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Sample records for 44ca 90zr pri

  1. Producing a compound Nucleus via Inelastic Scattering: The 90Zr(alpha,alpha')90Zr* Case

    SciTech Connect

    Escher, J E; Dietrich, F S

    2008-05-23

    In a Surrogate reaction a compound nucleus is produced via a direct reaction (pickup, stripping, or inelastic scattering). For a proper application of the Surrogate approach it is necessary to predict the resulting angular momentum and parity distribution in the compound nucleus. A model for determining these distributions is developed for the case of inelastic alpha scattering off a spherical nucleus. The focus is on obtaining a first, simple description of the direct-reaction process that produces the compound nucleus and on providing the basis for a more complete treatment of the problem. The approximations employed in the present description are discussed and the extensions required for a more rigorous treatment of the problem are outlined. To illustrate the formalism, an application to {sup 90}Zr({alpha},{alpha}{prime}){sup 90}Zr* is presented.

  2. Radiative strength functions for dipole transitions in {sup 90}Zr

    SciTech Connect

    Fedorets, I. D. Ratkevich, S. S.

    2013-01-15

    Partial cross sections for the (p, {gamma}) reaction on the {sup 89}Y nucleus that were measured previously at proton energies between 2.17 and 5.00 MeV and which were averaged over resonances were used to determine the absolute values and the energy distribution of the strength of dipole transitions from compound-nucleus states to low-lying levels of the {sup 90}Zr nucleus. The data obtained in this way were compared with the predictions of various models.

  3. Pygmy dipole resonance and dipole polarizability in {sup 90}Zr

    SciTech Connect

    Iwamoto, C.; Tamii, A.; Shima, T.; Hashimoto, T.; Suzuki, T.; Fujita, H.; Hatanaka, K.; Utsunomiya, H.; Akimune, H.; Yamagata, T.; Okamoto, A.; Kondo, T.; Nakada, H.; Kawabata, T.; Fujita, Y.; Matsubara, H.; Shimbara, Y.; Nagashima, M.; Sakuda, M.; Mori, T.; and others

    2014-05-02

    Electric dipole (E1) reduced transition probability B(E1) of {sup 90}Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability α{sub D} which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.

  4. Coulomb excitation of 44Ca and 46Ar

    NASA Astrophysics Data System (ADS)

    Calinescu, S.; Cáceres, L.; Grévy, S.; Sorlin, O.; Dombrádi, Z.; Stanoiu, M.; Astabatyan, R.; Borcea, C.; Borcea, R.; Bowry, M.; Catford, W.; Clément, E.; Franchoo, S.; Garcia, R.; Gillibert, R.; Guerin, I. H.; Kuti, I.; Lukyanov, S.; Lepailleur, A.; Maslov, V.; Morfouace, P.; Mrazek, J.; Negoita, F.; Niikura, M.; Perrot, L.; Podolyák, Z.; Petrone, C.; Penionzhkevich, Y.; Roger, T.; Rotaru, F.; Sohler, D.; Stefan, I.; Thomas, J. C.; Vajta, Z.; Wilson, E.

    2016-04-01

    The reduced transition probabilities B (E 2 ;0g.s . +→21+) of the 46Ar and 44Ca nuclei were studied using the Coulomb excitation technique at intermediate energy at the LISE/GANIL facility. The in-flight γ rays, emitted after the Coulomb excitation of their first 2+ states, were detected in an array of 64 BaF2 crystals. The present B(E 2 ↑ ) value for 44Ca, 475(36) e2fm4 , agrees well with the value of 495(35) e2fm4 obtained by averaging results of previous experiments. Consistent B (E 2 ;0g.s . +→21+) values of 225(29) e2fm4 and 234(19) e2fm4 have been obtained for 46Ar from an absolute and a relative measurement, normalized to the 44Ca value. Both results agree with the ones obtained with the same experimental technique at the NSCL facility but are a factor of 2 smaller than the shell model predictions. The drop in B (E 2 ;0g.s . +→21+) in the Ar chain at N =28 , confirmed in this experiment, shows that 46Ar is sensitive to the N =28 shell closure.

  5. The Isoscalar Giant Dipole Resonance in {sup 20}Pb, {sup 90}Zr and the Nuclear Compressibility

    SciTech Connect

    Yildirim, Serbulent; Koeroglu, Ulas

    2008-11-11

    The isoscalar giant dipol resonance (ISGDR) in finite nuclei is studied within the framework of a relativistic transport approach. The excitation energies of spherical {sup 90}Zr and {sup 208}Pb nuclei are obtained for different quantum hydrodynamical Lagrangian parametrization. The sensitivity of ISGDR excitation energy on the nuclear bulk to surface properties are also investigated.

  6. Spin differences in the 90Zr compound nucleus induced by (p ,p') , (p ,d ) , and (p ,t ) surrogate reactions

    NASA Astrophysics Data System (ADS)

    Ota, S.; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I. J.; Austin, R. A. E.; Abromeit, B.; Foley, N. J.; McCleskey, E.; McCleskey, M.; Park, H. I.; Saastamoinen, A.; Ross, T. J.

    2015-11-01

    The effect of the production mechanism on the decay of a compound nucleus is investigated. The nucleus 90Zr was produced by three different reactions, namely 90Zr(p ,p') 90Zr , 91Zr(p ,d ) 90Zr , and 92Zr(p ,t ) 90Zr , which served as surrogate reactions for 89Zr(n ,γ ) . The spin-parity (Jπ) distributions of the states populated by these reactions were studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as 89Zr . Discrete γ rays, associated with transitions in 90Zr and 89Zr , were measured in coincidence with light ions for scattering angles of 25∘-60∘ and 90Zr excitation energies extending above the neutron separation energy. The measured transition systematics were used to gain insights into the Jπ distributions of 90Zr . The 90Zr(p ,p') reaction was found to produce fewer γ rays associated with transitions involving high spin states (J =6 -8 ℏ ) than the other two reactions, suggesting that inelastic scattering preferentially populates states in 90Zr that have lower spins than those populated in the transfer reactions investigated. The γ -ray production was also observed to vary by factors of 2-3 with the angle at which the outgoing particle was detected. These findings are relevant to the application of the surrogate reaction approach.

  7. Reanalysis of muonic {sup 90}Zr and {sup 208}Pb atoms

    SciTech Connect

    Haga, Akihiro; Toki, Hiroshi; Horikawa, Yataro

    2007-04-15

    Muonic transition energies in lowlying {mu}{sup -}-{sup 90}Zr and {mu}{sup -}-{sup 208}Pb states are reanalyzed by using nuclear polarization with the full-electromagnetic nuclear response. The possibility of the observed enhancement of the energy-weighted sum rule is also considered in the analysis. The transverse part of the nuclear polarization and the enhancement effect play an important role in improving the fine structure splitting of muonic p-states in both nuclei. Furthermore, introducing a pygmy dipole resonance in the excitation spectrum, the final fit drastically improves in {sup 208}Pb. However, there remains a discrepancy in {sup 90}Zr, for which the structure of the nuclear excitation spectrum is insensitive to the nuclear-polarization energy shift. Therefore, the remaining discrepancy might be caused by effects other than the nuclear polarization.

  8. Striking behavior of photoneutron cross sections for {sup 90}Zr near threshold

    SciTech Connect

    Utsunomiya, H.; Akimune, H.; Yamagata, T.; Kondo, T.; Iwamoto, C.; Itoh, O.; Kamata, M.; Io, M.; Kususe, K.; Teramoto, T.; Goriely, S.; Harada, H.; Kitatani, F.; Goko, S.; Toyokawa, H.; Yamada, K.; Lui, Y.-W.

    2011-10-28

    Photoneutron cross sections for {sup 90}Zr near neutron threshold were examined with a photon difference technique using laser Compton scattering {gamma}-ray beams. The cross section decreasing in the vicinity of neutron threshold exhibited a steep rise within 150 keV above the threshold. We draw attention to a possible relation of this striking behavior to the 3P valence neutron resonance known in neutron capture in the mass region A{approx_equal}90.

  9. Exploring the spin states of 90Zr populated by (p,p'), (p,d), and (p,t) reactions

    NASA Astrophysics Data System (ADS)

    Ota, S.; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I. J.; Austin, R. A. E.; Abromeit, B.; Foley, N. J.; McCleskey, E.; McCleskey, M.; Park, H. I.; Saastamoinen, A.; Ross, T. J.

    2016-06-01

    The 90Zr nucleus was produced by three different reactions: 90Zr(p,p'), 91Zr(p,d), and 92Zr(p,t), and the spin-parity (Jπ) population of the 90Zr states produced by these reactions was studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as 89Zr(n,γ). Discrete γ-rays, associated with the de-excitation of 90Zr and 89Zr, were measured in coincidence with light ions at 90Zr excitation energies extending above the neutron separation energy. Low-lying states populated by (p,d) and (p,t) reactions agreed well with the previous measurements. The measured γ transition systematics were used to gain insights into the Jπ distribution of 90Zr around the neutron separation energy and it was found that the (p,p') reaction preferentially produces lower J states than (p,d) and (p,t) reactions in the studied energy region.

  10. Mössbauer study on surface crystallization behavior of amorphous Fe90Zr10 alloy ribbon

    NASA Astrophysics Data System (ADS)

    Fujinami, Masanori; Ujihira, Yusuke

    1986-03-01

    The precipitous drop of crystallization temperature at the surface of amorphous Fe90Zr10 ribbon is confirmed by TMS and CEMS. The deficiency in Zr at the surface amorphous phase, caused by the absorption and the diffusion of oxygen, is found to be responsible for it. The final crystalline products are assigned to α-Fe, Fe3Zr and Fe2Zr, whereas only α-Fe precipitates at the surfaces. Moreover, it is indicated that the crystallization behavior of the bulk is influenced by the ambient gases during annealing and quite different between in vacuum and in air.

  11. Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region

    SciTech Connect

    Pigni,M.T.; Herman, M.; Oblozinsky, P.

    2008-06-24

    We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from keV range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.

  12. 89 Zr(n,γ)90 Zr from a surrogate reaction approach

    NASA Astrophysics Data System (ADS)

    Ota, Shuya; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I.; Austin, R. A. E.; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Ross, T.

    2015-04-01

    While recent studies have demonstrated the validity of the surrogate reaction approach for studying fission cross sections of short-lived actinides, its applicability for (n, γ) is still under investigation. We studied the γ-decay of 90 Zr produced by 91 Zr(p,d) and 92 Zr(p,t) in order to infer the 89 Zr(n, γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons and tritons were measured at forward angles of 30-60° with the STARS (Silicon Telescope Array for Reaction Studies) array of three segmented Micron S2 silicon detectors. Compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the LiTeR (Livermore Texas Richmond) array of five Compton-suppressed HPGe clovers. We will present results of γ-emission probabilities of 89 Zr(n, γ) and some theoretical discussions. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344. One of the authors, S. O. is supported by JSPS Postdoctoral Fellowship for Research Abroad.

  13. 1- and 2+ discrete states in 90Zr populated via the (17O,'17Oγ ) reaction

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Bracco, A.; Nicolini, R.; Lanza, E. G.; Vitturi, A.; Mengoni, D.; Leoni, S.; Benzoni, G.; Blasi, N.; Boiano, C.; Bottoni, S.; Brambilla, S.; Camera, F.; Corsi, A.; Giaz, A.; Million, B.; Pellegri, L.; Vandone, V.; Wieland, O.; Bednarczyk, P.; Ciemała, M.; Kmiecik, M.; Krzysiek, M.; Maj, A.; Bazzacco, D.; Bellato, M.; Birkenbach, B.; Bortolato, D.; Calore, E.; Cederwall, B.; de Angelis, G.; Désesquelles, P.; Eberth, J.; Farnea, E.; Gadea, A.; Görgen, A.; Gottardo, A.; Hess, H.; Isocrate, R.; Jolie, J.; Jungclaus, A.; Kempley, R. S.; Labiche, M.; Menegazzo, R.; Michelagnoli, C.; Molini, P.; Napoli, D. R.; Pullia, A.; Quintana, B.; Recchia, F.; Reiter, P.; Sahin, E.; Siem, S.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.

    2015-02-01

    2+ and 1- states in 90Zr were populated via the (17O,'17Oγ ) reaction at 340 MeV. The γ decay was measured with high resolution using the AGATA (advanced γ tracking array demonstrator array). Differential cross sections were obtained at few different angles for the scattered particle. The results of the elastic scattering and inelastic excitation of 2+,3-, and 1- states are compared with distorted-wave Born approximation (DWBA) calculations, using both the standard collective form factor and a form factor obtained by folding microscopically calculated transition densities. This allowed to extract the isoscalar component of the 1- state at 6.424 MeV. The comparison of the present (17O,'17Oγ ) data with existing (γ ,γ' ) and (p ,p' ) data in the corresponding region of the γ continuum (6-11 MeV), characterized by a large E 1 component, shows completely different behaviors of the cross section as a function of the nuclear excitation energy. The comparison of the data with DWBA calculations suggests a decrease of the isoscalar strength in the cross section with increasing excitation energy.

  14. Hot fusion-evaporation cross sections of 44Ca-induced reactions with lanthanide targets

    NASA Astrophysics Data System (ADS)

    Werke, T. A.; Mayorov, D. A.; Alfonso, M. C.; Tereshatov, E. E.; Folden, C. M.

