Science.gov

Sample records for core limiting conditions

  1. 20 CFR 661.310 - Under what limited conditions may a Local Board directly be a provider of core services...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false Under what limited conditions may a Local Board directly be a provider of core services, intensive services, or training services, or act as a One-Stop Operator? 661.310 Section 661.310 Employees' Benefits EMPLOYMENT AND TRAINING...

  2. 20 CFR 661.310 - Under what limited conditions may a Local Board directly be a provider of core services...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Board directly be a provider of core services, intensive services, or training services, or act as a One... Board directly be a provider of core services, intensive services, or training services, or act as a One-Stop Operator? (a) A Local Board may not directly provide core services, or intensive services, or...

  3. Properties of iron under core conditions

    NASA Astrophysics Data System (ADS)

    Brown, J. M.

    2003-04-01

    Underlying an understanding of the geodynamo and evolution of the core is knowledge of the physical and chemical properties of iron and iron mixtures under high pressure and temperature conditions. Key properties include the viscosity of the fluid outer core, thermal diffusivity, equations-of-state, elastic properties of solid phases, and phase equilibria for iron and iron-dominated mixtures. As is expected for work that continues to tax technological and intellectual limits, controversy has followed both experimental and theoretical progress in this field. However, estimates for the melting temperature of the inner core show convergence and the equation-of-state for iron as determined in independent experiments and theories are in remarkable accord. Furthermore, although the structure and elastic properties of the solid inner-core phase remains uncertain, theoretical and experimental underpinnings are better understood and substantial progress is likely in the near future. This talk will focus on an identification of properties that are reasonably well known and those that merit further detailed study. In particular, both theoretical and experimental (static and shock wave) determinations of the density of iron under extreme conditions are in agreement at the 1% or better level. The behavior of the Gruneisen parameter (which determines the geothermal gradient and controls much of the outer core heat flux) is constrained by experiment and theory under core conditions for both solid and liquid phases. Recent experiments and theory are suggestive of structure or structures other than the high-pressure hexagonal close-packed (HCP) phase. Various theories and experiments for the elasticity of HCP iron remain in poor accord. Uncontroversial constraints on core chemistry will likely never be possible. However, reasonable bounds are possible on the basis of seismic profiles, geochemical arguments, and determinations of sound velocities and densities at high pressure and

  4. Limits on the Core Mass of Jupiter

    NASA Astrophysics Data System (ADS)

    Stevenson, D. J.

    2015-12-01

    The core is here defined as the central concentration of elements heavier than hydrogen and helium (it need not be solid and it need not be purely heavy elements and it will not have a sharp boundary). Its determination is a major goal of the Juno mission (2016-17) and it will be difficult to determine because it is expected to be only a few percent of the total mass. It has long been known that there is no prospect of determining the nature of this core (e.g., its density) from gravity measurements, even though the mass can be estimated. By consideration of simple models that are nonetheless faithful to the essential physics, it is further shown that should the core be contaminated with light elements (hydrogen and helium) then the gravity data can tell us the core mass as defined (with some caveats about the fuzziness of its boundary) but not the total mass within some small radius (which could include any light elements mixed in). This is both good and bad news: Good in that the core is thought to be diagnostic of the conditions under which the planet formed but bad in that the admixture also tells us more about both formation process and core erosion. Further, a linear perturbation theory has been developed that provides an easy approximate way of determining how errors in the equation of state (EOS) propagate into errors in the estimated core mass or envelope enrichment in heavies in models that nonetheless satisfy all observables. This theory does not require detailed models of the planet but provides an integral mapping from changes in the EOS into approximate changes in radius at fixed mass, and low degree gravity (or moment of inertia, MOI). This procedure also shows that there exist perturbations that leave the radius, mass and MOI unchanged but cause a change in J2, though in practice the non-uniqueness of structure by this consideration (~0.2% or less in MOI for example) is less than the non-uniqueness arising from likely EOS uncertainties (~1% in total

  5. Fault current limiter with shield and adjacent cores

    SciTech Connect

    Darmann, Francis Anthony; Moriconi, Franco; Hodge, Eoin Patrick

    2013-10-22

    In a fault current limiter (FCL) of a saturated core type having at least one coil wound around a high permeability material, a method of suppressing the time derivative of the fault current at the zero current point includes the following step: utilizing an electromagnetic screen or shield around the AC coil to suppress the time derivative current levels during zero current conditions.

  6. RIA Limits Based On Commercial PWR Core Response To RIA

    SciTech Connect

    Beard, Charles L.; Mitchell, David B.; Slagle, William H.

    2006-07-01

    Reactivity insertion accident (RIA) limits have been under intense review by regulators since 1993 with respect to what should be the proper limit as a function of burnup. Some national regulators have imposed new lower limits while in the United States the limits are still under review. The data being evaluated with respect to RIA limits come from specialized test reactors. However, the use of test reactor data needs to be balanced against the response of a commercial PWR core in setting reasonable limits to insure the health and safety of the public without unnecessary restrictions on core design and operation. The energy deposition limits for a RIA were set in the 1970's based on testing in CDC (SPERT), TREAT, PBF and NSRR test reactors. The US limits given in radially averaged enthalpy are 170 cal/gm for fuel cladding failure and 280 cal/gm for coolability. Testing conducted in the 1990's in the CABRI, NSRR and IGR test reactors have demonstrated that the cladding failure threshold is reduced with burnup, with the primary impact due to hydrogen pickup for in-reactor corrosion. Based on a review of this data very low enthalpy limits have been proposed. In reviewing proposed limits from RIL-0401(1) it was observed that much of the data used to anchor the low allowable energy deposition levels was from recent NSRR tests which do not represent commercial PWR reactor conditions. The particular characteristics of the NSRR test compared to commercial PWR reactor characteristics are: - Short pulse width: 4.5 ms vs > 8 ms; - Low temperature conditions: < 100 deg. F vs 532 deg. F. - Low pressure environment: atmospheric vs {approx} 2200 psi. A review of the historical RIA database indicates that some of the key NSRR data used to support the RIL was atypical compared to the overall RIA database. Based on this detailed review of the RIA database and the response of commercial PWR core, the following view points are proposed. - The Failure limit should reflect local fuel

  7. Critical conditions for core-collapse supernovae.

    PubMed

    Keshet, Uri; Balberg, Shmuel

    2012-06-22

    The explosion of a core-collapse supernova can be approximated by the breakdown of steady-state solutions for accretion onto a proto-neutron star (PNS). We analytically show that as the neutrino luminosity exceeds a critical value L(c), the neutrinosphere pressure exceeds the hydrostatic limit even for an optimal shock radius R. This yields L(c) [proportionally] M(2)T(2) (with logarithmic corrections) and R [proportionally] M/T, in agreement with numerical results, where M and T are the PNS mass and neutrino temperature, respectively. The near-critical flow can be approximated as a ballistic shell on top of an isothermal layer. PMID:23004581

  8. Bounds on metal-silicate equilibration conditions during core formation

    NASA Astrophysics Data System (ADS)

    Deguen, Renaud

    2016-04-01

    Much of the Earth was built by high-energy impacts of planetesimals and embryos, many of these impactors already differentiated, with metallic cores of their own. Geochemical data provide critical information on the timing of accretion and the prevailing physical conditions. The comparison between the inferred core/mantle partitioning with the experimentally determined partitioning behavior of a number of siderophile elements can be used to place constraints on the conditions (pressure, temperature, oxygen fugacity) under which the metal and silicates equilibrated before separating to form the core and mantle. The main limitation of this approach is that the interpretation of the geochemical data in terms of equilibration conditions is non-unique. This is an ill-posed inverse problem, and the inversion is usually carried out by making a number of assumptions to close the problem and make it (artificially) well-posed. Here, we take another approach and derive exact bounds on the distribution of conditions of equilibration during Earth's formation and core mantle differentiation.

  9. Double storey three phase saturated cores fault current limiter

    NASA Astrophysics Data System (ADS)

    Wolfus, Y.; Nikulshin, Y.; Friedman, A.; Yeshurun, Y.

    2014-05-01

    A novel saturated-cores Fault-Current-Limiter (FCL) configuration is described. This FCL is based on two parallel planes of iron rectangular cores, on which three-phase coils are mounted and connected in series to the grid. Two DC coils are mounted in between the planes on perpendicular core limbs connecting the two AC planes. The DC coils are set to magnetically saturate the AC cores. The transition to three-dimensional, double-storey design enables handling three-phase symmetrical faults while offering better decoupling between the AC and DC circuits. At the same time, it shortens the AC limb lengths and enables deeper magnetic saturation levels in comparison to other saturated cores FCL designs. Hence, this FCL configuration exhibits lower insertion impedance and higher ratio of fault to nominal state impedance in comparison with other designs.

  10. 42 CFR 418.64 - Condition of participation: Core services.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 3 2010-10-01 2010-10-01 false Condition of participation: Core services. 418.64 Section 418.64 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM HOSPICE CARE Conditions of Participation: Patient Care Core Services § 418.64 Condition of participation:...

  11. Limited Conditions of Operations Tracking Program

    Energy Science and Technology Software Center (ESTSC)

    1999-12-17

    The Lco tracking program is a computer based solution for tracking time limited action items for Limited Conditions of Operation (LCO) for nuclear and industrial processes. This use is not limited to any process except those not requiring specific action steps and times. The visual and audible assistance the LCO Tracking Program provides significantly reduces the chance of missing crucial actions required for safe operation of any facility in time of limited operations. The LCOmore » Tracking Program maintains all applicable action steps and times for each limited condition for the facility in its data base. The LCO Tracking Program is used to enter that condition by number, and the data base provides the applicble action steps and starts tracking their times based on the time the LCO was entered. The LCO display graphically displays, by colored bar charts, the time expired/time remaining of each specific action item. At 60% time expired, the bar chart turns yellow to caution personnel and then turns red at 90% time expired. Then an audible alarm is sounded at 95% as a warning, to finish or accomplish the required actions to satisfy the requirements. These warning and alarm limits are modifiable by the user and can be set at different values for each action. The display file is dynamic in function, checking every minute, and responds in real time to changes to the LCO Tracking Form file, providing the visual and audible warnings as to the status of the action steps chosen for display. The LCO Tracking Program efficiently tracks action times in minutes or days, up to 2 years. All current LCO''s are easily documentated using the LCO Tracking Form file with ease of printing and disposition. The Lco Tracking Program is designed as a user friendly program with navigational buttons to simplify use.« less

  12. Petrophysical core characterization at supercritical geothermal conditions

    NASA Astrophysics Data System (ADS)

    Kummerow, Juliane; Raab, Siegfried

    2015-04-01

    There is a growing scientific interest in the exploitation of supercritical geothermal reservoirs to increase the efficiency of geothermal power plants. The utilisation of geothermal energy requires in any case the detailed knowledge of the reservoir. In reservoir engineering, the characterisation of the geothermal system by electrical resistivity tomography (ERT) is a common geophysical exploration and monitoring strategy. For a realistic interpretation of the field measurements it is necessary to know both, the physical properties of the rock and those of the interacting fluid at defined temperature and pressure conditions. While there have been made great effort in determine the physical and chemical properties of water above its critical point (Tcritical = 374.21° C and pcritical = 221.2 bar), the influence of fluid-rock interactions on petrophysical properties in supercritical aqueous systems is nearly unknown. At supercritical conditions the viscosity of the fluid is low, which enhances the mass transfer and diffusion-controlled chemical reactions. This may have considerable effects on the porosity and hydraulic properties of a rock. To investigate high-enthalpy fluid-rock systems, in the framework of the EU-funded project IMAGE we have built a new percolation set-up, which allows for the measurement of electrical resistivity and permeability of rock samples at controlled supercritical conditions of aqueous fluids (pore pressure = 400 bar and a temperature = 400° C). First results will be presented.

  13. Thermal and electrical conductivity of iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2012-05-17

    The Earth acts as a gigantic heat engine driven by the decay of radiogenic isotopes and slow cooling, which gives rise to plate tectonics, volcanoes and mountain building. Another key product is the geomagnetic field, generated in the liquid iron core by a dynamo running on heat released by cooling and freezing (as the solid inner core grows), and on chemical convection (due to light elements expelled from the liquid on freezing). The power supplied to the geodynamo, measured by the heat flux across the core-mantle boundary (CMB), places constraints on Earth's evolution. Estimates of CMB heat flux depend on properties of iron mixtures under the extreme pressure and temperature conditions in the core, most critically on the thermal and electrical conductivities. These quantities remain poorly known because of inherent experimental and theoretical difficulties. Here we use density functional theory to compute these conductivities in liquid iron mixtures at core conditions from first principles--unlike previous estimates, which relied on extrapolations. The mixtures of iron, oxygen, sulphur and silicon are taken from earlier work and fit the seismologically determined core density and inner-core boundary density jump. We find both conductivities to be two to three times higher than estimates in current use. The changes are so large that core thermal histories and power requirements need to be reassessed. New estimates indicate that the adiabatic heat flux is 15 to 16 terawatts at the CMB, higher than present estimates of CMB heat flux based on mantle convection; the top of the core must be thermally stratified and any convection in the upper core must be driven by chemical convection against the adverse thermal buoyancy or lateral variations in CMB heat flow. Power for the geodynamo is greatly restricted, and future models of mantle evolution will need to incorporate a high CMB heat flux and explain the recent formation of the inner core. PMID:22495307

  14. Core stability training: applications to sports conditioning programs.

    PubMed

    Willardson, Jeffrey M

    2007-08-01

    In recent years, fitness practitioners have increasingly recommended core stability exercises in sports conditioning programs. Greater core stability may benefit sports performance by providing a foundation for greater force production in the upper and lower extremities. Traditional resistance exercises have been modified to emphasize core stability. Such modifications have included performing exercises on unstable rather than stable surfaces, performing exercises while standing rather than seated, performing exercises with free weights rather than machines, and performing exercises unilaterally rather than bilaterally. Despite the popularity of core stability training, relatively little scientific research has been conducted to demonstrate the benefits for healthy athletes. Therefore, the purpose of this review was to critically examine core stability training and other issues related to this topic to determine useful applications for sports conditioning programs. Based on the current literature, prescription of core stability exercises should vary based on the phase of training and the health status of the athlete. During preseason and in-season mesocycles, free weight exercises performed while standing on a stable surface are recommended for increases in core strength and power. Free weight exercises performed in this manner are specific to the core stability requirements of sports-related skills due to moderate levels of instability and high levels of force production. Conversely, during postseason and off-season mesocycles, Swiss ball exercises involving isometric muscle actions, small loads, and long tension times are recommended for increases in core endurance. Furthermore, balance board and stability disc exercises, performed in conjunction with plyometric exercises, are recommended to improve proprioceptive and reactive capabilities, which may reduce the likelihood of lower extremity injuries. PMID:17685697

  15. 42 CFR 418.64 - Condition of participation: Core services.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 3 2014-10-01 2014-10-01 false Condition of participation: Core services. 418.64 Section 418.64 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... must be available to the patient and family to assist the patient and family in minimizing the...

  16. 42 CFR 418.64 - Condition of participation: Core services.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 3 2012-10-01 2012-10-01 false Condition of participation: Core services. 418.64 Section 418.64 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... must be available to the patient and family to assist the patient and family in minimizing the...

  17. 42 CFR 418.64 - Condition of participation: Core services.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 3 2011-10-01 2011-10-01 false Condition of participation: Core services. 418.64 Section 418.64 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... must be available to the patient and family to assist the patient and family in minimizing the...

  18. 42 CFR 418.64 - Condition of participation: Core services.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 3 2013-10-01 2013-10-01 false Condition of participation: Core services. 418.64 Section 418.64 Public Health CENTERS FOR MEDICARE & MEDICAID SERVICES, DEPARTMENT OF HEALTH AND HUMAN... must be available to the patient and family to assist the patient and family in minimizing the...

  19. Performance analysis of saturated iron core superconducting fault current limiter using Jiles-Atherton hysteresis model

    NASA Astrophysics Data System (ADS)

    Sarkar, D.; Roy, D.; Choudhury, A. B.; Yamada, S.

    2015-09-01

    In this paper study of the Saturated Iron Core Superconducting Fault Current Limiter (SISFCL) has been carried out. Since in an SISFCL, the iron core plays a key role in distributing the magnetic flux, the hysteresis property of the core material has been introduced in a mathematical model to get a more accurate result. In this paper the Jiles-Atherton hysteresis model has been used for modeling the core. The equations are solved through numerical method and performances of SISFCL are analyzed for both normal and fault conditions. On further analysis it is observed that for suppression of higher value of fault current a high voltage develops across the DC source. Hence there is a chance of the DC source being damaged by the rise in voltage under fault condition. In order to protect the DC source, a shorted ring is introduced in the SISFCL circuit and its effects have been analyzed. It is noticed that the shorted ring has successfully reduced the voltage across the DC coil during fault condition while the performance of the limiter remains the same.

  20. Condition for Convective Cores in Main Sequence Stars

    NASA Astrophysics Data System (ADS)

    Monteiro, M. J. P. F. G.

    1990-09-01

    The aim of this work is to find the condition for the existence of convective cores in homogenous main sequence stars where the opacity per unit mass is $k=k_0ρα T-β and the energy generation rate per unit mass is ɛ=ɛ0ρ Tη (ρ and T being the density and the temperature, respectively). Numerical models of stars with different values of α, β and η are constructed and the condition for the existence of a convective core in terms of the relation between α, β and η determined. Forty points η=η(α,β) are determined for αin[0,2] and βin[0,4] and the condition is found to be η = - 3.3294; α + 2.0243; β + 1.8393

  1. Amyloid Fibrillation of Insulin under Water-Limited Conditions

    PubMed Central

    Choi, Tae Su; Lee, Jong Wha; Jin, Kyeong Sik; Kim, Hugh I.

    2014-01-01

    Amyloid fibrillation in water-organic mixtures has been widely studied to understand the effect of protein-solvent interactions on the fibrillation process. In this study, we monitored insulin fibrillation in formamide and its methyl derivatives (formamide, N-methyl formamide, N,N-dimethyl formamide) in the presence and absence of water. These model solvent systems mimic the cellular environment by providing denaturing conditions and a hydrophobic environment with limited water content. Thioflavin T (ThT) assay revealed that binary mixtures of water with formamide and its methyl derivatives enhanced fibrillation rates and β-sheet abundance, whereas organic solvents suppressed insulin fibrillation. We utilized solution small-angle x-ray scattering (SAXS) and differential scanning calorimetry (DSC) to investigate the correlation between protein-solvent interactions and insulin fibrillation. SAXS experiments combined with simulated annealing of the protein indicated that the degree of denaturation of the hydrophobic core region at residues B11–B17 determines the fibrillation rate. In addition, DSC experiments suggested a crucial role of hydrophobic interactions in the fibrillation process. These results imply that an environment with limited water, which imitates a lipid membrane system, accelerates protein denaturation and the formation of intermolecular hydrophobic interactions during amyloid fibrillation. PMID:25418175

  2. Equilibrium iron isotope fractionation at core-mantle boundary conditions.

    PubMed

    Polyakov, Veniamin B

    2009-02-13

    The equilibrium iron isotope fractionation between lower mantle minerals and metallic iron at core-mantle boundary conditions can be evaluated from the high-pressure 57Fe partial vibrational density of states determined by synchrotron inelastic nuclear resonant x-ray scattering spectroscopy using a diamond anvil. Ferropericlase [(Mg,Fe)O] and (Fe,Mg)SiO3- post-perovskite are enriched in heavy iron isotopes relative to metallic iron at ultrahigh pressures, as opposed to the equilibrium iron isotope fractionation between these compounds at low pressure. The enrichment of Earth and Moon basalts in heavy iron isotopes relative to those from Mars and asteroid Vesta can be explained by the equilibrium iron isotope fractionation during the segregation of Earth's core and the assumption that Earth was already differentiated before the Moon-forming "giant impact." PMID:19213913

  3. Spectroscopic modeling and analysis of plasma conditions in implosion cores

    NASA Astrophysics Data System (ADS)

    Golovkin, Igor E.

    implosions are extracted. We show that opacity effects must be taken into account in order to interpret the spectra and extract accurate plasma conditions. Finally, we determine the dynamic plasma gradients on ICF implosion cores driven by the GECCO XII laser system. The determination of the dynamics gradients in the imploding plasma core found here can serve as a critical test of the current model of the hydrodynamic behavior of high energy density implosions.

  4. Comparison of core sampling and visual inspection for assessment of concrete sewer pipe condition.

    PubMed

    Stanić, N; de Haan, C; Tirion, M; Langeveld, J G; Clemens, F H L R

    2013-01-01

    Sewer systems are costly to construct and even more costly to replace, requiring proper asset management. Sewer asset management relies to a large extent on available information. In sewer systems where pipe corrosion is the dominant failure mechanism, visual inspection by closed circuit television (CCTV) and core sampling are among the methods mostly applied to assess sewer pipe condition. This paper compares visual inspection and drill core analysis in order to enhance further understanding of the limitations and potentials of both methods. Both methods have been applied on a selected sewer reach in the city of The Hague, which was reportedly subject to pipe corrosion. Results show that both methods, visual inspection and core sampling, are associated with large uncertainties and that there is no obvious correlation between results of visual inspection and results of drill core analysis. PMID:23752377

  5. An Integral Condition for Core-Collapse Supernova Explosions

    NASA Astrophysics Data System (ADS)

    Murphy, Jeremiah Wayne; Dolence, Joshua C.

    2016-01-01

    We derive an integral condition for core-collapse supernova explosions and use it to construct a new diagnostic of explodability. The fundamental challenge in core-collapse supernova theory is to explain how a stalled accretion shock revives to explode a star. In this manuscript, we assume that shock revival is initiated by the delayed-neutrino mechanism and derive an integral condition for shock expansion, vs > 0. Assuming that vs > 0 corresponds to explosion, we recast this integral condition as a dimensionless condition for explosion, Ψ > 0. Using 1D simulations, we confirm that Ψ = 0 during the stalled phase and Ψ > 0 during explosion. Having validated the integral condition, we use it to derive a useful explosion diagnostic. First, for a given set of parameters, we find the family of solutions to the steady-state equations, parameterized by shock radius Rs, yielding Ψ(Rs). For any particular solution, Ψ(Rs) may be negative, zero, or positive, and, since Ψ ∝ vs, this corresponds to a solution with a receding, stationary, or expanding shock, respectively. Within this family, there is always a solution with a minimum Ψ, Ψmin. When Ψmin < 0, there always exists a stalled accretion shock solution, but when Ψmin > 0, all solutions have vs > 0. Therefore, Ψmin = 0 defines a critical hypersurface for explosion, and we show that the critical neutrino luminosity curve proposed by Burrows & Goshy 1993 is a projection of this more general critical condition. Finally, we propose and verify with 1D simulations that Ψmin is a reliable and accurate explosion diagnostic.

  6. Probing iron at Super-Earth core conditions

    SciTech Connect

    Amadou, N.; Brambrink, E.; Vinci, T.; Benuzzi-Mounaix, A.; Huser, G.; Brygoo, S.; Morard, G.; Guyot, F.; Resseguier, T. de; Mazevet, S.; Miyanishi, K.; Ozaki, N.; Kodama, R.; Henry, O.; Raffestin, D.; Boehly, T.; and others

    2015-02-15

    In this paper, we report on the quasi-isentropic compression of an iron sample using ramp shaped laser irradiation. This technique allows us to quasi-isentropically compress iron up to 700 GPa and 8500 K. To our knowledge, these data are the highest pressures reached on iron in off-Hugoniot conditions and the closest to the thermodynamic states thought to exist in Earth-like planetary cores. The experiment was performed on the Ligne d'Intégration laser facility at CESTA, Bordeaux, France.

  7. Conductivity and Correlations in Fe at Earth Core Conditions

    NASA Astrophysics Data System (ADS)

    Cohen, R. E.; Zhang, Peng; Haule, Kristjan

    We have computed electrical conductivity in iron at Earth core conditions self-consistently within many-body theory using DFT/DMFT. We find that electron correlations are important even in the generation of Earth's magnetic field. Earth's magnetic field was believed to arise from thermal convection of molten iron alloy in Earth's outer core, but density functional theory (DFT) calculations suggested that the conductivity of iron is too high to support thermal convection, so that new geodynamo models were being developed. The DFT computations for resistivity were based on the scattering of electrons off of atomic vibrations, or electron-phonon (e-p) scattering. We applied self-consistent density functional theory plus dynamical mean-field theory (DFT+DMFT) to iron and found that at high temperatures electron-electron (e-e) scattering is comparable to the e-p scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core, consistent with the conventional thermal geodynamo [Peng, Cohen, and Haule, Nature 517, 605, 2015]. How electron correlations change with pressure, and how this affects material properties, will be discussed. This work is supported by the US National Science Foundation and the ERC Advanced grant ToMCaT.

  8. Limitations in Life Participation and Independence Due to Secondary Conditions

    ERIC Educational Resources Information Center

    Koritsas, Stella; Iacono, Teresa

    2009-01-01

    The effects of secondary conditions across adults with autism, Down syndrome, and cerebral palsy were explored in terms of overall limitation in life participation and independence, changes over time, and the degree and nature of limitation in specific secondary conditions. Information was obtained for 35 adults with autism, 49 with Down syndrome,…

  9. Partitioning of Sulfur and Platinum at Core Formation Conditions.

    NASA Astrophysics Data System (ADS)

    Suer, T. A.; Siebert, J.; Fiquet, G.; Remusat, L.

    2015-12-01

    Measuring the partitioning behavior of highly siderophile elements (HSE) at high pressures and temperatures is important for understanding the mantle's elemental reservoir and the core mantle differentiation process. Low solubility of HSEs in silicate melts and the small size of samples obtained from diamond anvil cell (DAC) experiments have prevented the experimental study of the partitioning of these elements at realistic deep magma ocean conditions. In this study, we present results for metal-silicate partitioning experiments of sulfur and platinum conducted at pressures between 45 and 80 GPa and at temperatures from 3500 to 4200 K. With the nanoSIMS as our main tool for measuring trace element concentrations, we have developed a protocol for studying the partitioning behavior of these elements from samples that underwent equilibration at high pressure and temperatures in a Laser-Heated DAC. The nanoSIMS has the spatial resolution and the required sensitivity to measure the low concentration of some HSEs in the quenched silicate glass. The results of this study will help to refine current core-mantle differentiation models. Furthermore they add constraints to the contribution of the late veneer to the mantle's elemental abundances.

  10. Computational modeling for hexcan failure under core distruptive accidental conditions

    SciTech Connect

    Sawada, T.; Ninokata, H.; Shimizu, A.

    1995-09-01

    This paper describes the development of computational modeling for hexcan wall failures under core disruptive accident conditions of fast breeder reactors. A series of out-of-pile experiments named SIMBATH has been analyzed by using the SIMMER-II code. The SIMBATH experiments were performed at KfK in Germany. The experiments used a thermite mixture to simulate fuel. The test geometry of SIMBATH ranged from single pin to 37-pin bundles. In this study, phenomena of hexcan wall failure found in a SIMBATH test were analyzed by SIMMER-II. Although the original model of SIMMER-II did not calculate any hexcan failure, several simple modifications made it possible to reproduce the hexcan wall melt-through observed in the experiment. In this paper the modifications and their significance are discussed for further modeling improvements.

  11. Limited dissemination of the wastewater treatment plant core resistome

    PubMed Central

    Munck, Christian; Albertsen, Mads; Telke, Amar; Ellabaan, Mostafa; Nielsen, Per Halkjær; Sommer, Morten O. A.

    2015-01-01

    Horizontal gene transfer is a major contributor to the evolution of bacterial genomes and can facilitate the dissemination of antibiotic resistance genes between environmental reservoirs and potential pathogens. Wastewater treatment plants (WWTPs) are believed to play a central role in the dissemination of antibiotic resistance genes. However, the contribution of the dominant members of the WWTP resistome to resistance in human pathogens remains poorly understood. Here we use a combination of metagenomic functional selections and comprehensive metagenomic sequencing to uncover the dominant genes of the WWTP resistome. We find that this core resistome is unique to the WWTP environment, with <10% of the resistance genes found outside the WWTP environment. Our data highlight that, despite an abundance of functional resistance genes within WWTPs, only few genes are found in other environments, suggesting that the overall dissemination of the WWTP resistome is comparable to that of the soil resistome. PMID:26419330

  12. Limited dissemination of the wastewater treatment plant core resistome.

    PubMed

    Munck, Christian; Albertsen, Mads; Telke, Amar; Ellabaan, Mostafa; Nielsen, Per Halkjær; Sommer, Morten O A

    2015-01-01

    Horizontal gene transfer is a major contributor to the evolution of bacterial genomes and can facilitate the dissemination of antibiotic resistance genes between environmental reservoirs and potential pathogens. Wastewater treatment plants (WWTPs) are believed to play a central role in the dissemination of antibiotic resistance genes. However, the contribution of the dominant members of the WWTP resistome to resistance in human pathogens remains poorly understood. Here we use a combination of metagenomic functional selections and comprehensive metagenomic sequencing to uncover the dominant genes of the WWTP resistome. We find that this core resistome is unique to the WWTP environment, with <10% of the resistance genes found outside the WWTP environment. Our data highlight that, despite an abundance of functional resistance genes within WWTPs, only few genes are found in other environments, suggesting that the overall dissemination of the WWTP resistome is comparable to that of the soil resistome. PMID:26419330

  13. Saturation of electrical resistivity of solid iron at Earth's core conditions.

    PubMed

    Pozzo, Monica; Alfè, Dario

    2016-01-01

    We report on the temperature dependence of the electrical resistivity of solid iron at high pressure, up to and including conditions likely to be found at the centre of the Earth. We have extended some of the calculations of the resistivities of pure solid iron we recently performed at Earth's core conditions (Pozzo et al. in Earth Planet Sci Lett 393:159-164, 2014) to lower temperature. We show that at low temperature the resistivity increases linearly with temperature, and saturates at high temperature. This saturation effect is well known as the Mott-Ioffe-Regel limit in metals, but has been largely ignored to estimate the resistivity of iron at Earth's core conditions. Recent experiments (Gomi et al. in Phys Earth Planet Int 224:88-103, 2013) coupled new high pressure data and saturation to predict the resitivity of iron and iron alloys at Earth's core conditions, and reported values up to three times lower than previous estimates, confirming recent first principles calculations (de Koker et al. in Proc Natl Acad Sci 109:4070-4073, 2012; Pozzo et al. in Nature 485:355-358, 2012, Phys Rev B 87:014110-10, 2013, Earth Planet Sci Lett 393:159-164, 2014; Davies et al. in Nat Geosci 8:678-685, 2015). The present results support the saturation effect idea. PMID:27026948

  14. Fluorescent-Core Microcapillaries: Detection Limits for Biosensing Applications

    NASA Astrophysics Data System (ADS)

    McFarlane, Shalon A.

    This work develops a refractive-index sensor based on whispering gallery modes (WGMs) in glass microcapillaries. The capillary channel is coated with a layer of fluorescent silicon quantum dots (QDs), which provides a fluorescence source that also supports the WGMs. When different fluids are pumped into the channel, the fluorescence spectrum responds as the resonances shift to different frequencies. A study of the WGM spectral shift analysis techniques improved the detection limits to ˜10-4 refractive index units, and permitted the development of sensorgram-type analyses in which the channel fluid is probed continuously in time. The feasibility of the device as a microfluidic biosensor was demonstrated by first functionalizing the silica surface and then detecting the binding of biotin and streptavidin to the capillary channel. These structures could be attractive as microfluidic biological sensors, since they are easy to fabricate, mechanically robust, and relatively inexpensive compared to other technologies.

  15. Determination of core design thermal safety limits for a two-loop pressurized water reactor

    SciTech Connect

    Kostadinov, V.

    1996-04-01

    Results are given of independent research of core thermal design limits for the Nuklearna Elektrarna Krsko (NEK) nuclear power plant; procedures for two-loop pressurized water reactor plant core design safety limit calculation are used. Emphasis is placed on researching the vessel exit boiling and the hot-channel exit quality limits and their impact on the maximum available design safety operating range and thermal operating margin of the NEK reactor core. For this purpose, the LIMITS computer code is developed. Based on the modified, well-tried COBRA-IV-I computer code, the departure of nuclear boiling ratio core safety limits are calculated. The original results complement well those of the NEK Final Safety Analysis Report. The procedures and the methods for determining the reactor core design thermal limits are successfully proven despite the unavailability of proprietary data, different models, and computer codes. In addition to the acquired capability of in-house independent checking of the vendor`s results, the bases are set for further independent analyses of the limiting safety system settings for the NEK core.

  16. Core knowledge and its limits: The domain of food

    PubMed Central

    Shutts, Kristin; Condry, Kirsten F.; Santos, Laurie R.; Spelke, Elizabeth S.

    2009-01-01

    Adults, preschool children, and nonhuman primates detect and categorize food objects according to substance information, conveyed primarily by color and texture. In contrast, they perceive and categorize artifacts primarily by shape and rigidity. The present experiments investigated the origins of this distinction. Using a looking time procedure, Experiment 1 extended previous findings that rhesus macaques (Macaca mulatta) generalize learning about novel food objects by color over changes in shape. Six additional experiments then investigated whether human infants show the same signature patterns of perception and generalization. Nine-month-old infants failed to detect food objects in accord with their intrinsic properties, in contrast to rhesus monkeys tested in previous research with identical displays. Eight-month-old infants did not privilege substance information over other features when categorizing foods, even though they detected and remembered this information. Moreover, infants showed the same property generalization patterns when presented with foods and tools. The category-specific patterns of perception and categorization shown by human adults, children, and adult monkeys therefore were not found in human infants, providing evidence for limits to infants’ domains of knowledge. PMID:19409538

  17. Motions and Initial Conditions in Star-Forming Dense Cores

    NASA Technical Reports Server (NTRS)

    Myers, Philip C.

    2004-01-01

    The main focus was the study of star-forming regions through high spectral- and spatial resolution observations of mm-wavelength lines, and through models of the observations. The main accomplishments were a) demonstration that more than 15 starless cores show substantial evidence of extended inward motion at about half the sound speed; b) observations of infall asymmetry in several cores, in lines of N2H(+) and DCO(+), low- depletion tracers of the "inner core"; c) observation of "infall asymmetry" of spectral lines over approx. 0.5 pc in the NGC1333 cluster-forming region; d) observations indicating that cores are nearly at rest with respect to their envelopes; and e) development of analytic, power-series solutions to the equations of motions for condensing 1-D systems (layers, cylinders and spheres).

  18. Is iron at the Earth's core conditions hcp-structured?

    SciTech Connect

    Dubrovinsky, L; Dubrovinskaia, N; Prakapenka, V

    2012-02-07

    Iron is the main component of the Earth's core and its structure and properties are important for interpretation of geophysical observations and modeling dynamics of the core. We argue that the diffraction lines in the high temperature high pressure X-ray diffraction pattern, presented by Tateno et al., 2010 and interpreted as those of solely hot hcp-Fe, correspond indeed to the insufficiently heated part of the sample. We show that observed diffraction spots are either due to bcc-Fe or carbides.

  19. Trends in activity-limiting chronic conditions among children.

    PubMed Central

    Newacheck, P W; Budetti, P P; Halfon, N

    1986-01-01

    Data from the National Health Interview Survey indicate that the prevalence of activity-limiting chronic conditions among children under age 17 years doubled between 1960 and 1981, from 1.8 to 3.8 per cent. Approximately 40 per cent of the overall rise in prevalence occurred before 1970. Most of the increase in prevalence during this early period can be attributed to changes in questionnaire design and aging of the child population following the "baby boom" years. The factors responsible for increases in reported cases of activity limitation following 1970 are more difficult to specify and evaluate. During this later period, the increase in prevalence was restricted to less severe levels of limitations. While prevalence levels rose for a variety of conditions during this period, respiratory conditions and mental and nervous system disorders demonstrated the largest changes. It appears that much of the increase in reported cases of activity limitations during the 1970s can be attributed to shifting perceptions on the part of parents, educators, and physicians. PMID:2936257

  20. Flammability Limits of Gases Under Low Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Strehlow, R. A.

    1985-01-01

    The purpose of this combustion science investigation is to determine the effect of zero, fractional, and super gravity on the flammability limits of a premixed methane air flame in a standard 51 mm diameter flammability tube and to determine, if possible, the fluid flow associated with flame passage under zero-g conditions and the density (and hence, temperature) profiles associated with the flame under conditions of incipient extinction. This is accomplished by constructing an appropriate apparatus for placement in NASA's Lewis Research Center Lear Jet facility and flying the prescribed g-trajectories while the experiment is being performed. Data is recorded photographically using the visible light of the flame. The data acquired is: (1) the shape and propagation velocity of the flame under various g-conditions for methane compositions that are inside the flammable limits, and (2) the effect of gravity on the limits. Real time accelerometer readings for the three orthogonal directions are displayed in full view of the cameras and the framing rate of the cameras is used to measure velocities.

  1. 42 CFR 418.70 - Condition of participation: Furnishing of non-core services.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... HEALTH AND HUMAN SERVICES (CONTINUED) MEDICARE PROGRAM HOSPICE CARE Conditions of Participation: Patient Care Non-Core Services § 418.70 Condition of participation: Furnishing of non-core services. A hospice... hospice or under arrangements made by the hospice as specified in § 418.100. These services must...

  2. Core-halo limit and internal dynamics of high intensity beams

    SciTech Connect

    Nghiem, P. A. P.; Valette, M.; Chauvin, N.; Pichoff, N.; Uriot, D.

    2015-08-15

    The dynamics of high-intensity beams largely depends on their internal space charge forces. These forces are responsible of non-linear coupling, emittance growth, and halo generation. They contribute to shape the beam density profile. As a consequence, an analysis of this profile can be a precious indicator capable of revealing the internal dynamics of the beam. This paper recalls the precise core-halo limit determination proposed earlier, then studies its behavior through a wide range of beam profiles, and finally shows its relevance as an indicator of the limit separating the two space charge field regimes of the core and the halo.

  3. Geomagnetic polarity reversals, Earth's core evolution, and conditions for dynamo action in the cores of terrestrial exoplanets

    NASA Astrophysics Data System (ADS)

    Driscoll, Peter E.

    Planetary dynamos are responsible for the generation of large-scale magnetic fields and are ubiquitous in the solar system. Magnetic fields generated by dynamo action in a planetary core offer unique insight into the internal structure, composition, and energetics of the planet. This dissertation consists of two main parts, the first focuses on long period fluctuations in Earth's magnetic field and the second explores conditions for dynamo action in the cores of terrestrial exoplanets. The first part consists of three projects using first-principle numerical magnetohydrodynamic models of the geodynamo to investigate the relationship between two fundamental, but poorly understood, aspects of the geomagnetic field: magnetic polarity reversals and the influence of core evolution. The first project explores the dependence of various dynamo properties on the relative strengths of buoyancy and rotation, and identifies several dynamical regimes whose magnetic field fluctuations over time are consistent with the paleomagnetic field. We find that normal evolution of buoyancy production in the core and planetary rotation rate over 100 Myr produce a negligible change in dynamo polarity reversal rate and field intensity, implying that the observed fluctuations in the geomagnetic reversal rate requires either anomalous core evolution or a rough dynamo regime boundary. The second project models the long time-scale evolution of the Earth's core using time-dependent control parameters, which are constrained by the secular cooling of the core and tidal deceleration. We find that fluctuations in the geodynamo are closely coupled to the evolution of the core, which implies a connection between the long time-scale trends in the seafloor geomagnetic polarity reversal rate and the rate of core evolution over the last 100 Myr. In the third project we investigate the hypothesis that the long period (˜200 Myr) oscillation in paleomagnetic reversal frequency is controlled by the heat flow

  4. Biological conversion of synthesis gas. Limiting conditions/scale-up

    SciTech Connect

    Basu, R.; Klasson, K.T.; Takriff, M.; Clausen, E.C.; Gaddy, J.L.

    1993-09-01

    The purpose of this research is to develop a technically and economically feasible process for biologically producing H(sub 2) from synthesis gas while, at the same time, removing harmful sulfur gas compounds. Six major tasks are being studied: 1. Culture development, where the best cultures are selected and conditions optimized for simultaneous hydrogen production and sulfur gas removal; 2. Mass transfer and kinetic studies in which equations necessary for process design are developed; 3. Bioreactor design studies, where the cultures chosen in Task 1 are utilized in continuous reaction vessels to demonstrate process feasibility and define operating conditions; 4. Evaluation of biological synthetic gas conversion under limiting conditions in preparation for industrial demonstration studies; 5. Process scale-up where laboratory data are scaled to larger-size units in preparation for process demonstration in a pilot-scale unit; and 6. Economic evaluation, where process simulations are used to project process economics and identify high cost areas during sensitivity analyses.

  5. Relationship of core exit-temperature noise to thermal-hydraulic conditions in PWRs

    SciTech Connect

    Sweeney, F.J.; Upadhyaya, B.R.

    1983-01-01

    Core exit thermocouple temperature noise and neutron detector noise measurements were performed at the Loss of Fluid Test Facility (LOFT) reactor and a Westinghouse, 1148 MW(e) PWR to relate temperature noise to core thermal-hydraulic conditions. The noise analysis results show that the RMS of the temperature noise increases linearly with increasing core ..delta..T at LOFT and the commercial PWR. Out-of-core test loop temperature noise has shown similar behavior. The phase angle between core exit temperature noise and in-core or ex-core neutron noise is directly related to the core coolant flow velocity. However, if the thermocouple response time is slow, compared to the coolant transit time between the sensors, velocities inferred from the phase angle are lower than measured coolant flow velocities.

  6. Parametric initial conditions for core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Suwa, Yudai; Müller, Ewald

    2016-08-01

    We investigate a method to construct parametrized progenitor models for core-collapse supernova simulations. Different from all modern core-collapse supernova studies, which rely on progenitor models from stellar evolution calculations, we follow the methodology of Baron & Cooperstein to construct initial models. Choosing parametrized spatial distributions of entropy and electron fraction as a function of mass coordinate and solving the equation of hydrostatic equilibrium, we obtain the initial density structures of our progenitor models. First, we calculate structures with parameters fitting broadly the evolutionary model s11.2 of Woosley et al. (2002). We then demonstrate the reliability of our method by performing general relativistic hydrodynamic simulations in spherical symmetry with the isotropic diffusion source approximation to solve the neutrino transport. Our comprehensive parameter study shows that initial models with a small central entropy (≲0.4 kB nucleon-1) can explode even in spherically symmetric simulations. Models with a large entropy (≳6 kB nucleon-1) in the Si/O layer have a rather large explosion energy (˜4 × 1050 erg) at the end of the simulations, which is still rapidly increasing.

  7. Parametric initial conditions for core-collapse supernova simulations

    NASA Astrophysics Data System (ADS)

    Suwa, Yudai; Müller, Ewald

    2016-08-01

    We investigate a method to construct parametrized progenitor models for core-collapse supernova simulations. Different from all modern core-collapse supernova studies, which rely on progenitor models from stellar evolution calculations, we follow the methodology of Baron & Cooperstein (1990) to construct initial models. Choosing parametrized spatial distributions of entropy and electron fraction as a function of mass coordinate and solving the equation of hydrostatic equilibrium, we obtain the initial density structures of our progenitor models. First, we calculate structures with parameters fitting broadly the evolutionary model s11.2 of Woosley et al. (2002). We then demonstrate the reliability of our method by performing general relativistic hydrodynamic simulations in spherical symmetry with the isotropic diffusion source approximation to solve the neutrino transport. Our comprehensive parameter study shows that initial models with a small central entropy ($\\lesssim 0.4\\,k_B$ nucleon$^{-1}$) can explode even in spherically symmetric simulations. Models with a large entropy ($\\gtrsim 6\\,k_B$ nucleon$^{-1}$) in the Si/O layer have a rather large explosion energy ($\\sim 4\\times 10^{50}$ erg) at the end of the simulations, which is still rapidly increasing.

  8. Computational Study on the Steady-state Impedance of Saturated-core Superconducting Fault Current Limiter

    NASA Astrophysics Data System (ADS)

    Zhang, C.; Tang, Y.; Liang, S.; Ren, L.; Wang, Z.; Xu, Y.

    This paper presents the electromagnetic analysis of a high voltage saturated-core superconducting fault current limiter (SCSFCL). The numerical analyses of a three-dimensional (3D) model is shown, and the specific parameters are given. The model focus on the steady-state impedance of the limiter when connected to the power grid. It analyzed the dependence of steady-state impedance on the AC coil current, and the relationship between oil gap and coil inductance. The results suggest that, adding oil gap between slice of silicon steel can reduce the core cross-section, restrain the ultraharmonic and decrease the steady-state impedance. As the core cross-section of AC limb decreased from 4344 cm2 to 3983 cm2, the total harmonic distortion for voltage decreased from 2.4% to 1.8%, and the impedance decreased from 1.082 Ω to 1.069 Ω(Idc=400A,Iac=1296A).

  9. Hydromagnetic conditions near the core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1995-01-01

    The main results of the grant were (1) finishing the manuscript of a proof of completeness of the Poincare modes in an incompressible nonviscous fluid corotating with a rigid ellipsoidal boundary, (2) partial completion of a manuscript describing a definition of helicity that resolved questions in the literature about calculating the helicities of vector fields with complicated topologies, and (3) the beginning of a reexamination of the inverse problem of inferring properties of the geomagnetic field B just outside the core-mantle boundary (CMB) from measurements of elements of B at and above the earth's surface. This last work has led to a simple general formalism for linear and nonlinear inverse problems that appears to include all the inversion schemes so far considered for the uniqueness problem in geomagnetic inversion. The technique suggests some new methods for error estimation that form part of this report.

  10. Feasibility and benefits of methanogenesis under oxygen-limited conditions

    SciTech Connect

    Zitomer, D.H.; Shrout, J.D.

    1998-12-31

    Methanogenic and aerobic (or microaerophilic) biological processes are often considered mutually exclusive and separated as biological wastewater treatment options. However, under oxygen-limited conditions, both aerobic respiration and methanogenesis can be practically accomplished by a single mixed culture. This paper describes sustained batch culture, oxygen-limited methanogenic serum bottle and bench-scale systems. Serum bottle cultures exhibited methanogenic activity similar to or greater than that of a strictly anaerobic culture maintained in parallel. The COD removal efficiencies of anaerobic, oxygen-limited, and aerobic bench-scale reactors receiving 30,000 mg/l of sucrose were all greater than 93%, a system receiving 1 g O{sub 2}/L{sub R}-day achieved a lower final effluent COD than the strictly anaerobic reactor. After a shock-load of sucrose, the pH recovered in low-aeration batch reactors in 28--34 days, whereas anaerobic pH did not recover after 52 days of observation. In the future, methanogenesis under limited-aeration may be employed as an energy efficient treatment option to achieve low final COD concentrations, minimal biosolids generation, and mineralization of a broad range of specific organic chemicals.

  11. Oxygen Consumption Rates of Bacteria under Nutrient-Limited Conditions

    PubMed Central

    Riedel, Timothy E.; Nealson, Kenneth H.; Finkel, Steven E.

    2013-01-01

    Many environments on Earth experience nutrient limitation and as a result have nongrowing or very slowly growing bacterial populations. To better understand bacterial respiration under environmentally relevant conditions, the effect of nutrient limitation on respiration rates of heterotrophic bacteria was measured. The oxygen consumption and population density of batch cultures of Escherichia coli K-12, Shewanella oneidensis MR-1, and Marinobacter aquaeolei VT8 were tracked for up to 200 days. The oxygen consumption per CFU (QO2) declined by more than 2 orders of magnitude for all three strains as they transitioned from nutrient-abundant log-phase growth to the nutrient-limited early stationary phase. The large reduction in QO2 from growth to stationary phase suggests that nutrient availability is an important factor in considering environmental respiration rates. Following the death phase, during the long-term stationary phase (LTSP), QO2 values of the surviving population increased with time and more cells were respiring than formed colonies. Within the respiring population, a subpopulation of highly respiring cells increased in abundance with time. Apparently, as cells enter LTSP, there is a viable but not culturable population whose bulk community and per cell respiration rates are dynamic. This result has a bearing on how minimal energy requirements are met, especially in nutrient-limited environments. The minimal QO2 rates support the extension of Kleiber's law to the mass of a bacterium (100-fg range). PMID:23770901

  12. USE OF SEDIMENT CORES TO ESTABLISH REFERENCE CONDITIONS

    EPA Science Inventory

    In order to assess the degree to which integrity of waterbodies have been degraded, comparisons are made to "reference" conditions. Finding systems with similar ecological components, but absent the specific stressors of concern, may often be difficult or even impossible. An alt...

  13. Core Formation Under Dynamic Conditions: Physical Processes and Geochemical Signatures

    NASA Technical Reports Server (NTRS)

    Rushmer, T.; Gaetani, G.; Jones, J. H.; Sparks, J.

    2001-01-01

    We have experimentally investigated liquid metal segregation from a solid silicate matrix under conditions of applied stress. Liquid moves in fractures and formation of fayalitic olivine from orthopyroxene by migrating Fe-Ni-S-O liquids is observed. Additional information is contained in the original extended abstract.

  14. An analysis of the proposed MITR-III core to establish thermal-hydraulic limits at 10 MW. Final report

    SciTech Connect

    Harling, O.K.; Lanning, D.D.; Bernard, J.A.; Meyer, J.E.; Henry, A.F.

    1997-06-01

    The 5 MW Massachusetts Institute of Technology Research Reactor (MITR-II) is expected to operate under a new license beginning in 1999. Among the options being considered is an upgrade in the heat removal system to allow operation at 10 MW. The purpose of this study is to predict the Limiting Safety System Settings and Safety Limits for the upgraded reactor (MITR-III). The MITR Multi-Channel Analysis Code was written to analyze the response of the MITR system to a series of anticipated transients in order to determine the Limiting Safety System Settings and Safety Limits under various operating conditions. The MIT Multi-Channel Analysis Code models the primary and secondary systems, with special emphasis placed on analyzing the thermal-hydraulic conditions in the core. The code models each MITR fuel element explicitly in order to predict the behavior of the system during flow instabilities. The results of the code are compared to experimental data from MITR-II and other sources. New definitions are suggested for the Limiting Safety System Settings and Safety Limits. MITR Limit Diagrams are included for three different heat removal system configurations. It is concluded that safe, year-round operating at 10 MW is possible, given that the primary and secondary flow rates are both increased by approximately 40%.

  15. The Structure of Gas-accreting Protoplanets and the Condition of the Critical Core Mass

    NASA Astrophysics Data System (ADS)

    Kanagawa, Kazuhiro D.; Fujimoto, Masayuki Y.

    2013-03-01

    In the core accretion model for the formation of gas giant planets, runaway gas accretion onto a core is the primary requisite, triggered when the core mass reaches a critical value. The recently revealed wide diversity of the extrasolar giant planets suggests the necessity to further the understanding of the conditions resulting in the critical core mass that initiates runaway accretion. We study the internal structure of protoplanets under hydrostatic and thermal equilibria represented in terms of a polytropic equation of state to investigate what factors determine and affect the critical core mass. We find that the protoplanets, embedded in protoplanetary disks, have the same configuration as red giants, characterized by the envelope of the centrally condensed type solution. Applying the theory of stellar structure with homology invariants, we demonstrate that there are three types of criteria for the critical core mass depending on the stiffness of polytrope and the nature of outer boundary condition. For the stiff polytropes of index N <= 3 with the Bondi radius as the outer boundary, the criterion governing the critical core mass occurs at the surface. For stiff polytropes with the Hill outer boundary and for soft polytropes of N > 3, this criterion acts at the bottom of gaseous envelope. Further, we elucidate the roles and effects of coexistent radiative and convective zones in the envelope of critical core mass. Based on the results, we discuss the relevance of Bondi and Hill surface conditions and explore the parameter dependences of critical core mass.

  16. THE STRUCTURE OF GAS-ACCRETING PROTOPLANETS AND THE CONDITION OF THE CRITICAL CORE MASS

    SciTech Connect

    Kanagawa, Kazuhiro D.; Fujimoto, Masayuki Y.

    2013-03-01

    In the core accretion model for the formation of gas giant planets, runaway gas accretion onto a core is the primary requisite, triggered when the core mass reaches a critical value. The recently revealed wide diversity of the extrasolar giant planets suggests the necessity to further the understanding of the conditions resulting in the critical core mass that initiates runaway accretion. We study the internal structure of protoplanets under hydrostatic and thermal equilibria represented in terms of a polytropic equation of state to investigate what factors determine and affect the critical core mass. We find that the protoplanets, embedded in protoplanetary disks, have the same configuration as red giants, characterized by the envelope of the centrally condensed type solution. Applying the theory of stellar structure with homology invariants, we demonstrate that there are three types of criteria for the critical core mass depending on the stiffness of polytrope and the nature of outer boundary condition. For the stiff polytropes of index N {<=} 3 with the Bondi radius as the outer boundary, the criterion governing the critical core mass occurs at the surface. For stiff polytropes with the Hill outer boundary and for soft polytropes of N > 3, this criterion acts at the bottom of gaseous envelope. Further, we elucidate the roles and effects of coexistent radiative and convective zones in the envelope of critical core mass. Based on the results, we discuss the relevance of Bondi and Hill surface conditions and explore the parameter dependences of critical core mass.

  17. Motions and Initial Conditions in Star-Forming Dense Cores

    NASA Technical Reports Server (NTRS)

    Myers, Philip C.

    2001-01-01

    Under this grant in the past year we have pursued spectral-line observations of star-forming regions over size scales from 0.01 pc to 0.5 pc. Our main goal has been to measure the systematic and turbulent motions of condensing and collapsing gas. In this area, our results include (1) in 67 starless dense cores, some 19 show clear evidence of spatially extended inward motions, with typical line-of-sight inward speed 0.05-0.09 km s(sup -1) and with typical plane-of-the-sky extent 0.1-0.3 pc, (2) In some 40 nearby regions with embedded groups and clusters, we see extended infall asymmetry in lines of CS and HCO(+) clearly in 4 regions and less clearly in 4 others, (3) Using finer resolution (15 arcsec or 0.01-0.02 pc) and lines tracing higher density, we see spatial concentration of infall asymmetry near the protostars in NGC 1333 IRS 4A and B, L483, and L1251B, and with still finer resolution (2 arcsec or 0.003 pc or 600 AU) we detect inverse P Cyg profiles, indicating absorption of continuum emission from the protostellar envelope by infalling gas in NGC 1333 IRS 4A and 4B. Further, at high resolution we identify regions of stellar mass and low turbulence ("kernels") which are good candidates to become the next generation of stars in embedded clusters. In addition we have completed a survey for the OH Zeeman effect in absorption against nearby H II regions, indicating that the large-scale magnetic field may be nearly critical if it typically threads a flattened structure. We have also developed a model of spatially extended infall motions based on dissipation of turbulence in a magnetized, selfgravitating layer. In the following we describe some of these results in more detail.

  18. Social Interest and the Core Conditions: Could It Be that Adler Influenced Rogers?

    ERIC Educational Resources Information Center

    Watts, Richard E.

    1996-01-01

    Presents primary source documentation highlighting the similarities between Alfred Adler's social interest construct and the counselor-oriented core conditions of Carl Rogers. Implications of the similarities are discussed. (Author)

  19. Experimental determination of the electrical resistivity of iron at Earth’s core conditions

    NASA Astrophysics Data System (ADS)

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth’s core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth’s core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch–Grüneisen law, which considers only the electron–phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth’s core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core.

  20. Experimental determination of the electrical resistivity of iron at Earth's core conditions.

    PubMed

    Ohta, Kenji; Kuwayama, Yasuhiro; Hirose, Kei; Shimizu, Katsuya; Ohishi, Yasuo

    2016-06-01

    Earth continuously generates a dipole magnetic field in its convecting liquid outer core by a self-sustained dynamo action. Metallic iron is a dominant component of the outer core, so its electrical and thermal conductivity controls the dynamics and thermal evolution of Earth's core. However, in spite of extensive research, the transport properties of iron under core conditions are still controversial. Since free electrons are a primary carrier of both electric current and heat, the electron scattering mechanism in iron under high pressure and temperature holds the key to understanding the transport properties of planetary cores. Here we measure the electrical resistivity (the reciprocal of electrical conductivity) of iron at the high temperatures (up to 4,500 kelvin) and pressures (megabars) of Earth's core in a laser-heated diamond-anvil cell. The value measured for the resistivity of iron is even lower than the value extrapolated from high-pressure, low-temperature data using the Bloch-Grüneisen law, which considers only the electron-phonon scattering. This shows that the iron resistivity is strongly suppressed by the resistivity saturation effect at high temperatures. The low electrical resistivity of iron indicates the high thermal conductivity of Earth's core, suggesting rapid core cooling and a young inner core less than 0.7 billion years old. Therefore, an abrupt increase in palaeomagnetic field intensity around 1.3 billion years ago may not be related to the birth of the inner core. PMID:27251282

  1. First-wall and limiter conditioning in TFTR

    SciTech Connect

    Dylla, H.F.; Blanchard, W.R.; Hawryluk, R.J.; Hill, K.W.; Krawchuk, R.B.; Mueller, D.; Owens, D.K.; Ramsey, A.T.; Sesnic, S.; Tenney, F.H.

    1984-10-01

    A progress report on the experimental studies of vacuum vessel conditioning during the first year of TFTR operation is presented. A previous paper described the efforts expended to condition the TFTR vessel prior to and during the initial plasma start-up experiments. During the start-up phase, discharge cleaning was performed with the vessel at room temperature. For the second phase of TFTR operations, which was directed towards the optimization of ohmically heated plasmas, the vacuum vessel could be heated to 150/sup 0/C. The internal configuration of the TFTR vessel was more complex during the second phase with the addition of a TiC/C moveable limiter array, Inconel bellows cover plates, and ZrAl getter pumps. A quantitative comparison is given on the effectiveness of vessel bakeout, glow discharge cleaning, and pulse discharge cleaning in terms of the total quantity of removed carbon and oxygen, residual gas base pressures and the resulting plasma impurity levels as measured by visible, uv, and soft x-ray spectroscopy. The initial experience with hydrogen isotope changeover in TFTR is presented including the results of the attempt to hasten the changeover time by using a glow discharge to precondition the vessel with the new isotope.

  2. Sound velocities of iron carbides (Fe3C and Fe7C3) under core conditions

    NASA Astrophysics Data System (ADS)

    Chen, B.; Li, Z.; Zhang, D.; Liu, J.; Bi, W.; Zhao, J.; Alp, E. E.; Hu, M. Y.; Li, J.

    2014-12-01

    For a carbon-rich core, iron carbides might be the major phase crystallizing to form the Earth's solid inner core. On basis of high-pressure experiments and theoretical calculations, Fe3C, Fe7C3 and more recently Fe2C have been considered as the most stable carbide phase under the inner core conditions. The identity of the stable carbide phase in a carbon-containing inner core is still a topic under active debate. It is crucial to determine the elastic and acoustic properties of the relevant carbide phases to core conditions, in order to test the carbon-rich core composition model. In this study, we have performed nuclear resonant inelastic X-ray scattering (NRIXS) measurements of both Fe7C3 and Fe3C up to core pressures at 300 K and determined their shear-wave (VS) and compressional-wave (VP) velocities for comparison with seismic observations of the inner core. The high-pressure magnetic properties of both phases have also been investigated by X-ray Emission Spectroscopy (XES) and Synchrotron Mössbauer Spectroscopy (SMS). Our results show that the magnetic transitions from ferromagnetic to paramagnetic and then to nonmagnetic in Fe7C3 and Fe3C significantly affects their VS and VP at high pressures. Extrapolating the sound velocities of the nonmagnetic phases to the inner core conditions, we found that sound velocities, particularly VS, of the iron carbides are markedly low comparing with iron and other iron-rich alloys, making them compelling candidates to explain the seismic observations of the inner core. Our hypothesis of a carbon-rich core may also be consistent with geochemical and petrological evidence on deep carbon inventory in Earth's interior.

  3. Current limiting behavior in three-phase transformer-type SFCLs using an iron core according to variety of fault

    NASA Astrophysics Data System (ADS)

    Cho, Yong-Sun; Jung, Byung-Ik; Ha, Kyoung-Hun; Choi, Soo-Geun; Park, Hyoung-Min; Choi, Hyo-Sang

    To apply the superconducting fault current limiter (SFCL) to the power system, the reliability of the fault-current-limiting operation must be ensured in diverse fault conditions. The SFCL must also be linked to the operation of the high-speed recloser in the power system. In this study, a three-phase transformer-type SFCL, which has a neutral line to improve the simultaneous quench characteristics of superconducting elements, was manufactured to analyze the fault-current-limiting characteristic according to the single, double, and triple line-to-ground faults. The transformer-type SFCL, wherein three-phase windings are connected to one iron core, reduced the burden on the superconducting element as the superconducting element on the sound phase was also quenched in the case of the single line-to-ground fault. In the case of double or triple line-to-ground faults, the flux from the faulted phase winding was interlinked with other faulted or sound phase windings, and the fault-current-limiting rate decreased because the windings of three phases were inductively connected by one iron core.

  4. A distance-limited sample of massive star-forming cores from the RMS

    NASA Astrophysics Data System (ADS)

    Maud, L. T.; Lumsden, S. L.; Moore, T. J. T.; Mottram, J. C.; Urquhart, J. S.; Cicchini, A.

    2015-09-01

    We analyse C18O (J = 3-2) data from a sample of 99 infrared (IR)-bright massive young stellar objects (MYSOs) and compact H II regions that were identified as potential molecular-outflow sources in the Red MSX Source survey. We extract a distance-limited (D < 6 kpc) sample shown to be representative of star formation covering the transition between the source types. At the spatial resolution probed, Larson-like relationships are found for these cores, though the alternative explanation, that Larson's relations arise where surface-density-limited samples are considered, is also consistent with our data. There are no significant differences found between source properties for the MYSOs and H II regions, suggesting that the core properties are established prior to the formation of massive stars, which subsequently have little impact at the later evolutionary stages investigated. There is a strong correlation between dust-continuum and C18O-gas masses, supporting the interpretation that both trace the same material in these IR-bright sources. A clear linear relationship is seen between the independently established core masses and luminosities. The position of MYSOs and compact H II regions in the mass-luminosity plane is consistent with the luminosity expected from the most massive protostar in the cluster when using an ˜40 per cent star formation efficiency and indicates that they are at a similar evolutionary stage, near the end of the accretion phase.

  5. The Annular Core Research Reactor (ACRR) postulated limiting event initial and building source terms

    SciTech Connect

    Restrepo, L F

    1992-08-01

    As part of the update of the Safety analysis Report (SAR) for the Annular Core Research Reactor (ACRR), operational limiting events under the category of inadvertent withdrawal of an experiment while at power or during a power pulse were determined to be the most limiting event(s) for this reactor. This report provides a summary of the assumptions, modeling, and results in evaluation of: Reactivity and thermal hydraulics analysis to determine the amount of fuel melt or fuel damage ratios; The reactor inventories following the limiting event; A literature review of post NUREG-0772 release fraction experiment results on severe fuel damages; Decontamination factors due to in-pool transport; and In-building transport modeling and building source term analysis.

  6. Mode-converters for rectangular-core fiber amplifiers to achieve diffraction-limited power scaling.

    PubMed

    Sridharan, Arun Kumar; Pax, Paul H; Heebner, John E; Drachenberg, Derrek R; Armstrong, J Paul; Dawson, Jay W

    2012-12-17

    A rectangular-core (ribbon) fiber that guides and amplifies a single higher-order-mode (HOM) can potentially scale to much higher average powers than what is possible in traditional circular-core large-mode-area fibers. Such an amplifier would require mode-conversion at the input to enable interfacing with seed sources that typically output TEM(00) mode radiation and at the output to generate diffraction-limited radiation for end-user applications. We present the first simulation and experimental results of a mode conversion technique that uses two diffractive-optic-elements in conjugate Fourier planes to convert a diffraction limited TEM(00) mode to the HOM of a ribbon fiber. Mode-conversion-efficiency is approximately 84% and can theoretically approach 100%. We also demonstrate a mode-converter system that converts a single HOM of a ribbon fiber back to a diffraction-limited TEM(00) mode. Conversion efficiency is a record 80.5%. PMID:23263119

  7. Accessing High Pressure States Relevant to Core Conditions in the Giant Planets

    SciTech Connect

    Remington, B A; Cavallo, R M; Edwards, M J; Ho, D D; Lorenz, K T; Lorenzana, H E; Lasinski, B F; McNaney, J M; Pollaine, S M; Smith, R F

    2004-04-15

    We have designed an experimental technique to use on the National Ignition Facility (NIF) laser to achieve very high pressure (P{sub max} > 10 Mbar = 1000 GPa), dense states of matter at moderate temperatures (kT < 0.5 eV = 6000 K), relevant to the core conditions of the giant planets. A discussion of the conditions in the interiors of the giant planets is given, and an experimental design that can approach those conditions is described.

  8. Conditions for diffusion-limited and reaction-limited recombination in nanostructured solar cells

    SciTech Connect

    Ansari-Rad, Mehdi; Anta, Juan A.; Arzi, Ezatollah

    2014-04-07

    The performance of Dye-sensitized solar cells (DSC) and related devices made of nanostructured semiconductors relies on a good charge separation, which in turn is achieved by favoring charge transport against recombination. Although both processes occur at very different time scales, hence ensuring good charge separation, in certain cases the kinetics of transport and recombination can be connected, either in a direct or an indirect way. In this work, the connection between electron transport and recombination in nanostructured solar cells is studied both theoretically and by Monte Carlo simulation. Calculations using the Multiple-Trapping model and a realistic trap distribution for nanostructured TiO{sub 2} show that for attempt-to-jump frequencies higher than 10{sup 11}–10{sup 13} Hz, the system adopts a reaction limited (RL) regime, with a lifetime which is effectively independent from the speed of the electrons in the transport level. For frequencies lower than those, and depending on the concentration of recombination centers in the material, the system enters a diffusion-limited regime (DL), where the lifetime increases if the speed of free electrons decreases. In general, the conditions for RL or DL recombination depend critically on the time scale difference between recombination kinetics and free-electron transport. Hence, if the former is too rapid with respect to the latter, the system is in the DL regime and total thermalization of carriers is not possible. In the opposite situation, a RL regime arises. Numerical data available in the literature, and the behavior of the lifetime with respect to (1) density of recombination centers and (2) probability of recombination at a given center, suggest that a typical DSC in operation stays in the RL regime with complete thermalization, although a transition to the DL regime may occur for electrolytes or hole conductors where recombination is especially rapid or where there is a larger dispersion of energies of

  9. Body core temperature of rats subjected to daily exercise limited to a fixed time

    NASA Astrophysics Data System (ADS)

    Shido, O.; Sugimoto, Naotoshi; Sakurada, Sotaro; Kaneko, Yoshiko; Nagasaka, Tetsuo

    Several timed daily environmental cues alter the pattern of nycthemeral variations in body core temperature in rodents. The present study investigated the effect of timed exercise on variations of daily body core temperature. Male rats were housed in cages with a running wheel at an ambient temperature of 24° C with a 12:12 h light/dark cycle. Timed daily exercise rats (TEX) were allowed access to the wheel for 6 h in the last half of the dark phase, freely exercising rats (FEX) could run at any time, and sedentary rats (NEX) were not allowed to run. After a 3-week exercise period, all animals were denied access to the wheel. The intraabdominal temperatures (Tab) and spontaneous activities of rats were measured for 6 days after the exercise period. The Tab values of the TEX rats were significantly higher than those of the other two groups only in the last half of the dark phase, while Tab in the FEX and NEX rats showed no significant difference. The specific Tab changes in the TEX rats lasted for 2 days after the exercise period. Spontaneous activity levels were higher in the TEX rats than the FEX and NEX rats in the last half of the dark phase for 1 day after the exercise period. The results suggest that daily exercise limited to a fixed time per day modifies nycthemeral variations of body core temperature in rats so that the temperature increases during the period when the animals had previously exercised. Such a rise in body core temperature is partly attributed to an increase in the spontaneous activity level.

  10. Excitation energy transfer in Chlamydomonas reinhardtii deficient in the PSI core or the PSII core under conditions mimicking state transitions.

    PubMed

    Wlodarczyk, Lucyna M; Dinc, Emine; Croce, Roberta; Dekker, Jan P

    2016-06-01

    The efficient use of excitation energy in photosynthetic membranes is achieved by a dense network of pigment-protein complexes. These complexes fulfill specific functions and interact dynamically with each other in response to rapidly changing environmental conditions. Here, we studied how in the intact cells of Chlamydomonas reinhardtii (C.r.) the lack of the photosystem I (PSI) core or the photosystem II (PSII) core affects these interactions. To that end the mutants F15 and M18 (both PSI-deficient) and FUD7 (PSII-deficient) were incubated under conditions known to promote state transitions in wild-type. The intact cells were then instantly frozen to 77K and the full-spectrum time-resolved fluorescence emission of the cells was measured by means of streak camera. In the PSI-deficient mutants excitation energy transfer (EET) towards light-harvesting complexes of PSI (Lhca) occurs in less than 0.5 ns, and fluorescence from Lhca decays in 3.1 ns. Decreased trapping by PSII and increased fluorescence of Lhca upon state 1 (S1)→state 2 (S2) transition appears in the F15 and less in the M18 mutant. In the PSII-deficient mutant FUD7, quenched (0.5 ns) and unquenched (2 ns) light-harvesting complexes of PSII (LHCII) are present in both states, with the quenched form more abundant in S2 than in S1. Moreover, EET of 0.4 ns from the remaining LHCII to PSI increases upon S1→S2 transition. We relate the excitation energy kinetics observed in F15, M18 and FUD7 to the remodeling of the photosynthetic apparatus in these mutants under S1 and S2 conditions. PMID:26946087

  11. Liquid Iron Alloys with Hydrogen at Outer Core Conditions by First Principles

    NASA Astrophysics Data System (ADS)

    Umemoto, K.; Hirose, K.

