluate their dosimetric impact on breast and cardiac organs [heart and left anterior descending (LAD) artery]. Results: The stability and localization accuracy of the OTS was within 0.2 mm along each direction. The mean intrafraction variation among treatment BHs was less than 2.8 mm in all directions. Up to 12.6 mm anteroposterior undershoot, where the patient’s chest wall displacement of a BH is less than that of a reference BH, was observed with averages of 4.4, 3.6, and 0.1 mm in the anteroposterior, craniocaudal, and mediolateral directions

  10. ABC Technology Development Program

    SciTech Connect

    1994-10-14

    The Accelerator-Based Conversion (ABC) facility will be designed to accomplish the following mission: `Provide a weapon`s grade plutonium disposition capability in a safe, economical, and environmentally sound manner on a prudent schedule for [50] tons of weapon`s grade plutonium to be disposed on in [20] years.` This mission is supported by four major objectives: provide a reliable plutonium disposition capability within the next [15] years; provide a level of safety and of safety assurance that meets or exceeds that afforded to the public by modern commercial nuclear power plants; meet or exceed all applicable federal, state, and local regulations or standards for environmental compliance; manage the program in a cost effective manner. The ABC Technology Development Program defines the technology development activities that are required to accomplish this mission. The technology development tasks are related to the following topics: blanket system; vessel systems; reactivity control systems; heat transport system components; energy conversion systems; shutdown heat transport systems components; auxiliary systems; technology demonstrations - large scale experiments.

  11. The ABC transporters in Candidatus Liberibacter asiaticus

    PubMed Central

    Li, Wenlin; Cong, Qian; Pei, Jimin; Kinch, Lisa N; Grishin, Nick V

    2012-01-01

    Candidatus Liberibacter asiaticus (Ca. L. asiaticus) is a Gram-negative bacterium and the pathogen of Citrus Greening disease (Huanglongbing, HLB). As a parasitic bacterium, Ca. L. asiaticus harbors ABC transporters that play important roles in exchanging chemical compounds between Ca. L. asiaticus and its host. Here, we analyzed all the ABC transporter-related proteins in Ca. L. asiaticus. We identified 14 ABC transporter systems and predicted their structures and substrate specificities. In-depth sequence and structure analysis including multiple sequence alignment, phylogenetic tree reconstruction, and structure comparison further support their function predictions. Our study shows that this bacterium could use these ABC transporters to import metabolites (amino acids and phosphates) and enzyme cofactors (choline, thiamine, iron, manganese, and zinc), resist to organic solvent, heavy metal, and lipid-like drugs, maintain the composition of the outer membrane (OM), and secrete virulence factors. Although the features of most ABC systems could be deduced from the abundant experimental data on their orthologs, we reported several novel observations within ABC system proteins. Moreover, we identified seven nontransport ABC systems that are likely involved in virulence gene expression regulation, transposon excision regulation, and DNA repair. Our analysis reveals several candidates for further studies to understand and control the disease, including the type I virulence factor secretion system and its substrate that are likely related to Ca. L. asiaticus pathogenicity and the ABC transporter systems responsible for bacterial OM biosynthesis that are good drug targets. PMID:22807026

  12. Numerical experiments in ringing of offshore systems under viscous loads

    SciTech Connect

    Gurley, K.R.; Kareem, A.

    1996-12-31

    A phenomenon which has recently received much attention in offshore engineering is the ringing response of structures. This high frequency transient type response has been observed in nature, particularly in tension leg platforms (TLPs). Given the implications of this behavior on the fatigue life of tendons, it is important that it be considered for response analysis. Significant progress has been made in recent years in identifying the nonlinear mechanisms that induce ringing in complex offshore structural systems. This introductory study-uses a simple model to numerically demonstrates several of the more salient features that are commonly cited in current literature, and shows that viscous loads may result in inducing ringing type response of members under certain conditions. Ringing response in pitch due to viscous loading is simulated on a column piercing the surface, and the significant contributing force mechanisms are identified. System characteristics are altered to ameliorate the performance of these systems.

  13. A ring system detected around the Centaur (10199) Chariklo.

    PubMed

    Braga-Ribas, F; Sicardy, B; Ortiz, J L; Snodgrass, C; Roques, F; Vieira-Martins, R; Camargo, J I B; Assafin, M; Duffard, R; Jehin, E; Pollock, J; Leiva, R; Emilio, M; Machado, D I; Colazo, C; Lellouch, E; Skottfelt, J; Gillon, M; Ligier, N; Maquet, L; Benedetti-Rossi, G; Ramos Gomes, A; Kervella, P; Monteiro, H; Sfair, R; El Moutamid, M; Tancredi, G; Spagnotto, J; Maury, A; Morales, N; Gil-Hutton, R; Roland, S; Ceretta, A; Gu, S-h; Wang, X-b; Harpsøe, K; Rabus, M; Manfroid, J; Opitom, C; Vanzi, L; Mehret, L; Lorenzini, L; Schneiter, E M; Melia, R; Lecacheux, J; Colas, F; Vachier, F; Widemann, T; Almenares, L; Sandness, R G; Char, F; Perez, V; Lemos, P; Martinez, N; Jørgensen, U G; Dominik, M; Roig, F; Reichart, D E; LaCluyze, A P; Haislip, J B; Ivarsen, K M; Moore, J P; Frank, N R; Lambas, D G

    2014-04-01

    Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ±  9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites.

  14. A ring system detected around the Centaur (10199) Chariklo.

    PubMed

    Braga-Ribas, F; Sicardy, B; Ortiz, J L; Snodgrass, C; Roques, F; Vieira-Martins, R; Camargo, J I B; Assafin, M; Duffard, R; Jehin, E; Pollock, J; Leiva, R; Emilio, M; Machado, D I; Colazo, C; Lellouch, E; Skottfelt, J; Gillon, M; Ligier, N; Maquet, L; Benedetti-Rossi, G; Ramos Gomes, A; Kervella, P; Monteiro, H; Sfair, R; El Moutamid, M; Tancredi, G; Spagnotto, J; Maury, A; Morales, N; Gil-Hutton, R; Roland, S; Ceretta, A; Gu, S-h; Wang, X-b; Harpsøe, K; Rabus, M; Manfroid, J; Opitom, C; Vanzi, L; Mehret, L; Lorenzini, L; Schneiter, E M; Melia, R; Lecacheux, J; Colas, F; Vachier, F; Widemann, T; Almenares, L; Sandness, R G; Char, F; Perez, V; Lemos, P; Martinez, N; Jørgensen, U G; Dominik, M; Roig, F; Reichart, D E; LaCluyze, A P; Haislip, J B; Ivarsen, K M; Moore, J P; Frank, N R; Lambas, D G

    2014-04-01

    Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ±  9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites. PMID:24670644

  15. Progress Report on the g-2 Storage Ring Magnet System

    SciTech Connect

    Bunce, G.A.; Cullen, J.; Danby, G.; Green, M.A.; Jackson, J.; Jia, L.; Krienen, F.; Meier, R.; Meng, W.; Morse, W.; Pai, C.; Polk, I.; Prodell, A.; Shutt, R.; Snydstrup, L.; Yamamoto, A.

    1995-06-01

    The 3.1 GeV muon storage ring for the g-2 experiment at Brookhaven National Laboratory has three large solenoid magnets that form a continuous 1.451 tesla storage ring dipole with an average beam bend radius of 7.1 meters. In addition to the three storage ring solenoids, there is an inflector dipole with nested dipole coils that create very little stray magnetic field. A superconducting shield on the inflector gets rid of most of the remaining stray flux. This paper reports on the progress made on the storage ring solenoid magnet system and the inflector as of June 1995. The results of cryogenic system tests are briefly reported.

  16. Navy ABCs.

    ERIC Educational Resources Information Center

    Department of the Navy, Washington, DC.

    The U.S. Navy and other services use the same 26-letter alphabet that people use every day, but they substitute a word for each letter. You might pronounce the letter "a" when spelling the word a-n-t. A sailor uses words in place of each letter, making a-n-t into "alpha-november-tango." This system prevents mix-ups between similar sounding letters…

  17. The control system of the photon factory storage ring

    NASA Astrophysics Data System (ADS)

    Pak, Cheol On

    1989-05-01

    The Photon Factory 2.5 GeV electron storage ring at KEK, a dedicated machine for synchrotron radiation, stored its first beam on March, 1982. The first control system of the storage ring comprised seven distributed minicomputers connected through a star-type network. However, from 1985 they have been gradually replaced in order to meet increasing system requirements. At present, the control system uses four "supermini" computers as device controllers and a general-purpose computer as a library computer. These computers are connected to each other through a token ring-type network. Each control computer independently performs several processes. However, console functions as man-machine interfaces of all processes can be treated in a unified way using the network. A prototype database for operation logging has been completed and tested.

  18. SIMULATION STUDY AND INITIAL TEST OF THESNS RING RF SYSTEM

    SciTech Connect

    Zhang, Yan; Ma, Hengjie; Holmes, Jeffrey A; Champion, Mark; Chu, Paul; Cousineau, Sarah M; Hardek, Thomas W; Plum, Michael A; Danilov, Viatcheslav; Piller, Chip

    2008-01-01

    The rfsimulator code was developed for the study of the Spallation Neutron Source (SNS) dual-harmonic ring RF control. It uses time-domain solvers to compute beam-cavity interactions and FFT methods to simulate the time responses of the linear RF system. The important elements of the system considered in the model include beam loading, dynamic cavity detuning, circuit bandwidth, loop delay, proportional-integral controller for feedback and adaptive feed forward, stochastic noise, width-in-turn loop parameter change, beam current fluctuation, and bunch leakage. As the beam power increases, beam loss in the ring goes up and thus precise control of the bunching RF phase and amplitude is required to limit beam loss. The code will help in the development of a functional RF control and in achieving the goal of minimizing beam loss in the accumulator ring.

  19. Clump detections and limits on moons in Jupiter's ring system.

    PubMed

    Showalter, Mark R; Cheng, Andrew F; Weaver, Harold A; Stern, S Alan; Spencer, John R; Throop, Henry B; Birath, Emma M; Rose, Debi; Moore, Jeffrey M

    2007-10-12

    The dusty jovian ring system must be replenished continuously from embedded source bodies. The New Horizons spacecraft has performed a comprehensive search for kilometer-sized moons within the system, which might have revealed the larger members of this population. No new moons were found, however, indicating a sharp cutoff in the population of jovian bodies smaller than 8-kilometer-radius Adrastea. However, the search revealed two families of clumps in the main ring: one close pair and one cluster of three to five. All orbit within a brighter ringlet just interior to Adrastea. Their properties are very different from those of the few other clumpy rings known; the origin and nonrandom distribution of these features remain unexplained, but resonant confinement by Metis may play a role. PMID:17932287

  20. Position Ring System using Anger Type Detectors

    SciTech Connect

    Joel S. Karp, principal investigator

    2004-12-14

    The overall objective of our project was to develop PET scanners and imaging techniques that achieve high performance and excellent image quality. Our approach was based upon 3-D imaging (no septa) with position-sensitive Anger-logic detectors, whereby the encoding ratio of resolution elements to number of photo-multiplier tube channels is very high. This design led to a series of PET systems that emphasized cost-effectiveness and practicality in a clinical environment.

  1. Documentation for the token ring network simulation system

    NASA Technical Reports Server (NTRS)

    Peden, Jeffery H.; Weaver, Alfred C.

    1990-01-01

    A manual is presented which describes the language features of the Token Ring Network Simulation System. The simulation system is a powerful simulation tool for token ring networks which allows the specification of various Medium Access Control (MAC) layer protocols as well as the specification of various features of upper layer ISO protocols. In addition to these features, it also allows the user to specify message and station classes virtually to any degree of detail desired. The choice of a language instead of an interactive system to specify network parameters was dictated by both flexibility and time considerations. The language was developed specifically for the simulation system, and is very simple. It is also user friendly in that language elements which do not apply to the case at hand are ignored rather than treated as errors.

  2. BPM SYSTEM FOR THE SNS RING AND TRANSFER LINES.

    SciTech Connect

    DAWSON,W.C.; CAMERON,P.; CERNIGLIA,P.; CUPOLO,J.; DEGEN,C.; DELLAPENNA,A.; HUHN,A.; KESSELMAN,M.; MEAD,J.; SIKORA,R.

    2002-05-06

    The Spallation Neutron Source Ring accumulates about 1060 pulses of 38mA peak current IGeV H-minus particles from the Linac thru the HEBT line, then delivers this accumulated beam in a single pulse to the mercury target via the RTBT line. Bunching frequency of beam in the HEBT line is 402.5MHz, and about 1MHz in the Ring and RTBT. Position monitor electrodes in HEBT are of the shorted stripline type, with apertures of 12cm except in the dispersive bend, where the aperture is 21cm. Ring and RTBT electrodes are open striplines, with apertures of 21, 26, 30, and 36cm. All pickups are dual plane. The electronics will be PC-based with the Analog/Digital Front End passing data and receiving control and timing thru a custom PC1 interface developed by LANL[l]. LabVIEW will be used to direct the acquisition, process the data, and transfer results via Ethernet to the EPICS control system. To handle the dynamic range required with well over 60dB variation in signal size, the Ring and RTBT electronics will employ a fast gain switching technique that will take advantage of the 300ns tail-to-head gap to provide position measurement during the entire accumulation cycle. Beam-based alignment will be utilized as part of the system calibration.

  3. The ABC's required for establishing a practical computerized plant engineering management data base system

    NASA Technical Reports Server (NTRS)

    Maiocco, F. R.; Hume, J. P.

    1976-01-01

    A system's approach is outlined in the paper to assist facility and Plant Engineers improve their organization's data management system. The six basic steps identified may appear somewhat simple; however, adequate planning, proper resources, and the involvement of management will determine the success of a computerized facility management data base. Helpful suggestions are noted throughout the paper to insure the development of a practical computerized data management system.

  4. Thermodynamics of ABC transporters.

    PubMed

    Zhang, Xuejun C; Han, Lei; Zhao, Yan

    2016-01-01

    ABC transporters form the largest of all transporter families, and their structural study has made tremendous progress over recent years. However, despite such advances, the precise mechanisms that determine the energy-coupling between ATP hydrolysis and the conformational changes following substrate binding remain to be elucidated. Here, we present our thermodynamic analysis for both ABC importers and exporters, and introduce the two new concepts of differential-binding energy and elastic conformational energy into the discussion. We hope that the structural analysis of ABC transporters will henceforth take thermodynamic aspects of transport mechanisms into account as well.

  5. Dust in the Jovian System: Streams, Clouds and Rings

    NASA Astrophysics Data System (ADS)

    Krueger, H.; Gruen, E.

    2003-04-01

    Spacecraft investigations during the last ten years have vastly improved our knowledge about dust in the Jovian system. All Galilean satellites, and probably all smaller satellites as well, are sources of dust in the Jovian system. In-situ measurements with the dust detectors on board the Ulysses and Galileo spacecraft have for the first time demonstrated the electromagnetic interaction of charged dust grains with the interplanetary magnetic field and with a planetary magnetosphere. Jupiter's magnetosphere acts as a giant mass-velocity spectrometer for charged 10-nanometer dust grains. These grains are released from Jupiter's moon Io with a typical rate of ˜ 1 kg s-1. The seven-year long record of Galileo in-situ dust measurements revealed significant variations of the fluxes of the dust stream particles with Jovian local time which are caused by the dawn-dusk asymmetry of the Io plasma torus. The streams probe the plasma conditions in the torus, and they can be used as a potential monitor of Io's volcanic plume activity. The joint Galileo-Cassini dust measurements at Jupiter imply stream particle speeds up to 400 km s-1. All Galilean satellites are surrounded by tenuous impact-generated clouds of mostly sub-micrometer ejecta grains. Jovian rings not only exist in the well-known region of the main and gossamer rings but also much farther out. Very tenuous rings composed of mostly micron-sized grains have been detected in-situ in the region between the Galilean moons and further beyond out to ˜ 250 R_J from the planet. The dust densities there are much too low to allow detection with imaging techniques. The measurements have demonstrated that impact-ejecta derived from hypervelocity impacts onto satellites are the major constituent of dusty planetary rings. On 5 November 2002 Galileo traversed Jupiter's gossamer rings for the first time and had a close flyby at Amalthea. Several hundred dust impacts have been detected during this passage with the dust detector on

  6. READOUT SYSTEM FOR ARRAYS OF FRISCH-RING CDZNTE DETECTORS.

    SciTech Connect

    CUI, Y.; BOLOTNIKOV, A.E.; CAMARDA, G.S.; DE GERONIMO, G.; O'CONNOR, P.; JAMES, R.B.; KARGAR, A.; HARRISON, M.J.; MCGREGOR, D.S.

    2006-10-29

    Frisch-ring CdZnTe detectors have demonstrated good energy resolution for identifying isotopes, <1% FWHM at 662 keV, and good efficiency for detecting gamma rays. We will fabricate and test at Brookhaven National Laboratory an integrated module of a 64-element array of 6 x 6 x 12 mm{sup 3} Frisch-ring detectors, coupled with a readout electronics system. It supports 64 readout channels, and includes front-end electronics, signal processing circuit, USB interface and high-voltage power supply. The data-acquisition software is used to process the data stream, which includes amplitude and timing information for each detected event. This paper describes the design and assembly of the detector modules, readout electronics, and a conceptual prototype system. Some test results are also reported.

  7. Uranus. [Scientific study of planetary structure, ring systems, and magnetosphere

    SciTech Connect

    Bergstralh, J.T.

    1987-03-01

    Observations and theoretical investigations of the Uranus (U) system from the period 1983-1986 are reviewed, with an emphasis on the Voyager 2 encounter with U on January 26, 1986. Topics addressed include the bulk U composition, structure, and heat flux; the U atmospheric composition, structure, and circulation; the U rings; the major and minor U satellites; the U magnetosphere; and the Lyman-alpha 'electroglow' observed on the sunlit hemisphere of U. 191 references.

  8. Quantum interference in an electron-hole graphene ring system

    SciTech Connect

    Smirnov, D.; Schmidt, H.; Haug, R. J.

    2013-12-04

    Quantum interference is observed in a graphene ring system via the Aharonov Bohm effect. As graphene is a gapless semiconductor, this geometry allows to study the unique situation of quantum interference between electrons and holes in addition to the unipolar quantum interference. The period and amplitude of the observed Aharonov-Bohm oscillations are independent of the sign of the applied gate voltage showing the equivalence between unipolar and dipolar interference.

  9. Evolution of ring-field systems in microlithography

    NASA Astrophysics Data System (ADS)

    Williamson, David M.

    1998-09-01

    Offner's ring-field all-reflecting triplet was the first successful projection system used in microlithography. It evolved over several generations, increasing NA and field size, reducing the feature sizes printed from three down to one micron. Because of its relative simplicity, large field size and broad spectral bandwidth it became the dominant optical design used in microlithography until the early 1980's, when the demise of optical lithography was predicted. Rumours of the death of optics turned out to be exaggerated; what happened instead was a metamorphosis to more complex optical designs. A reduction ring-field system was developed, but the inevitable loss of concentricity led to a dramatic increase in complexity. Higher NA reduction projection optics have therefore been full-field, either all-refracting or catadioptric using a beamsplitter and a single mirror. At the present time, the terminal illness of optical lithography is once again being prognosed, but now at 0.1 micro feature sizes early in the next millenium. If optics has a future beyond that, it lies at wavelengths below the practical transmission cut-off of all refracting materials. Scanning all-reflecting ring-field systems are therefore poised for a resurgence, based on their well-established advantage of rotational symmetry and consequent small aberration variations over a small, annular field. This paper explores some such designs that potentially could take optical lithography down to the region of 0.025 micron features.

  10. Phase transition in the ABC model.

    PubMed

    Clincy, M; Derrida, B; Evans, M R

    2003-06-01

    Recent studies have shown that one-dimensional driven systems can exhibit phase separation even if the dynamics is governed by local rules. The ABC model, which comprises three particle species that diffuse asymmetrically around a ring, shows anomalous coarsening into a phase separated steady state. In the limiting case in which the dynamics is symmetric and the parameter q describing the asymmetry tends to one, no phase separation occurs and the steady state of the system is disordered. In the present work, we consider the weak asymmetry regime q=exp(-beta/N), where N is the system size, and study how the disordered state is approached. In the case of equal densities, we find that the system exhibits a second-order phase transition at some nonzero beta(c). The value of beta(c)=2pi square root 3 and the optimal profiles can be obtained by writing the exact large deviation functional. For nonequal densities, we write down mean-field equations and analyze some of their predictions. PMID:16241312

  11. The incretin system ABCs in obesity and diabetes - novel therapeutic strategies for weight loss and beyond.

    PubMed

    João, A L; Reis, F; Fernandes, R

    2016-07-01

    Incretins are gastrointestinal-derived hormones released in response to a meal playing a key role in the regulation of postprandial secretion of insulin (incretin effect) and glucagon by the pancreas. Both incretins, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 (GLP-1), have several other actions by peripheral and central mechanisms. GLP-1 regulates body weight by inhibiting appetite and delaying gastric, emptying actions that are dependent on central nervous system GLP-1 receptor activation. Several other hormones and gut peptides, including leptin and ghrelin, interact with GLP-1 to modulate appetite. GLP-1 is rapidly degraded by the multifunctional enzyme dipeptidyl peptidase-4 (DPP-4). DPP-4 is involved in adipose tissue inflammation, which is associated with insulin resistance and diabetes progression, being a common pathophysiological mechanism in obesity-related complications. Furthermore, the incretin system appears to provide the basis for understanding the high weight loss efficacy of bariatric surgery, a widely used treatment for obesity, often in association with diabetes. The present review brings together new insights into obesity pathogenesis, integrating GLP-1 and DPP-4 in the complex interplay between obesity and inflammation, namely, in diabetic patients. This in turn will provide the basis for novel incretin-based therapeutic strategies for obesity and diabetes with promising benefits in addition to weight loss. © 2016 World Obesity.

  12. The incretin system ABCs in obesity and diabetes - novel therapeutic strategies for weight loss and beyond.

    PubMed

    João, A L; Reis, F; Fernandes, R

    2016-07-01

    Incretins are gastrointestinal-derived hormones released in response to a meal playing a key role in the regulation of postprandial secretion of insulin (incretin effect) and glucagon by the pancreas. Both incretins, glucose-dependent insulinotropic polypeptide and glucagon-like peptide-1 (GLP-1), have several other actions by peripheral and central mechanisms. GLP-1 regulates body weight by inhibiting appetite and delaying gastric, emptying actions that are dependent on central nervous system GLP-1 receptor activation. Several other hormones and gut peptides, including leptin and ghrelin, interact with GLP-1 to modulate appetite. GLP-1 is rapidly degraded by the multifunctional enzyme dipeptidyl peptidase-4 (DPP-4). DPP-4 is involved in adipose tissue inflammation, which is associated with insulin resistance and diabetes progression, being a common pathophysiological mechanism in obesity-related complications. Furthermore, the incretin system appears to provide the basis for understanding the high weight loss efficacy of bariatric surgery, a widely used treatment for obesity, often in association with diabetes. The present review brings together new insights into obesity pathogenesis, integrating GLP-1 and DPP-4 in the complex interplay between obesity and inflammation, namely, in diabetic patients. This in turn will provide the basis for novel incretin-based therapeutic strategies for obesity and diabetes with promising benefits in addition to weight loss. © 2016 World Obesity. PMID:27125902

  13. RF system at HIRFL-CSR main ring

    NASA Astrophysics Data System (ADS)

    Zhang, W. Z.; Zhang, D. S.; Zhan, W. L.

    2001-12-01

    A heavy ion cooler-storage ring HIRFL-CSR[1] has been constructed at IMP. It consists of a main ring (CSRm) and an experimental ring (CSRe). Two RF cavities will be employed for CSRm. One is for beam acceleration, and another is for beam RF stacking. The accelerating cavity is designed to accelerate the beam from 10-50 MeV/u to 400-900 MeV/u with harmonic number h=1. The peak RF voltage is 8.0 kV and frequency range is from 0.25 MHz to 1.7 MHz. The RF stacking cavity with maximum voltage amplitude of 20 kV and tunable frequency range 6.0-14.0 MHz is used to capture the injected bunches from injector SSC (or SFC) and to accumulate the beam to high intensity by RF stacking method. In the present paper, the designed RF parameters and the details of hardware for the RF system are described.

  14. Planetary rings

    SciTech Connect

    Greenberg, R.; Brahic, A.

    1984-01-01

    Among the topics discussed are the development history of planetary ring research, the view of planetary rings in astronomy and cosmology over the period 1600-1900, the characteristics of the ring systems of Saturn and Uranus, the ethereal rings of Jupiter and Saturn, dust-magnetosphere interactions, the effects of radiation forces on dust particles, the collisional interactions and physical nature of ring particles, transport effects due to particle erosion mechanisms, and collision-induced transport processes in planetary rings. Also discussed are planetary ring waves, ring particle dynamics in resonances, the dynamics of narrow rings, the origin and evolution of planetary rings, the solar nebula and planetary disk, future studies of the planetary rings by space probes, ground-based observatories and earth-orbiting satellites, and unsolved problems in planetary ring dynamics.

  15. High resolution upgrade of the ATF damping ring BPM system

    SciTech Connect

    Terunuma, N.; Urakawa, J.; Frisch, J.; May, J.; McCormick, D.; Nelson, J.; Seryi, A.; Smith, T.; Woodley, M.; Briegel, C.; Dysert, R.; /Fermilab

    2008-05-01

    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished in its first stage, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, and also tests a new automatic gain error correction schema. The technical concept and realization, as well as preliminary results of beam studies are presented.

  16. Status of NSLS-II Storage Ring Vacuum Systems

    SciTech Connect

    Doom,L.; Hseuh,H.; Ferreira, M.; Longo, C.; Ravindranath, V.; Settepani, P.; Sharma, S.; Wilson, K.

    2009-05-04

    National Synchrotron Light Source II (NSLS-II), being constructed at Brookhaven National Laboratory, is a 3-GeV, high-flux and high- brightness synchrotron radiation facility with a nominal current of 500 mA. The storage ring vacuum system will have extruded aluminium chambers with ante-chamber for photon fans and distributed NEG strip pumping. Discrete photon absorbers will be used to intercept the un-used bending magnet radiation. In-situ bakeout will be implemented to achieve fast conditioning during initial commissioning and after interventions.

  17. Exogenous dust delivery into the Saturnian system and the age of Saturn's rings

    NASA Astrophysics Data System (ADS)

    Kempf, S.; Horanyi, M.; Srama, R.; Altobelli, N.

    2015-10-01

    Even 450 years after Galileo Galilei's discovery of Saturn's rings, their origin and evolution is still not known. The rings are the brightest of the four ring systems of the solar system and have at least the mass of the moon Mimas[?]. Interactions with Saturn's moons and viscous spreading of the ring material seem to imply a ring age of about a tenth of the age of the Saturnian system of about 4.5 billion years[?, ?]. A young ring age is problematic because the disruption of a Mimas-sized body or a comet in the Roche zone of Saturn would result in a ring with a much larger rock content than observed today[?, ?, ?]. The unique ring color resulting mainly from the pollution of the ring material with interplanetary meteoroids provides a key for constraining the ring age[?, ?, ?]. Here we report on the first direct measurements of the meteoroid flux into the Saturnian system byCassini's Cosmic Dust Analyzer (CDA).We measured the impact speed vectors of 133 extrinsic micrometeoroids # 2μm and determined their orbital elements. We determined the mass flux into the Saturnian system to be 10-18kg/m2s. This finding suggest a ring exposure time of 4.5 billion years and is in support of an early ring generation from a proto-Titan during the formation of the Saturnian system[?].

  18. O-Ring sealing arrangements for ultra-high vacuum systems

    DOEpatents

    Kim, Chang-Kyo; Flaherty, Robert

    1981-01-01

    An all metal reusable O-ring sealing arrangement for sealing two concentric tubes in an ultra-high vacuum system. An O-ring of a heat recoverable alloy such as Nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The O-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the O-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  19. Klystron 'efficiency loop' for the ALS storage ring RF system

    SciTech Connect

    Kwiatkowski, Slawomir; Julian, Jim; Baptiste, Kenneth

    2002-05-20

    The recent energy crisis in California has led us to investigate the high power RF systems at the Advanced Light Source (ALS) in order to decrease the energy consumption and power costs. We found the Storage Ring Klystron Power Amplifier system operating as designed but with significant power waste. A simple proportional-integrator (PI) analog loop, which controls the klystron collector beam current, as a function of the output RF power, has been designed and installed. The design considerations, besides efficiency improvement, were to interface to the existing system without major expense. They were to also avoid the klystron cathode power supply filter's resonance in the loop's dynamics, and prevent a conflict with the existing Cavity RF Amplitude Loop dynamics. This efficiency loop will allow us to save up to 700 MW-hours of electrical energy per year and increase the lifetime of the klystron.

  20. TRANSIT MODEL OF PLANETS WITH MOON AND RING SYSTEMS

    SciTech Connect

    Tusnski, Luis Ricardo M.; Valio, Adriana E-mail: avalio@craam.mackenzie.br

    2011-12-10

    Since the discovery of the first exoplanets, those most adequate for life to begin and evolve have been sought. Due to observational bias, however, most of the discovered planets so far are gas giants, precluding their habitability. However, if these hot Jupiters are located in the habitable zones of their host stars, and if rocky moons orbit them, then these moons may be habitable. In this work, we present a model for planetary transit simulation considering the presence of moons and planetary rings around a planet. The moon's orbit is considered to be circular and coplanar with the planetary orbit. The other physical and orbital parameters of the star, planet, moon, and rings can be adjusted in each simulation. It is possible to simulate as many successive transits as desired. Since the presence of spots on the surface of the star may produce a signal similar to that of the presence of a moon, our model also allows for the inclusion of starspots. The result of the simulation is a light curve with a planetary transit. White noise may also be added to the light curves to produce curves similar to those obtained by the CoRoT and Kepler space telescopes. The goal is to determine the criteria for detectability of moons and/or ring systems using photometry. The results show that it is possible to detect moons with radii as little as 1.3 R{sub Circled-Plus} with CoRoT and 0.3 R{sub Circled-Plus} with Kepler.

  1. Computer Generation of Wiswesser Line Notation: II. Polyfused, Perifused, and Chained Ring Systems

    ERIC Educational Resources Information Center

    Heller, Stephen R.; Koniver, Deena A.

    1972-01-01

    The computer program for the generation of Wiswesser Line Notation (WLN) has been extended to include polyfused rings, methyl contraction rules, chain of two ring systems, some perifused rings, some chelates, and some metallocenes. Salts and ions are also handled, but in a different manner than what is normally found. (10 references) (Author/NH)

  2. Enantioselective synthesis of the predominant AB ring system of the Schisandra nortriterpenoid natural products.

    PubMed

    Gockel, Birgit; Goh, Shermin S; Puttock, Emma J; Baars, Hannah; Chaubet, Guilhem; Anderson, Edward A

    2014-09-01

    An enantioselective synthesis of the AB ring system common to the majority of the Schisandra nortriterpenoid natural products is reported. Key steps include a stereospecific ring opening of a trisubstituted epoxide and the use of a β-lactone to enable installation of the gem-dimethyl functionality of the B ring. An acetalization strategy played a key role in a late-stage biomimetic AB ring bicyclization.

  3. ABC's of Being Smart

    ERIC Educational Resources Information Center

    Foster, Joanne

    2011-01-01

    Determining what giftedness is all about means focusing on many aspects of the individual. In this paper, the author focuses on letter D of the ABC's of being smart. She starts with specifics about giftedness (details), and then moves on to some ways of thinking (dispositions).

  4. Androgynous, Reconfigurable Closed Loop Feedback Controlled Low Impact Docking System With Load Sensing Electromagnetic Capture Ring

    NASA Technical Reports Server (NTRS)

    Lewis, James L. (Inventor); Carroll, Monty B. (Inventor); Morales, Ray H. (Inventor); Le, Thang D. (Inventor)

    2002-01-01

    The present invention relates to a fully androgynous, reconfigurable closed loop feedback controlled low impact docking system with load sensing electromagnetic capture ring. The docking system of the present invention preferably comprises two Docking- assemblies, each docking assembly comprising a load sensing ring having an outer face, one of more electromagnets, one or more load cells coupled to said load sensing ring. The docking assembly further comprises a plurality of actuator arms coupled to said load sensing ring and capable of dynamically adjusting the orientation of said load sensing ring and a reconfigurable closed loop control system capable of analyzing signals originating from said plurality of load cells and of outputting real time control for each of the actuators. The docking assembly of the present invention incorporates an active load sensing system to automatically dynamically adjust the load sensing ring during capture instead of requiring significant force to push and realign the ring.

  5. Semi-synthesis of biologically active nisin hybrids composed of the native lanthionine ABC-fragment and a cross-stapled synthetic DE-fragment.

    PubMed

    Slootweg, Jack C; Peters, Nienke; Quarles van Ufford, H Linda C; Breukink, Eefjan; Liskamp, Rob M J; Rijkers, Dirk T S

    2014-10-01

    The antimicrobial peptide nisin is a promising template for designing novel peptide-based antibiotics to improve its drug-like properties. First steps in that direction represent the synthesis of hybrid nisin derivatives that contain a native nisin ABC-part and synthesized cross-stapled DE-ring fragments and are described here. The biological activity of the newly synthesized nisin derivatives was evaluated in order to compare the bioactivity of the synthetic DE-ring containing mimic and native lanthionine-bridged DE-ring containing nisin. The native nisin ABC-ring system was obtained via chymotrypsin digestion of full-length nisin, and was subsequently functionalized at the C-terminal carboxylate with two different amino alkyne moieties. Next, nisin hybrids were successfully prepared using Cu(I)-catalyzed azide alkyne cycloaddition 'click' chemistry by chemo-selective ligation of the ABC-alkyne with the N-terminal azido functionalized dicarba-DE ring mimic. The newly synthesized compounds were active as potent lipid II binders and retained antimicrobial activity in a growth inhibition assay. However, pore formation was not observed, possibly either due to the different character of the 'staples' as compared to the parent sulfides, or due to the triazole moiety as a sub-optimal amide bond isostere.

  6. Semi-synthesis of biologically active nisin hybrids composed of the native lanthionine ABC-fragment and a cross-stapled synthetic DE-fragment.

    PubMed

    Slootweg, Jack C; Peters, Nienke; Quarles van Ufford, H Linda C; Breukink, Eefjan; Liskamp, Rob M J; Rijkers, Dirk T S

    2014-10-01

    The antimicrobial peptide nisin is a promising template for designing novel peptide-based antibiotics to improve its drug-like properties. First steps in that direction represent the synthesis of hybrid nisin derivatives that contain a native nisin ABC-part and synthesized cross-stapled DE-ring fragments and are described here. The biological activity of the newly synthesized nisin derivatives was evaluated in order to compare the bioactivity of the synthetic DE-ring containing mimic and native lanthionine-bridged DE-ring containing nisin. The native nisin ABC-ring system was obtained via chymotrypsin digestion of full-length nisin, and was subsequently functionalized at the C-terminal carboxylate with two different amino alkyne moieties. Next, nisin hybrids were successfully prepared using Cu(I)-catalyzed azide alkyne cycloaddition 'click' chemistry by chemo-selective ligation of the ABC-alkyne with the N-terminal azido functionalized dicarba-DE ring mimic. The newly synthesized compounds were active as potent lipid II binders and retained antimicrobial activity in a growth inhibition assay. However, pore formation was not observed, possibly either due to the different character of the 'staples' as compared to the parent sulfides, or due to the triazole moiety as a sub-optimal amide bond isostere. PMID:25199583

  7. Synthesis and biological activity of the C'D'E'F' ring system of maitotoxin.

    PubMed

    Kunitake, Masahiro; Oshima, Takahiro; Konoki, Keiichi; Ebine, Makoto; Torikai, Kohei; Murata, Michio; Oishi, Tohru

    2014-06-01

    Stereoselective synthesis of the C'D'E'F' ring system of maitotoxin was achieved starting from the E' ring through successive formation of the D' and C' rings based on SmI2-mediated reductive cyclization. Construction of the F' ring was accomplished via Suzuki-Miyaura cross-coupling with a side chain fragment and Pd(II)-catalyzed cyclization of an allylic alcohol. The C'D'E'F' ring system inhibited maitotoxin-induced Ca(2+) influx in rat glioma C6 cells with an IC50 value of 59 μM.

  8. The second ring-moon system of Uranus: discovery and dynamics.

    PubMed

    Showalter, Mark R; Lissauer, Jack J

    2006-02-17

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All of them orbit outside of Uranus's previously known (main) ring system but are interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely packed, rapidly varying, and possibly unstable dynamical system. PMID:16373533

  9. The second ring-moon system of Uranus: discovery and dynamics.

    PubMed

    Showalter, Mark R; Lissauer, Jack J

    2006-02-17

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All of them orbit outside of Uranus's previously known (main) ring system but are interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely packed, rapidly varying, and possibly unstable dynamical system.

  10. The Second Ring-Moon System of Uranus: Discovery and Dynamics

    NASA Technical Reports Server (NTRS)

    Showalter, M. R.; Lissauer, J. J.

    2005-01-01

    Deep exposures of Uranus taken with the Hubble Space Telescope reveal two small moons and two faint rings. All orbit outside of Uranus's previously known (main) ring system, but interior to the large, classical moons. The outer new moon, U XXVI Mab, orbits at roughly twice the radius of the main rings and shares its orbit with a dust ring. The second moon, U XXVII Cupid, orbits just interior to the satellite Belinda. A second ring falls between the orbits of Portia and Rosalind, in a region with no known source bodies. Collectively, these constitute a densely-packed, rapidly varying and possibly unstable dynamica1 system.

  11. Saturn's F ring and shepherd satellites a natural outcome of satellite system formation

    NASA Astrophysics Data System (ADS)

    Hyodo, Ryuki; Ohtsuki, Keiji

    2015-09-01

    Saturn's F ring is a narrow ring of icy particles, located 3,400 km beyond the outer edge of the main ring system. Enigmatically, the F ring is accompanied on either side by two small satellites, Prometheus and Pandora, which are called shepherd satellites. The inner regular satellites of giant planets are thought to form by the accretion of particles from an ancient massive ring and subsequent outward migration. However, the origin of a system consisting of a narrow ring and shepherd satellites remains poorly understood. Here we present N-body numerical simulations to show that a collision of two of the small satellites that are thought to accumulate near the main ring's outer edge can produce a system similar to the F ring and its shepherd satellites. We find that if the two rubble-pile satellites have denser cores, such an impact results in only partial disruption of the satellites and the formation of a narrow ring of particles between two remnant satellites. Our simulations suggest that the seemingly unusual F ring system is a natural outcome at the final stage of the formation process of the ring-satellite system of giant planets.

  12. Photometric Analysis of the Jovian Ring System and Modeling of Ring Origin and Evolution

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.

    2003-01-01

    We have successfully completed the work described in our proposal. The work supported by this grant resulted in the publication of the following paper: Brooks, S. M., L. W. Esposito, M. R. Showalter, and H. B. Throop. 2002. The size distribution of Jupiter's main ring from Galileo imaging and spectroscopy. Icarus, in press. This was also the major part of Dr. Shawn Brooks PhD dissertation. Dr. Brooks gave oral presentations on this work at the Lunar and Planetary Conference, the annual meetings of the Division for Planetary Sciences of the American Astronomical Society, the annual meetings of the European Geophysical Society, the international Jupiter Conference in Boulder, the Jupiter after Galileo and Cassini Conference in Lisbon and to the Working Group in Non-Linear Dynamics in Potsdam, Germany. This work was reviewed in: Esposito, L. W. 2002. Planetary rings. Rep. hog. Phys. 65, 1741-1783. Planetary rings. LASP reprint 874. Online at http://stacks.iop.org/RoPP/65/1741. Dr. Esposito gave presentations at schools and over the internet on the results of this work. Dr. Brooks lectured in undergraduate and graduate classes on Jupiter's rings, and on the meaning of his research. In August 2003, Dr. Shawn Brooks received the Phd degree from the University of Colorado in Astrophysical and Planetary Sciences.

  13. Commissioning results of the APS storage ring diagnostics systems

    SciTech Connect

    Lumpkin, A.H.

    1996-12-31

    Initial commissionings of the Advanced Photon Source (APS) 7-GeV storage ring and its diagnostics systems have been done. Early studies involved single-bunch measurements for beam transverse size ({sigma}{sub x} {approx} 150 {mu}m, {sigma}{sub y} {approx} 50 {mu}m), current, injection losses, and bunch length. The diagnostics have been used in studies related to the detection of an extra contribution to beam jitter at {approximately} 6.5 Hz frequency; observation of bunch lengthening ({sigma} {approx} 30 to 60 ps) with single-bunch current; observation of an induced vertical, head-tail instability; and detection of a small orbit change with insertion device gap position. More recently, operations at 100-mA stored-beam current, the baseline design goal, have been achieved with the support of beam characterizations.

  14. Arrayed Micro-Ring Spectrometer System and Method of Use

    NASA Technical Reports Server (NTRS)

    Choi, Sang H. (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2012-01-01

    A spectrometer system includes an array of micro-zone plates (MZP) each having coaxially-aligned ring gratings, a sample plate for supporting and illuminating a sample, and an array of photon detectors for measuring a spectral characteristic of the predetermined wavelength. The sample plate emits an evanescent wave in response to incident light, which excites molecules of the sample to thereby cause an emission of secondary photons. A method of detecting the intensity of a selected wavelength of incident light includes directing the incident light onto an array of MZP, diffracting a selected wavelength of the incident light onto a target focal point using the array of MZP, and detecting the intensity of the selected portion using an array of photon detectors. An electro-optic layer positioned adjacent to the array of MZP may be excited via an applied voltage to select the wavelength of the incident light.

  15. Commissioning results of the APS storage ring diagnostics systems

    NASA Astrophysics Data System (ADS)

    Lumpkin, Alex H.

    1997-01-01

    Initial commissionings of the Advanced Photon Source (APS) 7-GeV storage ring and its diagnostics systems have been done. Early studies involved single-bunch measurements for beam transverse size (σx≈150 μm, σy≈50 μm,) current, injection losses, and bunch length. The diagnostics have been used in studies related to the detection of an extra contribution to beam jitter at ˜6.5 Hz frequency; observation of bunch lengthening (σ≈30 to 60 ps) with single-bunch current; observation of an induced vertical, head-tail instability; and detection of a small orbit change with insertion device gap position. More recently, operations at 100-mA stored-beam current, the baseline design goal, have been achieved with the support of beam characterizations.

  16. Results from a survey of the dynamics shaping Uranus' Mab/μ-ring system

    NASA Astrophysics Data System (ADS)

    Kumar, Kartik; de Pater, Imke; Showalter, Mark R.

    2014-11-01

    Based on Hubble Space Telescope (HST) data, Showalter and Lissauer (2006) reported the discovery of two faint rings beyond Uranus’ main rings: the ν- and μ- rings. They constitute Uranus' outer ring system and are located beyond the ɛ-ring but interior to the large classical moons. After co-adding a series of HST images, Showalter and Lissauer (2006) obtained radial profiles for both new rings. They discovered that the peak radial intensity of the μ-ring aligns closely with the orbit of Mab. Along with numerous other observations, this points to the fact that the Mab/μ-ring system is highly coupled.The discovery of the μ-ring has led to open questions about dust dynamics beyond Uranus' main rings. Like Saturn's E-ring, observations reveal that the μ-ring is blue, indicative of a pre-dominance of sub-micron-sized particles (de Pater et al., 2006). The E-ring results from plumes on Enceladus' south pole, however the origin of the μ-ring remains a mystery. The latter is likely fed by ejecta from micro-meteorite impacts with Mab, much like Jupiter's faint rings are regenerated by companion (small) moons (Burns et al., 1999). The μ-ring's steep size-distribution suggests that there is an unknown mechanism at play that hides or removes large dust particles. We present results from an investigation into the forces shaping the μ-ring. To simulate the motion of dust in the Mab/μ-ring system, we developed a numerical toolbox (Dustsim; Kumar et al., 2015) that uses Tudat (Kumar et al., 2012). We performed integrations using Dustsim that included the effects of Uranus' gravity field, titled magnetic moment, solar radiation pressure, and collisions with a putative suite of large μ-ring bodies, hypothesized as the cause of Mab's anomalous orbital motion (Kumar et al., 2014). Following on from previous studies (e.g., Sfair and Giuliatti Winter, 2009; Sfair and Giuliatti Winter, 2012), we present a survey of the expected lifetime of μ-ring dust, as a function of

  17. Chariklo's ring system 3. Exploration of possible Chariklo spin/ring orbit resonances

    NASA Astrophysics Data System (ADS)

    Sicardy, Bruno; El Moutamid, Maryame; Leiva, Rodrigo; Berard, Diane; Renner, Stéfan

    2016-10-01

    Two dense and narrow rings orbit the Centaur object Chariklo at respective radii of 391±3 and 405±3 km (Braga-Ribas et al., Nature 508, 72, 2014).With a rotation period of PC = 7.004 ± 0.036 h (Fornasier et al. A.&A. 568, L11, 2014), Chariklo may adopt either a MacLaurin spheroid or a Jacobi ellipsoid shape, depending on density (and assuming hydrostatic equilibrium). Moreover, being a small icy body, Chariklo is prone to topographic features at several-kilometer scales.Meanwhile, scarce information on Chariklo's size and shape is presently available from occultation works, as only five chords have been obtained during three occultations that have been observed in 2013 and 2014. Those data are consistent with a MacLaurin shape with axes a, b, c ~ 133x133x110 km and mass MC ~ (1-2)x1019 kg, or with a Jacobi shape with a, b, c ~ 167x133x124 km and MC ~ 0.6-0.7x1019 kg, see the companion paper by Leiva et al.Those values imply a corotation radius between 190 and 280 km, depending on the adopted value of MC. This is well inside the ring radii, ruling out the corotation resonance as the main driver for the ring orbital dynamics.The ring orbital period could lie between Pr ~12 and 22 h, depending on MC, thus allowing possible resonances with Chariklo's spin rate ΩC. Two models will be explored. One model assumes a MacLaurin shape with a topographic feature of mass m that acts as perturbing satellites with orbital radius and period a and PC, respectively. This creates 1st order Linblad-type resonances of the kind Pr/PC = m+1/m (m integer) whose possible effects on the ring structure will be evaluated.The other model assumes a Jacobi shape that creates a perturbing potential GMc/r3 [(A+B-2C)2 + (3/2)(A-B).cos(2θ)] with θ= λ-ΩC.t in Chariklo's equatorial plane, where A, B, C are the moments of inertia around a, b, c, respectively, and λ is the mean longitude. This creates qth order Linblad-type resonances of the kind Pr/PC = q+2/q (q integer) that will also be

  18. Structural diversity of ABC transporters

    PubMed Central

    ter Beek, Josy; Guskov, Albert

    2014-01-01

    ATP-binding cassette (ABC) transporters form a large superfamily of ATP-dependent protein complexes that mediate transport of a vast array of substrates across membranes. The 14 currently available structures of ABC transporters have greatly advanced insight into the transport mechanism and revealed a tremendous structural diversity. Whereas the domains that hydrolyze ATP are structurally related in all ABC transporters, the membrane-embedded domains, where the substrates are translocated, adopt four different unrelated folds. Here, we review the structural characteristics of ABC transporters and discuss the implications of this structural diversity for mechanistic diversity. PMID:24638992

  19. Placement of the GaBP ring system in the banded gastric bypass operation.

    PubMed

    Fobi, Mathias A L

    2005-09-01

    Currently, bariatric surgeons fashion the band or ring reinforcement prosthesis, to control the stoma in the vertical banded gastroplasty and gastric bypass operations for morbid obesity. To meet this need, the GaBP Ring system has been developed in various sizes, and consists of 4 main parts to provide a means for inserting a ring around the gastric pouch in the banded gastric bypass or the vertical banded gastroplasty. The pre-manufactured and sterilized device provides for better standardization and quality control than individually surgeon-fashioned devices. The GaBP Ring system is described, and the technique of placement and the pertinent initial clinical results are presented. PMID:16197796

  20. Status of /hacek C/erenkov Ring Imaging systems

    SciTech Connect

    Leith, D.W.G.S.

    1987-06-01

    Cerenkov Ring Imaging is briefly introduced, and the problems or choices of designing such a counter are discussed. Recent results from the DELPHI and SLD prototype are presented and compared to the expected performances. 13 refs., 33 figs., 2 tabs.

  1. System analysis and design for the resonant inductive nearfield generation system (RINGS)

    NASA Astrophysics Data System (ADS)

    Alinger, Dustin James

    The Resonant Inductive Near-field Generation System (RINGS) is a technology demonstrator experiment which will allow for the first ever testing of electromagnetic formation flight (EMFF) algorithms in a full six degree of freedom environment on board the International Space Station (ISS). RINGS is a hybrid design, which, in addition to providing EMFF capabilities, also allows for wireless power transfer (WPT) via resonant inductive coupling. This thesis presents an overview of the mechanical and electrical design of the RINGS experiment, as well as simulation techniques used to model various system parameters in both EMFF and WPT operational modes. Also presented is an analytical and experimental investigation of the influence of the proximity effect on a multi-layer flat spiral coil made from ribbon wire.

  2. An ABC for decision making.

    PubMed

    Garcia, Luiz Henrique Costa; Ferreira, Bruna Cortez

    2015-01-01

    The present study was aimed at proposing a systematic evaluation of cranial computed tomography, identifying the main aspects to be analyzed in order to facilitate the decision making process regarding diagnosis and management in emergency settings. The present descriptive study comprised a literature review at the following databases: Access Medicine and Access Emergency Medicine (McGraw- Hill Education); British Medical Journal Evidence Center; UptoDate; Bireme; PubMed; Lilacs; SciELO; ProQuest; Micromedex (Thomson Reuters); Embase. Once the literature review was completed, the authors identified the main diseases with tomographic repercussions and proposed the present system to evaluate cranial computed tomography images. An easy-to-memorize ABC system will facilitate the decision making in emergency settings, as it covers the main diseases encountered by intensivists and emergency physicians, and provides a sequential guidance about anatomical structures to be investigated as well as their respective alterations.

  3. An ABC for decision making*

    PubMed Central

    Garcia, Luiz Henrique Costa; Ferreira, Bruna Cortez

    2015-01-01

    The present study was aimed at proposing a systematic evaluation of cranial computed tomography, identifying the main aspects to be analyzed in order to facilitate the decision making process regarding diagnosis and management in emergency settings. The present descriptive study comprised a literature review at the following databases: Access Medicine and Access Emergency Medicine (McGraw- Hill Education); British Medical Journal Evidence Center; UptoDate; Bireme; PubMed; Lilacs; SciELO; ProQuest; Micromedex (Thomson Reuters); Embase. Once the literature review was completed, the authors identified the main diseases with tomographic repercussions and proposed the present system to evaluate cranial computed tomography images. An easy-to-memorize ABC system will facilitate the decision making in emergency settings, as it covers the main diseases encountered by intensivists and emergency physicians, and provides a sequential guidance about anatomical structures to be investigated as well as their respective alterations. PMID:25987751

  4. Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Cuzzi, J. N.

    2014-12-01

    The rings are changing before our eyes; structure varies on all timescales and unexpected things have been discovered. Many questions have been answered, but some answers remain elusive (see Cuzzi et al 2010 for a review). Here we highlight the major ring science progress over the mission to date, and describe new observations planned for Cassini's final three years. Ring Composition and particle sizes: The rings are nearly all water ice with no other ices - so why are they reddish? The C Ring and Cassini Division are "dirtier" than the more massive B and A Rings, as shown by near-IR and, recently, microwave observations. Particle sizes, from stellar and radio occultations, vary from place to place. Ring structure, micro and macro: numerous spiral density waves and ubiquitous "self-gravity wakes" reveal processes which fostered planet formation in the solar system and elsewhere. However, big puzzles remain regarding the main ring divisions, the C Ring plateau structures, and the B Ring irregular structure. Moonlets, inside and out, seen and unseen: Two gaps contain sizeable moonlets, but more gaps seem to contain none; even smaller embedded "propeller" objects wander, systematically or randomly, through the A ring. Rubble pile ringmoons just outside the rings may escaped from the rings, and the recently discovered "Peggy" may be trying this as we watch. Impact bombardment of the rings: Comet fragments set the rings to rippling on century-timescales, and boulders crash through hourly; meanwhile, the constant hail of infalling Kuiper belt material has a lower mass flux than previously thought. Origin and Age of the Rings: The ring mass and bombardment play key roles. The ring mass is well known everywhere but in the B Ring (where most of it is). New models suggest how tidal breakup of evolving moons may have formed massive ancient rings, of which the current ring is just a shadow. During its last three years, the Cassini tour profile will allow entirely new

  5. Multiple internal seal ring micro-electro-mechanical system vacuum packaging method

    NASA Technical Reports Server (NTRS)

    Hayworth, Ken J. (Inventor); Yee, Karl Y. (Inventor); Shcheglov, Kirill V. (Inventor); Bae, Youngsam (Inventor); Wiberg, Dean V. (Inventor); Challoner, A. Dorian (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    A Multiple Internal Seal Ring (MISR) Micro-Electro-Mechanical System (MEMS) vacuum packaging method that hermetically seals MEMS devices using MISR. The method bonds a capping plate having metal seal rings to a base plate having metal seal rings by wafer bonding the capping plate wafer to the base plate wafer. Bulk electrodes may be used to provide conductive paths between the seal rings on the base plate and the capping plate. All seals are made using only metal-to-metal seal rings deposited on the polished surfaces of the base plate and capping plate wafers. However, multiple electrical feed-through metal traces are provided by fabricating via holes through the capping plate for electrical connection from the outside of the package through the via-holes to the inside of the package. Each metal seal ring serves the dual purposes of hermetic sealing and providing the electrical feed-through metal trace.

  6. Ring lens focusing and push-pull tracking scheme for optical disk systems

    NASA Technical Reports Server (NTRS)

    Gerber, R.; Zambuto, J.; Erwin, J. K.; Mansuripur, M.

    1993-01-01

    An experimental comparison of the ring lens and the astigmatic techniques of generating focus-error-signal (FES) in optical disk systems reveals that the ring lens generates a FES over two times steeper than that produced by the astigmat. Partly due to this large slope and, in part, because of its diffraction-limited behavior, the ring lens scheme exhibits superior performance characteristics. In particular the undesirable signal known as 'feedthrough' (induced on the FES by track-crossings during the seek operation) is lower by a factor of six compared to that observed with the astigmatic method. The ring lens is easy to align and has reasonable tolerance for positioning errors.

  7. Do You Know Your ABC?

    ERIC Educational Resources Information Center

    Neale, Claire

    2013-01-01

    Within primary schools, the core subjects of literacy and numeracy are highly regarded, and rightly so, as children need to learn to read, write and be numerically literate. This means that all children learn their ABCs at an early age, But, what about the "other ABC"--"Airway, Breathing and Circulation?" Accidents and medical…

  8. The Ring System of Uranus: Flat as a Pancake, Sprinkled with Dust

    SciTech Connect

    de Pater, I; Gibbard, S G; Hammel, H B

    2005-02-02

    We present a high quality image of the uranian ring system, obtained in July 2004 at 2.2 {micro}m with the adaptive optics camera NIRC2 on the Keck II telescope. Using these data, we report the first ground-based image of the ring 1986U2R, seen only once before by the Voyager spacecraft. We show that this ring extends inward to {approx} 7000 km above the Uranus cloud deck. Its VIF (total vertically integrated I/F) is {approx} 100 m. We further detected narrow sheets of dust in between the {delta} and {epsilon} rings, and in between rings 4 and {alpha}, with a VIF of 14 and 20 m, respectively. Surprisingly, we find that the particles in Uranus' 9 main rings are distributed within a mono-layer, rather than the usually adopted poly-layer model. We come to this conclusion via a comparison of the VIF as derived from our 2003 data at a ring opening angle B {approx} 18{sup o} (from Gibbard et al. 2004) with those derived in this paper at B {approx} 11{sup o}. We show that the VIF increases approximately as 1/sinB at the ring ansae, but is independent of sinB in front of the disk. This combination of factors can only be explained if the particles in Uranus' rings are distributed in a mono-layer, a configuration which makes the uranian system unique amongst the giant planets.

  9. Note: O-ring stack system for electron gun alignment.

    PubMed

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-01

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications. PMID:25638137

  10. Note: O-ring stack system for electron gun alignment

    NASA Astrophysics Data System (ADS)

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-01

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  11. Note: O-ring stack system for electron gun alignment

    SciTech Connect

    Park, In-Yong; Cho, Boklae; Han, Cheolsu; Shin, Seungmin; Lee, Dongjun; Ahn, Sang Jung

    2015-01-15

    We present a reliable method for aligning an electron gun which consists of an electron source and lenses by controlling a stack of rubber O-rings in a vacuum condition. The beam direction angle is precisely tilted along two axes by adjusting the height difference of a stack of O-rings. In addition, the source position is shifted in each of three orthogonal directions. We show that the tilting angle and linear shift along the x and y axes as obtained from ten stacked O-rings are ±2.55° and ±2 mm, respectively. This study can easily be adapted to charged particle gun alignment and adjustments of the flange position in a vacuum, ensuring that its results can be useful with regard to electrical insulation between flanges with slight modifications.

  12. Gaseous toroid around Saturn. [Saturnian ring system for atomic hydrogen trapping in Titan atmospheric model

    NASA Technical Reports Server (NTRS)

    Mcdonough, T. R.

    1974-01-01

    The trapping of Titan's escaping atmosphere in the Saturnian system by a toroidal ring is discussed. The radius of the toroid is comparable to Titan's orbit, or about ten times larger than the visible rings. Theoretical atmospheric models are formulated that consider Saturn's gravitational attraction and magnetospheric properties in forming this toroid and in protecting toroid particles from direct ionization by solar wind particles.