    2015-11-01

    Background: Previously reported cross sections of 45Sc-induced reactions with lanthanide targets are much smaller than 48Ca-induced reactions on the same targets. 44Ca is one proton removed from 45Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45Sc- and 48Ca-induced reactions. Purpose: As part of a systematic investigation of fusion-evaporation reactions, cross sections of 44Ca-induced reactions on lanthanide targets were measured. These results are compared to available data for 48Ca- and 45Sc-induced fusion-evaporation cross sections on the same lanthanide targets. Collectively, these data provide insight into the importance of the survival against fission of excited compound nuclei produced near spherical shell closures. Methods: A beam of 6+Ca at an energy of ≈5 MeV /u was delivered by the K500 superconducting cyclotron at the Cyclotron Institute at Texas A&M University. The desired evaporation residues were selected by the Momentum Achromat Recoil Spectrometer and identified via their characteristic α -decay energies. Excitation functions for the 44Ca+158Gd ,159Tb, and 162Dy reactions were measured at five or more energies each. A theoretical model was employed to study the fusion-evaporation process. Results: The 44Ca-induced reactions have x n cross sections that are two orders of magnitude larger than 45Sc-induced reactions but two orders of magnitude smaller than 48Ca-induced reactions on the same targets. Proton emission competes effectively with neutron emission for the 44Ca+159Tb and 162Dy reactions. The maximum 4 n cross sections in the 44Ca+158Gd ,159Tb, and 162Dy reactions were 2100 ± 230 ,230 ± 20 , and 130 ±20 μ b , respectively. The 44Ca+158Gd and 159Tb cross sections are in good agreement with the respective cross bombardments of 48Ca+154Gd and 45Sc+158Gd once differences in capture cross sections and compound nucleus formation probabilities are corrected for. Conclusions: Excitation

  15. Investigation of the reaction 90Zr(p,γ) with in-beam γ-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Erbacher, Philipp; Endres, A.; Glorius, J.; Netterdon, L.; Sonnabend, K.; Thomas, B.; Zilges, A.

    2015-05-01

    The p nucleus 92Mo is believed to be mainly produced through photodisintegration reactions in type II supernovae. However, this production scenario cannot solely account for the observed solar relative isotopic abundance of 92Mo. Additional production scenarios have been suggested to explain this discrepancy. One of these scenarios could be the production of 92Mo in type Ia supernovae via a chain of proton-capture reactions. To verify this scenario, an accurate knowledge of the involved reaction rates is important. We measured the cross section of 90Zr(p,γ) reaction using an enriched 90Zr target by means of in-beam γ-ray spectroscopy in the energy range between 3.6MeV and 5.1MeV. Since the reactions 90Zr(p,γ) and 91Zr(p,n) produce the same nucleus, the contributions of both reactions have to be disentangled. This procedure is explained in this contribution in detail.

  16. Nuclear spectroscopy study of the isotopes populated via multinucleon transfer in the 90Zr + 208Pb reaction

    SciTech Connect

    Ur, C. A.; Corradi, L.; Stefanini, A. M.; Behera, B. R.; Fioretto, E.; Gadea, A.; Latina, A.; Szilner, S.; Beghini, S.; Farnea, E.; Montagnoli, G.; Scarlassara, F.; Haas, F.; Pollarolo, G.

    2006-08-14

    The present work takes advantage of the multinucleon transfer mechanism between heavy reaction partners to study the population pattern of excited nuclear states in near spherical Zirconium isotopes following the 90Zr + 208Pb reaction at an energy closed to the Coulomb barrier. Both the projectile and the target are well known closed shell nuclei offering an optimum situation for clean experimental and theoretical conditions. Total kinetic energy loss (TKEL) distributions were compared with calculations performed with the GRAZING code. The ability to use the TKEL as a selection tool for the states at different excitation energies was shown.

  17. Comparison of Optical Models for 400 MeV alpha scattering off 90Zr and 92Mo

    NASA Astrophysics Data System (ADS)

    Jones, Daniel; Howard, Kevin; Garg, Umesh; Senyigit, Menekse

    2015-10-01

    Nuclear incompressibility is an important parameter governing the equation of state of nuclear matter. From the measurable centroid energies of the Isoscalar Giant Monopole Resonance (ISGMR), the incompressibility of nuclear matter can be calculated. The first necessary step is to fit elastic scattering angular distributions for a particular reaction and test the obtained model dependent parameters by calculating low-lying discrete state distributions for target nuclei. This study tests the suitability of two optical models to reproduce the angular distributions of differential cross sections from elastic and inelastic scattering of 400-MeV alpha particles. The first model utilizes a single folded potential for both the real and imaginary volume terms, and the second utilizes a single folded potential for the real volume term, and a phenomenological Woods-Saxon potential for the imaginary volume term. The elastic distributions for two heavy isotopes, 90Zr and 92Mo, are analyzed and the best parameter sets for each are shown. From this comparison, it is concluded that the second model, the so called ``hybrid model,'' is better able to reproduce the angular distributions for both 90Zr and 92Mo. Future work will include the Multipole Decomposition Analysis (MDA) for each reaction. NSF/REU Program at Notre Dame.

  18. Nuclear Structure of the Closed Subshell Nucleus 90Zr Studied with the (n,n'(gamma)) Reaction

    SciTech Connect

    Garrett, P E; Younes, Y; Becker, J A; Bernstein, L A; Baum, E M; DiPrete, D P; Gatenby, R A; Johnson, E L; McGrath, C A; Yates, S W; Devlin, M; Fotiades, N; Nelson, R O; Brown, B A

    2003-06-12

    States in {sup 90}Zr have been observed with the (n,n{prime}{gamma}) reaction using both spallation and monoenergetic accelerator-produced neutrons. A scheme comprised of 81 levels and 157 transitions was constructed concentrating on levels below 5.6 MeV in excitation energy. Spins have been determined by considering data from all experimental studies performed for {sup 90}Zr. Lifetimes have been deduced using the Doppler-shift attenuation method for many of the states and transition rates have been obtained. A spherical shell-model interpretation in terms of particle-hole excitations assuming a {sup 88}Sr closed core is given. In some cases, enhancements in B(M1) and B(E2) values are observed that cannot be explained by assuming simple particle-hole excitations. Shell-model calculations using an extended f pg-shell model space reproduce the spectrum of excited states very well, and the gross features of the B(M1) and B(E2) transition rates. Transition rates for individual levels show discrepancies between calculations and experimental values.

  19. Can d44Ca be a Proxy for Paleoceanography? - A Case Study of Globigerinoides Sacculifer from Western Equatorial Atlantic

    NASA Astrophysics Data System (ADS)

    Yang, S.; Wei, K.; Shen, J. J.

    2007-12-01

    The δ 44Ca, δ 18O, and Mg/Ca ratios of fossil Globigerinoides sacculifer over the past 20 ka extracted from a Caribbean core, TT9108-1GC, have been measured in order to examine the possibility of using δ 44Ca as a proxy for paleoceanography. Our results indicate that the δ 44Ca of G. sacculifer varies as a function of sea surface temperature (SST) and sea surface salinity (SSS). The Caribbean Sea SSS, reconstructed by combining the δ 18O and Mg/Ca ratios of G. sacculifer and sea level change data, shows significant fluctuations between 36.5 and 39.5 psu during the last 20 ka. After isolating the temperature effect, the δ 44Ca of G. sacculifer exhibits a positive correlation with SSS, ca 0.27±0.02 ‰ per 1 psu. On the other hand, no significant relationship is observed between δ 44Ca and seawater [CO3 -2]. Moreover, variation of G. sacculifer δ 44Ca can also be explained using a Rayleigh fractionation model. As a function of temperature and salinity, the metabolic rate may influence the utilization of vacuole Ca+2 in G. sacculifer, resulting in different δ 44Ca values. The results of this study are inconsistent with the "rate-controlled fractionation model" of Lemarchand et al. (2004), instead, the results are more in-line with the foraminiferal biomineralization model of Erez (2003), where δ 44Ca reflects the adjustments of temperature, salinity, and pH of seawater isolated in vacuoles during the growth of G. sacculifer.

  20. PriMux

    Energy Science and Technology Software Center (ESTSC)

    2010-08-31

    PriMux is used to compute sets of compatible Polymerase Chain Reaction (PCR)signatures that can be used for detecting the presence of biological species in a small sample of material. Before use, the computed signatures must be empirically tested in a wet lab.

  1. Estimated {sup 55}Mn and {sup 90}Zr Cross Section Covariances in the Fast Neutron Energy Region

    SciTech Connect

    Pigni, M.T. Herman, M.; Oblozinsky, P.

    2008-12-15

    We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from the keV energy range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by a perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.

  2. 87Y(n,γ) and 89,90Zr(n,γ) cross sections from a surrogate reaction approach

    NASA Astrophysics Data System (ADS)

    Ota, Shuya; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I.; Austin, R. A. E.; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Ross, T.

    2015-05-01

    The surrogate reaction approach is an indirect method for determining nuclear reaction cross sections which cannot be measured directly or predicted reliably. While recent studies demonstrated the validity of the surrogate reaction approach for studying fission cross sections for short-lived actinides, its applicability for radiative neutron capture reactions ((n,γ)) is still under investigation. We studied the γ decay of excited 88Y and 90,91Zr nuclei produced by 89Y(p,d), 91Zr(p,d), and 92Zr(p,d) reactions, respectively, in order to infer the 87Y(n,γ) and 89, 90Zr(n,γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 25-60° with the array of three segmented Micron S2 silicon detectors. The compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the array of five Compton-suppressed HPGe clover detectors.

  3. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    SciTech Connect

    Pajtler, M. Varga; Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N.; Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J.; Gadea, A.; Haas, F.; Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F.; Märginean, N.; Pollarolo, G.; and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  4. Heterogeneous-nucleation and glass-formation studies of 56Ga2O3-44CaO

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin C.; Curreri, Peter A.; Pline, David

    1987-01-01

    Glass formation and heterogeneous crystallization are described for the reluctant-glass-forming 56Ga2O3-44CaO eutectic composition. The times and temperatures for nucleation at various cooling rates and experimental conditions were measured and empirical continuous-cooling-crystallization boundaries were constructed for various heterogeneous nucleation processes. A definition for an empirical critical cooling rate to form a glass from reluctant borderline glass formers is proposed, i.e., the cooling rate that results in glass formation in 95 percent of the quenching experiments.

  5. Double folding analysis of 3He elastic and inelastic scattering to low lying states on 90Zr, 116Sn and 208Pb at 270 MeV

    NASA Astrophysics Data System (ADS)

    Marwa, N. El-Hammamy

    2015-03-01

    The experimental data on elastic and inelastic scattering of 270 MeV 3He particles to several low lying states in 90Zr, 116Sn and 208Pb are analyzed within the double folding model (DFM). Fermi density distribution (FDD) of target nuclei is used to obtain real potentials with different powers. DF results are introduced into a modified DWUCK4 code to calculate the elastic and inelastic scattering cross sections. Two choices of potentials form factors are used; Woods Saxon (WS) and Woods Saxon Squared (WS2) for real potential, while the imaginary part is taken as phenomenological Woods Saxon (PWS) and phenomenological Woods Saxon Squared (PWS2). This comparison provides information about the similarities and differences of the models used in calculations.

  6. MISR Browse Images: Puerto Rico Dust Experiment (PRiDE)

    Atmospheric Science Data Center

    2013-04-02

    MISR Browse Images: Puerto Rico Dust Experiment (PRiDE) These MISR Browse images provide ... overview of the region observed during the Puerto Rico Dust Experiment (PRiDE) field campaign. PRiDE was a study of the radiative, ...

  7. Linking Knowledge and Action: PRI's Community Consultant.

    ERIC Educational Resources Information Center

    Spencer, Gregory P.

    Within the Partnership for Rural Improvement (PRI), community consultants operate within three complex sets of relationships: client groups, the organizational structure of PRI, and the local operational base. Community consultants are responsible for developing and facilitating rural development and for providing assistance in community and…

  8. Ion microscopic imaging of calcium transport in the intestinal tissue of vitamin D-deficient and vitamin D-replete chickens: A sup 44 Ca stable isotope study

    SciTech Connect

    Chandra, S.; Fullmer, C.S.; Smith, C.A.; Wasserman, R.H.; Morrison, G.H. )

    1990-08-01

    The intestinal absorption of calcium includes at least three definable steps; transfer across the microvillar membrane, movement through the cytosolic compartment, and energy-dependent extrusion into the lamina propria, Tracing the movement of calcium through the epithelium has been hampered by lack of suitable techniques and, in this study, advantage was taken of ion microscopy in conjunction with cryosectioning and use of the stable isotope 44Ca to visualize calcium in transit during the absorptive process. The effect of vitamin D, required for optimal calcium absorption, was investigated. Twenty millimolar 44Ca was injected into the duodenal lumen in situ of vitamin D-deficient and vitamin D-replete chickens. At 2.5, 5.0, and 20.0 min after injection, duodenal tissue was obtained and processed for ion microscopic imaging. At 2.5 min. 44Ca was seen to be concentrated in the region subjacent to the microvillar membrane in tissue from both groups. At 5.0 and 20.0 min, a similar pattern of localization was evident in D-deficient tissues. In D-replete tissues, the distribution of 44Ca became more homogenous, indicating that vitamin D increased the rate of transfer of Ca2+ from the apical to the basolateral membrane, a function previously ascribed to the vitamin D-induced calcium-binding protein (28-kDa calbindin-D). Quantitative aspects of the calcium absorptive process were determined in parallel experiments with the radionuclide 47Ca. Complementary information on the localization of the naturally occurring isotopes of calcium (40Ca) and potassium (39K) is also described.