    2015-12-01

    Since the density of the outer core deduced from seismic data is about 10% lower than that of pure iron at core pressures and temperatures (P-T), it is widely believed that the outer core includes one or more light elements. Although intensive experimental and theoretical studies have been performed so far, the light element in the core has not yet been identified. Comparison of the density and sound velocity of liquid iron alloys with observations, such as the PREM, is a promising way to determine the species and quantity of light alloying component(s) in the outer core. Here we report the results of a first-principles molecular dynamics study on liquid iron alloyed with hydrogen, one of candidates of the light elements. Hydrogen had been much less studied than other candidates. However, hydrogen has been known to reduce the melting temperature of Fe-H solid [1]. Furthermore, very recently, Nomura et al. argued that the outer core may include 24 at.% H in order to be molten under relatively low temperature (< 3600 K) [2]. Since then hydrogen has attracted strong interests. We clarify the effects of hydrogen on density and sound velocity of liquid iron alloys under outer core P-T conditions. It is shown that ~1 wt% hydrogen can reproduce PREM density and sound velocity simultaneously very well. In addition, we show the presence of hydrogen rather reduces Gruneisen parameters. It indicates that, if hydrogen exists in the outer core, temperature profile of the outer core could be changed considerably from one estimated so far. [1] Sakamaki, K., E. Takahashi, Y. Nakajima, Y. Nishihara, K. Funakoshi, T. Suzuki, and Y. Fukai, Phys. Earth Planet. Inter., 174, 192-201 (2009). [2] Nomura, R., K. Hirose, K. Uesugi, Y. Ohishi, A. Tsuchiyama, A. Miyake, and Y. Ueno, Science 31, 522-525 (2014).

  12. Biological effects of extreme environmental conditions. [considering limits of biosphere

    NASA Technical Reports Server (NTRS)

    Imshenetskiy, A. A.

    1975-01-01

    Actions of extreme physical and chemical space factors on microorganisms and plants are elaborated in order to establish limits for the biosphere. Considered are effects of low and high temperatures; ionizing and ultraviolet radiation; various gases; and effects of vibration, desiccation and acceleration.

  13. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  14. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  15. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  16. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  17. Direct measurement of thermal conductivity in solid iron at planetary core conditions

    NASA Astrophysics Data System (ADS)

    Konôpková, Zuzana; McWilliams, R. Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F.

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth’s core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth’s magnetic field via dynamo action. Attempts to describe thermal transport in Earth’s core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth’s core near the low end of previous estimates, at 18–44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth’s geodynamo has persisted since the beginning of Earth’s history, and allows for a solid inner core as old as the dynamo.

  18. Direct measurement of thermal conductivity in solid iron at planetary core conditions.

    PubMed

    Konôpková, Zuzana; McWilliams, R Stewart; Gómez-Pérez, Natalia; Goncharov, Alexander F

    2016-06-01

    The conduction of heat through minerals and melts at extreme pressures and temperatures is of central importance to the evolution and dynamics of planets. In the cooling Earth's core, the thermal conductivity of iron alloys defines the adiabatic heat flux and therefore the thermal and compositional energy available to support the production of Earth's magnetic field via dynamo action. Attempts to describe thermal transport in Earth's core have been problematic, with predictions of high thermal conductivity at odds with traditional geophysical models and direct evidence for a primordial magnetic field in the rock record. Measurements of core heat transport are needed to resolve this difference. Here we present direct measurements of the thermal conductivity of solid iron at pressure and temperature conditions relevant to the cores of Mercury-sized to Earth-sized planets, using a dynamically laser-heated diamond-anvil cell. Our measurements place the thermal conductivity of Earth's core near the low end of previous estimates, at 18-44 watts per metre per kelvin. The result is in agreement with palaeomagnetic measurements indicating that Earth's geodynamo has persisted since the beginning of Earth's history, and allows for a solid inner core as old as the dynamo. PMID:27251283

  19. Thermopyhsical conditions for the onset of a core dynamo in Vesta

    NASA Astrophysics Data System (ADS)

    Formisano, Michelangelo; Federico, Costanzo; De Angelis, Simone; De Sanctis, Maria Cristina; Magni, Gianfranco

    2016-04-01

    Recently, a study on the magnetization of the eucrite meteorite Allan Hills A81001 [1] has suggested the possibility that, in its primordial history, Vesta had an active core dynamo. The magnetic field associated could have preserved Vesta from the space-weathering. In this work, using a parametrized thermal convection method, we verified the thermophysical conditions for the onset of a core dynamo. The starting point is a post-differentiated structure [2,3,4], made of a metallic core, silicate mantle and rocky crust. We explored four different fully differentiated configurations of Vesta [5], characterized by different chondritic composition, with the constraints on the core size and density provided by [6]. We also explored three different scaling laws for the core velocity (mixing-length theory, MAC and an intermediate case). Core and mantle have both a temperature-dependent viscosity, which is the parameter that largely influences the magnetic Reynolds number and the dynamo duration. Our results suggest that Vesta had an active dynamo, whose duration lies in the range 150-500 Myr and the more appropriate scaling law for the core velocity is that given by the mixing-length theory. The maximum strength of the primordial core magnetic field is compatible with the estimations provided by [1]. [1] Fu, R. et al, 2012, Science 338, 238 [2] Ghosh, A. and McSween, H.Y., 1998, Icarus, 134, 187 [3] Formisano, M. et al., 2013, Meteoritics and Planetary Science, 48, 2316 [4] Neumann, W., et al., 2014, Earth and Planetary Science Letters, 395, 267 [5] Toplis, M.J., et al., 2013, Meteoritics and Planetary Science, 48, 2300 [6] Ermakov, A.I., et al.2014, Icarus, 240, 146

  20. The Limits of Knowledge Management in Contemporary Corporate Conditions

    ERIC Educational Resources Information Center

    Garrick, John

    2014-01-01

    This paper draws on Jean-François Lyotard's (1984) seminal study "The Postmodern Condition: A Report on Knowledge" to reflect on two macro-level catastrophes: the global financial crisis (GFC) of 2009 (and its continuing effects throughout the Eurozone and elsewhere) and Fukushima. These two case studies probe aspects of these grand…

  1. 33 CFR 330.4 - Conditions, limitations, and restrictions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... comply with the provisions of 33 CFR 325.4. In the latter case, the conditioned 401 water quality... event shall the period exceed one (1) year (see 33 CFR 325.2(b)(1)(ii)). Upon receipt of an individual... provisions of 33 CFR 325.4 or believes for some other specific reason it would be inappropriate to...

  2. 33 CFR 330.4 - Conditions, limitations, and restrictions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... comply with the provisions of 33 CFR 325.4. In the latter case, the conditioned 401 water quality... event shall the period exceed one (1) year (see 33 CFR 325.2(b)(1)(ii)). Upon receipt of an individual... provisions of 33 CFR 325.4 or believes for some other specific reason it would be inappropriate to...

  3. 33 CFR 330.4 - Conditions, limitations, and restrictions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... comply with the provisions of 33 CFR 325.4. In the latter case, the conditioned 401 water quality... event shall the period exceed one (1) year (see 33 CFR 325.2(b)(1)(ii)). Upon receipt of an individual... provisions of 33 CFR 325.4 or believes for some other specific reason it would be inappropriate to...

  4. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  5. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  6. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 74 FR 62696, Dec. 1, 2009. (a) No pilot may take off an airplane that has frost, ice, or snow... follow conditions: (1) Takeoffs may be made with frost adhering to the wings, or stabilizing or control surfaces, if the frost has been polished to make it smooth. (2) Takeoffs may be made with frost under...

  7. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  8. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  9. Dendritic carbon architectures formed by nanotube core-directed diffusion-limited aggregation of nanoparticles.

    PubMed

    Liu, Zhenyu; Kong, Xiaohui

    2010-08-28

    A regular array of fractal patterns with macroscopic dendritic carbon architecture was prepared by catalytic chemical vapor deposition (CVD). The dendritic carbon architectures have micrometre-sized stems and hyperbranches evolved by lateral growth, and they are formed by diffusion-limited aggregation of carbon-encapsulated iron nanoparticle building blocks generated from catalytic pyrolysis of toluene, which is directed by carbon nanotube cores, and followed by subsequent restructuring from surface to bulk. Incorporation of such proposed processes in Monte Carlo simulations generates dendritic architectures similar to the morphologies observed from the experiments. The findings provide direct information to the time resolved evolution of the morphology and microstructure of the dendritic carbon architecture, which mimic the nature behavior as snowflake attaching on the tree branches. Those will be important to understand the growth of vapor grown carbon fibers and carbon filamentous structures, and further possibility to control branching out of vapor grown carbon fibers. PMID:20607160

  10. Operating condition limitations of high density QCW arrays

    NASA Astrophysics Data System (ADS)

    Junghans, Jeremy; Levy, Joseph; Feeler, Ryan

    2012-03-01

    Northrop Grumman Cutting Edge Optronics (NGCEO) has developed a laser diode array package with minimal bar-tobar spacing. These High Density Stack (HDS) packages allow for a power density increase on the order of ~ 2.5x when compared to industry-standard arrays. Power densities as high as 15 kW/cm2 can be achieved when operated at 200 W/bar. This work provides a detailed description of the duty factor, pulse width and power limitations of high density arrays. The absence of the interposing heatsinks requires that all of the heat generated by the interior bars must travel through the adjacent bars to the electrical contacts. This results in limitations to the allowable operating envelope of the HDS arrays. Thermal effects such as wavelength shifts across large HDS arrays are discussed. An overview of recent HDS design and manufacturing improvements is also presented. These improvements result in reliable operation at higher power densities and increased duty factors. A comparison of the effect of bar geometry on HDS performance is provided. Test data from arrays featuring these improvements based on both full 1 cm wide diode bars as well as 3 mm wide mini-bars is also presented.

  11. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    DOE PAGESBeta

    Bose, A.; Woo, K. M.; Betti, R.; Campbell, E. M.; Mangino, D.; Christopherson, A. R.; McCrory, R. L.; Nora, R.; Regan, S. P.; Goncharov, V. N.; et al

    2016-07-07

    Here, it is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett.more » 117, 025001 (2016)] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.« less

  12. Core conditions for alpha heating attained in direct-drive inertial confinement fusion

    NASA Astrophysics Data System (ADS)

    Bose, A.; Woo, K. M.; Betti, R.; Campbell, E. M.; Mangino, D.; Christopherson, A. R.; McCrory, R. L.; Nora, R.; Regan, S. P.; Goncharov, V. N.; Sangster, T. C.; Forrest, C. J.; Frenje, J.; Gatu Johnson, M.; Glebov, V. Yu; Knauer, J. P.; Marshall, F. J.; Stoeckl, C.; Theobald, W.

    2016-07-01

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016), 10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions.

  13. Massive Infrared-Quiet Dense Cores: Unveiling the Initial Conditions of High-Mass Star Formation

    NASA Astrophysics Data System (ADS)

    Motte, F.; Bontemps, S.; Schneider, N.; Schilke, P.; Menten, K. M.

    2008-05-01

    As Th. Henning said at the conference, cold precursors of high-mass stars are now ``hot topics''. We here propose some observational criteria to identify massive infrared-quiet dense cores which can host the high-mass analogs of Class~0 protostars and pre-stellar condensations. We also show how far-infrared to millimeter imaging surveys of entire complexes forming OB stars are starting to unveil the initial conditions of high-mass star formation.

  14. Laboratory Equipment for Investigation of Coring Under Mars-like Conditions

    NASA Astrophysics Data System (ADS)

    Zacny, K.; Cooper, G.

    2004-12-01

    To develop a suitable drill bit and set of operating conditions for Mars sample coring applications, it is essential to make tests under conditions that match those of the mission. The goal of the laboratory test program was to determine the drilling performance of diamond-impregnated bits under simulated Martian conditions, particularly those of low pressure and low temperature in a carbon dioxide atmosphere. For this purpose, drilling tests were performed in a vacuum chamber kept at a pressure of 5 torr. Prior to drilling, a rock, soil or a clay sample was cooled down to minus 80 degrees Celsius (Zacny et al, 2004). Thus, all Martian conditions, except the low gravity were simulated in the controlled environment. Input drilling parameters of interest included the weight on bit and rotational speed. These two independent variables were controlled from a PC station. The dependent variables included the bit reaction torque, the depth of the bit inside the drilled hole and the temperatures at various positions inside the drilled sample, in the center of the core as it was being cut and at the bit itself. These were acquired every second by a data acquisition system. Additional information such as the rate of penetration and the drill power were calculated after the test was completed. The weight of the rock and the bit prior to and after the test were measured to aid in evaluating the bit performance. In addition, the water saturation of the rock was measured prior to the test. Finally, the bit was viewed under the Scanning Electron Microscope and the Stereo Optical Microscope. The extent of the bit wear and its salient features were captured photographically. The results revealed that drilling or coring under Martian conditions in a water saturated rock is different in many respects from drilling on Earth. This is mainly because the Martian atmospheric pressure is in the vicinity of the pressure at the triple point of water. Thus ice, heated by contact with the

  15. Siderophile Element Constraints on the Conditions of Core Formation in Mars

    NASA Technical Reports Server (NTRS)

    Righter, K.; Humayun, M.

    2012-01-01

    Siderophile element concentrations in planetary basalts and mantle samples have been used to estimate conditions of core formation for many years and have included applications to Earth, Moon, Mars and asteroid 4 Vesta [1]. For Earth, we have samples of mantle and a diverse collection of mantle melts which have provided a mature understanding of the how to reconstruct the concentration of siderophile elements in mantle materials, from only concentrations in surficial basalt (e.g., [2]). This approach has led to the consensus views that Earth underwent an early magma ocean stage to pressures of 40-50 GPa (e.g., [3,4]), Moon melted extensively and formed a small (approx. 2 mass %) metallic core [5], and 4 Vesta contains a metallic core that is approximately 18 mass % [6,7]. Based on new data from newly found meteorites, robotic spacecraft, and experimental partitioning studies, [8] showed that eight siderophile elements (Ni, Co, Mo, W, Ga, P, V and Cr) are consistent with equilibration of a 20 mass% S-rich metallic core with the mantle at pressures of 14 +/- 3 GPa. We aim to test this rather simple scenario with additional analyses of meteorites for a wide range of siderophile elements, and application of new experimental data for the volatile siderophile and highly siderophile elements.

  16. Melting of iron at the physical conditions of the Earth's core.

    PubMed

    Nguyen, Jeffrey H; Holmes, Neil C

    2004-01-22

    Seismological data can yield physical properties of the Earth's core, such as its size and seismic anisotropy. A well-constrained iron phase diagram, however, is essential to determine the temperatures at core boundaries and the crystal structure of the solid inner core. To date, the iron phase diagram at high pressure has been investigated experimentally through both laser-heated diamond-anvil cell and shock-compression techniques, as well as through theoretical calculations. Despite these contributions, a consensus on the melt line or the high-pressure, high-temperature phase of iron is lacking. Here we report new and re-analysed sound velocity measurements of shock-compressed iron at Earth-core conditions. We show that melting starts at 225 +/- 3 GPa (5,100 +/- 500 K) and is complete at 260 +/- 3 GPa (6,100 +/- 500 K), both on the Hugoniot curve-the locus of shock-compressed states. This new melting pressure is lower than previously reported, and we find no evidence for a previously reported solid-solid phase transition on the Hugoniot curve near 200 GPa (ref. 16). PMID:14737164

  17. Transport properties for liquid silicon-oxygen-iron mixtures at Earth's core conditions

    NASA Astrophysics Data System (ADS)

    Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario

    2013-01-01

    We report on the thermal and electrical conductivities of two liquid silicon-oxygen-iron mixtures (Fe0.82Si0.10O0.08 and Fe0.79Si0.08O0.13), representative of the composition of the Earth's outer core at the relevant pressure-temperature conditions, obtained from density functional theory calculations with the Kubo-Greenwood formulation. We find thermal conductivities k=100(160) W m-1 K-1, and electrical conductivities σ=1.1(1.3)×106Ω-1 m-1 at the top (bottom) of the outer core. These values are between two and three times higher than previous estimates, and have important implications for our understanding of the Earth's thermal history and the functioning of the Earth's magnetic field, including rapid cooling rate for the whole core or high level of radiogenic elements in the core. We also show results for a number of structural and dynamic properties of the mixtures, including the partial radial distribution functions, mean square displacements, viscosities, and speeds of sound.

  18. Liquid iron-hydrogen alloys at outer core conditions by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Umemoto, Koichiro; Hirose, Kei

    2015-09-01

    We examined the density, bulk sound (compressional) velocity, and Grüneisen parameter of liquid pure Fe, Fe100H28 (0.50 wt % H), Fe88H40 (0.81 wt % H), and Fe76H52 (1.22 wt % H) at Earth's outer core pressure and temperature (P-T) conditions (~100 to 350 GPa, 4000 to 7000 K) based on first-principles molecular dynamics calculations. The results demonstrate that the thermodynamic Grüneisen parameter of liquid iron alloy decreases with increasing pressure, temperature, and hydrogen concentration, indicating a relatively small temperature gradient in the outer core when hydrogen is present. Along such temperature profile, both the density and compressional velocity of liquid iron containing ~1 wt % hydrogen match seismological observations. It suggests that hydrogen could be a primary light element in the core, although the shear velocity of the inner core is not reconciled with solid Fe-H alloy and thus requires another impurity element.

  19. Transition from the adiabatic to the sudden limit in core-electron photoemission

    NASA Astrophysics Data System (ADS)

    Hedin, Lars; Michiels, John; Inglesfield, John

    1998-12-01

    Experimental results for core-electron photoemission Jk(ω) are often compared with the one-electron spectral function Ac(ɛk-ω), where ω is the photon energy, ɛk is the photoelectron energy, and the optical transition matrix elements are taken as constant. Since Jk(ω) is nonzero only for ɛk>0, we must actually compare it with Ac(ɛk-ω)θ(ɛk). For metals Ac(ω) is known to have a quasiparticle (QP) peak with an asymmetric power-law [theories of Mahan, Nozières, de Dominicis, Langreth, and others (MND)] singularity due to low-energy particle-hole excitations. The QP peak starts at the core-electron energy ɛc, and is followed by an extended satellite (shakeup) structure at smaller ω. For photon energies ω just above threshold, ωth=-ɛc, Ac(ɛk-ω)θ(ɛk) as a function of ɛk (ω constant) is cut just behind the quasiparticle peak, and neither the tail of the MND line nor the plasmon satellites are present. The sudden (high-energy) limit is given by a convolution of Ac(ω) and a loss function, i.e., by the Berglund-Spicer two-step expression. Thus Ac(ω) alone does not give the correct photoelectron spectrum, neither at low nor at high energies. We present an extension of the quantum-mechanical (QM) models developed earlier by Inglesfield, and by Bardyszewski and Hedin to calculate Jk(ω). It includes recoil and damping, as well as shakeup effects and extrinsic losses, is exact in the high-energy limit, and allows calculations of Jk(ω) including the MND line and multiple plasmon losses. The model, which involves electrons coupled to quasibosons, is motivated by detailed arguments. As an illustration we have made quantitative calculations for a semi-infinite jellium with the density of aluminum metal and an embedded atom. The coupling functions (fluctuation potentials) between the electron and the quasibosons are related to the random-phase-approximation dielectric function, and different levels of approximations are evaluated numerically. The differences

  20. Initial condition for efficient mapping of level set algorithms on many-core architectures

    NASA Astrophysics Data System (ADS)

    Tornai, Gábor János; Cserey, György

    2014-12-01

    In this paper, we investigated the effect of adding more small curves to the initial condition which determines the required number of iterations of a fast level set (LS) evolution. As a result, we discovered two new theorems and developed a proof on the worst case of the required number of iterations. Furthermore, we found that these kinds of initial conditions fit well to many-core architectures. To show this, we have included two case studies which are presented on different platforms. One runs on a graphical processing unit (GPU) and the other is executed on a cellular nonlinear network universal machine (CNN-UM). With the new initial conditions, the steady-state solutions of the LS are reached in less than eight iterations depending on the granularity of the initial condition. These dense iterations can be calculated very quickly on many-core platforms according to the two case studies. In the case of the proposed dense initial condition on GPU, there is a significant speedup compared to the sparse initial condition in all cases since our dense initial condition together with the algorithm utilizes the properties of the underlying architecture. Therefore, greater performance gain can be achieved (up to 18 times speedup compared to the sparse initial condition on GPU). Additionally, we have validated our concept against numerically approximated LS evolution of standard flows (mean curvature, Chan-Vese, geodesic active regions). The dice indexes between the fast LS evolutions and the evolutions of the numerically approximated partial differential equations are in the range of 0.99±0.003.

  1. Mercury's core fraction and ancient crustal composition: Predictions from planetary formation under extremely reducing conditions

    NASA Astrophysics Data System (ADS)

    Brown, S. M.; Elkins-Tanton, L.

    2007-12-01

    Several hypotheses have been suggested to explain the paradox of Mercury's large core, which is on the order of sixty percent of the mass of the planet and recently demonstrated to be at least partially molten. Here we suggest that extremely reducing conditions in the earliest stages of planetary accretion nearest to the Sun may have produced the unusual metallic iron fraction by reducing iron otherwise bound into silicates. We demonstrate the formation conditions necessary for various meteoritic bulk compositions to produce the core/mantle ratio of Mercury. During this hypothetical core formation, we assume the remaining silicate fraction of Mercury (now largely lacking iron) has been heated to produce a magma ocean. The resulting cumulate mantle composition is calculated in a Matlab simulation of magma ocean solidification using a CMAS system adapted for Mercury. Plagioclase flotation, frequently cited as the necessary signature of a magma ocean, is highly dependent upon initial bulk composition. We demonstrate the initial silicate iron content of the magma ocean necessary to make plagioclase buoyant and thus produce a plagioclase flotation crust as seen on the Moon. In addition, over a range of bulk compositions the solidified mantle cumulates are unstable to gravitational overturn. During overturn hot cumulates rise from depth and may cross their solidi and melt, producing an earliest planetary crust. This crust may still exist on Mercury. With the first flyby results of the MESSENGER mission coming this winter, predictions from these models can be compared with initial ground measurements.

  2. Liquid iron-sulfur alloys at outer core conditions by first-principles calculations

    NASA Astrophysics Data System (ADS)

    Umemoto, Koichiro; Hirose, Kei; Imada, Saori; Nakajima, Yoichi; Komabayashi, Tetsuya; Tsutsui, Satoshi; Baron, Alfred Q. R.

    2014-10-01

    We perform first-principles calculations to investigate liquid iron-sulfur alloys (Fe, Fe56S8, Fe52S12, and Fe48S16) under high-pressure and high-temperature (150-300 GPa and 4000-6000 K) conditions corresponding to the Earth's outer core. Considering only the density profile, the best match with the preliminary reference Earth model is by liquid Fe-14 wt % S (Fe50S14), assuming sulfur is the only light element. However, its bulk sound velocity is too high, in particular in the deep outer core, suggesting that another light component such as oxygen is required. An experimental check using inelastic X-ray scattering shows good agreement with the calculations. In addition, a present study demonstrates that the Birch's law does not hold for liquid iron-sulfur alloy, consistent with a previous report on pure liquid iron.

  3. Genomic regions associated with the nitrogen limitation response revealed in a global wheat core collection.

    PubMed

    Bordes, Jacques; Ravel, C; Jaubertie, J P; Duperrier, B; Gardet, O; Heumez, E; Pissavy, A L; Charmet, G; Le Gouis, J; Balfourier, F

    2013-03-01

    Modern wheat (Triticum aestivum L.) varieties in Western Europe have mainly been bred, and selected in conditions where high levels of nitrogen-rich fertilizer are applied. However, high input crop management has greatly increased the risk of nitrates leaching into groundwater with negative impacts on the environment. To investigate wheat nitrogen tolerance characteristics that could be adapted to low input crop management, we supplied 196 accessions of a wheat core collection of old and modern cultivars with high or moderate amounts of nitrogen fertilizer in an experimental network consisting of three sites and 2 years. The main breeding traits were assessed including grain yield and grain protein content. The response to nitrogen level was estimated for grain yield and grain number per m(2) using both the difference and the ratio between performance at the two input levels and the slope of joint regression. A large variability was observed for all the traits studied and the response to nitrogen level. Whole genome association mapping was carried out using 899 molecular markers taking into account the five ancestral group structure of the collection. We identified 54 main regions involving almost all chromosomes that influence yield and its components, plant height, heading date and grain protein concentration. Twenty-three regions, including several genes, spread over 16 chromosomes were involved in the response to nitrogen level. These chromosomal regions may be good candidates to be used in breeding programs to improve the performance of wheat varieties at moderate nitrogen input levels. PMID:23192671

  4. 29 CFR Appendix A to Subpart Y of... - Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 8 2013-07-01 2013-07-01 false Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions A Appendix A to Subpart Y of Part 1926 Labor Regulations Relating to Labor... REGULATIONS FOR CONSTRUCTION Diving Pt. 1926, Subpt. Y, App. A Appendix A to Subpart Y of Part...

  5. 29 CFR Appendix A to Subpart Y of... - Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 8 2012-07-01 2012-07-01 false Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions A Appendix A to Subpart Y of Part 1926 Labor Regulations Relating to Labor... REGULATIONS FOR CONSTRUCTION Diving Pt. 1926, Subpt. Y, App. A Appendix A to Subpart Y of Part...

  6. 29 CFR Appendix A to Subpart Y of... - Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions A Appendix A to Subpart Y of Part 1926 Labor Regulations Relating to Labor... REGULATIONS FOR CONSTRUCTION Diving Pt. 1926, Subpt. Y, App. A Appendix A to Subpart Y of Part...

  7. 29 CFR Appendix A to Subpart T of... - Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 5 2014-07-01 2014-07-01 false Examples of Conditions Which May Restrict or Limit Exposure to Hyperbaric Conditions A Appendix A to Subpart T of Part 1910 Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Commercial Diving...

  8. THE INITIAL CONDITIONS OF CLUSTERED STAR FORMATION. III. THE DEUTERIUM FRACTIONATION OF THE OPHIUCHUS B2 CORE

    SciTech Connect

    Friesen, R. K.; Di Francesco, J.; Myers, P. C.; Bourke, T. L.; Belloche, A.; Shirley, Y. L.; Andre, P.

    2010-08-01

    We present N{sub 2}D{sup +} 3-2 (IRAM), and H{sub 2}D{sup +} 1{sub 11}-1{sub 10} and N{sub 2}H{sup +} 4-3 (JCMT) maps of the small cluster-forming Ophiuchus B2 core in the nearby Ophiuchus molecular cloud. In conjunction with previously published N{sub 2}H{sup +} 1-0 observations, the N{sub 2}D{sup +} data reveal the deuterium fractionation in the high-density gas across Oph B2. The average deuterium fractionation R{sub D} = N(N{sub 2}D{sup +})/N(N{sub 2}H{sup +}) {approx} 0.03 over Oph B2, with several small scale R{sub D} peaks and a maximum R{sub D} = 0.1. The mean R{sub D} is consistent with previous results in isolated starless and protostellar cores. The column density distributions of both H{sub 2}D{sup +} and N{sub 2}D{sup +} show no correlation with total H{sub 2} column density. We find, however, an anticorrelation in deuterium fractionation with proximity to the embedded protostars in Oph B2 to distances {approx}>0.04 pc. Destruction mechanisms for deuterated molecules require gas temperatures greater than those previously determined through NH{sub 3} observations of Oph B2 to proceed. We present temperatures calculated for the dense core gas through the equating of non-thermal line widths for molecules (i.e., N{sub 2}D{sup +} and H{sub 2}D{sup +}) expected to trace the same core regions, but the observed complex line structures in B2 preclude finding a reasonable result in many locations. This method may, however, work well in isolated cores with less complicated velocity structures. Finally, we use R{sub D} and the H{sub 2}D{sup +} column density across Oph B2 to set a lower limit on the ionization fraction across the core, finding a mean x{sub e,lim} {approx}> few x 10{sup -8}. Our results show that care must be taken when using deuterated species as a probe of the physical conditions of dense gas in star-forming regions.

  9. Sediment Core Sectioning and Extraction of Pore Waters under Anoxic Conditions.

    PubMed

    Keimowitz, Alison R; Zheng, Yan; Lee, Ming-Kuo; Natter, Michael; Keevan, Jeffrey

    2016-01-01

    We demonstrate a method for sectioning sediment cores and extracting pore waters while maintaining oxygen-free conditions. A simple, inexpensive system is built and can be transported to a temporary work space close to field sampling site(s) to facilitate rapid analysis. Cores are extruded into a portable glove bag, where they are sectioned and each 1-3 cm thick section (depending on core diameter) is sealed into 50 ml centrifuge tubes. Pore waters are separated with centrifugation outside of the glove bag and then returned to the glove bag for separation from the sediment. These extracted pore water samples can be analyzed immediately. Immediate analyses of redox sensitive species, such as sulfide, iron speciation, and arsenic speciation indicate that oxidation of pore waters is minimal; some samples show approximately 100% of the reduced species, e.g. 100% Fe(II) with no detectable Fe(III). Both sediment and pore water samples can be preserved to maintain chemical species for further analysis upon return to the laboratory. PMID:27023267

  10. 26 CFR 54.9801-3 - Limitations on preexisting condition exclusion period.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 17 2012-04-01 2012-04-01 false Limitations on preexisting condition exclusion period. 54.9801-3 Section 54.9801-3 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) MISCELLANEOUS EXCISE TAXES (CONTINUED) PENSION EXCISE TAXES § 54.9801-3 Limitations on preexisting condition exclusion period....

  11. 77 FR 69785 - Public Use Limit on Commercial Dog Walking; Revised Disposal Conditions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-21

    ... Part 1002 Public Use Limit on Commercial Dog Walking; Revised Disposal Conditions AGENCY: The Presidio... a public use limit on persons who are walking four or more dogs at one time in Area B of the Presidio of San Francisco (Presidio) for consideration (Commercial Dog Walkers). The limit will require...

  12. Core conditions for alpha heating attained in direct-drive inertial confinement fusion.

    PubMed

    Bose, A; Woo, K M; Betti, R; Campbell, E M; Mangino, D; Christopherson, A R; McCrory, R L; Nora, R; Regan, S P; Goncharov, V N; Sangster, T C; Forrest, C J; Frenje, J; Gatu Johnson, M; Glebov, V Yu; Knauer, J P; Marshall, F J; Stoeckl, C; Theobald, W

    2016-07-01

    It is shown that direct-drive implosions on the OMEGA laser have achieved core conditions that would lead to significant alpha heating at incident energies available on the National Ignition Facility (NIF) scale. The extrapolation of the experimental results from OMEGA to NIF energy assumes only that the implosion hydrodynamic efficiency is unchanged at higher energies. This approach is independent of the uncertainties in the physical mechanism that degrade implosions on OMEGA, and relies solely on a volumetric scaling of the experimentally observed core conditions. It is estimated that the current best-performing OMEGA implosion [Regan et al., Phys. Rev. Lett. 117, 025001 (2016)10.1103/PhysRevLett.117.025001] extrapolated to a 1.9 MJ laser driver with the same illumination configuration and laser-target coupling would produce 125 kJ of fusion energy with similar levels of alpha heating observed in current highest performing indirect-drive NIF implosions. PMID:27575069

  13. First-principles calculations of properties of orthorhombic iron carbide Fe7C3 at the Earth's core conditions

    NASA Astrophysics Data System (ADS)

    Raza, Zamaan; Shulumba, Nina; Caffrey, Nuala M.; Dubrovinsky, Leonid; Abrikosov, Igor A.

    2015-06-01

    A recently discovered phase of orthorhombic iron carbide o-Fe7C3 [Prescher et al., Nat. Geosci. 8, 220 (2015), 10.1038/ngeo2370] is assessed as a potentially important phase for interpretation of the properties of the Earth's core. In this paper, we carry out first-principles calculations on o-Fe7C3 , finding properties to be in broad agreement with recent experiments, including a high Poisson's ratio (0.38). Our enthalpy calculations suggest that o-Fe7C3 is more stable than Eckstrom-Adcock hexagonal iron carbide (h-Fe7C3 ) below approximately 100 GPa. However, at 150 GPa, the two phases are essentially degenerate in terms of Gibbs free energy, and further increasing the pressure towards Earth's core conditions stabilizes h-Fe7C3 with respect to the orthorhombic phase. Increasing the temperature tends to stabilize the hexagonal phase at 360 GPa, but this trend may change beyond the limit of the quasiharmonic approximation.

  14. Extinction and Reinstatement of Phasic Dopamine Signals in the Nucleus Accumbens Core during Pavlovian Conditioning

    PubMed Central

    Sunsay, Ceyhun; Rebec, George V.

    2014-01-01

    The prediction-error model of dopamine (DA) signaling has largely been confirmed with various appetitive Pavlovian conditioning procedures and has been supported in tests of Pavlovian extinction. Studies have repeatedly shown, however, that extinction does not erase the original memory of conditioning as the prediction-error model presumes, putting the model at odds with contemporary views that treat extinction as an episode of learning rather than unlearning of conditioning. Here, we combined fast-scan cyclic voltammetry (FSCV) with appetitive Pavlovian conditioning to assess DA release directly during extinction and reinstatement. DA was monitored in the nucleus accumbens core (NAc), which plays a key role in reward processing. Following at least 4 daily sessions of 16 tone-food pairings, FSCV was performed while rats received additional tone-food pairings followed by tone alone presentations (i.e., extinction). Acquisition memory was reinstated with non-contingent presentations of reward and then tested with cue presentation. Tone-food pairings produced transient (1–3 s) DA release in response to tone. During extinction, the amplitude of the DA response decreased significantly. Following presentation of two non-contingent food pellets, subsequent tone presentation reinstated the DA signal. Our results support the prediction-error model for appetitive Pavlovian extinction but not for reinstatement. PMID:25111335

  15. Global shielding analysis for the three-element core advanced neutron source reactor under normal operating conditions

    SciTech Connect

    Slater, C.O.; Bucholz, J.A.

    1995-08-01

    Two-dimensional discrete ordinates radiation transport calculations were performed for a model of the three-element core Advanced Neutron Source reactor design under normal operating conditions. The core consists of two concentric upper elements and a lower element radially centered in the annulus between the upper elements. The initial radiation transport calculations were performed with the DORT two-dimensional discrete ordinates radiation transport code using the 39-neutron-group/44-gamma-ray-group ANSL-V cross-section library, an S{sub 6} quadrature, and a P{sub 1} Legendre polynomial expansion of the cross sections to determine the fission neutron source distribution in the core fuel elements. These calculations were limited to neutron groups only. The final radiation transport calculations, also performed with DORT using the 39-neutron-group/44-gamma-ray-group ANSL-V cross-section library, an S{sub l0} quadrature, and a P{sub 3} Legendre polynomial expansion of the cross sections, produced neutron and gamma-ray fluxes over the full extent of the geometry model. Responses (or activities) at various locations in the model were then obtained by folding the appropriate response functions with the fluxes at those locations. Some comparisons were made with VENTURE-calculated (diffusion theory) 20-group neutron fluxes that were summed into four broad groups. Tne results were in reasonably good agreement when the effects of photoneutrons were not included, thus verifying the physics model upon which the shielding model was based. Photoneutrons increased the fast-neutron flux levels deep within the D{sub 2}0 several orders of magnitude. Results are presented as tables of activity values for selected radial and axial traverses, plots of the radial and axial traverse data, and activity contours superimposed on the calculational geometry model.

  16. Preliminary scoping safety analyses of the limiting design basis protected accidents for the Fast Flux Test Facility tritium production core

    SciTech Connect

    Heard, F.J.

    1997-11-19

    The SAS4A/SASSYS-l computer code is used to perform a series of analyses for the limiting protected design basis transient events given a representative tritium and medical isotope production core design proposed for the Fast Flux Test Facility. The FFTF tritium and isotope production mission will require a different core loading which features higher enrichment fuel, tritium targets, and medical isotope production assemblies. Changes in several key core parameters, such as the Doppler coefficient and delayed neutron fraction will affect the transient response of the reactor. Both reactivity insertion and reduction of heat removal events were analyzed. The analysis methods and modeling assumptions are described. Results of the analyses and comparison against fuel pin performance criteria are presented to provide quantification that the plant protection system is adequate to maintain the necessary safety margins and assure cladding integrity.

  17. VLBI limits on the proper motion of the 'core' of the superluminal quasar 3C345

    NASA Technical Reports Server (NTRS)

    Bartel, N.; Herring, T. A.; Ratner, M. I.; Shapiro, I. I.; Corey, B. E.

    1986-01-01

    VLBI (very-long-baseline interferometry) observations between 1971 and 1983 have been used to determine the positions of the 'core' of the quasar 3C345 relative to the more distant compact quasar NRAO512 with a fractional uncertainty as small as two parts in a hundred million. The core of 3C345 appears stationary in right ascension to within 20 arc microsec/yr, a subluminal bound corresponding to 0.7c. The apparent velocities of the jets are superluminal, up to 14c in magnitude.

  18. Partitioning of Phosphorus and Molybdenum between the Earth's Mantle and Core and the Conditions of Core Formation

    NASA Technical Reports Server (NTRS)

    Acuff, K. M.; Danielson, L.; Righter, K.; Lee, C. T.

    2008-01-01

    There are several hypotheses on the specific processes that might have occurred during the formation of the Earth. One hypothesis that has been proposed is that early in the Earth's formation, there was a magma ocean present, and within this body, siderophile elements separated out of the silicate liquid to form the metal core. This study addresses this hypothesis. P and Mo are moderately siderophile elements that are present in both the mantle and the core. The concentrations of P and Mo in silicate vs. metal can be measured and in turn used to determine the temperatures, pressures, oxygen fugacity and melt composition required to achieve the same concentrations as observed in the mantle. The data here include eight experiments examining the partitioning of P and Mo between metallic liquid and silicate liquid. The purpose of the experiments has been to gain a greater understanding of core-mantle separation during the Earth formation process and examines temperature effect on P and Mo, which has not been systematically studied before.

  19. Development of the BWR Dry Core Initial and Boundary Conditions for the SNL XR2 Experiments

    SciTech Connect

    Ott, L.J.

    1994-01-01

    The objectives of the Boiling Water Reactor Experimental Analysis and Model Development for Severe Accidents (BEAMD) Program at the Oak Ridge National Laboratory (ORNL) are: (1) the development of a sound quantitative understanding of boiling water reactor (BWR) core melt progression; this includes control blade and channel box effects, metallic melt relocation and possible blockage formation under severe accident conditions, and (2) provision of BWR melt progression modeling capabilities in SCDAP/RELAP5 (consistent with the BWR experimental data base). This requires the assessment of current modeling of BWR core melt progression against the expanding BWR data base. Emphasis is placed upon data from the BWR tests in the German CORA test facility and from the ex-reactor experiments [Sandia National Laboratories (SNL)] on metallic melt relocation and blockage formation in BWRs, as well as upon in-reactor data from the Annular Core Research Reactor (ACRR) DF-4 BWR test (conducted in 1986 at SNL). The BEAMD Program is a derivative of the BWR Severe Accident Technology Programs at ORNL. The ORNL BWR programs have studied postulated severe accidents in BWRs and have developed a set of models specific to boiling water reactor response under severe accident conditions. These models, in an experiment-specific format, have been successfully applied to both pretest and posttest analyses of the DF-4 experiment, and the BWR severe fuel damage (SFD) experiments performed in the CORA facility at the Kernforschungszentrum Karlsruhe (KfK) in Germany, resulting in excellent agreement between model prediction and experiment. The ORNL BWR models have provided for more precise predictions of the conditions in the BWR experiments than were previously available. This has provided a basis for more accurate interpretation of the phenomena for which the experiments are performed. The experiment-specific models, as used in the ORNL DF-4 and CORA BWR experimental analyses, also provide a

  20. Phase stability limit of c-BN under hydrostatic and non-hydrostatic pressure conditions

    SciTech Connect

    Xiao, Jianwei; Du, Jinglian; Wen, Bin Zhang, Xiangyi; Melnik, Roderick; Kawazoe, Yoshiyuki

    2014-04-28

    Phase stability limit of cubic boron nitride (c-BN) has been investigated by the crystal structure search technique. It indicated that this limit is ∼1000 GPa at hydrostatic pressure condition. Above this pressure, c-BN turns into a metastable phase with respect to rocksalt type boron nitride (rs-BN). However, rs-BN cannot be retained at 0 GPa owing to its instability at pressure below 250 GPa. For non-hydrostatic pressure conditions, the phase stability limit of c-BN is substantially lower than that under hydrostatic pressure conditions and it is also dramatically different for other pressure mode.

  1. Constraints on Earth's inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions.

    PubMed

    Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q R

    2016-02-01

    Hexagonal close-packed iron (hcp-Fe) is a main component of Earth's inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density-sound velocity data of Earth's core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (V P) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch's law for hcp-Fe, which gives us the V P of pure hcp-Fe up to core conditions. We find that Earth's inner core has a 4 to 5% smaller density and a 4 to 10% smaller V P than hcp-Fe. Our results demonstrate that components other than Fe in Earth's core are required to explain Earth's core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth's core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect. PMID:26933678

  2. Chronologies of marine sediment cores during the Last Interglacial: strengths and limitations of commonly used climato-stratigraphic alignments

    NASA Astrophysics Data System (ADS)

    Govin, Aline; Capron, Emilie

    2015-04-01

    The Last Interglacial (LIG, ~129-116 thousand of years, ka) is relatively well documented in marine sediment cores retrieved across the globe. However, these records exhibit very few absolute age markers such as magnetic events and dated tephra layers, which limits the definition of independent and precise LIG age models. As a result, age models of marine sediments are defined using various methods based on the (i) synchronisation or (ii) climato-stratigraphic alignment of marine records to dated "reference" records, assuming simultaneous regional changes for a given climate variable (e.g. foraminiferal δ18O, temperature). The use of different "reference" chronologies (e.g. LR04, speleothem or ice core chronologies) also limits a precise investigation of climatic sequences across the LIG. Here, we evaluate the underlying hypotheses, strengths and limitations, and age uncertainties of methods commonly used in marine sediments during the LIG: i.e. benthic δ18O alignment to the LR04 benthic δ18O stack, temperature alignment to ice core or to speleothem records. We compare the resulting age models using examples from the North Atlantic core MD95-2042 and the Southern Ocean core MD02-2488. We show a lack of remarkable tie-points within the LIG, which limits the study of the sub-millennial-scale climate variability. We also report age offsets up to 4 ka when different reference chronologies (e.g. ice cores vs. speleothems) or different types of aligned records (e.g. SST vs. planktonic δ18O) are used. These results highlight the need for careful estimates of age uncertainties when defining age models in marine sediments. They also emphasize the fact that LIG chronologies should be considered with care. A clear statement on the reference chronology, the method of alignment and the type of tracers that are used should be given when investigating the LIG sequence of climatic events from various sediment cores or when comparing LIG marine records and climate model

  3. Elevated-Temperature Tests Under Static and Aerodynamic Conditions on Honeycomb-Core Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Groen, Joseph M.; Johnson, Aldie E., Jr.

    1959-01-01

    Stainless-steel honeycomb-core sandwich panels which differed primarily in skin thicknesses were tested at elevated temperatures under static and aerodynamic conditions. The results of these tests were evaluated to determine the insulating effectiveness and structural integrity of the panels. The static radiant-heating tests were performed in front of a quartz-tube radiant heater at panel skin temperatures up to 1,5000 F. The aerodynamic tests were made in a Mach 1.4 heated blowdown wind tunnel. The tunnel temperature was augmented by additional heat supplied by a radiant heater which raised the panel surface temperature above 8000 F during air flow. Static radiant-heating tests of 2 minutes duration showed that all the panels protected the load-carrying structure about equally well. Thin-skin panels showed an advantage for this short-time test over thick-skin panels from a standpoint of weight against insulation. Permanent inelastic strains in the form of local buckles over each cell of the honeycomb core caused an increase in surface roughness. During the aero- dynamic tests all of the panels survived with little or no damage, and panel flutter did not occur.

  4. Dynamical stability of body center cubic iron at the Earth’s core conditions

    PubMed Central

    Luo, Wei; Johansson, Börje; Eriksson, Olle; Arapan, Sergiu; Souvatzis, Petros; Katsnelson, Mikhail I.; Ahuja, Rajeev

    2010-01-01

    Here, using self-consistent ab initio lattice dynamical calculations that go beyond the quasiharmonic approximation, we show that the high-pressure high-temperature bcc-Fe phase is dynamically stable. In this treatment the temperature-dependent phonon spectra are derived by exciting all the lattice vibrations, in which the phonon–phonon interactions are considered. The high-pressure and high-temperature bcc-Fe phase shows standard bcc-type phonon dispersion curves except for the transverse branch, which is overdamped along the high symmetry direction Γ-N, at temperatures below 4,500 K. When lowering the temperature down to a critical value TC, the lattice instability of the bcc structure is reached. The pressure dependence of this critical temperature is studied at conditions relevant for the Earth’s core. PMID:20479276

  5. Real-Time Dopamine Efflux in the Nucleus Accumbens Core During Pavlovian Conditioning

    PubMed Central

    Sunsay, Ceyhun; Rebec, George V.

    2009-01-01

    To assess the role of dopamine input to the nucleus accumbens core in anticipatory learning, fast-scan cyclic voltammetry was combined with appetitive Pavlovian conditioning. One group of rats (Paired) received 16 tone-food pairings for at least four daily sessions while the control group (Unpaired) received the same number of unpaired tone and food presentations. Both groups showed transient dopamine responses during food presentation throughout training, confirming dopamine involvement in reward processing. Only the Paired Group, however, showed consistently timed dopamine transients during the 10-s tone presentation. Transients first appeared near the end of the tone period as each animal acquired the tone-food association and then occurred progressively sooner on subsequent sessions. Later sessions also revealed a consistently timed dopamine response soon after food delivery in Paired animals. Collectively, these results implicate phasic dopamine release in the acquisition of Pavlovian learning and also suggest an early dopamine response to the unconditioned stimulus as training continues. PMID:18410174

  6. On the body centered structure of iron at Earth Core Conditions

    NASA Astrophysics Data System (ADS)

    Jeanloz, R.; Stixrude, L.; Verma, A.; Modak, P.; Godwal, B.

    2007-12-01

    The stability of the body-centered cubic (bcc) phase of iron is considered at Earth-core conditions (V = 7.2 Å3, T = 5500 K) by way of ab-initio molecular-dynamics simulations and electronic-structure calculations using the density-functional approach. Tetragonal strain splits a peak in the electronic density of states at the Fermi level, lowering the energy of the structure with distortion and therefore documenting the metastability of the bcc structure. As temperature is increased from zero to 5500 K, the bcc structure satisfies the condition of hydrostaticity, with vanishing of stress anisotropy, but it remains energetically unstable with respect to the tetragonal distortion; an increase in elastic anisotropy is documented with increasing tetragonal strain. An energy minimum is observed around c/a = 0.9 in a Bain-path plot, and has previously been interpreted as evidence of an elastically-stable body-centered tetragonal (bct) structure. However, we find from static total-energy calculations as a function of b/a and c/a that this is a local minimum in energy corresponding to a metastable structure. Analysis of the structure with tetragonal strain reveals the presence of anomalous shear stresses that, coupled with phonon instability, suggest a tendency toward formation of a hexagonal closed-packed (hcp) structure. Overall, these results argue against bcc or even bct structures of Fe being present in Earth's core, and instead highlight the importance of the known hcp (ɛ) high-pressure phase of iron.

  7. Investigation of fatty acid accumulation in the engineered Saccharomyces cerevisiae under nitrogen limited culture condition.

    PubMed

    Tang, Xiaoling; Chen, Wei Ning

    2014-06-01

    In this study, the Saccharomyces cerevisiae wild type strain and engineered strain with an overexpressed heterologous ATP-citrate lyase (acl) were cultured in medium with different carbon and nitrogen concentrations, and their fatty acid production levels were investigated. The results showed that when the S. cerevisiae engineered strain was cultivated under nitrogen limited culture condition, the yield of mono-unsaturated fatty acids showed higher than that under non-nitrogen limited condition; with the carbon concentration increased, the accumulation become more apparent, whereas in the wild type strain, no such correlation was found. Besides, the citrate level in the S. cerevisiae under nitrogen limited condition was found to be much higher than that under non-nitrogen limited condition, which indicated a relationship between the diminution of nitrogen and accumulation of citrate in the S. cerevisiae. The accumulated citrate could be further cleaved by acl to provide substrate for fatty acid synthesis. PMID:24755317

  8. Effectiveness and limitations of core needle biopsy in the diagnosis of thyroid nodules: review of current literature.

    PubMed

    Yoon, Jung Hyun; Kim, Eun-Kyung; Kwak, Jin Young; Moon, Hee Jung

    2015-05-01

    Fine needle aspiration (FNA) is currently accepted as an easy, safe, and reliable tool for the diagnosis of thyroid nodules. Nonetheless, a proportion of FNA samples are categorized into non-diagnostic or indeterminate cytology, which frustrates both the clinician and patient. To overcome this limitation of FNA, core needle biopsy (CNB) of the thyroid has been proposed as an additional diagnostic method for more accurate and decisive diagnosis for thyroid nodules of concern. In this review, we focus on the effectiveness and limitations of CNB, and what factors should be considered when CNB is utilized in the diagnosis of thyroid nodules. PMID:26018514

  9. 76 FR 25648 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-05

    .... These proposed special conditions pertain to their effects on the structural performance of the airplane... load imposed by sudden engine stoppage due to malfunction or structural failure.'' Limit loads are... structures be able to support limit loads without detrimental permanent deformation, meaning that...

  10. 78 FR 6273 - Public Use Limit on Commercial Dog Walking; Revised Disposal Conditions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-30

    ... proposed rule published November 21, 2012 (77 FR 69785-69788) is extended. Comments are due February 25... Part 1002 Public Use Limit on Commercial Dog Walking; Revised Disposal Conditions AGENCY: The Presidio... requesting public comment on a proposed public use limit on persons who are walking four or more dogs at...

  11. Design criteria for a self-actuated shutdown system to ensure limitation of core damage. [LMFBR

    SciTech Connect

    Deane, N.A.; Atcheson, D.B.

    1981-09-01

    Safety-based functional requirements and design criteria for a self-actuated shutdown system (SASS) are derived in accordance with LOA-2 success criteria and reliability goals. The design basis transients have been defined and evaluated for the CDS Phase II design, which is a 2550 MWt mixed oxide heterogeneous core reactor. A partial set of reactor responses for selected transients is provided as a function of SASS characteristics such as reactivity worth, trip points, and insertion times.

  12. Canadian Society for Exercise Physiology position stand: The use of instability to train the core in athletic and nonathletic conditioning.

    PubMed

    Behm, David G; Drinkwater, Eric J; Willardson, Jeffrey M; Cowley, Patrick M

    2010-02-01

    The use of instability devices and exercises to train the core musculature is an essential feature of many training centres and programs. It was the intent of this position stand to provide recommendations regarding the role of instability in resistance training programs designed to train the core musculature. The core is defined as the axial skeleton and all soft tissues with a proximal attachment originating on the axial skeleton, regardless of whether the soft tissue terminates on the axial or appendicular skeleton. Core stability can be achieved with a combination of muscle activation and intra-abdominal pressure. Abdominal bracing has been shown to be more effective than abdominal hollowing in optimizing spinal stability. When similar exercises are performed, core and limb muscle activation are reported to be higher under unstable conditions than under stable conditions. However, core muscle activation that is similar to or higher than that achieved in unstable conditions can also be achieved with ground-based free-weight exercises, such as Olympic lifts, squats, and dead lifts. Since the addition of unstable bases to resistance exercises can decrease force, power, velocity, and range of motion, they are not recommended as the primary training mode for athletic conditioning. However, the high muscle activation with the use of lower loads associated with instability resistance training suggests they can play an important role within a periodized training schedule, in rehabilitation programs, and for nonathletic individuals who prefer not to use ground-based free weights to achieve musculoskeletal health benefits. PMID:20130673

  13. 42 CFR 410.23 - Screening for glaucoma: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Screening for glaucoma: Conditions for and... Medical and Other Health Services § 410.23 Screening for glaucoma: Conditions for and limitations on... mellitus. (ii) Individual with a family history of glaucoma. (iii) African-Americans age 50 and over....

  14. 42 CFR 410.23 - Screening for glaucoma: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Screening for glaucoma: Conditions for and... Medical and Other Health Services § 410.23 Screening for glaucoma: Conditions for and limitations on... mellitus. (ii) Individual with a family history of glaucoma. (iii) African-Americans age 50 and over....

  15. 42 CFR 410.23 - Screening for glaucoma: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Screening for glaucoma: Conditions for and... Medical and Other Health Services § 410.23 Screening for glaucoma: Conditions for and limitations on... mellitus. (ii) Individual with a family history of glaucoma. (iii) African-Americans age 50 and over....

  16. 42 CFR 410.23 - Screening for glaucoma: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Screening for glaucoma: Conditions for and... Medical and Other Health Services § 410.23 Screening for glaucoma: Conditions for and limitations on... mellitus. (ii) Individual with a family history of glaucoma. (iii) African-Americans age 50 and over....

  17. 42 CFR 410.23 - Screening for glaucoma: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Screening for glaucoma: Conditions for and... Medical and Other Health Services § 410.23 Screening for glaucoma: Conditions for and limitations on...) Hispanic-Americans age 65 and over. (3) Screening for glaucoma means the following procedures furnished...

  18. 42 CFR 410.39 - Prostate cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Prostate cancer screening tests: Conditions for and... Medical and Other Health Services § 410.39 Prostate cancer screening tests: Conditions for and limitations... cancer screening tests means any of the following procedures furnished to an individual for the...

  19. 42 CFR 410.39 - Prostate cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Prostate cancer screening tests: Conditions for and... Medical and Other Health Services § 410.39 Prostate cancer screening tests: Conditions for and limitations... cancer screening tests means any of the following procedures furnished to an individual for the...

  20. 42 CFR 410.39 - Prostate cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Prostate cancer screening tests: Conditions for and... Medical and Other Health Services § 410.39 Prostate cancer screening tests: Conditions for and limitations... cancer screening tests means any of the following procedures furnished to an individual for the...

  1. 42 CFR 410.39 - Prostate cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Prostate cancer screening tests: Conditions for and... Medical and Other Health Services § 410.39 Prostate cancer screening tests: Conditions for and limitations... cancer screening tests means any of the following procedures furnished to an individual for the...

  2. 42 CFR 410.39 - Prostate cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Prostate cancer screening tests: Conditions for and... Medical and Other Health Services § 410.39 Prostate cancer screening tests: Conditions for and limitations... cancer screening tests means any of the following procedures furnished to an individual for the...

  3. Conditional cooling limit for a quantum channel going through an incoherent environment

    PubMed Central

    Straka, Ivo; Miková, Martina; Mičuda, Michal; Dušek, Miloslav; Ježek, Miroslav; Filip, Radim

    2015-01-01

    We propose and experimentally verify a cooling limit for a quantum channel going through an incoherent environment. The environment consists of a large number of independent non-interacting and non-interfering elementary quantum systems – qubits. The qubits travelling through the channel can only be randomly replaced by environmental qubits. We investigate a conditional cooling limit that exploits an additional probing output. The limit specifies when the single-qubit channel is quantum, i.e. it preserves entanglement. It is a fundamental condition for entanglement-based quantum technology. PMID:26568362

  4. Measurement of a tree growth condition by the hetero-core optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Uchida, Hoshito; Akita, Shohei; Nishiyama, Michiko; Kumekawa, Norikazu; Watanabe, Kazuhiro

    2011-04-01

    Condition and growth of trees are considered to be important in monitoring global circulation with heat and water, additionally growth of trees are affected by CO2 and air pollutants. On the other hand, since growth of plants is affected by surrounding climates, it is expected that real-time monitoring of crop plants growing makes possible quantitative agricultural management. This study proposed methods in measuring tree growth using hetero-core optical fiber sensors which are suitable for long-term, remote and real-time monitoring in wide area due to their features such as independence from temperature fluctuation and weather condition in addition to advantages of an optical fiber. Two types of sensors were used for that purpose. One of them was a dendrometer which measured radial changes of a tree stem and the other was elastic sensor which was to measure growth of smaller tree such as crop plant. In our experiment, it was demonstrated that the dendrometer was capable of measuring the differences of tree growing trend in period of different seasons such as growing rates 2.08 mm between spring and summer and 0.21 mm between autumn and winter, respectively. Additionally, this study had proposed the method of measuring crop plant growing by the elastic sensor because of its compact and light design and monotonious changes in optical loss to the amount of expansion and contraction.

  5. Transport of bromide measured by soil coring, suction plates, and lysimeters under transient flow conditions.

    NASA Astrophysics Data System (ADS)

    Kasteel, R.; Pütz, Th.; Vereecken, H.

    2003-04-01

    Lysimeter studies are one step within the registration procedure of pesticides. Flow and transport in these free-draining lysimeters do not reflect the field situation mainly because of the occurence of a zone of local saturation at the lower boundary (seepage face). The objective of this study is to evaluate the impact of flow and transport behaviour of bromide detected with different measuring devices (lysimeters, suction plates, and soil coring) by comparing experimental results with numerical simulations in heterogeneous flow domains. We applied bromide as a small pulse to the bare soil surface (Orthic Luvisol) of the three devices and the displacement of bromide was regurlarly sampled for three years under natural wheather conditions. Based on the mean breakthrough curves we observe experimentally that lysimeters have a lower effective pore-water velocity and exhibit more solute spreading resulting in a larger dispersivity than the suction plates. This can be ascribed to the artefact of the lower boundary. We performed numerical transport simulations in 2-D heterogeneous flow fields (scaling approach) choosing appropriate boundary conditions for the various devices. The simulations allow to follow the temporal evolution of flow and transport processes in the various devices and to gain additional process understanding. We conclude that the model is essentially capable to reproduce the main experimental findings only if we account for the spatial correlation structure of the hydraulic properties, i.e. soil heterogeneity.

  6. Reservoir condition special core analyses and relative permeability measurements on Almond formation and Fontainebleu sandstone rocks

    SciTech Connect

    Maloney, D.

    1993-11-01

    This report describes the results from special core analyses and relative permeability measurements conducted on Almond formation and Fontainebleu sandstone plugs. Almond formation plug tests were performed to evaluate multiphase, steady-state,reservoir-condition relative permeability measurement techniques and to examine the effect of temperature on relative permeability characteristics. Some conclusions from this project are as follows: An increase in temperature appeared to cause an increase in brine relative permeability results for an Almond formation plug compared to room temperature results. The plug was tested using steady-state oil/brine methods. The oil was a low-viscosity, isoparaffinic refined oil. Fontainebleu sandstone rock and fluid flow characteristics were measured and are reported. Most of the relative permeability versus saturation results could be represented by one of two trends -- either a k{sub rx} versus S{sub x} or k{sub rx} versus Sy trend where x and y are fluid phases (gas, oil, or brine). An oil/surfactant-brine steady-state relative permeability test was performed to examine changes in oil/brine relative permeability characteristics from changes in fluid IFTS. It appeared that, while low interfacial tension increased the aqueous phase relative permeability, it had no effect on the oil relative permeability. The BOAST simulator was modified for coreflood simulation. The simulator was useful for examining effects of variations in relative permeability and capillary pressure functions. Coreflood production monitoring and separator interface level measurement techniques were developed using X-ray absorption, weight methods, and RF admittance technologies. The three types of separators should be useful for routine and specialized core analysis applications.

  7. Atmospheric synoptic conditions of snow precipitation in East Antarctica using ice core and reanalysis data

    NASA Astrophysics Data System (ADS)

    Scarchilli, Claudio; Ciardini, Virginia; Bonazza, Mattia; Frezzotti, Massimo; Stenni, Barbara

    2014-05-01

    In the framework of the International Partnerships in Ice Core Sciences (IPCS) initiatives the GV7 site (70°41' S - 158°51' E) in East Antarctica was chosen as the new drilling site for the Italian contribution to the understanding of the climatic variability in the last 2000 years (IPICS 2k Array). Water stable isotopes and snow accumulation (SMB) values from a shallow firn core, obtained at GV7 during the 2001-2002 International Trans-Antarctic Scientific Expedition (ITASE) traverse, are analyzed and compared with different meteorological model output in order to characterize the atmospheric synoptic conditions driving precipitation events at the site. On annual basis, ECMWF +24h forecasted snowfalls (SF) seem to well reproduce GV7 SMB values trend for the period from 1980 to 2005. Calculated air mass back-trajectories show that Eastern Indian - Western Pacific oceans represent the main moisture path toward the site during autumn - winter season. Analysis of the ECMWF 500 hPa Geopotential height field (GP500) anomalies shows that atmospheric blocking events developing between 130° E and 150° W at high latitudes drive the GV7 SMB by blocking zonal flow and conveying warm and moist deep air masses from ocean into the continental interior. On inter-annual basis, The SF variability over GV7 region follows the temporal oscillation of the third CEOF mode (CEOF3 10% of the total explained variance) of a combined complex empirical orthogonal function (CEOF) performed over GP500 and SF field. The CEOF3 highlights an oscillating feature, with wavenumber 2, in GP500 field over the Western Pacific-Eastern Indian Oceans and propagating westward. The pattern is deeply correlated with the Indian Dipole Oscillation and ENSO and their associated quasi-stationary Rossby waves propagating from the lower toward the higher latitudes.

  8. Optical harmonic generation in hollow-core photonic-crystal fibres: analysis of optical losses and phase-matching conditions

    SciTech Connect

    Naumov, A N; Zheltikov, Aleksei M

    2002-02-28

    We consider hollow-core fibres with a microstructure photonic-crystal cladding, which open a unique opportunity of implementing nonlinear-optical interactions of waveguide modes with transverse sizes on the order of several microns in the gas phase. Phase-matching conditions for optical harmonic generation can be improved in higher waveguide modes of hollow-core photonic-crystal fibres by optimising parameters of the gas medium filling the fibre and characteristics of the fibre. (optical fibres)

  9. Reducing Conservatism in Aircraft Engine Response Using Conditionally Active Min-Max Limit Regulators

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Garg, Sanjay

    2012-01-01

    Current aircraft engine control logic uses a Min-Max control selection structure to prevent the engine from exceeding any safety or operational limits during transients due to throttle commands. This structure is inherently conservative and produces transient responses that are slower than necessary. In order to utilize the existing safety margins more effectively, a modification to this architecture is proposed, referred to as a Conditionally Active (CA) limit regulator. This concept uses the existing Min-Max architecture with the modification that limit regulators are active only when the operating point is close to a particular limit. This paper explores the use of CA limit regulators using a publicly available commercial aircraft engine simulation. The improvement in thrust response while maintaining all necessary safety limits is demonstrated in a number of cases.

  10. Sulfur Saturation Limits in Silicate Melts and their Implications for Core Formation Scenarios for Terrestrial Planets

    NASA Technical Reports Server (NTRS)

    Holzheid, Astrid; Grove, Timothy L.

    2002-01-01

    This study explores the controls of temperature, pressure, and silicate melt composition on S solubility in silicate liquids. The solubility of S in FeO-containing silicate melts in equilibrium with metal sulfide increases significantly with increasing temperature but decreases with increasing pressure. The silicate melt structure also exercises a control on S solubility. Increasing the degree of polymerization of the silicate melt structure lowers the S solubility in the silicate liquid. The new set of experimental data is used to expand the model of Mavrogenes and O'Neill(1999) for S solubility in silicate liquids by incorporating the influence of the silicate melt structure. The expected S solubility in the ascending magma is calculated using the expanded model. Because the negative pressure dependence of S solubility is more influential than the positive temperature dependence, decompression and adiabatic ascent of a formerly S-saturated silicate magma will lead to S undersaturation. A primitive magma that is S-saturated in its source region will, therefore, become S-undersaturated as it ascends to shallower depth. In order to precipitate magmatic sulfides, the magma must first cool and undergo fractional crystallization to reach S saturation. The S content in a metallic liquid that is in equilibrium with a magma ocean that contains approx. 200 ppm S (i.e., Earth's bulk mantle S content) ranges from 5.5 to 12 wt% S. This range of S values encompasses the amount of S (9 to 12 wt%) that would be present in the outer core if S is the light element. Thus, the Earth's proto-mantle could be in equilibrium (in terms of the preserved S abundance) with a core-forming metallic phase.

  11. Fate of MgSiO3 melts at core-mantle boundary conditions.

    PubMed

    Petitgirard, Sylvain; Malfait, Wim J; Sinmyo, Ryosuke; Kupenko, Ilya; Hennet, Louis; Harries, Dennis; Dane, Thomas; Burghammer, Manfred; Rubie, Dave C

    2015-11-17

    One key for understanding the stratification in the deep mantle lies in the determination of the density and structure of matter at high pressures, as well as the density contrast between solid and liquid silicate phases. Indeed, the density contrast is the main control on the entrainment or settlement of matter and is of fundamental importance for understanding the past and present dynamic behavior of the deepest part of the Earth's mantle. Here, we adapted the X-ray absorption method to the small dimensions of the diamond anvil cell, enabling density measurements of amorphous materials to unprecedented conditions of pressure. Our density data for MgSiO3 glass up to 127 GPa are considerably higher than those previously derived from Brillouin spectroscopy but validate recent ab initio molecular dynamics simulations. A fourth-order Birch-Murnaghan equation of state reproduces our experimental data over the entire pressure regime of the mantle. At the core-mantle boundary (CMB) pressure, the density of MgSiO3 glass is 5.48 ± 0.18 g/cm(3), which is only 1.6% lower than that of MgSiO3 bridgmanite at 5.57 g/cm(3), i.e., they are the same within the uncertainty. Taking into account the partitioning of iron into the melt, we conclude that melts are denser than the surrounding solid phases in the lowermost mantle and that melts will be trapped above the CMB. PMID:26578761

  12. Dependence of polarization mode dispersion of slotted core NZDF ribbon on cable design and environmental conditions

    NASA Astrophysics Data System (ADS)

    Karlik, Sait Eser; Yilmaz, Gunes

    2006-09-01

    Non-zero dispersion fiber (NZDF) ribbon cable has recently become a considerable alternative in long-haul high-speed network construction. Since long-distance high-bit rate transmission requires low polarization mode dispersion (PMD), it is very important to know the PMD performance of this type of optical fiber cables. In this paper, we report experimental analysis of effects of the cable design and environmental parameters, in particular ribbon thickness, positions of fibers in the ribbon, flexing and vibration, on PMD performances of several slotted-core fiber ribbon cables. Results show that ribbon thickness and positions of fibers in the ribbon alter the PMD values of NZDF ribbon cables. Also, 23% and 11% PMD variations have been determined in flexing and vibration experiments, respectively. Moreover, it has been observed that vibration amplitude has significant effects and vibration frequency has little effects (14% and 6% variations, respectively) on fiber PMD. Results are important for understanding effects of installation conditions and wind, especially for aerial fibers, on PMD values of cables.

  13. Microstructure evolution in proton-irradiated austenitic Fe-Cr-Ni alloys under LWR core conditions

    NASA Astrophysics Data System (ADS)

    Gan, Jian

    1999-11-01

    Irradiation-induced microstructure of austenitic stainless steel was investigated using proton irradiation. High-purity alloys of Fe-20Cr-9Ni (UHP 304 SS), Fe-20Cr-24Ni and Ni-18Cr-9Fe were irradiated using 3.2 MeV protons at a dose rate of 7 × 10-6 dpa/s between 300°C and 600°C. The irradiation produced a microstructure consisting of dislocation loops and voids. The dose and temperature dependence of the number density and size of dislocation loops and voids were investigated. The changes in yield strength due to irradiation were estimated from Vickers hardness measurements and compared to calculations using a dispersed-barrier hardening model. The dose and temperature dependence of microstructure and hardness change for proton irradiation follows the same trend as that for neutron irradiation at comparable irradiation conditions. Commercial purity alloys of CP 304 SS and CP 316 SS were irradiated at 360°C to doses between 0.3 and 3.0 dpa. The irradiated microstructure consists of dislocation loops. No voids were detected at doses up to 3.0 dpa. Loop size distributions are in close agreement with that in the same alloys neutron-irradiated in a LWR core. The loop density also agrees with neutron irradiation data. The yield strength as a function of dose in proton irradiated commercial purity alloys is consistent with the neutron- data trend. A fast-reactor microstructure model was adapted for light water reactor (LWR) irradiation conditions (275°C, 7 × 10 -8 dpa/s) and then applied to proton irradiation under conditions (360°C, 7 × 10-6 dpa/s) relevant to LWRs. The original model was modified by including in-cascade interstitial clustering and the loss of interstitial clusters to sinks by cluster diffusion. It was demonstrated that loop nucleation for both LWR irradiation condition and proton irradiation are driven by in-cascade interstitial clustering. One important result from this modeling work is that the difference in displacement cascade between

  14. Electronic correlations in Fe at Earth's inner core conditions: Effects of alloying with Ni

    NASA Astrophysics Data System (ADS)

    Vekilova, O. Yu.; Pourovskii, L. V.; Abrikosov, I. A.; Simak, S. I.