  13. Horizontal gene transfer and diverse functional constrains within a common replication-partitioning system in Alphaproteobacteria: the repABC operon

    PubMed Central

    2009-01-01

    Background The repABC plasmid family, which is extensively present within Alphaproteobacteria, and some secondary chromosomes of the Rhizobiales have the particular feature that all the elements involved in replication and partitioning reside within one transcriptional unit, the repABC operon. Given the functional interactions among the elements of the repABC operon, and the fact that they all reside in the same operon, a common evolutionary history would be expected if the entire operon had been horizontally transferred. Here, we tested whether there is a common evolutionary history within the repABC operon. We further examined different incompatibility groups in terms of their differentiation and degree of adaptation to their host. Results We did not find a single evolutionary history within the repABC operon. Each protein had a particular phylogeny, horizontal gene transfer events of the individual genes within the operon were detected, and different functional constraints were found within and between the Rep proteins. When different repABC operons coexisted in the same genome, they were well differentiated from one another. Finally, we found different levels of adaptation to the host genome within and between repABC operons coexisting in the same species. Conclusion Horizontal gene transfer with conservation of the repABC operon structure provides a highly dynamic operon in which each member of this operon has its own evolutionary dynamics. In addition, it seems that different incompatibility groups present in the same species have different degrees of adaptation to their host genomes, in proportion to the amount of time the incompatibility group has coexisted with the host genome. PMID:19919719

  14. Chariklo's ring system 2. Main body physical constraints

    NASA Astrophysics Data System (ADS)

    Leiva, Rodrigo; Sicardy, Bruno; Berard, Diane; Meza Quispe, Erick; camargo, julio; Assafin, Marcelo; Braga-Ribas, Felipe; Vieira-Martins, Roberto; Maquet, Lucie; Colas, François; Sickafoose, Amanda A.; Bath, Karl-Ludwig; Dauvergne, Jean-Luc

    2016-10-01

    We report the observation of two multi-chord stellar occultation by the Centaur object (10199) Chariklo on 29 April 2014 and 28 June 2014. From these and a previously published observation on 3 June 2013 (Braga-Ribas et al 2014) we estimate Chariklo's size, shape and density using a Bayesian approach. Assuming an homogeneous body in hydrostatic equilibrium we consider two possible models. For a Maclaurin spheroid model, topographic features of 8 km are needed to fit all the events and a density of 1.29 (+2.28-0.18) g cm ‑3 is found with equatorial radius of a = b = 133 ±5 km and polar radius c=110±10 km. For a Jacobi ellipsoid model, topographic features of 5 km are needed to fit all the events and a density of 0.81 ± 0.01 g cm‑3 is found with semi major axes of a = 167 ± 5 km, b = 133 ±5 km and c = 86±2 km. The mass for the Maclaurin model is 1.72 (+1.64 -0.49) × 1019 kg and for the Jacobi model is 1.08± 0.01 × 1019 kg.Considering a ring at an orbital radius of 400 km (the average radius of Chariklo's rings) we determine a Roche critical density limit for the ring particles of 0.44 g cm ‑3 and 0.20 g cm ‑3 for the Maclaurin and Jacobi model respectively.In a companion abstract we discuss possible resonance effects between Chariklo's spin period and ring particle orbital motion.*RL acknowledges support from CONICYT-PCHA/Doctorado Nacional/2014-21141198**Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ ERC Grant Agreement n 669416 "LUCKY STAR").

  15. Equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    SciTech Connect

    Ip, W.; Mendis, D.A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents ot flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionosheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  16. On the equatorial transport of Saturn's ionosphere as driven by a dust-ring current system

    NASA Astrophysics Data System (ADS)

    Ip, W.-H.; Mendis, D. A.

    1983-03-01

    The diurnal modulation of the dust ring current of Saturn's D-ring causes field-aligned Birkeland currents to flow near the dawn and dusk terminators and close across the mid-latitude ionosphere. One consequence of this current system is the establishment of a global convection pattern in the equatorial outer ionosphere. Outward motion of the dayside ionospheric plasma as well as the corresponding absorption effect of the inner ring system might be one physical cause of the depletion of the ionospheric content of Saturn.

  17. Feasibility study of shape memory alloy ring spring systems for self-centring seismic resisting devices

    NASA Astrophysics Data System (ADS)

    Fang, Cheng; Yam, Michael C. H.; Lam, Angus C. C.; Zhang, Yanyang

    2015-07-01

    Shape memory alloys (SMAs) have recently emerged as promising material candidates for structural seismic resisting purposes. Most of the existing SMA-based strategies, however, are based on the wire or rod form of SMAs, where issues such as gripping complexity and fracture may exist. This paper presents a proof-of-concept study on an innovative type of SMA-based self-centring system, namely, a superelastic SMA ring spring system. The proposed system includes a series of inner high-strength steel (HSS) rings and outer superelastic SMA rings stacked in alternation with mating taper faces, where the resisting load is provided by the wedging action which tends to expand the outer rings and concurrently to squeeze the inner rings. The superelastic effect of the SMA offers energy dissipation and a driving force for recentring, and the frictional effect over the taper face further contributes to the overall resisting load and energy dissipation. The feasibility of the new system is carefully examined via numerical studies considering the parameters of ring thickness, taper angle, and coefficient of friction. The key hysteretic responses, including resisting load, stiffness, stress distributions, source of residual deformation, energy dissipation, and equivalent viscous damping, are discussed in detail. The behaviour of the SMA ring springs is also studied via analytical models, and the analytical predictions are found to agree well with the numerical results. Finally, two practical applications of the new system, namely self-centring HS-SMA ring spring connections, and self-centring SMA ring spring dampers, are discussed via comprehensive numerical studies.

  18. Hydrodynamic optimization of trust ring pump and lubricating oil system for large hydroelectric units thrust bearing

    NASA Astrophysics Data System (ADS)

    Lai, X.; Lu, Z.; Zhang, X.; Yang, S.

    2014-03-01

    Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions form thrust bearing and operation conditions of hydro turbine generator unit. Because the oil circulating and cooling system with thrust-ring- pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump, additionally, the head and discharge are varying with the operation conditions of hydro-generator unit and characteristic of the oil circulating and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulating and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization of both the oil circulating and cooling system and thrust-ring-pump is purposed in this paper. Firstly, the head and discharge required at different conditions are decided by 1D flow numerical simulation of the oil circulating and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and discharge from the simulation. Thirdly, the flow passage geometry matching optimization between holes inside the thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulating and cooling system are collaborative hydrodynamic optimized with predicted head- discharge curve and the efficiency-discharge curve of thrust-ring-pump. The presented methodology has

  19. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    SciTech Connect

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-20

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to 'hop' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power ({>=}330 We at beginning of life) during the 10-year cruise and 1-year science mission ({approx}11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  20. A Saturn Ring Observer Mission Using Multi-Mission Radioisotope Power Systems

    NASA Astrophysics Data System (ADS)

    Abelson, Robert D.; Spilker, Thomas R.; Shirley, James H.

    2006-01-01

    Saturn remains one of the most fascinating planets within the solar system. To better understand the complex ring structure of this planet, a conceptual Saturn Ring Observer (SRO) mission is presented that would spend one year in close proximity to Saturn's A and B rings, and perform detailed observations and measurements of the ring particles and electric and magnetic fields. The primary objective of the mission would be to understand ring dynamics, including the microphysics of individual particles and small scale (meters to a few kilometers) phenomena such as particle agglomeration behavior. This would be accomplished by multispectral imaging of the rings at multiple key locations within the A and B rings, and by ring-particle imaging at an unprecedented resolution of 0.5 cm/pixel. The SRO spacecraft would use a Venus-Earth-Earth-Jupiter Gravity Assist (VEEJGA) and be aerocaptured into Saturn orbit using an advanced aeroshell design to minimize propellant mass. Once in orbit, the SRO would stand off from the ring plane 1 to 1.4 km using chemical thrusters to provide short propulsive maneuvers four times per revolution, effectively causing the SRO vehicle to ``hop'' above the ring plane. The conceptual SRO spacecraft would be enabled by the use of a new generation of multi-mission Radioisotope Power Systems (RPSs) currently being developed by NASA and DOE. These RPSs include the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Stirling Radioisotope Generator (SRG). The RPSs would generate all necessary electrical power (>=330 We at beginning of life) during the 10-year cruise and 1-year science mission (~11 years total). The RPS heat would be used to maintain the vehicle's operating and survival temperatures, minimizing the need for electrical heaters. Such a mission could potentially launch in the 2015-2020 timeframe, with operations at Saturn commencing in approximately 2030.

  1. Pharmacological correction of misfolding of ABC proteins☆

    PubMed Central

    Rudashevskaya, Elena L.; Stockner, Thomas; Trauner, Michael; Freissmuth, Michael; Chiba, Peter

    2014-01-01

    The endoplasmic reticulum (ER) quality control system distinguishes between correctly and incorrectly folded proteins to prevent processing of aberrantly folded conformations along the secretory pathway. Non-synonymous mutations can lead to misfolding of ABC proteins and associated disease phenotypes. Specific phenotypes may at least partially be corrected by small molecules, so-called pharmacological chaperones. Screening for folding correctors is expected to open an avenue for treatment of diseases such as cystic fibrosis and intrahepatic cholestasis. PMID:25027379

  2. Pharmacological correction of misfolding of ABC proteins.

    PubMed

    Rudashevskaya, Elena L; Stockner, Thomas; Trauner, Michael; Freissmuth, Michael; Chiba, Peter

    2014-06-01

    The endoplasmic reticulum (ER) quality control system distinguishes between correctly and incorrectly folded proteins to prevent processing of aberrantly folded conformations along the secretory pathway. Non-synonymous mutations can lead to misfolding of ABC proteins and associated disease phenotypes. Specific phenotypes may at least partially be corrected by small molecules, so-called pharmacological chaperones. Screening for folding correctors is expected to open an avenue for treatment of diseases such as cystic fibrosis and intrahepatic cholestasis. PMID:25027379

  3. The ABCs of Sex Ed.

    ERIC Educational Resources Information Center

    Sroka, Stephen R.

    2002-01-01

    Cites statistics on extent of sexually transmitted diseases and pregnancies among adolescents; describes ideological dispute over how to teach sex education; advocates teaching the ABCs of sex education: Abstinence, Be Monogamous, and Condoms. (PKP)

  4. Dragging of inertial frames in the composed black-hole-ring system

    NASA Astrophysics Data System (ADS)

    Hod, Shahar

    2015-11-01

    A well-established phenomenon in general relativity is the dragging of inertial frames by a spinning object. In particular, due to the dragging of inertial frames by a ring orbiting a central black hole, the angular velocity Ω ^{{BH-ring}}_{{H}} of the black-hole horizon in the composed black-hole-ring system is no longer related to the black-hole angular momentum J_{{H}} by the simple Kerr-like (vacuum) relation Ω ^{{Kerr}}_{{H}}(J_{{H}})=J_{{H}}/2M^2R_{{H}} (here M and R_{{H}} are the mass and horizon-radius of the black hole, respectively). Will has performed a perturbative treatment of the composed black-hole-ring system in the regime of slowly rotating black holes and found the explicit relation Ω ^{{BH-ring}}_{{H}}(J_{{H}}=0,J_{{R}},R)=2J_{{R}}/R^3 for the angular velocity of a central black hole with zero angular momentum, where J_{{R}} and R are respectively the angular momentum of the orbiting ring and its proper circumferential radius. Analyzing a sequence of black-hole-ring configurations with adiabatically varying (decreasing) circumferential radii, we show that the expression found by Will for Ω ^{{BH-ring}}_{{H}}(J_{{H}}=0,J_{{R}},R) implies a smooth transition of the central black-hole angular velocity from its asymptotic near-horizon value Ω ^{{BH-ring}}_{{H}}(J_{{H}}=0,J_{{R}},R→ R+_{{H}})→ 2J_{{R}}/R^3_{{H}} (that is, just before the assimilation of the ring by the central black hole), to its final Kerr (vacuum) value Ω ^{{Kerr}}_{{H}}(J^{{new}}_{{H}})= J^{{new}}_{{H}}/2{M^{{new}}}^2R^{{new}}_{{H}} [that is, after the adiabatic assimilation of the ring by the central black hole. Here J^{{new}}_{{H}}=J_{{R}}, M^{{new}}, and R^{{new}}_{{H}} are the new parameters of the resulting Kerr (vacuum) black hole after it assimilated the orbiting ring]. We use this important observation in order to generalize the result of Will to the regime of black-hole-ring configurations in which the central black holes possess non-zero angular momenta. In

  5. Submission of Earth-based ring occultation observations to the NASA planetary data system rings discipline node

    NASA Technical Reports Server (NTRS)

    French, Richard G.

    1993-01-01

    This is a technical report summarizing our progress in our program of contributing high quality Earth-based occultation observations to NASA's Planetary Data System (PDS) Rings Node. During our first year of funding, we selected five data sets for eventual inclusion in the PDS Rings Node. These were Uranus occultation observations obtained by the PI and co-workers from the IRTF of event stars U34 (26 April 1986), U1052 (5 May 1988), U65 (21 June 1990), U7872 (25 June 1991), and U7808 (28 June 1991). In our original proposal, we described four tasks: data sets to a common format; documentation of the occultation observations and associated calibrations; calculation of the occultation geometry for each event; establish prototype PDS templates. As discussed in our renewal proposal, submitted 8 June 1993, we have completed the first three tasks, and are working on the fourth. As an indication of our progress to date, we provide information about each of the data sets, their formats, the documentation, and the method used for reconstructing the occultation geometry.

  6. The repABC plasmids with quorum-regulated transfer systems in members of the Rhizobiales divide into two structurally and separately evolving groups

    DOE PAGES

    Wetzel, Margaret E.; Olsen, Gary J.; Chakravartty, Vandana; Farrand, Stephen K.

    2015-11-19

    The large repABC plasmids of the order Rhizobiales with Class I quorum-regulated conjugative transfer systems often define the nature of the bacterium that harbors them. These otherwise diverse plasmids contain a core of highly conserved genes for replication and conjugation raising the question of their evolutionary relationships. In an analysis of 18 such plasmids these elements fall into two organizational classes, Group I and Group II, based on the sites at which cargo DNA is located. Cladograms constructed from proteins of the transfer and quorum-sensing components indicated that those of the Group I plasmids, while coevolving, have diverged from thosemore » coevolving proteins of the Group II plasmids. Moreover, within these groups the phylogenies of the proteins usually occupy similar, if not identical, tree topologies. Remarkably, such relationships were not seen among proteins of the replication system; although RepA and RepB coevolve, RepC does not. Nor do the replication proteins coevolve with the proteins of the transfer and quorum-sensing systems. Functional analysis was mostly consistent with phylogenies. TraR activated promoters from plasmids within its group, but not between groups and dimerized with TraR proteins from within but not between groups. However, oriT sequences, which are highly conserved, were processed by the transfer system of plasmids regardless of group. Here, we conclude that these plasmids diverged into two classes based on the locations at which cargo DNA is inserted, that the quorum-sensing and transfer functions are coevolving within but not between the two groups, and that this divergent evolution extends to function.« less

  7. The repABC plasmids with quorum-regulated transfer systems in members of the Rhizobiales divide into two structurally and separately evolving groups

    SciTech Connect

    Wetzel, Margaret E.; Olsen, Gary J.; Chakravartty, Vandana; Farrand, Stephen K.

    2015-11-19

    The large repABC plasmids of the order Rhizobiales with Class I quorum-regulated conjugative transfer systems often define the nature of the bacterium that harbors them. These otherwise diverse plasmids contain a core of highly conserved genes for replication and conjugation raising the question of their evolutionary relationships. In an analysis of 18 such plasmids these elements fall into two organizational classes, Group I and Group II, based on the sites at which cargo DNA is located. Cladograms constructed from proteins of the transfer and quorum-sensing components indicated that those of the Group I plasmids, while coevolving, have diverged from those coevolving proteins of the Group II plasmids. Moreover, within these groups the phylogenies of the proteins usually occupy similar, if not identical, tree topologies. Remarkably, such relationships were not seen among proteins of the replication system; although RepA and RepB coevolve, RepC does not. Nor do the replication proteins coevolve with the proteins of the transfer and quorum-sensing systems. Functional analysis was mostly consistent with phylogenies. TraR activated promoters from plasmids within its group, but not between groups and dimerized with TraR proteins from within but not between groups. However, oriT sequences, which are highly conserved, were processed by the transfer system of plasmids regardless of group. Here, we conclude that these plasmids diverged into two classes based on the locations at which cargo DNA is inserted, that the quorum-sensing and transfer functions are coevolving within but not between the two groups, and that this divergent evolution extends to function.

  8. The repABC Plasmids with Quorum-Regulated Transfer Systems in Members of the Rhizobiales Divide into Two Structurally and Separately Evolving Groups

    PubMed Central

    Wetzel, Margaret E.; Olsen, Gary J.; Chakravartty, Vandana; Farrand, Stephen K.

    2015-01-01

    The large repABC plasmids of the order Rhizobiales with Class I quorum-regulated conjugative transfer systems often define the nature of the bacterium that harbors them. These otherwise diverse plasmids contain a core of highly conserved genes for replication and conjugation raising the question of their evolutionary relationships. In an analysis of 18 such plasmids these elements fall into two organizational classes, Group I and Group II, based on the sites at which cargo DNA is located. Cladograms constructed from proteins of the transfer and quorum-sensing components indicated that those of the Group I plasmids, while coevolving, have diverged from those coevolving proteins of the Group II plasmids. Moreover, within these groups the phylogenies of the proteins usually occupy similar, if not identical, tree topologies. Remarkably, such relationships were not seen among proteins of the replication system; although RepA and RepB coevolve, RepC does not. Nor do the replication proteins coevolve with the proteins of the transfer and quorum-sensing systems. Functional analysis was mostly consistent with phylogenies. TraR activated promoters from plasmids within its group, but not between groups and dimerized with TraR proteins from within but not between groups. However, oriT sequences, which are highly conserved, were processed by the transfer system of plasmids regardless of group. We conclude that these plasmids diverged into two classes based on the locations at which cargo DNA is inserted, that the quorum-sensing and transfer functions are coevolving within but not between the two groups, and that this divergent evolution extends to function. PMID:26590210

  9. Nanostructured assemblies from amphiphilic ABC multiblock polymers

    NASA Astrophysics Data System (ADS)

    Hillmyer, Marc A.

    2012-02-01

    Amphiphilic AB diblock copolymers containing a water compatible segment can self-assemble in aqueous media to give supramolecular structures that include simple spherical micelles and macromolecular vesicles termed polymersomes. Amphiphilic ABA triblocks with hydrophobic end blocks can adopt analogous structures but can also form gels at high polymer concentrations. The structural and chemical diversity demonstrated in block copolymer micelles and gels makes them attractive for applications ranging from drug delivery to personal care products to nanoreactors. The inclusion of a third block in amphiphilic ABC triblock systems can lead to a much wider array of self-assembled structures that depend not only on composition but also on block sequence, architecture and incompatibility considerations. I will present our recent efforts on tuning micelle and gel structure and behavior using controlled architecture ABC triblocks. The combination of diverse polymer segments into a single macromolecule is a powerful method for development of self-assembled structures with both new form and new function.

  10. Creating an iPhone application for collecting continuous ABC data.

    PubMed

    Whiting, Seth W; Dixon, Mark R

    2012-01-01

    This paper provides an overview and task analysis for creating a continuous ABC data-collection application using Xcode on a Mac computer. Behavior analysts can program an ABC data collection system, complete with a customized list of target clients, antecedents, behaviors, and consequences to be recorded, and have the data automatically sent to an e-mail account after observations have concluded. Further suggestions are provided to customize the ABC data- collection system for individual preferences and clinical needs.

  11. Solar system history as recorded in the Saturnian ring structure

    NASA Technical Reports Server (NTRS)

    Alfven, H.

    1983-01-01

    Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure, with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils, which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas, Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent.

  12. Planetary Rings

    NASA Technical Reports Server (NTRS)

    Cuzzi, Jeffrey N.

    1994-01-01

    Just over two decades ago, Jim Pollack made a critical contribution to our understanding of planetary ring particle properties, and resolved a major apparent paradox between radar reflection and radio emission observations. At the time, particle properties were about all there were to study about planetary rings, and the fundamental questions were, why is Saturn the only planet with rings, how big are the particles, and what are they made of? Since then, we have received an avalanche of observations of planetary ring systems, both from spacecraft and from Earth. Meanwhile, we have seen steady progress in our understanding of the myriad ways in which gravity, fluid and statistical mechanics, and electromagnetism can combine to shape the distribution of the submicron-to-several-meter size particles which comprise ring systems into the complex webs of structure that we now know them to display. Insights gained from studies of these giant dynamical analogs have carried over into improved understanding of the formation of the planets themselves from particle disks, a subject very close to Jim's heart. The now-complete reconnaissance of the gas giant planets by spacecraft has revealed that ring systems are invariably found in association with families of regular satellites, and there is ark emerging perspective that they are not only physically but causally linked. There is also mounting evidence that many features or aspects of all planetary ring systems, if not the ring systems themselves, are considerably younger than the solar system

  13. Clumps and Temporal Changes in the Jovian Ring System as Viewed by New Horizons

    NASA Astrophysics Data System (ADS)

    Showalter, Mark R.; Cheng, A. F.; Weaver, H. A.; Stern, S. A.; Spencer, J. R.; Throop, H.; Birath, E. M.; Rose, D.; Moore, J. M.

    2007-10-01

    New Horizons obtained 400 ring images of the Jovian ring system using the Long Range Reconnaissance Imager (LORRI). This camera has a broad bandpass spanning wavelengths λ = 0.35 to 0.85 µm. The ring was imaged at phase angles 7°-159°. In addition, one sequence of near-IR spectra (λ = 1.25 to 2.5 µm) was obtained by the Linear Etalon Imaging Spectral Array (LEISA) for compositional studies. Two ring rotation movies during Jupiter approach were used to search for small moons embedded within the system. These bodies might serve as source bodies for the prevalent ring dust. No moons were detected down to a threshold of 500 m radius, suggesting a sharp cutoff in the population of inner Jovian moons below 8-km Adrastea. Although this search focused on the main Jovian ring, any 1-km moons from orbital radius r = 100,000 km to beyond the orbit of Amalthea (r = 181,000 km) should have been detected multiple times. More surprisingly, the ring revealed two clusters of tiny clumps, one pair and one set of three. These are definitively not moons because they have longitudinal extents of a few tenths of a degree. Separations between clumps are 2 to 4° but are not uniform. These clump families both orbit within a brightness peak just interior to the orbit of Adrastea, at r = 128,740 km. Their origin is unknown. They are not visible at high phase angles, indicating that they are composed primarily of larger "parent” bodies, not dust. They are definitely not related to a clump detected in Cassini images of the Jovian ring from December 2000, indicating that at least some ring clumps are transient. The large quadrant asymmetries reported in earlier images from Voyager and Galileo are completely absent in the new data.

  14. Analysis of a Triple Star System Occulted By Saturn’s Rings

    NASA Astrophysics Data System (ADS)

    Bratcher, Allison; Colwell, J. E.; Bolin, B.

    2012-10-01

    On January 4, 2012, the Ultraviolet Imaging Spectrograph aboard the Cassini Spacecraft observed Saturn’s rings as they occulted the triple star system, Iota Orionis. Remarkably, the brightest star was occulted by the moon Prometheus, and we provide the timing information of first and last contact for navigation purposes and a chord across the moon. The large separation of the individual stars projected in the ring plane makes it possible to measure the profiles of narrow features in the rings as they were occulted by each of the three stars. This occultation thus provides a unique opportunity to measure short-scale longitudinal variations in narrow ringlets with stellar occultation data that usually provide only a single longitudinal sample. Iota Orionis has a low elevation angle (B=1.4 degrees) above the plane of the rings, enhancing the sensitivity of the occultation (by a factor of 1/sin(B)=41) to the optically thin regions of the rings such as the C Ring and the Cassini Division as well as faint ringlets in the Encke gap. We distinguished the three signals by creating a model triple star signal using data from another occultation. We were able to identify several faint, narrow ringlets, including two in the Encke gap, occulted by two of the three stars and more prominent ringlets, such as the Huygens ringlet, in all three stellar light curves. We present the equivalent widths of these ringlets in the data from this triple star system and limits on ring variability over the azimuthal separation of the stars that ranges from 6000 km at the inner C ring to 200 km at the outer A ring.

  15. DESIGN AND DEVELOPMENT OF THE SNS RING VACUUM INSTRUMENTATION AND CONTROL SYSTEMS.

    SciTech Connect

    HSEUH,H.C.; SMART,L.A.; TANG,J.Y.

    2001-06-18

    BNL is undertaking the design, construction and commissioning of the Spallation Neutron Source (SNS) accumulator ring and the beam transport lines [l]. Ultrahigh vacuum of 10{sup {minus}9} Torr is required in the accumulator ring to minimize beam-gas ionization, a contributing factor to the e-p instability observed in a few high-intensity proton storage rings. All vacuum instrumentation must be capable of local and remote operation to achieve a reliable vacuum system, especially in this extremely high intensity accelerator. The design and development of the SNS ring vacuum instrumentation and control through the Experimental Physics and Industrial Control System (EPICS) distributed real-time software tools are presented.

  16. The 1983 June 15 occultation by Neptune. I - Limits on a possible ring system

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.; Baron, R. L.; Dunham, E. W.; French, R. G.; Meech, K. J.; Mink, D. J.; Erickson, E. F.

    1985-01-01

    Observations on 15 June 1983 of an occultation of a star by Neptune from Mauna Kea, Mount Stromlo, Siding Spring, and the Kuiper Airborne Observatory show no evidence for equatorial rings between 25,300 and 200,000 km (R/N/ = 25,269 km). Within most of this region, the upper limit on the optical depth along the line of sight, for rings broader than 6 km , is 0.04, which corresponds to a normal optical depth of 0.016. These results rule out a Neptunian ring system similar to that of Saturn or Uranus, but not a system of low optical depth similar to the Jovian rings. The data show no features that appear likely to have been caused by material in the equatorial plane of Neptune near the Roche limit.

  17. Ring retroreflector system consisting of cube-corner reflectors with special coating

    SciTech Connect

    Burmistrov, V B; Sadovnikov, M A; Sokolov, A L; Shargorodskiy, V D

    2013-09-30

    The ring retroreflector system (RS) consisting of cubecorner reflectors (CCRs) with a special coating of reflecting surfaces, intended for uniaxially Earth-oriented navigation satellites, is considered. The error of distance measurement caused by both the laser pulse delay in the CCR and its spatial position (CCR configuration) is studied. It is shown that the ring RS, formed by the CCR with a double-spot radiation pattern, allows the distance measurement error to be essentially reduced. (nanogradient dielectric coatings and metamaterials)

  18. Concise copper-catalyzed synthesis of tricyclic biaryl ether-linked aza-heterocyclic ring systems.

    PubMed

    Mestichelli, Paola; Scott, Matthew J; Galloway, Warren R J D; Selwyn, Jamie; Parker, Jeremy S; Spring, David R

    2013-11-01

    A new method for the synthesis of tricyclic biaryl ether-linked ring systems incorporating seven-, eight-, and nine-membered ring amines is presented. In the presence of catalytic quantities of copper(I), readily accessible acyclic precursors undergo an intramolecular carbon-oxygen bond-forming reaction facilitated by a "templating" chelating nitrogen atom. The methodology displays a broad substrate scope, is practical, and generates rare and biologically interesting tricyclic heteroaromatic products that are difficult to access by other means.

  19. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    PubMed

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function. PMID:27420523

  20. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    PubMed

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function.

  1. The demise of Phobos and development of a Martian ring system

    NASA Astrophysics Data System (ADS)

    Black, Benjamin A.; Mittal, Tushar

    2015-12-01

    All of the gas giants in our Solar System host ring systems, in contrast to the inner planets. One proposed mechanism of planetary ring formation is disruption or mass shedding of moons. The orbit of Phobos, the larger of Mars's two moonlets, is gradually spiralling inwards towards Mars and the moon is experiencing increasing tidal stresses. Eventually, Phobos will either break apart to form a ring or it will crash into Mars. We evaluate these outcomes based on geologic, spectral and theoretical constraints, in conjunction with a geotechnical model that helps us determine the strength of Phobos. Our analysis suggests that much of Phobos is composed of weak, heavily damaged materials. We suggest that--with continued inward migration of the moon--the weakest material will disperse tidally in 20 to 40 million years to form a Martian ring. We predict that this ring will persist for 106 to 108 years and will initially have a comparable mass density to that of Saturn's rings. Any large fragment of Phobos that is strong enough to escape tidal breakup will eventually collide with Mars in an oblique, low-velocity impact. Our analysis of the evolution of Phobos underscores the potential orbital and topographic consequences of the growth and self-destruction of other inwardly migrating moons, including those that met their demise early in our Solar System's history.

  2. ABC transporter research: going strong 40 years on

    PubMed Central

    Theodoulou, Frederica L.; Kerr, Ian D.

    2015-01-01

    In most organisms, ABC transporters constitute one of the largest families of membrane proteins. In humans, their functions are diverse and underpin numerous key physiological processes, as well as being causative factors in a number of clinically relevant pathologies. Advances in our understanding of these diseases have come about through combinations of genetic and protein biochemical investigations of these transporters and the power of in vitro and in vivo investigations is helping to develop genotype–phenotype understanding. However, the importance of ABC transporter research goes far beyond human biology; microbial ABC transporters are of great interest in terms of understanding virulence and drug resistance and industrial biotechnology researchers are exploring the potential of prokaryotic ABC exporters to increase the capacity of synthetic biology systems. Plant ABC transporters play important roles in transport of hormones, xenobiotics, metals and secondary metabolites, pathogen responses and numerous aspects of development, all of which are important in the global food security area. For 3 days in Chester, this Biochemical Society Focused Meeting brought together researchers with diverse experimental approaches and with different fundamental questions, all of which are linked by the commonality of ABC transporters. PMID:26517919

  3. Synthetic studies on maitotoxin. 1. Stereoselective synthesis of the C'D'E'F'-ring system having a side chain.

    PubMed

    Morita, Masayuki; Ishiyama, Seishi; Koshino, Hiroyuki; Nakata, Tadashi

    2008-05-01

    The stereoselective synthesis of the maitotoxin C'D'E'F'-ring system having a side chain has been accomplished through a convergent strategy. The key reactions include Horner-Wadsworth-Emmons coupling of the C'D'E'-ring and the side chain and subsequent construction of the F'-ring by silane reduction of dihydropyran.

  4. Plasticizer contamination from vacuum system O-rings in a quadrupole ion trap mass spectrometer.

    PubMed

    Verge, Kent M; Agnes, George R

    2002-08-01

    The outgassing of plasticizers from Buna-N and Viton o-rings under vacuum lead to undesired ion-molecule chemistry in an Electrospray Quadrupole Ion Trap Mass Spectrometer. In experiments with the helium bath gas pressure >1.2 mTorr, or whenever analyte ions were stored for >100 ms, extensive loss of analyte ions by proton transfer or adduction with o-ring plasticizers bis(2-ethylhexyl) phthalate and bis(2-ethylhexyl) adipate occurred. A temporary solution to this contamination problem was found to be overnight refluxing in hexane of all the o-rings in the vacuum system. This procedure alleviated this plasticizer contamination for approximately 100 hours of operation. These results, and those that lead to identification of the contamination as plasticizers outgassing from o-rings are described. PMID:12216729

  5. The stability of the oscillation motion of charged grains in the Saturnian ring system

    NASA Astrophysics Data System (ADS)

    Xu, R.-L.; Houpis, L. F.

    1985-02-01

    A perturbation approach for the gravitoelectrodynamic forces encountered in the corotating plasma environment of Saturn is used to determine the stability of charged grains, given a random initial velocity. Attention is given to the implications of the Northrop and Hill (1982) and Mendis et al. (1982) results for the formation of the Saturnian ring system, and it is suggested that the marginal z stability radius at 1.5245 Saturn radii for Kepler-launched particles is due to an erosion process with ejecta of the order 0.05-0.5 microns, rather than that of the previously suggested plasma. The diffuseness of the Saturnian rings beyond the F ring is also explained in terms of instability, while a new critical radius for r instability is suggestd for the optical depth feature at 1.72 Saturn radii. The F ring is analyzed in detail.

  6. Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

    SciTech Connect

    Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei; Morozov, Vasiliy; Rimmer, Robert A.; Wang, Haipeng; Zhang, Yuhong

    2015-09-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

  7. Nature of the attractive interaction between proton acceptors and organic ring systems.

    PubMed

    Arras, Emmanuel; Seitsonen, Ari Paavo; Klappenberger, Florian; Barth, Johannes V

    2012-12-14

    Systematic ab initio calculations are combined with a deconvolution of electrostatic contributions to analyze the interplay between potential hydrogen bond acceptors and organic rings with C(sp(2))-H groups (benzene, pyridine and cyclopentadiene). A distinct anisotropic interaction between the ring systems and the electron lone pairs of cyanide, water and other acceptor species is revealed that favors the in-plane orientation of the proton acceptor group. In the attractive regime this interaction carries a pronounced electrostatic signature. By decomposing the electrostatic contribution into parts attributed to different subunits of the ring systems we demonstrate that a major proportion of the interaction energy gain is originating from the non-adjacent moieties, that are not in close contact with. This behavior holds equally for homocyclic, heterocyclic and non-aromatic rings but contrasts that of the ethyne molecule, taken as reference for a weak hydrogen bond donor clearly exhibiting the expected localized character. The ring interaction requires the presence of π-electron clouds and typically results in an interaction energy gain of 40 to 80 meV. Our findings suggest the proton acceptor-ring interaction as a new category of intermolecular non-covalent interactions.

  8. A pinger system for the Los Alamos Proton Storage Ring

    SciTech Connect

    Hardek, T.W.; Thiessen, H.A.

    1991-01-01

    Developers at the Proton Storage Ring have long desired a modulator and electrode combination capable of kicking the 800-MeV proton beam enough to conduct tune measurements with full intensity beams. At present this has been accomplished by reducing the voltage on one extraction kicker modulator and turning the other off. This method requires that all of the accumulated beam be lost on the walls of the vacuum chamber. In addition to tune measurements a more recent desire is to sweep out beam that may have leaked into the area between bunches. A four-meter electrode has been designed and constructed for the purpose. The design is flexible in that the electrode may be split in the center and rotated in order to provide vertical and horizontal electrodes each 2 meters long. In addition two solid-state pulse modulators that can provide 10kV in burst mode at up to 700 KHz have been purchased. This hardware and its intended use are described. 3 refs., 2 figs., 1 tab.

  9. Are most regular satellites of the Solar System born from massive rings ?

    NASA Astrophysics Data System (ADS)

    Crida, A.; Charnoz, S.

    2012-09-01

    We analytically describe satellite formation from the spreading of a massive ring of solid particles ; beyond the Roche radius, new moons coagulate and migrate outwards because of gravitational instability and the disk's tides. We show that it naturally produces either a satellite system with a specific orbital architecture (that matches the Saturnian, Uranian and Neptunian systems) or only one massive satellite (in the Earth's case). We conclude that Uranus and Neptune, like Saturn, had massive rings in the past, from which their regular satellites formed, and that satellite formation from the spreading of a tidal disk is thus a generic mechanism in the whole Solar System.

  10. Phase behavior of model ABC triblock copolymers

    NASA Astrophysics Data System (ADS)

    Chatterjee, Joon

    The phase behavior of poly(isoprene-b-styrene- b-ethylene oxide) (ISO), a model ABC triblock copolymer has been studied. This class of materials exhibit self-assembly, forming a large array of ordered morphologies at length scales of 5-100 nm. The formation of stable three-dimensionally continuous network morphologies is of special interest in this study. Since these nanostructures considerably impact the material properties, fundamental knowledge for designing ABC systems have high technological importance for realizing applications in the areas of nanofabrication, nanoporous media, separation membranes, drug delivery and high surface area catalysts. A comprehensive framework was developed to describe the phase behavior of the ISO triblock copolymers at weak to intermediate segregation strengths spanning a wide range of composition. Phases were characterized through a combination of characterization techniques, including small angle x-ray scattering, dynamic mechanical spectroscopy, transmission electron microscopy, and birefringence measurements. Combined with previous investigations on ISO, six different stable ordered state symmetries have been identified: lamellae (LAM), Fddd orthorhombic network (O70), double gyroid (Q230), alternating gyroid (Q214), hexagonal (HEX), and body-centered cubic (BCC). The phase map was found to be somewhat asymmetric around the fI = fO isopleth. This work provides a guide for theoretical studies and gives insight into the intricate effects of various parameters on the self-assembly of ABC triblock copolymers. Experimental SAXS data evaluated with a simple scattering intensity model show that local mixing varies continuously across the phase map between states of two- and three-domain segregation. Strategies of blending homopolymers with ISO triblock copolymer were employed for studying the swelling properties of a lamellar state. Results demonstrate that lamellar domains swell or shrink depending upon the type of homopolymer that

  11. Plasma effects in the formation, evolution and present configuration of the Saturnian ring system

    NASA Astrophysics Data System (ADS)

    Alfven, H.; Mendis, D. A.

    The Voyager 1 and 2 observations of the fine structure of the Saturnian ring system demonstrate the importance of electric forces in controlling the dynamics of fine (charged) dust in the rings. A new theory ('gravito-electrodynamics') which combines the electric and the gravitational forces on these grains leads to natural explanations of a number of observed ring phenomena. If plasma processes play a significant role in the dynamics of the ring system at the present time, it is difficult to avoid the conclusion that they also played an important and perhaps crucial role at cosmogonic times during the emplacement and subsequent condensation of the initial dusty plasma. It is suggested that the Saturnian ring system represents a 'time-capsule' containing vital clues about the physical processes operating during the early stages of its formation. It is shown that both its overall structure as well as its fine structure, as determined by Voyagers 1 and 2, indicate the crucial importance of plasma processes in its formation and subsequent evolution.

  12. The ZnuABC high-affinity zinc uptake system and its regulator Zur in Escherichia coli.

    PubMed

    Patzer, S I; Hantke, K

    1998-06-01

    In Escherichia coli, lacZ operon fusions were isolated that were derepressed under iron repletion and repressed under iron depletion. Two fusions were localized in genes that formed an operon whose gene products had characteristics of a binding protein-dependent transport system. The growth defect of these mutants on TY medium containing 5mM EGTA was compensated for by the addition of Zn2+. In the presence of 0.5mM EGTA, only the parental strain was able to take up 65Zn2+. This high-affinity transport was energized by ATP. The genes were named znuACB (for zinc uptake; former name yebLMI) and localized at 42 min on the genetic map of E. coli. At high Zn2+ concentrations, the znu mutants took up more 65Zn2+ than the parental strain. The high-affinity 65Zn2+ uptake was repressed by growth in the presence of 10 microM Zn2+. A znuA-lacZ operon fusion was repressed by 5 microM Zn2+ and showed a more than 20-fold increase in beta-galactosidase activity when Zn2+ was bound to 1.5 microM TPEN [tetrakis-(2-pyridylmethyl) ethylenediamine]. To identify the Zn2+-dependent regulator, constitutive mutants were isolated and tested for complementation by a gene bank of E. coli. A complementing gene, yjbK of the E. coli genome, was identified and named zur (for zinc uptake regulation). The Zur protein showed 27% sequence identity with the iron regulator Fur. High-affinity 65Zn2+ transport of the constitutive zur mutant was 10-fold higher than that of the uninduced parental strain. An in vivo titration assay suggested that Zur binds to the bidirectional promoter region of znuA and znuCB. PMID:9680209

  13. Design for ANL 7 GeV storage ring vacuum system

    SciTech Connect

    Wehrle, R.B.; Nielsen, R.W.

    1988-01-01

    The 7-GeV Advanced Photon Source (APS) design includes a storage ring having a 1060-m circumference with the capability of accommodating 34 insertion devices (ID) and their associated photon beam lines. An additional 35 photon lines can be provided from bending magnets. The vacuum system for the storage ring is designed to maintain a beam-on operating pressure of 1n Torr or less to achieve a positron beam lifetime of approximately 20 hours. The vacuum system and it's current developmental status are described.

  14. Configuration maintaining control of three-body ring tethered system based on thrust compensation

    NASA Astrophysics Data System (ADS)

    Huang, Panfeng; Liu, Binbin; Zhang, Fan

    2016-06-01

    Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

  15. ABCs and AYP Results, Wake County Public School System (WCPSS): 2009-10. Measuring Up. E&R Report No. 10.20

    ERIC Educational Resources Information Center

    Haynie, Glenda

    2011-01-01

    In 2009-10, 92% of WCPSS schools met Expected or High Growth as measured by the North Carolina ABCs program, a 3.5 percentage point increase from 2008-09. Fifty-four percent of the schools made High Growth and 38% made Expected Growth. All subgroups saw their percentages of students meeting growth increase to above 55% in 2009-10; with the…

  16. The Nucleolar Channel System of Human Endometrium Is Related to Endoplasmic Reticulum and R-Rings

    PubMed Central

    Kittur, Nupur; Zapantis, Gregory; Aubuchon, Mira; Santoro, Nanette; Bazett-Jones, David P.

    2007-01-01

    The nucleolar channel system (NCS) is a well-established ultrastructural hallmark of the postovulation endometrium. Its transient presence has been associated with human fertility. Nevertheless, the biogenesis, composition, and function of these intranuclear membrane cisternae are unknown. Membrane systems with a striking ultrastructural resemblance to the NCS, termed R-rings, are induced in nuclei of tissue culture cells by overexpression of the central repeat domain of the nucleolar protein Nopp140. Here we provide a first molecular characterization of the NCS and compare the biogenesis of these two enigmatic organelles. Like the R-rings, the NCS consists of endoplasmic reticulum harboring the marker glucose-6-phosphatase. R-ring formation initiates at the nuclear envelope, apparently by a calcium-mediated Nopp140-membrane interaction, as supported by the calcium-binding ability of Nopp140, the inhibition of R-ring formation by calcium chelators, and the concentration of Nopp140 and complexed calcium in R-rings. Although biogenesis of the NCS may initiate similarly, the reduced presence of complexed calcium and Nopp140 suggests the involvement of additional factors. PMID:17429075

  17. The ABCs of Student Engagement

    ERIC Educational Resources Information Center

    Parsons, Seth A.; Nuland, Leila Richey; Parsons, Allison Ward

    2014-01-01

    Student engagement is an important consideration for teachers and administrators because it is explicitly associated with achievement. What the authors call the ABC's of engagement they outline as: Affective engagement, Behavioral engagement, and Cognitive engagement. They also present "Three Things Every Teacher Needs to Know about…

  18. APOLLO 13: A News Bulletin from ABC

    NASA Technical Reports Server (NTRS)

    1974-01-01

    APOLLO 13: ABC breaks the news of a mishap aboard the spacecraft From the film documentary 'APOLLO 13: 'Houston, We've got a problem'', part of a documentary series on the APOLLO missions made in the early '70's and narrated by Burgess Meredith. APOLO 13 : Third manned lunar landing attempt with James A. Lovell, Jr., John L. Swigert, Jr., and Fred W. Haise, Jr. Pressure lost in SM oxygen system; mission aborted; LM used for life support. Mission Duration 142hrs 54mins 41sec

  19. ABC makes the switch to digital

    NASA Astrophysics Data System (ADS)

    Pearl, R. G.

    1984-05-01

    The digital satellite-distribution system being completed for the ABC radio network is briefly characterized. Audio programming on 19 channels at 15 kHz is digitized at the studio and transmitted by microwave to the uplink facility for distribution via Satcom I-R to 1800 affiliates with affiliate-owned receivers. A data channel comprising several 32-kbit/sec subchannels operates through network-owned data cards and printers installed in the affiliate ground stations to provide internal communication (to all affiliates, a selected group, or a single station) using soft addresses, data-distribution services for station customers, or the proposed 900-MHz nationwide paging service.

  20. SU-E-T-401: Feasibility Study of Using ABC to Gate Lung SBRT Treatment

    SciTech Connect

    Cao, D; Xie, X; Shepard, D

    2014-06-01

    Purpose: The current SBRT treatment techniques include free breathing (FB) SBRT and gated FB SBRT. Gated FB SBRT has smaller target and less lung toxicity with longer treatment time. The recent development of direct connectivity between the ABC and linac allowing for automated beam gating. In this study, we have examined the feasibility of using ABC system to gate the lung SBRT treatment. Methods: A CIRS lung phantom with a 3cm sphere-insert and a moving chest plate was used in this study. Sinusoidal motion was used for the FB pattern. An ABC signal was imported to simulate breath holds. 4D-CT was taken in FB mode and average-intensity-projection (AIP) was used to create FB and 50% gated FB SBRT planning CT. A manually gated 3D CT scan was acquired for ABC gated SBRT planning.An SBRT plan was created for each treatment option. A surface-mapping system was used for 50% gating and ABC system was used for ABC gating. A manually gated CBCT scan was also performed to verify setup. Results: Among three options, the ABC gated plan has the smallest PTV of 35.94cc, which is 35% smaller comparing to that of the FB plan. Consequently, the V20 of the left lung reduced by 15% and 23% comparing to the 50% gated FB and FB plans, respectively. The FB plan took 4.7 minutes to deliver, while the 50% gated FB plan took 18.5 minutes. The ABC gated plan delivery took only 10.6 minutes. A stationary target with 3cm diameter was also obtained from the manually gated CBCT scan. Conclusion: A strategy for ABC gated lung SBRT was developed. ABC gating can significantly reduce the lung toxicity while maintaining the target coverage. Comparing to the 50% gated FB SBRT, ABC gated treatment can also provide less lung toxicity as well as improved delivery efficiency. This research is funded by Elekta.

  1. ABC estimation of unit costs for emergency department services.

    PubMed

    Holmes, R L; Schroeder, R E

    1996-04-01

    Rapid evolution of the health care industry forces managers to make cost-effective decisions. Typical hospital cost accounting systems do not provide emergency department managers with the information needed, but emergency department settings are so complex and dynamic as to make the more accurate activity-based costing (ABC) system prohibitively expensive. Through judicious use of the available traditional cost accounting information and simple computer spreadsheets. managers may approximate the decision-guiding information that would result from the much more costly and time-consuming implementation of ABC. PMID:10156656

  2. Concise copper-catalyzed synthesis of tricyclic biaryl ether-linked aza-heterocyclic ring systems.

    PubMed

    Mestichelli, Paola; Scott, Matthew J; Galloway, Warren R J D; Selwyn, Jamie; Parker, Jeremy S; Spring, David R

    2013-11-01

    A new method for the synthesis of tricyclic biaryl ether-linked ring systems incorporating seven-, eight-, and nine-membered ring amines is presented. In the presence of catalytic quantities of copper(I), readily accessible acyclic precursors undergo an intramolecular carbon-oxygen bond-forming reaction facilitated by a "templating" chelating nitrogen atom. The methodology displays a broad substrate scope, is practical, and generates rare and biologically interesting tricyclic heteroaromatic products that are difficult to access by other means. PMID:24134806

  3. O-ring tube fittings form leakproof seal in hydraulic systems

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Leakproof fittings for hydraulic systems are designed to be welded to the ends of the tubing to be joined and mated to form a seal with one o-ring at the joint. Since the fittings are coupled at only one joint, they tend to be more reliable than standard fittings coupled at two joints.

  4. Diverse N-Heterocyclic Ring Systems via Aza-Heck Cyclizations of N-(Pentafluorobenzoyloxy)sulfonamides

    PubMed Central

    Langer, Thomas; Bower, John F.

    2016-01-01

    Aza-Heck cyclizations initiated by oxidative addition of Pd(0)-catalysts into the N-O bond of N-(pentafluoro-benzoyloxy)sulfonamides are described. These studies, which encompass only the second class of aza-Heck reaction developed to date, provide direct access to diverse N-heterocyclic ring systems. PMID:27460965

  5. Creating an iPhone Application for Collecting Continuous ABC Data

    ERIC Educational Resources Information Center

    Whiting, Seth W.; Dixon, Mark R.

    2012-01-01

    This paper provides an overview and task analysis for creating a continuous ABC data- collection application using Xcode on a Mac computer. Behavior analysts can program an ABC data collection system, complete with a customized list of target clients, antecedents, behaviors, and consequences to be recorded, and have the data automatically sent to…

  6. The ABCs of Activity-Based Costing: A Cost Containment and Reallocation Tool.

    ERIC Educational Resources Information Center

    Turk, Frederick J.

    1992-01-01

    This article describes activity-based costing (ABC) and how this tool may help management understand the costs of major activities and identify possible alternatives. Also discussed are the traditional costing systems used by higher education and ways of applying ABC to higher education. (GLR)

  7. The Role of Activity Based Costing (ABC) in Educational Support Services: A White Paper.

    ERIC Educational Resources Information Center

    Edds, Daniel B.

    Many front-line managers who are assuming more financial responsibility for their organizations find traditional cost accounting inadequate for their needs and are turning to Activity Based Costing (ABC). ABC is not a financial reporting system to serve the needs of regulatory agencies, but a tool that tracks costs from the general ledger…

  8. The upgraded ring loss radiation monitorinng system at the AGS

    SciTech Connect

    Bennett, G.W.; Beadle, E.; Castille, V.; Witkover, R.L.

    1989-01-01

    With the Booster the AGS will accelerate protons to 3 /times/ 10/sup 13/ per cycle, polarized protons at 10/sup 12/, and ions from Carbon to Gold at intensities from 50 to 3 /times/ 10/sup 9/. A loss monitoring system is being developed to facilitate tuning, and to reduce personnel radiation exposure by minimizing residual induced activity and by allowing remote monitoring of activity in the accelerator enclosure. The monitoring system must have a large dynamic range to monitor high intensity beam losses and to measure induced activity down to the level of a few mrad/hour. Various detectors are being evaluated, including ion chambers, proportional counters, and aluminium cathode electronmultipliers. Measurements of the prompt ionization distribution in the median plane at various energies from point targets at two representative locations in the accelerator lattice have been completed. Details of the monitoring system will be presented, as well as the experimental measurements of the prompt radiation field, and a comparable Monte Carlo calculation. 2 refs., 5 figs.

  9. Photometric and spectroscopic evidence for a dense ring system around Centaur Chariklo

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Pinilla-Alonso, N.; Ortiz, J. L.; Alvarez-Candal, A.; Sicardy, B.; Santos-Sanz, P.; Morales, N.; Colazo, C.; Fernández-Valenzuela, E.; Braga-Ribas, F.

    2014-08-01

    Context. A stellar occultation observed on 3rd June 2013 revealed the presence of two dense and narrow rings separated by a small gap around the Centaur object (10 199) Chariklo. The composition of these rings is not known. We suspect that water ice is present in the rings, as is the case for Saturn and other rings around the giant planets. Aims: In this work, we aim to determine if the variability in the absolute magnitude of Chariklo and the temporal variation of the spectral ice feature, even when it disappeared in 2007, can be explained by an icy ring system whose aspect angle changes with time. Methods: We explained the variations on the absolute magnitude of Chariklo and its ring by modeling the light reflected by a system as the one described above. Using X-shooter at VLT, we obtained a new reflectance spectra. We compared this new set of data with the ones available in the literature. We showed how the water ice feature is visible in 2013 in accordance with the ring configuration, which had an opening angle of nearly 34° in 2013. Finally, we also used models of light scattering to fit the visible and near-infrared spectra that shows different characteristics to obtain information on the composition of Chariklo and its rings. Results: We showed that absolute photometry of Chariklo from the literature and new photometric data that we obtained in 2013 can be explained by a ring of particles whose opening angle changes as a function of time. We used the two possible pole solutions for the ring system and found that only one of them, α = 151.30 ± 0.5, δ = 41.48 ± 0.2° (λ = 137.9 ± 0.5, β = 27.7 ± 0.2°), provides the right variation of the aspect angle with time to explain the photometry, whereas the other possible pole solution fails to explain the photometry. From spectral modeling, we derived the composition of the Chariklo surface and that of the rings using the result on the pole solution. Chariklo surface is composed with about 60% of amorphous

  10. Tissue culture system using a PANDA ring resonator and wavelength router for hydroponic plant.

    PubMed

    Kamoldilok, Surachart; Suwanpayak, Nathaporn; Suttirak, Saisudawan; Yupapin, Preecha P

    2012-06-01

    A novel system of nanofluidics trapping and delivery, which is known as a tissue culture system is proposed. By using the intense optical pulse(i.e., a soliton pulse) and a system constructed by a liquid core waveguide, the optical vortices (gradient optical fields/wells) can be generated, where the trapping tools in the same way as the optical tweezers in the PANDA ring resonator can be formed. By controlling the suitable parameters, the intense optical vortices can be generated within the PANDA ring resonator, in which the nanofluidics can be trapped and moved (transported) dynamically within the Tissue culture system(a wavelength router), which can be used for tissue culture and delivery in the hydroponic plant system.

  11. An innovative seismic bracing system based on a superelastic shape memory alloy ring

    NASA Astrophysics Data System (ADS)

    Gao, Nan; Jeon, Jong-Su; Hodgson, Darel E.; DesRoches, Reginald

    2016-05-01

    Shape memory alloys (SMAs) have great potential in seismic applications because of their remarkable superelasticity. Seismic bracing systems based on SMAs can mitigate the damage caused by earthquakes. The current study investigates a bracing system based on an SMA ring which is capable of both re-centering and energy dissipation. This lateral force resisting system is a cross-braced system consisting of an SMA ring and four tension-only cable assemblies, which can be applied to both new construction and seismic retrofit. The performance of this bracing system is examined through a quasi-static cyclic loading test and finite element (FE) analysis. This paper describes the experimental design in detail, discusses the experimental results, compares the performance with other bracing systems based on SMAs, and presents an Abaqus FE model calibrated on the basis of experimental results to simulate the superelastic behavior of the SMA ring. The experimental results indicate that the seismic performance of this system is promising in terms of damping and re-centering. The FE model can be used in the simulation of building structures using the proposed bracing system.

  12. Synthesis of the ABCDEFG ring system of maitotoxin.

    PubMed

    Nicolaou, K C; Aversa, Robert J; Jin, Jian; Rivas, Fatima

    2010-05-19

    Maitotoxin (1) continues to fascinate scientists not only because of its size and potent neurotoxicity but also due to its molecular architecture. To provide further support for its structure and facilitate fragment-based biological studies, we developed an efficient chemical synthesis of the ABCDEFG segment 3 of maitotoxin. (13)C NMR chemical shift comparisons of synthetic 3 with the corresponding values for the same carbons of maitotoxin revealed a close match, providing compelling evidence for the correctness of the originally assigned structure to this polycyclic system of the natural product. The synthetic strategy for the synthesis of 3 relied heavily on our previously developed furan-based technology involving sequential Noyori asymmetric reduction and Achmatowicz rearrangement for the construction of the required tetrahydropyran building blocks, and employed a B-alkyl Suzuki coupling and a Horner-Wadsworth-Emmons olefination to accomplish their assembly and elaboration to the final target molecule. PMID:20415445

  13. Stability Analysis of a Turbocharger Rotor System Supported on Floating Ring Bearings

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Shi, Z. Q.; Zhen, D.; Gu, F. S.; Ball, A. D.

    2012-05-01

    The stability of a turbocharger rotor is governed by the coupling of rotor dynamics and fluid dynamics because the high speed rotor system is supported on a pair of hydrodynamic floating ring bearings which comprise of inner and outer fluid films in series. In order to investigate the stability, this paper has developed a finite element model of the rotor system with consideration of such exciting forces as rotor imbalance, hydrodynamic fluid forces, lubricant feed pressure and dead weight. The dimensionless analytical expression of nonlinear oil film forces in floating ring bearings have been derived on the basis of short bearing theory. Based on numerical simulation, the effects of rotor imbalance, lubricant viscosity, lubricant feed pressure and bearing clearances on the stability of turbocharger rotor system have been studied. The disciplines of the stability of two films and dynamic performances of rotor system have been provided.

  14. Role of an ABC importer in mycobacterial drug resistance.

    PubMed

    Chakraborti, P K; Bhatt, K; Banerjee, S K; Misra, P

    1999-08-01

    Phosphate specific transporter (Pst) in bacteria is involved in phosphate transport. Pst is a multisubunit system which belongs to the ABC family of transporters. The import function of this transporter is known to be operative at media phosphate concentrations below the millimolar range. However, we found amplification of this transporter in a laboratory generated ciprofloxacin resistant Mycobacterium smegmatis colony (CIPr) which was grown in a condition when phosphate scavenging function of this operon was inoperative. Our results therefore argue the role of this ABC importer in conferring high level of fluoroquinolone resistance in CIPr.

  15. Pressurized balanced sealing system for use on the ring-liner interface of a coal fired diesel engine

    SciTech Connect

    Leonard, G.L.

    1989-03-14

    A system for minimizing a wear to a reciprocating internal combustion engine is described, consisting of a cylinder having a wall and a combustion chamber within the cylinder; a piston movable in a stroke within the cylinder between a top dead center position and a bottom dead center position, the piston having first and second ends, the first end being adjacent to the combustion chamber and the second end being remote from the combustion chamber; first, second, and third piston rings extending around the piston, the second piston ring being positioned between the first and the third piston rings; a ring pack area on the piston between the first piston ring and the second piston ring; a lubricant blowby area between the second piston ring and the third piston ring; and a pump communicating with an inlet in the wall such that the lubricant blowby area registers with the inlet during at least part of the stroke of the piston, the pump having an outlet in the wall such that the ring pack area registers with the outlet during at least part of the stroke of the piston, the pump operable to draw lubricant from the lubricant blowby area and provide lubricant to the ring pack area.