  9. Cross section measurements of proton capture reactions relevant to the p process: The case of 89Y(p,γ)90Zr and 121,123Sb(p,γ)122,124Te

    NASA Astrophysics Data System (ADS)

    Harissopulos, S.; Spyrou, A.; Lagoyannis, A.; Axiotis, M.; Demetriou, P.; Hammer, J. W.; Kunz, R.; Becker, H.-W.

    2013-02-01

    The cross sections of the 89Y(p,γ)90Zr and the 121,123Sb(p,γ)122,124Te reactions were determined from γ-angular distribution measurements at beam energies from 1.6 to 3.4 MeV. In addition, angle-integrated cross sections were also measured at Ep=2, 3, 4, and 4.8 MeV for the 89Y(p,γ)90Zr reaction using the 4π γ-summing method. Astrophysical S factors and reaction rates were deduced from the measured cross sections. Statistical model calculations were performed using the nuclear-reaction code talys. The results from the comparison between theory and experiment are discussed in detail.

  10. DnaT is a PriC-binding protein.

    PubMed

    Huang, Chien-Chih; Huang, Cheng-Yang

    2016-09-01

    DnaT and PriC are replication restart primosomal proteins required for re-initiating chromosomal DNA replication. DnaT is a component of the PriA-dependent primosome, while PriC belongs to the PriC-dependent primosome. Whether DnaT can interact with PriC is still unknown. In this study, we define a direct interaction between PriC, a key initiator protein in PriC-mediated DNA replication restart, and DnaT, a DnaB/C complex loader protein, from Klebsiella pneumoniae. In fluorescence titrations, PriC bound to single-stranded DNA with a binding-site size of approximately 9 nt. Gold nanoparticle assay showed that the solution of DnaT-PriC changed from red to purple, which indicated the protein-protein interactions due to gold nanoparticle aggregate. In addition, this DnaT-PriC complex could be co-purified by the heparin HP column. Surface plasmon resonance analysis showed that the Kd value of DnaT bound to PriC was 2.9 × 10(-8) M. These results constitute a pioneering study of the DnaT-PriC interaction and present a putative link between the two independent replication restart pathways, namely, PriA- and PriC-dependent primosome assemblies. Further research can directly focus on determining how DnaT binds to the PriC-SSB-DNA tricomplex and regulates the PriC-dependent replication restart. PMID:27387236

  11. Determination of 90Sr / 238U ratio by double isotope dilution inductively coupled plasma mass spectrometer with multiple collection in spent nuclear fuel samples with in situ 90Sr / 90Zr separation in a collision-reaction cell

    NASA Astrophysics Data System (ADS)

    Isnard, H.; Aubert, M.; Blanchet, P.; Brennetot, R.; Chartier, F.; Geertsen, V.; Manuguerra, F.

    2006-02-01

    Strontium-90 is one of the most important fission products generated in nuclear industry. In the research field concerning nuclear waste disposal in deep geological environment, it is necessary to quantify accurately and precisely its concentration (or the 90Sr / 238U atomic ratio) in irradiated fuels. To obtain accurate analysis of radioactive 90Sr, mass spectrometry associated with isotope dilution is the most appropriated method. But, in nuclear fuel samples the interference with 90Zr must be previously eliminated. An inductively coupled plasma mass spectrometer with multiple collection, equipped with an hexapole collision cell, has been used to eliminate the 90Sr / 90Zr interference by addition of oxygen in the collision cell as a reactant gas. Zr + ions are converted into ZrO +, whereas Sr + ions are not reactive. A mixed solution, prepared from a solution of enriched 84Sr and a solution of enriched 235U was then used to quantify the 90Sr / 238U ratio in spent fuel sample solutions using the double isotope dilution method. This paper shows the results, the reproducibility and the uncertainties that can be obtained with this method to quantify the 90Sr / 238U atomic ratio in an UOX (uranium oxide) and a MOX (mixed oxide) spent fuel samples using the collision cell of an inductively coupled plasma mass spectrometer with multiple collection to perform the 90Sr / 90Zr separation. A comparison with the results obtained by inductively coupled plasma mass spectrometer with multiple collection after a chemical separation of strontium from zirconium using a Sr spec resin (Eichrom) has been performed. Finally, to validate the analytical procedure developed, measurements of the same samples have been performed by thermal ionization mass spectrometry, used as an independent technique, after chemical separation of Sr.

  12. Deinococcus radiodurans PriA is a Pseudohelicase

    PubMed Central

    Lopper, Matthew E.; Boone, Jacob; Morrow, Christopher

    2015-01-01

    Reactivation of repaired DNA replication forks in bacteria is catalyzed by PriA helicase. This broadly-conserved bacterial enzyme can remodel the structure of DNA at a repaired DNA replication fork by unwinding small portions of duplex DNA to prepare the fork for replisome reloading. While PriA’s helicase activity is not strictly required for cell viability in E. coli, the sequence motifs that confer helicase activity upon PriA are well-conserved among sequenced bacterial priA genes, suggesting that PriA’s duplex DNA unwinding activity confers a selective advantage upon cells. However, these helicase sequence motifs are not well-conserved among priA genes from the Deinococcus-Thermus phylum. Here, we show that PriA from a highly radiation-resistant member of that phylum, Deinococcus radiodurans, lacks the ability to hydrolyze ATP and unwind duplex DNA, thus qualifying D. radiodurans PriA as a pseudohelicase. Despite the lack of helicase activity, D. radiodurans PriA has retained the DNA binding activity expected of a typical PriA helicase, and we present evidence for a physical interaction between D. radiodurans PriA and its cognate replicative helicase, DnaB. This suggests that PriA has retained a role in replisome reloading onto repaired DNA replication forks in D. radiodurans despite its lack of helicase activity. PMID:26182205

  13. Investigation of spin-isospin strength in sup 48 Ca r arrow sup 48 Sc and sup 90 Zr r arrow sup 90 Nb using the ( sup 6 Li, sup 6 He) reaction

    SciTech Connect

    Wirth, H.; Aschenauer, E.; Eyrich, W.; Lehmann, A.; Moosburger, M.; Schloesser, H. ); Gils, H.J.; Rebel, H.; Zagromski, S. )

    1990-06-01

    The ({sup 6}Li,{sup 6}He) reaction was studied on the target nuclei {sup 48}Ca and {sup 90}Zr at {ital E}{sub Li}=156 MeV at extreme forward reaction angles. From the zero degree spectra Gamow-Teller strength was extracted for excitation energies 0{le}{ital E}{sub {ital x}}{approx lt}20 MeV. The results are compared with distorted-wave Born approximation calculations and ({ital p},{ital n}) data.

  14. Remotely Sensing the Photochemical Reflectance Index (PRI)

    NASA Technical Reports Server (NTRS)

    Vanderbilt, Vern

    2015-01-01

    In remote sensing, the Photochemical Reflectance Index (PRI) provides insight into physiological processes occurring inside the leaves in a stand of plants. Developed by Gamon et al., (1990 and 1992), PRI evolved from laboratory measurements of the reflectance of individual leaves (Bilger et al.,1989). Yet in a remotely sensed image, a pixel measurement may include light from both reflecting and transmitting leaves. We conducted laboratory experiments comparing values of PRI based upon polarized reflectance and transmittance measurements of water and nutrient stressed leaves. We illuminated single detached leaves using a current controlled light source (Oriel model 66881) and measured the leaf weight using an analytical balance (Mettler model AE 260) and the light reflected and transmitted by the leaf during dry down using two Analytical Spectral Devices spectroradiometers. Polarizers on the incident and reflected light beams allowed us to divide the leaf reflectance into two parts: a polarized surface reflectance and a non-polarized 'leaf interior' reflectance. Our results underscore the importance when calculating PRI of removing the leaf surface reflection, which contains no information about physiological processes ongoing in the leaf interior. The results show that the leaf physiology information is in the leaf interior reflectance, not the leaf transmittance. Applied to a plant stand, these results suggest use of polarization measurements in sun-view directions that minimize the number of sunlit transmitting leaves in the sensor field of view.

  15. Temperature Dependent Sr-Isotope (δ 88Sr) and Ca-Isotope (δ 44Ca) Fractionation in Carbonate Precipitates and Corals

    NASA Astrophysics Data System (ADS)

    Eisenhauer, A.; Fietzke, J.; Gussone, N.; Böhm, F.; Bock, B.; Nägler, T.

    2003-12-01

    The knowledge of the influence of temperature and other environmental factors on isotope fractionation of divalent cations like Ca2+ and Sr2+ during inorganic and biogenic controlled precipitation of calcium carbonate is crucial for their interpretation as paleo proxies. In order to extend our earlier studies on Ca-isotope fractionation (e.g. Gussone et al., 2003), we determined δ 88Sr isotope ratios on seawater and on corals. We define the stable Sr isotope ratio as δ 88Sr=((88Sr/86Sr)Sample/(88Sr/86Sr)Standard -1)*1000; Sr Standard is NBS 987. First measurements of the IAPSO seawater standard result in δ 88Sr of 0.38+/-0.02 ‰ . Coral CaCO3 precipitated from seawater in a temperature range from about 22° C to about 27° C correspond to δ 88Sr-values ranging from 0.17 ‰ to about 0.32 ‰ indicating that carbonate precipitated from seawater is isotopically lighter than seawater itself. The slope of 0.027 ‰ /° C for the temperature-δ 88Sr relationship in corals is about a factor of 1.7 larger than the slope of δ 44Ca ratios in inorganically precipitated aragonite. However, the fractionation α (T)=((88Sr/86Sr)CaCO3)/(88Sr/86Sr)Seawater) at a given temperature is about one order of magnitude less for Sr-isotopes relative to Ca-isotopes. The larger temperature-δ 88Sr gradient in comparison to the Ca-isotopes is interpreted to reflect the smaller ion potential and the correspondingly smaller mass of the associated Sr2+-aquocomplex. The observation that δ 88Sr and δ 44Ca are positively correlated with temperature points to the likelihood that kinetic or equilibrium fractionation effects and the mass of the associated acquocomplex control the degree of divalent cation isotope fractionation during CaCO3-precipitation. Reference: Gussone N., Eisenhauer A., Heuser A., Dietzel M., Bock B., Böhm F., Spero H., Lea D. W., Bijma J., and Nägler T. F. (2003) Model for Kinetic Effects on Calcium Isotope Fractionation (δ 44Ca) in Inorganic Aragonite and Cultured

  16. Differential interference of vitamin D analogs PRI-1906, PRI-2191, and PRI-2205 with the renewal of human colon cancer cells refractory to treatment with 5-fluorouracil.

    PubMed

    Kotlarz, Agnieszka; Przybyszewska, Małgorzata; Swoboda, Paweł; Miłoszewska, Joanna; Grygorowicz, Monika Anna; Kutner, Andrzej; Markowicz, Sergiusz

    2016-04-01

    This study was aimed to determine whether hypocalcemic analogs of active forms of vitamins D modulate expression of genes related to stem-like phenotype in colon cancer cell lines HT-29 and HCT-116 undergoing renewal after the treatment with 5-fluorouracil (5-FU). Both lines express vitamin D receptor, but differ in differentiation stage and vitamin D sensitivity. Cells that resisted the 5-FU exposure were treated with synthetic analog of 1,25-dihydroxyvitamin D2 (PRI-1906) and analogs of 1,25-dihydroxyvitamin D3 (PRI-2191 and PRI-2205). Proliferative activity was more profoundly affected by vitamin D analogs in HT-29/5-FU than in HCT-116/5-FU cells. In HT-29/5-FU cells, analogs PRI-1906 and PRI-2191 downregulated the expression of genes related to survival, re-growth, and invasiveness during renewal, while PRI-2205 increased expression of genes related to differentiation only. In HCT-116/5-FU cells, PRI-2191 decreased the expression of stemness- and angiogenesis-related genes, whereas PRI-1906 augmented their expression. The effects in HCT-116/5-FU cells were observed at higher concentrations of the analogs than those used for HT-29/5-FU cells. Out of the series of analogs studied, PRI-2191 might be used to counteract the renewal of both moderately and poorly differentiated cancer cells following conventional treatment. PMID:26511971

  17. Sr2+/Ca2+ and 44Ca/40Ca fractionation during inorganic calcite formation: III. Impact of salinity/ionic strength

    PubMed Central

    Tang, Jianwu; Niedermayr, Andrea; Köhler, Stephan J.; Böhm, Florian; Kısakürek, Basak; Eisenhauer, Anton; Dietzel, Martin

    2012-01-01

    In order to apply Sr/Ca and 44Ca/40Ca fractionation during calcium carbonate (CaCO3) formation as a proxy to reconstruct paleo-environments, it is essential to evaluate the impact of various environmental factors. In this study, a CO2 diffusion technique was used to crystallize inorganic calcite from aqueous solutions at different ionic strength/salinity by the addition of NaCl at 25 °C. Results show that the discrimination of Sr2+ versus Ca2+ during calcite formation is mainly controlled by precipitation rate (R in μmol/m2/h) and is weakly influenced by ionic strength/salinity. In analogy to Sr incorporation, 44Ca/40Ca fractionation during precipitation of calcite is weakly influenced by ionic strength/salinity too. At 25 °C the calcium isotope fractionation between calcite and aqueous calcium ions (Δ44/40Cacalcite-aq = δ44/40Cacalcite − δ44/40Caaq) correlates inversely to log R values for all experiments. In addition, an inverse relationship between Δ44/40Cacalcite-aq and log DSr, which is independent of temperature, precipitation rate, and aqueous (Sr/Ca)aq ratio, is not affected by ionic strength/salinity either. Considering the log DSr and Δ44/40Cacalcite-aq relationship, Sr/Ca and δ44/40Cacalcite values of precipitated calcite can be used as an excellent multi-proxy approach to reconstruct environmental conditions (e.g., temperature, precipitation rate) of calcite growth and diagenetic alteration. PMID:22347722

  18. Cation self-diffusion of 44Ca, 88Y, and 96Zr in single-crystalline calcia- and yttria-doped zirconia

    NASA Astrophysics Data System (ADS)

    Kilo, M.; Taylor, M. A.; Argirusis, Ch.; Borchardt, G.; Lesage, B.; Weber, S.; Scherrer, S.; Scherrer, H.; Schroeder, M.; Martin, M.