    2015-06-01

    We have studied the body-centered cubic (bcc), face-centered cubic (fcc), and hexagonal close-packed (hcp) phases of Fe alloyed with 25 at.% of Ni at Earth's core conditions using an ab initio local density approximation + dynamical mean-field theory approach. The alloys have been modeled by ordered crystal structures based on the bcc, fcc, and hcp unit cells with the minimum possible cell size allowing for the proper composition. Our calculations demonstrate that the strength of electronic correlations on the Fe 3 d shell is highly sensitive to the phase and local environment. In the bcc phase, the 3 d electrons at the Fe site with Fe only nearest neighbors remain rather strongly correlated, even at extreme pressure-temperature conditions, with the local and uniform magnetic susceptibility exhibiting a Curie-Weiss-like temperature evolution and the quasiparticle lifetime Γ featuring a non-Fermi-liquid temperature dependence. In contrast, for the corresponding Fe site in the hcp phase, we predict a weakly correlated Fermi-liquid state with a temperature-independent local susceptibility and a quadratic temperature dependence of Γ. The iron sites with nickel atoms in the local environment exhibit behavior in the range between those two extreme cases, with the strength of correlations gradually increasing along the hcp-fcc-bcc sequence. Further, the intersite magnetic interactions in the bcc and hcp phases are also strongly affected by the presence of Ni nearest neighbors. The sensitivity to the local environment is related to modifications of the Fe partial density of states due to mixing with Ni 3 d states.

  15. A new 10Be record recovered from an Antarctic ice core: validity and limitations to record the solar activity

    NASA Astrophysics Data System (ADS)

    Baroni, Mélanie; Bard, Edouard; Aster Team

    2015-04-01

    Cosmogenic nuclides provide the only possibility to document solar activity over millennia. Carbon-14 (14C) and beryllium-10 (10Be) records are retrieved from tree rings and ice cores, respectively. Recently, 14C records have also proven to be reliable to detect two large Solar Proton Events (SPE) (Miyake et al., Nature, 2012, Miyake et al., Nat. Commun., 2013) that occurred in 774-775 A.D. and in 993-994 A.D.. The origin of these events is still under debate but it opens new perspectives for the interpretation of 10Be ice core records. We present a new 10Be record from an ice core from Dome C (Antarctica) covering the last millennium. The chronology of this new ice core has been established by matching volcanic events on the WAIS Divide ice core (WDC06A) that is the best dated record in Antarctica over the Holocene (Sigl et al., JGR, 2013, Sigl et al., Nat. Clim. Change, 2014). The five minima of solar activity (Oort, Wolf, Spörer, Maunder and Dalton) are detected and characterized by a 10Be concentration increase of ca. 20% above average in agreement with previous studies of ice cores drilled at South Pole and Dome Fuji in Antarctica (Bard et al., EPSL, 1997; Horiuchi et al., Quat. Geochrono., 2008) and at NGRIP and Dye3 in Greenland (Berggren et al., GRL, 2009). The high resolution, on the order of a year, allows the detection of the 11-year solar cycle. Sulfate concentration, a proxy for volcanic eruptions, has also been measured in the very same samples, allowing a precise comparison of both 10Be and sulfate profiles. We confirm the systematic relationship between stratospheric eruptions and 10Be concentration increases, first evidenced by observations of the stratospheric volcanic eruptions of Agung in 1963 and Pinatubo in 1991 (Baroni et al., GCA, 2011). This relationship is due to an increase in 10Be deposition linked to the role played by the sedimentation of volcanic aerosols. In the light of these new elements, we will discuss the limitations and

  16. Modelling reference conditions for the upper limit of Posidonia oceanica meadows: a morphodynamic approach

    NASA Astrophysics Data System (ADS)

    Vacchi, Matteo; Misson, Gloria; Montefalcone, Monica; Archetti, Renata; Nike Bianchi, Carlo; Ferrari, Marco

    2014-05-01

    The upper portion of the meadows of the protected Mediterranean seagrass Posidonia oceanica occurs in the region of the seafloor mostly affected by surf-related effects. Evaluation of its status is part of monitoring programs, but proper conclusions are difficult to draw due to the lack of definite reference conditions. Comparing the position of the meadow upper limit with the beach morphodynamics (i.e. the distinctive type of beach produced by topography and wave climate) provided evidence that the natural landwards extension of meadows can be predicted. Here we present an innovative predictive cartographic approach able to identify the seafloor portion where the meadow upper limit should naturally lies (i.e. its reference conditions). The conceptual framework of this model is based on 3 essential components: i) Definition of the breaking depth geometry: the breaking limit represents the major constrain for the landward meadow development. We modelled the breaking limit (1 year return time) using the software Mike 21 sw. ii) Definition of the morphodynamic domain of the beach using the surf scaling index ɛ; iii) Definition of the P. oceanica upper limit geometry. We coupled detailed aerial photo with thematic bionomic cartography. In GIS environment, we modelled the seafloor extent where the meadow should naturally lies according to the breaking limit position and the morphodynamic domain of the beach. Then, we added the GIS layer with the meadow upper limit geometry. Therefore, the final output shows, on the same map, both the reference condition and the actual location of the upper limit. It make possible to assess the status of the landward extent of a given P. oceanica meadow and quantify any suspected or observed regression caused by anthropic factors. The model was elaborated and validated along the Ligurian coastline (NW Mediteraanean) and was positively tested in other Mediterranean areas.

  17. 34 CFR 675.20 - Eligible employers and general conditions and limitation on employment.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION FEDERAL WORK-STUDY PROGRAMS Federal Work-Study Program § 675.20 Eligible employers and general conditions and limitation on employment... used or to be used for religious worship or sectarian instruction; or (v) Include employment for the...

  18. 34 CFR 675.20 - Eligible employers and general conditions and limitation on employment.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION FEDERAL WORK-STUDY PROGRAMS Federal Work-Study Program § 675.20 Eligible employers and general conditions and limitation on employment... used or to be used for religious worship or sectarian instruction; or (v) Include employment for the...

  19. 34 CFR 675.20 - Eligible employers and general conditions and limitation on employment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION FEDERAL WORK-STUDY PROGRAMS Federal Work-Study Program § 675.20 Eligible employers and general conditions and limitation on employment... used or to be used for religious worship or sectarian instruction; or (v) Include employment for the...

  20. 34 CFR 675.20 - Eligible employers and general conditions and limitation on employment.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION FEDERAL WORK-STUDY PROGRAMS Federal Work-Study Program § 675.20 Eligible employers and general conditions and limitation on employment... used or to be used for religious worship or sectarian instruction; or (v) Include employment for the...

  1. 76 FR 44245 - Special Conditions: Gulfstream Model GVI Airplane; Limit Engine Torque Loads for Sudden Engine...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-25

    ... FR 25648). One supportive comment was received and the special conditions are adopted as proposed... structural performance of the airplane. The applicable airworthiness regulations do not contain adequate or... imposed by sudden engine stoppage due to malfunction or structural failure.'' Limit loads are expected...

  2. 50 CFR 22.32 - Conditions and limitations on taking under depredation control order.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 9 2013-10-01 2013-10-01 false Conditions and limitations on taking under depredation control order. 22.32 Section 22.32 Wildlife and Fisheries UNITED STATES FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION, SALE, PURCHASE, BARTER, EXPORTATION, AND IMPORTATION...

  3. Bacillus spp. from rainforest soil promote plant growth under limited nitrogen conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aims: The aim of this study was to evaluate effects of PGPR (Plant Growth Promoting Rhizobacteria) isolated from rainforest on different plants under limited nitrogen conditions. Methods and Results: Bacterial isolates from a Peruvian rainforest soil were screened for plant growth promoting effects...

  4. 34 CFR 675.20 - Eligible employers and general conditions and limitation on employment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 34 Education 3 2010-07-01 2010-07-01 false Eligible employers and general conditions and limitation on employment. 675.20 Section 675.20 Education Regulations of the Offices of the Department of Education (Continued) OFFICE OF POSTSECONDARY EDUCATION, DEPARTMENT OF EDUCATION FEDERAL WORK-STUDY PROGRAMS Federal Work-Study Program § 675.20...

  5. Penman-Monteith Evapotranspiration under Soil Moisture Limiting Conditions across California

    NASA Astrophysics Data System (ADS)

    Purdy, A. J.; Famiglietti, J. S.

    2014-12-01

    In arid and semi-arid regions soil moisture often limits the flux of water to meet the atmospheric evapotranspiration (ET) demand. Potentially drier conditions and more variable precipitation and snow in California create a need to better understand how this reservoir limits ET across the state. The upcoming Soil Moisture Active Passive (SMAP) mission's surface and root zone soil moisture data will provide additional information to force observation based ET models at spatial scales ranging from 3-36 km2. To support application of SMAP data to ET modeling we investigate the role of soil moisture within the Penman-Monteith representation at FLUXNET and agricultural sites across California. We present findings on actual ET under soil moisture limiting conditions that do not violate assumptions within this modeling framework.

  6. Forming Limits in Sheet Metal Forming for Non-Proportional Loading Conditions - Experimental and Theoretical Approach

    SciTech Connect

    Ofenheimer, Aldo; Buchmayr, Bruno; Kolleck, Ralf

    2005-08-05

    The influence of strain paths (loading history) on material formability is well known in sheet forming processes. Sophisticated experimental methods are used to determine the entire shape of strain paths of forming limits for aluminum AA6016-T4 alloy. Forming limits for sheet metal in as-received condition as well as for different pre-deformation are presented. A theoretical approach based on Arrieux's intrinsic Forming Limit Stress Curve (FLSC) concept is employed to numerically predict the influence of loading history on forming severity. The detailed experimental strain paths are used in the theoretical study instead of any linear or bilinear simplified loading histories to demonstrate the predictive quality of forming limits in the state of stress.

  7. Microhabitat Conditions in Wyoming's Sage-Grouse Core Areas: Effects on Nest Site Selection and Success.

    PubMed

    Dinkins, Jonathan B; Smith, Kurt T; Beck, Jeffrey L; Kirol, Christopher P; Pratt, Aaron C; Conover, Michael R

    2016-01-01

    The purpose of our study was to identify microhabitat characteristics of greater sage-grouse (Centrocercus urophasianus) nest site selection and survival to determine the quality of sage-grouse habitat in 5 regions of central and southwest Wyoming associated with Wyoming's Core Area Policy. Wyoming's Core Area Policy was enacted in 2008 to reduce human disturbance near the greatest densities of sage-grouse. Our analyses aimed to assess sage-grouse nest selection and success at multiple micro-spatial scales. We obtained microhabitat data from 928 sage-grouse nest locations and 819 random microhabitat locations from 2008-2014. Nest success was estimated from 924 nests with survival data. Sage-grouse selected nests with greater sagebrush cover and height, visual obstruction, and number of small gaps between shrubs (gap size ≥0.5 m and <1.0 m), while selecting for less bare ground and rock. With the exception of more small gaps between shrubs, we did not find any differences in availability of these microhabitat characteristics between locations within and outside of Core Areas. In addition, we found little supporting evidence that sage-grouse were selecting different nest sites in Core Areas relative to areas outside of Core. The Kaplan-Meier nest success estimate for a 27-day incubation period was 42.0% (95% CI: 38.4-45.9%). Risk of nest failure was negatively associated with greater rock and more medium-sized gaps between shrubs (gap size ≥2.0 m and <3.0 m). Within our study areas, Wyoming's Core Areas did not have differing microhabitat quality compared to outside of Core Areas. The close proximity of our locations within and outside of Core Areas likely explained our lack of finding differences in microhabitat quality among locations within these landscapes. However, the Core Area Policy is most likely to conserve high quality habitat at larger spatial scales, which over decades may have cascading effects on microhabitat quality available between areas within

  8. Limiter

    DOEpatents

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  9. Computing cellular automata spectra under fixed boundary conditions via limit graphs

    NASA Astrophysics Data System (ADS)

    Ruivo, Eurico L. P.; de Oliveira, Pedro P. B.

    2016-01-01

    Cellular automata are fully discrete complex systems with parallel and homogeneous behavior studied both from the theoretical and modeling viewpoints. The limit behaviors of such systems are of particular interest, as they give insight into their emerging properties. One possible approach to investigate such limit behaviors is the analysis of the growth of graphs describing the finite time behavior of a rule in order to infer its limit behavior. Another possibility is to study the Fourier spectrum describing the average limit configurations obtained by a rule. While the former approach gives the characterization of the limit configurations of a rule, the latter yields a qualitative and quantitative characterisation of how often particular blocks of states are present in these limit configurations. Since both approaches are closely related, it is tempting to use one to obtain information about the other. Here, limit graphs are automatically adjusted by configurations directly generated by their respective rules, and use the graphs to compute the spectra of their rules. We rely on a set of elementary cellular automata rules, on lattices with fixed boundary condition, and show that our approach is a more reliable alternative to a previously described method from the literature.

  10. An adaptive confidence limit for periodic non-steady conditions fault detection

    NASA Astrophysics Data System (ADS)

    Wang, Tianzhen; Wu, Hao; Ni, Mengqi; Zhang, Milu; Dong, Jingjing; Benbouzid, Mohamed El Hachemi; Hu, Xiong

    2016-05-01

    System monitoring has become a major concern in batch process due to the fact that failure rate in non-steady conditions is much higher than in steady ones. A series of approaches based on PCA have already solved problems such as data dimensionality reduction, multivariable decorrelation, and processing non-changing signal. However, if the data follows non-Gaussian distribution or the variables contain some signal changes, the above approaches are not applicable. To deal with these concerns and to enhance performance in multiperiod data processing, this paper proposes a fault detection method using adaptive confidence limit (ACL) in periodic non-steady conditions. The proposed ACL method achieves four main enhancements: Longitudinal-Standardization could convert non-Gaussian sampling data to Gaussian ones; the multiperiod PCA algorithm could reduce dimensionality, remove correlation, and improve the monitoring accuracy; the adaptive confidence limit could detect faults under non-steady conditions; the fault sections determination procedure could select the appropriate parameter of the adaptive confidence limit. The achieved result analysis clearly shows that the proposed ACL method is superior to other fault detection approaches under periodic non-steady conditions.

  11. Strong premelting effect in the elastic properties of hcp-Fe under inner-core conditions.

    PubMed

    Martorell, Benjamí; Vocadlo, Lidunka; Brodholt, John; Wood, Ian G

    2013-10-25

    The observed shear-wave velocity VS in Earth's core is much lower than expected from mineralogical models derived from both calculations and experiments. A number of explanations have been proposed, but none sufficiently explain the seismological observations. Using ab initio molecular dynamics simulations, we obtained the elastic properties of hexagonal close-packed iron (hcp-Fe) at 360 gigapascals up to its melting temperature Tm. We found that Fe shows a strong nonlinear shear weakening just before melting (when T/Tm > 0.96), with a corresponding reduction in VS. Because temperatures range from T/Tm = 1 at the inner-outer core boundary to T/Tm ≈ 0.99 at the center, this strong nonlinear effect on VS should occur in the inner core, providing a compelling explanation for the low VS observed. PMID:24114785

  12. Limiter

    DOEpatents

    Cohen, Samuel A.; Hosea, Joel C.; Timberlake, John R.

    1986-01-01

    A limiter with a specially contoured front face accommodates the various power scrape-off distances .lambda..sub.p, which depend on the parallel velocity, V.sub..parallel., of the impacting particles. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution.

  13. A water use and growth model for Eucalyptus plantation in water-limited conditions

    SciTech Connect

    Calder, I.R.

    1992-12-31

    To investigate the environmental impact of plantation forestry using fast-growing tree species in southern India, a program of field studies was initiated in 1987 specifically to measure the water use, nutrient uptake and growth rates of the plantations. A water use and growth (WAG) model is proposed for calculating transpiration and growth of Eucalyptus plantation in water-limited conditions. The model is based on the measured relationships between transpiration rate and basal cross-sectional area and soil moisture availability. The volume growth rate (in water-limited conditions) is assumed to be proportional to the volume of water transpired. The model is calibrated using (deuterium tracing) measurements of transpiration and measurements of growth recorded at the Puradal experimental plantation, Karnataka, southern India.

  14. Role of microRNAs involved in plant response to nitrogen and phosphorous limiting conditions

    PubMed Central

    Nguyen, Giao N.; Rothstein, Steven J.; Spangenberg, German; Kant, Surya

    2015-01-01

    Plant microRNAs (miRNAs) are a class of small non-coding RNAs which target and regulate the expression of genes involved in several growth, development, and metabolism processes. Recent researches have shown involvement of miRNAs in the regulation of uptake and utilization of nitrogen (N) and phosphorus (P) and more importantly for plant adaptation to N and P limitation conditions by modifications in plant growth, phenology, and architecture and production of secondary metabolites. Developing strategies that allow for the higher efficiency of using both N and P fertilizers in crop production is important for economic and environmental benefits. Improved crop varieties with better adaptation to N and P limiting conditions could be a key approach to achieve this effectively. Furthermore, understanding on the interactions between N and P uptake and use and their regulation is important for the maintenance of nutrient homeostasis in plants. This review describes the possible functions of different miRNAs and their cross-talk relevant to the plant adaptive responses to N and P limiting conditions. In addition, a comprehensive understanding of these processes at molecular level and importance of biological adaptation for improved N and P use efficiency is discussed. PMID:26322069

  15. Resonant condition for storage ring short wavelength FEL with power exceeding Renieri limit

    SciTech Connect

    Litvinenko, V.N.; Burnham, B.; Wu, Y.

    1995-12-31

    In this paper we discuss the possibility of operating a storage ring FEL with resonant conditions providing for preservation of electron beam structure on an optical wave scale. We suggest tuning the storage ring betatron and synchrotron tunes on one of the high (N-th) order resonances to compensate dynamic diffusion of optical phase. This mode of operation does not require isochronicity of the ring lattice. In these conditions optical phase will be restored after N turns around the ring and stochastic conditions used in the derivation of Renieri limit are no longer applicable. We discuss the influence of high order terms in electron motion, RF frequency stability, and synchrotron radiation effects on preservation of optical phase.

  16. Direct laser-driven ramp compression studies of iron: A first step toward the reproduction of planetary core conditions

    NASA Astrophysics Data System (ADS)

    Amadou, N.; Brambrink, E.; Benuzzi-Mounaix, A.; Huser, G.; Guyot, F.; Mazevet, S.; Morard, G.; de Resseguier, T.; Vinci, T.; Myanishi, K.; Ozaki, N.; Kodama, R.; Boehly, T.; Henry, O.; Raffestin, D.; Koenig, M.

    2013-06-01

    The study of iron under quasi-isentropic compression using high energy lasers, might allow to understand its thermodynamical properties, in particular its melting line in conditions of pressure and temperature relevant to Earth-like planetary cores (330-1500 GPa, 5000-8000 K). However, the iron alpha-epsilon solid-solid phase transition at 13 GPa favors shock formation during the quasi-isentropic compression process which can depart from the appropriate thermodynamical path. Understanding this shock formation mechanism is a key issue for being able to reproduce Earth-like planetary core conditions in the laboratory by ramp compression. In this article, we will present recent results of direct laser-driven quasi-isentropic compression experiments on iron samples obtained on the LULI 2000 and LIL laser facilities.

  17. Prevalence of 'Candidatus Accumulibacter phosphatis' type II under phosphate limiting conditions.

    PubMed

    Welles, L; Lopez-Vazquez, C M; Hooijmans, C M; van Loosdrecht, M C M; Brdjanovic, D

    2016-12-01

    P-limitation in enhanced biological phosphorus removal (EBPR) systems fed with acetate, has generally been considered as a condition leading to enrichment of organisms of the genotype' Candidatus Competibacter phosphatis' expressing the glycogen-accumulating organisms (GAO) phenotype. Recent studies have demonstrated in short-term experiments that organisms of the genotype 'Candidatus Accumulibacter phosphatis' clade I and II, known to express the polyphosphate-accumulating organisms (PAO) phenotype can switch to the GAO phenotype when poly-P is absent, but are performing the HAc-uptake at lower kinetic rates, where clade I showed the lowest rates. The objective of this study was to verify whether organisms of the genotype 'Candidatus Accumulibacter phosphatis' can also be enriched under P-limiting conditions while expressing a GAO phenotype and more specifically to see which specific clade prevails. A sequencing batch reactor was inoculated with activated sludge to enrich an EBPR culture for a cultivation period of 128 days (16 times the solids retention time) under P-limiting conditions. A mixed culture was obtained comprising of 49 % 'Candidatus Accumulibacter phosphatis' clade II and 46 % 'Candidatus Competibacter phosphatis'. The culture performed a full GAO metabolism for anaerobic HAc-uptake, but was still able to switch to a PAO metabolism, taking up excessive amounts of phosphate during the aerobic phase when it became available in the influent. These findings show that P-limitation, often used as strategy for enrichment of 'Candidatus Competibacter phosphatis', does not always lead to enrichment of only 'Candidatus Competibacter phosphatis'. Furthermore, it demonstrates that 'Candidatus Accumulibacter phosphatis' are able to proliferate in activated sludge systems for periods of up to 128 days or longer when the influent phosphate concentrations are just enough for assimilation purposes and no poly-P is formed. The 'Candidatus Accumulibacter

  18. Analysis and Characterization of Dissolved Organic Matter in Ice Cores as Indicators of Past Environmental Conditions Using High Resolution FTICR-MS

    NASA Astrophysics Data System (ADS)

    Boschi, V.; Grannas, A. M.; Willoughby, A. S.; Catanzano, V.; Hatcher, P.

    2015-12-01

    With rapid changes in global temperatures, research aimed at better understanding past climatic events in order to predict future trends is an area of growing importance. Carbonaceous gases stored in ice cores are known to correlate with temperature change and provide evidence of such events. However, more complex forms of carbon preserved in ice cores such as dissolved organic matter (DOM) can provide additional information relating to changes in environmental conditions over time. The examination of ice core samples presents unique challenges including detection of ultra-low concentrations of organic material and extremely limited sample amounts. In this study, solid phase extraction techniques combined with ultra-high resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR-MS) were utilized to successfully extract, concentrate and analyze the low concentrations of DOM in only 100 mL of ice core samples originating from various regions of Antarctica and Greenland. We characterize the DOM composition in each sample by evaluating elemental ratios, molecular formula distribution (CHO, CHON, CHOS and CHNOS) and compound class composition (lignin, tannin, lipid, condensed aromatic, protein and unsaturated hydrocarbon content). Upon characterization, we identified molecular trends in ice core DOM chemistry that correlated with past climatic events in addition to observing possible photochemical and microbial influences affecting DOM chemistry. Considering these samples range in age from 350-1175 years old, thus being formed during the Medieval Warm Period and Little Ice Age, we observed that DOM properties reflected anticipated changes in composition as influenced by warming and cooling events occurring during that time period.

  19. The reef-building coral Acropora conditionally hybridize under sperm limitation.

    PubMed

    Kitanobo, Seiya; Isomura, Naoko; Fukami, Hironobu; Iwao, Kenji; Morita, Masaya

    2016-08-01

    Multi-specific synchronous spawning risks both sperm limitation, which reduces fertilization success, and hybridization with other species. If available sperm of conspecifics are limited, hybridization with heterospecific sperm could be an alternative. Some species of the reef-building coral Acropora produce hybrid offspring in vitro, and therefore hybridization between such species does sometimes occur in nature. Here, we report that the interbreeding species Acropora florida and A. intermedia preferentially bred with conspecifics at optimal gamete concentrations (10(6) cells ml(-1)), but when sperm concentration was low (10(4) cells ml(-1)), A florida eggs displayed an increased incidence of fertilization by sperm of A intermedia However, A intermedia eggs never crossed with heterospecific sperm, regardless of gamete concentrations. It appears that A florida eggs conditionally hybridize with heterospecific sperm; in nature, this would allow A florida to cross with later-spawning species such as A intermedia These results indicate that hybridization between some Acropora species could occur in nature according to the number of available sperm, and the choice of heterospecific sperm for fertilization could be one of the fertilization strategies in the sperm-limited condition. PMID:27555653

  20. Carbon Solution in Core-Forming Magma Ocean Conditions: Implications for the Origin and Distribution of Terrestrial Carbon

    NASA Astrophysics Data System (ADS)

    Dasgupta, R.; Chi, H.; Walker, D.; Shimizu, N.; Buono, A. S.

    2012-12-01

    The origin of bulk silicate Earth carbon inventory is poorly known and the fate of the element during the early Earth differentiation and core formation is a missing link in the evolution of the terrestrial carbon cycle. Here we present high pressure-temperature experiments that simulate metal-silicate equilibria in a shallow magma ocean. Experiments were performed at 1-5 GPa, 1600-2100 °C on mixtures of synthetic or natural silicates (tholeiitic basalt/ alkali basalt/ komatiite/ fertile peridotite) and Fe-Ni-C±Co±S contained in graphite or MgO capsules. All the experiments produced immiscible Fe-rich metallic and silicate melts at oxygen fugacity (fO2) between ~IW-1.5 and IW-1.9. Carbon and hydrogen concentrations of basaltic glasses and non-glassy quenched silicate melts were determined using secondary ionization mass spectrometry (SIMS) and speciation of dissolved C-O-H volatiles in silicate glasses was constrained using Raman spectroscopy. Carbon contents of metallic melts were determined using both electron microprobe and SIMS. Our experiments indicate that at core-forming, reduced conditions, carbon in mafic-ultramafic magmas dissolves primarily as various hydrogenated species and the total carbon storage capacity, although is significantly higher than solubility of CO2 under similar conditions, remains low (<500 ppm). The total carbon content in our reduced melts at graphite saturation increases with increasing melt depolymerization (NBO/T), consistent with recent spectroscopic studies [1], and modestly with increasing hydration. Carbon behaves as a metal loving element during core-mantle separation and metal/silicate carbon partition coefficient, DC varies between ~3500 and ≥150 and increases with increasing pressure and decreases with increasing temperature and melt NBO/T. Extrapolation of our data to the plausible conditions of core-mantle equilibration suggest that if only a trace amount of carbon (~730 ppm C; [2]) was available during early Earth

  1. Exploring the limits and utility of operant conditioning in the treatment of drug addiction

    PubMed Central

    Silverman, Kenneth

    2004-01-01

    This article describes a research program to develop an operant treatment for cocaine addiction in low-income, treatment-resistant methadone patients. The treatment's central feature is an abstinence reinforcement contingency in which patients earn monetary reinforcement for providing cocaine-free urine samples. Success and failure of this contingency appear to be an orderly function of familiar parameters of operant conditioning. Increasing reinforcement magnitude and duration can increase effectiveness, and sustaining the contingency can prevent relapse. Initial development of a potentially practical application of this technology suggests that it may be possible to integrate abstinence reinforcement into employment settings using salary for work to reinforce drug abstinence. This research illustrates the potential utility and current limitations of an operant approach to the treatment of drug addiction. Similar research programs are needed to explore the limits of the operant approach and to develop practical applications that can be used widely in society for the treatment of drug addiction. PMID:22478430

  2. Universal limiting shape of worn profile under multiple-mode fretting conditions: theory and experimental evidence

    PubMed Central

    Dmitriev, Andrey I.; Voll, Lars B.; Psakhie, Sergey G.; Popov, Valentin L.

    2016-01-01

    We consider multiple-mode fretting wear in a frictional contact of elastic bodies subjected to a small-amplitude oscillation, which may include in-plane and out-of-plane translation, torsion and tilting (“periodic rolling”). While the detailed kinetics of wear depends on the particular loading history and wear mechanism, the final worn shape, under some additional conditions, occurs to be universal for all types and loading and wear mechanisms. This universal form is determined solely by the radius of the permanent stick region and the maximum indentation depth during the loading cycle. We provide experimental evidence for the correctness of the theoretically predicted limiting shape. The existence of the universal limiting shape can be used for designing joints which are resistant to fretting wear. PMID:26979092

  3. Universal limiting shape of worn profile under multiple-mode fretting conditions: theory and experimental evidence.

    PubMed

    Dmitriev, Andrey I; Voll, Lars B; Psakhie, Sergey G; Popov, Valentin L

    2016-01-01

    We consider multiple-mode fretting wear in a frictional contact of elastic bodies subjected to a small-amplitude oscillation, which may include in-plane and out-of-plane translation, torsion and tilting ("periodic rolling"). While the detailed kinetics of wear depends on the particular loading history and wear mechanism, the final worn shape, under some additional conditions, occurs to be universal for all types and loading and wear mechanisms. This universal form is determined solely by the radius of the permanent stick region and the maximum indentation depth during the loading cycle. We provide experimental evidence for the correctness of the theoretically predicted limiting shape. The existence of the universal limiting shape can be used for designing joints which are resistant to fretting wear. PMID:26979092

  4. Universal limiting shape of worn profile under multiple-mode fretting conditions: theory and experimental evidence

    NASA Astrophysics Data System (ADS)

    Dmitriev, Andrey I.; Voll, Lars B.; Psakhie, Sergey G.; Popov, Valentin L.

    2016-03-01

    We consider multiple-mode fretting wear in a frictional contact of elastic bodies subjected to a small-amplitude oscillation, which may include in-plane and out-of-plane translation, torsion and tilting (“periodic rolling”). While the detailed kinetics of wear depends on the particular loading history and wear mechanism, the final worn shape, under some additional conditions, occurs to be universal for all types and loading and wear mechanisms. This universal form is determined solely by the radius of the permanent stick region and the maximum indentation depth during the loading cycle. We provide experimental evidence for the correctness of the theoretically predicted limiting shape. The existence of the universal limiting shape can be used for designing joints which are resistant to fretting wear.

  5. Calcification and photosynthesis of the coral acropora cervicornis under calcium limited conditions

    NASA Technical Reports Server (NTRS)

    Rathfon, Megan; Brewer, Debbie

    1997-01-01

    Differing hypothesis about the function of calcification are based on an interesting dilemma. Is the purpose of calcification mainly a structural and protective one or does calcification serve other functions? Does photosynthesis increase carbonate ion activity and cause calcification or does calcification increase CO2 levels and stimulate photsynthesis? It is proposed that calcification in corals is not dependent upon photosynthesis but upon calcium levels in the water. Under normal ocean conditions, corals convert a certain percentage of energy to photosynthesis and respiration and another percentage to calcification. As corals become nutrient stressed, particularly calcium limited, the ratio of photosynthesis to calcification shifts towards calcification in order to generate protons. The protons generated during calcification may stimulate photosynthesis and aid in the uptake of nutrients and biocarbonates. The results of the calcification experiment show a trend towards increased calcification and decreased photosynthesis when the coral Acropora cervicornis is calcium limited, but the data are inconclusive and further research is needed.

  6. The Agony of Choice: How Plants Balance Growth and Survival under Water-Limiting Conditions1

    PubMed Central

    Claeys, Hannes; Inzé, Dirk

    2013-01-01

    When confronted with water limitation, plants actively reprogram their metabolism and growth. Recently, it has become clear that growing tissues show specific and highly dynamic responses to drought, which differ from the well-studied responses in mature tissues. Here, we provide an overview of recent advances in understanding shoot growth regulation in water-limiting conditions. Of special interest is the balance between maintained growth and competitiveness on the one hand and ensured survival on the other hand. A number of master regulators controlling this balance have been identified, such as DELLAs and APETALA2/ETHYLENE RESPONSE FACTOR-type transcription factors. The possibilities of engineering or breeding crops that maintain growth in periods of mild drought, while still being able to activate protective tolerance mechanisms, are discussed. PMID:23766368

  7. A necessary condition for applying MUSIC algorithm in limited-view inverse scattering problem

    NASA Astrophysics Data System (ADS)

    Park, Taehoon; Park, Won-Kwang

    2015-09-01

    Throughout various results of numerical simulations, it is well-known that MUltiple SIgnal Classification (MUSIC) algorithm can be applied in the limited-view inverse scattering problems. However, the application is somehow heuristic. In this contribution, we identify a necessary condition of MUSIC for imaging of collection of small, perfectly conducting cracks. This is based on the fact that MUSIC imaging functional can be represented as an infinite series of Bessel function of integer order of the first kind. Numerical experiments from noisy synthetic data supports our investigation.

  8. Pedestrian evacuation in view and hearing limited condition: The impact of communication and memory

    NASA Astrophysics Data System (ADS)

    Xue, Shuqi; Jia, Bin; Jiang, Rui; Shan, Jingjing

    2016-09-01

    This paper studies pedestrian evacuation in view and hearing limited condition based on the social force approach. It is assumed that there are two types of pedestrians: Informed individuals know the exit location whereas uninformed individuals do not. The uninformed individuals can communicate with the informed ones within their perceptual fields, thus learning to know and memorize the exit location. We consider cases with and without communication/memory. The simulations show communication and memory are able to enhance the evacuation efficiency. We also investigate the impact of communication on the efficiency of an emergency exit.

  9. Surface potential and permeability of rock cores under asphaltenic oil flow conditions

    SciTech Connect

    Alkafeef, S.F.; Gochin, R.J.; Smith, A.L.

    1995-12-31

    The surface properties, wetting behaviour and permeability of rock samples are central to understanding recovery behaviour in oil reservoirs. This paper will present a method new to petroleum engineering to show how area/length ratios for porous systems can be obtained by combining streaming potential and streaming current measurements on rock cores. This has allows streaming current measurements (independent of surface conductivity errors) to be made on rock samples using hydrocarbon solvents with increasing concentrations of asphaltene. Negative surface potentials for the rock became steadily more positive as asphaltene coated the pore surfaces, with permeability reduction agreeing well with petrographic analysis.

  10. A vegetation sensitivity approximation for gross primary production in water limited conditions.

    NASA Astrophysics Data System (ADS)

    Claesson, Jonas; Nycander, Jonas

    2013-04-01

    The most severe impact of climate change on vegetation growth and agriculture is likely to occur under water-limited conditions. Under such conditions the plants optimize the inward flux of CO2 and the outward flux of water vapor (the transpiration) by regulating the size of the stomata openings. Higher temperature increases water loss through transpiration, forcing the plants to diminish the stomata openings, which decreases photosynthesis. This is counteracted by higher CO2 concentration, which allows plants to maintain the inward flux of CO2 through the smaller openings. These two counteracting effects, combined with the change in precipitation, determine the net change of biological productivity in a changed climate. Here, a vegetation sensitivity approximation (VSA) is introduced, in order to understand and estimate the combined effect of changed temperature, CO2-concentration and precipitation on gross primary production (GPP) to first order. According to the VSA, we have: ( ) ?CO2atm ν GP P = ?0 P Here ?CO2atm is the atmospheric CO2 concentration, ?0 is the baseline for atmospheric CO2 concentration, P is precipitation and ν is defined by: -s- ν = 1 - 11°C where s is the climate sensitivity i.e. the increase in temperature when atmospheric CO2 is doubled. The VSA is based on the physical laws of gas flux through the stomata openings, and is only valid under water-limited conditions. It assumes that the temperature depends logarithmically on the CO2 concentration with a given climate sensitivity. Transpiration is assumed to be a constant fraction of precipitation, which is reasonable under water-limited conditions. The VSA is compared to simulations with the dynamic vegetation model LPJ. The agreement is reasonable, and the deviations can be understood by comparison with Köppen's definition of arid climate: in an arid climate growth increases more according to LPJ than according to the VSA, and in non-arid conditions the reverse is true. Both the VSA and

  11. The Extracellular Matrix Protein Brevican Limits Time-Dependent Enhancement of Cocaine Conditioned Place Preference.

    PubMed

    Lubbers, Bart R; Matos, Mariana R; Horn, Annemarie; Visser, Esther; Van der Loo, Rolinka C; Gouwenberg, Yvonne; Meerhoff, Gideon F; Frischknecht, Renato; Seidenbecher, Constanze I; Smit, August B; Spijker, Sabine; van den Oever, Michel C

    2016-06-01

    Cocaine-associated environmental cues sustain relapse vulnerability by reactivating long-lasting memories of cocaine reward. During periods of abstinence, responding to cocaine cues can time-dependently intensify a phenomenon referred to as 'incubation of cocaine craving'. Here, we investigated the role of the extracellular matrix protein brevican in recent (1 day after training) and remote (3 weeks after training) expression of cocaine conditioned place preference (CPP). Wild-type and Brevican heterozygous knock-out mice, which express brevican at ~50% of wild-type levels, received three cocaine-context pairings using a relatively low dose of cocaine (5 mg/kg). In a drug-free CPP test, heterozygous mice showed enhanced preference for the cocaine-associated context at the remote time point compared with the recent time point. This progressive increase was not observed in wild-type mice and it did not generalize to contextual-fear memory. Virally mediated overexpression of brevican levels in the hippocampus, but not medial prefrontal cortex, of heterozygous mice prevented the progressive increase in cocaine CPP, but only when overexpression was induced before conditioning. Post-conditioning overexpression of brevican did not affect remote cocaine CPP, suggesting that brevican limited the increase in remote CPP by altering neuro-adaptive mechanisms during cocaine conditioning. We provide causal evidence that hippocampal brevican levels control time-dependent enhancement of cocaine CPP during abstinence, pointing to a novel substrate that regulates incubation of responding to cocaine-associated cues. PMID:26711251

  12. Prospects and limitations of digital Shearography and Active Thermography in finding and rating flaws in CFRP sandwich parts with honeycomb core

    NASA Astrophysics Data System (ADS)

    Gruber, J.; Mayr, G.; Hendorfer, G.

    2012-05-01

    This work shows the prospects and limitations of the non-destructive testing methods Digital Shearography and Active Thermography when applied to CFRP sandwich parts with honeycomb cores. Two specimens with different core materials (aluminum, NOMEX) and artificial flaws such as delaminations, disbonds and inclusions of foreign material, are tested with Digital Shearography and Pulse Thermography including Pulse Phase Thermography. Both methods provide a good ability for finding and rating the flaws.

  13. Characterization of direct-drive-implosion core conditions on OMEGA with time-resolved Ar K-shell spectroscopy

    NASA Astrophysics Data System (ADS)

    Regan, S. P.; Delettrez, J. A.; Epstein, R.; Jaanimagi, P. A.; Yaakobi, B.; Smalyuk, V. A.; Marshall, F. J.; Meyerhofer, D. D.; Seka, W.; Haynes, D. A.; Golovkin, I. E.; Hooper, C. F.

    2002-04-01

    Direct-drive-implosion core conditions have been characterized on the 60-beam OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system with time-resolved Ar K-shell spectroscopy. Plastic shells with an Ar-doped deuterium fill gas were driven with a 23 kJ, 1 ns square laser pulse smoothed with 1 THz smoothing by spectral dispersion (SSD) and polarization smoothing (PS) using birefringent wedges. The targets are predicted to have a convergence ratio of ˜15. The emissivity-averaged core electron temperature (Te) and density (ne) were inferred from the measured time-dependent Ar K-shell spectral line shapes. As the imploding shell decelerates the observed Te and ne increase to 2.0 (±0.2) keV and 2.5 (±0.5)×1024cm-3 at peak neutron production, which is assumed to occur at the time of the peak emissivity-averaged Te. At peak compression the ne increases to 3.1 (±0.6)×1024cm-3 and the Te decreases to 1.7 (±0.17) keV. The observed core conditions are close to those predicted by a one-dimensional hydrodynamics code.

  14. Contributions from geomagnetic inverse theory to the study of hydromagnetic conditions near the core-mantle boundary

    NASA Technical Reports Server (NTRS)

    Backus, George E.

    1991-01-01

    The Final Report on contributions from geomagnetic inverse theory to the study of hydromagnetic conditions near the core-mantle boundary (CMB) is presented. The original proposal was to study five questions concerning what the surface and satellite magnetic data imply about hydromagnetic and electromagnetic conditions near the CMB. The five questions are: (1) what do the surface and satellite data imply about the geomagnetic field B near the surface of the earth; (2) how does one extrapolate B down through the conducting mantle to the CMB; (3) if B on the CMB is visible, how accurately does it satisfy the frozen-flux approximation; (4) if frozen flux is a good approximation on the CMB, what can be inferred about the fluid velocity v in the upper core; and (5) if v at the CMB is visible, does it suggest any dynamical properties of the core, such as vertical advection, Alfven-inertial waves, link instabilities, or mantle effects. A summary of the research is provided.

  15. Effects of electron correlations on transport properties of iron at Earth's core conditions.

    PubMed

    Zhang, Peng; Cohen, R E; Haule, K

    2015-01-29

    Earth's magnetic field has been thought to arise from thermal convection of molten iron alloy in the outer core, but recent density functional theory calculations have suggested that the conductivity of iron is too high to support thermal convection, resulting in the investigation of chemically driven convection. These calculations for resistivity were based on electron-phonon scattering. Here we apply self-consistent density functional theory plus dynamical mean-field theory (DFT + DMFT) to iron and find that at high temperatures electron-electron scattering is comparable to the electron-phonon scattering, bringing theory into agreement with experiments and solving the transport problem in Earth's core. The conventional thermal dynamo picture is safe. We find that electron-electron scattering of d electrons is important at high temperatures in transition metals, in contrast to textbook analyses since Mott, and that 4s electron contributions to transport are negligible, in contrast to numerous models used for over fifty years. The DFT+DMFT method should be applicable to other high-temperature systems where electron correlations are important. PMID:25631449

  16. In-situ Density and Thermal Expansion Measurements of Fe and Fe-S Alloying Liquids Under Planetary Core Conditions

    NASA Astrophysics Data System (ADS)

    Jing, Z.; Chantel, J.; Yu, T.; Sakamaki, T.; Wang, Y.

    2015-12-01

    Liquid iron is likely the dominant constituent in the cores of terrestrial planets and icy satellites such as Earth, Mars, Mercury, the Moon, Ganymede, and Io. Suggested by geophysical and geochemical observations, light elements such as S, C, Si, etc., are likely present in planetary cores. These light elements can significantly reduce the density and melting temperature of the Fe cores, and hence their abundances are crucial to our understanding of the structure and thermal history of planetary cores, as well as the generation of intrinsic magnetic fields. Knowledge on the density of Fe-light element alloying liquids at high pressures is critical to place constraints on the composition of planetary cores. However, density data on liquid Fe-light element alloys at core pressures are very limited in pressure and composition and are sometimes controversial. In this study, we extend the density dataset for Fe-rich liquids by measuring the density of Fe, Fe-10wt%S, Fe-20wt%S, Fe-27wt%S, and FeS liquids using the X-ray absorption technique in a DIA-type multianvil apparatus up to 7 GPa and 2173 K. An ion chamber (1D-detector) and a CCD camera (2D-detector) were used to measure intensities of transmitted monochromatic X-rays through molten samples, with the photon energy optimized at 40 keV. The densities were then determined from the Beer-Lambert law using the mass absorption coefficients, calibrated by solid standards using X-ray diffraction. At each pressure, density measurements were conducted at a range of temperatures above the liquidus of the samples, enabling the determination of thermal expansion. Combined with our previous results on the sound velocity of Fe and Fe-S liquids at high pressures (Jing et al., 2014, Earth Planet. Sci. Lett. 396, 78-87), these data provide tight constraints on the equation of state and thermodynamic properties such as the adiabatic temperature gradient for Fe-S liquids. We will discuss these results with implications to planetary

  17. Assessment of bacterial community structure in nitrifying biofilm under inorganic carbon-sufficient and -limited conditions.

    PubMed

    Bae, Hyokwan; Chung, Yun-Chul; Yang, Heejeong; Lee, Changsoo; Aryapratama, Rio; Yoo, Young J; Lee, Seockheon

    2015-01-01

    In this work, nitrification and changes in the composition of the total bacterial community under inorganic carbon (IC)-limited conditions, in a nitrifying moving bed biofilm reactor, was investigated. A culture-independent analysis of cloning and sequencing based on the 16S rRNA gene was applied to quantify the bacterial diversity and to determine bacterial taxonomic assignment. IC concentrations had significant effects on the stability of ammonia-oxidation as indicated by the reduction of the nitrogen conversion rate with high NH4(+)-N loadings. The predominance of Nitrosomonas europaea was maintained in spite of changes in the IC concentration. In contrast, heterotrophic bacterial species contributed to a high bacterial diversity, and to a dynamic shift in the bacterial community structure, under IC-limited conditions. In this study, individual functions of heterotrophic bacteria were estimated based on taxonomic information. Possible key roles of coexisting heterotrophic bacteria are the assimilation of organic compounds of extracellular polymeric substances produced by nitrifiers, and biofilm formation by providing a filamentous structure and aggregation properties. PMID:25560266

  18. Conditions for shock revival by neutrino heating in core-collapse supernovae

    NASA Astrophysics Data System (ADS)

    Janka, H.-Th.

    2001-03-01

    Energy deposition by neutrinos can rejuvenate the stalled bounce shock and can provide the energy for the supernova explosion of a massive star. This neutrino-heating mechanism, though investigated by numerical simulations and analytic studies, is not finally accepted or proven as the trigger of the explosion. Part of the problem is that different groups have obtained seemingly discrepant results, and the complexity of the hydrodynamic models often hampers a clear and simple interpretation of the results. This demands a deeper theoretical understanding of the requirements of a successful shock revival. A toy model is developed here for discussing the neutrino heating phase analytically. The neutron star atmosphere between the neutrinosphere and the supernova shock can well be considered to be in hydrostatic equilibrium, with a layer of net neutrino cooling below the gain radius and a layer of net neutrino heating above. Since the mass infall rate to the shock is in general different from the rate at which gas is advected into the neutron star, the mass in the gain layer varies with time. Moreover, the gain layer receives additional energy input by neutrinos emitted from the neutrinosphere and the cooling layer. Therefore the determination of the shock evolution requires a time-dependent treatment. To this end the hydrodynamical equations of continuity and energy are integrated over the volume of the gain layer to obtain conservation laws for the total mass and energy in this layer. The radius and velocity of the supernova shock can then be calculated from global properties of the gain layer as solutions of an initial value problem, which expresses the fact that the behavior of the shock is controlled by the cumulative effects of neutrino heating and mass accumulation in the gain layer. The described toy model produces steady-state accretion and mass outflow from the nascent neutron star as special cases. The approach is useful to illuminate the conditions that can

  19. Composite Cores

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Spang & Company's new configuration of converter transformer cores is a composite of gapped and ungapped cores assembled together in concentric relationship. The net effect of the composite design is to combine the protection from saturation offered by the gapped core with the lower magnetizing requirement of the ungapped core. The uncut core functions under normal operating conditions and the cut core takes over during abnormal operation to prevent power surges and their potentially destructive effect on transistors. Principal customers are aerospace and defense manufacturers. Cores also have applicability in commercial products where precise power regulation is required, as in the power supplies for large mainframe computers.

  20. Physiological characterization of xylose metabolism in Aspergillus niger under oxygen-limited conditions.

    PubMed

    Meijer, S; Panagiotou, G; Olsson, L; Nielsen, J

    2007-10-01

    The physiology of Aspergillus niger was studied under different aeration conditions. Five different aeration rates were investigated in batch cultivations of A. niger grown on xylose. Biomass, intra- and extra-cellular metabolites profiles were determined and ten different enzyme activities in the central carbon metabolism were assessed. The focus was on organic acid production with a special interest in succinate production. The fermentations revealed that oxygen limitation significantly changes the physiology of the micro-organism. Changes in extra cellular metabolite profiles were observed, that is, there was a drastic increase in polyol production (erythritol, xylitol, glycerol, arabitol, and mannitol) and to a lesser extent in the production of reduced acids (malate and succinate). The intracellular metabolite profiles indicated changes in fluxes, since several primary metabolites, like the intermediates of the TCA cycle accumulated during oxygen limitation (on average three fold increase). Also the enzyme activities showed changes between the exponential growth phase and the oxygen limitation phase. In general, the oxygen availability has a significant impact on the physiology of this fungus causing dramatic alterations in the central carbon metabolism that should be taken into account in the design of A. niger as a succinate cell factory. PMID:17335061

  1. Deconvolution and IVIVC: Exploring the Role of Rate-Limiting Conditions.

    PubMed

    Margolskee, Alison; Darwich, Adam S; Galetin, Aleksandra; Rostami-Hodjegan, Amin; Aarons, Leon

    2016-03-01

    In vitro-in vivo correlations (IVIVCs) play an important role in formulation development and drug approval. At the heart of IVIVC is deconvolution, the method of deriving an in vivo "dissolution profile" for comparison with in vitro dissolution data. IVIVCs are generally believed to be possible for highly permeable and highly soluble compounds with release/dissolution as the rate-limiting step. In this manuscript, we apply the traditional deconvolution methods, Wagner-Nelson and numerical deconvolution, to profiles simulated using a simplified small intestine absorption and transit model. Small intestinal transit, dissolution, and absorption rate constants are varied across a range of values approximately covering those observed in the literature. IVIVC plots and their corresponding correlation coefficients are analyzed for each combination of parameters to determine the applicability of the deconvolution methods under a range of rate-limiting conditions. For highly absorbed formulations, the correlation coefficients obtained during IVIVC are comparable for both methods and steadily decline with decreasing dissolution rate and increasing transit rate. The applicability of numerical deconvolution to IVIVC is not greatly affected by absorption rate, whereas the applicability of Wagner-Nelson falls when dissolution rate overcomes absorption rate and absorption becomes the rate-limiting step. The discrepancy between the expected and deconvolved input arises from the violation of a key assumption of deconvolution that the unknown input and unit impulse enter the system in the same location. PMID:26667356

  2. Oceanographic Conditions Limit the Spread of a Marine Invader along Southern African Shores.

    PubMed

    Assis, Jorge; Zupan, Mirta; Nicastro, Katy R; Zardi, Gerardo I; McQuaid, Christopher D; Serrão, Ester A

    2015-01-01

    Invasive species can affect the function and structure of natural ecological communities, hence understanding and predicting their potential for spreading is a major ecological challenge. Once established in a new region, the spread of invasive species is largely controlled by their dispersal capacity, local environmental conditions and species interactions. The mussel Mytilus galloprovincialis is native to the Mediterranean and is the most successful marine invader in southern Africa. Its distribution there has expanded rapidly and extensively since the 1970s, however, over the last decade its spread has ceased. In this study, we coupled broad scale field surveys, Ecological Niche Modelling (ENM) and Lagrangian Particle Simulations (LPS) to assess the current invaded distribution of M. galloprovincialis in southern Africa and to evaluate what prevents further spread of this species. Results showed that all environmentally suitable habitats in southern Africa have been occupied by the species. This includes rocky shores between Rocky Point in Namibia and East London in South Africa (approx. 2800 km) and these limits coincide with the steep transitions between cool-temperate and subtropical-warmer climates, on both west and southeast African coasts. On the west coast, simulations of drifting larvae almost entirely followed the northward and offshore direction of the Benguela current, creating a clear dispersal barrier by advecting larvae away from the coast. On the southeast coast, nearshore currents give larvae the potential to move eastwards, against the prevalent Agulhas current and beyond the present distributional limit, however environmental conditions prevent the establishment of the species. The transition between the cooler and warmer water regimes is therefore the main factor limiting the northern spread on the southeast coast; however, biotic interactions with native fauna may also play an important role. PMID:26114766

  3. Oceanographic Conditions Limit the Spread of a Marine Invader along Southern African Shores

    PubMed Central

    Nicastro, Katy R.; Zardi, Gerardo I.; McQuaid, Christopher D.; Serrão, Ester A.

    2015-01-01

    Invasive species can affect the function and structure of natural ecological communities, hence understanding and predicting their potential for spreading is a major ecological challenge. Once established in a new region, the spread of invasive species is largely controlled by their dispersal capacity, local environmental conditions and species interactions. The mussel Mytilus galloprovincialis is native to the Mediterranean and is the most successful marine invader in southern Africa. Its distribution there has expanded rapidly and extensively since the 1970s, however, over the last decade its spread has ceased. In this study, we coupled broad scale field surveys, Ecological Niche Modelling (ENM) and Lagrangian Particle Simulations (LPS) to assess the current invaded distribution of M. galloprovincialis in southern Africa and to evaluate what prevents further spread of this species. Results showed that all environmentally suitable habitats in southern Africa have been occupied by the species. This includes rocky shores between Rocky Point in Namibia and East London in South Africa (approx. 2800 km) and these limits coincide with the steep transitions between cool-temperate and subtropical-warmer climates, on both west and southeast African coasts. On the west coast, simulations of drifting larvae almost entirely followed the northward and offshore direction of the Benguela current, creating a clear dispersal barrier by advecting larvae away from the coast. On the southeast coast, nearshore currents give larvae the potential to move eastwards, against the prevalent Agulhas current and beyond the present distributional limit, however environmental conditions prevent the establishment of the species. The transition between the cooler and warmer water regimes is therefore the main factor limiting the northern spread on the southeast coast; however, biotic interactions with native fauna may also play an important role. PMID:26114766

  4. Optimization of plant mineral nutrition under growth-limiting conditions in a lunar greenhouse

    NASA Astrophysics Data System (ADS)

    Zaets, I.; Voznyuk, T.; Kovalchuk, M.; Rogutskyy, I.; Lukashov, D.; Mytrokhyn, O.; Mashkovska, S.; Foing, B.; Kozyrovska, N.

    It may be assumed that the first plants in a lunar base will play a main role in forming a protosoil of acceptable fertility needed for purposively growing second generation plants like wheat, rice, tulips, etc. The residues of the first-generation plants could be composted and transformed by microorganisms into a soil-like substrate within a loop of regenerative life support system. The lunar regolith may be used as a substrate for plant growth at the very beginning of a mission to reduce its cost. The use of microbial communities for priming plants will allow one to facilitate adaption to stressful conditions and to support the plant development under growth limiting conditions. Well-defined plant-associated bacteria were used for growing three cultivars to colonize French marigold (Tagetes patula L.) in anorthosite, a substrate of low bioavailability, analogous to a lunar rock. The consortium was composed of plant growth promoting rhizobacteria and the bacterium Paenibacillus sp. IMBG156 which stimulated seed germination, better plant development, and finally, the flowering of inoculated tagetes. In contrast, control plants grew poorly in the anorthosite and practically did not survive until flowering. Analysis of bacterial community composition showed that all species colonized plant roots, however, the rate of colonization depended on the allelopatic characteristics of marigold varieties. Bacteria of consortium were able to liberate some elements (Ca, Fe, Mn, Si, Ni, Cu, Zn) from substrate anorthosite. Plant colonization by mixed culture of bacterial strains resulted in the increase of accumulation of K, Mg, Mn by the plant and in the lowering of the level of toxic metal accumulation. It was assumed that a rationally assembled consortium of bacterial strains promoted germination of marygold seeds and supported the plant development under growth limiting conditions by means of bioleaching plant essential nutritional elements and by protecting the plant against

  5. Floral resource limitation severely reduces butterfly survival, condition and flight activity in simplified agricultural landscapes.

    PubMed

    Lebeau, Julie; Wesselingh, Renate A; Van Dyck, Hans

    2016-02-01

    Agricultural intensification has a strong negative impact on farmland biodiversity (including flower-visiting insects), but understanding the mechanisms involved in this requires experimental work. We document the impact of nectar limitation on the performance of a flower-visiting insect, the meadow brown butterfly Maniola jurtina. We conducted two types of experiments: a field experiment in agricultural landscapes with grasslands of different management intensity and an experiment in outdoor flight cages in which the nectar supply was simulated. For the field experiment, we introduced an array of nectar resources in intensively managed, nectar-poor meadows and in extensively managed, flower-rich grasslands and counted flower visitors. Despite higher butterfly abundance in the extensive meadows, our introduced nectar sources were more frequently visited in intensive meadows, indicating the lack of floral resources. The 48-h confinement under nectar-poor conditions in the flight cages had a strong negative effect on body condition, flight activity and lifetime survival compared to butterflies under nectar-rich conditions. Female lifespan was reduced by 22% and male lifespan even by 43%. Agricultural landscapes that provide limited amounts of floral nectar, and no high-quality, preferred nectar sources relative to the needs of the flower-visiting species, may create ecological sinks. Regards an insect's performance, the simple presence of nectar is not necessarily functionally adequate. The effectiveness of agri-environmental schemes for flower-visiting insects (e.g. flower strips) could be improved based on ecological and evolutionary insights on the effects of specific nectar quantities and qualities. PMID:26541442

  6. MYB10 and MYB72 are required for growth under iron-limiting conditions.

    PubMed

    Palmer, Christine M; Hindt, Maria N; Schmidt, Holger; Clemens, Stephan; Guerinot, Mary Lou

    2013-11-01

    Iron is essential for photosynthesis and is often a limiting nutrient for plant productivity. Plants respond to conditions of iron deficiency by increasing transcript abundance of key genes involved in iron homeostasis, but only a few regulators of these genes have been identified. Using genome-wide expression analysis, we searched for transcription factors that are induced within 24 hours after transferring plants to iron-deficient growth conditions. Out of nearly 100 transcription factors shown to be up-regulated, we identified MYB10 and MYB72 as the most highly induced transcription factors. Here, we show that MYB10 and MYB72 are functionally redundant and are required for plant survival in alkaline soil where iron availability is greatly restricted. myb10myb72 double mutants fail to induce transcript accumulation of the nicotianamine synthase gene NAS4. Both myb10myb72 mutants and nas4-1 mutants have reduced iron concentrations, chlorophyll levels, and shoot mass under iron-limiting conditions, indicating that these genes are essential for proper plant growth. The double myb10myb72 mutant also showed nickel and zinc sensitivity, similar to the nas4 mutant. Ectopic expression of NAS4 rescues myb10myb72 plants, suggesting that loss of NAS4 is the primary defect in these plants and emphasizes the importance of nicotianamine, an iron chelator, in iron homeostasis. Overall, our results provide evidence that MYB10 and MYB72 act early in the iron-deficiency regulatory cascade to drive gene expression of NAS4 and are essential for plant survival under iron deficiency. PMID:24278034

  7. Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population.

    PubMed

    Adams, Jennifer R; Vucetich, Leah M; Hedrick, Philip W; Peterson, Rolf O; Vucetich, John A

    2011-11-22

    Genetic rescue, in which the introduction of one or more unrelated individuals into an inbred population results in the reduction of detrimental genetic effects and an increase in one or more vital rates, is a potentially important management tool for mitigating adverse effects of inbreeding. We used molecular techniques to document the consequences of a male wolf (Canis lupus) that immigrated, on its own, across Lake Superior ice to the small, inbred wolf population in Isle Royale National Park. The immigrant's fitness so exceeded that of native wolves that within 2.5 generations, he was related to every individual in the population and his ancestry constituted 56 per cent of the population, resulting in a selective sweep of the total genome. In other words, all the male ancestry (50% of the total ancestry) descended from this immigrant, plus 6 per cent owing to the success of some of his inbred offspring. The immigration event occurred in an environment where space was limiting (i.e. packs occupied all available territories) and during a time when environmental conditions had deteriorated (i.e. wolves' prey declined). These conditions probably explain why the immigration event did not obviously improve the population's demography (e.g. increased population numbers or growth rate). Our results show that the beneficial effects of gene flow may be substantial and quickly manifest, short-lived under some circumstances, and how the demographic benefits of genetic rescue might be masked by environmental conditions. PMID:21450731

  8. Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population

    PubMed Central

    Adams, Jennifer R.; Vucetich, Leah M.; Hedrick, Philip W.; Peterson, Rolf O.; Vucetich, John A.

    2011-01-01

    Genetic rescue, in which the introduction of one or more unrelated individuals into an inbred population results in the reduction of detrimental genetic effects and an increase in one or more vital rates, is a potentially important management tool for mitigating adverse effects of inbreeding. We used molecular techniques to document the consequences of a male wolf (Canis lupus) that immigrated, on its own, across Lake Superior ice to the small, inbred wolf population in Isle Royale National Park. The immigrant's fitness so exceeded that of native wolves that within 2.5 generations, he was related to every individual in the population and his ancestry constituted 56 per cent of the population, resulting in a selective sweep of the total genome. In other words, all the male ancestry (50% of the total ancestry) descended from this immigrant, plus 6 per cent owing to the success of some of his inbred offspring. The immigration event occurred in an environment where space was limiting (i.e. packs occupied all available territories) and during a time when environmental conditions had deteriorated (i.e. wolves' prey declined). These conditions probably explain why the immigration event did not obviously improve the population's demography (e.g. increased population numbers or growth rate). Our results show that the beneficial effects of gene flow may be substantial and quickly manifest, short-lived under some circumstances, and how the demographic benefits of genetic rescue might be masked by environmental conditions. PMID:21450731

  9. Comparison of estimated core body temperature measured with the BioHarness and rectal temperature under several heat stress conditions.

    PubMed

    Seo, Yongsuk; DiLeo, Travis; Powell, Jeffrey B; Kim, Jung-Hyun; Roberge, Raymond J; Coca, Aitor

    2016-08-01

    Monitoring and measuring core body temperature is important to prevent or minimize physiological strain and cognitive dysfunction for workers such as first responders (e.g., firefighters) and military personnel. The purpose of this study is to compare estimated core body temperature (Tco-est), determined by heart rate (HR) data from a wearable chest strap physiology monitor, to standard rectal thermometry (Tre) under different conditions.  Tco-est and Tre measurements were obtained in thermoneutral and heat stress conditions (high temperature and relative humidity) during four different experiments including treadmill exercise, cycling exercise, passive heat stress, and treadmill exercise while wearing personal protective equipment (PPE).  Overall, the mean Tco-est did not differ significantly from Tre across the four conditions. During exercise at low-moderate work rates under heat stress conditions, Tco-est was consistently higher than Tre at all-time points. Tco-est underestimated temperature compared to Tre at rest in heat stress conditions and at a low work rate under heat stress while wearing PPE. The mean differences between the two measurements ranged from -0.1 ± 0.4 to 0.3 ± 0.4°C and Tco-est correlated well with HR (r = 0.795 - 0.849) and mean body temperature (r = 0.637 - 0.861).  These results indicate that, the comparison of Tco-est to Tre may result in over- or underestimation which could possibly lead to heat-related illness during monitoring in certain conditions. Modifications to the current algorithm should be considered to address such issues. PMID:26954265

  10. Understanding the Disability Dynamics of Youth: Health Condition and Limitation Changes for Youth and Their Influence on Longitudinal Survey Attrition.

    PubMed

    Mann, David R; Honeycutt, Todd

    2016-06-01

    Disability status-experiencing a functional limitation caused by a health condition-is dynamic throughout the life cycle, even during adolescence and young adulthood. We use data from the 1997 cohort of the National Longitudinal Survey of Youth to better understand these dynamics, examining how health condition and limitation statuses evolve during adolescence and young adulthood as well as how changes in these characteristics are related to survey nonresponse and attrition. Health condition and limitation dynamics are evident in our data: the proportion of sample members who reported having a limitation in their activities for any interview increased from approximately 12 % during the initial interview (when sample members were 12 to 17 years old) to almost 25 % 13 years later. Multivariate analyses revealed that women are more likely than men to report changes in health condition or limitation status. Those with mild limitations were relatively less likely than those without limitations or with severe limitations to experience changes in limitation status. Somewhat surprisingly, a survival analysis of survey participation outcomes found limited correlation among health conditions, limitations, and either missing a survey interview for the first time or permanently leaving the survey sample. PMID:27083196

  11. The role of psychosocial working conditions on burnout and its core component emotional exhaustion – a systematic review

    PubMed Central

    2014-01-01

    Aims To analyze the association between psychosocial working conditions and burnout and its core component emotional exhaustion, a systematic literature review was undertaken including cohort studies, case–control studies, and randomized controlled trials. Methods The literature search in Medline and PsycInfo was based on a defined search string and strict exclusion and inclusion criteria. Evaluation of the 5,599 initially identified search hits by two independent reviewers and a detailed quality assessment resulted in six methodologically adequate cohort studies considering the relationship between psychosocial working conditions and burnout (one study) as well as the burnout core component emotional exhaustion (five studies). Results The results of our systematic review point to a relationship between psychosocial working conditions and the development of emotional exhaustion/burnout. Particularly high job demands seem to play a role in the development of emotional exhaustion. However, strong intercorrelations between workplace factors, as a matter of principle, make the identification of a single psychosocial workplace factor (being associated with an especially high or low risk of burnout) difficult. Conclusions Multidimensional approaches including reduction of work demands, enhancement of decision latitude and improving the social climate might be promising for preventing burnout and emotional exhaustion. However, methodologically adequate intervention studies are urgently needed to prove the effectiveness of workplace interventions. PMID:24628839

  12. Melting curves and entropy of melting of iron under Earth's core conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Jin; Liu, Zhi-Yong; Liu, Zhong-Li; Cai, Ling-Cang

    2015-07-01

    The melting curves of iron are determined up to 365 GPa via molecular dynamic (MD) simulations combining with the embedded atom model (EAM) potential developed by Ackland et al. We simulated the melting with three approaches, the hysteresis, two-phase and recently modified Z methods. All three techniques can produce satisfying results, consistent well with most of static compression measurements and shock experiments. Hence, we recommend that these three techniques and this EAM potential are reliable techniques and potential for simulating melting properties of iron. Fitting the well-known Simon equation to our two-phase data we yield the analytical melting curve for iron: 1825(1 + P/57.723)0.654, which gives a melting point at the inner core boundary of 6345 K, very close to the recent diamond anvil cell (DAC) extrapolated value and other ab initio calculations. Furthermore, the analyses of our entropy of melting and solid-liquid interfacial energy γsl indicate that at high pressure, the entropy of fusion shows weak pressure effect. The γsl increases monotonically with pressure, and can be described as a second-order polynomial relation.

  13. Structural response of reactor-core hexcan subassemblies subjected to dynamic overpressurization under accident conditions

    SciTech Connect

    Pfeiffer, P.A.; Kulak, R.F.

    1993-01-01

    This paper presents a two-dimensional structural analysis for the evaluation of a single core subassembly due to internal overpressure associated with possible failure of fuel pins having high fission gas plenum pressure. Structural models are developed for the subassemblies and their surroundings with emphasis on the critical physical aspects of the problem. With these models the strains, deformations and the extent of permanent damage (plastic strain) to the subassemblies can be assessed. The nonlinear structural analyses was performed with a finite element program called STRAW (Structural Transient Response of Assembly Wrappers). This finite element program is applicable to nonlinear large displacement problems. The results of this study indicate that the permanent deformation (damage) is strongly influenced by the rise time (time to reach peak pressure) of the pressure pulse and the pressure in the fuel pin. The rise time is influenced by the opening time of the flow path for release of gas from the fuel pin plenum. Several examples are illustrated with various rise times and pressure magnitudes and the resulting permanent deformation of the hexcan wall.

  14. Structural response of reactor-core hexcan subassemblies subjected to dynamic overpressurization under accident conditions

    SciTech Connect

    Pfeiffer, P.A.; Kulak, R.F.

    1993-06-01

    This paper presents a two-dimensional structural analysis for the evaluation of a single core subassembly due to internal overpressure associated with possible failure of fuel pins having high fission gas plenum pressure. Structural models are developed for the subassemblies and their surroundings with emphasis on the critical physical aspects of the problem. With these models the strains, deformations and the extent of permanent damage (plastic strain) to the subassemblies can be assessed. The nonlinear structural analyses was performed with a finite element program called STRAW (Structural Transient Response of Assembly Wrappers). This finite element program is applicable to nonlinear large displacement problems. The results of this study indicate that the permanent deformation (damage) is strongly influenced by the rise time (time to reach peak pressure) of the pressure pulse and the pressure in the fuel pin. The rise time is influenced by the opening time of the flow path for release of gas from the fuel pin plenum. Several examples are illustrated with various rise times and pressure magnitudes and the resulting permanent deformation of the hexcan wall.

  15. Diffusion modeling of fission product release during depressurized core conduction cooldown conditions

    SciTech Connect

    Martin, R.C.

    1990-01-01

    A simple model for diffusion through the silicon carbide layer of TRISO particles is applied to the data for accident condition testing of fuel spheres for the High-Temperature Reactor program of the Federal Republic of Germany (FRG). Categorization of sphere release of {sup 137}Cs based on fast neutron fluence permits predictions of release with an accuracy comparable to that of the US/FRG accident condition fuel performance model. Calculations are also performed for {sup 85}Kr, {sup 90}Sr, and {sup 110m}Ag. Diffusion of cesium through SiC suggests that models of fuel failure should consider fuel performance during repeated accident condition thermal cycling. Microstructural considerations in models in fission product release are discussed. The neutron-induced segregation of silicon within the SiC structure is postulated as a mechanism for enhanced fission product release during accident conditions. An oxygen-enhanced SiC decomposition mechanism is also discussed. 12 refs., 11 figs., 2 tabs.

