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Sample records for arpo bibi steinberg

  1. 65th birthday Jack Steinberger

    SciTech Connect

    2007-12-04

    Laudatio pour Jack Steinberger né le 25 mai 1921, à l'occasion de son 65me anniversaire et sa retraite officielle, pour sa précieuse collaboration au Cern. Néanmoins son principal activité continuera comme avant dans sa recherche au Cern. Plusieurs orateurs prennent la parole (p.ex. E.Picasso) pour le féliciter et lui rendre hommage

  2. 65th birthday Jack Steinberger

    ScienceCinema

    None

    2016-07-12

    Laudatio pour Jack Steinberger né le 25 mai 1921, à l'occasion de son 65me anniversaire et sa retraite officielle, pour sa précieuse collaboration au Cern. Néanmoins son principal activité continuera comme avant dans sa recherche au Cern. Plusieurs orateurs prennent la parole (p.ex. E.Picasso) pour le féliciter et lui rendre hommage

  3. The Media Do Matter: Comment on Steinberg and Monahan (2011)

    ERIC Educational Resources Information Center

    Brown, Jane D.

    2011-01-01

    Steinberg and Monahan's (2011) reanalysis of the Teen Media longitudinal survey of adolescents does not meet prevailing standards for propensity score analysis and therefore does not undermine the original conclusions of the Brown, L'Engle, Pardun, Guo, Kenneavy, and Jackson (2006) analysis. The media do matter in the sexual socialization of…

  4. Lattice dynamics and electron-phonon interaction in Bi/Bi2Te3 (111) heteroepitaxial film

    NASA Astrophysics Data System (ADS)

    Huang, G. Q.; Li, B.

    2013-12-01

    Bi/Bi2Te3 (111) heteroepitaxial film is a novel system which combines two-dimensional and three-dimensional topological insulators. The lattice dynamical properties and the electron-phonon coupling in this heteroepitaxial film are calculated by including spin-orbit coupling from density functional perturbation theory. Full phonon dispersion curves are calculated and the zone-center Raman active modes are analyzed. There is a large mismatch in the phonon densities of states between ultrathin Bi deposited layers and Bi2Te3 substrate, which might have a significant improvement of thermoelectric performance of this system. The large electron-phonon coupling λ in Bi/Bi2Te3 heteroepitaxial film suggests that this system may hopefully become a topological superconductor.

  5. Use of the Steinberg and Carroll-Holt Concepts in Ductile Fracture

    NASA Astrophysics Data System (ADS)

    Seaman, Lynn; Boustie, Michel; de Resseguier, Thibaut

    1997-07-01

    We have extended the SRI ductile fracture model (DFRACT) for spall behavior of aluminum and copper. The temperature computation procedure, thermal strength reduction function, work hardening, and Bauschinger effects from the Steinberg model ( D. J. Steinberg, S. G. Cochran, and M. W. Guinan, J. Appl. Phys. 51, 1498 (1980))were added. The threshold stress for void growth in the DFRACT model was equated to the stress for general yielding in the Carroll-Holt model (M. M. Carroll and A. C. Holt, J. Appl. Phys. 43, 1626 (1972)) for porous materials. With these modifications of DFRACT, we simulated a series of earlier SRI impacts in 1145 (commercially pure) aluminum in which partial spall had been reached. The revised model was able to represent the numbers, sizes, and locations of voids through the sample. The use of the Carroll-Holt and Steinberg model features allows the DFRACT model to reach larger void volumes in the simulations and therefore to better represent heavy damage.

  6. Award for Distinguished Contributions to Research in Public Policy: Laurence Steinberg

    ERIC Educational Resources Information Center

    American Psychologist, 2009

    2009-01-01

    Laurence Steinberg, recipient of the Award for Distinguished Contributions to Research in Public Policy, is cited for his extraordinary impact on policy in juvenile justice and child labor and on research into the role of parent and peer relationships in the development of children and adolescents. His groundbreaking research is marked by a…

  7. Narrow Assessments Misrepresent Development and Misguide Policy: Comment on Steinberg, Cauffman, Woolard, Graham, and Banich (2009)

    ERIC Educational Resources Information Center

    Fischer, Kurt W.; Stein, Zachary; Heikkinen, Katie

    2009-01-01

    Intellectual and psychosocial functioning develop along complex learning pathways. Steinberg, Cauffman, Woolard, Graham, and Banich measured these two classes of abilities with narrow, biased assessments that captured only a segment of each pathway and created misleading age patterns based on ceiling and floor effects. It is a simple matter to…

  8. Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal-semiconductor-heterojunction-assisted photoluminescence

    NASA Astrophysics Data System (ADS)

    Patil, Ranjit A.; Wei, Mao-Kuo; Yeh, P.-H.; Liang, Jyun-Bo; Gao, Wan-Ting; Lin, Jin-Han; Liou, Yung; Ma, Yuan-Ron

    2016-02-01

    We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs).We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes

  9. Facile fabrication of superhydrophobic Bi/Bi2O3 surfaces with hierarchical micro-nanostructures by electroless deposition or electrodeposition

    NASA Astrophysics Data System (ADS)

    Cao, Ling; Lu, Xiaoqing; Pu, Fang; Yin, Xiangle; Xia, Yue; Huang, Wei; Li, Zelin

    2014-01-01

    Superhydrophobic metallic surfaces are attracting wide interest. In this work, two facile one-step methods (displacement reaction and electrodeposition) were developed to fabricate superhydrophobic Bi/Bi2O3 surfaces with hierarchical porous dendritic structures, where the Bi2O3 cover layer was formed by surface self-passivation of the deposited Bi. The influence of various experimental parameters on the surface morphology and wettability were investigated in detail, including concentration of solutions, deposition times, and deposition potentials. A maximum contact angle about 164° can be obtained on the fabricated superhydrophobic Bi/Bi2O3 surfaces by these two methods under optimized conditions without additional surface modification.

  10. Low Emissions Alternative Power (LEAP) Project Office Business Team of the Aeropropulsion Research Program Office (ARPO) Org. 0140

    NASA Technical Reports Server (NTRS)

    Buttler, Jennifer A.

    2004-01-01

    The program for which I am working at this summer is Propulsion and Power/Low Emissions Alternative Power (P&P/LEAP). It invests in a fundamental TRL 1-6 research and technology portfolio that will enable the future of: Alternative fuels and/or alternative propulsion systems, non-combustion (electric) propulsion systems. P&P/LEAP will identify and capitalize on the highest potential concepts generated both internal and external to the Agency. During my 2004 summer at NASA Glenn Research Center, I worked with my mentor Barbara Mader, in the Project Office with the Business Team completing various tasks for the project and personnel. The LEAP project is a highly matrixed organization. The Project Office is responsible for the goals advocacy and dollar (budget) of the LEAP project. The objectives of the LEAP Project are to discover new energy sources and develop unconventional engines and power systems directed towards greatly reduced emissions, enable new vehicle concepts for public mobility, new science missions and national security. The Propulsion and PowerLow Emissions Alternative Power directly supports the environmental, mobility, national security objectives of the Vehicle Systems Program and the Aeronautics Technology Theme. Technology deliverables include the demonstration through integrated ground tests, a constant volume combustor in an engine system, and UAV/small transport aircraft all electric power system. My mentor serves as a key member of the management team for the Aeropropulsion Research Program Office (ARPO). She has represented the office on numerous occasions, and is a member of a number of center-wide panels/teams, such as the Space management Committee and is chair to the Business Process Consolidation Team. She is responsible for the overall coordination of resources for the Propulsion and Power Project - from advocacy to implementation. The goal for my summer at NASA was to document processes and archive program documents from the past

  11. Size-controllable synthesis of Bi/Bi2O3 heterojunction nanoparticles using pulsed Nd:YAG laser deposition and metal-semiconductor-heterojunction-assisted photoluminescence.

    PubMed

    Patil, Ranjit A; Wei, Mao-Kuo; Yeh, P-H; Liang, Jyun-Bo; Gao, Wan-Ting; Lin, Jin-Han; Liou, Yung; Ma, Yuan-Ron

    2016-02-14

    We synthesized Bi/Bi2O3 heterojunction nanoparticles at various substrate temperatures using the pulsed laser deposition (PLD) technique with a pulsed Nd:YAG laser. The Bi/Bi2O3 heterojunction nanoparticles consisted of Bi nanoparticles and Bi2O3 surface layers. The average diameter of the Bi nanoparticles and the thickness of the Bi2O3 surface layer are linearly proportional to the substrate temperature. The heterojunctions between the Bi nanoparticles and Bi2O3 surface layers, which are the metal-semiconductor heterojunctions, can strongly enhance the photoluminescence (PL) of the Bi/Bi2O3 nanoparticles, because the metallic Bi nanoparticles can provide massive free Fermi-level electrons for the electron transitions in the Bi2O3 surface layers. The enhancement of PL emission at room temperature by metal-semiconductor-heterojunctions make the Bi/Bi2O3 heterojunction nanoparticles potential candidates for use in optoelectronic nanodevices, such as light-emitting diodes (LEDs) and laser diodes (LDs).

  12. Kinetics of Spanish broom peroxidase obeys a Ping-Pong Bi-Bi mechanism with competitive inhibition by substrates.

    PubMed

    Pérez Galende, Patricia; Hidalgo Cuadrado, Nazaret; Kostetsky, Eduard Ya; Roig, Manuel G; Villar, Enrique; Shnyrov, Valery L; Kennedy, John F

    2015-11-01

    In plants, adverse conditions often induce an increase in reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). H2O2 is reduced to water, and thus becomes detoxified by enzymes such as Cytisus multiflorus peroxidase (CMP). Here, the steady-state kinetics of the H2O2-supported oxidation of different organic substrates by CMP was investigated. Analysis of the initial rates vs. H2O2 and reducing substrate concentrations proved to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters [Formula: see text] , [Formula: see text] , kcat, [Formula: see text] , [Formula: see text] and of the microscopic rate constants, k1 and k3, of the shared three-step catalytic cycle of peroxidases.

  13. Kinetics of Spanish broom peroxidase obeys a Ping-Pong Bi-Bi mechanism with competitive inhibition by substrates.

    PubMed

    Pérez Galende, Patricia; Hidalgo Cuadrado, Nazaret; Kostetsky, Eduard Ya; Roig, Manuel G; Villar, Enrique; Shnyrov, Valery L; Kennedy, John F

    2015-11-01

    In plants, adverse conditions often induce an increase in reactive oxygen species (ROS) such as hydrogen peroxide (H2O2). H2O2 is reduced to water, and thus becomes detoxified by enzymes such as Cytisus multiflorus peroxidase (CMP). Here, the steady-state kinetics of the H2O2-supported oxidation of different organic substrates by CMP was investigated. Analysis of the initial rates vs. H2O2 and reducing substrate concentrations proved to be consistent with a substrate-inhibited Ping-Pong Bi-Bi reaction mechanism. The phenomenological approach expresses the peroxidase Ping-Pong mechanism in the form of the Michaelis-Menten equation and affords an interpretation of the effects in terms of the kinetic parameters [Formula: see text] , [Formula: see text] , kcat, [Formula: see text] , [Formula: see text] and of the microscopic rate constants, k1 and k3, of the shared three-step catalytic cycle of peroxidases. PMID:26416239

  14. Accuracy of potentiometric oxygen sensors with Bi/Bi2O3 reference electrode for use in liquid LBE

    NASA Astrophysics Data System (ADS)

    Lim, J.; Mariën, A.; Rosseel, K.; Aerts, A.; Van den Bosch, J.

    2012-10-01

    Potentiometric oxygen sensors fabricated with yttria partially stabilized zirconia (YPSZ) and a Bi/Bi2O3 reference electrode were tested in oxygen saturated lead-bismuth eutectic (LBE) and oxygen saturated tin (Sn), respectively, in order to estimate the accuracy of the oxygen sensors prior to applying them to R&D work for MYRRHA. The accuracy of these sensors was estimated in the temperature range of 673-733 K by measuring the electromotive force (emf) of eight sensors. The standard deviation on the measured emf data was about 0.79 mV in the case of oxygen saturated LBE and was about 1.25 mV in the case of oxygen saturated Sn. These values result in a standard deviation of 4% on the oxygen concentration in LBE which is calculated from the measured emf.

  15. a Steinberg-Guinan Model for High-Pressure Carbon: Diamond Phase

    NASA Astrophysics Data System (ADS)

    Orlikowski, Daniel; Correa, Alfredo A.; Schwegler, Eric; Klepeis, John E.

    2007-12-01

    Since the diamond phase of carbon has such a high yield strength, dynamic simulations must account for strength even for strong shock waves (˜3 Mbar). We have determined an initial parametrization of two strength models: Steinberg-Guinan (SG) and a modified or improved SG(ISG), that captures the high pressure dependence of the calculated shear modulus up to 10 Mbar. The models are based upon available experimental data and on calculated elastic moduli using robust density functional theory. Additionally, we have evaluated these models using hydrodynamic simulations of planar shocks experiments.

  16. A Steinberg-Guinan model for High-Pressure Carbon, Diamond Phase

    SciTech Connect

    Orlikowski, D; Correa, A; Schwegler, E; Klepeis, J

    2007-07-27

    Since the carbon, diamond phase has such a high yield strength, dynamic simulations must account for strength even for strong shock waves ({approx} 3 Mbar). We have determined an initial parametrization of two strength models: Steinberg-Guinan (SG) and a modified or improved SG, that captures the high pressure dependence of the calculated shear modulus up to 10 Mbar. The models are based upon available experimental data and on calculated elastic moduli using robust density functional theory. Additionally, we have evaluated these models using hydrodynamic simulations of planar shocks experiments.

  17. Narrow assessments misrepresent development and misguide policy: comment on Steinberg, Cauffman, Woolard, Graham, and Banich (2009).

    PubMed

    Fischer, Kurt W; Stein, Zachary; Heikkinen, Katie

    2009-10-01

    Intellectual and psychosocial functioning develop along complex learning pathways. Steinberg, Cauffman, Woolard, Graham, and Banich (see record 2009-18110-001) measured these two classes of abilities with narrow, biased assessments that captured only a segment of each pathway and created misleading age patterns based on ceiling and floor effects. It is a simple matter to shift the assessments to produce the opposite pattern, with cognitive abilities appearing to develop well into adulthood and psychosocial abilities appearing to stop developing at age 16. Their measures also lacked a realistic connection to the lived behaviors of adolescents, abstracting too far from messy realities and thus lacking ecological validity and the nuanced portrait that the authors called for. A drastically different approach to assessing development is required that (a) includes the full age-related range of relevant abilities instead of a truncated set and (b) examines the variability and contextual dependence of abilities relevant to the topics of murder and abortion. PMID:19824746

  18. [The terminal patient: Jewish religious law, the Steinberg report and the bioethical discourse in Israel].

    PubMed

    Barilan, Y Michael

    2003-07-01

    This article surveys key texts in contemporary orthodox Jewish law (Halakha) with regard to end-of-life decision making. The author proposes twelve principles that govern Jewish law in that matter. The article proceeds to examine the Steinberg report in the light of Halakha. Orthodox Judaism regards human life as a prime value, which is always beyond consideration of economical means or quality of life. The avoidance of suffering is the only justification to shorten the life of the sufferer, provided that the acts performed do not fall within the Halakhic definition of murder, namely active and direct action that shortens life. It is argued that the main challenge of bioethics in Israel is the bridging between the positive law of Halakha whose fundamental value is submission to God's will as manifested in Halakha, and the rationalism, universalism, and egalitarianism which constitute naturalistic ethics. This challenge may produce ideas such as the "clock machine". It is too early to know if this is a trickery, or genuine ethical creativity.

  19. Depleted subcontinental lithospheric mantle and its tholeiitic melt metasomatism beneath NE termination of the Eger Rift (Europe): the case study of the Steinberg (Upper Lusatia, SE Germany) xenoliths

    NASA Astrophysics Data System (ADS)

    Kukuła, Anna; Puziewicz, Jacek; Matusiak-Małek, Magdalena; Ntaflos, Theodoros; Büchner, Jörg; Tietz, Olaf

    2015-12-01

    The ca. 30 Ma Steinberg basanite occurs at the NE termination of the Eger (Ohře) Rift in the NW Bohemian Massif, Central Europe, and belongs to the Cenozoic alkaline Central European Volcanic Province. The basanite hosts a suite of mantle xenoliths, most of which are harzburgites containing relatively magnesian olivine (Fo 90.5-91.6) and Al-poor (0.04-0.13 a pfu) orthopyroxene (mg# 0.90-0.92). Some of these harzburgites also contain volumetrically minor clinopyroxene (mg# 0.92-0.95, Al 0.03-0.13 a pfu) and have U-shaped LREE-enriched REE patterns. The Steinberg harzburgites are typical for the Lower Silesian - Upper Lusatian domain of the European subcontinental lithospheric mantle. They represent residual mantle that has undergone extensive partial melting and was subsequently affected by mantle metasomatism by mixed carbonatite-silicate melts. The Steinberg xenolith suite comprises also dunitic xenoliths affected by metasomatism by melt similar to the host basanite, which lowered the Fo content in olivine to 87.6 %. This metasomatism happened shortly before xenolith entrainment in the erupting lava. One of the xenoliths is a wehrlite (olivine Fo 73 %, clinopyroxene mg# 0.83-0.85, subordinate orthopyroxene mg# 0.76-0.77). Its clinopyroxene REE pattern is flat and slightly LREE-depleted. This wehrlite is considered to be a tholeiitic cumulate. One of the studied harzburgites contains clinopyroxene with similar trace element contents to those in wehrlite. This type of clinopyroxene records percolation of tholeiitic melt through harzburgite. The tholeiitic melt might be similar to Cenozoic continental tholeiites occurring in the Central European Volcanic Province (e.g., Vogelsberg, Germany).

  20. Changing the Context Is Important and Necessary, but Not Sufficient, for Reducing Adolescent Risky Sexual Behavior: A Reply to Steinberg (2015).

    PubMed

    Bryan, Angela D; Gillman, Arielle S; Hansen, Natasha S

    2016-07-01

    Starting school later, keeping adolescents busy with structured programming, and making free condoms available, as Steinberg (2015) suggests, are important and necessary steps, but they are simply not sufficient if the goal is reducing sexually transmitted infections and unplanned pregnancy. We agree that the current state of affairs, which in many schools involves sexuality education using programs that are not empirically supported, is unacceptable. However, abandoning sexuality education entirely would leave adolescents ill equipped to protect themselves. Despite the fact that current intervention technology is neither perfect nor optimally effective, there are empirically supported, school-based sexual risk reduction interventions that teach these skills and are readily available. In addition, even though we agree that structured afternoon programs for school-aged adolescents would reduce the opportunity for sexual risk behavior during the school years, such programs would not address the demographic reality of sexual risk that continues for adolescents and emerging adults far past the end of traditional secondary education. We believe Steinberg's suggestions are an excellent start and ought to be implemented. But complementary to this approach should be the use of existing empirically supported sexual risk reduction interventions and research into the development of even more effective interventions. PMID:27474139

  1. Changing the Context Is Important and Necessary, but Not Sufficient, for Reducing Adolescent Risky Sexual Behavior: A Reply to Steinberg (2015).

    PubMed

    Bryan, Angela D; Gillman, Arielle S; Hansen, Natasha S

    2016-07-01

    Starting school later, keeping adolescents busy with structured programming, and making free condoms available, as Steinberg (2015) suggests, are important and necessary steps, but they are simply not sufficient if the goal is reducing sexually transmitted infections and unplanned pregnancy. We agree that the current state of affairs, which in many schools involves sexuality education using programs that are not empirically supported, is unacceptable. However, abandoning sexuality education entirely would leave adolescents ill equipped to protect themselves. Despite the fact that current intervention technology is neither perfect nor optimally effective, there are empirically supported, school-based sexual risk reduction interventions that teach these skills and are readily available. In addition, even though we agree that structured afternoon programs for school-aged adolescents would reduce the opportunity for sexual risk behavior during the school years, such programs would not address the demographic reality of sexual risk that continues for adolescents and emerging adults far past the end of traditional secondary education. We believe Steinberg's suggestions are an excellent start and ought to be implemented. But complementary to this approach should be the use of existing empirically supported sexual risk reduction interventions and research into the development of even more effective interventions.

  2. Steinberg ``AUDIOMAPS'' Music Appreciation-Via-Understanding: Special-Relativity + Expectations ``Quantum-Theory'': a Quantum-ACOUSTO/MUSICO-Dynamics (QA/MD)

    NASA Astrophysics Data System (ADS)

    Fender, Lee; Steinberg, Russell; Siegel, Edward Carl-Ludwig

    2011-03-01

    Steinberg wildly popular "AUDIOMAPS" music enjoyment/appreciation-via-understanding methodology, versus art, music-dynamics evolves, telling a story in (3+1)-dimensions: trails, frames, timbres, + dynamics amplitude vs. music-score time-series (formal-inverse power-spectrum) surprisingly closely parallels (3+1)-dimensional Einstein(1905) special-relativity "+" (with its enjoyment-expectations) a manifestation of quantum-theory expectation-values, together a music quantum-ACOUSTO/MUSICO-dynamics(QA/MD). Analysis via Derrida deconstruction enabled Siegel-Baez "Category-Semantics" "FUZZYICS"="CATEGORYICS ('TRIZ") Aristotle SoO DEduction , irrespective of Boon-Klimontovich vs. Voss-Clark[PRL(77)] music power-spectrum analysis sampling-time/duration controversy: part versus whole, shows QA/MD reigns supreme as THE music appreciation-via-analysis tool for the listener in musicology!!! Connection to Deutsch-Hartmann-Levitin[This is Your Brain on Music, (06)] brain/mind-barrier brain/mind-music connection is subtle/compelling/immediate!!!

  3. Synthesis and Biological Activity of Manganese (II) Complexes of Phthalic and Isophthalic Acid: X-Ray Crystal Structures of [Mn(ph)(Phen)2(H2O)]· 4H2O, [Mn(Phen)2(H2O)2]2(Isoph)2(Phen)· 12H2O and {[Mn(Isoph)(bipy)]4· 2.75biby}n(phH2 = Phthalic Acid; isoph = Isophthalic Acid; phen = 1,10-Phenanthroline; bipy = 2,2-Bipyridine)

    PubMed Central

    McCann, Malachy; Leon, Vanessa; Geraghty, Majella; McKee, Vickie; Wikaira, Jan

    2000-01-01

    Manganese(II) acetate reacts with phthalic acid (phH2) to give [Mn(ph)]·0.5H2O (1). Reaction of 1 with 1,10-phenanthroline produces [Mn(ph)(phen)]·2H2O (2) and [Mn(ph)(phen)2(H2O)]·4H2O (3). Reaction of isophthalic acid (isophH2) with manganese(II) acetate results in the formation of [Mn(isoph)]·2H2O (4). The addition of the N,N-donor ligands 1,10-phenanthroline or 2,2'-bipyridine to 4 leads to the formation of [Mn2 (isoph)2(phen)3)]·4H2O (5), [(Mn(phen)2(H2O)2]2(isoph)2(phen)·12H2O (6) and {[Mn(isoph)(bipy)]4·2.75 biby}n (7), respectively. Molecular structures of 3, 6 and 7 were determined crystallographically. In 3 the phthalate ligand is bound to the manganese via just one of its carboxylate groups in a monodentate mode with the remaining coordination sites filled by four phenanthroline nitrogen and one water oxygen atoms. In 6 the isophthalates are uncoordinated with the octahedral manganese center ligated by two phenanthrolines and two waters. In 7 the Isophthalate ligands act as bridges resulting in a polymeric structure. One of the carboxylate groups is chelating a single manganese with the other binding two metal centres in a bridging bidentate mode. The phthalate and isophthalate complexes, the metal free ligands and a number of simple manganes salts were each tested for their ability, to inhibit the growth of Candida albicans. Only the “metal free” 1,10-phenanthroline and its manganese complexes were found to be active. PMID:18475957

  4. Jack Steinberger: Memories of the PS and of LEP

    NASA Astrophysics Data System (ADS)

    Tsesmelis, Emmanuel

    2012-03-01

    This contribution, a personal recollection by the author, is part of a special issue - CERN's accelerators, experiments and international integration 1959-2009. Guest Editor: Herwig Schopper [Schopper, Herwig. 2011. Editorial. Eur. Phys. J. H 36: 437

  5. Authors' Rejoinder to Respondents (Shulman, Steinberg, & Piquero, 2013)

    ERIC Educational Resources Information Center

    Males, Mike A.; Brown, Elizabeth A.

    2014-01-01

    Respondents, in "A Mistaken Account of the Age-Crime Curve: Response to Males and Brown," dispute our finding that virtually all of the discrepancy in violent crime rates between adolescents/emerging adults versus older adults is explained not by young age per se but by higher poverty levels among the young. Our rejoinder argues that…

  6. The alien replicon: Artificial genetic constructs to direct the synthesis of transmissible self-replicating RNAs: In vivo synthesised heterologous (alien) RNA constructs are capable of initiating self-replication following transmission to the host organism.

    PubMed

    Kochetov, Alex V

    2014-12-01

    Artificial genetic constructs that direct the synthesis of self-replicating RNA molecules are used widely to induce gene silencing, for bioproduction, and for vaccination. Interestingly, one variant of the self-replicon has not been discussed in the literature: namely, transgenic organisms that synthesise alien replicons. For example, plant cells may be easily genetically modified to produce bacteriophages or insect viruses. Alien replicon-producing organisms (ARPOs) may serve as a unique tool for biocontrol or to selectively influence the characteristics of a target organism. The ARPO approach would have to meet strict biosafety criteria, and its practical applications are problematic. However, a discussion on ARPO applicability would be valuable to outline the full set of options available in the bioengineering toolbox. In this paper, RNA replicons for bioengineering are reviewed briefly, and the ARPO approach is discussed.

  7. Steinberg ``AUDIOMAPS" Music Appreciation-Via-Understanding: Special-Relativity + Expectations "Quantum-Theory": a Quantum-ACOUSTO/MUSICO-Dynamics (QA/MD)

    NASA Astrophysics Data System (ADS)

    Steinberg, R.; Siegel, E.

    2010-03-01

    ``AUDIOMAPS'' music enjoyment/appreciation-via-understanding methodology, versus art, music-dynamics evolves, telling a story in (3+1)-dimensions: trails, frames, timbres, + dynamics amplitude vs. music-score time-series (formal-inverse power- spectrum) surprisingly closely parallels (3+1)-dimensional Einstein(1905) special-relativity ``+'' (with its enjoyment- expectations) a manifestation of quantum-theory expectation- values, together a music quantum-ACOUSTO/MUSICO-dynamics (QA/MD). Analysis via Derrida deconstruction enabled Siegel- Baez ``Category-Semantics'' ``FUZZYICS''=``CATEGORYICS (``SON of 'TRIZ") classic Aristotle ``Square-of-Opposition" (SoO) DEduction-logic, irrespective of Boon-Klimontovich versus Voss- Clark[PRL(77)] music power-spectrum analysis sampling- time/duration controversy: part versus whole, shows that ``AUDIOMAPS" QA/MD reigns supreme as THE music appreciation-via- analysis tool for the listener in musicology!!! Connection to Deutsch-Hartmann-Levitin[This is Your Brain on Music,(2006)] brain/mind-barrier brain/mind-music connection is both subtle and compelling and immediate!!!

  8. COMPARISON OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

    EPA Science Inventory

    The Chesapeake Benthic Index of Biotic Integrity (B-IBI) and the EMAP-VP Benthic Index were applied to samples from 239 sites in Chesapeake Bay. The B-IBI weights several community measures equally and uses a simple scoring system while the EMAP-VP Benthic Index uses discriminant...

  9. [Stream health assessment using a benthic-index of biotic integrity in Xitiaoxi Stream, Zhejiang Province, China].

    PubMed

    Li, Qiang; Yang, Lian-fang; Wu, Jing; Wang, Bei-xin

    2007-09-01

    Stream macro-invertebrate assemblages were collected from 64 stream sites in Xitiaoxi Stream, Anji County, Zhejiang Province, China. Thirty-six candidate metrics were evaluated stepwise by distributing range analysis, discriminatory power analysis, and Pearson's correlation analysis. The B-IBI was composed of seven metrics: total taxa, EPT taxa, Coleoptera %, three dominant taxa, Hydropsychidae (Trichoptera) %, filterers %, and Biotic Index (BI). The ratio scoring method was used to transform the value of each metric into a uniform score. A variability coefficient method and an entropy method were used to calculate the weight value of each metric of the B-IBI. The measurement accuracy of the health criteria for the B-IBI derived from all sample data was better than that from only reference data. The entropy method had a higher accuracy (92.9%) than the sum total score method (85.7%) and the variability coefficient method (78.5%) in discriminating stressed and reference sites. The B-IBI health criteria for Xitiaoxi Stream were: B-IBI > 0.69 = healthy, 0.52 - 0.68 = sub-healthy, 0.35-0.51 = good-fair, 0.18-0.34 = fair, B-IBI < 0.17 = poor. The Pearson's correlation analysis between B-IBI and chemical-physical variables showed that the B-IBI strongly corresponded with the habitat quality index (r = 0.62, p < 0.01), water temperature (r = -0.64, p < 0.01), and altitude (r = 0.64, p < 0.01). Our results suggest that the B-IBI is a good indicator in stream health assessment and should be used in water resource management in China.

  10. Predicting biological condition in southern California streams

    USGS Publications Warehouse

    Brown, Larry R.; May, Jason T.; Rehn, Andrew C.; Ode, Peter R.; Waite, Ian R.; Kennen, Jonathan G.

    2012-01-01

    As understanding of the complex relations among environmental stressors and biological responses improves, a logical next step is predictive modeling of biological condition at unsampled sites. We developed a boosted regression tree (BRT) model of biological condition, as measured by a benthic macroinvertebrate index of biotic integrity (BIBI), for streams in urbanized Southern Coastal California. We also developed a multiple linear regression (MLR) model as a benchmark for comparison with the BRT model. The BRT model explained 66% of the variance in B-IBI, identifying watershed population density and combined percentage agricultural and urban land cover in the riparian buffer as the most important predictors of B-IBI, but with watershed mean precipitation and watershed density of manmade channels also important. The MLR model explained 48% of the variance in B-IBI and included watershed population density and combined percentage agricultural and urban land cover in the riparian buffer. For a verification data set, the BRT model correctly classified 75% of impaired sites (B-IBI < 40) and 78% of unimpaired sites (B-IBI = 40). For the same verification data set, the MLR model correctly classified 69% of impaired sites and 87% of unimpaired sites. The BRT model should not be used to predict B-IBI for specific sites; however, the model can be useful for general applications such as identifying and prioritizing regions for monitoring, remediation or preservation, stratifying new bioassessments according to anticipated biological condition, or assessing the potential for change in stream biological condition based on anticipated changes in population density and development in stream buffers.

  11. Electroproduction at very small values of the scaling variable

    NASA Astrophysics Data System (ADS)

    Bjorken, J. D.

    It is a real pleasure to dedicate these remarks to my colleague and friend, Jack Steinberger, whose work with neutrino production of hadrons has so much advanced our knowledge of the interior structure of the nucleon.

  12. Perminalized Alethopteris from the Upper Pennsylvanian of Ohio and Illinois

    SciTech Connect

    Mickle, J.E.; Rothwell, G.W.

    1982-03-01

    Fern-like foliage referable to Alethopteris Steinberg has been discovered in coal balls of Late Pennsylvanian age from near Staubenville, Ohio, and Berryville, Illinois. Pinnule morphology is described from specimens preserved on coal-ball surfaces.

  13. What's In a Proton?

    ScienceCinema

    Brookhaven Lab

    2016-07-12

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  14. What's In a Proton?

    SciTech Connect

    Brookhaven Lab

    2009-07-08

    Physicist Peter Steinberg explains that fundamental particles like protons are themselves made up of still smaller particles called quarks. He discusses how new particles are produced when quarks are liberated from protons...a process that can be observed

  15. Application of the benthic index of biotic integrity to environmental monitoring in Chesapeake Bay.

    PubMed

    Llansó, Roberto J; Dauer, Daniel M; Vølstad, Jon H; Scott, Lisa C

    2003-01-01

    The Chesapeake Bay benthic index of biotic integrity (B-IBI) was developed to assess benthic community health and environmental quality in Chesapeake Bay. The B-IBI provides Chesapeake Bay monitoring programs with a uniform tool with which to characterize bay-wide benthic community condition and assess the health of the Bay. A probability-based design permits unbiased annual estimates of areal degradation within the Chesapeake Bay and its tributaries with quantifiable precision. However, of greatest interest to managers is the identification of problem areas most in need of restoration. Here we apply the B-IBI to benthic data collected in the Bay since 1994 to assess benthic community degradation by Chesapeake Bay Program segment and water depth. We used a new B-IBI classification system that improves the reliability of the estimates of degradation. Estimates were produced for 67 Chesapeake Bay Program segments. Greatest degradation was found in areas that are known to experience hypoxia or show toxic contamination, such as the mesohaline portion of the Potomac River, the Patapsco River, and the Maryland mainstem. Logistic regression models revealed increased probability of degraded benthos with depth for the lower Potomac River, Patapsco River. Nanticoke River, lower York River, and the Maryland mainstem. Our assessment of degradation by segment and water depth provided greater resolution of relative condition than previously available, and helped define the extent of degradation in Chesapeake Bay.

  16. Blog life: Entropy Bound

    NASA Astrophysics Data System (ADS)

    Steinberg, Peter

    2008-06-01

    Who is the blog written by? Peter Steinberg is a nuclear physicist at the Brookhaven National Laboratory in New York, US. He is acting project manager of the PHOBOS experiment, which used Brookhaven's Relativistic Heavy Ion Collider (RHIC) to search for unusual events produced during collisions between gold nuclei. He is also involved with the PHENIX experiment, which seeks to discover a new state of matter known as the quark-gluon plasma. In addition to his own blog Entropy Bound, Steinberg is currently blogging on a website that was set up last year to publicize the involvement of US scientists with the Large Hadron Collider (LHC) at CERN.

  17. Further Thoughts on "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games"

    ERIC Educational Resources Information Center

    Oliveri, María Elena; Khan, Saad

    2014-01-01

    María Oliveri, and Saad Khan write that the article: "How Task Features Impact Evidence from Assessments Embedded in Simulations and Games" provided helpful illustrations regarding the implementation of evidence-centered assessment design (Mislevy & Haertel, 2006; Mislevy, Steinberg, & Almond, 1999) with games and simulations.…

  18. Adolescent Development and the Regulation of Youth Crime

    ERIC Educational Resources Information Center

    Scott, Elizabeth S.; Steinberg, Laurence

    2008-01-01

    Elizabeth Scott and Laurence Steinberg explore the dramatic changes in the law's conception of young offenders between the end of the nineteenth century and the beginning of the twenty-first. At the dawn of the juvenile court era, they note, most youths were tried and punished as if they were adults. Early juvenile court reformers argued strongly…

  19. Parental Characteristics, Ecological Factors, and the Academic Achievement of African American Males

    ERIC Educational Resources Information Center

    Hines, Erik M.; Holcomb-McCoy, Cheryl

    2013-01-01

    Parental characteristics, ecological factors, and the academic achievement of African American male high school students were examined. One hundred fifty-three 11th and 12th grade African American males completed the Parenting Style Index (Steinberg, Lamborn, Darling, Mounts, & Dornbusch, 1994) and a demographic questionnaire. Results…

  20. 410th Brookhaven Lecture

    ScienceCinema

    Peter Steinberg

    2016-07-12

    In a lecture titled "Hotter, Denser, Faster, Smaller...and Nearly Perfect: What's the Matter at RHIC?", Steinberg discusses the basic physics of the quark-gluon plasma and BNL's Relativistic Heavy Ion Collider, with a focus on several intriguing results from RHIC's recently ended PHOBOS experiment.

  1. Literacy Update. Volume 18, Number 2

    ERIC Educational Resources Information Center

    Steinberg, Jon, Ed.

    2009-01-01

    This newsletter, published five times a year, features articles on issues of concern to adult, family, and youth literacy practitioners, as well as recommended resources, announcements, and teaching strategies. This issue contains: (1) Using a License to Drive Improvement: Professional Development in Massachusetts (Jon Steinberg); (2) Building…

  2. Reciprocal Relations between Perceived Parental Knowledge and Adolescent Substance Use and Delinquency: The Moderating Role of Parent-Teen Relationship Quality

    ERIC Educational Resources Information Center

    Abar, Caitlin C.; Jackson, Kristina M.; Wood, Mark

    2014-01-01

    The current study prospectively examined hypothesized short- and long-term reciprocal relations between perceived parental knowledge and adolescent heavy episodic drinking, marijuana use, and delinquency. Using the contextual model of parenting style (Darling & Steinberg, 1993), we examined the extent to which the bidirectional nature of…

  3. The Literacy Issue: Feminist Perspectives on Reading and Writing.

    ERIC Educational Resources Information Center

    Turner, Susan, Ed.

    1990-01-01

    A special issue of a journal devoted to women's literacy education contains the following articles: "Literacy: A Tool for Empowerment of Women?" (Agneta Lind); "Khulumani Makhosikazi: Women and Literacy...Some South African Women Speak" (Dawn Norton, Carola Steinberg); "Tomorrow Will Be Different: A Literacy Course for Women--An Experience from…

  4. Academic Value of Non-Academics: The Case for Keeping Extracurriculars

    ERIC Educational Resources Information Center

    Kronholz, June

    2012-01-01

    A growing body of research says there is a link between afterschool activities and graduating from high school, going to college, and becoming a responsible citizen. Temple University psychologist Laurence Steinberg, whose book, "You and Your Adolescent: The Essential Guide for Ages 10-25," discusses afterschool activities. He suggested two more…

  5. Selling Out (In) Sport Management: Practically Evaluating the State of the American (Sporting) Union

    ERIC Educational Resources Information Center

    Wiest, Amber; King-White, Ryan

    2013-01-01

    When teaching in Sport Management programs professors are often forced to respond to the actions and teachings of professionals in the field. According to the study by Kincheloe & Steinberg many of these normalized and, indeed celebrated, behaviors are actions that are part and parcel of the "recovery movement" which (re)inscribe new…

  6. King of Cool

    ERIC Educational Resources Information Center

    Freado, Mark; Van Bockern, Steve

    2010-01-01

    Many teenagers get involved in criminal activity. This tendency is so pervasive that psychologist Terrie Moffitt, one of the world's leading experts on the development of antisocial behavior, has described delinquent behavior as a normal part of teenager life (Scott & Steinberg, 2008). Adults, even those in the justice system, are often at a loss…

  7. The Development of Reproductive Strategy in Females: Early Maternal Harshness [right arrow] Earlier Menarche [right arrow] Increased Sexual Risk Taking

    ERIC Educational Resources Information Center

    Belsky, Jay; Steinberg, Laurence; Houts, Renate M.; Halpern-Felsher, Bonnie L.

    2010-01-01

    To test a proposition central to J. Belsky, L. Steinberg, and P. Draper's (1991) evolutionary theory of socialization--that pubertal maturation plays a role in linking early rearing experience with adolescent sexual risk taking (i.e., frequency of sexual behavior) and, perhaps, other risk taking (e.g., alcohol, drugs, delinquency)--the authors…

  8. Designing across Ages: Multi-Agent-Based Models and Learning Electricity

    ERIC Educational Resources Information Center

    Sengupta, Pratim

    2009-01-01

    Electricity is regarded as one of the most challenging topics for students at all levels--middle school--college (Cohen, Eylon, & Ganiel, 1983; Belcher & Olbert, 2003; Eylon & Ganiel, 1990; Steinberg et al., 1985). Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta & Chi,…

  9. Beyond Authoritarianism: A Cultural Perspective on Asian American Parenting Practices.

    ERIC Educational Resources Information Center

    Chao, Ruth K.

    A study was conducted to determine Asian American conceptualizations of parenting, focusing on socialization goals, parenting style, and parenting practices related to schooling, aspects of parental influences discussed by D. Darling and L. Steinberg (1993). It was suggested that the standard conceptualizations of parenting style, those of D.…

  10. Relationships between Adolescent Sexual Outcomes and Exposure to Sex in Media: Robustness to Propensity-Based Analysis

    ERIC Educational Resources Information Center

    Collins, Rebecca L.; Martino, Steven C.; Elliott, Marc N.; Miu, Angela

    2011-01-01

    Adolescent sexual health is a substantial problem in the United States, and two recent studies have linked adolescent sexual behavior and/or outcomes to youths' exposure to sex in the media. Both studies had longitudinal survey designs and used covariate-adjusted regression analysis. Steinberg and Monahan (2011) reanalyzed data from one of these…

  11. In praise of weakness

    NASA Astrophysics Data System (ADS)

    Steinberg, Aephraim; Feizpour, Amir; Rozema; Mahler; Hayat

    2013-03-01

    Quantum physics is being transformed by a radical new conceptual and experimental approach known as weak measurement that can do everything from tackling basic quantum mysteries to mapping the trajectories of photons in a Young's double-slit experiment. Aephraim Steinberg, Amir Feizpour, Lee Rozema, Dylan Mahler and Alex Hayat unveil the power of this new technique.

  12. 75 FR 28849 - Review of the Designation of Ansar al-Islam (aka Ansar Al-Sunnah and Other Aliases) as a Foreign...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-24

    ... Immigration and Nationality Act, as amended (8 U.S.C. 1189(a)(4)(C)) (``INA''), and in consultation with the... security of the United States does not warrant a revocation of the designation. Therefore, I hereby... published in the Federal Register. Dated: May 6, 2010. James B. Steinberg, Deputy Secretary of...