    2003-12-01

    Self-diffusion of calcium, yttrium, and zirconium in single-crystalline YSZ and CSZ (YSZ: yttria-stabilized zirconia; containing 10 to 32 mol % Y2O3; CSZ: calcia-stabilized zirconia; containing 11 and 17 mol % CaO) was measured at temperatures between 960 and 1700 °C. For zirconium and calcium diffusion, the stable isotopes 44Ca and 96Zr were used as tracers and the samples were analyzed with secondary ion mass spectrometry. In the case of yttrium diffusion, the radioactive tracer 88Y was used and an abrasive sectioning technique was applied. Zirconium bulk diffusion is slower than yttrium and calcium bulk diffusion, and there is a nearly linear correlation of diffusion coefficient with cation radius. In YSZ, zirconium and yttrium bulk diffusivity are maximum for a stabilizer content of 10-11 mol %, while in CSZ both calcium and zirconium tracer diffusion are independent of the calcium content. The activation enthalpy of yttrium stabilizer bulk diffusion (4.2 eV) is, as in CSZ, slightly smaller than for zirconium bulk diffusion (4.5 eV). The yttrium dislocation pipe diffusivity is five to six orders of magnitude faster than the bulk diffusivity, and its activation enthalpy (3.5 eV) is also smaller than that of the bulk diffusion. From the activation enthalpy and from the concentration dependence of the cation bulk diffusion, it is concluded that the cation diffusion occurs either via free vacancies (VZr4' in YSZ) or via bound vacancies ([VZr4'-2VO2•]x in CSZ).

  19. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics.

    PubMed

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K W

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr(3+), owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  20. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    PubMed Central

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-01-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process. PMID:27339815

  1. Tailoring Electrical Properties and the Structure Evolution of (Ba0.85Ca0.15)(Ti0.90Zr0.10)1- x Li4 x O3 Ceramics with Low Sintering Temperature

    NASA Astrophysics Data System (ADS)

    Chao, Xiaolian; Wang, Juanjuan; Xie, Xueke; Liang, Pengfei; Yang, Zupei

    2016-01-01

    The objective of this work is to lower the sintering temperature of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCZT) ceramics without sacrificing their piezoelectric performance. Li2CO3 was used as sintering aid so that BCZT ceramics with low sintering temperature were fabricated by conventional solid-state sintering. The sintering temperature of the BCZT ceramics was greatly decreased from 1450°C to 1260°C by introducing Li2CO3. The ceramics with a Li2CO3 content of x = 0.02 demonstrated outstanding piezoelectric and dielectric properties: d 33 = 436 pC/N, k p = 56%, Q m = 86, ɛ r = 5185, tan δ = 0.017 and T c = 83°C. We explain the structural evolution in these ceramics through the growth mechanism of liquid-phase sintering, which includes 4 steps: (1) interface reaction in the initial state; (2) diffusion of Li2CO3 into BCZT grains; (3) densification by diffusion of CO2 through BCZT; and (4) improvement of properties by diffusion into the lattice of grain. As a result, Li2CO3 additive can effectively improve the piezoelectric properties of BCZT-based ceramics sintered at low temperatures.

  2. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    NASA Astrophysics Data System (ADS)

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-06-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process.

  3. Finding the SurPriSe: A Case Study of a Faculty Learning Community

    ERIC Educational Resources Information Center

    Michel, Roberta M.

    2014-01-01

    This article details a faculty learning community (FLC) that started in 2009 on the campus of a Midwestern University and has evolved into an interdisciplinary research, teaching and social community of practice and learning called SurPriSe. SurPriSe is an acronym that reflects the interest area of the FLC; Sur for surveillance, Pri for privacy,…

  4. Canopy Level Chlorophyll Fluorescence and the PRI in a Cornfield

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Cheng, Yen-Ben; Corp, Lawrence A.; Campbell, Petya K. E.; Huemmrich, K. Fred; Zhang, Qingyuan; Kustas, William P.

    2012-01-01

    Two bio-indicators, the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (SIF), were derived from directional hyperspectral observations and studied in a cornfield on two contrasting days in the growing season. Both red and far-red SIF exhibited higher values on the day when the canopy in the early senescent stage, but only the far-red SIF showed sensitivity to viewing geometry. Consequently, the red/far-red SIF ratio varied greatly among azimuth positions while the largest values were obtained for the "hotspot" at both growth stages. This ratio was lower (approx.0.88 +/- 0.4) in early July than in August when the ratio approached equivalence (near approx.1). In concert, the PRI exhibited stronger responses to both zenith and azimuth angles and different values on the two growth stages. The potential of using these indices to monitor photosynthetic activities needs further investigation

  5. Prodifferentiation Activity of Novel Vitamin D₂ Analogs PRI-1916 and PRI-1917 and Their Combinations with a Plant Polyphenol in Acute Myeloid Leukemia Cells.

    PubMed

    Nachliely, Matan; Sharony, Ehud; Bolla, Narasimha Rao; Kutner, Andrzej; Danilenko, Michael

    2016-01-01

    1α,25-dihydroxyvitamin D₃ (1,25D3) is a powerful differentiation inducer for acute myeloid leukemia (AML) cells. However, 1,25D3 doses required for differentiation of AML cells may cause lethal hypercalcemia in vivo. There is evidence that vitamin D₂ is less toxic than vitamin D₃ in animals. Here, we determined the differentiation effects of novel analogs of 1α,25-dihydroxyvitamin D₂ (1,25D2), PRI-1916 and PRI-1917, in which the extended side chains of their previously reported precursors (PRI-1906 and PRI-1907, respectively) underwent further 24Z (24-cis) modification. Using four human AML cell lines representing different stages of myeloid maturation (KG-1a, HL60, U937, and MOLM-13), we found that the potency of PRI-1916 was slightly higher or equal to that of PRI-1906 while PRI-1917 was significantly less potent than PRI-1907. We also demonstrated that 1,25D2 was a less effective differentiation agent than 1,25D3 in these cell lines. Irrespective of their differentiation potency, all the vitamin D₂ derivatives tested were less potent than 1,25D3 in transactivating the DR3-type vitamin D response elements. However, similar to 1,25D3, both 1,25D2 and its analogs could strongly cooperate with the plant polyphenol carnosic acid in inducing cell differentiation and inhibition of G1-S cell cycle transition. These results indicate that the 24Z modification has contrasting effects on the differentiation ability of PRI-1906 and PRI-1907 and that the addition of a plant polyphenol could result in a similar extent of cell differentiation induced by different vitamin D compounds. The enhanced antileukemic effects of the tested combinations may constitute the basis for the development of novel approaches for differentiation therapy of AML. PMID:27399677

  6. Prodifferentiation Activity of Novel Vitamin D2 Analogs PRI-1916 and PRI-1917 and Their Combinations with a Plant Polyphenol in Acute Myeloid Leukemia Cells

    PubMed Central

    Nachliely, Matan; Sharony, Ehud; Bolla, Narasimha Rao; Kutner, Andrzej; Danilenko, Michael

    2016-01-01

    1α,25-dihydroxyvitamin D3 (1,25D3) is a powerful differentiation inducer for acute myeloid leukemia (AML) cells. However, 1,25D3 doses required for differentiation of AML cells may cause lethal hypercalcemia in vivo. There is evidence that vitamin D2 is less toxic than vitamin D3 in animals. Here, we determined the differentiation effects of novel analogs of 1α,25-dihydroxyvitamin D2 (1,25D2), PRI-1916 and PRI-1917, in which the extended side chains of their previously reported precursors (PRI-1906 and PRI-1907, respectively) underwent further 24Z (24-cis) modification. Using four human AML cell lines representing different stages of myeloid maturation (KG-1a, HL60, U937, and MOLM-13), we found that the potency of PRI-1916 was slightly higher or equal to that of PRI-1906 while PRI-1917 was significantly less potent than PRI-1907. We also demonstrated that 1,25D2 was a less effective differentiation agent than 1,25D3 in these cell lines. Irrespective of their differentiation potency, all the vitamin D2 derivatives tested were less potent than 1,25D3 in transactivating the DR3-type vitamin D response elements. However, similar to 1,25D3, both 1,25D2 and its analogs could strongly cooperate with the plant polyphenol carnosic acid in inducing cell differentiation and inhibition of G1–S cell cycle transition. These results indicate that the 24Z modification has contrasting effects on the differentiation ability of PRI-1906 and PRI-1907 and that the addition of a plant polyphenol could result in a similar extent of cell differentiation induced by different vitamin D compounds. The enhanced antileukemic effects of the tested combinations may constitute the basis for the development of novel approaches for differentiation therapy of AML. PMID:27399677

  7. Presenilin-1 influences processing of the acetylcholinesterase membrane anchor PRiMA.

    PubMed

    García-Ayllón, María-Salud; Campanari, María-Letizia; Montenegro, María-Fernanda; Cuchillo-Ibáñez, Inmaculada; Belbin, Olivia; Lleó, Alberto; Tsim, Karl; Vidal, Cecilio J; Sáez-Valero, Javier

    2014-07-01

    Presenilin-1 (PS1) is the catalytic component of the γ-secretase complex. In this study, we explore if PS1 participates in the processing of the cholinergic acetylcholinesterase (AChE). The major AChE variant expressed in the brain is a tetramer (G(4)) bound to a proline-rich membrane anchor (PRiMA). Overexpression of the transmembrane PRiMA protein in Chinese hamster ovary cells expressing AChE and treated with the γ-secretase inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester have enabled us to study whether, through its γ-secretase activity, PS1 participates in the processing of PRiMA-linked AChE. γ-Secretase inhibition led to a notable increase in the level of PRiMA-linked AChE, suggesting that γ-secretase is involved in the cleavage of PRiMA. We demonstrate that cleavage of PRiMA by γ-secretase results in a C-terminal PRiMA fragment. Immunofluorescence labeling allowed us to identify this PRiMA fragment in the nucleus. Moreover, we have determined changes in the proportion of the raft-residing AChE-PRiMA in a PS1 conditional knockout mouse. Our results are of interest as both enzymes have therapeutic relevance for Alzheimer's disease. PMID:24612677

  8. Diffuse sky radiation influences the relationship between canopy PRI and shadow fraction

    NASA Astrophysics Data System (ADS)

    Mõttus, Matti; Takala, Tuure L. H.; Stenberg, Pauline; Knyazikhin, Yuri; Yang, Bin; Nilson, Tiit

    2015-07-01

    The Photochemical Reflectance Index (PRI) of green leaves is an indicator of photosynthetic downregulation: when the photosynthetic apparatus is close to the saturation limit, PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves under different local irradiance conditions, it should be possible to determine the saturation level of the leaves and obtain information on the light use efficiency (LUE) of a vegetation canopy. The dependence of PRI on the ratio of sunlit to shaded foliage (quantified by the canopy shadow fraction) in the field of view of an instrument has been used to remotely measure canopy LUE on clear days. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature.

  9. Correcting the relationship between PRI and shadow fraction for the blue sky effect

    NASA Astrophysics Data System (ADS)

    Mõttus, Matti

    2016-04-01

    The Photochemical Reflectance Index (PRI) is defined as the normalized difference ratio of leaf reflectance at two specific wavelengths in the green spectral region. Its value depends on the status of leaf carotenoid content, and especially that of the xanthophyll cycle pigments. Due to the dependence on the xanthophyll cycle, when the photosynthetic apparatus of green leaves is close to the saturation limit, their PRI becomes dependent on light conditions. Therefore, by measuring the PRI of leaves in the same canopy under different local irradiance conditions on a sunny day, it should be possible to determine the saturation level of the leaves. In turn, this gives information on the light use efficiency (LUE) of the vegetation canopy. The average light conditions of visible foliage elements are often quantified with the shadow fraction -- the fraction of visible foliage not lit by direct sunlight. The dependence of PRI on the shadow fraction has been used to remotely measure canopy LUE on clear days. Variations in shadow fraction have been achieved with multiangular measurement. However, besides photosynthetic downregulation, the dependence of canopy PRI on shadow fraction is affected by the blue sky radiation caused by scattering in the atmosphere. To quantify this effect on remotely sensed PRI, we present the underlying definitions relating leaf and canopy PRI and perform the required calculations for typical midsummer conditions in Central Finland. We demonstrate that the effect of blue sky radiation on the variation of PRI with canopy shadow fraction is similar in shape and magnitude to that of LUE variations reported in literature. Next, we propose a new method to assess these PRI variations in structured vegetation. We investiagate this blue sky effect on the PRI -- shadow fraction relationship with high spatial (60 cm) and spectral (9.8 nm) resolution airborne imaging spectroscopy data from Hyytiälä, Finland. We evaluate the spectral irradiance in

  10. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuck, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-07-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use-efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "spectral reflectance sensors" (SRS sensors; recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration - one that considered sky conditions (cloud cover) at midday only, and another that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal timescale, PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different timescales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches for studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  11. Monitoring seasonal and diurnal changes in photosynthetic pigments with automated PRI and NDVI sensors

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.; Kovalchuk, O.; Wong, C. Y. S.; Harris, A.; Garrity, S. R.