  16. Soil texture and climatc conditions for biocrust growth limitation: a meta analysis

    NASA Astrophysics Data System (ADS)

    Fischer, Thomas; Subbotina, Mariia

    2015-04-01

    clay content and with study site as a random effect. (III) Threshold values of texture and climatc effects were identified using a regression tree. Three mean annual temperature classes for texture dependent BSC growth limitation were identified: (1) <9 °C with a threshold value of 25% silt and clay (limited growth on coarser soils), (2) 9-19 °C, where texture did have no influence on relative crust biomass, and (3) >19 °C at soils with <4 or >17% silt and clay. Because biocrust development is limited under certain climatic and soil texture conditions, it is suggested to consider soil texture for biocrust rehabilitation purposes and in biogeochemical modeling of cryptogamic ground covers. References Belnap, J. & Eldridge, D. 2001. Disturbance and Recovery of Biological Soil Crusts. In: Belnap, J. & Lange, O. (eds.) Biological Soil Crusts: Structure, Function, and Management, Springer, Berlin. Belnap, J. 2001. Biological Soil Crusts and Wind Erosion. In: Belnap, J. & Lange, O. (eds.) Fischer, T., Subbotina, M. 2014. Climatic and soil texture threshold values for cryptogamic cover development: a meta analysis. Biologia 69/11:1520-1530,

  17. Language and Traits of Autism Spectrum Conditions: Evidence of Limited Phenotypic and Etiological Overlap

    PubMed Central

    Taylor, Mark J.; Charman, Tony; Robinson, Elise B.; Hayiou-Thomas, Marianna E.; Happé, Francesca; Dale, Philip S.; Ronald, Angelica

    2015-01-01

    Language difficulties have historically been viewed as integral to autism spectrum conditions (ASC), leading molecular genetic studies to consider whether ASC and language difficulties have overlapping genetic bases. The extent of genetic, and also environmental, overlap between ASC and language is, however, unclear. We hence conducted a twin study of the concurrent association between autistic traits and receptive language abilities. Internet-based language tests were completed by ~3,000 pairs of twins, while autistic traits were assessed via parent ratings. Twin model fitting explored the association between these measures in the full sample, while DeFries-Fulker analysis tested these associations at the extremes of the sample. Phenotypic associations between language ability and autistic traits were modest and negative. The degree of genetic overlap was also negative, indicating that genetic influences on autistic traits lowered language scores in the full sample (mean genetic correlation = −0.13). Genetic overlap was also low at the extremes of the sample (mean genetic correlation = 0.14), indicating that genetic influences on quantitatively defined language difficulties were largely distinct from those on extreme autistic traits. Variation in language ability and autistic traits were also associated with largely different nonshared environmental influences. Language and autistic traits are influenced by largely distinct etiological factors. This has implications for molecular genetic studies of ASC and understanding the etiology of ASC. Additionally, these findings lend support to forthcoming DSM-5 changes to ASC diagnostic criteria that will see language difficulties separated from the core ASC communication symptoms, and instead listed as a clinical specifier. PMID:25088445

  18. Language and traits of autism spectrum conditions: evidence of limited phenotypic and etiological overlap.

    PubMed

    Taylor, Mark J; Charman, Tony; Robinson, Elise B; Hayiou-Thomas, Marianna E; Happé, Francesca; Dale, Philip S; Ronald, Angelica

    2014-10-01

    Language difficulties have historically been viewed as integral to autism spectrum conditions (ASC), leading molecular genetic studies to consider whether ASC and language difficulties have overlapping genetic bases. The extent of genetic, and also environmental, overlap between ASC and language is, however, unclear. We hence conducted a twin study of the concurrent association between autistic traits and receptive language abilities. Internet-based language tests were completed by ~3,000 pairs of twins, while autistic traits were assessed via parent ratings. Twin model fitting explored the association between these measures in the full sample, while DeFries-Fulker analysis tested these associations at the extremes of the sample. Phenotypic associations between language ability and autistic traits were modest and negative. The degree of genetic overlap was also negative, indicating that genetic influences on autistic traits lowered language scores in the full sample (mean genetic correlation = -0.13). Genetic overlap was also low at the extremes of the sample (mean genetic correlation = 0.14), indicating that genetic influences on quantitatively defined language difficulties were largely distinct from those on extreme autistic traits. Variation in language ability and autistic traits were also associated with largely different nonshared environmental influences. Language and autistic traits are influenced by largely distinct etiological factors. This has implications for molecular genetic studies of ASC and understanding the etiology of ASC. Additionally, these findings lend support to forthcoming DSM-5 changes to ASC diagnostic criteria that will see language difficulties separated from the core ASC communication symptoms, and instead listed as a clinical specifier. PMID:25088445

  19. Changes in exercise and post-exercise core temperature under different clothing conditions

    NASA Astrophysics Data System (ADS)

    Kenny, Glen P.; Reardon, Francis D.; Thoden, Jim S.; Giesbrecht, Gordon G.; Kenny, G.

    This study evaluates the effect of different levels of insulation on esophageal (Tes) and rectal (Tre) temperature responses during and following moderate exercise. Seven subjects completed three 18-min bouts of treadmill exercise (75% VO2max, 22°C ambient temperature) followed by 30 min of recovery wearing either: (1) jogging shoes, T-shirt and shorts (athletic clothing); (2) single-knit commercial coveralls worn over the athletic clothing (coveralls); or (3) a Canadian Armed Forces nuclear, bacteriological and chemical warfare protective overgarment with hood, worn over the athletic clothing (NBCW overgarment). Tes was similar at the start of exercise for each condition and baseline Tre was 0.4°C higher than Tes. The hourly equivalent rate of increase in Tes during the final 5 min of exercise was 1.8°C, 3.0°C and 4.2°C for athletic clothing, coveralls and NBCW overgarment respectively (P<0.05). End-exercise Tes was significantly different between conditions [37.7°C (SEM 0.1°C), 38.2°C (SEM 0.2°C and 38.5°C (SEM 0.2°C) for athletic clothing, coveralls and NBCW overgarment respectively)] (P<0.05). No comparable difference in the rate of temperature increase for Tre was demonstrated, except that end-exercise Tre for the NBCW overgarment condition was significantly greater (0.5°C) than that for the athletic clothing condition. There was a drop in Tes during the initial minutes of recovery to sustained plateaus which were significantly (P<0.05) elevated above pre-exercise resting values by 0.6°C, 0.8°C and 1.0°C, for athletic clothing, coveralls, and NBCW overgarment, respectively. Post-exercise Tre decreased very gradually from end-exercise values during the 30-min recovery. Only the NBCW overgarment condition Tre was significantly elevated (0.3°C) above the athletic clothing condition (P<0.05). In conclusion, Tes is far more sensitive in reflecting the heat stress of different levels of insulation during exercise and post-exercise than Tre

  20. Core functional traits of bacterial communities in the Upper Mississippi River show limited variation in response to land cover

    PubMed Central

    Staley, Christopher; Gould, Trevor J.; Wang, Ping; Phillips, Jane; Cotner, James B.; Sadowsky, Michael J.

    2014-01-01

    Taxonomic characterization of environmental microbial communities via high-throughput DNA sequencing has revealed that patterns in microbial biogeography affect community structure. However, shifts in functional diversity related to variation in taxonomic composition are poorly understood. To overcome limitations due to the prohibitive cost of high-depth metagenomic sequencing, tools to infer functional diversity based on phylogenetic distributions of functional traits have been developed. In this study we characterized functional microbial diversity at 11 sites along the Mississippi River in Minnesota using both metagenomic sequencing and functional-inference-based (PICRUSt) approaches. This allowed us to determine how distance and variation in land cover throughout the river influenced the distribution of functional traits, as well as to validate PICRUSt inferences. The distribution and abundance of functional traits, by metagenomic analysis, were similar among sites, with a median standard deviation of 0.0002% among tier 3 functions in KEGG. Overall inferred functional variation was significantly different (P ≤ 0.035) between two water basins surrounded by agricultural vs. developed land cover, and abundances of bacterial orders that correlated with functional traits by metagenomic analysis were greater where abundances of the trait were inferred to be higher. PICRUSt inferences were significantly correlated (r = 0.147, P = 1.80 × 10−30) with metagenomic annotations. Discrepancies between metagenomic and PICRUSt taxonomic-functional relationships, however, suggested potential functional redundancy among abundant and rare taxa that impeded the ability to accurately assess unique functional traits among rare taxa at this sequencing depth. Results of this study suggest that a suite of “core functional traits” is conserved throughout the river and distributions of functional traits, rather than specific taxa, may shift in response to environmental

  1. Haze, clouds and limited sky visibility: polarotactic orientation of crickets under difficult stimulus conditions.

    PubMed

    Henze, Miriam J; Labhart, Thomas

    2007-09-01

    Field crickets (Gryllus campestris L.) are able to detect the orientation of the electric vector (e-vector) of linearly polarized light. They presumably use this sense to exploit the celestial polarization pattern for course control or navigation. Polarization vision in crickets can be tested by eliciting a spontaneous polarotactic response. Previously, wide and 100% polarized stimuli were employed to induce this behavior. However, field crickets live on meadows where the observation of the sky is strongly limited by surrounding vegetation. Moreover, degrees of polarization (d) in the natural sky are much lower than 100%. We have therefore investigated thresholds for the behavioral response to polarized light under conditions mimicking those experienced by the insects in the field. We show that crickets are able to rely on polarized stimuli of just 1 degrees diameter. We also provide evidence that they exploit polarization down to an (average) polarization level of less than 7%, irrespective of whether the stimulus is homogeneous, such as under haze, or patched, such as a sky spotted by clouds. Our data demonstrate that crickets can rely on skylight polarization even under unfavorable celestial conditions, emphasizing the significance of polarized skylight orientation for insects. PMID:17766304

  2. Upper limit for the D2H+ ortho-to-para ratio in the prestellar core 16293E (CHESS)

    NASA Astrophysics Data System (ADS)

    Vastel, C.; Caselli, P.; Ceccarelli, C.; Bacmann, A.; Lis, D. C.; Caux, E.; Codella, C.; Beckwith, J. A.; Ridley, T.

    2012-11-01

    The H_3^+ ion plays a key role in the chemistry of dense interstellar gas clouds where stars and planets are forming. The low temperatures and high extinctions of such clouds make direct observations of H_3^+ impossible, but lead to large abundances of H2D+ and D2H+, which are very useful probes of the early stages of star and planet formation. The ground-state rotational ortho-D2H+ 11,1-00,0 transition at 1476.6 GHz in the prestellar core 16293E has been searched for with the Herschel HIFI instrument, within the CHESS (Chemical HErschel Surveys of Star forming regions) Key Program. The line has not been detected at the 21 mK km s-1 level (3σ integrated line intensity). We used the ortho-H2D+ 11,0-11,1 transition and para-D2H+ 11,0-10,1 transition detected in this source to determine an upper limit on the ortho-to-para D2H+ ratio as well as the para-D2H+/ortho-H2D+ ratio from a non-local thermodynamic equilibrium analysis. The comparison between our chemical modeling and the observations suggests that the CO depletion must be high (larger than 100), with a density between 5 × 105 and 106 cm-3. Also the upper limit on the ortho-D2H+ line is consistent with a low gas temperature (~11 K) with a ortho-to-para ratio of 6 to 9, i.e. 2 to 3 times higher than the value estimated from the chemical modeling, making it impossible to detect this high frequency transition with the present state of the art receivers. The chemical network is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/547/A33Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  3. Cultivar Mixture Cropping Increased Water Use Efficiency in Winter Wheat under Limited Irrigation Conditions

    PubMed Central

    Wang, Yunqi; Zhang, Yinghua; Ji, Wei; Yu, Peng; Wang, Bin; Li, Jinpeng; Han, Meikun; Xu, Xuexin; Wang, Zhimin

    2016-01-01

    The effects of cultivar mixture cropping on yield, biomass, and water use efficiency (WUE) in winter wheat (Triticum aestivum L.) were investigated under non-irrigation (W0, no irrigation during growth stage), one time irrigation (W1, irrigation applied at stem elongation) and two times irrigation (W2, irrigation applied at stem elongation and anthesis) conditions. Nearly 90% of cultivar mixture cropping treatments experienced an increase in grain yield as compared with the mean of the pure stands under W0, those for W1 and W2 were 80% and 85%, respectively. Over 75% of cultivar mixture cropping treatments got greater biomass than the mean of the pure stands under the three irrigation conditions. Cultivar mixture cropping cost more water than pure stands under W0 and W1, whereas the water consumption under W2 decreased by 5.9%–6.8% as compared with pure stands. Approximately 90% of cultivar mixtures showed an increase of 5.4%–34.5% in WUE as compared with the mean of the pure stands, and about 75% of cultivar mixtures had 0.8%–28.5% higher WUE than the better pure stands under W0. Similarly, there were a majority of mixture cropping treatments with higher WUE than the mean and the better one of the pure stands under W1 and W2. On the whole, proper cultivar mixture cropping could increase yield and WUE, and a higher increase in WUE occurred under limited irrigation condition. PMID:27362563

  4. Kinetics of benzene biotransformation under microaerophilic and oxygen-limited conditions.

    PubMed

    Yerushalmi, Laleh; Lascourreges, Jean-Francois; Guiot, Serge R

    2002-08-01

    A special microbial consortium adapted to degrade petroleum hydrocarbons at limited availability of oxygen, transformed benzene, a highly toxic and carcinogenic contaminant of groundwater and soil, at low initial dissolved oxygen (DO) concentrations of 0.05-2 mg/L. The employed initial concentrations of dissolved oxygen were considerably lower than the previously reported values. Under these conditions, the overall transformation of benzene ranged from 34% +/- 1.7% to 100%, considerably higher than the theoretical predictions for complete mineralization of benzene based on the requirement of 3.08 mg oxygen/mg benzene. Unlike biotransformation that proceeded at the lowest examined DO concentration of 0.05 mg/L, the mineralization of benzene, defined by its conversion to CO(2) and water, required a minimum DO concentration of 0.2 mg/L. The mineralization of benzene under microaerophilic conditions (DO < 2 mg/L), ranged from 0.83% +/- 0.06% to 89% +/- 1.3%, which was less than the theoretical predictions at any given initial DO concentration. The regulatory effects of dissolved oxygen concentration or its partial pressure on the activities of enzymes catalyzing the biotransformation of aromatic hydrocarbons was postulated to account for the reduced mineralization of benzene. The ratio between the transformed benzene and the consumed oxygen increased with the decrease of initial DO concentration, reaching a value of 2.8, considerably higher than the theoretical value of 0.33 obtained for a complete aerobic oxidation of benzene. Phenol was the major and the most stable intermediate metabolite during the biotransformation of benzene at low concentrations of DO. While benzene transformation stopped after the depletion of oxygen in the experimental system, phenol continued to accumulate under strictly anaerobic conditions, indicating its formation from an alternative carbon source, possibly biomass. PMID:12115423

  5. Electromagnetic characterization of current transformer with toroidal core under sinusoidal conditions

    NASA Astrophysics Data System (ADS)

    Koprivica, Branko; Milovanovic, Alenka

    2016-04-01

    The aim of this paper is to present a new procedure for the electromagnetic analysis of a measuring current transformer under sinusoidal conditions in its electrical and magnetic circuit. The influence of the magnetic hysteresis has been taken into account using the measured inverse magnetization curve and phase lag between the time waveforms of the magnetic field and the magnetic induction. Using the proposed analysis, ratio and phase errors of the current transformer have been calculated. The results of the calculation have been compared with experimental results and a good agreement has been found.

  6. Permeability Changes of Coal Cores and Briquettes under Tri-Axial Stress Conditions

    NASA Astrophysics Data System (ADS)

    Wierzbicki, Mirosław; Konečný, Pavel; Kožušníková, Alena

    2014-12-01

    The paper is dealing with the permeability of coal in triaxial state of stress. The permeability of coal, besides coal's methane capacity, is the main parameter determining the quantity of methane inflow into underground excavations. The stress in a coal seam is one of the most important factors influencing coal permeability therefore the permeability measurements were performed in tri-axial state of stress. The hydrostatic three-axial state of stress was gradually increased from 5 MPa with steps of 5 MPa up to a maximum of 30 MPa. Nitrogen was applied as a gas medium in all experiments. The results of the permeability measurements of coal cores from the "Zofiówka" mine, Poland, and three mines from the Czech Republic are presented in this paper. As a "reference", permeability measurements were also taken for coal briquettes prepared from coal dust with defined porosity. It was confirmed that the decreasing porosity of coal briquettes affects the decreasing permeability. The advantage of experimentation on coal briquettes is its good repeatability. From the experimental results, an empirical relation between gas permeability and confining pressure has also been identified. The empirical relation for coal briquettes is in good correspondence with published results. However, for coal cores, the character of change differs. The influence of confining pressure has a different character and the decrease in permeability is stronger due to the increasing confining pressure Przepuszczalność węgla, oprócz pojemności sorpcyjnej względem metanu jest głównym parametrem określającym dopływ metanu do podziemnych wyrobiskach górniczych. W warunkach naturalnych wartość przepuszczalności jest ściśle związana ze stanem naprężenia w pokładzie węgla. W pracy przedstawiono wyniki pomiarów przepuszczalności wykonanych w trójosiowym stanie naprężenia. Hydrostatyczny trójosiowy stan naprężenia stopniowo zwiększano od 5 MPa do maksymalnie 30 MPa z krokiem

  7. Spatial heterogeneity of dechlorinating bacteria and limiting factors for in situ trichloroethene dechlorination revealed by analyses of sediment cores from a polluted field site.

    PubMed

    Dowideit, Kerstin; Scholz-Muramatsu, Heidrun; Miethling-Graff, Rona; Vigelahn, Lothar; Freygang, Martina; Dohrmann, Anja B; Tebbe, Christoph C

    2010-03-01

    Microbiological analyses of sediment samples were conducted to explore potentials and limitations for bioremediation of field sites polluted with chlorinated ethenes. Intact sediment cores, collected by direct push probing from a 35-ha contaminated area, were analyzed in horizontal layers. Cultivation-independent PCR revealed Dehalococcoides to be the most abundant 16S rRNA gene phylotype with a suspected potential for reductive dechlorination of the major contaminant trichloroethene (TCE). In declining abundances, Desulfitobacterium, Desulfuromonas and Dehalobacter were also detected. In TCE-amended sediment slurry incubations, 66% of 121 sediment samples were dechlorinating, among them one-third completely and the rest incompletely (end product cis-1,2-dichloroethene; cDCE). Both PCR and slurry analyses revealed highly heterogeneous horizontal and vertical distributions of the dechlorination potentials in the sediments. Complete reductive TCE dechlorination correlated with the presence of Dehalococcoides, accompanied by Acetobacterium and a relative of Trichococcus pasteurii. Sediment incubations under close to in situ conditions showed that a low TCE dechlorination activity could be stimulated by 7 mg L(-1) dissolved carbon for cDCE formation and by an additional 36 mg carbon (lactate) L(-1) for further dechlorination. The study demonstrates that the highly heterogeneous distribution of TCE degraders and their specific requirements for carbon and electrons are key issues for TCE degradation in contaminated sites. PMID:20041951

  8. Intracellular release of doxorubicin from core-crosslinked polypeptide micelles triggered by both pH and reduction conditions.

    PubMed

    Wu, Liangliang; Zou, Yan; Deng, Chao; Cheng, Ru; Meng, Fenghua; Zhong, Zhiyuan

    2013-07-01

    Reduction and pH dual-sensitive reversibly core-crosslinked polypeptide micelles were developed from lipoic acid (LA) and cis-1,2-cyclohexanedicarboxylic acid (CCA) decorated poly(ethylene glycol)-b-poly(L-lysine) (PEG-P(LL-CCA/LA)) block copolymers for active loading and triggered intracellular release of doxorubicin (DOX). PEG-P(LL18-CCA4/LA14) and PEG-P(LL18-CCA8/LA10) (M(n PEG) = 5.0 kg/mol) formed nano-sized micelles that were readily crosslinked in the presence of a catalytic amount of dithiothreitol (DTT) in phosphate buffer (pH 7.4, 10 mM). PEG-P(LL18-CCA4/LA14) micelles displayed an elevated DOX loading over PEG-P(LL14-LA14) controls likely due to presence of ionic interactions between DOX and CCA. These core-crosslinked polypeptide micelles while exhibiting high stability against extensive dilution and high salt concentration were quickly dissociated into unimers in the presence of 10 mM DTT. The in vitro release studies showed that DOX release from PEG-P(LL18-CCA4/LA14) micelles at pH 7.4 and 37 °C was significantly inhibited by crosslinking (i.e. less than 20% release in 24 h). The release of DOX was, however, doubled under endosomal pH of 5.0, possibly triggered by cleavage of the acid-labile amide bonds of CCA. In particular, rapid DOX release was observed under a reductive condition containing 10 mm glutathione (GSH), in which 86.0% and 96.7% of DOX were released in 24 h at pH 7.4 and 5.0, respectively, under otherwise the same conditions. MTT assays demonstrated that these core-crosslinked polypeptide micelles were practically non-toxic up to a tested concentration of 1.0 mg/mL, while DOX-loaded micelles caused pronounced cytotoxic effects to HeLa and HepG2 tumor cells with IC50 (inhibitory concentration to produce 50% cell death) of ca. 12.5 μg DOX equiv/mL following 48 h incubation. Confocal microscopy observations revealed that DOX-loaded crosslinked PEG-P(LL18-CCA4/LA14) micelles more efficiently delivered and released DOX into the nuclei of

  9. Synthesis of Xenon and Iron/Nickel Intermetallic Compounds Under the Thermodynamic Conditions of the Earth's Core.

    NASA Astrophysics Data System (ADS)

    Stavrou, E.; Zaug, J. M.; Crowhurst, J.; Lobanov, S.; Goncharov, A. F.; Prakapenka, V.; Prescher, C.; Yao, Y.; Liu, H.; Dai, Z.; Oleynik, I.; Steele, B.; Cong, K. N.

    2015-12-01

    The lower Xe abundance in Earth's atmosphere, in comparison to other noble gases like Ar and Kr, is one of the most challenging open questions in geosciences [1]. The origin of the so-called "missing Xe paradox" is usually attributed to the inclusion of Xe in the interior of Earth[2]. Although Xe is known to form compounds (e.g. with hydrogen, oxygen), none of them can be related with Earth's interior. Indeed, only a very low amount of Xe can be incorporated in silica at <1 GPa and 500K [3]. On the other hand, experimental attempts have failed to trace possible formation of Fe-Xe compounds up to 155 GPa and bellow 2500K [4]. A very recent theoretical study, suggests that Xe-Ni and Xe-Fe compounds can form at thermodynamic conditions representative of Earth's outer core [5]. Here we explored the possible formation of stable compounds in the Xe-Fe/Ni system at thermodynamic conditions representative of Earth's outer core starting from the following mixtures: a) Xe-Fe, b) Xe-Ni and c) Xe and an Fe/Ni alloy representative of Earth's core (ca 6% Ni). Using in situ synchrotron X-ray diffraction and Raman spectroscopy we report the formation of: a) a XeNi3 compound, in the form of a CrNi3-type FCC solid solution, above 150 GPa and 1500K, b) a Xe(Fe/Ni)3 compound, tentatively characterized as an orthorhombic NbPd3-type solid solution, above 190 GPa and 2000K and c) a still not completely characterized XeFexcompound above 180 GPa and 2000K. This work provides a plausible explanation of the "missing Xe paradox", and underscores the importance of understanding the novel rules of high-pressure chemistry for an improved understanding of the structure and chemistry of the Earth's core. [1] E. Anders, E. and T. Owen, Science 198, 453 (1977). [2] Caldwell, W. A. et al.,Science 277, 930 (1997). [3] C. Sanloup et al.,Science 310, 1174(2005). [4] D. Nishio-Hamane et al.,Geophys. Res. Lett. 37, L04302 (2010). [5] L. Zhu et al., Nature chemistry 6, 664 (2014).

  10. Parameter identification of the SWAT model on the BANI catchment (West Africa) under limited data condition

    NASA Astrophysics Data System (ADS)

    Chaibou Begou, Jamilatou; Jomaa, Seifeddine; Benabdallah, Sihem; Rode, Michael

    2015-04-01

    Due to the climate change, drier conditions have prevailed in West Africa, since the seventies, and the consequences are important on water resources. In order to identify and implement management strategies of adaptation to climate change in the sector of water, it is crucial to improve our physical understanding of water resources evolution in the region. To this end, hydrologic modelling is an appropriate tool for flow predictions under changing climate and land use conditions. In this study, the applicability and performance of the recent version of Soil and Water Assessment Tool (SWAT2012) model were tested on the Bani catchment in West Africa under limited data condition. Model parameters identification was also tested using one site and multisite calibration approaches. The Bani is located in the upper part of the Niger River and drains an area of about 101, 000 km2 at the outlet of Douna. The climate is tropical, humid to semi-arid from the South to the North with an average annual rainfall of 1050 mm (period 1981-2000). Global datasets were used for the model setup such as: USGS hydrosheds DEM, USGS LCI GlobCov2009 and the FAO Digital Soil Map of the World. Daily measured rainfall from nine rain gauges and maximum and minimum temperature from five weather stations covering the period 1981-1997 were used for model setup. Sensitivity analysis, calibration and validation are performed within SWATCUP using GLUE procedure at Douna station first (one site calibration), then at three additional internal stations, Bougouni, Pankourou and Kouoro1 (multi-site calibration). Model parameters were calibrated at daily time step for the period 1983-1992, then validated for the period 1993-1997. A period of two years (1981-1982) was used for model warming up. Results of one-site calibration showed that the model performance is evaluated by 0.76 and 0.79 for Nash-Sutcliffe (NS) and correlation coefficient (R2), respectively. While for the validation period the performance

  11. Performance of Airborne Precision Spacing Under Realistic Wind Conditions and Limited Surveillance Range

    NASA Technical Reports Server (NTRS)

    Wieland, Frederick; Santos, Michel; Krueger, William; Houston, Vincent E.

    2011-01-01

    With the expected worldwide increase of air traffic during the coming decade, both the Federal Aviation Administration's (FAA's) Next Generation Air Transportation System (NextGen), as well as Eurocontrol's Single European Sky ATM Research (SESAR) program have, as part of their plans, air traffic management (ATM) solutions that can increase performance without requiring time-consuming and expensive infrastructure changes. One such solution involves the ability of both controllers and flight crews to deliver aircraft to the runway with greater accuracy than they can today. Previous research has shown that time-based spacing techniques, wherein the controller assigns a time spacing to each pair of arriving aircraft, can achieve this goal by providing greater runway delivery accuracy and producing a concomitant increase in system-wide performance. The research described herein focuses on one specific application of time-based spacing, called Airborne Precision Spacing (APS), which has evolved over the past ten years. This research furthers APS understanding by studying its performance with realistic wind conditions obtained from atmospheric sounding data and with realistic wind forecasts obtained from the Rapid Update Cycle (RUC) short-range weather forecast. In addition, this study investigates APS performance with limited surveillance range, as provided by the Automatic Dependent Surveillance-Broadcast (ADS-B) system, and with an algorithm designed to improve APS performance when ADS-B surveillance data is unavailable. The results presented herein quantify the runway threshold delivery accuracy of APS under these conditions, and also quantify resulting workload metrics such as the number of speed changes required to maintain spacing.

  12. First-principles Exploration of Crystal Structures of Pure Iron at Earth’s Inner Core Conditions

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Tsuchiya, T.; Tsuchiya, J.

    2009-12-01

    Determining the structure of Earth’s inner core has been a long standing challenge for geoscience. Iron has been considered as a main composition of the inner core and expected to exist as an iron-nickel-light elements alloy there. In order to get some information about the structure of the inner core, pure iron has been also investigated by many experimental and ab-initio studies. Pure iron has been expected to take the hexagonal close-packed (hcp) structure at the inner core conditions (Jephcoat and Olson, Nature 325, 332-335, 1987.; Mao et al., Nature 396, 741-743, 1998.; Fiquet et al., Science 291, 468-471, 2001.; Uchida et al., J. Geophys. Res. 106, 21799-21810, 2001.). On the other hand, the face-centered cubic (fcc) structure (Mikhaylushkin et al., Phys. Rev. Lett. 99, 165505-165508, 2007.) and the body-centered cubic structure (Vocadlo et al., Phys. Earth Planet In. 170, 52-59, 2008.) have been also considered as the candidate structures. In this study, first we explored the crystal structures of pure iron at 400 GPa by our originally developing algorithm for the structure exploration, Free Energy Surface Trekking (FEST). In FEST, using a minus sign of driving force acting on a simulation cell, we force a system to climb up to a ridge of a free energy surface (ascent-run). Then, flipping the negative driving force to an original one, we make the system go down to a neighboring potential well (descent-run). The more different directions we examine in the ascent-run, the more accurate topography we capture of free energy surface. For the exploration of the ultrahigh-pressure structures of pure iron, we used 16 atoms supercell and explored 64 pathways around the initial local minimum corresponding to hcp. As the result, 30 pathways lead to a complex hcp (chcp) structure, which has ABCACABCBCAB stacking with 12 layers. Other 33 pathways lead to hcp and 1 pathway fcc. The enthalpy of chcp was found higher than that of hcp but only by 4 mRy/atom and lower than

  13. Conditions of Core Formation in the Early Earth: Single Stage or Heterogeneous Accretion?

    NASA Technical Reports Server (NTRS)

    Righter, Kevin

    2010-01-01

    Since approx.1990 high pressure and temperature (PT) experiments on metal-silicate systems have showed that partition coefficients [D(met/sil)] for siderophile (iron-loving) elements are much different than those measured at low PT conditions [1,2]. The high PT data have been used to argue for a magma ocean during growth of the early Earth [3,4]. In the ensuing decades there have been hundreds of new experiments carried out and published on a wide range of siderophile elements (> 80 experiments published for Ni, Co, Mo, W, P, Mn, V, Cr, Ga, Cu and Pd). At the same time several different models have been advanced to explain the siderophile elements in Earth's mantle: a) shallow depth magma ocean 25-30 GPa [3,5]; b) deep magma ocean; up to 50 GPa [6,7], and c) early reduced and later oxidized magma ocean [8,9]. Some studies have drawn conclusions based on a small subset of siderophile elements, or a set of elements that provides little leverage on the big picture (like slightly siderophile elements), and no single study has attempted to quantitatively explain more than 5 elements at a time. The purpose of this abstract is to identify issues that have lead to a difference in interpretation, and to present updated predictive expressions based on new experimental data. The resulting expressions will be applied to the siderophile element depletions in Earth's upper mantle.

  14. Biocorrosion and biofilm formation in a nutrient limited heating system subjected to alternating microaerophilic conditions.

    PubMed

    Kjellerup, B V; Kjeldsen, K U; Lopes, F; Abildgaard, L; Ingvorsen, K; Frølund, B; Sowers, K R; Nielsen, P H

    2009-11-01

    Severe biofilm formation and biocorrosion have been observed in heating systems even when the water quality complied with existing standards. The coupling between water chemistry, biofilm formation, species composition, and biocorrosion in a heating system was investigated by adding low concentrations of nutrients and oxygen under continuous and alternating dosing regimes. Molecular analysis of 16S rRNA gene fragments demonstrated that the amendments did not cause changes in the overall bacterial community composition. The combined alternating dosing of nutrients and oxygen caused increased rates of pitting (bio-) corrosion. Detection of bacteria involved in sulfide production and oxidation by retrieval of the functional dsrAB and apsA genes revealed the presence of Gram-positive sulfate- and sulfite-reducers and an unknown sulfur-oxidizer. Therefore, to control biocorrosion, sources of oxygen and nutrients must be limited, since the effect of the alternating operational conditions apparently is more important than the presence of potentially corrosive biofilm bacteria. PMID:20183131

  15. Do water-limiting conditions predispose Norway spruce to bark beetle attack?

    PubMed

    Netherer, Sigrid; Matthews, Bradley; Katzensteiner, Klaus; Blackwell, Emma; Henschke, Patrick; Hietz, Peter; Pennerstorfer, Josef; Rosner, Sabine; Kikuta, Silvia; Schume, Helmut; Schopf, Axel

    2015-02-01

    Drought is considered to enhance susceptibility of Norway spruce (Picea abies) to infestations by the Eurasian spruce bark beetle (Ips typographus, Coleoptera: Curculionidae), although empirical evidence is scarce. We studied the impact of experimentally induced drought on tree water status and constitutive resin flow, and how physiological stress affects host acceptance and resistance. We established rain-out shelters to induce both severe (two full-cover plots) and moderate (two semi-cover plots) drought stress. In total, 18 sample trees, which were divided equally between the above treatment plots and two control plots, were investigated. Infestation was controlled experimentally using a novel 'attack box' method. Treatments influenced the ratios of successful and defended attacks, but predisposition of trees to infestation appeared to be mainly driven by variations in stress status of the individual trees over time. With increasingly negative twig water potentials and decreasing resin exudation, the defence capability of the spruce trees decreased. We provide empirical evidence that water-limiting conditions impair Norway spruce resistance to bark beetle attack. Yet, at the same time our data point to reduced host acceptance by I. typographus with more extreme drought stress, indicated by strongly negative pre-dawn twig water potentials. PMID:25417785

  16. Do water-limiting conditions predispose Norway spruce to bark beetle attack?

    PubMed Central

    Netherer, Sigrid; Matthews, Bradley; Katzensteiner, Klaus; Blackwell, Emma; Henschke, Patrick; Hietz, Peter; Pennerstorfer, Josef; Rosner, Sabine; Kikuta, Silvia; Schume, Helmut; Schopf, Axel

    2015-01-01

    Drought is considered to enhance susceptibility of Norway spruce (Picea abies) to infestations by the Eurasian spruce bark beetle (Ips typographus, Coleoptera: Curculionidae), although empirical evidence is scarce. We studied the impact of experimentally induced drought on tree water status and constitutive resin flow, and how physiological stress affects host acceptance and resistance. We established rain-out shelters to induce both severe (two full-cover plots) and moderate (two semi-cover plots) drought stress. In total, 18 sample trees, which were divided equally between the above treatment plots and two control plots, were investigated. Infestation was controlled experimentally using a novel ‘attack box’ method. Treatments influenced the ratios of successful and defended attacks, but predisposition of trees to infestation appeared to be mainly driven by variations in stress status of the individual trees over time. With increasingly negative twig water potentials and decreasing resin exudation, the defence capability of the spruce trees decreased. We provide empirical evidence that water-limiting conditions impair Norway spruce resistance to bark beetle attack. Yet, at the same time our data point to reduced host acceptance byI. typographus with more extreme drought stress, indicated by strongly negative pre-dawn twig water potentials. PMID:25417785

  17. Conditioned Medium From Human Amniotic Mesenchymal Stromal Cells Limits Infarct Size and Enhances Angiogenesis

    PubMed Central

    Danieli, Patrizia; Malpasso, Giuseppe; Ciuffreda, Maria Chiara; Cervio, Elisabetta; Calvillo, Laura; Copes, Francesco; Pisano, Federica; Mura, Manuela; Kleijn, Lennaert; de Boer, Rudolf A.; Viarengo, Gianluca; Rosti, Vittorio; Spinillo, Arsenio; Roccio, Marianna

    2015-01-01

    The paracrine properties of human amniotic membrane-derived mesenchymal stromal cells (hAMCs) have not been fully elucidated. The goal of the present study was to elucidate whether hAMCs can exert beneficial paracrine effects on infarcted rat hearts, in particular through cardioprotection and angiogenesis. Moreover, we aimed to identify the putative active paracrine mediators. hAMCs were isolated, expanded, and characterized. In vitro, conditioned medium from hAMC (hAMC-CM) exhibited cytoprotective and proangiogenic properties. In vivo, injection of hAMC-CM into infarcted rat hearts limited the infarct size, reduced cardiomyocyte apoptosis and ventricular remodeling, and strongly promoted capillary formation at the infarct border zone. Gene array analysis led to the identification of 32 genes encoding for the secreted factors overexpressed by hAMCs. Among these, midkine and secreted protein acidic and rich in cysteine were also upregulated at the protein level. Furthermore, high amounts of several proangiogenic factors were detected in hAMC-CM by cytokine array. Our results strongly support the concept that the administration of hAMC-CM favors the repair process after acute myocardial infarction. PMID:25824141

  18. Conditioned medium from human amniotic mesenchymal stromal cells limits infarct size and enhances angiogenesis.

    PubMed

    Danieli, Patrizia; Malpasso, Giuseppe; Ciuffreda, Maria Chiara; Cervio, Elisabetta; Calvillo, Laura; Copes, Francesco; Pisano, Federica; Mura, Manuela; Kleijn, Lennaert; de Boer, Rudolf A; Viarengo, Gianluca; Rosti, Vittorio; Spinillo, Arsenio; Roccio, Marianna; Gnecchi, Massimiliano

    2015-05-01

    The paracrine properties of human amniotic membrane-derived mesenchymal stromal cells (hAMCs) have not been fully elucidated. The goal of the present study was to elucidate whether hAMCs can exert beneficial paracrine effects on infarcted rat hearts, in particular through cardioprotection and angiogenesis. Moreover, we aimed to identify the putative active paracrine mediators. hAMCs were isolated, expanded, and characterized. In vitro, conditioned medium from hAMC (hAMC-CM) exhibited cytoprotective and proangiogenic properties. In vivo, injection of hAMC-CM into infarcted rat hearts limited the infarct size, reduced cardiomyocyte apoptosis and ventricular remodeling, and strongly promoted capillary formation at the infarct border zone. Gene array analysis led to the identification of 32 genes encoding for the secreted factors overexpressed by hAMCs. Among these, midkine and secreted protein acidic and rich in cysteine were also upregulated at the protein level. Furthermore, high amounts of several proangiogenic factors were detected in hAMC-CM by cytokine array. Our results strongly support the concept that the administration of hAMC-CM favors the repair process after acute myocardial infarction. PMID:25824141

  19. Kinetically limited weathering at low denudation rates in semiarid climatic conditions

    NASA Astrophysics Data System (ADS)

    Schoonejans, Jérôme; Vanacker, Veerle; Opfergelt, Sophie; Ameijeiras-Mariño, Yolanda; Christl, Marcus

    2016-02-01

    Biogeochemical cycling within the Critical Zone depends on the interactions between minerals and fluids controlling chemical weathering and physical erosion rates. In this study, we explore the role of water availability in controlling soil chemical weathering in semiarid climatic conditions. Weathering rates and intensities were evaluated for nine soil profiles located on convex ridge crests of three mountain ranges in the Spanish Betic Cordillera. We combine a geochemical mass balance with 10Be cosmogenic nuclides to constrain chemical weathering intensities and long-term denudation rates. As such, this study presents new data on chemical weathering and 10Be-derived denudation for understudied semiarid climate systems. In the Betic Cordillera, chemical weathering intensities are relatively low (~5 to 30% of the total denudation of the soil) and negatively correlated with the magnitude of the water deficit in soils. Chemical mass losses are inversely related to denudation rates (14-109 mm/kyr) and positively to soil thickness (14-58 cm); these results are consistent with kinetic limitation of chemical weathering rates. A worldwide compilation of chemical weathering data suggests that soil water balance may regulate the coupling between chemical weathering and physical erosion by modulating soil solute fluxes. Therefore, future landscape evolution models that seek to link chemical weathering and physical erosion should include soil water flux as an essential driver of weathering.

  20. Measurements of core and compressed-shell temperature and density conditions in thick-wall target implosions at the OMEGA laser facility

    SciTech Connect

    Florido, R.; Mancini, R. C.; Nagayama, T.; Tommasini, R.; Delettrez, J. A.; Regan, S. P.; Yaakobi, B.

    2011-06-15

    A spectroscopic method is discussed to measure core and compressed-shell conditions in thick-wall plastic-shell implosions filled with deuterium and a tracer amount of argon. Simultaneous observation over a broad photon energy range of the argon line emission and the attenuation and self-emission effects of the compressed shell confining the core yields enough information to extract average temperature and density conditions in both core and compressed shell. The spectroscopic analysis also provides an estimate of the target areal density which is an important characteristic of inertial confinement fusion implosions.

  1. Constraints on Earth’s inner core composition inferred from measurements of the sound velocity of hcp-iron in extreme conditions

    PubMed Central

    Sakamaki, Tatsuya; Ohtani, Eiji; Fukui, Hiroshi; Kamada, Seiji; Takahashi, Suguru; Sakairi, Takanori; Takahata, Akihiro; Sakai, Takeshi; Tsutsui, Satoshi; Ishikawa, Daisuke; Shiraishi, Rei; Seto, Yusuke; Tsuchiya, Taku; Baron, Alfred Q. R.

    2016-01-01

    Hexagonal close-packed iron (hcp-Fe) is a main component of Earth’s inner core. The difference in density between hcp-Fe and the inner core in the Preliminary Reference Earth Model (PREM) shows a density deficit, which implies an existence of light elements in the core. Sound velocities then provide an important constraint on the amount and kind of light elements in the core. Although seismological observations provide density–sound velocity data of Earth’s core, there are few measurements in controlled laboratory conditions for comparison. We report the compressional sound velocity (VP) of hcp-Fe up to 163 GPa and 3000 K using inelastic x-ray scattering from a laser-heated sample in a diamond anvil cell. We propose a new high-temperature Birch’s law for hcp-Fe, which gives us the VP of pure hcp-Fe up to core conditions. We find that Earth’s inner core has a 4 to 5% smaller density and a 4 to 10% smaller VP than hcp-Fe. Our results demonstrate that components other than Fe in Earth’s core are required to explain Earth’s core density and velocity deficits compared to hcp-Fe. Assuming that the temperature effects on iron alloys are the same as those on hcp-Fe, we narrow down light elements in the inner core in terms of the velocity deficit. Hydrogen is a good candidate; thus, Earth’s core may be a hidden hydrogen reservoir. Silicon and sulfur are also possible candidates and could show good agreement with PREM if we consider the presence of some melt in the inner core, anelasticity, and/or a premelting effect. PMID:26933678

  2. Little Ice Age climate and oceanic conditions of the Ross Sea, Antarctica from a coastal ice core record

    NASA Astrophysics Data System (ADS)

    Rhodes, R. H.; Bertler, N. A. N.; Baker, J. A.; Steen-Larsen, H. C.; Sneed, S. B.; Morgenstern, U.; Johnsen, S. J.

    2012-07-01

    Increasing paleoclimatic evidence suggests that the Little Ice Age (LIA) was a global climate change event. Understanding the forcings and associated climate system feedbacks of the LIA is made difficult by the scarcity of Southern Hemisphere paleoclimate records. We use a new glaciochemical record of a coastal ice core from Mt. Erebus Saddle, Antarctica, to reconstruct atmospheric and oceanic conditions in the Ross Sea sector of Antarctica over the past five centuries. The LIA is identified in stable isotope (δD) and lithophile element records, which respectively demonstrate that the region experienced 1.6 ± 1.4 °C cooler average temperatures prior to 1850 AD than during the last 150 yr and strong (>57 m s-1) prevailing katabatic winds between 1500 and 1800 AD. Al and Ti concentration increases of an order of magnitude (>120 ppb Al) are linked to enhanced aeolian transport of complex silicate minerals and represent the strongest katabatic wind events of the LIA. These events are associated with three 12-30 yr intervals of cooler temperatures at ca. 1690 AD, 1770 AD and 1840 AD. Furthermore, ice core concentrations of the biogenic sulphur species MS- suggest that biological productivity in the Ross Sea polynya was ~80% higher prior to 1875 AD than at any subsequent time. We propose that cooler Antarctic temperatures promoted stronger katabatic winds across the Ross Ice Shelf, resulting in an enlarged Ross Sea polynya during the LIA.

  3. Limited Expansion of the New Self-Expandable Transcathether Aortic Valve Prosthesis (CoreValve Evolut R).

    PubMed

    Serio, Daniela; Doss, Mirko; Kim, Won-Keun; Möllmann, Helge; Walther, Thomas

    2016-05-01

    Transcatheter aortic valve implantation (TAVI) has been established as a therapeutic option in patients with a high procedural risk presenting with severe aortic stenosis. Recent improvements of TAVI technology made it possible to treat degenerated bioprosthesis using the valve-in-valve implantation concept. The self-expanding CoreValve (Medtronic, Minneapolis, MN) prosthesis has recently been redesigned and was introduced into clinical practice. We report a case of a not fully expanded Medtronic CoreValve Evolut R after deploying a 26 mm prosthesis into a degenerated 25 mm Carpentier-Edwards Perimount prosthesis. PMID:27106459

  4. Metabolomic Profiling of 13 Diatom Cultures and Their Adaptation to Nitrate-Limited Growth Conditions

    PubMed Central

    Bromke, Mariusz A.; Sabir, Jamal S.; Alfassi, Fahad A.; Hajarah, Nahid H.; Kabli, Saleh A.; Al-Malki, Abdulrahman L.; Ashworth, Matt P.; Méret, Michaël; Jansen, Robert K.; Willmitzer, Lothar

    2015-01-01

    Diatoms are very efficient in their use of available nutrients. Changes in nutrient availability influence the metabolism and the composition of the cell constituents. Since diatoms are valuable candidates to search for oil producing algae, measurements of diatom-produced compounds can be very useful for biotechnology. In order to explore the diversity of lipophilic compounds produced by diatoms, we describe the results from an analysis of 13 diatom strains. With the help of a lipidomics platform, which combines an UPLC separation with a high resolution/high mass accuracy mass spectrometer, we were able to measure and annotate 142 lipid species. Out of these, 32 were present in all 13 cultures. The annotated lipid features belong to six classes of glycerolipids. The data obtained from the measurements were used to create lipidomic profiles. The metabolomic overview of analysed cultures is amended by the measurement of 96 polar compounds. To further increase the lipid diversity and gain insight into metabolomic adaptation to nitrogen limitation, diatoms were cultured in media with high and low concentrations of nitrate. The growth in nitrogen-deplete or nitrogen-replete conditions affects metabolite accumulation but has no major influence on the species-specific metabolomic profile. Thus, the genetic component is stronger in determining metabolic patterns than nitrogen levels. Therefore, lipid profiling is powerful enough to be used as a molecular fingerprint for diatom cultures. Furthermore, an increase of triacylglycerol (TAG) accumulation was observed in low nitrogen samples, although this trend was not consistent across all 13 diatom strains. Overall, our results expand the current understanding of metabolomics diversity in diatoms and confirm their potential value for producing lipids for either bioenergy or as feed stock. PMID:26440112

  5. Valence and metal/silicate partitioning of Mo: Implications for conditions of Earth accretion and core formation

    NASA Astrophysics Data System (ADS)

    Righter, K.; Danielson, L. R.; Pando, K. M.; Shofner, G. A.; Sutton, S. R.; Newville, M.; Lee, C.-T.

    2016-03-01

    To better understand and predict the partition coefficient of Mo at the conditions of the deep interior of Earth and other terrestrial planets or bodies, we have undertaken new measurements of the valence and partitioning of Mo. X-ray absorption near edge structure (XANES) K-edge spectra for Mo have been measured in a series of Fe-bearing glasses produced at 1 bar and higher PT conditions. High pressure experiments have been carried out up to 19 GPa in order to better understand the effect of pressure on Mo partitioning. And, finally, a series of experiments at very low fO2 conditions and high Si content metallic liquids has been carried out to constrain the effect of Si on the partitioning of Mo between metallic liquids and silicate melt. The valence measurements demonstrate that Mo undergoes a transition from 4+ to 6+ near IW-1, in general agreement with previous 1 bar studies on FeO-free silicate melts. High pressure experiments demonstrate a modest pressure dependence of D (Mo) metal/silicate and, combined with previous results, show a significant decrease with pressure that must be quantified in any predictive expression. Finally, the effect of dissolved Si in Fe-rich metallic liquid is to decrease D (Mo) significantly, as suggested by previous work in metallurgical systems. The effect of pressure, temperature, oxygen fugacity, metallic liquid composition, and silicate melt composition can be quantified by using multiple linear regression of available experimental data for Mo. Our XANES results show that Mo will be 4+ at conditions of core formation, so only experiments carried out at fO2 of IW-1 and lower were used in the regressions. Application of predictive expressions to Earth accretion shows that D (Mo) decreases to values consistent with an equilibrium scenario for early Earth core-mantle. The Mo content of the primitive upper mantle (PUM) can be attained by metal-silicate equilibrium involving S-, C-, and Si-bearing metallic liquid, and peridotite

  6. Bottom-up design and synthesis of limit size lipid nanoparticle systems with aqueous and triglyceride cores using millisecond microfluidic mixing.

    PubMed

    Zhigaltsev, Igor V; Belliveau, Nathan; Hafez, Ismail; Leung, Alex K K; Huft, Jens; Hansen, Carl; Cullis, Pieter R

    2012-02-21

    Limit size systems are defined as the smallest achievable aggregates compatible with the packing of the molecular constituents in a defined and energetically stable structure. Here we report the use of rapid microfluidic mixing for the controlled synthesis of two types of limit size lipid nanoparticle (LNP) systems, having either polar or nonpolar cores. Specifically, limit size LNP consisting of 1-palmitoyl, 2-oleoyl phosphatidylcholine (POPC), cholesterol and the triglyceride triolein were synthesized by mixing a stream of ethanol containing dissolved lipid with an aqueous stream, employing a staggered herringbone micromixer. Millisecond mixing of aqueous and ethanol streams at high flow rate ratios (FRR) was used to rapidly increase the polarity of the medium, driving bottom-up synthesis of limit size LNP systems by spontaneous assembly. For POPC/triolein systems the limit size structures consisted of a hydrophobic core of triolein surrounded by a monolayer of POPC where the diameter could be rationally engineered over the range 20-80 nm by varying the POPC/triolein ratio. In the case of POPC and POPC/cholesterol (55/45; mol/mol) the limit size systems achieved were bilayer vesicles of approximately 20 and 40 nm diameter, respectively. We further show that doxorubicin, a representative weak base drug, can be efficiently loaded and retained in limit size POPC LNP, establishing potential utility as drug delivery systems. To our knowledge this is the first report of stable triglyceride emulsions in the 20-50 nm size range, and the first time vesicular systems in the 20-50 nm size range have been generated by a scalable manufacturing method. These results establish microfluidic mixing as a powerful and general approach to access novel LNP systems, with both polar or nonpolar core structures, in the sub-100 nm size range. PMID:22268499

  7. 76 FR 10489 - Special Conditions: Bell Helicopter Textron Canada Limited Model 407 Helicopter, Installation of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-25

    .../Stabilization Augmentation System (AP/SAS) that has potential failure conditions with more severe adverse... conditions contain the added safety standards the Administrator considers necessary to ensure the failures... independent of this system. However, the possible failure conditions for this system, and their effect...

  8. Capillary ion chromatography with on-column focusing for ultra-trace analysis of methanesulfonate and inorganic anions in limited volume Antarctic ice core samples.

    PubMed

    Rodriguez, Estrella Sanz; Poynter, Sam; Curran, Mark; Haddad, Paul R; Shellie, Robert A; Nesterenko, Pavel N; Paull, Brett

    2015-08-28

    Preservation of ionic species within Antarctic ice yields a unique proxy record of the Earth's climate history. Studies have been focused until now on two proxies: the ionic components of sea salt aerosol and methanesulfonic acid. Measurement of the all of the major ionic species in ice core samples is typically carried out by ion chromatography. Former methods, whilst providing suitable detection limits, have been based upon off-column preconcentration techniques, requiring larger sample volumes, with potential for sample contamination and/or carryover. Here, a new capillary ion chromatography based analytical method has been developed for quantitative analysis of limited volume Antarctic ice core samples. The developed analytical protocol applies capillary ion chromatography (with suppressed conductivity detection) and direct on-column sample injection and focusing, thus eliminating the requirement for off-column sample preconcentration. This limits the total sample volume needed to 300μL per analysis, allowing for triplicate sample analysis with <1mL of sample. This new approach provides a reliable and robust analytical method for the simultaneous determination of organic and inorganic anions, including fluoride, methanesulfonate, chloride, sulfate and nitrate anions. Application to composite ice-core samples is demonstrated, with coupling of the capillary ion chromatograph to high resolution mass spectrometry used to confirm the presence and purity of the observed methanesulfonate peak. PMID:26206628

  9. Exprimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions.

    NASA Technical Reports Server (NTRS)

    Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

    2015-01-01

    NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency for large gas turbine engines. Under ERA, the highly loaded core compressor technology program attempts to realize the fuel burn reduction goal by increasing overall pressure ratio of the compressor to increase thermal efficiency of the engine. Study engines with overall pressure ratio of 60 to 70 are now being investigated. This means that the high pressure compressor would have to almost double in pressure ratio while keeping a high level of efficiency. NASA and GE teamed to address this challenge by testing the first two stages of an advanced GE compressor designed to meet the requirements of a very high pressure ratio core compressor. Previous test experience of a compressor which included these front two stages indicated a performance deficit relative to design intent. Therefore, the current rig was designed to run in 1-stage and 2-stage configurations in two separate tests to assess whether the bow shock of the second rotor interacting with the upstream stage contributed to the unpredicted performance deficit, or if the culprit was due to interaction of rotor 1 and stator 1. Thus, the goal was to fully understand the stage 1 performance under isolated and multi-stage conditions, and additionally to provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to understand fluid dynamics loss source mechanisms due to rotor shock interaction and endwall losses. This paper will present the description of the compressor test article and its measured performance and operability, for both the single stage and two stage configurations. We focus the paper on measurements at 97% corrected speed with design intent vane setting angles.

  10. Experimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions

    NASA Technical Reports Server (NTRS)

    Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

    2015-01-01

    NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency of large gas turbine engines. Under ERA the task for a High Pressure Ratio Core Technology program calls for a higher overall pressure ratio of 60 to 70. This mean that the HPC would have to almost double in pressure ratio and keep its high level of efficiency. The challenge is how to match the corrected mass flow rate of the front two supersonic high reaction and high corrected tip speed stages with a total pressure ratio of 3.5. NASA and GE teamed to address this challenge by using the initial geometry of an advanced GE compressor design to meet the requirements of the first 2 stages of the very high pressure ratio core compressor. The rig was configured to run as a 2 stage machine, with Strut and IGV, Rotor 1 and Stator 1 run as independent tests which were then followed by adding the second stage. The goal is to fully understand the stage performances under isolated and multi-stage conditions and fully understand any differences and provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to isolate fluid dynamics loss source mechanisms due to interaction and endwalls. The paper will present the description of the compressor test article, its predicted performance and operability, and the experimental results for both the single stage and two stage configurations. We focus the detailed measurements on 97 and 100 of design speed at 3 vane setting angles.

  11. Moisture rivals temperature in limiting photosynthesis by trees establishing beyond their cold-edge range limit under ambient and warmed conditions.

    PubMed

    Moyes, Andrew B; Germino, Matthew J; Kueppers, Lara M

    2015-09-01

    Climate change is altering plant species distributions globally, and warming is expected to promote uphill shifts in mountain trees. However, at many cold-edge range limits, such as alpine treelines in the western United States, tree establishment may be colimited by low temperature and low moisture, making recruitment patterns with warming difficult to predict. We measured response functions linking carbon (C) assimilation and temperature- and moisture-related microclimatic factors for limber pine (Pinus flexilis) seedlings growing in a heating × watering experiment within and above the alpine treeline. We then extrapolated these response functions using observed microclimate conditions to estimate the net effects of warming and associated soil drying on C assimilation across an entire growing season. Moisture and temperature limitations were each estimated to reduce potential growing season C gain from a theoretical upper limit by 15-30% (c. 50% combined). Warming above current treeline conditions provided relatively little benefit to modeled net assimilation, whereas assimilation was sensitive to either wetter or drier conditions. Summer precipitation may be at least as important as temperature in constraining C gain by establishing subalpine trees at and above current alpine treelines as seasonally dry subalpine and alpine ecosystems continue to warm. PMID:25902893

  12. 45 CFR 146.111 - Limitations on preexisting condition exclusion period.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... Individual C has asthma and is treated for that condition several times during the 6-month period before C's... Employer T's plan. Two months later, C is hospitalized for asthma. (ii) Conclusion. In this Example 4, Employer T's plan may impose a preexisting condition exclusion with respect to C's asthma because...

  13. 42 CFR 410.37 - Colorectal cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Colorectal cancer screening tests: Conditions for...) BENEFITS Medical and Other Health Services § 410.37 Colorectal cancer screening tests: Conditions for and...) Colorectal cancer screening tests means any of the following procedures furnished to an individual for...

  14. 42 CFR 410.37 - Colorectal cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Colorectal cancer screening tests: Conditions for...) BENEFITS Medical and Other Health Services § 410.37 Colorectal cancer screening tests: Conditions for and...) Colorectal cancer screening tests means any of the following procedures furnished to an individual for...

  15. 42 CFR 410.37 - Colorectal cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Colorectal cancer screening tests: Conditions for...) BENEFITS Medical and Other Health Services § 410.37 Colorectal cancer screening tests: Conditions for and...) Colorectal cancer screening tests means any of the following procedures furnished to an individual for...

  16. 42 CFR 410.37 - Colorectal cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Colorectal cancer screening tests: Conditions for...) BENEFITS Medical and Other Health Services § 410.37 Colorectal cancer screening tests: Conditions for and...) Colorectal cancer screening tests means any of the following procedures furnished to an individual for...

  17. 42 CFR 410.37 - Colorectal cancer screening tests: Conditions for and limitations on coverage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Colorectal cancer screening tests: Conditions for...) BENEFITS Medical and Other Health Services § 410.37 Colorectal cancer screening tests: Conditions for and...) Colorectal cancer screening tests means any of the following procedures furnished to an individual for...

  18. Limited condition dependence of male acoustic signals in the grasshopper Chorthippus biguttulus

    PubMed Central

    Franzke, Alexandra; Reinhold, Klaus

    2012-01-01

    In many animal species, male acoustic signals serve to attract a mate and therefore often play a major role for male mating success. Male body condition is likely to be correlated with male acoustic signal traits, which signal male quality and provide choosy females indirect benefits. Environmental factors such as food quantity or quality can influence male body condition and therefore possibly lead to condition-dependent changes in the attractiveness of acoustic signals. Here, we test whether stressing food plants influences acoustic signal traits of males via condition-dependent expression of these traits. We examined four male song characteristics, which are vital for mate choice in females of the grasshopper Chorthippus biguttulus. Only one of the examined acoustic traits, loudness, was significantly altered by changing body condition because of drought- and moisture-related stress of food plants. No condition dependence could be observed for syllable to pause ratio, gap duration within syllables, and onset accentuation. We suggest that food plant stress and therefore food plant quality led to shifts in loudness of male grasshopper songs via body condition changes. The other three examined acoustic traits of males do not reflect male body condition induced by food plant quality. PMID:22957192

  19. An Analysis of Sequential Variables in Pavlovian Conditioning Employing Extended and Limited Acquisition Training

    ERIC Educational Resources Information Center

    Miller, Ronald Mellado; Capaldi, E. John

    2006-01-01

    Sequential theory's memory model of learning has been successfully applied in response contingent instrumental conditioning experiments (Capaldi, 1966, 1967, 1994; Capaldi & Miller, 2003). However, it has not been systematically tested in nonresponse contingent Pavlovian conditioning experiments. The present experiments attempted to determine if…

  20. Limitations on Silicon in the Outer Core: Ultrasonic Measurements at High Temperatures and High dK/dP's of Fe-Ni-Si Liquids at High Pressures

    NASA Astrophysics Data System (ADS)

    Williams, Q. C.; Manghnani, M. H.; Secco, R.; Fu, S.

    2015-12-01

    The sound velocities of four iron-nickel-silicon liquids (Fe-5wt%Ni-6wt%Si, Fe-5wt%Ni-10wt%Si, Fe-5wt%Ni-14wt%Si and Fe-5wt%Ni-20wt%Si) are measured between 1460 and 1925 K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids, and the temperature-dependence of their elasticity. These elastic data are utilized to assess both relatively low-pressure (to 12 GPa) compressional data on Fe-Si liquids, and to extrapolate to higher pressure and temperature conditions. If a single equation of state for Fe-Ni-Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low-pressures in Fe-Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.

  1. Computational Assessment of the GT-MHR Graphite Core Support Structural Integrity in Air-Ingress Accident Condition

    SciTech Connect

    Jong B. Lim; Eung S. Kim; Chang H. Oh; Richard R. Schultz; David A. Petti

    2008-10-01

    The objective of this project was to perform stress analysis for graphite support structures of the General Atomics’ 600 MWth GT-MHR prismatic core design using ABAQUS ® (ver. 6.75) to assess their structural integrity in air-ingress accident conditions where the structure weakens over time due to oxidation damages. The graphite support structures of prismatic type GT-MHR was analyzed based on the change of temperature, burn-off and corrosion depth during the accident period predicted by GAMMA, a multi-dimensional gas multi-component mixture analysis code developed in the Republic of Korea (ROK)/United States (US) International –Nuclear Engineering Research Initiative (I-NERI) project. Both the loading and thermal stresses were analyzed, but the thermal stress was not significant, leaving the loading stress to be the major factor. The mechanical strengths are exceeded between 11 to 11.5 days after loss-of-coolant-accident (LOCA), corresponding to 5.5 to 6 days after the start of natural convection.

  2. Synthesis of branched cores by poly-O-alkylation reaction under phase transfer conditions. A systematic study

    NASA Astrophysics Data System (ADS)

    Landeros, José M.; Silvestre, Hugo A.; Guadarrama, Patricia

    2013-04-01

    In the present paper is described a systematic study of poly-O-alkylation reactions of pentaerythritol (PE) and 1,1,1-tris(hydroxymethyl)ethane (TME) by 1,4 Michael addition, under phase transfer catalysis (PTC), considering the effect of: (1) the organophilicity of PTC (three different catalysts were tested), (2) PTC concentration (from catalytic to equimolar conditions), and (3) the regime of addition of reactants coexisting in the aqueous phase of the heterogeneous reaction system. The less organophilic transfer agent showed the best performance on these reactions. In our case, benzyltriethylammonium chloride (TEBAC) gathers the best features. The presence of NaOH as base, promotes the interfacial mechanism and not the bulk one. Out of the optimal range of concentration of NaOH (35-40%), competition between nucleophiles can occur, due to the saturation of the medium. Regarding the regime of addition of reactants, the scenario where NaOH and TEBAC are less time in contact, favors the formation of the desired products. Finally, the deprotection of tert-butyl groups of the poly-O-alkylated compounds is described, to get branched cores with terminal carboxylic acid groups in good yields (90-94%). Spectroscopic properties, such as IR, 1H and 13C NMR, of the synthesized compounds are also described.

  3. Phase averaging of the precessing vortex core in a swirl burner under piloted and premixed combustion conditions

    SciTech Connect

    Froud, D.; O`Doherty, T.; Syred, N.

    1995-02-01

    The flow patterns produced in and past the exhaust of a 100-KW swirl burner have been investigated experimentally under piloted premixed combustion conditions. The well-known three-dimensional time-dependent instability called the precessing vortex core (PVC) dominates the flow and mixing patterns. The PVC and its associated cycle time were used to trigger a three-component laser anemometry system. Successive cycles were overlaid and phase averaged to give a three-dimensional picture of the rotating flow fields. Measurements were obtained over successive slices of the flow, extending to X/De = 2.5 past the burner exit. A description of the flow was thus obtained in terms of phase averaged tangential, axial and radial velocities in tangential/radial and axial/radial planes. The results confirm previous reported work on the same burner operated isothermally and show that the center of the vortex flow is displaced from the central axis of the burner, creating the PVC phenomena as the center of the vortex precesses around the central axis of symmetry. As a consequence of this displacement the reverse flow zone (RFZ) is also displaced, while also partially lagging behind the PVC by up to 180{degree}. The RFZ acts as a feedback mechanism for the PVC phenomena. As a consequence of the displaced vortex center, flow between the PVC center and the wall is squeezed. Thus, due to angular momentum flux consideration, it produces a considerable increase in tangential velocity and gives the characteristic PVC signal. The displaced RFZ is both rotating through a region of forward flow while also being of an intermittent nature, giving rise to the excellent flame stabilization and mixing characteristics of these types of burners. Similar results were obtained for isothermal and premixed combustion conditions providing the flame was stabilized close to the burner exit nozzle.

  4. Experimental Evidence for Self-Limiting Reactive Flow through a Fractured Cement Core: Implications for Time-Dependent Wellbore Leakage

    SciTech Connect

    Huerta, Nicolas J.; Hesse, Marc A.; Bryant, Steven L.; Strazisar, Brian R; Lopano, Christina L.

    2013-01-01

    We present a set of reactive transport experiments in cement fractures. The experiments simulate coupling between flow and reaction when acidic, CO{sub 2}-rich fluids flow along a leaky wellbore. An analog dilute acid with a pH between 2.0 and 3.15 was injected at constant rate between 0.3 and 9.4 cm/s into a fractured cement core. Pressure differential across the core and effluent pH were measured to track flow path evolution, which was analyzed with electron microscopy after injection. In many experiments reaction was restricted within relatively narrow, tortuous channels along the fracture surface. The observations are consistent with coupling between flow and dissolution/precipitation. Injected acid reacts along the fracture surface to leach calcium from cement phases. Ahead of the reaction front, high pH pore fluid mixes with calcium-rich water and induces mineral precipitation. Increases in the pressure differential for most experiments indicate that precipitation can be sufficient to restrict flow. Experimental data from this study combined with published field evidence for mineral precipitation along cemented annuli suggests that leakage of CO{sub 2}-rich fluids along a wellbore may seal the leakage pathway if the initial aperture is small and residence time allows mobilization and precipitation of minerals along the fracture.

  5. Measuring the Internal Structure and Physical Conditions in Star and Planet Forming Clouds Cores: Towards a Quantitative Description of Cloud Evolution

    NASA Technical Reports Server (NTRS)

    Lada, Charles J.

    2004-01-01

    This grant funds a research program to use infrared extinction measurements to probe the detailed structure of dark molecular cloud cores and investigate the physical conditions which give rise to star and planet formation. The goals of this program are to acquire, reduce and analyze deep infrared and molecular-line observations of a carefully selected sample of nearby dark clouds in order to determine the detailed initial conditions for star formation from quantitative measurements of the internal structure of starless cloud cores and to quantitatively investigate the evolution of such structure through the star and planet formation process.

  6. 40 CFR 122.44 - Establishing limitations, standards, and other permit conditions (applicable to State NPDES...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS EPA ADMINISTERED PERMIT... limitations guidelines and standards in an NPDES permit to forego sampling of a pollutant found at 40 CFR... good only for the term of the permit and is not available during the term of the first permit issued...

  7. Inclusive and Integrated Schooling for Children with Limited Abilities: Problems and Conditions Necessary for Effectiveness

    ERIC Educational Resources Information Center

    Liubavina, N. V.

    2014-01-01

    For more than twenty years now the system of education in Russia has been adopting the ideas of integrated schooling for children with limited abilities. The absence of positive outcomes has been confirmed by the results of numerous surveys (Malofeev 2007, 2011; Nazarova 1996, 2009). In this article, N. V. Liubavina writes that the time has now…

  8. Chirally-coupled-core Yb-fiber laser delivering 80-fs pulses with diffraction-limited beam quality warranted by a high-dispersion mirror based compressor.

    PubMed

    Chen, Hung-Wen; Sosnowski, Tom; Liu, Chi-Hung; Chen, Li-Jin; Birge, Jonathan R; Galvanauskas, Almantas; Kärtner, Franz X; Chang, Guoqing

    2010-11-22

    We demonstrate a high-energy femtosecond laser system that incorporates two rapidly advancing technologies: chirally-coupled-core large-mode-area Yb-fiber to ensure fundamental-mode operation and high-dispersion mirrors to enable loss-free pulse compression while preserving the diffraction-limited beam quality. Mode-locking is initiated by a saturable absorber mirror and further pulse shortening is achieved by nonlinear polarization evolution. Centered at 1045 nm with 39-MHz repetition rate, the laser emits 25-nJ, positively chirped pulses with 970-mW average power. 6 bounces from double-chirped-mirrors compress these pulses down to 80 fs, close to their transform-limited duration. The loss-free compression gives rise to a diffraction-limited optical beam (M2 = 1.05). PMID:21164816

  9. Integrated core-log petrofacies analysis in the construction of a reservoir geomodel: A case study of a mature Mississippian carbonate reservoir using limited data

    USGS Publications Warehouse

    Bhattacharya, S.; Doveton, J.H.; Carr, T.R.; Guy, W.R.; Gerlach, P.M.

    2005-01-01

    Small independent operators produce most of the Mississippian carbonate fields in the United States mid-continent, where a lack of integrated characterization studies precludes maximization of hydrocarbon recovery. This study uses integrative techniques to leverage extant data in an Osagian and Meramecian (Mississippian) cherty carbonate reservoir in Kansas. Available data include petrophysical logs of varying vintages, limited number of cores, and production histories from each well. A consistent set of assumptions were used to extract well-level porosity and initial saturations, from logs of different types and vintages, to build a geomodel. Lacking regularly recorded well shut-in pressures, an iterative technique, based on material balance formulations, was used to estimate average reservoir-pressure decline that matched available drillstem test data and validated log-analysis assumptions. Core plugs representing the principal reservoir petrofacies provide critical inputs for characterization and simulation studies. However, assigning plugs among multiple reservoir petrofacies is difficult in complex (carbonate) reservoirs. In a bottom-up approach, raw capillary pressure (Pc) data were plotted on the Super-Pickett plot, and log- and core-derived saturation-height distributions were reconciled to group plugs by facies, to identify core plugs representative of the principal reservoir facies, and to discriminate facies in the logged interval. Pc data from representative core plugs were used for effective pay evaluation to estimate water cut from completions, in infill and producing wells, and guide-selective perforations for economic exploitation of mature fields. The results from this study were used to drill 22 infill wells. Techniques demonstrated here can be applied in other fields and reservoirs. Copyright ?? 2005. The American Association of Petroleum Geologists. All rights reserved.

  10. 42 CFR 410.19 - Ultrasound screening for abdominal aortic aneurysms: Condition for and limitation on coverage.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Ultrasound screening for abdominal aortic aneurysms... aneurysms: Condition for and limitation on coverage. (a) Definitions: As used in this section, the following... screening for an abdominal aortic aneurysm as a result of an initial preventive physical examination...