  16. Formation of regular satellites from ancient massive rings in the solar system.

    PubMed

    Crida, A; Charnoz, S

    2012-11-30

    When a planetary tidal disk--like Saturn's rings--spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn's, Uranus', and Neptune's satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems. PMID:23197530

  17. Formation of regular satellites from ancient massive rings in the solar system.

    PubMed

    Crida, A; Charnoz, S

    2012-11-30

    When a planetary tidal disk--like Saturn's rings--spreads beyond the Roche radius (inside which planetary tides prevent aggregation), satellites form and migrate away. Here, we show that most regular satellites in the solar system probably formed in this way. According to our analytical model, when the spreading is slow, a retinue of satellites appear with masses increasing with distance to the Roche radius, in excellent agreement with Saturn's, Uranus', and Neptune's satellite systems. This suggests that Uranus and Neptune used to have massive rings that disappeared to give birth to most of their regular satellites. When the spreading is fast, only one large satellite forms, as was the case for Pluto and Earth. This conceptually bridges the gap between terrestrial and giant planet systems.

  18. Controllable multiple-quantum transitions in a T-shaped small quantum dot-ring system

    NASA Astrophysics Data System (ADS)

    Chen, Xiongwen; Chen, Baoju; Song, Kehui; Zhou, Guanghui

    2016-05-01

    Based on the tight-binding model and the slave boson mean field approximation, we investigate the electron transport properties in a small quantum dot (QD)-ring system. Namely, a strongly correlated QD not only attaches directly to two normal metallic electrodes, but also forms a magnetic control Aharonov-Bohm quantum ring with a few noninteracting QDs. We show that the parity effect, the Kondo effect, and the multiple Fano effects coexist in our system. Moreover, the parities, defined by the odd- and even-numbered energy levels in this system, can be switched by adjusting magnetic flux phase ϕ located at the center of the quantum ring, which induces multiple controllable Fano-interference energy pathways. Therefore, the constructive and destructive multi-Fano interference transition, the Kondo and Fano resonance transition at the Fermi level, the Fano resonance and ani-resonance transition are realized in the even parity system. They can also be observed in the odd parity system when one adjusts the phase ϕ and the gate voltage Vg applied to the noninteracting QDs. The multi-quantum transitions determine some interesting transport properties such as the current switch and its multi-flatsteps, the differential conductance switch at zero bias voltage and its oscillation or quantization at the low bias voltage. These results may be useful for the observation of multiple quantum effect interplays experimentally and the design of controllable QD-based device.

  19. Multidrug-Resistance Transporter AbcA Secretes Staphylococcus aureus Cytolytic Toxins.

    PubMed

    Yoshikai, Hirono; Kizaki, Hayato; Saito, Yuki; Omae, Yosuke; Sekimizu, Kazuhisa; Kaito, Chikara

    2016-01-15

    Phenol-soluble modulins (PSMs) are Staphylococcus aureus cytolytic toxins that lyse erythrocytes and neutrophils and have important functions in the S. aureus infectious process. The molecular mechanisms of PSM secretion, however, are not well understood. Here we report that knockout of the multidrug-resistance ABC transporter AbcA, which contributes to S. aureus resistance against antibiotics and chemicals, diminished the secreted amount of PSM, leading to the accumulation of PSM in the intracellular fraction. The amount of PSM in the culture supernatants of the abcA knockout mutants was restored by introduction of the wild-type abcA gene, whereas it was not completely restored by introduction of mutant abcA genes encoding AbcA mutant proteins carrying amino acid substitutions in the adenosine triphosphate binding motifs. The abcA knockout mutant exhibited attenuated virulence in a mouse systemic infection model. These findings suggest that the multidrug resistance transporter AbcA secretes PSMs and contributes to S. aureus virulence.

  20. Multidrug-Resistance Transporter AbcA Secretes Staphylococcus aureus Cytolytic Toxins.

    PubMed

    Yoshikai, Hirono; Kizaki, Hayato; Saito, Yuki; Omae, Yosuke; Sekimizu, Kazuhisa; Kaito, Chikara

    2016-01-15

    Phenol-soluble modulins (PSMs) are Staphylococcus aureus cytolytic toxins that lyse erythrocytes and neutrophils and have important functions in the S. aureus infectious process. The molecular mechanisms of PSM secretion, however, are not well understood. Here we report that knockout of the multidrug-resistance ABC transporter AbcA, which contributes to S. aureus resistance against antibiotics and chemicals, diminished the secreted amount of PSM, leading to the accumulation of PSM in the intracellular fraction. The amount of PSM in the culture supernatants of the abcA knockout mutants was restored by introduction of the wild-type abcA gene, whereas it was not completely restored by introduction of mutant abcA genes encoding AbcA mutant proteins carrying amino acid substitutions in the adenosine triphosphate binding motifs. The abcA knockout mutant exhibited attenuated virulence in a mouse systemic infection model. These findings suggest that the multidrug resistance transporter AbcA secretes PSMs and contributes to S. aureus virulence. PMID:26160745

  1. The Value of Green Technology at ABC Community College

    ERIC Educational Resources Information Center

    McAllister, Bernadette

    2012-01-01

    A challenge facing community colleges nationwide is to reduce the carbon footprint of campuses by initiating green technology initiatives. This case study assessed the effect of switching from paper assignments to a learning management system at ABC Community College. The topic is important because federal and state funding, as well as…

  2. Mapping the functional yeast ABC transporter interactome

    PubMed Central

    Snider, Jamie; Hanif, Asad; Lee, Mid Eum; Jin, Ke; Yu, Analyn R.; Graham, Chris; Chuk, Matthew; Damjanovic, Dunja; Wierzbicka, Marta; Tang, Priscilla; Balderes, Dina; Wong, Victoria; Jessulat, Matthew; Darowski, Katelyn D.; Luis, Bryan-Joseph San; Shevelev, Igor; Sturley, Stephen L; Boone, Charles; Greenblatt, Jack F.; Zhang, Zhaolei; Paumi, Christian M.; Babu, Mohan; Park, Hay-Oak; Michaelis, Susan; Stagljar, Igor

    2013-01-01

    ABC transporters are a ubiquitous class of integral membrane proteins of immense clinical interest because of their strong association with human disease and pharmacology. To improve our understanding of these proteins, we used Membrane Yeast Two-Hybrid (MYTH) technology to map the protein interactome of all non-mitochondrial ABC transporters in the model organism Saccharomy cescerevisiae, and combined this data with previously reported yeast ABC transporter interactions in the BioGRID database to generate a comprehensive, integrated interactome. We show that ABC transporters physically associate with proteins involved in a surprisingly diverse range of functions. We specifically examine the importance of the physical interactions of ABC transporters in both the regulation of one another and in the modulation of proteins involved in zinc homeostasis. The interaction network presented here will be a powerful resource for increasing our fundamental understanding of the cellular role and regulation of ABC transporters. PMID:23831759

  3. Position and rotation-invariant pattern recognition system by binary rings masks

    NASA Astrophysics Data System (ADS)

    Solorza, S.; Álvarez-Borrego, J.

    2015-06-01

    In this paper, algorithms invariant to position, rotation, noise and non-homogeneous illumination are presented. Here, several manners are studied to generate binary rings mask filters and the corresponding signatures associated to each image. Also, in this work it is shown that digital systems, which are based on the ?-law non-linear correlation, are ?-invariant for ?. The methodologies are tested using greyscale fossil diatoms digital images (real images), and considering the great similarity between those images the results obtained are excellent. The box plot statistical analysis and the computational cost times yield that the Bessel rings masks are the best option when the images contain a homogeneous illumination and the Fourier masks digital system is the right selection when the non-homogeneous illumination and noise is presented in the images.

  4. COMPUTATIONAL BEAM DYNAMICS STUDIES FOR IMPROVING THE RING INJECTION AND EXTRACTION SYSTEMS IN SNS

    SciTech Connect

    Holmes, Jeffrey A; Cousineau, Sarah M; Plum, Michael A; Wang, Jian-Guang

    2008-01-01

    The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated ongoing study and development by a multidisciplinary team. Results already include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertent introduction of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

  5. Performance of the RF bunch coalescing system in the Fermilab main ring

    SciTech Connect

    Martin, P.; Meisner, K.; Miller, H.; Nicholls, G.; Wildman, D.

    1985-10-01

    Both the proton and antiproton bunches which will collide in the Tevatron have longitudinal emittance greater than can be accelerated by the Main Ring from 8 GeV without large loss and emittance growth. To circumvent this restriction, several bunches of smaller intensity are accelerated in the Main Ring to an energy of 150 GeV where these bunches are coalesced into a single high-intensity bunch. Coalescing has possible uses in other applications. Applications could be any time that a beam which has been accelerated by an rf system of one frequency must be captured by another rf frequency. The bunch coalescing system is described and some preliminary coalescing results are shown.

  6. Hepatopancreatic arterial ring: bilateral symmetric typology in human celiaco-mesenteric arterial system.

    PubMed

    Kosaka, Motohiro; Horiuchi, Kanji; Nishida, Keiichiro; Taguchi, Takehito; Murakami, Takuro; Ohtsuka, Aiji

    2002-10-01

    The celiac and mesenteric arterial system including the left gastric, splenic, common hepatic, and superior mesenteric arteries shows various types of origins, courses, ramifications and anastomoses. In order to explain the various expressions of this system, we have proposed a typological model, in which celiacomesenteric arteries develop as paired or bilaterally symmetrical primordial vessels originated from the anterior aspect of the aorta, and these vessels anastomose each other with longitudinal and horizontal pathways. Here, we report 3 unusual cases characterized by arterial rings, formed by the left gastric, left accessory hepatic, proper hepatic, anterior pancreaticoduodenal, and dorsal pancreatic arteries. The dorsal pancreatic and anterior pancreaticoduodenal arteries are located to the right and left of the embryonic pancreas developing in the dorsal mesentery, respectively. Such hepatopancreatic arterial rings simultaneously containing right and left elements can only be explained using our typological model, in which the concept of paired arteries or bilateral symmetry is introduced. PMID:12530508

  7. Overall design concepts for the APS storage ring machine protection system

    SciTech Connect

    Lumpkin, A.; Fuja, R.; Votaw, A.; Wang, X.; Shu, D.; Stepp, J.; Arnold, N.; Nawrocki, G.; Decker, G.; Chung, Y.

    1995-07-01

    The basic design and status of the machine protection system for the Advanced Photon Source (APS) storage ring are discussed. The machine is passively safe to the bending magnet sources, but the high power of the insertion devices requires missteering conditions to be identified and the beam aborted in less than one millisecond. The basic aspects of waterflow, temperature, beam position, etc. monitoring are addressed. Initial commissioning of subsystems and sensors is statused.

  8. Bioinformatic survey of ABC transporters in dermatophytes.

    PubMed

    Gadzalski, Marek; Ciesielska, Anita; Stączek, Paweł

    2016-01-15

    ATP binding cassette (ABC) transporters constitute a very large and ubiquitous superfamily of membrane proteins. They are responsible for ATP hydrolysis driven translocation of countless substrates. Being a very old and diverse group of proteins present in all organisms they share a common feature, which is the presence of an evolutionary conservative nucleotide binding domain (NBD)--the engine that drives the transport. Another common domain is a transmembrane domain (TMD) which consists of several membrane-spanning helices. This part of protein is substrate-specific, thus it is much more variable. ABC transporters are known for driving drug efflux in many pathogens and cancer cells, therefore they are the subject of extensive studies. There are many examples of conferring a drug resistance phenotype in fungal pathogens by ABC transporters, however, little is known about these proteins in dermatophytes--a group of fungi causing superficial mycoses. So far only a single ABC transporter has been extensively studied in this group of pathogens. We analyzed available genomic sequences of seven dermatophyte species in order to provide an insight into dermatophyte ABC protein inventory. Phylogenetic studies of ABC transporter genes and their products were conducted and included ABC transporters of other fungi. Our results show that each dermatophyte genome studied possesses a great variety of ABC transporter genes. Detailed analysis of selected genes and their products indicates that relatively recent duplication of ABC transporter genes could lead to novel substrate specificity. PMID:26524502

  9. Conceptual design of the vaccum system for the 6 GeV storage ring

    SciTech Connect

    Be, S.H.; Morimoto, Y.; Sakamoto, H.; Yokouchi, S.

    1988-09-30

    Preliminary design results for the vacuum system of the 6 GeV storage ring which is being planned at RIKEN, are presented. The vacuum system is designed to maintain a beam-on operating pressure of 1 x 10/sup 10/ Torr. This report places special emphasis on the new vacuum chamber whose antechamber is with two isolated-pump chambers, and pumping system. The distribution of the synchrotron radiation depositions at the absorber or within the vacuum chambers is discussed. Finally the new type of a crotch absorber is briefly described.

  10. Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

    SciTech Connect

    Gao, F.; Rose, J.; Cupolo, J.; Dilgen, T.; Rose, B.; Gash, W.; Ravindranath, V.; Yeddulla, M.; Papu, J.; Davila, P.; Holub, B.; Tagger, J.; Sikora, R.; Ramirez, G.; Kulpin, J.

    2015-05-03

    The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

  11. Monitor and control systems for the SLD Cherenkov Ring Imaging Detector

    SciTech Connect

    Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dunwoodie, W.; Fernandez, F.; Hallewell, G.; Kawahara, H.; Korff, P.; Kwon, Y.; Leith, D.; Muller, D.; Nagamine, T.; Pavel, T.; Rabinowitz, L.; Ratcliff, B.; Rensing, P.; Schultz, D.; Shapiro, S.; Simopoulos, C.; Solodov, E.; Toge, N.; Va'Vra, J.; Williams, S.; Whitaker, J.; Wilson, R.J.; Bean, A.; Caldwell, D.; Duboscq, J.; Huber, J.; Lu, A.; McHugh, S.; Mathys, L.; Morriso

    1989-10-01

    To help ensure the stable long-term operation of a Cherenkov Ring Detector at high efficiency, a comprehensive monitor and control system is being developed. This system will continuously monitor and maintain the correct operating temperatures, and will provide an on-line monitor and maintain the correct operating temperatures, and will provide an on-line monitor of the pressures, flows, mixing, and purity of the various fluids. In addition the velocities and trajectories of Cherenkov photoelectrons drifting within the imaging chambers will be measured using a pulsed uv lamp and a fiberoptic light injection system. 9 refs., 6 figs.

  12. An active feedback system to control synchrotron oscillations in the SLC Damping Rings

    SciTech Connect

    Corredoura, P.L.; Pellegrin, J.L.; Schwarz, H.D.; Sheppard, J.C.

    1989-03-01

    Initially the SLC Damping Rings accomplished Robinson instability damping by operating the RF accelerating cavities slightly detuned. In order to be able to run the cavities tuned and achieve damping for Robinson instability and synchrotron oscillations at injection an active feedback system has been developed. This paper describes the theoretical basis for the feedback system and the development of the hardware. Extensive measurements of the loop response including stored beam were performed. Overall performance of the system is also reported. 3 refs., 6 figs.

  13. The micro-optical ring electrode. 3: Transient photocurrent studies of photophysical-electrochemical and photophysical-chemical-electrochemical systems.

    PubMed

    Andrieux, Fabrice P L; Boxall, Colin; O'hare, Danny

    2006-08-17

    The micro-optical ring electrode (MORE) is a photoelectrochemical device based on a ring microelectrode that uses the insulating material interior to the ring electrode as a light guide. In this paper, we describe the preparation and characterization of very thin ring MOREs with (ring inner radius)/(ring outer radius) > 0.99. Theoretically, we derive asymptotic analytical expressions for the time dependence of the diffusion-limited transient light-on photocurrent generated by two general types of photoelectrochemical systems: (a) the PE (photophysical-electrochemical) system, wherein the photoexcited species itself is directly detected on the ring; (b) the PCE (photophysical-chemical-electrochemical) system, wherein the photoexcited species undergoes a homogeneous electron transfer reaction prior to electrochemical detection. Experimentally, we establish that it is possible to use such MOREs to study the wavelength dependence of photocurrents derived from photoelectrochemically active systems, such as the Ru(bipy)3 2+/Fe3+ PCE system, demonstrating the potential utility of the MORE as a selective electroanalytical probe. We also use our expressions for the time dependence of photocurrents at the MORE to derive values for the photoelectrochemical kinetic parameters of this system, including the rate coefficient for the back reaction of photogenerated Ru(bipy)3 3+ (0.115 s(-1)) and the quantum efficiency for the primary redox products, Ru(bipy)3 3+ and Fe2+, escaping cage recombination, phi(CE) = 0.099.

  14. Facile Synthesis of Novel Polyethylene-Based A-B-C Block Copolymers Containing Poly(methyl methacrylate) Using a Living Polymerization System.

    PubMed

    Song, Xiangyang; Ma, Qiong; Cai, Zhengguo; Tanaka, Ryo; Shiono, Takeshi; Grubbs, Robert B

    2016-02-01

    Ethylene-propylene-methyl methacrylate (MMA) and ethylene-hexene-MMA A-B-C block copolymers with high molecular weight (>100,000) are synthesized using fluorenylamide-ligated titanium complex activated by modified methylaluminoxane and 2,6-di-tert-butyl-4-methylphenol for the first time. After diblock copolymerization of olefin is conducted completely, MMA is added and activated by aluminum Lewis acid to promote anionic polymerization. The length of polyolefin and poly (methyl methacrylate) (PMMA) is controllable precisely by the change of the additive amount of olefin and polymerization time, respectively. A soft amorphous polypropylene or polyhexene segment is located between two hard segments of semicrystalline polyethylene and glassy PMMA blocks.

  15. Improved temperature regulation of process water systems for the APS storage ring.

    SciTech Connect

    Putnam, C.; Dortwegt, R.

    2002-10-10

    Beam stability and operational reliability of critical mechanical systems are key performance issues for synchrotron accelerators such as the Advanced Photon Source (APS). Stability is influenced by temperature fluctuations of the process water (PW) used for cooling and/or temperature conditioning storage ring (SR) components such as vacuum chambers, magnets, absorbers, etc. Operational reliability is crucial in maintaining facility beam operations and remaining within downtime ''budgets.'' Water systems for the APS storage ring were originally provided with a distributive control system (DCS) capable of regulation to {+-}1.0 F, as specified by facility design requirements. After several years of operation, a particular mode of component mortality indicated a need for upgrade of the temperature control system. The upgrade that was implemented was chosen for both improved component reliability and temperature stability (now on the order of {+-}0.2 F for copper components and {+-}0.05 F for aluminum components). The design employs a network of programmable logic controllers (PLCs) for temperature control that functions under supervision of the existing DCS. The human-machine interface (HMI) of the PLC system employs RSView32 software. The PLC system also interfaces with the EPICS accelerator control system to provide monitoring of temperature control parameters. Eventual supervision of the PLC system by EPICS is possible with this design.

  16. James Webb Space Telescope Observations of Stellar Occultations by Solar System Bodies and Rings

    NASA Astrophysics Data System (ADS)

    Santos-Sanz, P.; French, R. G.; Pinilla-Alonso, N.; Stansberry, J.; Lin, Z.-Y.; Zhang, Z.-W.; Vilenius, E.; Müller, Th.; Ortiz, J. L.; Braga-Ribas, F.; Bosh, A.; Duffard, R.; Lellouch, E.; Tancredi, G.; Young, L.; Milam, Stefanie N.; the JWST “Occultations” Focus Group

    2016-01-01

    In this paper, we investigate the opportunities provided by the James Webb Space Telescope (JWST) for significant scientific advances in the study of Solar System bodies and rings using stellar occultations. The strengths and weaknesses of the stellar occultation technique are evaluated in light of JWST's unique capabilities. We identify several possible JWST occultation events by minor bodies and rings and evaluate their potential scientific value. These predictions depend critically on accurate a priori knowledge of the orbit of JWST near the Sun-Earth Lagrange point 2 (L2). We also explore the possibility of serendipitous stellar occultations by very small minor bodies as a byproduct of other JWST observing programs. Finally, to optimize the potential scientific return of stellar occultation observations, we identify several characteristics of JWST's orbit and instrumentation that should be taken into account during JWST's development.

  17. Pharmacophore generation of 2-substituted benzothiazoles as AdeABC efflux pump inhibitors in A. baumannii.

    PubMed

    Yilmaz, S; Altinkanat-Gelmez, G; Bolelli, K; Guneser-Merdan, D; Over-Hasdemir, M U; Yildiz, I; Aki-Yalcin, E; Yalcin, I

    2014-01-01

    RND family efflux pumps are important for multidrug resistance in Gram-negative bacteria. To date no efflux pump inhibitors for clinical use have been found, so developing the specific inhibitors of this pump system will be beneficial for the treatment of infections caused by these multidrug-resistant pathogens. A set of BSN-coded 2-substituted benzothiazoles were tested alone and in combination with ciprofloxacin (CIP) against the RND family efflux pump AdeABC overexpressor Acinetobacter baumannii SbMox-2 strain. The results indicated that the BSN compounds did not have antimicrobial activity when tested alone. However, if they were applied in combination with CIP, it was observed that the antibiotic had antimicrobial activity against the tested pathogen, possessing a minimum inhibitory concentration value that could be utilized in clinical treatment. A 3D-common features pharmacophore model was applied by using the HipHop method and the generated pharmacophore hypothesis revealed that the hydrogen bond acceptor property of nitrogen in the thiazole ring and the oxygen of the amide substituted at the second position of the benzothiazole ring system were significant for binding to the target protein. Moreover, three hydrophobic aromatic features were found to be essential for inhibitory activity. PMID:24905472

  18. Pharmacophore generation of 2-substituted benzothiazoles as AdeABC efflux pump inhibitors in A. baumannii.

    PubMed

    Yilmaz, S; Altinkanat-Gelmez, G; Bolelli, K; Guneser-Merdan, D; Over-Hasdemir, M U; Yildiz, I; Aki-Yalcin, E; Yalcin, I

    2014-01-01

    RND family efflux pumps are important for multidrug resistance in Gram-negative bacteria. To date no efflux pump inhibitors for clinical use have been found, so developing the specific inhibitors of this pump system will be beneficial for the treatment of infections caused by these multidrug-resistant pathogens. A set of BSN-coded 2-substituted benzothiazoles were tested alone and in combination with ciprofloxacin (CIP) against the RND family efflux pump AdeABC overexpressor Acinetobacter baumannii SbMox-2 strain. The results indicated that the BSN compounds did not have antimicrobial activity when tested alone. However, if they were applied in combination with CIP, it was observed that the antibiotic had antimicrobial activity against the tested pathogen, possessing a minimum inhibitory concentration value that could be utilized in clinical treatment. A 3D-common features pharmacophore model was applied by using the HipHop method and the generated pharmacophore hypothesis revealed that the hydrogen bond acceptor property of nitrogen in the thiazole ring and the oxygen of the amide substituted at the second position of the benzothiazole ring system were significant for binding to the target protein. Moreover, three hydrophobic aromatic features were found to be essential for inhibitory activity.

  19. Simulation and analysis of rf feedback systems on the SLC damping rings

    SciTech Connect

    Minty, M.; Himel, T.; Krejcik, P.; Siemann, R.H.; Tighe, R.

    1993-09-01

    The rf system of the SLC Damping Rings has evolved since tighter tolerances on beam stability are encountered as beam intensities are increased. There are now many feedback systems controlling the phase and amplitude of the rf, the phase of the beam, and the tune of the cavity. The bandwidths of the feedback loops range from several MHz to compensate for beam loading to a few Hz for the cavity tuners. To improve our understanding of the interaction of these loops and verify the expected behavior, we have simulated their behavior using computer models. A description of the models and the first results are discussed.

  20. Conceptual Design of ILC Damping Ring Wiggler Straight VacuumSystem

    SciTech Connect

    Marks, S.; Kennedy, K.; Plate, D.; Schlueter, R.D.; Zisman, M.

    2007-06-22

    The positron and electron damping rings for the International Linear Collider will contain long straight sections consisting of twenty wiggler/quadrupole pairs. The wigglers will be based upon the CESR superconducting design. There are a number of challenges associated with the design of the wiggler straight vacuum system, in particular, the absorption of photon power generated by the wigglers. This paper will present the overall conceptual design of the wiggler straight vacuum system developed for the ILC Reference Design Report. Particular emphasis will be placed on photon power load calculations and the absorber design.

  1. The fluid systems for the SLD Cherenkov ring imaging detector. [01

    SciTech Connect

    Abe, K.; Hasegawa, K.; Hasegawa, Y.; Iwasaki, Y.; Suekane, F.; Yuta, H. . Dept. of Physics); Antilogus, P.; Aston, D.; Bienz, T.; Bird, F.; Dasu, S.; Dolinsky, S.; Dunwoodie, W.; Hallewell, G.; Kawahara, H.; Kwon, Y.; Leith, D.W.G.S.; McCulloch, M.; McShurley, D.; Mueller, G.; Muller, D.; Nagamine, T.; Pavel, T.J.; Peterson, H.; Ratcliff, B.; Reif, R.; Rensing, P.; Schultz, D.; Shapiro, S.; Shaw,

    1992-10-01

    We describe the design and operation of the fluid delivery, monitor and control systems for the SLD barrel Cherenkov Ring Imaging Detector (CRID). The systems deliver drift gas (C[sub 2]H[sub 6] + TMAE), radiator gas (C[sub 5]F[sub 12] + N[sub 2]) and radiator liquid (C[sub 6]F[sub 14]). Measured critical quantities such as electron lifetime in the drift gas and ultra-violet (UV) transparencies of the radiator fluids, together with the operational experience, are also reported.

  2. Photocatalytic Systems with Flavinium Salts: From Photolyase Models to Synthetic Tool for Cyclobutane Ring Opening.

    PubMed

    Hartman, Tomáš; Cibulka, Radek

    2016-08-01

    Two new photocatalytic systems based on flavinium species formed in situ by protonation of riboflavin-tetraacetate (1) with triflic acid or prepared in advance via alloxazine quaternization are presented as effective tools for oxidative cyclobutane ring [2 + 2] cycloreversion using visible light. The system with 1,3-dimethyl-8-trifluoromethylalloxazinium perchlorate (2c) was found to be superior allowing an acid-free mild procedure, which results in the opening of cyclobutanes with high oxidation potential (up to 2.14 V) and/or with sensitive groups (e.g., furan) without side reactions. PMID:27415962

  3. The vacuum system for the PEP II high energy ring straight sections

    SciTech Connect

    Wienands, U.; Daly, E.; Kulikov, A.; Kurita, N.; Nordby, M.; Perkins, C.; Reuter, E.; Seeman, J. T.

    1995-01-01

    The six straight sections of the PEP II High Energy Ring (HER) serve various functions: lattice tuning, beam injection and abort, providing space for rf cavities, longitudinal and transverse feedback, beam diagnostics and the interaction point. A stainless steel vacuum system has been designed; prototypes are currently being built. Cooling is required due to radiation coming from the last arc dipole and resistive losses in the vacuum chamber. Although the nominal beam current of the HER is 1 A the vacuum system is designed for 3 A to provide margin and an upgrade path. 5 refs., 7 figs.

  4. Ballistic transport in planetary ring systems due to particle erosion mechanisms. I - Theory, numerical methods, and illustrative examples

    NASA Astrophysics Data System (ADS)

    Durisen, R. H.; Cramer, N. L.; Murphy, B. W.; Cuzzi, J. N.; Mullikin, T. L.; Cederbloom, S. E.

    1989-07-01

    Ballistic transport, defined as the net radial transport of mass and angular momentum due to exchanges of meteoroid hypersonic-impact ejecta by neighboring planetary ring regions on time-scales orders-of-magnitude shorter than the age of the solar system, is presently considered as a problem in mathematical physics. The preliminary results of a numerical scheme for following the combined effects of ballistic transport and viscous diffusion demonstrate that ballistic transport generates structure near sharp edges already present in the ring-mass distribution; the entire ring system ultimately develops an undulatory structure whose length scale is typically of the order of the radial excursion of the impact ejecta.

  5. Saturn's seasonal winds and temperature: The effect of the ring system on the troposphere and stratosphere

    SciTech Connect

    Barnet, C.D.

    1990-01-01

    The radiative properties of Saturn's rings (insolation shadowing, insolation scattering, and thermal emission) were incorporated into a seasonal, zonally-averaged, radiative-dynamical model to investigate the magnitude of small seasonal fluctuations in the troposphere and stratosphere of Saturn. Although the radiative time constant is large in Saturn's troposphere and stratosphere, the rings induce significant latitudinal insolation gradients resulting in potential disturbances in the upper stratosphere. The results of the model are compared to the Pioneer and Voyager Radio Sub-System (RSS) vertical temperature profile measurements and to the Voyager Infrared Interferometric Spectrometer (IRIS) latitudinal temperature profile measurements. In the upper stratosphere (1 to 30 mBar) the heating is dominated by methane and the model can be directly compared to the Voyager data. Below the temperature minimum the radiative time constant is sufficiently long to strongly dampen seasonal variations, however, the temperature excursions seen in the IRIS data are significantly larger than those predicted by the radiative model. The thermal effects of the strong Saturnian zonal winds are simulated with a first-order dynamical model to provide some insight into the lower boundary conditions. The remaining differences between the model and the Voyager IRIS data-sets are used to estimate the quantity of aerosol required near the tropopause region. The magnitudes of the wind and temperature perturbations, caused by the radiative effects of Saturn's rings, are discussed in the context of the future Hubble Space Telescope and the planned Cassini Saturnian Orbiter missions.

  6. The terminal Eocene event - Formation of a ring system around the earth

    NASA Technical Reports Server (NTRS)

    Okeefe, J. A.

    1980-01-01

    It is suggested that the formation of a ring system about the earth by particles and debris related to the North American strewn tektite field is responsible for the terminal Eocene event of 34 million years ago, in which severe climatic changes accompanied by widespread biological extinctions occurred. Botanical data is cited which implies a 20-C decrease in winter temperature with no change in summer temperature, and evidence of the correlation of the North American tektite fall, which is estimated to have a total mass of 10 to the 9th to 10 to the 10th tons, with the disappearance of five of the most abundant species of radiolaria is presented. The possible connection between the tektites and climatic change is argued to result from the screening of sunlight by an equatorial ring of trapped particles of extraterrestrial origin in geocentric orbit which would cut off sunlight only in the winter months. Such a ring, located at a distance of between 1.5 and 2.5 earth radii (the Roche limit) is estimated to have a lifetime of a few million years.

  7. A Performance Comparison of Tree and Ring Topologies in Distributed System

    SciTech Connect

    Huang, Min

    2004-01-01

    A distributed system is a collection of computers that are connected via a communication network. Distributed systems have become commonplace due to the wide availability of low-cost, high performance computers and network devices. However, the management infrastructure often does not scale well when distributed systems get very large. Some of the considerations in building a distributed system are the choice of the network topology and the method used to construct the distributed system so as to optimize the scalability and reliability of the system, lower the cost of linking nodes together and minimize the message delay in transmission, and simplify system resource management. We have developed a new distributed management system that is able to handle the dynamic increase of system size, detect and recover the unexpected failure of system services, and manage system resources. The topologies used in the system are the tree-structured network and the ring-structured network. This thesis presents the research background, system components, design, implementation, experiment results and the conclusions of our work. The thesis is organized as follows: the research background is presented in chapter 1. Chapter 2 describes the system components, including the different node types and different connection types used in the system. In chapter 3, we describe the message types and message formats in the system. We discuss the system design and implementation in chapter 4. In chapter 5, we present the test environment and results, Finally, we conclude with a summary and describe our future work in chapter 6.

  8. Affinity-based release of chondroitinase ABC from a modified methylcellulose hydrogel.

    PubMed

    Pakulska, Malgosia M; Vulic, Katarina; Shoichet, Molly S

    2013-10-10

    Chondroitinase ABC (ChABC) is a promising therapeutic for spinal cord injury as it can degrade the glial scar that is detrimental to regrowth and repair. However, the sustained delivery of bioactive ChABC is a challenge requiring highly invasive methods such as intra-spinal injections, insertion of intrathecal catheters, or implantation of delivery vehicles directly into the tissue. ChABC is thermally unstable, further complicating its delivery. Moreover, there are no commercial antibodies available for its detection. To achieve controlled release, we designed an affinity-based system that sustained the release of bioactive ChABC for at least 7days. ChABC was recombinantly expressed as a fusion protein with Src homology domain 3 (SH3) with an N-terminal histidine (HIS) tag and a C-terminal FLAG tag (ChABC-SH3). Protein purification was achieved using a nickel affinity column and, for the first time, direct quantification of ChABC down to 0.1nM was attained using an in-house HIS/FLAG double tag ELISA. The release of active ChABC-SH3 was sustained from a methylcellulose hydrogel covalently modified with an SH3 binding peptide. The rate of release was tunable by varying either the binding strength of the SH3-protein/SH3-peptide pair or the SH3-peptide to SH3-protein ratio. This innovative system has the potential to be used as a platform technology for the release and detection of other proteins that can be expressed using a similar construct.

  9. Affinity-based release of chondroitinase ABC from a modified methylcellulose hydrogel.

    PubMed

    Pakulska, Malgosia M; Vulic, Katarina; Shoichet, Molly S

    2013-10-10

    Chondroitinase ABC (ChABC) is a promising therapeutic for spinal cord injury as it can degrade the glial scar that is detrimental to regrowth and repair. However, the sustained delivery of bioactive ChABC is a challenge requiring highly invasive methods such as intra-spinal injections, insertion of intrathecal catheters, or implantation of delivery vehicles directly into the tissue. ChABC is thermally unstable, further complicating its delivery. Moreover, there are no commercial antibodies available for its detection. To achieve controlled release, we designed an affinity-based system that sustained the release of bioactive ChABC for at least 7days. ChABC was recombinantly expressed as a fusion protein with Src homology domain 3 (SH3) with an N-terminal histidine (HIS) tag and a C-terminal FLAG tag (ChABC-SH3). Protein purification was achieved using a nickel affinity column and, for the first time, direct quantification of ChABC down to 0.1nM was attained using an in-house HIS/FLAG double tag ELISA. The release of active ChABC-SH3 was sustained from a methylcellulose hydrogel covalently modified with an SH3 binding peptide. The rate of release was tunable by varying either the binding strength of the SH3-protein/SH3-peptide pair or the SH3-peptide to SH3-protein ratio. This innovative system has the potential to be used as a platform technology for the release and detection of other proteins that can be expressed using a similar construct. PMID:23831055

  10. Functional, Anatomical, and Molecular Investigation of the Cardiac Conduction System and Arrhythmogenic Atrioventricular Ring Tissue in the Rat Heart

    PubMed Central

    Atkinson, Andrew J.; Logantha, Sunil Jit R. J.; Hao, Guoliang; Yanni, Joseph; Fedorenko, Olga; Sinha, Aditi; Gilbert, Stephen H.; Benson, Alan P.; Buckley, David L.; Anderson, Robert H.; Boyett, Mark R.; Dobrzynski, Halina

    2013-01-01

    Background The cardiac conduction system consists of the sinus node, nodal extensions, atrioventricular (AV) node, penetrating bundle, bundle branches, and Purkinje fibers. Node‐like AV ring tissue also exists at the AV junctions, and the right and left rings unite at the retroaortic node. The study aims were to (1) construct a 3‐dimensional anatomical model of the AV rings and retroaortic node, (2) map electrical activation in the right ring and study its action potential characteristics, and (3) examine gene expression in the right ring and retroaortic node. Methods and Results Three‐dimensional reconstruction (based on magnetic resonance imaging, histology, and immunohistochemistry) showed the extent and organization of the specialized tissues (eg, how the AV rings form the right and left nodal extensions into the AV node). Multiextracellular electrode array and microelectrode mapping of isolated right ring preparations revealed robust spontaneous activity with characteristic diastolic depolarization. Using laser microdissection gene expression measured at the mRNA level (using quantitative PCR) and protein level (using immunohistochemistry and Western blotting) showed that the right ring and retroaortic node, like the sinus node and AV node but, unlike ventricular muscle, had statistically significant higher expression of key transcription factors (including Tbx3, Msx2, and Id2) and ion channels (including HCN4, Cav3.1, Cav3.2, Kv1.5, SK1, Kir3.1, and Kir3.4) and lower expression of other key ion channels (Nav1.5 and Kir2.1). Conclusions The AV rings and retroaortic node possess gene expression profiles similar to that of the AV node. Ion channel expression and electrophysiological recordings show the AV rings could act as ectopic pacemakers and a source of atrial tachycardia. PMID:24356527

  11. Voyager 2 radio science observations of the uranian system: atmosphere, rings, and satellites.

    PubMed

    Tyler, G L; Sweetnam, D N; Anderson, J D; Campbell, J K; Eshleman, V R; Hinson, D P; Levy, G S; Lindal, G F; Marouf, E A; Simpson, R A

    1986-07-01

    Voyager 2 radio occultation measurements of the Uranian atmosphere were obtained between 2 and 7 degrees south latitude. Initial atmospheric temperature profiles extend from pressures of 10 to 900 millibars over a height range of about 100 kilometers. Comparison of radio and infrared results yields mole fractions near the tropopause of 0.85 and 0.15 +/- 0.05 for molecular hydrogen and helium, respectively, if no other components are present; for this composition the tropopause is at about 52 kelvins and 110 millibars. Distinctive features in the signal intensity measurements for pressures above 900 millibars strongly favor model atmospheres that include a cloud deck of methane ice. Modeling of the intensity measurements for the cloud region and below indicates that the cloud base is near 1,300 millibars and 81 kelvins and yields an initial methane mole fraction of about 0.02 for the deep atmosphere. Scintillations in signal intensity indicate small-scale stucture throughout the stratosphere and upper troposphere. As judged from data obtained during occultation ingress, the ionosphere consists of a multilayer structure that includes two distinct layers at 2,000 and 3,500 kilometers above the 100-millibar level and an extended topside that may reach altitudes of 10,000 kilometers or more. Occultation measurements of the nine previously known rings at wavelengths of 3.6 and 13 centimeters show characteristic values of optical depth between about 0.8 and 8; the maxim value occurs in the outer region of the in ring, near its periapsis. Forward-scattered signals from this ring have properties that differ from those of any of Saturn's rings, and they are inconsistent with a discrete scattering object or local (three-dimensional) assemblies of orbiting objects. These signals suggest a new kdnd of planetary ring feature characterized by highly ordered cylindrical substructures of radial scale on the order of meters and azimuthal scale of kilometers or more. From radio data

  12. Optical Properties of a Quantum Dot-Ring System Grown Using Droplet Epitaxy.

    PubMed

    Linares-García, Gabriel; Meza-Montes, Lilia; Stinaff, Eric; Alsolamy, S M; Ware, M E; Mazur, Y I; Wang, Z M; Lee, Jihoon; Salamo, G J

    2016-12-01

    Electronic and optical properties of InAs/GaAs nanostructures grown by the droplet epitaxy method are studied. Carrier states were determined by k · p theory including effects of strain and In gradient concentration for a model geometry. Wavefunctions are highly localized in the dots. Coulomb and exchange interactions are studied and we found the system is in the strong confinement regime. Microphotoluminescence spectra and lifetimes were calculated and compared with measurements performed on a set of quantum rings in a single sample. Some features of spectra are in good agreement.

  13. Universal cumulants of the current in diffusive systems on a ring.

    PubMed

    Appert-Rolland, C; Derrida, B; Lecomte, V; van Wijland, F

    2008-08-01

    We calculate exactly the first cumulants of the integrated current and of the activity (which is the total number of changes of configurations) of the symmetric simple exclusion process on a ring with periodic boundary conditions. Our results indicate that for large system sizes the large deviation functions of the current and of the activity take a universal scaling form, with the same scaling function for both quantities. This scaling function can be understood either by an analysis of Bethe ansatz equations or in terms of a theory based on fluctuating hydrodynamics or on the macroscopic fluctuation theory of Bertini, De Sole, Gabrielli, Jona-Lasinio, and Landim. PMID:18850801

  14. Synthesis and Thermal Behavior of a Fused, Tricyclic 1,2,3,4-Tetrazine Ring System.

    PubMed

    Chavez, David E; Bottaro, Jeffery C; Petrie, Mark; Parrish, Damon A

    2015-10-26

    This study presents the synthesis and characterization of a fused, tricyclic 1,2,3,4-tetrazine ring system. The molecule is synthesized in a three-step process from 5,5'-dinitro-bis,1,2,4-triazole via a di-N-amino compound. Oxidation to form the azo-coupled fused tricyclic 1,2,3,4-tetrazine is achieved using tert-butyl hypochlorite as the oxidant. The di-N-amino compound and the desired fused tricyclic 1,2,3,4-triazine display interesting thermal behavior and are predicted to be high-performance energetic materials.

  15. Synthesis of the polycyclic ring systems of artocarpol A and D.

    PubMed

    Paduraru, M Peggy; Wilson, Peter D

    2003-12-11

    The first synthesis of the polycyclic ring systems of artocarpol A and D has been accomplished. These natural products were isolated recently from the root bark of Artocarpus rigida, and artocarpol A has been shown to have potent antiinflammatory properties. The synthesis of an artocarpol D analogue was achieved on condensation of 11H-dibenzo[b,f]oxepin-10-one with senecialdehyde. The reaction of this oxepinone with citral afforded a 2H-pyran that on subsequent irradiation afforded an analogue of artocarpol A. [reaction: see text

  16. Cavity Ring-Down System for Density Measurement of Negative Hydrogen Ion on Negative Ion Source

    SciTech Connect

    Nakano, Haruhisa; Tsumori, Katsuyoshi; Nagaoka, Kenichi; Shibuya, Masayuki; Kisaki, Masashi; Ikeda, Katsunori; Osakabe, Masaki; Kaneko, Osamu; Asano, Eiji; Kondo, Tomoki; Sato, Mamoru; Komada, Seiji; Sekiguchi, Haruo; Takeiri, Yasuhiko; Fantz, Ursel

    2011-09-26

    A Cavity Ring-Down (CRD) system was applied to measure the density of negative hydrogen ion (H{sup -}) in vicinity of extraction surface in the H{sup -} source for the development of neutral beam injector on Large Helical Device (LHD). The density measurement with sampling time of 50 ms was carried out. The measured density with the CRD system is relatively good agreement with the density evaluated from extracted beam-current with applying a similar relation of positive ion sources. In cesium seeded into ion-source plasma, the linearity between an arc power of the discharge and the measured density with the CRD system was observed. Additionally, the measured density was proportional to the extracted beam current. These characteristics indicate the CRD system worked well for H{sup -} density measurement in the region of H{sup -} and extraction.

  17. Identification of ABC transporters in Sarcoptes scabiei.

    PubMed

    Mounsey, K E; Holt, D C; McCarthy, J; Walton, S F

    2006-06-01

    We have identified and partially sequenced 8 ABC transporters from an EST dataset of Sarcoptes scabiei var. hominis, the causative agent of scabies. Analysis confirmed that most of the known ABC subfamilies are represented in the EST dataset including several members of the multidrug resistance protein subfamily (ABC-C). Although P-glycoprotein (ABC-B) sequences were not found in the EST dataset, a partial P-glycoprotein sequence was subsequently obtained using a degenerate PCR strategy and library screening. Thus a total of 9 potential S. scabiei ABC transporters representing the subfamilies A, B, C, E, F and H have been identified. Ivermectin is currently used in the treatment of hyper-infested (crusted) scabies, and has also been identified as a potentially effective acaricide for mass treatment programmes in scabies-endemic communities. The observation of clinical and in vitro ivermectin resistance in 2 crusted scabies patients who received multiple treatments has raised serious concerns regarding the sustainability of such programmes. One possible mechanism for ivermectin resistance is through ABC transporters such as P-glycoprotein. This work forms an important foundation for further studies to elucidate the potential role of ABC transporters in ivermectin resistance of S. scabiei.

  18. Nerve ring of the hypostome in hydra: is it an origin of the central nervous system of bilaterian animals?

    PubMed

    Koizumi, Osamu

    2007-01-01

    A hypothesis, 'the nerve ring in hydra shares a common origin with the central nervous system in bilaterian animals', is discussed in this review. The nerve ring of hydra is a ring of neurons whose neurites make a bundle running circumferentially around the hypostome just above the tentacle zone. This nervous structure has unique features in the hydra nervous system. It shows a tight association of neurons in contrast to the diffuse nerve net seen in other regions. It shows static developmental characters in contrast to the dynamic features of hydra nerve net present in other regions. Moreover, its structure and location are similar to the central nervous system (CNS) of other animals without a complex CNS such as nematodes and starfishes. Functions of the hydra nerve ring are also studied to test the hypothesis. The identified function is a crumpling of the tentacles, corresponding to the function of the inner nerve ring of hydrozoan jellyfish. The jellyfish nerve ring is considered to be a primitive central nervous system of radiates. Considering all the information available, the hypothesis is highly possible.

  19. Applying the ABCs in provider organizations.

    PubMed

    Pandey, Seema

    2012-11-01

    Activity-based costing (ABC) is an accounting technique designed to guard against potentially serious financial problems that can arise when an organization's accounting costs deviate significantly from its actual costs. In general, an ABC analysis considers two factors: a cost element (a directly measurable unit of cost, such as the cost of an item) and a cost driver (a directly measurable feature of the service, such as how often the item is used). ABC is best applied to specific service areas, orservice packages, for which consumption of resources is largely predictable and atomic units of services can be accurately identified. PMID:23173369

  20. Applying the ABCs in provider organizations.

    PubMed

    Pandey, Seema

    2012-11-01

    Activity-based costing (ABC) is an accounting technique designed to guard against potentially serious financial problems that can arise when an organization's accounting costs deviate significantly from its actual costs. In general, an ABC analysis considers two factors: a cost element (a directly measurable unit of cost, such as the cost of an item) and a cost driver (a directly measurable feature of the service, such as how often the item is used). ABC is best applied to specific service areas, orservice packages, for which consumption of resources is largely predictable and atomic units of services can be accurately identified.

  1. Generation of optical frequency combs in a fiber-ring/microresonator laser system.

    PubMed

    Guo, Changlei; Che, Kaijun; Xu, Huiying; Zhang, Pan; Tang, Deyu; Ren, Changyan; Luo, Zhengqian; Cai, Zhiping

    2016-06-01

    We propose and experimentally demonstrate a simple scheme for generating optical frequency combs (OFCs) in a fiber-ring/microresonator laser system. The ultrahigh Q whispering gallery mode microresonator is employed both as a mode reflection mirror to generate erbium lasing and as a Kerr-nonlinearity initiator that introduces optical parametric oscillation signals to form OFCs. By controlling the coupling position between the fiber taper and microresonator, optimizing the fiber polarization, as well as the pump power from a 974 nm laser diode (LD), versatile OFCs can be tuned out from single-wavelength states. The OFCs have single, multiple, or combined free spectral ranges. In addition, a Raman-gain-assisted OFC is also observed with a bandwidth of ∼230  nm. This LD-pumped and multifunctional laser system could find applications in precision spectroscopy, biochemical sensing, and optical fiber communication systems. PMID:27244418

  2. The Ring of Fire - an internal illimination system for detector sensitivity and filter bandpass characterization

    SciTech Connect

    Scarpine, Victor E.; Kent, Stephen M.; Deustua, Susana E.; Sholl, Michael J.; Mufson, Stuart L.; Ott, Melanie N.; Wiesner, Matthew P.; Baptitst, Brian J.; /Indiana U.

    2010-07-01

    We describe a prototype of an illumination system, the Ring of Fire (ROF), which is used as part of an internal calibration system for large focal plane detector arrays in TMA (Three Mirror Anastigmat) telescope designs. Such designs have been proposed for the SNAP (SuperNova Acceleration Probe) version of a Joint Dark Energy Mission (JDEM). The ROF system illuminates the focal plane with a light beam the closely matches that of the telescope and is used for creating high spatial frequency flat fields and monitoring filter bandpasses for experiments that demand a highly accurate characterization of the detectors. We present measurements of a mockup of this prototype ROF design including studies in variations in illumination across a large focal plane.

  3. The trigger system for the external target experiment in the HIRFL cooling storage ring

    NASA Astrophysics Data System (ADS)

    Li, Min; Zhao, Lei; Liu, Jin-Xin; Lu, Yi-Ming; Liu, Shu-Bin; An, Qi

    2016-08-01

    A trigger system was designed for the external target experiment in the Cooling Storage Ring (CSR) of the Heavy Ion Research Facility in Lanzhou (HIRFL). Considering that different detectors are scattered over a large area, the trigger system is designed based on a master-slave structure and fiber-based serial data transmission technique. The trigger logic is organized in hierarchies, and flexible reconfiguration of the trigger function is achieved based on command register access or overall field-programmable gate array (FPGA) logic on-line reconfiguration controlled by remote computers. We also conducted tests to confirm the function of the trigger electronics, and the results indicate that this trigger system works well. Supported by the National Natural Science Foundation of China (11079003), the Knowledge Innovation Program of the Chinese Academy of Sciences (KJCX2-YW-N27), and the CAS Center for Excellence in Particle Physics (CCEPP).

  4. Hubble Observations of the Ongoing Evolution of Neptune's Ring-Moon System

    NASA Astrophysics Data System (ADS)

    Showalter, Mark Robert; de Pater, Imke; Lissauer, Jack J.; French, Robert S.

    2016-10-01

    We report on a new analysis of Hubble Space Telescope (HST) images of the Neptune system spanning 2004 to 2016. This expands upon an initial analysis we presented in 2013 (Showalter et al., DPS Meeting #45, abstract 206.01), based on HST images from 2004-2009. At that time we reported (1) the discovery of Neptune's fourteenth moon, S/2004 N 1, which orbits between Proteus and Larissa; (2) the recovery of Naiad, Neptune's innermost moon, although at an orbital longitude 90 degrees away from its prediction; and (3) the disappearance of the leading arcs in the Adams Ring, along with a marked decrease in the brightness of the trailing two arcs. Recent HST images extend the time baseline of the system by seven additional years, allowing us to expand upon prior results. We will report on our progress in refining the orbit, size and shape of S/2004 N 1, on understanding the orbital dynamics of Naiad, and on determining the ongoing evolution of the arcs and rings.

  5. Isolation and Characterization of the Colletotrichum acutatum ABC Transporter CaABC1

    PubMed Central

    Kim, Suyoung; Park, Sook-Young; Kim, Hyejeong; Kim, Dongyoung; Lee, Seon-Woo; Kim, Heung Tae; Lee, Jong-Hwan; Choi, Woobong

    2014-01-01

    Fungi tolerate exposure to various abiotic stresses, including cytotoxic compounds and fungicides, via their ATP-driven efflux pumps belonging to ATP-binding cassette (ABC) transporters. To clarify the molecular basis of interaction between the fungus and various abiotic stresses including fungicides, we constructed a cDNA library from germinated conidia of Colletotrichum acutatum, a major anthracnose pathogen of pepper (Capsicum annum L.). Over 1,000 cDNA clones were sequenced, of which single clone exhibited significant nucleotide sequence homology to ABC transporter genes. We isolated three fosmid clones containing the C. acutatum ABC1 (CaABC1) gene in full-length from genomic DNA library screening. The CaABC1 gene consists of 4,059 bp transcript, predicting a 1,353-aa protein. The gene contains the typical ABC signature and Walker A and B motifs. The 5′-flanking region contains a CAAT motif, a TATA box, and a Kozak region. Phylogenetic and structural analysis suggested that the CaABC1 is a typical ABC transporter gene highly conserved in various fungal species, as well as in Chromista, Metazoans, and Viridiplantae. We also found that CaABC1 was up-regulated during conidiation and a minimal medium condition. Moreover, CaABC1 was induced in iprobenfos, kresoxim-methyl, thiophanate-methyl, and hygromycin B. These results demonstrate that CaABC1 is necessary for conidiation, abiotic stress, and various fungicide resistances. These results will provide the basis for further study on the function of ABC transporter genes in C. acutatum. PMID:25506302

  6. Evolution of the ABC model among the segregated configurations in the zero-temperature limit

    NASA Astrophysics Data System (ADS)

    Misturini, Ricardo

    2016-05-01

    We consider the ABC model on a ring in a strongly asymmetric regime. The main result asserts that the particles almost always form three pure domains (one of each species) and that this segregated shape evolves, in a proper time scale, as a Brownian motion on the circle, which may have a drift. This is, to our knowledge, the first proof of a zero-temperature limit for a non-reversible dynamics whose invariant measure is not explicitly known.

  7. Vacuum system of the high energy ring of an asymmetric B-factory based on PEP

    SciTech Connect

    Barletta, W.A.; Calderon, M.O.; Wong, R. ); Jenkins, T.M. )

    1991-05-07

    The multi-ampere currents required for high luminosity operation of an asymmetric B factory leads to extremely stressing requirements on a vacuum system suitable for maintaining long beam-gas lifetimes and acceptable background levels in the detector. We present the design for a Cu alloy vacuum chamber and its associated pumping system for the 9 GeV electron storage ring of the proposed B factory based on PEP. The excellent thermal and photo-desorption properties of Cu allows handling the high proton flux in a conventional, single chamber design with distributed ion pumps. The x-ray opacity of the Cu is sufficiently high that no additional lead shielding is necessary to protect the dipoles from the intense synchrotron radiation generated by the beam. The design allows chamber commissioning in <500 hr of operation. 5 refs., 3 figs., 2 tabs.

  8. Optical Analog to Electromagnetically Induced Transparency in Cascaded Ring-Resonator Systems

    PubMed Central

    Wang, Yonghua; Zheng, Hua; Xue, Chenyang; Zhang, Wendong

    2016-01-01

    The analogue of electromagnetically induced transparency in optical methods has shown great potential in slow light and sensing applications. Here, we experimentally demonstrated a coupled resonator induced transparency system with three cascaded ring coupled resonators in a silicon chip. The structure was modeled by using the transfer matrix method. Influences of various parameters including coupling ratio of couplers, waveguide loss and additional loss of couplers on transmission characteristic and group index have been investigated theoretically and numerically in detail. The transmission character of the system was measured by the vertical grating coupling method. The enhanced quality factor reached 1.22 × 105. In addition, we further test the temperature performance of the device. The results provide a new method for the manipulation of light in highly integrated optical circuits and sensing applications. PMID:27463720

  9. Preliminary vibration analysis of magnet/support system for 7-GeV APS storage ring

    SciTech Connect

    Wambsganss, M.W.

    1989-05-08

    The storage ring quadrupoles, sextupoles, and correction magnets will be mounted on a common girder approximately 4.0 m long. The rigid girder, in turn, is mounted on three five-ton jacks, each of which is mounted on a pedestal that is grouted and bolted to the floor. For this preliminary analysis, we will assume that the girder has a weight per unit length of 100 lb/ft and a bending stiffness that is significantly greater than the vertical stiffness provided by the pedestal (jack-screw) supports. This allows us to approximate the magnet/support system as a rigid beam (girder) on spring supports (jack-screws) carrying distributed masses (magnets). These approximations permit us to study the rigid body translational and rotational (rocking) modes of the system. It should be noted that the preliminary design has two jack-screw supports at the left end and one at the right end. It should be noted that the magnet/support system studied is only a conceptual design. In actuality, there are five different magnet/support configurations comprising each of the 40 sectors of the storage ring. Also, it is expected that the details of the final design, in particular with respect to the positioning of the pedestal supports, will somewhat different. It should further be noted that a major assumption in the analysis is that the stiffness of the support beam with respect to the stiffness of the jack-screw supports is such that the support girder can be assumed rigid. To evaluate this assumption it is planned to perform a finite element analysis of the magnet/support system in which the flexibility of the support girder is included in the dynamic analysis.

  10. Dosimetric advantages of O-ring design radiotherapy system for skull-base tumors.

    PubMed

    Ogura, Kengo; Mizowaki, Takashi; Ishida, Yuichi; Hiraoka, Masahiro

    2014-01-01

    The purpose of this study was to investigate whether a new O-ring design radiotherapy delivery system has advantages in radiotherapy planning for skull-base tumors. Twenty-five patients with skull-base tumors were included in this study. Two plans were made using conventional (Plan A) or new (Plan B) techniques. Plan A consisted of four dynamic conformal arcs (DCAs): two were horizontal, and the other two were from cranial directions. Plan B was created by converting horizontal arcs to those from caudal directions making use of the O-ring design radiotherapy system. The micromultileaf collimators were fitted to cover at least 99% of the planning target volume with prescribed doses, 90% of the dose at the isocenter. The two plans were compared in terms of target homogeneity, conformity, and irradiated volume of normal tissues, using a two-sided paired t-test. For evaluation regarding target coverage, the homogeneity indices defined by the International Commission on Radiation Units and Measurements 83 were 0.099 ± 0.010 (mean ± standard deviation) and 0.092 ± 0.010, the conformity indices defined by the Radiation Therapy Oncology Group were 1.720 ± 0.249 and 1.675 ± 0.239, and the Paddick's conformity indices were 0.585 ± 0.078 and 0.602 ± 0.080, in Plans A and B, respectively. For evaluation of irradiated normal tissue, the Paddick's gradient indices were 3.118 ± 0.283 and 2.938 ± 0.263 in Plans A and B, respectively. All of these differences were statistically significant (p-values < 0.05). The mean doses of optic nerves, eyes, brainstem, and hippocampi were also significantly lower in Plan B. The DCA technique from caudal directions using the new O-ring design radiotherapy system can improve target homogeneity and conformity compared with conventional DCA techniques, and can also decrease the volume of surrounding normal tissues that receives moderate doses. PMID:24710448

  11. Dosimetric advantages of O-ring design radiotherapy system for skull-base tumors.

    PubMed

    Ogura, Kengo; Mizowaki, Takashi; Ishida, Yuichi; Hiraoka, Masahiro

    2014-03-06

    The purpose of this study was to investigate whether a new O-ring design radiotherapy delivery system has advantages in radiotherapy planning for skull-base tumors. Twenty-five patients with skull-base tumors were included in this study. Two plans were made using conventional (Plan A) or new (Plan B) techniques. Plan A consisted of four dynamic conformal arcs (DCAs): two were horizontal, and the other two were from cranial directions. Plan B was created by converting horizontal arcs to those from caudal directions making use of the O-ring design radiotherapy system. The micromultileaf collimators were fitted to cover at least 99% of the planning target volume with prescribed doses, 90% of the dose at the isocenter. The two plans were compared in terms of target homogeneity, conformity, and irradiated volume of normal tissues, using a two-sided paired t-test. For evaluation regarding target coverage, the homogeneity indices defined by the International Commission on Radiation Units and Measurements 83 were 0.099 ± 0.010 (mean ± standard deviation) and 0.092 ± 0.010, the conformity indices defined by the Radiation Therapy Oncology Group were 1.720 ± 0.249 and 1.675 ± 0.239, and the Paddick's conformity indices were 0.585 ± 0.078 and 0.602 ± 0.080, in Plans A and B, respectively. For evaluation of irradiated normal tissue, the Paddick's gradient indices were 3.118 ± 0.283 and 2.938 ± 0.263 in Plans A and B, respectively. All of these differences were statistically significant (p-values < 0.05). The mean doses of optic nerves, eyes, brainstem, and hippocampi were also significantly lower in Plan B. The DCA technique from caudal directions using the new O-ring design radiotherapy system can improve target homogeneity and conformity compared with conventional DCA techniques, and can also decrease the volume of surrounding normal tissues that receives moderate doses.