    2015-02-01

    The vegetation indices normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) provide indicators of pigmentation and photosynthetic activity that can be used to model photosynthesis from remote sensing with the light-use efficiency model. To help develop and validate this approach, reliable proximal NDVI and PRI sensors have been needed. We tested new NDVI and PRI sensors, "SRS" sensors recently developed by Decagon Devices, during spring activation of photosynthetic activity in evergreen and deciduous stands. We also evaluated two methods of sensor cross-calibration, one that considered sky conditions (cloud cover) at midday only, and the other that also considered diurnal sun angle effects. Cross-calibration clearly affected sensor agreement with independent measurements, with the best method dependent upon the study aim and time frame (seasonal vs. diurnal). The seasonal patterns of NDVI and PRI differed for evergreen and deciduous species, demonstrating the complementary nature of these two indices. Over the spring season, PRI was most strongly influenced by changing chlorophyll : carotenoid pool sizes, while over the diurnal time scale PRI was most affected by the xanthophyll cycle epoxidation state. This finding demonstrates that the SRS PRI sensors can resolve different processes affecting PRI over different time scales. The advent of small, inexpensive, automated PRI and NDVI sensors offers new ways to explore environmental and physiological constraints on photosynthesis, and may be particularly well-suited for use at flux tower sites. Wider application of automated sensors could lead to improved integration of flux and remote sensing approaches to studying photosynthetic carbon uptake, and could help define the concept of contrasting vegetation optical types.

  12. Structure and Function of the PriC DNA Replication Restart Protein.

    PubMed

    Wessel, Sarah R; Cornilescu, Claudia C; Cornilescu, Gabriel; Metz, Alice; Leroux, Maxime; Hu, Kaifeng; Sandler, Steven J; Markley, John L; Keck, James L

    2016-08-26

    Collisions between DNA replication complexes (replisomes) and barriers such as damaged DNA or tightly bound protein complexes can dissociate replisomes from chromosomes prematurely. Replisomes must be reloaded under these circumstances to avoid incomplete replication and cell death. Bacteria have evolved multiple pathways that initiate DNA replication restart by recognizing and remodeling abandoned replication forks and reloading the replicative helicase. In vitro, the simplest of these pathways is mediated by the single-domain PriC protein, which, along with the DnaC helicase loader, can load the DnaB replicative helicase onto DNA bound by the single-stranded DNA (ssDNA)-binding protein (SSB). Previous biochemical studies have identified PriC residues that mediate interactions with ssDNA and SSB. However, the mechanisms by which PriC drives DNA replication restart have remained poorly defined due to the limited structural information available for PriC. Here, we report the NMR structure of full-length PriC from Cronobacter sakazakii PriC forms a compact bundle of α-helices that brings together residues involved in ssDNA and SSB binding at adjacent sites on the protein surface. Disruption of these interaction sites and of other conserved residues leads to decreased DnaB helicase loading onto SSB-bound DNA. We also demonstrate that PriC can directly interact with DnaB and the DnaB·DnaC complex. These data lead to a model in which PriC acts as a scaffold for recruiting DnaB·DnaC to SSB/ssDNA sites present at stalled replication forks. PMID:27382050

  13. Bi-directional processing of pri-miRNAs with branched terminal loops by Arabidopsis Dicer-like1

    PubMed Central

    Zhu, Hongliang; Zhou, Yuyi; Castillo-González, Claudia; Lu, Amber; Ge, Chunxiao; Zhao, Ying-Tao; Duan, Liusheng; Li, Zhaohu; Axtell, Michael J.; Wang, Xiu-Jie; Zhang, Xiuren

    2013-01-01

    miRNAs originate from primary transcripts (pri-miRNAs) with characteristic stem-loop structures. Accurate processing of pri-miRNAs is required for functional miRNAs. Here, using pri-miR166 family as a paradigm, we report the decisive role of pri-miRNA terminal loops in miRNA biogenesis. We found that multi-branched terminal loops in pri-miR166s substantially suppressed miR166 expression in vivo. Unlike canonical processing of pri-miRNAs, terminal-loop-branched (TLBed) pri-miRNAs can be processed by Dicer-like1 (DCL1) complexes bi-directionally: from base to loop and from loop to base, resulting in productive and abortive processing of miRNAs, respectively. In either case, DCL1 complexes canonically cut pri-miRNAs at a distance of 16-17 base pairs (bp) from a reference single-stranded loop region. DCL1 also adjusts processing sites toward an internal loop through its helicase domain. Thus, these results provide new insight into the poorly understood processing mechanism of pri-miRNAs with complicated secondary structures. PMID:23934148

  14. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein.

    PubMed

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M; Schneiter, Roger; Asojo, Oluwatoyin A

    2016-01-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg(2+) coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg(2+)-dependent sterol binding by Pry1. PMID:27344972

  15. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein

    PubMed Central

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M.; Schneiter, Roger; Asojo, Oluwatoyin A.

    2016-01-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg2+ coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg2+-dependent sterol binding by Pry1. PMID:27344972

  16. Structural and functional characterization of the CAP domain of pathogen-related yeast 1 (Pry1) protein

    NASA Astrophysics Data System (ADS)

    Darwiche, Rabih; Kelleher, Alan; Hudspeth, Elissa M.; Schneiter, Roger; Asojo, Oluwatoyin A.

    2016-06-01

    The production, crystal structure, and functional characterization of the C-terminal cysteine-rich secretory protein/antigen 5/pathogenesis related-1 (CAP) domain of pathogen-related yeast protein-1 (Pry1) from Saccharomyces cerevisiae is presented. The CAP domain of Pry1 (Pry1CAP) is functional in vivo as its expression restores cholesterol export to yeast mutants lacking endogenous Pry1 and Pry2. Recombinant Pry1CAP forms dimers in solution, is sufficient for in vitro cholesterol binding, and has comparable binding properties as full-length Pry1. Two crystal structures of Pry1CAP are reported, one with Mg2+ coordinated to the conserved CAP tetrad (His208, Glu215, Glu233 and His250) in spacegroup I41 and the other without divalent cations in spacegroup P6122. The latter structure contains four 1,4-dioxane molecules from the crystallization solution, one of which sits in the cholesterol binding site. Both structures reveal that the divalent cation and cholesterol binding sites are connected upon dimerization, providing a structural basis for the observed Mg2+-dependent sterol binding by Pry1.

  17. Diurnal and Directional Responses of Chlorophyll Fluorescence and the PRI in a Cornfield

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth; Cheng, Y. B.; Corp, L.; Campbell, P.; Kustas, W.

    2010-01-01

    Determining the health and vigor of vegetation using high spectral resolution remote sensing is an important goal which has application to monitoring agriculture and ecosystem productivity and carbon exchange. Two spectral indices used to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.) are the Photochemical Reflectance Index (PRI) and solar-induced red and far-red Chlorophyll Fluorescence (Fs). Both the PRI and Fs capture the dynamics of photoprotection mechanisms within green foliage: the PRI is based on the association of the reflected radiation in the green spectrum with the xanthophyll cycle, whereas Fs measures the emitted radiation in the red and far-red spectrum. Fs was determined from retrievals in the atmospheric oxygen absorption features centered at 688 and 760 nm using a modified Fraunhofer Line Depth (FLD) method. We previously demonstrated diurnal and seasonal PRI differences for sunlit vs. shaded foliage in a conifer forest canopy, as expressed in the hotspot and darkspot of the Bidirectional Reflectance Function (BRF). In a USDA-ARS experimental field site located in Beltsville, MD, USA, measurements were acquired over a corn crop from a nadir view in 2008 with an ASD FieldSpec Pro (Analytical Spectral Devices, Inc., Boulder, CO, USA) to study the behavior of the PRI for sunlit and shaded foliage as captured in reflectance variations associated with the BRF, in a I m tall canopy in the vegetative growth stage. Those observations were compared to simulations obtained from two radiative transfer models. Measurements were then acquired to examine whether the PRI and Fs were influenced by view zenith and azimuth geometries at different times of day. Those measurements were made in 2010 with the Ocean Optics USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at several times during the day on

  18. Fluorescence, PRI and canopy temperature for water stress detection in cereal crops

    NASA Astrophysics Data System (ADS)

    Panigada, C.; Rossini, M.; Meroni, M.; Cilia, C.; Busetto, L.; Amaducci, S.; Boschetti, M.; Cogliati, S.; Picchi, V.; Pinto, F.; Marchesi, A.; Colombo, R.

    2014-08-01

    Narrow-band multispectral remote sensing techniques and thermal imagery were investigated for water stress detection in cereal crops. Visible and near infrared AISA Eagle (Specim, Finland) and thermal AHS-160 (Sensytech Inc., USA) imageries were acquired with an airborne survey on a farm-level experimental site where maize (Zea mays L.) and sorghum (Sorghum bicolor L.) were grown with three different irrigation treatments. Vegetation biophysical and eco-physiological measurements were collected concurrently with the airborne campaign. Leaf fluorescence yield (ΔF/Fm‧) resulted to be a good indirect measure of water stress. Therefore, ΔF/Fm‧ measurements were compared against remotely sensed indicators: (i) the Photochemical Reflectance Index (PRI), (ii) the sun-induced chlorophyll fluorescence at 760 nm (F760), retrieved by the Fraunhofer line depth method and (iii) the canopy temperature (TC) calculated decoupling soil and vegetation contributions. TC was related to ΔF/Fm‧ with the highest determination coefficient (R2 = 0.65), followed by PRI586 (reference band at 586 nm) (R2 = 0.51). The relationship with F760 was significant but weaker (R2 = 0.36). The coefficient of determination increased up to 0.54 when pigment concentration was considered by multiplying ΔF/Fm‧ and chlorophyll content, confirming the close relationship between passive fluorescence signal, pigment content and light photosystem efficiency. PRI586, F760 and TC maps were produced in maize and sorghum plots. The differences in the average values of PRI586, F760 and TC extracted from the plots with different water treatments showed that water treatments were well discriminated in maize plots by the three remotely sensed indicators. This was confirmed by the visual observation of the PRI586, F760 and TC maps, while in sorghum plots, F760 and TC appeared more sensitive to water stress compared to PRI586.

  19. Distinct localization of Collagen Q and PRiMA forms of Acetylcholinesterase at the neuromuscular junction

    PubMed Central

    Bernard, Véronique; Girard, Emmanuelle; Hrabovska, Anna; Camp, Shelley; Taylor, Palmer; Plaud, Benoit; Krejci, Eric

    2015-01-01

    Acetylcholinesterase (AChE) terminates the action of acetylcholine at cholinergic synapses thereby preventing rebinding of acetylcholine to nicotinic post-synaptic receptors at the neuromuscular junction. Here we show that AChE is not localized close to these receptors on the post-synaptic surface, but is instead clustered along the presynaptic membrane and deep in the post-synaptic folds. Because AChE is anchored by ColQ in the basal lamina and is linked to the plasma membrane by a transmembrane subunit (PRiMA), we used a genetic approach to evaluate the respective contribution of each anchoring oligomer. By visualization and quantification of AChE in mouse strains devoid of ColQ, PRiMA or AChE, specifically in the muscle, we found that along the nerve terminus, the vast majority of AChE is anchored by ColQ that is only produced by the muscle, whereas very minor amounts of AChE are anchored by PRiMA that is produced by motoneurons. In its synaptic location, AChE is therefore positioned to scavenge ACh that effluxes from the nerve by non-quantal release. AChE-PRiMA, produced by the muscle, is diffusely distributed along the muscle in extra-junctional regions. PMID:20883790

  20. Diurnal and directional responses of chlorophyll fluorescence and pri in a cornfield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two high spectral resolution reflectance-based indices were used to assess whether vegetation in a cornfield was performing near-optimally or exhibiting symptoms of environmental stress. These were the Photochemical Reflectance Index (PRI) and solar-induced Chlorophyll Fluorescence (SIF). This study...

  1. Dimeric structure of the N-terminal domain of PriB protein from Thermoanaerobacter tengcongensis solved ab initio

    SciTech Connect

    Liebschner, Dorothee; Brzezinski, Krzysztof; Dauter, Miroslawa; Dauter, Zbigniew; Nowak, Marta; Kur, Józef; Olszewski, Marcin

    2012-12-01

    The N-terminal domain of the PriB protein from the thermophilic bacterium T. tengcongensis (TtePriB) was expressed and its crystal structure has been solved at the atomic resolution of 1.09 Å by direct methods. PriB is one of the components of the bacterial primosome, which catalyzes the reactivation of stalled replication forks at sites of DNA damage. The N-terminal domain of the PriB protein from the thermophilic bacterium Thermoanaerobacter tengcongensis (TtePriB) was expressed and its crystal structure was solved at the atomic resolution of 1.09 Å by direct methods. The protein chain, which encompasses the first 104 residues of the full 220-residue protein, adopts the characteristic oligonucleotide/oligosaccharide-binding (OB) structure consisting of a five-stranded β-barrel filled with hydrophobic residues and equipped with four loops extending from the barrel. In the crystal two protomers dimerize, forming a six-stranded antiparallel β-sheet. The structure of the N-terminal OB domain of T. tengcongensis shows significant differences compared with mesophile PriBs. While in all other known structures of PriB a dimer is formed by two identical OB domains in separate chains, TtePriB contains two consecutive OB domains in one chain. However, sequence comparison of both the N-terminal and the C-terminal domains of TtePriB suggests that they have analogous structures and that the natural protein possesses a structure similar to a dimer of two N-terminal domains.