  11. 42 CFR 410.19 - Ultrasound screening for abdominal aortic aneurysms: Condition for and limitation on coverage.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 2 2011-10-01 2011-10-01 false Ultrasound screening for abdominal aortic aneurysms... aneurysms: Condition for and limitation on coverage. (a) Definitions: As used in this section, the following... screening for an abdominal aortic aneurysm as a result of an initial preventive physical examination...

  12. 42 CFR 410.19 - Ultrasound screening for abdominal aortic aneurysms: Condition for and limitation on coverage.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Ultrasound screening for abdominal aortic aneurysms... aneurysms: Condition for and limitation on coverage. (a) Definitions: As used in this section, the following... screening for an abdominal aortic aneurysm as a result of an initial preventive physical examination...

  13. 42 CFR 410.19 - Ultrasound screening for abdominal aortic aneurysms: Condition for and limitation on coverage.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Ultrasound screening for abdominal aortic aneurysms... aneurysms: Condition for and limitation on coverage. (a) Definitions: As used in this section, the following... ultrasound screening for an abdominal aortic aneurysm under Medicare program; and (2) Is included in at...

  14. 42 CFR 410.19 - Ultrasound screening for abdominal aortic aneurysms: Condition for and limitation on coverage.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Ultrasound screening for abdominal aortic aneurysms... aneurysms: Condition for and limitation on coverage. (a) Definitions: As used in this section, the following... screening for an abdominal aortic aneurysm as a result of an initial preventive physical examination...

  15. GCM Simulations of Neoproterozoic "Snowball Earth" Conditions: Implications for the Environmental Limits on Terrestrial Metazoans and Their Extraterrestrial Analogues

    NASA Technical Reports Server (NTRS)

    Sohl, L. E.; Chandler, M. A.

    2001-01-01

    The Neoproterozoic Snowball Earth intervals provide excellent opportunities to examine the environmental limits on terrestrial metazoans. A series of GCM simulations was run in order to quantify climatic conditions during these intervals. Additional information is contained in the original extended abstract.

  16. 7 CFR 301.76-5 - General conditions governing the issuance of any certificate or limited permit; provisions for...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Asian Citrus Psyllid § 301.76-5 General conditions governing the issuance of any certificate or limited... Act (7 U.S.C. 7714) 2 /> to prevent the spread of Asian citrus psyllid; and 2 An inspector may hold... greening and the Asian citrus psyllid; and (3) Is eligible for interstate movement under all other...

  17. 7 CFR 301.76-7 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... and Asian Citrus Psyllid § 301.76-7 Additional conditions for issuance of certificates and limited... area if: (1) The nursery stock is treated for Asian citrus psyllid with an APHIS-approved soil drench... § 301.76-6(b)(1), or with methyl bromide or irradiation, in accordance with 7 CFR part 305 of...

  18. 10 CFR Appendix I to Part 50 - Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the Criterion âAs Low as is Reasonably Achievableâ for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents I Appendix I to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF...

  19. 10 CFR Appendix I to Part 50 - Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... light-water-cooled nuclear power reactors licensed under 10 CFR part 50 or part 52 of this chapter. The... 10 CFR part 50 or part 52 of this chapter. The guides on limiting conditions for operation for light... 10 Energy 1 2011-01-01 2011-01-01 false Numerical Guides for Design Objectives and...

  20. 10 CFR Appendix I to Part 50 - Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the Criterion âAs Low as is Reasonably Achievableâ for Radioactive Material in Light-Water-Cooled Nuclear Power Reactor Effluents I Appendix I to Part 50 Energy NUCLEAR REGULATORY COMMISSION DOMESTIC LICENSING OF...

  1. 10 CFR Appendix I to Part 50 - Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... light-water-cooled nuclear power reactors licensed under 10 CFR part 50 or part 52 of this chapter. The... 10 CFR part 50 or part 52 of this chapter. The guides on limiting conditions for operation for light... 10 Energy 1 2013-01-01 2013-01-01 false Numerical Guides for Design Objectives and...

  2. 7 CFR 301.76-5 - General conditions governing the issuance of any certificate or limited permit; provisions for...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-5 General conditions governing the issuance of any certificate or limited... Act (7 U.S.C. 7714) 2 to prevent the spread of Asian citrus psyllid; and 2 An inspector may hold...

  3. 7 CFR 301.76-5 - General conditions governing the issuance of any certificate or limited permit; provisions for...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-5 General conditions governing the issuance of any certificate or limited... Act (7 U.S.C. 7714) 2 /> to prevent the spread of Asian citrus psyllid; and 2 An inspector may...

  4. 7 CFR 301.76-5 - General conditions governing the issuance of any certificate or limited permit; provisions for...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus Greening and Asian Citrus Psyllid § 301.76-5 General conditions governing the issuance of any certificate or limited... Act (7 U.S.C. 7714) 2 /> to prevent the spread of Asian citrus psyllid; and 2 An inspector may...

  5. Photosystem II cycle activity and alternative electron transport in the diatom Phaeodactylum tricornutum under dynamic light conditions and nitrogen limitation.

    PubMed

    Wagner, Heiko; Jakob, Torsten; Lavaud, Johann; Wilhelm, Christian

    2016-05-01

    Alternative electron sinks are an important regulatory mechanism to dissipate excessively absorbed light energy particularly under fast changing dynamic light conditions. In diatoms, the cyclic electron transport (CET) around Photosystem II (PS II) is an alternative electron transport pathway (AET) that contributes to avoidance of overexcitation under high light illumination. The combination of nitrogen limitation and high-intensity irradiance regularly occurs under natural conditions and is expected to force the imbalance between light absorption and the metabolic use of light energy. The present study demonstrates that under N limitation, the amount of AET and the activity of CETPSII in the diatom Phaeodactylum tricornutum were increased. Thereby, the activity of CETPSII was linearly correlated with the amount of AET rates. It is concluded that CETPSII significantly contributes to AET in P. tricornutum. Surprisingly, CETPSII was found to be activated already at the end of the dark period under N-limited conditions. This coincided with a significantly increased degree of reduction of the plastoquinone (PQ) pool. The analysis of the macromolecular composition of cells of P. tricornutum under N-limited conditions revealed a carbon allocation in favor of carbohydrates during the light period and their degradation during the dark phase. A possible linkage between the activity of CETPSII and degree of reduction of the PQ pool on the one side and the macromolecular changes on the other is discussed. PMID:26650230

  6. 7 CFR 301.76-7 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 5 2012-01-01 2012-01-01 false Additional conditions for issuance of certificates and limited permits for regulated articles moved interstate from areas quarantined for citrus greening. 301.76-7 Section 301.76-7 Agriculture Regulations of the Department of Agriculture (Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE,...

  7. 10 CFR Appendix I to Part 50 - Numerical Guides for Design Objectives and Limiting Conditions for Operation To Meet the...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... light-water-cooled nuclear power reactors licensed under 10 CFR part 50 or part 52 of this chapter. The... 10 CFR part 50 or part 52 of this chapter. The guides on limiting conditions for operation for light... 10 Energy 1 2012-01-01 2012-01-01 false Numerical Guides for Design Objectives and...

  8. Hydrogen isotope exchange and conditioning in graphite limiters used in TFTR

    SciTech Connect

    LaMarche, P.H.; Dylla, H.F.; McCarthy, P.J.; Ulrickson, M.

    1986-02-01

    Isotopic exchange experiments performed in TFTR are used to examine the outgassing and diffusive properties of graphite used as the plasma limiter. Changeover from hydrogen to deuterium for different periods ranges from approx.600 to 60 plasma discharges, which appears to be correlated to the limiter temperature. We present a simple analytical model that predicts a fast transient (approx.10 plasma discharges) changeover where the deuterium fueling dilutes the adsorbed and near-surface hydrogen, and a slowly changing term where bulk hydrogen diffuses to the surface. Using this model we can extract an activation energy for diffusion of 0.15 +- 0.02 eV. We hypothesize that interpore diffusion for this porous (approx.15%) material is consistent with our observations. 19 refs.

  9. The condition of a finite Markov chain and perturbation bounds for the limiting probabilities

    NASA Technical Reports Server (NTRS)

    Meyer, C. D., Jr.

    1979-01-01

    The inequalities bounding the relative error the norm of w- w squiggly/the norm of w are exhibited by a very simple function of E and A. Let T denote the transition matrix of an ergodic chain, C, and let A = I - T. Let E be a perturbation matrix such that T squiggly = T - E is also the transition matrix of an ergodic chain, C squiggly. Let w and w squiggly denote the limiting probability (row) vectors for C and C squiggly. The inequality is the best one possible. This bound can be significant in the numerical determination of the limiting probabilities for an ergodic chain. In addition to presenting a sharp bound for the norm of w-w squiggly/the norm of w an explicit expression for w squiggly will be derived in which w squiggly is given as a function of E, A, w and some other related terms.

  10. Polyhydroxyalkanoates from Pseudomonas sp. using synthetic and olive mill wastewater under limiting conditions.

    PubMed

    Kourmentza, C; Ntaikou, I; Lyberatos, G; Kornaros, M

    2015-03-01

    The present study aimed at investigating the ability of bacteria isolated from an enriched mixed culture to produce polyhydroxyalkanoates (PHAs) and examining the effect of nitrogen and dual nitrogen-oxygen limitation on PHAs production, by using both synthetic and olive mill wastewater (OMW). PHAs production was performed through batch experiments using both the enriched culture and the isolated strains (belonging to the genus of Pseudomonas) aiming to compare PHAs accumulation capacity, yields and rates. The use of enriched culture and synthetic wastewater under nitrogen limitation resulted in the highest PHA accumulation, i.e. 64.4%gPHAs/g of cell dry mass (CDM). However, when OMW was used, PHAs accumulation significantly decreased, i.e. 8.8%gPHAs/g CDM. The same trend was followed by the isolated strains, nevertheless, their ability to synthesize PHAs was lower. Although, dual nitrogen-oxygen limitation generally slowed down PHAs biosynthesis, in certain strains PHAs production was positively affected. PMID:25542172

  11. Biomass and cellulosic ethanol production of forage sorghum under limited water conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two year field study was conducted to evaluate biofuel production potential of two forage sorghum cultivars differing in brown midrib trait under non-irrigated and deficit irrigation conditions in the semiarid Southern High Plains of the U.S. Cultivar SP1990 (non-bmr = conventional cell wall comp...

  12. Effect of labour market conditions on reporting of limiting long-term illness and permanent sickness in England and Wales.

    PubMed Central

    Haynes, R; Bentham, G; Lovett, A; Eimermann, J

    1997-01-01

    STUDY OBJECTIVE: To identify any bias in the reporting of limiting long term illness and permanent sickness due to labour market conditions, and show the absence of the effect in mortality rates. DESIGN: A geographically based study using data from the 1991 census. Standardised ratios for mortality and long term illness in people aged 0-64 years and permanent sickness in people of working age were compared with Carstairs deprivation scores in multilevel models which separated the effects operating at three geographical scales: census wards, travel to work areas, and standard regions. Holding ward and regional effects constant, variations between travel to work areas were compared with long term unemployment rates. SETTING: Altogether 8690 wards and 262 travel to work areas in England and Wales. MAIN RESULTS: Variations in mortality, limiting long term illness, and permanent sickness were related to Carstairs deprivation scores and standard region. With these relationships controlled, limiting long term illness and permanent sickness were significantly related to long term unemployment levels in travel to work areas, but mortality was not affected. Self reported morbidity was more sensitive to variations in long term unemployment rates in conditions of high social deprivation than in affluent populations. CONCLUSIONS: Limiting long term illness and permanent sickness measures may reflect a tendency for higher positive response in difficult labour market conditions. For average social deprivation conditions, standardised limiting long term illness for people aged 0-64 years was 20% higher in travel to work areas where employment prospects were relatively poor compared with areas with relatively good employment prospects. This casts doubt on the use of limiting long term illness as an indicator of objective health care needs for resource allocation purposes at national level. PMID:9229058

  13. An Individual-Based Diploid Model Predicts Limited Conditions Under Which Stochastic Gene Expression Becomes Advantageous

    PubMed Central

    Matsumoto, Tomotaka; Mineta, Katsuhiko; Osada, Naoki; Araki, Hitoshi

    2015-01-01

    Recent studies suggest the existence of a stochasticity in gene expression (SGE) in many organisms, and its non-negligible effect on their phenotype and fitness. To date, however, how SGE affects the key parameters of population genetics are not well understood. SGE can increase the phenotypic variation and act as a load for individuals, if they are at the adaptive optimum in a stable environment. On the other hand, part of the phenotypic variation caused by SGE might become advantageous if individuals at the adaptive optimum become genetically less-adaptive, for example due to an environmental change. Furthermore, SGE of unimportant genes might have little or no fitness consequences. Thus, SGE can be advantageous, disadvantageous, or selectively neutral depending on its context. In addition, there might be a genetic basis that regulates magnitude of SGE, which is often referred to as “modifier genes,” but little is known about the conditions under which such an SGE-modifier gene evolves. In the present study, we conducted individual-based computer simulations to examine these conditions in a diploid model. In the simulations, we considered a single locus that determines organismal fitness for simplicity, and that SGE on the locus creates fitness variation in a stochastic manner. We also considered another locus that modifies the magnitude of SGE. Our results suggested that SGE was always deleterious in stable environments and increased the fixation probability of deleterious mutations in this model. Even under frequently changing environmental conditions, only very strong natural selection made SGE adaptive. These results suggest that the evolution of SGE-modifier genes requires strict balance among the strength of natural selection, magnitude of SGE, and frequency of environmental changes. However, the degree of dominance affected the condition under which SGE becomes advantageous, indicating a better opportunity for the evolution of SGE in different genetic

  14. The limits of the adaptation of life to extreme conditions (in connection with problems of exobiology)

    NASA Technical Reports Server (NTRS)

    Aksenov, S. I.

    1973-01-01

    Accommodation is discussed as a universal evolutionary principle which essentially will apply to all life forms, regardless of chemical base (carbon, silicon, etc.). Life forms must either adapt to extreme conditions or perish, and for any life form an extremum factor is any significant deviation in environmental parameters. The possibility of life forms existing in specific extraterrestrial environments is discussed, and a conclusion is drawn which unequivocally states that through many forms of accommodation life is possible in many different environments.

  15. Factors limiting endurance of armor, artillery, and infantry units under simulated NBC conditions

    SciTech Connect

    Rauch, T.M.; Tharion, W.J.; Banderet, L.E.; Lussier, A.R.

    1986-03-13

    The war of the future will require 72-hour operations in environments contaminated with nuclear/biological/chemical (NBC) agents. The 1985 P2NBC2 (Physiological and Psychological Effects of NBC and Extended Operations on Combined Arms Crews) Program assessed soldier endurance and performance under simulated NBC conditions. A total of 175 soldiers were observed during four tests differing in design, site, climatic conditions, and performance demands. In all but one of the iterations where the full chemical-protective ensemble (MOPP 4) was used without cooling, soldier endurance fell far short of the projected requirement. Psychological data were analyzed to determine which factors were associated with the incidence of casualties. The findings showed that perceived intensity of symptoms resembling the hyperventilation syndrome was significantly greater in soldiers classified as Casualties. Five of these symptoms (painful breathing, difficulty breathing, shortness of breath, headache, and nausea) showed Casualty-Survivor differences in all tests. Symptom intensity was attributed to two factors. (1) External conditions. Thermal stress exacerbated the five basic symptoms, induced others (tetany and paresthesia), and decreased endurance. Periodic relief from respirator use attenuated these symptoms and enhanced endurance. (2) Individual differences. Significant Casualty-Survivor differences in anxiety, depression, and cognitive strategy scores indicated that perception of hyperventilation symptoms and endurance were related to personality variables. Hyperventilation symptoms could incapacitate the soldier or induce removal of the protective mask under actual chemical attack.

  16. Scaling Hydrodynamic Boundary Conditions of Microstructured Surfaces in the Thin Channel Limit.

    PubMed

    Pilkington, Georgia A; Gupta, Rohini; Fréchette, Joëlle

    2016-03-15

    Despite its importance in many applications and processes, a complete and unified view on how nano- and microscale asperities influence hydrodynamic interactions has yet to be reached. In particular, the effects of surface structure can be expected to become more dominant when the length scale of the asperities or textures becomes comparable to that of the fluid flow. Here we analyze the hydrodynamic drainage of a viscous silicone oil squeezed between a smooth plane and a surface decorated with hexagonal arrays of lyophilic microsized cylindrical posts. For all micropost arrays studied, the periodicity of the structures was much larger than the separation range of our measurements. In this thin channel geometry, we find the hydrodynamic drainage and separation forces for the micropost arrays cannot be fully described by existing boundary condition models for interfacial slip or a no-slip shifted plane. Instead, our results show that the influence of the microposts on the hydrodynamic drag exhibits three distinct regimes as a function of separation. For large separations, a no slip boundary condition (Reynolds theory) is observed for all surfaces until a critical (intermediate) separation, below which the position of the no-slip plane scales with surface separation until reaching a maximum, just before contact. Below this separation, a sharp decrease in the no-slip plane position then suggests that a boundary condition of a smooth surface is recovered at contact. PMID:26901492

  17. Teleportation of qubit states through dissipative channels: Conditions for surpassing the no-cloning limit

    SciTech Connect

    Oezdemir, Sahin Kaya; Bartkiewicz, Karol; Liu, Yu-xi; Miranowicz, Adam

    2007-10-15

    We investigate quantum teleportation through dissipative channels and calculate teleportation fidelity as a function of damping rates. It is found that the average fidelity of teleportation and the range of states to be teleported depend on the type and rate of the damping in the channel. Using the fully entangled fraction, we derive two bounds on the damping rates of the channels: one is to beat the classical limit and the second is to guarantee the nonexistence of any other copy with better fidelity. The effect of the initially distributed maximally entangled state on the process is presented; the concurrence and the fully entangled fraction of the shared states are discussed. We intend to show that prior information on the dissipative channel and the range of qubit states to be teleported is helpful for the evaluation of the success of teleportation, where success is defined as surpassing the fidelity limit imposed by the fidelity of the 1-to-2 optimal cloning machine for the specific range of qubits.

  18. Limits on conservative behavior of Nd isotopes in seawater assessed from analysis of fish teeth from Pacific core tops

    NASA Astrophysics Data System (ADS)

    Horikawa, Keiji; Martin, Ellen E.; Asahara, Yoshihiro; Sagawa, Takuya

    2011-10-01

    Neodymium (Nd) isotopes have become an accepted water mass tracer for paleoceanographic reconstructions; however, high rates of radiogenic Nd input from volcanic islands/arcs in the western equatorial Pacific (WEP) and the subarctic North Pacific (SANP) can significantly alter the isotopic composition of ambient seawaters, leading to questions about the conservative nature of Nd isotopes in the Pacific. Here we present the first comprehensive study of Nd isotopes preserved in core-top fossil fish teeth/debris from 31 sites in the Pacific to define the vertical and horizontal distributions of seawater Nd isotopes and to test the reliability of Nd isotopes as a water mass tracer in the Pacific. We found that Nd isotopic values of northward-flowing Lower Circumpolar Deep Water (LCDW) are significantly modified in the western-central equatorial Pacific and the SANP as a result of local radiogenic inputs from young circum-Pacific island arcs. Consequently, 'modified LCDW' with ~-5 ɛ Nd is created in the central equatorial Pacific, while recirculated North Pacific Deep Water (NPDW) acquires a radiogenic Nd isotope value (~-2 ɛ Nd) in the SANP. Nd isotopic ratios of fish teeth/debris in the central North Pacific plotted against salinity (or phosphate concentration) from the overlying bottom water produce a mixing envelope between modified LCDW and NPDW, indicating that these Nd isotopic values represent the southern- and northern-sourced end member values for the central North Pacific and that mixing of these water masses defines vertical profiles of Nd isotopes in this region. In the eastern equatorial Pacific (EEP) three water masses (modified LCDW, NPDW SANP, and NPDW western Pacific) combine to produce Nd isotopic values that reflect this conservative mixture. Therefore, Nd isotopes behave as a conservative water mass tracer in the central North Pacific and the EEP, but high rates of lithogenic inputs from young circum-Pacific island arcs compromise the conservative

  19. Phycobilisome-Deficient Strains of Synechocystis sp. PCC 6803 Have Reduced Size and Require Carbon-Limiting Conditions to Exhibit Enhanced Productivity1[W][OPEN

    PubMed Central

    Lea-Smith, David J.; Bombelli, Paolo; Dennis, John S.; Scott, Stuart A.; Smith, Alison G.; Howe, Christopher J.

    2014-01-01

    Reducing excessive light harvesting in photosynthetic organisms may increase biomass yields by limiting photoinhibition and increasing light penetration in dense cultures. The cyanobacterium Synechocystis sp. PCC 6803 harvests light via the phycobilisome, which consists of an allophycocyanin core and six radiating rods, each with three phycocyanin (PC) discs. Via targeted gene disruption and alterations to the promoter region, three mutants with two (pcpcT→C) and one (ΔCpcC1C2:pcpcT→C) PC discs per rod or lacking PC (olive) were generated. Photoinhibition and chlorophyll levels decreased upon phycobilisome reduction, although greater penetration of white light was observed only in the PC-deficient mutant. In all strains cultured at high cell densities, most light was absorbed by the first 2 cm of the culture. Photosynthesis and respiration rates were also reduced in the ΔCpcC1C2:pcpcT→C and olive mutants. Cell size was smaller in the pcpcT→C and olive strains. Growth and biomass accumulation were similar between the wild-type and pcpcT→C under a variety of conditions. Growth and biomass accumulation of the olive mutant were poorer in carbon-saturated cultures but improved in carbon-limited cultures at higher light intensities, as they did in the ΔCpcC1C2:pcpcT→C mutant. This study shows that one PC disc per rod is sufficient for maximal light harvesting and biomass accumulation, except under conditions of high light and carbon limitation, and two or more are sufficient for maximal oxygen evolution. To our knowledge, this study is the first to measure light penetration in bulk cultures of cyanobacteria and offers important insights into photobioreactor design. PMID:24760817

  20. Water-Limiting Conditions Alter the Structure and Biofilm-Forming Ability of Bacterial Multispecies Communities in the Alfalfa Rhizosphere

    PubMed Central

    Bogino, Pablo; Abod, Ayelén; Nievas, Fiorela; Giordano, Walter

    2013-01-01

    Biofilms are microbial communities that adhere to biotic or abiotic surfaces and are enclosed in a protective matrix of extracellular compounds. An important advantage of the biofilm lifestyle for soil bacteria (rhizobacteria) is protection against water deprivation (desiccation or osmotic effect). The rhizosphere is a crucial microhabitat for ecological, interactive, and agricultural production processes. The composition and functions of bacterial biofilms in soil microniches are poorly understood. We studied multibacterial communities established as biofilm-like structures in the rhizosphere of Medicago sativa (alfalfa) exposed to 3 experimental conditions of water limitation. The whole biofilm-forming ability (WBFA) for rhizospheric communities exposed to desiccation was higher than that of communities exposed to saline or nonstressful conditions. A culture-dependent ribotyping analysis indicated that communities exposed to desiccation or saline conditions were more diverse than those under the nonstressful condition. 16S rRNA gene sequencing of selected strains showed that the rhizospheric communities consisted primarily of members of the Actinobacteria and α- and γ-Proteobacteria, regardless of the water-limiting condition. Our findings contribute to improved understanding of the effects of environmental stress factors on plant-bacteria interaction processes and have potential application to agricultural management practices. PMID:24223979

  1. [Unequal living conditions and health chances in preschool children: support protective factors - limit risk factors].

    PubMed

    Horstkotte, E; Zimmermann, E

    2008-11-01

    Manifestations of an aggravation of social antagonisms and increased reports about childhood poverty and child abuse have unleashed a broad debate about the situation of children in risk-laden circumstances. More and more children are affected by relative poverty and disadvantage. An increase in the number children under 15 who receive social assistance can also be registered in Bremen, this share even increased to 60% in especially burdened districts. Against this background, the Bremen Health Department used a socio-spatial analysis to determine whether the utilisation of health examinations and the social and cultural participation chances of preschool children differed according to their living conditions. To this end, selected data from the school entrance examinations from 1998 to 2005 were analysed in regard to their relevance for the participation chances in different child-related dimensions of the life situation. Contradictory developments could be found, both in the dimension of the utilisation of health examinations and in the dimension of social and cultural participation chances. Children from disadvantaged neighbourhoods exhibited a lower utilisation of health examinations and less chances for social and cultural participation than children from more well-to-do residential areas. Trend calculations for the years 1998 to 2005 show an increasing discrepancy between children from disadvantaged and those from well-to-do neighbourhoods. Disadvantaged life situations - with the danger of increasing exclusion - appear to be establishing themselves in Bremen. The resources of children and families for dealing with risk-laden life situations have to be strengthened. Effective and long-lasting prevention approaches have to be developed and implemented at the local level. Kindergartens and schools could serve as centres for community networking strategies. Integrated concepts for action in the respective social areas are necessary to protect children and

  2. Microhabitat Conditions in Wyoming’s Sage-Grouse Core Areas: Effects on Nest Site Selection and Success

    PubMed Central

    Beck, Jeffrey L.; Kirol, Christopher P.; Pratt, Aaron C.; Conover, Michael R.

    2016-01-01

    The purpose of our study was to identify microhabitat characteristics of greater sage-grouse (Centrocercus urophasianus) nest site selection and survival to determine the quality of sage-grouse habitat in 5 regions of central and southwest Wyoming associated with Wyoming’s Core Area Policy. Wyoming’s Core Area Policy was enacted in 2008 to reduce human disturbance near the greatest densities of sage-grouse. Our analyses aimed to assess sage-grouse nest selection and success at multiple micro-spatial scales. We obtained microhabitat data from 928 sage-grouse nest locations and 819 random microhabitat locations from 2008–2014. Nest success was estimated from 924 nests with survival data. Sage-grouse selected nests with greater sagebrush cover and height, visual obstruction, and number of small gaps between shrubs (gap size ≥0.5 m and <1.0 m), while selecting for less bare ground and rock. With the exception of more small gaps between shrubs, we did not find any differences in availability of these microhabitat characteristics between locations within and outside of Core Areas. In addition, we found little supporting evidence that sage-grouse were selecting different nest sites in Core Areas relative to areas outside of Core. The Kaplan-Meier nest success estimate for a 27-day incubation period was 42.0% (95% CI: 38.4–45.9%). Risk of nest failure was negatively associated with greater rock and more medium-sized gaps between shrubs (gap size ≥2.0 m and <3.0 m). Within our study areas, Wyoming’s Core Areas did not have differing microhabitat quality compared to outside of Core Areas. The close proximity of our locations within and outside of Core Areas likely explained our lack of finding differences in microhabitat quality among locations within these landscapes. However, the Core Area Policy is most likely to conserve high quality habitat at larger spatial scales, which over decades may have cascading effects on microhabitat quality available between

  3. Isolation and characterization of ubiquinol oxidase complexes from Paracoccus denitrificans cells cultured under various limiting growth conditions in the chemostat.

    PubMed

    Bosma, G; Braster, M; Stouthamer, A H; van Verseveld, H W

    1987-06-15

    To obtain more information about the composition of the respiratory chain under different growth conditions and about the regulation of electron-transfer to several oxidases and reductases, ubiquinol oxidase complexes were partially purified from membranes of Paracoccus denitrificans cells grown in carbon-source-limited aerobic, nitrate-limited anaerobic and oxygen-limited chemostat cultures. The isolated enzymes consisted of cytochromes bc1, c552 and aa3. In comparison with the aerobic ubiquinol oxidase complex, the oxygen- and nitrate-limited ones contained, respectively, less and far less of the cytochrome aa3 subunits and the anaerobic complex also contained lower amounts of cytochrome c552. In addition, extra haem-containing polypeptides were present with apparent Mr of 14,000, 30,000 and 45,000, the former one only in the anaerobic and the latter two in both the anaerobic and oxygen-limited preparations. This is the first report describing four different membrane-bound c-type cytochromes. The potentiometric and spectral characteristics of the redox components in membrane particles and isolated ubiquinol oxidase fractions were determined by combined potentiometric analysis and spectrum deconvolution. Membranes of nitrate- and oxygen-limited cells contained extra high-potential cytochrome b in comparison with the membranes of aerobically grown cells. No difference was detected between the three isolated ubiquinol oxidase complexes. Aberrances with already published values of redox potentials are discussed. PMID:3036512

  4. Conditions and limitations on learning in the adaptive management of mallard harvests

    USGS Publications Warehouse

    Johnson, F.A.; Kendall, W.L.; Dubovsky, J.A.

    2002-01-01

    In 1995, the United States Fish and Wildlife Service adopted a protocol for the adaptive management of waterfowl hunting regulations (AHM) to help reduce uncertainty about the magnitude of sustainable harvests. To date, the AHM process has focused principally on the midcontinent population of mallards (Anas platyrhynchos), whose dynamics are described by 4 alternative models. Collectively, these models express uncertainty (or disagreement) about whether harvest is an additive or a compensatory form of mortality and whether the reproductive process is weakly or strongly density-dependent. Each model is associated with a probability or 'weight,' which describes its relative ability to predict changes in population size. These Bayesian probabilities are updated annually using a comparison of population size predicted under each model with that observed by a monitoring program. The current AHM process is passively adaptive, in the sense that there is no a priori consideration of how harvest decisions might affect discrimination among models. We contrast this approach with an actively adaptive approach, in which harvest decisions are used in part to produce the learning needed to increase long-term management performance. Our investigation suggests that the passive approach is expected to perform nearly as well as an optimal actively adaptive approach, particularly considering the nature of the model set, management objectives and constraints, and current regulatory alternatives. We offer some comments about the nature of the biological hypotheses being tested and describe some of the inherent limitations on learning in the AHM process.

  5. Measuring the Internal Structure and Physical Conditions in Star and Planet Forming Clouds Core: Toward a Quantitative Description of Cloud Evolution

    NASA Technical Reports Server (NTRS)

    Lada, Charles J.

    2005-01-01

    This grant funds a research program to use infrared extinction measurements to probe the detailed structure of dark molecular cloud cores and investigate the physical conditions which give rise to star and planet formation. The goals of this program are to acquire, reduce and analyze deep infrared and molecular-line observations of a carefully selected sample of nearby dark clouds in order to internal structure of starless cloud cores and to quantitatively investigate the evolution of such structure through the star and planet formation process. During the second year of this grant, progress toward these goals is discussed.

  6. Limited physical contact through a mesh barrier is sufficient for social reward-conditioned place preference in adolescent male rats

    PubMed Central

    Peartree, Natalie A.; Hood, Lauren E.; Thiel, Kenneth J.; Sanabria, Federico; Pentkowski, Nathan S.; Chandler, Kayla N.; Neisewander, Janet L.

    2012-01-01

    Adolescence is a period of enhanced sensitivity to social influences and vulnerability to drug abuse. Social reward in adolescent rats has been demonstrated with the conditioned place preference (CPP) model, but it is not clear whether limited contact with another rat without play is sufficient to produce reward. We investigated this issue using an apparatus containing two main compartments each with a wire mesh barrier that allowed rats placed on either side of the barrier to have limited physical contact. Adolescent male rats were given two conditioning sessions/day for 2 or 8 days following baseline preference tests. Rats were placed into their preferred side alone for one daily 10-min session and into their initially non-preferred side (i.e., CS) for the other session during which they either had restricted or unrestricted physical access to another rat (Rat/Mesh or Rat/Phys, respectively) or to a tennis ball (Ball/Mesh or Ball/Phys, respectively) unconditioned stimulus (US). Only the Rat/Phys group exhibited CPP after 2 CS-US pairings; however, after 8 CS-US pairings, the Rat/Mesh and Ball/Phys groups also exhibited CPP. During conditioning, the rat US elicited more robust approach and contact behavior compared to the ball, regardless of physical or restricted access. The incidence of contact and/or approach increased as the number of exposures increased. The results suggest that the rank order of US reward efficacy was physical contact with a rat > limited contact with a rat > physical contact with a ball, and that rough-and-tumble play is not necessary to establish social reward-CPP. The findings have important implications for emerging drug self-administration models in which two rats self-administering drug intravenously have limited physical contact via a mesh barrier shared between their respective operant conditioning chambers. PMID:22008744

  7. Limited physical contact through a mesh barrier is sufficient for social reward-conditioned place preference in adolescent male rats.

    PubMed

    Peartree, Natalie A; Hood, Lauren E; Thiel, Kenneth J; Sanabria, Federico; Pentkowski, Nathan S; Chandler, Kayla N; Neisewander, Janet L

    2012-02-01

    Adolescence is a period of enhanced sensitivity to social influences and vulnerability to drug abuse. Social reward in adolescent rats has been demonstrated with the conditioned place preference (CPP) model, but it is not clear whether limited contact with another rat without play is sufficient to produce reward. We investigated this issue using an apparatus containing two main compartment, each with a wire mesh barrier that allowed rats placed on either side of the barrier to have limited physical contact. Adolescent male rats were given two conditioning sessions/day for 2 or 8 days following baseline preference tests. Rats were placed into their preferred side alone for one daily 10-min session and into their initially non-preferred side (i.e., CS) for the other session during which they either had restricted or unrestricted physical access to another rat (Rat/Mesh or Rat/Phys, respectively) or to a tennis ball (Ball/Mesh or Ball/Phys, respectively) unconditioned stimulus (US). Only the Rat/Phys group exhibited CPP after 2 CS-US pairings; however, after 8 CS-US pairings, the Rat/Mesh and Ball/Phys groups also exhibited CPP. During conditioning, the rat US elicited more robust approach and contact behavior compared to the ball, regardless of physical or restricted access. The incidence of contact and/or approach increased as the number of exposures increased. The results suggest that the rank order of US reward efficacy was physical contact with a rat>limited contact with a rat>physical contact with a ball, and that rough-and-tumble play is not necessary to establish social reward-CPP. The findings have important implications for emerging drug self-administration models in which two rats self-administering drug intravenously have limited physical contact via a mesh barrier shared between their respective operant conditioning chambers. PMID:22008744

  8. BACLOFEN, RACLOPRIDE, AND NALTREXONE DIFFERENTIALLY AFFECT INTAKE OF FAT/SUCROSE MIXTURES UNDER LIMITED ACCESS CONDITIONS

    PubMed Central

    Wong, KJ; Wojnicki, FHW; Corwin, RLW

    2009-01-01

    This study assessed the effects of the opioid antagonist naltrexone, the dopamine 2-like (D2) antagonist raclopride, and the GABAB agonist baclofen on consumption of fat/sucrose mixtures (FSM) using a limited access protocol. Sixty male Sprague-Dawley rats were grouped according to two schedules of access (Daily [D] or Intermittent [I]) to an optional FSM. Each FSM was created by whipping 3.2% (L), 10% (M), or 32% (H) powdered sugar into 100% vegetable shortening in a w/w manner (n=10 per group). One-hour intakes of the IL and IM groups were significantly greater than intakes of the respective DL and DM groups, thus fulfilling our operational definition of binge-type eating in these groups. Baclofen reduced intakes of the L and M mixtures regardless of access schedule, but failed to reduce intake of the H mixture. Naltrexone reduced intake in all groups, but potency was greater in IL rats than in DL rats. Furthermore, potency was attenuated in Intermittent rats, but enhanced in Daily rats, at higher sucrose concentrations. Raclopride reduced intake in the DL and stimulated intake in the IL groups, reduced intake in both M groups, and was without effect in both H groups. These results indicate that fat/sucrose mixtures containing relatively low concentrations of sucrose allow distinctions to be made between: 1) intakes stimulated by different access schedules and 2) opioid and dopaminergic modulation of those intakes. These results also suggest that brief bouts of food consumption involving fatty, sugar-rich foods may prove to be particularly resistant to pharmacological intervention. PMID:19217918

  9. Determination of Bacterial Weathering Ability in Nutrient Limited Conditions on Biotite

    NASA Astrophysics Data System (ADS)

    Grant, M. R.; Harsh, J. B.

    2011-12-01

    Bacterial and fungal communities facilitate the weathering of minerals in oligotrophic soils. The bacterial communities reside in biofilms, consisting of extracellular polymeric substances (EPS) such as lipids, carbohydrates, proteins, and nuclei acids. Biotite, a 2:1 aluminosilicate mica, is a common primary mineral found in these low nutrient soils and is a source of potassium, magnesium and iron for both microorganisms and plants. Studies show that bacteria, when incubated with biotite flakes, can remove iron, potassium, and magnesium at higher quantities and increased rates compared to abiotic controls (Balogh-Brunstad et al., 2008; Calvaruso et al., 2006; Hopf et al. 2008; Uroz et al., 2007 and 2009). How this happens mechanistically is still unclear and this study seeks to shed light on this issue. We hypothesize that weathering by bacteria is selective; i.e., that the mechanism will depend on the limiting nutrient. Using a drip flow biofilm reactor, biofilms are grown on biotite coupons under non-turbulent, low sheer flow, with four different nutrient treatments. The nutrient treatments include a complete nutrient solution and the same solution without K, Mg, or Fe. In each treatment, we determine the concentration and cumulative release of each cation in the effluent. Congruent dissolution of biotite indicates that weathering is nonselective whereas incongruent dissolution suggests that the bacteria alter the weathering mechanism for a specific nutrient. The bacteria are selected from a bacterial inoculum collected from the roots of young White Pine (Pinus strobus) trees in the Saint Joseph National Forest, Idaho. The bacteria are isolated on plates and the best weathering species are selected using a microplate bioassay technique to determine the concentrations of K, Ca, Mg, and protons colorimetrically.

  10. Profiling of spatial metabolite distributions in wheat leaves under normal and nitrate limiting conditions

    PubMed Central

    Allwood, J. William; Chandra, Surya; Xu, Yun; Dunn, Warwick B.; Correa, Elon; Hopkins, Laura; Goodacre, Royston; Tobin, Alyson K.; Bowsher, Caroline G.

    2015-01-01

    The control and interaction between nitrogen and carbon assimilatory pathways is essential in both photosynthetic and non-photosynthetic tissue in order to support metabolic processes without compromising growth. Physiological differences between the basal and mature region of wheat (Triticum aestivum) primary leaves confirmed that there was a change from heterotrophic to autotrophic metabolism. Fourier Transform Infrared (FT-IR) spectroscopy confirmed the suitability and phenotypic reproducibility of the leaf growth conditions. Principal Component–Discriminant Function Analysis (PC–DFA) revealed distinct clustering between base, and tip sections of the developing wheat leaf, and from plants grown in the presence or absence of nitrate. Gas Chromatography-Time of Flight/Mass Spectrometry (GC-TOF/MS) combined with multivariate and univariate analyses, and Bayesian network (BN) analysis, distinguished different tissues and confirmed the physiological switch from high rates of respiration to photosynthesis along the leaf. The operation of nitrogen metabolism impacted on the levels and distribution of amino acids, organic acids and carbohydrates within the wheat leaf. In plants grown in the presence of nitrate there was reduced levels of a number of sugar metabolites in the leaf base and an increase in maltose levels, possibly reflecting an increase in starch turnover. The value of using this combined metabolomics analysis for further functional investigations in the future are discussed. PMID:25680480

  11. A strong conditional mutualism limits and enhances seed dispersal and germination of a tropical palm

    USGS Publications Warehouse

    Klinger, R.; Rejmanek, M.

    2010-01-01

    Seed predation and seed dispersal can have strong effects on early life history stages of plants. These processes have often been studied as individual effects, but the degree to which their relative importance co-varies with seed predator abundance and how this influences seed germination rates is poorly understood. Therefore, we used a combination of observations and field experiments to determine the degree to which germination rates of the palm Astrocaryum mexicanum varied with abundance of a small mammal seed predator/disperser, Heteromysdesmarestianus, in a lowland tropical forest. Patterns of abundance of the two species were strongly related; density of H. desmarestianus was low in sites with low density of A. mexicanum and vice versa. Rates of predation and dispersal of A. mexicanum seeds depended on abundance of H. desmarestianus; sites with high densities of H. desmarestianus had the highest rates of seed predation and lowest rates of seed germination, but a greater total number of seeds were dispersed and there was greater density of seedlings, saplings, and adults of A. mexicanum in these sites. When abundance of H. desmarestianus was experimentally reduced, rates of seed predation decreased, but so did dispersal of A. mexicanum seeds. Critically, rates of germination of dispersed seeds were 5 times greater than undispersed seeds. The results suggest that the relationship between A. mexicanum and H. desmarestianus is a conditional mutualism that results in a strong local effect on the abundance of each species. However, the magnitude and direction of these effects are determined by the relative strength of opposing, but related, mechanisms. A. mexicanum nuts provide H. desmarestianus with a critical food resource, and while seed predation on A. mexicanum nuts by H. desmarestianus is very intense, A. mexicanum ultimately benefits because of the relatively high germination rates of its seeds that are dispersed by H. desmarestianus. ?? The Author(s) 2010.

  12. Arsenic-induced phosphate limitation under experimental Early Proterozoic oceanic conditions

    NASA Astrophysics Data System (ADS)

    Chi Fru, Ernest; Hemmingsson, Christoffer; Holm, Mikaela; Chiu, Beverly; Iñiguez, Enrique

    2016-01-01

    Comparison of phosphorus concentrations associated with modern hydrothermal Fe(III)(oxyhydr)oxides and ancient Fe(III) oxide-rich iron formations, is used to estimate bioavailable Precambrian marine phosphorus (P) concentrations. This led to the proposition of a low dissolved P budget of ˜10-25% of present-day levels, before ˜1.9 billion years ago. Estimates incorporating ancient marine Si levels ≥ 0.67 mM instead suggested global dissolved P levels greater than today. Here we unite current experimental models that have considered NaCl solutions containing elevated dissolved Fe(II), Si, Ca2+ and Mg2+ ions in the incorporation of P in Precambrian marine Fe(III)(oxyhydr)oxides, in addition to arsenic as a hydrothermal proxy. We show that the coprecipitation of dissolved P and Fe(III)(oxyhydr)oxides from arsenic-rich marine waters produces an average P distribution coefficient of ˜0.072 (± 0.01) μM-1. This is comparable to the ˜ 0.07 μM-1 predicted for Fe(III)(oxyhydr)oxides in modern arsenic-rich, submarine hydrothermal settings, from which the lower Early Proterozoic dissolved marine P concentrations were predicted. As/P molar ratios below modern seawater ratios removed the negative feedback effect high Si impose on P scavenging by Fe(III)(oxyhydr)oxides. The binding of As(III) to Fe(III)(oxyhydr)oxides exhibits a lower competitive influence on P fixation. As(V) that likely became prominent in the surficially oxidized Early Proterozoic oceans induced dissolved P limitation because of preferential P sequestration at the expense of dissolved As(V) enrichment. The control of As on P scavenging by the precipitating Fe(III)(oxyhydr)oxides is strong regardless of common seawater cations (Mg2+ and Ca2+). The data suggest that the application of Si and Fe(III)(oxyhydr)oxides as an ancient seawater P proxy should consider chemical variability between depositional basins, taking into account the rather strong role hydrothermal arsenic has on the distribution of P in

  13. CHEMICAL AND PHYSICAL CONDITIONS IN MOLECULAR CLOUD CORE DC 000.4-19.5 (SL42) IN CORONA AUSTRALIS

    SciTech Connect

    Hardegree-Ullman, E.; Whittet, D. C. B.; Harju, J.; Juvela, M.; Sipilae, O.; Hotzel, S.

    2013-01-20

    Chemical reactions in starless molecular clouds are heavily dependent on interactions between gas phase material and solid phase dust and ices. We have observed the abundance and distribution of molecular gases in the cold, starless core DC 000.4-19.5 (SL42) in Corona Australis using data from the Swedish ESO Submillimeter Telescope. We present column density maps determined from measurements of C{sup 18}O (J = 2-1, 1-0) and N{sub 2}H{sup +} (J = 1-0) emission features. Herschel data of the same region allow a direct comparison to the dust component of the cloud core and provide evidence for gas phase depletion of CO at the highest extinctions. The dust color temperature in the core calculated from Herschel maps ranges from roughly 10.7 to 14.0 K. This range agrees with the previous determinations from Infrared Space Observatory and Planck observations. The column density profile of the core can be fitted with a Plummer-like density distribution approaching n(r) {approx} r {sup -2} at large distances. The core structure deviates clearly from a critical Bonnor-Ebert sphere. Instead, the core appears to be gravitationally bound and to lack thermal and turbulent support against the pressure of the surrounding low-density material: it may therefore be in the process of slow contraction. We test two chemical models and find that a steady-state depletion model agrees with the observed C{sup 18}O column density profile and the observed N(C{sup 18}O) versus A{sub V} relationship.

  14. Benefits and limitations of pig slurry to reclaim bare mine soils under Mediterranean semiarid conditions

    NASA Astrophysics Data System (ADS)

    Zornoza, Raúl; Faz, Ángel; Acosta, Jose A.; Kabas, Sebla; Martínez-Martínez, Silvia; Ángeles Muñoz, M.

    2013-04-01

    In this study, the effects of pig slurry application on reclamation of mine soils from Cartagena-La Unión Mining District (SE Spain) were investigated in a field experiment. Exchangeable metals (Cd, Cu, Pb and Zn), total organic carbon, total nitrogen, soluble carbon, microbial biomass and three enzyme activities were periodically monitored during 67 days. In addition, one year after the application of the pig slurry, soil and developed vegetation was sampled. Results showed that only exchangeable Cd and Zn significantly decreased in the amended plots, mainly for Cd, with decreases of 98%. The rest of metals and chemical properties did not change with time after application of amendments, showing values not significantly different than those present before pig slurry application. Soluble carbon, microbial biomass carbon and the enzyme activities increased after the application of pig slurry. However, after various days these parameters started a decreasing trend until reaching values similar to the control from approximately day 25. Thus, mainly precipitation as phosphate from the waste was very effective for Cd immobilization. No increments were observed in soil organic carbon because the organic carbon applied with the slurry was too low to be significantly detected. Nonetheless, pig slurry is a good fertilizer owing to the high quantity of nutrients provided, needed to promote the development of vegetation. One year after application, a native vegetation cover (25-30%) was reached by spontaneous colonization. Triggered plant growth by the effect of amendment improved soil conditions, particularly by the help of the medium created by their rhizosphere systems. Increments in soil organic carbon and total nitrogen, and decreases in the exchangeable metals fraction concentration were observed in rhizospheric soils when compared to the bare soils. This improvement in soil quality mediated by vegetation was more efficient than the direct effect of the amendment. In

  15. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - II: Experimental verification

    NASA Astrophysics Data System (ADS)

    Hausmaninger, Thomas; Silander, Isak; Ma, Weiguang; Axner, Ove

    2016-01-01

    Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is normally described by an expression, here termed the conventional (CONV) description, that is restricted to the conventional cavity-limited weak absorption condition (CCLWA), i.e. when the single pass absorbance is significantly smaller than the empty cavity losses, i.e. when α0 L < < π / F. To describe NICE-OHMS signals beyond this limit two simplified extended descriptions (termed the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT), which are assumed to be valid under the relaxed cavity-limited weak absorption condition (RCLWA), i.e. when α0 L < π / F, and a full description (denoted FULL), presumed to be valid also when the α0 L < π / F condition does not hold, have recently been derived in an accompanying work (Ma W, et al. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical Description. J Quant Spectrosc Radiat Transfer, 2015, http://dx.doi.org/10.1016/j.jqsrt.2015.09.007). The present work constitutes an experimental verification and assessment of the validity of these, performed in the Doppler limit for a set of Fα0 L / π values (up to 3.5); it is shown under which conditions the various descriptions are valid. It is concluded that for samples with Fα0 L / π up to 0.01, all descriptions replicate the data well. It is shown that the CONV description is adequate and provides accurate assessments of the signal strength (and thereby the analyte concentration) up to Fα0 L / π of around 0.1, while the ELET is accurate for Fα0 L / π up to around 0.3. The ELFT description mimics the Db NICE-OHMS signal well for Fα0 L / π up to around unity, while the FULL description is adequate for all Fα0 L / π values investigated. Access to these descriptions both increases considerably the dynamic range of the technique and

  16. On the effect of accident conditions on the molten core debris relocation into lower head of a PWR vessel

    NASA Astrophysics Data System (ADS)

    An, Xuegao

    From 1975 to present, it has been found that the primary risk to the public health and safety from nuclear power reactors lies in ``beyond design basis'' accidents. During such severe accidents, melting of the reactor core may lead to a loss of primary system integrity, or even containment failure, which will allow escape of significant amounts of radioactive material to the environment. It is very important to understand the mechanism of reactor core degradation during a severe accident. In this study, the damage progression of the reactor core and the slumping mechanism of molten material to the lower head of the reactor vessel were examined through simulation of severe accident scenarios that lead to large-scale core damage. The calculations were carried out using the computer code SCDAP/RELAP5. Different modeling parameters or models were used in calculations by version MOD3.2. The cladding oxidation shell ``durability'' parameter, which can control the timing of fuel clad failure, was varied. The heat flux model of steady-state natural convection of the molten pool was changed. The ultimate strength of the crust supporting the molten pool was doubled. These changes were made to examine the effects on the calculated core damage, and the molten pool expansion and its slumping. Different accident scenarios were simulated. The HPI/makeup flow rates were changed. The timing of opening and closing the PORV was considered. Reflood by restart of coolant pump 2B was also studied. Finally, the size of the PORV opening was also changed. The effects of these accident scenarios on accident progression and core damage process were studied. From the calculated results, it was concluded that the accurate modeling of core damage phenomena was very important to the prediction of the later stage of an accident. According to code MOD3.2, the molten material in a pool slumped to the lower head of the reactor vessel when the juncture of the top and side crusts failed after the

  17. The initial conditions of isolated star formation - IX. Akari mapping of an externally heated pre-stellar core

    NASA Astrophysics Data System (ADS)

    Nutter, D.; Stamatellos, D.; Ward-Thompson, D.

    2009-07-01

    We present observations of L1155 and L1148 in the Cepheus molecular cloud, taken using the Far Infrared Surveyor (FIS) instrument on the Akari satellite. We compare these data to submillimetre data taken using the Submillimetre Common-User Bolometer Array (SCUBA) camera on the James Clerk Maxwell Telescope, and far-infrared data taken with the imaging photo-polarimeter (ISOPHOT) camera on board the Infrared Space Observatory (ISO) satellite. The Akari data cover a similar spectral window and are consistent with the ISO data. All of the data show a relation between the position of the peak of emission and the wavelength for the core of L1155. We interpret this as a temperature gradient. We fit modified blackbody curves to the spectral energy distributions at two positions in the core and see that the central core in L1155 (L1155C) is approximately 2° warmer at one edge than it is in the centre. We consider a number of possible heating sources and conclude that the A6V star BD+67 1263 is the most likely candidate. This star is at a distance of 0.7pc from the front of L1155C in the plane of the sky. We carry out radiative transfer modelling of the L1155C core including the effects from the nearby star. We find that we can generate a good fit to the observed data at all wavelengths, and demonstrate that the different morphologies of the core at different wavelengths can be explained by the observed 2° temperature gradient. The L1148 core exhibits a similar morphology to that of L1155C, and the data are also consistent with a temperature gradient across the core. In this case, the most likely heating source is the star BD197053. Our findings illustrate very clearly that the apparent observed morphology of a pre-stellar core can be highly dependent on the wavelength of the observation, and that temperature gradients must be taken into account before converting images into column density distributions. This is important to note when interpreting Akari and Spitzer data

  18. 3D scalar model as a 4D perfect conductor limit: Dimensional reduction and variational boundary conditions

    SciTech Connect

    Edery, Ariel; Graham, Noah; MacDonald, Ilana

    2009-06-15

    Under dimensional reduction, a system in D spacetime dimensions will not necessarily yield its D-1-dimensional analog version. Among other things, this result will depend on the boundary conditions and the dimension D of the system. We investigate this question for scalar and Abelian gauge fields under boundary conditions that obey the symmetries of the action. We apply our findings to the Casimir piston, an ideal system for detecting boundary effects. Our investigation is not limited to extra dimensions and we show that the original piston scenario proposed in 2004, a toy model involving a scalar field in 3D (2+1) dimensions, can be obtained via dimensional reduction from a more realistic 4D electromagnetic (EM) system. We show that for perfect conductor conditions, a D-dimensional EM field reduces to a D-1 scalar field and not its lower-dimensional version. For Dirichlet boundary conditions, no theory is recovered under dimensional reduction and the Casimir pressure goes to zero in any dimension. This ''zero Dirichlet'' result is useful for understanding the EM case. We then identify two special systems where the lower-dimensional version is recovered in any dimension: systems with perfect magnetic conductor (PMC) and Neumann boundary conditions. We show that these two boundary conditions can be obtained from a variational procedure in which the action vanishes outside the bounded region. The fields are free to vary on the surface and have zero modes, which survive after dimensional reduction.

  19. VLBI FOR GRAVITY PROBE B. III. A LIMIT ON THE PROPER MOTION OF THE 'CORE' OF THE QUASAR 3C 454.3

    SciTech Connect

    Bartel, N.; Bietenholz, M. F.; Ransom, R. R.; Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.; Lederman, J. I.; Petrov, L.

    2012-07-01

    We made very long baseline interferometry observations at 8.4 GHz between 1997 and 2005 to estimate the coordinates of the 'core' component of the superluminal quasar, 3C 454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope Relativity Mission, Gravity Probe B (GP-B). These coordinates are determined relative to those of the brightness peaks of two other compact extragalactic sources, B2250+194 and B2252+172, nearby on the sky, and within a celestial reference frame (CRF), defined by a large suite of compact extragalactic radio sources, and nearly identical to the International Celestial Reference Frame 2 (ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each other, and also in the CRF, to within 1{sigma} upper limits of 15 and 30 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. The core of 3C 454.3 appears to jitter in its position along the jet direction over {approx}0.2 mas, likely due to activity close to the putative supermassive black hole nearby, but on average is stationary in the CRF within 1{sigma} upper limits on its proper motion of 39 {mu}as yr{sup -1} (1.0c) and 30 {mu}as yr{sup -1} (0.8c) in {alpha} and {delta}, respectively, for the period 2002-2005. Our corresponding limit over the longer interval, 1998-2005, of more importance to GP-B, is 46 and 56 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. Some of 3C 454.3's jet components show significantly superluminal motion with speeds of up to {approx}200 {mu}as yr{sup -1} or 5c in the CRF. The core of 3C 454.3 thus provides for GP-B a sufficiently stable reference in the distant universe.

  20. NMDA antagonist MK 801 in nucleus accumbens core but not shell disrupts the restraint stress-induced reinstatement of extinguished cocaine-conditioned place preference in rats.

    PubMed

    De Giovanni, Laura N; Guzman, Andrea S; Virgolini, Miriam B; Cancela, Liliana M

    2016-12-15

    Relapse is a common feature of cocaine addiction. In rodents, it can be elicited by cues, stress or the drug. Restraint stress-induced reinstatement of cocaine-conditioned place preference (CPP) is a useful model to study the mechanisms involved in stress-induced relapse of drug-seeking behavior. There is evidence that the glutamate NMDA receptors are critically involved in drug- and cue-induced reinstatement of seeking behavior and drug-CPP responses. The aim of this study was to investigate the contribution of NMDA receptors within core vs. shell nucleus accumbens (NAc) subregions to restraint stress-induced reinstatement of extinguished cocaine-CPP. After extinction of cocaine-conditioned preference, animals were administered MK 801 systemically or directly into intra-core or intra-shell, and restrained for 30min or left undisturbed in their home-cages. First, we demonstrated that restraint stress-induced reinstatement of extinguished cocaine-CPP depends on the duration of restraint as well as on the context in which it is applied. Second, this effect was blocked by systemic MK 801 administration either before or after restraint. Third, intra-core but not intra-shell administration abrogated the restraint stress-induced reinstatement. These findings show that NMDA receptors within NAc core, but not shell, play a critical role in restraint stress-induced reinstatement of cocaine-CPP. PMID:27506656

  1. The behavior of fuel-lean premixed flames in a standard flammability limit tube under controlled gravity conditions

    NASA Technical Reports Server (NTRS)

    Wherley, B. L.; Strehlow, R. A.

    1986-01-01

    Fuel-lean flames in methane-air mixtures from 4.90 to 6.20 volume percent fuel and propane-air mixtures from 1.90 to 3.00 volume percent fuel were studied in the vicinity of the limit for a variety of gravity conditions. The limits were determined and the behavior of the flames studied for one g upward, one g downward, and zero g propagation. Photographic records of all flammability tube firings were obtained. The structure and behavior of these flames were detailed including the variations of the curvature of the flame front, the skirt length, and the occurrence of cellular instabilities with varying gravity conditions. The effect of ignition was also discussed. A survey of flame speeds as a function of mixture strength was made over a range of lean mixture compositions for each of the fuels studied. The results were presented graphically with those obtained by other researchers. The flame speed for constant fractional gravity loadings were plotted as a function of gravity loadings from 0.0 up to 2.0 g's against flame speeds extracted from the transient gravity flame histories for corresponding gravity loadings. The effects of varying gravity conditions on the extinguishment process for upward and downward propagating flames were investigated.

  2. Towards lag phase of microbial populations at growth-limiting conditions: The role of the variability in the growth limits of individual cells.

    PubMed

    Aguirre, Juan S; Koutsoumanis, Konstantinos P

    2016-05-01

    The water activity (aw) growth limits of unheated and heat stressed Listeria monocytogenes individual cells were studied. The aw limits varied from 0.940 to 0.997 and 0.951 to 0.997 for unheated and heat stressed cells, respectively. Due to the above variability a decrease in aw results in the presence of a non-growing fraction in the population leading to an additional pseudo-lag in population growth. In this case the total apparent lag of the population is the sum of the physiological lag of the growing cells (time required to adjust to the new environment) and the pseudo-lag. To investigate the effect of aw on the above lag components, the growth kinetics of L. monocytogenes on tryptone soy agar with aw adjusted to values ranging from 0.997 to 0.940 was monitored. The model of B&R was fitted to the data for the estimation of the apparent lag. In order to estimate the physiological lag of the growing fraction of the inoculum, the model was refitted to the growth data using as initial population level the number of cells that were able to grow (estimated from the number of colonies formed on the agar at the end of storage) and excluding the rest data during the lag. The results showed that for the unheated cells the apparent lag was almost identical to the physiological lag for aw values ranging from 0.997 to 0.970, as the majority of the cells in the initial population was able to grow in these conditions. As the aw decreased from 0.970 to 0.940 however, the number of cells in the population which were able to grow, decreased resulting to an increase in the pseudo-lag. The maximum value of pseudo-lag was 13.1h and it was observed at aw=0.940 where 10% of the total inoculated cells were able to grow. For heat stressed populations a pseudo-lag started to increase at higher aw conditions (0.982) compared to unheated cells. In contrast to the apparent lag, a linear relation between physiological lag and aw was observed for both unheated and heat stressed cells. PMID

  3. Impaired growth under iron-limiting conditions associated with the acquisition of colistin resistance in Acinetobacter baumannii.

    PubMed

    López-Rojas, Rafael; García-Quintanilla, Meritxell; Labrador-Herrera, Gema; Pachón, Jerónimo; McConnell, Michael J

    2016-06-01

    Acquisition of colistin resistance in Acinetobacter baumannii has been associated with reduced bacterial fitness and virulence, although the mechanisms underlying this fitness loss have not been well characterised. In this study, the role played by environmental iron levels on the growth and survival of colistin-resistant strains of A. baumannii was assessed. Growth assays with the colistin-susceptible ATCC 19606 strain and its colistin-resistant derivative RC64 [colistin minimum inhibitory concentration (MIC) of 64 mg/L] demonstrated that the strains grew similarly in rich laboratory medium (Mueller-Hinton broth), whereas RC64 demonstrated impaired growth compared with ATCC 19606 in human serum (>100-fold at 24 h). Compared with RC64, ATCC 19606 grew in the presence of higher concentrations of the iron-specific chelator 2,2'-bipyridine and grew more readily under iron-limiting conditions in solid and liquid media. In addition, iron supplementation of human serum increased the growth of RC64 compared with unsupplemented human serum to a greater extent than ATCC 19606. The ability of 11 colistin-resistant clinical isolates with mutations in the pmrB gene to grow in iron-replete and iron-limiting conditions was assessed, demonstrating that eight of the strains showed reduced growth under iron limitation. Individual mutations in the pmrB gene did not directly correlate with a decreased capacity for growth under iron limitation, suggesting that mutations in pmrB may not directly produce this phenotype. Together these results indicate that acquisition of colistin resistance in A. baumannii can be associated with a decreased ability to grow in low-iron environments. PMID:27179817

  4. The HITECH Act and electronic health records' limitation in coordinating care for children with complex chronic conditions.

    PubMed

    Cook, Jason E

    2014-01-01

    While the HITECH Act was implemented to promote the use of electronic health records to improve the quality and coordination of healthcare, the limitations established to the setting of the hospital or physician's office affect the care coordination for those who utilize many health-related services outside these settings, including children with complex and chronic conditions. Incentive-based support or nationally supported electronic health record systems for allied and other healthcare professionals are necessary to see the full impact that electronic health records can have on care coordination for individuals who utilize many skilled healthcare services that are not associated with a hospital or physician's office. PMID:24925039

  5. The Axial Ratio of hcp Fe and Fe-Ni-Si Alloys to the Conditions of Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Fischer, R. A.; Campbell, A. J.

    2015-12-01

    The Earth's iron-rich inner core is seismically anisotropic, which may be due to the preferred orientation of Fe-rich hexagonal close packed (hcp) alloy crystals. Elastic anisotropy in a hexagonal crystal is related to its c/a axial ratio; therefore, it is important to know how this ratio depends on volume (or pressure), temperature, and composition. Experimental data on the axial ratio of iron and alloys in the Fe-Ni-Si system from 15 previous studies are combined here to parameterize the effects of these variables. The axial ratio increases with increasing volume, temperature, silicon content, and nickel content. When an hcp phase coexists with another structure, sample recovery and chemical analysis from each pressure-temperature point is one method for determining the phase's composition and thus the position of the phase boundary. An alternate method is demonstrated here, using this parameterization to calculate the composition of an hcp phase whose volume, temperature, and axial ratio are measured. The hcp to hcp+B2 phase boundary in the Fe-FeSi system is parameterized as a function of pressure, temperature, and composition, showing that a silicon-rich inner core may be an hcp+B2 mixture. These findings could help explain observations of a layered seismic anisotropy structure in the Earth's inner core.

  6. Extreme metamorphism in a firn core from the Allan Hills, Antarctica, as an analogue for glacial conditions

    NASA Astrophysics Data System (ADS)

    Dadic, Ruzica; Schneebeli, Martin; Bertler, Nancy; Schwikowski, Margit; Matzl, Margret

    2015-04-01

    Understanding processes in near-zero accumulation areas can help to better understand the ranges of isotopic composition in ice cores, particularly during ice ages, when accumulation rates were lower than today. Snow metamorphism is a primary driver of the transition from snow to ice and can be accompanied by altered isotopic compositions and chemical species concentration. High degree snow metamorphism, which results in major structural changes, is little-studied but has been identified in certain places in Antarctica. Here we report on a 5-m firn core collected adjacent to a blue-ice field in the Allan Hills, Antarctica. We determined the physical properties of the snow using computer tomography (microCT) and measured the isotopic composition of δD and δ18O, as well as 210Pb activity. The core shows a high degree of snow metamorphism and an exponential decrease in specific surface area (SSA), but no clear densification, with depth. The micro-CT measurements show a homogenous and stable structure throughout the entire core, with obvious erosion features in the near-surface, where high-resolution data is available. The observed firn structure is likely caused by a combination of unique depositional and post-depositional processes. The defining depositional process is the impact deposition under high winds and with a high initial density. The defining post-depositional processes are a) increased moisture transport due to forced ventilation and high winds and b) decades of temperature-gradient driven metamorphic growth in the near surface due to prolonged exposure to seasonal temperature cycling. Both post-processes are enhanced in low accumulation regions where snow stays close to surface for a long time. We observe an irregular signal in δD and δ18O that does not follow the stratigraphic sequence. The isotopic signal is likely caused by the same post-depositional processes that are responsible for the firn structure, and that are driven by local climate

  7. A Comparison Between the Burn Condition of Deuterium-Tritium and Deuterium-Helium-3 Reaction and Stability Limits

    NASA Astrophysics Data System (ADS)

    Motevalli, Seyed Mohammad; Fadaei, Fereshteh

    2015-02-01

    The nuclear reaction of deuterium-tritium (D-T) fusion by the usual magnetic or inertial confinement suffers from a number of difficulties and problems caused by tritium handling, neutron damage to materials and neutron-induced radioactivity, etc. The study of the nuclear synthesis reaction of deuterium-helium-3 (D-3He) at low collision energies (below 1 keV) is of interest for its applications in nuclear physics and astrophysics. Spherical tokamak (ST) reactors have a low aspect ratio and can confine plasma with β≈1. These capabilities of ST reactors are due to the use of the alternative D-3He reaction. In this work, the burn condition of D-3He reaction was calculated by using zero-dimensional particles and power equations, and, with the use of the parameters of the ST reactor, the stability limit of D-3He reaction was calculated and then the results were compared with those of D-T reaction. The obtained results show that the burn conditions of D-3He reaction required a higher temperature and had a much more limited temperature range in comparison to those of D-T reaction.

  8. Oxygen Response of the Wine Yeast Saccharomyces cerevisiae EC1118 Grown under Carbon-Sufficient, Nitrogen-Limited Enological Conditions

    PubMed Central

    Aceituno, Felipe F.; Orellana, Marcelo; Torres, Jorge; Mendoza, Sebastián; Slater, Alex W.; Melo, Francisco

    2012-01-01

    Discrete additions of oxygen play a critical role in alcoholic fermentation. However, few studies have quantitated the fate of dissolved oxygen and its impact on wine yeast cell physiology under enological conditions. We simulated the range of dissolved oxygen concentrations that occur after a pump-over during the winemaking process by sparging nitrogen-limited continuous cultures with oxygen-nitrogen gaseous mixtures. When the dissolved oxygen concentration increased from 1.2 to 2.7 μM, yeast cells changed from a fully fermentative to a mixed respirofermentative metabolism. This transition is characterized by a switch in the operation of the tricarboxylic acid cycle (TCA) and an activation of NADH shuttling from the cytosol to mitochondria. Nevertheless, fermentative ethanol production remained the major cytosolic NADH sink under all oxygen conditions, suggesting that the limitation of mitochondrial NADH reoxidation is the major cause of the Crabtree effect. This is reinforced by the induction of several key respiratory genes by oxygen, despite the high sugar concentration, indicating that oxygen overrides glucose repression. Genes associated with other processes, such as proline uptake, cell wall remodeling, and oxidative stress, were also significantly affected by oxygen. The results of this study indicate that respiration is responsible for a substantial part of the oxygen response in yeast cells during alcoholic fermentation. This information will facilitate the development of temporal oxygen addition strategies to optimize yeast performance in industrial fermentations. PMID:23001663

  9. Fate of dissolved toluene during steady infiltration throughout unsaturated soil: II. Biotransformation under nutrient-limited conditions

    SciTech Connect

    Allen-King, R.M.; Gillham, R.W.; Barker, J.F.; Sudicky, E.A.

    1996-03-01

    Biotransformation rates for dissolved toluene in unsaturated sandy soil were determined in dynamic column infiltration experiments. Transformation rates under N-limited conditions and in the presence of sufficient oxygen were 8 to 35 mg (kg d){sup {minus}1} and appeared to follow zero order kinetics. Toluene-degrading microoganisms were demonstrated to increase significantly in both activity and numbers with exposure to toluene. Relatively low CO{sub 2} production to oxygen consumption ratios were observed during these experiments suggesting incomplete toluene mineralization. Over the ranges tested, water flux (20-80 cm d{sup {minus}1}) and toluene concentration (4-46 mg L{sup {minus}1}) appeared to have a secondary control on rate relative to nutrient and/or oxygen limitations. Under conditions where the oxygen concentration was near zero due to removal of toluene degradation in the soil columns, the transformation rate was sufficiently low to be insignificant relative to column residence time. 32 refs., 5 figs., 4 tabs.

  10. A New Methodology for Open Pit Slope Design in Karst-Prone Ground Conditions Based on Integrated Stochastic-Limit Equilibrium Analysis

    NASA Astrophysics Data System (ADS)

    Zhang, Ke; Cao, Ping; Ma, Guowei; Fan, Wenchen; Meng, Jingjing; Li, Kaihui

    2016-07-01

    Using the Chengmenshan Copper Mine as a case study, a new methodology for open pit slope design in karst-prone ground conditions is presented based on integrated stochastic-limit equilibrium analysis. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, SLIDE simulation and bisection method optimization. Borehole investigations are performed, and the statistical result shows that the length of the karst cave fits a negative exponential distribution model, but the length of carbonatite does not exactly follow any standard distribution. The inverse transform method and acceptance-rejection method are used to reproduce the length of the karst cave and carbonatite, respectively. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.

  11. The Effect of Nickel on the Seismic Wave Belocities of Iron at the Pressure Conditions of the Earth's Core

    NASA Astrophysics Data System (ADS)

    Martorell Masip, B.; Vocadlo, L.; Brodholt, J. P.; Wood, I.