  13. Diabetes - foot ulcers

    MedlinePlus

    ... 33. Kim PJ, Steinberg JS. Complications of the diabetic foot. Endocrinol Metab Clin N Am. 2013;42:833-847. PMID: 24286952 www.ncbi.nlm.nih.gov/pubmed/24286952 . Read More Diabetes Diabetes and nerve damage Leg or foot amputation Type 1 diabetes Type 2 diabetes Patient Instructions Diabetes and ...

  14. Will There Always be an English?

    ERIC Educational Resources Information Center

    Henry, George H.

    1972-01-01

    A critical review of English Education Today," edited by L.S. Josephs and E. R. Steinberg, which is more a review of English curriculum, the directions, philosophies, and problems in English instruction, with emphasis on the need to think critically and innovatively. (JB)

  15. Autonomy, Educational Plans, and Self-Esteem in Institution-Reared and Home-Reared Teenagers in Estonia

    ERIC Educational Resources Information Center

    Tulviste, Tiia

    2011-01-01

    The study examines autonomy, self-esteem, and educational plans for the future of 109 institution-reared and 106 home-reared teenagers (15-19 years). Teenagers were asked to complete the Teen Timetable Scale (Feldman & Rosenthal), two Emotional Autonomy Scales (Steinberg & Silverberg), the Rosenberg Self-Esteem Scale, and answer questions about…

  16. Literacy Update. Volume 18, Number 4

    ERIC Educational Resources Information Center

    Steinberg, Jon, Ed.

    2009-01-01

    This newsletter, published five times a year, features articles on issues of concern to adult, family, and youth literacy practitioners, as well as recommended resources, announcements, and teaching strategies. This issue includes: (1) Career Pathways for High School Dropouts: A National Survey (Jon Steinberg); (2) Work (Elyse Barbell); (3) Peer…

  17. Annual Review of Applied Linguistics, Volume 5, 1984.

    ERIC Educational Resources Information Center

    Kaplan, Robert B., Ed.

    This volume of the annual review includes introductory remarks by G. Richard Tucker and these papers: "Current Issues in Bilingualism: An Update of Directions in Research" (Braj B. Kachru); "Psycholinguistics: Application. The Writing System as a Native Language for the Deaf" (Danny D. Steinberg); "Sociolinguistics: Theory" (Monica Heller);…

  18. Some funny things about error diffusion

    NASA Astrophysics Data System (ADS)

    Eschbach, Reiner

    2003-12-01

    Error diffusion has been a topic of study for many years and a large number of improvements have been made to the original form as it was proposed by Floyd and Steinberg. This paper will show some lesser known behaviors and modifica-tions to the algorithm along with some surprising or perplexing results.

  19. Acts of God - The Unnatural History of Natural Disaster in America

    NASA Astrophysics Data System (ADS)

    Steinberg, Ted

    2003-05-01

    With the exception of the 9/11 disaster, the top ten most costly catastrophes in U.S. history have all been natural disasters--five of them hurricanes--and all have occurred since 1989. Why this tremendous plague on our homes? In Acts of God , environmental historian Ted Steinberg explains that much of the death and destruction has been well within the realm of human control. Steinberg exposes the fallacy of seeing such calamities as simply random events. Beginning with the 1886 Charleston and 1906 San Francisco earthquakes, and continuing to the present, Steinberg explores the unnatural history of natural calamity, the decisions of business leaders and government officials that have paved the way for the greater losses of life and property, especially among those least able to withstand such blows--America's poor, elderly, and minorities. Seeing nature or God as the primary culprit, Steinberg argues, has helped to hide the fact that some Americans are better protected from the violence of nature than their counterparts lower down the socioeconomic ladder. Sure to provoke discussion, Acts of God is a call to action that must be heard. "A sobering lesson in humanity's vulnerability to extreme climatic events, especially the impoverished farmer and the urban poor."--The Los Angeles Times Book Review

  20. An Exploratory Study of Mathematics Engagement of Secondary Students

    ERIC Educational Resources Information Center

    Brown, Tracy Thomas

    2008-01-01

    A large proportion of American students are not psychologically connected or engaged to what is occurring in their classes; in addition, they fail to take school seriously, have lost interest in school, and do not value or seek out success (Steinberg, Brown, & Dornbusch, 1996). In addition, the relationship in a mathematics classroom between…

  1. Joe L. Kincheloe: Genies and Wishes--A Review of "Key Works in Critical Pedagogy"

    ERIC Educational Resources Information Center

    Ali-Khan, Carolyne; Siry, Christina

    2012-01-01

    We review "Key Works in Critical Pedagogy: Joe L. Kincheloe" edited by Kecia Hayes, Shirley R. Steinberg and Kenneth Tobin, which gathers the seminal works of Joe. L. Kincheloe and pairs them with contemporary scholars who respond to and push forward Kincheloe's work. The chapters of "Key Works in Critical Pedagogy" are arranged to begin with…

  2. 410th Brookhaven Lecture

    SciTech Connect

    Peter Steinberg

    2005-12-21

    In a lecture titled "Hotter, Denser, Faster, Smaller...and Nearly Perfect: What's the Matter at RHIC?", Steinberg discusses the basic physics of the quark-gluon plasma and BNL's Relativistic Heavy Ion Collider, with a focus on several intriguing results from RHIC's recently ended PHOBOS experiment.

  3. Premature Dissemination of Advice Undermines Our Credibility as Scientists: Reply to Brown (2011) and to Collins, Martino, and Elliott (2011)

    ERIC Educational Resources Information Center

    Steinberg, Laurence; Monahan, Kathryn C.

    2011-01-01

    In our reanalysis of data from the Brown et al. (2006) study (Steinberg & Monahan, 2011), we found no support for the contention that adolescents' exposure to sexy media content hastens their sexual debut. In their critiques of our article, Brown (2011) and Collins, Martino, and Elliott (2011) both questioned some of the decisions we made with…

  4. The MA in Writing at DePaul University

    ERIC Educational Resources Information Center

    Clary-Lemon, Jennifer; Vandenberg, Peter

    2006-01-01

    While discussion about the nature and function of the PhD has flourished for years in the broad context of English studies (Bérubé; Lunsford et al.; Nelson) and for more than a decade now in rhetoric and composition (Brown, Meyer, and Enos; North; Young and Steinberg), the Master's degree has attracted scant attention. No doubt this traces to a…

  5. Revisiting the Impact of Part-Time Work on Adolescent Adjustment: Distinguishing between Selection and Socialization Using Propensity Score Matching

    ERIC Educational Resources Information Center

    Monahan, Kathryn C.; Lee, Joanna M.; Steinberg, Laurence

    2011-01-01

    The impact of part-time employment on adolescent functioning remains unclear because most studies fail to adequately control for differential selection into the workplace. The present study reanalyzes data from L. Steinberg, S. Fegley, and S. M. Dornbusch (1993) using multiple imputation, which minimizes bias in effect size estimation, and 2 types…

  6. 19 Urban Questions: Teaching in the City. Second Edition. Counterpoints: Studies in Postmodern Theory of Education, Vol. 215

    ERIC Educational Resources Information Center

    Steinberg, Shirley R., Ed

    2010-01-01

    The second edition of "19 Urban Questions: Teaching in the City" adds new questions to those in the original volume. Continuing the developing conversation in urban education, the book is provocative in style and rich in detail. Emphasizing the complexity of urban education, Shirley R. Steinberg and the authors ask direct questions about what…

  7. Review of Pearson Test of English Academic: Building an Assessment Use Argument

    ERIC Educational Resources Information Center

    Wang, Huan; Choi, Ikkyu; Schmidgall, Jonathan; Bachman, Lyle F.

    2012-01-01

    This review departs from current practice in reviewing tests in that it employs an "argument-based approach" to test validation to guide the review (e.g. Bachman, 2005; Kane, 2006; Mislevy, Steinberg, & Almond, 2002). Specifically, it follows an approach to test development and use that Bachman and Palmer (2010) call the process of "assessment…

  8. A Test of a Counting Model for Chiasma Interference

    PubMed Central

    Foss, E. J.; Stahl, F. W.

    1995-01-01

    According to the model of FOSS, LANDE, STAHL and STEINBERG, chiasma interference is a reflection of the requirement for crossovers to be separated by an organism-specific number of potential conversion events without associated crossovers. This model predicts that tetrads with close double crossovers should be enriched for conversion events that themselves are not associated with crossing over. We tested this prediction in Saccharomyces cerevisiae and found it to be unfulfilled. PMID:7768433

  9. [Research progress on using index of biological integrity to assess aquatic ecosystem health].

    PubMed

    Liao, Jing-Qiu; Huang, Yi

    2013-01-01

    Index of biological integrity (IBI) is one of the most important and popular tools in assessing aquatic ecosystem health. This paper reviewed the selection of indicator species for IBI, its construction process, and its applications in assessing aquatic ecosystem health, summarized the commonly used candidate biological parameter indices of fish-index of biological integrity (F-IBI), benthos-index of biological integrity (B-IBI), and periphyton-index of biological integrity (P-IBI), and pointed out the feasibility and necessity of using microbe-index of biological integrity (M-IBI) to assess the health of aquatic ecosystem.

  10. Infrared reflection and Raman scattering on Ba 1-xRb xBiO 3

    NASA Astrophysics Data System (ADS)

    Inoue, A.; Iyo, A.; Oiji, Y.; Tanaka, Y.; Tokumoto, M.; Uwe, H.; Sakudo, T.

    1991-12-01

    Measurements of infrared (IR) reflectivity and Raman scattering have been performed on Ba 1-xRb xBiO 3. The oscillator strength of the Bi-Bi stretching mode decreases with increasing Rb concentration, while the frequency change is small. The phonons detected by the Raman scattering experiment have the same frequencies as the LO phonons, although the system has the center of symmetry in the average structure. It is suggested that the coherence length of the charge density wave shorter than the incident laser wavelength 5145Å gets shorter with increasing the Rb concentration.

  11. Deposition studies of lithium and bismuth at tungsten microelectrodes in LiCl:KCl eutectic

    NASA Astrophysics Data System (ADS)

    Carlin, Richard T.; Osteryoung, Robert A.

    1989-05-01

    Tungsten microelectrodes (diam = 25 microns) have been used to study the deposition and stripping behavior of Li/Li(+) and Bi/Bi(3+) in the LiCl:KCl eutectic at 400 C. The Li deposition current can be simulated assuming the growth of a single hemisphere of liquid metal on the microelectrode. High stripping current densities were observed and quantitated using standard electrochemical equipment. An inverted microscope assembly was employed for in situ observation of the Li/Li(+) deposition and stripping processes at the microelectrode. A precipitate appears to form in the melt surrounding the electrode during Li deposition.

  12. [Catalytic properties of enzymes from Erwinia carotovora involved in transamination of phenylpyruvate].

    PubMed

    Paloian, A M; Stepanian, L A; Dadaian, S A; Ambartsumian, A A; Alebian, G P; Sagian, A S

    2013-01-01

    Km for L-phenylalanine, L-glutamic acid, L-aspartic acid, and the corresponding keto acids were calculated, as well as Vmax, was measured for the following pairs of substrates: L-phenylalanine-2-ketoglutarate, L-phenylalanine-oxaloacetate, L-glutamic acid-phenylpyruvate, and L-aspartic acid-phenylpyruvate for aminotransferases PATI, PAT2, and PAT3 from Erwinia carotovora catalyzing transamination of phenylpyruvate. The ping-pong bi-bi mechanism was shown for the studied aminotransferases. The substrate inhibition (Ks) of PAT3 with 2-ketoglutarate and oxaloacetate was 10.23 +/- 3.20 and 3.73 +/- 1.99 mM, respectively.

  13. Assessing ecological integrity for impaired waters decisions in Chesapeake Bay, USA.

    PubMed

    Llansó, Roberto J; Dauer, Daniel M; Vølstad, Jon H

    2009-01-01

    To meet the requirements of the Clean Water Act, the States of Maryland and Virginia are using benthic biological criteria for identifying impaired waters in Chesapeake Bay and reporting their overall condition. The Chesapeake Bay benthic index of biotic integrity (B-IBI) is the basis for these biological criteria. Working together with the states and the US Environmental Protection Agency, we developed a method for impairment decisions based on the B-IBI. The impaired waters decision approach combines multiple benthic habitat-dependent indices in a Bay segment (equivalent to water bodies in the European Water Framework Directive) with a statistical test of impairment. The method takes into consideration uncertainty in reference conditions, sampling variability, multiple habitats, and sample size. We applied this method to 1430 probability-based benthic samples in 85 Chesapeake Bay segments. Twenty-two segments were considered impaired for benthic community condition. The final decision for each segment considers benthic condition in combination with key stressors such as dissolved oxygen and toxic contaminants. PMID:19084878

  14. Effects of urbanization on benthic macroinvertebrate assemblages in contrasting environmental settings: Boston, Massachusetts; Birmingham, Alabama; and Salt Lake City, Utah

    USGS Publications Warehouse

    Cuffney, T.F.; Zappia, H.; Giddings, E.M.P.; Coles, J.F.

    2005-01-01

    Responses of invertebrate assemblages along gradients of urban intensity were examined in three metropolitan areas with contrasting climates and topography (Boston, Massachusetts; Birmingham, Alabama; Salt Lake City, Utah). Urban gradients were defined using an urban intensity index (UII) derived from basin-scale population, infrastructure, land-use, land-cover, and socioeconomic characteristics. Responses based on assemblage metrics, indices of biotic integrity (B-IBI), and ordinations were readily detected in all three urban areas and many responses could be accurately predicted simply using regional UIIs. Responses to UII were linear and did not indicate any initial resistance to urbanization. Richness metrics were better indicators of urbanization than were density metrics. Metrics that were good indicators were specific to each study except for a richness-based tolerance metric (TOLr) and one B-IBI. Tolerances to urbanization were derived for 205 taxa. These tolerances differed among studies and with published tolerance values, but provided similar characterizations of site conditions. Basin-scale land-use changes were the most important variables for explaining invertebrate responses to urbanization. Some chemical and instream physical habitat variables were important in individual studies, but not among studies. Optimizing the study design to detect basin-scale effects may have reduced the ability to detect local-scale effects. ?? 2005 by the American Fisheries Society.

  15. Applying Benthic Index of Biotic Integrity in a soft bottom ecosystem in North of the Persian Gulf.

    PubMed

    Doustshenas, B; Savari, A; Nabavi, S M B; Kochanian, P; Sadrinasab, M

    2009-06-15

    In this study, the Chesapeake Bay Benthic Index of Biotic Integrity (B-IBI) was selected in an attempt to describe ecological health of soft bottom channels (Khowr-e Musa) in North of the Persian Gulf. Most of study area was found to be in degraded or severely degraded conditions. B-IBI scores were ranged between 1 and 3.86. Comparison ofmacrobenthos abundance and organic content between two developmental periods showed significant difference (p < 0.05). After the establishment and development of petrochemical industries, the abundance of macrofauna decreased (809 to 239 individuals m(-2)) and organic content increased leading to organic enrichment (15.3 to 22.4%). Three new sources of organic matter were found to be important namely industrial waste, sewage and mangrove litter. After 1999 about 6 millions Avicennia marina tree were planted near petrochemical zone in the area. Study area changed rapidly in the last decade and region is under severely anthropogenic impacts. The present study showed that Khowr-e Musa is under both natural stress and anthropogenic impacts and two main impacts could be attributed to the organic enrichment and to the dredging. Choice of suitable management plans and metric controls could help to the salvage of the largest tidal channel complex in Persian Gulf.

  16. Configuration dependence of band-gap narrowing and localization in dilute GaAs1 -xBix alloys

    NASA Astrophysics Data System (ADS)

    Bannow, Lars C.; Rubel, Oleg; Badescu, Stefan C.; Rosenow, Phil; Hader, Jörg; Moloney, Jerome V.; Tonner, Ralf; Koch, Stephan W.

    2016-05-01

    Anion substitution with bismuth (Bi) in III-V semiconductors is an effective method for experimental engineering of the band gap Eg at low Bi concentrations (≤2 % ), in particular in gallium arsenide (GaAs). The inverse Bi-concentration dependence of Eg has been found to be linear at low concentrations x and dominated by a valence band defect level anticrossing between As and Bi occupied p levels. Predictive models for the valence band hybridization require a first-principle understanding which can be obtained by density functional theory with the main challenges being the proper description of Eg and the spin-orbit coupling. By using an efficient method to include these effects, it is shown here that at high concentrations Eg is modified mainly by a Bi-Bi p orbital interaction and by the large Bi atom-induced strain. In particular, we find that at high concentrations, the Bi-Bi interactions depend strongly on model periodic cluster configurations, which are not captured by tight-binding models. Averaging over various configurations supports the defect level broadening picture. This points to the role of different atomic configurations obtained by varying the experimental growth conditions in engineering arsenide band gaps, in particular for telecommunication laser technology.

  17. Assessing ecological integrity for impaired waters decisions in Chesapeake Bay, USA.

    PubMed

    Llansó, Roberto J; Dauer, Daniel M; Vølstad, Jon H

    2009-01-01

    To meet the requirements of the Clean Water Act, the States of Maryland and Virginia are using benthic biological criteria for identifying impaired waters in Chesapeake Bay and reporting their overall condition. The Chesapeake Bay benthic index of biotic integrity (B-IBI) is the basis for these biological criteria. Working together with the states and the US Environmental Protection Agency, we developed a method for impairment decisions based on the B-IBI. The impaired waters decision approach combines multiple benthic habitat-dependent indices in a Bay segment (equivalent to water bodies in the European Water Framework Directive) with a statistical test of impairment. The method takes into consideration uncertainty in reference conditions, sampling variability, multiple habitats, and sample size. We applied this method to 1430 probability-based benthic samples in 85 Chesapeake Bay segments. Twenty-two segments were considered impaired for benthic community condition. The final decision for each segment considers benthic condition in combination with key stressors such as dissolved oxygen and toxic contaminants.

  18. First to second sound conversion through scattering by quantum vorticity in superfluid Helium

    NASA Astrophysics Data System (ADS)

    Coste, Christophe; Lund, Fernando

    1997-03-01

    Following earlier results(F. Lund and V. Steinberg, Phys. Rev. Lett.) 75, 1102 (1995) on second sound to second sound scattering by quantized vortices in superfluid Helium, we have computed the scattering of first and second sound waves by quantum vorticity. Exact expressions are derived for first sound to second sound, as well as second sound to first sound, conversions. Calculations are performed using two-fluid hydrodynamics and a first Born approximation. The reason for the mode conversion lies in the nonlinear coupling between the longitudinal (sound) and transverse (vortical) hydrodynamic modes.

  19. The data acquisition system for ALEPH

    SciTech Connect

    Videau, I.

    1985-08-01

    The ALEPH Collaboration is formed by 27 institutes from nine countries plus CERN and counts about 300 physicists and engineers. Its spokesman is Jack Steinberger (CERN). The ALEPH Detector is being built by the collaboration now, in order to operate at LEP beginning of 1989. LEP is the Large Electron Positron Collider built at CERN. Its initial energy will be of 90GeV (Phase I) and its nominal luminosity 10/sup 32/cm/sup -1/s/sup -1/. It is foreseen to increase the energy of the machine up to about 200 GeV during Phase II.

  20. From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

    ScienceCinema

    None

    2016-07-12

    The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

  1. Sensitivity analysis of seismic hazard for Western Liguria (North Western Italy): A first attempt towards the understanding and quantification of hazard uncertainty

    NASA Astrophysics Data System (ADS)

    Barani, Simone; Spallarossa, Daniele; Bazzurro, Paolo; Eva, Claudio

    2007-05-01

    The use of logic trees in probabilistic seismic hazard analyses often involves a large number of branches that reflect the uncertainty in the selection of different models and in the selection of the parameter values of each model. The sensitivity analysis, as proposed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796-817], is an efficient tool that allows the construction of logic trees focusing attention on the parameters that have greater impact on the hazard. In this paper the sensitivity analysis is performed in order to identify the parameters that have the largest influence on the Western Liguria (North Western Italy) seismic hazard. The analysis is conducted for six strategic sites following the multi-parameter approach developed by Rabinowitz and Steinberg [Rabinowitz, N., Steinberg, D.M., 1991. Seismic hazard sensitivity analysis: a multi-parameter approach. Bull. Seismol. Soc. Am. 81, 796-817] and accounts for both mean hazard values and hazard values corresponding to different percentiles (e.g., 16%-ile and 84%-ile). The results are assessed in terms of the expected PGA with a 10% probability of exceedance in 50 years for rock conditions and account for both the contribution from specific source zones using the Cornell approach [Cornell, C.A., 1968. Engineering seismic risk analysis. Bull. Seismol. Soc. Am. 58, 1583-1606] and the spatially smoothed seismicity [Frankel, A., 1995. Mapping seismic hazard in the Central and Eastern United States. Seismol. Res. Lett. 66, 8-21]. The influence of different procedures for calculating seismic hazard, seismic catalogues (epicentral parameters), source zone models, frequency-magnitude parameters, maximum earthquake magnitude values and attenuation relationships is considered. As a result, the sensitivity analysis allows us to identify the parameters with higher influence on the hazard. Only these

  2. From the Proton Synchroton to the Large Hadron Collider - 50 Years of Nobel Memories in High-Energy Physics

    SciTech Connect

    2009-12-07

    The seminars will be held in the Main Auditorium with transmission to : Council Chamber, IT Auditorium, Prévessin BE Auditorium , Kjell Johnssen Auditorium in Building 30, Room 40-S2-A01, and via webcast. Confirmed Speakers include: Prof. Jack Steinberger, Dr. Guenther Plass, Prof. Emilio Picasso, Dr. Steve Myers, Prof. Carlo Rubbia, Prof. Burton Richter, Dr. Lyndon Evans, Prof. Rolf-Dieter Heuer, Prof. Leon Lederman, Prof. Jim Cronin, Prof. Sheldon Glashow, Prof. Jerome Friedman, Prof. Frank Wilczek, Prof. Martinus Veltman, Prof. Gerardus 't Hooft, Prof. David Gross, Prof. Samuel Ting, Prof. Steven Weinberg (via teleconference) --- Contact: Directorate.Office@cern.ch

  3. COMMITTEES: SQM2004 Organising and International Advisory Committees

    NASA Astrophysics Data System (ADS)

    2005-06-01

    Organising Committee Jean Cleymans (Chairman) Zeblon Vilakazi Roger Fearick Peter Steinberg Rory Adams Bruce Becker Sarah Blyth Gareth de Vaux Heather Gray Mark Horner Nawahl Razak Artur Szostak Spencer Wheaton International Advisory Committee Federico Antinori Tim Hallman John Harris Tetsuo Hatsuda Ulrich Heinz Huan Z Huang Sonja Kabana Volker Koch Rob Lacey Jes Madsen Yasuo Miake Maurizio Morando Berndt Mueller Grazyna Odyniec Helmut Oeschler Apostolos Panagiotou Josef Pochodzalla Johann Rafelski Karel Safarik Jack Sandweiss Jürgen Schaffner-Bielich Georges Stephans Horst Stoecker Herbert Stroebele Thomas Ullrich Orlando Villalobos-Baillie Bill Zajc Joseph Zimanyi

  4. Kernel weights optimization for error diffusion halftoning method

    NASA Astrophysics Data System (ADS)

    Fedoseev, Victor

    2015-02-01

    This paper describes a study to find the best error diffusion kernel for digital halftoning under various restrictions on the number of non-zero kernel coefficients and their set of values. As an objective measure of quality, WSNR was used. The problem of multidimensional optimization was solved numerically using several well-known algorithms: Nelder- Mead, BFGS, and others. The study found a kernel function that provides a quality gain of about 5% in comparison with the best of the commonly used kernel introduced by Floyd and Steinberg. Other kernels obtained allow to significantly reduce the computational complexity of the halftoning process without reducing its quality.

  5. Streamflow, water-quality, and biological data for three tributaries to Lake Houston near Houston, Texas, 2002-04

    USGS Publications Warehouse

    East, Jeffery W.; Sneck-Fahrer, Debra A.

    2005-01-01

    -insect taxa (17) were collected at site on Caney Creek near New Caney. The benthic-macroinvertebrate index of biotic integrity (B-IBI) scores (averages of samples) for the three upstream Lake Creek sites indicate intermediate aquatic life use, and the B-IBI score for the most downstream site indicates high aquatic life use. B-IBI scores for the Peach Creek sites, in downstream order, are exceptional and high; and scores for the Caney Creek sites, in downstream order, are high and intermediate.

  6. A structural analysis of Bi/Si(1 0 0) 2 × n surfaces by ICISS

    NASA Astrophysics Data System (ADS)

    Oishi, N.; Saitoh, N.; Naitoh, M.; Nishigaki, S.; Shoji, F.; Nakanishi, S.; Umezawa, K.

    2003-05-01

    We have investigated the structure of Bi-adsorbed Si(1 0 0) 2× n surfaces with various Bi coverages by low-energy electron diffraction (LEED) and impact-collision ion scattering spectroscopy (ICISS). Intensities of He + scattered from Bi and Si atoms were measured as a function of ion incidence angle. Bi-Bi interatomic distances for the toplayer including Bi-dimers were estimated by the shadow-cone technique. Bi-signal peaks appeared even at considerably large angles of incidence, which are attributed to collisions with Bi atoms in sub-surface layers. Bi adsorption is not completed at a mono-layer level, but continues to form multiple layers, fitted in the Si lattice, in the Frank-van der Merwe growth mode.

  7. Efficient Charge Separation between Bi and Bi2 MoO6 for Photoelectrochemical Properties.

    PubMed

    Ma, Ying; Jia, Yulong; Wang, Lina; Yang, Min; Bi, Yingpu; Qi, Yanxing

    2016-04-18

    Herein, porous Bi/Bi2 MoO6 nanoparticles have been prepared by a facile in-situ reduction approach. Moreover, the morphology and Bi content of product could be controlled by varying the reaction time. By controlled fabrication, the desired porous Bi2 MoO6 nanostructure with incorporation of Bi was obtained and exhibited high photoelectric and photocatalytic activity. In particular, the samples yield a photocurrent density of 320 μA cm(-2) , which is 3.2 times that of the pure Bi2 MoO6 nanosheet (100 μA cm(-2) ) under the same conditions. UV/Vis diffuse reflectance spectroscopy analysis confirmed the surface plasmon resonance in the as-prepared porous nanoparticles. The improved photoelectric properties could be the synergistic effect of the porous structure with large surface area and effective electron-hole separations between Bi and Bi2 MoO6 .

  8. Enhanced biocatalytic activity of immobilized Pseudomonas cepacia lipase under sonicated condition.

    PubMed

    Badgujar, Kirtikumar C; Pai, Poorna A; Bhanage, Bhalchandra M

    2016-02-01

    The present work reports the use of biocatalyst and ultrasound for greener synthesis of cinnamyl propionate. The lipase Pseudomonas cepacia was immobilized on a copolymer of hydroxypropyl methyl cellulose and polyvinyl alcohol. This biocatalyst was u sed for ultrasound-assisted synthesis of cinnamyl propionate with the detailed optimization of various reaction parameters. Besides this, protocol was extended to synthesize various industrially important propionate esters. In addition to this, different enzyme-kinetic parameters such as r max and K m(vinyl propionate), K m(cinnamyl alcohol) and K i(cinnamyl alcohol) were studied which presented ordered bi-bi mechanism with an inhibition by cinnamyl alcohol. The developed biocatalyst demonstrated enhancement in catalytic activity and recyclability up to five recycles. Moreover, the biocatalyst was tested to investigate the effects of sonication via various characterization techniques such as scanning electron microscopy, thermogravimetry, and water content analysis. PMID:26590966

  9. Cross-Species Application of SNP Chips is Not Suitable for Identifying Runs of Homozygosity.

    PubMed

    Shafer, Aaron B A; Miller, Joshua M; Kardos, Marty

    2016-03-01

    Cross-species application of single-nucleotide polymorphism (SNP) chips is a valid, relatively cost-effective alternative to the high-throughput sequencing methods generally required to obtain a genome-wide sampling of polymorphisms. Kharzinova et al. (2015) examined the applicability of SNP chips developed in domestic bovids (cattle and sheep) to a semi-wild cervid (reindeer). The ancestors of bovids and cervids diverged between 20 and 30 million years ago (Hassanin and Douzery 2003; Bibi et al. 2013). Empirical work has shown that for a SNP chip developed in a bovid and applied to a cervid species, approximately 50% genotype success with 1% of the loci being polymorphic is expected (Miller et al. 2012). The genotyping of Kharzinova et al. (2015) follows this pattern; however, these data are not appropriate for identifying runs of homozygosity (ROH) and can be problematic for estimating linkage disequilibrium (LD) and we caution readers in this regard.

  10. Characterization of a membrane-associated cytidine diphosphate-diacylglycerol-dependent phosphatidylserine synthase in bacilli.

    PubMed Central

    Dutt, A; Dowhan, W

    1981-01-01

    The synthesis of phosphatidylserine in two gram-positive aerobic bacteria has been partially characterized. We have located a cytidine 5'-diphospho-diacylglycerol:L-serine O-phosphatidyltransferase (phosphatidylserine synthase) activity in the membrane fraction of Bacillus licheniformis and Bacillus subtilis. The activity was demonstrated to be membrane associated by differential centrifugation, sucrose gradient centrifugation, and detergent solubilization. The direct involvement of cytidine 5'-diphospho-diacylglycerol in the reaction was demonstrated by the conversion of the liponucleotide phosphatidyl moiety to phosphatidylserine. This activity is dependent on divalent metal ion (manganese being optimal) and is stimulated by nonionic detergent and its product phosphatidylserine. Based on studies with various combinations of products and substrates, the reaction appears to follow a sequential BiBi kinetic mechanism. PMID:6267011

  11. Efficient Charge Separation between Bi and Bi2 MoO6 for Photoelectrochemical Properties.

    PubMed

    Ma, Ying; Jia, Yulong; Wang, Lina; Yang, Min; Bi, Yingpu; Qi, Yanxing

    2016-04-18

    Herein, porous Bi/Bi2 MoO6 nanoparticles have been prepared by a facile in-situ reduction approach. Moreover, the morphology and Bi content of product could be controlled by varying the reaction time. By controlled fabrication, the desired porous Bi2 MoO6 nanostructure with incorporation of Bi was obtained and exhibited high photoelectric and photocatalytic activity. In particular, the samples yield a photocurrent density of 320 μA cm(-2) , which is 3.2 times that of the pure Bi2 MoO6 nanosheet (100 μA cm(-2) ) under the same conditions. UV/Vis diffuse reflectance spectroscopy analysis confirmed the surface plasmon resonance in the as-prepared porous nanoparticles. The improved photoelectric properties could be the synergistic effect of the porous structure with large surface area and effective electron-hole separations between Bi and Bi2 MoO6 . PMID:26868192

  12. Cross-Species Application of SNP Chips is Not Suitable for Identifying Runs of Homozygosity.

    PubMed

    Shafer, Aaron B A; Miller, Joshua M; Kardos, Marty

    2016-03-01

    Cross-species application of single-nucleotide polymorphism (SNP) chips is a valid, relatively cost-effective alternative to the high-throughput sequencing methods generally required to obtain a genome-wide sampling of polymorphisms. Kharzinova et al. (2015) examined the applicability of SNP chips developed in domestic bovids (cattle and sheep) to a semi-wild cervid (reindeer). The ancestors of bovids and cervids diverged between 20 and 30 million years ago (Hassanin and Douzery 2003; Bibi et al. 2013). Empirical work has shown that for a SNP chip developed in a bovid and applied to a cervid species, approximately 50% genotype success with 1% of the loci being polymorphic is expected (Miller et al. 2012). The genotyping of Kharzinova et al. (2015) follows this pattern; however, these data are not appropriate for identifying runs of homozygosity (ROH) and can be problematic for estimating linkage disequilibrium (LD) and we caution readers in this regard. PMID:26774056

  13. Phosphonate analogues of dinucleotides as substrates for DNA-dependent RNA polymerase from Escherichia coli in primed abortive initiation reaction.

    PubMed

    Cvekl, A; Horská, K; Sebesta, K; Rosenberg, I; Holý, A

    1989-02-01

    Dinucleotides (3'-5')-ApU and UpA and their 3'-O-phosphonylmethyl and 5'-O-phosphonylmethyl analogues were studied as substrates in the primed abortive synthesis catalysed by Escherichia coli DNA-dependent RNA polymerase on poly[d(A-T)] template. All phosphonate analogues of dinucleotides containing the anomalous sugar-phosphate backbone are substrates for the holoenzyme as verified by RNase A and RNase T2 digestion of the trinucleotide analogues obtained. The finding that phosphonate dinucleotides act as primers for transcription indicates that steric requirements at the initiation site are not as specific as previously supposed. Analysis of kinetic constants of ordered bibi reaction Kia, KmA, KmB and Vmax suggests that the instability of short RNA-DNA hybrids contributes to the abortive release of trinucleotides formed.

  14. Impacts of land disturbance on aquatic ecosystem health: quantifying the cascade of events.

    PubMed

    Sciera, Katherine L; Smink, John A; Morse, John C; Post, Christopher J; Pike, Jeremy W; English, William R; Karanfil, Tanju; Hayes, John C; Schlautman, Mark A; Klaine, Stephen J

    2008-10-01

    The impacts of land disturbance on streams have been studied extensively, but a quantitative mechanism of stream degradation is still lacking. Small changes in land use result in changes in physical and chemical characteristics in the stream, which significantly alter biotic integrity. The objective of this study was to quantify the mechanisms of aquatic ecosystem degradation in streams impacted by watershed urbanization. By quantifying the development level and the changes in the physical parameters of receiving streams, the effects of land use change can be illustrated in a conceptual model and evaluated using a traditional ecological risk assessment framework. Three 1st-order streams draining catchments undergoing varying stages of land development were examined in the upper Piedmont physiographic province of South Carolina, U.S.A. A disturbance index was developed to quantify the changes in land use on a monthly basis. This normalized disturbance index (NDI) was quantitatively linked to an increase in the percentage of impervious cover, stormwater runoff, storm-event total suspended solid (TSS) concentrations, and the North Carolina biotic index (NCBI). The NDI was inversely related to a decline in habitat, median bed-sediment particle size, and benthic index of biotic integrity (BIBI). Unlike the percentage of impervious cover, the NDI facilitated the development of strategies for multiple scales of regulation. Predictive multivariate regressions were developed for storm-event TSS concentrations, the BIBI, and the NCBI. These regressions can be used to develop improved regulations for the effects of development and can lead to better implementation of best management practices, improved monitoring of land use change, and more sustainable development.

  15. Antiphase Boundaries in the Turbostratically Disordered Misfit Compound (BiSe)(1+δ)NbSe2.

    PubMed

    Mitchson, Gavin; Falmbigl, Matthias; Ditto, Jeffrey; Johnson, David C

    2015-11-01

    (BiSe)(1+δ)NbSe2 ferecrystals were synthesized in order to determine whether structural modulation in BiSe layers, characterized by periodic antiphase boundaries and Bi-Bi bonding, occurs. Specular X-ray diffraction revealed the formation of the desired compound with a c-axis lattice parameter of 1.21 nm from precursors with a range of initial compositions and initial periodicities. In-plane X-ray diffraction scans could be indexed as hk0 reflections of the constituents, with a rectangular basal BiSe lattice and a trigonal basal NbSe2 lattice. Electron micrographs showed extensive turbostratic disorder in the samples and the presence of periodic antiphase boundaries (approximately 1.5 nm periodicity) in BiSe layers oriented with the [110] direction parallel to the zone axis of the microscope. This indicates that the structural modulation in the BiSe layers is not due to coherency strain resulting from commensurate in-plane lattices. Electrical transport measurements indicate that holes are the dominant charge carrying species, that there is a weak decrease in resistivity as temperature decreases, and that minimal charge transfer occurs from the BiSe to NbSe2 layers. This is consistent with the lack of charge transfer from the BiX to the TX2 layers reported in misfit layer compounds where antiphase boundaries were observed. This suggests that electronic considerations, i.e., localization of electrons in the Bi-Bi pairs at the antiphase boundaries, play a dominant role in stabilizing the structural modulation. PMID:26465820

  16. Emotional autonomy redux: revisiting Ryan and Lynch.

    PubMed

    Lamborn, S D; Steinberg, L

    1993-04-01

    Ryan and Lynch have suggested that emotional autonomy in adolescence, at least as indexed by Steinberg and Silverberg's Emotional Autonomy Scale, is associated with poor family functioning and might therefore be better conceptualized as detachment. In the present study, we contrast adjustment scores among adolescents who differ in both emotional autonomy and perceptions of support in their relationship with their parents. Several thousand adolescents aged 14 through 18 completed Steinberg and Silverberg's emotional autonomy measure, a measure designed to assess the provision of support in the parent-adolescent relationship, and a number of standardized measures of adjustment. Adolescents high in emotional autonomy but low in relationship support show problematic adjustment profiles, consistent with Ryan and Lynch's interpretation of the measure as an index of detachment. Although adolescents high in both emotional autonomy and relationship support report more internal distress and behavior problems than some adolescents, they score higher on measures of psychosocial development and academic competence than their peers. Emotional autonomy in the context of a supportive adolescent-parent relationship may carry some developmental advantages as well as some deleterious consequences suggested by Ryan and Lynch.

  17. Too close and too rigid: applying the Circumplex Model of Family Systems to first-generation family firms.

    PubMed

    Michael-Tsabari, Nava; Lavee, Yoav

    2012-06-01

    Despite growing research interest in family businesses, little is known about the characteristics of the families engaging in them. The present paper uses Olson's (Journal of Psychotherapy & the Family, 1988, 4(12), 7-49; Journal of Family Therapy, 2000, 22, 144-167) Circumplex Model of Marital and Family Systems to look at first-generation family firms. We describe existing typologies of family businesses and discuss similarities between the characteristics of first-generation family firms and the rigidly enmeshed family type described in the Circumplex Model. The Steinberg family business (Gibbon & Hadekel (1990) Steinberg: The breakup of a family empire. ON, Canada: MacMillan) serves to illustrate the difficulties of rigidly enmeshed first-generation family firms. Implications for understanding troubled family businesses are discussed together with guidelines for the assessment of a family business in crisis and for intervention: enhancing open communication; allowing for more flexible leadership style, roles, and rules; and maintaining a balance between togetherness and separateness. PMID:22765328

  18. Too close and too rigid: applying the Circumplex Model of Family Systems to first-generation family firms.

    PubMed

    Michael-Tsabari, Nava; Lavee, Yoav

    2012-06-01

    Despite growing research interest in family businesses, little is known about the characteristics of the families engaging in them. The present paper uses Olson's (Journal of Psychotherapy & the Family, 1988, 4(12), 7-49; Journal of Family Therapy, 2000, 22, 144-167) Circumplex Model of Marital and Family Systems to look at first-generation family firms. We describe existing typologies of family businesses and discuss similarities between the characteristics of first-generation family firms and the rigidly enmeshed family type described in the Circumplex Model. The Steinberg family business (Gibbon & Hadekel (1990) Steinberg: The breakup of a family empire. ON, Canada: MacMillan) serves to illustrate the difficulties of rigidly enmeshed first-generation family firms. Implications for understanding troubled family businesses are discussed together with guidelines for the assessment of a family business in crisis and for intervention: enhancing open communication; allowing for more flexible leadership style, roles, and rules; and maintaining a balance between togetherness and separateness.

  19. Charge fractionalization in nonchiral Luttinger systems

    NASA Astrophysics Data System (ADS)

    Le Hur, Karyn; Halperin, Bertrand I.; Yacoby, Amir

    2008-12-01

    One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1 - f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

  20. Charge fractionalization in nonchiral Luttinger systems

    SciTech Connect

    Le Hur, Karyn Halperin, Bertrand I.; Yacoby, Amir

    2008-12-15

    One-dimensional metals, such as quantum wires or carbon nanotubes, can carry charge in arbitrary units, smaller or larger than a single electron charge. However, according to Luttinger theory, which describes the low-energy excitations of such systems, when a single electron is injected by tunneling into the middle of such a wire, it will tend to break up into separate charge pulses, moving in opposite directions, which carry definite fractions f and (1-f) of the electron charge, determined by a parameter g that measures the strength of charge interactions in the wire. (The injected electron will also produce a spin excitation, which will travel at a different velocity than the charge excitations.) Observing charge fractionalization physics in an experiment is a challenge in those (nonchiral) low-dimensional systems which are adiabatically coupled to Fermi liquid leads. We theoretically discuss a first important step towards the observation of charge fractionalization in quantum wires based on momentum-resolved tunneling and multi-terminal geometries, and explain the recent experimental results of Steinberg et al. [H. Steinberg, G. Barak, A. Yacoby, L.N. Pfeiffer, K.W. West, B.I. Halperin, K. Le Hur, Nature Physics 4 (2008) 116].