  12. Pedology around a 6700 year old Neolithic ring ditch system in Germany

    NASA Astrophysics Data System (ADS)

    Leopold, Matthias; Völkel, Jörg; Schmotz, Karl; Huerkamp, Kerstin

    2010-05-01

    The cultural landscape in Europe is the product of many different human and natural activities and processes. Settlement, clearing and farming over thousands of years are constantly transforming the landscape and the according bio- and geo-components like flora and fauna, relief, hydrology, soils and others. As Geoarchaeology tries to reconstruct certain stages of this cultural landscape development, the existence of geoarchives of the respective time period are a crucial precondition. Soil science often works with colluvium as geoarchives but that presupposes the original soil to be destroyed by erosion. Therefore there is a lack of in situ soils of certain time periods throughout Europe. During archaeological excavations conducted by the Kreisarchäologie Deggendorf in eastern Bavaria late 2008 a new Neolithic ring ditch system was discovered which dates back to 4700 BC. Beside its enormous archaeological relevance the study site offers unique possibilities for pedological studies. Situated in the loess belt of eastern Bavaria calcic luvisols form the native soils of the region. However, black soils from older floodplains, the so-called Tschernitza, are described some hundred meters beside the excavation area. In addition black sediments which fill the pits of a Neolithic settlement close to the ring ditch system have been detected. The black backfill sediments are correlated with anthropogenic settlement activities. Interestingly, the backfills of the contemporaneous ring ditch system differ. The 2 m wide and 2.5 m deep ditch functioned as an ideal trap for naturally eroded sediments. The backfills of the ditch indicate different phases of sedimentation and artificial reformation of the ditch. Furthermore, the analysis of thin sections and laboratory data (such as RFA, RDA, pedogenic oxides , magn. suszept., etc.) together with geophysical measurements point to the existence of a fully developed calcic luvisol around 6700 years ago. At the same time within some

  13. Electromagnetic Calculation of Combined Earthing System with Ring Earth Electrode and Vertical Rods for Wind Turbine

    NASA Astrophysics Data System (ADS)

    Fujii, Toshiaki; Yasuda, Yoh; Ueda, Toshiaki

    With the worldwide spread of wind turbine installations, various problems such as landscape issues, bird strikes and grid connections have arisen. Protection of wind turbines from lightning is cited as one of the main problems. Wind turbines are often struck by lightning because of their open-air locations, such as in mountainous areas, and their special configuration and very-high construction. Especially, low-voltage and control circuits can fail or suffer burnout while blades can incur serious damage if struck by lightning. Wind turbine failures caused by lightning strikes account for approximately 25% of all failures. The problem is regarded as a global one that needs immediate resolution. It is important to understand the impedance characteristics of wind turbine earthing systems from the viewpoint of lightning protection. A report from IEC TR61400-24 recommends a “ring earth electrode”. This was originally defined in IEC 61024 (currently revised and re-numbered as IEC 62305), where such an electrode is recommended to reduce touch and step voltages in households and buildings. IEC TR61400-24 also recommended additional electrodes of vertical or horizontal rods. However, these concepts have not been fully discussed from the viewpoint of its application to wind turbines. To confirm the effect of a combination of a ring earth electrode and additional vertical rods for protection of a wind turbine, this report uses the Finite Difference Time Domain (FDTD) method to present an electromagnetic transient analysis on such a wind turbine earthing system. The results show that an optimal combination can be arranged from viewpoints of lightning protection and construction cost. Thus, this report discusses how to establish a quantitative design methodology of the wind turbine earthing system to provide effective lightning protection.

  14. A wireless fatigue monitoring system utilizing a bio-inspired tree ring data tracking technique.

    PubMed

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  15. A Wireless Fatigue Monitoring System Utilizing a Bio-Inspired Tree Ring Data Tracking Technique

    PubMed Central

    Bai, Shi; Li, Xuan; Xie, Zhaohui; Zhou, Zhi; Ou, Jinping

    2014-01-01

    Fatigue, a hot scientific research topic for centuries, can trigger sudden failure of critical structures such as aircraft and railway systems, resulting in enormous casualties as well as economic losses. The fatigue life of certain structures is intrinsically random and few monitoring techniques are capable of tracking the full life-cycle fatigue damage. In this paper, a novel in-situ wireless real-time fatigue monitoring system using a bio-inspired tree ring data tracking technique is proposed. The general framework, methodology, and verification of this intelligent system are discussed in details. The rain-flow counting (RFC) method is adopted as the core algorithm which quantifies fatigue damages, and Digital Signal Processing (DSP) is introduced as the core module for data collection and analysis. Laboratory test results based on strain gauges and polyvinylidene fluoride (PVDF) sensors have shown that the developed intelligent system can provide a reliable quick feedback and early warning of fatigue failure. With the merits of low cost, high accuracy and great reliability, the developed wireless fatigue sensing system can be further applied to mechanical engineering, civil infrastructures, transportation systems, aerospace engineering, etc. PMID:24603635

  16. Simulating the Librational Behaviour of Propeller Moons In The Saturnian Ring System

    NASA Astrophysics Data System (ADS)

    Seiler, Michael; Seiss, Martin; Hoffmann, Holger; Spahn, Frank

    2016-10-01

    The propeller structure Blériot orbiting in the outer A ring of the Saturnian ring system has been one of the tremendous discoveries of the spacecraft Cassini [Tiscareno et al., 2010, ApJL]. The reconstruction of the orbital evolution of Blériot from recurrent observations in the ISS images yielded a systematic offset motion from the expected Keplerian orbit. This offset motion can be well described by three sinusoidal harmonics with amplitudes and periods of 1845, 152, 58 km and 11.1, 3.7 and 2.2 years, respectively [Sremčević et al., 2014, EPSC]. Oscillatory deviations from the Keplerian orbit are a known phenomenon for the Saturnian moons, which can be explained by resonant interactions with other moons [Spitale et al., 2006, AJ] and which look similar to the observation of Blériot.In this work we present our results from N-Body simulations, where we integrated the orbital evolution of a test particle, orbiting at the radial position of the propeller Blériot and 15 other moons of Saturn. Our simulation yield, that gravitational interactions with the larger moons result in reasonable and observable frequencies, but the resulting amplitudes of the librations are by far too small to explain the observations. Further mechanisms are needed, to amplify the amplitudes of the forced librations -- as e.g. by moonlet-ring interactions. Inspired by the recent work of Pan and Chiang [2010, ApJL; 2012, AJ] we introduce an alternative, physically more reasonable model. In our model, the moonlet is allowed to be slightly displaced with respect to its created gaps, resulting in a repulsive force. As a result, the moonlet's longitude starts to oscillate. In the presence of the additional external forcing by the outer moons the libration amplitude gets amplified, if the forcing frequency is close to the eigenfrequency of the system. Applying our model to Blériot, we can indeed reproduce a libration period of 13 years with an amplitude of about 2000 km.

  17. Temporal dynamics of the ABC transporter response to insecticide treatment: insights from the malaria vector Anopheles stephensi

    NASA Astrophysics Data System (ADS)

    Epis, Sara; Porretta, Daniele; Mastrantonio, Valentina; Urbanelli, Sandra; Sassera, Davide; De Marco, Leone; Mereghetti, Valeria; Montagna, Matteo; Ricci, Irene; Favia, Guido; Bandi, Claudio

    2014-12-01

    In insects, ABC transporters have been shown to contribute to defence/resistance to insecticides by reducing toxic concentrations in cells/tissues. Despite the extensive studies about this detoxifying mechanism, the temporal patterns of ABC transporter activation have been poorly investigated. Using the malaria vector Anopheles stephensi as a study system, we investigated the expression profile of ABC genes belonging to different subfamilies in permethrin-treated larvae at different time points (30 min to 48 h). Our results showed that the expression of ABCB and ABCG subfamily genes was upregulated at 1 h after treatment, with the highest expression observed at 6 h. Therefore, future investigations on the temporal dynamics of ABC gene expression will allow a better implementation of insecticide treatment regimens, including the use of specific inhibitors of ABC efflux pumps.

  18. Temporal dynamics of the ABC transporter response to insecticide treatment: insights from the malaria vector Anopheles stephensi.

    PubMed

    Epis, Sara; Porretta, Daniele; Mastrantonio, Valentina; Urbanelli, Sandra; Sassera, Davide; De Marco, Leone; Mereghetti, Valeria; Montagna, Matteo; Ricci, Irene; Favia, Guido; Bandi, Claudio

    2014-01-01

    In insects, ABC transporters have been shown to contribute to defence/resistance to insecticides by reducing toxic concentrations in cells/tissues. Despite the extensive studies about this detoxifying mechanism, the temporal patterns of ABC transporter activation have been poorly investigated. Using the malaria vector Anopheles stephensi as a study system, we investigated the expression profile of ABC genes belonging to different subfamilies in permethrin-treated larvae at different time points (30 min to 48 h). Our results showed that the expression of ABCB and ABCG subfamily genes was upregulated at 1 h after treatment, with the highest expression observed at 6 h. Therefore, future investigations on the temporal dynamics of ABC gene expression will allow a better implementation of insecticide treatment regimens, including the use of specific inhibitors of ABC efflux pumps. PMID:25504146

  19. New beam-position monitor system for upgraded Photon Factory storage ring.

    PubMed

    Haga, K; Honda, T; Tadano, M; Obina, T; Kasuga, T

    1998-05-01

    Accompanying the brilliance-upgrading project at the Photon Factory storage ring, the beam-position monitor (BPM) system has been renovated. The new system was designed to enable precise and fast measurements to correct the closed-orbit distortion (COD), as well as to feed back the orbit position during user runs. There are 42 BPMs newly installed, amounting to a total of 65 BPMs. All of the BPMs are calibrated on the test bench using a coaxially strung metallic wire. The measured electrical offsets are typically 200 micro m in both directions, which is 1/2-1/3 of those of the old-type BPMs. In the signal-processing system, PIN diode switches are employed in order to improve reliability. In the fastest mode, this system is capable of measuring COD within about 10 ms; this fast acquisition will allow fast suppression of the beam movement for frequencies up to 50 Hz using a global feedback system. PMID:15263599

  20. LARS Artificial Ligament Versus ABC Purely Polyester Ligament for Anterior Cruciate Ligament Reconstruction

    PubMed Central

    Iliadis, Dimitrios Ph.; Bourlos, Dimitrios N.; Mastrokalos, Dimitrios S.; Chronopoulos, Efstathios; Babis, George C.

    2016-01-01

    Background: Graft choice for anterior cruciate ligament (ACL) reconstruction is of critical importance. Various grafts have been used so far, with autografts long considered the optimal solution for the treatment of ACL-deficient knees. Limited data are available on the long-term survivorship of synthetic grafts. Purpose: To compare the functional outcome and survivorship of ACL reconstructions performed using the LARS (ligament augmentation and reconstruction system) ligament and the ABC (active biosynthetic composite) purely polyester ligament. Study Design: Case series; Level of evidence, 4. Methods: The results of 72 patients who underwent primary arthroscopic ACL reconstruction with the LARS ligament and 31 cases with an ABC purely polyester ligament were reviewed. The mean follow-up periods for the LARS and ABC groups were 9.5 and 5.1 years, respectively. A survivorship analysis of the 2 synthetic grafts was performed using the Kaplan-Meier method with a log-rank test (Mantel-Cox, 95% CI). Lysholm, Tegner activity, Knee injury and Osteoarthritis Outcome Score (KOOS), and International Knee Documentation Committee (IKDC) scores as well as laxity measurements obtained using a KT-1000 arthrometer were recorded for all intact grafts, and a Mann-Whitney U test was used for comparison reasons. Results: The rupture rates for LARS and ABC grafts were 31% (95% CI, 20%-42%) and 42% (95% CI, 25%-59%), respectively. For intact grafts, the mean Lysholm score was good for both groups (90 for the LARS group and 89 for the ABC group), with the majority of patients returning to their preinjury level of activities, and the mean IKDC score was 90 for the LARS group and 86 for the ABC group. Conclusion: The rupture rates of both LARS and ABC grafts were both high. However, the LARS ligament provided significantly better survivorship compared with the ABC ligament at short- to midterm follow-up (95% CI). PMID:27453894

  1. Synthesis of the ABCDEF and FGHI ring system of yessotoxin and adriatoxin

    PubMed Central

    Zhang, Yuan; Rainier, Jon D.

    2016-01-01

    Yessotoxin and adriatoxin are members of the polycyclic ether family of marine natural products. Outlined in this article is our synthetic approach to two subunits of these targets. Central to our strategy is a coupling sequence that employs an olefinic-ester cyclization reaction. As outlined, this sequence was used in two coupling sequences. First it was used to merge the A,B- and E,F-bicyclic precursors and in the process generate the C, D-rings. Second it was used to couple the F- and I-rings while building the eight-membered G-ring and subsequently the H-ring pyran. PMID:26956788

  2. Giant relaxation oscillations in a very strongly hysteretic superconductive quantum interference device ring-tank circuit system

    NASA Astrophysics Data System (ADS)

    Clark, T. D.; Prance, R. J.; Whiteman, R.; Prance, H.; Everitt, M. J.; Bulsara, A. R.; Ralph, J. F.

    2001-09-01

    In this article, we show that the radio frequency (rf) dynamical characteristics of a very strongly hysteretic superconducting quantum interference device (SQUID) ring, coupled to a rf tank circuit resonator, display relaxation oscillations. We demonstrate that the overall form of these characteristics, together with the relaxation oscillations, can be modeled accurately by solving the quasiclassical nonlinear equations of motion for the system. We suggest that in these very strongly hysteretic regimes, SQUID ring-resonator systems may find application in logic and memory devices.

  3. Novel DC ring topology and protection system - a comprehensive solution for mega city power grids

    NASA Astrophysics Data System (ADS)

    Haj-Maharsi, Mohamed Yassine

    2009-07-01

    The development of mega cities leads to increased load concentration and brings additional challenges to managing the electrical grid while keeping power available for critical loads. Techniques using FACTS devices are being applied to alleviate power management difficulties and to confine faults in their originating areas in order to limit the risk of cascading failures in the grid. The addition of many FACTS devices often results in control and protection coordination difficulties, power oscillations between connected networks, subsynchronous resonance problems, and torsional interactions with nearby generator units. The most effective solution is obtained when the individual AC subsystems representing sources and loads are decoupled so a fault in a given subsystem is not propagated to another subsystem. This solution can be achieved by the deployment of a DC system where power sources and loads are connected to the DC bus through voltage source converters. For a mega city, this would be conceived as a DC ring feeding multiple loads and connected to remote and local power sources. Unfortunately, the lack of fast DC circuit breakers has been one of the key issues affecting extensive applications of DC systems with common DC buses; a DC fault would discharge all the capacitors of the DC bus and cause delays in system recovery and possibly a wide system collapse. In this research, I provide a comprehensive solution to mega city power grid problems by proposing a DC system topology that enables grid expansions without affecting existing protection settings or changing existing AC breaker ratings. I also propose the means for protecting the DC system by designing a fast DC breaker and developing a control algorithm capable of isolating DC faults without blocking converter stations or depleting DC bus capacitors. My contribution is three folds: (1) I modeled and simulated Shanghai power grid and performed a study to identify short circuit and voltage stability problems

  4. Saturn's largest ring.

    PubMed

    Verbiscer, Anne J; Skrutskie, Michael F; Hamilton, Douglas P

    2009-10-22

    Most planetary rings in the Solar System lie within a few radii of their host body, because at these distances gravitational accelerations inhibit satellite formation. The best known exceptions are Jupiter's gossamer rings and Saturn's E ring, broad sheets of dust that extend outward until they fade from view at five to ten planetary radii. Source satellites continuously supply the dust, which is subsequently lost in collisions or by radial transport. Here we report that Saturn has an enormous ring associated with its outer moon Phoebe, extending from at least 128R(S) to 207R(S) (Saturn's radius R(S) is 60,330 km). The ring's vertical thickness of 40R(S) matches the range of vertical motion of Phoebe along its orbit. Dynamical considerations argue that these ring particles span the Saturnian system from the main rings to the edges of interplanetary space. The ring's normal optical depth of approximately 2 x 10(-8) is comparable to that of Jupiter's faintest gossamer ring, although its particle number density is several hundred times smaller. Repeated impacts on Phoebe, from both interplanetary and circumplanetary particle populations, probably keep the ring populated with material. Ring particles smaller than centimetres in size slowly migrate inward and many of them ultimately strike the dark leading face of Iapetus.

  5. Initial test results of the Los Alamos proton-storage-ring bump-magnet system

    SciTech Connect

    Rose, C.R.; Barlow, D.B.; Redd, D.B.

    1997-09-01

    An upgrade program for increasing the stored beam current in the LANSCE Proton Storage is presently under way. Part of the upgrade effort has been to design, specify, and add four bump-magnet/modulator systems to the ring. This paper describes the initial test results of the first bump-magnet/modulator system. The paper begins with an overview of the pulsed-power system including important specifications of the modulator, magnet, cabling, and control system. In the main portion of the paper, waveforms and test data are included showing the accuracy, repeatability, and stability of the magnet-current pulses. These magnet pulses are programmable both in rise and fall time as well as in amplitude. The amplitude can be set between 50 and 300 A, the rise-time is fixed at 1 ms, and the linear fall-time can be varied between 500 {mu}s and 1500 {mu}s. Other issues such as loading effects and power dissipation in the magnet-bore beamtube are examined and reported.

  6. Nonlinear effects of unbalance in the rotor-floating ring bearing system of turbochargers

    NASA Astrophysics Data System (ADS)

    Tian, L.; Wang, W. J.; Peng, Z. J.

    2013-01-01

    Turbocharger (TC) rotor-floating ring bearing (FRB) system is characterised by high speed as well as high non-linearity. Using the run-up and run-down simulation method, this paper systematically investigates the influence of unbalance on the rotordynamic characteristics of a real TC-FRB system over the speed range from 0 Hz to 3500 Hz. The rotor is discretized by the finite element method, and the desired oil film forces at each simulation step are calculated by an efficient analytical method. The imposed unbalance amount and distribution are the variables considered in the performed non-stationary simulations. The newly obtained results evidently show the distinct phenomena brought about by the variations of the unbalance offset, which confirms that the unbalance level is a critical parameter for the system response. In the meantime, the variations of unbalance distribution, i.e. out-of-phase and in-phase unbalance, can lead to entirely different simulation results as well, which proves the distribution of unbalance is not negligible during the dynamic analysis of the rotor-FRB system. Additionally, considerable effort has been placed on the description as well as discussion of a unique phenomenon termed Critical Limit Cycle Oscillation (CLC Oscillation), which is of great importance and interest to the TC research and development.

  7. MRI-compatible ultrasound heating system with ring-shaped phased arrays for breast tumor thermal therapy.

    PubMed

    Chen, Hung-Nien; Chen, Guan-Ming; Lin, Bo-Sian; Lien, Pi-Hsien; Chen, Yung-Yaw; Chen, Gin-Shin; Lin, Win-Li

    2013-01-01

    Therapeutic ultrasound transducers can carry out precise and efficient power deposition for tumor thermal therapy under the guidance of magnetic resonance imaging. For a better heating, organ-specific ultrasound transducers with precision location control system should be developed for tumors located at various organs. It is feasible to perform a better heating for breast tumor thermal therapy with a ring-shaped ultrasound phased-array transducer. In this study, we developed ring-shaped phased-array ultrasound transducers with 1.0 and 2.5 MHz and a precision location control system to drive the transducers to the desired location to sonicate the designated region. Both thermo-sensitive hydrogel phantom and ex vivo fresh pork were used to evaluate the heating performance of the transducers. The results showed that the ring-shaped phased array ultrasound transducers were very promising for breast tumor heating with the variation of heating patterns and without overheating the ribs.

  8. Can we distinguish between black holes and wormholes by their Einstein-ring systems?

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Naoki; Harada, Tomohiro; Yajima, Kohji

    2012-11-01

    For the past decade, gravitational lensing in the strong gravitational field has been studied eagerly. It is well known that, for the lensing by a black hole, an infinite number of Einstein rings are formed by the light rays which wind around the black hole nearly on the photon sphere, which are called relativistic Einstein rings. This is also the case for the lensing by a wormhole. In this paper, we study the Einstein ring and relativistic Einstein rings for the Schwarzschild black hole and the Ellis wormhole, the latter of which is an example of traversable wormholes of the Morris-Thorne class. Given the configuration of the gravitational lensing and the radii of the Einstein ring and relativistic Einstein rings, we can distinguish between a black hole and a wormhole in principle. We conclude that we can detect the relativistic Einstein rings by wormholes which have the radii of the throat a≃0.5pc at a Galactic center with the distance 10 Mpc and which have a≃10AU in our Galaxy using the most powerful modern instruments which have the resolution of 10-2arcsecond such as a 10-meter optical-infrared telescope. The black holes which make the Einstein rings of the same size as the ones by the wormholes are galactic supermassive black holes and the relativistic Einstein rings by the black holes are too small to measure with the current technology. We may test the hypotheses of astrophysical wormholes by using the Einstein ring and relativistic Einstein rings in the future.

  9. Effective ATPase activity and moderate chaperonin-cochaperonin interaction are important for the functional single-ring chaperonin system.

    PubMed

    Illingworth, Melissa; Salisbury, Jared; Li, Wenqian; Lin, Donghai; Chen, Lingling

    2015-10-01

    Escherichia coli chaperonin GroEL and its cochaperonin GroES are essential for cell growth as they assist folding of cellular proteins. The double-ring assembly of GroEL is required for the chaperone function, and a single-ring variant GroEL(SR) is inactive with GroES. Mutations in GroEL(SR) (A92T, D115N, E191G, and A399T) have been shown to render GroEL(SR)-GroES functional, but the molecular mechanism of activation is unclear. Here we examined various biochemical properties of these functional GroEL(SR)-GroES variants, including ATP hydrolysis rate, chaperonin-cochaperonin interaction, and in vitro protein folding activity. We found that, unlike the diminished ATPase activity of the inactive GroEL(SR)-GroES, all four single-ring variants hydrolyzed ATP at a level comparable to that of the double-ring GroEL-GroES. The chaperonin-cochaperonin interaction in these single-ring systems was weaker, by at least a 50-fold reduction, than the highly stable inactive GroEL(SR)-GroES. Strikingly, only GroEL(SR)D115N-GroES and GroEL(SR)A399T-GroES assisted folding of malate dehydrogenase (MDH), a commonly used folding substrate. These in vitro results are interesting considering that all four of the single-ring systems were able to substitute GroEL-GroES to support cell growth, suggesting that the precise action of chaperonin on MDH folding may not represent that on the intrinsic cellular substrates. Our findings that both effective ATP hydrolysis rate and moderate chaperonin-cochaperonin interaction are important factors for functional single-ring GroEL(SR)-GroES are reminiscent of the naturally occurring single-ring human mitochondrial chaperonin mtHsp60-mtHsp10. Differences in biochemical properties between the single- and double-ring chaperonin systems may be exploited in designing molecules for selective targeting. PMID:26271593

  10. Accelerator-based conversion (ABC) of weapons plutonium: Plant layout study and related design issues

    SciTech Connect

    Cowell, B.S.; Fontana, M.H.; Krakowski, R.A.; Beard, C.A.; Buksa, J.J.; Davidson, J.W.; Sailor, W.C.; Williamson, M.A.

    1995-04-01

    In preparation for and in support of a detailed R and D Plan for the Accelerator-Based Conversion (ABC) of weapons plutonium, an ABC Plant Layout Study was conducted at the level of a pre-conceptual engineering design. The plant layout is based on an adaptation of the Molten-Salt Breeder Reactor (MSBR) detailed conceptual design that was completed in the early 1070s. Although the ABC Plant Layout Study included the Accelerator Equipment as an essential element, the engineering assessment focused primarily on the Target; Primary System (blanket and all systems containing plutonium-bearing fuel salt); the Heat-Removal System (secondary-coolant-salt and supercritical-steam systems); Chemical Processing; Operation and Maintenance; Containment and Safety; and Instrumentation and Control systems. Although constrained primarily to a reflection of an accelerator-driven (subcritical) variant of MSBR system, unique features and added flexibilities of the ABC suggest improved or alternative approaches to each of the above-listed subsystems; these, along with the key technical issues in need of resolution through a detailed R&D plan for ABC are described on the bases of the ``strawman`` or ``point-of-departure`` plant layout that resulted from this study.

  11. Dust and Planetary Rings

    NASA Astrophysics Data System (ADS)

    Siddiqui, Muddassir

    ABSTRACT Space is not empty it has comic radiations (CMBR), dust etc. Cosmic dust is that type of dust which is composed of particles in space which vary from few molecules to 0.1micro metres in size. This type of dust is made up of heavier atoms born in the heart of stars and supernova. Mainly it contains dust grains and when these dust grains starts compacting then it turns to dense clouds, planetary ring dust and circumstellar dust. Dust grains are mainly silicate particles. Dust plays a major role in our solar system, for example in zodiacal light, Saturn's B ring spokes, planetary rings at Jovian planets and comets. Observations and measurements of cosmic dust in different regions of universe provide an important insight into the Universe's recycling processes. Astronomers consider dust in its most recycled state. Cosmic dust have radiative properties by which they can be detected. Cosmic dusts are classified as intergalactic dusts, interstellar dusts and planetary rings. A planetary ring is a ring of cosmic dust and other small particles orbiting around a planet in flat disc shape. All of the Jovian planets in our solar system have rings. But the most notable one is the Saturn's ring which is the brightest one. In March 2008 a report suggested that the Saturn's moon Rhea may have its own tenuous ring system. The ring swirling around Saturn consists of chunks of ice and dust. Most rings were thought to be unstable and to dissipate over course of tens or hundreds of millions of years but it now appears that Saturn's rings might be older than that. The dust particles in the ring collide with each other and are subjected to forces other than gravity of its own planet. Such collisions and extra forces tend to spread out the rings. Pluto is not known to have any ring system but some Astronomers believe that New Horizons probe might find a ring system when it visits in 2015.It is also predicted that Phobos, a moon of Mars will break up and form into a planetary ring

  12. Pi overlapping ring systems contained in a homogeneous assay: a novel homogeneous assay for antigens

    NASA Astrophysics Data System (ADS)

    Kidwell, David A.

    1993-05-01

    A novel immunoassay, Pi overlapping ring systems contained in a homogeneous assay (PORSCHA), is described. This assay relies upon the change in fluorescent spectral properties that pyrene and its derivatives show with varying concentration. Because antibodies and other biomolecules can bind two molecules simultaneously, they can change the local concentration of the molecules that they bind. This concentration change may be detected spectrally as a change in the fluorescence emission wavelength of an appropriately labeled biomolecule. Several tests of PORSCHA have been performed which demonstrate this principle. For example: with streptavidin as the binding biomolecule and a biotin labeled pyrene derivative, the production of the excimer emitting at 470 nm is observed. Without the streptavidin present, only the monomer emitting at 378 and 390 nm is observed. The ratio of monomer to excimer provides the concentration of unlabeled biotin in the sample. Approximately 1 ng/mL of biotin may be detected with this system using a 50 (mu) l sample (2 X 10-16 moles biotin). The principles behind PORSCHA, the results with the streptavidin/biotin system are discussed and extensions of the PORSCHA concept to antibodies as the binding partner and DNA in homogeneous assays are suggested.

  13. Flight test results of the strapdown ring laser gyro tetrad inertial navigation system

    NASA Technical Reports Server (NTRS)

    Carestia, R. A.; Hruby, R. J.; Bjorkman, W. S.

    1983-01-01

    A helicopter flight test program undertaken to evaluate the performance of Tetrad (a strap down, laser gyro, inertial navigation system) is described. The results of 34 flights show a mean final navigational velocity error of 5.06 knots, with a standard deviation of 3.84 knots; a corresponding mean final position error of 2.66 n. mi., with a standard deviation of 1.48 n. mi.; and a modeled mean position error growth rate for the 34 tests of 1.96 knots, with a standard deviation of 1.09 knots. No laser gyro or accelerometer failures were detected during the flight tests. Off line parity residual studies used simulated failures with the prerecorded flight test and laboratory test data. The airborne Tetrad system's failure--detection logic, exercised during the tests, successfully demonstrated the detection of simulated ""hard'' failures and the system's ability to continue successfully to navigate by removing the simulated faulted sensor from the computations. Tetrad's four ring laser gyros provided reliable and accurate angular rate sensing during the 4 yr of the test program, and no sensor failures were detected during the evaluation of free inertial navigation performance.

  14. A new classification system for bacterial Rieske non-heme iron aromatic ring-hydroxylating oxygenases

    PubMed Central

    Kweon, Ohgew; Kim, Seong-Jae; Baek, Songjoon; Chae, Jong-Chan; Adjei, Michael D; Baek, Dong-Heon; Kim, Young-Chang; Cerniglia, Carl E

    2008-01-01

    Background Rieske non-heme iron aromatic ring-hydroxylating oxygenases (RHOs) are multi-component enzyme systems that are remarkably diverse in bacteria isolated from diverse habitats. Since the first classification in 1990, there has been a need to devise a new classification scheme for these enzymes because many RHOs have been discovered, which do not belong to any group in the previous classification. Here, we present a scheme for classification of RHOs reflecting new sequence information and interactions between RHO enzyme components. Result We have analyzed a total of 130 RHO enzymes in which 25 well-characterized RHO enzymes were used as standards to test our hypothesis for the proposed classification system. From the sequence analysis of electron transport chain (ETC) components of the standard RHOs, we extracted classification keys that reflect not only the phylogenetic affiliation within each component but also relationship among components. Oxygenase components of standard RHOs were phylogenetically classified into 10 groups with the classification keys derived from ETC components. This phylogenetic classification scheme was converted to a new systematic classification consisting of 5 distinct types. The new classification system was statistically examined to justify its stability. Type I represents two-component RHO systems that consist of an oxygenase and an FNRC-type reductase. Type II contains other two-component RHO systems that consist of an oxygenase and an FNRN-type reductase. Type III represents a group of three-component RHO systems that consist of an oxygenase, a [2Fe-2S]-type ferredoxin and an FNRN-type reductase. Type IV represents another three-component systems that consist of oxygenase, [2Fe-2S]-type ferredoxin and GR-type reductase. Type V represents another different three-component systems that consist of an oxygenase, a [3Fe-4S]-type ferredoxin and a GR-type reductase. Conclusion The new classification system provides the following

  15. The cloning of a human ABC gene (ABC3) mapping to chromosome 16p13.3

    SciTech Connect

    Connors, T.D.; Van Raay, T.J.; Petry, L.R.

    1997-01-15

    The ATP binding cassette (ABC) transporters, or traffic ATPases, constitute a large family of proteins responsible for the transport of a wide variety of substrates across cell membranes in both prokaryotic and eukaryotic cells. We describe a human ABC protein with regions of strong homology to the recently described murine ABC1 and ABC2 transporters. The gene for this novel protein, human ABC3, maps near the polycystic kidney disease type 1 (PKD1) gene on chromosome 16p13.3. The ABC3 gene is expressed at highest levels in lung compared to other tissues. 19 refs., 3 figs.

  16. Planetary rings

    NASA Technical Reports Server (NTRS)

    Cook, A. F.

    1980-01-01

    Observations of the Rings of Saturn from the Pioneer spacecraft, discovery of the Ring of Jupiter, ground based polarimetry of the Rings of Saturn and some theoretical studies may be combined to markedly advance our understanding of the Rings of Jupiter, Saturn and Uranus. In particular, narrow rings can be self-gravitatingly stable inside Roche's limit and outside another closer limit. They can be created from a satellite which evolves across its Roche limit either by inward tidal drift or by growth of the planet by accretion. These considerations suggest that Neptune may well be surrounded by one or more narrow rings like those of Uranus.

  17. Thermodynamic black di-rings

    SciTech Connect

    Iguchi, Hideo; Mishima, Takashi

    2010-10-15

    Previously the five dimensional S{sup 1}-rotating black rings have been superposed in a concentric way by some solitonic methods, and regular systems of two S{sup 1}-rotating black rings were constructed by the authors and then Evslin and Krishnan (we called these solutions 'black di-rings'). In this place we show some characteristics of the solutions of five dimensional black di-rings, especially in thermodynamic equilibrium. After the summary of the di-ring expressions and their physical quantities, first we comment on the equivalence of the two different solution sets of the black di-rings. Then the existence of thermodynamic black di-rings is shown, in which both isothermality and isorotation between the inner black ring and the outer black ring are realized. We also give detailed analysis of peculiar properties of the thermodynamic black di-ring including discussion about a certain kind of thermodynamic stability (instability) of the system.

  18. Biocompatibility and Systemic Safety of a Novel Implantable Annuloplasty Ring for the Treatment of Mitral Regurgitation in a Minipig Model.

    PubMed

    Ramot, Yuval; Rousselle, Serge D; Yellin, Nadav; Willenz, Udi; Sabag, Itai; Avner, Avi; Nyska, Abraham

    2016-07-01

    Prosthetic annuloplasty rings are a common treatment modality for mitral regurgitation, and recently, percutaneous implantation techniques have gained popularity due to their favorable safety profile. Although in common use, biocompatibility of annuloplasty rings has been reported only sparsely in the literature, and none of these reports used the percutaneous technique of implantation. We report on the biocompatibility and the systemic safety of a novel transcatheter mitral valve annuloplasty ring (AMEND™) in 6 minipigs. This device is composed of a nitinol tube surrounded by a braided polyethylene terephthalate fabric tube. The device produced no adverse inflammatory response, showing gradual integration between the metal ring and the fabric by normal host fibrocellular response, leading to complete neoendocardium coverage. There was no evidence for adverse reactions, rejection, or intolerance in the valvular structure. In 2 animals, hemopericardium resulted from the implantation procedure, leading to right-sided cardiac insufficiency with pulmonary edema and liver congestion. The findings reported herein can serve as a case study for the expected healing pathology reactions after implantation of transcatheter mitral valve annuloplasty rings.

  19. Structural insights into ABC transporter mechanism

    SciTech Connect

    Oldham, Michael L.; Davidson, Amy L.; Chen, Jue

    2010-07-27

    ATP-binding cassette (ABC) transporters utilize the energy from ATP hydrolysis to transport substances across the membrane. In recent years, crystal structures of several ABC transporters have become available. These structures show that both importers and exporters oscillate between two conformations: an inward-facing conformation with the substrate translocation pathway open to the cytoplasm and an outward-facing conformation with the translocation pathway facing the opposite side of the membrane. In this review, conformational differences found in the structures of homologous ABC transporters are analyzed to understand how alternating-access is achieved. It appears that rigid-body rotations of the transmembrane subunits, coinciding with the opening and closing of the nucleotide-binding subunits, couples ATP hydrolysis to substrate translocation.

  20. ABC transporters, atherosclerosis and inflammation.

    PubMed

    Fitzgerald, Michael L; Mujawar, Zahedi; Tamehiro, Norimasa

    2010-08-01

    Atherosclerosis, driven by inflamed lipid-laden lesions, can occlude the coronary arteries and lead to myocardial infarction. This chronic disease is a major and expensive health burden. However, the body is able to mobilize and excrete cholesterol and other lipids, thus preventing atherosclerosis by a process termed reverse cholesterol transport (RCT). Insight into the mechanism of RCT has been gained by the study of two rare syndromes caused by the mutation of ABC transporter loci. In Tangier disease, loss of ABCA1 prevents cells from exporting cholesterol and phospholipid, thus resulting in the build-up of cholesterol in the peripheral tissues and a loss of circulating HDL. Consistent with HDL being an athero-protective particle, Tangier patients are more prone to develop atherosclerosis. Likewise, sitosterolemia is another inherited syndrome associated with premature atherosclerosis. Here mutations in either the ABCG5 or G8 loci, prevents hepatocytes and enterocytes from excreting cholesterol and plant sterols, including sitosterol, into the bile and intestinal lumen. Thus, ABCG5 and G8, which from a heterodimer, constitute a transporter that excretes cholesterol and dietary sterols back into the gut, while ABCA1 functions to export excess cell cholesterol and phospholipid during the biogenesis of HDL. Interestingly, a third protein, ABCG1, that has been shown to have anti-atherosclerotic activity in mice, may also act to transfer cholesterol to mature HDL particles. Here we review the relationship between the lipid transport activities of these proteins and their anti-atherosclerotic effect, particularly how they may reduce inflammatory signaling pathways. Of particular interest are recent reports that indicate both ABCA1 and ABCG1 modulate cell surface cholesterol levels and inhibit its partitioning into lipid rafts. Given lipid rafts may provide platforms for innate immune receptors to respond to inflammatory signals, it follows that loss of ABCA1 and ABCG1

  1. Circumbinary Ring, Circumstellar Disks, and Accretion in the Binary System UY Aurigae

    NASA Astrophysics Data System (ADS)

    Tang, Ya-Wen; Dutrey, Anne; Guilloteau, Stéphane; Piétu, Vincent; Di Folco, Emmanuel; Beck, Tracy; Ho, Paul T. P.; Boehler, Yann; Gueth, Fréderic; Bary, Jeff; Simon, Michal

    2014-09-01

    Recent exo-planetary surveys reveal that planets can orbit and survive around binary stars. This suggests that some fraction of young binary systems which possess massive circumbinary (CB) disks may be in the midst of planet formation. However, there are very few CB disks detected. We revisit one of the known CB disks, the UY Aurigae system, and probe 13CO 2-1, C18O 2-1, SO 5(6)-4(5) and 12CO 3-2 line emission and the thermal dust continuum. Our new results confirm the existence of the CB disk. In addition, the circumstellar (CS) disks are clearly resolved in dust continuum at 1.4 mm. The spectral indices between the wavelengths of 0.85 mm and 6 cm are found to be surprisingly low, being 1.6 for both CS disks. The deprojected separation of the binary is 1.''26 based on our 1.4 mm continuum data. This is 0.''07 (10 AU) larger than in earlier studies. Combining the fact of the variation of UY Aur B in R band, we propose that the CS disk of an undetected companion UY Aur Bb obscures UY Aur Ba. A very complex kinematical pattern inside the CB disk is observed due to a mixing of Keplerian rotation of the CB disk, the infall and outflow gas. The streaming gas accreting from the CB ring toward the CS disks and possible outflows are also identified and resolved. The SO emission is found to be at the bases of the streaming shocks. Our results suggest that the UY Aur system is undergoing an active accretion phase from the CB disk to the CS disks. The UY Aur B might also be a binary system, making the UY Aur a triple system.

  2. Π-Stacking Interaction between Heterocyclic Rings in a Reaction Field of Biological System

    NASA Astrophysics Data System (ADS)

    Koyimatu, Muhamad; Shimahara, Hideto; Sugimori, Kimikazu; Kawaguchi, Kazutomo; Saito, Hiroaki; Nagao, Hidemi

    Reaction fields in biological systems are given by surrounding structures where various interactions such as hydrogen bonding, van der Waals, and π-stacking interaction. However, there is no experimental method to evaluate the interaction energy. Recently, computational techniques have been used as a standard method in order to estimate the interaction energy or to verify the experimental results. Here, we are focusing on the π-electrons, p-orbitals, and conjugate systems in relation to the π-stacking interaction between heterocyclic rings in the reaction field: the active site of human carbonic anhydrase II (HCA II). The electron correlation interaction was calculated on the basis of the Møller-Plesset perturbation theory. Since the His64 has two conformations in the HCA II, the rotational motion of His64 has been used to explain the catalytic mechanism of HCA II. The calculated results indicate that the π-stacking interaction stabilizes the structure and restrict the rotational motion of His64.

  3. Neptune's rings

    NASA Technical Reports Server (NTRS)

    1999-01-01

    This 591-second exposure of the rings of Neptune were taken with the clear filter by the Voyager 2 wide-angle camera. The two main rings are clearly visible and appear complete over the region imaged. Also visible in this image is the inner faint ring and the faint band which extends smoothly from the ring roughly halfway between the two bright rings. Both of these newly discovered rings are broad and much fainter than the two narrow rings. The bright glare is due to over-exposure of the crescent on Neptune. Numerous bright stars are evident in the background. Both bright rings have material throughout their entire orbit, and are therefore continuous. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications.

  4. Vascular ring

    MedlinePlus

    ... with aberrant subclavian and left ligamentum ateriosus; Congenital heart defect - vascular ring; Birth defect heart - vascular ring ... accounts for less than 1% of all congenital heart problems. The condition occurs as often in males ...

  5. Bacitracin and nisin resistance in Staphylococcus aureus: a novel pathway involving the BraS/BraR two-component system (SA2417/SA2418) and both the BraD/BraE and VraD/VraE ABC transporters.

    PubMed

    Hiron, Aurélia; Falord, Mélanie; Valle, Jaione; Débarbouillé, Michel; Msadek, Tarek

    2011-08-01

    Two-component systems (TCSs) are key regulatory pathways allowing bacteria to adapt their genetic expression to environmental changes. Bacitracin, a cyclic dodecylpeptide antibiotic, binds to undecaprenyl pyrophosphate, the lipid carrier for cell wall precursors, effectively inhibiting peptidoglycan biosynthesis. We have identified a novel and previously uncharacterized TCS in the major human pathogen Staphylococcus aureus that we show to be essential for bacitracin and nisin resistance: the BraS/BraR system (Bacitracin resistance associated; SA2417/SA2418). The braRS genes are located immediately upstream from genes encoding an ABC transporter, accordingly designated BraDE. We have shown that the BraSR/BraDE module is a key bacitracin and nisin resistance determinant in S. aureus. In the presence of low antibiotic concentrations, BraSR activate transcription of two operons encoding ABC transporters: braDE and vraDE. We identified a highly conserved imperfect palindromic sequence upstream from the braDE and vraDE promoter sequences, essential for their transcriptional activation by BraSR, suggesting it is the likely BraR binding site. We demonstrated that the two ABC transporters play distinct and original roles in antibiotic resistance: BraDE is involved in bacitracin sensing and signalling through BraSR, whereas VraDE acts specifically as a detoxification module and is sufficient to confer bacitracin and nisin resistance when produced on its own. We show that these processes require functional BraD and VraD nucleotide-binding domain proteins, and that the large extracellular loop of VraE confers its specificity in bacitracin resistance. This is the first example of a TCS associated with two ABC transporters playing separate roles in signal transduction and antibiotic resistance. PMID:21696458

  6. Application of ring tectonic theory to Mercury and other solar system bodies

    NASA Technical Reports Server (NTRS)

    Mckinnon, W. B.

    1981-01-01

    It is pointed out that multiringed structures, by their presence or absence, provide a powerful tool for deciphering the thermal histories of the solid planets. The theory of ring tectonics considered by Melosh and McKinnon (1978) and Melosh et al. (1980) establishes the framework of that undertaking. The present investigation has the objective to apply this conceptualization in detail to the multiringed basins on Mercury, taking into account also a brief review concerning the current state of understanding of ring tectonics on the moon, Mars, earth, Ganymede, and Callisto. The small, icy satellites of Saturn are also discussed. The mechanics of multiple ring formation are related to the collapse of the transient basin cavity when the excavation depth and lithosphere thickness are comparable. Attention is given to the Caloris Basin on Mercury, the peak ring basins on Mercury, and the Argyre Basin on Mars.

  7. Communicating a New ABC: Advocacy, Partnerships, and Implementing Change.

    ERIC Educational Resources Information Center

    Ryan, Cathy

    2001-01-01

    Reiterates some key points and responds to challenges issued by the speakers to the Association for Business Communication (ABC) conference. Notes that Paula Pomerenke spoke about formalizing support of Plain Language across the continents and about ABC's continuing need to strengthen relationships with practitioners. Suggests the ABC build…

  8. Understanding the Dynamical Evolution of the Earth Radiation Belt and Ring Current Coupled System

    NASA Astrophysics Data System (ADS)

    Shprits, Yuri; Usanova, Maria; Kellerman, Adam; Drozdov, Alexander

    2016-07-01

    Modeling and understanding the ring current and radiation belt-coupled system has been a grand challenge since the beginning of the space age. In this study we show long-term simulations with a 3D Versatile Electron Radiation Belt (VERB) code of modeling the radiation belts with boundary conditions derived from observations around geosynchronous orbit. Simulations can reproduce long term variations of the electron radiation belt fluxes and show the importance of local acceleration, radial diffusion, loss to the atmosphere and loss to the magnetopause. We also present 4D VERB simulations that include convective transport, radial diffusion, pitch angle scattering and local acceleration. VERB simulations show that the lower energy inward transport is dominated by the convection and higher energy transport is dominated by the diffusive radial transport. We also show that at energies of 100s of keV, a number of processes work simultaneously, including convective transport, radial diffusion, local acceleration, loss to the loss cone and loss to the magnetopause. The results of the simulation of the March 2013 storm are compared with Van Allen Probes observations.

  9. New Psychoactive Substances: Chemistry, Pharmacology, Metabolism, and Detectability of Amphetamine Derivatives With Modified Ring Systems.

    PubMed

    Welter-Luedeke, Jessica; Maurer, Hans H

    2016-02-01

    In recent years, new amphetamine derivatives with modified ring systems were sold and consumed as new drugs of abuse. They belong together with other new drugs of abuse classes to the so-called new psychoactive substances (NPS). The chemistry, pharmacology, toxicology, metabolism, and toxicokinetics are shortly discussed of camfetamine, 3 methylphenyl-amphetamines (2-MA, 3-MA, and 4-MA), 2-methiopropamine (2-MPA), and 5-(2-aminopropyl)benzofuran (5-APB), 6-(2-aminopropyl)benzofuran (6-APB, so-called "benzofury") and their N-methyl derivatives 5-MAPB and 6-MAPB. Only a rough assessment of the pharmacology and toxicology NPS can be performed in most cases using published data of analogs, trip reports, and described clinical cases. Accordingly, they all act more or less as central nervous stimulants mainly by increasing the concentration of the neurotransmitters noradrenaline, dopamine, and serotonin (5-HT) by inducing their release and reuptake inhibition. Thus, the acute toxicity is associated with the sympathomimetic effects, such as mydriasis, hyperthermia, hypertension, tachycardia, insomnia, and anxiety. With the exception of 5- and 6-APB, these NPS were extensively metabolized by N-demethylation and/or aromatic hydroxylation catalyzed by various cytochrome P450 isoenzymes followed by partial glucuronidation and/or sulfation. For urinalysis, the unchanged drugs and/or the nor-metabolites are the main targets. PMID:26327309

  10. The New ABC of the Arts

    ERIC Educational Resources Information Center

    Tusa, John

    2007-01-01

    This article presents a new alphabet of the arts that shows how the arts world has been transformed the past five years. Beginning with "A" for assessment and continuing through "Y" for year end, the ABC of the arts illustrates the ways in which the arts world is judged, managed, and evaluated, and shows that the skill of arts management is to…

  11. Calculus ABCs: A Gateway for Freshman Calculus

    ERIC Educational Resources Information Center

    Fulton, Scott R.

    2003-01-01

    This paper describes a gateway testing program designed to ensure that students acquire basic skills in freshman calculus. Students must demonstrate they have mastered standards for "Absolutely Basic Competency"--the Calculus ABCs--in order to pass the course with a grade of C or better. We describe the background, standards, and testing program.…

  12. The ABC's of Learning in Infancy.

    ERIC Educational Resources Information Center

    Saunders, Minta M.

    Learning in infancy is based on activity, beginnings, and curiosity, the so-called ABC's. Earliest behavior consists of mass activity, the period from birth to 24 months of sensory-motor development which provides the foundation for all future learning. Adults must provide space, toys, and affectionate care to help infants proceed through…

  13. The ABCs of Managing Teacher Stress.

    ERIC Educational Resources Information Center

    Nagel, Liza; Brown, Sheri

    2003-01-01

    Describes stress management for teachers and presents strategies that teachers can use to lessen the impact of stress. Outlines the ABCs of stress: Acknowledge, Behavior Modification, and Communication. Notes that stress can motivate teachers to explore new instructional strategies, adopt innovative approaches to increasing student motivation, and…

  14. Sustained delivery of chondroitinase ABC by poly(propylene carbonate)-chitosan micron fibers promotes axon regeneration and functional recovery after spinal cord hemisection.

    PubMed

    Ni, Shilei; Xia, Tongliang; Li, Xingang; Zhu, Xiaodong; Qi, Hongxu; Huang, Shanying; Wang, Jiangang

    2015-10-22

    We describe the sustained delivery of chondroitinase ABC (ChABC) in the hemisected spinal cord using polypropylene carbonate (PPC) electrospun fibers with chitosan (CS) microspheres as a vehicle. PPC and ChABC-loaded CS microspheres were mixed with acetonitrile, and micron fibers were generated by electrospinning. ChABC release was assessed in vitro with high-performance liquid chromatography (HPLC) and revealed stabilized and prolonged release. Moreover, the released ChABC showed sustained activity. PPC-CS micron fibers with or without ChABC were then implanted into a hemisected thoracic spinal cord. In the following 4 weeks, we examined functional recovery and performed immunohistochemical analyses. We found that sustained delivery of ChABC promoted axon sprouting and functional recovery and reduced glial scarring; PPC-CS micron fibers without ChABC did not show these effects. The present findings suggest that PPC-CS micron fibers containing ChABC are a feasible option for spinal cord injury treatment. Furthermore, the system described here may be useful for local delivery of other therapeutic agents. PMID:26315376

  15. A MULTIPLE TESTING OF THE ABC METHOD AND THE DEVELOPMENT OF A SECOND GENERATION MODEL. PART I, PRELIMINARY DISCUSSIONS OF METHODOLOGY. SUPPLEMENT, COMPUTER PROGRAMS OF THE HDL INFORMATION SYSTEMS.

    ERIC Educational Resources Information Center

    ALTMANN, BERTHOLD; BROWN, WILLIAM G.

    THE FIRST-GENERATION APPROACH BY CONCEPT (ABC) STORAGE AND RETRIEVAL METHOD, A METHOD WHICH UTILIZES AS A SUBJECT APPROACH APPROPRIATE STANDARDIZED ENGLISH-LANGUAGE STATEMENTS PROCESSED AND PRINTED IN A PERMUTED INDEX FORMAT, UNDERWENT A PERFORMANCE TEST, THE PRIMARY OBJECTIVE OF WHICH WAS TO SPOT DEFICIENCIES AND TO DEVELOP A SECOND-GENERATION…

  16. The dynamics of magnetic flux rings

    NASA Technical Reports Server (NTRS)

    Deluca, E. E.; Fisher, G. H.; Patten, B. M.

    1993-01-01

    The evolution of magnetic fields in the presence of turbulent convection is examined using results of numerical simulations of closed magnetic flux tubes embedded in a steady 'ABC' flow field, which approximate some of the important characteristics of a turbulent convecting flow field. Three different evolutionary scenarios were found: expansion to a steady deformed ring; collapse to a compact fat flux ring, separated from the expansion type of behavior by a critical length scale; and, occasionally, evolution toward an advecting, oscillatory state. The work suggests that small-scale flows will not have a strong effect on large-scale, strong fields.

  17. Comparative investigation of the energetic ion spectra comprising the magnetospheric ring currents of the solar system

    PubMed Central

    Mauk, B H

    2014-01-01

    Investigated here are factors that control the intensities and shapes of energetic ion spectra that make up the ring current populations of the strongly magnetized planets of the solar system, specifically those of Earth, Jupiter, Saturn, Uranus, and Neptune. Following a previous and similar comparative investigation of radiation belt electrons, we here turn our attention to ions. Specifically, we examine the possible role of the differential ion Kennel-Petschek limit, as moderated by Electromagnetic Ion Cyclotron (EMIC) waves, as a standard for comparing the most intense ion spectra within the strongly magnetized planetary magnetospheres. In carrying out this investigation, the substantial complexities engendered by the very different ion composition distributions of these diverse magnetospheres must be addressed, given that the dispersion properties of the EMIC waves are strongly determined by the ion composition of the plasmas within which the waves propagate. Chosen for comparison are the ion spectra within these systems that are the most intense observed, specifically at 100 keV and 1 MeV. We find that Earth and Jupiter are unique in having their most intense ion spectra likely limited and sculpted by the Kennel-Petschek process. The ion spectra of Saturn, Uranus, and Neptune reside far below their respective limits and are likely limited by interactions with gas and dust (Saturn) and by the absence of robust ion acceleration processes (Uranus and Neptune). Suggestions are provided for further testing the efficacy of the differential Kennel-Petschek limit for ions using the Van Allen Probes. PMID:26167438

  18. Prediscovery evidence of planetary rings

    NASA Technical Reports Server (NTRS)

    Mclaughlin, W. I.

    1980-01-01

    The discoveries of the Uranian and Jovian ring systems were surprising events to most of the scientific community. However, as far back as 1787 reports of observations of rings about a planet other than Saturn were made; Herschel, the discoverer of Uranus, thought he had detected rings about that planet on several occasions. Although Herschel's observations were almost certainly due to defects in the optical system of his telescope, several valid observations and predictions have been made in the last two hundred years. This paper focuses on such prediscovery evidence for the Uranian and Jovian rings and for the newly designated F ring of Saturn. Some new work of the author on the structure of the Saturnian rings is included which is relevant to the F ring. The prospects for rings about Neptune and Pluto and a ring close to the Sun are also reviewed. The relevance of the prediscovery evidence to aspects of scientific methodology is discussed.

  19. ABC transporters in fish species: a review

    PubMed Central

    Ferreira, Marta; Costa, Joana; Reis-Henriques, Maria A.

    2014-01-01

    ATP-binding cassette (ABC) proteins were first recognized for their role in multidrug resistance (MDR) in chemotherapeutic treatments, which is a major impediment for the successful treatment of many forms of malignant tumors in humans. These proteins, highly conserved throughout vertebrate species, were later related to cellular detoxification and accounted as responsible for protecting aquatic organisms from xenobiotic insults in the so-called multixenobiotic resistance mechanism (MXR). In recent years, research on these proteins in aquatic species has highlighted their importance in the detoxification mechanisms in fish thus it is necessary to continue these studies. Several transporters have been pointed out as relevant in the ecotoxicological context associated to the transport of xenobiotics, such as P-glycoproteins (Pgps), multidrug-resistance-associated proteins (MRPs 1-5) and breast cancer resistance associated protein (BCRP). In mammals, several nuclear receptors have been identified as mediators of phase I and II metabolizing enzymes and ABC transporters. In aquatic species, knowledge on co-regulation of the detoxification mechanism is scarce and needs to be addressed. The interaction of emergent contaminants that can act as chemosensitizers, with ABC transporters in aquatic organisms can compromise detoxification processes and have population effects and should be studied in more detail. This review intends to summarize the recent advances in research on MXR mechanisms in fish species, focusing in (1) regulation and functioning of ABC proteins; (2) cooperation with phase I and II biotransformation enzymes; and (3) ecotoxicological relevance and information on emergent pollutants with ability to modulate ABC transporters expression and activity. Several lines of evidence are clearly suggesting the important role of these transporters in detoxification mechanisms and must be further investigated in fish to underlay the mechanism to consider their use as

  20. Voyager 2 and the Uranian rings

    SciTech Connect

    Porco, C.C.

    1986-12-01

    Voyager 2 data on the Uranian disk system are presented and examined. The disk system consists of nine narrow rings, ranging in width from a few km to about 100 km. The Uranian rings are eccentric, inclined to the planet's equatorial plane, and precessing. The Uranian ring characteristics detected in the Voyager data are described and compared with those of the Saturn rings. The origin and maintenance of the rings are discussed, and the particle distribution in the ring system is studied.

  1. Improvement of a serodiagnostic strategy for foot-and-mouth disease virus surveillance in cattle under systematic vaccination: a combined system of an indirect ELISA-3ABC with an enzyme-linked immunoelectrotransfer blot assay.

    PubMed

    Bergmann, I E; Malirat, V; Neitzert, E; Beck, E; Panizzutti, N; Sánchez, C; Falczuk, A

    2000-01-01

    Foot-and-mouth disease (FMD) recombinant non-capsideal viral antigens 3A, 3B, 2C, 3D and 3ABC were assessed individually in an indirect enzyme-linked immunosorbent assay (I-ELISA) for their ability to screen for persistent infection-specific antibodies in cattle, regardless of vaccination condition. Results of sequential serum samples from non-vaccinated animals with experimentally induced persistent infection, and their correlation with virus isolation, indicated that the polypeptides 3A, 3B and 3ABC showed the most adequate characteristics for further field studies. Reliable performance of the I-ELISA with the selected antigen 3ABC was indicated by the distinct patterns observed for the frequency distribution values of naive and true positive samples. For regularly vaccinated livestock, a clear negative profile was proved in samples from regions without recent history of FMD. In contrast, at 90 and 900 days post-outbreak, coexistence of a positive and a negative population was established. These findings indicated that, irrespective of vaccination, the test allowed a classification of the herd-disease status. A high degree of agreement was observed between I-ELISA-3ABC and EITB results for clearly reactive and non-reactive sera. For samples with reactivity values close to that of the cut-off, the EITB profiles upheld the definition of the infection condition. On this basis, screening by I-ELISA-3ABC, together with confirmation of suspect or positive samples by EITB is proposed as an adequate and accurate approach for large-scale epidemiological surveillance.