  2. Functional interactions between polypyrimidine tract binding protein and PRI peptide ligand containing proteins.

    PubMed

    Coelho, Miguel B; Ascher, David B; Gooding, Clare; Lang, Emma; Maude, Hannah; Turner, David; Llorian, Miriam; Pires, Douglas E V; Attig, Jan; Smith, Christopher W J

    2016-08-15

    Polypyrimidine tract binding protein (PTBP1) is a heterogeneous nuclear ribonucleoprotein (hnRNP) that plays roles in most stages of the life-cycle of pre-mRNA and mRNAs in the nucleus and cytoplasm. PTBP1 has four RNA binding domains of the RNA recognition motif (RRM) family, each of which can bind to pyrimidine motifs. In addition, RRM2 can interact via its dorsal surface with proteins containing short peptide ligands known as PTB RRM2 interacting (PRI) motifs, originally found in the protein Raver1. Here we review our recent progress in understanding the interactions of PTB with RNA and with various proteins containing PRI ligands. PMID:27528752

  3. Remote detection of water stress conditions via a diurnal photochemical reflectance index (PRI) improves yield prediction in rainfed wheat

    NASA Astrophysics Data System (ADS)

    Magney, T. S.; Vierling, L. A.; Eitel, J.

    2014-12-01

    Employing remotely sensed techniques to quantify the existence and magnitude of midday photosynthetic downregulation using the photochemical reflectance index (PRI) may reveal new information about plant responses to abiotic stressors in space and time. However, the interpretation and application of the PRI can be confounded because of its sensitivity to several variables changing at the diurnal (e.g., irradiation, shadow fraction) and seasonal (e.g., leaf area, chlorophyll and carotene pigment concentrations, irradiation) time scales. We explored different techniques to correct the PRI for variations in canopy structure and relative chlorophyll content (ChlR) using highly temporally resolved (frequency = five minutes) in-situ radiometric measurements of PRI and the Normalized Difference Vegetation Index (NDVI) over eight soft white spring wheat (Triticum aestivum L.)field plots under varying nitrogen and soil water conditions over two seasons. Our results suggest that the influence of seasonal variation in canopy ChlR and LAI on the diurnally measured PRI (PRIdiurnal) can be minimized using simple correction techniques, therefore improving the strength of PRI as a tool to quantify abiotic stressors such as daily changes in soil volumetric water content (SVWC), and vapor pressure deficit (VPD). PRIdiurnal responded strongly to available nitrogen, and linearly tracked seasonal changes in SVWC, VPD, and stomatal conductance (gc). Utilizing the PRI as an indicator of stress, yield predictions significantly over greenness indices such as the NDVI. This study provides insight towards the future interpretation and scaling of PRI to quantify rapid changes in photosynthesis, and as an indicator of plant stress.

  4. The crystal structure of Neisseria gonorrhoeae PriB reveals mechanistic differences among bacterial DNA replication restart pathways

    SciTech Connect

    Dong, Jinlan; George, Nicholas P.; Duckett, Katrina L.; DeBeer, Madeleine A.P.; Lopper, Matthew E.

    2010-05-25

    Reactivation of repaired DNA replication forks is essential for complete duplication of bacterial genomes. However, not all bacteria encode homologs of the well-studied Escherichia coli DNA replication restart primosome proteins, suggesting that there might be distinct mechanistic differences among DNA replication restart pathways in diverse bacteria. Since reactivation of repaired DNA replication forks requires coordinated DNA and protein binding by DNA replication restart primosome proteins, we determined the crystal structure of Neisseria gonorrhoeae PriB at 2.7 {angstrom} resolution and investigated its ability to physically interact with DNA and PriA helicase. Comparison of the crystal structures of PriB from N. gonorrhoeae and E. coli reveals a well-conserved homodimeric structure consisting of two oligosaccharide/oligonucleotide-binding (OB) folds. In spite of their overall structural similarity, there is significant species variation in the type and distribution of surface amino acid residues. This correlates with striking differences in the affinity with which each PriB homolog binds single-stranded DNA and PriA helicase. These results provide evidence that mechanisms of DNA replication restart are not identical across diverse species and that these pathways have likely become specialized to meet the needs of individual organisms.

  5. Blocking the maturation of OncomiRNAs using pri-miRNA-17∼92 aptamer in retinoblastoma.

    PubMed

    Subramanian, Nithya; Kanwar, Jagat R; Kanwar, Rupinder K; Krishnakumar, Subramanian

    2015-02-01

    The miR-17∼92. or oncomiR-1, cluster encodes oncogenic microRNAs (miRNAs), and it also promotes retinoblastoma (RB) tumor formation. Antagomir and miRNA mimics based approaches are widely tried against oncogenic and tumor suppressive miRNAs. Other methods for targeting cancer related miRNAs are still under development. In the current study, we focused on the pri-miRNA-17∼92 aptamer (pri-apt), which can potentially replace the mix of five antagomirs by one aptamer that function to abrogate the maturation of miR-17, miR-18a, and miR-19b (P<0.05) for targeting RB. We used RB cell lines WERI-Rb1 and Y79 as an in vitro model. Cellular changes upon transfecting the pri-apt led to S-phase arrest in WERI-Rb1 cells and onset of apoptosis in both Y79 and WERI-Rb1 cell lines. There was increased cytotoxicity as measured by lactate dehydrogenase activity in pri-apt treated Y79 cells (P<0.05), and significant inhibition of cell proliferation was observed in both of the cell lines. Thus we showed the antiproliferative property of pri-apt in RB cell lines, which can be readily modified by developing appropriate vectors for the delivery of the aptamer specifically to cancer cells. PMID:25513843

  6. Blocking the Maturation of OncomiRNAs Using pri-miRNA-17∼92 Aptamer in Retinoblastoma

    PubMed Central

    Subramanian, Nithya; Kanwar, Jagat R.; Kanwar, Rupinder K.

    2015-01-01

    The miR-17∼92. or oncomiR-1, cluster encodes oncogenic microRNAs (miRNAs), and it also promotes retinoblastoma (RB) tumor formation. Antagomir and miRNA mimics based approaches are widely tried against oncogenic and tumor suppressive miRNAs. Other methods for targeting cancer related miRNAs are still under development. In the current study, we focused on the pri-miRNA-17∼92 aptamer (pri-apt), which can potentially replace the mix of five antagomirs by one aptamer that function to abrogate the maturation of miR-17, miR-18a, and miR-19b (P<0.05) for targeting RB. We used RB cell lines WERI-Rb1 and Y79 as an in vitro model. Cellular changes upon transfecting the pri-apt led to S-phase arrest in WERI-Rb1 cells and onset of apoptosis in both Y79 and WERI-Rb1 cell lines. There was increased cytotoxicity as measured by lactate dehydrogenase activity in pri-apt treated Y79 cells (P<0.05), and significant inhibition of cell proliferation was observed in both of the cell lines. Thus we showed the antiproliferative property of pri-apt in RB cell lines, which can be readily modified by developing appropriate vectors for the delivery of the aptamer specifically to cancer cells. PMID:25513843

  7. Use of ERS SAR interferometric coherence and PRI images to evaluate crop height and soil moisture and to identify crops

    NASA Astrophysics Data System (ADS)

    Moeremans, Benoit; Dautrebande, Sylvia

    1998-12-01

    The aim of the present project was to identify the capabilities of multitemporal ERS SAR interferometric coherence and PRI images to evaluate soil moisture, to estimate crop height and to identify crops for four crop types (winter wheat, potato, sugar beet and maize) and for different pilot fields. The coherence images acquired during the winter and spring seasons can be used to identify bare or nearly bare fields with a threshold value, and then PRI images were used to quantify soil moisture value for each bare field. The coherence images acquired during the growing season were used to evaluate crop height for each studied crop type. Moreover, the coherence image provided some additional information to PRI images for the crop type identification. This study was carried out in the framework of the PRODEX program financed by the Belgian Federal Office for Scientific, Technical and Cultural affairs (OSTC) and the European Space Agency (ESA).

  8. Explaining the variability of Photochemical Reflectance Index (PRI): deconvolution of variability related to Light Use Efficiency and Canopy attributes.

    NASA Astrophysics Data System (ADS)

    Merlier, Elodie; Hmimina, Gabriel; Dufrêne, Eric; Soudani, Kamel

    2014-05-01

    The Photochemical Reflectance Index (PRI) was designed as a proxy of the state of xanthophyll cycle which is used as a response of plants to excess of light (Gamon et al., 1990; 1992). Strong relationships between PRI and LUE were shown at leaf and canopy scales and over a wide range of species (Garbulsky et al., 2011). However, its use at canopy scale was shown to be significantly hampered by effects of confounding factors such as the PRI sensitivity to leaf pigment content (Gamon et al. 2001; Nakaji et al. 2006) and to canopy structure (Hilker et al. 2008). Several approaches aimed at correcting such effects and recent works focused on the deconvolution of LUE related and LUE unrelated PRI variability (Rahimzadeh-Bajgiran et al. 2012).In this study, the PRI variability at canopy scale is investigated over two years on three species (Fagus sylvatica, Quercus robur and Pinus sylvestris) growing under two water regimes. At daily scale, PRI variability is mainly explained by radiation conditions. As already reported at leaf scale in Hmimina et al. (2014), analysis of PRI responses to incoming photosynthetically active radiation over seasonal scale allowed to separate two sources of variability : a constitutive variability mainly related to canopy structure and leaf chlorophyll content and a facultative variability mainly related to LUE and soil moisture content. These results highlight the composite nature of PRI signal measured at canopy scale and the importance of disentangling its sources of variability in order to accurately assess ecosystem light use efficiency. Gamon JA, Field CB, Bilger W, Björkman O, Fredeen AL, Peñuelas J. 1990. Remote sensing of the xanthophyll cycle and chlorophyll fluorescence in sunflower leaves and canopies. Oecologia 85, 1-7. Gamon JA, Field CB, Fredeen A AL, Thayer S. 2001. Assessing photosynthetic downregulation in sunflower stands with an optically-based model. Photosynthesis Research 67, 113-125. Gamon JA, Peñuelas J, Field CB

  9. SDZ PRI 053, an orally bioavailable human immunodeficiency virus type 1 proteinase inhibitor containing the 2-aminobenzylstatine moiety.

    PubMed Central

    Billich, A; Fricker, G; Müller, I; Donatsch, P; Ettmayer, P; Gstach, H; Lehr, P; Peichl, P; Scholz, D; Rosenwirth, B

    1995-01-01

    A series of inhibitors of human immunodeficiency virus type 1 (HIV-1) proteinase containing the 2-aralkyl-amino-substituted statine moiety as a novel transition-state analog was synthesized, with the aim to obtain compounds which combine anti-HIV potency with oral bioavailability. The reduced-size 2-aminobenzylstatine derivative SDZ PRI 053, which contains 2-(S)-amino-3-(R)-hydroxyindane in place of an amino acid amide, is a potent and orally bioavailable inhibitor of HIV-1 replication. The antiviral activity of SDZ PRI 053 was demonstrated in various cell lines, in primary lymphocytes, and in primary monocytes, against laboratory strains as well as clinical HIV-1 isolates (50% effective dose = 0.028 to 0.15 microM). Cell proliferation was impaired only at 100- to 300-fold-higher concentrations. The mechanism of antiviral action of the proteinase inhibitor SDZ PRI 0.53 was demonstrated to be inhibition of gag precursor protein processing. The finding that the inhibitory potency of SDZ PRI 053 in chronic virus infection, determined by p24 release, was considerably lower than that in de novo infection may be explained by the fact that the virus particles produced in the presence of SDZ PRI 053 are about 50-fold less infectious than those from untreated cultures. Upon intravenous administration, half-lives in blood of 100 and 32 min in mice and rats, respectively, were measured. Oral bioavailability of SDZ PRI 053 in rodents was 20 to 60%, depending on the dose. In mice, rats, and dogs, the inhibitor levels after oral administration remained far above the concentrations needed to efficiently block HIV replication in vitro for a prolonged period. This compound is thus a promising candidate for clinical use in HIV disease. PMID:7492076

  10. Assessing canopy PRI from airborne imagery to map water stress in maize

    NASA Astrophysics Data System (ADS)

    Rossini, M.; Fava, F.; Cogliati, S.; Meroni, M.; Marchesi, A.; Panigada, C.; Giardino, C.; Busetto, L.; Migliavacca, M.; Amaducci, S.; Colombo, R.

    2013-12-01

    This paper presents a method for mapping water stress in a maize field using hyperspectral remote sensing imagery. An airborne survey using AISA (Specim, Finland) was performed in July 2008 over an experimental farm in Italy. Hyperspectral data were acquired over a maize field with three different irrigation regimes. An intensive field campaign was also conducted concurrently with imagery acquisition to measure relative leaf water content (RWC), active chlorophyll fluorescence (ΔF/Fm‧), leaf temperature (Tl) and Leaf Area Index (LAI). The analysis of the field data showed that at the time of the airborne overpass the maize plots with irrigation deficits were experiencing a moderate water stress, affecting the plant physiological status (ΔF/Fm‧, difference between Tl and air temperature (Tair), and RWC) but not the canopy structure (LAI). Among the different Vegetation Indices (VIs) computed from the airborne imagery the Photochemical Reflectance Index computed using the reflectance at 570 nm as the reference band (PRI570) showed the strongest relationships with ΔF/Fm‧ (r2 = 0.76), Tl - Tair (r2 = 0.82) and RWC (r2 = 0.64) and the red-edge Chlorophyll Index (CIred-edge) with LAI (r2 = 0.64). Thus PRI has been proven to be related to water stress at early stages, before structural changes occurred.