  1. Sheep heart RNA stimulates myofibril formation and beating in cardiac mutant axolotl hearts in organ culture.

    PubMed

    Zhang, Chi; LaFrance, Sherrie M; Lemanski, Sharon L; Huang, Xupei; Dube, Dipak K; Lemanski, Larry F

    2003-05-01

    In the Mexican axolotl, Ambystoma mexicanum, recessive mutant gene c, when homozygous, results in a failure of the heart to form sarcomeric myofibrils and contract normally. Previous studies have shown that purified RNA from normal anterior endoderm or from medium conditioned with anterior endoderm/pre-cardiac mesoderm has the capacity to rescue mutant hearts in organ culture. In the present study, RNA extracted from adult sheep heart was tested for its capacity to promote differentiation in the mutant axolotl hearts. Mutant hearts cultured in the presence of the sheep heart RNA in Steinberg's solution for 48 h displayed rhythmic contractions. Ultrastructural studies showed that the rescued mutant axolotl ventricular myocardial cells contained myofibrils of normal morphology. Mutant hearts cultured in Steinberg's solution alone did not beat throughout their lengths and myofibrils were not observable in the ventricles. Confocal microscopy confirmed the increase of Tropomyosin expression and formation of myofibrils in mutant hearts treated by sheep heart RNA. Thus, sheep heart RNA promotes myofibrillogenesis and the development of contractile function in embryonic cardiac mutant axolotl hearts. PMID:12684761

  2. Metal-Metal Bonding in Uranium-Group 10 Complexes.

    PubMed

    Hlina, Johann A; Pankhurst, James R; Kaltsoyannis, Nikolas; Arnold, Polly L

    2016-03-16

    Heterobimetallic complexes containing short uranium-group 10 metal bonds have been prepared from monometallic IU(IV)(OAr(P)-κ(2)O,P)3 (2) {[Ar(P)O](-) = 2-tert-butyl-4-methyl-6-(diphenylphosphino)phenolate}. The U-M bond in IU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3M(0), M = Ni (3-Ni), Pd (3-Pd), and Pt (3-Pt), has been investigated by experimental and DFT computational methods. Comparisons of 3-Ni with two further U-Ni complexes XU(IV)(μ-OAr(P)-1κ(1)O,2κ(1)P)3Ni(0), X = Me3SiO (4) and F (5), was also possible via iodide substitution. All complexes were characterized by variable-temperature NMR spectroscopy, electrochemistry, and single crystal X-ray diffraction. The U-M bonds are significantly shorter than any other crystallographically characterized d-f-block bimetallic, even though the ligand flexes to allow a variable U-M separation. Excellent agreement is found between the experimental and computed structures for 3-Ni and 3-Pd. Natural population analysis and natural localized molecular orbital (NLMO) compositions indicate that U employs both 5f and 6d orbitals in covalent bonding to a significant extent. Quantum theory of atoms-in-molecules analysis reveals U-M bond critical point properties typical of metallic bonding and a larger delocalization index (bond order) for the less polar U-Ni bond than U-Pd. Electrochemical studies agree with the computational analyses and the X-ray structural data for the U-X adducts 3-Ni, 4, and 5. The data show a trend in uranium-metal bond strength that decreases from 3-Ni down to 3-Pt and suggest that exchanging the iodide for a fluoride strengthens the metal-metal bond. Despite short U-TM (transition metal) distances, four other computational approaches also suggest low U-TM bond orders, reflecting highly transition metal localized valence NLMOs. These are more so for 3-Pd than 3-Ni, consistent with slightly larger U-TM bond orders in the latter. Computational studies of the model systems (PH3)3MU(OH)3I (M = Ni, Pd) reveal

  3. Adolescent development and the regulation of youth crime.

    PubMed

    Scott, Elizabeth S; Steinberg, Laurence

    2008-01-01

    Elizabeth Scott and Laurence Steinberg explore the dramatic changes in the law's conception of young offenders between the end of the nineteenth century and the beginning of the twenty-first. At the dawn of the juvenile court era, they note, most youths were tried and punished as if they were adults. Early juvenile court reformers argued strongly against such a view, believing that the justice system should offer young offenders treatment that would cure them of their antisocial ways. That rehabilitative model of juvenile justice held sway until a sharp upswing in youth violence at the end of the twentieth century led both public opinion and public policy toward a view that youths should be held to the same standard of criminal accountability as adults. Lawmakers seemed to lose sight of developmental differences between adolescents and adults. But Scott and Steinberg note that lawmakers and the public appear now to be rethinking their views once more. A justice system that operates on the principle of "adult time for adult crime" now seems to many to take too little note of age and immaturity in calculating criminal punishment. In 2005 the United States Supreme Court abolished the juvenile death penalty as cruel and unusual punishment, emphasizing that the immaturity of adolescents made them less culpable than adult criminals. In addition, state legislatures recently have repealed or moderated some of the punitive laws they recently enacted. Meanwhile, observe the authors, public anger has abated and attitudes toward young offenders have softened somewhat. In response to these changes, Scott and Steinberg argue that it is appropriate to reexamine juvenile justice policy and to devise a new model for the twenty-first century. In this article, they propose what they call a developmental model. They observe that substantial new scientific evidence about adolescence and criminal activity by adolescents provides the building blocks for a new legal regime superior to

  4. Adolescent development and the regulation of youth crime.

    PubMed

    Scott, Elizabeth S; Steinberg, Laurence

    2008-01-01

    Elizabeth Scott and Laurence Steinberg explore the dramatic changes in the law's conception of young offenders between the end of the nineteenth century and the beginning of the twenty-first. At the dawn of the juvenile court era, they note, most youths were tried and punished as if they were adults. Early juvenile court reformers argued strongly against such a view, believing that the justice system should offer young offenders treatment that would cure them of their antisocial ways. That rehabilitative model of juvenile justice held sway until a sharp upswing in youth violence at the end of the twentieth century led both public opinion and public policy toward a view that youths should be held to the same standard of criminal accountability as adults. Lawmakers seemed to lose sight of developmental differences between adolescents and adults. But Scott and Steinberg note that lawmakers and the public appear now to be rethinking their views once more. A justice system that operates on the principle of "adult time for adult crime" now seems to many to take too little note of age and immaturity in calculating criminal punishment. In 2005 the United States Supreme Court abolished the juvenile death penalty as cruel and unusual punishment, emphasizing that the immaturity of adolescents made them less culpable than adult criminals. In addition, state legislatures recently have repealed or moderated some of the punitive laws they recently enacted. Meanwhile, observe the authors, public anger has abated and attitudes toward young offenders have softened somewhat. In response to these changes, Scott and Steinberg argue that it is appropriate to reexamine juvenile justice policy and to devise a new model for the twenty-first century. In this article, they propose what they call a developmental model. They observe that substantial new scientific evidence about adolescence and criminal activity by adolescents provides the building blocks for a new legal regime superior to

  5. Role of temperature differences between surface and deep reservoirs in geyser dynamics: Insights from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Munoz Saez, C.; Shteinberg, A.; Manga, M.

    2012-12-01

    Geysers are springs that produce episodic eruptions of steam, liquid water, and non-condensable gases. Their eruptions are smaller and more frequent than other eruptive processes (volcanic, or hydrothermal eruptions), providing a feasible natural laboratory to understand eruptive processes. Moreover, the fluid dynamics of geysers probe processes that operate in more inaccessible geothermal systems. We developed laboratory experiments to understand the role of the surface temperature on geyser dynamics. For the experimental model, we followed to model developed by Steinberg et al. (1982), which produced periodic eruptions. In this experimental model, eruptions are driven by the ascent of bubbles. The "explosive" ejection of fluid occurs when bubbles reach the surface of the conduit. The eruption of a bubble influences the nucleation on the next bubble through the pressure changes in the conduit. The experimental apparatus consists of a bottom reservoir and a vertical conduit that opens into an upper chamber that collects and returns liquid to the reservoir after the eruption. The reservoir was heated from below at a constant rate. The fluid used was Freon 113, which has a boiling point of 48°C. Temperature in the upper part of the tube was varied between 0° to 20°C. As we increase the temperature difference between the reservoir and the surface of the tube we find (1) that vapor contained in the upper part of bubble tends condense, impeding its ascent to the surface, (2) an increase the number of bubbles generated during the time between eruptions, (3) that the volume of vapor in the tube remain almost constant during the period between eruptions (4) an increase the frequency of eruptions, (5) an increase the escape speed of fluid from the tube, and (6) an increase in Reynolds number. We interpret these results in terms of heat transport by the rising bubbles. Bubbles transport the heat as latent heat of evaporation. Because the amount of heating was the same in

  6. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    NASA Astrophysics Data System (ADS)

    Henry de Frahan, M. T.; Belof, J. L.; Cavallo, R. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; Johnsen, E.; LeBlanc, M. M.

    2015-06-01

    We present a set of high explosive driven Rayleigh-Taylor strength experiments for beryllium to produce data to distinguish predictions by various strength models. Design simulations using existing strength model parameterizations from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, suggests growth consistent with little material strength. We focus mostly on efforts to simulate the data using published strength models as well as the more recent RING relaxation model developed at VNIIEF. The results of the strength experiments indicate weak influence of strength in mitigating the growth with the RING model coming closest to predicting the material behavior. Finally, we present shock and ramp-loading recovery experiments.

  7. Dynamic Strength of Tantalum under impact

    NASA Astrophysics Data System (ADS)

    Glam, Benny; Werdiger, Meir; Pistinner, Shlomi

    2013-06-01

    Plane impact experiments of double shock and shock-rarefaction in Tantalum were carried out in a gas gun. VISAR diagnostics has been implemented to measure the particle velocity and the free surface velocity. The VISAR information was utilized to study the dynamic strength of Tantalum under compression and tension. The pressure in the experiments was below 35 GPa. In this pressure range the dominant mechanism is expected to be dislocation motion. A 1-d hydrodynamic code was used in order to match various strength models. As expected, both the Johnson-Cook and the Guinan-Steinberg models do not reproduce the experimental results. Therefore in this paper we compare the Zerilli-Armstrong model which has been recently calibrated at strain rate of 6 x 103 s-1 using the split Kowalsky-Hopkinson bar to our experimental results at strain rate of 106 s-1.

  8. On the dynamic strength of 304l stainless steel under impact

    NASA Astrophysics Data System (ADS)

    Werdiger, Meir; Glam, Benny; Bakshi, Lior; Moshe, Ella; Horovitz, Yossef; Pistinner, Shlomi Levi

    2012-03-01

    Uniaxial strain plane impact (300-1700 m/s), loading and reloading experiments carried out on SS304L are reported. The aim of these experiments was to measure the material strength properties under shock compression. Most of the experiments reported here show a viscous type elastic precursor. The experimental results are compared to numerical simulations performed using a 1D code. The input physics to the simulations are the Steinberg equation of state and Johnson-Cook strength model. This model has been previously calibrated under uniaxial stress conditions in the rangee ɛ =1-5×103 s-1. Our experiments extended the data into the regione ɛ =105 -106 s-1. In spite of this extrapolation, there is a general agreement between simulations and experiments. However, differences in some details still exist.

  9. The prejudiced personality, racism, and anti-Semitism: the PR scale forty years later.

    PubMed

    Dunbar, E

    1995-10-01

    The relationship of prejudiced personality traits with racism and anti-Semitism was examined with 150 Asian American and White university students. The Prejudice (PR) scale, composed of 32 items from the Minnesota Multiphasic Personality Inventory, was administered along with the McConahay racism scale and the Selznick and Steinberg Anti-Semitism scale. Results indicated that for Whites, the PR scale was significantly correlated with old-fashioned and modern racism and anti-Semitism, replicating Gough's 1951 study (Gough, 1951b) with the PR scale. However, no such relationship was observed for the Asian American group. This suggests that personality traits of prejudicial attitudes may be relatively stable for Whites but may not be related to outgroup bias for other racial or ethnic groups.

  10. Dynamic material properties of refractory materials: Tantalum and tantalum/tungsten alloys

    SciTech Connect

    Furnish, M.D.; Chhabildas, L.C.; Lassila, D.H.; Steinberg, D.J.

    1995-08-01

    We have made a careful set of impact wave-profile measurements (16 profiles) on tantalum and tantalum-tungsten alloys at relatively low stresses (to 15 GPa). Alloys used were Ta{sub 97.5}W{sub 2.5} and Ta{sub 90}W{sub 10} (wt. %) with oxygen contents of 30--70 ppM. Information available from these experiments includes Hugoniot, elastic limits, loading fates, spall strength, unloading paths, reshock structure and specimen thickness effects. Hugoniot and spall properties are illustrated, and are consistent with expectations from earlier work. Modeling the tests with the Steinberg-Lund rate-dependent material model provides for an excellent match of the shape of the plastic wave, although the release wave is not well modeled. There is also a discrepancy between experiments and calculations regarding the relative timing of the elastic and plastic waves that may be due to texture effects.

  11. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    SciTech Connect

    Henry de Frahan, M. T. Johnsen, E.; Belof, J. L.; Cavallo, R. M.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; LeBlanc, M. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.

    2015-06-14

    We present a set of high explosive driven Rayleigh-Taylor strength experiments for beryllium to produce data to distinguish predictions by various strength models. Design simulations using existing strength model parameterizations from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, suggests growth consistent with little material strength. We focus mostly on efforts to simulate the data using published strength models as well as the more recent RING relaxation model developed at VNIIEF. The results of the strength experiments indicate weak influence of strength in mitigating the growth with the RING model coming closest to predicting the material behavior. Finally, we present shock and ramp-loading recovery experiments.

  12. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: Numerical Simulation of Wave Propagation and Phase Transition of Tin under Shock-Wave Loading

    NASA Astrophysics Data System (ADS)

    Song, Hai-Feng; Liu, Hai-Feng; Zhang, Guang-Cai; Zhao, Yan-Hong

    2009-06-01

    We undertake a numerical simulation of shock experiments on tin reported in the literature, by using a multiphase equation of state (MEOS) and a multiphase Steinberg Guinan (MSG) constitutive model for tin in the β, γ and liquid phases. In the MSG model, the Bauschinger effect is considered to better describe the unloading behavior. The phase diagram and Hugoniot of tin are calculated by MEOS, and they agree well with the experimental data. Combined with the MEOS and MSG models, hydrodynamic computer simulations are successful in reproducing the measured velocity profile of the shock wave experiment. Moreover, by analyzing the mass fraction contour as well as stress and temperature profiles of each phase for tin, we further discuss the complex behavior of tin under shock-wave loading.

  13. Comment on ``Einstein-Podolsky-Rosen state for space-time variables in a two-photon interference experiment''

    NASA Astrophysics Data System (ADS)

    Kwiat, P. G.; Steinberg, A. M.; Chiao, R. Y.

    1993-11-01

    A recent article by Shih, Sergienko, and Rubin [Phys. Rev. A 47, 1288 (1993)] reports a two-photon interference effect in which fringes with a visibility of 59% were observed; for an ideal system, quantum mechanics predicts perfect visibility interference. In explanation of this discrepancy, the authors conclude that the reduced visibility is due to ``nonperfect phase matching of the down-conversion,'' the parent process of the correlated photon pairs. They imply that the nonperfect phase matching stems from the finite size of their down-conversion crystal. We argue that the crystal length was not a limiting factor in their measurement, citing three similar experiments which achieved higher visibilities [Kwiat, Steinberg, and Chiao, Phys. Rev. A 47, R2472 (1993); Brendel, Mohler, and Martienssen, Phys. Rev. Lett. 66, 1142 (1991); Europhys. Lett. 20, 575 (1992)].

  14. Experimental and numerical investigations of beryllium strength models using the Rayleigh-Taylor instability

    SciTech Connect

    Henry de Frahan, M. T.; Belof, J. L.; Cavallo, R. M.; Raevsky, V. A.; Ignatova, O. N.; Lebedev, A.; Ancheta, D. S.; El-dasher, B. S.; Florando, J. N.; Gallegos, G. F.; Johnsen, E.; LeBlanc, M. M.

    2015-06-14

    A recent collaboration between LLNL and VNIIEF has produced a set of high explosive driven Rayleigh-Taylor strength data for beryllium. Design simulations using legacy strength models from Steinberg-Lund and Preston-Tonks-Wallace (PTW) suggested an optimal design that would delineate between not just different strength models, but different parameters sets of the PTW model. Application of the models to the post-shot results, however, shows close to classical growth. We characterize the material properties of the beryllium tested in the experiments. We also discuss recent efforts to simulate the data using the legacy strength models as well as the more recent RING relaxation model developed at VNIIEF. Finally, we present shock and ramp-loading recovery experiments conducted as part of the collaboration.

  15. Modeling of Uranium Alloy Response in Plane Impact and Reverse Ballistic Experiments

    NASA Astrophysics Data System (ADS)

    Herrmann, B.; Landau, A.; Shvarts, D.; Favorsky, V.; Zaretsky, E.

    2002-07-01

    The dynamic behavior of a solution heat-treated, water-quenched and aged U-0.75wt%Ti alloy was studied in planar (disk-on-disk) and reverse ballistic (disk-on-rod) impact experiments performed with a 25 mm light-gas gun. The impact velocity ranged from 100 to 500 m/sec. The impacted samples were softly recovered for further metallographic examination. The VISAR records of the sample free surface velocity, obtained in planar impact experiments, were simulated with 1-D hydrocode for calibrating the parameters of modified Steinberg-Cochran-Guinan (SCG) constitutive equation of the alloy. The same SCG equation was employed in 2-D AUTODYN simulation of the alloy response in the reverse ballistic experiments, with VISAR monitoring of the lateral sample surface velocity. Varying the parameters of the strain-dependent failure model allows relating the features of the recorded velocity profiles with the results of the examination of the damaged samples.

  16. U-0.75Ti and Ti-6Al-4V in Planar and Ballistic Impact Experiments

    NASA Astrophysics Data System (ADS)

    Herrmann, B.; Venkert, A.; Favorsky, V.; Shvarts, D.; Zaretsky, E.

    2004-07-01

    The response of U and Ti alloys has been studied in planar and ballistic impact experiments performed with a 25 mm light-gas gun. Free surface velocities were monitored by VISAR. The velocity profiles and the damage maps were simulated using 2D AUTODYN™ finite differences code. A modified Steinberg-Cochran-Guinan constitutive model was calibrated by simulating planar impact experiments. Bauschinger effect and a single-parameter spall model were added to describe the unloading and the tensile paths. The ballistic experiments were simulated by using the calibrated model. Softly recovered samples revealed different degrees of spall fracture (planar impact) and of adiabatic shear bands (ballistic experiments). The results demonstrate a possibility to combine experimental and numerical techniques, VISAR and AUTODYN, to calibrate constitutive models of solids in a wide range of shock-induced strain.

  17. CACNA1H missense mutations associated with amyotrophic lateral sclerosis alter Cav3.2 T-type calcium channel activity and reticular thalamic neuron firing.

    PubMed

    Rzhepetskyy, Yuriy; Lazniewska, Joanna; Blesneac, Iulia; Pamphlett, Roger; Weiss, Norbert

    2016-11-01

    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. In a recent study by Steinberg and colleagues, 2 recessive missense mutations were identified in the Cav3.2 T-type calcium channel gene (CACNA1H), in a family with an affected proband (early onset, long duration ALS) and 2 unaffected parents. We have introduced and functionally characterized these mutations using transiently expressed human Cav3.2 channels in tsA-201 cells. Both of these mutations produced mild but significant changes on T-type channel activity that are consistent with a loss of channel function. Computer modeling in thalamic reticular neurons suggested that these mutations result in decreased neuronal excitability of thalamic structures. Taken together, these findings implicate CACNA1H as a susceptibility gene in amyotrophic lateral sclerosis.

  18. MESOSCALE SIMULATIONS OF POWDER COMPACTION

    SciTech Connect

    Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-28

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  19. Mesoscale Simulations of Powder Compaction

    NASA Astrophysics Data System (ADS)

    Lomov, Ilya.; Fujino, Don; Antoun, Tarabay; Liu, Benjamin

    2009-12-01

    Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

  20. Using the SCID-D to assess dissociative identity disorder in adolescents: three case studies.

    PubMed

    Steinberg, M; Steinberg, A

    1995-01-01

    The authors report on the diagnostic assessment of dissociative identity disorder in three adolescents using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D; Steinberg, 1993b), a semistructured instrument for the diagnosis and assessment of dissociative symptoms and disorders. Although the SCID-D has received good-to-excellent ratings for reliability and validity in the adult population, these three cases are the first reports of the results of its administration to younger patients. Comparison of the three adolescent SCID-D interviews with findings in adults indicates that the profiles of the five dissociative symptoms measured by the SCID-D are virtually identical in adolescents and adults. The authors conclude with suggestions for future research regarding dissociative symptomatology in adolescents and outcome studies.

  1. Congressional liaison task force - a briefing of the October 1994 meeting

    SciTech Connect

    1994-12-31

    As the US Senate overturned roadblocks attempting-unsuccessfully-to halt passage of the elementary and secondary education reauthorization legislation representatives from several federal agencies and laboratories addressed Congressional Liaison Task Force (CLTF) participants October 12th. They spoke about their commitment, programs, and accomplishments toward the nation`s science knowledge, particularly at the precollege level. Marjorie S. Steinberg legislative assistant to bill cosponsor Sen. Jeff Bingaman (DNM), and Gary Allen, Triangle Coalition director of Governmental affairs, spoke about education legislation and specifically about the Technology for Education Act that was on the Senate floor for a vote in October and now is law. Bruce A. Fuchs talked about the National Institute of Health`s (NIH) work in science literacy and education. The National Aeronautics and Space Administration`s (NASA) Frank C. Owens and Eddie Anderson contributed to this report.

  2. Bidirectional associations between bedtime parenting and infant sleep: Parenting quality, parenting practices, and their interaction.

    PubMed

    Philbrook, Lauren E; Teti, Douglas M

    2016-06-01

    In keeping with transactional conceptualizations of infant sleep development (Sadeh, Tikotzky, & Scher, 2010), the present study was an examination of longitudinal, bidirectional linkages between bedtime parenting (through direct observations of parenting practices and quality) and infant sleep across the first 6 months postpartum. In doing so, we also drew from Darling and Steinberg's (1993) conceptual model to examine parenting quality as a moderator of linkages between specific bedtime practices and infant sleep. Multilevel model analyses revealed that the strongest increases in infant nighttime sleep across the first 6 months occurred among infants of mothers who engaged in low levels of nursing at bedtime. Within-person linkages between mothers' emotional availability (EA) at bedtime, infant distress, and infant sleep were found, such that at time points when mothers were more emotionally available, infants were less distressed and slept more throughout the night. Several moderating effects of maternal EA on linkages between parenting practices and infant sleep were obtained that were consistent with predictions from Darling and Steinberg (1993). Higher maternal EA in combination with less close contact at bedtime was associated with more infant sleep across the night on average, and higher EA in combination with fewer arousing bedtime activities predicted more rapid increases in infant sleep with age. Finally, there was evidence of infant-driven effects, as higher infant nighttime distress predicted lower EA at subsequent time points. Results showcased the complex, reciprocal interplay between parents and infants in the development of infant sleep patterns and parenting behavior during the first 6 months postpartum. (PsycINFO Database Record PMID:27010601

  3. Aluminum Rayleigh Taylor Strength Measurements and Calculations

    SciTech Connect

    Lindquist, M J; Cavallo, R M; Lorenz, K T; Pollaine, S M; Remington, B A; Raevsky, V A

    2007-01-10

    A traditional approach to the study of material strength has been revitalized at the Russian Federal Nuclear Center (VNIIEF). Rayleigh Taylor strength experiments have long been utilized to measure the material response of metals at high pressure and strain rates. A modulated (sinusoidal or sawtooth perturbation) surface is shocklessly (quasi-isentropically) accelerated by a high explosive (HE) driver, and radiography is used to measure the perturbation amplitude as a function of time. The Aluminum T-6061 targets are designed with several sets of two-dimensional sawtooth perturbations machined on the loading surface. The HE driver was designed to reach peak pressures in the range of 200 to 300 kbar and strain rates in the range of 10{sup 4} - 10{sup 6} s{sup -1}. The standard constitutive strength models, Steinberg-Guinan (SG) [1], Steinberg-Lund (SL) [2], Preston-Tonks-Wallace (PTW) [3], Johnson-Cooke (JC) [4], and Mechanical Threshold Stress (MTS) [5], have been calibrated by traditional techniques: (Hopkinson-Bar, Taylor impact, flyer plate/shock-driven experiments). The VNIIEF experimental series accesses a strain rate regime not attainable using traditional methods. We have performed a detailed numerical study with a two-dimensional Arbitrary Lagrangian Eulerian hydrodynamics computer code containing several constitutive strength models to predict the perturbation growth. Results show that the capabilities of the computational methodology predict the amplitude growth to within 5 percent of the measured data, thus validating both the code and the strength models under the given conditions and setting the stage for credible future design work using different materials.

  4. Linking Hydrologic Alteration to Biological Impairment in Urbanizing Streams of the Puget Lowland, Washington, USA1

    PubMed Central

    DeGasperi, Curtis L; Berge, Hans B; Whiting, Kelly R; Burkey, Jeff J; Cassin, Jan L; Fuerstenberg, Robert R

    2009-01-01

    We used a retrospective approach to identify hydrologic metrics with the greatest potential for ecological relevance for use as resource management tools (i.e., hydrologic indicators) in rapidly urbanizing basins of the Puget Lowland. We proposed four criteria for identifying useful hydrologic indicators: (1) sensitive to urbanization consistent with expected hydrologic response, (2) demonstrate statistically significant trends in urbanizing basins (and not in undeveloped basins), (3) be correlated with measures of biological response to urbanization, and (4) be relatively insensitive to potentially confounding variables like basin area. Data utilized in the analysis included gauged flow and benthic macroinvertebrate data collected at 16 locations in 11 King County stream basins. Fifteen hydrologic metrics were calculated from daily average flow data and the Pacific Northwest Benthic Index of Biological Integrity (B-IBI) was used to represent the gradient of response of stream macroinvertebrates to urbanization. Urbanization was represented by percent Total Impervious Area (%TIA) and percent urban land cover (%Urban). We found eight hydrologic metrics that were significantly correlated with B-IBI scores (Low Pulse Count and Duration; High Pulse Count, Duration, and Range; Flow Reversals, TQmean, and R-B Index). Although there appeared to be a great deal of redundancy among these metrics with respect to their response to urbanization, only two of the metrics tested – High Pulse Count and High Pulse Range – best met all four criteria we established for selecting hydrologic indicators. The increase in these high pulse metrics with respect to urbanization is the result of an increase in winter high pulses and the occurrence of high pulse events during summer (increasing the frequency and range of high pulses), when practically none would have occurred prior to development. We performed an initial evaluation of the usefulness of our hydrologic indicators by

  5. Lipase catalyzed esterification of glycidol in organic solvents

    SciTech Connect

    Martins, J.F.; Nunes da Ponte, M.; Barreiros, S. . Centro de Tecnologia Quimica e Biologica)

    1993-08-05

    The authors studied the resolution of racemic glycidol through esterification with butyric acid catalyzed by porcine pancreatic lipase in organic media. A screening of seven solvents (log P values between 0.49 and 3.0, P being the n-octanol-water partition coefficient of the solvent) showed that neither log P nor the logarithm of the molar solubility of water in the solvent provides good correlations between enantioselectivity and the properties of the organic media. Chloroform was one of the best solvents as regards the enantiometic purity (e.p.) of the ester produced. In this solvent, the optimum temperature for the reaction was determined to be 35C. The enzyme exhibited maximum activity at a water content of 13 [plus minus] 2% (w/w). The enantiomeric purity obtained was 83 [plus minus] 2% of (S)-glycidol butyrate and did not depend on the alcohol concentration or the enzyme water content for values of these parameters up to 200 mM and 25% (w/w), respectively. The reaction was found to follow a BiBi mechanism.

  6. Lipase catalyzed esterification of glycidol in organic solvents.

    PubMed

    Martins, J F; Da Ponte, M N; Barreiros, S

    1993-08-01

    We studied the resolution of racemic glycidol through esterification with butyric acid catalyzed by porcine pancreatic lipase in organic media. A screening of seven solvents (log P values between 0.49 and 3.0, P being the n-octanol-water partition coefficient of the solvent) showed that neither log P nor the logarithm of the molar solubility of water in the solvent provides good correlations between enantioselectivity and the properties of the organic media. Chloroform was one of the best solvents as regards the enantiomeric purity (e. p.) of the ester produced. In this solvent, the optimum temperature for the reaction was determined to be 35 degrees C. The enzyme exhibited maximum activity at a water content of 13 +/- 2% (w/w). The enantiomeric purity obtained was 83 +/- 2% of (S)-glycidyl butyrate and did not depend on the alcohol concentration or the enzyme water content for values of these parameters up to 200 mM and 25% (w/w), respectively. The reaction was found to follow a BiBi mechanism.

  7. Catalase-like activity of bovine met-hemoglobin: interaction with the pseudo-catalytic peroxidation of anthracene traces in aqueous medium.

    PubMed

    Paco, Laveille; Galarneau, Anne; Drone, Jullien; Fajula, François; Bailly, Carole; Pulvin, Sylviane; Thomas, Daniel

    2009-10-01

    Hemoglobin is a member of the hemoprotein superfamily whose main role is to transport O(2) in vertebrate organisms. It has two known promiscuous enzymatic activities, peroxidase and oxygenase. Here we show for the first time that bovine hemoglobin also presents a catalase-like activity characterized by a V(max )of 344 microM/min, a K(M )of 24 mM and a k(cat) equal to 115/min. For high anthracene and hemoglobin concentrations and low hydrogen peroxide concentrations, this activity inhibits the expected oxidation of anthracene, which occurs through a peroxidase-like mechanism. Anthracene belongs to the polycyclic aromatic hydrocarbon (PAH) family whose members are carcinogenic and persistent pollutants found in industrial waste waters. Our results show that anthracene oxidation by hemoglobin and hydrogen peroxide follows a typical bi-bi ping-pong mechanism with a V(max) equal to 0.250 microM/min, K(M(H2O2) )of 80 microM, K(M(ANT)) of 1.1 microM and k(cat) of 0.17/min. The oxidation of anthracene is shown to be pseudo-catalytic because an excess of hemoglobin and hydrogen peroxide is required to make PAH completely disappear. Thus, bovine hemoglobin presents, in different degrees, all the catalytic activities of the hemoprotein group, which makes it a very interesting protein for biotechnological processes and one with which structure-activity relationships can be studied.

  8. Efficient mono-acylation of fructose by lipase-catalyzed esterification in ionic liquid co-solvents.

    PubMed

    Li, Lu; Ji, Fangling; Wang, Jingyun; Jiang, Bo; Li, Yachen; Bao, Yongming

    2015-10-30

    Fructose monoesters are eco-friendly nonionic surfactants in various applications. Selective preparation of mono-acylated fructose is challenging due to the multiple hydroxyl sites available for acylation both chemically and enzymatically. Ionic liquids (ILs) have profound impacts not only on the reaction media but also on the catalytic properties of enzymes in the acylation process. In this study, utilizing an IL co-solvent system, selective synthesis of mono-acylated fructose with lauric acid catalyzed by immobilized Candida antarctica lipase B (CALB) was investigated. The imidazolium-based ILs selected as co-solvents with 2-methyl-2-butanol (2M2B) markedly improved the ratios of monolauroyl fructose in the presence of 60% [BMIM][TfO] (v/v) and 20% [BMIM][BF4] (v/v), in which the mono-acylated fructose was 85% and 78% respectively. Based on a Ping-Pong Bi-Bi model, a kinetic equation was fitted, by which the kinetic parameters revealed that the affinity between fructose and acyl-enzyme intermediate was enhanced. The inhibition effect of fructose on free enzyme was weakened in the presence of IL co-solvents. The conformation of CALB binding substrates also changed in the co-solvent system as demonstrated by Fourier transform infrared spectra. These results demonstrated that the variation of CALB kinetic characteristics was a crucial factor for the selectivity of mono-acylation in ILs/2M2B co-solvents.

  9. The kinetic mechanism of Human Thymidine Phosphorylase - a molecular target for cancer drug development.

    PubMed

    Deves, Candida; Rostirolla, Diana Carolina; Martinelli, Leonardo Kras Borges; Bizarro, Cristiano Valim; Santos, Diogenes Santiago; Basso, Luiz Augusto

    2014-03-01

    Human Thymidine Phosphorylase (HTP), also known as the platelet-derived endothelial cell growth factor (PD-ECGF) or gliostatin, catalyzes the reversible phosphorolysis of thymidine (dThd) to thymine and 2-deoxy-α-d-ribose-1-phosphate (2dR1P). HTP is a key enzyme in the pyrimidine salvage pathway involved in dThd homeostasis in cells. HTP is a target for anticancer drug development as its enzymatic activity promotes angiogenesis. Here, we describe cloning, expression, and purification to homogeneity of recombinant TYMP-encoded HTP. Peptide fingerprinting and the molecular mass value of the homogenous protein confirmed its identity as HTP assessed by mass spectrometry. Size exclusion chromatography showed that HTP is a dimer in solution. Kinetic studies revealed that HTP displayed substrate inhibition for dThd. Initial velocity and isothermal titration calorimetry (ITC) studies suggest that HTP catalysis follows a rapid-equilibrium random bi-bi kinetic mechanism. ITC measurements also showed that dThd and Pi binding are favorable processes. The pH-rate profiles indicated that maximal enzyme activity was achieved at low pH values. Functional groups with apparent pK values of 5.2 and 9.0 are involved in dThd binding and groups with pK values of 6.1 and 7.8 are involved in phosphate binding. PMID:24407036

  10. Indole-3-ethanol Oxidase

    PubMed Central

    Percival, Frank W.; Purves, William K.; Vickery, Larry E.

    1973-01-01

    We report the further characterization of indole-3-ethanol oxidase from cucumber seedlings. The effects of various inhibitors suggest that the enzyme may be a flavoprotein with a metal ion and sulfhydryl groups required for full activity. Indole-3-acetaldehyde, a product of the reaction, inhibits the enzyme. This inhibition is overcome by O2 but not by indole-3-ethanol, indicating that the kinetic mechanism of the enzyme is a ping-pong Bi-Bi. The enzyme undergoes cooperative interactions with indoleethanol, yielding Hill coefficients as high as 2.96. Gibberellins are without effect on the enzyme, but it is inhibited by several acidic indoles possessing growth-promoting activity and by two synthetic auxins, 2,4-dichlorophenoxyacetic acid and 2,4,5-trichlorophenoxyacetic acid. Increasing concentrations of indoleacetic acid (IAA) brought about a slight reduction in the indoleethanol concentration producing halfmaximal velocity. Increasing levels of indoleethanol decreased the concentration of IAA required for half-maximal inhibition. At low concentrations of indoleethanol, low levels of IAA activated rather than inhibited. The effect of IAA was not overcome at higher levels of indoleethanol. These results may be interpreted as showing that IAA is a noncompetitive inhibitor which binds to that conformation of the enzyme which also binds indoleethanol. The significance of these interactions for the regulation of IAA biosynthesis is discussed. PMID:16658401

  11. Acyclic monoterpene primary alcohol:NADP+ oxidoreductase of Rauwolfia serpentina cells: the key enzyme in biosynthesis of monoterpene alcohols.

    PubMed

    Ikeda, H; Esaki, N; Nakai, S; Hashimoto, K; Uesato, S; Soda, K; Fujita, T

    1991-02-01

    Acyclic monoterpene primary alcohol:NADP+ oxidoreductase, a key enzyme in the biosynthesis of monoterpene alcohols in plants, is unstable and has been only poorly characterized. However we have established conditions which stabilize the enzyme from Rauwolfia serpentina cells, and then purified it to homogeneity. It is a monomer with a molecular weight of about 44,000 and contains zinc ions. Various branched-chain allylic primary alcohols such as nerol, geraniol, and 10-hydroxygeraniol were substrates, but ethanol was inert. The enzyme exclusively requires NADP+ or NADPH as the cofactor. Steady-state kinetic studies showed that the nerol dehydrogenation proceeds by an ordered Bi-Bi mechanism. NADP+ binds the enzyme first and then NADPH is the second product released from it. Gas chromatography-mass spectrometric analysis of the reaction products showed that 10-hydroxygeraniol undergoes a reversible dehydrogenation to produce 10-oxogeraniol or 10-hydroxygeranial, which are oxidized further to give 10-oxogeranial, the direct precursor of iridodial. The enzyme has been found to exclusively transfer the pro-R hydrogen of NADPH to neral. The N-terminal sequence of the first 21 amino acids revealed no significant homology with those of various other proteins including the NAD(P)(+)-dependent alcohol dehydrogenases registered in a protein data bank. PMID:1864846

  12. Molecular determinants of azo reduction activity in the strain Pseudomonas putida MET94.

    PubMed

    Mendes, Sónia; Pereira, Luciana; Batista, Carlos; Martins, Lígia O

    2011-10-01

    Azo dyes are the major group of synthetic colourants used in industry and are serious environmental pollutants. In this study, Pseudomonas putida MET94 was selected from 48 bacterial strains on the basis of its superior ability to degrade a wide range of structurally diverse azo dyes. P. putida is a versatile microorganism with a well-recognised potential for biodegradation or bioremediation applications. P. putida MET94 removes, in 24 h and under anaerobic growing conditions, more than 80% of the majority of the structurally diverse azo dyes tested. Whole cell assays performed under anaerobic conditions revealed up to 90% decolourisation in dye wastewater bath models. The involvement of a FMN dependent NADPH: dye oxidoreductase in the decolourisation process was suggested by enzymatic measurements in cell crude extracts. The gene encoding a putative azoreductase was cloned from P. putida MET94 and expressed in Escherichia coli. The purified P. putida azoreductase is a 40 kDa homodimer with broad substrate specificity for azo dye reduction. The presence of dioxygen leads to the inhibition of the decolourisation activity in agreement with the results of cell cultures. The kinetic mechanism follows a ping-pong bi-bi reaction scheme and aromatic amine products were detected in stoichiometric amounts by high-performance liquid chromatography. Overall, the results indicate that P. putida MET94 is a promising candidate for bioengineering studies aimed at generating more effective dye-reducing strains.

  13. Lipase-catalyzed synthesis of palmitanilide: Kinetic model and antimicrobial activity study.

    PubMed

    Liu, Kuan-Miao; Liu, Kuan-Ju

    2016-01-01

    Enzymatic syntheses of fatty acid anilides are important owing to their wide range of industrial applications in detergents, shampoo, cosmetics, and surfactant formulations. The amidation reaction of Mucor miehei lipase Lipozyme IM20 was investigated for direct amidation of triacylglycerol in organic solvents. The process parameters (reaction temperature, substrate molar ratio, enzyme amount) were optimized to achieve the highest yield of anilide. The maximum yield of palmitanilide (88.9%) was achieved after 24 h of reaction at 40 °C at an enzyme concentration of 1.4% (70 mg). Kinetics of lipase-catalyzed amidation of aniline with tripalmitin has been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. The kinetic constants were estimated by using non-linear regression method using enzyme kinetic modules. The enzyme operational stability study showed that Lipozyme IM20 retained 38.1% of the initial activity for the synthesis of palmitanilide (even after repeated use for 48 h). Palmitanilide, a fatty acid amide, exhibited potent antimicrobial activity toward Bacillus cereus. PMID:26672452

  14. Substitution of arginine for histidine-47 in the coenzyme binding site of yeast alcohol dehydrogenase I

    SciTech Connect

    Gould, R.M.; Plapp, B.V. )

    1990-06-12

    Molecular modeling of alcohol dehydrogenases suggests that His-47 in the yeast enzyme (His-44 in the protein sequence, corresponding to Arg-47 in the horse liver enzyme) binds the pyrophosphate of the NAD coenzyme. His-47 in the Saccharomyces cerevisiae isoenzyme I was substituted with an arginine by a directed mutation. Steady-state kinetic results at pH 7.3 and 30{degree}C of the mutant and wild-type enzymes were consistent with an ordered Bi-Bi mechanism. The substitution decreased dissociation constants by 4-fold for NAD{sup +} and 2-fold for NADH while turnover numbers were decreased by 4-fold for ethanol oxidation and 6-fold for acetaldehyde reduction. The magnitudes of these effects are smaller than those found for the same mutation in the human liver {beta} enzyme, suggesting that other amino acid residues in the active site modulate the effects of the substitution. The pH dependencies of dissociation constants and other kinetic constants were similar in the two yeast enzymes. Thus, it appears that His-47 is not solely responsible for a pK value near 7 that controls activity and coenzyme binding rates in the wild-type enzyme. The small substrate deuterium isotope effect above pH 7 and the single exponential phase of NADH production during the transient oxidation of ethanol by the Arg-47 enzyme suggest that the mutation makes an isomerization of the enzyme-NAD{sup +} complex limiting for turnover with ethanol.

  15. All1371 is a polyphosphate-dependent glucokinase in Anabaena sp. PCC 7120.

    PubMed

    Klemke, Friederike; Beyer, Gabriele; Sawade, Linda; Saitov, Ali; Korte, Thomas; Maldener, Iris; Lockau, Wolfgang; Nürnberg, Dennis J; Volkmer, Thomas

    2014-12-01

    The polyphosphate glucokinases can phosphorylate glucose to glucose 6-phosphate using polyphosphate as the substrate. ORF all1371 encodes a putative polyphosphate glucokinase in the filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. Here, ORF all1371 was heterologously expressed in Escherichia coli, and its purified product was characterized. Enzyme activity assays revealed that All1371 is an active polyphosphate glucokinase that can phosphorylate both glucose and mannose in the presence of divalent cations in vitro. Unlike many other polyphosphate glucokinases, for which nucleoside triphosphates (e.g. ATP or GTP) act as phosphoryl group donors, All1371 required polyphosphate to confer its enzymic activity. The enzymic reaction catalysed by All1371 followed classical Michaelis-Menten kinetics, with kcat = 48.2 s(-1) at pH 7.5 and 28 °C and KM = 1.76 µM and 0.118 mM for polyphosphate and glucose, respectively. Its reaction mechanism was identified as a particular multi-substrate mechanism called the 'bi-bi ping-pong mechanism'. Bioinformatic analyses revealed numerous polyphosphate-dependent glucokinases in heterocyst-forming cyanobacteria. Viability of an Anabaena sp. PCC 7120 mutant strain lacking all1371 was impaired under nitrogen-fixing conditions. GFP promoter studies indicate expression of all1371 under combined nitrogen deprivation. All1371 might play a substantial role in Anabaena sp. PCC 7120 under these conditions.