  2. Improved avidin-biotin-peroxidase complex (ABC) staining.

    PubMed

    Cattoretti, G; Berti, E; Schiró, R; D'Amato, L; Valeggio, C; Rilke, F

    1988-02-01

    A considerable intensification of the avidin-biotin-peroxidase complex staining system (ABC) was obtained by sequentially overlaying the sections to be immunostained with an avidin-rich and a biotin-rich complex. Each sequential addition contributed to the deposition of horseradish peroxidase on the immunostained site and allowed the subsequent binding of a complementary complex. With this technique a higher dilution of the antisera could be used and minute amounts of antigen masked by the fixative could be demonstrated on paraffin sections.

  3. The ABC transporter HrtAB confers resistance to hemin toxicity and is regulated in a hemin-dependent manner by the ChrAS two-component system in Corynebacterium diphtheriae.

    PubMed

    Bibb, Lori A; Schmitt, Michael P

    2010-09-01

    Corynebacterium diphtheriae, the causative agent of the severe respiratory disease diphtheria, utilizes hemin and hemoglobin as iron sources for growth in iron-depleted environments. Because of the toxicity of high levels of hemin and iron, these compounds are often tightly regulated in bacterial systems. In this report, we identify and characterize the C. diphtheriae hrtAB genes, which encode a putative ABC type transporter involved in conferring resistance to the toxic effects of hemin. Deletion of the hrtAB genes in C. diphtheriae produced increased sensitivity to hemin, which was complemented by a plasmid harboring the cloned hrtAB locus. The HrtAB system was not involved in the uptake and use of hemin as an iron source. The hrtAB genes are located on the C. diphtheriae genome upstream from the chrSA operon, which encodes a previously characterized two-component signal transduction system that regulates gene expression in a heme-dependent manner. The hrtB promoter is activated by the ChrAS system in the presence of hemin or hemoglobin, and mutations in the chrSA genes abolish heme-activated expression from the hrtB promoter. It was also observed that transcription from the hrtB promoter is reduced in a dtxR deletion mutant, suggesting that DtxR is required for optimal expression of hrtAB. Previous studies proposed that the ChrS sensor kinase may be responsive to an environmental signal, such as hemin. We show that specific point mutations in the ChrS N-terminal transmembrane domain result in a reduced ability to activate the hrtB promoter in the presence of a heme source, suggesting that this putative sensor region is essential for the detection of a signal produced in response to hemin exposure. This study shows that the HrtAB system is required for protection from hemin toxicity and that expression of the hrtAB genes is regulated by the ChrAS two-component system. This study demonstrates a direct correlation between the detection of heme or a heme

  4. Saturn's Rings, the Yarkovsky Effects, and the Ring of Fire

    NASA Technical Reports Server (NTRS)

    Rubincam, David Parry

    2004-01-01

    The dimensions of Saturn's A and B rings may be determined by the seasonal Yarkovsky effect and the Yarkovsky-Schach effect; the two effects confine the rings between approximately 1.68 and approximately 2.23 Saturn radii, in reasonable agreement with the observed values of 1.525 and 2.267. The C ring may be sparsely populated because its particles are transients on their way to Saturn; the infall may create a luminous Ring of Fire around Saturn's equator. The ring system may be young: in the past heat flow from Saturn's interior much above its present value would not permit rings to exist.

  5. Intramolecular [2 + 2] photocycloaddition/thermal fragmentation: formally "allowed" and "forbidden"pathways toward 5-8-5 ring systems.

    PubMed

    Bader, Scott J; Snapper, Marc L

    2005-02-01

    The thermal fragmentation of highly functionalized, linear polycyclobutanes with a cis,syn,cis-relative stereochemistry is shown to offer a rapid entry into the dicyclopenta[a,d]cyclooctenyl (5-8-5) ring system. The thermolysis of polyfused cyclobutanes with a cis,syn,cis- or a cis,anti,cis-relationship proceeds in a formally "symmetry-allowed" manner through the intermediacy of a cis,trans-cyclooctadiene. When a bridging tether used to establish the cis,syn,cis-stereochemistry in the intramolecular [2 + 2] photocyclization is present in the thermolysis step, however, the result of a formally "symmetry-forbidden" fragmentation is observed yielding cis,cis-cyclooctadiene-containing 5-8-5 products. In general, the stereochemical observations noted in these fragmentations offer new opportunities for accessing a variety of stereochemical relationships in these 5-8-5 ring systems.

  6. Radiochemical separations by the ring-oven technique-IV The system (144)Ce/(144)Pr.

    PubMed

    Klockow, D; Böhmer, R G

    1969-08-01

    By using filter papers impregnated with a manganese oxide hydrate having an average oxidation number of + 3, it is possible to separate (144)Pr from (144)Ce rapidly by the ring-oven technique. With 0.06-0.07M trichloracetic acid as wash-solution, the daughter nuclide can be concentrated in the ring zone with 80-90% yield and decontamination factors > 10(3). The half-life of the separated (144)Pr was found to be 17.60 +/- 0.05 min. The behaviour of other fission nuclides under the same conditions was also investigated. PMID:18960624

  7. Redesign of solid rocket booster/external tank attachment ring for the space transportation system

    NASA Technical Reports Server (NTRS)

    Mccomb, Harvey G., Jr. (Compiler)

    1987-01-01

    An improved design concept is presented for the Space Shuttle solid rocket booster (SRB)/external tank (ET) attachment ring structural component. This component picks up three struts which attach the aft end of each SRB to the ET. The concept is a partial ring with carefully tapered ends to distribute fastener loads safely into the SRB. Extensive design studies and analyses were performed to arrive at the concept. Experiments on structural elements were performed to determine material strength and stiffness characteristics. Materials and fabrication studies were conducted to determine acceptable tolerances for the design concept. An overview is provided of the work along with conclusions and major recommendations.

  8. Merging tree ring chronologies and climate system model simulated temperature by optimal interpolation algorithm in North America

    NASA Astrophysics Data System (ADS)

    Chen, Xin; Xing, Pei; Luo, Yong; Zhao, Zongci; Nie, Suping; Huang, Jianbin; Wang, Shaowu; Tian, Qinhua

    2015-04-01

    A new dataset of annual mean surface temperature has been constructed over North America in recent 500 years by performing optimal interpolation (OI) algorithm. Totally, 149 series totally were screened out including 69 tree ring width (MXD) and 80 tree ring width (TRW) chronologies are screened from International Tree Ring Data Bank (ITRDB). The simulated annual mean surface temperature derives from the past1000 experiment results of Community Climate System Model version 4 (CCSM4). Different from existing research that applying data assimilation approach to (General Circulation Models) GCMs simulation, the errors of both the climate model simulation and tree ring reconstruction were considered, with a view to combining the two parts in an optimal way. Variance matching (VM) was employed to calibrate tree ring chronologies on CRUTEM4v, and corresponding errors were estimated through leave-one-out process. Background error covariance matrix was estimated from samples of simulation results in a running 30-year window in a statistical way. Actually, the background error covariance matrix was calculated locally within the scanning range (2000km in this research). Thus, the merging process continued with a time-varying local gain matrix. The merging method (MM) was tested by two kinds of experiments, and the results indicated standard deviation of errors can be reduced by about 0.3 degree centigrade lower than tree ring reconstructions and 0.5 degree centigrade lower than model simulation. During the recent Obvious decadal variability can be identified in MM results including the evident cooling (0.10 degree per decade) in 1940-60s, wherein the model simulation exhibit a weak increasing trend (0.05 degree per decade) instead. MM results revealed a compromised spatial pattern of the linear trend of surface temperature during a typical period (1601-1800 AD) in Little Ice Age, which basically accorded with the phase transitions of the Pacific decadal oscillation (PDO) and

  9. Using a double-frequency RF system to facilitate on-axis beam accumulation in a storage ring

    NASA Astrophysics Data System (ADS)

    Jiang, B. C.; Zhao, Z. T.; Tian, S. Q.; Zhang, M. Z.; Zhang, Q. L.

    2016-04-01

    An on-axis injection scheme using a double-frequency RF system in a storage ring with small dynamic aperture is proposed. By altering RF voltages, empty RF buckets can be created which will be used for on-axis injection. After bunches are injected, a reverse RF voltage altering process is performed and the injected bunches can be longitudinally dumped to the main RF buckets. The scheme allows reaping the advantages of the on-axis injection while still performing accumulation.

  10. Neptune may have polar rings

    NASA Astrophysics Data System (ADS)

    Dobrovolskis, A. R.; Steiman-Cameron, T. Y.; Borderies, N. J.

    1989-08-01

    Perturbations from Neptune's highly inclined satellite Triton can maintain rings passing nearly over Neptune's poles. These hypothetical polar rings are nearly perpendicular to Triton's orbit as well, and lie within several degrees of the plane of Voyager II's trajectory through the Neptunian system. Polar rings can coexist with equatorial rings at different radii. A randomly oriented torus of debris around Neptune has a probability of several percent to settle into a polar ring. Voyager II stands a significant chance of encountering a polar ring.

  11. [The non-contact effect of substances containing benzene rings and heterocycles on biological systems].

    PubMed

    Frolov, Iu P

    2001-01-01

    It was found that some substances containing benzolic rings and heterocyclic structures have a noncontact effect on biosystems. Some results of experiments dealing with the noncontact effect on enzyme molecules, cells, and uni- and multicellular organisms are presented. Factors influencing the efficiency of the noncontact effect were revealed. PMID:11605403

  12. Application of edge-based finite elements and vector ABCs in 3D scattering

    NASA Technical Reports Server (NTRS)

    Chatterjee, A.; Jin, J. M.; Volakis, John L.

    1992-01-01

    A finite element absorbing boundary condition (FE-ABC) solution of the scattering by arbitrary 3-D structures is considered. The computational domain is discretized using edge-based tetrahedral elements. In contrast to the node-based elements, edge elements can treat geometries with sharp edges, are divergence-less, and easily satisfy the field continuity condition across dielectric interfaces. They do, however, lead to a higher unknown count but this is balanced by the greater sparsity of the resulting finite element matrix. Thus, the computation time required to solve such a system iteratively with a given degree of accuracy is less than the traditional node-based approach. The purpose is to examine the derivation and performance of the ABC's when applied to 2-D and 3-D problems and to discuss the specifics of our FE-ABC implementation.

  13. Loss of plastoglobule kinases ABC1K1 and ABC1K3 causes conditional degreening, modified prenyl-lipids, and recruitment of the jasmonic acid pathway

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plastoglobules (PGs) are plastid lipid-protein particles. This study examines the function of PG-localized kinases ABC1K1 and ABC1K3 in Arabidopsis thaliana. Several lines of evidence suggested that ABC1K1 and ABC1K3 form a protein complex. Null mutants for both genes (abc1k1 and abc1k3) and the dou...

  14. Three ways to learn the ABCs.

    PubMed

    Ng, M; Yanofsky, M F

    2000-02-01

    The ABC model of flower development represents a milestone in explaining how the fate of emerging floral organ primordia is specified. This model states that organ identity is specified by different combinations of the activities of the A, B and C class homeotic genes. In spite of the remarkable simplicity of this model, the complex regulatory interactions that establish the initial pattern of A, B and C gene activity have yet to be fully explained. It has been shown that the LEAFY gene functions early to promote flower meristem identity, and that it is subsequently required for the normal expression of the ABC genes. Recently, LEAFY has been identified as an immediate upstream regulator of the floral homeotic genes, thus opening up an avenue to examine the transcriptional interactions that underlie floral patterning. PMID:10679448

  15. Effect of body temperature on chondroitinase ABC's ability to cleave chondroitin sulfate glycosaminoglycans.

    PubMed

    Tester, Nicole J; Plaas, Anna H; Howland, Dena R

    2007-04-01

    Chondroitinase ABC (Ch'ase ABC) is a bacterial lyase that degrades chondroitin sulfate (CS), dermatan sulfate, and hyaluronan glycosaminoglycans (GAGs). This enzyme has received significant attention as a potential therapy for promoting central nervous system and peripheral nervous system repair based on its degradation of CS GAGs. Determination of the stability of Ch'ase ABC activity at temperatures equivalent to normal (37 degrees C) and elevated (39 degrees C) body temperatures is important for optimizing its clinical usage. We report here data obtained from examining enzymatic activity at these temperatures across nine lots of commercially available protease-free Ch'ase ABC. CS GAG degrading activity was assayed by using 1) immunohistochemical detection of unsaturated disaccharide stubs generated by digestion of proteoglycans in tissue sections and 2) fluorophore-assisted carbohydrate electrophoresis (FACE) and/or high-performance liquid chromatography (HPLC) to separate and quantify unsaturated disaccharide digestion products. Our results indicate that there is a significant effect of lot and time on enzymatic thermostability. Average enzymatic activity is significantly decreased at 1 and 3 days at 39 degrees C and 37 degrees C, respectively. Furthermore, the average activity seen after 1 day was significantly different between the two temperatures. Addition of bovine serum albumin as a stabilizer significantly preserved enzymatic activity at 1 day, but not 3 days, at 39 degrees C. These results show that the CS GAG degrading activity of Ch'ase ABC is significantly decreased with incubation at body temperature over time and that all lots do not show equal thermostability. These findings are important for the design and interpretation of experimental and potential clinical studies involving Ch'ase ABC.

  16. Adhesion to chondroitinase ABC treated dentin

    PubMed Central

    Mazzoni, Annalisa; Pashley, David H.; Ruggeri, Alessandra; Vita, Francesca; Falconi, Mirella; Di Lenarda, Roberto; Breschi, Lorenzo

    2013-01-01

    Dentin bonding relies on complete resin impregnation throughout the demineralised hydrophilic collagen mesh. Chondroitin sulphate-glycosaminoglycans are claimed to regulate the three-dimensional arrangement of the dentin organic matrix and its hydrophilicity. The aim of this study was to investigate bond strength of two etch-and-rinse adhesives to chondroitinase ABC treated dentin. Human extracted molars were treated with chondroitinase ABC and a double labelling immunohistochemical technique was applied to reveal type I collagen and chondroitin 4/6 sulphate distribution under field emission in-lens scanning electron microscope. The immunohistochemical technique confirmed the effective removal of chondroitin 4/6 sulphate after the enzymatic treatment. Dentin surfaces exposed to chondroitinase ABC and untreated specimens prepared on untreated acid-etched dentin were bonded with Adper Scotchbond Multi-Purpose or Prime & Bond NT. Bonded specimens were submitted to microtensile testing and nanoleakage interfacial analysis under transmission electron microscope. Increased mean values of microtensile bond strength and reduced nanoleakage expression were found for both adhesives after chondroitinase ABC treatment of the dentin surface. Adper Scotchbond Multi-Purpose increased its bond strength about 28%, while bonding made with Prime & Bond NT almost doubled (92% increase) compared to untreated specimens. This study supports the hypothesis that adhesion can be enhanced by removal of chondroitin 4/6 sulphate and dermatan sulphate, probably due to a reduced amount of water content and enlarged interfibrillar spaces. Further studies should validate this hypothesis investigating the stability of chondroitin 4/6 and dermatan sulphate-depleted dentin bonded interface over time. PMID:18161809

  17. Analyzing health care operations using ABC.

    PubMed

    Ross, Thomas K

    2004-01-01

    The evolution of health care created a climate in which cost was subordinate to medical treatment. Current reimbursement constraints have increased the need for providers to be cost conscious, but they have discovered that current accounting practices do not provide the appropriate information to determine the cost of service or make decisions. This article argues that activity-based costing (ABC) can bridge the gap between the medical and financial communities and provide a foundation for performance improvement. PMID:15151193

  18. Earth: A Ringed Planet?

    NASA Astrophysics Data System (ADS)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  19. Synthesis and action on the central nervous system of mescaline analogues containing piperazine or homopiperazine rings.

    PubMed

    Majchrzak, M W; Kotełko, A; Guryn, R; Lambert, J B; Szadowska, A; Kowalczyk, K

    1983-03-01

    Structural juxtaposition of the 3,4,5-trimethoxyphenyl group in the same molecule with a piperazine or homopiperazine ring has been realized in a series of mescaline analogues (I-IV) as part of an investigation into the pharmacological properties of the seven-membered perhydro-1,4-diazepines (homopiperazines). The analogous six-membered piperazines were synthesized and tested as reference substances to determine whether the seven-membered ring conveyed special properties. A variety of pharmacological tests of action on the CNS showed that replacement of the amino group in mescaline by the heterocycles significantly alters the biological activity. In particular, both the piperazine and the homopiperazine derivatives displayed sedative activity to about the same extent.

  20. Efficient Biosynthesis of Fungal Polyketides Containing the Dioxabicyclo-octane Ring System.

    PubMed

    Mao, Xu-Ming; Zhan, Zha-Jun; Grayson, Matthew N; Tang, Man-Cheng; Xu, Wei; Li, Yong-Quan; Yin, Wen-Bing; Lin, Hsiao-Ching; Chooi, Yit-Heng; Houk, K N; Tang, Yi

    2015-09-23

    Aurovertins are fungal polyketides that exhibit potent inhibition of adenosine triphosphate synthase. Aurovertins contain a 2,6-dioxabicyclo[3.2.1]octane ring that is proposed to be derived from a polyene precursor through regioselective oxidations and epoxide openings. In this study, we identified only four enzymes required to produce aurovertin E. The core polyketide synthase produces a polyene α-pyrone. Following pyrone O-methylation by a methyltransferase, a flavin-dependent mono-oxygenase and an epoxide hydrolase can iteratively transform the terminal triene portion of the precursor into the dioxabicyclo[3.2.1]octane scaffold. We demonstrate that a tetrahydrofuranyl polyene is the first stable intermediate in the transformation, which can undergo epoxidation and anti-Baldwin 6-endo-tet ring opening to yield the cyclic ether product. Our results further demonstrate the highly concise and efficient ways in which fungal biosynthetic pathways can generate complex natural product scaffolds. PMID:26340065

  1. Efficient Biosynthesis of Fungal Polyketides Containing the Dioxabicyclo-octane Ring System.

    PubMed

    Mao, Xu-Ming; Zhan, Zha-Jun; Grayson, Matthew N; Tang, Man-Cheng; Xu, Wei; Li, Yong-Quan; Yin, Wen-Bing; Lin, Hsiao-Ching; Chooi, Yit-Heng; Houk, K N; Tang, Yi

    2015-09-23

    Aurovertins are fungal polyketides that exhibit potent inhibition of adenosine triphosphate synthase. Aurovertins contain a 2,6-dioxabicyclo[3.2.1]octane ring that is proposed to be derived from a polyene precursor through regioselective oxidations and epoxide openings. In this study, we identified only four enzymes required to produce aurovertin E. The core polyketide synthase produces a polyene α-pyrone. Following pyrone O-methylation by a methyltransferase, a flavin-dependent mono-oxygenase and an epoxide hydrolase can iteratively transform the terminal triene portion of the precursor into the dioxabicyclo[3.2.1]octane scaffold. We demonstrate that a tetrahydrofuranyl polyene is the first stable intermediate in the transformation, which can undergo epoxidation and anti-Baldwin 6-endo-tet ring opening to yield the cyclic ether product. Our results further demonstrate the highly concise and efficient ways in which fungal biosynthetic pathways can generate complex natural product scaffolds.

  2. Analysis and design modifications for upgrade of storage ring bump pulse system driving the injection bump magnets at the ALS

    SciTech Connect

    Stover, G.D.

    1995-04-01

    A fast (4.0 ms half period) resonant discharge pulse system, using SCRs, was designed and constructed to drive the injection bump magnet system at the Advanced Light Source (ALS). The commissioning process revealed a high frequency resonance (T = 800 NS) superimposed on the driver discharge wave form. In addition, the peak amplitude of the magnet load recovery current exceeded design specifications. A SPICE analysis confirmed the suspected mechanisms for the parasitic ringing and the excessive load current {open_quotes}undershoot{close_quotes}. This paper will address the subsequent analysis, measurements, and modifications carried out during the maintenance shutdown in June 1993.

  3. The first transannular [4+3] cycloaddition reaction: synthesis of the ABCD ring structure of cortistatins.

    PubMed

    Craft, Derek T; Gung, Benjamin W

    2008-10-01

    A 14-membered macrocycle with an allene and a furan strategically located at across the ring from each other is synthesized using an allene ring closing metathesis reaction. Upon treatment of the macrocycle with a catalytic amount of Pd(OAc)(2) and other additives, the first transannular [4+3] cycloaddition occurred to yield 37% of a tetracyclic compound containing the ABC ring structure of the natural products cortistatins.

  4. The ABCs of Data Dictionaries

    ERIC Educational Resources Information Center

    Gould, Tate; Nicholas, Amy; Blandford, William; Ruggiero, Tony; Peters, Mary; Thayer, Sara

    2014-01-01

    This overview of the basic components of a data dictionary is designed to educate and inform IDEA Part C and Part B 619 state staff about the purpose and benefits of having up-to-date data dictionaries for their data systems. This report discusses the following topics: (1) What Is a Data Dictionary?; (2) Why Is a Data Dictionary Needed and How Can…

  5. Jupiter's Gossamer Rings Explained.

    NASA Astrophysics Data System (ADS)

    Hamilton, D. P.

    2003-05-01

    Over the past several years, Galileo measurements and groundbased imaging have drastically improved our knowledge of Jupiter's faint ring system. We now recognize that the ring consists of four components: a main ring 7000km wide, whose inner edge blossoms into a vertically-extended halo, and a pair of more tenuous Gossamer rings, one associated with each of the small moons Thebe and Amalthea. When viewed edge on, the Gossamer rings appear as diaphanous disks whose thicknesses agree with the vertical excursions of the inclined satellites from the equatorial plane. In addition, the brightness of each Gossamer ring drops off sharply outside the satellite orbits. These correlations allowed Burns etal (1999, Science, 284, 1146) to argue convincingly that the satellites act as sources of the dusty ring material. In addition, since most material is seen inside the orbits of the source satellites, an inwardly-acting dissipative force such as Poynting-Robertson drag is implicated. The most serious problem with this simple and elegant picture is that it is unable to explain the existence of a faint swath of material that extends half a jovian radius outward from Thebe. A key constraint is that this material has the same thickness as the rest of the Thebe ring. In this work, we identify the mechanism responsible for the outward extension: it is a shadow resonance, first investigated by Horanyi and Burns (1991, JGR, 96, 19283). When a dust grain enters Jupiter's shadow, photoelectric processes shut down and the grain's electric charge becomes more negative. The electromagnetic forces associated with the varying charge cause periodic oscillations in the orbital eccentricity and semimajor axis as the orbital pericenter precesses. This results in a ring which spreads both inward and outward of its source satellite while preserving its vertical thickness - just as is observed for the Thebe ring. Predictions of the model are: i) gaps of micron-sized material interior to Thebe and

  6. IMG-ABC: A Knowledge Base To Fuel Discovery of Biosynthetic Gene Clusters and Novel Secondary Metabolites

    PubMed Central

    Hadjithomas, Michalis; Chen, I-Min Amy; Chu, Ken; Ratner, Anna; Palaniappan, Krishna; Szeto, Ernest; Huang, Jinghua; Reddy, T. B. K.; Cimermančič, Peter; Fischbach, Michael A.; Ivanova, Natalia N.; Markowitz, Victor M.

    2015-01-01

    ABSTRACT In the discovery of secondary metabolites, analysis of sequence data is a promising exploration path that remains largely underutilized due to the lack of computational platforms that enable such a systematic approach on a large scale. In this work, we present IMG-ABC (https://img.jgi.doe.gov/abc), an atlas of biosynthetic gene clusters within the Integrated Microbial Genomes (IMG) system, which is aimed at harnessing the power of “big” genomic data for discovering small molecules. IMG-ABC relies on IMG’s comprehensive integrated structural and functional genomic data for the analysis of biosynthetic gene clusters (BCs) and associated secondary metabolites (SMs). SMs and BCs serve as the two main classes of objects in IMG-ABC, each with a rich collection of attributes. A unique feature of IMG-ABC is the incorporation of both experimentally validated and computationally predicted BCs in genomes as well as metagenomes, thus identifying BCs in uncultured populations and rare taxa. We demonstrate the strength of IMG-ABC’s focused integrated analysis tools in enabling the exploration of microbial secondary metabolism on a global scale, through the discovery of phenazine-producing clusters for the first time in Alphaproteobacteria. IMG-ABC strives to fill the long-existent void of resources for computational exploration of the secondary metabolism universe; its underlying scalable framework enables traversal of uncovered phylogenetic and chemical structure space, serving as a doorway to a new era in the discovery of novel molecules. PMID:26173699

  7. Particle properties and processes in Uranus' rings

    NASA Technical Reports Server (NTRS)

    Esposito, L. W.; Brahic, A.; Burns, J. A.; Marouf, Essam A.

    1991-01-01

    The particle properties and processes in the Uranian rings are analyzed from Voyager observations and ground-based data. Occultation observations of the epsilon ring are interpreted to yield an effective size of the ring particles that exceeds 70 cm, a surface mass density that exceeds 80 g/sq cm, and a ring vertical thickness greater than tens of meters for solid ice particles. The particles forming the classic rings are dark and gray, with albedo of 0.014 +/-0.004. It is argued that the small amount of dust that exists in the classical rings and between the rings in bands is created by erosion of ring particles and unseen satellites resulting from collisions and micrometeoroid bombardment. As proposed for regions of the other known ring systems, new ring material can be continually created by the destruction of small moons near the rings, which may explain the youthful appearance of the Uranian rings.

  8. Routes to complex dynamics in a ring of unidirectionally coupled systems.

    PubMed

    Perlikowski, P; Yanchuk, S; Wolfrum, M; Stefanski, A; Mosiolek, P; Kapitaniak, T

    2010-03-01

    We study the dynamics of a ring of unidirectionally coupled autonomous Duffing oscillators. Starting from a situation where the individual oscillator without coupling has only trivial equilibrium dynamics, the coupling induces complicated transitions to periodic, quasiperiodic, chaotic, and hyperchaotic behavior. We study these transitions in detail for small and large numbers of oscillators. Particular attention is paid to the role of unstable periodic solutions for the appearance of chaotic rotating waves, spatiotemporal structures, and the Eckhaus effect for a large number of oscillators. Our analytical and numerical results are confirmed by a simple experiment based on the electronic implementation of coupled Duffing oscillators. PMID:20370266

  9. Synthesis, Characterization, and Electronic Structures of Porphyrins Fused with Polycyclic Aromatic Ring Systems.

    PubMed

    Okujima, Tetsuo; Mack, John; Nakamura, Jun; Kubheka, Gugu; Nyokong, Tebello; Zhu, Hua; Komobuchi, Naoki; Ono, Noboru; Yamada, Hiroko; Uno, Hidemitsu; Kobayashi, Nagao

    2016-10-01

    A series of porphyrins fused with acenaphthylene, phenanthroline, and benzofluoranthene polycyclic aromatic rings were prepared by means of a 3+1 porphyrin synthesis approach and subsequent retro-Diels-Alder reaction of bicyclo[2.2.2]octadiene-fused precursors. Analysis of the magnetic circular dichroism spectra and the results of time-dependent DFT calculations are used to identify the reasons for the trends observed in the wavelengths and relative intensities of the Q bands of the products. Michl's perimeter model is used as a conceptual framework to explain the changes in the relative energies of the frontier π-molecular orbitals. PMID:27558988

  10. Jupiter's ring

    NASA Technical Reports Server (NTRS)

    1979-01-01

    First evidence of a ring around the planet Jupiter is seen in this photograph taken by Voyager 1 on March 4, 1979. The multiple exposure of the extremely thin faint ring appears as a broad light band crossing the center of the picture. The edge of the ring is 1,212,000 km from the spacecraft and 57,000 km from the visible cloud deck of Jupiter. The background stars look like broken hair pins because of spacecraft motion during the 11 minute 12 second exposure. The wavy motion of the star trails is due to the ultra-slow natural oscillation of the spacecraft (with a period of 78 seconds). The black dots are geometric calibration points in the camera. The ring thickness is estimated to be 30 km or less. The photograph was part of a sequence planned to search for such rings in Jupiter's equatorial plane. The ring has been invisible from Earth because of its thinness and its transparency when viewed at any angle except straight on. JPL manages and controls the Voyager Project for NASA's Office of Space Science.

  11. The Role of the Atypical Kinases ABC1K7 and ABC1K8 in Abscisic Acid Responses

    PubMed Central

    Manara, Anna; DalCorso, Giovanni; Furini, Antonella

    2016-01-01

    The ABC1K family of atypical kinases (activity of bc1 complex kinase) is represented in bacteria, archaea, and eukaryotes. In plants they regulate diverse physiological processes in the chloroplasts and mitochondria, but their precise functions are poorly defined. ABC1K7 and ABC1K8 are probably involved in oxidative stress responses, isoprenyl lipid synthesis and distribution of iron within chloroplasts. Because reactive oxygen species take part in abscisic acid (ABA)-mediated processes, we investigated the functions of ABC1K7 and ABC1K8 during germination, stomatal movement, and leaf senescence. Both genes were upregulated by ABA treatment and some ABA-responsive physiological processes were affected in abc1k7 and abc1k8 mutants. Germination was more severely affected by ABA, osmotic stress and salt stress in the single and double mutants; the stomatal aperture was smaller in the mutants under standard growth conditions and was not further reduced by exogenous ABA application; ABA-induced senescence symptoms were more severe in the leaves of the single and double mutants compared to wild type leaves. Taken together, our results suggest that ABC1K7 and ABC1K8 might be involved in the cross-talk between ABA and ROS signaling. PMID:27047531

  12. The Role of the Atypical Kinases ABC1K7 and ABC1K8 in Abscisic Acid Responses.

    PubMed

    Manara, Anna; DalCorso, Giovanni; Furini, Antonella

    2016-01-01

    The ABC1K family of atypical kinases (activity of bc1 complex kinase) is represented in bacteria, archaea, and eukaryotes. In plants they regulate diverse physiological processes in the chloroplasts and mitochondria, but their precise functions are poorly defined. ABC1K7 and ABC1K8 are probably involved in oxidative stress responses, isoprenyl lipid synthesis and distribution of iron within chloroplasts. Because reactive oxygen species take part in abscisic acid (ABA)-mediated processes, we investigated the functions of ABC1K7 and ABC1K8 during germination, stomatal movement, and leaf senescence. Both genes were upregulated by ABA treatment and some ABA-responsive physiological processes were affected in abc1k7 and abc1k8 mutants. Germination was more severely affected by ABA, osmotic stress and salt stress in the single and double mutants; the stomatal aperture was smaller in the mutants under standard growth conditions and was not further reduced by exogenous ABA application; ABA-induced senescence symptoms were more severe in the leaves of the single and double mutants compared to wild type leaves. Taken together, our results suggest that ABC1K7 and ABC1K8 might be involved in the cross-talk between ABA and ROS signaling. PMID:27047531

  13. Radioactive Carbon Isotope Monitoring System Based on Cavity Ring-down Laser Spectroscopy for Decommissioning Process of Nuclear Facilities

    NASA Astrophysics Data System (ADS)

    Tomita, Hideki; Watanabe, Kenichi; Takiguchi, Yu; Kawarabayashi, Jun; Iguchi, Tetsuo

    In decommissioning process of nuclear facilities, large amount of radioactive isotopes are discharged as waste. Radioactive carbon isotope (14C) is one of the key nuclides to determine the upper limit of concentration in the waste disposal. In particular, 14C on the graphite reactor decommissioning should be separated from stable carbon isotopes (12C and 13C) and monitored for the public health and safety. We propose an isotope analysis system based on cavity ring-down laser spectroscopy (CRDS) to monitor the carbon isotopes (12C, 13C and 14C) in the isotope separation process for the graphite reactor decommissioning. This system is compact and suitable for a continuous monitoring, because the concentration of molecules including the carbon isotope is derived from its photo absorbance with ultra high sensitive laser absorption spectroscopy. Here are presented the necessary conditions of CRDS system for 14C isotope analysis through the preliminary experimental results of 13C isotope analysis with a prototype system.

  14. The Enceladus Ring

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] The Enceladus Ring (labeled)

    This excellent view of the faint E ring -- a ring feature now known to be created by Enceladus -- also shows two of Saturn's small moons that orbit within the ring, among a field of stars in the background.

    The E ring extends from three to eight Saturn radii -- about 180,000 kilometers (118,000 miles) to 482,000 kilometers (300,000 miles). Its full extent is not visible in this view.

    Calypso (22 kilometers, or 14 miles across) and Helene (32 kilometers, or 20 miles across) orbit within the E ring's expanse. Helene skirts the outer parts of the E ring, but here it is projected in front of a region deeper within the ring.

    Calypso and Helene are trojan satellites, or moons that orbit 60 degrees in front or behind a larger moon. Calypso is a Tethys trojan and Helene is a trojan of Dione.

    An interesting feature of note in this image is the double-banded appearance of the E-ring, which is created because the ring is somewhat fainter in the ringplane than it is 500-1,000 kilometers (300-600 miles) above and below the ringplane. This appearance implies that the particles in this part of the ring have nonzero inclinations (a similar affect is seen in Jupiter's gossamer ring). An object with a nonzero inclination does not orbit exactly at Saturn's ringplane. Instead, its orbit takes it above and below the ringplane. Scientists are not entirely sure why the particles should have such inclinations, but they are fairly certain that the reason involves Enceladus.

    One possible explanation is that all the E ring particles come from the plume of icy material that is shooting due south out of the moon's pole. This means all of the particles are created with a certain velocity out of the ringplane, and then they orbit above and below that plane.

    Another possible explanation is that Enceladus produces particles with a range of speeds, but the moon gravitationally

  15. Multifunctional nanoarchitectures from DNA-based ABC monomers

    NASA Astrophysics Data System (ADS)

    Lee, Jong B.; Roh, Young H.; Um, Soong Ho; Funabashi, Hisakage; Cheng, Wenlong; Cha, Judy J.; Kiatwuthinon, Pichamon; Muller, David A.; Luo, Dan

    2009-07-01

    The ability to attach different functional moieties to a molecular building block could lead to applications in nanoelectronics, nanophotonics, intelligent sensing and drug delivery. The building unit needs to be both multivalent and anisotropic, and although many anisotropic building blocks have been created, these have not been universally applicable. Recently, DNA has been used to generate various nanostructures or hybrid systems, and as a generic building block for various applications. Here, we report the creation of anisotropic, branched and crosslinkable building blocks (ABC monomers) from which multifunctional nanoarchitectures have been assembled. In particular, we demonstrate a target-driven polymerization process in which polymers are generated only in the presence of a specific DNA molecule, leading to highly sensitive pathogen detection. Using this monomer system, we have also designed a biocompatible nanovector that delivers both drugs and tracers simultaneously. Our approach provides a general yet versatile route towards the creation of a range of multifunctional nanoarchitectures.

  16. A season in Saturn's rings: Cycling, recycling and ring history

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Albers, N.; Sremcevic, M.

    2012-04-01

    Cassini experiments have watched Saturn's ring system evolve before our eyes. Images and occultations show changes and transient events. The rings are a dynamic and complex geophysical system, incompletely modeled as a single-phase fluid. Key Cassini observations: High resolution images show straw, propellers, embedded moonlets, and F ring objects. Multiple UVIS, RSS and VIMS occutlations indicate multimodal ringlet and edge structure, including free and forced modes along with stochastic perturbations that are most likely caused by nearby mass concentrations. Vertical excursions are evident at ring edges and in other perturbed regions. The rings are occasionally hit by meteorites that leave a signature that may last centuries; meteoritic dust pollutes the rings. Temperature, reflectance and transmission spectra are influenced by the dynamical state of the ring particles. Saturn's Equinox 2009: Oblique lighting exposed vertical structure and embedded objects. The rings were the coldest ever. Images inspired new occultation and spectral analysis that show abundant structure in the perturbed regions. The rings are more variable and complex than we had expected prior to this seasonal viewing geometry. Sub-kilometer structure in power spectral analysis: Wavelet analysis shows features in the strongest density waves and at the shepherded outer edge of the B ring. Edges are variable as shown by multiple occultations and occultations of double stars. F ring kittens: 25 features seen in the first 102 occultations show a weak correlation with Prometheus location. We interpret these features as temporary aggregations. Simulation results indicate that accretion must be enhanced to match the kittens' size distribution. Images show that Prometheus triggers the formation of transient objects. Propellers and ghosts: Occulations and images provide evidence for small moonlets in the A, B and C rings. These indicate accretion occurs inside the classical Roche limit. Implications

  17. Ring Enlargement of Three-Membered Boron Heterocycles upon Reaction with Organic π Systems: Implications for the Trapping of Borylenes.

    PubMed

    Krasowska, Małgorzata; Bettinger, Holger F

    2016-07-18

    New low-energy pathways for the reaction between substituted boriranes and borirenes with unsaturated hydrocarbons (ethyne or ethene) were discovered using density functional and coupled cluster theory. The interaction between the π bond of the hydrocarbon and the empty p orbital of the boron center leads to ring expansion of the three-membered to a five-membered boron heterocycle. The reactions are strongly exothermic and have low or even no barriers. They involve intermediates with a pentacoordinate boron center with two hydrocarbon molecules coordinating to boron akin to metal-olefin complexes. These borylene complexes are shallow minima on the potential energy surfaces. But significantly higher barriers for ring formation are computed for 1,5-cyclooctadiene and dibenzocyclooctatetraene complexes of borylenes, making these complexes likely detectable under appropriate experimental conditions. Our computational findings have implications for the interpretation of trapping experiments of thermally generated small borylenes with excess of small π systems. Because of very low barriers for reactions of three-membered boron heterocycles with π systems and the at least locally large excess of the latter under such conditions, formation of five-membered boron heterocycles should be considered. PMID:27305278

  18. Analysis of Longitudinal Beam Dynamics Behavior and RF System Operative Limits at High Beam Currents in Storage Rings

    SciTech Connect

    Mastorides, T; Rivetta, C.; Fox, J.D.; Winkle, D.Van; Tytelman, D.; /Dimtel, Redwood City

    2008-07-07

    A dynamics simulation model is used to estimate limits of performance of the Positron-Electron Project (PEP-II). The simulation captures the dynamics and technical limitations of the Low Level Radio Frequency (LLRF) system, the high-power RF components and the low-order mode coupled bunch longitudinal beam dynamics. Simulation results showing the effect of non-linearities on the LLRF loops, and studies of the effectiveness of technical component upgrades are reported, as well as a comparison of these results with PEP-II measurements. These studies have led to the estimation of limits and determining factors in the maximum stored current that the Low Energy Ring/High Energy Ring (LER/HER) can achieve, based on system stability for different RF station configurations and upgrades. In particular, the feasibility of the PEP-II plans to achieve the final goal in luminosity, which required an increase of the beam currents to 4A for LER and 2.2A for HER, is studied. These currents are challenging in part because they would push the longitudinal low-order beam mode stability to the limit, and the klystron forward power past a level of satisfactory margin. An acceptable margin is defined in this paper, which in turn determines the corresponding klystron forward power limitation.

  19. Highlights in planetary rings

    NASA Astrophysics Data System (ADS)

    Porco, Carolyn C.

    1995-07-01

    There is a rich phenomenology within the planetary rings surrounding the giant planets, most of it discovered by the Voyagers during their historic tours of t he outer solar system in the 1980s. In the last decade, there have been two detailed IUGG reviews of planetary rings. Cuzzi [1983] covered the time period from 1979-1983 which included the Pioneer 11 encounter with Saturn (1979), the Voyager 1 and 2 encounters with Jupiter (1979) and with Saturn (1980 and 1981). Nicholson and Dones [1991] reviewed the developments in the field between 1984 and 1991, a period of time which included the Voyager 2 Uranus (1986) and Neptune (1989) encounters. (References t o additional reviews of planetary rings and related fields can be found in Nicholson and Dones [1991].) Rather than being comprehensive in nature, this review will concentrate on only those areas of ring research in which particularly promising developments have occurred in the last half decade.

  20. Phosphine-Catalyzed Enantioselective Intramolecular [3+2] Annulations To Generate Fused Ring Systems

    PubMed Central

    2015-01-01

    Substantial progress has been described in the development of asymmetric variants of the phosphine-catalyzed intermolecular [3+2] annulation of allenes with alkenes; however, there have not been corresponding advances for the intramolecular process, which can generate a higher level of complexity (an additional ring and stereocenter(s)). In this study, we describe the application of chiral phosphepine catalysts to address this challenge, thereby providing access to useful scaffolds that are found in bioactive compounds, including diquinane and quinolin-2-one derivatives, with very good stereoselectivity. The products of the [3+2] annulation can be readily transformed into structures that are even more stereochemically rich. Mechanistic studies are consistent with β addition of the phosphepine to the allene being the turnover-limiting step of the catalytic cycle, followed by a concerted [3+2] cycloaddition to the pendant olefin. PMID:25815702

  1. The Reign of Confusion: ABC and the "Crisis in Iran."

    ERIC Educational Resources Information Center

    Palmerton, Patricia R.

    A study examined reports broadcast by ABC News between November 8, 1979 and December 7, 1979 in its series entitled "Crisis in Iran: America Held Hostage." Transcripts of approximately 50% of actual broadcasts were subjected to rhetorical critical analysis, from which the finding emerged that confusion was the predominant characteristic in ABC's…

  2. The ABCs of School Choice, 2009-2010 Edition

    ERIC Educational Resources Information Center

    Friedman Foundation for Educational Choice, 2010

    2010-01-01

    This publication presents the 2009-2010 edition of the Friedman Foundation for Educational Choice's "ABCs of School Choice". The "ABCs of School Choice" provides the latest in up-to-date and accurate information about the many school choice success stories taking place throughout the country. Readers will find this guide an essential resource on…

  3. To What Extent Does Attention Affect K-ABC Scores?

    ERIC Educational Resources Information Center

    Gordon, Michael; And Others

    1990-01-01

    Analyzed the protocols of 52 clinic-referred children who were administered the Kaufman Assessment Battery for Children (K-ABC) as well as version of the Continuous Performance Test (CPT), a laboratory measure of attention. Results demonstrated significant interrelationships among K-ABC and CPT scores. (Author/ABL)

  4. ABCs of Being Smart: S Is for Supporting

    ERIC Educational Resources Information Center

    Foster, Joanne

    2014-01-01

    Joanne Foster's article "R We There Yet?" was first published in "Parenting for High Potential" ("PHP") in 2006, which became the springboard for the "ABCs of Being Smart" series of columns. At that time, Foster invited "PHP" readers to think about their own versions of the "ABCs of Being…

  5. Measuring Academic Behavioural Confidence: The ABC Scale Revisited

    ERIC Educational Resources Information Center

    Sander, Paul; Sanders, Lalage

    2009-01-01

    The Academic Behavioural Confidence (ABC) scale has been shown to be valid and can be useful to teachers in understanding their students, enabling the design of more effective teaching sessions with large cohorts. However, some of the between-group differences have been smaller than expected, leading to the hypothesis that the ABC scale many not…

  6. ATP-Binding Cassette (ABC) Transporters of the Human Respiratory Tract Pathogen, Moraxella catarrhalis: Role in Virulence

    PubMed Central

    Murphy, Timothy F; Brauer, Aimee L.; Johnson, Antoinette; Kirkham, Charmaine

    2016-01-01

    Moraxella catarrhalis is a human respiratory tract pathogen that causes otitis media (middle ear infections) in children and respiratory tract infections in adults with chronic obstructive pulmonary disease. In view of the huge global burden of disease caused by M. catarrhalis, the development of vaccines to prevent these infections and better approaches to treatment have become priorities. In previous work, we used a genome mining approach that identified three substrate binding proteins (SBPs) of ATP-binding cassette (ABC) transporters as promising candidate vaccine antigens. In the present study, we performed a comprehensive assessment of 19 SBPs of 15 ABC transporter systems in the M. catarrhalis genome by engineering knockout mutants and studying their role in assays that assess mechanisms of infection. The capacity of M. catarrhalis to survive and grow in the nutrient-limited and hostile environment of the human respiratory tract, including intracellular growth, account in part for its virulence. The results show that ABC transporters that mediate uptake of peptides, amino acids, cations and anions play important roles in pathogenesis by enabling M. catarrhalis to 1) grow in nutrient-limited conditions, 2) invade and survive in human respiratory epithelial cells and 3) persist in the lungs in a murine pulmonary clearance model. The knockout mutants of SBPs and ABC transporters showed different patterns of activity in the assay systems, supporting the conclusion that different SBPs and ABC transporters function at different stages in the pathogenesis of infection. These results indicate that ABC transporters are nutritional virulence factors, functioning to enable the survival of M catarrhalis in the diverse microenvironments of the respiratory tract. Based on the role of ABC transporters as virulence factors of M. catarrhalis, these molecules represent potential drug targets to eradicate the organism from the human respiratory tract. PMID:27391026

  7. ATP-Binding Cassette (ABC) Transporters of the Human Respiratory Tract Pathogen, Moraxella catarrhalis: Role in Virulence.

    PubMed

    Murphy, Timothy F; Brauer, Aimee L; Johnson, Antoinette; Kirkham, Charmaine

    2016-01-01

    Moraxella catarrhalis is a human respiratory tract pathogen that causes otitis media (middle ear infections) in children and respiratory tract infections in adults with chronic obstructive pulmonary disease. In view of the huge global burden of disease caused by M. catarrhalis, the development of vaccines to prevent these infections and better approaches to treatment have become priorities. In previous work, we used a genome mining approach that identified three substrate binding proteins (SBPs) of ATP-binding cassette (ABC) transporters as promising candidate vaccine antigens. In the present study, we performed a comprehensive assessment of 19 SBPs of 15 ABC transporter systems in the M. catarrhalis genome by engineering knockout mutants and studying their role in assays that assess mechanisms of infection. The capacity of M. catarrhalis to survive and grow in the nutrient-limited and hostile environment of the human respiratory tract, including intracellular growth, account in part for its virulence. The results show that ABC transporters that mediate uptake of peptides, amino acids, cations and anions play important roles in pathogenesis by enabling M. catarrhalis to 1) grow in nutrient-limited conditions, 2) invade and survive in human respiratory epithelial cells and 3) persist in the lungs in a murine pulmonary clearance model. The knockout mutants of SBPs and ABC transporters showed different patterns of activity in the assay systems, supporting the conclusion that different SBPs and ABC transporters function at different stages in the pathogenesis of infection. These results indicate that ABC transporters are nutritional virulence factors, functioning to enable the survival of M catarrhalis in the diverse microenvironments of the respiratory tract. Based on the role of ABC transporters as virulence factors of M. catarrhalis, these molecules represent potential drug targets to eradicate the organism from the human respiratory tract. PMID:27391026

  8. Monte Carlo simulations of ABC stacked kagome lattice films.

    PubMed

    Yerzhakov, H V; Plumer, M L; Whitehead, J P

    2016-05-18

    Properties of films of geometrically frustrated ABC stacked antiferromagnetic kagome layers are examined using Metropolis Monte Carlo simulations. The impact of having an easy-axis anisotropy on the surface layers and cubic anisotropy in the interior layers is explored. The spin structure at the surface is shown to be different from that of the bulk 3D fcc system, where surface axial anisotropy tends to align spins along the surface [1 1 1] normal axis. This alignment then propagates only weakly to the interior layers through exchange coupling. Results are shown for the specific heat, magnetization and sub-lattice order parameters for both surface and interior spins in three and six layer films as a function of increasing axial surface anisotropy. Relevance to the exchange bias phenomenon in IrMn3 films is discussed.

  9. Monte Carlo simulations of ABC stacked kagome lattice films

    NASA Astrophysics Data System (ADS)

    Yerzhakov, H. V.; Plumer, M. L.; Whitehead, J. P.

    2016-05-01

    Properties of films of geometrically frustrated ABC stacked antiferromagnetic kagome layers are examined using Metropolis Monte Carlo simulations. The impact of having an easy-axis anisotropy on the surface layers and cubic anisotropy in the interior layers is explored. The spin structure at the surface is shown to be different from that of the bulk 3D fcc system, where surface axial anisotropy tends to align spins along the surface [1 1 1] normal axis. This alignment then propagates only weakly to the interior layers through exchange coupling. Results are shown for the specific heat, magnetization and sub-lattice order parameters for both surface and interior spins in three and six layer films as a function of increasing axial surface anisotropy. Relevance to the exchange bias phenomenon in IrMn3 films is discussed.

  10. Ghostly Ring

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for poster version

    This image shows a ghostly ring extending seven light-years across around the corpse of a massive star. The collapsed star, called a magnetar, is located at the exact center of this image. NASA's Spitzer Space Telescope imaged the mysterious ring around magnetar SGR 1900+14 in infrared light. The magnetar itself is not visible in this image, as it has not been detected at infrared wavelengths (it has been seen in X-ray light).

    Magnetars are formed when a massive giant star ends its life in a supernova explosion, leaving behind a super dense neutron star with an incredibly strong magnetic field. The ring seen by Spitzer could not have formed during the original explosion, as any material as close to the star as the ring would have been disrupted by the supernova shock wave. Scientists suspect that the ring my actually be the edges of a bubble that was hollowed out by an explosive burst from the magnetar in 1998. The very bright region near the center of the image is a cluster of young stars, which may be illuminating the inner edge of the bubble, making it look like a ring in projection.

    This composite image was taken using all three of Spitzer's science instruments. The blue color represents 8-micron infrared light taken by the infrared array camera, green is 16-micron light from the infrared spectograph, and red is 24-micron radiation from the multiband imaging photometer.

  11. The Orbits of the Uranian Satellites and Rings, the Gravity Field of the Uranian System, and the Orientation of the Pole of Uranus

    NASA Astrophysics Data System (ADS)

    Jacobson, R. A.

    2014-11-01

    French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson & Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques. Government sponsorship acknowledged.

  12. The orbits of the uranian satellites and rings, the gravity field of the uranian system, and the orientation of the pole of Uranus

    SciTech Connect

    Jacobson, R. A.

    2014-11-01

    French et al. determined the orbits of the Uranian rings, the orientation of the pole of Uranus, and the gravity harmonics of Uranus from Earth-based and Voyager ring occultations. Jacobson et al. determined the orbits of the Uranian satellites and the masses of Uranus and its satellites from Earth-based astrometry and observations acquired with the Voyager 2 spacecraft; they used the gravity harmonics and pole from French et al. Jacobson and Rush reconstructed the Voyager 2 trajectory and redetermined the Uranian system gravity parameters, satellite orbits, and ring orbits in a combined analysis of the data used previously augmented with additional Earth-based astrometry. Here we report on an extension of that work that incorporates additional astrometry and ring occultations together with improved data processing techniques.

  13. In-situ calibration: migrating control system IP module calibration from the bench to the storage ring

    SciTech Connect

    Weber, Jonah M.; Chin, Michael

    2002-04-30

    The Control System for the Advanced Light Source (ALS) at Lawrence Berkeley National Lab (LBNL) uses in-house designed IndustryPack(registered trademark) (IP) modules contained in compact PCI (cPCI) crates with 16-bit analog I/O to control instrumentation. To make the IP modules interchangeable, each module is calibrated for gain and offset compensation. We initially developed a method of verifying and calibrating the IP modules in a lab bench test environment using a PC with LabVIEW. The subsequent discovery that the ADCs have significant drift characteristics over periods of days of installed operation prompted development of an ''in-situ'' calibration process--one in which the IP modules can be calibrated without removing them from the cPCI crates in the storage ring. This paper discusses the original LabVIEW PC calibration and the migration to the proposed in-situ EPICS control system calibration.

  14. A low-frequency high-voltage rf-barrier-bunching system for high-intensity neutron source compressor rings

    SciTech Connect

    Hardek, T.W.; Ziomek, C.; Rees, D.

    1995-05-01

    A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an rf-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in this case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured retrode amplifiers incorporating local rf feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with rf feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated.

  15. Experimental investigation of thermal processes in the multi-ring Couette system with counter rotation of cylinders

    NASA Astrophysics Data System (ADS)

    Mamonov, V. N.; Nazarov, A. D.; Serov, A. F.; Terekhov, V. I.

    2016-01-01

    The effect of parameters of the multi-ring Couette system with counter rotating coaxial cylinders on the process of thermal energy release in a viscous liquid filling this system is considered with regard to the problem of determining the possibility of creating the high-performance wind heat generator. The multi-cylinder rotor design allows directly conversion of the mechanical power of a device consisting of two "rotor" wind turbines with a common axis normal to the air flow into the thermal energy in a wide range of rotational speed of the cylinders. Experimental results on the measurement of thermal power released in the pilot heat generator at different relative angular speeds of cylinder rotation are presented.

  16. Detergent-free purification of ABC (ATP-binding-cassette) transporters.

    PubMed

    Gulati, Sonali; Jamshad, Mohammed; Knowles, Timothy J; Morrison, Kerrie A; Downing, Rebecca; Cant, Natasha; Collins, Richard; Koenderink, Jan B; Ford, Robert C; Overduin, Michael; Kerr, Ian D; Dafforn, Timothy R; Rothnie, Alice J

    2014-07-15

    ABC (ATP-binding-cassette) transporters carry out many vital functions and are involved in numerous diseases, but study of the structure and function of these proteins is often hampered by their large size and membrane location. Membrane protein purification usually utilizes detergents to solubilize the protein from the membrane, effectively removing it from its native lipid environment. Subsequently, lipids have to be added back and detergent removed to reconstitute the protein into a lipid bilayer. In the present study, we present the application of a new methodology for the extraction and purification of ABC transporters without the use of detergent, instead, using a copolymer, SMA (polystyrene-co-maleic acid). SMA inserts into a bilayer and assembles into discrete particles, essentially solubilizing the membrane into small discs of bilayer encircled by a polymer, termed SMALPs (SMA lipid particles). We show that this polymer can extract several eukaryotic ABC transporters, P-glycoprotein (ABCB1), MRP1 (multidrug-resistance protein 1; ABCC1), MRP4 (ABCC4), ABCG2 and CFTR (cystic fibrosis transmembrane conductance regulator; ABCC7), from a range of different expression systems. The SMALP-encapsulated ABC transporters can be purified by affinity chromatography, and are able to bind ligands comparably with those in native membranes or detergent micelles. A greater degree of purity and enhanced stability is seen compared with detergent solubilization. The present study demonstrates that eukaryotic ABC transporters can be extracted and purified without ever being removed from their lipid bilayer environment, opening up a wide range of possibilities for the future study of their structure and function.

  17. Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium of an internal ring current system

    SciTech Connect

    Furukawa, M.

    2014-01-15

    Effects of pressure anisotropy on magnetospheric magnetohydrodynamics equilibrium are studied analytically and numerically, where the plasma is confined by only poloidal magnetic field generated by an internal ring current. The plasma current due to finite pressure can be divided into two components; one remains at isotropic pressure and the other arises from pressure anisotropy. When p{sub ⊥}, the pressure perpendicular to the magnetic field, is larger than p{sub ∥}, the pressure parallel to the magnetic field, those two components of plasma current tend to cancel each other to reduce the total amount of plasma current. Equilibrium beta limit is also examined, where the beta is a ratio of the plasma pressure to the magnetic pressure. The equilibrium beta limit decreases as the pressure anisotropy becomes strong. The beta value is strictly limited by ellipticity of the equilibrium equation when p{sub ∥}>p{sub ⊥}. On the other hand, when p{sub ⊥}>p{sub ∥}, although the tendency of the beta limit agrees with the ellipticity condition of the equilibrium equation, equilibria with a hyperbolic region can be obtained by iterative procedure with practically reasonable convergence criteria.

  18. Study of photon–magnon coupling in a YIG-film split-ring resonant system

    SciTech Connect

    Bhoi, B.; Aiyar, R.; Cliff, T.; Maksymov, I. S.; Kostylev, M.; Venkataramani, N.; Prasad, S.; Stamps, R. L.

    2014-12-28

    By using the stripline Microwave Vector–Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium–iron–garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9% at 3 GHz. Theoretically, we propose an equivalent circuit model of the SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetisation dynamics in the YIG film driven by the microwave currents in the SRR. The results obtained with the equivalent-circuit model are in good agreement with the experiment. This model provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in nonlinear and magnetically tuneable metamaterials exploiting the strong coupling of magnons to microwave photons.

  19. Study of photon-magnon coupling in a YIG-film split-ring resonant system

    NASA Astrophysics Data System (ADS)

    Bhoi, B.; Cliff, T.; Maksymov, I. S.; Kostylev, M.; Aiyar, R.; Venkataramani, N.; Prasad, S.; Stamps, R. L.

    2014-12-01

    By using the stripline Microwave Vector-Network Analyser Ferromagnetic Resonance and Time Domain spectroscopy techniques, we study a strong coupling regime of magnons to microwave photons in the planar geometry of a lithographically formed split-ring resonator (SRR) loaded by a single-crystal epitaxial yttrium-iron-garnet (YIG) film. Strong anti-crossing of the photon modes of SRR and of the magnon modes of the YIG film is observed in the applied-magnetic-field resolved measurements. The coupling strength extracted from the experimental data reaches 9% at 3 GHz. Theoretically, we propose an equivalent circuit model of the SRR loaded by a magnetic film. This model follows from the results of our numerical simulations of the microwave field structure of the SRR and of the magnetisation dynamics in the YIG film driven by the microwave currents in the SRR. The results obtained with the equivalent-circuit model are in good agreement with the experiment. This model provides a simple physical explanation of the process of mode anti-crossing. Our findings are important for future applications in microwave quantum photonic devices as well as in nonlinear and magnetically tuneable metamaterials exploiting the strong coupling of magnons to microwave photons.