    2011-12-01

    Understanding the physical properties of the Earth's core is a key step in the study of the evolution and dynamics of our planet. For much of the last century, based on studies of meteorites [1], it was believed that Earth's core was predominantly a mixture of iron and nickel. More specifically, the Earth's inner core is a solid Fe-Ni alloy at high temperature (T, 6000 K) and high pressure (P, 360 GPa). Furthermore, to account for the lower than expected density in the Earth's core, it has been suggested that light elements must also be present [2]. While the effect of light elements on the properties of iron have been the subject of an extensive literature [3-6], the effect of nickel on the properties of iron has often been overlooked; this is due to the expectation, based on their proximity in the periodic table, that the properties of Ni are sufficiently similar to those of iron that the presence of nickel can be neglected. Although recent research using high P-T experiments and theoretical studies of Fe-Ni alloys has been performed in order to establish whether nickel affects the physical properties of iron, the results have been inconclusive and sometimes contradictory [7-11]. Here we present a DFT study of the athermal elastic properties of solid Fe-Ni alloys at core pressures using the GGA. We have calculated the equation of state (EoS) for Fe-Ni alloys at several compositions for bcc, fcc and hcp structures, and fitted the results to Birch-Murnaghan 3rd order equations of state. We have also calculated the elastic constants for each structure at 360 GPa and evaluated the seismic wave velocities. Our results show that the effect of small amounts of Ni is significant (-1.9% in vp and -4.0% in vs for hcp structure of Fe93.25-Ni6.75 alloy), and therefore nickel must be taken into account if a detailed model of the Earth's inner core is to be constructed. Other aspects of the influence of nickel, such as its effect on the high P-T phase diagram and melting curve

  12. Testing phenotypic trade-offs in the chemical defence strategy of Scots pine under growth-limiting field conditions.

    PubMed

    Villari, Caterina; Faccoli, Massimo; Battisti, Andrea; Bonello, Pierluigi; Marini, Lorenzo

    2014-09-01

    Plants protect themselves from pathogens and herbivores through fine-tuned resource allocation, including trade-offs among resource investments to support constitutive and inducible defences. However, empirical research, especially concerning conifers growing under natural conditions, is still scarce. We investigated the complexity of constitutive and induced defences in a natural Scots pine (Pinus sylvestris L.) stand under growth-limiting conditions typical of alpine environments. Phenotypic trade-offs at three hierarchical levels were tested by investigating the behaviour of phenolic compounds and terpenoids of outer bark and phloem. We tested resource-derived phenotypic correlations between (i) constitutive and inducible defences vs tree ring growth, (ii) different constitutive defence metabolites and (iii) constitutive concentration and inducible variation of individual metabolites. Tree ring growth was positively correlated only with constitutive concentration of total terpenoids, and no overall phenotypic trade-offs between different constitutive defensive metabolites were found. At the lowest hierarchical level tested, i.e., at the level of relationship between constitutive and inducible variation of individual metabolites, we found that different compounds displayed different behaviours; we identified five different defensive metabolite response types, based on direction and strength of the response, regardless of tree age and growth rate. Therefore, under growth-limiting field conditions, Scots pine appears to utilize varied and complex outer bark and phloem defence chemistry, in which only part of the constitutive specialized metabolism is influenced by tree growth, and individual components do not appear to be expressed in a mutually exclusive manner in either constitutive or inducible metabolism. PMID:25194142

  13. Potassium Transporter KUP7 Is Involved in K(+) Acquisition and Translocation in Arabidopsis Root under K(+)-Limited Conditions.

    PubMed

    Han, Min; Wu, Wei; Wu, Wei-Hua; Wang, Yi

    2016-03-01

    Potassium (K(+)) is one of the essential macronutrients for plant growth and development. K(+) uptake from environment and K(+) translocation in plants are conducted by K(+) channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K(+) uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on low-K(+) medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K(+) uptake rate and K(+) content in xylem sap under K(+)-deficient conditions. Thus, the K(+) content in kup7 shoot was significantly reduced under low-K(+) conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K(+) transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level in Arabidopsis root. Together, our data demonstrated that KUP7 is crucial for K(+) uptake in Arabidopsis root and might be also involved in K(+) transport into xylem sap, affecting K(+) translocation from root toward shoot, especially under K(+)-limited conditions. PMID:26851373

  14. Multi-Physics Feedback Simulations with Realistic Initial Conditions of the Formation of Star Clusters: From Large Scale Magnetized Clouds to Turbulent Clumps to Cores to Stars

    NASA Astrophysics Data System (ADS)

    Klein, R. I.; Li, P.; McKee, C. F.

    2015-10-01

    Multi-physics zoom-in adaptive mesh refinement simulations with feedback and realistic initial conditions, starting from large scale turbulent molecular clouds through the formation of clumps and cores to the formation os stellar clusters are presented. I give a summary of results at the different scales undergoing gravitational collapse from cloud to core to cluster formation. Detailed comparisons with observations are made at each stage of the simulations. In particular, properties of the magnetized clumps are compared with recent observations of Crutcher et al. 2010 and Crutcher 2012 and the magnetic field orientation in cloud clumps relative to the global mean field of the inter-cloud medium (Li et al. 2009). The Initial Mass Function (IMF) obtained is compared with the Chabrier IMF and the protostellar mass function of the cluster is compared with different theories.

  15. Magnetic phase diagrams and thermal equations of state of Fe7C3 and Fe3C up to the pressure-temperature conditions of Earth's core

    NASA Astrophysics Data System (ADS)

    Liu, J.; Li, Z.; Chen, B.; Li, J.; Ikuta, D.; Smith, J.; Sinogeikin, S. V.; Popov, D.; Kenney-Benson, C.

    2015-12-01

    Iron carbides Fe7C3 and Fe3C have been proposed as candidates for the dominant components of the Earth's inner core to explain its density deficit and velocity discrepancy with respect to those of pure iron at relevant pressure-temperature conditions (e.g. Chen et al., 2012; Chen et al., 2014; Gao et al., 2011). Testing the hypothesis of carbon-rich inner core requires knowledge of the thermal equations of state of the iron carbides to megabar pressures. Existing experimental data, however, are restricted to either ambient temperature or the pressures near the top of the lower mantle. In particular, the thermal expansion coefficients of the carbides under high pressures remain poorly constrained. Previous studies showed that both Fe7C3 an Fe3C are Invar-type alloys with extremely low thermal expansions in the ferromagnetic phases, and their thermal expansion coefficients more than triple across the ferromagnetic-paramagnetic transition at 1 bar (Litasov et al., 2015). On the other hand, both iron carbides experience pressure-induced spin transitions under high pressures (e.g. Chen et al., 2012; Prescher et al., 2012), but their effects on the thermal expansion are still unknown. We conducted synchrotron X-ray diffraction measurements on Fe7C3 and Fe3C up to the core's pressure and temperature conditions. High pressures up to ~140 GPa were generated by using diamond anvil cells (DAC), while high temperatures were generated using the whole-cell resistive heating device up to 700 K, and using the double-sided laser-heating system up to ~ 3500 K. The new data allow us to construct the magnetic phase diagrams of Fe7C3 and Fe3C and to assess the influences of magnetic transitions on their thermal expansion coefficients. The density profiles of appropriate magnetic phases are calculated and compared with that of the Earth's inner core to estimate its carbon content.

  16. Permeability Evolution During Reactive Flow Experiments on Cores Under CO2 Sequestration Conditions and Development of Fully Coupled Reactive Flow Simulations at the Reservoir Scale

    NASA Astrophysics Data System (ADS)

    Saar, M. O.; Kong, X. Z.; Luhmann, A. J.; Tutolo, B. M.; Seyfried, W. E., Jr.

    2015-12-01

    Physical, chemical, thermal, and mechanical processes can modify permeability and affect CO2 injectivity and reactive fluid flow during geologic CO2 sequestration. Here we report permeability evolutions observed in core-flood experiments using CO2-charged fluids under various formation conditions. Temperature-series experiments on consolidated dolomite cores show a permeability increase due to dissolution, followed by a two-step permeability decrease due to CO2 exsolution and secondary dolomite precipitation, as temperature is increased from 21 to 50°C and then to 100°C, respectively. CO2 mass balance calculations suggest that, under dynamic steady-state conditions, CO2 saturation and its relative permeability can only reach up to ~0.5 and ~0.0065, respectively. Permeability reductions of ~1/3 and mass losses of ~2% are observed both in a 52-day recycling and in two 3-day single-pass experiments with K-feldspar-rich sandstone (150°C, 200 bar). Water chemistry, SEM, and XRCT data suggest feldspar dissolution and precipitation of either boehmite (recycling) or kaolinite (single-pass) during the experiments. These observations indicate that permeability can decrease with increasing porosity due to mineral precipitation in critical pore throats. Single-pass experiments on nine dolomite cores (150°C and 150 bar with NaCl) reveal permeability enhancements and dissolution patterns at different flow rates. Permeability-porosity data indicate an increase in permeability enhancement rate per increase in porosity with reaction progress as dissolution channels lengthen along the core. These experimental observations provide the requisite data for informing up-scaled, fully-coupled reactive transport simulations of CO2 sequestration in interbedded siliclastic-carbonate sedimentary reservoirs, which we present.

  17. ATP production from adenine by a self-coupling enzymatic process: high-level accumulation under ammonium-limited conditions.

    PubMed

    Maruyama, A; Fujio, T

    2001-03-01

    To improve ATP production from adenine, we optimized cultivation and reaction conditions for the ATP producing strain, Corynebacterium ammoniagenes KY13510. In the conventional method, 28% NH4OH has been used both to adjust pH during cultivation and reaction, and to provide nitrogen for cell growth. In the ATP-producing reaction, high concentrations of inorganic phosphate and magnesium ion are needed, which form magnesium ammonium phosphate (MgNH4PO4) precipitate. To keep inorganic phosphate and magnesium ions soluble in the reaction mixture, it was indispensable to add phytic acid as a chelating agent of divalent metal ions. Under such conditions, 37 mg/ml (61.2 mM) ATP was accumulated in 13 h (Appl. Microbiol. Biotechnol. 21, 143 1985). If ammonium ion was depleted from the reaction mixture to avoid MgNH4 PO4 formation, we expected that there was no need to add phytic acid and ATP accumulation might be improved. Therefore, we obtained the cultured broth of C. ammoniagenes KY13510 strain with low ammonium ion content (less than 1 mg/ml as NH3) by the method that a part of alkali solution (28% NH4OH) for pH control was replaced with 10 N KOH. Using this culture broth, ATP producing reaction was done in 2-liter jar fermentor, controlling the pH of the reaction mixture with 10 N KOH. Under these conditions, the rate of ATP accumulation improved greatly, and 70.6 mg/ml (117 mM) ATP was accumulated in 28 h. The molar conversion ratio from adenine to ATP was about 82%. Phytic acid was slightly inhibitory to ATP formation under these ammonium-limited conditions. PMID:11330681

  18. Preservation of deep Himalayan PT conditions that formed during multiple events in garnet cores: Mylonitization produces erroneous results for rims

    NASA Astrophysics Data System (ADS)

    Sapkota, J.; Sanislav, I. V.

    2013-03-01

    The Kathmandu Thrust Sheet, which overlies the Lesser Himalayas along the southern part of the Main Central Thrust (MCT) and forms the leading edge of the Higher Himalayan crystalline rocks, is folded at a regional scale by the Gorkha-Kathmandu fold couplet in Central Nepal. Garnet porphyroblasts lying close to the MCT within this thrust sheet preserve structural and metamorphic history that predates mylonitization during thrust emplacement. The succession of five FIA sets preserved within these porphyroblasts formed due to changes in the direction of India's motion relative to Asia after they collided. The intersection of Fe, Ca and Mn isopleths for garnet cores reveals that FIA sets 1, 2, 3, 4 and 5 nucleated respectively at 6.2 kbar and 515 °C, 6-7 kbar and 545-550 °C, 6.6 kbar and 530 °C, 5.6-6.2 kbar and 525-550 °C and 6.8-6.9 kbar and 520-560 °C. The average PT mode of THERMOCALC, which relies on equilibrium being achieved between the garnet rims and the matrix, gives pressures around 11 kbar that do not accord with the lengthy succession of lower core pressures. The many foliations in the matrix, which formed during top to the south thrusting plus subsequent deformations that eventually led to these rocks reaching the surface, truncate all foliations preserved within the porphyroblasts that are defined by inclusion trails. This has resulted in the garnet rims not being in equilibrium with the matrix and the anomalously high pressures. The garnet rims may have been affected by slow dissolution and solution transfer over the period of time that the matrix was deforming plastically at high strain rates as the rocks were uplifted. The assumption of equilibrium between garnet rims and surrounding silicates used by various rim geothermobarometric methods does not hold for these rocks.

  19. A relational understanding of sibling experiences of children with rare life-limiting conditions: findings from a qualitative study.

    PubMed

    Malcolm, Cari; Gibson, Faith; Adams, Sally; Anderson, Gillian; Forbat, Liz

    2014-09-01

    Mucopolysaccharidoses (MPS) and Batten disease are rare life-limiting conditions (LLCs) characterised by progressive and permanent physical and cognitive decline. The impact of such conditions on families, and notably on siblings, has not yet been described or documented. This paper presents data from a UK-wide study that sought to understand the family experience of supporting a child with the rare degenerative LLCs of MPS and Batten disease. The aim of this paper is to report sibling experiences related to these rare degenerative and progressive conditions, in order to inform the future development of supportive interventions. Eight siblings of children with MPS (n = 7) and Batten Disease (n = 1) participated in semi-structured qualitative interviews. A card sort technique was utilised to support and engage the children. Siblings are clearly impacted emotionally, pragmatically and relationally by the ill health of another child in the family. The data indicate four key themes which demonstrate impacts on siblings: perceptions of the condition and its symptoms, impact on daily life, emotional consequences and ways of coping. Siblings often had considerable knowledge of the condition and took on important roles in symptom management. However, these experiences were in the context of managing relationships within the family (often protecting parents from an awareness of how much they knew) and relationships at school (including distraction from learning and being bullied by peers). The data highlight how sibling experiences are generated through a combination of negative disability discourses and support through peers and family members. The data indicate how these features shift as a consequence of witnessing the advancement of their brother's or sister's condition and the emotional sequelae of disease progression. Exploration of siblings' experiences of living with such rare progressive and degenerative LLCs suggest the focus of interventions to support this

  20. A physiological, biochemical and proteomic characterization of Saccharomyces cerevisiae trk1,2 transport mutants grown under limiting potassium conditions.

    PubMed

    Gelis, Samuel; González-Fernández, Raquel; Herrera, Rito; Jorrín, Jesús; Ramos, José

    2015-06-01

    Saccharomyces cerevisiae mutants lacking both isoforms of the main plasma membrane potassium transporter display impaired potassium transport and defective growth at limiting concentrations of the cation. Moreover, they are hyperpolarized and have a lower intracellular pH than wild-type. In order to unravel global physiological processes altered in trk1,2 mutants, we have established conditions at which both wild-type and mutants can grow at different rates. Using a combination of physiological, biochemical and proteomic approaches, we show that during growth at suboptimal potassium concentrations, double trk1,2 mutants accumulate less potassium and reach lower yields. In contrast, the mutants maintain increased viability in the stationary phase and retain more potassium. Moreover, the mutants show increased expression of stress-related proteins such as catalase T, thioredoxin peroxidase or hexokinase 2, suggesting that they are better adapted to the additional stress factors associated with entry into stationary growth phase. PMID:25777080

  1. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical description

    NASA Astrophysics Data System (ADS)

    Ma, Weiguang; Silander, Isak; Hausmaninger, Thomas; Axner, Ove

    2016-01-01

    Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is conventionally described by an expression (here referred to as the CONV expression) that is restricted to the case when the single-pass absorbance, α0L, is much smaller than the empty cavity losses, π/F [here termed the conventional cavity-limited weak absorption (CCLWA) condition]. This limits the applicability of the technique, primarily its dynamic range and calibration capability. To remedy this, this work derives extended descriptions of Db NICE-OHMS that are not restricted to the CCLWA condition. First, the general principles of Db NICE-OHMS are scrutinized in some detail. Based solely upon a set of general assumptions, predominantly that it is appropriate to linearize the Beer-Lambert law, that the light is modulated to a triplet, and that the Pound-Drever-Hall sidebands are fully reflected, a general description of Db NICE-OHMS that is not limited to any specific restriction on α0L vs. π/F, here referred to as the FULL description, is derived. However, this description constitutes a set of equations to which no closed form solution has been found. Hence, it needs to be solved numerically (by iterations), which is inconvenient. To circumvent this, for the cases when α0L<π/F but without the requirement that the stronger CCLWA condition needs to be fulfilled, a couple of simplified extended expressions that are expressible in closed analytical form, referred to as the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT, have been derived. An analysis based on simulations validates the various descriptions and assesses to which extent they agree. It is shown that in the CCLWA limit, all extended descriptions revert to the CONV expression. The latter one deviates though from the extended ones for α0L around and above 0.1π/F. The two simplified extended descriptions agree

  2. Ab-initio study of the physics and chemistry of metals in planetary core materials and nanomaterials at relevant thermodynamics conditions

    NASA Astrophysics Data System (ADS)

    Alnemrat, Sufian

    Material science investigates the relationship between the structure of materials at the atomic or molecular scales and their macroscopic properties. Ab-initio DFT, atomistic force-field, and molecular dynamic simulations have been used to investigate the electronic, optical, structural, magnetic properties of group II-VI semiconductor nanoparticles, metal organic frameworks, amide-water complexes, and planetary core materials at the atomic and/or molecular level. Structure, density of electronic states, magnetic dipole moments, and HOMO-LUMO gaps of surface-passivated ZnnSem, Cd nTem, CdTe-core/ZnTe-shell, and ZnSe-core/CdSe-shell nanocrystals are calculated using a first principles. The intrinsic magnetic dipole moments are found to be strongly size dependent. The detailed analysis of the dipole moment as a function of particle size shows the appearance of zincblende-wurtzite polymorphism in these nano-particles. Energy-efficient adsorption processes are considered promising alternatives to traditional separation techniques. Mg-MOF-74, a magnesium-based metal organic framework, has been used as an efficient adsorbent structure for several gas separation purposes. Adsorption equilibria and kinetics of ethane, ethylene, propane, and propylene on Mg-MOF-74 were determined at temperatures of 278, 298, and 318 K and pressures up to 100 kPa. A grand canonical Monte Carlo simulation was conducted to calculate the adsorption isotherms and to explore adsorption mechanisms. I found that propylene and propane have a stronger affinity to the Mg-MOF-74 adsorbent than ethane and ethylene because of their significant dipole moments. Ab-initio molecular dynamics simulations were carried out to study the role of equilibrium volume and magnetism in Fe and FeX alloys (X=Ni, O) and their stability at earth core conditions. This study provides new insights into the pressure dependence of magnetism by tracking the hybridization between crystal orbitals for pressures up to 600 GPa in

  3. Pyruvate and Lactate Metabolism by Shewanella oneidensis MR-1 under Fermentation, Oxygen Limitation, and Fumarate Respiration Conditions

    SciTech Connect

    Pinchuk, Grigoriy E.; Geydebrekht, Oleg V.; Hill, Eric A.; Reed, Jennifer L.; Konopka, Allan; Beliaev, Alex S.; Fredrickson, Jim K.

    2011-12-30

    Shewanella oneidensis MR-1 is a facultative anaerobe growing by coupling organic matter oxidation to reduction of wide range of electron acceptors. Here we quantitatively assessed lactate and pyruvate metabolism of these bacteria under three distinct conditions: electron acceptor limited growth on lactate with O2 and fumarate, and pyruvate fermentation, which does not sustain growth but allows cells to survive for prolonged period. Using physiological and genetic approaches combined with flux balance analysis, we showed that the proportion of ATP produced by substrate-level phosphorylation varied from 33% to 72.5% of all ATP needed for growth depending on the electron acceptor nature and availability. While being indispensible for growth, respiration of fumarate does not contribute much to ATP generation and likely serves to remove formate, a product of pyruvate formate-lyase-catalyzed pyruvate disproportionation. Under both tested respiratory conditions S. oneidensis MR-1 carried out incomplete substrate oxidation, and TCA cycle did not contribute significantly to substrate oxidation. Pyruvate dehydrogenase reaction was not involved in lactate metabolism under O2 limitation, however was important for anaerobic growth probably supplying reducing equivalents for biosynthesis. Unexpectedly, obtained results suggest that pyruvate fermentation by S. oneidensis MR-1 cells represents a combination between substrate-level phosphorylation and a respiratory process, where pyruvate serves as electron donor and electron acceptor. Pyruvate reduction to lactate at the expense of formate oxidation is catalyzed by recently described new type of oxidative NAD(P)H independent D-lactate dehydrogenase (Dld-II). Based on involved enzymes localization we hypothesize that pyruvate reduction coupled to formate oxidation may be accompanied by proton motive force generation.

  4. Pyruvate and Lactate Metabolism by Shewanella oneidensis MR-1 under Fermentation, Oxygen Limitation, and Fumarate Respiration Conditions

    SciTech Connect

    Pinchuk, Grigoriy E.; Geydebrekht, Oleg V.; Hill, Eric A.; Reed, Jennifer L.; Konopka, Allan; Beliaev, Alex S.; Fredrickson, Jim K.

    2011-12-01

    Shewanella oneidensis MR-1 is a facultative anaerobe that derives energy by coupling organic matter oxidation to the reduction of wide range of electron acceptors. Here, we quantitatively assessed lactate and pyruvate metabolism of MR-1 under three distinct conditions: electron acceptor limited growth on lactate with O2; lactate with fumarate; and pyruvate fermentation. The latter does not support growth but provides energy for cell survival. Using physiological and genetic approaches combined with flux balance analysis, we showed that the proportion of ATP produced by substrate-level phosphorylation varied from 33% to 72.5% of that needed for growth depending on the electron acceptor nature and availability. While being indispensible for growth, respiration of fumarate does not contribute significantly to ATP generation and likely serves to remove formate, a product of pyruvate formate-lyase-catalyzed pyruvate disproportionation. Under both tested respiratory conditions S. oneidensis MR-1 carried out incomplete substrate oxidation, whereby the TCA cycle did not contribute significantly. Pyruvate dehydrogenase was not involved in lactate metabolism under O2 limitation but was required for anaerobic growth likely by supplying reducing equivalents for biosynthesis. The results suggest that pyruvate fermentation by S. oneidensis MR-1 cells represents a combination of substrate-level phosphorylation and respiration, where pyruvate serves as electron donor and electron acceptor. Pyruvate reduction to lactate at the expense of formate oxidation is catalyzed by recently described new type of oxidative NAD(P)H independent D-lactate dehydrogenase (Dld-II). The results further indicate that pyruvate reduction coupled to formate oxidation may be accompanied by proton motive force generation.

  5. Non-limiting food conditions for growth and production of the copepod community in a highly productive upwelling zone

    NASA Astrophysics Data System (ADS)

    Escribano, Rubén; Bustos-Ríos, Evelyn; Hidalgo, Pamela; Morales, Carmen E.

    2016-09-01

    Zooplankton production is critical for understanding marine ecosystem dynamics. This work estimates copepod growth and production in the coastal upwelling and coastal transition zones off central-southern Chile (~35 to 37°S) during a 3-year time series (2004, 2005, and 2006) at a fixed shelf station, and from spring-summer spatial surveys during the same period. To estimate copepod production (CP), we used species-biomasses and associated C-specific growth rates from temperature dependent equations (food-saturated) for the dominant species, which we assumed were maximal growth rates (gmax). Using chlorophyll-a concentrations as a proxy for food conditions, we determined a size-dependent half-saturation constant with the Michaelis-Menten equation to derive growth rates (g) under the effect of food limitation. These food-dependent C-specific growth rates were much lower (<0.1 d-1) than those observed in the field for the dominant species, while gmax for same species, in the range of 0.19-0.23 d-1 better represented the necessary growth to attain observed adult sizes of at least two copepods, Paracalanus cf. indicus and Calanus chilensis. Copepod biomass (CB) and rates of maximal copepod production (CPmax) obtained with gmax were higher in the coastal upwelling zone (<50 km from shore), and correlated significantly to oceanographic variables associated with upwelling conditions. Both CPmax and gmax exhibited negative trends at the fixed station from 2004 to 2006 in association with increased duration of upwelling in the latter year. Annual CPmax ranged between 24 and 52 g C m-2 y-1 with a mean annual P/B ratio of 7.3. We concluded that interannual variation in copepod production resulted from factors and processes regulating copepod abundance and biomass in the absence of bottom-up control, allowing copepods to grow without limitation due to food resources.

  6. Conditional solvation thermodynamics of isoleucine in model peptides and the limitations of the group-transfer model.

    PubMed

    Tomar, Dheeraj S; Weber, Valéry; Pettitt, B Montgomery; Asthagiri, D

    2014-04-17

    The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute-solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance. PMID:24650057

  7. Conditional Solvation Thermodynamics of Isoleucine in Model Peptides and the Limitations of the Group-Transfer Model

    PubMed Central

    2015-01-01

    The hydration thermodynamics of the amino acid X relative to the reference G (glycine) or the hydration thermodynamics of a small-molecule analog of the side chain of X is often used to model the contribution of X to protein stability and solution thermodynamics. We consider the reasons for successes and limitations of this approach by calculating and comparing the conditional excess free energy, enthalpy, and entropy of hydration of the isoleucine side chain in zwitterionic isoleucine, in extended penta-peptides, and in helical deca-peptides. Butane in gauche conformation serves as a small-molecule analog for the isoleucine side chain. Parsing the hydrophobic and hydrophilic contributions to hydration for the side chain shows that both of these aspects of hydration are context-sensitive. Furthermore, analyzing the solute–solvent interaction contribution to the conditional excess enthalpy of the side chain shows that what is nominally considered a property of the side chain includes entirely nonobvious contributions of the background. The context-sensitivity of hydrophobic and hydrophilic hydration and the conflation of background contributions with energetics attributed to the side chain limit the ability of a single scaling factor, such as the fractional solvent exposure of the group in the protein, to map the component energetic contributions of the model-compound data to their value in the protein. But ignoring the origin of cancellations in the underlying components the group-transfer model may appear to provide a reasonable estimate of the free energy for a given error tolerance. PMID:24650057

  8. Use of the Priestley-Taylor evaporation equation for soil water limited conditions in a small forest clearcut

    USGS Publications Warehouse

    Flint, A.L.; Childs, S.W.

    1991-01-01

    The Priestley-Taylor equation, a simplification of the Penman equation, was used to allow calculations of evapotranspiration under conditions where soil water supply limits evapotranspiration. The Priestley-Taylor coefficient, ??, was calculated to incorporate an exponential decrease in evapotranspiration as soil water content decreases. The method is appropriate for use when detailed meteorological measurements are not available. The data required to determine the parameter for the ?? coefficient are net radiation, soil heat flux, average air temperature, and soil water content. These values can be obtained from measurements or models. The dataset used in this report pertains to a partially vegetated clearcut forest site in southwest Oregon with soil depths ranging from 0.48 to 0.70 m and weathered bedrock below that. Evapotranspiration was estimated using the Bowen ratio method, and the calculated Priestley-Taylor coefficient was fitted to these estimates by nonlinear regression. The calculated Priestley-Taylor coefficient (?????) was found to be approximately 0.9 when the soil was near field capacity (0.225 cm3 cm-3). It was not until soil water content was less than 0.14 cm3 cm-3 that soil water supply limited evapotranspiration. The soil reached a final residual water content near 0.05 cm3 cm-3 at the end of the growing season. ?? 1991.

  9. The activity of nodules of the supernodulating mutant Mtsunn is not limited by photosynthesis under optimal growth conditions.

    PubMed

    Cabeza, Ricardo A; Lingner, Annika; Liese, Rebecca; Sulieman, Saad; Senbayram, Mehmet; Tränkner, Merle; Dittert, Klaus; Schulze, Joachim

    2014-01-01

    Legumes match the nodule number to the N demand of the plant. When a mutation in the regulatory mechanism deprives the plant of that ability, an excessive number of nodules are formed. These mutants show low productivity in the fields, mainly due to the high carbon burden caused through the necessity to supply numerous nodules. The objective of this study was to clarify whether through optimal conditions for growth and CO2 assimilation a higher nodule activity of a supernodulating mutant of Medicago truncatula (M. truncatula) can be induced. Several experimental approaches reveal that under the conditions of our experiments, the nitrogen fixation of the supernodulating mutant, designated as sunn (super numeric nodules), was not limited by photosynthesis. Higher specific nitrogen fixation activity could not be induced through short- or long-term increases in CO2 assimilation around shoots. Furthermore, a whole plant P depletion induced a decline in nitrogen fixation, however this decline did not occur significantly earlier in sunn plants, nor was it more intense compared to the wild-type. However, a distinctly different pattern of nitrogen fixation during the day/night cycles of the experiment indicates that the control of N2 fixing activity of the large number of nodules is an additional problem for the productivity of supernodulating mutants. PMID:24727372

  10. Anhydrobiosis in yeast: is it possible to reach anhydrobiosis for yeast grown in conditions with severe oxygen limitation?

    PubMed

    Rozenfelde, Linda; Rapoport, Alexander

    2014-08-01

    The yeast Saccharomyces cerevisiae was shown to be extremely sensitive to dehydration-rehydration treatments when stationary phase cells were subjected to conditions of severe oxygen limitation, unlike the same cells grown in aerobic conditions. The viability of dehydrated anaerobically grown yeast cells never exceeded 2 %. It was not possible to increase this viability using gradual rehydration of dry cells in water vapour, which usually strongly reduces damage to intracellular membranes. Specific pre-dehydration treatments significantly increased the resistance of anaerobic yeast to drying. Thus, incubation of cells with trehalose (100 mM), increased the viability of dehydrated cells after slow rehydration in water vapour to 30 %. Similarly, pre-incubation of cells in 1 M xylitol or glycerol enabled up to 50-60 % of cells to successfully enter a viable state of anhydrobiosis after subsequent rehydration. We presume that trehalose and sugar alcohols function mainly according to a water replacement hypothesis, as well as initiating various protective intracellular reactions. PMID:24791685

  11. The Activity of Nodules of the Supernodulating Mutant Mtsunn Is not Limited by Photosynthesis under Optimal Growth Conditions

    PubMed Central

    Cabeza, Ricardo A.; Lingner, Annika; Liese, Rebecca; Sulieman, Saad; Senbayram, Mehmet; Tränkner, Merle; Dittert, Klaus; Schulze, Joachim

    2014-01-01

    Legumes match the nodule number to the N demand of the plant. When a mutation in the regulatory mechanism deprives the plant of that ability, an excessive number of nodules are formed. These mutants show low productivity in the fields, mainly due to the high carbon burden caused through the necessity to supply numerous nodules. The objective of this study was to clarify whether through optimal conditions for growth and CO2 assimilation a higher nodule activity of a supernodulating mutant of Medicago truncatula (M. truncatula) can be induced. Several experimental approaches reveal that under the conditions of our experiments, the nitrogen fixation of the supernodulating mutant, designated as sunn (super numeric nodules), was not limited by photosynthesis. Higher specific nitrogen fixation activity could not be induced through short- or long-term increases in CO2 assimilation around shoots. Furthermore, a whole plant P depletion induced a decline in nitrogen fixation, however this decline did not occur significantly earlier in sunn plants, nor was it more intense compared to the wild-type. However, a distinctly different pattern of nitrogen fixation during the day/night cycles of the experiment indicates that the control of N2 fixing activity of the large number of nodules is an additional problem for the productivity of supernodulating mutants. PMID:24727372

  12. Accumulation of cellobiose lipids under nitrogen-limiting conditions by two ustilaginomycetous yeasts, Pseudozyma aphidis and Pseudozyma hubeiensis.

    PubMed

    Morita, Tomotake; Fukuoka, Tokuma; Imura, Tomohiro; Kitamoto, Dai

    2013-02-01

    Some basidiomycetous yeast strains extracellularly produce cellobiose lipids (CLs), glycolipid biosurfactants which have strong fungicidal activity. The representative CL producer Ustilago maydis produces CLs together with the other glycolipids, mannosylerythritol lipids (MELs); the preference of the two glycolipids is affected considerably by the nitrogen source. To develop new CL producers, 12 MEL producers were cultured under the nitrogen-limited conditions. Pseudozyma aphidis and Pseudozyma. hubeiensis were characterized as new CL producers. CL production was induced on three strains, P. aphidis, Pseudozyma graminicola, and P. hubeiensis under these conditions. The putative homologous genes of U. maydis cyp1, which encodes a P450 monooxygenase, essential for CL biosynthesis, were partially amplified from their genomic DNA. The nucleotide sequences of the gene fragments from P. hubeiensis and P. aphidis shared identities with U. maydis cyp1 of 99% and 78%, respectively. Furthermore, all of the deduced translation products are tightly clustered in the phylogenic tree of the monooxygenase. These results suggest that the genes involved with CL biosynthesis must be widely distributed in the basidiomycetous fungi as well as the MEL biosynthesis genes, and thus, the genus Pseudozyma has great potential as a biosurfactant producer. PMID:22985214

  13. On the spatial distribution of the transpiration and soil moisture of a Mediterranean heterogeneous ecosystem in water-limited conditions.

    NASA Astrophysics Data System (ADS)

    Curreli, Matteo; Corona, Roberto; Montaldo, Nicola; Albertson, John D.; Oren, Ram

    2014-05-01

    Mediterranean ecosystems are characterized by a strong heterogeneity, and often by water-limited conditions. In these conditions contrasting plant functional types (PFT, e.g. grass and woody vegetation) compete for the water use. Both the vegetation cover spatial distribution and the soil properties impact the soil moisture (SM) spatial distribution. Indeed, vegetation cover density and type affects evapotranspiration (ET), which is the main lack of the soil water balance in these ecosystems. With the objective to carefully estimate SM and ET spatial distribution in a Mediterranean water-limited ecosystem and understanding SM and ET relationships, an extended field campaign is carried out. The study was performed in a heterogeneous ecosystem in Orroli, Sardinia (Italy). The experimental site is a typical Mediterranean ecosystem where the vegetation is distributed in patches of woody vegetation (wild olives mainly) and grass. Soil depth is low and spatially varies between 10 cm and 40 cm, without any correlation with the vegetation spatial distribution. ET, land-surface fluxes and CO2 fluxes are estimated by an eddy covariance technique based micrometeorological tower. But in heterogeneous ecosystems a key assumption of the eddy covariance theory, the homogeneity of the surface, is not preserved and the ET estimate may be not correct. Hence, we estimate ET of the woody vegetation using the thermal dissipation method (i.e. sap flow technique) for comparing the two methodologies. Due the high heterogeneity of the vegetation and soil properties of the field a total of 54 sap flux sensors were installed. 14 clumps of wild olives within the eddy covariance footprint were identified as the most representative source of flux and they were instrumented with the thermal dissipation probes. Measurements of diameter at the height of sensor installation (height of 0.4 m above ground) were recorded in all the clumps. Bark thickness and sapwood depth were measured on several

  14. New measurement system for on line in core high-energy neutron flux monitoring in materials testing reactor conditions

    SciTech Connect

    Geslot, B.; Filliatre, P.; Barbot, L.; Jammes, C.; Breaud, S.; Oriol, L.; Villard, J.-F.; Lopez, A. Legrand

    2011-03-15

    Flux monitoring is of great interest for experimental studies in material testing reactors. Nowadays, only the thermal neutron flux can be monitored on line, e.g., using fission chambers or self-powered neutron detectors. In the framework of the Joint Instrumentation Laboratory between SCK-CEN and CEA, we have developed a fast neutron detector system (FNDS) capable of measuring on line the local high-energy neutron flux in fission reactor core and reflector locations. FNDS is based on fission chambers measurements in Campbelling mode. The system consists of two detectors, one detector being mainly sensitive to fast neutrons and the other one to thermal neutrons. On line data processing uses the CEA depletion code DARWIN in order to disentangle fast and thermal neutrons components, taking into account the isotopic evolution of the fissile deposit. The first results of FNDS experimental test in the BR2 reactor are presented in this paper. Several fission chambers have been irradiated up to a fluence of about 7 x 10{sup 20} n/cm{sup 2}. A good agreement (less than 10% discrepancy) was observed between FNDS fast flux estimation and reference flux measurement.

  15. In situ visualization on cores with different boundary conditions through X-ray computed tomography scanner (CT-Scanner) during spontaneous imbibition

    NASA Astrophysics Data System (ADS)

    Kim, T.; Kovscek, A. R.

    2013-12-01

    Spontaneous imbibition (SI) is defined as displacement of non-wetting phase by wetting phase through the action of capillary forces in porous media. Spontaneous imbibition may occur as countercurrent or cocurrent multiphase flow. SI is an important test of rock wettability and is relevant to oil recovery from rocks of many different types of wettability. The rate of SI depends on permeability and water/oil relative permeability, medium shapes and boundary conditions, fluid viscosity, interfacial tension, and wettability, among other factors. This study investigates the effect of characteristic length (CL), boundary conditions (BC), and initial water saturation on the rate of spontaneous imbibition. We conduct countercurrent and cocurrent SI tests using cylindrical Berea sandstone (water-wet) and Indiana limestone (weakly wetting) through an X-ray computed tomography scanner and an imbibition cell with different boundary conditions and initial water saturations. Brine (1 wt% NaCl) is used as the wetting fluid. Also, decane (n-C10) and Blandol are used as non-wetting fluids, respectively to compare the effect of mobility ratio. The observed 2-D and 3-D saturation profile histories within each rock show clearly different imbibition patterns for each boundary condition. Also, low permeability limestones have more heterogeneous features than sandstones. The effect of characteristic length (CL) on the imbibition recovery curve was investigated using dimensionless time (tD). CL had an inverse effect on the rate of spontaneous imbibition within the same core samples. In addition, we used three different boundary conditions (BC) including (1) all faces open (AFO), (2) two ends open (TEO, i.e., inlet and outlet face), and (3) one end open (OEO, i.e., one face of the core) systems. BC experiments showed the effect of total open surface area for the oil production rate of spontaneous imbibition with different Swi. In addition, the generalized correlation (Aronofsy's equation

  16. Are Opioid Antagonists Effective in Attenuating the Core Symptoms of Autism Spectrum Conditions in Children: A Systematic Review

    ERIC Educational Resources Information Center

    Roy, A.; Roy, M.; Deb, S.; Unwin, G.; Roy, A.

    2015-01-01

    Background: ASC (autism spectrum conditions) may result from a failure of striatal beta endorphins to diminish with maturation. Many symptoms of ASC resemble behaviours induced in animals or humans by opiate administration, including decreased socialisation, diminished crying, repetitive stereotypies, insensitivity to pain and motor hyperactivity.…

  17. Methods for automatized detection of rapid changes in lateral boundary condition fields for NWP limited area models

    NASA Astrophysics Data System (ADS)

    Tudor, M.

    2015-08-01

    Three-hourly temporal resolution of lateral boundary data for limited area models (LAMs) can be too infrequent to resolve rapidly moving storms. This problem is expected to be worse with increasing horizontal resolution. In order to detect intensive disturbances in surface pressure moving rapidly through the model domain, a filtered surface pressure field (MCUF) is computed operationally in the ARPEGE global model of Météo France. The field is distributed in the coupling files along with conventional meteorological fields used for lateral boundary conditions (LBCs) for the operational forecast using limited area model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) in the Meteorological and Hydrological Service of Croatia (DHMZ). Here an analysis is performed of the MCUF field for the LACE coupling domain for the period from 23 January 2006, when it became available, until 15 November 2014. The MCUF field is a good indicator of rapidly moving pressure disturbances (RMPDs). Its spatial and temporal distribution can be associated with the usual cyclone tracks and areas known to be supporting cyclogenesis. An alternative set of coupling files from the IFS operational run in the European Centre for Medium-Range Weather Forecasts (ECMWF) is also available operationally in DHMZ with 3-hourly temporal resolution, but the MCUF field is not available. Here, several methods are tested that detect RMPDs in surface pressure a posteriori from the IFS model fields provided in the coupling files. MCUF is computed by running ALADIN on the coupling files from IFS. The error function is computed using one-time-step integration of ALADIN on the coupling files without initialization, initialized with digital filter initialization (DFI) or scale-selective DFI (SSDFI). Finally, the amplitude of changes in the mean sea level pressure is computed from the fields in the coupling files. The results are compared to the MCUF field of ARPEGE and the results of same

  18. Expected years of life free of chronic condition-induced activity limitations - United States, 1999-2008.

    PubMed

    Molla, Michael T

    2013-11-22

    Over the 20th century, the U.S. population has witnessed major changes in fatal and nonfatal health outcomes. Mortality has declined, and life expectancy has increased continuously; chronic conditions have replaced acute diseases as leading causes of both illness and death. During 1900-2008, average life expectancy at birth for the total U.S. population increased from 47.3 years in 1900 to 78.1 years in 2008, a gain of 30.8 years. In addition, an increasing proportion of the U.S. population is aged >65 years. According to the U.S. Census Bureau estimates, at the beginning of the 20th century, the U.S. population aged >65 years constituted only 4.1 percent of the total population; by 2008, the percentage of the total U.S. population aged >65 years was 12.8%. However, declines in mortality are not necessarily associated with declines in morbidity or the consequences of chronic conditions on life activities. The possibility that longer life might be accompanied by poor health makes it essential to develop measures that account for both mortality and morbidity at the same time. Hence, over the past 40 years, a new set of health measures (e.g., "healthy life expectancies") have been developed that account for both mortality and life spent free of the consequences of ill health. One of these newly developed set of measures (called "active life expectancy") is the average number of years expected to be lived without activity limitations. PMID:24264496

  19. NAP (davunetide) protects primary hippocampus culture by modulating expression profile of antioxidant genes during limiting oxygen conditions.

    PubMed

    Arya, A; Meena, R; Sethy, N K; Das, M; Sharma, M; Bhargava, K

    2015-04-01

    Hypoxia is a well-known threat to neuronal cells and triggers the pathophysiological syndromes in extreme environments such as high altitudes and traumatic conditions such as stroke. Among several prophylactic molecules proven suitable for ameliorating free radical damage, NAP (an octapeptide with initial amino acids: asparagine/N, alanine/A, and proline/P) can be considered superlative, primarily due to its high permeability into brain through blood-brain barrier and observed activity at femtomolar concentrations. Several mechanisms of action of NAP have been hypothesized for its protective role during hypoxia, yet any distinct mechanism is unknown. Oxidative stress is advocated as the leading event in hypoxia; we, therefore, investigated the regulation of key antioxidant genes to understand the regulatory role of NAP in providing neuroprotection. Primary neuronal culture of rat was subjected to cellular hypoxia by limiting the oxygen concentration to 0.5% for 72 h and observing the prophylactic efficacies of 15fM NAP by conventional cell death assays using flow cytometry. We performed real-time quantitative polymerase chain reaction to comprehend the regulatory mechanism. Further, we validated the significantly regulated candidates by enzyme assays and immunoblotting. In the present study, we report that NAP regulates a major clad of cellular antioxidants and there is an involvement of more than one route of action in neuroprotection during hypoxia. PMID:25727410

  20. Conditional knockdown of BCL2A1 reveals rate-limiting roles in BCR-dependent B-cell survival.

    PubMed

    Sochalska, M; Ottina, E; Tuzlak, S; Herzog, S; Herold, M; Villunger, A

    2016-04-01

    Bcl2 family proteins control mitochondrial apoptosis and its members exert critical cell type and differentiation stage-specific functions, acting as barriers against autoimmunity or transformation. Anti-apoptotic Bcl2a1/Bfl1/A1 is frequently deregulated in different types of blood cancers in humans but its physiological role is poorly understood as quadruplication of the Bcl2a1 gene locus in mice hampers conventional gene targeting strategies. Transgenic overexpression of A1, deletion of the A1-a paralogue or constitutive knockdown in the hematopoietic compartment of mice by RNAi suggested rate-limiting roles in lymphocyte development, granulopoiesis and mast cell activation. Here we report on the consequences of conditional knockdown of A1 protein expression using a reverse transactivator (rtTA)-driven approach that highlights a critical role for this Bcl2 family member in the maintenance of mature B-cell homeostasis. Furthermore, we define the A1/Bim (Bcl-2 interacting mediator of cell death) axis as a target of key kinases mediating B-cell receptor (BCR)-dependent survival signals, such as, spleen tyrosine kinase (Syk) and Brutons tyrosine kinase (Btk). As such, A1 represents a putative target for the treatment of B-cell-related pathologies depending on hyperactivation of BCR-emanating survival signals and loss of A1 expression accounts, in part, for the pro-apoptotic effects of Syk- or Btk inhibitors that rely on the 'BH3-only' protein Bim for cell killing. PMID:26450454

  1. Role of secondary metabolites in the interaction between Pseudomonas fluorescens and soil microorganisms under iron-limited conditions.

    PubMed

    Deveau, Aurélie; Gross, Harald; Palin, Béatrice; Mehnaz, Samina; Schnepf, Max; Leblond, Pierre; Dorrestein, Pieter C; Aigle, Bertrand

    2016-08-01

    Microorganisms can be versatile in their interactions with each other, being variously beneficial, neutral or antagonistic in their effect. Although this versatility has been observed among many microorganisms and in many environments, little is known regarding the mechanisms leading to these changes in behavior. In the present work, we analyzed the mechanism by which the soil bacterium Pseudomonas fluorescens BBc6R8 shifts from stimulating the growth of the ectomycorrhizal fungus Laccaria bicolor S238N to killing the fungus. We show that among the three secondary metabolites produced by the bacterial strain-the siderophores enantio-pyochelin and pyoverdine, and the biosurfactant viscosin-the siderophores are mainly responsible for the antagonistic activity of the bacterium under iron-limited conditions. While the bacterial strain continues to produce beneficial factors, their effects are overridden by the action of their siderophores. This antagonistic activity of the strain P. fluorescens BBC6R8 in iron-depleted environments is not restricted to its influence on L. bicolor, since it was also seen to inhibit the growth of the actinomycete Streptomyces ambofaciens ATCC23877. We show that the strain P. fluorescens BBc6R8 uses different strategies to acquire iron, depending on certain biotic and abiotic factors. PMID:27199346

  2. Life from the core

    NASA Astrophysics Data System (ADS)

    Doglioni, Carlo; Coleman, Max; Pignatti, Johannes; Glassmeier, Karl-Heinz

    2010-05-01

    Life on Earth is the result of the chaotic combination of several independent chemical and physical parameters. One of them is the shield from ionizing radiation exerted by the atmosphere and the Earth's magnetic field. We hypothesise that the first few billion years of the Earth's history, dominated by bacteria, were characterized by stronger ionizing radiation. Bacteria can survive under such conditions better than any other organism. During the Archean and early Proterozoic the shield could have been weaker, allowing the development of only a limited number of species, more resistant to the external radiation. The Cambrian explosion of life could have been enhanced by the gradual growth of the solid inner core, which was not existent possibly before 1 Ga. The cooling of the Earth generated the solidification of the iron alloy in the center of the planet. As an hypothesis, before the crystallization of the core, the turbulence in the liquid core could have resulted in a lower or different magnetic field from the one we know today, being absent the relative rotation between inner and external core.

  3. ASH1 mRNP-core factors form stable complexes in absence of cargo RNA at physiological conditions.

    PubMed

    Edelmann, Franziska T; Niedner, Annika; Niessing, Dierk

    2015-01-01

    Asymmetric ASH1 mRNA transport during mitosis of budding yeast constitutes one of the best-studied examples of mRNA localization. Recently, 2 studies used in vitro motility assays to prove that motile ASH1 mRNA-transport complexes can be reconstituted entirely from recombinant factors. Both studies, however, differed in their conclusions on whether cargo RNA itself is required for particle assembly and thus activation of directional transport. Here we provide direct evidence that stable complexes do assemble in absence of RNA at physiologic conditions and even at ionic strengths above cellular levels. These results directly confirm the previous notion that the ASH1 transport machinery is not activated by the cargo RNA itself, but rather through protein-protein interactions. PMID:25826656

  4. Controlled Release of Ciprofloxacin from Core-Shell Nanofibers with Monolithic or Blended Core.

    PubMed

    Zupančič, Špela; Sinha-Ray, Sumit; Sinha-Ray, Suman; Kristl, Julijana; Yarin, Alexander L

    2016-04-01

    Sustained controlled drug release is one of the prominent contributions for more successful treatment outcomes in the case of several diseases. However, the incorporation of hydrophilic drugs into nanofibers, a promising novel delivery system, and achieving a long-term sustained release still pose a challenging task. In this work we demonstrated a robust method of avoiding burst release of drugs and achieving a sustained drug release from 2 to 4 weeks using core-shell nanofibers with poly(methyl methacrylate) (PMMA) shell and monolithic poly(vinyl alcohol) (PVA) core or a novel type of core-shell nanofibers with blended (PVA and PMMA) core loaded with ciprofloxacin hydrochloride (CIP). It is also shown that, for core-shell nanofibers with monolithic core, drug release can be manipulated by varying flow rate of the core PVA solution, whereas for core-shell nanofibers with blended core, drug release can be manipulated by varying the ratios between PMMA and PVA in the core. During coaxial electrospinning, when the solvent from the core evaporates in concert with the solvent from the shell, the interconnected pores spanning the core and the shell are formed. The release process is found to be desorption-limited and agrees with the two-stage desorption model. Ciprofloxacin-loaded nanofiber mats developed in the present work could be potentially used as local drug delivery systems for treatment of several medical conditions, including periodontal disease and skin, bone, and joint infections. PMID:26950163

  5. Acute acetaminophen ingestion does not alter core temperature or sweating during exercise in hot-humid conditions.

    PubMed

    Coombs, G B; Cramer, M N; Ravanelli, N M; Morris, N B; Jay, O

    2015-06-01

    Acute acetaminophen (ACT) ingestion has been reported to reduce thermal strain during cycling in the heat. In this study, nine active participants ingested 20 mg of ACT per kg of total body mass (ACT) or a placebo (PLA), 60 min prior to cycling at a fixed rate of metabolic heat production (ACT: 8.3 ± 0.3 W/kg; PLA: 8.5 ± 0.5 W/kg), which was equivalent to 55 ± 6% VO2max , for 60 min at 34.5 ± 0.1 °C, 52 ± 1% relative humidity. Resting rectal temperature (Tre ; ACT: 36.70 ± 0.17 °C; PLA: 36.80 ± 0.16 °C, P = 0.24), esophageal temperature (Tes ; ACT: 36.54 ± 0.22 °C; PLA: 36.61 ± 0.17 °C, P = 0.50) and mean skin temperature (Tsk ; ACT: 34.00 ± 0.14 °C; PLA: 33.96 ± 0.20 °C, P = 0.70) were all similar among conditions. At end-exercise, no differences in ΔTre (ACT: 1.12 ± 0.15 °C; PLA: 1.11 ± 0.21 °C, P = 0.92), ΔTes (ACT: 0.90 ± 0.28 °C; PLA: 0.88 ± 0.23 °C, P = 0.84), ΔTsk (ACT: 0.80 ± 0.39 °C; PLA: 0.70 ± 0.46 °C, P = 0.63), mean local sweat rate (ACT: 1.02 ± 0.15 mg/cm(2) /min; PLA: 1.02 ± 0.13 mg/cm(2) /min, P = 0.98) and whole-body sweat loss (ACT: 663 ± 83 g; PLA: 663 ± 77 g, P = 0.995) were evident. Furthermore, ratings of perceived exertion and thermal sensation and thermal comfort were not different between ACT and PLA conditions. In conclusion, ACT ingested 60 min prior to moderate intensity exercise in hot-humid conditions does not alter physiologic thermoregulatory control nor perceived strain. PMID:25943660

  6. Laser anemometer measurements and computations for transonic flow conditions in an annular cascade of high turning core turbine vanes

    NASA Technical Reports Server (NTRS)

    Goldman, Louis J.

    1993-01-01

    An advanced laser anemometer (LA) was used to measure the axial and tangential velocity components in an annular cascade of turbine stator vanes operating at transonic flow conditions. The vanes tested were based on a previous redesign of the first-stage stator in a two-stage turbine for a high-bypass-ratio engine. The vanes produced 75 deg of flow turning. Tests were conducted on a 0.771-scale model of the engine-sized stator. The advanced LA fringe system employed an extremely small 50-micron diameter probe volume. Window correction optics were used to ensure that the laser beams did not uncross in passing through the curved optical access port. Experimental LA measurements of velocity and turbulence were obtained at the mean radius upstream of, within, and downstream of the stator vane row at an exit critical velocity ratio of 1.050 at the hub. Static pressures were also measured on the vane surface. The measurements are compared, where possible, with calculations from a three-dimensional inviscid flow analysis. Comparisons were also made with the results obtained previously when these same vanes were tested at the design exit critical velocity ratio of 0.896 at the hub. The data are presented in both graphical and tabulated form so that they can be readily compared against other turbomachinery computations.

  7. MATTER MIXING IN ASPHERICAL CORE-COLLAPSE SUPERNOVAE: A SEARCH FOR POSSIBLE CONDITIONS FOR CONVEYING {sup 56}Ni INTO HIGH VELOCITY REGIONS

    SciTech Connect

    Ono, Masaomi; Nagataki, Shigehiro; Ito, Hirotaka; Lee, Shiu-Hang; Mao, Jirong; Tolstov, Alexey; Hashimoto, Masa-aki

    2013-08-20

    We perform two-dimensional axisymmetric hydrodynamic simulations of matter mixing in aspherical core-collapse supernova explosions of a 16.3 M{sub Sun} star with a compact hydrogen envelope. Observations of SN 1987A have provided evidence that {sup 56}Ni synthesized by explosive nucleosynthesis is mixed into fast moving matter ({approx}>3500 km s{sup -1}) in the exploding star. In order to clarify the key conditions for reproducing such high velocity of {sup 56}Ni, we revisit matter mixing in aspherical core-collapse supernova explosions. Explosions are initiated artificially by injecting thermal and kinetic energies around the interface between the iron core and the silicon-rich layer. Perturbations of 5% or 30% amplitude in the radial velocities are introduced at several points in time. We find that no high velocity {sup 56}Ni can be obtained if we consider bipolar explosions with perturbations (5% amplitude) of pre-supernova origins. If large perturbations (30% amplitude) are introduced or exist due to some unknown mechanism in a later phase just before the shock wave reaches the hydrogen envelope, {sup 56}Ni with a velocity of 3000 km s{sup -1} can be obtained. Aspherical explosions that are asymmetric across the equatorial plane with clumpy structures in the initial shock waves are investigated. We find that the clump sizes affect the penetration of {sup 56}Ni. Finally, we report that an aspherical explosion model that is asymmetric across the equatorial plane with multiple perturbations of pre-supernova origins can cause the penetration of {sup 56}Ni clumps into fast moving matter of 3000 km s{sup -1}. We show that both aspherical explosions with clumpy structures and perturbations of pre-supernova origins may be necessary to reproduce the observed high velocity of {sup 56}Ni. To confirm this, more robust three-dimensional simulations are required.

  8. Catabolite repression of the toluene degradation pathway in Pseudomonas putida harboring pWW0 under various conditions of nutrient limitation in chemostat culture

    SciTech Connect

    Duetz, W.A.; Wind, B.; Andel, J.G. van

    1996-02-01

    Many xenobiotic compounds are biodegradable in laboratory bacterial cultures, but results in the environment are not as reassuring. Actual biodegradation rates of aromatics under natural conditions may be very low. This study mimicked limiting conditions of oxygen phosphate and nitrogen in chemostat cultures of Pseudomonas putida and studied the inducibility of TOL plasmid pathway in response to the nonmetabolizable inducer-o-xylene.

  9. Effects of latitudinally heterogeneous buoyancy flux conditions at the inner core boundary of an MHD dynamo in a rotating spherical shell

    NASA Astrophysics Data System (ADS)

    Sasaki, Youhei; Takehiro, Shin-ichi; Nishizawa, Seiya; Hayashi, Yoshi-Yuki

    2013-10-01

    Numerical experiments on an MHD dynamo in a rotating spherical shell are performed in order to examine effects of latitudinally heterogeneous buoyancy flux conditions at the inner core boundary on the establishment of dynamo solutions. The Ekman number, the Prandtl number, and the ratio of the inner to outer radii are fixed as 10-3, 1, and 0.35, respectively. The magnetic Prandtl number is varied from 1 to 10, and the modified Rayleigh number is increased from 100 to 500. The electrically-conducting inner sphere is allowed to rotate rigidly around the rotation axis of the outer sphere at a different angular velocity. It is found that self-sustained dynamo solutions are obtained in the presence of a strong buoyancy flux around the equatorial regions or a homogeneous buoyancy flux, whereas a magnetic field does not develop spontaneously in all cases when a strong buoyancy flux is present around the polar regions. This difference in the development of the magnetic fields is considered to be affected by the different distributions of the mean zonal flow. In the case of the strong polar buoyancy flux, the direction of the mean zonal flow around the inner core is reversed due to the thermal wind balance and strong shear layer produced there. This shear may prevent the coherent growth of vortex columns and the magnetic field.

  10. 78 FR 67320 - Special Conditions: Airbus, Model A350-900 series Airplane; Pitch and Roll Limiting by Electronic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-12

    ..., 2000 (65 FR 19477- 19478), as well as at http://DocketsInfo.dot.gov/ . Docket: Background documents or...; Pitch and Roll Limiting by Electronic Flight Control System AGENCY: Federal Aviation Administration (FAA... feature(s) associated with the Electronic Flight Control System that limits pitch and roll...

  11. Development of lithium and tungsten limiters for test on T-10 tokamak at high heat load condition

    NASA Astrophysics Data System (ADS)

    Lyublinski, I. E.; Vertkov, A. V.; Zharkov, M. Yu; Vershkov, V. A.; Mirnov, S. V.

    2016-04-01

    Application of a complex of powerful (up to 3 MW) ECR plasma heating in T-10 tokamak is pulled down with a problem of the strong plasma pollution at power input more than 2 MW. For the solution of these problems the new W and Li limiters is developed and prepared to implementation. As it is supposed, application of W as a plasma facing material will allow excluding carbon influx into vacuum chamber. An additional Li limiter arranged in a shadow of W one will be used as a Li source for plasma periphery cooling due to a reradiation on Li that will lead to decrease in power deposition on W limiters. Parameters and design of limiters are presented. Plasma facing surface of a limiter is made of capillary-porous system (CPS) with Li. Porous matrix of CPS (W felt) provides stability of liquid Li surface under MHD force effect and an opportunity of its constant renewal due to capillary forces. The necessary Li flux from a Li limiter surface is estimated for maintenance of normal operation mode of W limiters at ECRH power of 3 MW during 400 ms. It is shown, that upgrade of limiters in tokamak T-10 will allow providing of ECR plasma heating with power up to 3 MW at reasonable Li flux.

  12. 76 FR 12274 - Special Conditions: Bell Helicopter Textron Canada Limited Model 206B and 206L Series Helicopters...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-07

    ... failure conditions with more severe adverse consequences than those envisioned by the existing applicable... considers necessary to ensure the failures and their effects are sufficiently analyzed and contained. DATES... possible failure conditions for this system, and their effect on the continued safe flight and landing...

  13. 78 FR 11554 - Special Conditions: Embraer S.A., Model EMB-550 Airplane, Limit Pilot Forces for Sidestick Control

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-19

    ...These special conditions for the Embraer S.A. Model EMB-550 airplane. This airplane will have a novel or unusual design feature, specifically sidestick controllers designed to be operated with only one hand. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards......

  14. Genetic Variation of Morphological Traits and Transpiration in an Apple Core Collection under Well-Watered Conditions: Towards the Identification of Morphotypes with High Water Use Efficiency

    PubMed Central

    Lopez, Gerardo; Pallas, Benoît; Martinez, Sébastien; Lauri, Pierre-Éric; Regnard, Jean-Luc; Durel, Charles-Éric; Costes, Evelyne

    2015-01-01

    Water use efficiency (WUE) is a quantitative measurement which improvement is a major issue in the context of global warming and restrictions in water availability for agriculture. In this study, we aimed at studying the variation and genetic control of WUE and the respective role of its components (plant biomass and transpiration) in a perennial fruit crop. We explored an INRA apple core collection grown in a phenotyping platform to screen one-year-old scions for their accumulated biomass, transpiration and WUE under optimal growing conditions. Plant biomass was decompose into morphological components related to either growth or organ expansion. For each trait, nine mixed models were evaluated to account for the genetic effect and spatial heterogeneity inside the platform. The Best Linear Unbiased Predictors of genetic values were estimated after model selection. Mean broad-sense heritabilities were calculated from variance estimates. Heritability values indicated that biomass (0.76) and WUE (0.73) were under genetic control. This genetic control was lower in plant transpiration with an heritability of 0.54. Across the collection, biomass accounted for 70% of the WUE variability. A Hierarchical Ascendant Classification of the core collection indicated the existence of six groups of genotypes with contrasting morphology and WUE. Differences between morphotypes were interpreted as resulting from differences in the main processes responsible for plant growth: cell division leading to the generation of new organs and cell elongation leading to organ dimension. Although further studies will be necessary on mature trees with more complex architecture and multiple sinks such as fruits, this study is a first step for improving apple plant material for the use of water. PMID:26717192

  15. Transient climate simulations of the deglaciation 21-9 thousand years before present; PMIP4 Core experiment design and boundary conditions

    NASA Astrophysics Data System (ADS)

    Ivanovic, Ruza; Gregoire, Lauren; Kageyama, Masa; Roche, Didier; Valdes, Paul; Burke, Andrea; Drummond, Rosemarie; Peltier, W. Richard; Tarasov, Lev

    2016-04-01

    The last deglaciation, which marked the transition between the last glacial and present interglacial periods, was punctuated by a series of rapid (centennial and decadal) climate changes. Numerical climate models are useful for investigating mechanisms that underpin the events, especially now that some of the complex models can be run for multiple millennia. We have set up a Paleoclimate Modelling Intercomparison Project (PMIP) working group to coordinate efforts to run transient simulations of the last deglaciation, and to facilitate the dissemination of expertise between modellers and those engaged with reconstructing the climate of the last 21 thousand years. Here, we present the design of a coordinated Core simulation over the period 21-9 thousand years before present (ka) with time varying orbital forcing, greenhouse gases, ice sheets, and other geographical changes. A choice of two ice sheet reconstructions is given. Additional focussed simulations will also be coordinated on an ad-hoc basis by the working group, for example to investigate the effect of ice sheet and iceberg meltwater, and the uncertainty in other forcings. Some of these focussed simulations will concentrate on shorter durations around specific events to allow the more computationally expensive models to take part. Ivanovic, R. F., Gregoire, L. J., Kageyama, M., Roche, D. M., Valdes, P. J., Burke, A., Drummond, R., Peltier, W. R., and Tarasov, L.: Transient climate simulations of the deglaciation 21-9 thousand years before present; PMIP4 Core experiment design and boundary conditions, Geosci. Model Dev. Discuss., 8, 9045-9102, doi:10.5194/gmdd-8-9045-2015, 2015.

  16. AMPA/Kainate, NMDA, and Dopamine D1 Receptor Function in the Nucleus Accumbens Core: A Context-Limited Role in the Encoding and Consolidation of Instrumental Memory

    ERIC Educational Resources Information Center

    Hernandez, Pepe J.; Andrzejewski, Matthew E.; Sadeghian, Kenneth; Panksepp, Jules B.; Kelley, Ann E.

    2005-01-01

    Neural integration of glutamate- and dopamine-coded signals within the nucleus accumbens (NAc) is a fundamental process governing cellular plasticity underlying reward-related learning. Intra-NAc core blockade of NMDA or D1 receptors in rats impairs instrumental learning (lever-pressing for sugar pellets), but it is not known during which phase of…

  17. Understanding of polyhydroxybutyrate production under carbon and phosphorus-limited growth conditions in non-axenic continuous culture.

    PubMed

    Cavaillé, Laëtitia; Albuquerque, Maria; Grousseau, Estelle; Lepeuple, Anne-Sophie; Uribelarrea, Jean-Louis; Hernandez-Raquet, Guillermina; Paul, Etienne

    2016-02-01

    In a waste into resource strategy, a selection of polyhydroxybutyrate (PHB)-accumulating organisms from activated sludge was achieved in an open continuous culture under acetic acid and phosphorus limitation. Once the microbial population was selected at a dilution rate (D), an increase in phosphorus limitation degree was applied in order to study the intracellular phosphorus plasticity of selected bacteria and the resulting capacity to produce PHB. Whatever D, all selected populations were able to produce PHB. At a D, the phosphorus availability determined the phosphorus-cell content which in turn fixed the amount of cell. All the remaining carbon was thus directed toward PHB. By decreasing D, microorganisms adapted more easily to higher phosphorus limitation leading to higher PHB content. A one-stage continuous reactor operated at D=0.023h(-)(1) gave reliable high PHB productivity with PHB content up to 80%. A two-stage reactor could ensure better productivity while allowing tuning product quality. PMID:26638135

  18. Using Multiple Approaches, including δ18O Signatures of Phosphate to Investigate Potential Phosphorus Limitation and Cycling under Changing Climate Conditions

    NASA Astrophysics Data System (ADS)

    Roberts, K.; Paytan, A.; Field, C. B.; Honn, E.; Edwards, E.; Gottlieb, R.

    2012-12-01

    Phosphorus (P) is often a limiting or co-limiting nutrient in terrestrial systems. It has been proposed that it will play an even greater role in ecosystems experiencing some of the many predicted effects of climate change, in particular release from nitrogen limitation. Recent work in 2007 by Menge et al. suggests that this is indeed a possibility. To investigate the potential for P limitation, and P cycling under multiple controlled conditions we collected samples from the Jasper Ridge Global Change Experiment (JRGCE) in May 2011. For over a decade the JRGCE has been manipulating four key parameters predicted to change in the future in a native Californian grassland system. Elevated Nitrogen deposition, increased precipitation, increased pCO2, and increased temperature are applied and monitored in a split plot design at the Jasper Ridge Biological Preserve in the eastern foothills of the Santa Cruz Mountains, California. Work done previously at the site using a suite of indicators of the potential P limitation suggest P limitation in some of the manipulated plots in the JRGCE. In this study we replicate a subset of the prior analyses to compare inter-annual signals of P limitation, and further attempt to utilize the oxygen isotopes of phosphate to investigate P cycling in soils at JRGCE. A fractional soil extraction process for phosphate enables separation of several operationally defined P pools, and provides auxiliary information regarding the relative concentrations of bio-available P, and relevant minerals in this grassland system under the varied conditions.

  19. 7 CFR 301.76-7 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... CFR part 305 of this chapter. (2) The nursery stock is inspected by an inspector in accordance with... limited permits for regulated articles moved interstate from areas quarantined for citrus greening. 301.76... PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE DOMESTIC QUARANTINE NOTICES Citrus...

  20. 7 CFR 301.76-6 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 3 in accordance with 7 CFR part 305 of this chapter. 3 EPA and State and local environmental... irradiation in accordance with 7 CFR part 305 of this chapter at an irradiation facility that is not located... accordance with 7 CFR part 305 of this chapter. (3) A copy of the limited permit is attached to the...

  1. 7 CFR 301.76-6 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... in accordance with 7 CFR part 305 of this chapter. (2) The article is shipped in a container that has... irradiation in accordance with 7 CFR part 305 of this chapter at an irradiation facility that is not located... accordance with 7 CFR part 305 of this chapter. (3) A copy of the limited permit is attached to the...

  2. 7 CFR 301.76-6 - Additional conditions for issuance of certificates and limited permits for regulated articles...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... with methyl bromide in accordance with 7 CFR part 305 of this chapter. (2) The article is shipped in a... treated with irradiation in accordance with 7 CFR part 305 of this chapter at an irradiation facility that... were treated in accordance with 7 CFR part 305 of this chapter. (3) A copy of the limited permit...

  3. No evidence of carbon limitation with tree age and height in Nothofagus pumilio under Mediterranean and temperate climate conditions

    PubMed Central

    Piper, Frida I.; Fajardo, Alex

    2011-01-01

    Background and Aims Trees universally decrease their growth with age. Most explanations for this trend so far support the hypothesis that carbon (C) gain becomes limited with age; though very few studies have directly assessed the relative reductions of C gain and C demand with tree age. It has also been suggested that drought enhances the effect of C gain limitation in trees. Here tests were carried out to determine whether C gain limitation is causing the growth decay with tree age, and whether drought accentuates its effect. Methods The balance between C gain and C demand across tree age and height ranges was estimated. For this, the concentration of non-structural carbohydrates (NSCs) in stems and roots of trees of different ages and heights was measured in the deciduous temperate species Nothofagus pumilio. An ontogenetic decrease in NSCs indicates support for C limitation. Furthermore, the importance of drought in altering the C balance with ontogeny was assessed by sampling the same species in Mediterranean and humid climate locations in the southern Andes of Chile. Wood density (WD) and stable carbon isotope ratios (δ13C) were also determined to examine drought constraints on C gain. Key Results At both locations, it was effectively found that tree growth ultimately decreased with tree age and height. It was found, however, that NSC concentrations did not decrease with tree age or height when WD was considered, suggesting that C limitation is not the ultimate mechanism causing the age/height-related declining tree growth. δ13C decreased with tree age/height at the Mediterranean site only; drought effect increased with tree age/height, but this pattern was not mirrored by the levels of NSCs. Conclusions The results indicate that concentrations of C storage in N. pumilio trees do not decrease with tree age or height, and that reduced C assimilation due to summer drought does not alter this pattern. PMID:21852277

  4. 30 CFR 203.42 - What conditions and limitations apply to royalty relief for deep wells and phase 1 ultra-deep wells?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 2 2013-07-01 2013-07-01 false What conditions and limitations apply to royalty relief for deep wells and phase 1 ultra-deep wells? 203.42 Section 203.42 Mineral Resources BUREAU OF SAFETY AND ENVIRONMENTAL ENFORCEMENT, DEPARTMENT OF THE INTERIOR MINERALS REVENUE MANAGEMENT RELIEF OR REDUCTION IN ROYALTY RATES OCS Oil,...