  16. Kinetic modeling and docking study of immobilized lipase catalyzed synthesis of furfuryl acetate.

    PubMed

    Mathpati, Ashwini C; Badgujar, Kirtikumar C; Bhanage, Bhalchandra M

    2016-03-01

    The present work deals with the kinetic modeling and docking study for the furfuryl acetate synthesis using immobilized Burkholderia cepacia (BCL) lipase. Initially various lipases were immobilized on hydroxypropyl methyl cellulose (HPMC) and poly vinyl alcohol (PVA) base hybrid polymer matrix. After screening of various immobilized biocatalysts, HPMC:PVA:BCL was found to be a robust biocatalyst. Various reaction conditions were optimized using response surface methodology (RSM) based on a four-factor-three-level Box-Behnken design. The optimal conditions were obtained at molar ratio of 1:2 of furfuryl alcohol to acyl donor, temperature 50°C with catalyst loading of 30mg in 3mL of non-aqueous media toluene. Under these conditions 99.98% yield was obtained in 3h. The Arrhenius plot showed that the activation energy for furfuryl acetate synthesis was 10.68kcal/mol. The kinetics of reaction was studied close to optimized conditions which obey order bi-bi model. Molecular docking study was carried out to understand the active site of BCL which is responsible for the reaction. It was observed that the reaction proceeds via acylation of the active serine of BCL and demonstrating strong hydrogen bond between the substrate and histidine site. The catalyst recyclability study was carried up to five cycles. PMID:26827768

  17. Application of lipase immobilized on the biocompatible ternary blend polymer matrix for synthesis of citronellyl acetate in non-aqueous media: kinetic modelling study.

    PubMed

    Badgujar, Kirtikumar C; Bhanage, Bhalchandra M

    2014-04-10

    This work reports the use of new support for immobilization of lipase Burkholderia cepacia (BCL) matrix made up of polylactic acid (PLA), chitosan (CH), and polyvinyl alcohol (PVA). Initially lipase from various microbial sources and immobilization support composition was screened to obtain a robust biocatalyst. Among various biocatalysts preparation, the PLA:PVA:CH:BCL (1:6:1:2) was worked as a robust biocatalyst for the citronellyl acetate synthesis. Various reaction parameters were studied in detail to obtain the suitable reaction conditions for model citronellyl acetate synthesis reaction. Various kinetic parameters such as r(max), K(i(citronellol)), K(m(citronellol)), K(m(vinyl acetate)) were determined using non-linear regression analysis for the ternary complex as well as bi-bi ping-pong mechanism. The experimental results and kinetic study showed that citronellyl acetate synthesis catalyzed by immobilized lipase BCL followed the ternary complex mechanism with inhibition by alcohol (citronellol). The energy of activation for citronellyl acetate synthesis was found to be lower for immobilized lipase (8.9 kcal/mol) than aggregated lipase (14.8 kcal/mol) enzyme. The developed biocatalyst showed four to fivefold higher catalytic activity and excellent recyclability (up to six cycles) than the aggregated lipase. PMID:24629263

  18. Substrate-induced structures of bismuth adsorption on graphene: a first principles study.

    PubMed

    Lin, Shih-Yang; Chang, Shen-Lin; Chen, Hsin-Hsien; Su, Shu-Hsuan; Huang, Jung-Chun; Lin, Ming-Fa

    2016-07-28

    The geometric and electronic properties of Bi-adsorbed monolayer graphene, enriched by the strong effect of a substrate, are investigated by first-principles calculations. The six-layered substrate, corrugated buffer layer, and slightly deformed monolayer graphene are all simulated. Adatom arrangements are thoroughly studied by analyzing the ground-state energies, bismuth adsorption energies, and Bi-Bi interaction energies of different adatom heights, inter-adatom distance, adsorption sites, and hexagonal positions. A hexagonal array of Bi atoms is dominated by the interactions between the buffer layer and the monolayer graphene. An increase in temperature can overcome a ∼50 meV energy barrier and induce triangular and rectangular nanoclusters. The most stable and metastable structures agree with the scanning tunneling microscopy measurements. The density of states exhibits a finite value at the Fermi level, a dip at ∼-0.2 eV, and a peak at ∼-0.6 eV, as observed in the experimental measurements of the tunneling conductance. PMID:27354143

  19. All1371 is a polyphosphate-dependent glucokinase in Anabaena sp. PCC 7120.

    PubMed

    Klemke, Friederike; Beyer, Gabriele; Sawade, Linda; Saitov, Ali; Korte, Thomas; Maldener, Iris; Lockau, Wolfgang; Nürnberg, Dennis J; Volkmer, Thomas

    2014-12-01

    The polyphosphate glucokinases can phosphorylate glucose to glucose 6-phosphate using polyphosphate as the substrate. ORF all1371 encodes a putative polyphosphate glucokinase in the filamentous heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. Here, ORF all1371 was heterologously expressed in Escherichia coli, and its purified product was characterized. Enzyme activity assays revealed that All1371 is an active polyphosphate glucokinase that can phosphorylate both glucose and mannose in the presence of divalent cations in vitro. Unlike many other polyphosphate glucokinases, for which nucleoside triphosphates (e.g. ATP or GTP) act as phosphoryl group donors, All1371 required polyphosphate to confer its enzymic activity. The enzymic reaction catalysed by All1371 followed classical Michaelis-Menten kinetics, with kcat = 48.2 s(-1) at pH 7.5 and 28 °C and KM = 1.76 µM and 0.118 mM for polyphosphate and glucose, respectively. Its reaction mechanism was identified as a particular multi-substrate mechanism called the 'bi-bi ping-pong mechanism'. Bioinformatic analyses revealed numerous polyphosphate-dependent glucokinases in heterocyst-forming cyanobacteria. Viability of an Anabaena sp. PCC 7120 mutant strain lacking all1371 was impaired under nitrogen-fixing conditions. GFP promoter studies indicate expression of all1371 under combined nitrogen deprivation. All1371 might play a substantial role in Anabaena sp. PCC 7120 under these conditions. PMID:25320362

  20. Unraveling the B. pseudomallei Heptokinase WcbL: From Structure to Drug Discovery

    PubMed Central

    Vivoli, Mirella; Isupov, Michail N.; Nicholas, Rebecca; Hill, Andrew; Scott, Andrew E.; Kosma, Paul; Prior, Joann L.; Harmer, Nicholas J.

    2015-01-01

    Summary Gram-negative bacteria utilize heptoses as part of their repertoire of extracellular polysaccharide virulence determinants. Disruption of heptose biosynthesis offers an attractive target for novel antimicrobials. A critical step in the synthesis of heptoses is their 1-O phosphorylation, mediated by kinases such as HldE or WcbL. Here, we present the structure of WcbL from Burkholderia pseudomallei. We report that WcbL operates through a sequential ordered Bi-Bi mechanism, loading the heptose first and then ATP. We show that dimeric WcbL binds ATP anti-cooperatively in the absence of heptose, and cooperatively in its presence. Modeling of WcbL suggests that heptose binding causes an elegant switch in the hydrogen-bonding network, facilitating the binding of a second ATP molecule. Finally, we screened a library of drug-like fragments, identifying hits that potently inhibit WcbL. Our results provide a novel mechanism for control of substrate binding and emphasize WcbL as an attractive anti-microbial target for Gram-negative bacteria. PMID:26687481

  1. Evidence for Distributivity Effects in Comprehension

    PubMed Central

    Patson, Nikole D.; Warren, Tessa

    2010-01-01

    In the current paper, we introduce a new methodology for detecting whether a word in a sentence is conceptually represented as plural and use it to shed light on a debate about whether comprehenders interpret singular indefinite noun phrases within a distributed predicate as plural during on-line reading. Experiment 1 extended a methodology previously used by Berent, Pinker, Tzelgov, Bibi, and Goldfarb (2005) to test individual words or word pairs by, at a critical word, having readers judge whether one or two words appeared on a computer screen while performing self-paced reading on a sentence presented in one- and two-word chunks. Consistent with Berent et al., Experiment 1 indicated that participants were slower to judge that one word was on the screen when the word was plural (e.g., cats) than when it was singular (e.g., cat). Experiment 2 used this paradigm to show that readers build different conceptual representations for distributed versus collective predicates, and interpret a singular indefinite noun phrase within a distributed predicate as plural (e.g., Kaup, Kelter, & Habel, 2002, but cf. Filik, Paterson, & Liversedge, 2004; Paterson, Filik, & Liversedge, 2008). PMID:20438272

  2. Regulation by Phospholipids and Kinetic Studies of Plant Membrane-Bound UDP-Glucose Sterol β-d-Glucosyl Transferase 1

    PubMed Central

    Ullmann, Pascaline; Bouvier-Navé, Pierrette; Benveniste, P.

    1987-01-01

    Solubilization and partial purification of the microsomal UDP-glucose sterol glucosyl transferase activity from maize coleoptiles by chromatography on DEAE-cellulose resulted in a highly delipidated (>95%) and inactive enzymic preparation. Addition of sterols revealed part of the activity and subsequent addition of phospholipids further increased the activity. Negatively charged phospholipids were shown to be by far the best activators. The purification step also produced the elimination of two interfering microsomal enzymic activities: UDPase and steryl glucoside acyl transferase. The removal of these two enzymic activities was a prerequisite for kinetic studies including product-inhibition studies, since the substrates of these two latter enzymes are the products of UDPG-SGTase activity. The results of the kinetic studies strongly suggest an ordered bi-bi mechanism for the glucosylation of sterols. Finally the effect of different phospholipids on the kinetic parameters of the reaction was studied. Both phosphatidylcholine and phosphatidylglycerol significantly decrease Km-sterol (and not Km-UDPglucose) and increase the reaction Vmax. The decrease of Km-sterol is similar with both phospholipids whereas the increase of Vmax is much greater with phosphatidylglycerol than with phosphatidylcholine. PMID:16665682

  3. Ferromagnetism below 10K in Mn-doped BiTe

    NASA Astrophysics Data System (ADS)

    Bos, J. W. G.; Lee, M.; Morosan, E.; Zandbergen, H. W.; Lee, W. L.; Ong, N. P.; Cava, R. J.

    2006-11-01

    Ferromagnetism is observed below 10K in [Bi0.75Te0.125Mn0.125]Te . This material has the BiTe structure, which is made from the stacking of two Te-Bi-Te-Bi-Te blocks and one Bi-Bi block per unit cell. Crystal structure analysis shows that Mn is localized in the Bi2 blocks, and is accompanied by an equal amount of TeBi antisite occupancy in the Bi2Te3 blocks. These TeBi antisite defects greatly enhance the Mn solubility. This is demonstrated by comparison of the [Bi1-xMnx]Te and [Bi1-2xTexMnx]Te series; in the former, the solubility is limited to x=0.067 , while the latter has xmax=0.125 . The magnetism in [Bi1-xMnx]Te changes little with x , while that for [Bi1-2xTexMnx]Te shows a clear variation, leading to ferromagnetism for x>0.067 . Magnetic hysteresis and the anomalous Hall effect are observed for the ferromagnetic samples.

  4. A repetition-suppression account of between-trial effects in a modified Stroop paradigm.

    PubMed

    Juvina, Ion; Taatgen, Niels A

    2009-05-01

    Theories that postulate cognitive inhibition are very common in psychology and cognitive neuroscience [e.g., Hasher, L., Lustig, C., & Zacks, R. T. (2007). Inhibitory mechanisms and the control of attention. In A. Conway, C. Jarrold, M. Kane, A. Miyake, A. Towse, & J. Towse (Eds.), Variation in working memory (pp. 227-249). New York, NY: Oxford, University Press], although they have recently been severely criticized [e.g., MacLeod, C. M., Dodd, M. D., Sheard, E. D., Wilson, D. E., & Bibi, U. (2003). In opposition to inhibition. In H. Ross (Ed.), The psychology of learning and motivation (Vol. 43, pp. 163-214). Elsevier Science]. This paper poses and attempts to answer the question whether a research program with cognitive inhibition as its main theoretical assumption is still worth pursuing. We present a set of empirical data from a modified Stroop paradigm that replicates previously reported findings. These findings refer to between-trial effects previously described in the literature on Stroop, negative priming, and inhibition-of-return. Existing theoretical accounts fail to explain all these effects in an integrated way. A repetition-suppression mechanism is proposed in order to account for these data. This mechanism is instantiated as a computational cognitive model. The theoretical implications of this model are discussed.

  5. Kinetic modeling of solvent-free lipase-catalyzed partial hydrolysis of palm oil.

    PubMed

    Voll, Fernando Augusto Pedersen; Zanette, Andreia Fatima; Cabral, Vladimir Ferreira; Dariva, Claudio; Souza, Rodrigo Octavio Mendonça Alves de; Cardozo Filho, Lucio; Corazza, Marcos Lúcio

    2012-11-01

    This work reports the experimental data and kinetic modeling of diacylglycerol (DAG) production from palm oil using a commercial immobilized lipase (Lipozyme RM IM) in a solvent-free medium. The experiments were performed in batch mode, at 55 °C and 400 rpm, and the effects of enzyme concentration (0.68-2.04 wt% related to the mass of substrates), initial water concentration (5-15 wt% related to the mass of oil), and reaction time were evaluated. A novel kinetic model is presented based on the ordered-sequential bi-bi mechanism considering hydrolysis and esterification steps, in which a correlation between water-in-oil solubility and surfactant molecules concentration in the oil allowed the model to describe the induction period in the beginning of the hydrolysis reaction. Moreover, mass transfer limitations related to the enzyme concentration in the system were also taken into account. The proposed model presented a very satisfactory agreement with the experimental data, thus allowing a better understanding of the reaction kinetics. The best conditions obtained for the product (partially hydrolyzed palm oil) in terms of DAG yield (35.91 wt%) were 2.87 wt% enzyme/substrate, 2.10 wt% water/oil, and 72 h of reaction.

  6. Allosteric competitive inhibitors of the glucose-1-phosphate thymidylyltransferase (RmlA) from Pseudomonas aeruginosa.

    PubMed

    Alphey, Magnus S; Pirrie, Lisa; Torrie, Leah S; Boulkeroua, Wassila Abdelli; Gardiner, Mary; Sarkar, Aurijit; Maringer, Marko; Oehlmann, Wulf; Brenk, Ruth; Scherman, Michael S; McNeil, Michael; Rejzek, Martin; Field, Robert A; Singh, Mahavir; Gray, David; Westwood, Nicholas J; Naismith, James H

    2013-02-15

    Glucose-1-phosphate thymidylyltransferase (RmlA) catalyzes the condensation of glucose-1-phosphate (G1P) with deoxy-thymidine triphosphate (dTTP) to yield dTDP-d-glucose and pyrophosphate. This is the first step in the l-rhamnose biosynthetic pathway. l-Rhamnose is an important component of the cell wall of many microorganisms, including Mycobacterium tuberculosis and Pseudomonas aeruginosa. Here we describe the first nanomolar inhibitors of P. aeruginosa RmlA. These thymine analogues were identified by high-throughput screening and subsequently optimized by a combination of protein crystallography, in silico screening, and synthetic chemistry. Some of the inhibitors show inhibitory activity against M. tuberculosis. The inhibitors do not bind at the active site of RmlA but bind at a second site remote from the active site. Despite this, the compounds act as competitive inhibitors of G1P but with high cooperativity. This novel behavior was probed by structural analysis, which suggests that the inhibitors work by preventing RmlA from undergoing the conformational change key to its ordered bi-bi mechanism.

  7. Bismuth-palladium heterometallic carboxylate as a single-source precursor for the carbon-supported Pd-Bi/C catalysts.

    PubMed

    Li, Bo; Zhang, Haitao; Huynh, Lan; Diverchy, Chantal; Hermans, Sophie; Devillers, Michel; Dikarev, Evgeny V

    2009-07-01

    The heterometallic complex [Bi(2)Pd(2)(O(2)CCF(3))(10)(HO(2)CCF(3))(2)] (1) was obtained by the solid state reaction of Bi(III) trifluoroacetate/trifluoroacetic acid adduct with unsolvated trinuclear Pd(II) trifluoroacetate. The crystal structure of 1 consists of discrete tetranuclear molecules, in which two paddlewheel [BiPd(O(2)CCF(3))(4)] units are connected by two chelating-bridging trifluoroacetate ligands through bismuth ends. There are no metal-metal bonds in the tetrameric structure of 1, since both Bi...Pd (3.0843(4) A) and Bi...Bi (4.5074(4) A) distances are too long to be considered as bonding interactions. A study of the solution behavior revealed that not only the coordinated trifluoroacetic acid in 1 can be effectively replaced by other donor solvent molecules but also the tetranuclear complex can be cleaved in solution into discrete dinuclear Bi-Pd species. Complex 1 was used as precursor for the preparation of a bimetallic Pd-Bi carbon-supported catalyst. The preparation procedure included the modification of the carbon support to increase the number of oxygenated functions at its surface followed by grafting complex 1 via ligand exchange for surface carboxylates and activating thermally. The resulting catalyst, consisting of small supported metallic particles, was found to be more active than the reference materials prepared from multisource homometallic Pd and Bi precursors. PMID:19499893

  8. A kinetic study of isoamyl acetate synthesis by immobilized lipase-catalyzed acetylation in n-hexane.

    PubMed

    Romero, M D; Calvo, L; Alba, C; Daneshfar, A

    2007-01-01

    The objective of this work was to propose a reaction mechanism and to develop a rate equation for the synthesis of isoamyl acetate by acylation of the corresponding alcohol with acetic anhydride using the lipase Novozym 435 in n-hexane. The reaction between isoamyl alcohol and acetic anhydride occurred at high rate in first place. Then, if excess alcohol was used, produced acetic acid further reacted with remaining alcohol, leading to yields higher than 100% (based on initial acetic anhydride content). This reaction was much slower and took place only when acetic anhydride had been totally consumed. Optimal pH for Novozym 435 was 7.7. Acetic acid strongly inactivated the enzyme but it was partially caused by the pH drop in the biocatalyst aqueous microenvironment. Acetic anhydride also showed an important inhibition effect. On the contrary, isoamyl alcohol and isoamyl acetate had no negative effect on the lipase. The analysis of the initial rate data showed that reaction followed a Ping-Pong Bi-Bi mechanism with inhibition by acetic anhydride. The kinetic constants were obtained by multiple regression analysis of experimental findings. Equation predictions and experimental reaction rate values matched very well at conditions where acetic acid concentration in the medium was low.

  9. Evolution of Enzyme Kinetic Mechanisms.

    PubMed

    Ulusu, Nuriye Nuray

    2015-06-01

    This review paper discusses the reciprocal kinetic behaviours of enzymes and the evolution of structure-function dichotomy. Kinetic mechanisms have evolved in response to alterations in ecological and metabolic conditions. The kinetic mechanisms of single-substrate mono-substrate enzyme reactions are easier to understand and much simpler than those of bi-bi substrate enzyme reactions. The increasing complexities of kinetic mechanisms, as well as the increasing number of enzyme subunits, can be used to shed light on the evolution of kinetic mechanisms. Enzymes with heterogeneous kinetic mechanisms attempt to achieve specific products to subsist. In many organisms, kinetic mechanisms have evolved to aid survival in response to changing environmental factors. Enzyme promiscuity is defined as adaptation to changing environmental conditions, such as the introduction of a toxin or a new carbon source. Enzyme promiscuity is defined as adaptation to changing environmental conditions, such as the introduction of a toxin or a new carbon source. Enzymes with broad substrate specificity and promiscuous properties are believed to be more evolved than single-substrate enzymes. This group of enzymes can adapt to changing environmental substrate conditions and adjust catalysing mechanisms according to the substrate's properties, and their kinetic mechanisms have evolved in response to substrate variability.

  10. Efficient mono-acylation of fructose by lipase-catalyzed esterification in ionic liquid co-solvents.

    PubMed

    Li, Lu; Ji, Fangling; Wang, Jingyun; Jiang, Bo; Li, Yachen; Bao, Yongming

    2015-10-30

    Fructose monoesters are eco-friendly nonionic surfactants in various applications. Selective preparation of mono-acylated fructose is challenging due to the multiple hydroxyl sites available for acylation both chemically and enzymatically. Ionic liquids (ILs) have profound impacts not only on the reaction media but also on the catalytic properties of enzymes in the acylation process. In this study, utilizing an IL co-solvent system, selective synthesis of mono-acylated fructose with lauric acid catalyzed by immobilized Candida antarctica lipase B (CALB) was investigated. The imidazolium-based ILs selected as co-solvents with 2-methyl-2-butanol (2M2B) markedly improved the ratios of monolauroyl fructose in the presence of 60% [BMIM][TfO] (v/v) and 20% [BMIM][BF4] (v/v), in which the mono-acylated fructose was 85% and 78% respectively. Based on a Ping-Pong Bi-Bi model, a kinetic equation was fitted, by which the kinetic parameters revealed that the affinity between fructose and acyl-enzyme intermediate was enhanced. The inhibition effect of fructose on free enzyme was weakened in the presence of IL co-solvents. The conformation of CALB binding substrates also changed in the co-solvent system as demonstrated by Fourier transform infrared spectra. These results demonstrated that the variation of CALB kinetic characteristics was a crucial factor for the selectivity of mono-acylation in ILs/2M2B co-solvents. PMID:26343327

  11. MatProps: Material Properties Database and Associated Access Library

    SciTech Connect

    Durrenberger, J K; Becker, R C; Goto, D M; Neely, J R; Wallin, B K

    2007-08-13

    Coefficients for analytic constitutive and equation of state models (EOS), which are used by many hydro codes at LLNL, are currently stored in a legacy material database (Steinberg, UCRL-MA-106349). Parameters for numerous materials are available through this database, and include Steinberg-Guinan and Steinberg-Lund constitutive models for metals, JWL equations of state for high explosives, and Mie-Gruniesen equations of state for metals. These constitutive models are used in most of the simulations done by ASC codes today at Livermore. Analytic EOSs are also still used, but have been superseded in many cases by tabular representations in LEOS (http://leos.llnl.gov). Numerous advanced constitutive models have been developed and implemented into ASC codes over the past 20 years. These newer models have more physics and better representations of material strength properties than their predecessors, and therefore more model coefficients. However, a material database of these coefficients is not readily available. Therefore incorporating these coefficients with those of the legacy models into a portable database that could be shared amongst codes would be most welcome. The goal of this paper is to describe the MatProp effort at LLNL to create such a database and associated access library that could be used by codes throughout the DOE complex and beyond. We have written an initial version of the MatProp database and access library and our DOE/ASC code ALE3D (Nichols et. al., UCRL-MA-152204) is able to import information from the database. The database, a link to which exists on the Sourceforge server at LLNL, contains coefficients for many materials and models (see Appendix), and includes material parameters in the following categories--flow stress, shear modulus, strength, damage, and equation of state. Future versions of the Matprop database and access library will include the ability to read and write material descriptions that can be exchanged between codes. It will

  12. Plume Generation Zones On The Core Mantle Boundary: their origin and what they tell about how the Earth works - and how it has worked (Arthur Holmes Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Burke, Kevin

    2014-05-01

    proving useful in the interpretation of mantle behaviour (For example: TPW, Steinberger and Torsvik 2008) and represent an as yet not fully utilized opportunity for improving understanding of the solid Earth. SUCCINCT REFERENCES: Burke et al. EPSLv.265, 2008, Burke et al. GRL v.39.2012, Garnero et al. GSA Mem.430, 2007, Morgan 1972 GSA Mem.132, Steinberger and Torsvik, Nature v.452, 2008, Torsvik et al Nature v.466, 2010, Wilson Can. J. Physics 1963.

  13. Eruption Sites of LIPs of the Past 250 My With Respect to the slow/fast D" Boundary in Four Improved Reference Frames

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.; Smethurst, M. A.; Burke, K.; Steinberger, B.

    2005-05-01

    We have shown (Burke and Torsvik 2004) that nearly all of the Large Igneous Provinces (LIPs) erupted on the Earth's surface during the past 250 My rose, at the time of their eruption, from the base of the mantle close to the 1 percent slow S-wave delta V contour of the D" zone. Here we report on the use of (1) Improved plate-circuitry (among PAC-ANT-AUS-MADAGAS-IND-SOAM-AFR) and (2) upgraded paleomagnetic data-sets to confirm and refine our results. In an attempt to establish whether rotation of LIPs to their sites at eruption can be used to learn something about mantle and core behavior over the past 250 My we have performed rotations on assumptions of: (1) a persistent geocentric axial magnetic dipole field, (2) a time-dependent non-dipole (octopole) magnetic field contribution (Torsvik and Van der Voo (2002), (3) a mantle wind contribution to mantle flow (Steinberger et al. 2004) and (4) a revised (new timescale) fixed hot-spot (no mantle wind) reference frame. Our test consisted of estimating how closely radials dropped from rotated LIP sets based on these four assumptions plotted to the 1 percent slow contour derived from seismic tomography. We compared S-wave tomographic models at the CMB and opted to use the SMEAN model (Becker and Boschi 2002) recognizing that other models are similar and that all have similar limitations. The mean deviation of the projected rotated LIPs from the 1 percent slow contour is 6 degrees at the CMB. The four different assumptions yield results between 6.5 and 5.5 degrees which seems unlikely to be a significant difference. Our conclusion is that it is not yet possible to discriminate among the four models of mantle and core behavior using our procedure. Becker, T.W and Boschi, L. 2002: A comparison of tomographic and geodynamic mantle models. Geochemistry, Geophysics, Geosystems 3, 2001GC000168. Burke, K. and Torsvik, T.H. 2004: Derivation of large igneous provinces of the past 200 million years from long-term heterogeneities in

  14. A V2O3-ordered mesoporous carbon composite with novel peroxidase-like activity towards the glucose colorimetric assay

    NASA Astrophysics Data System (ADS)

    Han, Lei; Zeng, Lingxing; Wei, Mingdeng; Li, Chang Ming; Liu, Aihua

    2015-07-01

    It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a significantly higher catalytic efficiency (kcat/KM) towards the oxidation of ABTS in comparison with the natural peroxidases. Furthermore, the Ping-pong BiBi mechanism was proposed to explain the catalytic reaction by V2O3-OMC. Based on this highly active biomimetic peroxidase and the colorimetric detection of H2O2, a facile analytical method was developed to detect glucose by using V2O3-OMC and glucose oxidase, which had a wide linear range (0.01-4 mM glucose), good selectivity and reliability for successful detection of various real samples. Thus, the novel V2O3-OMC peroxidase mimetic holds great promise for broad potential applications.It is of great scientific and practical significance to explore inorganic mimetic enzymes to replace natural enzymes due to their instability and high cost. Herein we present an interesting discovery that a V2O3-ordered mesoporous carbon composite (V2O3-OMC) has a novel peroxidase-like activity towards fast redox reaction of typical peroxidase substrates H2O2 and 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS). Due to the small size effect and large surface area of V2O3 nanoparticles supported by OMC, V2O3-OMC exhibited excellent catalytic performance with a kcat of 1.28 × 104 s-1, KM (ABTS) of 0.067 mM and KM (H2O2) of 0.16 mM, and a

  15. Global Asymmetries in the Heliosphere: Signature of the Interstellar Magnetic Field

    NASA Astrophysics Data System (ADS)

    Opher, Merav; Alouani-Bibi, Fathallah; Izmodenov, Vladislav; Richardson, John; Toth, Gabor; Gombosi, Tamas

    In recent years it become clear that magnetic field effects, plays an important role in the Heliosphere, from shaping it and possible being responsible for the asymmetries observed in the Voyager data (e.g., Opher et al. 2007, 2009). However, the strength and orientation of the field in the local interstellar medium near the heliosphere has been poorly constrained. Previous estimates of the field strength range from 1.8-2.5 G and the field was thought to be parallel to the Galactic plane or inclined by 38-60 (Lallement et al. 2005) or 60-90 (Opher et al. 2007) to this plane. These estimates relied either on indirect observational inferences or modeling in which the interstellar neutral hydrogen was not taken into account. We will discuss recent work that indicate that based on asymmetries detected by Voyager 1 and 2 and measurements of the deflection of the solar wind plasma flows in the heliosheath (Opher et al. 2009) indicate that the field strength in the local interstellar medium is strong, between 4-5 G (Other works such as Izmodenov 2009; Pogorelov et al. 2009; Ratkiewickz et al. 2009 found similar strength). The field is tilted 20-30 from the interstellar medium flow direction (resulting from the peculiar motion of the Sun in the Galaxy) and is at an angle of about 30 from the Galactic plane. We will discuss the effect of such magnetic field in the global asymmetries of the heliosphere. We further will comment on the effect on asymmetries of our recent model of Kinetic-MHD model treating the neutrals in kinetic fashion (Alouani-Bibi et al. 2010). We will relate our findings with the most recent results of IBEX that indicate that the interstellar magnetic field has a strong signature in the emission of energetic neutrals.

  16. Expression, purification and characterization of enoyl-ACP reductase II, FabK, from Porphyromonas gingivalis

    SciTech Connect

    Hevener, Kirk E.; Mehboob, Shahila; Boci, Teuta; Truong, Kent; Santarsiero, Bernard D.; Johnson, Michael E.

    2012-10-25

    The rapid rise in bacterial drug resistance coupled with the low number of novel antimicrobial compounds in the discovery pipeline has led to a critical situation requiring the expedient discovery and characterization of new antimicrobial drug targets. Enzymes in the bacterial fatty acid synthesis pathway, FAS-II, are distinct from their mammalian counterparts, FAS-I, in terms of both structure and mechanism. As such, they represent attractive targets for the design of novel antimicrobial compounds. Enoyl-acyl carrier protein reductase II, FabK, is a key, rate-limiting enzyme in the FAS-II pathway for several bacterial pathogens. The organism, Porphyromonas gingivalis, is a causative agent of chronic periodontitis that affects up to 25% of the US population and incurs a high national burden in terms of cost of treatment. P. gingivalis expresses FabK as the sole enoyl reductase enzyme in its FAS-II cycle, which makes this a particularly appealing target with potential for selective antimicrobial therapy. Herein we report the molecular cloning, expression, purification and characterization of the FabK enzyme from P. gingivalis, only the second organism from which this enzyme has been isolated. Characterization studies have shown that the enzyme is a flavoprotein, the reaction dependent upon FMN and NADPH and proceeding via a Ping-Pong Bi-Bi mechanism to reduce the enoyl substrate. A sensitive assay measuring the fluorescence decrease of NADPH as it is converted to NADP{sup +} during the reaction has been optimized for high-throughput screening. Finally, protein crystallization conditions have been identified which led to protein crystals that diffract x-rays to high resolution.

  17. The enzymology of alanine aminotransferase (AlaAT) isoforms from Hordeum vulgare and other organisms, and the HvAlaAT crystal structure.

    PubMed

    Duff, Stephen M G; Rydel, Timothy J; McClerren, Amanda L; Zhang, Wenlan; Li, Jimmy Y; Sturman, Eric J; Halls, Coralie; Chen, Songyang; Zeng, Jiamin; Peng, Jiexin; Kretzler, Crystal N; Evdokimov, Artem

    2012-12-01

    In this paper we describe the expression, purification, kinetics and biophysical characterization of alanine aminotransferase (AlaAT) from the barley plant (Hordeum vulgare). This dimeric PLP-dependent enzyme is a pivotal element of several key metabolic pathways from nitrogen assimilation to carbon metabolism, and its introduction into transgenic plants results in increased yield. The enzyme exhibits a bi-bi ping-pong reaction mechanism with a K(m) for alanine, 2-oxoglutarate, glutamate and pyruvate of 3.8, 0.3, 0.8 and 0.2 mM, respectively. Barley AlaAT catalyzes the forward (alanine-forming) reaction with a k(cat) of 25.6 s(-1), the reverse (glutamate-forming) reaction with k(cat) of 12.1 s(-1) and an equilibrium constant of ~0.5. The enzyme is also able to utilize aspartate and oxaloacetate with ~10% efficiency as compared to the native substrates, which makes it much more specific than related bacterial/archaeal enzymes (that also have lower K(m) values). We have crystallized barley AlaAT in complex with PLP and l-cycloserine and solved the structure of this complex at 2.7 Å resolution. This is the first example of a plant AlaAT structure, and it reveals a canonical aminotransferase fold similar to structures of the Thermotoga maritima, Pyrococcus furiosus, and human enzymes. This structure bridges our structural understanding of AlaAT mechanism between three kingdoms of life and allows us to shed some light on the specifics of the catalysis performed by these proteins. PMID:22750542

  18. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis.

    PubMed

    Giancaspero, Teresa A; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina M; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-01-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in a broad spectrum of biological activities, among which energetic metabolism and chromatin remodeling. Subcellular localisation of FAD synthase (EC 2.7.7.2, FADS), the second enzyme in the FAD forming pathway, is addressed here in HepG2 cells by confocal microscopy, in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalyzed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesizing activity, hFADS is able to operate as a FAD "chaperone." The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear lysine-specific demethylase 1 (LSD1) or a mitochondrial dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4). Both enzymes carry out similar reactions of oxidative demethylation, in which tetrahydrofolate is converted into 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells. PMID:25954742

  19. DNA (cytosine-N4-)- and -(adenine-N6-)-methyltransferases have different kinetic mechanisms but the same reaction route. A comparison of M.BamHI and T4 Dam.

    PubMed

    Malygin, Ernst G; Zinoviev, Victor V; Evdokimov, Alexey A; Lindstrom, William M; Reich, Norbert O; Hattman, Stanley

    2003-05-01

    We studied the kinetics of methyl group transfer by the BamHI DNA-(cytosine-N(4)-)-methyltransferase (MTase) from Bacillus amyloliquefaciens to a 20-mer oligodeoxynucleotide duplex containing the palindromic recognition site GGATCC. Under steady state conditions the BamHI MTase displayed a simple kinetic behavior toward the 20-mer duplex. There was no apparent substrate inhibition at concentrations much higher than the K(m) for either DNA (100-fold higher) or S-adenosyl-l-methionine (AdoMet) (20-fold higher); this indicates that dead-end complexes did not form in the course of the methylation reaction. The DNA methylation rate was analyzed as a function of both substrate and product concentrations. It was found to exhibit product inhibition patterns consistent with a steady state random bi-bi mechanism in which the dominant order of substrate binding and product release (methylated DNA, DNA(Me), and S-adenosyl-l-homocysteine, AdoHcy) was Ado-Met DNA DNA(Me) AdoHcy. The M.BamHI kinetic scheme was compared with that for the T4 Dam (adenine-N(6)-)-MTase. The two differed with respect to an effector action of substrates and in the rate-limiting step of the reaction (product inhibition patterns are the same for the both MTases). From this we conclude that the common chemical step in the methylation reaction, methyl transfer from AdoMet to a free exocyclic amino group, is not sufficient to dictate a common kinetic scheme even though both MTases follow the same reaction route.

  20. The enzymology of alanine aminotransferase (AlaAT) isoforms from Hordeum vulgare and other organisms, and the HvAlaAT crystal structure.

    PubMed

    Duff, Stephen M G; Rydel, Timothy J; McClerren, Amanda L; Zhang, Wenlan; Li, Jimmy Y; Sturman, Eric J; Halls, Coralie; Chen, Songyang; Zeng, Jiamin; Peng, Jiexin; Kretzler, Crystal N; Evdokimov, Artem

    2012-12-01

    In this paper we describe the expression, purification, kinetics and biophysical characterization of alanine aminotransferase (AlaAT) from the barley plant (Hordeum vulgare). This dimeric PLP-dependent enzyme is a pivotal element of several key metabolic pathways from nitrogen assimilation to carbon metabolism, and its introduction into transgenic plants results in increased yield. The enzyme exhibits a bi-bi ping-pong reaction mechanism with a K(m) for alanine, 2-oxoglutarate, glutamate and pyruvate of 3.8, 0.3, 0.8 and 0.2 mM, respectively. Barley AlaAT catalyzes the forward (alanine-forming) reaction with a k(cat) of 25.6 s(-1), the reverse (glutamate-forming) reaction with k(cat) of 12.1 s(-1) and an equilibrium constant of ~0.5. The enzyme is also able to utilize aspartate and oxaloacetate with ~10% efficiency as compared to the native substrates, which makes it much more specific than related bacterial/archaeal enzymes (that also have lower K(m) values). We have crystallized barley AlaAT in complex with PLP and l-cycloserine and solved the structure of this complex at 2.7 Å resolution. This is the first example of a plant AlaAT structure, and it reveals a canonical aminotransferase fold similar to structures of the Thermotoga maritima, Pyrococcus furiosus, and human enzymes. This structure bridges our structural understanding of AlaAT mechanism between three kingdoms of life and allows us to shed some light on the specifics of the catalysis performed by these proteins.

  1. Enhancement of Er optical efficiency through bismuth sensitization in yttrium oxide

    SciTech Connect

    Scarangella, Adriana; Reitano, Riccardo; Franzò, Giorgia; Miritello, Maria; Priolo, Francesco

    2015-07-27

    The process of energy transfer (ET) between optically active ions has been widely studied to improve the optical efficiency of a system for different applications, from lighting and photovoltaics to silicon microphotonics. In this work, we report the influence of Bi on the Er optical emission in erbium-yttrium oxide thin films synthesized by magnetron co-sputtering. We demonstrate that this host permits to well dissolve Er and Bi ions, avoiding their clustering, and thus to stabilize the optically active Er{sup 3+} and Bi{sup 3+} valence states. In addition, we establish the ET occurrence from Bi{sup 3+} to Er{sup 3+} by the observed Bi{sup 3+} PL emission decrease and the simultaneous Er{sup 3+} photoluminescence (PL) emission increase. This was further confirmed by the coincidence of the Er{sup 3+} and Bi{sup 3+} excitation bands, analyzed by PL excitation spectroscopy. By increasing the Bi content of two orders of magnitude inside the host, though the occurrence of Bi-Bi interactions becomes deleterious for Bi{sup 3+} optical efficiency, the ET process between Bi{sup 3+} and Er{sup 3+} is still prevalent. We estimate ET efficiency of 70% for the optimized Bi:Er ratio equal to 1:3. Moreover, we have demonstrated to enhance the Er{sup 3+} effective excitation cross section by more than three orders of magnitude with respect to the direct one, estimating a value of 5.3 × 10{sup −18} cm{sup 2}, similar to the expected Bi{sup 3+} excitation cross section. This value is one of the highest obtained for Er in Si compatible hosts. These results make this material very promising as an efficient emitter for Si-compatible photonics devices.

  2. Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

    PubMed

    Martinelle, M; Hult, K

    1995-09-01

    The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid. PMID:7669809

  3. The effect of thermodynamic properties of solvent mixtures explains the difference between methanol and ethanol in C.antarctica lipase B catalyzed alcoholysis.

    PubMed

    Sasso, Francesco; Kulschewski, Tobias; Secundo, Francesco; Lotti, Marina; Pleiss, Jürgen

    2015-11-20

    Kinetic modelling, molecular modelling, and experimental determination of the initial reaction velocity of lipase-catalyzed alcoholysis were combined to study the effect of the alcohol substrate to catalytic activity. The model system consisted of methanol or ethanol at varying concentrations, vinyl acetate as ester substrate 15.2% (v/v), toluene as organic solvent, water at a controlled thermodynamic activity of 0.09, and C. antarctica lipase B as enzyme. For both alcohol substrates, the initial reaction velocity increased sharply at low concentrations and reached a maximum at 0.7% (v/v) for methanol and 2% (v/v) for ethanol. For higher concentrations, the reaction rate decreased to a level of 74% and 60% of the peak value, respectively, due to substrate inhibition. The concentration dependency was described by a kinetic model, including a ping-pong bi-bi mechanism and competitive inhibition by the alcohol, and confirmed previous observations that methanol is more efficiently inhibiting the enzyme than ethanol. However, if the initial reaction velocity was expressed in terms of thermodynamic activity of the two alcohol substrates, the maximum of initial reaction velocity was similar for methanol (a MeOH(max)=0.19) and ethanol (a EtOH(max)=0.21). This was confirmed by molecular modelling which resulted in similar KM (0.22 and 0.19) and Ki values (0.44 and 0.49) for methanol and ethanol, respectively, if expressed in thermodynamic activities. Thus, the experimentally observed difference between methanol and ethanol is not due to differences in interaction with the enzyme but is a consequence of the thermodynamics of the substrate-solvent mixture. For low concentrations in toluene, the activity coefficient of methanol is 40% higher than the activity coefficient of ethanol (γ MeOH=8.5, γ EtOH=6.1).