  20. Toward Determining ATPase Mechanism in ABC Transporters: Development of the Reaction Path–Force Matching QM/MM Method

    PubMed Central

    Zhou, Y.; Ojeda-May, P.; Nagaraju, M.; Pu, J.

    2016-01-01

    Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path–force matching (RP–FM) has been developed. In RP–FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP–FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639

  1. Toward Determining ATPase Mechanism in ABC Transporters: Development of the Reaction Path-Force Matching QM/MM Method.

    PubMed

    Zhou, Y; Ojeda-May, P; Nagaraju, M; Pu, J

    2016-01-01

    Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path-force matching (RP-FM) has been developed. In RP-FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP-FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639

  2. Application of artificial bee colony (ABC) algorithm in search of optimal release of Aswan High Dam

    NASA Astrophysics Data System (ADS)

    Hossain, Md S.; El-shafie, A.

    2013-04-01

    The paper presents a study on developing an optimum reservoir release policy by using ABC algorithm. The decision maker of a reservoir system always needs a guideline to operate the reservoir in an optimal way. Release curves have developed for high, medium and low inflow category that can answer how much water need to be release for a month by observing the reservoir level (storage condition). The Aswan high dam of Egypt has considered as the case study. 18 years of historical inflow data has used for simulation purpose and the general system performance measuring indices has measured. The application procedure and problem formulation of ABC is very simple and can be used in optimizing reservoir system. After using the actual historical inflow, the release policy succeeded in meeting demand for about 98% of total time period.

  3. An ABC status report. [Advancing Blade Concept for XH-59A rotors

    NASA Technical Reports Server (NTRS)

    Linden, A. W.; Ruddell, A. J.

    1981-01-01

    The Advancing Blade Concept (ABC) uses two rigid counterrotating rotors in a coaxial arrangement to provide advancing blades on both sides of the aircraft. This makes use of the high dynamic pressure on the advancing side of the rotors at high forward speed, virtually ignoring the low dynamic pressure on the retreating side, while still keeping the rotor system in roll trim. Theoretically such a rotor system will maintain its lift potential as speed increases. The XH-59A was designed to investigate this theory. A description is provided of the flight test program from May, 1980 to January, 1981. A summary is presented of the knowledge gained throughout the entire program, and current pitfalls are reviewed. It is concluded that the ABC has been verified, with the XH-59A envelope of blade lift coefficient as a function of advance ratio greatly exceeding that of conventional helicopter rotor systems.

  4. The composition and structure of planetary rings

    NASA Technical Reports Server (NTRS)

    Burns, J. A.

    1985-01-01

    The properties of planetary ring systems are summarized herein; emphasis is given to the available evidence on their compositions and to their dynamical attributes. Somewhat contaminated water ice makes up the vast expanse of Saturn's rings. Modified methane ice may comprise Uranus' rings while silicates are the likely material of the Jovian ring. Saturn's rings form an elaborate system whose characteristics are still being documented and whose nature is being unravelled following the Voyager flybys. Uranus' nine narrow bands display an intriguing dynamical structure thought to be caused by unseen shephard satellites. Jupiter's ring system is a mere wisp, probably derived as ejecta off hidden parent bodies.

  5. Cooperative activation of cyclobutanones and olefins leads to bridged-ring systems by a catalytic [4+2] coupling

    PubMed Central

    Ko, Haye Min; Dong, Guangbin

    2014-01-01

    Bridged-ring systems are widely found in natural products and successful syntheses of them frequently feature intramolecular Diels-Alder (IMDA) reactions. These reactions are subclassified as either type I or type II IMDAs depending on how the diene motif is tethered to the rest of the substrate - type I are tethered at the 1-position of the diene and type II at the 2-position. While the type I IMDA has been used to great success, the molecular scaffolds accessible by type II IMDAs are limited by the strain inherent in the formation of a sp2-carbon at a bridgehead position. Here, we describe a complementary approach that provides access to these structures through the C−C activation of cyclobutanones and their coupling with olefins. Various alkenes have been coupled with cyclobutanones to provide a range of bridged skeletons. The ketone group of the products serves as a convenient handle for downstream functionalization. PMID:25054946

  6. Removal of copper and iron by polyurethane foam column in FIA system for the determination of nickel in pierced ring.

    PubMed

    Vongboot, Monnapat; Suesoonthon, Monrudee

    2015-01-01

    Polyurethane foam (PUF) mini-column was used to eliminate copper and iron for the determination of nickel in pierced rings. The PUF mini-column was connected to FIA system for on-line sorption of copper and iron in complexes form of CuSCN(+) and FeSCN(2+). For this season, the acid solution containing a mixture of Ni(II), Fe(III), Cu(II) and SCN(-) ions was firstly flew into the PUF column. Then, the percolated solution which Fe(III) and Cu(II) ions is separated from analysis was injected into FIA system to react with 4-(2-pyridylazo) resorcinol (PAR) reagent in basic condition which this method is called pH gradient technique. The Ni-PAR complexes obtained were measured theirs absorbance at 500 nm by UV visible spectrophotometer. In this study, it was found that Cu(II) and Fe(III) were completely to form complexes with 400 mmol/L KSCN and entirely to eliminate in acidic condition at pH 3.0. In the optimum condition of these experiments, the method provided the linear relationship between absorbance and the concentration of Ni(II) in the range from 5.00 to 30.00 mg/L. Linear equation is y=0.0134x+0.0033 (R(2)=0.9948). Precision, assessed in the term of the relative standard deviation, RSD, and accuracy for multiple determinations obtained in values of 0.77-1.73% and 97.4%, respectively. The level of an average amount of Ni(II) in six piercing rings was evaluated to be 14.78 mg/g.

  7. Positron ring system using anger-type detectors. Progress report, January 1-December 31, 1986

    SciTech Connect

    Muehllehner, G.

    1986-09-01

    The design of a new multislice system consisting of six position-sensitive area detectors has been completed, and the system is now in the final assembly phase. This system will be able to reconstruct a volume 50 cm in diameter and 10 cm long with equal resolution of 4 to 5 mm in all directions. The system achieves high sensitivity through a large acceptance angle which is made possible through the use of three-dimensional reconstruction algorithms.

  8. Synthetic approaches to the bicyclo[2.2.2]diazaoctane ring system common to the paraherquamides, stephacidins and related prenylated indole alkaloids.

    PubMed

    Miller, Kenneth A; Williams, Robert M

    2009-11-01

    The bicyclo[2.2.2]diazaoctane ring system is common to a number of highly biologically active secondary metabolites isolated from numerous species of fungi. In this tutorial review, we describe the varied synthetic approaches that have been employed to construct this ring system in the course of recent total synthesis endeavors, and this review should be of interest to synthetic organic chemists and natural product chemists. Detailed herein are a number of synthetic disconnections including intramolecular S(N)2' cyclizations, biomimetic Diels-Alder reactions, radical cyclizations, and cationic cascade reactions. PMID:19847349

  9. Image reconstruction algorithms for a novel PET system with a half-ring insert

    NASA Astrophysics Data System (ADS)

    Pal, Debashish; Tai, Yuan-Chuan; Janecek, Martin; Wu, Heyu; O'Sullivan, Joseph A.

    2006-02-01

    Breast cancer continues to be the most common malignancy of women in the United States. Nuclear imaging techniques such as positron emission tomography (PET) have been widely used for the staging of cancer. The primary limitations of PET for breast cancer diagnosis are the lack of a highly specific radiotracer and the limited resolution of imaging systems. The sensitivity for detecting small lesions is very low. Many groups are developing positron emission mammography (PEM) systems dedicated for breast imaging using high resolution detectors. Although image resolution is significantly improved compared to whole-body PET systems, the clinical value of a PEM system is yet to be proven, 3.4 Most PET systems have limitations in imaging tissues near the chest walls and lymph nodes. The proposed system addresses the sampling requirements specific to breast imaging and achieves high resolution in PET images of breast and thorax.

  10. Total synthesis of dihydrolysergic acid and dihydrolysergol: development of a divergent synthetic strategy applicable to rapid assembly of D-ring analogs

    PubMed Central

    Lee, Kiyoun; Poudel, Yam B.; Glinkerman, Christopher M.; Boger, Dale L.

    2015-01-01

    The total syntheses of dihydrolysergic acid and dihydrolysergol are detailed based on a Pd(0)-catalyzed intramolecular Larock indole cyclization for the preparation of the embedded tricyclic indole (ABC ring system) and a subsequent powerful inverse electron demand Diels–Alder reaction of 5-carbomethoxy-1,2,3-triazine with a ketone-derived enamine for the introduction of a functionalized pyridine, serving as the precursor for a remarkably diastereoselective reduction to the N-methylpiperidine D-ring. By design, the use of the same ketone-derived enamine and a set of related complementary heterocyclic azadiene [4 + 2] cycloaddition reactions permitted the late stage divergent preparation of a series of alternative heterocyclic derivatives not readily accessible by more conventional approaches. PMID:26273113

  11. IMG-ABC: An Atlas of Biosynthetic Gene Clusters to Fuel the Discovery of Novel Secondary Metabolites

    SciTech Connect

    Chen, I-Min; Chu, Ken; Ratner, Anna; Palaniappan, Krishna; Huang, Jinghua; Reddy, T. B.K.; Cimermancic, Peter; Fischbach, Michael; Ivanova, Natalia; Markowitz, Victor; Kyrpides, Nikos; Pati, Amrita

    2014-10-28

    In the discovery of secondary metabolites (SMs), large-scale analysis of sequence data is a promising exploration path that remains largely underutilized due to the lack of relevant computational resources. We present IMG-ABC (https://img.jgi.doe.gov/abc/) -- An Atlas of Biosynthetic gene Clusters within the Integrated Microbial Genomes (IMG) system1. IMG-ABC is a rich repository of both validated and predicted biosynthetic clusters (BCs) in cultured isolates, single-cells and metagenomes linked with the SM chemicals they produce and enhanced with focused analysis tools within IMG. The underlying scalable framework enables traversal of phylogenetic dark matter and chemical structure space -- serving as a doorway to a new era in the discovery of novel molecules.

  12. How much do we know about drug handling by SLC and ABC drug transporters in children?

    PubMed

    Nigam, S K; Bhatnagar, V

    2013-07-01

    Although solute carrier (SLC) and ATP-binding cassette (ABC) transporters are critical to the absorption, distribution, and elimination of many small-molecule drugs in children, how these transporters regulate pediatric drug handling remains unclear. For proper dosing and to diminish toxicity, we need a better understanding of how organ development and functional maturation, as well as developmental changes in systemic physiology, impact transporter-mediated drug handling at pediatric developmental stages from the preterm infant through adolescence.

  13. ABC's of Being Smart: I Can "C" Clearly Now

    ERIC Educational Resources Information Center

    Foster, Joanne

    2011-01-01

    In this paper, the author focuses on C of the ABC's of being smart. She continues to categorize the points for readers. These categories include the following: (1) being; (2) doing; and (3) stretching.

  14. ABC proteins protect the human body and maintain optimal health.

    PubMed

    Ueda, Kazumitsu

    2011-01-01

    Human MDR1, a multi-drug transporter gene, was isolated as the first of the eukaryote ATP Binding Cassette (ABC) proteins from a multidrug-resistant carcinoma cell line in 1986. To date, over 25 years, many ABC proteins have been found to play important physiological roles by transporting hydrophobic compounds. Defects in their functions cause various diseases, indicating that endogenous hydrophobic compounds, as well as water-soluble compounds, are properly transported by transmembrane proteins. MDR1 transports a large number of structurally unrelated drugs and is involved in their pharmacokinetics, and thus is a key factor in drug interaction. ABCA1, an ABC protein, eliminates excess cholesterol in peripheral cells by generating HDL. Because ABCA1 is a key molecule in cholesterol homeostasis, its function and expression are highly regulated. Eukaryote ABC proteins function on the body surface facing the outside and in organ pathways to adapt to the extracellular environment and protect the body to maintain optimal health.

  15. MDR-ABC transporters: biomarkers in rheumatoid arthritis.

    PubMed

    Márki-Zay, János; Tauberné Jakab, Katalin; Szerémy, Péter; Krajcsi, Peter

    2013-01-01

    MDR-ABC transporters are widely expressed in cell types relevant to pathogenesis of rheumatoid arthritis. Many reports demonstrate the interaction of small molecule drugs with MDR-ABC transporters. Cell-based assays for disease relevant cell types can be easily gated and could reveal specific drug targets and may increase significance and utilisation of data in clinical practice. Many commonly used DMARDs (e.g. methotrexate, sulfasalazine, leflunomide/teriflunomide, hydroxychloroquine) are ABCG2 substrates. Consequently, the activity of this transporter in patients should be determined to understand the disposition and pharmacokinetics of the therapy. In addition, MDR-ABC transporters transport a variety of endobiotics that play important roles in cell proliferation, cell migration, angiogenesis and inflammation. Therefore, MDR-ABC transporters are important biomarkers in rheumatoid arthritis. PMID:23711386

  16. ArgR is an essential local transcriptional regulator of the arcABC operon in Streptococcus suis and is crucial for biological fitness in an acidic environment.

    PubMed

    Fulde, Marcus; Willenborg, Joerg; de Greeff, Astrid; Benga, Laurentiu; Smith, Hilde E; Valentin-Weigand, Peter; Goethe, Ralph

    2011-02-01

    Streptococcus suis is one of the most important pathogens in pigs and can also cause severe infections in humans. Despite its clinical relevance, very little is known about the factors that contribute to its virulence. Recently, we identified a new putative virulence factor in S. suis, the arginine deiminase system (ADS), an arginine catabolic enzyme system encoded by the arcABC operon, which enables S. suis to survive in an acidic environment. In this study, we focused on ArgR, an ADS-associated regulator belonging to the ArgR/AhrC arginine repressor family. Using an argR knockout strain we were able to show that ArgR is essential for arcABC operon expression and necessary for the biological fitness of S. suis. By cDNA expression microarray analyses and quantitative real-time RT-PCR we found that the arcABC operon is the only gene cluster regulated by ArgR, which is in contrast to the situation in many other bacteria. Reporter gene analysis with gfp under the control of the arcABC promoter demonstrated that ArgR is able to activate the arcABC promoter. Electrophoretic mobility shift assays with fragments of the arcABC promoter and recombinant ArgR, and chromatin immunoprecipitation with antibodies directed against ArgR, revealed that ArgR interacts with the arcABC promoter in vitro and in vivo by binding to a region from -147 to -72 bp upstream of the transcriptional start point. Overall, our results show that in S. suis, ArgR is an essential, system-specific transcriptional regulator of the ADS that interacts directly with the arcABC promoter in vivo.

  17. Implementation of activity-based costing (ABC) to drive cost reduction efforts in a semiconductor manufacturing operation

    NASA Astrophysics Data System (ADS)

    Naguib, Hussein; Bol, Igor I.; Lora, J.; Chowdhry, R.

    1994-09-01

    This paper presents a case study on the implementation of ABC to calculate the cost per wafer and to drive cost reduction efforts for a new IC product line. The cost reduction activities were conducted through the efforts of 11 cross-functional teams which included members of the finance, purchasing, technology development, process engineering, equipment engineering, production control, and facility groups. The activities of these cross functional teams were coordinated by a cost council. It will be shown that these activities have resulted in a 57% reduction in the wafer manufacturing cost of the new product line. Factors contributed to successful implementation of an ABC management system are discussed.

  18. A microcomputer-based data acquisition and control system for the direct shear, ring shear, triaxial shear, and consolidation tests

    USGS Publications Warehouse

    Powers, Philip S.

    1983-01-01

    This report is intended to provide internal documentation for the U.S. Geological Survey laboratory's automatic data acquisition system. The operating procedures for each type of test are designed to independently lead a first-time user through the various stages of using the computer to control the test. Continuing advances in computer technology and the availability of desktop microcomputers with a wide variety of peripheral equipment at a reasonable cost can create an efficient automated geotechnical testing environment. A geotechnical testing environment is shown in figure 1. Using an automatic data acquisition system, laboratory test data from a variety of sensors can be collected, and manually or automatically recorded on a magnetic device at the same apparent time. The responses of a test can be displayed graphically on a CRT in a matter of seconds, giving the investigator an opportunity to evaluate the test data, and to make timely, informed decisions on such matters as whether to continue testing, abandon a test, or modify procedures. Data can be retrieved and results reported in tabular form, or graphic plots, suitable for publication. Thermistors, thermocouples, load cells, pressure transducers, and linear variable differential transformers are typical sensors which are incorporated in automated systems. The geotechnical tests which are most practical to automate are the long-term tests which often require readings to be recorded outside normal work hours and on weekends. Automation applications include incremental load consolidation tests, constant-rate-of-strain consolidation tests, direct shear tests, ring shear tests, and triaxial shear tests.

  19. A low-cost dielectric spectroscopic system using metamaterial open horn-ring resonator-inspired BSF and detection circuitry

    NASA Astrophysics Data System (ADS)

    Kumari, Ratnesh; Patel, Piyush N.

    2016-07-01

    The sensitivity in a lower microwave band dielectric spectroscopic system is relatively less compared to that of millimeter wave and terahertz system. This work reports modeling and development of an epsilon-negative metamaterial resonator-inspired microwave band-stop filter as a prototype device and its detection circuitry for the spectroscopic analysis of dielectric samples in S-band. The device structure consists of a diamond-shaped patch with a complementary open split horn-ring resonator, fabricated on a Neltech substrate of relative permittivity ( ɛ r = 3.2). The measured transmission coefficient at 2.2 GHz and simulated result at 2.24 GHz demonstrate an excellent accuracy in the device fabrication. A low-cost connector-type microwave signal detection system was assembled for the real-time transduction of device signal into an equivalent DC voltage. Further, a single channel cavity developed using polydimethylsiloxane was placed over the resonator gap for analyzing the perturbation effect of electric field intensity on the resonance and circuit output DC level for different dielectric samples under test. The performed calibrations show linearity up to 82.5 % in the device response.

  20. Castro ring zone: a 4,500-km2 fossil hydrothermal system in the Challis volcanic field, central Idaho.

    USGS Publications Warehouse

    Criss, R.E.; Ekren, E.B.; Hardyman, R.F.

    1984-01-01

    The largest fossil hydrothermal system occupying a 4500 km2 area in central Idaho is revealed by delta 18O studies. The remains of this meteoric-hydrothermal system are preserved within a sharply bounded, 15 km wide, 70-km-diameter annulus of low delta 18O rock (+2.0 to -8.8per mille) termed the Castro ring zone. The zone is centred on a less depleted (+4.5) core zone consisting of granitic rocks of the Castro pluton. This 700-km2 Eocene subvolcanic batholith has intruded, domed, and hydrothermally metamorphosed a thick sequence of Challis Volcanics, the stratigraphically low rocks in the 2000-km2 Van Horn Peak and the 1000-km2 Thunder Mountain cauldron complexes being most strongly altered. Less extreme 18O depletions occur in the youngest major ash-flow sheets of these complexes, indicating a vertical 18O gradient. Water/rock ratios of geothermal systems are surprisingly insensitive to the circulation scale.-L.-di H.

  1. How Jupiter's Ring Was Discovered.

    ERIC Educational Resources Information Center

    Elliot, James; Kerr, Richard

    1985-01-01

    "Rings" (by astronomer James Elliot and science writer Richard Kerr) is a nontechnical book about the discovery and exploration of ring systems from the time of Galileo to the era of the Voyager spacecraft. One of this book's chapters is presented. (JN)

  2. The ABC daycare disaster of Hermosillo, Mexico.

    PubMed

    Greenhalgh, David G; Chang, Philip; Maguina, Pirko; Combs, Elena; Sen, Soman; Palmieri, Tina L

    2012-01-01

    On June 5, 2009, the ABC Daycare facility in Hermosillo, Mexico, caught on fire with an estimated 142 children and 6 adult caregivers inside. The purpose of this article is to describe the factors contributing to the disaster including care of the survivors, tertiary burn center triage, patient transport, and treatment for this international mass casualty event. Finally, the results of an investigation performed by the Mexican Government are reviewed. A summary of the Mexican Government's investigation of the circumstances of fire and an examination of prevention lapses in other Mexican daycare centers was obtained from their public Web site. The demographic and clinical characteristics of the children transported to the burn center were obtained from the patients' medical records and transport data sheets. The ABC Daycare had many fire safety breaches that contributed to the severity of the tragedy. Twenty-nine children died at the scene and more than 35 children were hospitalized throughout Mexico. A total of 12 children were transported to two Shriners Hospitals, 9 to Sacramento, and 3 to Cincinnati. The mean age of patients sent to the Shriners Hospitals was 2.9 ± 0.16 years (2-4 years), with 5 being male and 7 female. The mean duration between injury and arrival was 9.2 ± 2.1 days, the burn size was 43.0 ± 6.8% TBSA (6.5-80%), and there were 3.75 operations per patient. Four had fourth-degree burns requiring finger amputations (2), flaps to cover bone (1), or a through-knee amputation (1). Ten patients were admitted to the intensive care unit, and nine patients (seven with inhalation injury) required mechanical ventilation for a mean of 23.6 ± 10.3 days. All the surviving children were discharged after a mean length of stay of 45.9 ± 8.7 days. In the first year postinjury, seven children were readmitted a total of 11 times for reconstructive surgery, wound care, or rehabilitation. Ultimately, a total of 49 children died. A review of other daycare centers

  3. The LEO Archipelago: A system of earth-rings for communications, mass-transport to space, solar power, and control of global warming

    NASA Astrophysics Data System (ADS)

    Meulenberg, Andrew; Karthik Balaji, P. S.

    2011-06-01

    Man's quest to get into space is hindered by major problems (e.g., system-development and capital costs, expense of putting mass into orbit, trapped-radiation belts, and environmental impact of a large increase in rocket launches). A multi-purpose low-earth-orbit system of rings circling the earth - the "LEO ARCHIPELAGO TM" - is proposed as a means of solving or bypassing many of them. A fiber-optic ring about the earth would be an initial testing and developmental stage for the Ring Systems, while providing cash-flow through a LEO-based, high-band-width, world-wide communication system. A low-earth-orbit-based space-elevator system, "Sling-on-a-Ring TM", is proposed as the crucial developmental stage of the LEO Archipelago. Being a LEO-based heavy-mass lifter, rather than earth- or GEO-based, it is much less massive and therefore less costly than other proposed space-elevators. With the advent of lower-cost, higher-mass transport to orbit, the options for further space development (e.g., space solar power, radiation, and space-debris dampers, sun shades, and permanent LEO habitation) are greatly expanded. This paper provides an update of the Sling-on-a-Ring concept in terms of new materials, potential applications, and trade-offs associated with an earlier model. The impact of Colossal Carbon Tubes, CCT, a new material with high tensile strength, extremely-low density, and other favorable properties, and other new technologies (e.g., solar-powered lasers, power beaming to near-space and earth, and thermal-control systems) on the development of associated LEO-Ring systems is also explored. The material's effect on the timeline for the system development indicates the feasibility of near-term implementation of the system (possibly within the decade). The Sling-on-a-Ring can provide a less-expensive, environment-friendly mode of access to space. This would pave the way (via eventual operation at >1000 t per day by 2050) for large scale development of space

  4. Ringing wormholes

    SciTech Connect

    Konoplya, R.A.; Molina, C.

    2005-06-15

    We investigate the response of traversable wormholes to external perturbations through finding their characteristic frequencies and time-domain profiles. The considered solution describes traversable wormholes between the branes in the two brane Randall-Sundrum model and was previously found within Einstein gravity with a conformally coupled scalar field. The evolution of perturbations of a wormhole is similar to that of a black hole and represents damped oscillations (ringing) at intermediately late times, which are suppressed by power-law tails (proportional to t{sup -2} for monopole perturbations) at asymptotically late times.

  5. ABC and IFC: Modules Detection Method for PPI Network

    PubMed Central

    Lei, Xiujuan; Tian, Jianfang

    2014-01-01

    Many clustering algorithms are unable to solve the clustering problem of protein-protein interaction (PPI) networks effectively. A novel clustering model which combines the optimization mechanism of artificial bee colony (ABC) with the fuzzy membership matrix is proposed in this paper. The proposed ABC-IFC clustering model contains two parts: searching for the optimum cluster centers using ABC mechanism and forming clusters using intuitionistic fuzzy clustering (IFC) method. Firstly, the cluster centers are set randomly and the initial clustering results are obtained by using fuzzy membership matrix. Then the cluster centers are updated through different functions of bees in ABC algorithm; then the clustering result is obtained through IFC method based on the new optimized cluster center. To illustrate its performance, the ABC-IFC method is compared with the traditional fuzzy C-means clustering and IFC method. The experimental results on MIPS dataset show that the proposed ABC-IFC method not only gets improved in terms of several commonly used evaluation criteria such as precision, recall, and P value, but also obtains a better clustering result. PMID:24991575

  6. Learning the ABC of oral fungal drug resistance.

    PubMed

    Cannon, R D; Holmes, A R

    2015-12-01

    ATP-binding cassette (ABC) proteins are ubiquitous in prokaryotes and eukaryotes. They are involved in energy-dependent transport of molecules across membranes. ABC proteins are often promiscuous transporters that can translocate a variety of substrates. In oral fungi, especially in Candida species, they have been implicated as major contributors to the high-level azole resistance of clinical isolates from infections that do not respond to drug therapy. Although this is predominantly due to efflux of azoles from the cells, ABC proteins can contribute to fungal drug resistance in other ways as well. Cells in biofilms are notoriously resistant to antifungal agents. ABC proteins can contribute to this resistance through the efflux of drugs. Biofilms are complex communities of myriad microorganisms which, to survive in such a milieu, need to communicate with, and respond to, other microorganisms and their products. ABC proteins are involved in the secretion of fungal mating factors and quorum sensing molecules. These molecules affect biofilm structure and behavior that can result in increased drug resistance. Hence, ABC proteins make multiple contributions to oral fungal drug resistance through a variety of responses to environmental signals. PMID:26042641

  7. Structural basis for the mechanism of ABC transporters.

    PubMed

    Beis, Konstantinos

    2015-10-01

    The ATP-binding cassette (ABC) transporters are primary transporters that couple the energy stored in adenosine triphosphate (ATP) to the movement of molecules across the membrane. ABC transporters can be divided into exporters and importers; importers mediate the uptake of essential nutrients into cells and are found predominantly in prokaryotes whereas exporters transport molecules out of cells or into organelles and are found in all organisms. ABC exporters have been linked with multi-drug resistance in both bacterial and eukaryotic cells. ABC transporters are powered by the hydrolysis of ATP and transport their substrate via the alternating access mechanism, whereby the protein alternates between a conformation in which the substrate-binding site is accessible from the outside of the membrane, outward-facing and one in which it is inward-facing. In this mini-review, the structures of different ABC transporter types in different conformations are presented within the context of the alternating access mechanism and how they have shaped our current understanding of the mechanism of ABC transporters.

  8. ABCE1 Is a Highly Conserved RNA Silencing Suppressor

    PubMed Central

    Kärblane, Kairi; Gerassimenko, Jelena; Nigul, Lenne; Piirsoo, Alla; Smialowska, Agata; Vinkel, Kadri; Kylsten, Per; Ekwall, Karl; Swoboda, Peter; Truve, Erkki; Sarmiento, Cecilia

    2015-01-01

    ATP-binding cassette sub-family E member 1 (ABCE1) is a highly conserved protein among eukaryotes and archaea. Recent studies have identified ABCE1 as a ribosome-recycling factor important for translation termination in mammalian cells, yeast and also archaea. Here we report another conserved function of ABCE1. We have previously described AtRLI2, the homolog of ABCE1 in the plant Arabidopsis thaliana, as an endogenous suppressor of RNA silencing. In this study we show that this function is conserved: human ABCE1 is able to suppress RNA silencing in Nicotiana benthamiana plants, in mammalian HEK293 cells and in the worm Caenorhabditis elegans. Using co-immunoprecipitation and mass spectrometry, we found a number of potential ABCE1-interacting proteins that might support its function as an endogenous suppressor of RNA interference. The interactor candidates are associated with epigenetic regulation, transcription, RNA processing and mRNA surveillance. In addition, one of the identified proteins is translin, which together with its binding partner TRAX supports RNA interference. PMID:25659154

  9. Learning the ABC of oral fungal drug resistance.

    PubMed

    Cannon, R D; Holmes, A R

    2015-12-01

    ATP-binding cassette (ABC) proteins are ubiquitous in prokaryotes and eukaryotes. They are involved in energy-dependent transport of molecules across membranes. ABC proteins are often promiscuous transporters that can translocate a variety of substrates. In oral fungi, especially in Candida species, they have been implicated as major contributors to the high-level azole resistance of clinical isolates from infections that do not respond to drug therapy. Although this is predominantly due to efflux of azoles from the cells, ABC proteins can contribute to fungal drug resistance in other ways as well. Cells in biofilms are notoriously resistant to antifungal agents. ABC proteins can contribute to this resistance through the efflux of drugs. Biofilms are complex communities of myriad microorganisms which, to survive in such a milieu, need to communicate with, and respond to, other microorganisms and their products. ABC proteins are involved in the secretion of fungal mating factors and quorum sensing molecules. These molecules affect biofilm structure and behavior that can result in increased drug resistance. Hence, ABC proteins make multiple contributions to oral fungal drug resistance through a variety of responses to environmental signals.

  10. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David R.

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receive a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  11. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2000-01-01

    An all-refelctive optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six refelecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  12. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first concave mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 12.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 15.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 7 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 14 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than 16.0 .mu.m.

  13. High numerical aperture ring field projection system for extreme ultraviolet lithography

    DOEpatents

    Hudyma, Russell; Shafer, David

    2001-01-01

    An all-reflective optical system for a projection photolithography camera has a source of EUV radiation, a wafer and a mask to be imaged on the wafer. The optical system includes a first convex mirror, a second mirror, a third convex mirror, a fourth concave mirror, a fifth convex mirror and a sixth concave mirror. The system is configured such that five of the six mirrors receives a chief ray at an incidence angle of less than substantially 9.degree., and each of the six mirrors receives a chief ray at an incidence angle of less than substantially 14.degree.. Four of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Five of the six reflecting surfaces have an aspheric departure of less than substantially 12 .mu.m. Each of the six reflecting surfaces has an aspheric departure of less than substantially 16 .mu.m.

  14. Physics of planetary rings

    NASA Astrophysics Data System (ADS)

    Gorkavyi, N.

    2007-08-01

    It is difficult to enumerate all the surprises presented by the planetary rings. The Saturnian rings are stratified into thousands of ringlets and the Uranian rings are compressed into narrow streams, which for some reason or other differ from circular orbits like the wheel of an old bicycle. The edge of the rings is jagged and the rings themselves are pegged down under the gravitational pressure of the satellites, bending like a ship's wake. There are spiral waves, elliptical rings, strange interlacing of narrow ringlets, and to cap it all one has observed in the Neptunian ring system three dense, bright arcs - like bunches of sausages on a transparent string. For celestial mechanics this is a spectacle as unnatural as a bear's tooth in the necklace of the English queen. In the dynamics of planetary rings the physics of collective interaction was supplemented by taking collisions between particles into account. One was led to study a kinetic equation with a rather complex collision integral - because the collisions are inelastic - which later on made it possible, both by using the Chapman-Enskog method and by using the solution of the kinetic equation for a plasma in a magnetic field, to reduce it to a closed set of (hydrodynamical) moment equations [1]. The hydrodynamical instabilities lead to the growth of short-wavelength waves and large-scale structures of the Saturnian rings [1]. We have shown that the formation of the existing dense Uranian rings is connected with the capture of positively drifting ring particles in inner Lindblad resonances which arrest this drift [1]. After the formation of dense rings at the positions of satellite resonances the collective interaction between resonant particles is amplified and the rings can leave the resonance and drift away from the planet and the parent resonance. We can expect in the C ring an appreciable positive ballistic particle drift caused by the erosion of the B ring by micrometeorites. It is therefore natural

  15. Rings from Close Encounters

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-09-01

    Weve recently discovered narrow sets of rings around two minor planets orbiting in our solar system. How did these rings form? A new study shows that they could be a result of close encounters between the minor planets and giants like Jupiter or Neptune.Unexpected Ring SystemsPositions of the centaurs in our solar system (green). Giant planets (red), Jupiter trojans (grey), scattered disk objects (tan) and Kuiper belt objects (blue) are also shown. [WilyD]Centaurs are minor planets in our solar system that orbit between Jupiter and Neptune. These bodies of which there are roughly 44,000 with diameters larger than 1 km have dynamically unstable orbits that cross paths with those of one or more giant planets.Recent occultation observations of two centaurs, 10199 Chariklo and 2060 Chiron, revealed that these bodies both host narrow ring systems. Besides our four giant planets, Chariklo and Chiron are the only other bodies in the solar system known to have rings. But how did these rings form?Scientists have proposed several models, implicating collisions, disruption of a primordial satellite, or dusty outgassing. But a team of scientists led by Ryuki Hyodo (Paris Institute of Earth Physics, Kobe University) has recently proposed an alternative scenario: what if the rings were formed from partial disruption of the centaur itself, after it crossed just a little too close to a giant planet?Tidal Forces from a GiantHyodo and collaborators first used past studies of centaur orbits to estimate that roughly 10% of centaurs experience close encounters (passing within a distance of ~2x the planetary radius) with a giant planet during their million-year lifetime. The team then performed a series of simulations of close encounters between a giant planet and a differentiated centaur a body in which the rocky material has sunk to form a dense silicate core, surrounded by an icy mantle.Some snapshots of simulation outcomes (click for a closer look!) for different initial states of

  16. Total synthesis and evaluation of vinblastine analogues containing systematic deep-seated modifications in the vindoline subunit ring system: core redesign.

    PubMed

    Schleicher, Kristin D; Sasaki, Yoshikazu; Tam, Annie; Kato, Daisuke; Duncan, Katharine K; Boger, Dale L

    2013-01-24

    The total synthesis of a systematic series of vinblastine analogues that contain deep-seated structural modifications to the core ring system of the lower vindoline subunit is described. Complementary to the vindoline 6,5 DE ring system, compounds with 5,5, 6,6, and the reversed 5,6 membered DE ring systems were prepared. Both the natural cis and unnatural trans 6,6-membered ring systems proved accessible, with the latter representing a surprisingly effective class for analogue design. Following Fe(III)-promoted coupling with catharanthine and in situ oxidation to provide the corresponding vinblastine analogues, their evaluation provided unanticipated insights into how the structure of the vindoline subunit contributes to activity. Two potent analogues (81 and 44) possessing two different unprecedented modifications to the vindoline subunit core architecture were discovered that matched the potency of the comparison natural products and both lack the 6,7-double bond whose removal in vinblastine leads to a 100-fold drop in activity.

  17. Conformational dynamics in substrate-binding domains influences transport in the ABC importer GlnPQ.

    PubMed

    Gouridis, Giorgos; Schuurman-Wolters, Gea K; Ploetz, Evelyn; Husada, Florence; Vietrov, Ruslan; de Boer, Marijn; Cordes, Thorben; Poolman, Bert

    2015-01-01

    The conformational dynamics in ABC transporters is largely elusive. The ABC importer GlnPQ from Lactococcus lactis has different covalently linked substrate-binding domains (SBDs), thus making it an excellent model system to elucidate the dynamics and role of the SBDs in transport. We demonstrate by single-molecule spectroscopy that the two SBDs intrinsically transit from open to closed ligand-free conformation, and the proteins capture their amino acid ligands via an induced-fit mechanism. High-affinity ligands elicit transitions without changing the closed-state lifetime, whereas low-affinity ligands dramatically shorten it. We show that SBDs in the closed state compete for docking onto the translocator, but remarkably the effect is strongest without ligand. We find that the rate-determining steps depend on the SBD and the amino acid transported. We conclude that the lifetime of the closed conformation controls both SBD docking to the translocator and substrate release.

  18. Ground Movement in SSRL Ring

    SciTech Connect

    Sunikumar, Nikita; /UCLA /SLAC

    2011-08-25

    Users of the Stanford Synchrotron Radiation Lightsource (SSRL) are being affected by diurnal motion of the synchrotron's storage ring, which undergoes structural changes due to outdoor temperature fluctuations. In order to minimize the effects of diurnal temperature fluctuations, especially on the vertical motion of the ring floor, scientists at SSRL tried three approaches: painting the storage ring white, covering the asphalt in the middle of the ring with highly reflective Mylar and installing Mylar on a portion of the ring roof and walls. Vertical motion in the storage ring is measured by a Hydrostatic Leveling System (HLS), which calculates the relative height of water in a pipe that extends around the ring. The 24-hr amplitude of the floor motion was determined using spectral analysis of HLS data, and the ratio of this amplitude before and after each experiment was used to quantitatively determine the efficacy of each approach. The results of this analysis showed that the Mylar did not have any significant effect on floor motion, although the whitewash project did yield a reduction in overall HLS variation of 15 percent. However, further analysis showed that the reduction can largely be attributed to a few local changes rather than an overall reduction in floor motion around the ring. Future work will consist of identifying and selectively insulating these local regions in order to find the driving force behind diurnal floor motion in the storage ring.

  19. Optimal ABC inventory classification using interval programming

    NASA Astrophysics Data System (ADS)

    Rezaei, Jafar; Salimi, Negin

    2015-08-01

    Inventory classification is one of the most important activities in inventory management, whereby inventories are classified into three or more classes. Several inventory classifications have been proposed in the literature, almost all of which have two main shortcomings in common. That is, the previous methods mainly rely on an expert opinion to derive the importance of the classification criteria which results in subjective classification, and they need precise item parameters before implementing the classification. While the problem has been predominantly considered as a multi-criteria, we examine the problem from a different perspective, proposing a novel optimisation model for ABC inventory classification in the form of an interval programming problem. The proposed interval programming model has two important features compared to the existing methods: it provides optimal results instead of an expert-based classification and it does not require precise values of item parameters, which are not almost always available before classification. Finally, by illustrating the proposed classification model in the form of numerical example, conclusion and suggestions for future works are presented.

  20. Mu-28: an open-framework fluorogallophosphate with a three-dimensional 12-membered ring channel system

    SciTech Connect

    Josien, Ludovic; Simon-Masseron, Angelique . E-mail: a.simon@univ-mulhouse.fr; Gramlich, Volker; Porcher, Florence; Patarin, Jogl

    2004-10-01

    A new three-dimensional (3-D) microporous fluorogallophosphate, named Mu-28, was obtained by hydrothermal synthesis. It was obtained in the presence of fluoride ions with 1,4-dimethylpiperazine as organic template. This new fluorogallophosphate, with chemical formula [Ga{sub 20}P{sub 20}O{sub 80}(OH){sub 6}F{sub 6}(H{sub 2}O){sub 4}(C{sub 6}H{sub 16}N{sub 2}){sub 6}] 8H{sub 2}O, crystallizes in the monoclinic system space group P2{sub 1} with the following unit cell parameters: a=13.23(1)A, b=15.40(1)A, c=14.80(1)A, {beta}=95.10(9){sup o} (Z=1, R1=0.0435 [I>2{sigma}(I)]). Its structure was determined by single-crystal X-ray diffraction with the help of {sup 31}P NMR spectroscopy. Mu-28 consists of a complex arrangement of GaO{sub 3}(OH,F)(H{sub 2}O){sub 2}, GaO{sub 4}(OH)F and GaO{sub 4}(OH){sub 2} octahedra, GaO{sub 4}F trigonal bipyramids and GaO{sub 3}(OH,F) and PO{sub 4} tetrahedra. It displays a 3-D channel system delimited by 12-membered ring openings.

  1. A free-flowing soap film combined with cavity ring-down spectroscopy as a detection system for liquid chromatography.

    PubMed

    Vogelsang, Markus; Welsch, Thomas; Jones, Harold

    2010-05-01

    We have shown that a free-flowing soap film has sufficiently high-quality optical properties to allow it to be used in the cavity of a ring-down spectrometer (CRDS). The flow rates required to maintain a stable soap film were similar to those used in liquid chromatography and thus allowed interfacing with an HPLC system for use as an optical detector. We have investigated the properties of the system in a relevant analytical application. The soap film/CRDS combination was used at 355 nm as a detector for the separation of a mixture of nitroarenes. These compounds play a role in the residue analysis of areas contaminated with explosives and their decomposition products. In spite of the short absorption path length (9 microm) obtained by the soap film, the high-sensitivity of CRDS allowed a limit of detection of 4 x 10(-6) in absorption units (AU) or less than 17 fmol in the detection volume to be achieved.

  2. Operations with the digital orbit feedback system in the NSLS x-ray ring

    SciTech Connect

    Bozoki, E.; Rammamorthy, S.; Singh, O.; Tang, Y.; Friedman, A.

    1996-05-01

    The digital filtering and eigenvector decomposition-based orbit correction is performed by two dedicated HP 742/743 rt micros which communicate with Motorola CPU based orbit-measuring and orbit-correction systems. The correction algorithm in the DFbk was orthogonalized with respect of the analog global harmonic feedback. Operational results concerning improvements in the noise suppression at low frequencies and especially in the dc drift as well as in the orbit stability are shown. Efforts are underway to improve the resolution of the orbit measuing system and the sampling rate using 16 bit 400 kHz ADC`s which will allow orbit sampling with high resolution at 4 kHz frequency.

  3. ABC transporters involved in the biogenesis of the outer membrane in gram-negative bacteria.

    PubMed

    Narita, Shin-ichiro

    2011-01-01

    The outer membrane of gram-negative bacteria is an asymmetric lipid bilayer with phospholipids and lipopolysaccharides (LPSs). β-Barreled outer membrane proteins and lipoproteins are embedded in the outer membrane. All of these constituents are essential to the function of the outer membrane. The transport systems for lipoproteins have been characterized in detail. An ATP-binding cassette (ABC) transporter, LolCDE, initiates sorting by mediating the detachment of lipoproteins from the inner membrane to form a water-soluble lipoprotein-LolA complex in the periplasm. Lipoproteins are then transferred to LolB at the outer membrane and are incorporated into the lipid bilayer. A model analogous to the Lol system has been suggested for the transport of LPS, where an ABC transporter, LptBFG, mediates the detachment of LPS from the inner membrane. Recent developments in the functional characterization of ABC transporters involved in the biogenesis of the outer membrane in gram-negative bacteria are discussed. PMID:21670534

  4. Synthetic and Computational Studies on the ABC Trioxadispiroketal Subunit of the Marine Biotoxin Azaspiracid-1

    PubMed Central

    Li, Jialiang; Li, Xiaohua; Mootoo, David R.

    2009-01-01

    The trioxadispiroketal residue in the marine biotoxin azaspiracid-1, which exists in a configuration capable of exhibiting a double anomeric effect, is believed to be the thermodynamically most stable bis-spiroketal diastereomer. In order to get insight into how structural factors affect this equilibrium, a simplified ABC trioxadispiroketal analog of azaspiracid-1 was synthesized and subjected to equilbration and computational studies. Compound 7, which represents a double anomeric effect was obtained as the major isomer, together with diastereomers 14 and 15, in a respective ratio of 62:22:16. DFT calculations for 7, 14 and 15 qualitatively matched this observation. These results suggest that while a double anomeric effect may play a major role in the stability of the trioxadispiroketal configuration in the more complex natural product, the substitution pattern of the C ring is also a contributing factor. PMID:19759853

  5. Complex microstructures of ABC triblock copolymer thin films directed by polymer brushes based on self-consistent field theory.

    PubMed

    Jiang, Zhibin; Xu, Chang; Qiu, Yu Dong; Wang, Xiaoliang; Zhou, Dongshan; Xue, Gi

    2014-01-01

    The morphology and the phase diagram of ABC triblock copolymer thin film directed by polymer brushes are investigated by the self-consistent field theory in three dimensions. The polymer brushes coated on the substrate can be used as a good soft template to tailor the morphology of the block copolymer thin films compared with those on the hard substrates. The polymer brush is identical with the middle block B. By continuously changing the composition of the block copolymer, the phase diagrams are constructed for three cases with the fixed film thickness and the brush density: identical interaction parameters, frustrated and non-frustrated cases. Some ordered complex morphologies are observed: parallel lamellar phase with hexagonally packed pores at surfaces (LAM3 (ll) -HFs), perpendicular lamellar phase with cylinders at the interface (LAM(⊥)-CI), and perpendicular hexagonally packed cylinders phase with rings at the interface (C2 (⊥)-RI). A desired direction (perpendicular or parallel to the coated surfaces) of lamellar phases or cylindrical phases can be obtained by varying the composition and the interactions between different blocks. The phase diagram of ABC triblock copolymer thin film wetted between the polymer brush-coated surfaces is very useful in designing the directed pattern of ABC triblock copolymer thin film. PMID:25114650

  6. Substrate binding by a bacterial ABC transporter involved in polysaccharide export

    SciTech Connect

    Cuthbertson, Leslie; Kimber, Matthew S.; Whitfield, Chris

    2008-04-02

    ATP-binding-cassette (ABC) transporters are responsible for the export of a wide variety of cell-surface glycoconjugates in both Gram-positive and Gram-negative bacteria. These include the O-antigenic polysaccharide (O-PS) portion of lipopolysaccharide, a crucial virulence determinant in Gram-negative pathogens. O-PSs are synthesized by one of two fundamentally different pathways. Escherichia coli O serotypes O8 and O9a provide the prototype systems for studying O-PS export via ABC transporters. The transporter is composed of the transmembrane component Wzm and the nucleotide-binding component Wzt. Although the N-terminal domain of Wzt is a conventional ABC protein, the C-terminal domain of Wzt (C-Wzt) is a unique structural element that determines the specificity of the transporter for either the O8 or O9a O-PS. We show here that the two domains of Wzt can function when expressed as separate polypeptides; both are essential for export. In vitro, C-Wzt binds its cognate O-PS by recognizing a residue located at the nonreducing end of the polymer. The crystal structure of C-WztO9a is reported here and reveals a {beta} sandwich with an immunoglobulin-like topology that contains the O-PS-binding pocket. Substrate interactions with nucleotide-binding domains have been demonstrated in an ABC exporter previously. However, to our knowledge substrate binding by a discrete, cytoplasmic accessory domain in an extended nucleotide-binding domain polypeptide has not previously been demonstrated. Elucidation of the substrate-recognition system involved in O-PS export provides insight into the mechanism that coordinates polymer biosynthesis, termination, and export.

  7. IMG-ABC. A knowledge base to fuel discovery of biosynthetic gene clusters and novel secondary metabolites

    DOE PAGES

    Hadjithomas, Michalis; Chen, I-Min Amy; Chu, Ken; Ratner, Anna; Palaniappan, Krishna; Szeto, Ernest; Huang, Jinghua; Reddy, T. B. K.; Cimermančič, Peter; Fischbach, Michael A.; et al

    2015-07-14

    In the discovery of secondary metabolites, analysis of sequence data is a promising exploration path that remains largely underutilized due to the lack of computational platforms that enable such a systematic approach on a large scale. In this work, we present IMG-ABC (https://img.jgi.doe.gov/abc), an atlas of biosynthetic gene clusters within the Integrated Microbial Genomes (IMG) system, which is aimed at harnessing the power of “big” genomic data for discovering small molecules. IMG-ABC relies on IMG’s comprehensive integrated structural and functional genomic data for the analysis of biosynthetic gene clusters (BCs) and associated secondary metabolites (SMs). SMs and BCs serve asmore » the two main classes of objects in IMG-ABC, each with a rich collection of attributes. A unique feature of IMG-ABC is the incorporation of both experimentally validated and computationally predicted BCs in genomes as well as metagenomes, thus identifying BCs in uncultured populations and rare taxa. We demonstrate the strength of IMG-ABC’s focused integrated analysis tools in enabling the exploration of microbial secondary metabolism on a global scale, through the discovery of phenazine-producing clusters for the first time in lphaproteobacteria. IMG-ABC strives to fill the long-existent void of resources for computational exploration of the secondary metabolism universe; its underlying scalable framework enables traversal of uncovered phylogenetic and chemical structure space, serving as a doorway to a new era in the discovery of novel molecules. IMG-ABC is the largest publicly available database of predicted and experimental biosynthetic gene clusters and the secondary metabolites they produce. The system also includes powerful search and analysis tools that are integrated with IMG’s extensive genomic/metagenomic data and analysis tool kits. As new research on biosynthetic gene clusters and secondary metabolites is published and more genomes are sequenced, IMG-ABC

  8. IMG-ABC. A knowledge base to fuel discovery of biosynthetic gene clusters and novel secondary metabolites

    SciTech Connect

    Hadjithomas, Michalis; Chen, I-Min Amy; Chu, Ken; Ratner, Anna; Palaniappan, Krishna; Szeto, Ernest; Huang, Jinghua; Reddy, T. B. K.; Cimermančič, Peter; Fischbach, Michael A.; Ivanova, Natalia N.; Markowitz, Victor M.; Kyrpides, Nikos C.; Pati, Amrita

    2015-07-14

    In the discovery of secondary metabolites, analysis of sequence data is a promising exploration path that remains largely underutilized due to the lack of computational platforms that enable such a systematic approach on a large scale. In this work, we present IMG-ABC (https://img.jgi.doe.gov/abc), an atlas of biosynthetic gene clusters within the Integrated Microbial Genomes (IMG) system, which is aimed at harnessing the power of “big” genomic data for discovering small molecules. IMG-ABC relies on IMG’s comprehensive integrated structural and functional genomic data for the analysis of biosynthetic gene clusters (BCs) and associated secondary metabolites (SMs). SMs and BCs serve as the two main classes of objects in IMG-ABC, each with a rich collection of attributes. A unique feature of IMG-ABC is the incorporation of both experimentally validated and computationally predicted BCs in genomes as well as metagenomes, thus identifying BCs in uncultured populations and rare taxa. We demonstrate the strength of IMG-ABC’s focused integrated analysis tools in enabling the exploration of microbial secondary metabolism on a global scale, through the discovery of phenazine-producing clusters for the first time in lphaproteobacteria. IMG-ABC strives to fill the long-existent void of resources for computational exploration of the secondary metabolism universe; its underlying scalable framework enables traversal of uncovered phylogenetic and chemical structure space, serving as a doorway to a new era in the discovery of novel molecules. IMG-ABC is the largest publicly available database of predicted and experimental biosynthetic gene clusters and the secondary metabolites they produce. The system also includes powerful search and analysis tools that are integrated with IMG’s extensive genomic/metagenomic data and analysis tool kits. As new research on biosynthetic gene clusters and secondary metabolites is published and more genomes are sequenced, IMG-ABC

  9. Cavity-locked ring down spectroscopy

    DOEpatents

    Zare, Richard N.; Paldus, Barbara A.; Harb, Charles C.; Spence, Thomas

    2000-01-01

    Distinct locking and sampling light beams are used in a cavity ring-down spectroscopy (CRDS) system to perform multiple ring-down measurements while the laser and ring-down cavity are continuously locked. The sampling and locking light beams have different frequencies, to ensure that the sampling and locking light are decoupled within the cavity. Preferably, the ring-down cavity is ring-shaped, the sampling light is s-polarized, and the locking light is p-polarized. Transmitted sampling light is used for ring-down measurements, while reflected locking light is used for locking in a Pound-Drever scheme.

  10. Saturn's Rings Edge-on

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.

    For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.

    The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.

    This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).

    Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science

  11. Beamloading compensation of the rf system for the storage ring of the advanced photon source (APS)

    NASA Astrophysics Data System (ADS)

    Bridges, J.; Stepp, J.

    1994-10-01

    A brief overview of the rf system is given. Design and operating parameters for the klystron amplifiers powering the single cell cavities are described with operating parameters for various positron beam intensities and for optimization of the feedback loops. Klystron efficiencies are low except in saturated operation, but any feedback loop around the klystron requires at least some klystron gain. The gain in the amplitude feedback loop must be adjusted to compensate for saturation. The operating point of the klystron may be dynamically adjusted through a pre-programmed computer or dedicated local processor. Feed forward techniques may be used to alter the program based on beam intensity over the ten-hour storage cycle, using a new digitizer module from Hewlett-Packard. Reduction of the cavity impedance for multi-bunch operation is also described.

  12. Function of prokaryotic and eukaryotic ABC proteins in lipid transport.

    PubMed

    Pohl, Antje; Devaux, Philippe F; Herrmann, Andreas

    2005-03-21

    ATP binding cassette (ABC) proteins of both eukaryotic and prokaryotic origins are implicated in the transport of lipids. In humans, members of the ABC protein families A, B, C, D and G are mutated in a number of lipid transport and metabolism disorders, such as Tangier disease, Stargardt syndrome, progressive familial intrahepatic cholestasis, pseudoxanthoma elasticum, adrenoleukodystrophy or sitosterolemia. Studies employing transfection, overexpression, reconstitution, deletion and inhibition indicate the transbilayer transport of endogenous lipids and their analogs by some of these proteins, modulating lipid transbilayer asymmetry. Other proteins appear to be involved in the exposure of specific lipids on the exoplasmic leaflet, allowing their uptake by acceptors and further transport to specific sites. Additionally, lipid transport by ABC proteins is currently being studied in non-human eukaryotes, e.g. in sea urchin, trypanosomatides, arabidopsis and yeast, as well as in prokaryotes such as Escherichia coli and Lactococcus lactis. Here, we review current information about the (putative) role of both pro- and eukaryotic ABC proteins in the various phenomena associated with lipid transport. Besides providing a better understanding of phenomena like lipid metabolism, circulation, multidrug resistance, hormonal processes, fertilization, vision and signalling, studies on pro- and eukaryotic ABC proteins might eventually enable us to put a name on some of the proteins mediating transbilayer lipid transport in various membranes of cells and organelles. It must be emphasized, however, that there are still many uncertainties concerning the functions and mechanisms of ABC proteins interacting with lipids. In particular, further purification and reconstitution experiments with an unambiguous role of ATP hydrolysis are needed to demonstrate a clear involvement of ABC proteins in lipid transbilayer asymmetry. PMID:15749056

  13. Control of zinc homeostasis in Agrobacterium tumefaciens via zur and the zinc uptake genes znuABC and zinT.

    PubMed

    Bhubhanil, Sakkarin; Sittipo, Panida; Chaoprasid, Paweena; Nookabkaew, Sumontha; Sukchawalit, Rojana; Mongkolsuk, Skorn

    2014-11-01

    The Agrobacterium tumefaciens zinc uptake regulator (Zur) was shown to negatively regulate the zinc uptake genes znuABC, encoding a zinc transport system belonging to the ATP-binding cassette (ABC) transporter family, and zinT, which encodes a periplasmic zinc-binding protein. The expression of znuABC and zinT was inducible when cells were grown in medium containing a metal chelator (EDTA), and this induction was shown to be specific for zinc depletion. The expression of znuABC was reduced in response to increased zinc in a dose-dependent manner, and zinT had a less pronounced but similar pattern of zinc-regulated expression. The inactivation of zur led to constitutively high expression of znuABC and zinT. In addition, a zur mutant had an increased total zinc content compared to the WT NTL4 strain, whereas the inactivation of zinT caused a reduction in the total zinc content. The zinT gene is shown to play a dominant role and to be more important than znuA and znuB for A. tumefaciens survival under zinc deprivation. ZinT can function even when ZnuABC is inactivated. However, mutations in zur, znuA, znuB or zinT did not affect the virulence of A. tumefaciens. PMID:25227896

  14. Compact stellar systems in the polar ring galaxies NGC 4650A and NGC 3808B: Clues to polar disk formation

    NASA Astrophysics Data System (ADS)

    Ordenes-Briceño, Yasna; Georgiev, Iskren Y.; Puzia, Thomas H.; Goudfrooij, Paul; Arnaboldi, Magda

    2016-01-01

    Context. Polar ring galaxies (PRGs) are composed of two kinematically distinct and nearly orthogonal components, a host galaxy (HG) and a polar ring/disk (PR). The HG usually contains an older stellar population than the PR. The suggested formation channel of PRGs is still poorly constrained. Suggested options are merger, gas accretion, tidal interaction, or a combination of both. Aims: To constrain the formation scenario of PRGs, we study the compact stellar systems (CSSs) in two PRGs at different evolutionary stages: NGC 4650A with well-defined PR, and NGC 3808 B, which is in the process of PR formation. Methods: We use archival HST/WFPC2 imaging in the F450W, F555W, or F606W and F814W filters. Extensive completeness tests, PSF-fitting techniques, and color selection criteria are used to select cluster candidates. Photometric analysis of the CSSs was performed to determine their ages and masses using stellar population models at a fixed metallicity. Results: Both PRGs contain young CSSs (<1 Gyr) with masses of up to 5 × 106M⊙, mostly located in the PR and along the tidal debris. The most massive CSSs may be progenitors of metal-rich globular clusters or ultra compact dwarf (UCD) galaxies. We identify one such young UCD candidate, NGC 3808 B-8, and measure its size of reff = 25.23+1.43-2.01 pc. We reconstruct the star formation history of the two PRGs and find strong peaks in the star formation rate (SFR, ≃200 M⊙/yr) in NGC 3808 B, while NGC 4650 A shows milder (declining) star formation (SFR< 10 M⊙/yr). This difference may support different evolutionary paths between these PRGs. Conclusions: The spatial distribution, masses, and peak star formation epoch of the clusters in NGC 3808 suggest for a tidally triggered star formation. Incompleteness at old ages prevents us from probing the SFR at earlier epochs of NGC 4650 A, where we observe the fading tail of CSS formation. This also impedes us from testing the formation scenarios of this PRG.

  15. Synthesis and Characterization of High Performance Polyimides Containing the Bicyclo(2.2.2)oct-7-ene Ring System

    NASA Technical Reports Server (NTRS)

    Alvarado, M.; Harruna, I. I.; Bota, K. B.