  5. The Importance of Awareness and Communication for the Inclusion of Young People with Life-Limiting and Life-Threatening Conditions in Mainstream Schools and Colleges

    ERIC Educational Resources Information Center

    Asprey, Anthea; Nash, Tricia

    2006-01-01

    Anthea Asprey and Tricia Nash both belong to the Children's Hospice South West Research Group, based at the University of Exeter. In this article, they report one aspect of a research project designed to determine the adequacy of support for young people with life-limiting and life-threatening conditions in the education system. They describe here…

  6. GENERAL: Bifurcation of a Saddle-Node Limit Cycle with Homoclinic Orbits Satisfying the Small Lobe Condition in a Leech Neuron Model

    NASA Astrophysics Data System (ADS)

    Yooer, Chi-Feng; Xu, Jian-Xue; Zhang, Xin-Hua

    2009-08-01

    Mechanism of period-adding cascades with chaos in a reduced leech neuron model is suggested as the bifurcation of a saddle-node limit cycle with homoclinic orbits satisfying the “small lobe condition", instead of the blue-sky catastrophe. In every spiking adding, the new spike emerges at the end of the spiking phase of the bursters.

  7. The optimum conditions for synthesis of Fe3O4/ZnO core/shell magnetic nanoparticles for photodegradation of phenol

    PubMed Central

    2014-01-01

    The photocatalysis of phenol was studied using Fe3O4/ZnO core/shell magnetic nanoparticles (MNPs). The photocatalysts were synthesized by coating of ZnO onto the magnetite by precipitation method and characterized by XRD, SEM and FTIR measurements. Using the Taguchi method, this study analyzes the effect of parameters such as calcinations time, calcinations temperature and molar ratio of Fe3O4:ZnO on the photo activity of Fe3O4/ZnO MNPs. XRD and FTIR analysis confirm that coating process was done successfully. SEM images show that the average particle size of synthesized Fe3O4/ZnO nanoparticles was about 50 nm. The phenol removal efficiency of 88% can be achieved by using a photocatalyst which is synthesized through the optimum conditions: calcinations temperature of 550°C, calcinations time of 2 hours and molar ratio of 1:10 for Fe3O4:ZnO. PMID:24406040

  8. Differential Effects of Accumbens Core vs. Shell Lesions in a Rat Concurrent Conditioned Place Preference Paradigm for Cocaine vs. Social Interaction

    PubMed Central

    Fritz, Michael; Rawas, Rana El; Klement, Sabine; Kummer, Kai; Mayr, Michael J.; Eggart, Vincent; Salti, Ahmad; Bardo, Michael T.; Saria, Alois; Zernig, Gerald

    2011-01-01

    Background A main challenge in the therapy of drug dependent individuals is to help them reactivate interest in non-drug-associated activities. Among these activities, social interaction is doubly important because treatment adherence itself depends on it. We previously developed a rat experimental model based on the conditioned place preference (CPP) paradigm in which only four 15-min episodes of social interaction with a gender- and weight-matched male conspecific (i) reversed CPP from cocaine to social interaction despite continuing cocaine training and (ii) prevented the reinstatement of cocaine CPP. In the present study, we investigated if the two subregions of the nucleus accumbens (Acb), i.e., the core (AcbC) and the shell (AcbSh), would differentially affect CPP for cocaine vs social interaction. Methodology/Principal Findings Animals were concurrently trained for CPP pairing cocaine with one compartment and social interaction with the other (i.e., mutually exclusive stimulus presentation during training). Excitotoxic lesioning of the AcbC or the BLA shifted CPP toward social interaction, whereas AcbSh inactivation shifted CPP toward cocaine. Conclusions Overall, our findings suggest that inactivation of the AcbC or the BLA is sufficient to shift CPP away from a drug of abuse toward social interaction. Lesioning the AcbSh produced the opposite effect. PMID:22046347

  9. Evaluation of tensile retention of Y-TZP crowns after long-term aging: effect of the core substrate and crown surface conditioning.

    PubMed

    Amaral, R; Rippe, M; Oliveira, B G; Cesar, P F; Bottino, M A; Valandro, L F

    2014-01-01

    This study evaluated the effect of the core substrate type (dentin and composite resin) on the retention of crowns made of yttrium oxide stabilized tetragonal zirconia polycrystal (Y-TZP), submitted to three inner surface conditionings. For this purpose, 72 freshly extracted molars were embedded in acrylic resin, perpendicular to the long axis, and prepared for full crowns: 36 specimens had crown preparations in dentin; the remaining 36 teeth had the crowns removed, and crown preparations were reconstructed with composite resin plus fiber posts with dimensions identical to the prepared dentin. The preparations were impressed using addition silicone, and 72 Y-TZP copings for the tensile test were produced. Cementation was performed with a dual-cured cement containing phosphate monomers. For cementation, the crown preparation (dentin or resin) was conditioned with the adhesive system, and the ceramic was subjected to one of three surface treatments: isopropyl alcohol, tribochemical silica coating, or thin low-fusing glassy porcelain layer application plus silanization. After 24 hours, all specimens were submitted to thermocycling (6000 cycles) and placed in a special tensile testing device in a universal testing machine to determine failure loads. The failure modes of all samples were analyzed under a stereomicroscope. Two-way analysis of variance showed that the surface treatment and substrate type (α=0.05) affected the tensile retention results. The dentin substrate presented the highest tensile retention values, regardless of the surface treatment. When the substrate was resin, the tribochemical silica coating and low-fusing glaze application plus silanization groups showed the higher retention values. PMID:24809542

  10. Approaches to managing uncertainty in people with life-limiting conditions: role of communication and palliative care.

    PubMed

    Etkind, S N; Koffman, J

    2016-07-01

    Patients with any major illness can expect to experience uncertainty about the nature of their illness, its treatment and their prognosis. Prognostic uncertainty is a particular source of patient distress among those living with life-limiting disease. Uncertainty also affects professionals and it has been argued that the level of professional tolerance of uncertainty can affect levels of investigation as well as healthcare resource use. We know that the way in which uncertainty is recognised, managed and communicated can have important impacts on patients' treatment and quality of life. Current approaches to uncertainty in life-limiting illness include the use of care bundles and approaches that focus on communication and education. The experience in communicating in difficult situations that specialist palliative care professionals can provide may also be of benefit for patients with life-limiting illness in the context of uncertainty. While there are a number of promising approaches to uncertainty, as yet few interventions targeted at recognising and addressing uncertainty have been fully evaluated and further research is needed in this area. PMID:27129911

  11. 26 CFR 20.2056(b)-3 - Marital deduction; interest of spouse conditioned on survival for limited period.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DECEDENTS DYING AFTER AUGUST 16, 1954 Taxable Estate § 20.2056(b)-3 Marital deduction; interest of spouse... decedent to his surviving spouse subject to the condition that she does not die as a result of a common... passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact...

  12. 26 CFR 20.2056(b)-3 - Marital deduction; interest of spouse conditioned on survival for limited period.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... DECEDENTS DYING AFTER AUGUST 16, 1954 Taxable Estate § 20.2056(b)-3 Marital deduction; interest of spouse... decedent to his surviving spouse subject to the condition that she does not die as a result of a common... passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact...

  13. 26 CFR 20.2056(b)-3 - Marital deduction; interest of spouse conditioned on survival for limited period.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DECEDENTS DYING AFTER AUGUST 16, 1954 Taxable Estate § 20.2056(b)-3 Marital deduction; interest of spouse... decedent to his surviving spouse subject to the condition that she does not die as a result of a common... passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact...

  14. 26 CFR 20.2056(b)-3 - Marital deduction; interest of spouse conditioned on survival for limited period.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... DECEDENTS DYING AFTER AUGUST 16, 1954 Taxable Estate § 20.2056(b)-3 Marital deduction; interest of spouse... decedent to his surviving spouse subject to the condition that she does not die as a result of a common... passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact...

  15. 26 CFR 20.2056(b)-3 - Marital deduction; interest of spouse conditioned on survival for limited period.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... DECEDENTS DYING AFTER AUGUST 16, 1954 Taxable Estate § 20.2056(b)-3 Marital deduction; interest of spouse... decedent to his surviving spouse subject to the condition that she does not die as a result of a common... passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact...

  16. Passive fault current limiting device

    DOEpatents

    Evans, D.J.; Cha, Y.S.

    1999-04-06

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment. 6 figs.

  17. Passive fault current limiting device

    DOEpatents

    Evans, Daniel J.; Cha, Yung S.

    1999-01-01

    A passive current limiting device and isolator is particularly adapted for use at high power levels for limiting excessive currents in a circuit in a fault condition such as an electrical short. The current limiting device comprises a magnetic core wound with two magnetically opposed, parallel connected coils of copper, a high temperature superconductor or other electrically conducting material, and a fault element connected in series with one of the coils. Under normal operating conditions, the magnetic flux density produced by the two coils cancel each other. Under a fault condition, the fault element is triggered to cause an imbalance in the magnetic flux density between the two coils which results in an increase in the impedance in the coils. While the fault element may be a separate current limiter, switch, fuse, bimetal strip or the like, it preferably is a superconductor current limiter conducting one-half of the current load compared to the same limiter wired to carry the total current of the circuit. The major voltage during a fault condition is in the coils wound on the common core in a preferred embodiment.

  18. The sulfur depletion problem: upper limits on the H2S2, HS·2, and S2 gas-phase abundances toward the low-mass warm core IRAS 16293-2422

    NASA Astrophysics Data System (ADS)

    Martín-Doménech, R.; Jiménez-Serra, I.; Muñoz Caro, G. M.; Müller, H. S. P.; Occhiogrosso, A.; Testi, L.; Woods, P. M.; Viti, S.

    2016-01-01

    Context. A fraction of the missing sulfur in dense clouds and circumstellar regions could be in the form of three species not yet detected in the interstellar medium: H2S2, HS.2, and S2 according to experimental simulations performed under astrophysically relevant conditions. These S-S bonded molecules can be formed by the energetic processing of H2S-bearing ice mantles on dust grains, and subsequently desorb to the gas phase. Aims: The detection of these species could partially solve the sulfur depletion problem, and would help to improve our knowledge of the poorly known chemistry of sulfur in the interstellar medium. To this purpose we calculated the frequencies and expected intensities of the rotational transitions not previously reported, and performed dedicated ground-based observations toward the low-mass warm core IRAS 16293-2422, a region with one of the highest measured gas-phase H2S abundances. Methods: Observations in the submillimeter regime were obtained with the APEX 12 m telescope during 15 h of observation. A total of ~16 GHz were covered in a range of about 100 GHz, targeting a wide selection of the predicted rotational transitions of the three molecules. Results: The 1σ noise rms values were extracted in the spectral regions where the targeted species should have been detected. These values were a factor of 2-7 lower than those reached by previous observations toward the same source, and allowed us to estimate a 1σ upper limit to their molecular abundances of ≤8.1 × 10-9, ≤ 1.1 × 10-8, and ≤ 2.9 × 10-7 relative to H2, for H2S 2 , HS.2, and S2, respectively. Conclusions: The upper limit abundances of the three molecules containing the S2 unit are up to two orders of magnitude lower than the H2S abundance in the source, and one order of magnitude lower than the expected abundances from the experimental simulations using ice analogs. Subsequent gas-phase chemistry after desorption could lower the abundances of the three species to

  19. Limitations on silicon in the outer core: Ultrasonic measurements at high temperatures and high dK/dP values of Fe-Ni-Si liquids at high pressures

    NASA Astrophysics Data System (ADS)

    Williams, Quentin; Manghnani, Murli H.; Secco, Richard A.; Fu, Shunsheng

    2015-10-01

    The sound velocities of four iron-nickel-silicon liquids (Fe-5 wt %Ni-6 wt %Si, Fe-5 wt %Ni-10 wt %Si, Fe-5 wt %Ni-14 wt %Si, and Fe-5 wt %Ni-20 wt %Si) are measured between 1460 and 1925 K at ambient pressures using ultrasonic interferometry. The results constrain both the dependence on Si content of the bulk modulus of these liquids and the temperature dependence of their elasticity. These elastic data are utilized to assess both relatively low pressure (to 12 GPa) compressional data on Fe-Si liquids and to extrapolate to higher-pressure and higher-temperature conditions. If a single equation of state for Fe-Ni-Si liquids of a given composition applies from low pressure to near core conditions, then our results imply that the isothermal pressure derivative of the bulk modulus of these liquids is high: likely 8 and above at high temperatures. This high value of the pressure derivative of the bulk modulus at low pressures in Fe-Si liquids causes marked stiffening at higher pressures, leading to notable incompressibility and apparent low values of the pressure derivative of the bulk modulus at core conditions. These results reinforce the conclusion that silicon is not a major alloying component of Earth's core.

  20. Impact of B{sub 4}C on the stratification of molten steel and BWR-type core material under IVR conditions

    SciTech Connect

    Fischer, M.; Sulatsky, A. A.; Krushinov, E. V.

    2012-07-01

    As part of the validation of the In-Vessel Melt Retention (IVR) strategy for its KERENA BWR, AREVA NP has performed a quantitative assessment of the potential impact of thermochemical phenomena. This was motivated by the fact that several of these phenomena, namely the formation of a dense metallic phase, have the potential to lead to a strong increase in local heat fluxes, with the risk of early IVR failure. In this context, experiments performed in the MASCA project with PWR-type corium melts were repeated using a typical BWR core melt: characterized by a lower U/Zr-ratio and higher contents of Zr, steel, and boron carbide (B{sub 4}C). Applying an improved 'cold crucible' induction heating technique, two series of test were performed, first without B{sub 4}C and then with a B{sub 4}C content of about 1.4 wt%. These two values bound the uncertainty with respect to the incorporation of B{sub 4}C into the molten pool. The target of the tests was to localize the point of equal densities between the dense metallic phase (Fe, U, Zr and O) and the residual oxidic phase in thermo-chemical equilibrium. An interesting result of these experiments was that, different from earlier MASCA tests with PWR-type corium that showed an only insignificant impact of B{sub 4}C on metal density, the new experiments reveal a strong corresponding effect, which can over-compensates the density increase caused by U-migration into the metallic melt. This deviating result is attributed, first, to the higher Zr-fraction in the BWR-type core melt, and second, to the higher content of B{sub 4}C in the BWR-type melt in comparison to the MASCA tests (B{sub 4}C-content <0.5 wt%). Based on the obtained results it is predicted that - under certain conditions -B{sub 4}C can completely prevent the formation of a dense metallic phase, independent of the amount of molten steel in the melt. The paper gives an overview of the performed experiments and their main results and provides theoretical models to

  1. A Method for Rapid Determination of the Icing Limit of a Body in Terms of the Stream Conditions

    NASA Technical Reports Server (NTRS)

    Callaghan, Edmund E.; Serafini, John S.

    1953-01-01

    The effects of existing frictional heating were analyzed to determine the conditions under which ice formations on aircraft surfaces can be prevented. A method is presented for rapidly determining by means of charts the combination of-Mach number, altitude, and stream temperature which will maintain an ice-free surface in an icing cloud. The method can be applied to both subsonic and supersonic flow. The charts presented are for Mach numbers up to 1.8 and pressure altitudes from sea level to 45,000 feet.

  2. The EPQ model under conditions of two levels of trade credit and limited storage capacity in supply chain management

    NASA Astrophysics Data System (ADS)

    Chung, Kun-Jen

    2013-09-01

    An inventory problem involves a lot of factors influencing inventory decisions. To understand it, the traditional economic production quantity (EPQ) model plays rather important role for inventory analysis. Although the traditional EPQ models are still widely used in industry, practitioners frequently question validities of assumptions of these models such that their use encounters challenges and difficulties. So, this article tries to present a new inventory model by considering two levels of trade credit, finite replenishment rate and limited storage capacity together to relax the basic assumptions of the traditional EPQ model to improve the environment of the use of it. Keeping in mind cost-minimisation strategy, four easy-to-use theorems are developed to characterise the optimal solution. Finally, the sensitivity analyses are executed to investigate the effects of the various parameters on ordering policies and the annual total relevant costs of the inventory system.

  3. Differential regulation of two types of monogalactosyldiacylglycerol synthase in membrane lipid remodeling under phosphate-limited conditions in sesame plants

    PubMed Central

    Shimojima, Mie; Watanabe, Takahide; Madoka, Yuka; Koizumi, Ryota; Yamamoto, Masayuki P.; Masuda, Kyojiro; Yamada, Kyoji; Masuda, Shinji; Ohta, Hiroyuki

    2013-01-01

    Phosphate (Pi) limitation causes drastic lipid remodeling in plant membranes. Glycolipids substitute for the phospholipids that are degraded, thereby supplying Pi needed for essential biological processes. Two major types of remodeling of membrane lipids occur in higher plants: whereas one involves an increase in the concentration of sulfoquinovosyldiacylglycerol in plastids to compensate for a decreased concentration of phosphatidylglycerol, the other involves digalactosyldiacylglycerol (DGDG) synthesis in plastids and the export of DGDG to extraplastidial membranes to compensate for reduced abundances of phospholipids. Lipid remodeling depends on an adequate supply of monogalactosyldiacylglycerol (MGDG), which is a substrate that supports the elevated rate of DGDG synthesis that is induced by low Pi availability. Regulation of MGDG synthesis has been analyzed most extensively using the model plant Arabidopsis thaliana, although orthologous genes that encode putative MGDG synthases exist in photosynthetic organisms from bacteria to higher plants. We recently hypothesized that two types of MGDG synthase diverged after the appearance of seed plants. This divergence might have both enabled plants to adapt to a wide range of Pi availability in soils and contributed to the diversity of seed plants. In the work presented here, we found that membrane lipid remodeling also takes place in sesame, which is one of the most common traditional crops grown in Asia. We identified two types of MGDG synthase from sesame (encoded by SeMGD1 and SeMGD2) and analyzed their enzymatic properties. Our results show that both genes correspond to the Arabidopsis type-A and -B isoforms of MGDG synthase. Notably, whereas Pi limitation up-regulates only the gene encoding the type-B isoform of Arabidopsis, low Pi availability up-regulates the expression of both SeMGD1 and SeMGD2. We discuss the significance of the different responses to low Pi availability in sesame and Arabidopsis. PMID

  4. Effect of core body temperature, time of day, and climate conditions on behavioral patterns of lactating dairy cows experiencing mild to moderate heat stress.

    PubMed

    Allen, J D; Hall, L W; Collier, R J; Smith, J F

    2015-01-01

    Cattle show several responses to heat load, including spending more time standing. Little is known about what benefit this may provide for the animals. Data from 3 separate cooling management trials were analyzed to investigate the relationship between behavioral patterns in lactating dairy cows experiencing mild to moderate heat stress and their body temperature. Cows (n=157) were each fitted with a leg data logger that measured position and an intravaginal data logger that measures core body temperature (CBT). Ambient conditions were also collected. All data were standardized to 5-min intervals, and information was divided into several categories: when standing and lying bouts were initiated and the continuance of each bout (7,963 lying and 6,276 standing bouts). In one location, cows were continuously subjected to heat-stress levels according to temperature-humidity index (THI) range (THI≥72). The THI range for the other 2 locations was below and above a heat-stress threshold of 72 THI. Overall and regardless of period of day, cows stood up at greater CBT compared with continuing to stand or switching to a lying position. In contrast, cows lay down at lower CBT compared with continuing to lie or switching to a standing position, and lying bouts lasted longer when cows had lower CBT. Standing bouts also lasted longer when cattle had greater CBT, and they were less likely to lie down (less than 50% of lying bouts initiated) when their body temperature was over 38.8°C. Also, cow standing behavior was affected once THI reached 68. Increasing CBT decreased lying duration and increased standing duration. A CBT of 38.93°C marked a 50% likelihood a cow would be standing. This is the first physiological evidence that standing may help cool cows and provides insight into a communally observed behavioral response to heat. PMID:25468707

  5. AN Core Analysis

    NASA Astrophysics Data System (ADS)

    Barbarino, Andrea; Tomatis, Daniele

    2014-06-01

    Several alternative approximations of neutron transport have been proposed in years to move around the known limitations imposed by neutron diffusion in the modeling of nuclear cores. However, only a few complied with the industrial requirements of fast numerical computation, concentrating more on physical accuracy. In this work, the AN transport methodology is discussed with particular interest in core performance calculations. The implementation of the methodology in full core codes is discussed with particular attention to numerical issues and to the integration within the entire simulation process. Finally, first results from core studies in AN transport are analyzed in detail and compared to standard results of neutron diffusion.

  6. Tectonic drift versus climatic variations: rhodoliths as indicators of limits between tropical and nontropical sedimentary conditions: examples from Pacific Miocene

    SciTech Connect

    Bourrouilh-le Jan, F.G.

    1986-05-01

    Modern examples show that rhodoliths or red algal nodules are forming around the 18/sup 0/C winter isocline and that huge amounts of these red coralline algae are living and accumulating in the subtidal zones, from -60 m to sea level, of temperate seas, such as the English Channel and Rockall. In the Pacific Ocean, several high carbonate platforms, so-called uplifted atolls, show uniform, extended, and thick accumulation of rhodoliths. These accumulations have been recognized in the Solomon Islands (Rennell) and in the Loyalty Islands (Mare and Lifu, New Caledonia), but also in the Vanuatu (Vila), in the Austral Archipelago (Rurutu), where their age can be proved or estimated as middle Miocene. They are also mentioned in the literature on the Emperor Rise (northwest Pacific). On other high carbonate islands, such as Makatea (Tuamotu), red algae and rhodolith formations appear at the top of a sedimentary pile of lower Miocene coral accumulation. The same observations and perhaps the same age can be said for Nauru (central Pacific). Such a wide distribution, from the east to the west part of the Pacific Ocean and between the tropics, seems to be due to climate variations during the Miocene, more than tectonic drift due to oceanic spreading. Temperate conditions shown by this shallow platform sedimentation, just under the coral growth conditions, seem to be confirmed by isotopic studies on pelagic and benthic Foraminifera and could confirm the existence of climate variations affecting the surface water of the Pacific in an extensive area that does not consider the presence of trenches, arcs, and ridges.

  7. A one-pot protocol for synthesis of non-noble metal-based core-shell nanoparticles under ambient conditions: toward highly active and cost-effective catalysts for hydrolytic dehydrogenation of NH3BH3.

    PubMed

    Jiang, Hai-Long; Akita, Tomoki; Xu, Qiang

    2011-10-21

    A one-pot synthesis of non-noble transition metal-based core-shell nanoparticles (NPs) has been developed under ambient conditions. The obtained Cu@M (M = Co, Fe, Ni) NPs exhibit superior catalytic activity for hydrolytic dehydrogenation of NH(3)BH(3), compared to the alloy and monometallic counterparts. PMID:21909589

  8. An analytical model for relating global terrestrial carbon assimilation with climate and surface conditions using a rate limitation framework

    NASA Astrophysics Data System (ADS)

    Yang, Yuting; Donohue, Randall J.; McVicar, Tim R.; Roderick, Michael L.

    2015-11-01

    We develop an analytical model for estimating mean annual terrestrial gross primary productivity (GPP) based on a rate limitation framework. Actual GPP (climatological mean from 1982 to 2010) is calculated as a function of the balance between two GPP potentials defined by the climate (i.e., precipitation and solar radiation) and a third parameter that encodes other environmental variables and modifies the GPP-climate relationship. The model was tested using observed GPP from 94 flux sites and modeled GPP (using the model tree ensemble approach) at 48,654 (0.5°) grid cells globally. Results show that the model could account for the spatial GPP patterns, with a root-mean-square error of 0.70 and 0.65 g C m-2 d-1 and R2 of 0.79 and 0.92 for the flux site and grid cell scales, respectively. This analytical GPP model shares a similar form with the Budyko hydroclimatological model, which opens the possibility of a general analytical framework to analyze the linked carbon-water-energy cycles.

  9. Ice Core Investigations

    ERIC Educational Resources Information Center

    Krim, Jessica; Brody, Michael

    2008-01-01

    What can glaciers tell us about volcanoes and atmospheric conditions? How does this information relate to our understanding of climate change? Ice Core Investigations is an original and innovative activity that explores these types of questions. It brings together popular science issues such as research, climate change, ice core drilling, and air…

  10. Final Rules for Grandfathered Plans, Preexisting Condition Exclusions, Lifetime and Annual Limits, Rescissions, Dependent Coverage, Appeals, and Patient Protections Under the Affordable Care Act. Final rules.

    PubMed

    2015-11-18

    This document contains final regulations regarding grandfathered health plans, preexisting condition exclusions, lifetime and annual dollar limits on benefits, rescissions, coverage of dependent children to age 26, internal claims and appeal and external review processes, and patient protections under the Affordable Care Act. It finalizes changes to the proposed and interim final rules based on comments and incorporates subregulatory guidance issued since publication of the proposed and interim final rules. PMID:26595941

  11. A Core Curriculum & Training Program To Prepare Paraeducators To Work with Learners Who Have Limited English Proficiency. Case 10-98.

    ERIC Educational Resources Information Center

    Pickett, Anna Lou; Safarik, Lynn; Echevarria, Jana

    These instructional materials are designed to improve the performance of paraeducators working in inclusive classrooms servicing school age students with limited English proficiency. The competency-based program helps participants to learn skills they can apply immediately, to accept new practices, and to increase their understanding of education…

  12. Nitrogen availability impacts oilseed rape (Brassica napus L.) plant water status and proline production efficiency under water-limited conditions.

    PubMed

    Albert, Benjamin; Le Cahérec, Françoise; Niogret, Marie-Françoise; Faes, Pascal; Avice, Jean-Christophe; Leport, Laurent; Bouchereau, Alain

    2012-08-01

    Large amounts of nitrogen (N) fertilizers are used in the production of oilseed rape. However, as low-input methods of crop management are introduced crops will need to withstand temporary N deficiency. In temperate areas, oilseed rape will also be affected by frequent drought periods. Here we evaluated the physiological and metabolic impact of nitrate limitation on the oilseed rape response to water deprivation. Different amounts of N fertilizer were applied to plants at the vegetative stage, which were then deprived of water and rehydrated. Both water and N depletion accelerated leaf senescence and reduced leaf development. N-deprived plants exhibited less pronounced symptoms of wilting during drought, probably because leaves were smaller and stomata were partially closed. Efficiency of proline production, a major stress-induced diversion of nitrogen metabolism, was assessed at different positions along the whole plant axis and related to leaf developmental stage and water status indices. Proline accumulation, preferentially in younger leaves, accounted for 25-85% of the free amino acid pool. This was mainly due to a better capacity for proline synthesis in fully N-supplied plants whether they were subjected to drought or not, as deduced from the expression patterns of the proline metabolism BnP5CS and BnPDH genes. Although less proline accumulated in the oldest leaves, a significant amount was transported from senescing to emerging leaves. Moreover, during rehydration proline was readily recycled. Our results therefore suggest that proline plays a significant role in leaf N remobilization and in N use efficiency in oilseed rape. PMID:22526495

  13. Analysis of Influenza Virus Hemagglutinin Receptor Binding Mutants with Limited Receptor Recognition Properties and Conditional Replication Characteristics▿

    PubMed Central

    Bradley, Konrad C.; Galloway, Summer E.; Lasanajak, Yi; Song, Xuezheng; Heimburg-Molinaro, Jamie; Yu, Hai; Chen, Xi; Talekar, Ganesh R.; Smith, David F.; Cummings, Richard D.; Steinhauer, David A.

    2011-01-01

    To examine the range of selective processes that potentially operate when poorly binding influenza viruses adapt to replicate more efficiently in alternative environments, we passaged a virus containing an attenuating mutation in the hemagglutinin (HA) receptor binding site in mice and characterized the resulting mutants with respect to the structural locations of mutations selected, the replication phenotypes of the viruses, and their binding properties on glycan microarrays. The initial attenuated virus had a tyrosine-to-phenylalanine mutation at HA1 position 98 (Y98F), located in the receptor binding pocket, but viruses that were selected contained second-site pseudoreversion mutations in various structural locations that revealed a range of molecular mechanisms for modulating receptor binding that go beyond the scope that is generally mapped using receptor specificity mutants. A comparison of virus titers in the mouse respiratory tract versus MDCK cells in culture showed that the mutants displayed distinctive replication properties depending on the system, but all were less attenuated in mice than the Y98F virus. An analysis of receptor binding properties confirmed that the initial Y98F virus bound poorly to several different species of erythrocytes, while all mutants reacquired various degrees of hemagglutination activity. Interestingly, both the Y98F virus and pseudoreversion mutants were shown to bind very inefficiently to standard glycan microarrays containing an abundance of binding substrates for most influenza viruses that have been characterized to date, provided by the Consortium for Functional Glycomics. The viruses were also examined on a recently developed microarray containing glycans terminating in sialic acid derivatives, and limited binding to a potentially interesting subset of glycans was revealed. The results are discussed with respect to mechanisms for HA-mediated receptor binding, as well as regarding the species of molecules that may act

  14. Medical Underwriting In Long-Term Care Insurance: Market Conditions Limit Options For Higher-Risk Consumers.

    PubMed

    Cornell, Portia Y; Grabowski, David C; Cohen, Marc; Shi, Xiaomei; Stevenson, David G

    2016-08-01

    A key feature of private long-term care insurance is that medical underwriters screen out would-be buyers who have health conditions that portend near-term physical or cognitive disability. We applied common underwriting criteria based on data from two long-term care insurers to a nationally representative sample of individuals in the target age range (50-71 years) for long-term care insurance. The screening criteria put upper bounds on the current proportion of Americans who could gain coverage in the individual market without changes to medical underwriting practice. Specifically, our simulations show that in the target age range, approximately 30 percent of those whose wealth meets minimum industry standards for suitability for long-term care insurance would have their application for such insurance rejected at the underwriting stage. Among the general population-without considering financial suitability-we estimated that 40 percent would have their applications rejected. The predicted rejection rates are substantially higher than the rejection rates of about 20-25 percent of applicants in the actual market. In evaluating reforms for long-term care financing and their potential to increase private insurance rates, as well as to reduce financial pressure on public safety-net programs, policy makers need to consider the role of underwriting in the market for long-term care insurance. PMID:27503976

  15. Lunar core: occam's razor?

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    Whether or not the earth's moon has a core is a much bandied question. Like many notions about the properties of the moon, ideas of a lunar core changed drastically after the Apollo studies. A review of the development of these ideas was given a scholarly treatment by S.K. Runcorn recently (Nature, 304, 589-596, 1983). In contrast, L.L. Hood, C.P. Sonett, and L.J. Srnka have questioned the concept in serious detail (Nature, 307, 661-662, 1984).Whether or not the moon actually has or has had a fluid metallic core is of great consequence for a number of geophysical theories about the solar system. Most investigators concede that the possible existence of a lunar core remains one of the major unanswered, and yet most critical, questions about the moon. A lot rides on the answer: Can a lunar-sized body have a core? Is the core metallic? How is the core related to lunar magnetism and its paleomagnetism? Is or was a lunar core related to lunar volcanism? If the moon can have a core, is planetary core formation in the solar system a simple matter of gravitationally segregating metallic fragments that were formed elsewhere? Implications of the questions are without limit. There is, perhaps, no more valid issue about the moon to explore scientifically.

  16. Pyrotag sequencing of the gut microbiota of the cockroach Shelfordella lateralis reveals a highly dynamic core but only limited effects of diet on community structure.

    PubMed

    Schauer, Christine; Thompson, Claire; Brune, Andreas

    2014-01-01

    Although blattid cockroaches and termites share a common ancestor, their diets are distinctly different. While termites consume a highly specialized diet of lignocellulose, cockroaches are omnivorous and opportunistic feeders. The role of the termite gut microbiota has been studied intensively, but little is known about the cockroach gut microbiota and its function in digestion and nutrition, particularly the adaptation to different diets. Our analyses of the bacterial gut microbiota of the blattid cockroach Shelfordella lateralis combining terminal restriction fragment length polymorphism of their 16S rRNA genes with physiological parameters (microbial metabolites, hydrogen and methane emission) indicated substantial variation between individuals but failed to identify any diet-related response. Subsequent deep-sequencing of the 16S rRNA genes of the colonic gut microbiota of S. lateralis fed either a high- or a low-fiber diet confirmed the absence of bacterial taxa that responded to diet. Instead, we found a small number of abundant phylotypes that were consistently present in all samples and made up half of the community in both diet groups. They varied strongly in abundance between individual samples at the genus but not at the family level. The remaining phylotypes were inconsistently present among replicate batches. Our findings suggest that S. lateralis harbors a highly dynamic core gut microbiota that is maintained even after fundamental dietary shifts, and that any dietary effects on the gut community are likely to be masked by strong individual variations. PMID:24454939

  17. Incompressible limit of all-time solutions to 3-D full Navier-Stokes equations for perfect gas with well-prepared initial condition

    NASA Astrophysics Data System (ADS)

    Ren, Dandan; Ou, Yaobin

    2016-08-01

    In this paper, we prove the incompressible limit of all-time strong solutions to the three-dimensional full compressible Navier-Stokes equations. Here the velocity field and temperature satisfy the Dirichlet boundary condition and convective boundary condition, respectively. The uniform estimates in both the Mach number {ɛin(0,overline{ɛ}]} and time {tin[0,∞)} are established by deriving a differential inequality with decay property, where {overline{ɛ} in(0,1]} is a constant. Based on these uniform estimates, the global solution of full compressible Navier-Stokes equations with "well-prepared" initial conditions converges to the one of isentropic incompressible Navier-Stokes equations as the Mach number goes to zero.

  18. Ultraviolet laser desorption/ionization mass spectrometry of single-core and multi-core polyaromatic hydrocarbons under variable conditions of collisional cooling: insights into the generation of molecular ions, fragments and oligomers.

    PubMed

    Gámez, Francisco; Hortal, Ana R; Martínez-Haya, Bruno; Soltwisch, Jens; Dreisewerd, Klaus

    2014-11-01

    The ultraviolet laser desorption/ionization of polyaromatic hydrocarbons (PAHs) has been investigated under different background pressures of an inert gas (up to 1.2 mbar of N2) in the ion source of a hybrid, orthogonal-extracting time-of-flight mass spectrometer (oTOF-MS). The study includes an ensemble of six model PAHs with isolated single polyaromatic cores and four ones with multiple cross-linked aromatic and polyaromatic cores. In combination with a weak ion extraction field, the variation of the buffer gas pressure allowed to control the degree of collisional cooling of the desorbed PAHs and, thus, to modulate their decomposition into fragments. The dominant fragmentation channels observed are related to dehydrogenation of the PAHs, in most cases through the cleavage of even numbers of C-H bonds. Breakage of C-C bonds leading to the fragmentation of rings, side chains and core linkages is also observed, in particular, at low buffer gas pressures. The precise patterns of the combined fragmentation processes vary significantly between the PAHs. The highest abundances of molecular PAH ions and cleanest mass spectra were consistently obtained at the highest buffer gas pressure of 1.2 mbar. The effective quenching of the fragmentation pathways at this elevated pressure improves the sensitivity and data interpretation for analytical applications, although the fragmentation of side chains and of bonds between (poly)aromatic cores is not completely suppressed in all cases. Moreover, these results suggest that the detected fragments are generated through thermal equilibrium processes rather than as a result of rapid photolysis. This assumption is further corroborated by a laser desorption/ionization post-source decay analysis using an axial time-of-flight MS. In line with these findings, covalent oligomers of the PAHs, which are presumably formed by association of two or more dehydrogenated fragments, are detected with higher abundances at the lower buffer gas

  19. Superconducting shielded core reactor with reduced AC losses

    DOEpatents

    Cha, Yung S.; Hull, John R.

    2006-04-04

    A superconducting shielded core reactor (SSCR) operates as a passive device for limiting excessive AC current in a circuit operating at a high power level under a fault condition such as shorting. The SSCR includes a ferromagnetic core which may be either closed or open (with an air gap) and extends into and through a superconducting tube or superconducting rings arranged in a stacked array. First and second series connected copper coils each disposed about a portion of the iron core are connected to the circuit to be protected and are respectively wound inside and outside of the superconducting tube or rings. A large impedance is inserted into the circuit by the core when the shielding capability of the superconducting arrangement is exceeded by the applied magnetic field generated by the two coils under a fault condition to limit the AC current in the circuit. The proposed SSCR also affords reduced AC loss compared to conventional SSCRs under continuous normal operation.

  20. The amino-terminal GAF domain of Azotobacter vinelandii NifA binds 2-oxoglutarate to resist inhibition by NifL under nitrogen-limiting conditions.

    PubMed

    Little, Richard; Dixon, Ray

    2003-08-01

    The expression of genes required for the synthesis of molybdenum nitrogenase in Azotobacter vinelandii is controlled by the NifL-NifA transcriptional regulatory complex in response to nitrogen, carbon, and redox status. Activation of nif gene expression by the transcriptional activator NifA is inhibited by direct protein-protein interaction with NifL under conditions unfavorable for nitrogen fixation. We have recently shown that the NifL-NifA system responds directly to physiological concentrations of 2-oxoglutarate, resulting in relief of NifA activity from inhibition by NifL under conditions when fixed nitrogen is limiting. The inhibitory activity of NifL is restored under conditions of excess combined nitrogen through the binding of the signal transduction protein Av GlnK to the carboxyl-terminal domain of NifL. The amino-terminal domain of NifA comprises a GAF domain implicated in the regulatory response to NifL. A truncated form of NifA lacking this domain is not responsive to 2-oxoglutarate in the presence of NifL, suggesting that the GAF domain is required for the response to this ligand. Using isothermal titration calorimetry, we demonstrate stoichiometric binding of 2-oxoglutarate to both the isolated GAF domain and the full-length A. vinelandii NifA protein with a dissociation constant of approximately 60 microm. Limited proteolysis experiments indicate that the binding of 2-oxoglutarate increases the susceptibility of the GAF domain to trypsin digestion and also prevents NifL from protecting these cleavage sites. However, protection by NifL is restored when the non-modified (non-uridylylated) form of Av GlnK is also present. Our results suggest that the binding of 2-oxoglutarate to the GAF domain of NifA may induce a conformational change that prevents inhibition by NifL under conditions when fixed nitrogen is limiting. PMID:12759352

  1. The ColRS system of Xanthomonas oryzae pv. oryzae is required for virulence and growth in iron-limiting conditions.

    PubMed

    Subramoni, Sujatha; Pandey, Alok; Vishnu Priya, M R; Patel, Hitendra Kumar; Sonti, Ramesh V

    2012-09-01

    Xanthomonas oryzae pv. oryzae, the causal agent of bacterial blight of rice, produces siderophores only under iron-limiting conditions. We screened 15 400 mTn5-induced mutants of X. oryzae pv. oryzae and isolated 27 mutants that produced siderophores even under iron-replete conditions. We found that the mTn5 insertions in 25 of these mutants were in or close to six genes. Mutants with insertions in five of these genes [colS, XOO1806 (a conserved hypothetical protein), acnB, prpR and prpB] exhibited a deficiency for growth on iron-limiting medium and a decrease in virulence. Insertions in a sixth gene, XOO0007 (a conserved hypothetical protein), were found to affect the ability to grow on iron-limiting medium, but did not affect the virulence. Targeted gene disruptants for colR (encoding the predicted cognate regulatory protein for ColS) also exhibited a deficiency for growth on iron-limiting medium and a decrease in virulence. colR and colS mutants were defective in the elicitation of hypersensitive response symptoms on the nonhost tomato. In addition, colR and colS mutants induced a rice basal defence response, suggesting that they are compromised in the suppression of host innate immunity. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis demonstrated that a functional ColRS system is required for the optimal expression of several genes encoding components of the type 3 secretion system (T3SS) of X. oryzae pv. oryzae. Our results demonstrate the role of several novel genes, including colR/colS, in the promotion of growth on iron-limiting medium and the virulence of X. oryzae pv. oryzae. PMID:22257308

  2. Combined core/boundary layer transport simulations in tokamaks

    SciTech Connect

    Prinja, A.K.; Schafer, R.F. Jr.; Conn, R.W.; Howe, H.C.

    1986-04-01

    Significant new numerical results are presented from self-consistent core and boundary or scrape-off layer plasma simulations with 3-D neutral transport calculations. For a symmetric belt limiter it is shown that, for plasma conditions considered here, the pump limiter collection efficiency increases from 11% to 18% of the core efflux as a result of local reionization of blade deflected neutrals. This hitherto unobserved effect causes a significant amplification of upstream ion flux entering the pump limiter. Results from coupling of an earlier developed two-zone edge plasma model ODESSA to the PROCTR core plasma simulation code indicates that intense recycling divertor operation may not be possible because of stagnation of upstream flow velocity. This results in a self-consistent reduction of density gradient in an intermediate region between the central plasma and separatrix, and a concomitant reduction of core-efflux. There is also evidence of increased recycling at the first wall.

  3. Global Core Plasma Model

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis L.; Craven, P. D.; Comfort, R. H.

    1999-01-01

    Abstract. The Global Core Plasma Model (GCPM) provides, empirically derived, core plasma density as a function of geomagnetic and solar conditions throughout the inner magnetosphere. It is continuous in value and gradient and is composed of separate models for the ionosphere, the plasmasphere, the plasmapause, the trough, and the polar cap. The relative composition of plasmaspheric H+, He+, and O+ is included in the GCPM. A blunt plasmaspheric bulge and rotation of the bulge with changing geomagnetic conditions is included. The GCPM is an amalgam of density models, intended to serve as a framework for continued improvement as new measurements become available and are used to characterize core plasma density, composition, and temperature.

  4. On Limits

    NASA Technical Reports Server (NTRS)

    Holzmann, Gerard J.

    2008-01-01

    In the last 3 decades or so, the size of systems we have been able to verify formally with automated tools has increased dramatically. At each point in this development, we encountered a different set of limits -- many of which we were eventually able to overcome. Today, we may have reached some limits that may be much harder to conquer. The problem I will discuss is the following: given a hypothetical machine with infinite memory that is seamlessly shared among infinitely many CPUs (or CPU cores), what is the largest problem size that we could solve?

  5. End-of-Life Discussions and Advance Care Planning for Children on Long-Term Assisted Ventilation with Life-Limiting Conditions

    PubMed Central

    Kun, Sheila S.; Graham, Robert J.; Keens, Thomas G.

    2013-01-01

    Families of children with life-limiting conditions who are on long-term assisted ventilation need to undertake end-of-life advance care planning (ACP) in order to align their goals and values with the inevitability of their child's condition and the risks it entails. To discuss how best to conduct ACP in this population, we performed a retrospective analysis of end-of-life discussions involving our deceased ventilator-assisted patients between 1987 and 2009. A total of 34 (72 percent) of 47 study patients were the subject of these discussions; many discussions occurred after acute deterioration. They resulted in directives to forgo or limit interventions for 21 children (45 percent). We surmise that many families were hesitant to discuss end-of-life issues during periods of relative stability. By offering anticipatory guidance and encouraging contemplation of patients’ goals both in times of stability and during worsening illness, health care providers can better engage patients’ families in ACP. As the child's condition progresses, the emphasis can be recalibrated. How families respond to such encouragement can also serve as a gauge of their willingness to pursue ACP. PMID:22582468

  6. Behavior of fuel-lean premixed flames in a standard flammability limit tube under controlled gravity conditions. Final report, January-December 1985

    SciTech Connect

    Wherley, B.L.; Strehlow, R.A.

    1986-07-01

    Fuel-lean flames in methane-air mixtures from 4.90 to 6.20 volume percent fuel and propane-air mixtures from 1.90 to 3.00 volume percent fuel were studied in the vicinity of the limit for a variety of gravity conditions. The limits were determined and the behavior of the flames studied for one g upward, one g downward, and zero g propagation. Photographic records of all flammability tube firings were obtained. The structure and behavior of these flames were detailed including the variations of the curvature of the flame front, the skirt length, and the occurrence of cellular instabilities with varying gravity conditions. The effect of ignition was also discussed. A survey of flame speeds as a function of mixture strength was made over a range of lean mixture compositions for each of the fuels studied. The results were presented graphically with those obtained by other researchers. The flame speed for constant fractional gravity loadings were plotted as a function of gravity loadings from 0.0 up to 2.0 g's against flame speeds extracted from the transient gravity flame histories for corresponding gravity loadings. The effects of varying gravity conditions on the extinguishment process for upward and downward propagating flames were investigated.

  7. A Comprehensive Approach to Assess Arabidopsis Survival Phenotype in Water-Limited Condition Using a Non-invasive High-Throughput Phenomics Platform

    PubMed Central

    Vello, Emilio; Tomita, Akiko; Diallo, Amadou Oury; Bureau, Thomas E.

    2015-01-01

    With the rapid rise in global population and the challenges caused by climate changes, the maximization of plant productivity and the development of sustainable agriculture strategies are vital for food security. One of the resources more affected in this new environment will be the limitation of water. In this study, we describe the use of non-invasive technologies exploiting sensors for visible, fluorescent, and near-infrared lights to accurately screen survival phenotypes in Arabidopsis thaliana exposed to water-limited conditions. We implemented two drought protocols and a robust analysis methodology that enabled us to clearly assess the wilting or dryness status of the plants at different time points using a phenomics platform. In conclusion, our approach has shown to be very accurate and suitable for experiments where hundred of samples have to be screened making a manual evaluation unthinkable. This approach can be used not only in functional genomics studies but also in agricultural applications. PMID:26697051

  8. CO2 Reaction Induced Wettability Alteration and its Impacts on CO2 Storage: Pore to Core Scale Reservoir Condition Experimental Studies

    NASA Astrophysics Data System (ADS)

    Wan, J.; Tokunaga, T. K.; Kim, Y.; Jung, J.; Kim, T.; Dong, W.

    2013-12-01

    Wettability of the mineral surfaces plays an important role in subsurface multiphase flow and transport. Wettability affects the capillary pressure-saturation (Pc- S) relations, relative permeability (kr) of each fluid phase, and relative phase occupancy in reservoir pores. Although wettability issues have been studied extensively in other fields, significant knowledge gaps remain when applying the existing understanding to geological carbon sequestration; due largely to the unique physical-chemical properties of supercritical (sc) CO2 relative to other common non-wetting fluids such as air and oil. Here, we report our recent progress on wettability alteration upon reaction with CO2 and the resulting differences in capillary trapping of CO2 versus air. (1) Pore Scale Studies. There are conflict predictions in the literature concerning the effect of wettability on capillary trapping; some find that larger contact angles lead to lower capillary trapping while others have found opposite behavior. We hypothesized that spontaneous imbibition becomes energetically unfavorable with decreased wettability, so that increased residual trapping of scCO2 should occur during the post-injection inbibition stage. We developed a laboratory high-pressure and elevated temperature microscopic-micromodel system that is capable of controlling fine scale capillary pressure of scCO2-brine, and enabled us to conduct imbibition under controlled capillary pressures at the pore scale. We found that the de-wetting enhanced scCO2 capillary trapping is significant. These results suggest that scCO2 reaction induced dewetting can result in higher degrees of CO2 residual trapping in the post-injection stage than previously predicted. (2) Core Scale Studies. Capillary scaling is used routinely to predict Pc(S) relations for scCO2-brine systems at field scale, based on relations measured with air-water or mercury porosimetry. However, scaling-based predictions for CO2-brine systems have not been

  9. Effect of Fuel Composition, Engine Operating Variables, and Spark-Plug Type and Condition on Preignition-Limited Performance of an R-2800 Cylinder

    NASA Technical Reports Server (NTRS)

    Pfender, John F.

    1946-01-01

    The preignition characteristics of the R-2800 cylinder, as effected by fuel consumption, engine operating variables, and spark plug type and condition, were evaluated. The effects on preignition-limited performance of various percentages of aromatics (benzene, toluene, cumene, xylene) in a base fuel of triptane were investigated. Two paraffins (triptane and S + 6.0 ml TEL/gal) and two refinery blends (28-R and 33-R) were preignition rated. The effect of changes in the following engine operating variables on preignition limit was determined: inlet-air temperature, rear spark plug gasket temperature, engine speed, spark advance, tappet clearance, and oil consumption. Preignition limits of the R-2800 cylinder using Champion C34S and C35S and AC-LS86, LS87, and LS88 spark plugs were established and the effect of spark plug deterioration was investigated. No definite trends in preignition-limited indicated mean effective pressure were indicated for aromatics as a class when increased percentages of different aromatics were added to a base fuel of triptane. Three types of fuel (aromatics, paraffins, and refinery blends) showed a preignition range for this cylinder from 65 to 104 percent when based on the performance of S plus 6.0 ml TEL per gallon as 100 percent. The R-2800 cylinder is therefore relatively insensitive to fuel composition when compared to a CFR F-4 engine, which had a pre-ignition range from 72 to 100 percent for the same fuels. Six engine operating variables were investigated with the following results: preignition-limited indicated mean effective pressure decreased, with increases in engine speed, rear spark plug gasket temperature, inlet-air temperature, and spark advance beyond 20 F B.T.C. and was unaffected by rate of oil consumption or by tappet clearance. Spark plugs were rated over a range of preignition-limited indicated mean effective pressure from 200 to 390 pounds per square inch at a fuel-air ratio of 0.07 in the following order of increased

  10. Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition

    PubMed Central

    Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

    2016-01-01

    The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

  11. Oxygen Partial Pressure Is a Rate-Limiting Parameter for Cell Proliferation in 3D Spheroids Grown in Physioxic Culture Condition.

    PubMed

    Gomes, Aurélie; Guillaume, Ludivine; Grimes, David Robert; Fehrenbach, Jérôme; Lobjois, Valérie; Ducommun, Bernard

    2016-01-01

    The in situ oxygen partial pressure in normal and tumor tissues is in the range of a few percent. Therefore, when studying cell growth in 3D culture systems, it is essential to consider how the physiological oxygen concentration, rather than the one in the ambient air, influences the proliferation parameters. Here, we investigated the effect of reducing oxygen partial pressure from 21% to 5% on cell proliferation rate and regionalization in a 3D tumor spheroid model. We found that 5% oxygen concentration strongly inhibited spheroid growth, changed the proliferation gradient and reduced the 50% In Depth Proliferation index (IDP50), compared with culture at 21% oxygen. We then modeled the oxygen partial pressure profiles using the experimental data generated by culturing spheroids in physioxic and normoxic conditions. Although hypoxia occurred at similar depth in spheroids grown in the two conditions, oxygen partial pressure was a major rate-limiting factor with a critical effect on cell proliferation rate and regionalization only in spheroids grown in physioxic condition and not in spheroids grown at atmospheric normoxia. Our findings strengthen the need to consider conducting experiment in physioxic conditions (i.e., tissue normoxia) for proper understanding of cancer cell biology and the evaluation of anticancer drugs in 3D culture systems. PMID:27575790

  12. Over-expression of the Arabidopsis proton-pyrophosphatase AVP1 enhances transplant survival, root mass, and fruit development under limiting phosphorus conditions

    PubMed Central

    Yang, Haibing; Zhang, Xiao; Gaxiola, Roberto A.; Xu, Guohua; Peer, Wendy Ann; Murphy, Angus S.

    2014-01-01

    Phosphorus (P), an element required for plant growth, fruit set, fruit development, and fruit ripening, can be deficient or unavailable in agricultural soils. Previously, it was shown that over-expression of a proton-pyrophosphatase gene AVP1/AVP1D (AVP1DOX) in Arabidopsis, rice, and tomato resulted in the enhancement of root branching and overall mass with the result of increased mineral P acquisition. However, although AVP1 over-expression also increased shoot biomass in Arabidopsis, this effect was not observed in tomato under phosphate-sufficient conditions. AVP1DOX tomato plants exhibited increased rootward auxin transport and root acidification compared with control plants. AVP1DOX tomato plants were analysed in detail under limiting P conditions in greenhouse and field trials. AVP1DOX plants produced 25% (P=0.001) more marketable ripened fruit per plant under P-deficient conditions compared with the controls. Further, under low phosphate conditions, AVP1DOX plants displayed increased phosphate transport from leaf (source) to fruit (sink) compared to controls. AVP1DOX plants also showed an 11% increase in transplant survival (P<0.01) in both greenhouse and field trials compared with the control plants. These results suggest that selection of tomato cultivars for increased proton pyrophosphatase gene expression could be useful when selecting for cultivars to be grown on marginal soils. PMID:24723407

  13. OD(X/sup 2/II) and SD(X/sup 2/II) from reactions of D atoms with OCS under bulk and precursor geometry limited conditions

    SciTech Connect

    Haeusler, D.; Rice, J.; Wittig, C.

    1987-10-08

    Reactions of D atoms with OCS were studied by 193-nm pulsed laser photolysis of DBr as a nearly monoenergetic D-atom source. Nascent OD(X/sup 2/II) and SD(X/sup 2/II) rotational, vibrational, spin-orbit, and ..lambda..-doublet populations were obtained under single-collision bulk conditions at 300 K. The SD channel is favored energetically (..delta.. H = -43 +/- 13 and 230 +/- 13 kJ mol/sup -1/ for the SD and OD channels, respectively) and is the dominant pathway ((SD)/(OD) = 5 +/- 2). Nascent OD(X/sup 2/II) products were also obtained from a precursor geometry limited (PGL) reaction by using the weakly bound van der Waals complex SCO-DBr. The OD(X/sup 2/II) rotational distributions are the same for both bulk and PGL conditions and can be reproduced by using a statistical model. Due to experimental difficulties, SD(X/sup 2/II) distributions could not be obtained under PGL conditions. The SD(X/sup 2/II) distribution obtained under bulk conditions is very nonstatistical, suggesting that this species is not formed via a long-lived DSCO intermediate complex in which vibrational energy is randomized.

  14. Controls on dissolved organic matter (DOM) degradation in a headwater stream: the influence of photochemical and hydrological conditions in determining light-limitation or substrate-limitation of photo-degradation

    NASA Astrophysics Data System (ADS)

    Cory, R. M.; Harrold, K. H.; Neilson, B. T.; Kling, G. W.

    2015-11-01

    -degradation is "light-limited" or "substrate-limited". We suggest that degradation of DOM in CDOM-rich streams or ponds similar to Imnavait is typically light-limited under most flow conditions. Thus, export of DOM from this stream will be less under conditions that increase the light available for DOM photo-degradation (i.e., low flows, sunny days).

  15. Micro coring apparatus

    NASA Technical Reports Server (NTRS)

    Collins, David; Brooks, Marshall; Chen, Paul; Dwelle, Paul; Fischer, Ben

    1989-01-01

    A micro-coring apparatus for lunar exploration applications, that is compatible with the other components of the Walking Mobile Platform, was designed. The primary purpose of core sampling is to gain an understanding of the geological composition and properties of the prescribed environment. This procedure has been used extensively for Earth studies and in limited applications during lunar explorations. The corer is described and analyzed for effectiveness.

  16. Nuclear core positioning system

    DOEpatents

    Garkisch, Hans D.; Yant, Howard W.; Patterson, John F.

    1979-01-01

    A structural support system for the core of a nuclear reactor which achieves relatively restricted clearances at operating conditions and yet allows sufficient clearance between fuel assemblies at refueling temperatures. Axially displaced spacer pads having variable between pad spacing and a temperature compensated radial restraint system are utilized to maintain clearances between the fuel elements. The core support plates are constructed of metals specially chosen such that differential thermal expansion produces positive restraint at operating temperatures.

  17. DUBLIN CORE

    EPA Science Inventory

    The Dublin Core is a metadata element set intended to facilitate discovery of electronic resources. It was originally conceived for author-generated descriptions of Web resources, and the Dublin Core has attracted broad ranging international and interdisciplinary support. The cha...

  18. An advanced coarse-grained nucleosome core particle model for computer simulations of nucleosome-nucleosome interactions under varying ionic conditions.

    PubMed

    Fan, Yanping; Korolev, Nikolay; Lyubartsev, Alexander P; Nordenskiöld, Lars

    2013-01-01

    In the eukaryotic cell nucleus, DNA exists as chromatin, a compact but dynamic complex with histone proteins. The first level of DNA organization is the linear array of nucleosome core particles (NCPs). The NCP is a well-defined complex of 147 bp DNA with an octamer of histones. Interactions between NCPs are of paramount importance for higher levels of chromatin compaction. The polyelectrolyte nature of the NCP implies that nucleosome-nucleosome interactions must exhibit a great influence from both the ionic environment as well as the positively charged and highly flexible N-terminal histone tails, protruding out from the NCP. The large size of the system precludes a modelling analysis of chromatin at an all-atom level and calls for coarse-grained approximations. Here, a model of the NCP that include the globular histone core and the flexible histone tails described by one particle per each amino acid and taking into account their net charge is proposed. DNA wrapped around the histone core was approximated at the level of two base pairs represented by one bead (bases and sugar) plus four beads of charged phosphate groups. Computer simulations, using a Langevin thermostat, in a dielectric continuum with explicit monovalent (K(+)), divalent (Mg(2+)) or trivalent (Co(NH(3))(6) (3+)) cations were performed for systems with one or ten NCPs. Increase of the counterion charge results in a switch from repulsive NCP-NCP interaction in the presence of K(+), to partial aggregation with Mg(2+) and to strong mutual attraction of all 10 NCPs in the presence of CoHex(3+). The new model reproduced experimental results and the structure of the NCP-NCP contacts is in agreement with available data. Cation screening, ion-ion correlations and tail bridging contribute to the NCP-NCP attraction and the new NCP model accounts for these interactions. PMID:23418426

  19. Associations between chronic conditions, body functions, activity limitations and participation restrictions: a cross-sectional approach in Spanish non-clinical populations

    PubMed Central

    Rodríguez-Blázquez, Carmen; Damián, Javier; Andrés-Prado, María José; Almazán-Isla, Javier; Alcalde-Cabero, Enrique; Forjaz, Maria João; Castellote, Juan Manuel; González-Enríquez, Jesús; Martínez-Martín, Pablo; Comín, Magdalena; de Pedro-Cuesta, Jesús

    2016-01-01

    Objectives To analyse the relationships between chronic conditions, body functions, activity limitations and participation restrictions in the International Classification of Functioning, Disability and Health (ICF) framework. Design A cross-sectional study. Setting 2 geographical areas in the Autonomous Region of Aragon, Spain, namely, a rural area, Cinco Villas, and an urban area in the city of Zaragoza. Participants 864 individuals selected by simple random sampling from the register of Social Security card holders, aged 50 years and over, positive to disability screening. Main outcome measures ICF Checklist—body function domains, WHO Disability Assessment Schedule 2.0 (WHODAS 2.0, 36-item (WHODAS-36)) global scores and medical diagnoses (chronic conditions) from primary care records. Results Mild disability (WHODAS-36 level 5–24%) was present in 51.5% of the sample. In the adjusted ordinal regression model with WHODAS-36 as the dependent variable, disability was substantially associated with moderate-to-complete impairment in the following functions: mental, OR 212.8 (95% CI 72 to 628.9); neuromusculoskeletal, OR 44.8 (24.2 to 82.8); and sensory and pain, OR 6.3 (3.5 to 11.2). In the relationship between health conditions and body function impairments, the strongest links were seen for: dementia with mental functions, OR 50.6 (25.1 to 102.1); cerebrovascular disease with neuromusculoskeletal function, OR 5.8 (3.5 to 9.7); and chronic renal failure with sensory function and pain, OR 3.0 (1.49 to 6.4). Dementia, OR 8.1 (4.4 to 14.7) and cerebrovascular disease, OR 4.1 (2.7 to 6.4) were associated with WHODAS-36 scores. Conclusions Body functions are heterogeneously linked to limitations in activities and restrictions on participation, with the highest impact being due to mental and musculoskeletal functions. This may be relevant for disability assessment and intervention design, particularly if defined on a body function basis. Control of specific health

  20. Phosphorus as a driver of nitrogen limitation and sustained eutrophic conditions in Bolinao and Anda, Philippines, a mariculture-impacted tropical coastal area.

    PubMed

    Ferrera, Charissa M; Watanabe, Atsushi; Miyajima, Toshihiro; San Diego-McGlone, Maria Lourdes; Morimoto, Naoko; Umezawa, Yu; Herrera, Eugene; Tsuchiya, Takumi; Yoshikai, Masaya; Nadaoka, Kazuo

    2016-04-15

    The dynamics of nitrogen (N) and phosphorus (P) was studied in mariculture areas around Bolinao and Anda, Philippines to examine its possible link to recurring algal blooms, hypoxia and fish kills. They occur despite regulation on number of fish farm structures in Bolinao to improve water quality after 2002, following a massive fish kill in the area. Based on spatiotemporal surveys, coastal waters remained eutrophic a decade after imposing regulation, primarily due to decomposition of uneaten and undigested feeds, and fish excretions. Relative to Redfield ratio (16), these materials are enriched in P, resulting in low N/P ratios (~6.6) of regenerated nutrients. Dissolved inorganic P (DIP) in the water reached 4μM during the dry season, likely exacerbated by increase in fish farm structures in Anda. DIP enrichment created an N-limited condition that is highly susceptible to sporadic algal blooms whenever N is supplied from freshwater during the wet season. PMID:26936120

  1. Microwave-Assisted Superheating and/or Microwave-Specific Superboiling (Nucleation-Limited Boiling) of Liquids Occurs under Certain Conditions but is Mitigated by Stirring.

    PubMed

    Ferrari, Anthony; Hunt, Jacob; Stiegman, Albert; Dudley, Gregory B

    2015-01-01

    Temporary superheating and sustained nucleation-limited "superboiling" of unstirred liquids above the normal atmospheric boiling point have been documented during microwave heating. These phenomena are reliably observed under prescribed conditions, although the duration (of superheating) and magnitude (of superheating and superboiling) vary according to system parameters such as volume of the liquid and the size and shape of the vessel. Both phenomena are mitigated by rapid stirring with an appropriate stir bar and/or with the addition of boiling chips, which provide nucleation sites to support the phase-change from liquid to gas. With proper experimental design and especially proper stirring, the measured temperature of typical organic reaction mixtures heated at reflux will be close to the normal boiling point temperature of the solvent, whether heated using microwave radiation or conventional convective heat transfer. These observations are important to take into consideration when comparing reaction rates under conventional and microwave heating. PMID:26690096

  2. Impact of sea-level rise on cross-shore sediment transport on fetch-limited barrier reef island beaches under modal and cyclonic conditions.

    PubMed

    Baldock, T E; Golshani, A; Atkinson, A; Shimamoto, T; Wu, S; Callaghan, D P; Mumby, P J

    2015-08-15

    A one-dimensional wave model is combined with an analytical sediment transport model to investigate the likely influence of sea-level rise on net cross-shore sediment transport on fetch-limited barrier reef and lagoon island beaches. The modelling considers if changes in the nearshore wave height and wave period in the lagoon induced by different water levels over the reef flat are likely to lead to net offshore or onshore movement of sediment. The results indicate that the effects of SLR on net sediment movement are highly variable and controlled by the bathymetry of the reef and lagoon. A significant range of reef-lagoon bathymetry, and notably shallow and narrow reefs, appears to lead hydrodynamic conditions and beaches that are likely to be stable or even accrete under SLR. Loss of reef structural complexity, particularly on the reef flat, increases the chance of sediment transport away from beaches and offshore. PMID:26093817

  3. Transient climate simulations of the deglaciation 21-9 thousand years before present (version 1) - PMIP4 Core experiment design and boundary conditions

    NASA Astrophysics Data System (ADS)

    Ivanovic, Ruza F.; Gregoire, Lauren J.; Kageyama, Masa; Roche, Didier M.; Valdes, Paul J.; Burke, Andrea; Drummond, Rosemarie; Peltier, W. Richard; Tarasov, Lev

    2016-07-01

    The last deglaciation, which marked the transition between the last glacial and present interglacial periods, was punctuated by a series of rapid (centennial and decadal) climate changes. Numerical climate models are useful for investigating mechanisms that underpin the climate change events, especially now that some of the complex models can be run for multiple millennia. We have set up a Paleoclimate Modelling Intercomparison Project (PMIP) working group to coordinate efforts to run transient simulations of the last deglaciation, and to facilitate the dissemination of expertise between modellers and those engaged with reconstructing the climate of the last 21 000 years. Here, we present the design of a coordinated Core experiment over the period 21-9 thousand years before present (ka) with time-varying orbital forcing, greenhouse gases, ice sheets and other geographical changes. A choice of two ice sheet reconstructions is given, and we make recommendations for prescribing ice meltwater (or not) in the Core experiment. Additional focussed simulations will also be coordinated on an ad hoc basis by the working group, for example to investigate more thoroughly the effect of ice meltwater on climate system evolution, and to examine the uncertainty in other forcings. Some of these focussed simulations will target shorter durations around specific events in order to understand them in more detail and allow for the more computationally expensive models to take part.

  4. Transient climate simulations of the deglaciation 21-9 thousand years before present; PMIP4 Core experiment design and boundary conditions

    NASA Astrophysics Data System (ADS)

    Ivanovic, R. F.; Gregoire, L. J.; Kageyama, M.; Roche, D. M.; Valdes, P. J.; Burke, A.; Drummond, R.; Peltier, W. R.; Tarasov, L.

    2015-10-01

    The last deglaciation, which marked the transition between the last glacial and present interglacial periods, was punctuated by a series of rapid (centennial and decadal) climate changes. Numerical climate models are useful for investigating mechanisms that underpin the events, especially now that some of the complex models can be run for multiple millennia. We have set up a Paleoclimate Modelling Intercomparison Project (PMIP) working group to coordinate efforts to run transient simulations of the last deglaciation, and to facilitate the dissemination of expertise between modellers and those engaged with reconstructing the climate of the last 21 thousand years. Here, we present the design of a coordinated Core simulation over the period 21-9 thousand years before present (ka) with time varying orbital forcing, greenhouse gases, ice sheets, and other geographical changes. A choice of two ice sheet reconstructions is given, but no ice sheet or iceberg meltwater should be prescribed in the Core simulation. Additional focussed simulations will also be coordinated on an ad-hoc basis by the working group, for example to investigate the effect of ice sheet and iceberg meltwater, and the uncertainty in other forcings. Some of these focussed simulations will focus on shorter durations around specific events to allow the more computationally expensive models to take part.

  5. Impaired health-related quality of life in children and adolescents with chronic conditions: a comparative analysis of 10 disease clusters and 33 disease categories/severities utilizing the PedsQL™ 4.0 Generic Core Scales

    PubMed Central

    Varni, James W; Limbers, Christine A; Burwinkle, Tasha M

    2007-01-01

    Background Advances in biomedical science and technology have resulted in dramatic improvements in the healthcare of pediatric chronic conditions. With enhanced survival, health-related quality of life (HRQOL) issues have become more salient. The objectives of this study were to compare generic HRQOL across ten chronic disease clusters and 33 disease categories/severities from the perspectives of patients and parents. Comparisons were also benchmarked with healthy children data. Methods The analyses were based on over 2,500 pediatric patients from 10 physician-diagnosed disease clusters and 33 disease categories/severities and over 9,500 healthy children utilizing the PedsQL™ 4.0 Generic Core Scales. Patients were recruited from general pediatric clinics, subspecialty clinics, and hospitals. Results Pediatric patients with diabetes, gastrointestinal conditions, cardiac conditions, asthma, obesity, end stage renal disease, psychiatric disorders, cancer, rheumatologic conditions, and cerebral palsy self-reported progressively more impaired overall HRQOL than healthy children, respectively, with medium to large effect sizes. Patients with cerebral palsy self-reported the most impaired HRQOL, while patients with diabetes self-reported the best HRQOL. Parent proxy-reports generally paralleled patient self-report, with several notable differences. Conclusion The results demonstrate differential effects of pediatric chronic conditions on patient HRQOL across diseases clusters, categories, and severities utilizing the PedsQL™ 4.0 Generic Core Scales from the perspectives of pediatric patients and parents. The data contained within this study represents a larger and more diverse population of pediatric patients with chronic conditions than previously reported in the extant literature. The findings contribute important information on the differential effects of pediatric chronic conditions on generic HRQOL from the perspectives of children and parents utilizing the Peds

  6. The chemolithoautotroph Acidithiobacillus ferrooxidans can survive under phosphate-limiting conditions by expressing a C-P lyase operon that allows it to grow on phosphonates.

    PubMed

    Vera, Mario; Pagliai, Fernando; Guiliani, Nicolas; Jerez, Carlos A

    2008-03-01

    The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans is of great importance in biomining operations. During the bioleaching of ores, microorganisms are subjected to a variety of environmental stresses and to the limitations of some nutrients, such as inorganic phosphate (P(i)), which is an essential component for all living cells. Although the primary source of phosphorus for microorganisms is P(i), some bacteria are also able to metabolize P(i) esters (with a C-O-P bond) and phosphonates (with a very inert C-P bond). By using bioinformatic analysis of genomic sequences of the type strain of A. ferrooxidans (ATCC 23270), we found that as part of a Pho regulon, this bacterium has a complete gene cluster encoding C-P lyase, which is the main bacterial enzyme involved in phosphonate (Pn) degradation in other microorganisms. A. ferrooxidans was able to grow in the presence of methyl-Pn or ethyl-Pn as an alternative phosphorus source. Under these growth conditions, a great reduction in inorganic polyphosphate (polyP) levels was seen compared with the level for cells grown in the presence of P(i). By means of reverse transcription-PCR (RT-PCR), DNA macroarrays, and real-time RT-PCR experiments, it was found that A. ferrooxidans phn genes were cotranscribed and their expression was induced when the microorganism was grown in methyl-Pn as the only phosphorus source. This is the first report of phosphonate utilization in a chemolithoautotrophic microorganism. The existence of a functional C-P lyase system is a clear advantage for the survival under P(i) limitation, a condition that may greatly affect the bioleaching of ores. PMID:18203861

  7. Overexpression of Arabidopsis NLP7 improves plant growth under both nitrogen-limiting and -sufficient conditions by enhancing nitrogen and carbon assimilation.