  4. Determination of the Structure and Catalytic Mechanism of Sorghum bicolor Caffeic Acid O-Methyltransferase and the Structural Impact of Three brown midrib12 Mutations1[W

    PubMed Central

    Green, Abigail R.; Lewis, Kevin M.; Barr, John T.; Jones, Jeffrey P.; Lu, Fachuang; Ralph, John; Vermerris, Wilfred; Sattler, Scott E.; Kang, ChulHee

    2014-01-01

    Using S-adenosyl-methionine as the methyl donor, caffeic acid O-methyltransferase from sorghum (Sorghum bicolor; SbCOMT) methylates the 5-hydroxyl group of its preferred substrate, 5-hydroxyconiferaldehyde. In order to determine the mechanism of SbCOMT and understand the observed reduction in the lignin syringyl-to-guaiacyl ratio of three brown midrib12 mutants that carry COMT gene missense mutations, we determined the apo-form and S-adenosyl-methionine binary complex SbCOMT crystal structures and established the ternary complex structure with 5-hydroxyconiferaldehyde by molecular modeling. These structures revealed many features shared with monocot ryegrass (Lolium perenne) and dicot alfalfa (Medicago sativa) COMTs. SbCOMT steady-state kinetic and calorimetric data suggest a random bi-bi mechanism. Based on our structural, kinetic, and thermodynamic results, we propose that the observed reactivity hierarchy among 4,5-dihydroxy-3-methoxycinnamyl (and 3,4-dihydroxycinnamyl) aldehyde, alcohol, and acid substrates arises from the ability of the aldehyde to stabilize the anionic intermediate that results from deprotonation of the 5-hydroxyl group by histidine-267. Additionally, despite the presence of other phenylpropanoid substrates in vivo, sinapaldehyde is the preferential product, as demonstrated by its low Km for 5-hydroxyconiferaldehyde. Unlike its acid and alcohol substrates, the aldehydes exhibit product inhibition, and we propose that this is due to nonproductive binding of the S-cis-form of the aldehydes inhibiting productive binding of the S-trans-form. The S-cis-aldehydes most likely act only as inhibitors, because the high rotational energy barrier around the 2-propenyl bond prevents S-trans-conversion, unlike alcohol substrates, whose low 2-propenyl bond rotational energy barrier enables rapid S-cis/S-trans-interconversion. PMID:24948836

  5. The rate-determining steps of aldo-keto reductases (AKRs), a study on human steroid 5β-reductase (AKR1D1).

    PubMed

    Chen, Mo; Jin, Yi; Penning, Trevor M

    2015-06-01

    Aldo-keto reductases (AKRs) are an expanding family of NAD(P)(H)-dependent oxidoreductases that catalyze the reduction of either carbonyl groups or α,β-unsaturated ketones on a variety of endogenous and exogenous substrates. The enzymes catalyze a sequential ordered bi-bi kinetic mechanism, in which cofactor is bound first and released last. Using human steroid 5β-reductase (AKR1D1) as a representative enzyme, the influence of substrate structure on the rate-limiting steps of AKR catalysis has been previously determined. The rate of the chemistry step was found to differ by two orders of magnitude when different steroid substrates were used in single turnover experiments with AKR1D1. This difference was reflected in multiple turnover experiments. C17-C21 steroid substrates exhibited a fast chemistry step followed by slow product release as suggested by "burst" phase kinetics. By contrast, C27 steroids have a slower chemical step that determines the rate of the reaction and "burst-phase" kinetics are no longer observed. Here we present single turnover kinetic experiments and find that they support the existence of two different binding poses for fast substrates due to their biphasic nature. We also re-interpret the loss of "burst-phase" kinetics in the multiple turnover experiments as due to long range effects of the steroid side-chain interacting with distal parts of the steroid pocket to perturb the reaction trajectory for hydride transfer and thus reduce kcat. The ability of steroid structure and hence binding pose to influence rate determination in steroid transforming AKRs is discussed as a general phenomenon.

  6. Ecosystem responses to extreme natural events: impacts of three sequential hurricanes in fall 1999 on sediment quality and condition of benthic fauna in the Neuse River Estuary, North Carolina.

    PubMed

    Balthis, W Leonard; Hyland, Jeffrey L; Bearden, Daniel W

    2006-08-01

    A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km2 (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissolved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia.

  7. The anti-Fn14 antibody BIIB036 inhibits tumor growth in xenografts and patient derived primary tumor models and enhances efficacy of chemotherapeutic agents in multiple xenograft models.

    PubMed

    Michaelson, Jennifer S; Kelly, Rebecca; Yang, Lu; Zhang, Xiamei; Wortham, Kathleen; Joseph, Ingrid B J K

    2012-07-01

    Agonistic antibodies targeting Fn14, the receptor for TWEAK, have demonstrated anti-tumor activity in xenograft models. Herein, we further explore the therapeutic potential of the humanized anti-Fn14 agonistic antibody, BIIB036, as a single agent and in combination with standard of care cancer therapeutics. Pharmacokinetic studies of BIIB036 in tumor-bearing mice revealed a half-life of approximately three days suggesting twice a week dosing would be necessary to maintain efficacy. However, in multiple xenograft models, BIIB036 treatment resulted in extended tumor growth inhibition up to 40-50 d following cessation of dosing, suggesting that frequent administration of BIIB036 may not be necessary to maintain prolonged anti-tumor activity. Subsequent xenograft studies revealed that maximal efficacy was achieved with BIIB036 dosing once every two weeks, by either intraperitoneal or subcutaneous administration. Xenograft tumors that were initially treated with BIBI036 and then re-grew up to 1000 mm³ following cessation of the first cycle of treatment remained sensitive to a second cycle of treatment. BIIB036 was also evaluated in patient derived primary colon tumor models, where efficacy compared favorably with a standard of care agent. Lastly, BIIB036 enhanced the efficacy of several standard of care chemotherapeutics, including paclitaxel in MDA-MBA-231 breast tumor xenografts, paclitaxel or carboplatin in HOP62 non-small cell lung xenografts, and 5-FU in NCI-N87 gastric xenografts, with no overlapping toxicities. These studies thus establish BIIB036 as a promising therapeutic agent with durable anti-tumor activity in human xenografts as well as patient derived primary tumor models, and enhanced activity and tolerability in combination with standard of care chemotherapeutics. Taken together, the data presented herein suggest that BIIB036 warrants evaluation in the clinic.

  8. A novel viral thymidylate kinase with dual kinase activity.

    PubMed

    Guevara-Hernandez, Eduardo; Arvizu-Flores, Aldo A; Lugo-Sanchez, Maria E; Velazquez-Contreras, Enrique F; Castillo-Yañez, Francisco J; Brieba, Luis G; Sotelo-Mundo, Rogerio R

    2015-10-01

    Nucleotide phosphorylation is a key step in DNA replication and viral infections, since suitable levels of nucleotide triphosphates pool are required for this process. Deoxythymidine monophosphate (dTMP) is produced either by de novo or salvage pathways, which is further phosphorylated to deoxythymidine triphosphate (dTTP). Thymidyne monophosphate kinase (TMK) is the enzyme in the junction of both pathways, which phosphorylates dTMP to yield deoxythymidine diphosphate (dTDP) using adenosine triphosphate (ATP) as a phosphate donor. White spot syndrome virus (WSSV) genome contains an open reading frame (ORF454) that encodes a thymidine kinase and TMK domains in a single polypeptide. We overexpressed the TMK ORF454 domain (TMKwssv) and its specific activity was measured with dTMP and dTDP as phosphate acceptors. We found that TMKwssv can phosphorylate dTMP to yield dTDP and also is able to use dTDP as a substrate to produce dTTP. Kinetic parameters K M and k cat were calculated for dTMP (110 μM, 3.6 s(-1)), dTDP (251 μM, 0.9 s(-1)) and ATP (92 μM, 3.2 s(-1)) substrates, and TMKwssv showed a sequential ordered bi-bi reaction mechanism. The binding constants K d for dTMP (1.9 μM) and dTDP (10 μM) to TMKwssv were determined by Isothermal Titration Calorimetry. The affinity of the nucleotidic analog stavudine monophosphate was in the same order of magnitude (K d 3.6 μM) to the canonical substrate dTMP. These results suggest that nucleotide analogues such as stavudine could be a suitable antiviral strategy for the WSSV-associated disease.

  9. Kinetic, Thermodynamic, and Structural Insight into the Mechanism of Phosphopantetheine Adenylyltransferase from Mycobacterium tuberculosis

    SciTech Connect

    Wubben, Thomas J.; Mesecar, Andrew D.

    2012-05-29

    Phosphopantetheine adenylyltransferase (PPAT) catalyzes the penultimate step in the coenzyme A (CoA) biosynthetic pathway, reversibly transferring an adenylyl group from ATP to 4'-phosphopantetheine (PhP) to form dephosphocoenzyme A. This reaction sits at the branch point between the de novo pathway and the salvage pathway, and has been shown to be a rate-limiting step in the biosynthesis of CoA. Importantly, bacterial and mammalian PPATs share little sequence homology, making the enzyme a potential target for antibiotic development. A series of steady-state kinetic, product inhibition, and direct binding studies with Mycobacterium tuberculosis PPAT (MtPPAT) was conducted and suggests that the enzyme utilizes a nonrapid-equilibrium random bi-bi mechanism. The kinetic response of MtPPAT to the binding of ATP was observed to be sigmoidal under fixed PhP concentrations, but substrate inhibition was observed at high PhP concentrations under subsaturating ATP concentrations, suggesting a preferred pathway to ternary complex formation. Negative cooperativity in the kinetic response of MtPPAT to PhP binding was observed under certain conditions and confirmed thermodynamically by isothermal titration calorimetry, suggesting the formation of an asymmetric quaternary structure during sequential ligation of substrates. Asymmetry in binding was also observed in isothermal titration calorimetry experiments with dephosphocoenzyme A and CoA. X-ray structures of MtPPAT in complex with PhP and the nonhydrolyzable ATP analogue adenosine-5'-[({alpha},{beta})-methyleno]triphosphate were solved to 1.57 {angstrom} and 2.68 {angstrom}, respectively. These crystal structures reveal small conformational changes in enzyme structure upon ligand binding, which may play a role in the nonrapid-equilibrium mechanism. We suggest that the proposed kinetic mechanism and asymmetric character in MtPPAT ligand binding may provide a means of reaction and pathway regulation in addition to that of the

  10. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis

    NASA Astrophysics Data System (ADS)

    Giancaspero, Teresa Anna; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina Maria; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-04-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in energetic metabolism, epigenetics, protein folding, as well as in a number of diverse regulatory processes. The problem of localisation of flavin cofactor synthesis events and in particular of the FAD synthase (EC 2.7.7.2) in HepG2 cells is addressed here by confocal microscopy in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalysed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesising activity, hFADS is able to operate as a FAD "chaperone". The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear or a mitochondrial enzyme that is lysine specific demethylase 1 (LSD1, EC 1.-.-.-) and dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4), respectively which carry out similar reactions of oxidative demethylation, assisted by tetrahydrofolate used to form 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells.

  11. Kinetics of acyl transfer reactions in organic media catalysed by Candida antarctica lipase B.

    PubMed

    Martinelle, M; Hult, K

    1995-09-01

    The acyl transfer reactions catalysed by Candida antartica lipase B in organic media followed a bi-bi ping-pong mechanism, with competitive substrate inhibition by the alcohols used as acyl acceptors. The effect of organic solvents on Vm and Km was investigated. The Vm values in acetonitrile was 40-50% of those in heptane. High Km values in acetonitrile compared to those in heptane could partly be explained by an increased solvation of the substrates in acetonitrile. Substrate solvation caused a 10-fold change in substrate specificity, defined as (Vm/Km)ethyl octanoate/(Vm/Km)octanoic acid, going from heptane to acetonitrile. Deacylation was the rate determining step for the acyl transfer in heptane with vinyl- and ethyl octanoate as acyl donors and (R)-2-octanol as acyl acceptor. With 1-octanol, a rate determining deacylation step in heptane was indicated using the same acyl donors. Using 1-octanol as acceptor in heptane, S-ethyl thiooctanoate had a 25- to 30-fold lower Vm/Km value and vinyl octanoate a 4-fold higher Vm/Km value than that for ethyl octanoate. The difference showed to be a Km effect for vinyl octanoate and mainly a Km effect for S-ethyl thiooctanoate. The Vm values of the esterification of octanoic acid with different alcohols was 10-30-times lower than those for the corresponding transesterification of ethyl octanoate. The low activity could be explained by a low pH around the enzyme caused by the acid or a withdrawing of active enzyme by nonproductive binding by the acid.

  12. Expression, Purification and Characterization of Enoyl-ACP Reductase II, FabK, from Porphyromonas gingivalis

    PubMed Central

    Hevener, Kirk E.; Mehboob, Shahila; Boci, Teuta; Truong, Kent; Santarsiero, Bernard D.; Johnson, Michael E.

    2012-01-01

    The rapid rise in bacterial drug resistance coupled with the low number of novel antimicrobial compounds in the discovery pipeline has led to a critical situation requiring the expedient discovery and characterization of new antimicrobial drug targets. Enzymes in the bacterial fatty acid synthesis pathway, FAS-II, are distinct from their mammalian counterparts, FAS-I, in terms of both structure and mechanism. As such, they represent attractive targets for the design of novel antimicrobial compounds. Enoyl-acyl carrier protein reductase II, FabK, is a key, rate-limiting enzyme in the FAS-II pathway for several bacterial pathogens. The organism, Porphyromonas gingivalis, is a causative agent of chronic periodontitis that affects up to 25% of the U.S. population and incurs a high national burden in terms of cost of treatment. P. gingivalis expresses FabK as the sole enoyl reductase enzyme in its FAS-II cycle, which makes this a particularly appealing target with potential for selective antimicrobial therapy. Herein we report the molecular cloning, expression, purification and characterization of the FabK enzyme from P. gingivalis, only the second organism from which this enzyme has been isolated. Characterization studies have shown that the enzyme is a flavoprotein, the reaction dependent upon FMN and NADPH and proceeding via a Ping-Pong Bi-Bi mechanism to reduce the enoyl substrate. A sensitive assay measuring the fluorescence decrease of NADPH as it is converted to NADP+ during the reaction has been optimized for high-throughput screening. Finally, protein crystallization conditions have been identified which led to protein crystals that diffract x-rays to high resolution. PMID:22820244

  13. Remaining challenges in cellular flavin cofactor homeostasis and flavoprotein biogenesis

    PubMed Central

    Giancaspero, Teresa A.; Colella, Matilde; Brizio, Carmen; Difonzo, Graziana; Fiorino, Giuseppina M.; Leone, Piero; Brandsch, Roderich; Bonomi, Francesco; Iametti, Stefania; Barile, Maria

    2015-01-01

    The primary role of the water-soluble vitamin B2 (riboflavin) in cell biology is connected with its conversion into FMN and FAD, the cofactors of a large number of dehydrogenases, oxidases and reductases involved in a broad spectrum of biological activities, among which energetic metabolism and chromatin remodeling. Subcellular localisation of FAD synthase (EC 2.7.7.2, FADS), the second enzyme in the FAD forming pathway, is addressed here in HepG2 cells by confocal microscopy, in the frame of its relationships with kinetics of FAD synthesis and delivery to client apo-flavoproteins. FAD synthesis catalyzed by recombinant isoform 2 of FADS occurs via an ordered bi-bi mechanism in which ATP binds prior to FMN, and pyrophosphate is released before FAD. Spectrophotometric continuous assays of the reconstitution rate of apo-D-aminoacid oxidase with its cofactor, allowed us to propose that besides its FAD synthesizing activity, hFADS is able to operate as a FAD “chaperone.” The physical interaction between FAD forming enzyme and its clients was further confirmed by dot blot and immunoprecipitation experiments carried out testing as a client either a nuclear lysine-specific demethylase 1 (LSD1) or a mitochondrial dimethylglycine dehydrogenase (Me2GlyDH, EC 1.5.8.4). Both enzymes carry out similar reactions of oxidative demethylation, in which tetrahydrofolate is converted into 5,10-methylene-tetrahydrofolate. A direct transfer of the cofactor from hFADS2 to apo-dimethyl glycine dehydrogenase was also demonstrated. Thus, FAD synthesis and delivery to these enzymes are crucial processes for bioenergetics and nutri-epigenetics of liver cells. PMID:25954742

  14. Dissecting the Catalytic Mechanism of Betaine-Homocysteine S-Methyltransferase Using Intrinsic Tryptophan Fluorescence and Site-Directed Mutagenesis

    SciTech Connect

    Castro, C.; Gratson, A.A.; Evans, J.C.; Jiracek, J.; Collinsova, M.; Ludwig, M.L.; Garrow, T.A.

    2010-03-05

    Betaine-homocysteine S-methyltransferase (BHMT) is a zinc-dependent enzyme that catalyzes the transfer of a methyl group from glycine betaine (Bet) to homocysteine (Hcy) to form dimethylglycine (DMG) and methionine (Met). Previous studies in other laboratories have indicated that catalysis proceeds through the formation of a ternary complex, with a transition state mimicked by the inhibitor S-({delta}-carboxybutyl)-l-homocysteine (CBHcy). Using changes in intrinsic tryptophan fluorescence to determine the affinity of human BHMT for substrates, products, or CBHcy, we now demonstrate that the enzyme-substrate complex reaches its transition state through an ordered bi-bi mechanism in which Hcy is the first substrate to bind and Met is the last product released. Hcy, Met, and CBHcy bind to the enzyme to form binary complexes with K{sub d} values of 7.9, 6.9, and 0.28 {micro}M, respectively. Binary complexes with Bet and DMG cannot be detected with fluorescence as a probe, but Bet and DMG bind tightly to BHMT-Hcy to form ternary complexes with K{sub d} values of 1.1 and 0.73 {micro}M, respectively. Mutation of each of the seven tryptophan residues in human BHMT provides evidence that the enzyme undergoes two distinct conformational changes that are reflected in the fluorescence of the enzyme. The first is induced when Hcy binds, and the second, when Bet binds. As predicted by the crystal structure of BHMT, the amino acids Trp44 and Tyr160 are involved in binding Bet, and Glu159 in binding Hcy. Replacing these residues by site-directed mutagenesis significantly reduces the catalytic efficiency (V{sub max}/K{sub m}) of the enzyme. Replacing Tyr77 with Phe abolishes enzyme activity.

  15. Development and evaluation of a spatially-explicit index of Chesapeake Bay health.

    PubMed

    Williams, Michael; Longstaff, Ben; Buchanan, Claire; Llansó, Roberto; Dennison, William

    2009-01-01

    In an effort to better portray changing health conditions in Chesapeake Bay and support restoration efforts, a Bay Health Index (BHI) was developed to assess the ecological effects of nutrient and sediment loading on 15 regions of the estuary. Three water quality and three biological measures were combined to formulate the BHI. Water quality measures of chlorophyll-a, dissolved oxygen, and Secchi depth were averaged to create the Water Quality Index (WQI), and biological measures of the phytoplankton and benthic indices of biotic integrity (P-IBI and B-IBI, respectively) and the area of submerged aquatic vegetation (SAV) were averaged to create the Biotic Index (BI). The WQI and BI were subsequently averaged to give a BHI value representing ecological conditions over the growing season (i.e., March-October). Lower chlorophyll-a concentrations, higher dissolved oxygen concentrations, deeper Secchi depths, higher phytoplankton and benthic indices relative to ecological health-based thresholds, and more extensive SAV area relative to restoration goal areas, characterized the least-impaired regions. The WQI, P-IBI and BHI were significantly correlated with (1) regional river flow (r=-0.64, -0.57 and -0.49, respectively; p<0.01), (2) nitrogen (N), phosphorus (P) and sediment loads (all positively correlated with flow), and (3) the sum of developed and agricultural land use (highest annual r(2)=0.86, 0.71 and 0.68, respectively) in most reporting regions, indicating that the BHI is strongly regulated by nutrient and sediment loads from these land uses. The BHI uses ecological health-based thresholds that give an accurate representation of the health conditions in Chesapeake Bay and was the basis for an annual, publicly released environmental report card that debuted in 2007.

  16. Recombinant Escherichia coli GMP reductase: kinetic, catalytic and chemical mechanisms, and thermodynamics of enzyme-ligand binary complex formation.

    PubMed

    Martinelli, Leonardo Krás Borges; Ducati, Rodrigo Gay; Rosado, Leonardo Astolfi; Breda, Ardala; Selbach, Bruna Pelegrim; Santos, Diógenes Santiago; Basso, Luiz Augusto

    2011-04-01

    Guanosine monophosphate (GMP) reductase catalyzes the reductive deamination of GMP to inosine monophosphate (IMP). GMP reductase plays an important role in the conversion of nucleoside and nucleotide derivatives of guanine to adenine nucleotides. In addition, as a member of the purine salvage pathway, it also participates in the reutilization of free intracellular bases. Here we present cloning, expression and purification of Escherichia coli guaC-encoded GMP reductase to determine its kinetic mechanism, as well as chemical and thermodynamic features of this reaction. Initial velocity studies and isothermal titration calorimetry demonstrated that GMP reductase follows an ordered bi-bi kinetic mechanism, in which GMP binds first to the enzyme followed by NADPH binding, and NADP(+) dissociates first followed by IMP release. The isothermal titration calorimetry also showed that GMP and IMP binding are thermodynamically favorable processes. The pH-rate profiles showed groups with apparent pK values of 6.6 and 9.6 involved in catalysis, and pK values of 7.1 and 8.6 important to GMP binding, and a pK value of 6.2 important for NADPH binding. Primary deuterium kinetic isotope effects demonstrated that hydride transfer contributes to the rate-limiting step, whereas solvent kinetic isotope effects arise from a single protonic site that plays a modest role in catalysis. Multiple isotope effects suggest that protonation and hydride transfer steps take place in the same transition state, lending support to a concerted mechanism. Pre-steady-state kinetic data suggest that product release does not contribute to the rate-limiting step of the reaction catalyzed by E. coli GMP reductase.

  17. Structural comparison between the open and closed forms of citrate synthase from Thermus thermophilus HB8.

    PubMed

    Kanamori, Eiji; Kawaguchi, Shin-Ichi; Kuramitsu, Seiki; Kouyama, Tsutomu; Murakami, Midori

    2015-01-01

    The crystal structures of citrate synthase from the thermophilic eubacteria Thermus thermophilus HB8 (TtCS) were determined for an open form at 1.5 Å resolution and for closed form at 2.3 Å resolution, respectively. In the absence of ligands TtCS in the open form was crystalized into a tetragonal form with a single subunit in the asymmetric unit. TtCS was also co-crystallized with citrate and coenzyme-A to form an orthorhombic crystal with two homodimers in the asymmetric unit. Citrate and CoA are found in the active site situated between the large domain and the small domain in all subunit whereas the complex shows two distinct closed conformations, the fully closed form and partially closed form. Structural comparisons are performed to describe conformational changes associated with binding of products of TtCS. Upon binding of citrate, basic residues in the active site move toward citrate and make a hydrogen bond network in the active site, inducing a large-scale rotation of the small domain relative to the large domain. CoA is sandwiched between the small and large domains and then the cysteamine tail is inserted into the active site with a cooperative rotation around mainchain dihedrals in the hinge region connecting helices M and N. According to this rotation these helices are extended to close the active site completely. The considerable flexibility and structural rearrangements in the hinge region are crucial for an ordered bibi reaction in catalysis for microbial CSs.

  18. Three Dimensional Dirac Semimetals

    NASA Astrophysics Data System (ADS)

    Zaheer, Saad

    2014-03-01

    Dirac points on the Fermi surface of two dimensional graphene are responsible for its unique electronic behavior. One can ask whether any three dimensional materials support similar pseudorelativistic physics in their bulk electronic spectra. This possibility has been investigated theoretically and is now supported by two successful experimental demonstrations reported during the last year. In this talk, I will summarize the various ways in which Dirac semimetals can be realized in three dimensions with primary focus on a specific theory developed on the basis of representations of crystal spacegroups. A three dimensional Dirac (Weyl) semimetal can appear in the presence (absence) of inversion symmetry by tuning parameters to the phase boundary separating a bulk insulating and a topological insulating phase. More generally, we find that specific rules governing crystal symmetry representations of electrons with spin lead to robust Dirac points at high symmetry points in the Brillouin zone. Combining these rules with microscopic considerations identifies six candidate Dirac semimetals. Another method towards engineering Dirac semimetals involves combining crystal symmetry and band inversion. Several candidate materials have been proposed utilizing this mechanism and one of the candidates has been successfully demonstrated as a Dirac semimetal in two independent experiments. Work carried out in collaboration with: Julia A. Steinberg, Steve M. Young, J.C.Y. Teo, C.L. Kane, E.J. Mele and Andrew M. Rappe.

  19. Revisiting the problem of Jewish bioethics: the case of terminal care.

    PubMed

    Barilan, Y Michael

    2003-06-01

    This paper examines the main Jewish sources relevant to end-of-life ethics, two Talmudic stories, the early modern code of law (Shulhan Aruch), and contemporary Halakhaic (religious law) responsa. Some Orthodox rabbis object to the use of artificial life support that prolongs the life of a dying patient and permit its active discontinuation when the patient is suffering. Other rabbis believe that every medical measure must be taken in order to prolong life. The context of the discussion is the most recent release of the "Steinberg Report," which proposes a law regulating end-of-life issues in Israel. It is argued that the Orthodox rabbis base their views on a strongly positivist concept of religious law. The rabbis deliberate the law as a manifestation of the will of God and try to stretch the law as much as possible in order to benefit the patient, even when it is good for the patient to die. Direct and active actions that kill are prohibited; certain forms of passive euthanasia and contrivances that terminate life support without needing direct human action are accepted.

  20. Cookoff Response of PBXN-109: Material Characterization and ALE3D Thermal Predictions

    SciTech Connect

    McClelland, M A; Tran, T D; Cunningham, B J; Weese, R K; Maienschein, J L

    2001-05-29

    Materials properties measurements are made for the RDX-based explosive, PBXN-109, and initial ALE3D model predictions are given for the cookoff temperature in a U.S. Navy test. This work is part of an effort in the U.S. Navy and Department of Energy (DOE) laboratories to understand the thermal explosion behavior of this material. Benchmark cookoff experiments are being performed by the U.S. Navy to validate DOE materials models and computer codes. The ALE3D computer code can model the coupled thermal, mechanical, and chemical behavior of heating, ignition, and explosion in cookoff tests. In our application, a standard three-step step model is selected for the chemical kinetics. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. Materials characterization measurements are given for thermal expansion, heat capacity, shear modulus, bulk modulus, and One-Dimensional-Time-to-Explosion (ODTX). These measurements and those of the other project participants are used to determine parameters in the ALE3D chemical, mechanical, and thermal models. Time-dependent, two-dimensional results are given for the temperature and material expansion. The results show predicted cookoff temperatures slightly higher than the measured values.

  1. ALE3D Model Predictions and Experimental Analysis of the Cookoff Response of Comp B*

    SciTech Connect

    Maienschein, J L; McClelland, M A; Wardell, J F; Reaugh, J E; Nichols, A L; Tran, T D

    2003-11-24

    ALE3D simulations are presented for the thermal explosion of Comp B (RDX,TNT) in a Scaled Thermal Explosion Experiment (STEX). Candidate models and numerical strategies are being tested using the ALE3D code which simulates the coupled thermal, mechanical, and chemical behavior during heating, ignition, and explosion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A three-step chemical kinetics model is used for each of the RDX and TNT reaction sequences during the heating and ignition phases, and a pressure-dependent deflagration model is employed during the rapid expansion. Parameters for the three-step kinetics model are specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate are employed to determine parameters in the burn front model. We compare model predictions to measurements for temperature fields, ignition temperature, and tube wall strain during the heating, ignition, and explosive phases.

  2. Fine Tuning of Tissues' Viscosity and Surface Tension through Contractility Suggests a New Role for α-Catenin

    PubMed Central

    Stirbat, Tomita Vasilica; Mgharbel, Abbas; Bodennec, Selena; Ferri, Karine; Mertani, Hichem C.; Rieu, Jean-Paul; Delanoë-Ayari, Hélène

    2013-01-01

    What governs tissue organization and movement? If molecular and genetic approaches are able to give some answers on these issues, more and more works are now giving a real importance to mechanics as a key component eventually triggering further signaling events. We chose embryonic cell aggregates as model systems for tissue organization and movement in order to investigate the origin of some mechanical constraints arising from cells organization. Steinberg et al. proposed a long time ago an analogy between liquids and tissues and showed that indeed tissues possess a measurable tissue surface tension and viscosity. We question here the molecular origin of these parameters and give a quantitative measurement of adhesion versus contractility in the framework of the differential interfacial tension hypothesis. Accompanying surface tension measurements by angle measurements (at vertexes of cell-cell contacts) at the cell/medium interface, we are able to extract the full parameters of this model: cortical tensions and adhesion energy. We show that a tunable surface tension and viscosity can be achieved easily through the control of cell-cell contractility compared to cell-medium one. Moreover we show that -catenin is crucial for this regulation to occur: these molecules appear as a catalyser for the remodeling of the actin cytoskeleton underneath cell-cell contact, enabling a differential contractility between the cell-medium and cell-cell interface to take place. PMID:23390488

  3. Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

    NASA Astrophysics Data System (ADS)

    Krahe, Michael; Wenzel, Iris; Lin, Kao-Nung; Fischer, Julia; Goldmann, Joseph; Kästner, Markus; Fütterer, Claus

    2013-03-01

    We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid-spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients, which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels, allowing us to observe the deformation modes over longer periods of time. We found increasing mechanical fluctuations which break the toroidal symmetry, and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to single-cell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellular actin ring assembled along the toroid's inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin-driven length fluctuations of supra-cellular F-actin bundles (myonemes) in the outer cell layer. This paper is dedicated to Malcolm Steinberg.

  4. Pubertal development and behavior: hormonal activation of social and motivational tendencies.

    PubMed

    Forbes, Erika E; Dahl, Ronald E

    2010-02-01

    Adolescence is a time of dramatic changes including rapid physical growth, the onset of sexual maturation, the activation of new drives and motivations, and a wide array of social and affective changes and challenges. This review focuses on behavioral changes in this interval and is organized by the claim that a key set of these adolescent changes are part of a more general re-orientation of social behavior. More specifically we hypothesize that pubertal maturation is associated with the activation of social and motivational tendencies, which in turn influence behavior and emotion in adolescence depending upon interactions with social context. We focus on evidence for two examples of these motivational changes: (1) increases in sensation-seeking (motivational tendency to want to experience high-intensity, exciting experiences) and (2) stronger natural interest in--and pursuit of--contact with peers and potential romantic partners. We consider how these motivational changes contribute to the broader social re-orientation of adolescence, including exploration of social experiences, development of skills and knowledge relevant to taking on adult social roles, individuation from family, and establishment of an individual identity, all of which represent core developmental tasks during this period in the life span (Blakemore, 2008; Dahl & Spear, 2004; Steinberg & Morris, 2000). The paper also emphasizes the importance of investigating and understanding the direct influences of puberty on behavior and disentangling these from the broader set of changes during adolescent development.

  5. NIMH during the tenure of Director Lewis L. Judd, M.D. (1987-1990): the decade of the brain and the four national research plans.

    PubMed

    Judd, L L

    1998-09-01

    My tenure at NIMH was an exhilarating, heady time of great satisfaction and achievement for all of us at the Institute. I have great affection and loyalty for NIMH, but my fondest memories are of the individuals who led and staffed the Institute's programs while I was there. One of the most gratifying aspects of my tenure was the opportunity to recruit and appoint people to new responsibilities and to interact with and support them as they grew into and beyond their positions of leadership within NIMH. When I left NIMH, I felt that the Institute's managers and staff were unparalleled in their creativity, competence, commitment, loyalty, and sheer hard work on behalf of the Institute and our field. My thanks and deep gratitude genuinely go out to the entire staff at NIMH during my tenure. However, a special debt of gratitude is owed to a group of colleagues and friends who, at my request, carried very heavy responsibilities and excelled in meeting them: Dr. Alan Leshner (Deputy Director of NIMH, now Director of NIDA); Dr. Stephen Koslow, Dr. Stephen Paul, Dr. Jack "Jay" Burke, Dr. David Segal, Dr. Ira Glick, Dr. Ellen Stover, Dr. Irene Levine, Dr. Daryl Kirsch, Dr. Rex Cowdry, Dr. Sam Keith, Dr. Delores Paron, Leroy Goldman, Richard Pine, William Fitzsimmons, Gordon Seidenberg, Lewis Steinberg, Gemma Weiblinger, George Halter, and my invaluable assistant, Margaret Shanley. PMID:9736861

  6. The mechanics of cellular compartmentalization as a model for tumor spreading

    NASA Astrophysics Data System (ADS)

    Fritsch, Anatol; Pawlizak, Steve; Zink, Mareike; Kaes, Josef A.

    2012-02-01

    Based on a recently developed surgical method of Michael H"ockel, which makes use of cellular confinement to compartments in the human body, we study the mechanics of the process of cell segregation. Compartmentalization is a fundamental process of cellular organization and occurs during embryonic development. A simple model system can demonstrate the process of compartmentalization: When two populations of suspended cells are mixed, this mixture will eventually segregate into two phases, whereas mixtures of the same cell type will not. In the 1960s, Malcolm S. Steinberg formulated the so-called differential adhesion hypothesis which explains the segregation in the model system and the process of compartmentalization by differences in surface tension and adhesiveness of the interacting cells. We are interested in to which extend the same physical principles affect tumor growth and spreading between compartments. For our studies, we use healthy and cancerous breast cell lines of different malignancy as well as primary cells from human cervix carcinoma. We apply a set of techniques to study their mechanical properties and interactions. The Optical Stretcher is used for whole cell rheology, while Cell-cell-adhesion forces are directly measured with a modified AFM. In combination with 3D segregation experiments in droplet cultures we try to clarify the role of surface tension in tumor spreading.

  7. Computational Modeling of Tissue Self-Assembly

    NASA Astrophysics Data System (ADS)

    Neagu, Adrian; Kosztin, Ioan; Jakab, Karoly; Barz, Bogdan; Neagu, Monica; Jamison, Richard; Forgacs, Gabor

    As a theoretical framework for understanding the self-assembly of living cells into tissues, Steinberg proposed the differential adhesion hypothesis (DAH) according to which a specific cell type possesses a specific adhesion apparatus that combined with cell motility leads to cell assemblies of various cell types in the lowest adhesive energy state. Experimental and theoretical efforts of four decades turned the DAH into a fundamental principle of developmental biology that has been validated both in vitro and in vivo. Based on computational models of cell sorting, we have developed a DAH-based lattice model for tissues in interaction with their environment and simulated biological self-assembly using the Monte Carlo method. The present brief review highlights results on specific morphogenetic processes with relevance to tissue engineering applications. Our own work is presented on the background of several decades of theoretical efforts aimed to model morphogenesis in living tissues. Simulations of systems involving about 105 cells have been performed on high-end personal computers with CPU times of the order of days. Studied processes include cell sorting, cell sheet formation, and the development of endothelialized tubes from rings made of spheroids of two randomly intermixed cell types, when the medium in the interior of the tube was different from the external one. We conclude by noting that computer simulations based on mathematical models of living tissues yield useful guidelines for laboratory work and can catalyze the emergence of innovative technologies in tissue engineering.

  8. NIMH during the tenure of Director Lewis L. Judd, M.D. (1987-1990): the decade of the brain and the four national research plans.

    PubMed

    Judd, L L

    1998-09-01

    My tenure at NIMH was an exhilarating, heady time of great satisfaction and achievement for all of us at the Institute. I have great affection and loyalty for NIMH, but my fondest memories are of the individuals who led and staffed the Institute's programs while I was there. One of the most gratifying aspects of my tenure was the opportunity to recruit and appoint people to new responsibilities and to interact with and support them as they grew into and beyond their positions of leadership within NIMH. When I left NIMH, I felt that the Institute's managers and staff were unparalleled in their creativity, competence, commitment, loyalty, and sheer hard work on behalf of the Institute and our field. My thanks and deep gratitude genuinely go out to the entire staff at NIMH during my tenure. However, a special debt of gratitude is owed to a group of colleagues and friends who, at my request, carried very heavy responsibilities and excelled in meeting them: Dr. Alan Leshner (Deputy Director of NIMH, now Director of NIDA); Dr. Stephen Koslow, Dr. Stephen Paul, Dr. Jack "Jay" Burke, Dr. David Segal, Dr. Ira Glick, Dr. Ellen Stover, Dr. Irene Levine, Dr. Daryl Kirsch, Dr. Rex Cowdry, Dr. Sam Keith, Dr. Delores Paron, Leroy Goldman, Richard Pine, William Fitzsimmons, Gordon Seidenberg, Lewis Steinberg, Gemma Weiblinger, George Halter, and my invaluable assistant, Margaret Shanley.

  9. Reciprocal relations between perceived parental knowledge and adolescent substance use and delinquency: The moderating role of parent-teen relationship quality.

    PubMed

    Abar, Caitlin C; Jackson, Kristina M; Wood, Mark

    2014-09-01

    The current study prospectively examined hypothesized short- and long-term reciprocal relations between perceived parental knowledge and adolescent heavy episodic drinking, marijuana use, and delinquency. Using the contextual model of parenting style (Darling & Steinberg, 1993), we examined the extent to which the bidirectional nature of associations between knowledge and adolescent outcomes is dependent on a facet of parenting style: the quality of the parent-child relationship. Data came from the first 4 waves of the National Longitudinal Study of Youth 1997. The sample for the current study consisted of 5,419 students between 12 and 14 years of age at baseline (52% male) surveyed annually for 4 years. Parallel process, autoregressive latent trajectory models were used to examine relations between initial levels and change over time in perceived parental knowledge and adolescent risk, and short-term cross-lagged paths were included to examine bidirectionality while accounting for long-term associations. Results showed significant short-term and long-term bidirectionality between perceived parental knowledge and adolescent outcomes, with parent effects on students and student effects on parents. Long-term associations across constructs were negative, whereas short-term associations were positive. These reciprocal associations were shown to differ across levels of parent-child relationship quality with regard to adolescent heavy episodic drinking and delinquency, providing support for the contextual model of parenting style. Implications for future work on parent-child bidirectional relationships and parent-based interventions are discussed.

  10. Hereditary pancreatitis associated with a balanced translocation (5q;11p)

    SciTech Connect

    Dasouki, J.J.; Summar, M.L.; Mixon, C.

    1994-09-01

    Dominantly inherited pancreatitis was first described by Comfort and Steinberg in 1952. It is estimated to account for <1% of all childhood pancreatitis cases. Patients as young as 17 months of age were reported. Presentation varies from acute abdominal pain mimicking familial Mediterranean fever to more chronic steatorrhea causing malabsorption. Urinary excretion of cystine in both affected and unaffected family members is an unexplained feature. Our 37 year old, G{sub 1}P{sub 0{minus}1} proband is known to have familial pancreatitis which complicated her current pregnancy. Family history was also positive in her mother and a sister who has a 12 year old daughter with recurrent abdominal pain. The proband sought genetic counselling because her amniocentesis showed a male fetus with an apparently balanced reciprocal translocation: t(5;11)(q13;p15). A detailed fetal ultrasound examination failed to show any abnormality. On chromosomal analysis, the proband was found to have a similar translocation. Her plasma aminogram was normal, however the spot and 24 hour urine aminograms demonstrated generalized aminoaciduria. This is the first report of hereditary pancreatitis with a segregating balanced autosomal translocation which may be etiologically important. In addition, unlike what was described previously, the aminoaciduria was generalized and nonspecific. Molecular analysis of the genes located in the breakpoint region may prove to be helpful in identifying the responsible gene and the delineation of the pathogenesis of this developmental disorder.

  11. Modeling Hemispheric Detonation Experiments in 2-Dimensions

    SciTech Connect

    Howard, W M; Fried, L E; Vitello, P A; Druce, R L; Phillips, D; Lee, R; Mudge, S; Roeske, F

    2006-06-22

    Experiments have been performed with LX-17 (92.5% TATB and 7.5% Kel-F 800 binder) to study scaling of detonation waves using a dimensional scaling in a hemispherical divergent geometry. We model these experiments using an arbitrary Lagrange-Eulerian (ALE3D) hydrodynamics code, with reactive flow models based on the thermo-chemical code, Cheetah. The thermo-chemical code Cheetah provides a pressure-dependent kinetic rate law, along with an equation of state based on exponential-6 fluid potentials for individual detonation product species, calibrated to high pressures ({approx} few Mbars) and high temperatures (20000K). The parameters for these potentials are fit to a wide variety of experimental data, including shock, compression and sound speed data. For the un-reacted high explosive equation of state we use a modified Murnaghan form. We model the detonator (including the flyer plate) and initiation system in detail. The detonator is composed of LX-16, for which we use a program burn model. Steinberg-Guinan models5 are used for the metal components of the detonator. The booster and high explosive are LX-10 and LX-17, respectively. For both the LX-10 and LX-17, we use a pressure dependent rate law, coupled with a chemical equilibrium equation of state based on Cheetah. For LX-17, the kinetic model includes carbon clustering on the nanometer size scale.

  12. Tunneling Time and Weak Measurement in Strong Field Ionization

    NASA Astrophysics Data System (ADS)

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R.; Gordon, Daniel F.; Landsman, Alexandra S.

    2016-06-01

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process.