    1997-01-01

    Due to the difficulty in processing polyimides with high temperature stability and good solvent resistance, we have synthesized high performance polyimides with bicyclo(2.2.2)-oct-7-ene ring system which can easily be fabricated into films and fibers and subsequently converted to the more stable aromatic polyimides. In order to improve processability, we prepared two polyimides by reacting 1,4-phenylenediamine and 1,3phenylediamine with bicyclo(2.2.2)-7-octene-2,3,5,6-tetracarboxylic dianhydride. The polyimides were characterized by FTIR, FTNMR, solubility and thermal analysis. Thermogravimetric analysis (TGA) showed that the 1,4-phenylenediamine and 1,3-phenylenediamine containing polyimides were stable up to 460 and 379 C, respectively under nitrogen atmosphere. No melting transitions were observed for both polyimides. The 1,4-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, methane sulfonic acid and soluble in sulfuric acid at room temperature. The 1,3-phenylenediamine containing polyimide is partially soluble in dimethyl sulfoxide, tetramethyl urea, N,N-dimethyl acetamide and soluble in methane sulfonic acid and sulfuric acid.

  16. A novel FPGA-based bunch purity monitor system at the APS storage ring.

    SciTech Connect

    Norum, W. E.; APS Engineering Support Division

    2008-01-01

    Bunch purity is an important source quality factor for the magnetic resonance experiments at the Advanced Photon Source. Conventional bunch-purity monitors utilizing time-to-amplitude converters are subject to dead time. We present a novel design based on a single field- programmable gate array (FPGA) that continuously processes pulses at the full speed of the detector and front-end electronics. The FPGA provides 7778 single-channel analyzers (six per rf bucket). The starting time and width of each single-channel analyzer window can be set to a resolution of 178 ps. A detector pulse arriving inside the window of a single-channel analyzer is recorded in an associated 32-bit counter. The analyzer makes no contribution to the system dead time. Two channels for each rf bucket count pulses originating from the electrons in the bucket. The other four channels on the early and late side of the bucket provide estimates of the background. A single-chip microcontroller attached to the FPGA acts as an EPICS IOC to make the information in the FPGA available to the EPICS clients.

  17. Alzheimer’s and ABC transporters - new opportunities for diagnostics and treatment

    PubMed Central

    Pahnke, Jens; Langer, Oliver; Krohn, Markus

    2014-01-01

    Much has been said about the increasing number of demented patients and the main risk factor ‘age’. Frustratingly, we do not know the precise pattern and all modulating factors that provoke the pathologic changes in the brains of affected elderly. We have to diagnose early to be able to stop the progression of diseases that irreversibly destroy brain substance. Familiar AD cases have mislead some researchers for almost 20 years, which has unfortunately narrowed the scientific understanding and has, thus, lead to insufficient funding of independent approaches. Therefore, basic researchers hardly have been able to develop causative treatments and clinicians still do not have access to prognostic and early diagnostic tools. During the recent years it became clear that insufficient Aβ export, physiologically facilitated by the ABC transporter superfamily at the brain’s barriers, plays a fundamental role in disease initiation and progression. Furthermore, export mechanisms that are deficient in affected elderly are new targets for activation and, thus, treatment, but ideally also for prevention. In sporadic AD disturbed clearance of β-amyloid from the brain is so far the most important factor for its accumulation in the parenchyma and vessel walls. Here, we review findings about the contribution of ABC transporters and of the perivascular drainage/glymphatic system on β-amyloid clearance. We highlight their potential value for innovative early diagnostics using PET and describe recently described, effective ABC transporter-targeting agents as potential causative treatment for neurodegenerative proteopathies/dementias. PMID:24746857

  18. Regulation of ABC efflux transporters at blood-brain barrier in health and neurological disorders.

    PubMed

    Qosa, Hisham; Miller, David S; Pasinelli, Piera; Trotti, Davide

    2015-12-01

    The strength of the blood-brain barrier (BBB) in providing protection to the central nervous system from exposure to circulating chemicals is maintained by tight junctions between endothelial cells and by a broad range of transporter proteins that regulate exchange between CNS and blood. The most important transporters that restrict the permeability of large number of toxins as well as therapeutic agents are the ABC transporters. Among them, P-gp, BCRP, MRP1 and MRP2 are the utmost studied. These efflux transporters are neuroprotective, limiting the brain entry of neurotoxins; however, they could also restrict the entry of many therapeutics and contribute to CNS pharmacoresistance. Characterization of several regulatory pathways that govern expression and activity of ABC efflux transporters in the endothelium of brain capillaries have led to an emerging consensus that these processes are complex and contain several cellular and molecular elements. Alterations in ABC efflux transporters expression and/or activity occur in several neurological diseases. Here, we review the signaling pathways that regulate expression and transport activity of P-gp, BCRP, MRP1 and MRP2 as well as how their expression/activity changes in neurological diseases. This article is part of a Special Issue entitled SI: Neuroprotection.

  19. Nitrite Transport Activity of the ABC-Type Cyanate Transporter of the Cyanobacterium Synechococcus elongatus▿

    PubMed Central

    Maeda, Shin-ichi; Omata, Tatsuo

    2009-01-01

    In addition to the ATP-binding cassette (ABC)-type nitrate/nitrite-bispecific transporter, which has a high affinity for both substrates (Km, ∼1 μM), Synechococcus elongatus has an active nitrite transport system with an apparent Km (NO2−) value of 20 μM. We found that this activity depends on the cynABD genes, which encode a putative cyanate (NCO−) ABC-type transporter. Accordingly, nitrite transport by CynABD was competitively inhibited by NCO− with a Ki value of 0.025 μM. The transporter was induced under conditions of nitrogen deficiency, and the induced cells showed a Vmax value of 11 to 13 μmol/mg of chlorophyll per h for cyanate or nitrite, which could supply ∼30% of the amount of nitrogen required for optimum growth. Its relative specificity for the substrates and regulation at transcriptional and posttranslational levels suggested that the physiological role of the bispecific cyanate/nitrite transporter in S. elongatus is to allow nitrogen-deficient cells to assimilate low concentrations of cyanate in the medium. Its contribution to nitrite assimilation was significant in a mutant lacking the ABC-type nitrate/nitrite transporter, suggesting a possible role for CynABD in nitrite assimilation by cyanobacterial species that lack another high-affinity mechanism(s) for nitrite transport. PMID:19286804

  20. Study of the use of methanol-filled Er-doped suspended-core fibres in a temperature-sensing ring laser system

    NASA Astrophysics Data System (ADS)

    Martín, J. C.; Berdejo, V.; Vallés, J. A.; Sánchez-Martín, J. A.; Díez, A.; Andrés, M. V.

    2013-10-01

    We report on an experimental/numerical investigation into the use of methanol-filled Er-doped suspended-core fibres (SCFs) in temperature-sensing ring laser systems. We have adopted a ring laser configuration that includes an Er-doped SCF as a temperature-dependent attenuator (TDA) with a step-index Er-doped fibre (EDF) as the laser active medium. The laser performance dependence on the temperature was measured both in continuous wave (CW) and transient regimes. CW laser output power and build-up time values are compared with those of similar laser systems based on other types of Er-doped PCFs or using other laser configurations. A notable variation of 0.73% °C-1 was achieved in CW operation. Then, by means of parameters obtained by numerically fitting the experimental results, the potential sensing performance of the laser configuration with an SCF as a TDA is studied. Moreover, two ring cavity laser configurations (with the SCF acting basically as an attenuator or also as the active media) are compared and the influence of the position of the coupler inside the ring cavity and the contribution of the erbium doping to improve the sensor features are analysed. The longer interaction lengths compatible with laser action using the Er-doped SCF as a TDA could provide variations of laser output power up to 8.6% °C-1 for 90 mW pump power and a 1 m methanol-filled SCF.

  1. Synthesis and biological evaluation of some polymethoxylated fused pyridine ring systems as antitumor agents.

    PubMed

    Rostom, Sherif A F; Hassan, Ghada S; El-Subbagh, Hussein I

    2009-10-01

    A series of 3,5-bis(arylidene)-4-piperidones like chalcone analogues carrying variety of methoxylated aryl groups, pyrazolo[4,3-c]pyridines, pyrido[4,3-d]pyrimidines, and pyrido[3,2-c]pyridines, carrying an arylidene moiety, and some pyrano[3,2-c]pyridines, like flavone and coumarin isosteres, were synthesized and screened for their in-vitro antitumor activity at the National Cancer Institute (NCI, USA). The tested compounds 7, 9, 10, 12, 13, 15, 17, and 19 exhibited a broad spectrum of antitumor activity. Compounds belonging to the pyrazolo[4,3-c]pyridine series proved to be more active than those of the pyrido[3,2-c]pyridine and pyrano[3,2-c]pyridine analogues, in which the monomethoxylated derivatives showed better antitumor activity when compared with their corresponding dimethoxylated congeners. Compound 7 is considered to be the most active member identified in this study with a broad spectrum of activity against 22 different tumor cell lines belonging to the nine subpanels employed, and a particular effectiveness against the breast cancer T-47D cell line (GI 54.7%). The pyrano[3,2-c]pyridine heterocyclic system 19 proved to be the most active antitumor agent among the six-membered fused pyridines, with variable activity against 18 different tumor cell lines, and special activity against the non-small cell lung cancer Hop-92 and ovarian cancer OVCAR-4 cell lines (GI values 63.9 and 48.5%, respectively).

  2. A bisphenol-A-based resin system that cures via triazole ring formation for marine composite applications

    NASA Astrophysics Data System (ADS)

    Gorman, Irene Elizabeth

    Large composite panels, such as those utilized in marine applications, cannot be economically cured in an autoclave. For these structures the elevated temperatures necessary to achieve high crosslink density must come from the curing reaction itself. We are developing a resin system that cures via triazole ring formation (cycloaddition reaction of azides with terminal alkynes) instead of the traditional oxirane/amine reaction. The high exothermicity of the azido/alkyne reaction is expected to yield higher extents of reaction under ambient-cure conditions, making the resin system potentially suitable for "out-of-autoclave" curing processes. This work was conducted through a multi-tiered approach involving synthesis, kinetic studies, thermal characterization, and mechanical analysis. The difunctional azide-terminated resin, di(3-azido-2 hydroxypropyl) ether of bisphenol-A (DAHP-BPA), was selected as the baseline diazide. A number of alkyne crosslinkers were synthesized and characterized, including propiolate esters of di- and trifunctional alcohols, propargyl esters of di- and trifunctional carboxylic acids, propargyl ethers of di- and trifunctional alcohols, and N,N,N',N'-tetrapropargyl derivatives of primary diamines. Commercially available tripropargylamine (TPA) was also studied. Curing energetics as a function of alkyne type and catalyst loading, investigated through a dynamic differential scanning calorimetry approach, displayed two distinct kinetic profiles when considering propiolate and propargyl type crosslinkers. Those systems employing a propiolate-based alkyne were found to be much more reactive towards the Huisgen 1,3-dipolar cycloaddition than the propargyl species. Additionally, the mechanical and thermal properties of resin systems, both un-catalyzed and catalyzed, composed of DAHP-BPA and tripropargyl amine were investigated by compression and rheological studies, differential scanning calorimetry, and thermogravametric analysis. The moduli of both

  3. Belt-hierarchic structure of th ring, satellite and planet systems: prediction S/2001 U1 and others objects in Solar system

    NASA Astrophysics Data System (ADS)

    Barkin, Yu. V.

    2003-04-01

    BELT-HIERARCHIC STRUCTURE OF THE RING, SATELLITE AND PLANET SYSTEMS: PREDICTION S/2001 U1 AND OTHERS OBJECTS IN SOLAR SYSTEM Yu.V.Barkin Sternberg Astronomical Institute, Moscow, Russia, barkin@sai.msu.ru Structure regularities of the planet and satellite systems have been studied. Statistic analysis of the distribution of the major semi-axes of the orbits of the planets, comets and centaurs of the Solar system, satellite and ring systems of Jupiter, Saturn, Neptune and Uran, exoplanet systems of the pulsars PSR 1257+12, PSR 1828-11 and of the main consequence star Ups And was fulfilled. The following empirical regularities were described [1]: 1) the bodies of systems are combined into hierarchic groups and main from them combine 5 companions; 2) differences of the major semi-axes of the neighboring orbits for bodies of every group are constant; 4) for main neighboring hierarchic group these distances are distinguished in 6 times increasing to external grope; 5) the filling of the gropes and some present changes in their structure are caused by the past catastrophes in corresponding systems. The special method of reconstruction of the catastrophes which had place in the life of the Solar system (SS) was developed. Suggested method has let us to explain uniformly observed values of the major semi-axes and average values of eccentricities of the planets. In particular the Pancul’s hypothesis about Jupiter formation from two giant protoplanets (Jupiter I and Jupiter II) was confirmed. The new empirical law of the filling of the orbits of the regular groups of the planets or satellites (or rings structures) of the hierarchic ordered systems of celestial bodies was established. It was shown that sum number of bodies is proportional to the value of catastrophic value of the eccentricities which are same for first, second ,.... and fifth orbits of all gropes. The theoretical numbers of bodies for pointed orbits practically coincide with their observed numbers in main

  4. Cloning of two novel ABC transporters mapping on human chromosome 9

    SciTech Connect

    Luciani, M.F.; Savary, S.; Chimini, G. ); Denizot, F. ); Mattei, M.G. )

    1994-05-01

    The family of ATP binding cassette (ABC) transporters or traffic ATPases is composed of several membrane-associated proteins that transport a great variety of solutes across cellular membranes. Two novel mammalian members of the family, ABC1 and ABC2, have been identified by a PCR-based approach. They belong to a group of traffic ATPases encoded as a single multifunctional protein, such as CFTR, STE 6, and P-glycoproteins. Their peculiar structural features and close relationship to ABC transporters involved in nodulation suggest that ABC1 and ABC2 define a novel subgroup of mammalian traffic ATPases. 51 refs., 7 figs.

  5. ABC transporters involved in export of cell surface glycoconjugates.

    PubMed

    Cuthbertson, Leslie; Kos, Veronica; Whitfield, Chris

    2010-09-01

    Complex glycoconjugates play critical roles in the biology of microorganisms. Despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. One of the primary pathways involves representatives of the ATP-binding cassette (ABC) transporter superfamily. These proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both Gram-positive and Gram-negative bacteria. Recent investigations of the structure and function of ABC transporters involved in the export of lipopolysaccharide O antigens have revealed two fundamentally different strategies for coupling glycan polymerization to export. These mechanisms are distinguished by the presence (or absence) of characteristic nonreducing terminal modifications on the export substrates, which serve as chain termination and/or export signals, and by the presence (or absence) of a discrete substrate-binding domain in the nucleotide-binding domain polypeptide of the ABC transporter. A bioinformatic survey examining ABC exporters from known oligo- and polysaccharide biosynthesis loci identifies conserved nucleotide-binding domain protein families that correlate well with themes in the structures and assembly of glycans. The familial relationships among the ABC exporters generate hypotheses concerning the biosynthesis of structurally diverse oligo- and polysaccharides, which play important roles in the biology of bacteria with different lifestyles.

  6. The ABC of Ribosome-Related Antibiotic Resistance.

    PubMed

    Wilson, Daniel N

    2016-01-01

    The increase in multidrug-resistant pathogenic bacteria is limiting the utility of our current arsenal of antimicrobial agents. Mechanistically understanding how bacteria obtain antibiotic resistance is a critical first step to the development of improved inhibitors. One common mechanism for bacteria to obtain antibiotic resistance is by employing ATP-binding cassette (ABC) transporters to actively pump the drug from the cell. The ABC-F family includes proteins conferring resistance to a variety of clinically important ribosome-targeting antibiotics; however, controversy remains as to whether resistance is conferred via efflux like other ABC transporters or whether another mechanism, such as ribosome protection, is at play. A recent study by Sharkey and coworkers (L. K. Sharkey, T. A. Edwards, and A. J. O'Neill, mBio 7:e01975-15, 2016, http://dx.doi.org/10.1128/mBio.01975-15) provides strong evidence that ABC-F proteins conferring antibiotic resistance utilize ribosome protection mechanisms, namely, by interacting with the ribosome and displacing the drug from its binding site, thus revealing a novel role for ABC-F proteins in antibiotic resistance. PMID:27143393

  7. The ABC of Ribosome-Related Antibiotic Resistance.

    PubMed

    Wilson, Daniel N

    2016-05-03

    The increase in multidrug-resistant pathogenic bacteria is limiting the utility of our current arsenal of antimicrobial agents. Mechanistically understanding how bacteria obtain antibiotic resistance is a critical first step to the development of improved inhibitors. One common mechanism for bacteria to obtain antibiotic resistance is by employing ATP-binding cassette (ABC) transporters to actively pump the drug from the cell. The ABC-F family includes proteins conferring resistance to a variety of clinically important ribosome-targeting antibiotics; however, controversy remains as to whether resistance is conferred via efflux like other ABC transporters or whether another mechanism, such as ribosome protection, is at play. A recent study by Sharkey and coworkers (L. K. Sharkey, T. A. Edwards, and A. J. O'Neill, mBio 7:e01975-15, 2016, http://dx.doi.org/10.1128/mBio.01975-15) provides strong evidence that ABC-F proteins conferring antibiotic resistance utilize ribosome protection mechanisms, namely, by interacting with the ribosome and displacing the drug from its binding site, thus revealing a novel role for ABC-F proteins in antibiotic resistance.

  8. ABC Transporters Involved in Export of Cell Surface Glycoconjugates

    PubMed Central

    Cuthbertson, Leslie; Kos, Veronica; Whitfield, Chris

    2010-01-01

    Summary: Complex glycoconjugates play critical roles in the biology of microorganisms. Despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. One of the primary pathways involves representatives of the ATP-binding cassette (ABC) transporter superfamily. These proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both Gram-positive and Gram-negative bacteria. Recent investigations of the structure and function of ABC transporters involved in the export of lipopolysaccharide O antigens have revealed two fundamentally different strategies for coupling glycan polymerization to export. These mechanisms are distinguished by the presence (or absence) of characteristic nonreducing terminal modifications on the export substrates, which serve as chain termination and/or export signals, and by the presence (or absence) of a discrete substrate-binding domain in the nucleotide-binding domain polypeptide of the ABC transporter. A bioinformatic survey examining ABC exporters from known oligo- and polysaccharide biosynthesis loci identifies conserved nucleotide-binding domain protein families that correlate well with themes in the structures and assembly of glycans. The familial relationships among the ABC exporters generate hypotheses concerning the biosynthesis of structurally diverse oligo- and polysaccharides, which play important roles in the biology of bacteria with different lifestyles. PMID:20805402

  9. The Saturn Ring Observer: In situ studies of planetary rings

    NASA Astrophysics Data System (ADS)

    Nicholson, P. D.; Tiscareno, M. S.; Spilker, L. J.

    2010-12-01

    targets of observation by the SRO will include “propellers” (thought to be the signature of sub-km moonlets embedded in the rings), the “ropy” and “straw” structure seen in images of strong density waves and gap edges, and km-scale radial oscillations which may be signatures of “viscous overstabilities” in high-optical depth regions. Most of the science goals identified above could be accomplished by high-resolution nadir imaging of the rings from a platform that co-orbits with the ring particles, i.e., from a spacecraft in circular orbit a few km above the rings. The vertical displacement of the spacecraft is maintained by a continuous low-thrust ion engine, which can be tilted to provide a slow inward radial drift across the rings. Chemical thrusters permit the craft to `hop' over vertical obstacles in the rings (e.g., bending waves and inclined ringlets). In addition to an imaging system with a resolution of at least 10 cm (with 1 cm a desirable goal), other instrumentat ion might include a laser altimeter/range-finder to measure the effective thickness of the rings, as well as the vertical component of particle motions, aswell as in situ instruments to measure the density and composition of the neutral and ionized ring atmosphere, meteoritic and secondary dust fluxes, and local electric fields (especially in spoke regions).

  10. Asymmetric dipolar ring

    DOEpatents

    Prosandeev, Sergey A.; Ponomareva, Inna V.; Kornev, Igor A.; Bellaiche, Laurent M.

    2010-11-16

    A device having a dipolar ring surrounding an interior region that is disposed asymmetrically on the ring. The dipolar ring generates a toroidal moment switchable between at least two stable states by a homogeneous field applied to the dipolar ring in the plane of the ring. The ring may be made of ferroelectric or magnetic material. In the former case, the homogeneous field is an electric field and in the latter case, the homogeneous field is a magnetic field.

  11. Functional diversification of the RING finger and other binuclear treble clef domains in prokaryotes and the early evolution of the ubiquitin system.

    PubMed

    Burroughs, A Maxwell; Iyer, Lakshminarayan M; Aravind, L

    2011-07-01

    Recent studies point to a diverse assemblage of prokaryotic cognates of the eukaryotic ubiquitin (Ub) system. These systems span an entire spectrum, ranging from those catalyzing cofactor and amino acid biosynthesis, with only adenylating E1-like enzymes and ubiquitin-like proteins (Ubls), to those that are closer to eukaryotic systems by virtue of possessing E2 enzymes. Until recently E3 enzymes were unknown in such prokaryotic systems. Using contextual information from comparative genomics, we uncover a diverse group of RING finger E3s in prokaryotes that are likely to function with E1s, E2s, JAB domain peptidases and Ubls. These E1s, E2s and RING fingers suggest that features hitherto believed to be unique to eukaryotic versions of these proteins emerged progressively in such prokaryotic systems. These include the specific configuration of residues associated with oxyanion-hole formation in E2s and the C-terminal UFD in the E1 enzyme, which presents the E2 to its active site. Our study suggests for the first time that YukD-like Ubls might be conjugated by some of these systems in a manner similar to eukaryotic Ubls. We also show that prokaryotic RING fingers possess considerable functional diversity and that not all of them are involved in Ub-related functions. In eukaryotes, other than RING fingers, a number of distinct binuclear (chelating two Zn atoms) and mononuclear (chelating one zinc atom) treble clef domains are involved in Ub-related functions. Through detailed structural analysis we delineated the higher order relationships and interaction modes of binuclear treble clef domains. This indicated that the FYVE domain acquired the binuclear state independently of the other binuclear forms and that different treble clef domains have convergently acquired Ub-related functions independently of the RING finger. Among these, we uncover evidence for notable prokaryotic radiations of the ZF-UBP, B-box, AN1 and LIM clades of treble clef domains and present

  12. Functional diversification of the RING finger and other binuclear treble clef domains in prokaryotes and the early evolution of the ubiquitin system.

    PubMed

    Burroughs, A Maxwell; Iyer, Lakshminarayan M; Aravind, L

    2011-07-01

    Recent studies point to a diverse assemblage of prokaryotic cognates of the eukaryotic ubiquitin (Ub) system. These systems span an entire spectrum, ranging from those catalyzing cofactor and amino acid biosynthesis, with only adenylating E1-like enzymes and ubiquitin-like proteins (Ubls), to those that are closer to eukaryotic systems by virtue of possessing E2 enzymes. Until recently E3 enzymes were unknown in such prokaryotic systems. Using contextual information from comparative genomics, we uncover a diverse group of RING finger E3s in prokaryotes that are likely to function with E1s, E2s, JAB domain peptidases and Ubls. These E1s, E2s and RING fingers suggest that features hitherto believed to be unique to eukaryotic versions of these proteins emerged progressively in such prokaryotic systems. These include the specific configuration of residues associated with oxyanion-hole formation in E2s and the C-terminal UFD in the E1 enzyme, which presents the E2 to its active site. Our study suggests for the first time that YukD-like Ubls might be conjugated by some of these systems in a manner similar to eukaryotic Ubls. We also show that prokaryotic RING fingers possess considerable functional diversity and that not all of them are involved in Ub-related functions. In eukaryotes, other than RING fingers, a number of distinct binuclear (chelating two Zn atoms) and mononuclear (chelating one zinc atom) treble clef domains are involved in Ub-related functions. Through detailed structural analysis we delineated the higher order relationships and interaction modes of binuclear treble clef domains. This indicated that the FYVE domain acquired the binuclear state independently of the other binuclear forms and that different treble clef domains have convergently acquired Ub-related functions independently of the RING finger. Among these, we uncover evidence for notable prokaryotic radiations of the ZF-UBP, B-box, AN1 and LIM clades of treble clef domains and present

  13. Latitudinal gradients in tree ring stable carbon and oxygen isotopes reveal differential climate influences of the North American Monsoon System

    NASA Astrophysics Data System (ADS)

    Szejner, Paul; Wright, William E.; Babst, Flurin; Belmecheri, Soumaya; Trouet, Valerie; Leavitt, Steven W.; Ehleringer, James R.; Monson, Russell K.

    2016-07-01

    The arrival of the North American Monsoon System (NAMS) terminates a presummer hyperarid period in the southwestern United States (U.S.), providing summer moisture that is favorable for forest growth. Montane forests in this region rely on winter snowpack to drive much of their growth; the extent to which they use NAMS moisture is uncertain. We addressed this by studying stable carbon and oxygen isotopes in earlywood and latewood from 11 sites along a latitudinal gradient extending from Arizona and New Mexico to Utah. This study provides the first regional perspective on the relative roles of winter versus summer precipitation as an ecophysiological resource. Here we present evidence that Ponderosa pine uses NAMS moisture differentially across this gradient. 13C/12C ratios suggest that photosynthetic water use efficiency during latewood formation is more sensitive to summer precipitation at the northern than at the southern sites. This is likely due to the fact that NAMS moisture provides sufficiently favorable conditions for tree photosynthesis and growth during most years in the southern sites, whereas the northern sites experience larger summer moisture variability, which in some years is limiting growth. Cellulose δ18O and δ13C values revealed that photoassimilates in the southern sites were produced under higher vapor pressure deficit conditions during spring compared to summer, demonstrating a previously underappreciated effect of seasonal differences in atmospheric humidity on tree ring isotope ratios. Our findings suggest that future changes in NAMS will potentially alter productivity and photosynthetic water use dynamics differentially along latitudinal gradients in southwestern U.S. montane forests.

  14. Combined Brillouin light scattering and microwave absorption study of magnon-photon coupling in a split-ring resonator/YIG film system

    NASA Astrophysics Data System (ADS)

    Klingler, S.; Maier-Flaig, H.; Gross, R.; Hu, C.-M.; Huebl, H.; Goennenwein, S. T. B.; Weiler, M.

    2016-08-01

    Microfocused Brillouin light scattering (BLS) and microwave absorption (MA) are used to study magnon-photon coupling in a system consisting of a split-ring microwave resonator and an yttrium iron garnet (YIG) film. The split-ring resonator is defined by optical lithography and loaded with a 1 μm-thick YIG film grown by liquid phase epitaxy. BLS and MA spectra of the hybrid system are simultaneously recorded as a function of the applied magnetic field magnitude and microwave excitation frequency. Strong coupling of the magnon and microwave resonator modes is found with a coupling strength of geff /2π = 63 MHz. The combined BLS and MA data allow us to study the continuous transition of the hybridized modes from a purely magnonic to a purely photonic mode by varying the applied magnetic field and microwave frequency. Furthermore, the BLS data represent an up-conversion of the microwave frequency coupling to optical frequencies.

  15. Plant cuticular lipid export requires an ABC transporter.

    PubMed

    Pighin, Jamie A; Zheng, Huanquan; Balakshin, Laura J; Goodman, Ian P; Western, Tamara L; Jetter, Reinhard; Kunst, Ljerka; Samuels, A Lacey

    2004-10-22

    A waxy protective cuticle coats all primary aerial plant tissues. Its synthesis requires extensive export of lipids from epidermal cells to the plant surface. Arabidopsis cer5 mutants had reduced stem cuticular wax loads and accumulated sheetlike inclusions in the cytoplasm of wax-secreting cells. These inclusions represented abnormal deposits of cuticular wax and resembled inclusions found in a human disorder caused by a defective peroxisomal adenosine triphosphate binding cassette (ABC) transporter. We found that the CER5 gene encodes an ABC transporter localized in the plasma membrane of epidermal cells and conclude that it is required for wax export to the cuticle.

  16. SrrAB Modulates Staphylococcus aureus Cell Death through Regulation of cidABC Transcription

    PubMed Central

    Windham, Ian H.; Chaudhari, Sujata S.; Bose, Jeffrey L.; Thomas, Vinai C.

    2016-01-01

    ABSTRACT The death and lysis of a subpopulation in Staphylococcus aureus biofilm cells are thought to benefit the surviving population by releasing extracellular DNA, a critical component of the biofilm extracellular matrix. Although the means by which S. aureus controls cell death and lysis is not understood, studies implicate the role of the cidABC and lrgAB operons in this process. Recently, disruption of the srrAB regulatory locus was found to cause increased cell death during biofilm development, likely as a result of the sensitivity of this mutant to hypoxic growth. In the current study, we extended these findings by demonstrating that cell death in the ΔsrrAB mutant is dependent on expression of the cidABC operon. The effect of cidABC expression resulted in the generation of increased reactive oxygen species (ROS) accumulation and was independent of acetate production. Interestingly, consistently with previous studies, cidC-encoded pyruvate oxidase was found to be important for the generation of acetic acid, which initiates the cell death process. However, these studies also revealed for the first time an important role of the cidB gene in cell death, as disruption of cidB in the ΔsrrAB mutant background decreased ROS generation and cell death in a cidC-independent manner. The cidB mutation also caused decreased sensitivity to hydrogen peroxide, which suggests a complex role for this system in ROS metabolism. Overall, the results of this study provide further insight into the function of the cidABC operon in cell death and reveal its contribution to the oxidative stress response. IMPORTANCE The manuscript focuses on cell death mechanisms in Staphylococcus aureus and provides important new insights into the genes involved in this ill-defined process. By exploring the cause of increased stationary-phase death in an S. aureus ΔsrrAB regulatory mutant, we found that the decreased viability of this mutant was a consequence of the overexpression of the cidABC

  17. Tiling patterns from ABC star molecules: 3-colored foams?

    PubMed

    Kirkensgaard, Jacob J K; Pedersen, Martin C; Hyde, Stephen T

    2014-10-01

    We present coarse-grained simulations of the self-assembly of 3-armed ABC star polyphiles. In systems of star polyphiles with two arms of equal length the simulations corroborate and expand previous findings from related miktoarm star terpolymer systems on the formation of patterns containing columnar domains whose sections are 2D planar tilings. However, the systematic variation of face topologies as the length of the third (unequal) arm is varied differs from earlier findings regarding the compositional dependence. We explore 2D 3-colored foams to establish the optimal patterns based on interfacial energy alone. A generic construction algorithm is described that accounts for all observed 2D tiling patterns and suggests other patterns likely to be found beyond the range of the simulations reported here. Patterns resulting from this algorithm are relaxed using Surface Evolver calculations to form 2D foams with minimal interfacial length as a function of composition. This allows us to estimate the interfacial enthalpic contributions to the free energy of related star molecular assemblies assuming strong segregation. We compare the resulting phase sequence with a number of theoretical results from particle-based simulations and field theory, allowing us to tease out relative enthalpic and entropic contributions as a function of the chain lengths making up the star molecules. Our results indicate that a richer polymorphism is to be expected in systems not dominated by chain entropy. Further, analysis of corresponding planar tiling patterns suggests that related two-periodic columnar structures are unlikely hypothetical phases in 4-arm star polyphile melts in the absence of sufficient arm configurational freedom for minor domains to form lens-shaped di-gons, which require higher molecular weight polymeric arms. Finally, we discuss the possibility of forming a complex tiling pattern that is a quasi-crystalline approximant for 3-arm star polyphiles with unequal arm

  18. Long-distance fiber Bragg grating sensor system with a high optical signal-to-noise ratio based on a tunable fiber ring laser configuration.

    PubMed

    Rao, Yun-Jiang; Ran, Zeng-Ling; Chen, Rong-Rui

    2006-09-15

    A novel tunable fiber ring laser configuration with a combination of bidirectional Raman amplification and dual erbium-doped fiber (EDF) amplification is proposed for realizing high optical signal-to-noise ratio (SNR), long-distance, quasi-distributed fiber Bragg grating (FBG) sensing systems with large capacities and low cost. The hybrid Raman-EDF amplification configuration arranged in the ring laser can enhance the optical SNR of FBG sensor signals significantly owing to the good combination of the high gain of the erbium-doped fiber amplifier (EDFA) and the low noise of the Raman amplification. Such a sensing system can support a large number of FBG sensors because of the use of a tunable fiber Fabry-Perot filter located within the ring laser and spatial division multiplexing for expansion of sensor channels. Experimental results show that an excellent optical SNR of approximately 60 dB has been achieved for a 50 km transmission distance with a low Raman pump power of approximately 170 mW at a wavelength of 1455 nm and a low EDFA pump power of approximately 40 mW at a wavelength of 980 nm, which is the highest optical SNR achieved so far for a 50 km long FBG sensor system, to our knowledge. PMID:16936857

  19. Migration of Adipose-derived Mesenchymal Stem Cells Stably Expressing Chondroitinase ABC In vitro

    PubMed Central

    Wu, Jian-Huang; Li, Miao; Liang, Yan; Lu, Tao; Duan, Chun-Yue

    2016-01-01

    Background: Several studies have revealed that adipose-derived mesenchymal stem cells (ADSCs) can be used as seed cells for the treatment of spinal cord injury (SCI). Chondroitinase ABC (ChABC) decomposes chondroitin sulfate proteoglycans in the glial scar that forms following SCI, allowing stem cells to penetrate through the scar and promote recovery of nerve function. This study aimed to establish ADSCs that stably express ChABC (ChABC-ADSCs) and evaluate the migratory capability of ChABC-ADSCs in vitro. Methods: ADSCs were obtained from Sprague-Dawley rats using secondary collagenase digestion. Their phenotypes were characterized using flow cytometry detection of cell surface antigens and their stem cell properties were confirmed by induction of differentiation. After successful culture, ADSCs were transfected with lentiviral vectors and ChABC-ADSCs were obtained. Proliferation curves of ChABC-ADSCs were determined using the Cell Counting Kit-8 method, ChABC expression was verified using Western blotting, and the migration of ChABC-ADSCs was analyzed using the transwell assay. Results: Secondary collagenase digestion increased the isolation efficiency of primary ADSCs. Following transfection using lentiviral vectors, the proliferation of ChABC-ADSCs was reduced in comparison with control ADSCs at 48 h (P < 0.05). And the level of ChABC expression in the ChABC-ADSC group was significantly higher than that of the ADSC group (P < 0.05). Moreover, ChABC-ADSC migration in matrigel was significantly enhanced in comparison with the control (P < 0.05). Conclusions: Secondary collagenase digestion can be used to effectively isolate ADSCs. ChABC-ADSCs constructed using lentiviral vector transfection stably express ChABC, and ChABC expression significantly enhances the migratory capacity of ADSCs. PMID:27364797

  20. Thermal emission from Saturn's rings at 380 microns

    SciTech Connect

    Roellig, T.L.; Werner, M.W.; Becklin, E.E.

    1988-03-01

    Two different techniques have been used to derive the Saturn disk's ring brightness temperatures from 380-micron observations: (1) comparisons of these wide-beam observation disk-ring system results with those obtained for an earlier epoch, when the rings were edge-on, then differencing the two measurements to obtain a value for the rings' contribution; and (2) ring contribution resolution during scanning along the disk-ring plane, to yield a B-ring brightness temperature of 39 + or - 8 K at 380 microns. The results obtained indicate a gradual decrease of observed ring brightness temperature from the IR to the radio wavelength range. 24 references.

  1. Asymmetric Hydrogenation of Azaindoles: Chemo- and Enantioselective Reduction of Fused Aromatic Ring Systems Consisting of Two Heteroarenes.

    PubMed

    Makida, Yusuke; Saita, Masahiro; Kuramoto, Takahiro; Ishizuka, Kentaro; Kuwano, Ryoichi

    2016-09-19

    High enantioselectivity was achieved for the hydrogenation of azaindoles by using the chiral catalyst, which was prepared from [Ru(η(3) -methallyl)2 (cod)] and a trans-chelating bis(phosphine) ligand (PhTRAP). The dearomative reaction exclusively occurred on the five-membered ring, thus giving the corresponding azaindolines with up to 97:3 enantiomer ratio. PMID:27561154

  2. Regulation of Expression of abcA and Its Response to Environmental Conditions

    PubMed Central

    Villet, Regis A.; Truong-Bolduc, Que Chi; Wang, Yin; Estabrooks, Zoe; Medeiros, Heidi

    2014-01-01

    The ATP-dependent transporter gene abcA in Staphylococcus aureus confers resistance to hydrophobic β-lactams. In strain ISP794, abcA is regulated by the transcriptional regulators MgrA and NorG and shares a 420-nucleotide intercistronic region with the divergently transcribed pbp4 gene, which encodes the transpeptidase Pbp4. Exposure of exponentially growing cells to iron-limited media, oxidative stress, and acidic pH (5.5) for 0.5 to 2 h had no effect on abcA expression. In contrast, nutrient limitation produced a significant increase in abcA transcripts. We identified three additional regulators (SarA, SarZ, and Rot) that bind to the overlapping promoter region of abcA and pbp4 in strain MW2 and investigated their role in the regulation of abcA expression. Expression of abcA is decreased by 10.0-fold in vivo in a subcutaneous abscess model. In vitro, abcA expression depends on rot and sarZ regulators. Moenomycin A exposure of strain MW2 produced an increase in abcA transcripts. Relative to MW2, the MIC of moenomycin was decreased 8-fold for MW2ΔabcA and increased 10-fold for the MW2 abcA overexpresser, suggesting that moenomycin is a substrate of AbcA. PMID:24509312

  3. Which Ringed Planet...!?

    NASA Astrophysics Data System (ADS)

    2002-12-01

    Don't worry - you are not the only one who thought this was a nice amateur photo of planet Saturn, Lord of the Rings in our Solar System! But then the relative brightness and positions of the moons may appear somewhat unfamiliar... and the ring system does look unusually bright when compared to the planetary disk...?? Well, it is not Saturn, but Uranus , the next giant planet further out, located at a distance of about 3,000 million km, or 20 times the distance between the Sun and the Earth. The photo shows Uranus surrounded by its rings and some of the moons, as they appear on a near-infrared image that was obtained in the K s -band (at wavelength 2.2 µm) with the ISAAC multi-mode instrument on the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory (Chile) . The exposure was made on November 19, 2002 (03:00 hrs UT) during a planetary research programme. The observing conditions were excellent (seeing 0.5 arcsec) and the exposure lasted 5 min. The angular diameter of Uranus is about 3.5 arcsec. The observers at ISAAC were Emmanuel Lellouch and Thérése Encrenaz of the Observatoire de Paris (France) and Jean-Gabriel Cuby and Andreas Jaunsen (both ESO-Chile). The rings The rings of Uranus were discovered in 1977, from observations during a stellar occultation event by astronomer teams at the Kuiper Airborne Observatory (KAO) and the Perth Observatory (Australia). Just before and after the planet moved in front of the (occulted) star, the surrounding rings caused the starlight to dim for short intervals of time. Photos obtained from the Voyager-2 spacecraft in 1986 showed a multitude of very tenuous rings. These rings are almost undetectable from the Earth in visible light. However, on the present VLT near-infrared picture, the contrast between the rings and the planet is strongly enhanced. At the particular wavelength at which this observation was made, the infalling sunlight is almost completely absorbed by gaseous methane present in the planetary atmosphere

  4. Stirling engine piston ring

    DOEpatents

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  5. Combination treatment with anti-Nogo-A and chondroitinase ABC is more effective than single treatments at enhancing functional recovery after spinal cord injury.

    PubMed

    Zhao, Rong-Rong; Andrews, Melissa R; Wang, Difei; Warren, Philippa; Gullo, Miriam; Schnell, Lisa; Schwab, Martin E; Fawcett, James W

    2013-09-01

    Anti-Nogo-A antibody and chondroitinase ABC (ChABC) enzyme are two promising treatments that promote functional recovery after spinal cord injury (SCI). Treatment with them has encouraged axon regeneration, sprouting and functional recovery in a variety of spinal cord and central nervous system injury models. The two compounds work, in part, through different mechanisms, so it is possible that their effects will be additive. In this study, we used a rat cervical partial SCI model to explore the effectiveness of a combination of anti-Nogo-A, ChABC, and rehabilitation. We found that spontaneous recovery of forelimb functions reflects the extent of the lesion on the ipsilateral side. We applied a combination treatment with acutely applied anti-Nogo-A antibody followed by delayed ChABC treatment starting at 3 weeks after injury, and rehabilitation starting at 4 weeks, to accommodate the requirement that anti-Nogo-A be applied acutely, and that rehabilitation be given after the cessation of anti-Nogo-A treatment. We found that single treatment with either anti-Nogo-A or ChABC, combined with rehabilitation, produced functional recovery of similar magnitude. The combination treatment, however, was more effective. Both single treatments produced increases in sprouting and axon regeneration, but the combination treatment produced greater increases. Anti-Nogo-A stimulated growth of a greater number of axons with a diameter of > 3 μm, whereas ChABC treatment stimulated increased growth of finer axons with varicosities. These results point to different functions of Nogo-A and chondroitin sulfate proteoglycans in axonal regeneration. The combination of anti-Nogo-A, ChABC and rehabilitation shows promise for enhancing functional recovery after SCI.

  6. Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

    PubMed

    Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

    2016-06-01

    We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency. PMID:27155868

  7. Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study.

    PubMed

    Biswas, Abul Kalam; Barik, Sunirmal; Das, Amitava; Ganguly, Bishwajit

    2016-06-01

    We have reported a number of new metal-free organic dyes (2-6) that have cyclic asymmetric benzotripyrrole derivatives as donor groups with peripheral nitrogen atoms in the ring, fluorine and thiophene groups as π-spacers, and a cyanoacrylic acid acceptor group. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations were employed to examine the influence of the position of the donor nitrogen atom and π-conjugation on solar cell performance. The calculated electron-injection driving force (ΔG inject), electron-regeneration driving force (ΔG regen), light-harvesting efficiency (LHE), dipole moment (μ normal), and number of electrons transferred (∆q) indicate that dyes 3, 4, and 6 have significantly higher efficiencies than reference dye 1, which exhibits high efficiency. We also extended our comparison to some other reported dyes, 7-9, which have a donor nitrogen atom in the middle of the ring system. The computed results suggest that dye 6 possesses a higher incident photon to current conversion efficiency (IPCE) than reported dyes 7-9. Thus, the use of donor groups with peripheral nitrogen atoms appears to lead to more efficient dyes than those in which the nitrogen atom is present in the middle of the donor ring system. Graphical Abstract The locations of the nitrogen atoms in the donor groups in the designed dye molecules have an important influence on DSSC efficiency.

  8. Development of high-speed reactive processing system for carbon fiber-reinforced polyamide-6 composite: In-situ anionic ring-opening polymerization

    NASA Astrophysics Data System (ADS)

    Kim, Sang-Woo; Seong, Dong Gi; Yi, Jin-Woo; Um, Moon-Kwang

    2016-05-01

    In order to manufacture carbon fiber-reinforced polyamide-6 (PA-6) composite, we optimized the reactive processing system. The in-situ anionic ring-opening polymerization of ɛ-caprolactam was utilized with proper catalyst and initiator for PA-6 matrix. The mechanical properties such as tensile strength, inter-laminar shear strength and compressive strength of the produced carbon fiber-reinforced PA-6 composite were measured, which were compared with the corresponding scanning electron microscope (SEM) images to investigate the polymer properties as well as the interfacial interaction between fiber and polymer matrix. Furthermore, kinetics of in-situ anionic ring-opening polymerization of ɛ-caprolactam will be discussed in the viewpoint of increasing manufacturing speed and interfacial bonding between PA-6 matrix and carbon fiber during polymerization.

  9. Dissociations among ABA, ABC, and AAB Recovery Effects

    ERIC Educational Resources Information Center

    Ungor, Metin; Lachnit, Harald

    2008-01-01

    In a human predictive learning experiment, the strengths of ABA, ABC, and AAB recovery effects after discrimination reversal learning were compared. Initially, a discrimination between two stimuli (X+, Y-) was trained in Context A. During Phase 2, participants received discrimination reversal training (X-, Y+) either in Context A (Group AAB) or in…

  10. Electronic excitation spectrum of ABC-stacked multilayer graphene

    NASA Astrophysics Data System (ADS)

    Henni, Y.; Nogajewski, K.; Ojeda Collado, H. P.; Usaj, G.; Balseiro, C. A.; Potemski, M.; Faugeras, C.

    The electronic properties of ABC graphene trilayers has attracted lot of attention recently due to their potential applications in engineering carbon-based devices with gate tunable electrical conductivity. Morever,ABC-stacked thin layers of graphite are predicted to host peculiar surface electronic states, with a flat dispersion over most of the Brillouin zone. The associated high density of states is likely to favour the emergence of exotic electronic phases, such as charge density waves or even superconductivity. We present a micro-magneto-Raman scattering study of a thin graphite flake produced by exfoliation of natural graphite, composed of ~15graphene layers, and including a large ABC-stacked domain. Exploring the low temperature Raman scattering spectrum of this domain up to B=29T,we identify inter Landau level electronic excitations within the surface flat bands,together with electronic excitations involving the gapped states in the bulk. This interband electronic excitation at B=0T can be observed,up to room temperature, directly in the Raman scattering spectrum as a broad(~ 180 cm-1) feature. Because the energy gap strongly depends on the number of layers,this electronic excitation can be used to identify and characterize ABC-stacked graphite thin layers.

  11. Selections from the ABC 2009 Annual Convention, Portsmouth, Virginia

    ERIC Educational Resources Information Center

    Whalen, D. Joel

    2010-01-01

    The "My Favorite Assignment" Session at the 2009 Association for Business Communication (ABC) annual convention in Portsmouth, Virginia, featured over a dozen teachers sharing pedagogical innovations in a fast-paced, 4-minute format designed by Dan Dietrich. The wide variety of ideas and techniques presented makes these sessions popular ABC…

  12. The ABCs for Pre-Service Teacher Cultural Competency Development

    ERIC Educational Resources Information Center

    He, Ye; Cooper, Jewell E.

    2009-01-01

    In an effort to combine pre-service teachers' self-reflection with their field experiences to enhance their cultural competency, this study adopted Schmidt's ABC's (Autobiography, Biography, and Cross-cultural Comparison) Model in two courses in a pre-service teacher education program. Through group comparisons, this study measured the impact that…

  13. The Library ABC's Game: Sneaking in Learning through Gaming

    ERIC Educational Resources Information Center

    Maxwell, D. Jackson

    2007-01-01

    Teaching library terminology and definitions can be a real bore. Unfortunately, no matter how one looks at it, students need to learn a set of basic library words and their meanings. The Library ABC's game teaches elementary age students library terms and definitions, and it is effective, efficient, easy, exciting, and fun. Introduce the Library…

  14. The K-ABC in Historical and Contemporary Perspective.

    ERIC Educational Resources Information Center

    Anastasi, Anne

    1984-01-01

    The Kaufman Assessment Battery for Children is examined with particular attention to evolution of current psychometric concepts and methods, as well as the historical sources of popular misconceptions. The K-ABC reveals sophisticated applications of current test construction methodology but requires knowledgeable examiners. (Author/CL)

  15. Selections from the ABC 2012 Annual Convention, Honolulu, Hawaii

    ERIC Educational Resources Information Center

    Whalen, D. Joel

    2013-01-01

    The 13 Favorite Assignments featured here were presented at the 2012 Association for Business Communication (ABC) Annual Convention, Honolulu, Hawaii. A variety of learning objectives are featured, including the following: enhancing resume's visual impact, interpersonal skills, social media, team building, web design, community service…

  16. Selections from the ABC 2011 Annual Convention, Montreal, Canada

    ERIC Educational Resources Information Center

    Whalen, D. Joel; Andersen, Ken; Campbell, Gloria; Crenshaw, Cheri; Cross, Geoffrey A.; Grinols, Anne Bradstreet; Hildebrand, John; Newman, Amy; Ortiz, Lorelei A.; Paulson, Edward; Phillabaum, Melinda; Powell, Elizabeth A.; Sloan, Ryan

    2012-01-01

    The 12 Favorite Assignments featured in this article were presented at the 2011 Annual Convention of the Association for Business Communication (ABC), Montreal, Canada. A variety of learning objectives are featured: delivering bad news, handling difficult people, persuasion, reporting financial analysis, electronic media, face-to-face…

  17. Beyond the ABCs: The Pleasures of the Alphabet Book.

    ERIC Educational Resources Information Center

    Thatcher, Debra H.

    2002-01-01

    Identifies seven types of alphabet books: letter shapes, word play, art play, topical/thematic, multicultural, narrative, and puzzles. Presents annotations of around 30 titles. Suggests that alphabet books are not intended just for the emergent reader--there is a wide range of ABC books with intriguing stories, captivating illustrations, playful…

  18. ABCs of Being Smart... G Is for Gifted!

    ERIC Educational Resources Information Center

    Foster, Joanne

    2012-01-01

    Giftedness can generate speculation, misconceptions, expectations, pride, innuendo, apprehension, puzzlement--and the list goes on. What does it mean to be a gifted learner? In this installment of the series "ABCs of Being Smart," the author grapples with the term gifted, giving a glimpse into giftedness, along with some general guidelines for…

  19. Actin Rings of Power.

    PubMed

    Schwayer, Cornelia; Sikora, Mateusz; Slováková, Jana; Kardos, Roland; Heisenberg, Carl-Philipp

    2016-06-20

    Circular or ring-like actin structures play important roles in various developmental and physiological processes. Commonly, these rings are composed of actin filaments and myosin motors (actomyosin) that, upon activation, trigger ring constriction. Actomyosin ring constriction, in turn, has been implicated in key cellular processes ranging from cytokinesis to wound closure. Non-constricting actin ring-like structures also form at cell-cell contacts, where they exert a stabilizing function. Here, we review recent studies on the formation and function of actin ring-like structures in various morphogenetic processes, shedding light on how those different rings have been adapted to fulfill their specific roles. PMID:27326928

  20. The rings of Saturn

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1978-01-01

    Consideration is given to the development of theories concerning the rings of Saturn. Particular attention is given to ring structure, noting its thinness, the separations between rings, and observed variations in brightness. Data gathered via infrared, radio and radar techniques are described in terms of ring particle composition and size. Hypotheses about ring origin and evolution are outlined, including the tidal disruption model, calculations of Saturn's gravitational contraction history, grazing, and meteoroid bombardment. Prospects for future observations of Saturn's rings are reviewed, such as the variation in their radar reflectivity as a function of the tilt of the ring plane.

  1. New Dust Belts of Uranus: One Ring, Two Ring, Red Ring, Blue Ring

    SciTech Connect

    de Pater, I; Hammel, H B; Gibbard, S G; Showalter, M R

    2006-02-02

    We compare near-infrared observations of the recently discovered outer rings of Uranus with HST results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced via impacts into the embedded moon Mab, which apparently orbits at a location where non-gravitational perturbations favor the survival and spreading of sub-micron sized dust. R/2003 U 2 more closely resembles Saturn's G ring.

  2. Placental ABC transporters, cellular toxicity and stress in pregnancy.

    PubMed

    Aye, Irving L M H; Keelan, Jeffrey A

    2013-04-25

    The human placenta, in addition to its roles as a nutrient transfer and endocrine organ, functions as a selective barrier to protect the fetus against the harmful effects of exogenous and endogenous toxins. Members of the ATP-binding cassette (ABC) family of transport proteins limit the entry of xenobiotics into the fetal circulation via vectorial efflux from the placenta to the maternal circulation. Several members of the ABC family, including proteins from the ABCA, ABCB, ABCC and ABCG subfamilies, have been shown to be functional in the placenta with clinically significant roles in xenobiotic efflux. However, recent findings suggest that these transporters also protect placental tissue by preventing the cellular accumulation of cytotoxic compounds such as lipids, sterols and their derivatives. Such protective functions are likely to be particularly important in pregnancies complicated by inflammatory or oxidative stress, where the generation of toxic metabolites is enhanced. For example, ABC transporters have been shown to protect against the harmful effects of hypoxia and oxidative stress through increased expression and efflux of oxysterols and glutathione conjugated xenobiotics. However, this protective capacity may be diminished in response to the same stressors. Several studies in primary human trophoblast cells and animal models have demonstrated decreased expression and activity of placental ABC transporters with inflammatory, oxidative or metabolic stress. Several clinical studies in pregnancies complicated by inflammatory conditions such as preeclampsia and gestational diabetes support these findings, although further studies are required to determine the clinical relevance of the relationships between placental ABC transporter expression and activity, and placental function in stressed pregnancies. Such studies are necessary to fully understand the consequences of pregnancy disorders on placental function and viability in order to optimise pregnancy

  3. Efficient Diethylzinc/Gallic Acid and Diethylzinc/Gallic Acid Ester Catalytic Systems for the Ring-Opening Polymerization of rac-Lactide.

    PubMed

    Żółtowska, Karolina; Piotrowska, Urszula; Oledzka, Ewa; Sobczak, Marcin

    2015-12-08

    Polylactide (PLA) represents one of the most promising biomedical polymers due to its biodegradability, bioresorbability and good biocompatibility. This work highlights the synthesis and characterization of PLAs using novel diethylzinc/gallic acid (ZnEt₂/GAc) and diethylzinc/propyl gallate (ZnEt₂/PGAc) catalytic systems that are safe for human body. The results of the ring-opening polymerization (ROP) of rac-lactide (rac-LA) in the presence of zinc-based catalytic systems have shown that, depending on the reaction conditions, "predominantly isotactic", disyndiotactic or atactic PLA can be obtained. Therefore, the controlled and stereoselective ROP of rac-LA is discussed in detail in this paper.

  4. Euphorikanin A, a Diterpenoid Lactone with a Fused 5/6/7/3 Ring System from Euphorbia kansui.

    PubMed

    Fei, Dong-Qing; Dong, Le-Le; Qi, Feng-Ming; Fan, Gai-Xia; Li, Hui-Hong; Li, Zheng-Yu; Zhang, Zhan-Xin

    2016-06-17

    Euphorikanin A (1), an unprecedented diterpenoid lactone which possesses a novel 5/6/7/3-fused tetracyclic ring skeleton, was isolated from the roots of Euphorbia kansui. The chemical structure and absolute stereochemistry were elucidated on the basis of extensive spectroscopic methods and single-crystal X-ray diffraction analysis. Compound 1 exhibited moderate cytotoxicity against two human tumor cell lines HeLa and NCI-446. A proposed biosynthetic pathway of compound 1 is also described. PMID:27230557

  5. GintABC1 encodes a putative ABC transporter of the MRP subfamily induced by Cu, Cd, and oxidative stress in Glomus intraradices.

    PubMed

    González-Guerrero, Manuel; Benabdellah, Karim; Valderas, Ascensión; Azcón-Aguilar, Concepción; Ferrol, Nuria

    2010-02-01

    A full-length cDNA sequence putatively encoding an ATP-binding cassette (ABC) transporter (GintABC1) was isolated from the extraradical mycelia of the arbuscular mycorrhizal fungus Glomus intraradices. Bioinformatic analysis of the sequence indicated that GintABC1 encodes a 1513 amino acid polypeptide, containing two six-transmembrane clusters (TMD) intercalated with sequences characteristics of the nucleotide binding domains (NBD) and an extra N-terminus extension (TMD0). GintABC1 presents a predicted TMD0-(TMD-NBD)(2) topology, typical of the multidrug resistance-associated protein subfamily of ABC transporters. Gene expression analyses revealed no difference in the expression levels of GintABC1 in the extra- vs the intraradical mycelia. GintABC1 was up-regulated by Cd and Cu, but not by Zn, suggesting that this transporter might be involved in Cu and Cd detoxification. Paraquat, an oxidative agent, also induced the transcription of GintABC1. These data suggest that redox changes may be involved in the transcriptional regulation of GintABC1 by Cd and Cu.

  6. The modular structure of the inner-membrane ring component PrgK facilitates assembly of the type III secretion system basal body.

    PubMed

    Bergeron, Julien R C; Worrall, Liam J; De, Soumya; Sgourakis, Nikolaos G; Cheung, Adrienne H; Lameignere, Emilie; Okon, Mark; Wasney, Gregory A; Baker, David; McIntosh, Lawrence P; Strynadka, Natalie C J

    2015-01-01

    The type III secretion system (T3SS) is a large macromolecular assembly found at the surface of many pathogenic Gram-negative bacteria. Its role is to inject toxic "effector" proteins into the cells of infected organisms. The molecular details of the assembly of this large, multimembrane-spanning complex remain poorly understood. Here, we report structural, biochemical, and functional analyses of PrgK, an inner-membrane component of the prototypical Salmonella typhimurium T3SS. We have obtained the atomic structures of the two ring building globular domains and show that the C-terminal transmembrane helix is not essential for assembly and secretion. We also demonstrate that structural rearrangement of the two PrgK globular domains, driven by an interconnecting linker region, may promote oligomerization into ring structures. Finally, we used electron microscopy-guided symmetry modeling to propose a structural model for the intimately associated PrgH-PrgK ring interaction within the assembled basal body. PMID:25533490

  7. Self-Assembly of MinE on the Membrane Underlies Formation of the MinE Ring to Sustain Function of the Escherichia coli Min System*

    PubMed Central

    Zheng, Min; Chiang, Ya-Ling; Lee, Hsiao-Lin; Kong, Lih-Ren; Hsu, Shang-Te Danny; Hwang, Ing-Shouh; Rothfield, Lawrence I.; Shih, Yu-Ling

    2014-01-01

    The pole-to-pole oscillation of the Min proteins in Escherichia coli results in the inhibition of aberrant polar division, thus facilitating placement of the division septum at the midcell. MinE of the Min system forms a ring-like structure that plays a critical role in triggering the oscillation cycle. However, the mechanism underlying the formation of the MinE ring remains unclear. This study demonstrates that MinE self-assembles into fibrillar structures on the supported lipid bilayer. The MinD-interacting domain of MinE shows amyloidogenic properties, providing a possible mechanism for self-assembly of MinE. Supporting the idea, mutations in residues Ile-24 and Ile-25 of the MinD-interacting domain affect fibril formation, membrane binding ability of MinE and MinD, and subcellular localization of three Min proteins. Additional mutations in residues Ile-72 and Ile-74 suggest a role of the C-terminal domain of MinE in regulating the folding propensity of the MinD-interacting domain for different molecular interactions. The study suggests a self-assembly mechanism that may underlie the ring-like structure formed by MinE-GFP observed in vivo. PMID:24914211

  8. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  9. Introduction of argon beam coagulation functionality to robotic procedures using the ABC D-Flex probe: equivalency to an existing laparoscopic instrument

    NASA Astrophysics Data System (ADS)

    Merchel, Renée. A.; Barnes, Kelli S.; Taylor, Kenneth D.