  11. Remote sensing of plant emissions of volatile isoprenoids with PRI. Prospects for upscaling (Invited)

    NASA Astrophysics Data System (ADS)

    Penuelas, J.

    2013-12-01

    Josep Peñuelas*1,2, Giovanni Marino1,2,3,4, Joan LLusia1,2, Catherine Morfopoulos1,2,5, Gerard Farre-Armengol1,2, Shawn Kefauver, Alex Guenther6 , Francesca Rapparini7 , Roger Seco1,2,6, Marc Estiarte1,2, Mónica Mejia-Chang1,2, Romà Ogaya1,2, Jordi Sardans1,2 , Andrew Turnipseed6, Peter Harley6, Osvaldo Facini7, Rita Baraldi7, Jim Greenberg6 , Iolanda Filella1,2 1 CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallés 08193, Catalonia, Spain 2 CREAF, Cerdanyola del Vallés 08193, Catalonia, Spain 3 Dipartimento di Bioscienze e Territorio, Università degli Studi del Molise, Contrada Fonte Lappone, 86090 Pesche (IS), Italy 4 Institute for Plant Protection, National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy 5 Division of Ecology and Evolution, Imperial College, Silwood Park, Ascot, SL5 7PY, UK 6 Atmospheric Chemistry Division, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, USA 7 Biometeorology Institute, IBIMET-CNR, Via P. Gobetti 101, Bologna, Italy Abstract Terrestrial plants re-emit around 1-2% of the carbon they fix as isoprene and monoterpenes. These emissions play major roles in the ecological relationships among living organisms and in atmospheric chemistry and climate, and yet their actual quantification at the ecosystem level in different regions is far from being resolved. Phenomenological models are used to estimate the emission rates, but the limited understanding of the function and regulation of these emissions leads to large uncertainties in such estimations. Many measurements have been made at the foliar but few at the ecosystem level, and those that do exist are limited in space and time. We here provide evidence that a simple remote sensing index, the photochemical reflectance index (PRI), which is indicative of light use efficiency (LUE), is a good indirect estimator of foliar isoprenoid emissions and therefore can be used to sense them remotely. These results open

  12. Developmentally regulated expression and complex processing of barley pri-microRNAs

    PubMed Central

    2013-01-01

    Background MicroRNAs (miRNAs) regulate gene expression via mRNA cleavage or translation inhibition. In spite of barley being a cereal of great economic importance, very little data is available concerning its miRNA biogenesis. There are 69 barley miRNA and 67 pre-miRNA sequences available in the miRBase (release 19). However, no barley pri-miRNA and MIR gene structures have been shown experimentally. In the present paper, we examine the biogenesis of selected barley miRNAs and the developmental regulation of their pri-miRNA processing to learn more about miRNA maturation in barely. Results To investigate the organization of barley microRNA genes, nine microRNAs - 156g, 159b, 166n, 168a-5p/168a-3p, 171e, 397b-3p, 1120, and 1126 - were selected. Two of the studied miRNAs originate from one MIR168a-5p/168a-3p gene. The presence of all miRNAs was confirmed using a Northern blot approach. The miRNAs are encoded by genes with diverse organizations, representing mostly independent transcription units with or without introns. The intron-containing miRNA transcripts undergo complex splicing events to generate various spliced isoforms. We identified miRNAs that were encoded within introns of the noncoding genes MIR156g and MIR1126. Interestingly, the intron that encodes miR156g is spliced less efficiently than the intron encoding miR1126 from their specific precursors. miR397b-3p was detected in barley as a most probable functional miRNA, in contrast to rice where it has been identified as a complementary partner miRNA*. In the case of miR168a-5p/168a-3p, we found the generation of stable, mature molecules from both pre-miRNA arms, confirming evolutionary conservation of the stability of both species, as shown in rice and maize. We suggest that miR1120, located within the 3′ UTR of a protein-coding gene and described as a functional miRNA in wheat, may represent a siRNA generated from a mariner-like transposable element. Conclusions Seven of the eight barley miRNA genes

  13. The PriA Replication Restart Protein Blocks Replicase Access Prior to Helicase Assembly and Directs Template Specificity through Its ATPase Activity*

    PubMed Central

    Manhart, Carol M.; McHenry, Charles S.

    2013-01-01

    The PriA protein serves as an initiator for the restart of DNA replication on stalled replication forks and as a checkpoint protein that prevents the replicase from advancing in a strand displacement reaction on forks that do not contain a functional replicative helicase. We have developed a primosomal protein-dependent fluorescence resonance energy transfer (FRET) assay using a minimal fork substrate composed of synthetic oligonucleotides. We demonstrate that a self-loading reaction, which proceeds at high helicase concentrations, occurs by threading of a preassembled helicase over free 5′-ends, an event that can be blocked by attaching a steric block to the 5′-end or coating DNA with single-stranded DNA binding protein. The specificity of PriA for replication forks is regulated by its intrinsic ATPase. ATPase-defective PriA K230R shows a strong preference for substrates that contain no gap between the leading strand and the duplex portion of the fork, as demonstrated previously. Wild-type PriA prefers substrates with larger gaps, showing maximal activity on substrates on which PriA K230R is inactive. We demonstrate that PriA blocks replicase function on forks by blocking its binding. PMID:23264623

  14. siRNA release from pri-miRNA scaffolds is controlled by the sequence and structure of RNA.

    PubMed

    Galka-Marciniak, Paulina; Olejniczak, Marta; Starega-Roslan, Julia; Szczesniak, Michal W; Makalowska, Izabela; Krzyzosiak, Wlodzimierz J

    2016-04-01

    shmiRs are pri-miRNA-based RNA interference triggers from which exogenous siRNAs are expressed in cells to silence target genes. These reagents are very promising tools in RNAi in vivo applications due to their good activity profile and lower toxicity than observed for other vector-based reagents such as shRNAs. In this study, using high-resolution northern blotting and small RNA sequencing, we investigated the precision with which RNases Drosha and Dicer process shmiRs. The fidelity of siRNA release from the commonly used pri-miRNA shuttles was found to depend on both the siRNA insert and the pri-miR scaffold. Then, we searched for specific factors that may affect the precision of siRNA release and found that both the structural features of shmiR hairpins and the nucleotide sequence at Drosha and Dicer processing sites contribute to cleavage site selection and cleavage precision. An analysis of multiple shRNA intermediates generated from several reagents revealed the complexity of shmiR processing by Drosha and demonstrated that Dicer selects substrates for further processing. Aside from providing new basic knowledge regarding the specificity of nucleases involved in miRNA biogenesis, our results facilitate the rational design of more efficient genetic reagents for RNAi technology. PMID:26921501

  15. mirEX: a platform for comparative exploration of plant pri-miRNA expression data.

    PubMed

    Bielewicz, Dawid; Dolata, Jakub; Zielezinski, Andrzej; Alaba, Sylwia; Szarzynska, Bogna; Szczesniak, Michal W; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia; Karlowski, Wojciech M

    2012-01-01

    mirEX is a comprehensive platform for comparative analysis of primary microRNA expression data. RT-qPCR-based gene expression profiles are stored in a universal and expandable database scheme and wrapped by an intuitive user-friendly interface. A new way of accessing gene expression data in mirEX includes a simple mouse operated querying system and dynamic graphs for data mining analyses. In contrast to other publicly available databases, the mirEX interface allows a simultaneous comparison of expression levels between various microRNA genes in diverse organs and developmental stages. Currently, mirEX integrates information about the expression profile of 190 Arabidopsis thaliana pri-miRNAs in seven different developmental stages: seeds, seedlings and various organs of mature plants. Additionally, by providing RNA structural models, publicly available deep sequencing results, experimental procedure details and careful selection of auxiliary data in the form of web links, mirEX can function as a one-stop solution for Arabidopsis microRNA information. A web-based mirEX interface can be accessed at http://bioinfo.amu.edu.pl/mirex. PMID:22013167

  16. Binding Specificity of E. coli SSB protein for the χ subunit of DNA pol III Holoenzyme and PriA helicase.†

    PubMed Central

    Kozlov, Alexander G.; Jezewska, Maria J.; Bujalowski, Wlodzimierz; Lohman, Timothy M.

    2010-01-01

    The E. coli single stranded DNA binding (SSB) protein plays a central role in DNA metabolism through its high affinity interactions with ssDNA, as well as its interactions with numerous other proteins via its unstructured C-termini. Although SSB interacts with at least 14 other proteins, it is not understood how SSB might recruit one protein over another for a particular metabolic role. To probe the specificity of these interactions we have used isothermal titration calorimetry to examine the thermodynamics of binding of SSB to two E. coli proteins important for DNA replication, the χ subunit of DNA polymerase III holoenzyme and the PriA helicase. We find that an SSB tetramer can bind up to four molecules of either protein primarily via interactions with the last ~ 9 amino acids in the conserved SSB C-terminal tails (SSB-Ct). We observe intrinsic specificity for the binding of an isolated SSB-Ct peptide to PriA over χ due primarily to a more favorable enthalpic component. PriA and χ also bind with weaker affinity to SSB (in the absence of ssDNA) than to isolated SSB-Ct peptides, indicating an inhibitory effect of the SSB protein core. Although the binding affinity of SSB for both χ and PriA is enhanced if SSB is prebound to ssDNA, this effect is larger with PriA indicating a further enhancement of SSB specificity for PriA. These results also suggest that DNA binding proteins such as PriA, which also interact with SSB, could use this interaction to gain access to ssDNA by first interacting with the SSB C-termini. PMID:20329707

  17. Linking chlorophyll fluorescence, hyperspectral reflectance and plant physiological responses to detect stress using the photochemical reflectance index (PRI) (Invited)

    NASA Astrophysics Data System (ADS)

    Naumann, J. C.; Young, D.; Anderson, J.

    2009-12-01

    The concept of using vegetation as sentinels to indicate natural or anthropogenic stress is not new and could potentially provide an ideal mechanism for large-scale detection. Advances in fluorescence spectroscopy and reflectance-derived fluorescence have made possible earlier detection of stress in plants, especially before changes in chlorophyll content are visible. Our studies have been used to fuse leaf fluorescence and reflectance characteristics to remotely sense and rapidly detect vegetation stress and terrain characteristics. Laboratory studies have indicated that light-adapted fluorescence (ΔF/F‧m) measurements have been successful in all experiments at detecting stress from flooding, salinity, drought, herbicide and TNT contamination prior to visible signs of damage. ΔF/F‧m was related to plant physiological status in natural stress conditions, as seen in the relationships with stomatal conductance and photosynthesis The photochemical reflectance index (PRI) and other reflectance ratios were effective at tracking changes in ΔF/F‧m at the leaf and canopy-level scales. At the landscape-level, chlorophyll fluorescence and airborne reflectance imagery were used to evaluate spatial variations in stress in the dominant shrub on a barrier island, Myrica cerifera, during a severe drought and compared to an extremely wet year. Measurements of relative water content and the water band index (WBI970) indicated that water stress did not vary across the island. In contrast, there were significant differences in tissue chlorides across sites. Using PRI we were able to detect salinity stress across the landscape. PRI did not differ between wet and dry years. There was a positive relationship between PRI and ΔF/F‧m for M. cerifera (r2 = 0.79). The normalized difference vegetation index (NDVI), the chlorophyll index (CI) and WBI970 were higher during the wet summer but varied little across the island. PRI was not significantly related to NDVI, suggesting that

  18. Dysfunctional Presynaptic M2 Receptors in the Presence of Chronically High Acetylcholine Levels: Data from the PRiMA Knockout Mouse

    PubMed Central

    Mohr, Franziska; Krejci, Eric; Zimmermann, Martina; Klein, Jochen

    2015-01-01

    The muscarinic M2 receptor (M2R) acts as a negative feedback regulator in central cholinergic systems. Activation of the M2 receptor limits acetylcholine (ACh) release, especially when ACh levels are increased because acetylcholinesterase (AChE) activity is acutely inhibited. Chronically high ACh levels in the extracellular space, however, were reported to down-regulate M2R to various degrees. In the present study, we used the PRiMA knockout mouse which develops severely reduced AChE activity postnatally to investigate ACh release, and we used microdialysis to investigate whether the function of M2R to reduce ACh release in vivo was impaired in adult PRiMA knockout mice. We first show that striatal and hippocampal ACh levels, while strongly increased, still respond to AChE inhibitors. Infusion or injection of oxotremorine, a muscarinic M2 agonist, reduced ACh levels in wild-type mice but did not significantly affect ACh levels in PRiMA knockout mice or in wild-type mice in which ACh levels were artificially increased by infusion of neostigmine. Scopolamine, a muscarinic antagonist, increased ACh levels in wild-type mice receiving neostigmine, but not in wild-type mice or in PRiMA knockout mice. These results demonstrate that M2R are dysfunctional and do not affect ACh levels in PRiMA knockout mice, likely because of down-regulation and/or loss of receptor-effector coupling. Remarkably, this loss of function does not affect cognitive functions in PRiMA knockout mice. Our results are discussed in the context of AChE inhibitor therapy as used in dementia. PMID:26506622