  13. Joe L. Kincheloe: Genies and wishes: a review of Key Works in Critical Pedagogy

    NASA Astrophysics Data System (ADS)

    Ali-Khan, Carolyne; Siry, Christina

    2012-06-01

    We review Key Works in Critical Pedagogy: Joe L. Kincheloe edited by kecia hayes, Shirley R. Steinberg and Kenneth Tobin, which gathers the seminal works of Joe. L. Kincheloe and pairs them with contemporary scholars who respond to and push forward Kincheloe's work. The chapters of Key Works in Critical Pedagogy are arranged to begin with Kincheloe's earlier works, going back to 1991, and progress through to the last works he published before his death in 2008. Through this format, readers are able to see the evolution of Kincheloe's scholarship. In addition to this, a few key authors provide a behind the scenes look at the man who wrote the texts. As Kincheloe's ideas and the ideas of the scholars that he drew from are presented, applied, reworked and reconfigured, they shift and transform. The response chapters work to (in effect) show us the notes in the margins of scholars who have been influenced by Kincheloe's ideas. Using the metaphors of lamps and wish-granting genies, we argue that this book is an important tool in illuminating the way forward for social justice work, published in an historical moment that requires precisely this.

  14. Relationships Between Adolescent Sexual Outcomes and Exposure to Sex in Media: Robustness to Propensity-Based Analysis.

    PubMed

    Collins, Rebecca L; Martino, Steven C; Elliott, Marc N; Miu, Angela

    2011-03-01

    Adolescent sexual health is a substantial problem in the U.S., and two recent studies have linked adolescent sexual behavior and/or outcomes to youths' exposure to sex in the media. Both studies had longitudinal survey designs and used covariate-adjusted regression analysis. Steinberg and Monahan (2010) reanalyzed data from one of these studies (Brown et al., 2006) using a propensity-score approach, arguing that this method better addresses the possibility of unobserved confounders. Based on their reanalysis, which found no relationship between media exposure and sexual behavior, they concluded that "Adolescents' Exposure to Sexy Media Does Not Hasten the Initiation of Sexual Intercourse." We subject data from the second study (Collins et al., 2004; Chandra et al., 2008) to reanalysis using a propensity-score approach. We find only modest reductions in two of the three previously documented associations, and no reduction in the third. Based on these findings, we conclude that there is an association between exposure to sex in the media and adolescent sexual outcomes. While the evidence does not prove causality, it is sufficient to advise caution among parents, develop interventions for youth, and work with media producers and distributors to reduce youth exposure to sexual content. PMID:24839301

  15. Tunneling Time and Weak Measurement in Strong Field Ionization.

    PubMed

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R; Gordon, Daniel F; Landsman, Alexandra S

    2016-06-10

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process. PMID:27341232

  16. Quark Matter 2011 (QM11) Quark Matter 2011 (QM11)

    NASA Astrophysics Data System (ADS)

    2011-12-01

    International Advisory Committee Antinori, FedericoPaic, Guy Braun-Munzinger, PeterPajares, Carlos Cifarelli, LuisaPeitzmann, Thomas Erazmus, BarbaraRedlich, Krzysztof Eskola, KariRiccati, Lodovico Gaardhøje, Jens JørgenRoland, Gunther Gale, CharlesRoy, Christelle Gelis, FrancoisSchukraft, Jürgen Giubellino, PaoloSinha, Bikash Greiner, CarstenSrivastava, Dinesh Gyulassy, MiklosStachel, Johanna Harris, JohnSteinberg, Peter Hatsuda, TetsuoStroth, Joachim Heinz, UlrichSugitate, Toru Jacak, BarbaraTserruya, Itzhak Karsch, FrithjofVelkovska, Julia Kharzeev, DimaWang, Enke Kodama, TakeshiWang, Xin, Nian Lévai, PéterWessels, Johannes Manko, VladislavXu, Nu Müller, BerndtZajc, William Ollitrault, Jean-Yves Organizing Committee Arleo, FrancoisDupieux, Pascal Bastid, NicoleFurget, Christophe Bourgeois, Marie-LaureGranier de Cassagnac, Raphael Bregant, MarcoGuernane, Rachid Carminati, FedericoHervet, Carnita Castillo, JavierKuhn, Christian Cheynis, BrigitteOlivier, Nathalie Conesa, DelValle, Zaida Connor, MichelleRenshall, Lucy Crochet, PhilippeSuire, Christophe Delagrange, HuguesTihinen, Ulla Program Committee Schutz, Yves (Chair)Baldisseri, Alberto Wiedemann, Urs (co-Chair)Safarik, Karel Aurenche, Patrick

  17. Bilocal current densities and mean trajectories in a Young interferometer with two Gaussian slits and two detectors

    SciTech Connect

    Withers, L. P.; Narducci, F. A.

    2015-06-15

    The recent single-photon double-slit experiment of Steinberg et al., based on a weak measurement method proposed by Wiseman, showed that, by encoding the photon’s transverse momentum behind the slits into its polarization state, the momentum profile can subsequently be measured on average, from a difference of the separated fringe intensities for the two circular polarization components. They then integrated the measured average velocity field, to obtain the average trajectories of the photons enroute to the detector array. In this paper, we propose a modification of their experiment, to demonstrate that the average particle velocities and trajectories change when the mode of detection changes. The proposed experiment replaces a single detector by a pair of detectors with a given spacing between them. The pair of detectors is configured so that it is impossible to distinguish which detector received the particle. The pair of detectors is then analogous to the simple pair of slits, in that it is impossible to distinguish which slit the particle passed through. To establish the paradoxical outcome of the modified experiment, the theory and explicit three-dimensional formulas are developed for the bilocal probability and current densities, and for the average velocity field and trajectories as the particle wavefunction propagates in the volume of space behind the Gaussian slits. Examples of these predicted results are plotted. Implementation details of the proposed experiment are discussed.

  18. Frequency importance functions for a feature recognition test material.

    PubMed

    Duggirala, V; Studebaker, G A; Pavlovic, C V; Sherbecoe, R L

    1988-06-01

    The relative importance of different parts of the auditory spectrum to recognition of the Diagnostic Rhyme Test (DRT) and its six speech feature subtests was determined. Three normal hearing subjects were tested twice in each of 70 experimental conditions. The analytical procedures of French and Steinberg [J. Acoust. Soc. Am. 19, 90-119 (1947)] were applied to the data to derive frequency importance functions for each of the DRT subtests and the test as a whole over the frequency range 178-8912 Hz. For the DRT as a whole, the low frequencies were found to be more important than is the case for nonsense syllables. Importance functions for the feature subtests also differed from those for nonsense syllables and from each other as well. These results suggest that test materials loaded with different proportions of particular phonemes have different frequency importance functions. Comparison of the results with those from other studies suggests that importance functions depend to a degree on the available response options as well. PMID:3411027

  19. Cookoff Response of PBXN-109: Material Characterization and ALE3D Thermal Predictions

    SciTech Connect

    McClelland, M A; Tran, T D; Cunningham, B J; Weese, R K; Maienschein, J L

    2001-08-21

    Materials properties measurements are made for the RDX-based explosive, PBXN-109, and initial ALE3D model predictions are given for the cookoff temperature in a U.S. Navy test. This work is part of an effort in the U.S. Navy and Department of Energy (DOE) laboratories to understand the thermal explosion behavior of this material. Benchmark cookoff experiments are being performed by the U.S. Navy to validate DOE materials models and computer codes. The ALE3D computer code can model the coupled thermal, mechanical, and chemical behavior of heating, ignition, and explosion in cookoff tests. In our application, a standard three-step step model is selected for the chemical kinetics. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. Materials characterization measurements are given for thermal expansion, heat capacity, shear modulus, bulk modulus, and One-Dimensional-Time-to-Explosion (ODTX). These measurements and those of the other project participants are used to determine parameters in the ALE3D chemical, mechanical, and thermal models. Time-dependent, two-dimensional results are given for the temperature and material expansion. The results show predicted cookoff temperatures slightly higher than the measured values.

  20. ALE3D Model Predictions and Materials Characterization for the Cookoff Response of PBXN-109

    SciTech Connect

    McClelland, M A; Maienschein, J L; Nichols, A L; Wardell, J F; Atwood, A I; Curran, P O

    2002-03-19

    ALE3D simulations are presented for the thermal explosion of PBXN-109 (RDX, AI, HTPB, DOA) in support of an effort by the U. S. Navy and Department of Energy (DOE) to validate computational models. The U.S. Navy is performing benchmark tests for the slow cookoff of PBXN-109 in a sealed tube. Candidate models are being tested using the ALE3D code, which can simulate the coupled thermal, mechanical, and chemical behavior during heating, ignition, and explosion. The strength behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the Equation Of State (EOS) for the solid and gas species, respectively. A void model is employed to represent the air in gaps. ALE3D model 'parameters are specified using measurements of thermal and mechanical properties including thermal expansion, heat capacity, shear modulus, and bulk modulus. A standard three-step chemical kinetics model is used during the thermal ramp, and a pressure-dependent burn front model is employed during the rapid expansion. Parameters for the three-step kinetics model are specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate of pristine and thermally damaged material are employed to determine parameters in the burn front model. Results are given for calculations in which heating, ignition, and explosion are modeled in a single simulation. We compare model results to measurements for the cookoff temperature and tube wall strain.

  1. The future of space science in the 21st century

    NASA Astrophysics Data System (ADS)

    Bonnet, R. M.

    2001-06-01

    Space Science helped the start of the open space race after the launch of Sputnik-1 in 1957. Conversely, the use of space vehicles during the cold war allowed the scientists to conduct many observations and make discoveries which have dramatically changed our views of our own Solar System and of the Universe. What will be the future of this activity in the next century, with the disappearance of the cold war justification and in the context of shrinking budgets? Is there a future for space exploration? For what benefit and how will space science programmes be conducted? Who will be the main players? Are there limits to our ability to explore? The pioneers of space research in the post-Sputnik-1 era, like J-L. Steinberg, had both an easier and a more difficult time than space scientists of today. Nevertheless, space science will only survive in the next century if it succeeds in reaching the deep interest and motivation of society at large.

  2. Modeling Propagation of Shock Waves in Metals

    SciTech Connect

    Howard, W M; Molitoris, J D

    2005-08-19

    We present modeling results for the propagation of strong shock waves in metals. In particular, we use an arbitrary Lagrange Eulerian (ALE3D) code to model the propagation of strong pressure waves (P {approx} 300 to 400 kbars) generated with high explosives in contact with aluminum cylinders. The aluminum cylinders are assumed to be both flat-topped and have large-amplitude curved surfaces. We use 3D Lagrange mechanics. For the aluminum we use a rate-independent Steinberg-Guinan model, where the yield strength and shear modulus depend on pressure, density and temperature. The calculation of the melt temperature is based on the Lindermann law. At melt the yield strength and shear modulus is set to zero. The pressure is represented as a seven-term polynomial as a function of density. For the HMX-based high explosive, we use a JWL, with a program burn model that give the correct detonation velocity and C-J pressure (P {approx} 390 kbars). For the case of the large-amplitude curved surface, we discuss the evolving shock structure in terms of the early shock propagation experiments by Sakharov.

  3. Bilocal current densities and mean trajectories in a Young interferometer with two Gaussian slits and two detectors

    NASA Astrophysics Data System (ADS)

    Withers, L. P.; Narducci, F. A.

    2015-06-01

    The recent single-photon double-slit experiment of Steinberg et al., based on a weak measurement method proposed by Wiseman, showed that, by encoding the photon's transverse momentum behind the slits into its polarization state, the momentum profile can subsequently be measured on average, from a difference of the separated fringe intensities for the two circular polarization components. They then integrated the measured average velocity field, to obtain the average trajectories of the photons enroute to the detector array. In this paper, we propose a modification of their experiment, to demonstrate that the average particle velocities and trajectories change when the mode of detection changes. The proposed experiment replaces a single detector by a pair of detectors with a given spacing between them. The pair of detectors is configured so that it is impossible to distinguish which detector received the particle. The pair of detectors is then analogous to the simple pair of slits, in that it is impossible to distinguish which slit the particle passed through. To establish the paradoxical outcome of the modified experiment, the theory and explicit three-dimensional formulas are developed for the bilocal probability and current densities, and for the average velocity field and trajectories as the particle wavefunction propagates in the volume of space behind the Gaussian slits. Examples of these predicted results are plotted. Implementation details of the proposed experiment are discussed.

  4. Critical Plastic Strain as a Criterion for Failure in Ballistic Impact Experiments of U/Ti and Ti64 Alloys

    NASA Astrophysics Data System (ADS)

    Herrmann, B.; Favorsky, V.; Zaretsky, E.; Shvarts, D.

    2006-07-01

    Strain localization and failure in U-0.75Ti and Ti-6Al-4V alloys were studied in symmetric (rod-on-rod) and reverse ballistic (disk-on-rod) impact experiments, accompanied by VISAR monitoring of the lateral sample surface velocity. Softly-recovered samples were metallurgically examined, and the experiments were numerically simulated using an AUTODYN™ 2-D code. Satisfactory reproduction of both the measured velocity profiles and the results of metallographic examination of the damage produced by adiabatic shearing were obtained by using the Steinberg-Cochran-Guinan-type constitutive equation (calibrated in preliminary planar impact experiments) and the AUTODYN™ built-in erosion function. A good agreement was found between strains, measured by using natural markers (martensite in U/Ti and texture in Ti64), corresponding to the onset of adiabatic shearing (0.5 - 1.0) and the value of the critical plastic strain used in the simulations as a criterion for triggering the erosion function (0.6 for both alloys). In the case of Ti64 the shearing is finalized by cracking at observed strain values of 1.0 - 1.5, whereas in the U/Ti the shear strain reaches values greater by at least one order of magnitude and is terminated by void growth and coalescence.

  5. 1-D and 2-D modeling of U-Ti alloy response in impact experiments

    NASA Astrophysics Data System (ADS)

    Hermann, B.; Favorsky, V.; Landau, A.; Shvarts, D.; Zaretsky, E. B.

    2003-09-01

    Dynamie response of a U-0.75wt%Ti alloy bas been studied in planar (disk-on-disk), reverse (disk-on-rod) and symmetric (rod-on-rod) ballistic impact experiments performed with a 25 mm light-gas gun. The impact velocities ranged between 100 and 500 m/see and the samples were softly recovered for further examination, revealing different degrees of spall fracture (planar impact) and of adiabatic shear bands (ballistic experiments). The back (planar experiments) and the lateral (ballistic experiments) surface velocities were continuously monitored by VISAR. The velocity profiles and the damage maps were simulated using a 2-D AUTODYN^TM Lagrangian finite differences code. Simulations of the planar experiments were performed with special attention to the compressive path of the loading cycle in order to calibrate a modified Steinberg-Cochran-Guinan (SCG) constitutive model. The Bauschinger effect and a single-parameter spall model were added to describe the unloading and tensile paths. The calibrated SCG model was then employed to simulate the ballistic experiments. An erosion AUTODYN built-in subroutine with a threshold value of plastic strain was chosen to describe the failure in the ballistic impact experiments. The results of the suggested experimental-numerical technique can be taken into account in estimating the different contributions to the shock-induced plastic deformation and failure.

  6. Reciprocal relations between perceived parental knowledge and adolescent substance use and delinquency: The moderating role of parent-teen relationship quality.

    PubMed

    Abar, Caitlin C; Jackson, Kristina M; Wood, Mark

    2014-09-01

    The current study prospectively examined hypothesized short- and long-term reciprocal relations between perceived parental knowledge and adolescent heavy episodic drinking, marijuana use, and delinquency. Using the contextual model of parenting style (Darling & Steinberg, 1993), we examined the extent to which the bidirectional nature of associations between knowledge and adolescent outcomes is dependent on a facet of parenting style: the quality of the parent-child relationship. Data came from the first 4 waves of the National Longitudinal Study of Youth 1997. The sample for the current study consisted of 5,419 students between 12 and 14 years of age at baseline (52% male) surveyed annually for 4 years. Parallel process, autoregressive latent trajectory models were used to examine relations between initial levels and change over time in perceived parental knowledge and adolescent risk, and short-term cross-lagged paths were included to examine bidirectionality while accounting for long-term associations. Results showed significant short-term and long-term bidirectionality between perceived parental knowledge and adolescent outcomes, with parent effects on students and student effects on parents. Long-term associations across constructs were negative, whereas short-term associations were positive. These reciprocal associations were shown to differ across levels of parent-child relationship quality with regard to adolescent heavy episodic drinking and delinquency, providing support for the contextual model of parenting style. Implications for future work on parent-child bidirectional relationships and parent-based interventions are discussed. PMID:25046124

  7. Testing the Teacher? Or Teaching the Test?

    NASA Astrophysics Data System (ADS)

    Moore, John W.

    2001-08-01

    Tests, including those written by someone other than the teacher, are a good thing. They provide one useful measure of the success of a student, course, teacher, or school. But too much of a good thing can cause serious, long-term harm. Let us resolve to use tests judiciously, thoughtfully, and appropriately, and to influence others to do the same.

    Literature Cited

    1. High Stakes Testing for Tracking, Promotion, and Graduation; Heubert, J. P.; Hauser, R. M., Eds.; National Academy Press: Washington, DC, 1999; (accessed Jun 2001).
    2. Steinberg, J.; Henriques, D. B. None of the Above; The New York Times May 21, 2001, p A1; May 22, 2001, p A1.
    3. Glenn, T.; Akin, M. Questioning Testing; School Administrator 1996, 53, 26.
    4. Klein, S. P.; Hamilton, L. S.; McCaffrey, D. F.; Stecher, B. M. What Do Test Scores in Texas Tell Us? Educ. Policy Anal. Arch. 2000, 8 (49); (accessed Jun 2001).
    5. Morris, B. R. School Testing Bandwagon Spawns Web Coaching Sites; The New York Times May 24, 2001, p D6.
    6. Goodnough, A. High Stakes of Fourth-Grade Tests Are Driving Off Veteran Teachers; The New York Times June 14, 2001, p A1.

    7. The clinical utility of CA 19-9 in pancreatic adenocarcinoma: diagnostic and prognostic updates.

      PubMed

      Poruk, Katherine E; Gay, D Z; Brown, K; Mulvihill, J D; Boucher, K M; Scaife, C L; Firpo, M A; Mulvihill, S J

      2013-03-01

      CA 19-9 and CEA are the most commonly used biomarkers for diagnosis and management of patients with pancreatic cancer. Since the original compendium by Steinberg in 1990, numerous studies have reported the use of CA 19-9 and, to a lesser extent, CEA in the diagnosis of pancreatic cancer. Here we update an evaluation of the accuracy of CA 19-9 and CEA, and, unlike previous reviews, focus on discrimination between malignant and benign disease instead of normal controls. In 57 studies involving 3,285 pancreatic carcinoma cases, the combined sensitivity of CA 19-9 was 78.2% and in 37 studies involving 1,882 cases with benign pancreatic disease the specificity of CA 19-9 was 82.8%. From the combined analysis of studies reporting CEA, the sensitivity was 44.2% (1,324 cases) and the specificity was 84.8% (656 cases). These measurements more appropriately reflect the expected biomarker accuracy in the differential diagnosis of patients with periampullary diseases. We also present a summary of the use of CA 19-9 as a prognostic tool and evaluate CA 19-9 diagnostic and prognostic utility in a 10-year, single institution experience.

    8. Fabry-Perot measurements and analysis of TOW-2A liner collapse and jet formation

      SciTech Connect

      Simonson, S.C.; Winer, K.A.; Breithaupt, R.D.; Avara, G.R.; Baum, D.W.

      1996-07-01

      A TOW-2A 146 mm shaped charge was fired and observed with five beam Fabry-Perot laser velocimetry. The liner collapse velocities were measured at five lines of sight covering the outer half of the liner. A record of 8-10 {mu}s in length was obtained for each sight line The velocity records at late time differ for each location, reflecting the varying charge-to-mass ratio as the end of the liner is approached. The results were analyzed with the CALE-2D hydrodynamic simulation code. The calculations reproduce the jump-off times, the shapes of the velocity jumps and the late time velocity asymptotes, but they underestimate the jump-off velocities by 6-7%. The calculations show that there exist no features in the velocity records that require spallation to account for them. Rather, the standard Steinberg-Guinan material model adequately accounts for the response of this copper liner to LX-14.

    9. Integral group actions on symmetric spaces and discrete duality symmetries of supergravity theories

      SciTech Connect

      Carbone, Lisa; Murray, Scott H.; Sati, Hisham

      2015-10-15

      For G = G(ℝ), a split, simply connected, semisimple Lie group of rank n and K the maximal compact subgroup of G, we give a method for computing Iwasawa coordinates of K∖G using the Chevalley generators and the Steinberg presentation. When K∖G is a scalar coset for a supergravity theory in dimensions ≥3, we determine the action of the integral form G(ℤ) on K∖G. We give explicit results for the action of the discrete U-duality groups SL{sub 2}(ℤ) and E{sub 7}(ℤ) on the scalar cosets SO(2)∖SL{sub 2}(ℝ) and [SU(8)/( ± Id)]∖E{sub 7(+7)}(ℝ) for type IIB supergravity in ten dimensions and 11-dimensional supergravity reduced to D = 4 dimensions, respectively. For the former, we use this to determine the discrete U-duality transformations on the scalar sector in the Borel gauge and we describe the discrete symmetries of the dyonic charge lattice. We determine the spectrum-generating symmetry group for fundamental BPS solitons of type IIB supergravity in D = 10 dimensions at the classical level and we propose an analog of this symmetry at the quantum level. We indicate how our methods can be used to study the orbits of discrete U-duality groups in general.

    10. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

      NASA Astrophysics Data System (ADS)

      Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

      2007-12-01

      We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

    11. Numerical simulation of interaction of hypervelocity particle stream with a target

      NASA Astrophysics Data System (ADS)

      Lomov, Ilya; Liu, Benjamin; Georgevich, Vlad; Antoun, Tarabay

      2007-06-01

      We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

    12. Empathy for Pain from Adolescence through Adulthood: An Event-Related Brain Potential Study

      PubMed Central

      Mella, Nathalie; Studer, Joseph; Gilet, Anne-Laure; Labouvie-Vief, Gisela

      2012-01-01

      Affective and cognitive empathy are traditionally differentiated, the affective component being concerned with resonating with another’s emotional state, whereas the cognitive component reflects regulation of the resulting distress and understanding of another’s mental states (see Decety and Jackson, 2004 for a review). Adolescence is a critical period for the development of cognitive control processes necessary to regulate affective processes: it is only in young adulthood that these control processes achieve maturity (Steinberg, 2005). Thus, one should expect adolescents to show greater automatic empathy than young adults. The present study aimed at exploring the neural correlates of affective (automatic) and cognitive empathy for pain from adolescence to young adulthood. With this aim, Event Related Potentials (ERPs) were recorded in 32 participants (aged 11–39) in a task designed to dissociate these components. ERPs results showed an early automatic fronto-central response to pain (that was not modulated by task demand) and a late parietal response to painful stimuli modulated by attention to pain cues. Adolescents exhibited earlier automatic responses to painful situations than young adults did and showed greater activity in the late cognitive component even when viewing neutral stimuli. Results are discussed in the context of the development of regulatory abilities during adolescence. PMID:23189065

    13. Mesoscale Simulations of Power Compaction

      SciTech Connect

      Lomov, I; Fujino, D; Antoun, T; Liu, B

      2009-08-06

      Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

    14. Mesoscale simulations of powder compaction

      NASA Astrophysics Data System (ADS)

      Lomov, Ilya; Antoun, Tarabay; Liu, Benjamin

      2009-06-01

      Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to experimental match compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show evidence of hard-to-explain reshock states above the single-shock Hugoniot line, which have also been observed in the experiments. We found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations, since 2D results tend to underpredict stress levels for high-porosity powders regardless of material properties. We developed a process to extract macroscale information for the simulation which can be directly used in calibration of continuum model for heterogeneous media.

    15. Numerical Simulation of Interaction of Hypervelocity Particle Stream with a Target

      SciTech Connect

      Lomov, I; Liu, B; Georgevich, V; Antoun, T

      2007-07-31

      We present results of direct numerical simulations of impact of hypervelocity particle stream with a target. The stream of interest consists of submillimeter (30-300 micron) brittle ceramic particles. Current supercomputer capabilities make it possible to simulate a realistic size of streams (up to 20 mm in diameter and 500 mm in length) while resolving each particle individually. Such simulations make possible to study the damage of the target from synergistic effects of individual impacts. In our research we fixed the velocity distribution along the axis of the stream (1-4 km/s) and volume fraction of the solid material (1-10%) and study effects of particle size variation, particle and target material properties and surrounding air properties. We ran 3D calibration simulations with up to 10 million individual particles and conducted sensitivity studies with 2D cylindrically symmetric simulations. We used an Eulerian Godunov hydrocode with adaptive mesh refinement. The particles, target material and air are represented with volume-of-fluid approach. Brittle particle and target material has been simulated with pressure-dependent yield strength and Steinberg model has been used for metal targets. Simulations demonstrated penetration depth and a hole diameter similar to experimental observations and can explain the influence of parameters of the stream on the character of the penetration.

    16. Expression of classical cadherins in the cerebellar anlage: quantitative and functional aspects.

      PubMed

      Gliem, Michael; Weisheit, Gunnar; Mertz, Kirsten D; Endl, Elmar; Oberdick, John; Schilling, Karl

      2006-12-01

      During central nervous system (CNS) development, cell migration precedes and is key to the integration of diverse sets of cells. Mechanistically, CNS histogenesis is realized through a balanced interplay of cell-cell and cell-matrix adhesion molecules. Here, we summarize experiments that probe the developmental expression and potential significance of a set of cadherins, including M-, N- and R-cadherin, for patterning of the cerebellar cortex. We established a transgenic marker that allows cerebellar granule cells to be followed from the neuroblast stage to their final, postmitotic settlement. In conjunction with flow cytometry, this allowed us to derive a quantitative view of cadherin expression in differentiating granule cells and relate it to the expression of the same cadherins in cerebellar inhibitory interneuronal precursors. In vitro reaggregation analysis supports a role for cadherins in cell sorting and migration within the nascent cerebellar cortex that may be rationalized within the context of the differential adhesion hypothesis (Foty, R.A. and Steinberg, M.S., 2005. The differential adhesion hypothesis: a direct evaluation. Dev. Biol. 278, 255-263.).

    17. Turbulent transport of cold and dense solar wind plasma into the magnetosphere by 3-D evolution of the Kelvin-Helmholtz instability

      NASA Astrophysics Data System (ADS)

      Matsumoto, Y.; Seki, K.

      2006-12-01

      An appearance of cold and dense plasma at the geosynchronous orbit is one of the characteristic natures after a prolonged northward IMF duration. This cold dense material can contribute to the enhancement of the ring current density, which results a further declination of Dst. Therefore investigating the origin, path and fate of the cold dense plasma is important to understand how it preconditions the magnetosphere during a quiet interval before storm [Borovsky and Steinberg, 2006]. Observational evidences have shown that the cold dense material builds up during the northward IMF intervals in the flanks of the magnetosphere [e.g., Wing and Newell, 2002] which is referred to as the low latitude boundary layer (LLBL). The entry process of the solar wind plasma into the magnetosphere during the northward IMF conditions has been controversial in contrast to the Dungey's reconnection model for the southward IMF cases. The major candidate processes are the double lobe reconnection model [Song et al., 1999], in which newly closed magnetic field lines on the dayside magnetopause capture the solar wind plasma, and the turbulent transport by the Kelvin-Helmholtz instability (KHI) driven by the fast solar wind flow. We have studied the solar wind entry process by the KHI. Matsumoto and Hoshino [2004, 2006] showed by 2- D MHD and full particle simulation studies that the strong flow turbulence is a natural consequence of the nonlinear development of the KHI through the secondary Rayleigh-Taylor instability, if there is a large density difference between the two media. The mechanism is fundamentally two-dimensional and therefore we term it the 2-D secondary instability. They also showed that the turbulent development greatly contributes to the solar wind plasma transport deep into the magnetosphere. Based on the previous 2-D studies, the 3-D nonlinear evolution of the KHI is studied by performing MHD simulation. Starting with a uniform background field configuration and a

    18. Kilometer-scale, late Miocene and early Pliocene surface uplift in East Greenland: tectonic forerunners for the build-up of the Greenland Ice Sheet

      NASA Astrophysics Data System (ADS)

      Japsen, Peter; Green, Paul F.; Bonow, Johan M.

      2015-04-01

      anchoring points during the build-up of the Greenland Ice Sheet over the period leading up to the Pleistocene (Solgaard et al., 2013). Tectonic processes thus underpinned the build-up of the Greenland Ice Sheet (Steinberger et al., 2015). The three uplift phases in Greenland overlap in time with similar events in North America and Europe and correlate with changes in plate motion. The much higher elevation of East Greenland compared to West Greenland suggests active support in the east from the Iceland plume. These observations indicate a connection between mantle convection, changes in plate motion and vertical movements along passive continental margins. Bonow, J.M. et al. 2014. Global Planet. Change 116, 10-29. Japsen, P. et al. 2014. Global Planet. Change 116, 91-114. Molnar, P., England, P.C. 1990. Nature 346, 29-34. Solgaard, A.M. et al. 2013. Palaeogeography Palaeoclimatology Palaeoecology 392, 161-176. Steinberger, B. et al. 2015. Terra Nova in press.

    19. Biomineral formation as a biosignature for microbial activities Precambrian cherts

      NASA Astrophysics Data System (ADS)

      Rincón Tomás, Blanca; Mühlen, Dominik; Hoppert, Michael; Reitner, Joachim

      2015-04-01

      In recent anoxic sediments manganese(II)carbonate minerals (e.g., rhodochrosite, kutnohorite) derive mainly from the reduction of manganese(IV) compounds by microbial anaerobic respiration. Small particles of rhodochrosite in stromatolite-like features in the Dresser chert Fm (Pilbara supergroup, W-Australia), associated with small flakes of kerogen, account for biogenic formation of the mineral in this early Archaean setting. Contrastingly, the formation of huge manganese-rich (carbonate) deposits requires effective manganese redox cycling, also conducted by various microbial processes, mainly requiring conditions of the early and late Proterozoic (Kirschvink et al., 2000; Nealson and Saffrani 1994). However, putative anaerobic pathways like microbial nitrate-dependent manganese oxidation (Hulth et al., 1999), anoxygenic photosynthesis (Johnson et al., 2013) and oxidation in UV light may facilitate manganese cycling even in a reducing atmosphere. Thus manganese redox cycling might have been possible even before the onset of oxygenic photosynthesis. Hence, there are several ways how manganese carbonates could have been formed biogenically and deposited in Precambrian sediments. Thus, the minerals may be suitable biosignatures for microbial redox processes in many respects. The hyperthermophilic archaeon Pyrobaculum islandicum produces rhodochrosite during growth on hydrogen and organic compounds and may be a putative model organism for the reduction of Mn(IV). References Hulth S, Aller RC, Gilbert F. (1999) Geochim Cosmochim Acta, 63, 49-66. Johnson JE, Webb SM, Thomas K, Ono S, Kirschvink JL, Fischer WW. (2013) Proc Natl Acad Sci USA, 110, 11238-11243. Kirschvink JL, Gaidos EJ, Bertani LE, Beukes NJ, Gutzmer J, Maepa LN, Steinberger LE. (2000) Proc Natl Acad Sci USA, 97, 1400-1405. Nealson KH, Saffarini D. (1994). Annu Rev Microbiol, 48, 311-343.

  1. Ig-like transcript 4 as a cellular receptor for soluble complement fragment C4d.

    PubMed

    Hofer, Johannes; Forster, Florian; Isenman, David E; Wahrmann, Markus; Leitner, Judith; Hölzl, Markus A; Kovarik, Johannes J; Stockinger, Hannes; Böhmig, Georg A; Steinberger, Peter; Zlabinger, Gerhard J

    2016-04-01

    Complement regulation leads to the generation of complement split products (CSPs) such as complement component (C)4d, a marker for disease activity in autoimmune syndromes or antibody-mediated allograft rejection. However, the physiologic role of C4d has been unknown. By screening murine thymoma BW5147 cells expressing a cDNA library generated from human monocyte-derived dendritic cells with recombinant human C4d, we identified Ig-like transcript (ILT)4 and ILT5v2 as cellular receptors for C4d. Both receptors, expressed on monocytes, macrophages, and dendritic cells, also interacted with the CSPs C3d, C4b, C3b, and iC3b. However, C4d did not bind to classic complement receptors (CRs). Interaction between cell surface-resident ILT4 and soluble monomeric C4d resulted in endocytosis of C4d. Surprisingly, binding of soluble ILT4 to C4d covalently immobilized to a cellular surface following classic complement activation could not be detected. Remarkably, C4d immobilized to a solid phaseviaits intrinsic thioester conferred a dose-dependent inhibition of TNF-α and IL-6 secretion in monocytes activatedviaFc-cross-linking of up to 50% as compared to baseline. Similarly, C4d conferred an attenuation of intracellular Ca(2+)flux in monocytes activatedviaFc-cross-linking. In conclusion, ILT4 represents a scavenger-type endocytotic CR for soluble monomeric C4d, whereas attenuation of monocyte activation by physiologically oriented C4d on a surface appears to be dependent on a yet to be identified C4d receptor.-Hofer, J., Forster, F., Isenman, D. E., Wahrmann, M., Leitner, J., Hölzl, M. A., Kovarik, J. K., Stockinger, H., Böhmig, G. A., Steinberger, P., Zlabinger, G. J. Ig-like transcript 4 as a cellular receptor for soluble complement fragment C4d.

  2. Patterns and Predictors of Mother-Adolescent Discrepancies across Family Constructs.

    PubMed

    Rote, Wendy M; Smetana, Judith G

    2016-10-01

    Parent-child discrepancies pervade the family literature; they appear in reports of relationship dynamics (e.g., conflict; Laursen et al. 1998), parent and child behaviors (e.g., monitoring; De Los Reyes et al. 2010), and individual family members' beliefs (e.g., parental legitimate authority; Smetana 2011). Discrepancies are developmentally normative (Steinberg 2001) but also may be indicators of relationship and adjustment problems for teens (Ohannessian 2012). Because of this variation, it is important to consider the extent to which parent-child discrepancies are a function of both the dyad and the family construct considered. The present study contributed to our understanding of informant discrepancies in family relationships by considering the patterning, consistency, and correlates of mother-adolescent discrepancies across three family constructs that vary in their objectivity. Using person-centered analyses, discrepancies in adolescents' and mothers' ratings of parents' right to know about teens' activities, mothers' knowledge of them, and positive mother-adolescents relationships were examined in 167 middle class, primarily European American mother-adolescent dyads (M teen age = 15.68 years, SD = .64, 53 % female). Each construct was best described by three profiles, one where adolescents' standardized ratings were consistently higher than mothers', one showing the reverse, and one revealing little disagreement. Adolescent-reported problem behavior (but not depression), behavioral and psychological control, and mothers' wellbeing significantly predicted profile membership. Most dyads maintained consistent membership in a discrepancy profile across at least two family constructs. Results contribute to understanding the different sources of discrepancies in views of the family.

  3. Simple rules for a “simple” nervous system? Molecular and biomathematical approaches to enteric nervous system formation and malformation

    PubMed Central

    Newgreen, Donald F.; Dufour, Sylvie; Howard, Marthe J.; Landman, Kerry A.

    2013-01-01

    We review morphogenesis of the enteric nervous system from migratory neural crest cells, and defects of this process such as Hirschsprung disease, centering on cell motility and assembly, and cell adhesion and extracellular matrix molecules, along with cell proliferation and growth factors. We then review continuum and agent-based (cellular automata) models with rules of cell movement and logistical proliferation. Both movement and proliferation at the individual cell level are modeled with stochastic components from which stereotyped outcomes emerge at the population level. These models reproduced the wave-like colonization of the intestine by enteric neural crest cells, and several new properties emerged, such as colonization by frontal expansion, which were later confirmed biologically. These models predict a surprising level of clonal heterogeneity both in terms of number and distribution of daughter cells. Biologically, migrating cells form stable chains made up of unstable cells, but this is not seen in the initial model. We outline additional rules for cell differentiation into neurons, axon extension, cell-axon and cell-cell adhesions, chemotaxis and repulsion which can reproduce chain migration. After the migration stage, the cells rearrange as a network of ganglia. Changes in cell adhesion molecules parallel this, and we describe additional rules based on Steinberg's Differential Adhesion Hypothesis, reflecting changing levels of adhesion in neural crest cells and neurons. This was able to reproduce enteric ganglionation in a model. Mouse mutants with disturbances of enteric nervous system morphogenesis are discussed, and these suggest future refinement of the models. The modeling suggests a relatively simple set of cell behavioral rules could account for complex patterns of morphogenesis. The model has allowed the proposal that Hirschsprung disease is mostly an enteric neural crest cell proliferation defect, not a defect of cell migration. In addition

  4. Ignition and combustion of bulk metals under elevated, normal and reduced gravity conditions

    NASA Technical Reports Server (NTRS)

    Abbud-Madrid, Angel; Branch, Melvyn C.; Daily, John W.

    1995-01-01

    This research effort is aimed at providing further insight into this multi-variable dependent phenomena by looking at the effects of gravity on the ignition and combustion behavior of metals. Since spacecraft are subjected to higher-than-1g gravity loads during launch and reentry and to zero-gravity environments while in orbit, the study of ignition and combustion of bulk metals at different gravitational potentials is of great practical concern. From the scientific standpoint, studies conducted under microgravity conditions provide simplified boundary conditions since buoyancy is removed, and make possible the identification of fundamental ignition mechanisms. The effect of microgravity on the combustion of bulk metals has been investigated by Steinberg, et al. on a drop tower simulator. However, no detailed quantitative work has been done on ignition phenomena of bulk metals at lower or higher-than-normal gravitational fields or on the combustion characteristics of metals at elevated gravity. The primary objective of this investigation is the development of an experimental system capable of providing fundamental physical and chemical information on the ignition of bulk metals under different gravity levels. The metals used in the study, iron (Fe), titanium (Ti), zirconium (Zr), magnesium (Mg), zinc (Zn), and copper (Cu) were selected because of their importance as elements of structural metals and their simple chemical composition (pure metals instead of multi-component alloys to avoid complication in morphology and spectroscopic studies). These samples were also chosen to study the two different combustion modes experienced by metals: heterogeneous or surface oxidation, and homogeneous or gas-phase reaction. The experimental approach provides surface temperature profiles, spectroscopic measurements, surface morphology, x-ray spectrometry of metals specimens and their combustion products, and high-speed cinematography of the heating, ignition and combustion

  5. Responses of coastal ecosystems to environmental variability in emerging countries from the Americas

    NASA Astrophysics Data System (ADS)

    Muniz, Pablo; Calliari, Danilo; Giménez, Luis; Defeo, Omar

    2015-12-01

    Coastal ecosystems supply critical ecological services and benefits to human society (Barbier et al., 2011). Nearly 38% of the global monetary value of annual ecosystem services arises from estuaries, seagrass and algal beds, coral reefs and shelf ecosystems (Costanza et al., 1997). However, these ecosystems are being increasingly affected by multiple drivers acting simultaneously at several spatial and temporal scales (Lotze et al., 2006; Hoegh-Guldberg and Bruno, 2010). Climate change (temperature increase, sea level rise, ocean acidification), human activities (e.g. land use/cover change, pollution, overexploitation, translocation of species), and extreme natural events (storms, floods, droughts) are the most important drivers degrading the resilience of coastal systems. Such factors operate on individual level processes, leading organisms away from their niches (Steinberg, 2013) or modifying rates and phenology (Giménez, 2011; Mackas et al., 2012, Deutsch et al., 2015). All of these influence ecosystem level processes, causing changes in species composition, diversity losses and deterioration of ecosystem functions (Worm et al., 2006; Defeo et al., 2009; Doney et al., 2011; Dornelas et al., 2014). The rate of change in habitats, species distributions and whole ecosystems has accelerated over the past decades as shown, for example, in the increase in the frequency of events of coastal hypoxia (Diaz and Rosenberg, 2008,Vaquer-Sunyer and Duarte, 2008), extensive translocation of species by global shipping (Seebens et al., 2013), and in ecosystem regime shifts (Möllmann et al., 2015 and references therein). Some coastal areas have been transformed into novel ecosystems with physical and biological characteristics outside their natural range of variability (Cloern et al., 2015) while others are likely to become sink areas, limiting the migration of marine species away from warming habitats (Burrows et al., 2014).

  6. Dissociative amnesia in dissociative disorders and borderline personality disorder: self-rating assessment in a college population.

    PubMed

    Sar, Vedat; Alioğlu, Firdevs; Akyuz, Gamze; Karabulut, Sercan

    2014-01-01

    Dissociative amnesia (DA) among subjects with a dissociative disorder and/or borderline personality disorder (BPD) recruited from a nonclinical population was examined. The Steinberg Dissociative Amnesia Questionnaire (SDAQ), the Childhood Trauma Questionnaire, and the self-report screening tool of the BPD section of the Structured Clinical Interview for DSM-IV(SCID-BPD) were administered to 1,301 college students. A total of 80 participants who were diagnosed with BPD according to the clinician-administered SCID-BPD and 111 nonborderline controls were evaluated using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D) by a psychiatrist blind to diagnosis and scale scores. Internal consistency analyses and test-retest evaluations suggested that the SDAQ is a reliable instrument for the population studied. Of the participants, 20.6% reported an SDAQ score of 20 or above and impairment by DA. Those who had both dissociative disorder and BPD (n = 78) had the highest SDAQ scores. Both disorders had significant effects on the SCID-D total and amnesia scores in the variance analysis. On SDAQ scores, however, only BPD had this effect. There was a significant interaction between the 2 disorders for the SCID-D total but not for the SDAQ or SCID-D amnesia scores. BPD represented the severity of dissociation and childhood trauma in this study group. However, in contrast to the dissociative disorders, BPD was characterized by better awareness of DA in self-report. The discrepancies between self-report and clinical interview associated with BPD and dissociative disorders are discussed in the context of betrayal theory (J. J. Freyd, 1994) of BPD and perceptual theory (D. B. Beere, 2009) of dissociative disorders.