    PubMed

    Yu, Lin-Hui; Wu, Jie; Tang, Hui; Yuan, Yang; Wang, Shi-Mei; Wang, Yu-Ping; Zhu, Qi-Sheng; Li, Shi-Gui; Xiang, Cheng-Bin

    2016-01-01

    Nitrogen is essential for plant survival and growth. Excessive application of nitrogenous fertilizer has generated serious environment pollution and increased production cost in agriculture. To deal with this problem, tremendous efforts have been invested worldwide to increase the nitrogen use ability of crops. However, only limited success has been achieved to date. Here we report that NLP7 (NIN-LIKE PROTEIN 7) is a potential candidate to improve plant nitrogen use ability. When overexpressed in Arabidopsis, NLP7 increases plant biomass under both nitrogen-poor and -rich conditions with better-developed root system and reduced shoot/root ratio. NLP7-overexpressing plants show a significant increase in key nitrogen metabolites, nitrogen uptake, total nitrogen content, and expression levels of genes involved in nitrogen assimilation and signalling. More importantly, overexpression of NLP7 also enhances photosynthesis rate and carbon assimilation, whereas knockout of NLP7 impaired both nitrogen and carbon assimilation. In addition, NLP7 improves plant growth and nitrogen use in transgenic tobacco (Nicotiana tabacum). Our results demonstrate that NLP7 significantly improves plant growth under both nitrogen-poor and -rich conditions by coordinately enhancing nitrogen and carbon assimilation and sheds light on crop improvement. PMID:27293103

  8. On the effects of assembly compression on the performance of liquid-feed DMFCs under methanol-limiting conditions: A 2D numerical study

    NASA Astrophysics Data System (ADS)

    García-Salaberri, P. A.; Vera, M.

    2015-07-01

    The influence of assembly compression on the performance of liquid-feed DMFCs under methanol-limiting conditions is explored by means of a 2D/1D multiphysics across-the-channel model. The numerical formulation incorporates a comprehensive 2D description of the anode GDL, including two-phase phenomena, non-uniform anisotropic transport properties, and electrical contact resistances at the GDL/BPP interface. GDL effective properties are evaluated using empirical data corresponding to Toray® carbon paper. A simplified but physically sound 1D description, locally coupled to the 2D anode GDL model, is adopted to describe transport processes in the MPLs, membrane and cathode GDL, whereas the catalyst layers are treated as infinitely thin surfaces. Good agreement is found between the numerical results and previous experimental data. The interplay between assembly compression, bipolar plate material, and channel configuration is also investigated. The results show that there is an optimum GDL compression ratio in terms of overall power density, the optimal compression level being strongly dependent on bipolar plate material. Beyond the optimum, the detrimental effect of compression is larger in non-parallel flow fields due to the additional reduction of methanol transported by under-rib convection. The results suggest that, under certain conditions, this transport mechanism could be more important than diffusion in the anode of liquid-feed DMFCs.

  9. Bacterial Growth Stimulation with Exogenous Siderophore and Synthetic N-Acyl Homoserine Lactone Autoinducers under Iron-Limited and Low-Nutrient Conditions

    PubMed Central

    Guan, Le Luo; Onuki, Hiroyuki; Kamino, Kei

    2000-01-01

    The growth of marine bacteria under iron-limited conditions was investigated. Neither siderophore production nor bacterial growth was detected for Pelagiobacter sp. strain V0110 when Fe(III) was present in the culture medium at a concentration of <1.0 μM. However, the growth of V0110 was strongly stimulated by the presence of trace amounts of exogenous siderophore from an alpha proteobacterium, V0902, and 1 nM N-acyl-octanoylhomoserine lactone (C8-HSL), which is known as a quorum-sensing chemical signal. Even though the iron-binding functionality of a hydroxamate siderophore was undetected in the supernatant of V0902, a hydroxamate siderophore was detected in the supernatant of V0110 under the above conditions. These results indicated that hydroxamate siderophore biosynthesis by V0110 began in response to the exogenous siderophore from V0902 when in the presence of C8-HSL; however, C8-HSL production by V0110 and V0902 was not detected. Direct interaction between V0902 and V0110 through siderophore from V0902 was observed in the dialyzing culture. Similar stimulated growth by exogenous siderophore and HSL was also observed in other non-siderophore-producing bacteria isolated from marine sponges and seawater. The requirement of an exogenous siderophore and an HSL for heterologous siderophore production indicated the possibility that cell-cell communication between different species was occurring. PMID:10877770

  10. Overexpression of Arabidopsis NLP7 improves plant growth under both nitrogen-limiting and -sufficient conditions by enhancing nitrogen and carbon assimilation

    PubMed Central

    Yu, Lin-Hui; Wu, Jie; Tang, Hui; Yuan, Yang; Wang, Shi-Mei; Wang, Yu-Ping; Zhu, Qi-Sheng; Li, Shi-Gui; Xiang, Cheng-Bin

    2016-01-01

    Nitrogen is essential for plant survival and growth. Excessive application of nitrogenous fertilizer has generated serious environment pollution and increased production cost in agriculture. To deal with this problem, tremendous efforts have been invested worldwide to increase the nitrogen use ability of crops. However, only limited success has been achieved to date. Here we report that NLP7 (NIN-LIKE PROTEIN 7) is a potential candidate to improve plant nitrogen use ability. When overexpressed in Arabidopsis, NLP7 increases plant biomass under both nitrogen-poor and -rich conditions with better-developed root system and reduced shoot/root ratio. NLP7–overexpressing plants show a significant increase in key nitrogen metabolites, nitrogen uptake, total nitrogen content, and expression levels of genes involved in nitrogen assimilation and signalling. More importantly, overexpression of NLP7 also enhances photosynthesis rate and carbon assimilation, whereas knockout of NLP7 impaired both nitrogen and carbon assimilation. In addition, NLP7 improves plant growth and nitrogen use in transgenic tobacco (Nicotiana tabacum). Our results demonstrate that NLP7 significantly improves plant growth under both nitrogen-poor and -rich conditions by coordinately enhancing nitrogen and carbon assimilation and sheds light on crop improvement. PMID:27293103

  11. 24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...

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

    24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  12. A Deficiency in the Flavoprotein of Arabidopsis Mitochondrial Complex II Results in Elevated Photosynthesis and Better Growth in Nitrogen-Limiting Conditions1[W][OA

    PubMed Central

    Fuentes, Daniela; Meneses, Marco; Nunes-Nesi, Adriano; Araújo, Wagner L.; Tapia, Rodrigo; Gómez, Isabel; Holuigue, Loreto; Gutiérrez, Rodrigo A.; Fernie, Alisdair R.; Jordana, Xavier

    2011-01-01

    Mitochondrial complex II (succinate dehydrogenase [SDH]) plays roles both in the tricarboxylic acid cycle and the respiratory electron transport chain. In Arabidopsis (Arabidopsis thaliana), its flavoprotein subunit is encoded by two nuclear genes, SDH1-1 and SDH1-2. Here, we characterize heterozygous SDH1-1/sdh1-1 mutant plants displaying a 30% reduction in SDH activity as well as partially silenced plants obtained by RNA interference. We found that these plants displayed significantly higher CO2 assimilation rates and enhanced growth than wild-type plants. There was a strong correlation between CO2 assimilation and stomatal conductance, and both mutant and silenced plants displayed increased stomatal aperture and density. By contrast, no significant differences were found for dark respiration, chloroplastic electron transport rate, CO2 uptake at saturating concentrations of CO2, or biochemical parameters such as the maximum rates of carboxylation by Rubisco and of photosynthetic electron transport. Thus, photosynthesis is enhanced in SDH-deficient plants by a mechanism involving a specific effect on stomatal function that results in improved CO2 uptake. Metabolic and transcript profiling revealed that mild deficiency in SDH results in limited effects on metabolism and gene expression, and data suggest that decreases observed in the levels of some amino acids were due to a higher flux to proteins and other nitrogen-containing compounds to support increased growth. Strikingly, SDH1-1/sdh1-1 seedlings grew considerably better in nitrogen-limiting conditions. Thus, a subtle metabolic alteration may lead to changes in important functions such as stomatal function and nitrogen assimilation. PMID:21921116

  13. A deficiency in the flavoprotein of Arabidopsis mitochondrial complex II results in elevated photosynthesis and better growth in nitrogen-limiting conditions.

    PubMed

    Fuentes, Daniela; Meneses, Marco; Nunes-Nesi, Adriano; Araújo, Wagner L; Tapia, Rodrigo; Gómez, Isabel; Holuigue, Loreto; Gutiérrez, Rodrigo A; Fernie, Alisdair R; Jordana, Xavier

    2011-11-01

    Mitochondrial complex II (succinate dehydrogenase [SDH]) plays roles both in the tricarboxylic acid cycle and the respiratory electron transport chain. In Arabidopsis (Arabidopsis thaliana), its flavoprotein subunit is encoded by two nuclear genes, SDH1-1 and SDH1-2. Here, we characterize heterozygous SDH1-1/sdh1-1 mutant plants displaying a 30% reduction in SDH activity as well as partially silenced plants obtained by RNA interference. We found that these plants displayed significantly higher CO(2) assimilation rates and enhanced growth than wild-type plants. There was a strong correlation between CO(2) assimilation and stomatal conductance, and both mutant and silenced plants displayed increased stomatal aperture and density. By contrast, no significant differences were found for dark respiration, chloroplastic electron transport rate, CO(2) uptake at saturating concentrations of CO(2), or biochemical parameters such as the maximum rates of carboxylation by Rubisco and of photosynthetic electron transport. Thus, photosynthesis is enhanced in SDH-deficient plants by a mechanism involving a specific effect on stomatal function that results in improved CO(2) uptake. Metabolic and transcript profiling revealed that mild deficiency in SDH results in limited effects on metabolism and gene expression, and data suggest that decreases observed in the levels of some amino acids were due to a higher flux to proteins and other nitrogen-containing compounds to support increased growth. Strikingly, SDH1-1/sdh1-1 seedlings grew considerably better in nitrogen-limiting conditions. Thus, a subtle metabolic alteration may lead to changes in important functions such as stomatal function and nitrogen assimilation. PMID:21921116

  14. Initial Piloted Simulation Evaluation of the Reference-H High-Speed Civil Transport Design During Takeoff and Recovery From Limit Flight Conditions

    NASA Technical Reports Server (NTRS)

    Glaab, Louis J.

    1999-01-01

    An initial assessment of a proposed High-Speed Civil Transport (HSCT) was conducted in the fall of 1995 at the NASA Langley Research Center. This configuration, known as the Industry Reference-H (Ref.-H), was designed by the Boeing Aircraft Company as part of their work in the High Speed Research program. It included a conventional tail, a cranked-arrow wing, four mixed-flow turbofan engines, and capacity for transporting approximately 300 passengers. The purpose of this assessment was to evaluate and quantify operational aspects of the Reference-H configuration from a pilot's perspective with the additional goal of identifying design strengths as well as any potential configuration deficiencies. This study was aimed at evaluating the Ref.-H configuration at many points of the aircraft's envelope to determine the suitability of the vehicle to accomplish typical mission profiles as well as emergency or envelope-limit conditions. Pilot-provided Cooper-Harper ratings and comments constituted the primary vehicle evaluation metric. The analysis included simulated real-time piloted evaluations, performed in a 6 degree of freedom motion base NASA Langley Visual-Motion Simulator, combined with extensive bath analysis. The assessment was performed using the third major release of the simulation data base (known as Ref.-H cycle 2B).

  15. 'Why does it happen like this?' Consulting with users and providers prior to an evaluation of services for children with life limiting conditions and their families.

    PubMed

    Hunt, Anne; Brown, Erica; Coad, Jane; Staniszewska, Sophie; Hacking, Suzanne; Chesworth, Brigit; Chambers, Lizzie

    2015-09-01

    Children with life limiting conditions and their families have complex needs. Evaluations must consider their views and perspectives to ensure care is relevant, appropriate and acceptable. We consulted with children, young people, their parents and local professionals to gain a more informed picture of issues affecting them prior to preparing a bid to evaluate services in the area. Multiple methods included focus groups, face-to-face and telephone interviews and participatory activities. Recordings and products from activities were analysed for content to identify areas of relevance and concern. An overarching theme from parents was 'Why does it happen like this?' Services did not seem designed to meet their needs. Whilst children and young people expressed ideas related to quality of environment, services and social life, professionals focused on ways of meeting the families' needs. The theme that linked families' concerns with those of professionals was 'assessing individual needs'. Two questions to be addressed by the evaluation are (1) to what extent are services designed to meet the needs of children and families and (2) to what extent are children, young people and their families consulted about what they need? Consultations with families and service providers encouraged us to continue their involvement as partners in the evaluation. PMID:24270996

  16. The effect of various sandblasting conditions on surface changes of dental zirconia and shear bond strength between zirconia core and indirect composite resin

    PubMed Central

    Su, Naichuan; Yue, Li; Liao, Yunmao; Liu, Wenjia; Zhang, Hai; Li, Xin

    2015-01-01

    PURPOSE To measure the surface loss of dental restorative zirconia and the short-term bond strength between an indirect composite resin (ICR) and zirconia ceramic after various sandblasting processes. MATERIALS AND METHODS Three hundred zirconia bars were randomly divided into 25 groups according to the type of sandblasting performed with pressures of 0.1, 0.2, 0.4 and 0.6 MPa, sandblasting times of 7, 14 and 21 seconds, and alumina powder sizes of 50 and 110 µm. The control group did not receive sandblasting. The volume loss and height loss on zirconia surface after sandblasting and the shear bond strength (SBS) between the sandblasted zirconia and ICR after 24-h immersion were measured for each group using multivariate analysis of variance (ANOVA) and Least Significance Difference (LSD) test (α=.05). After sandblasting, the failure modes of the ICR/zirconia surfaces were observed using scanning electron microscopy. RESULTS The volume loss and height loss were increased with higher sandblasting pressure and longer sandblasting treatment, but they decreased with larger powder size. SBS was significantly increased by increasing the sandblasting time from 7 seconds to 14 seconds and from 14 seconds to 21 seconds, as well as increasing the size of alumina powder from 50 µm to 110 µm. SBS was significantly increased from 0.1 MPa to 0.2 MPa according to the size of alumina powder. However, the SBSs were not significantly different with the sandblasting pressure of 0.2, 0.4 and 0.6 MPa. The possibilities of the combination of both adhesive failure and cohesive failure within the ICR were higher with the increases in bonding strength. CONCLUSION Based on the findings of this study, sandblasting with alumina particles at 0.2 MPa, 21 seconds and the powder size of 110 µm is recommended for dental applications to improve the bonding between zirconia core and ICR. PMID:26140173

  17. University City Core Plan.

    ERIC Educational Resources Information Center

    Philadelphia City Planning Commission, PA.

    A redevelopment plan for an urban core area of about 300 acres was warranted by--(1) unsuitable building conditions, (2) undesirable land usage, and (3) faulty traffic circulation. The plan includes expansion of two universities and creation of a regional science center, high school, and medical center. Guidelines for proposed land use and zoning…

  18. Ultrasonic Drilling and Coring

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph

    1998-01-01

    A novel drilling and coring device, driven by a combination, of sonic and ultrasonic vibration, was developed. The device is applicable to soft and hard objects using low axial load and potentially operational under extreme conditions. The device has numerous potential planetary applications. Significant potential for commercialization in construction, demining, drilling and medical technologies.

  19. Core strengthening.

    PubMed

    Arendt, Elizabeth A

    2007-01-01

    Several recent studies have evaluated interventional techniques designed to reduce the risk of serious knee injuries, particularly noncontact anterior cruciate ligament injuries in female athletes. Maintenance of rotational control of the limb underneath the pelvis, especially in response to cutting and jumping activities, is a common goal in many training programs. Rotational control of the limb underneath the pelvis is mediated by a complex set of factors including the strength of the trunk muscles and the relationship between the core muscles. It is important to examine the interrelationship between lower extremity function and core stability. PMID:17472321

  20. ON THE INTERNAL DYNAMICS OF STARLESS CORES: STABILITY OF STARLESS CORES WITH INTERNAL MOTIONS AND COLLAPSE DYNAMICS

    SciTech Connect

    Seo, Young Min; Shirley, Yancy L.; Hong, Seung Soo

    2013-05-20

    In order to understand the collapse dynamics of observed low-mass starless cores, we revise the conventional stability condition of hydrostatic Bonnor-Ebert spheres to take internal motions into account. Because observed starless cores resemble Bonnor-Ebert density structures, the stability and dynamics of the starless cores are frequently analyzed by comparing to the conventional stability condition of a hydrostatic Bonnor-Ebert sphere. However, starless cores are not hydrostatic but have observed internal motions. In this study, we take gaseous spheres with a homologous internal velocity field and derive stability conditions of the spheres utilizing a virial analysis. We propose two limiting models of spontaneous gravitational collapse: the collapse of critical Bonnor-Ebert spheres and uniform density spheres. The collapse of these two limiting models is intended to provide the lower and the upper limits, respectively, of the infall speeds for a given density structure. The results of our study suggest that the stability condition sensitively depends on internal motions. A homologous inward motion with a transonic speed can reduce the critical size compared to the static Bonnor-Ebert sphere by more than a factor of two. As an application of the two limiting models of spontaneous gravitational collapse, we compare the density structures and infall speeds of the observed starless cores L63, L1544, L1689B, and L694-2 to the two limiting models. L1689B and L694-2 seem to have been perturbed to result in faster infall motions than for spontaneous gravitational collapse.

  1. Pressure Core Characterization

    NASA Astrophysics Data System (ADS)

    Santamarina, J. C.

    2014-12-01

    Natural gas hydrates form under high fluid pressure and low temperature, and are found in permafrost, deep lakes or ocean sediments. Hydrate dissociation by depressurization and/or heating is accompanied by a multifold hydrate volume expansion and host sediments with low permeability experience massive destructuration. Proper characterization requires coring, recovery, manipulation and testing under P-T conditions within the stability field. Pressure core technology allows for the reliable characterization of hydrate bearing sediments within the stability field in order to address scientific and engineering needs, including the measurement of parameters used in hydro-thermo-mechanical analyses, and the monitoring of hydrate dissociation under controlled pressure, temperature, effective stress and chemical conditions. Inherent sampling effects remain and need to be addressed in test protocols and data interpretation. Pressure core technology has been deployed to study hydrate bearing sediments at several locations around the world. In addition to pressure core testing, a comprehensive characterization program should include sediment analysis, testing of reconstituted specimens (with and without synthetic hydrate), and in situ testing. Pressure core characterization technology can be used to study other gas-charged formations such as deep sea sediments, coal bed methane and gas shales.

  2. Increased belowground C release during initial plant development of Populus deltoides x nigra grown under light and C reserve limited conditions

    NASA Astrophysics Data System (ADS)

    Studer, Mirjam S.; Siegwolf, Rolf T. W.; Schmidt, Michael W. I.; Abiven, Samuel

    2014-05-01

    Plants might be a key factor for the long-term stabilisation of carbon (C) in the soil, e.g. through enhanced physical protection of root-derived C against microbial decomposition in soil aggregates. On the other hand C released by the plants into the soil might promote the decomposition of native soil organic matter (SOM) through the stimulation of microbial activity. We measured the C budget of developing plant-soil systems (Populus deltoides x nigra, Cambisol soil) in the laboratory under controlled environmental conditions. In order to distinguish plant-derived from native C in the SOM and the soil CO2 efflux, we labelled the poplar shoots continuously with 13C-CO2 from first emergence of leaves (sprouting from stem cuttings). Throughout the experiment the CO2 fluxes (photosynthetic assimilation, dark respiratory loss, soil CO2 efflux) were measured frequently (every 30 min) and the 13C was traced in the soil CO2 efflux (1-2 times a week). After 10 weeks the plant-soil systems were destructively harvested and the distribution of the 13C distribution was analysed. The plants developed slowly (compared to previous experiments), most likely due to limitation in C reserves (long term cutting storage) and C supply (low light intensities). The amount of 13C recovered in the roots, microbial biomass and soil CO2 efflux was directly correlated with the leaf area of the different plant individuals. After 3-4 weeks of plant development we observed a high peak in the total soil CO2 efflux. During this time the relative belowground C release was increased massively over the basal rate of 17 % of net C assimilated, whereby the variability between the plant individuals was large. The smallest plants, i.e. the plants that were most resource limited, obtained the highest belowground C release accounting at the peak time for up to 57 % of net assimilated C. We hypothesize that the plants released specific compounds, which either directly (enzymatically) or indirectly (priming

  3. Strain localization in brittle-ductile shear zones: fluid-abundant vs. fluid-limited conditions (an example from Wyangala area, Australia)

    NASA Astrophysics Data System (ADS)

    Spruzeniece, L.; Piazolo, S.

    2015-07-01

    This study focuses on physiochemical processes occurring in a brittle-ductile shear zone at both fluid-present and fluid-limited conditions. In the studied shear zone (Wyangala, SE Australia), a coarse-grained two-feldspar-quartz-biotite granite is transformed into a medium-grained orthogneiss at the shear zone margins and a fine-grained quartz-muscovite phyllonite in the central parts. The orthogneiss displays cataclasis of feldspar and crystal-plastic deformation of quartz. Quartz accommodates most of the deformation and is extensively recrystallized, showing distinct crystallographic preferred orientation (CPO). Feldspar-to-muscovite, biotite-to-muscovite and albitization reactions occur locally at porphyroclasts' fracture surfaces and margins. However, the bulk rock composition shows very little change in respect to the wall rock composition. In contrast, in the shear zone centre quartz occurs as large, weakly deformed porphyroclasts in sizes similar to that in the wall rock, suggesting that it has undergone little deformation. Feldspars and biotite are almost completely reacted to muscovite, which is arranged in a fine-grained interconnected matrix. Muscovite-rich layers contain significant amounts of fine-grained intermixed quartz with random CPO. These domains are interpreted to have accommodated most of the strain. Bulk rock chemistry data show a significant increase in SiO2 and depletion in NaO content compared to the wall rock composition. We suggest that the high- and low-strain microstructures in the shear zone represent markedly different scenarios and cannot be interpreted as a simple sequential development with respect to strain. Instead, we propose that the microstructural and mineralogical changes in the shear zone centre arise from a local metasomatic alteration around a brittle precursor. When the weaker fine-grained microstructure is established, the further flow is controlled by transient porosity created at (i) grain boundaries in fine

  4. The prrAB Two-Component System Is Essential for Mycobacterium tuberculosis Viability and Is Induced under Nitrogen-Limiting Conditions

    PubMed Central

    Malhotra, Vandana; Cornelison, Garrett L.; Clark-Curtiss, Josephine E.

    2012-01-01

    The Mycobacterium tuberculosis prrA-prrB (Rv0903c-Rv0902c) two-component regulatory system is expressed during intracellular growth in human macrophages and is required for early intracellular multiplication in murine macrophages, suggesting its importance in establishing infection. To better understand the function of the prrA-prrB two-component system, we defined the transcriptional characteristics of the prrA and prrB genes during exponential and stationary growth and upon exposure to different environmental stresses and attempted to generate a prrA-prrB deletion mutant. The prrA and prrB genes constitute an operon and are cotranscribed during logarithmic growth, with transcriptional levels decreasing in stationary phase and during hypoxia. Despite the transcriptional differences, PrrA protein levels remained relatively stable throughout growth and in hypoxia. Under conditions of nitrogen limitation, prrAB transcription was induced, while acidic pH stress and carbon starvation did not significantly alter transcript levels. Deletion of the prrAB operon on the chromosome of M. tuberculosis H37Rv occurred only in the presence of an episomal copy of the prrAB genes, indicating that this two-component system is essential for viability. Characterization of the prrAB locus in M. tuberculosis Mt21D3, a previously described prrA transposon mutant, revealed that this strain is not a true prrA knockout mutant. Rather, Tn5367 transposon insertion into the prrA promoter only decreased prrA and prrB transcription and PrrA levels in Mt21D3 compared to those in the parental Mt103 clinical strain. These data provide the first report describing the essentiality of the M. tuberculosis prrAB two-component system and reveal insights into its potential role in mycobacterial growth and metabolism. PMID:22081401

  5. The prrAB two-component system is essential for Mycobacterium tuberculosis viability and is induced under nitrogen-limiting conditions.

    PubMed

    Haydel, Shelley E; Malhotra, Vandana; Cornelison, Garrett L; Clark-Curtiss, Josephine E

    2012-01-01

    The Mycobacterium tuberculosis prrA-prrB (Rv0903c-Rv0902c) two-component regulatory system is expressed during intracellular growth in human macrophages and is required for early intracellular multiplication in murine macrophages, suggesting its importance in establishing infection. To better understand the function of the prrA-prrB two-component system, we defined the transcriptional characteristics of the prrA and prrB genes during exponential and stationary growth and upon exposure to different environmental stresses and attempted to generate a prrA-prrB deletion mutant. The prrA and prrB genes constitute an operon and are cotranscribed during logarithmic growth, with transcriptional levels decreasing in stationary phase and during hypoxia. Despite the transcriptional differences, PrrA protein levels remained relatively stable throughout growth and in hypoxia. Under conditions of nitrogen limitation, prrAB transcription was induced, while acidic pH stress and carbon starvation did not significantly alter transcript levels. Deletion of the prrAB operon on the chromosome of M. tuberculosis H37Rv occurred only in the presence of an episomal copy of the prrAB genes, indicating that this two-component system is essential for viability. Characterization of the prrAB locus in M. tuberculosis Mt21D3, a previously described prrA transposon mutant, revealed that this strain is not a true prrA knockout mutant. Rather, Tn5367 transposon insertion into the prrA promoter only decreased prrA and prrB transcription and PrrA levels in Mt21D3 compared to those in the parental Mt103 clinical strain. These data provide the first report describing the essentiality of the M. tuberculosis prrAB two-component system and reveal insights into its potential role in mycobacterial growth and metabolism. PMID:22081401

  6. The ZmASR1 Protein Influences Branched-Chain Amino Acid Biosynthesis and Maintains Kernel Yield in Maize under Water-Limited Conditions1[W][OA

    PubMed Central

    Virlouvet, Laetitia; Jacquemot, Marie-Pierre; Gerentes, Denise; Corti, Hélène; Bouton, Sophie; Gilard, Françoise; Valot, Benoît; Trouverie, Jacques; Tcherkez, Guillaume; Falque, Matthieu; Damerval, Catherine; Rogowsky, Peter; Perez, Pascual; Noctor, Graham; Zivy, Michel; Coursol, Sylvie

    2011-01-01

    Abscisic acid-, stress-, and ripening-induced (ASR) proteins were first described about 15 years ago as accumulating to high levels during plant developmental processes and in response to diverse stresses. Currently, the effects of ASRs on water deficit tolerance and the ways in which their physiological and biochemical functions lead to this stress tolerance remain poorly understood. Here, we characterized the ASR gene family from maize (Zea mays), which contains nine paralogous genes, and showed that maize ASR1 (ZmASR1) was encoded by one of the most highly expressed paralogs. Ectopic expression of ZmASR1 had a large overall impact on maize yield that was maintained under water-limited stress conditions in the field. Comparative transcriptomic and proteomic analyses of wild-type and ZmASR1-overexpressing leaves led to the identification of three transcripts and 16 proteins up- or down-regulated by ZmASR1. The majority of them were involved in primary and/or cellular metabolic processes, including branched-chain amino acid (BCAA) biosynthesis. Metabolomic and transcript analyses further indicated that ZmASR1-overexpressing plants showed a decrease in BCAA compounds and changes in BCAA-related gene expression in comparison with wild-type plants. Interestingly, within-group correlation matrix analysis revealed a close link between 13 decreased metabolites in ZmASR1-overexpressing leaves, including two BCAAs. Among these 13 metabolites, six were previously shown to be negatively correlated to biomass, suggesting that ZmASR1-dependent regulation of these 13 metabolites might contribute to regulate leaf growth, resulting in improvement in kernel yield. PMID:21852416

  7. Sulfur in Earth's Mantle and Its Behavior During Core Formation

    NASA Technical Reports Server (NTRS)

    Chabot, Nancy L.; Righter,Kevin

    2006-01-01

    The density of Earth's outer core requires that about 5-10% of the outer core be composed of elements lighter than Fe-Ni; proposed choices for the "light element" component of Earth's core include H, C, O, Si, S, and combinations of these elements [e.g. 1]. Though samples of Earth's core are not available, mantle samples contain elemental signatures left behind from the formation of Earth's core. The abundances of siderophile (metal-loving) elements in Earth's mantle have been used to gain insight into the early accretion and differentiation history of Earth, the process by which the core and mantle formed, and the composition of the core [e.g. 2-4]. Similarly, the abundance of potential light elements in Earth's mantle could also provide constraints on Earth's evolution and core composition. The S abundance in Earth's mantle is 250 ( 50) ppm [5]. It has been suggested that 250 ppm S is too high to be due to equilibrium core formation in a high pressure, high temperature magma ocean on early Earth and that the addition of S to the mantle from the subsequent accretion of a late veneer is consequently required [6]. However, this earlier work of Li and Agee [6] did not parameterize the metalsilicate partitioning behavior of S as a function of thermodynamic variables, limiting the different pressure and temperature conditions during core formation that could be explored. Here, the question of explaining the mantle abundance of S is revisited, through parameterizing existing metal-silicate partitioning data for S and applying the parameterization to core formation in Earth.

  8. Thermal barrier and support for nuclear reactor fuel core

    DOEpatents

    Betts, Jr., William S.; Pickering, J. Larry; Black, William E.

    1987-01-01

    A thermal barrier/core support for the fuel core of a nuclear reactor having a metallic cylinder secured to the reactor vessel liner and surrounded by fibrous insulation material. A top cap is secured to the upper end of the metallic cylinder that locates and orients a cover block and post seat. Under normal operating conditions, the metallic cylinder supports the entire load exerted by its associated fuel core post. Disposed within the metallic cylinder is a column of ceramic material, the height of which is less than that of the metallic cylinder, and thus is not normally load bearing. In the event of a temperature excursion beyond the design limits of the metallic cylinder and resulting in deformation of the cylinder, the ceramic column will abut the top cap to support the fuel core post.

  9. The effect of flow limitation on the cardiorespiratory response to arousal from sleep under controlled conditions of chemostimulation in healthy older adults.

    PubMed

    Goff, Elizabeth A; Nicholas, Christian L; Kleiman, Jan; Spear, Owen; Morrell, Mary J; Trinder, John

    2012-12-01

    The influence of flow limitation on the magnitude of the cardiorespiratory response to arousal from sleep is of interest in older people, because they experience considerable flow limitation and frequent arousals from sleep. We studied older flow-limiting subjects, testing the hypothesis that the cardiorespiratory activation response would be larger when arousal occurred during flow limitation, compared to no flow limitation, and chemical stimuli were controlled. In 11 older adults [mean ± standard deviation (SD) age: 68 ± 5 years] ventilation was stabilized using continuous positive airway pressure, and flow limitation was induced by dialling down the pressure. Partial pressure of end-tidal carbon dioxide (PetCO(2)) was maintained by titration of the inspired CO(2) and hyperoxia was maintained using 40% O(2) balanced with nitrogen. Flow limitation at the time of arousal did not augment cardiovascular activation response (heart rate P = 0.7; systolic blood pressure P = 0.6; diastolic blood pressure P = 0.3), whereas ventilation was greater following arousals during flow limitation compared to no flow limitation (P < 0.001). The pre-post-arousal differences in ventilation reflected significant pre-arousal suppression (due to flow limitation) plus post-arousal activation. In summary, the cardiovascular response to arousal from sleep is not influenced by flow limitation at the time of arousal, when chemical stimuli are controlled in older adults. This finding may contribute to the decreased cardiovascular burden associated with sleep-disordered breathing reported in older adults, although our data do not exclude the possibility that flow limitation in the presence of mild hypoxic hypercapnia could increase the cardiovascular response to arousal. PMID:22906153

  10. Earth's core iron

    NASA Astrophysics Data System (ADS)

    Geophysicist J. Michael Brown of Texas A & M University noted recently at the Spring AGU Meeting in Baltimore that the structure and phase of metallic iron at pressures of the earth's inner core (approximately 3.3 Mbar) could have great significance in defining geometrical aspects of the core itself. Brown worked at the Los Alamos Scientific Laboratory with R.B. McQueen to redetermine the phase relations of metallic iron in a series of new shock-wave experiments. They found the melting point of iron at conditions equal to those at the boundary of the earth's outer (liquid) and inner (solid) cores to be 6000°±500°C (Geophysical Research Letters, 7, 533-536, 1980).

  11. Structure and behavior of the barringerite Ni end-member, Ni[subscript 2]P, at deep Earth conditions and implications for natural Fe-Ni phosphides in planetary cores

    SciTech Connect

    Dera, P.; Lavina, B.; Borkowski, L.A.; Prakapenka, V.B.; Sutton, S.R.; Rivers, M.L.; Downs, R.T.; Boctor, N.Z.; Prewitt, C.T.

    2009-06-01

    High pressure and high temperature behavior of synthetic Ni{sub 2}P has been studied in a laser-heated diamond anvil cell up to 50 GPA and 2200 K. Incongruent melting associated with formation of pyrite-type NiP{sub 2} and amorphous Ni-P alloy was found at an intermediate pressure range, between 6.5 and 40 GPa. Above GPa, Ni{sub 2}P melts congruently. At room conditions, Ni{sub 2}P has hexagonal C22-type structure, and without heating it remains in this structure to at least 50 GPa. With a bulk modulus K{sub 0} = 201(8) GPa and K' = 4.2(6), Ni{sub 2}P is noticeable less compressible than hcp Fe, as well as all previously described iron phosphides, and its presence in the Earth core would favorable lower the core density. In contrast to Fe{sub 2}P, the c/a ratio in Ni{sub 2}P decreases on compression because of the lack of ferromagnetic interaction along the c direction. Lack of the C22{yields}C23 transition in the Ni{sub 2}P rules out a stabilizing effect of Ni on the orthorhombic phase of natural (Fe{sub 1-x}Ni{sub x}){sub 2}P allabogdanite.

  12. Core-Noise

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2010-01-01

    This presentation is a technical progress report and near-term outlook for NASA-internal and NASA-sponsored external work on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system level noise metrics for the 2015, 2020, and 2025 timeframes; the emerging importance of core noise and its relevance to the SFW Reduced-Noise-Aircraft Technical Challenge; the current research activities in the core-noise area, with some additional details given about the development of a high-fidelity combustion-noise prediction capability; the need for a core-noise diagnostic capability to generate benchmark data for validation of both high-fidelity work and improved models, as well as testing of future noise-reduction technologies; relevant existing core-noise tests using real engines and auxiliary power units; and examples of possible scenarios for a future diagnostic facility. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Noise-Aircraft Technical Challenge aims to enable concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical for enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor designs could increase

  13. A DinB Ortholog Enables Mycobacterial Growth under dTTP-Limiting Conditions Induced by the Expression of a Mycobacteriophage-Derived Ribonucleotide Reductase Gene

    PubMed Central

    Ghosh, Shreya; Samaddar, Sourabh; Kirtania, Prithwiraj

    2015-01-01

    ABSTRACT Mycobacterium species such as M. smegmatis and M. tuberculosis encode at least two translesion synthesis (TLS) polymerases, DinB1 and DinB2, respectively. Although predicted to be linked to DNA repair, their role in vivo remains enigmatic. M. smegmatis mc2155, a strain commonly used to investigate mycobacterial genetics, has two copies of dinB2, the gene that codes for DinB2, by virtue of a 56-kb chromosomal duplication. Expression of a mycobacteriophage D29 gene (gene 50) encoding a class II ribonucleotide reductase in M. smegmatis ΔDRKIN, a strain derived from mc2155 in which one copy of the duplication is lost, resulted in DNA replication defects and growth inhibition. The inhibitory effect could be linked to the deficiency of dTTP that resulted under these circumstances. The selective inhibition observed in the ΔDRKIN strain was found to be due solely to a reduced dosage of dinB2 in this strain. Mycobacterium bovis, which is closely related to M. tuberculosis, the tuberculosis pathogen, was found to be highly susceptible to gene 50 overexpression. Incidentally, these slow-growing pathogens harbor one copy of dinB2. The results indicate that the induction of a dTTP-limiting state can lead to growth inhibition in mycobacteria, with the effect being maximum in cells deficient in DinB2. IMPORTANCE Mycobacterium species, such as M. tuberculosis, the tuberculosis pathogen, are known to encode several Y family DNA polymerases, one of which is DinB2, an ortholog of the DNA repair-related protein DinP of Escherichia coli. Although this protein has been biochemically characterized previously and found to be capable of translesion synthesis in vitro, its in vivo function remains unknown. Using a novel method to induce dTTP deficiency in mycobacteria, we demonstrate that DinB2 can aid mycobacterial survival under such conditions. Apart from unraveling a specific role for the mycobacterial Y family DNA polymerase DinB2 for the first time, this study also paves

  14. Transport of Recycled Deuterium to the Plasma Core in TFTR

    SciTech Connect

    Bell, M.G.; Budny, R.V.; Jassby, D.L.; Park, H.; Skinner, C.H.; et al

    1997-10-01

    We report a study of the fueling of the plasma core by recycling in the Tokamak Fusion Test Reactor (TFTR) [Phys. Plasmas 2, 2176 (1995)]. We have analyzed discharges fueled by deuterium recycled from the limiter and tritium-only neutral beam injection. In these plasmas, the DT neutron rate provides a measure of the deuterium influx into the core plasma. We find a reduced influx with plasmas using lithium pellet conditioning and with plasmas of reduced major (and minor) radius. Modeling with the DEGAS neutrals code shows that the dependence on radius can be related to the penetration of neutrals through the scrape-off layer.

  15. Transport of recycled deuterium to the plasma core in TFTR

    SciTech Connect

    Skinner, C.H.; Bell, M.G.; Budny, R.V.; Jassby, D.L.; Park, H.; Ramsey, A.T.; Stotler, D.P.; Strachan, J.D.

    1997-10-01

    The authors report a study of the fueling of the plasma core by recycling in the Tokamak Fusion Test Reactor (TFTR). They have analyzed discharges fueled by deuterium recycled from the limiter and tritium-only neutral beam injection. In these plasmas, the DT neutron rate provides a measure of the deuterium influx into the core plasma. They find a reduced influx with plasmas using lithium pellet conditioning and with plasmas of reduced major (and minor) radius. Modeling with the DEGAS neutrals code shows that the dependence on radius can be related to the penetration of neutrals through the scrape-off layer.

  16. Core Noise - Increasing Importance

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.

    2011-01-01

    This presentation is a technical summary of and outlook for NASA-internal and NASA-sponsored external research on core (combustor and turbine) noise funded by the Fundamental Aeronautics Program Subsonic Fixed Wing (SFW) Project. Sections of the presentation cover: the SFW system-level noise metrics for the 2015, 2020, and 2025 timeframes; turbofan design trends and their aeroacoustic implications; the emerging importance of core noise and its relevance to the SFW Reduced-Perceived-Noise Technical Challenge; and the current research activities in the core-noise area, with additional details given about the development of a high-fidelity combustor-noise prediction capability as well as activities supporting the development of improved reduced-order, physics-based models for combustor-noise prediction. The need for benchmark data for validation of high-fidelity and modeling work and the value of a potential future diagnostic facility for testing of core-noise-reduction concepts are indicated. The NASA Fundamental Aeronautics Program has the principal objective of overcoming today's national challenges in air transportation. The SFW Reduced-Perceived-Noise Technical Challenge aims to develop concepts and technologies to dramatically reduce the perceived aircraft noise outside of airport boundaries. This reduction of aircraft noise is critical to enabling the anticipated large increase in future air traffic. Noise generated in the jet engine core, by sources such as the compressor, combustor, and turbine, can be a significant contribution to the overall noise signature at low-power conditions, typical of approach flight. At high engine power during takeoff, jet and fan noise have traditionally dominated over core noise. However, current design trends and expected technological advances in engine-cycle design as well as noise-reduction methods are likely to reduce non-core noise even at engine-power points higher than approach. In addition, future low-emission combustor

  17. Viscosity of the earth's core.

    NASA Technical Reports Server (NTRS)

    Gans, R. F.

    1972-01-01

    Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

  18. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of Soybean (Glycine max) at elevated [CO2] and temperatures under fully open air field conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on 1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the ma...

  19. The bidirectional NiFe-hydrogenase in Synechocystis sp. PCC 6803 is reduced by flavodoxin and ferredoxin and is essential under mixotrophic, nitrate-limiting conditions.

    PubMed

    Gutekunst, Kirstin; Chen, Xi; Schreiber, Karoline; Kaspar, Ursula; Makam, Srinivas; Appel, Jens

    2014-01-24

    Cyanobacteria are able to use solar energy for the production of hydrogen. It is generally accepted that cyanobacterial NiFe-hydrogenases are reduced by NAD(P)H. This is in conflict with thermodynamic considerations, as the midpoint potentials of NAD(P)H do not suffice to support the measured hydrogen production under physiological conditions. We show that flavodoxin and ferredoxin directly reduce the bidirectional NiFe-hydrogenase of Synechocystis sp. PCC 6803 in vitro. A merodiploid ferredoxin-NADP reductase mutant produced correspondingly more photohydrogen. We furthermore found that the hydrogenase receives its electrons via pyruvate:flavodoxin/ferredoxin oxidoreductase (PFOR)-flavodoxin/ferredoxin under fermentative conditions, enabling the cells to gain ATP. These results strongly support that the bidirectional NiFe-hydrogenases in cyanobacteria function as electron sinks for low potential electrons from photosystem I and as a redox balancing device under fermentative conditions. However, the selective advantage of this enzyme is not known. No strong phenotype of mutants lacking the hydrogenase has been found. Because bidirectional hydrogenases are widespread in aquatic nutrient-rich environments that are capable of triggering phytoplankton blooms, we mimicked those conditions by growing cells in the presence of increased amounts of dissolved organic carbon and dissolved organic nitrogen. Under these conditions the hydrogenase was found to be essential. As these conditions close the two most important sinks for reduced flavodoxin/ferredoxin (CO2-fixation and nitrate reduction), this discovery further substantiates the connection between flavodoxin/ferredoxin and the NiFe-hydrogenase. PMID:24311779

  20. Core formation by giant impacts

    NASA Technical Reports Server (NTRS)

    Tonks, W. B.; Melosh, H. J.

    1991-01-01

    Ideas about the accretion and early evolution of the Earth and the other terrestrial planets have recently undergone a number of revolutionary changes. It has become clear that giant impacts were far from rare events. In the later stages of accretion any given planetary embryo is liable to be struck several times by other bodies of up to half its own diameter. Such an impact may have the ability to trigger core formation. Traditional accretion models have had great difficulty explaining the formation of the core. If one admits the importance of infrequent large events that may melt an entire hemisphere, the core formation difficulty vanishes. Millimeter-size iron blebs in the melted region will rain out due to their density difference with the silicate melt. Core formation may not require the melting of the entire hemisphere of the planet. The conditions are explored under which impact induced core formation may occur.

  1. FLAVODIIRON2 and FLAVODIIRON4 proteins mediate an oxygen-dependent alternative electron flow in Synechocystis sp. PCC 6803 under CO2-limited conditions.

    PubMed

    Shimakawa, Ginga; Shaku, Keiichiro; Nishi, Akiko; Hayashi, Ryosuke; Yamamoto, Hiroshi; Sakamoto, Katsuhiko; Makino, Amane; Miyake, Chikahiro

    2015-02-01

    This study aims to elucidate the molecular mechanism of an alternative electron flow (AEF) functioning under suppressed (CO2-limited) photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803. Photosynthetic linear electron flow, evaluated as the quantum yield of photosystem II [Y(II)], reaches a maximum shortly after the onset of actinic illumination. Thereafter, Y(II) transiently decreases concomitantly with a decrease in the photosynthetic oxygen evolution rate and then recovers to a rate that is close to the initial maximum. These results show that CO2 limitation suppresses photosynthesis and induces AEF. In contrast to the wild type, Synechocystis sp. PCC 6803 mutants deficient in the genes encoding FLAVODIIRON2 (FLV2) and FLV4 proteins show no recovery of Y(II) after prolonged illumination. However, Synechocystis sp. PCC 6803 mutants deficient in genes encoding proteins functioning in photorespiration show AEF activity similar to the wild type. In contrast to Synechocystis sp. PCC 6803, the cyanobacterium Synechococcus elongatus PCC 7942 has no FLV proteins with high homology to FLV2 and FLV4 in Synechocystis sp. PCC 6803. This lack of FLV2/4 may explain why AEF is not induced under CO2-limited photosynthesis in S. elongatus PCC 7942. As the glutathione S-transferase fusion protein overexpressed in Escherichia coli exhibits NADH-dependent oxygen reduction to water, we suggest that FLV2 and FLV4 mediate oxygen-dependent AEF in Synechocystis sp. PCC 6803 when electron acceptors such as CO2 are not available. PMID:25540330

  2. Biochemical acclimation, stomatal limitation and precipitation patterns underlie decreases in photosynthetic stimulation of soybean (Glycine max) at elevated [CO₂] and temperatures under fully open air field conditions.

    PubMed

    Rosenthal, David M; Ruiz-Vera, Ursula M; Siebers, Matthew H; Gray, Sharon B; Bernacchi, Carl J; Ort, Donald R

    2014-09-01

    The net effect of elevated [CO2] and temperature on photosynthetic acclimation and plant productivity is poorly resolved. We assessed the effects of canopy warming and fully open air [CO2] enrichment on (1) the acclimation of two biochemical parameters that frequently limit photosynthesis (A), the maximum carboxylation capacity of Rubisco (Vc,max) and the maximum potential linear electron flux through photosystem II (Jmax), (2) the associated responses of leaf structural and chemical properties related to A, as well as (3) the stomatal limitation (l) imposed on A, for soybean over two growing seasons in a conventionally managed agricultural field in Illinois, USA. Acclimation to elevated [CO2] was consistent over two growing seasons with respect to Vc,max and Jmax. However, elevated temperature significantly decreased Jmax contributing to lower photosynthetic stimulation by elevated CO2. Large seasonal differences in precipitation altered soil moisture availability modulating the complex effects of elevated temperature and CO2 on biochemical and structural properties related to A. Elevated temperature also reduced the benefit of elevated [CO2] by eliminating decreases in stomatal limitation at elevated [CO2]. These results highlight the critical importance of considering multiple environmental factors (i.e. temperature, moisture, [CO2]) when trying to predict plant productivity in the context of climate change. PMID:25113459

  3. 41 CFR 102-36.180 - Is there any limitation/condition to acquiring excess personal property for use by cooperatives?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    .../condition to acquiring excess personal property for use by cooperatives? 102-36.180 Section 102-36.180...) FEDERAL MANAGEMENT REGULATION PERSONAL PROPERTY 36-DISPOSITION OF EXCESS PERSONAL PROPERTY Acquiring Excess Personal Property for Non-Federal Recipients Cooperatives § 102-36.180 Is there any...

  4. Yield determination and water-use effenciency of wheat under water-limited conditions in the U.S. southern high plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought is the most important stress for reducing wheat (Triticum aestivum L.) yield and water-use efficiency (WUE) on the U.S. Southern High Plains. Adoption of cultivars with higher yield and WUE under drought conditions is critical in the area. The objective of this study was to investigate the p...

  5. Why Do Only Some Galaxy Clusters Have Cool Cores?

    NASA Astrophysics Data System (ADS)

    Burns, Jack O.; Hallman, Eric J.; Gantner, Brennan; Motl, Patrick M.; Norman, Michael L.

    2008-03-01

    Flux-limited X-ray samples indicate that about half of rich galaxy clusters have cool cores. Why do only some clusters have cool cores while others do not? In this paper, cosmological N-body + Eulerian hydrodynamic simulations, including radiative cooling and heating, are used to address this question as we examine the formation and evolution of cool core (CC) and noncool core (NCC) clusters. These adaptive mesh refinement simulations produce both CC and NCC clusters in the same volume. They have a peak resolution of 15.6 h-1 kpc within a (256 h-1 Mpc)3 box. Our simulations suggest that there are important evolutionary differences between CC clusters and their NCC counterparts. Many of the numerical CC clusters accreted mass more slowly over time and grew enhanced CCs via hierarchical mergers; when late major mergers occurred, the CCs survived the collisions. By contrast, NCC clusters experienced major mergers early in their evolution that destroyed embryonic CCs and produced conditions that prevented CC reformation. As a result, our simulations predict observationally testable distinctions in the properties of CC and NCC beyond the core regions in clusters. In particular, we find differences between CC versus NCC clusters in the shapes of X-ray surface brightness profiles, between the temperatures and hardness ratios beyond the cores, between the distribution of masses, and between their supercluster environs. It also appears that CC clusters are no closer to hydrostatic equilibrium than NCC clusters, an issue important for precision cosmology measurements.

  6. Gas core reactors for actinide transmutation and breeder applications

    NASA Technical Reports Server (NTRS)

    Clement, J. D.; Rust, J. H.

    1978-01-01

    This work consists of design power plant studies for four types of reactor systems: uranium plasma core breeder, uranium plasma core actinide transmuter, UF6 breeder and UF6 actinide transmuter. The plasma core systems can be coupled to MHD generators to obtain high efficiency electrical power generation. A 1074 MWt UF6 breeder reactor was designed with a breeding ratio of 1.002 to guard against diversion of fuel. Using molten salt technology and a superheated steam cycle, an efficiency of 39.2% was obtained for the plant and the U233 inventory in the core and heat exchangers was limited to 105 Kg. It was found that the UF6 reactor can produce high fluxes (10 to the 14th power n/sq cm-sec) necessary for efficient burnup of actinide. However, the buildup of fissile isotopes posed severe heat transfer problems. Therefore, the flux in the actinide region must be decreased with time. Consequently, only beginning-of-life conditions were considered for the power plant design. A 577 MWt UF6 actinide transmutation reactor power plant was designed to operate with 39.3% efficiency and 102 Kg of U233 in the core and heat exchanger for beginning-of-life conditions.

  7. The phytopathogen Pseudomonas syringae pv. tomato DC3000 has three high-affinity iron-scavenging systems functional under iron limitation conditions but dispensable for pathogenesis.

    PubMed

    Jones, Alexander M; Wildermuth, Mary C

    2011-06-01

    High-affinity iron scavenging through the use of siderophores is a well-established virulence determinant in mammalian pathogenesis. However, few examples have been reported for plant pathogens. Here, we use a genetic approach to investigate the role of siderophores in Pseudomonas syringae pv. tomato DC3000 (DC3000) virulence in tomato. DC3000, an agronomically important pathogen, has two known siderophores for high-affinity iron scavenging, yersiniabactin and pyoverdin, and we uncover a third siderophore, citrate, required for growth when iron is limiting. Though growth of a DC3000 triple mutant unable to either synthesize or import these siderophores is severely restricted in iron-limited culture, it is fully pathogenic. One explanation for this phenotype is that the DC3000 triple mutant is able to directly pirate plant iron compounds such as heme/hemin or iron-nicotianamine, and our data indicate that DC3000 can import iron-nicotianamine with high affinity. However, an alternative explanation, supported by data from others, is that the pathogenic environment of DC3000 (i.e., leaf apoplast) is not iron limited but is iron replete, with available iron of >1 μM. Growth of the triple mutant in culture is restored to wild-type levels by supplementation with a variety of iron chelates at >1 μM, including iron(III) dicitrate, a dominant chelate of the leaf apoplast. This suggests that lower-affinity iron import would be sufficient for DC3000 iron nutrition in planta and is in sharp contrast to the high-affinity iron-scavenging mechanisms required in mammalian pathogenesis. PMID:21441525

  8. Sustained enhancement of photosynthesis in coffee trees grown under free-air CO2 enrichment conditions: disentangling the contributions of stomatal, mesophyll, and biochemical limitations.

    PubMed

    DaMatta, Fábio M; Godoy, Alice G; Menezes-Silva, Paulo E; Martins, Samuel C V; Sanglard, Lílian M V P; Morais, Leandro E; Torre-Neto, André; Ghini, Raquel

    2016-01-01

    Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuaí and Obatã) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest. PMID:26503540

  9. Sustained enhancement of photosynthesis in coffee trees grown under free-air CO2 enrichment conditions: disentangling the contributions of stomatal, mesophyll, and biochemical limitations

    PubMed Central

    DaMatta, Fábio M.; Godoy, Alice G.; Menezes-Silva, Paulo E.; Martins, Samuel C.V.; Sanglard, Lílian M.V.P.; Morais, Leandro E.; Torre-Neto, André; Ghini, Raquel

    2016-01-01

    Coffee (Coffea spp.), a globally traded commodity, is a slow-growing tropical tree species that displays an improved photosynthetic performance when grown under elevated atmospheric CO2 concentrations ([CO2]). To investigate the mechanisms underlying this response, two commercial coffee cultivars (Catuaí and Obatã) were grown using the first free-air CO2 enrichment (FACE) facility in Latin America. Measurements were conducted in two contrasting growth seasons, which were characterized by the high (February) and low (August) sink demand. Elevated [CO2] led to increases in net photosynthetic rates (A) in parallel with decreased photorespiration rates, with no photochemical limitations to A. The stimulation of A by elevated CO2 supply was more prominent in August (56% on average) than in February (40% on average). Overall, the stomatal and mesophyll conductances, as well as the leaf nitrogen and phosphorus concentrations, were unresponsive to the treatments. Photosynthesis was strongly limited by diffusional constraints, particularly at the stomata level, and this pattern was little, if at all, affected by elevated [CO2]. Relative to February, starch pools (but not soluble sugars) increased remarkably (>500%) in August, with no detectable alteration in the maximum carboxylation capacity estimated on a chloroplast [CO2] basis. Upregulation of A by elevated [CO2] took place with no signs of photosynthetic downregulation, even during the period of low sink demand, when acclimation would be expected to be greatest. PMID:26503540

  10. Adjusting the light in the limit conditions of consciousness by the means of ascending reticular activating system (ARAS) and of subordinated systems

    PubMed Central

    Aliu, Octavian Florin

    2014-01-01

    Background: In our activity in the Ambulance Service of Bucharest Municipality during March 2002 – March 2003 we studied a casuistry of patients who had fallen in a coma of varying degrees. To aid better understanding of coma, the concept of “pre-coma stage” or “diencephalic 0 stage” was introduced. This concept complements the Arseni classification already used in medical practice, because some doctors alternatively use the term of “inaugural coma” for the same condition that we call diencephalic “0 stage”. In the median hypothalamus and on the retino-hypothalamic path (SCN - AN) optical waves are transmitted, probably in the near infrared spectral range (800–1000 nm) in what we term the ascending reticular activating system (ARAS). These waves would constitute a means of transmitting information via the ARAS about the infradian biorhythm of coordination (frequencies below 1 cycle/28 hours), essential for the modulation and pre-processing of the consciousness and wakefulness, a fact which has already been demonstrated in animals. Methods: The current work is based on observations made on a group of 51 patients with the precoma and coma conditions, and on a thorough study of the specialized (especially Romanian) literature. Also, we used validated scientific proof of torture in conditions of lack of light. Results: We found a perfect interpenetration between the ARAS and the following two complementary subsystems: 1. The hypothalamic suprachiasmatic nucleus, that has the role of coordinating the periodicity of some biological functions depending on the circadian rhythm; and 2. The main photoperiodic organ, the pineal gland (epiphysis), which together with the ARAS has a role in the photoperiodicity modulation of some biological functions during the state of vigilance. PMID:25071308

  11. CONTROL LIMITER DEVICE

    DOEpatents

    DeShong, J.A.

    1960-03-01

    A control-limiting device for monltoring a control system is described. The system comprises a conditionsensing device, a condition-varying device exerting a control over the condition, and a control means to actuate the condition-varying device. A control-limiting device integrates the total movement or other change of the condition-varying device over any interval of time during a continuum of overlapping periods of time, and if the tothl movement or change of the condition-varying device exceeds a preset value, the control- limiting device will switch the control of the operated apparatus from automatic to manual control.

  12. Phosphate Homeostasis in Conditions of Phosphate Proficiency and Limitation in the Wild Type and the phoP Mutant of Streptomyces lividans

    PubMed Central

    Prigent, Magali; Holland, Ian Barry; Virolle, Marie-Joelle

    2015-01-01

    Phosphate, as a constituent of the high energy molecules, ATP/GTP and polyphosphate, plays a crucial role in most of the metabolic processes of living organisms. Therefore, the adaptation to low Pi availability is a major challenge for bacteria. In Streptomyces, this adaptation is tightly controlled by the two component PhoR/PhoP system. In this study, the free intracellular Pi, ATP, ADP and polyP content of the wild type and the phoP mutant strain of S. lividans TK24 were analyzed at discrete time points throughout growth in Pi replete and limited media. PolyP length and content was shown to be directly related to the Pi content of the growth medium. In Pi repletion, ATP and high molecular weight (HMW) polyP contents were higher in the phoP mutant than in the WT strain. This supports the recently proposed repressive effect of PhoP on oxidative phosphorylation. High oxidative phosphorylation activity might also have a direct or indirect positive impact on HMW polyP synthesis. In Pi sufficiency as in Pi limitation, the degradation of these polymers was shown to be clearly delayed in the phoP mutant, indicating PhoP dependent expression of the enzymes involved in this degradation. The efficient storage of Pi as polyphosphate and/or its inefficient degradation in Pi in the phoP mutant resulted in low levels of free Pi and ATP that are likely to be, at least in part, responsible for the very poor growth of this mutant in Pi limitation. Furthermore, short polyP was shown to be present outside the cell, tightly bound to the mycelium via electrostatic interactions involving divalent cations. Less short polyP was found to be associated with the mycelium of the phoP mutant than with that of the WT strain, indicating that generation and externalization of these short polyP molecules was directly or indirectly dependent on PhoP. PMID:25978423

  13. Adjusting the light in the limit conditions of consciousness by the means of ascending reticular activating system (ARAS*) and of subordinated systems Part 1: Introduction and Aims

    PubMed Central

    Siposan, Dan Georgel; Aliu, Octavian Florin

    2014-01-01

    Background: In our activity in the Ambulance Service of Bucharest Municipality during March 2002 – March 2003 we studied a casuistry of patients who had fallen in a coma of varying degrees. To aid better understanding of coma, the concept of “pre-coma stage” or diencephalic “0 stage” was introduced. This concept complements the Arseni classification already used in medical practice, because some doctors alternatively use the term of “inaugural coma” for the same condition that we call diencephalic “0 stage”. In the median hypothalamus and on the retino-hypothalamic path (SCN - AN) optical waves are transmitted, probably in the near infrared spectral range (800–1000 nm). These waves would constitute a means of transmitting information about the infradian biorhythm of coordination (frequencies below 1 cycle/28 hours), essential for the modulation and pre-processing of the consciousness and wakefulness, a fact which has already been demonstrated in animals. Methods: The current work is based on observations made on a group of 51 patients with the precoma and coma conditions, and on a thorough study of the specialized (especially Romanian) literature. Also, we used validated scientific proof of torture in conditions of lack of light. Results: We found a perfect interpenetration between the ARAS and the following two complementary subsystems: 1. The hypothalamic suprachiasmatic nucleus, that has the role of coordinating the periodicity of some biological functions depending on the circadian rhythm; and 2. The main photoperiodic organ, the pineal gland (epiphysis), which together with the ARAS has a role in the photoperiodicity modulation of some biological functions during the state of vigilance. Conclusion: From the above mentioned one may conclude that the consciousness condition is the unitary result of action of all human brain systems and especially sub-systems, which are controlled and led by a psycho-neurological process of integration at the

  14. Analysis of imidacloprid and pyrimethanil in shallot (Allium ascalonicum) grown under greenhouse conditions using tandem mass spectrometry: establishment of pre-harvest residue limits.

    PubMed

    Park, Jong-Hyouk; Park, Joon-Seong; Abd El-Aty, A M; Rahman, Md Musfiqur; Na, Tae-Woong; Shim, Jae-Han

    2013-04-01

    In this study, the original Quick, Easy, Cheap, Effective, Rugged and Safe method was used for the extraction of imidacloprid and pyrimethanil followed by a rapid clean-up through dispersive solid-phase extraction technique with primary secondary amine sorbent and magnesium sulfate in shallot. Residues were analyzed using LC-tandem mass spectrometry in positive-ion electrospray ionization mode. The limits of detection and quantification were estimated to be 0.006 and 0.02 mg/kg, respectively. The samples were fortified at two different concentration levels (0.2 and 1.0 mg/kg), and the recoveries ranged between 79.7 and 83.9% with relative standard deviation values < 6%. The method was successfully applied for the establishment of the pre-harvest residue limits (PHRL). The rate of disappearance of imidacloprid and pyrimethanil on shallot was described with first-order kinetics (imidacloprid, y(2)  = 0.9670; pyrimethanil, y(2)  = 0.9841), with half-lives of 2.87 and 2.08 days, respectively. Based on the dissipation patterns of the pesticide residues, the PHRL was recommended at 7.86 mg/kg for 14 days (PHRL14 ) and 1.98 mg/kg for 7 days (PHRL7 ) before harvest for imidacloprid, and 21.64 mg/kg for 7 days (PHRL7 ) and 9.28 mg/kg for 4 days (PHRL4 ) before harvest for pyrimethanil in shallot. PMID:22949075

  15. The role of iron in Mycobacterium smegmatis biofilm formation: the exochelin siderophore is essential in limiting iron conditions for biofilm formation but not for planktonic growth

    PubMed Central

    Ojha, Anil; Hatfull, Graham F

    2007-01-01

    Many species of mycobacteria form structured biofilm communities at liquid–air interfaces and on solid surfaces. Full development of Mycobacterium smegmatis biofilms requires addition of supplemental iron above 1 μM ferrous sulphate, although addition of iron is not needed for planktonic growth. Microarray analysis of the M. smegmatis transcriptome shows that iron-responsive genes – especially those involved in siderophore synthesis and iron uptake – are strongly induced during biofilm formation reflecting a response to iron deprivation, even when 2 μM iron is present. The acquisition of iron under these conditions is specifically dependent on the exochelin synthesis and uptake pathways, and the strong defect of an iron–exochelin uptake mutant suggests a regulatory role of iron in the transition to biofilm growth. In contrast, although the expression of mycobactin and iron ABC transport operons is highly upregulated during biofilm formation, mutants in these systems form normal biofilms in low-iron (2 μM) conditions. A close correlation between iron availability and matrix-associated fatty acids implies a possible metabolic role in the late stages of biofilm maturation, in addition to the early regulatory role. M. smegmatis surface motility is similarly dependent on iron availability, requiring both supplemental iron and the exochelin pathway to acquire it. PMID:17854402

  16. Environmental information from ice cores

    SciTech Connect

    Delmas, R.J. )

    1992-02-01

    Information from snow and ice core studies which is useful for documenting the interplay between the climate and the chemistry of the natural atmosphere is reviewed. Particular attention is given to the formation and interpretation of the ice records for the present conditions and the data obtained from the analysis of the Vostok ice core. It is concluded that the deep ice core data provide precise information on the ice-age environmental conditions. When polar temperatures were approximately 10 C lower than now, atmospheric CO2 and CH4 contents were factors of 2 and 4 lower, respectively, than the present conditions. At this time, sea salt and overall crustal dust depositions were significantly higher. According to modifications in source intensity and transport of gaseous precursors the biogeochemical cycles of S and N were also disturbed. 91 refs.

  17. Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and H2-enriched conditions: implications for the origin of methane and its isotopic diagnosis

    NASA Astrophysics Data System (ADS)

    Okumura, Tomoyo; Kawagucci, Shinsuke; Saito, Yayoi; Matsui, Yohei; Takai, Ken; Imachi, Hiroyuki

    2016-12-01

    Hydrogen and carbon isotope systematics of H2O-H2-CO2-CH4 in hydrogenotrophic methanogenesis and their relation to H2 availability were investigated. Two H2-syntrophic cocultures of fermentatively hydrogenogenic bacteria and hydrogenotrophic methanogens under conditions of <102 Pa-H2 and two pure cultures of hydrogenotrophic methanogens under conditions of 105 Pa-H2 were tested. Carbon isotope fractionation between CH4 and CO2 during hydrogenotrophic methanogenesis was correlated with pH2, as indicated in previous studies. The hydrogen isotope ratio of CH4 produced during rapid growth of the thermophilic methanogen Methanothermococcus okinawensis under high pH2 conditions ( 105 Pa) was affected by the isotopic composition of H2, as concluded in a previous study of Methanothermobacter thermautotrophicus. This " {δ D}_{{H}_2} effect" is a possible cause of the diversity of previously reported values for hydrogen isotope fractionation between CH4 and H2O examined in H2-enriched culture experiments. Hydrogen isotope fractionation between CH4 and H2O, defined by (1000 + {δ D}_{{CH}_4} )/(1000 + {δ D}_{{H}_2O} ), during hydrogenotrophic methanogenesis of the H2-syntrophic cocultures was in the range 0.67-0.69. The hydrogen isotope fractionation of our H2-syntrophic dataset overlaps with those obtained not only from low- pH2 experiments reported so far but also from natural samples of "young" methane reservoirs (0.66-0.74). Conversely, such hydrogen isotope fractionation is not consistent with that of "aged" methane in geological samples (≥0.79), which has been regarded as methane produced via hydrogenotrophic methanogenesis from the carbon isotope fractionation. As a possible process inducing the inconsistency in hydrogen isotope signatures between experiments and geological samples, we hypothesize that the hydrogen isotope signature of CH4 imprinted at the time of methanogenesis, as in the experiments and natural young methane, may be altered by diagenetic hydrogen

  18. Feldspathic granulite 79215 - Limitations on T-fo2 conditions and time of metamorphism. [temperature-oxygen fugacity relationship in annealed lunar polymict beccia

    NASA Technical Reports Server (NTRS)

    Mcgee, J. J.; Bence, A. E.; Eichhorn, G.; Schaeffer, O. A.

    1978-01-01

    Feldspathic granulite 79215, an annealed polymict breccia which has a bulk composition between anorthositic gabbro and gabbroic anorthosite, contains numerous oxide complexes in the matrix. An Ar-39-Ar-40 stepwise heating experiment gives a well-defined plateau corresponding to an age of 4.03 + or - 0.02 AE. The polmict character of this breccia and the variability of the complexes suggest that they formed as a consequence of reactions between spinel-rich clasts and matrix under the high-T low-P conditions of an ejecta blanket. The duration of annealing is estimated to have been less than 10 million yr; the absence of a KREEP component may indicate an inhomogeneous distribution of this component at the lunar surface at 4.0 AE.

  19. Glass-clad semiconductor core optical fibers

    NASA Astrophysics Data System (ADS)

    Morris, Stephanie Lynn

    Glass-clad optical fibers comprising a crystalline semiconductor core have garnered considerable recent attention for their potential utility as novel waveguides for applications in nonlinear optics, sensing, power delivery, and biomedicine. As research into these fibers has progressed, it has become evident that excessive losses are limiting performance and so greater understanding of the underlying materials science, coupled with advances in fiber processing, is needed. More specifically, the semiconductor core fibers possess three performance-limiting characteristics that need to be addressed: (a) thermal expansion mismatches between crystalline core and glass cladding that lead to cracks, (b) the precipitation of oxide species in the core upon fiber cooling, which results from partial dissolution of the cladding glass by the core melt, and (c) polycrystallinity; all of which lead to scattering and increased transmission losses. This dissertation systematically studies each of these effects and develops both a fundamental scientific understanding of and practical engineering methods for reducing their impact. With respect to the thermal expansion mismatch and, in part, the dissolution of oxides, for the first time to our knowledge, oxide and non-oxide glass compositions are developed for a series of semiconductor cores based on two main design criteria: (1) matching the thermal expansion coefficient between semiconductor core and glass cladding to minimize cracking and (2) matching the viscosity-temperature dependences, such that the cladding glass draws into fiber at a temperature slightly above the melting point of the semiconductor in order to minimize dissolution and improve the fiber draw process. The x[Na 2O:Al2O3] + (100 - 2x)SiO2 glass compositional family was selected due to the ability to tailor the glass properties to match the aforementioned targets through slight variations in composition and adjusting the ratios of bridging and non-bridging oxygen

  20. Dual-core antiresonant hollow core fibers.

    PubMed

    Liu, Xuesong; Fan, Zhongwei; Shi, Zhaohui; Ma, Yunfeng; Yu, Jin; Zhang, Jing

    2016-07-25

    In this work, dual-core antiresonant hollow core fibers (AR-HCFs) are numerically demonstrated, based on our knowledge, for the first time. Two fiber structures are proposed. One is a composite of two single-core nested nodeless AR-HCFs, exhibiting low confinement loss and a circular mode profile in each core. The other has a relatively simple structure, with a whole elliptical outer jacket, presenting a uniform and wide transmission band. The modal couplings of the dual-core AR-HCFs rely on a unique mechanism that transfers power through the air. The core separation and the gap between the two cores influence the modal coupling strength. With proper designs, both of the dual-core fibers can have low phase birefringence and short modal coupling lengths of several centimeters. PMID:27464191