    2015-03-01

    INTRODUCTION: The ABC® D-Flex Probe utilizes argon beam coagulation (ABC) technology to achieve hemostasis during minimally invasive surgery. A handle on the probe allows for integration with robotic surgical systems and introduces ABC to the robotic toolbox. To better understand the utility of D-Flex, this study compares the performance of the D-Flex probe to an existing ABC laparoscopic probe through ex vivo tissue analysis. METHODS: Comparisons were performed to determine the effect of four parameters: ABC device, tissue type, activation duration, and distance from tissue. Ten ABC D-Flex probes were used to create 30 burn samples for each comparison. Ex vivo bovine liver and porcine muscle were used as tissue models. The area and depth of each burn was measured using a light microscope. The resulting dimensional data was used to correlate tissue effect with each variable. RESULTS: D-Flex created burns which were smaller in surface area than the laparoscopic probe at all power levels. Additionally, D-Flex achieved thermal penetration levels equivalent to the laparoscopic probe. CONCLUSION: D-Flex implements a small 7F geometry which creates a more focused beam. When used with robotic precision, quick localized superficial hemostasis can be achieved with minimal collateral damage. Additionally, D-Flex achieved equivalent thermal penetration levels at lower power and argon flow-rate settings than the laparoscopic probe.

  10. Optimizing Thomson's jumping ring

    NASA Astrophysics Data System (ADS)

    Tjossem, Paul J. H.; Brost, Elizabeth C.

    2011-04-01

    The height to which rings will jump in a Thomson jumping ring apparatus is the central question posed by this popular lecture demonstration. We develop a simple time-averaged inductive-phase-lag model for the dependence of the jump height on the ring material, its mass, and temperature and apply it to measurements of the jump height for a set of rings made by slicing copper and aluminum alloy pipe into varying lengths. The data confirm a peak jump height that grows, narrows, and shifts to smaller optimal mass when the rings are cooled to 77 K. The model explains the ratio of the cooled/warm jump heights for a given ring, the reduction in optimal mass as the ring is cooled, and the shape of the mass resonance. The ring that jumps the highest is found to have a characteristic resistance equal to the inductive reactance of the set of rings.

  11. 75 FR 49549 - ABC & D Recycling, Inc.-Lease and Operation Exemption-a Line of Railroad in Ware, MA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-13

    ... Surface Transportation Board ABC & D Recycling, Inc.--Lease and Operation Exemption--a Line of Railroad in Ware, MA ABC & D Recycling, Inc. (ABC & D), a noncarrier, has filed a verified notice of exemption... operation of this trackage in FD 35356, ABC & D Recycling, Inc.--Lease and Operation Exemption--a Line...

  12. A burst of ABC genes in the genome of the polyphagous spider mite Tetranychus urticae

    PubMed Central

    2013-01-01

    Background The ABC (ATP-binding cassette) gene superfamily is widespread across all living species. The majority of ABC genes encode ABC transporters, which are membrane-spanning proteins capable of transferring substrates across biological membranes by hydrolyzing ATP. Although ABC transporters have often been associated with resistance to drugs and toxic compounds, within the Arthropoda ABC gene families have only been characterized in detail in several insects and a crustacean. In this study, we report a genome-wide survey and expression analysis of the ABC gene superfamily in the spider mite, Tetranychus urticae, a chelicerate ~ 450 million years diverged from other Arthropod lineages. T. urticae is a major agricultural pest, and is among of the most polyphagous arthropod herbivores known. The species resists a staggering array of toxic plant secondary metabolites, and has developed resistance to all major classes of pesticides in use for its control. Results We identified 103 ABC genes in the T. urticae genome, the highest number discovered in a metazoan species to date. Within the T. urticae ABC gene set, all members of the eight currently described subfamilies (A to H) were detected. A phylogenetic analysis revealed that the high number of ABC genes in T. urticae is due primarily to lineage-specific expansions of ABC genes within the ABCC, ABCG and ABCH subfamilies. In particular, the ABCC subfamily harbors the highest number of T. urticae ABC genes (39). In a comparative genomic analysis, we found clear orthologous relationships between a subset of T. urticae ABC proteins and ABC proteins in both vertebrates and invertebrates known to be involved in fundamental cellular processes. These included members of the ABCB-half transporters, and the ABCD, ABCE and ABCF families. Furthermore, one-to-one orthologues could be distinguished between T. urticae proteins and human ABCC10, ABCG5 and ABCG8, the Drosophila melanogaster sulfonylurea receptor and ecdysone

  13. The "Good, Bad and Ugly" pin site grading system: A reliable and memorable method for documenting and monitoring ring fixator pin sites.

    PubMed

    Clint, S A; Eastwood, D M; Chasseaud, M; Calder, P R; Marsh, D R

    2010-02-01

    Although there is much in the literature regarding pin site infections, there is no accepted, validated method for documenting their state. We present a system for reliably labelling pin sites on any ring fixator construct and an easy-to-remember grading system to document the state of each pin site. Each site is graded in terms of erythema, pain and discharge to give a 3-point scale, named "Good", "Bad" and "Ugly" for ease of recall. This system was tested for intra- and inter-observer reproducibility. 15 patients undergoing elective limb reconstruction were recruited. A total of 218 pin sites were independently scored by 2 examiners. 82 were then re-examined later by the same examiners. 514 pin sites were felt to be "Good", 80 "Bad" and 6 "Ugly". The reproducibility of the system was found to be excellent. We feel our system gives a quick, reliable and reproducible method to monitor individual pin sites and their response to treatment.

  14. Modification of N-glycosylation sites allows secretion of bacterial chondroitinase ABC from mammalian cells.

    PubMed

    Muir, Elizabeth M; Fyfe, Ian; Gardiner, Sonya; Li, Li; Warren, Philippa; Fawcett, James W; Keynes, Roger J; Rogers, John H

    2010-01-15

    Although many eukaryotic proteins have been secreted by transfected bacterial cells, little is known about how a bacterial protein is treated as it passes through the secretory pathway when expressed in a eukaryotic cell. The eukaryotic N-glycosylation system could interfere with folding and secretion of prokaryotic proteins whose sequence has not been adapted for glycosylation in structurally appropriate locations. Here we show that such interference does indeed occur for chondroitinase ABC from the bacterium Proteus vulgaris, and can be overcome by eliminating potential N-glycosylation sites. Chondroitinase ABC was heavily glycosylated when expressed in mammalian cells or in a mammalian translation system, and this process prevented secretion of functional enzyme. Directed mutagenesis of selected N-glycosylation sites allowed efficient secretion of active chondroitinase. As these proteoglycans are known to inhibit regeneration of axons in the mammalian central nervous system, the modified chondroitinase gene is a potential tool for gene therapy to promote neural regeneration, ultimately in human spinal cord injury.

  15. Modification of N-glycosylation sites allows secretion of bacterial chondroitinase ABC from mammalian cells

    PubMed Central

    Muir, Elizabeth M.; Fyfe, Ian; Gardiner, Sonya; Li, Li; Warren, Philippa; Fawcett, James W.; Keynes, Roger J.; Rogers, John H.

    2010-01-01

    Although many eukaryotic proteins have been secreted by transfected bacterial cells, little is known about how a bacterial protein is treated as it passes through the secretory pathway when expressed in a eukaryotic cell. The eukaryotic N-glycosylation system could interfere with folding and secretion of prokaryotic proteins whose sequence has not been adapted for glycosylation in structurally appropriate locations. Here we show that such interference does indeed occur for chondroitinase ABC from the bacterium Proteus vulgaris, and can be overcome by eliminating potential N-glycosylation sites. Chondroitinase ABC was heavily glycosylated when expressed in mammalian cells or in a mammalian translation system, and this process prevented secretion of functional enzyme. Directed mutagenesis of selected N-glycosylation sites allowed efficient secretion of active chondroitinase. As these proteoglycans are known to inhibit regeneration of axons in the mammalian central nervous system, the modified chondroitinase gene is a potential tool for gene therapy to promote neural regeneration, ultimately in human spinal cord injury. PMID:19900493

  16. Active transmembrane drug transport in microgravity: a validation study using an ABC transporter model

    PubMed Central

    Vaquer, Sergi; Cuyàs, Elisabet; Rabadán, Arnau; González, Albert; Fenollosa, Felip; de la Torre, Rafael

    2014-01-01

    Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay ® (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and

  17. Cost Analysis of Selected Patient Categories within a Dermatology Department Using an ABC Approach

    PubMed Central

    Papadaki, Šárka; Popesko, Boris

    2016-01-01

    Background: Present trends in hospital management are facilitating the utilization of more accurate costing methods, which potentially results in superior cost-related information and improved managerial decision-making. However, the Activity-Based Costing method (ABC), which was designed for cost allocation purposes in the 1980s, is not widely used by healthcare organizations. This study analyzes costs related to selected categories of patients, those suffering from psoriasis, varicose ulcers, eczema and other conditions, within a dermatology department at a Czech regional hospital. Methods: The study was conducted in a hospital department where both inpatient and outpatient care are offered. Firstly, the diseases treated at the department were identified. Further costs were determined for each activity using ABC. The study utilized data from managerial and financial accounting, as well as data obtained through interviews with departmental staff. Using a defined cost-allocation procedure makes it possible to determine the cost of an individual patient with a given disease more accurately than via traditional costing procedures. Results: The cost analysis focused on the differences between the costs related to individual patients within the selected diagnoses, variations between inpatient and outpatient treatments and the costs of activities performed by the dermatology department. Furthermore, comparing the costs identified through this approach and the revenue stemming from the health insurance system is an option. Conclusions: Activity-Based Costing is more accurate and relevant than the traditional costing method. The outputs of ABC provide an abundance of additional information for managers. The benefits of this research lie in its practically-tested outputs, resulting from calculating the costs of hospitalization, which could prove invaluable to persons involved in hospital management and decision-making. The study also defines the managerial implications of

  18. Nucleotide-induced conformational dynamics in ABC transporters from structure-based coarse grained modelling.

    NASA Astrophysics Data System (ADS)

    Flechsig, Holger

    2016-02-01

    ATP-binding cassette (ABC) transporters are integral membrane proteins which mediate the exchange of diverse substrates across membranes powered by ATP molecules. Our understanding of their activity is still hampered since the conformational dynamics underlying the operation of such proteins cannot yet be resolved in detailed molecular dynamics studies. Here a coarse grained model which allows to mimic binding of nucleotides and follow subsequent conformational motions of full-length transporter structures in computer simulations is proposed and implemented. To justify its explanatory quality, the model is first applied to the maltose transporter system for which multiple conformations are known and we find that the model predictions agree remarkably well with the experimental data. For the MalK subunit the switching from open to the closed dimer configuration upon ATP binding is reproduced and, moreover, for the full-length maltose transporter, progression from inward-facing to the outward-facing state is correctly obtained. For the heme transporter HmuUV, for which only the free structure could yet be determined, the model was then applied to predict nucleotide-induced conformational motions. Upon binding of ATP-mimicking ligands the structure changed from a conformation in which the nucleotide-binding domains formed an open shape, to a conformation in which they were found in tight contact, while, at the same time, a pronounced rotation of the transmembrane domains was observed. This finding is supported by normal mode analysis, and, comparison with structural data of the homologous vitamin B12 transporter BtuCD suggests that the observed rotation mechanism may contribute a common functional aspect for this class of ABC transporters. Although in HmuuV noticeable rearrangement of essential transmembrane helices was detected, there are no indications from our simulations that ATP binding alone may facilitate propagation of substrate molecules in this transporter

  19. A Silent ABC Transporter Isolated from Streptomyces rochei F20 Induces Multidrug Resistance

    PubMed Central

    Fernández-Moreno, Miguel A.; Carbó, Lázaro; Cuesta, Trinidad; Vallín, Carlos; Malpartida, Francisco

    1998-01-01

    In the search for heterologous activators for actinorhodin production in Streptomyces lividans, 3.4 kb of DNA from Streptomyces rochei F20 (a streptothricin producer) were characterized. Subcloning experiments showed that the minimal DNA fragment required for activation was 0.4 kb in size. The activation is mediated by increasing the levels of transcription of the actII-ORF4 gene. Sequencing of the minimal activating fragment did not reveal any clues about its mechanism; nevertheless, it was shown to overlap the 3′ end of two convergent genes, one of whose translated products (ORF2) strongly resembles that of other genes belonging to the ABC transporter superfamily. Computer-assisted analysis of the 3.4-kb DNA sequence showed the 3′ terminus of an open reading frame (ORF), i.e., ORFA, and three complete ORFs (ORF1, ORF2, and ORFB). Searches in the databases with their respective gene products revealed similarities for ORF1 and ORF2 with ATP-binding proteins and transmembrane proteins, respectively, which are found in members of the ABC transporter superfamily. No similarities for ORFA and ORFB were found in the databases. Insertional inactivation of ORF1 and ORF2, their transcription analysis, and their cloning in heterologous hosts suggested that these genes were not expressed under our experimental conditions; however, cloning of ORF1 and ORF2 together (but not separately) under the control of an expressing promoter induced resistance to several chemically different drugs: oleandomycin, erythromycin, spiramycin, doxorubicin, and tetracycline. Thus, this genetic system, named msr, is a new bacterial multidrug ABC transporter. PMID:9696745

  20. Benzene-derived N2-(4-hydroxyphenyl)-deoxyguanosine adduct: UvrABC incision and its conformation in DNA

    SciTech Connect

    Hang, Bo; Rodriguez, Ben; Yang, Yanu; Guliaev, Anton B.; Chenna, Ahmed

    2010-06-14

    Benzene, a ubiquitous human carcinogen, forms DNA adducts through its metabolites such as p-benzoquinone (p-BQ) and hydroquinone (HQ). N(2)-(4-Hydroxyphenyl)-2'-deoxyguanosine (N(2)-4-HOPh-dG) is the principal adduct identified in vivo by (32)P-postlabeling in cells or animals treated with p-BQ or HQ. To study its effect on repair specificity and replication fidelity, we recently synthesized defined oligonucleotides containing a site-specific adduct using phosphoramidite chemistry. We here report the repair of this adduct by Escherichia coli UvrABC complex, which performs the initial damage recognition and incision steps in the nucleotide excision repair (NER) pathway. We first showed that the p-BQ-treated plasmid was efficiently cleaved by the complex, indicating the formation of DNA lesions that are substrates for NER. Using a 40-mer substrate, we found that UvrABC incises the DNA strand containing N(2)-4-HOPh-dG in a dose- and time-dependent manner. The specificity of such repair was also compared with that of DNA glycosylases and damage-specific endonucleases of E. coli, both of which were found to have no detectable activity toward N(2)-4-HOPh-dG. To understand why this adduct is specifically recognized and processed by UvrABC, molecular modeling studies were performed. Analysis of molecular dynamics trajectories showed that stable G:C-like hydrogen bonding patterns of all three Watson-Crick hydrogen bonds are present within the N(2)-4-HOPh-G:C base pair, with the hydroxyphenyl ring at an almost planar position. In addition, N(2)-4-HOPh-dG has a tendency to form more stable stacking interactions than a normal G in B-type DNA. These conformational properties may be critical in differential recognition of this adduct by specific repair enzymes.

  1. Decoding Debris System Substructures: Imprints of Planets/Planetesimals and Signatures of Extrinsic Influences on Material in Ring-Like Disks

    NASA Astrophysics Data System (ADS)

    Grady, C. A.; Schneider, Glenn; Carson, Joseph; Debes, John H.; Gaspar, Andras; Henning, Thomas; Hines, Dean C.; Hinz, Philip; Jang-Condell, Hannah; Kuchner, Marc J.; Moro-Martin, Amaya; Perrin, Marshall D.; Rodigas, T. J.; Serabyn, Gene; Silverstone, Murray D.; Stark, Christopher C.; Tamura, Motohide; Weinberger, Alycia J.; Wisniewski, John P.; Konishi, Mihoko

    2016-01-01

    How do circumstellar (CS) disks evolve and form planetary systems? Is our solar system's two-component debris disk (DD) typical? Are planets implicated by evidence of dynamical stirring in disks? Are DD architectures correlated with stellar mass? To address these highly-compelling questions of fundamental astrophysical import, we obtained deep follow-up HST/STIS coronagraphic imagery of five intermediate-inclination ring-like DDs. By combining data from two coronagraphic apertures we obtain images with unprecedented clarity, sensitivity, and photometric efficacy. We discover a scattered light counterpart to the dust disk previously seen in the mid-IR only in HD 141569 A interior to the 2 rings previously imaged in scattered light. We also place refined optical limits on planets in that system. For HR 4796 A we detect outer nebulosity extending as far as 10 arc seconds from the star, and compare it with other systems with distant dust. We report on early stages of analysis for our other 3 program stars.

  2. Visible and infrared mapping spectrometer for exploration of comets, asteroids, and the Saturnian system of rings and moons

    NASA Technical Reports Server (NTRS)

    Juergens, David W.; Duval, James E.; Lockhart, Robert F.; Langevin, Yves; Formisano, Vittorio; Bellucci, Giancarlo

    1991-01-01

    Consideration is given to a visible and infrared mapping spectrometer (VIMS) developed by American, Italian, and French scientists and engineers as a facility instrument for the Comet Rendezvous Asteroid Flyby (CRAF) mission and as a candidate facility instrument for the Cassini mission to explore Saturn and its rings and moons. VIMS is characterized by 0.35-5.2 micron spectral range with a nominal spatial resolution of 0.5 mrad and spectral resolutions of 7 nm at 0.35-1.0 micron wavelength and 16 nm at 1.0-5.2 micron wavelength.

  3. Intrinsic structure in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Albers, N.

    2015-10-01

    Saturn's rings are the most prominent in our Solar system and one example of granular matter in space. Dominated by tides and inelastic collisions the system is highly flattened being almost 300000km wide while only tens of meters thick. Individual particles are composed of primarily water ice and range from microns to few tens of meters in size. Apparent patterns comprise ringlets, gaps, kinematic wakes, propellers, bending waves, and the winding spiral arms of density waves. These large-scale structures are perturbations foremost created by external as well as embedded moons. Observations made by the Cassini spacecraft currently in orbit around Saturn show these structures in unprecedented detail. But high-resolution measurements reveal the presence of small-scale structures throughout the system. These include self-gravity wakes (50-100m), overstable waves (100-300m), subkm structure at the A and B ring edges, "straw" and "ropy" structures (1-3km), and the C ring "ghosts". Most of these had not been anticipated and are found in perturbed regions, driven by resonances with external moons, where the system undergoes periodic phases of compression and relaxation that correlate with the presence of structure. High velocity dispersion and the presence of large clumps imply structure formation on time scales as short as one orbit (about 10 hours). The presence of these intrinsic structures is seemingly the response to varying local conditions such as internal density, optical depth, underlying particle size distribution, granular temperature, and distance from the central planet. Their abundance provides evidence for an active and dynamic ring system where aggregation and fragmentation are ongoing on orbital timescales. Thus a kinetic description of the rings may be more appropriate than the fluid one. I will present Cassini Ultraviolet Spectrometer (UVIS) High Speed Photometer (HSP) occultations, Voyager 1 and 2 Imaging Science Subsystem (ISS), and high

  4. Double-O-Ring Plug For Leak Tests

    NASA Technical Reports Server (NTRS)

    Greene, James H.

    1989-01-01

    Pressure plug features redundant O-ring bore seals and axial port opening laterally into space between O-rings to enable testing of seals. Axial passage in plug connected through radial passage to space between O-rings. Opening used to test O-rings, then sealed with smaller O-ring compressed by machine screw. Useful to seal test or cleanout holes normally kept closed in hydraulic actuators, pumps, and other pressurized systems.

  5. On the appearance of a system of ring vortices in the mixing layer of axially symmetric turbulent jets under acoustic action

    NASA Astrophysics Data System (ADS)

    Pimshtein, V. G.

    2016-07-01

    The shadow visualization method is applied to study the process of loss of stability of the mixing layer of a subsonic axially symmetric turbulent jet under longitudinal internal action of saw-tooth sound waves of finite amplitude. Such action leads to the formation of a system of ring vortices in the mixing layer at the frequency of its intrinsic instability. The interaction of the vortices can be accompanied by sound emission. A similar phenomenon is also observed in turbulent jets for small supercritical pressure fluctuations on a nozzle.

  6. A summary of laboratory testing performed to characterize and select an elastomeric O-ring material to be used in the redesigned solid rocket motors of the space transportation system

    NASA Technical Reports Server (NTRS)

    Turner, J. E.

    1993-01-01

    An elastomeric O-ring material is used in the joints of the redesigned solid motors (RSRM's) of the National Space Transportation System (NSTS). The selection of the O-ring material used in the RSRM's was a very thorough process that included efforts by NASA's Marshall Space Flight Center and the Langley Research Center, and the Thiokol Corporation. One of the efforts performed at MSFC was an extensive in-house laboratory test regime to screen potential O-ring materials and ultimately to characterize the elastomeric material that was chosen to be used in the RSRM's. The laboratory tests performed at MSFC are summarized.

  7. Vascular ring (image)

    MedlinePlus

    Vascular ring is a term used to describe a number of abnormal formations of the aorta, the large artery ... the pulmonary artery. The abnormal vessel(s) forms a ring, which encircles and may press down on the ...

  8. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings. PMID:16601188

  9. New dust belts of Uranus: one ring, two ring, red ring, blue ring.

    PubMed

    de Pater, Imke; Hammel, Heidi B; Gibbard, Seran G; Showalter, Mark R

    2006-04-01

    We compared near-infrared observations of the recently discovered outer rings of Uranus with Hubble Space Telescope results. We find that the inner ring, R/2003 U 2, is red, whereas the outer ring, R/2003 U 1, is very blue. Blue is an unusual color for rings; Saturn's enigmatic E ring is the only other known example. By analogy to the E ring, R/2003 U 1 is probably produced by impacts into the embedded moon Mab, which apparently orbits at a location where nongravitational perturbations favor the survival and spreading of submicron-sized dust. R/2003 U 2 more closely resembles Saturn's G ring, which is red, a typical color for dusty rings.

  10. Insights into how nucleotide-binding domains power ABC transport.

    PubMed

    Newstead, Simon; Fowler, Philip W; Bilton, Paul; Carpenter, Elisabeth P; Sadler, Peter J; Campopiano, Dominic J; Sansom, Mark S P; Iwata, So

    2009-09-01

    The mechanism by which nucleotide-binding domains (NBDs) of ABC transporters power the transport of substrates across cell membranes is currently unclear. Here we report the crystal structure of an NBD, FbpC, from the Neisseria gonorrhoeae ferric iron uptake transporter with an unusual and substantial domain swap in the C-terminal regulatory domain. This entanglement suggests that FbpC is unable to open to the same extent as the homologous protein MalK. Using molecular dynamics we demonstrate that this is not the case: both NBDs open rapidly once ATP is removed. We conclude from this result that the closed structures of FbpC and MalK have higher free energies than their respective open states. This result has important implications for our understanding of the mechanism of power generation in ABC transporters, because the unwinding of this free energy ensures that the opening of these two NBDs is also powered. PMID:19748342

  11. Investigation of Finite Element-Abc Methods for Electromagnetic Field Simulation

    NASA Astrophysics Data System (ADS)

    Chatterjee, Arindam

    The demand for accurate characterization and design of complex, composite structures has necessitated the use of numerical techniques for their analysis. Since these structures are often not amenable to closed-form analytical expressions, numerical methods are the only recourse for analyzing these structures. However, a viable numerical method needs to be as efficient and economical as possible such that increasingly complex and large problems can be modeled with minimal computational resources. To this end, the method of finite elements in conjunction with absorbing boundary conditions (ABCs) is proposed in this thesis for solving large and complex three-dimensional problems in unbounded domains. The problem is first formulated using the variational as well as the weighted residual approach. The field variable is expanded in terms of edge-based finite elements on tetrahedra, for the sake of accurate modeling of field continuity and ease of imposing boundary conditions. Initially, the closed problem is solved by determining the eigenvalues of arbitrary, inhomogeneous metallic cavities. For the open problem, ABCs are used as boundary conditions on spherical mesh termination boundaries. The resulting matrix system is sparse symmetric and is found to converge rapidly when solved iteratively. Remarkably accurate results are obtained by placing the truncation boundary only 0.3 lambda from the farthest edge of the target. In order to solve very large problems, the code is optimized on vector as well as parallel architectures like the KSR1 and the Intel iPSC/860. Near-linear speedup is obtained on the KSR1 for the computationally intensive portions of the finite element code, allowing extremely rapid solution for problems involving about half a million unknowns. Since existing ABCs were applicable on spherical mesh termination boundaries, long, thin geometries could be solved only at enormous computational cost. New ABCs enforceable on mesh termination boundaries

  12. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, Larry W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-10-01

    7/16/10 12:23 PM UVIS occultation data show clumping in Saturn's F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime. 7/16/10 12:23 PM 7/16/10 12:23 PM

  13. Boom and Bust Cycles in Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Esposito, L. W.; Meinke, B. K.; Sremcevic, M.; Albers, N.

    2010-12-01

    Cassini UVIS occultation data show clumping in Saturn’s F ring and at the B ring outer edge, indicating aggregation and disaggregation at these locations perturbed by Mimas and Prometheus. Timescales range from hours to months. The maximum clumping lags the moon by roughly π in the forcing frame. This indicates a direct relation between the moon and the ring clumping. We propose that the collective behavior of the ring particles resembles a predator-prey system: the aggregate mean size is the prey, which feeds the velocity dispersion; conversely, increasing dispersion breaks up the aggregates. For realistic values of the parameters this creates a limit cycle behavior, as for the ecology of foxes and hares or the boom-bust economic cycle. Solving for the long-term behavior of this forced system gives a periodic response at the perturbing frequency, with a phase lag roughly consistent with the UVIS occultation measurements. We conclude that the agitation by the moons at both these locations in the F ring and at the B ring outer edge drives aggregation and disaggregation in the forcing frame. This agitation of the ring material allows fortuitous formation of solid objects from the temporary clumps, via stochastic processes like compaction, adhesion, sintering or reorganization that drives the denser parts of the aggregate to the center or ejects the lighter elements. These more persistent objects would then orbit at the Kepler rate. Such processes can create the equinox objects seen at the B ring edge and in the F ring, explain the ragged nature of those ring regions and allow for rare events to aggregate ring particles into solid objects, recycling the ring material and extending the ring lifetime.

  14. TaAbc1, a member of Abc1-like family involved in hypersensitive response against the stripe rust fungal pathogen in wheat.

    PubMed

    Wang, Xiaojing; Wang, Xiaojie; Duan, Yinghui; Yin, Shuining; Zhang, Hongchang; Huang, Li; Kang, Zhensheng

    2013-01-01

    To search for genes involved in wheat (Triticum aestivum L.) defense response to the infection of stripe rust pathogen Puccinia striiformis f. sp. tritici (Pst), we identified and cloned a new wheat gene similar to the genes in the Abc1-like gene family. The new gene, designated as TaAbc1, encodes a 717-amino acid, 80.35 kD protein. The TaAbc1 protein contains two conserved domains shared by Abc1-like proteins, two trans-membrane domains at the C-terminal, and a 36-amino acid chloroplast targeting presequence at the N-terminal. Characterization of TaAbc1 expression revealed that gene expression was tissue-specific and could be up-regulated by biotic agents (e.g., stripe rust pathogen) and/or by an abiotic stress like wounding. High-fold induction was associated with the hypersensitive response (HR) triggered only by avirulent stripe rust pathotypes, suggesting that TaAbc1 is a rust-pathotype specific HR-mediator. Down-regulating TaAbc1 reduced HR but not the overall resistance level in Suwon11 to CYR23, suggesting TaAbc1 was involved in HR against stripe rust, but overall host resistance is not HR-dependent.

  15. Metal Binding Specificity of the MntABC Permease of Neisseria gonorrhoeae and Its Influence on Bacterial Growth and Interaction with Cervical Epithelial Cells▿ †

    PubMed Central

    Lim, Karen H. L.; Jones, Christopher E.; vanden Hoven, Rachel N.; Edwards, Jennifer L.; Falsetta, Megan L.; Apicella, Michael A.; Jennings, Michael P.; McEwan, Alastair G.

    2008-01-01

    mntABC from Neisseria gonorrhoeae encodes an ABC permease which includes a periplasmic divalent cation binding receptor protein of the cluster IX family, encoded by mntC. Analysis of an mntC mutant showed that growth of N. gonorrhoeae could be stimulated by addition of either manganese(II) or zinc(II) ions, suggesting that the MntABC system could transport both ions. In contrast, growth of the mntAB mutant in liquid culture was possible only when the medium was supplemented with an antioxidant such as mannitol, consistent with the view that ion transport via MntABC is essential for protection of N. gonorrhoeae against oxidative stress. Using recombinant MntC, we determined that MntC binds Zn2+ and Mn2+ with almost equal affinity (dissociation constant of ∼0.1 μM). Competition assays with the metallochromic zinc indicator 4-(2-pyridylazo)resorcinol showed that MntC binds Mn2+ and Zn2+ at the same binding site. Analysis of the N. gonorrhoeae genome showed that MntC is the only Mn/Zn metal binding receptor protein cluster IX in this bacterium, in contrast to the situation in many other bacteria which have systems with dedicated Mn and Zn binding proteins as part of distinctive ABC cassette permeases. Both the mntC and mntAB mutants had reduced intracellular survival in a human cervical epithelial cell model and showed reduced ability to form a biofilm. These data suggest that the MntABC transporter is of importance for survival of Neisseria gonorrhoeae in the human host. PMID:18426887

  16. Active breathing control (ABC): Determination and reduction of breathing-induced organ motion in the chest

    SciTech Connect

    Gagel, Bernd . E-mail: BGagel@UKAachen.de; Demirel, Cengiz M.P.; Kientopf, Aline; Pinkawa, Michael; Piroth, Marc; Stanzel, Sven; Breuer, Christian; Asadpour, Branka; Jansen, Thomas; Holy, Richard; Wildberger, Joachim E.; Eble, Michael J.

    2007-03-01

    Purpose: Extensive radiotherapy volumes for tumors of the chest are partly caused by interfractional organ motion. We evaluated the feasibility of respiratory observation tools using the active breathing control (ABC) system and the effect on breathing cycle regularity and reproducibility. Methods and Materials: Thirty-six patients with unresectable tumors of the chest were selected for evaluation of the ABC system. Computed tomography scans were performed at various respiratory phases starting at the same couch position without patient movement. Threshold levels were set at minimum and maximum volume during normal breathing cycles and at a volume defined as shallow breathing, reflecting the subjective maximal tolerable reduction of breath volume. To evaluate the extent of organ movement, 13 landmarks were considering using commercial software for image coregistration. In 4 patients, second examinations were performed during therapy. Results: Investigating the differences in a normal breathing cycle versus shallow breathing, a statistically significant reduction of respiratory motion in the upper, middle, and lower regions of the chest could be detected, representing potential movement reduction achieved through reduced breath volume. Evaluating interfraction reproducibility, the mean displacement ranged between 0.24 mm (chest wall/tracheal bifurcation) to 3.5 mm (diaphragm) for expiration and shallow breathing and 0.24 mm (chest wall) to 5.25 mm (diaphragm) for normal inspiration. Conclusions: By modifying regularity of the respiratory cycle through reduction of breath volume, a significant and reproducible reduction of chest and diaphragm motion is possible, enabling reduction of treatment planning margins.

  17. ABC inventory analysis and economic order quantity concept in hospital pharmacy purchasing.

    PubMed

    Ballentine, R; Ravin, R L; Gilbert, J R

    1976-06-01

    ABC inventory analysis and the economic order quantity (EOQ) concept were studied as alternatives to the cyclical ordering system used by the pharmacy in a 558-bed general hospital. The inventory was divided into A, B or C groups according to the annual dollar value of the items. Two samples were selected to be studied (the first consisting of 10% of the total inventory and the second consisting of 10% of the A, or high cost, items). For each item in both samples the EOQ was calculated to estimate the proposed annual inventory cost as compared to the actual cost as determined from past inventory records. In the first sample, there was a statistically significant mean annual savings of $4.13 +/- $0.36 (S.E.) using the proposed annual cost. In the second sample there was a mean savings of $2.42 +/- $0.60 (S.E.) using the proposed method, which was not statistically significant. Most of the savings with the proposed ABC-EOQ system would occur with the low dollar value items (B and C items) which were being purchased too frequently.

  18. Saturn's F-Ring

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This narrow-angle camera image of Saturn's F Ring was taken through the Clear filter while at a distance of 6.9 million km from Saturn on 8 November 1980. The brightness variations of this tightly-constrained ring shown here indicate that the ring is less uniform in makeup than the larger rings. JPL managed the Voyager Project for NASA's Office of Space Science

  19. Future studies of planetary rings by space probes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1984-01-01

    Recent space probe observations of the rings of Jupiter and Saturn have furnished a substantial enhancement of the current understanding of the outer planets' rings. Voyager 2 offers further opportunities for the study of the Neptune and Uranus ring systems. The Galileo mission to Jupiter furnishes the first opportunity for long term space probe studies of a planetary ring system. It is suggested that an appropriately instrumented Saturn orbiter would not only provide a similar opportunity for the study of the Saturn rings, but may also be the only means by which to adequately address the nature of the diverse phenomena displayed by this prototypical planetary ring system.

  20. Goethe and the ABC model of flower development.

    PubMed

    Coen, E

    2001-06-01

    About 10 years ago, the ABC model for the genetic control of flower development was proposed. This model was initially based on the analysis of mutant flowers but has subsequently been confirmed by molecular analysis. This paper describes the 200-year history behind this model, from the late 18th century when Goethe arrived at his idea of plant metamorphosis, to the genetic studies on flower mutants carried out on Arabidopsis and Antirrhinum in the late 20th century.

  1. Fungal ABC transporters and microbial interactions in natural environments.

    PubMed

    Schoonbeek, Henk-jan; Raaijmakers, Jos M; De Waard, Maarten A

    2002-11-01

    In natural environments, microorganisms are exposed to a wide variety of antibiotic compounds produced by competing organisms. Target organisms have evolved various mechanisms of natural resistance to these metabolites. In this study, the role of ATP-binding cassette (ABC) transporters in interactions between the plant-pathogenic fungus Botrytis cinerea and antibiotic-producing Pseudomonas bacteria was investigated in detail. We discovered that 2,4-diacetylphloroglucinol, phenazine-1-carboxylic acid and phenazine-1-carboxamide (PCN), broad-spectrum antibiotics produced by Pseudomonas spp., induced expression of several ABC transporter genes in B. cinerea. Phenazines strongly induced expression of BcatrB, and deltaBcatrB mutants were significantly more sensitive to these antibiotics than their parental strain. Treatment of B. cinerea germlings with PCN strongly affected the accumulation of [14C]fludioxonil, a phenylpyrrole fungicide known to be transported by BcatrB, indicating that phenazines also are transported by BcatrB. Pseudomonas strains producing phenazines displayed a stronger antagonistic activity in vitro toward ABcatrB mutants than to the parental B. cinerea strain. On tomato leaves, phenazine-producing Pseudomonas strains were significantly more effective in reducing gray mold symptoms incited by a ABcatrB mutant than by the parental strain. We conclude that the ABC transporter BcatrB provides protection to B. cinerea in phenazine-mediated interactions with Pseudomonas spp. Collectively, these results indicate that fungal ABC transporters can play an important role in antibiotic-mediated interactions between bacteria and fungi in plant-associated environments. The implications of these findings for the implementation and sustainability of crop protection by antagonistic microorganisms are discussed. PMID:12423022

  2. Structural analysis of Chi1 Chitinase from Yen-Tc: the multisubunit insecticidal ABC toxin complex of Yersinia entomophaga.

    PubMed

    Busby, Jason N; Landsberg, Michael J; Simpson, Robert M; Jones, Sandra A; Hankamer, Ben; Hurst, Mark R H; Lott, J Shaun

    2012-01-13

    Yersinia entomophaga MH96 is a native New Zealand soil bacterium that secretes a large ABC-type protein toxin complex, Yen-Tc, similar to those produced by nematode-associated bacteria such as Photorhabdus luminescens. Y. entomophaga displays an exceptionally virulent pathogenic phenotype in sensitive insect species, causing death within 72 h of infection. Because of this phenotype, there is intrinsic interest in the mechanism of action of Yen-Tc, and it also has the potential to function as a novel class of biopesticide. We have identified genes that encode chitinases as part of the toxin complex loci in Y. entomophaga MH96, P. luminescens, Photorhabdus asymbiotica and Xenorhabdus nematophila. Furthermore, we have shown that the secreted toxin complex from Y. entomophaga MH96 includes two chitinases as an integral part of the complex, a feature not described previously in other ABC toxins and possibly related to the severe disease caused by this bacterium. We present here the structure of the Y. entomophaga MH96 Chi1 chitinase, determined by X-ray crystallography to 1.74 Å resolution, and show that a ring of five symmetrically arranged lobes on the surface of the Yen-Tc toxin complex structure, as determined by single-particle electron microscopy, provides a good fit to the Chi1 monomer. We also confirm that the isolated chitinases display endochitinase activity, as does the complete toxin complex. PMID:22108167

  3. The Jumping Ring Experiment

    ERIC Educational Resources Information Center

    Baylie, M.; Ford, P. J.; Mathlin, G. P.; Palmer, C.

    2009-01-01

    The jumping ring experiment has become central to liquid nitrogen shows given as part of the outreach and open day activities carried out within the University of Bath. The basic principles of the experiment are described as well as the effect of changing the geometry of the rings and their metallurgical state. In general, aluminium rings are…

  4. Rings Around Uranus

    ERIC Educational Resources Information Center

    Maran, Stephen P.

    1977-01-01

    Events leading up to the discovery of the rings of Uranus are described. The methods used and the logic behind the methods are explained. Data collected to prove the existence of the rings are outlined and theories concerning the presence of planetary rings are presented. (AJ)

  5. Second-order nonlinear optical metamaterials: ABC-type nanolaminates

    SciTech Connect

    Alloatti, L. Kieninger, C.; Lauermann, M.; Köhnle, K.; Froelich, A.; Wegener, M.; Frenzel, T.; Freude, W.; Leuthold, J.; Koos, C.

    2015-09-21

    We demonstrate a concept for second-order nonlinear metamaterials that can be obtained from non-metallic centrosymmetric constituents with inherently low optical absorption. The concept is based on iterative atomic-layer deposition of three different materials, A = Al{sub 2}O{sub 3}, B = TiO{sub 2}, and C = HfO{sub 2}. The centrosymmetry of the resulting ABC stack is broken since the ABC and the inverted CBA sequences are not equivalent—a necessary condition for non-zero second-order nonlinearity. In our experiments, we find that the bulk second-order nonlinear susceptibility depends on the density of interfaces, leading to a nonlinear susceptibility of 0.26 pm/V at a wavelength of 800 nm. ABC-type nanolaminates can be deposited on virtually any substrate and offer a promising route towards engineering of second-order optical nonlinearities at both infrared and visible wavelengths.

  6. ABC-F Proteins Mediate Antibiotic Resistance through Ribosomal Protection

    PubMed Central

    Sharkey, Liam K. R.; Edwards, Thomas A.

    2016-01-01

    ABSTRACT Members of the ABC-F subfamily of ATP-binding cassette proteins mediate resistance to a broad array of clinically important antibiotic classes that target the ribosome of Gram-positive pathogens. The mechanism by which these proteins act has been a subject of long-standing controversy, with two competing hypotheses each having gained considerable support: antibiotic efflux versus ribosomal protection. Here, we report on studies employing a combination of bacteriological and biochemical techniques to unravel the mechanism of resistance of these proteins, and provide several lines of evidence that together offer clear support to the ribosomal protection hypothesis. Of particular note, we show that addition of purified ABC-F proteins to an in vitro translation assay prompts dose-dependent rescue of translation, and demonstrate that such proteins are capable of displacing antibiotic from the ribosome in vitro. To our knowledge, these experiments constitute the first direct evidence that ABC-F proteins mediate antibiotic resistance through ribosomal protection. PMID:27006457

  7. High-level assessment of LANL ABC Design

    SciTech Connect

    Not Available

    1994-04-15

    An annual weapon`s grade Pu disposition goal should be stated and related to the amount of Pu that needs to be disposed of. It needs to be determined to what extent it is possible to destroy Pu without building up any new Pu, i.e., how realistic this goal is. The strong positive Doppler coefficient for a Pu core might require the addition of some fertile material to ensure a negative Doppler coefficient. This in turn will affect the net Pu disposition rate. If a fertile material is required throughout the life of the ABC to ensure a negative Doppler coefficient, the difference between the molten salt ABC and other reactors in regard to Pu disposition is not a principled difference anymore but one of degree. A rationale has then to be developed that explains why {open_quotes}x{close_quotes} kg production of fissile material are acceptable but {open_quotes}y{close_quotes} kg are not. It is important to determine how a requirement for electricity production will impact on the ABC design choices. It is conceivable that DOE will not insist on electricity generation. In this case advantage has to be taken in terms of design simplifications and relaxed operating conditions.

  8. The ABCs of Candida albicans Multidrug Transporter Cdr1

    PubMed Central

    Banerjee, Atanu; Khandelwal, Nitesh Kumar; Dhamgaye, Sanjiveeni

    2015-01-01

    In the light of multidrug resistance (MDR) among pathogenic microbes and cancer cells, membrane transporters have gained profound clinical significance. Chemotherapeutic failure, by far, has been attributed mainly to the robust and diverse array of these proteins, which are omnipresent in every stratum of the living world. Candida albicans, one of the major fungal pathogens affecting immunocompromised patients, also develops MDR during the course of chemotherapy. The pivotal membrane transporters that C. albicans has exploited as one of the strategies to develop MDR belongs to either the ATP binding cassette (ABC) or the major facilitator superfamily (MFS) class of proteins. The ABC transporter Candida drug resistance 1 protein (Cdr1p) is a major player among these transporters that enables the pathogen to outplay the battery of antifungals encountered by it. The promiscuous Cdr1 protein fulfills the quintessential need of a model to study molecular mechanisms of multidrug transporter regulation and structure-function analyses of asymmetric ABC transporters. In this review, we cover the highlights of two decades of research on Cdr1p that has provided a platform to study its structure-function relationships and regulatory circuitry for a better understanding of MDR not only in yeast but also in other organisms. PMID:26407965

  9. Archiving of Planetary Ring Data

    NASA Technical Reports Server (NTRS)

    Elliot, James L.

    2001-01-01

    Stellar occultation data provide our only Earth-based means of probing planetary rings at kilometer spatial resolution. The occultation data archive at MIT contains original data and analysis products of stellar occultations by the ring systems of the planets Jupiter, Saturn, Uranus, and Neptune observed by members of the group (and other groups) from 1977 to the present. During this time period, several media have been used to record and store the original and processed data: (1) chart records; (2) printed output, (3) audio reel tape; (4) audio cassette tape; (5) 7-track, 1/2-inch computer tape; (6) 9-track, 1/2-inch computer tape at 800, 1600, and 6250 bpi; (7) NOVA disk platters (2.5 and 5.0 Mbyte); (8) write once optical disks; (9) punched cards; and (10) read-write optical disks. With the rapid change of computer technology over this time period, some of these media have become not only obsolete, but nearly extinct. In particular, it has become nearly impossible to find any facilities that can still read 800 bpi tapes, which contain the only copies of several important data sets for the ring system of Uranus. In particular, we have an extensive ring data collection that includes data sets for the following Uranian ring occultations: U0, U11, U12, U13, U14, U25, U17, and U36.

  10. Potential role of ABC-assisted repositories in U.S. plutonium and high-level waste disposition

    NASA Astrophysics Data System (ADS)

    Berwald, David; Favale, Anthony; Myers, Timothy; McDaniel, Jerry

    1995-09-01

    This paper characterizes the issues involving deep geologic disposal of LWR spent fuel rods, then presents results of an investigation to quantify the potential role of Accelerator-Based Conversion (ABC) in an integrated national nuclear materials and high level waste disposition strategy. The investigation used the deep geological repository envisioned for Yucca Mt., Nevada as a baseline and considered complementary roles for integrated ABC transmutation systems. The results indicate that although a U.S. geologic waste repository will continue to be required, waste partitioning and accelerator transmutation of plutonium, the minor actinides, and selected long-lived fission products can result in the following substantial benefits: plutonium burndown to near zero levels, a dramatic reduction of the long term hazard associated with geologic repositories, an ability to place several-fold more high level nuclear waste in a single repository, electricity sales to compensate for capital and operating costs.

  11. Potential role of ABC-assisted repositories in U.S. plutonium and high-level waste disposition

    SciTech Connect

    Berwald, David; Favale, Anthony; Myers, Timothy; McDaniel, Jerry

    1995-09-15

    This paper characterizes the issues involving deep geologic disposal of LWR spent fuel rods, then presents results of an investigation to quantify the potential role of Accelerator-Based Conversion (ABC) in an integrated national nuclear materials and high level waste disposition strategy. The investigation used the deep geological repository envisioned for Yucca Mt., Nevada as a baseline and considered complementary roles for integrated ABC transmutation systems. The results indicate that although a U.S. geologic waste repository will continue to be required, waste partitioning and accelerator transmutation of plutonium, the minor actinides, and selected long-lived fission products can result in the following substantial benefits: plutonium burndown to near zero levels, a dramatic reduction of the long term hazard associated with geologic repositories, an ability to place several-fold more high level nuclear waste in a single repository, electricity sales to compensate for capital and operating costs.

  12. Dynamics of dust in Jupiter's gossamer rings

    NASA Astrophysics Data System (ADS)

    Hamilton, D.; Burns, J.; Krueger, H.; Showalter, M.

    2003-04-01

    Over the past several years, the Galileo spacecraft has drastically improved our knowledge of Jupiter's faint rings. We now know the system to be composed of a main ring 7000km wide whose inner edge blossoms into a vertically-extended halo, and a pair of gossamer rings, each one extending inward from a small moon. These moonlets, Thebe and Amalthea, have large orbital tilts and resulting vertical excursions of 1150km and 4300km, respectively. The vertical thicknesses of the two Gossamer rings accurately match these values, providing compelling evidence that the two small satellites act as the dominant sources of ring material. Ring Material is born during high speed impacts onto the moonlet surfaces, after which the material evolves inward under the action of a dissipative force, either Poynting-Robertson Drag or Resonant Charge Variations. The basic framework for the origin and evolution of the Gossamer Rings is well understood, but there are a few loose ends that are not so easily explained: i) an outward extension of the Thebe Ring, ii) the nature of the dissipative force. In this talk I will report my latest dynamical modeling of the Gossamer rings associated with Thebe and Amalthea, and will discuss how in-situ impact data collected by the Galileo dust detector during the first ever ring "fly-through" may help to resolve some of these and other outstanding issues.

  13. Efficient Synthesis of the 2-amino-6-chloro-4-cyclopropyl-7-fluoro-5-methoxy-pyrido[1,2-c]pyrimidine-1,3-dione core ring system

    PubMed Central

    Rosen, Jonathan D.; German, Nadezhda; Kerns, Robert J.

    2008-01-01

    An optimized total synthesis of the 2-amino-6-chloro-4-cyclopropyl-7-fluoro-5-methoxy-pyrido[1,2-c]pyrimidine-1,3-dione core structure of a new fluoroquinolone-like class of antibacterial agents is described. This synthesis is highlighted by a nearly quantitative ring-closing reaction to form the pyrido[1,2-c]pyrimidine core. This bicyclic ring system serves as a scaffold for a family of biologically active compounds. PMID:20160840

  14. Multi-wavelength studies of Saturn's rings to constrain ring particle properties and ring structure: the VIMS perspective

    NASA Astrophysics Data System (ADS)

    Filacchione, G.; Capaccioni, F.; Ciarniello, M.; Nicholson, P. D.; Hedmann, M. M.; Clark, R. N.; Cerroni, P.; Spilker, L. J.; Colwell, J.; Bradley, T.

    2012-04-01

    Saturn has the most prominent and complex ring system in our solar system, extending along radial axis from 74658 km (inner C ring edge) to 136780 km (outer A). The physical and dynamical properties of ring particles can be fully understood only using a broad spectral range, which allow us to recognize very different processes. In this context, the scientific goal of our investigation is the study of Saturn's rings particle properties using combined datasets returned from different instruments aboard the Cassini mission. We are merging rings observations and compare results collected by Cassini's UV Imaging Spectrometer (UVIS), Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS) and Composite Infrared Spectrometer (CIRS). Merging multi-wavelength data sets allow us to test different thermal models, combining the effects of particle albedo, regolith composition, grain size and thermal properties with the ring structure. In this work we report about the VIMS contributions to this investigation, coming from the analysis of 0.35-5.1 µm spectra of A, B, C rings and Cassini Division. VIMS, in fact, has the capabilities to determine ring particles composition (water ice vs. chromophores mixed within ice), surface regolith grain size and particle albedo. After having described the dataset considered in this work (several rings radial mosaics taken at 12° ≤ phase ≤ 136° and -21° ≤ opening angle ≤ +5°) and the method to reduce data to spectrograms, we explain how the spectral indicators we have selected (slopes and band parameters) allow us to infer ring particle properties across different regions. Specifically, we report about: 1) the variations induced by illumination phase on visible reddening and water ice bands depth; 2) the average composition and regolith grain size of ring particles in A, B, C rings and CD; 3) an application of Hapke's model to compare VIMS data with synthetic spectra.

  15. The Structure of the Uranian Rings and the Search for Rings Around Neptune

    NASA Technical Reports Server (NTRS)

    Elliot, J. L.

    1984-01-01

    The nine narrow rings of Uranus, presently the only confirmed features of this system, have been observed with the diffraction-limited resolution (3.5 km) of ground-based occultations since their discovery in 1977. These data have been used to establish an orbit model, from which the five Keplerian orbit parameters for each ring, the pole of the mean ring plane, and the gravitational harmonic coefficients J sub 2 and J sub 4 have been determined. The rings are typically a few kilometers wide with eccentricities of about 0.001 and inclinations of a few hundredths of a degree, although a few have no measurable eccentricity or inclination. Interesting Voyager investigations would include probing the structure of the rings at higher spatial resolution, searching for new rings in the system (including inter-ring material), locating the postulated shepherd satellites, and searching for satellites inside the orbit of Miranda that might have dynamical influence on the rings. The high precision (approx 2 km) of the ring orbits might prove useful for spacecraft navigation. For Neptune, occultation searches have revealed no rings to a limit of a few hundreths optical depth, within a few hundred kilometers from the top of the planet's atmosphere (for equatorial rings).

  16. ABC1K atypical kinases in plants; filling the organellar kinase void

    PubMed Central

    Lundquist, Peter K.; Davis, Jerrold I.; van Wijk, Klaas J.

    2014-01-01

    Surprisingly few protein kinases have been demonstrated in chloroplasts or mitochondria. Here we discuss the “activity of bc1 complex kinase” (ABC1K) protein family which we suggest locate in mitochondria and plastids, thus filling the kinase void. The ABC1Ks are atypical protein kinases and their ancestral function is the regulation of quinone synthesis. ABC1Ks have proliferated from 1–2 members in non-photosynthetic organisms to more than 16 members in algae and higher plants. In this review we reconstruct the evolutionary history of the ABC1K family, provide a functional domain analysis for angiosperms and a nomenclature for ABC1Ks in Arabidopsis (Arabidopsis thaliana), rice (Oryza sativa) and maize (Zea mays). Finally, we hypothesize that targets of ABC1Ks include enzymes of prenyl-lipid metabolism as well as components of the organellar gene expression machineries. PMID:22694836

  17. Simulation of Rings about Ellipsoidal Bodies

    NASA Astrophysics Data System (ADS)

    Gupta, Akash; Nadkarni-Ghosh, Sharvari; Sharma, Ishan

    2016-10-01

    Recent discovery of rings around Chariklo, a centaur orbiting the Sun (F. Braga-Ribas et al., 2014) and speculations of rings around minor planet, Chiron (Ortiz et al., 2015), Saturn's satellites, Rhea (Jones et al., 2008; Schenk et al., 2011), Iapetus (Ip, 2006) or exoplanets, suggest that rings about non-spherical bodies is perhaps a more general phenomenon than anticipated. As a first step towards understanding such systems, we examine the dynamical behavior of rings around similar bodies using N-body simulations. Our code employs the `local simulation method' (Wisdom & Tremaine, 1988; Salo, 1995) and accounts for particle interactions via collisions using Discrete Element Method (Cundall & Strack, 1978; Bhateja et al., 2016) and mutual gravitation. The central body has been modeled as an axisymmetric ellipsoid characterized by its axis ratio, or defined via characteristic frequencies (circular, vertical and epicyclic frequency) representing the gravitational field of an axisymmetric body. We vary the central body's characterizing parameter and observe the change in various ring properties like the granular temperature, impact frequency, radial width and vertical thickness. We also look into the effect on ring properties upon variation in the size of the central body-ring system. Further, we investigate the role of characteristic frequencies in dictating the ring dynamics, and how this could help in qualitatively estimating the ring dynamics about any arbitrary central body with symmetry about the equatorial plane and the axis normal to it.

  18. Accretion in Saturn's F Ring

    NASA Astrophysics Data System (ADS)

    Meinke, B. K.; Esposito, L. W.; Stewart, G.

    2012-12-01

    Saturn's F ring is the solar system's principal natural laboratory for direct observation of accretion and disruption processes. The ring resides in the Roche zone, where tidal disruption competes with self-gravity, which allows us to observe the lifecycle of moonlets. Just as nearby moons create structure at the B ring edge (Esposito et al. 2012) and the Keeler gap (Murray 2007), the F ring "shepherding" moons Prometheus and Pandora stir up ring material and create observably changing structures on timescales of days to decades. In fact, Beurle et al (2010) show that Prometheus makes it possible for "distended, yet gravitationally coherent clumps" to form in the F ring, and Barbara and Esposito (2002) predicted a population of ~1 km bodies in the ring. In addition to the observations over the last three decades, the Cassini Ultraviolet Imaging Spectrograph (UVIS) has detected 27 statistically significant features in 101 occultations by Saturn's F ring since July 2004. Seventeen of those 27 features are associated with clumps of ring material. Two features are opaque in occultation, which makes them candidates for solid objects, which we refer to as Moonlets. The 15 other features partially block stellar signal for 22 m to just over 3.7 km along the radial expanse of the occultation. Upon visual inspection of the occultation profile, these features resemble Icicles, thus we will refer to them as such here. The density enhancements responsible for such signal attenuations are likely due to transient clumping of material, evidence that aggregations of material are ubiquitous in the F ring. Our lengthy observing campaign reveals that Icicles are likely transient clumps, while Moonlets are possible solid objects. Optical depth is an indicator of clumping because more-densely aggregated material blocks more light; therefore, it is natural to imagine moonlets as later evolutionary stage of icicle, when looser clumps of material compact to form a feature that appears

  19. Identification of ABC Transporter Genes of Fusarium graminearum with Roles in Azole Tolerance and/or Virulence

    PubMed Central

    Döll, Katharina; Karlovsky, Petr; Deising, Holger B.; Wirsel, Stefan G. R.

    2013-01-01

    Fusarium graminearum is a plant pathogen infecting several important cereals, resulting in substantial yield losses and mycotoxin contamination of the grain. Triazole fungicides are used to control diseases caused by this fungus on a worldwide scale. Our previous microarray study indicated that 15 ABC transporter genes were transcriptionally upregulated in response to tebuconazole treatment. Here, we deleted four ABC transporter genes in two genetic backgrounds of F. graminearum representing the DON (deoxynivalenol) and the NIV (nivalenol) trichothecene chemotypes. Deletion of FgABC3 and FgABC4 belonging to group I of ABC-G and to group V of ABC-C subfamilies of ABC transporters, respectively, considerably increased the sensitivity to the class I sterol biosynthesis inhibitors triazoles and fenarimol. Such effects were specific since they did not occur with any other fungicide class tested. Assessing the contribution of the four ABC transporters to virulence of F. graminearum revealed that, irrespective of their chemotypes, deletion mutants of FgABC1 (ABC-C subfamily group V) and FgABC3 were impeded in virulence on wheat, barley and maize. Phylogenetic context and analyses of mycotoxin production suggests that FgABC3 may encode a transporter protecting the fungus from host-derived antifungal molecules. In contrast, FgABC1 may encode a transporter responsible for the secretion of fungal secondary metabolites alleviating defence of the host. Our results show that ABC transporters play important and diverse roles in both fungicide resistance and pathogenesis of F. graminearum. PMID:24244413

  20. Electronic Structure of ABC-stacked Multilayer Graphene and Trigonal Warping:A First Principles Calculation

    NASA Astrophysics Data System (ADS)

    Yelgel, Celal

    2016-04-01

    We present an extensive density functional theory (DFT) based investigation of the electronic structures of ABC-stacked N-layer graphene. It is found that for such systems the dispersion relations of the highest valence and the lowest conduction bands near the K point in the Brillouin zone are characterised by a mixture of cubic, parabolic, and linear behaviours. When the number of graphene layers is increased to more than three, the separation between the valence and conduction bands decreases up until they touch each other. For five and six layer samples these bands show flat behaviour close to the K point. We note that all states in the vicinity of the Fermi energy are surface states originated from the top and/or bottom surface of all the systems considered. For the trilayer system, N = 3, pronounced trigonal warping of the bands slightly above the Fermi level is directly obtained from DFT calculations.