  7. Elastic turbulence in curvilinear flows of polymer solutions

    NASA Astrophysics Data System (ADS)

    Groisman, Alexander; Steinberg, Victor

    2004-03-01

    Following our first report (A Groisman and V Steinberg 2000 Nature 405 53), we present an extended account of experimental observations of elasticity-induced turbulence in three different systems: a swirling flow between two plates, a Couette-Taylor (CT) flow between two cylinders, and a flow in a curvilinear channel (Dean flow). All three set-ups had a high ratio of the width of the region available for flow to the radius of curvature of the streamlines. The experiments were carried out with dilute solutions of high-molecular-weight polyacrylamide in concentrated sugar syrups. High polymer relaxation time and solution viscosity ensured prevalence of non-linear elastic effects over inertial non-linearity, and development of purely elastic instabilities at low Reynolds number (Re) in all three flows. Above the elastic instability threshold, flows in all three systems exhibit features of developed turbulence. They include: (i) randomly fluctuating fluid motion excited in a broad range of spatial and temporal scales and (ii) significant increase in the rates of momentum and mass transfer (compared with those expected for a steady flow with a smooth velocity profile). Phenomenology, driving mechanisms and parameter dependence of the elastic turbulence are compared with those of the conventional high-Re hydrodynamic turbulence in Newtonian fluids. Some similarities as well as multiple principal differences were found. In two out of three systems (swirling flow between two plates and flow in the curvilinear channel), power spectra of velocity fluctuations decayed rather quickly, following power laws with exponents of about -3.5. It suggests that, being random in time, the flow is rather smooth in space, in the sense that the main contribution to deformation and mixing (and, possibly, elastic energy) is coming from flow at the largest scale of the system. This situation, random in time and smooth in space, is analogous to flows at small scales (below the Kolmogorov

  8. Binary-YORP Coefficients for Known Asteroid Shapes

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.; Scheeres, D. J.

    2012-10-01

    The binary YORP (bYORP) effect has been hypothesized to be a significant factor in the evolution of near-Earth binary asteroid systems (Cuk and Burns, Icarus, v.176, pp.418-431, 2005; McMahon and Scheeres, CMDA, v.106, pp.261-300, 2010). However, understanding of the coefficient values for realistic asteroid shapes is lacking due to the small number of shape models available for the generally smaller secondary asteroids. Until now, we have only calculated the coefficients based on the shape of 1999 KW4 Beta, although various studies by other authors have computed coefficients for artificially generated asteroids based on Gaussian Spheres and some shape models without self-shadowing (Steinberg and Sari, The Astronomical Journal, v.141, pp.55-64, 2011). We also scaled the 1999 KW4 Beta coefficients to other binary systems with no knowledge of the other systems' secondary shapes in order to make evolutionary predictions (McMahon and Scheeres, Icarus Vol. 209, pp 494-509, 2010). In this study, we compute the bYORP coefficient for a range of asteroid shapes, using these as a stand-in for actual secondaries. This allows us to circumvent the lack of information on binary asteroid secondaries and to develop a richer database of realistic coefficients. While this approach may miss some key features of binary secondaries, at the least it provides some statistics on the expected variability of the bYORP coefficient. We analyze all available asteroid shape models on the PDS-SBN, including radar-based shape models and models estimated from past spacecraft missions. The coefficients are computed with an updated algorithm that includes the effects of self-shadowing. We also present the coefficients for perturbed versions of the available shape models, which give effective error bars to the computed coefficients due to inexact shape models. Finally, we discuss the dynamical implications of the derived bYORP coefficients on binary asteroid evolution.

  9. 2169 steel waveform experiments.

    SciTech Connect

    Furnish, Michael David; Alexander, C. Scott; Reinhart, William Dodd; Brown, Justin L.

    2012-11-01

    In support of LLNL efforts to develop multiscale models of a variety of materials, we have performed a set of eight gas gun impact experiments on 2169 steel (21% Cr, 6% Ni, 9% Mn, balance predominantly Fe). These experiments provided carefully controlled shock, reshock and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa (particle velocities from 0.25 to 1.05 km/s). Both windowed and free-surface measurements were included in this experiment set to increase the utility of the data set, as were samples ranging in thickness from 1 to 5 mm. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release path (windowed and free-surface). The Hugoniot was found to be nearly linear, with no indications of the Fe phase transition. Releases were non-hysteretic, and relatively consistent between 3- and 5-mmthick samples (the 3 mm samples giving slightly lower wavespeeds on release). Reshock tests with explosively welded impactors produced clean results; those with glue bonds showed transient releases prior to the arrival of the reshock, reducing their usefulness for deriving strength information. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A configuration used for the last three shots allows release information to be determined from these free surface samples. The sample strength appears to increase with stress from ~1 GPa to ~ 3 GPa over this range, consistent with other recent work but about 40% above the Steinberg model.

  10. Patterns and Predictors of Mother-Adolescent Discrepancies across Family Constructs.

    PubMed

    Rote, Wendy M; Smetana, Judith G

    2016-10-01

    Parent-child discrepancies pervade the family literature; they appear in reports of relationship dynamics (e.g., conflict; Laursen et al. 1998), parent and child behaviors (e.g., monitoring; De Los Reyes et al. 2010), and individual family members' beliefs (e.g., parental legitimate authority; Smetana 2011). Discrepancies are developmentally normative (Steinberg 2001) but also may be indicators of relationship and adjustment problems for teens (Ohannessian 2012). Because of this variation, it is important to consider the extent to which parent-child discrepancies are a function of both the dyad and the family construct considered. The present study contributed to our understanding of informant discrepancies in family relationships by considering the patterning, consistency, and correlates of mother-adolescent discrepancies across three family constructs that vary in their objectivity. Using person-centered analyses, discrepancies in adolescents' and mothers' ratings of parents' right to know about teens' activities, mothers' knowledge of them, and positive mother-adolescents relationships were examined in 167 middle class, primarily European American mother-adolescent dyads (M teen age = 15.68 years, SD = .64, 53 % female). Each construct was best described by three profiles, one where adolescents' standardized ratings were consistently higher than mothers', one showing the reverse, and one revealing little disagreement. Adolescent-reported problem behavior (but not depression), behavioral and psychological control, and mothers' wellbeing significantly predicted profile membership. Most dyads maintained consistent membership in a discrepancy profile across at least two family constructs. Results contribute to understanding the different sources of discrepancies in views of the family. PMID:27295041

  11. First-principles thermoelasticity of transition metals at high pressure: Tantalum prototype in the quasiharmonic limit

    NASA Astrophysics Data System (ADS)

    Orlikowski, Daniel; Söderlind, Per; Moriarty, John A.

    2006-08-01

    The thermoelastic properties of tantalum have been investigated over its theoretical high-pressure bcc solid phase (up to 26000K at 10Mbar ) using an advanced first-principles approach that accurately accounts for cold, electron-thermal, and ion-thermal contributions in materials where anharmonic effects are small. Specifically, we have combined ab initio full-potential linear-muffin-tin-orbital electronic-structure calculations for the cold and electron-thermal contributions to the elastic moduli with phonon contributions for the ion-thermal part calculated using model generalized pseudopotential theory. For the latter, a summation of terms over the Brillouin zone is performed within the quasiharmonic approximation, where each term is composed of a strain derivative of the phonon frequency at a particular k point. At ambient pressure, the resulting temperature dependence of the Ta elastic moduli is in excellent agreement with ultrasonic measurements. The experimentally observed anomalous behavior of C44 at low temperatures is shown to originate from the electron-thermal contribution. At higher temperatures, the main contribution to the temperature dependence of the elastic moduli comes from thermal expansion, but inclusion of the electron- and ion-thermal contributions is essential to obtain quantitative agreement with experiment. In addition, the pressure dependence of the moduli at ambient temperature compares well with recent diamond-anvil-cell measurements to 1.05Mbar . Moreover, the calculated longitudinal and bulk sound velocities in polycrystalline Ta at higher pressure and temperature in the vicinity of shock melting (˜3Mbar) agree well with data obtained from shock experiments. However, at high temperatures along the melt curve above 1Mbar , the B' shear modulus becomes negative, indicating the onset of unexpectedly strong anharmonic effects. Finally, the assumed temperature dependence of the Steinberg-Guinan strength model obtained from scaling with the

  12. Anharmonic Materials and Thermoelasticity at High Temperatures and Pressures

    NASA Astrophysics Data System (ADS)

    Orlikowski, Daniel

    2005-03-01

    For large-scale constitutive strength models, the shear modulus is typically assumed to be linearly dependent on temperature. However, for materials compressed along or beyond the Hugoniot into high pressure and temperature regimes where there is no experimental measurement or very little, accurate and validated models must be used. To this end, we have investigated and compared, as a function of temperature (<26,000 K) and pressure (<10 Mbar), the anharmonic and quasi-harmonic thermoelasticity accounting for both the electron-thermal and ion-thermal contributions for bcc tantalum and bcc molybdenum. In this approach, the full potential linear muffin-tin orbital (FP-LMTO) method for the cold and electron-thermal contributions is closely coupled with ion-thermal contributions. For the ion contribution two separate approaches are used. In one approach, the quasi-harmonic ion contribution is obtained through a Brillouin zone sum of strain derivatives of the phonons, and in the other the anharmonic ion contribution is obtained directly through Monte Carlo (MC) canonical distribution averages of strain derivatives on the multi-ion potential itself. Both methods for the ion-contribution use quantum-based interatomic potentials derived from model generalized pseudopotential theory (MGPT). The resulting elastic moduli are compared to available ultrasonic measurements and diamond-anvil-cell compression experiments, as well as to sound speeds along the Hugoniot. Over this range of temperature and pressure, the results are then used in a polycrystalline averaging for a comparison to larger-scale shear models like the Steinberg-Guinan strength model. These results give an indication that anharmonic effects are negligible in tantalum but not in molybdenum for high pressures and temperatures up to melt. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract W-7405-Eng-48.

  13. Bacteriophage T4 Dam DNA-[N6-adenine]methyltransferase. Kinetic evidence for a catalytically essential conformational change in the ternary complex.

    PubMed

    Evdokimov, Alexey A; Zinoviev, Victor V; Malygin, Ernst G; Schlagman, Samuel L; Hattman, Stanley

    2002-01-01

    We carried out a steady state kinetic analysis of the bacteriophage T4 DNA-[N6-adenine]methyltransferase (T4 Dam) mediated methyl group transfer reaction from S-adenosyl-l-methionine (AdoMet) to Ade in the palindromic recognition sequence, GATC, of a 20-mer oligonucleotide duplex. Product inhibition patterns were consistent with a steady state-ordered bi-bi mechanism in which the order of substrate binding and product (methylated DNA, DNA(Me) and S-adenosyl-l-homocysteine, AdoHcy) release was AdoMet downward arrow DNA downward arrow DNA(Me) upward arrow AdoHcy upward arrow. A strong reduction in the rate of methylation was observed at high concentrations of the substrate 20-mer DNA duplex. In contrast, increasing substrate AdoMet concentration led to stimulation in the reaction rate with no evidence of saturation. We propose the following model. Free T4 Dam (initially in conformational form E) randomly interacts with substrates AdoMet and DNA to form a ternary T4 Dam-AdoMet-DNA complex in which T4 Dam has isomerized to conformational state F, which is specifically adapted for catalysis. After the chemical step of methyl group transfer from AdoMet to DNA, product DNA(Me) dissociates relatively rapidly (k(off) = 1.7 x s(-1)) from the complex. In contrast, dissociation of product AdoHcy proceeds relatively slowly (k(off) = 0.018 x s(-1)), indicating that its release is the rate-limiting step, consistent with kcat = 0.015 x s(-1). After AdoHcy release, the enzyme remains in the F conformational form and is able to preferentially bind AdoMet (unlike form E, which randomly binds AdoMet and DNA), and the AdoMet-F binary complex then binds DNA to start another methylation cycle. We also propose an alternative pathway in which the release of AdoHcy is coordinated with the binding of AdoMet in a single concerted event, while T4 Dam remains in the isomerized form F. The resulting AdoMet-F binary complex then binds DNA, and another methylation reaction ensues. This route is

  14. Biological assessment of the lower Boise River, October 1995 through January 1998, Ada and Canyon Counties, Idaho

    USGS Publications Warehouse

    Mullins, William H.

    1999-01-01

    The lower Boise River, between Lucky Peak Dam and the mouth of the river near Parma, Idaho, is adversely affected by various land- and water-use activities. To assess the biotic integrity of the river and the effects of environmental perturbations on aquatic community structure, and to provide a baseline from which to identify future changes in habitat conditions, biological data were collected from October 1995 through January 1998 and evaluated using protocols developed for the U.S. Geological Survey National Water-Quality Assessment Program. Aquatic biological communities were sampled according to the following schedule: epilithic periphyton were collected in October 1995, October 1996, and August 1997; benthic macroinvertebrates were collected in October 1995, 1996, and 1997; and fish were collected in December 1996 and August 1997. Qualitative measurements of instream and riparian habitat indicated an overall decrease in instream habitat quality in a downstream direction. Embeddedness was high at all sites but was lower at the Eckert Road site than at the downstream sites near Middleton and Parma. Silt/sand substrate increased from 17 percent at the Eckert Road site to 49 percent near the mouth of the river. The Eckert Road site had a mix of geomorphic channel units (pool/riffle/run), whereas the Middleton and Parma sites were dominated by runs with very little pool or riffle habitat. Epilithic periphyton chlorophyll-a and ashfree dry weight values tended to increase downstream to the Middleton site and decrease from Middleton to the downstream sites near Caldwell and near Parma. Benthic index of biotic integrity (B-IBI) scores for macroinvertebrates collected in 1995, 1996, and 1997 were highest at the Eckert Road site and decreased at sites downstream. IBI scores for fish collected in 1996 were similar at the Glenwood Bridge and Middleton sites (17 and 16, respectively) and were indicative of a low to moderate level of disturbance. In contrast, the IBI score

  15. Examining the effects of students' classroom expectations on undergraduate biology course reform

    NASA Astrophysics Data System (ADS)

    Hall, Kristi Lyn

    In this dissertation, I perform and compare three studies of introductory biology students' classroom expectations -- what students expect to be the nature of the knowledge that they are learning, what they think they should be (or are) doing in order to learn, and what they think they should be (or are) doing in order to be successful. Previous work has shown that expectations can impact how students approach learning, yet biology education researchers have been reluctant to acknowledge or address the effects of student expectations on curricular reform (NRC, 2012). Most research in biology education reform has focused on students' conceptual understandings of biology and the efficacy of specific changes to content and pedagogy. The current research is lacking a deeper understanding of how students perceive the classroom environment and how those perceptions can shape students' interactions with the content and pedagogy. For present and future reforms in biology to reach their full potential, I argue that biology education should actively address the different ways students think about and approach learning in biology classes. The first study uses a Likert-scale instrument, adapted from the Maryland Physics Expectations Survey (Redish, Saul, & Steinberg, 1998). This new survey, the Maryland Biology Expectations Survey (MBEX) documents two critical results in biology classrooms: (i) certain student-centered pedagogical contexts can produce favorable changes in students' expectations, and (ii) more traditional classroom contexts appear to produce negative epistemological effects. The second study utilizes a modified version of the MBEX and focuses on students' interdisciplinary views. This study documents that: (i) biology students have both discipline-specific and context-specific classroom expectations, (ii) students respond more favorably to interdisciplinary content in the biology courses we surveyed (as opposed to biology content introduced into the physics

  16. Measurements and ALE3D Simulations for Violence in a Scaled Thermal Explosion Experiment with LX-10 and AerMet 100 Steel

    SciTech Connect

    McClelland, M A; Maienschein, J L; Yoh, J J; deHaven, M R; Strand, O T

    2005-06-03

    We completed a Scaled Thermal Explosion Experiment (STEX) and performed ALE3D simulations for the HMX-based explosive, LX-10, confined in an AerMet 100 (iron-cobalt-nickel alloy) vessel. The explosive was heated at 1 C/h until cookoff at 182 C using a controlled temperature profile. During the explosion, the expansion of the tube and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. These results were combined to produce a single curve describing 15 cm of tube wall motion. A majority of the metal fragments were captured and cataloged. A fragment size distribution was constructed, and a typical fragment had a length scale of 2 cm. Based on these results, the explosion was considered to be a violent deflagration. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A four-step chemical kinetics model is employed for the HMX while a one-step model is used for the Viton. A pressure-dependent deflagration model is employed during the expansion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A Johnson-Cook model with an empirical rule for failure strain is used to describe fracture behavior. Parameters for the kinetics model were specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate were employed to determine parameters in the burn front model. The ALE3D models provide good predictions for the thermal behavior and time to explosion, but the predicted wall expansion curve is higher than the measured curve. Possible contributions to this discrepancy include inaccuracies in the chemical models

  17. Recent advances in data assimilation in computational geodynamic models

    NASA Astrophysics Data System (ADS)

    Ismail-Zadeh, Alik

    2010-05-01

    To restore dynamics of mantle structures in the geological past, data assimilation can be used to constrain the initial conditions for the mantle temperature and velocity from their present observations and estimations. The initial conditions so obtained can then be used to run forward models of mantle dynamics to restore the evolution of mantle structures. If heat diffusion is neglected, the present mantle temperature and flow can be assimilated using the backward advection (BAD) into the past. Two- and three-dimensional numerical approaches to the solution of the inverse problem of the Rayleigh-Taylor instability were developed for a dynamic restoration of diapiric structures to their earlier stages (e.g., Ismail-Zadeh et al., 1998, 2001, 2004; Kaus and Podladchikov, 2001). The mantle flow was modelled backwards in time from present-day mantle density heterogeneities inferred from seismic observations (e.g., Steinberger and O'Connell, 1998; Conrad and Gurnis, 2003). The variational (VAR) (or also called adjoint) data assimilation has been pioneered by meteorologists and widely used in oceanography and in hydrological studies. The use of VAR data assimilation in models of geodynamics has been put forward by Bunge et al. (2003) and Ismail-Zadeh et al. (2003). The VAR data assimilation algorithm was employed to restore numerically models of mantle plumes (Ismail-Zadeh et al., 2004, 2006; Hier-Majumder et al., 2005; Liu and Gurnis, 2008; Liu et al., 2008). The use of the quasi-reversibility (QRV) technique (more robust computationally) implies the introduction into the backward heat equation of the additional term involving the product of a small regularization parameter and a higher order temperature derivative (the resulting regularized heat equation is based on the Riemann law of heat conduction). The data assimilation in this case is based on a search of the best fit between the forecast model state and the observations by minimizing the regularization parameter

  18. Molecular mechanisms of Alzheimer disease protection by the A673T allele of amyloid precursor protein.

    PubMed

    Maloney, Janice A; Bainbridge, Travis; Gustafson, Amy; Zhang, Shuo; Kyauk, Roxanne; Steiner, Pascal; van der Brug, Marcel; Liu, Yichin; Ernst, James A; Watts, Ryan J; Atwal, Jasvinder K

    2014-11-01

    Pathogenic mutations in the amyloid precursor protein (APP) gene have been described as causing early onset familial Alzheimer disease (AD). We recently identified a rare APP variant encoding an alanine-to-threonine substitution at residue 673 (A673T) that confers protection against development of AD (Jonsson, T., Atwal, J. K., Steinberg, S., Snaedal, J., Jonsson, P. V., Bjornsson, S., Stefansson, H., Sulem, P., Gudbjartsson, D., Maloney, J., Hoyte, K., Gustafson, A., Liu, Y., Lu, Y., Bhangale, T., Graham, R. R., Huttenlocher, J., Bjornsdottir, G., Andreassen, O. A., Jönsson, E. G., Palotie, A., Behrens, T. W., Magnusson, O. T., Kong, A., Thorsteinsdottir, U., Watts, R. J., and Stefansson, K. (2012) Nature 488, 96-99). The Ala-673 residue lies within the β-secretase recognition sequence and is part of the amyloid-β (Aβ) peptide cleavage product (position 2 of Aβ). We previously demonstrated that the A673T substitution makes APP a less favorable substrate for cleavage by BACE1. In follow-up studies, we confirm that A673T APP shows reduced cleavage by BACE1 in transfected mouse primary neurons and in isogenic human induced pluripotent stem cell-derived neurons. Using a biochemical approach, we show that the A673T substitution modulates the catalytic turnover rate (V(max)) of APP by the BACE1 enzyme, without affecting the affinity (K(m)) of the APP substrate for BACE1. We also show a reduced level of Aβ(1-42) aggregation with A2T Aβ peptides, an observation not conserved in Aβ(1-40) peptides. When combined in a ratio of 1:9 Aβ(1-42)/Aβ(1-40) to mimic physiologically relevant mixtures, A2T retains a trend toward slowed aggregation kinetics. Microglial uptake of the mutant Aβ(1-42) peptides correlated with their aggregation level. Cytotoxicity of the mutant Aβ peptides was not dramatically altered. Taken together, our findings demonstrate that A673T, a protective allele of APP, reproducibly reduces amyloidogenic processing of APP and also mildly decreases A

  19. Molecular Mechanisms of Alzheimer Disease Protection by the A673T Allele of Amyloid Precursor Protein*

    PubMed Central

    Maloney, Janice A.; Bainbridge, Travis; Gustafson, Amy; Zhang, Shuo; Kyauk, Roxanne; Steiner, Pascal; van der Brug, Marcel; Liu, Yichin; Ernst, James A.; Watts, Ryan J.; Atwal, Jasvinder K.

    2014-01-01

    Pathogenic mutations in the amyloid precursor protein (APP) gene have been described as causing early onset familial Alzheimer disease (AD). We recently identified a rare APP variant encoding an alanine-to-threonine substitution at residue 673 (A673T) that confers protection against development of AD (Jonsson, T., Atwal, J. K., Steinberg, S., Snaedal, J., Jonsson, P. V., Bjornsson, S., Stefansson, H., Sulem, P., Gudbjartsson, D., Maloney, J., Hoyte, K., Gustafson, A., Liu, Y., Lu, Y., Bhangale, T., Graham, R. R., Huttenlocher, J., Bjornsdottir, G., Andreassen, O. A., Jönsson, E. G., Palotie, A., Behrens, T. W., Magnusson, O. T., Kong, A., Thorsteinsdottir, U., Watts, R. J., and Stefansson, K. (2012) Nature 488, 96–99). The Ala-673 residue lies within the β-secretase recognition sequence and is part of the amyloid-β (Aβ) peptide cleavage product (position 2 of Aβ). We previously demonstrated that the A673T substitution makes APP a less favorable substrate for cleavage by BACE1. In follow-up studies, we confirm that A673T APP shows reduced cleavage by BACE1 in transfected mouse primary neurons and in isogenic human induced pluripotent stem cell-derived neurons. Using a biochemical approach, we show that the A673T substitution modulates the catalytic turnover rate (Vmax) of APP by the BACE1 enzyme, without affecting the affinity (Km) of the APP substrate for BACE1. We also show a reduced level of Aβ(1–42) aggregation with A2T Aβ peptides, an observation not conserved in Aβ(1–40) peptides. When combined in a ratio of 1:9 Aβ(1–42)/Aβ(1–40) to mimic physiologically relevant mixtures, A2T retains a trend toward slowed aggregation kinetics. Microglial uptake of the mutant Aβ(1–42) peptides correlated with their aggregation level. Cytotoxicity of the mutant Aβ peptides was not dramatically altered. Taken together, our findings demonstrate that A673T, a protective allele of APP, reproducibly reduces amyloidogenic processing of APP and also mildly

  20. Global Dynamic Numerical Simulations of Plate Tectonic Reorganizations

    NASA Astrophysics Data System (ADS)

    Morra, G.; Quevedo, L.; Butterworth, N.; Matthews, K. J.; Müller, D.

    2010-12-01

    We use a new numerical approach for global geodynamics to investigate the origin of present global plate motion and to identify the causes of the last two global tectonic reorganizations occurred about 50 and 100 million years ago (Ma) [1]. While the 50 Ma event is the most well-known global plate-mantle event, expressed by the bend in the Hawaiian-Emperor volcanic chain, a prominent plate reorganization at about 100 Ma, although presently little studied, is clearly indicated by a major bend in the fracture zones in the Indian Ocean and by a change in Pacific plate motion [2]. Our workflow involves turning plate reconstructions into surface meshes that are subsequently employed as initial conditions for global Boundary Element numerical models. The tectonic setting that anticipates the reorganizations is processed with the software GPlates, combining the 3D mesh of the paleo-plate morphology and the reconstruction of paleo-subducted slabs, elaborated from tectonic history [3]. All our models involve the entire planetary system, are fully dynamic, have free surface, are characterized by a spectacular computational speed due to the simultaneous use of the multi-pole algorithm and the Boundary Element formulation and are limited only by the use of sharp material property variations [4]. We employ this new tool to unravel the causes of plate tectonic reorganizations, producing and comparing global plate motion with the reconstructed ones. References: [1] Torsvik, T., Müller, R.D., Van der Voo, R., Steinberger, B., and Gaina, C., 2008, Global Plate Motion Frames: Toward a unified model: Reviews in Geophysics, VOL. 46, RG3004, 44 PP., 2008 [2] Wessel, P. and Kroenke, L.W. Pacific absolute plate motion since 145 Ma: An assessment of the fixed hot spot hypothesis. Journal of Geophysical Research, Vol 113, B06101, 2008 [3] L. Quevedo, G. Morra, R. D. Mueller. Parallel Fast Multipole Boundary Element Method for Crustal Dynamics, Proceeding 9th World Congress and 4th Asian

  1. Polyphase basin evolution of the Vienna Basin inferred from 3D visualization of sedimentation setting and quantitative subsidence

    NASA Astrophysics Data System (ADS)

    Lee, Eun Young; Novotny, Johannes; Wagreich, Michael

    2016-04-01

    This study analyzed and visualized data from 210 wells using a MATLAB-based program (BasinVis 1.0) for 3D visualization of sediment distribution, thickness, and quantitative subsidence of the northern and central Vienna Basin. The sedimentation settings for selected horizons were visualized to 3D sediment distribution maps, isopach maps, and cross-sections. Subsidence of the study area resulted in 3D subsidence depth and rate maps of basement and tectonic subsidences. Due to the special position of the Vienna Basin, the basin evolution was influenced by the regional tectonics of surrounding units. The 2D/3D maps provided insights into the polyphase evolution of the Vienna Basin, which is closely related to changes in the changing regional stress field and the paleoenvironmental setting. In the Early Miocene, the sedimentation and subsidence were shallow and E-W/NE-SW trending, indicating the development of piggy-back basins. During the late Early Miocene, maps show wider sedimentation and abruptly increasing subsidence by sinistral strike-slip faults, which initiated the Vienna pull-apart basin system. The sediments of the Early Miocene were supplied through a small deltaic system entering from the south. After thin sedimentation and shallow subsidence of the early Middle Miocene, the development of the Vienna Basin was controlled and accelerated mainly by NE-SW trending synsedimentary normal faults, especially the Steinberg fault. From the Middle Miocene, the subsidence was decreasing overall, however the tectonic subsidence show regionally different patterns. This study suggests that a major tensional regime change, from transtension to E-W extension, caused laterally varying subsidence across the Vienna Basin. The Late Miocene was characterized by the slowing down of basement and tectonic subsidence. From the middle Middle to Late Miocene, enormous amount of sediments supplied by a broad paleo-Danube delta complex on the western flank of the basin. The latest

  2. The enzymatic and antioxidative stress response of Lemna minor to copper and a chloroacetamide herbicide.

    PubMed

    Obermeier, Michael; Schröder, Christian A; Helmreich, Brigitte; Schröder, Peter

    2015-12-01

    Lemna minor L., a widely used model plant for toxicity tests has raised interest for its application to phytoremediation due to its rapid growth and ubiquitous occurrence. In rural areas, the pollution of water bodies with heavy metals and agrochemicals poses a problem to surface water quality. Among problematic compounds, heavy metals (copper) and pesticides are frequently found in water bodies. To establish duckweed as a potential plant for phytoremediation, enzymatic and antioxidative stress responses of Lemna minor during exposure to copper and a chloroacetamide herbicide were investigated in laboratory studies. The present study aimed at evaluating growth and the antioxidative and glutathione-dependent enzyme activity of Lemna plants and its performance in a scenario for phytoremediation of copper and a chloroacetamide herbicide. Lemna minor was grown in Steinberg medium under controlled conditions. Plants were treated with CuSO4 (ion conc. 50 and 100 μg/L) and pethoxamide (1.25 and 2.5 μg/L). Measurements following published methods focused on plant growth, oxidative stress, and basic detoxification enzymes. Duckweed proved to survive treatment with the respective concentrations of both pollutants very well. Its growth was inhibited scarcely, and no visible symptoms occurred. On the cellular basis, accumulation of O2(-) and H2O2 were detected, as well as stress reactions of antioxidative enzymes. Duckweed detoxification potential for organic pollutants was high and increased significantly with incubation. Pethoxamide was found to be conjugated with glutathione. Copper was accumulated in the fronds at high levels, and transient oxidative defense reactions were triggered. This work confirms the significance of L. minor for the removal of copper from water and the conjugation of the selective herbicide pethoxamide. Both organic and inorganic xenobiotics induced different trends of enzymatic and antioxidative stress response. The strong increase of stress

  3. Sex hormones and the immune system--Part 2. Animal data.

    PubMed

    Ahmed, S A; Talal, N

    1990-04-01

    Sex hormones have physiological and pathological (autoimmune conditions) effects on the immune system. Studies in experimental animal models of human autoimmune diseases have clearly shown that sex hormones regulate the expression, severity and course of autoimmune diseases. Sex hormones affect the function of T, B and NK cells, and macrophages. Precisely how sex hormones affect lymphocytes is a highly complex question. Sex hormones can modulate the immune system, perhaps directly (e.g. thymic reticular tissue), or indirectly via host and many oestrogen target tissues, including the central nervous system hypothalamic-pituitary axis (the neuroendocrine tissues). The effects of sex hormones on the immune system (immunosuppression or immunopotentiation) may vary, even with the same hormone. For example, oestrogen can increase IgA levels in the uterus, but decrease IgA levels in the vagina or have no effect in lacrimal tissues (Sullivan, 1989). Therefore the effects of sex hormones on the immune system cannot be generalized but must be evaluated independently. Some of the reasons for variability in results have been reviewed in detail elsewhere (Steinberg et al, 1979; Ansar Ahmed et al, 1985b). These include, dose of hormones, age and sex-hormonal status of animals, route and time of administration, the immunocompetence of the host, stress, the metabolism of hormones (e.g. metabolism of testosterone to oestrogen) resulting in alteration of biological activity, and differential response to various antigens. The initial encounter of sex hormones with the type of target cells, the variability of secondary messengers and gene activation events are other important considerations. The effects of sex hormones on the immune system to modulate immune responses are unequivocal. The burgeoning advances in cellular immunology, endocrinology and molecular biology, should provide a better understanding of: (1) the interactions of hormones with the immune system; (2) how hormones

  4. STAT3 governs hyporesponsiveness and granzyme B-dependent suppressive capacity in human CD4+ T cells

    PubMed Central

    Schmetterer, Klaus G.; Neunkirchner, Alina; Wojta-Stremayr, Daniela; Leitner, Judith; Steinberger, Peter; Pickl, Winfried F.

    2015-01-01

    Signal transducer and activator of transcription 3 (STAT3) integrates key signals of cell surface immune receptors, yet its precise role in cluster of differentiation (CD)4+ T cells is not well-established. Current research has indicated T-helper cell 17–inducing roles but also tolerogenic roles. To address this issue, human T cells were transduced with the constitutively active STAT3 mutant STAT3C. Following stimulation, STAT3C+ T cells up-regulated IL-10 (4.1 ± 0.5-fold; P < 0.001) and granzyme B (2.5 ± 1.2, P < 0.05) secretion, combined with significantly reduced IFN-γ (35 ± 5%), IL-2 (57 ± 4%), TNF-α (64 ± 8%), and IL-13 (89 ± 3%) secretion (P < 0.001). CD3/CD2- or CD3/CD28-activated STAT3C+ T cells revealed reduced proliferation (53.4 ± 23.5% and 70.5 ± 10.4%, respectively), which was independent of IL-10 production and significantly suppressed effector T cell proliferation by 68.7 ± 10.6% and 65.9 ± 2.6%, respectively (P < 0.001). Phenotypically, STAT3C-transgenic CD4+ T cells resembled effector T cells regarding expression of T regulatory cell markers, but up-regulated granzyme B expression levels by 2.4-fold (P < 0.05). Suppression was cell contact dependent and mediated by granzyme B-induced cell death, but was independent of IL-10 and TGF-β. Notably, peripheral blood CD4+CD45RA−lymphocyte activation gene-3+CD49+ type 1 regulatory T cells revealed activation-induced hyperphosphorylation of STAT3. In agreement, pharmacological inhibition of STAT3 activation partially reverted hyporesponsiveness of peripheral type 1 regulatory T cells (increasing their division index from 0.46 ± 0.11 to 0.89 ± 0.04; P < 0.01). These observations indicate a clear-cut relation between activation of STAT3 and the acquisition of a tolerogenic program, which is also used by peripheral blood type 1 regulatory T cells.—Schmetterer, K. G., Neunkirchner, A., Wojta-Stremayr, D., Leitner, J., Steinberger, P., Pickl, W. F. STAT3 governs hyporesponsiveness and

  5. Diffusion-enhanced Förster resonance energy transfer and the effects of external quenchers and the donor quantum yield.

    PubMed

    Jacob, Maik H; Dsouza, Roy N; Ghosh, Indrajit; Norouzy, Amir; Schwarzlose, Thomas; Nau, Werner M

    2013-01-10

    The structural and dynamic properties of a flexible peptidic chain codetermine its biological activity. These properties are imprinted in intrachain site-to-site distances as well as in diffusion coefficients of mutual site-to-site motion. Both distance distribution and diffusion determine the extent of Förster resonance energy transfer (FRET) between two chain sites labeled with a FRET donor and acceptor. Both could be obtained from time-resolved FRET measurements if their individual contributions to the FRET efficiency could be systematically varied. Because the FRET diffusion enhancement (FDE) depends on the donor-fluorescence lifetime, it has been proposed that the FDE can be reduced by shortening the donor lifetime through an external quencher. Benefiting from the high diffusion sensitivity of short-distance FRET, we tested this concept experimentally on a (Gly-Ser)(6) segment labeled with the donor/acceptor pair naphthylalanine/2,3-diazabicyclo[2.2.2]oct-2-ene (NAla/Dbo). Surprisingly, the very effective quencher potassium iodide (KI) had no effect at all on the average donor-acceptor distance, although the donor lifetime was shortened from ca. 36 ns in the absence of KI to ca. 3 ns in the presence of 30 mM KI. We show that the proposed approach had to fail because it is not the experimentally observed but the radiative donor lifetime that controls the FDE. Because of that, any FRET ensemble measurement can easily underestimate diffusion and might be misleading even if it employs the Haas-Steinberg diffusion equation (HSE). An extension of traditional FRET analysis allowed us to evaluate HSE simulations and to corroborate as well as generalize the experimental results. We demonstrate that diffusion-enhanced FRET depends on the radiative donor lifetime as it depends on the diffusion coefficient, a useful symmetry that can directly be applied to distinguish dynamic and structural effects of viscous cosolvents on the polymer chain. We demonstrate that the

  6. ALE3D Simulation and Measurement of Violence in a Fast Cookoff Experiment for LX-10

    SciTech Connect

    McClelland, M A; Maienschein, J L; Howard, W M; deHaven, M R

    2006-05-23

    Fast cookoff is of interest in the areas of fire hazard reduction and the development of directed energy systems for defense. During a fast cookoff (thermal explosion), high heat fluxes cause rapid temperature increases and ignition in thin boundary layers. We are developing ALE3D models to describe the thermal, chemical, and mechanical behavior during the heating, ignition, and explosive phases. The candidate models and numerical strategies are being evaluated using benchmark cookoff experiments. Fast cookoff measurements were made in a Scaled-Thermal-Explosion-eXperiment (STEX) for LX-10 (94.7% HMX, 5.3% Viton A) confined in a 4130 steel tube with reinforced end caps. Gaps were present at the side and top of the explosive charge to allow for thermal expansion. The explosive was heated until explosion using radiant heaters. Temperatures were measured using thermocouples positioned on the tube wall and in the explosive. During the explosion, the tube expansion and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. A fragment size distribution was constructed from fragments captured in Lexan panels. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A multi-step chemical kinetics model is employed for the HMX while a one-step model is used for the Viton. A pressure-dependent deflagration model is employed during the expansion. A Steinberg-Guinan model represents the mechanical behavior of the solid constituents while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. Parameters for the kinetics model were specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate were employed to determine parameters in the burn front model. The simulations include radiative and conductive transport across the dynamic gaps between the

  7. Constraints on the mantle and lithosphere dynamics from the observed geoid with the effect of visco-elasto-plastic rheology in the upper 300 km

    NASA Astrophysics Data System (ADS)

    Osei Tutu, Anthony; Steinberger, Bernhard; Rogozhina, Irina; Sobolev, Stephan

    2015-04-01

    used. Finally, given significant dispersion of geodynamic predictions from different seismic tomography models currently available, we further look for seismic models that provide predictions closest to observations at both regional and global scales. References 1. Hager B.H & O'Connell R.J., 1981. A simple global model of plate dynamics and mantle convection, J.Geophys. Res. 86, 4843-4867 2. Popov A.A., Sobolev S.V., 2008. SLIM3D: A tool for three-dimensional thermo- mechanical modelling of lithospheric deformation with elasto-visco-plastic rheology, J.pepi.2008.03.007 3. Steinberger B., 2014. Dynamic topography: A comparison between observations and models based on seismic tomography. (Submitted) 4. Becker T and Boschi L., 2002, A comparison of tomographic and geodynamic mantle models. , J.Geophys. Res. 115, 0148-0227

  8. The enzymatic and antioxidative stress response of Lemna minor to copper and a chloroacetamide herbicide.

    PubMed

    Obermeier, Michael; Schröder, Christian A; Helmreich, Brigitte; Schröder, Peter

    2015-12-01

    Lemna minor L., a widely used model plant for toxicity tests has raised interest for its application to phytoremediation due to its rapid growth and ubiquitous occurrence. In rural areas, the pollution of water bodies with heavy metals and agrochemicals poses a problem to surface water quality. Among problematic compounds, heavy metals (copper) and pesticides are frequently found in water bodies. To establish duckweed as a potential plant for phytoremediation, enzymatic and antioxidative stress responses of Lemna minor during exposure to copper and a chloroacetamide herbicide were investigated in laboratory studies. The present study aimed at evaluating growth and the antioxidative and glutathione-dependent enzyme activity of Lemna plants and its performance in a scenario for phytoremediation of copper and a chloroacetamide herbicide. Lemna minor was grown in Steinberg medium under controlled conditions. Plants were treated with CuSO4 (ion conc. 50 and 100 μg/L) and pethoxamide (1.25 and 2.5 μg/L). Measurements following published methods focused on plant growth, oxidative stress, and basic detoxification enzymes. Duckweed proved to survive treatment with the respective concentrations of both pollutants very well. Its growth was inhibited scarcely, and no visible symptoms occurred. On the cellular basis, accumulation of O2(-) and H2O2 were detected, as well as stress reactions of antioxidative enzymes. Duckweed detoxification potential for organic pollutants was high and increased significantly with incubation. Pethoxamide was found to be conjugated with glutathione. Copper was accumulated in the fronds at high levels, and transient oxidative defense reactions were triggered. This work confirms the significance of L. minor for the removal of copper from water and the conjugation of the selective herbicide pethoxamide. Both organic and inorganic xenobiotics induced different trends of enzymatic and antioxidative stress response. The strong increase of stress

  9. Deep structure and origin of active volcanoes in China

    NASA Astrophysics Data System (ADS)

    Zhao, D.

    2010-12-01

    Recent geophysical studies have provided important constraints on the deep structure and origin of the active intraplate volcanoes in Mainland China. Magmatism in the western Pacific arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab (e.g., Zhao et al., 2009a), while the intraplate magmatism in China has different origins. The active volcanoes in Northeast China (such as the Changbai and Wudalianchi) are caused by hot upwelling in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well (Zhao et al., 2009b). The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate (or Indian plate) (Lei et al., 2009a). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and Indian slab's deep subduction in the west down to the lower mantle (Lei et al., 2009b; Zhao, 2009). The stagnant slab finally collapses down to the bottom of the mantle, which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab-plume interactions (Zhao, 2009). References Lei, J., D. Zhao, Y. Su, 2009a. Insight into the origin of the Tengchong intraplate volcano and seismotectonics in southwest China from local and teleseismic data. J. Geophys. Res. 114, B05302. Lei, J., D. Zhao, B. Steinberger et al., 2009b. New seismic constraints on the upper mantle structure of the Hainan plume. Phys. Earth Planet. Inter. 173, 33-50. Zhao, D., 2009. Multiscale seismic tomography and mantle dynamics. Gondwana Res. 15, 297-323. Zhao, D., Z. Wang, N. Umino, A. Hasegawa, 2009a. Mapping the mantle wedge and interplate thrust zone of the northeast Japan arc. Tectonophysics 467, 89-106. Zhao, D., Y. Tian, J. Lei, L. Liu, 2009b. Seismic

  10. Designing across ages: Multi-agent-based models and learning electricity

    NASA Astrophysics Data System (ADS)

    Sengupta, Pratim

    Electricity is regarded as one of the most challenging topics for students at all levels -- middle school -- college (Cohen, Eylon, & Ganiel, 1983; Belcher & Olbert, 2003; Eylon & Ganiel, 1990; Steinberg et al., 1985). Several researchers have suggested that naive misconceptions about electricity stem from a deep incommensurability (Slotta & Chi, 2006; Chi, 2005) or incompatibility (Chi, Slotta & Leauw, 1994; Reiner, Slotta, Chi, & Resnick, 2000) between naive and expert knowledge structures. I first present an alternative theoretical framework that adopts an emergent levels-based perspective as proposed by Wilensky & Resnick (1999). From this perspective, macro-level phenomena such as electric current and resistance, as well as behavior of linear electric circuits, can be conceived of as emergent from simple, body-syntonic interactions between electrons and ions in a circuit. I argue that adopting such a perspective enables us to reconceive commonly noted misconceptions in electricity as behavioral evidences of "slippage between levels" -- i.e., these misconceptions appear when otherwise productive knowledge elements are sometimes inappropriately activated due to certain macro-level phenomenological cues only -- and, that the same knowledge elements when activated due to phenomenological cues at both micro- and macro-levels, can engender a deeper, expert-like understanding. I will then introduce NIELS (NetLogo Investigations In Electromagnetism, Sengupta & Wilensky, 2006, 2008, 2009), a low-threshold high-ceiling (LTHC) learning environment of multi-agent-based computational models that represent phenomena such as electric current and resistance, as well as the behavior of linear electric circuits, as emergent. I also present results from implementations of NIELS in 5th, 7th and 12th grade classrooms that show the following: (a) how leveraging certain "design elements" over others in NIELS models can create new phenomenological cues, which in turn can be

  11. Binary porous convection

    NASA Astrophysics Data System (ADS)

    Carey, Michael Richard

    Binary porous convection falls into the larger category of pattern formation---a symmetry breaking instability which creates a spatially periodic structure within a homogeneous system. The experiments and model presented in this dissertation indicate that an essential piece of physics is missing from the standard Darcian picture used to describe pattern formation in a porous medium convection system. Present theory predicts a bifurcation to an oscillatory state at onset for a binary mixture in a porous media over a wide range of experimental parameters (Brand and Steinberg, Physics Letters 93A 333 (1983)). This theory is inadequate in explaining the predominant large amplitude, backward, stationary overturning convection state observed in our experiments after transients have decayed. Convection experiments were visualized with magnetic resonance imaging and performed with a foam medium in slot and cylindrical geometries as well as a rectangular, packed bead system with water-ethanol mixtures. We explore the possibility that the difference between theory and experiment is due to enhanced solutal mixing not included in previous theories. The enhanced mixing of the fluid produces an effective diffusion coefficient that largely suppresses gradients in the concentration field, resulting in single-fluid like behavior. We model the experimental system with a Lorenz truncation of the binary Darcy equations with enhanced mixing. This model predicts results qualitatively similar to experiments: a forward bifurcation to small amplitude oscillations with a secondary backward bifurcation to large amplitude stationary convection. We have also developed an experimental nuclear magnetic resonance technique that measures the effective diffusion coefficient, D = D(v), as a function of velocity, v, for the individual species of the binary mixture simultaneously. However, the mixing effect measured in plug flow experiments is roughly two to three orders of magnitude too small to have

  12. Some remarks on waves in the solar wind

    NASA Technical Reports Server (NTRS)

    Kellogg, Paul J.

    1995-01-01

    Waves are significant to the solar wind in two ways as modifiers of the particle distribution functions, and as diagnostics. In addition, the solar wind serves as an important laboratory for the study of plasma wave processes, as it is possible to make detailed measurements of phenomena which are too small to be easily measured by laboratory sized sensors. There are two areas where waves (we include discontinuities under this heading) must make important modifications of the distribution functions: in accelerating the alpha particles to higher speeds than the protons (Marsch et al.) and in accelerating the solar wind itself. A third area is possibly in maintaining the relative isotropy of the solar wind ion distribution in the solar wind rest frame. As the solar wind is nearly collisionless, the ions should conserve magnetic moment in rushing out from the sun, and therefore Tperp/B should be relatively constant, but it is obviously not. This has not received much attention. The waves, both electromagnetic and electrostatic, which are pan of the solar Type 111 burst phenomenon, have been extensively studied as examples of nonlinear plasma phenomena, and also used as remote sensors to trace the solar magnetic field. The observations made by Ulysses show that the field can be traced in this way out to perhaps a little more than an A.U., but then the electromagnetic pan of the type 111 burst fades out. Nevertheless, sometimes Langmuir waves appear at Ulysses at an appropriate extrapolated time. This seems to support the picture in which the electromagnetic waves at the fundamental plasma frequency are trapped in density fluctuations. Langmuir waves in the solar wind are usually in quasi-thermal equilibrium quasi because the solar wind itself is not isothermal. The Observatory of Paris group (Steinberg. Meyer-Vernet, Hoang) has exploited this with an experiment on WIND which is capable of providing density and temperature on a faster time scale than hitherto. Recently

  13. Global Paleobathymetry for the Cenomanian-Turonian (90 Ma)

    NASA Astrophysics Data System (ADS)

    Goswami, A.; Olson, P.; Hinnov, L. A.; Gnanadesikan, A.

    2014-12-01

    , C., Steinberger, B., Heine, C., 2008a, Science, 319, 1357-1362. Scotese, C., 2011, PALEOMAP Project, Arlington, Texas. Turcotte, D., Schubert, G., 2002, Cambridge University Press, Cambridge, 456 p. Whittaker, J., Goncharov, A., Williams, S., Müller, R., Leitchenkov, G., 2013, Geochemistry, Geophysics, Geosystems. DOI:10.1002/ggge.20181

  14. Mechanism and Significance of Post-Translational Modifications in the Large (LS) and Small (SS) Subunits of Ribulose-1,5 Bisphosphate Carboxylase/Oxygenase

    SciTech Connect

    Houtz, Robert, L.

    2012-11-09

    . Additionally, the tight initial binding of Rubisco LSMT to Rubisco also allowed us to design a novel immobilized complex between Rubisco and Rubisco LSMT, which allowed for an unambiguous demonstration of the requirement for trimethyllysine formation prior to disassociation of the Rubisco LSMT:Rubisco complex, and therefore proof of the processive mechanism for methyl group transfer. These kinetic studies also demonstrated that an important factor has been overlooked in all kinetic analyses of SET domain protein methyltransferases reported to date. This factor is the influence of the low turnover number for SET domain protein methyltransferases and how, relative to the time-frame of kinetic enzyme assays, this can generate changes in kinetic profiles shifting reciprocal plot patterns from random/ordered bi-bi to the real kinetic reaction mechanism plots of ping-pong. Although the ternary complexes of Rubisco LSMT with S-Adenosylhomocysteine and lysine and monomethyllysine were informative in regard to reaction mechanism, they were not helpful in identifying the mechanism used by Rubisco LSMT for determining substrate specificity. We were unsuccessful at obtaining ternary complexes of Rubisco LSMT with bound synthetic polypeptide substrates, as has been reported for several histone methyltransferases. However, we were able to model a polypeptide sequence corresponding to the N-terminal region of the LS of Rubisco into the apparent substrate binding cleft in Rubisco LSMT. Knowledge of the determinants of polypeptide substrate specificity are important for identifying possible alternate substrates, as well as the possibility of generating more desirable substrates amenable to site-directed mutagenesis experiments unlike Rubisco. We determined that Rubisco LSMT is capable of methylating synthetic polypeptide mimics of the N-terminal region of the LS, both free as well as conjugated to keyhole limpet hemacyanin, but with considerable less efficiency than intact holoenzyme.

  15. Substrate specificity and stereoselectivity of horse liver alcohol dehydrogenase. Kinetic evaluation of binding and activation parameters controlling the catalytic cycles of unbranched, acyclic secondary alcohols and ketones as substrates of the native and active-site-specific Co(II)-substituted enzyme.

    PubMed

    Adolph, H W; Maurer, P; Schneider-Bernlöhr, H; Sartorius, C; Zeppezauer, M

    1991-11-01

    1. The steady-state parameters kcat and Km and the rate constants of hydride transfer for the substrates isopropanol/acetone; (S)-2-butanol, (R)-2-butanol/2-butanone; (S)-2-pentanol, (R)-2-pentanol/2-pentanone; 3-pentanol/3-pentanone; (S)-2-octanol and (R)-2-octanol have been determined for the native Zn(II)-containing horse-liver alcohol dehydrogenase (LADH) and the specific active-site-substituted Co(II)LADH. 2. A combined evaluation of steady-state kinetic data and rate constants obtained from stopped-flow measurements, allowed the determination of all rate constants of the following ordered bi-bi mechanism: E in equilibrium E.NAD in equilibrium E.NAD.R1R2 CHOH in equilibrium E.NADH.R1R2CO in equilibrium E.NADH in equilibrium E. 3. On the basis of the different substrate specificities of LADH and yeast alcohol dehydrogenase (YADH), a procedure has been developed to evaluate the enantiomeric product composition of ketone reductions. 2-Butanone and 2-pentanone reductions revealed (S)-2-butanol (86%) and (S)-2-pentanol (95%) as the major products. 4. The observed enantioselectivity implies the existence of two productive ternary complexes; E.NADH.(pro-S) 2-butanone and E.NADH.(pro-R) 2-butanone. All rate constants describing the kinetic pathways of the system (S)-2-butanol, (R)-2-butanol/2-butanone have been determined. These data have been used to estimate the expected enantiomer product composition of 2-butanone reductions using apparent kcat/Km values for the two different ternary-complex configurations of 2-butanone. Additionally, these data have been used for computer simulations of the corresponding reaction cycles. Calculated, simulated and experimental data were found to be in good agreement. Thus, the system (S)-2-butanol, (R)-2-butanol/2-butanone is the first example of a LADH-catalyzed reaction for which the stereochemical course could be described in terms of rate constants of the underlying mechanism. 5. The effects of Co(II) substitution on the

  16. Feasibility of using benthic invertebrates as indicators of stream quality in Hawaii

    USGS Publications Warehouse

    Wolff, Reuben H.

    2005-01-01

    Macroinvertebrates were collected from 19 sites on 14 streams on the island of Oahu and from 9 sites on 7 streams on the island of Kauai to evaluate associations between macroinvertebrate assemblages and environmental variables and to determine whether or not it would be feasible, in future studies, to develop macroinvertebrate metrics that would indicate stream quality based on the macroinvertebrate assemblages and/or components of the assemblages. The purpose of applying rapid bioassessment techniques is to identify stream quality problems and to document changes in stream quality. Samples were collected at 10 sites in 1999, 3 sites in 2000, and 5 sites in 2003 on Oahu and at 9 sites on Kauai in 2003. Additionally, multiple year and multiple reach samples were collected at 1 site on Oahu. Macroinvertebrates were collected primarily from boulder/cobble riffles or from the fastest flowing habitat when riffles were absent. Although most streams in Hawaii originate in mountainous, forested areas, the lower reaches often drain urban, agricultural, or mixed land-use areas. The macroinvertebrate community data were used to identify metrics that could best differentiate between sites according to levels of environmental impairment. Environmental assessments were conducted using land-use/land-cover data, bed-sediment and fish-tissue contaminant data, and reach-level environmental data using a calibration set of 15 sites. The final scores of the environmental assessments were used to classify the sites into three categories of impairment: mild, moderate or severe. A number of invertebrate metrics were then tested and calibrated to the environmental assessments scores. The individual metrics that were the best at discerning environmental assessments among the sites were combined into a multimetric benthic index of biotic integrity (BIBI). These metrics were: total invertebrate abundance, taxa richness, insect relative abundance, amphipod abundance, crayfish presence or

  17. Biomimetic Production of Hydrogen

    NASA Astrophysics Data System (ADS)

    Gust, Devens

    2004-03-01

    organism. Some possible approaches to achieving this will be discussed. References (1) Gust, D.; Moore, T. A.; Moore, A. L. "Mimicking photosynthetic solar energy transduction," Acc. Chem. Res. 2001, 34, 40-48. (2) Kodis, G.; Liddell, P. A.; de la Garza, L.; Clausen, P. C.; Lindsey, J. S.; Moore, A. L.; Moore, T. A.; Gust, D. "Efficient energy transfer and electron transfer in an artificial photosynthetic antenna-reaction center complex," J. Phys. Chem. A 2002, 106, 2036-2048. (3) Liddell, P. A.; Kuciauskas, D.; Sumida, J. P.; Nash, B.; Nguyen, D.; Moore, A. L.; Moore, T. A.; Gust, D. "Photoinduced charge separation and charge recombination to a triplet state in a carotene-porphyrin-fullerene triad," J. Am. Chem. Soc. 1997, 119, 1400-1405. (4) Steinberg-Yfrach, G.; Liddell, P. A.; Hung, S.-C.; Moore, A. L.; Gust, D.; Moore, T. A. "Artificial photosynthetic reaction centers in liposomes: Photochemical generation of transmembrane proton potential," Nature 1997, 385, 239-241. (5) Steinberg-Yfrach, G.; Rigaud, J.-L.; Durantini, E. N.; Moore, A. L.; Gust, D.; Moore, T. A. "Light-driven production of ATP catalyzed by F0F1-ATP synthase in an artificial photosynthetic membrane," Nature 1998, 392, 479-482. (6) de la Garza, L.; Jeong, G.; Liddell, P. A.; Sotomura, T.; Moore, T. A.; Moore, A. L.; Gust, D. "Enzyme-based photoelectrochemical biofuel cell," J. Phys. Chem. B 2003, 107, 10252-10260.

  18. Long-term stability of Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle and Velocity Provinces at the base of the mantle and near the equator

    NASA Astrophysics Data System (ADS)

    Beuchert, Marcus; Podladchikov, Yuri; Torsvik, Trond

    2010-05-01

    The observed long-term stability of Large Low Shear Velocity Provinces (LLSVPs) at the base of the mantle and near the equator raises two major questions: Even if gravitational stability can in principle be explained from intrinsically increased density of LLSVP material, (i) how can LLSVPs retain their shape and coherence within a vigorously convecting mantle over long geological times given their expectedly relatively low viscosities? We devised a numerical convection model to investigate this question of dynamical stability. Our results indicate that dense, low viscous LLSVPs can remain stable in the convecting mantle over long geological time. Yet, we observe in our numerical model that LLSVPs, whereas remaining dynamically stable, move laterally along the base of the model, thus leading to question (ii): How can we explain the stability of LLSVPs near the equator for at least the last 300 m.y. given their ability to move laterally? A common explanation for the fact that LLSVPs are situated near the equator is that true polar wander (TPW) arising from the geoid anomalies associated with LLSVPs would cause their rotation towards and subsequent stabilization at the equator. Indeed, if LLSVPs move along the base of the mantle and stay at antipodal position, TPW would reorient the Earth's rotation axis such that the anomalies remain at the equator. Yet, Steinberger and Torsvik (2008) show that TPW did not occur in a plane containing the LLSVPs during the last 320 m.y., meaning that TPW played no role in the near-equatorial stabilization of LLSVPs during that time. Consequently, the lack of latitudinal migration of LLSVPs over long geological time requires explanation. We suggest that centrifugal acceleration, even though providing only small driving forces, might be important in explaining migration of dense, low viscous LLSVPs to the equator, given the vast amount of time available in Earth history, and their subsequent stabilization near the equator. A first

  19. The Solid Earth Research and Teaching Environment, a new software framework to share research tools in the classroom and across disciplines

    NASA Astrophysics Data System (ADS)

    Milner, K.; Becker, T. W.; Boschi, L.; Sain, J.; Schorlemmer, D.; Waterhouse, H.

    2009-12-01

    The Solid Earth Teaching and Research Environment (SEATREE) is a modular and user-friendly software framework to facilitate the use of solid Earth research tools in the classroom and for interdisciplinary research collaboration. SEATREE is open source and community developed, distributed freely under the GNU General Public License. It is a fully contained package that lets users operate in a graphical mode, while giving more advanced users the opportunity to view and modify the source code. Top level graphical user interfaces which initiate the calculations and visualize results, are written in the Python programming language using an object-oriented, modern design. Results are plotted with either Matlab-like Python libraries, or SEATREE’s own Generic Mapping Tools wrapper. The underlying computational codes used to produce the results can be written in any programming language and accessed through Python wrappers. There are currently four fully developed science modules for SEATREE: (1) HC is a global geodynamics tool based on a semi-analytical mantle-circulation program based on work by B. Steinberger, Becker, and C. O'Neill. HC can compute velocities and tractions for global, spherical Stokes flow and radial viscosity variations. HC is fast enough to be used for classroom instruction, for example to let students interactively explore the role of radial viscosity variations for global geopotential (geoid) anomalies. (2) ConMan wraps Scott King’s 2D finite element mantle convection code, allowing users to quickly observe how modifications to input parameters affect heat flow over time. As seismology modules, SEATREE includes, (3), Larry, a global, surface wave phase-velocity inversion tool and, (4), Syn2D, a Cartesian tomography teaching tool for ray-theory wave propagation in synthetic, arbitrary velocity structure in the presence of noise. Both underlying programs were contributed by Boschi. Using Syn2D, students can explore, for example, how well a given

  20. Pions to Quarks

    NASA Astrophysics Data System (ADS)

    Brown, Laurie Mark; Dresden, Max; Hoddeson, Lillian

    2009-01-01

    Part I. Introduction; 1. Pions to quarks: particle physics in the 1950s Laurie M Brown, Max Dresden and Lillian Hoddeson; 2. Particle physics in the early 1950s Chen Ning Yang; 3. An historian's interest in particle physics J. L. Heilbron; Part II. Particle discoveries in cosmic rays; 4. Cosmic-ray cloud-chamber contributions to the discovery of the strange particles in the decade 1947-1957 George D. Rochester; 5. Cosmic-ray work with emulsions in the 1940s and 1950s Donald H. Perkins; Part III. High-energy nuclear physics; Learning about nucleon resonances with pion photoproduction Robert L. Walker; 7. A personal view of nucleon structure as revealed by electron scattering Robert Hofstadter; 8. Comments on electromagnetic form factors of the nucleon Robert G. Sachs and Kameshwar C. Wali; Part IV. The new laboratory; 9. The making of an accelerator physicist Matthew Sands; 10. Accelerator design and construction in the 1950s John P. Blewett; 11. Early history of the Cosmotron and AGS Ernest D. Courant; 12. Panel on accelerators and detectors in the 1950s Lawrence W. Jones, Luis W. Alvarez, Ugo Amaldi, Robert Hofstadter, Donald W. Kerst, Robert R. Wilson; 13. Accelerators and the Midwestern Universities Research Association in the 1950s Donald W. Kerst; 14. Bubbles, sparks and the postwar laboratory Peter Galison; 15. Development of the discharge (spark) chamber in Japan in the 1950s Shuji Fukui; 16. Early work at the Bevatron: a personal account Gerson Goldhaber; 17. The discovery of the antiproton Owen Chamberlain; 18. On the antiproton discovery Oreste Piccioni; Part V. The Strange Particles; 19. The hydrogen bubble chamber and the strange resonances Luis W. Alvarez; 20. A particular view of particle physics in the fifties Jack Steinberger; 21. Strange particles William Chinowsky; 22. Strange particles: production by Cosmotron beams as observed in diffusion cloud chambers William B. Fowler; 23. From the 1940s into the 1950s Abraham Pais; Part VI. Detection of the

  1. Numerical Modeling of Deep Mantle Convection: Advection and Diffusion Schemes for Marker Methods

    NASA Astrophysics Data System (ADS)

    Mulyukova, Elvira; Dabrowski, Marcin; Steinberger, Bernhard

    2013-04-01

    Thermal and chemical evolution of Earth's deep mantle can be studied by modeling vigorous convection in a chemically heterogeneous fluid. Numerical modeling of such a system poses several computational challenges. Dominance of heat advection over the diffusive heat transport, and a negligible amount of chemical diffusion results in sharp gradients of thermal and chemical fields. The exponential dependence of the viscosity of mantle materials on temperature also leads to high gradients of the velocity field. The accuracy of many numerical advection schemes degrades quickly with increasing gradient of the solution, while the computational effort, in terms of the scheme complexity and required resolution, grows. Additional numerical challenges arise due to a large range of length-scales characteristic of a thermochemical convection system with highly variable viscosity. To examplify, the thickness of the stem of a rising thermal plume may be a few percent of the mantle thickness. An even thinner filament of an anomalous material that is entrained by that plume may consitute less than a tenth of a percent of the mantle thickness. We have developed a two-dimensional FEM code to model thermochemical convection in a hollow cylinder domain, with a depth- and temperature-dependent viscosity representative of the mantle (Steinberger and Calderwood, 2006). We use marker-in-cell method for advection of chemical and thermal fields. The main advantage of perfoming advection using markers is absence of numerical diffusion during the advection step, as opposed to the more diffusive field-methods. However, in the common implementation of the marker-methods, the solution of the momentum and energy equations takes place on a computational grid, and nodes do not generally coincide with the positions of the markers. Transferring velocity-, temperature-, and chemistry- information between nodes and markers introduces errors inherent to inter- and extrapolation. In the numerical scheme

  2. RHUM-RUM investigates La Réunion mantle plume from crust to core

    NASA Astrophysics Data System (ADS)

    Sigloch, K.; Barruol, G.

    2012-12-01

    neighboring ridges of the Indian Ocean. There is in particular a long-standing hypothesis, not yet examined seismically, that channelized plume flow beneath the aseismic Rodrigues Ridge could feed the Central Indian Ridge at 1000 km distance. The RHUM-RUM group (www.rhum-rum.net): * IPG Paris & Géosciences Réunion: G. Barruol, J.P. Montagner, E. Stutzmann, F.R. Fontaine, C. Deplus, M. Cannat, G. Roult, J. Dyment, S. Singh, W. Crawford, C. Farnetani, N. Villeneuve, L. Michon. V. Ferrazzini, Y. Capdeville. * Univ. Munich (LMU): K. Sigloch, H. Igel. AWI Bremerhaven: V. Schlindwein. Univ. Frankfurt: G. Rümpker. Univ. Münster: C. Thomas. Univ. Bonn: S. Miller. * Géosciences Montpellier: C. Tiberi, A. Tommasi, D. Arcay, C. Thoraval. * Mauritius Oceanography Institute: D. Bissessur. Univ. Antananarivo: G. Rambolamanana. SEYPEC Seychelles Petroleum: P. Samson, P. Joseph. * Other institutes: A. Davaille, M. Jegen, M. Maia, G. Nolet, D. Sauter, B. Steinberger.

  3. RHUM-RUM investigates La Réunion mantle plume from crust to core

    NASA Astrophysics Data System (ADS)

    Sigloch, Karin; Barruol, Guilhem

    2013-04-01

    neighboring ridges of the Indian Ocean. There is in particular a long-standing hypothesis, not yet examined seismically, that channelized plume flow beneath the aseismic Rodrigues Ridge could feed the Central Indian Ridge at 1000 km distance. The RHUM-RUM group (www.rhum-rum.net): * IPG Paris & Géosciences Réunion: G. Barruol, J.P. Montagner, E. Stutzmann, F.R. Fontaine, C. Deplus, M. Cannat, G. Roult, J. Dyment, S. Singh, W. Crawford, C. Farnetani, N. Villeneuve, L. Michon. V. Ferrazzini, Y. Capdeville. * Univ. Munich (LMU): K. Sigloch, H. Igel. AWI Bremerhaven: V. Schlindwein. Univ. Frankfurt: G. Rümpker. Univ. Münster: C. Thomas. Univ. Bonn: S. Miller. * Géosciences Montpellier: C. Tiberi, A. Tommasi, D. Arcay, C. Thoraval. * Mauritius Oceanography Institute: D. Bissessur. Univ. Antananarivo: G. Rambolamanana. SEYPEC Seychelles Petroleum: P. Samson, P. Joseph. * Other institutes: A. Davaille, M. Jegen, M. Maia, G. Nolet, D. Sauter, B. Steinberger.

  4. New 40Ar/39Ar age progression for the Louisville hot spot trail and implications for inter-hot spot motion

    NASA Astrophysics Data System (ADS)

    Koppers, Anthony A. P.; Gowen, Molly D.; Colwell, Lauren E.; Gee, Jeffrey S.; Lonsdale, Peter F.; Mahoney, John J.; Duncan, Robert A.

    2011-12-01

    In this study we present 42 new 40Ar/39Ar incremental heating age determinations that contribute to an updated age progression for the Louisville seamount trail. Louisville is the South Pacific counterpart to the Hawaiian-Emperor seamount trail, both trails representing intraplate volcanism over the same time interval (˜80 Ma to present) and being examples of primary hot spot lineaments. Our data provide evidence for an age-progressive trend from 71 to 21 Ma. Assuming fixed hot spots, this makes possible a direct comparison to the Hawaiian-Emperor age progression and the most recent absolute plate motion (APM) model (WK08G) of Wessel and Kroenke (2008). We observe that for the Louisville seamount trail the measured ages are systematically older relative to both the WK08G model predictions and Hawaiian seamount ages, with offsets ranging up to 6 Myr. Taking into account the uncertainty about the duration of eruption and magmatic succession at individual Louisville volcanoes, these age offsets should be considered minimum estimates, as our sampling probably tended to recover the youngest lava flows. These large deviations point to either a contribution of inter-hot spot motion between the Louisville and Hawaiian hot spots or to a more easterly location of the Louisville hot spot than the one inferred in the WK08G model. Both scenarios are investigated in this paper, whereby the more eastern hot spot location (52.0°S, 134.5°W versus 52.4°S, 137.2°W) reduces the average age offset, but still results in a relatively large maximum offset of 3.7 Myr. When comparing the new ages to the APM models (S04P, S04G) by Steinberger et al. (2004) that attempt to compensate for the motion of hot spots in the Pacific (Hawaii) or globally (Hawaii, Louisville, Reunion and Walvis), the measured and predicted ages are more in agreement, showing only a maximum offset of 2.3 Myr with respect to the S04G model. At face value these more advanced APM models, which consider both plate and

  5. In situ measurement of mesopelagic particle sinking rates and the control of carbon transfer to the ocean interior during the Vertical Flux in the Global Ocean (VERTIGO) voyages in the North Pacific

    NASA Astrophysics Data System (ADS)

    Trull, T. W.; Bray, S. G.; Buesseler, K. O.; Lamborg, C. H.; Manganini, S.; Moy, C.; Valdes, J.

    2008-07-01

    sinking slower than 137 m d -1. At K2, less than 1% of the POC flux sank at >820 m d -1, but a large fraction (˜15-45%) of the flux was contributed by other fast-sinking classes (410 and 205 m d -1). PIC and BSi minerals were not present in higher proportions in the faster sinking fractions, but the observations were too limited to rule out a ballasting contribution to the control of sinking rates. Photographic evidence for a wide range of particle types within individual sinking-rate fractions suggests that biological processes that set the porosity and shape of particles are also important and may mask the role of minerals. Comparing the spectrum of sinking rates observed at K2 with the power-law profile of flux attenuation with depth obtained from other VERTIGO sediment traps deployed at multiple depths [Buesseler, K.O., Lamborg, C.H., Boyd, P.W., Lam, P.J., Trull, T.W., Bidigare, R.R., Bishop, J.K.B., Casciotti, K.L., Dehairs, F., Elskens, M., Honda, M., Karl, D.M., Siegel, D., Silver, M., Steinberg, D., Valdes, J., Van Mooy, B., Wilson, S.E., 2007b. Revisiting carbon flux through the Ocean's twilight zone. Science 316(5824), 567-570, doi: 10.1126/science.1137959] emphasizes the importance of particle transformations within the mesopelagic zone in the control of carbon transport to the ocean interior.

  6. A new phase of matter in Oakland

    SciTech Connect

    Klein, Spencer; Nystrand, Joakim

    2004-03-18

    Recent results from the Relativistic Heavy Ion Collider (RHIC) and the phase diagram of matter at very high energies were the focal points of Quark Matter 2004, held January 10-17, 2004 in the Oakland, California convention center. About 700 participants, including 125 students, from 28 countries gathered for 5 days of plenary and parallel sessions. Besides the scientific discussions, participants enjoyed an afternoon of excursions; choices included visits to San Francisco, the Muir woods, and, of course, a chance to sample Napa Valley wines. There was also a day of introductory lectures for graduate students and a separate afternoon program for 50 local high school teachers. The ''Quark Matter'' conference series has evolved into the premier venue for relativistic heavy ion collisions, and QM2004 was no exception. The 44 plenary and 92 parallel session talks featured a veritable flood of data from STAR (Kai Schweda, LBNL), PHENIX (Tony Frawley, Florida State), PHOBOS (Peter Steinberg, BNL) and BRAHMS (Michael Murray, Kansas), at RHIC. This was accompanied by contributions from HERMES ( Pasquale DiNezza, Frascati) and HERA-B (Joakim Spengler, Heidelberg) and continuing analyses from NA-49 (Marek Gazdzicki, Frankfurt) and NA-57 (Giuseppe Bruno, Bari) at the CERN SPS. The theoretical contributions presented a broad range of models and calculations, from microscopic particle-by-particle simulations to hydrodynamic models that model the bulk behavior using an equation of state. A focus of much discussion was the question ''Have we found the Quark Gluon Plasma (QGP)?'' This search was the prime motivation to build RHIC. Although the RHIC experiments made no formal statement, most conference attendees seemed to feel that the answer was yes. No single measurement makes the case, but the variety of data featured at QM2004 seems most easily explained in the context of a QGP. Some of the signatures included the suppression of high transverse momentum (pT) particles and

  7. Impact of different detachment topographies on pull-apart basin evolution - analog modelling and computer visualisation

    NASA Astrophysics Data System (ADS)

    Hoprich, M.; Decker, K.; Grasemann, B.; Sokoutis, D.; Willingshofer, E.

    2009-04-01

    floor. The surface of the model was photographed after each deformation increment through the experiment. Pictures of serial cross sections cut through the models in their final state every 4 cm were also taken and interpreted. The formation of en-echelon normal faults with relay ramps is observed in all models. These faults are arranged in an acute angle to the basin borders, according to a Riedel-geometry. In the case of an asymmetric basin they emerge within the non-moving fault block. Substantial differences between the models are the number, the distance and the angle of these Riedel faults, the length of the bounding strike-slip faults and the cross basin symmetry. A flat detachment produces straight fault traces, whereas inclined detachments (or inclined ramps) lead to "bending" of the normal faults, rollover and growth strata thickening towards the faults. Positions and the sizes of depocenters also vary, with depocenters preferably developing above ramp-flat-transitions. Depocenter thicknesses increase with ramp heights. A similar relation apparently exists in the natural Vienna basin, which shows ramp-like structures in the detachment just underneath large faults like the Steinberg normal fault and the associated depocenters. The 3-ramp-model also reveals segmentation of the basin above the lowermost ramp. The evolving structure is comparable to the Wiener Neustadt sub-basin in the southern part of the Vienna basin, which is underlain by a topographical high of the detachment. Cross sections through the ductile model show a strong disintergration into a horst-and-graben basin. The thin silicon putty base influences the overlying strata in a way that the basin - unlike the "dry" sand models - becomes very flat and shallow. The top view shows an irregular basin shape and no rhombohedral geometry, which characterises the Vienna basin. The ductile base also leads to a symmetrical distribution of deformation on both fault blocks, even though only one fault block is

  8. PREFACE: EmQM13: Emergent Quantum Mechanics 2013

    NASA Astrophysics Data System (ADS)

    2014-04-01

    these proceedings represent the talks of the invited speakers as written immediately after the symposium. The volume starts with a contribution by organizers Jan Walleczek and Gerhard Grössing, essentially explaining why emergent quantum mechanics, and other deterministic approaches to quantum theory, must be considered viable approaches in quantum foundations today. This is followed by the exposition of Stephen Adler's talk who introduced to a general audience key questions at the current frontiers of quantum mechanics during the opening evening (with the contents of his conference talk appearing elsewhere). The conference proceedings then continues with the presentations as given in their chronological order i.e. starting with the opening talk of the scientific program by Gerard 't Hooft. While the page number was restricted for all invited speakers, the paper by Jeff Tollaksen was given more space, as his invited collaborator Yakir Aharonov was unable to deliver a separate talk, in order to represent both contributions in one paper. Note that the talks of all speakers, including the talks of those who could not be represented in this volume (M. Arndt, B. Braverman, C. Brukner, S. Colin, Y. Couder, B. Poirier, A. Steinberg, G. Weihs and H. Wiseman) are freely available on the conference website as video presentations (http://www.emqm13.org). The organizers wish to express their gratitude to Siegfried Fussy and Herbert Schwabl from AINS for the organizational support. The organizers also wish to thank Bruce Fetzer, President and CEO, John E. Fetzer Memorial Trust, and the Members of the Board of Trustees, for their strong support and for funding this symposium. We also wish to thank the Austrian Academy of Sciences for allowing the symposium to be held on their premises, and Anton Zeilinger, President of the Austrian Academy of Sciences, for his welcome address. The expertise of the Members of the Scientific Advisory Board of the EmQM13 symposium, Ana Maria Cetto

  9. Humic first, A new theory on the origin of life

    NASA Astrophysics Data System (ADS)

    Daei, Mohammad Ali; Daei, Manijeh

    2016-04-01

    other enantiomers, because their spatial structure dictate, as did so regarding elemental selection. References: 1- Miller, Stanly L." production of amino acid under possible primitive Earth conditions" Science 117:528.(may 1953) 2- Encyclopedia Britannica website "carbonaceous contrite" October 17, 2014 3- Shapiro, Robert " A simpler origin for life" Science American February 12 . 2007 4- Pettit, Robert, "organic matter, humus, humate, humic acid, fulvic acid humin: their importance in soil fertility and plant health" 5- International Humic Substances Society website, " What are humic substances" 6- Humic, Fulvic and microbial balance: organic soil conditioning, by William R. Jackson 1993, pag 165-167 7- Steinberg, Christian E.W "Ecology of humic substances in freshwater-determination from geochemistry to ecological niches" (2003)

  10. Titanium (IV) sol-gel chemistry in varied gravity environments

    NASA Astrophysics Data System (ADS)

    Hales, Matthew; Martens, Wayde; Steinberg, Theodore

    . The test systems and experimental results obtained will be presented. 1. Okubo, T., Tsuchida, A., Okuda, T., Fujitsuna, K., Ishikawa, M., Morita, T., Tada, T. , Kinetic Analyses of Colloidal Crystallization in Microgravity -Aircraft Experiments. . Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1999. 153: p. 515-524. 2. Okubo, T., Tsuchida, A., Kobayashi, K., Kuno, A., Morita, T., Fujishima, M., Kohno, Y., Kinetic Study of the Formation Reaction of Colloidal Silica Spheres in Microgravity Using Aircraft. Colloid Polymer Science, 1999. 277(5): p. 474-478. 3. Pienaar, C.L., Chiffoleau, G. J. A., Follens, L. R. A., Martens, J. A., Kirschhock, C. E. A., Steinberg, T. A., Effect of Gravity on the Gelation of Silica Sols. Chem. Mater., 2007. 19(4): p. 660-664. 4. Smith, D.D., et al., Effect of Microgravity on the Growth of Silica Nanostructures. Langmuir, 2000. 16(26): p. 10055-10060. 5. Zhang, X., Johnson, D.P., Manerbino, A.R., Moore, J.J., Schowengerdt, F. , Recent Mi-crogravity Results in the Synthesis of Porous Materials. AIP Conference Proceedings (Space Technology and Applications International Forum-1999, Pt. 1), 1999. 458: p. 88-93. 6. Dunbar, P.B., Bendzko, N.J.,, 1H and 13C NMR observation of the reaction of acetic acid with titanium isopropoxide. Materials Chemistry and Physics, 1999. 59: p. 26-35. 7. Krunks, M., Oja, I., T˜nsuaadu, K., Es-Souni, M., Gruselle, M., Niinistü,. L, Thermoanalytical study of acetylacetonate-modified titanium (iv) isopropoxide as precursor for TiO2 films. Journal of Thermal Analysis and Calorimetry, 2005: p. 483-488. 8. Moran, P.D., Bowmaker, G. A., Cooney, R. P., Vibrational Spectra and Molecular Associa-tion of Titanium Tetraisopropoxide. Inorg. Chem., 1998. 37(1): p. 2741-2748. 9. Somogyvari, A., Serpone, N.,, Evidence for five-coordination in titanium(1V) complexes. A nuclear magnetic resonance investigation. Canadian Journal of Chemistry, 1977. 56: p. 316-319.

  11. The "heartbeat of the proton"

    NASA Astrophysics Data System (ADS)

    Weisskopf, Victor F.

    Once Nino came to my office to tell me about his ideas of studying lepton pair production at PS. I was still not Director General, but Research Director at CERN. In addition to (e+e-) and (μ+μ-) pairs, he wanted to search for (e±μ∓) pairs as a signature of a new lepton carrying its own lepton number. He told me that if such a lepton existed with one GeV mass, it would have escaped detection in hadron accelerator experiments for two reasons: i) it would decay with a lifetime of order 10-11 sec and ii) because there is no π → μ mechanism for such a heavy new lepton: for its production a time-like photon would be needed. Time-like photons could be produced in hadronic interactions: for example in (bar{p}p) annihilation. This was before Lederman-Schwartz and Steinberger had discovered the two neutrinos. To think of a "sequential" Heavy Lepton and to work out the possible ways to get it in a hadron machine was for me extremely interesting Nino had just finished his first high precision work on the muon (g-2). It was some time after the Rochester Conference in 1960. I gave Nino the following suggestion: if you want to search for something so revolutionary as a Heavy Lepton carrying its own lepton number you should work out a proposal for a series of experiments where the study of lepton pairs (e+e-) and (μ+μ-) could be justified in terms of physics accepted by the community. In addition a high intensity antiproton beam was needed. He came later to tell me that he had two very good friends, both excellent engineers: Mario Morpurgo and Guido Petrucci. A very high intensity antiproton beam could be built to study the electromagnetic form factor of the proton in the time-like region. If the proton was "point-like" in the time-like region, the rate of time-like photons yielding (e+e-) and (μ+μ-) pairs could be accessible to experimental observation, thus allowing to establish some limits on the new Heavy Lepton mass, or to see it, via the (e±μ∓) channel. The

  12. PREFACE: Turbulent Mixing and Beyond Turbulent Mixing and Beyond

    NASA Astrophysics Data System (ADS)

    Abarzhi, Snezhana I.; Gauthier, Serge; Rosner, Robert

    2008-10-01

    , Italy) V Steinberg (Weiznmann Institute, Israel) A L Velikovich (Naval Research Laboratory, USA) P K Yeung (Georgia Institute of Technology, USA) F A Williams (University of California at San Diego, USA) We would like to thank all the authors and the referees for their contributions to this Topical Issue and for offering their expertise, time and effort We cordially invite the reader to take a look at this Topical Issue for information on the frontiers of theoretical, numerical and experimental research and technology The Organizing Committee hopes the TMB Conference will serve to advance the state-of-the-art in understanding of fundamental physical properties of turbulent mixing and turbulence in unsteady flows and will have an impact on predictive modeling capabilities, physical description and, ultimately, control of these complex processes Snezhana I Abarzhi, Serge Gauthier, Robert Rosner Chicago, 20 Nov 2008

  13. Life cycle assessment in support of sustainable transportation

    NASA Astrophysics Data System (ADS)

    Eckelman, Matthew J.

    2013-06-01

    cycle GHG and air pollutant emissions. A related study in Toronto on life cycle energy use and GHG emissions for high- and low-density development strategies found a ~60% difference in GHG emissions, largely due to transportation (Norman et al 2006). System dynamics and agent-based models may complement LCA in capturing long-term effects of transportation strategies as they are inherently dynamic (Stepp et al 2009), and can internalize spatially resolved decisions about where to settle and work (Waddell 2002). Transportation planning decisions have both direct and indirect, spatially distributed, often long-term effects on our health and our environment. The accompanying work by Chester et al (2013) provides a well-documented case study that highlights the potential of LCA as a rich source of decision support. References Chester M, Pincetl S, Elizabeth Z, Eisenstein W and Matute J 2013 Infrastructure and automobile shifts: positioning transit to reduce life-cycle environmental impacts for urban sustainability goals Environ. Res. Lett. 8 015041 Chester M V and Horvath A 2009 Environmental assessment of passenger transportation should include infrastructure and supply chains Environ. Res. Lett. 4 024008 Fargione J, Hill J, Tilman D, Polasky S and Hawthorne P 2008 Land clearing and the biofuel carbon debt Science 319 1235-8 Kennedy C, Steinberger J, Gasson B, Hansen Y, Hillman T, Havránek M, Pataki D, Phdungsilp A, Ramaswami A and Mendez G V 2009 Greenhouse gas emissions from global cities Environ. Sci. Technol. 43 7297-302 Kunstler J H 1994 Geography of Nowhere: The Rise and Decline of America's Man-Made Landscape (New York: Free Press) Mashayekh Y, Jaramillo P, Samaras C, Hendrickson C T, Blackhurst M, MacLean H L and Matthews H S 2012 Potentials for sustainable transportation in cities to alleviate climate change impacts Environ. Sci. Technol. 46 2529-37 Mutel C L and Hellweg S 2009 Regionalized life cycle assessment: computational methodology and application to