  19. Evaluation of the pri-miR-34b/c rs4938723 polymorphism and its association with breast cancer risk

    PubMed Central

    SANAEI, SARA; HASHEMI, MOHAMMAD; REZAEI, MARYAM; HASHEMI, SEYED MEHDI; BAHARI, GHOLAMREZA; GHAVAMI, SAEID

    2016-01-01

    MicroRNAs (miRNAs or miRs) are a family of small non-coding RNAs that function as oncogenes or tumor suppressor genes. Recent evidence suggests that the pri-miR-34b/c rs4938723 variant is associated with the development of cancer. At present, there is an inconsistent association between the single-nucleotide polymorphism in pri-miR-34b/c and cancer in the limited studies. The present study is a case-control investigation, with 263 breast cancer (BC) patients and 221 control women, which examined the potential association of the pri-miR-34b/c rs4938723 polymorphisms with BC susceptibility. The polymorphisms were genotyped by the polymerase chain reaction restriction fragment length polymorphism method. No significant association between the pri-miR-34b/c rs4938723 variant and BC was identified [TC vs. TT: Odds ratio (OR), 0.87; 95% confidence interval (CI), 0.60–1.26; P=0.506; CC vs. TT: OR, 1.22; 95% CI, 0.61–2.47; P=0.600; TC+CC vs. TT: OR, 0.91; 95% CI, 0.64–1.31; P=0.648; CC vs. TT+TC: OR, 1.32; 95% CI, 0.67–2.59; P=0.498; C vs. T: OR, 0.99; 95% CI, 0.75–1.31; P=0.986]. However, a significant association was observed between the pri-miR-34b/c rs4938723 genotypes and clinicopathological characteristics, such a grade, progesterone receptor and human epidermal growth factor receptor 2 status were observed (P<0.05). These findings suggest that the pri-miR-34b/c rs4938723 variant may not be a risk factor for the development of BC. PMID:27347415

  20. Transcriptional, post-transcriptional and chromatin-associated regulation of pri-miRNAs, pre-miRNAs and moRNAs.

    PubMed

    Nepal, Chirag; Coolen, Marion; Hadzhiev, Yavor; Cussigh, Delphine; Mydel, Piotr; Steen, Vidar M; Carninci, Piero; Andersen, Jesper B; Bally-Cuif, Laure; Müller, Ferenc; Lenhard, Boris

    2016-04-20

    MicroRNAs (miRNAs) play a major role in the post-transcriptional regulation of target genes, especially in development and differentiation. Our understanding about the transcriptional regulation of miRNA genes is limited by inadequate annotation of primary miRNA (pri-miRNA) transcripts. Here, we used CAGE-seq and RNA-seq to provide genome-wide identification of the pri-miRNA core promoter repertoire and its dynamic usage during zebrafish embryogenesis. We assigned pri-miRNA promoters to 152 precursor-miRNAs (pre-miRNAs), the majority of which were supported by promoter associated post-translational histone modifications (H3K4me3, H2A.Z) and RNA polymerase II (RNAPII) occupancy. We validated seven miR-9 pri-miRNAs byin situhybridization and showed similar expression patterns as mature miR-9. In addition, processing of an alternative intronic promoter ofmiR-9-5was validated by 5' RACE PCR. Developmental profiling revealed a subset of pri-miRNAs that are maternally inherited. Moreover, we show that promoter-associated H3K4me3, H2A.Z and RNAPII marks are not only present at pri-miRNA promoters but are also specifically enriched at pre-miRNAs, suggesting chromatin level regulation of pre-miRNAs. Furthermore, we demonstrated that CAGE-seq also detects 3'-end processing of pre-miRNAs on Drosha cleavage site that correlates with miRNA-offset RNAs (moRNAs) production and provides a new tool for detecting Drosha processing events and predicting pre-miRNA processing by a genome-wide assay. PMID:26673698

  1. Pri-let-7a-1 rs10739971 polymorphism is associated with gastric cancer prognosis and might affect mature let-7a expression

    PubMed Central

    Li, Ying; Xu, Qian; Liu, Jingwei; He, Caiyun; Yuan, Quan; Xing, Chengzhong; Yuan, Yuan

    2016-01-01

    The relationship between the pri-let-7a-1 rs10739971 polymorphism and gastric cancer (GC) risk has been reported. However, the role of this polymorphism in the prognosis of GC remains largely elusive. Sequenom MassARRAY platform method and the polymerase chain reaction (PCR)-restriction fragment length polymorphism were used to investigate pri-let-7a-1 rs10739971 G→A in 334 GC patients. Real-time PCR detected expression of mature let-7a in serum and tissue. Patients with AA or GA+AA genotypes of the pri-let-7a-1 rs10739971 polymorphism demonstrated significantly longer survival time than those with the wild GG genotype. Stratified analysis indicated that survival time was significantly longer in women with AA or GA+AA genotypes and in Borrmann type I/II patients with GA heterozygote or GA+AA genotypes. AA genotype was more frequent in the lymphatic-metastasis-negative subgroup. Serum mature let-7a expression in healthy people with the GA heterozygote and the GA+AA genotype was higher than in those with the GG genotype, and the difference remained significant in the female healthy subgroup. Pri-let-7a-1 rs10739971 polymorphism might be a biomarker for GC prognosis, especially for female and Borrmann type I/II patients. The pri-let-7a-1 rs10739971 polymorphism might affect serum mature let-7a expression, and partly explain the mechanism of the relationship between the pri-let-7a-1 rs10739971 polymorphism and GC survival. PMID:27445488

  2. Interfacial magnetic anisotropy of Co90Zr10 on Pt layer.

    PubMed

    Kil, Joon Pyo; Bae, Gi Yeol; Suh, Dong Ik; Choi, Won Joon; Noh, Jae Sung; Park, Wanjun

    2014-11-01

    Spin Transfer Torque (STT) is of great interest in data writing scheme for the Magneto-resistive Random Access Memory (MRAM) using Magnetic Tunnel Junction (MTJ). Scalability for high density memory requires ferromagnetic electrodes having the perpendicular magnetic easy axis. We investigated CoZr as the ferromagnetic electrode. It is observed that interfacial magnetic anisotropy is preferred perpendicular to the plane with thickness dependence on the interfaces with Pt layer. The anisotropy energy (K(u)) with thickness dependence shows a change of magnetic-easy-axis direction from perpendicular to in-plane around 1.2 nm of CoZr. The interfacial anisotropy (K(i)) as the directly related parameters to switching and thermal stability, are estimated as 1.64 erg/cm2 from CoZr/Pt multilayered system. PMID:25958513

  3. RecG protein and single-strand DNA exonucleases avoid cell lethality associated with PriA helicase activity in Escherichia coli.

    PubMed

    Rudolph, Christian J; Mahdi, Akeel A; Upton, Amy L; Lloyd, Robert G

    2010-10-01

    Replication of the Escherichia coli chromosome usually initiates at a single origin (oriC) under control of DnaA. Two forks are established and move away in opposite directions. Replication is completed when these meet in a broadly defined terminus area half way around the circular chromosome. RecG appears to consolidate this arrangement by unwinding D-loops and R-loops that PriA might otherwise exploit to initiate replication at other sites. It has been suggested that without RecG such replication generates 3' flaps as the additional forks collide and displace nascent leading strands, providing yet more potential targets for PriA. Here we show that, to stay alive, cells must have either RecG or a 3' single-stranded DNA (ssDNA) exonuclease, which can be exonuclease I, exonuclease VII, or SbcCD. Cells lacking all three nucleases are inviable without RecG. They also need RecA recombinase and a Holliday junction resolvase to survive rapid growth, but SOS induction, although elevated, is not required. Additional requirements for Rep and UvrD are identified and linked with defects in DNA mismatch repair and with the ability to cope with conflicts between replication and transcription, respectively. Eliminating PriA helicase activity removes the requirement for RecG. The data are consistent with RecG and ssDNA exonucleases acting to limit PriA-mediated re-replication of the chromosome and the consequent generation of linear DNA branches that provoke recombination and delay chromosome segregation. PMID:20647503

  4. Identification and Analysis of Genetic Variations in Pri-MiRNAs Expressed Specifically or at a High Level in Sheep Skeletal Muscle

    PubMed Central

    Zhang, Wei; Wang, Limin; Zhou, Ping; Song, Guangchao; Shen, Min; Gan, Shangquan; Shi, Guoqing

    2015-01-01

    MicroRNAs (miRNAs) are key regulators in miRNA-mediated gene regulatory networks and play important roles in many biological processes, such as growth and development of mammals. In this study, we used microarrays to detect 261 miRNAs that are expressed in sheep skeletal muscle. We found 22 miRNAs that showed high levels of expression and equated to 89% of the total miRNA. Genetic variations in these 22 pri-miRNAs were further investigated using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing. A total of 49 genetic variations, which included 41 single nucleotide polymorphisms (SNPs) and 8 deletions/insertions, were identified in four sheep breeds. Three variations were further researched in a larger sample set, including five sheep breeds with different meat production performances. We found that the genotype and allele frequencies of the CCC deletion/insertion in pri-miR-133a were significantly related to the sheep meat production trait. Finally, cell assays and quantitative reverse transcription PCR (qRT-PCR) were employed to investigate the effect of pri-miRNA genetic variation on the miRNA biogenesis process. The results confirmed that genetic variations can influence miRNA biogenesis and increase or decrease the levels of mature miRNAs, in accordance with the energy and stability change of hair-pin secondary structures. Our findings will help to further the understanding of the functions of genetic variations in sheep pri-miRNAs in skeletal muscle growth and development. PMID:25699993

  5. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring.

    PubMed

    Fréchette, Emmanuelle; Wong, Christopher Y S; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-12-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI-LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. PMID:26386258

  6. Assessing Steady-state Fluorescence and PRI from Hyperspectral Proximal Sensing as Early Indicators of Plant Stress: The Case of Ozone Exposure

    PubMed Central

    Meroni, Michele; Rossini, Micol; Picchi, Valentina; Panigada, Cinzia; Cogliati, Sergio; Nali, Cristina; Colombo, Roberto

    2008-01-01

    High spectral resolution spectrometers were used to detect optical signals of ongoing plant stress in potted white clover canopies subjected to ozone fumigation. The case of ozone stress is used in this manuscript as a paradigm of oxidative stress. Steady-state fluorescence (Fs) and the Photochemical Reflectance Index (PRI) were investigated as advanced hyperspectral remote sensing techniques able to sense variations in the excess energy dissipation pathways occurring when photosynthesis declines in plants exposed to a stress agent. Fs and PRI were monitored in control and ozone fumigated canopies during a 21-day experiment together with the traditional Normalized Difference Vegetation Index (NDVI) and physiological measurements commonly employed by physiologists to describe stress development (i.e. net CO2 assimilation, active fluorimetry, chlorophyll concentration and visible injuries). It is shown that remote detection of an ongoing stress through Fs and PRI can be achieved in an early phase, characterized by the decline of photosynthesis. On the contrary, NDVI was able to detect the stress only when damage occurred. These results open up new possibilities for assessment of plant stress by means of hyperspectral remote sensing.

  7. Characterization of Staphylococcus aureus Primosomal DnaD Protein: Highly Conserved C-Terminal Region Is Crucial for ssDNA and PriA Helicase Binding but Not for DnaA Protein-Binding and Self-Tetramerization

    PubMed Central

    Huang, Chien-Chih; Huang, Cheng-Yang

    2016-01-01

    The role of DnaD in the recruitment of replicative helicase has been identified. However, knowledge of the DNA, PriA, and DnaA binding mechanism of this protein for the DnaA- and PriA-directed replication primosome assemblies is limited. We characterized the DNA-binding properties of DnaD from Staphylococcus aureus (SaDnaD) and analyzed its interactions with SaPriA and SaDnaA. The gel filtration chromatography analysis of purified SaDnaD and its deletion mutant proteins (SaDnaD1-195, SaDnaD1-200 and SaDnaD1-204) showed a stable tetramer in solution. This finding indicates that the C-terminal region aa 196–228 is not crucial for SaDnaD oligomerization. SaDnaD forms distinct complexes with ssDNA of different lengths. In fluorescence titrations, SaDnaD bound to ssDNA with a binding-site size of approximately 32 nt. A stable complex of SaDnaD1-195, SaDnaD1-200, and SaDnaD1-204 with ssDNA dT40 was undetectable, indicating that the C-terminal region of SaDnaD (particularly aa 205–228) is crucial for ssDNA binding. The SPR results revealed that SaDnaD1-195 can interact with SaDnaA but not with SaPriA, which may indicate that DnaD has different binding sites for PriA and DnaA. Both SaDnaD and SaDnaDY176A mutant proteins, but not SaDnaD1-195, can significantly stimulate the ATPase activity of SaPriA. Hence, the stimulation effect mainly resulted from direct contact within the protein—protein interaction, not via the DNA—protein interaction. Kinetic studies revealed that the SaDnaD-SaPriA interaction increases the Vmax of the SaPriA ATPase fivefold without significantly affecting the Km. These results indicate that the conserved C-terminal region is crucial for ssDNA and PriA helicase binding, but not for DnaA protein-binding and self-tetramerization. PMID:27304067

  8. Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring

    PubMed Central

    Fréchette, Emmanuelle; Wong, Christopher Y. S.; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

    2015-01-01

    In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI–LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. PMID:26386258

  9. Experimental oxygen potentials of U1-yPryO2± x and thermodynamic assessment of the U-Pr-O system

    DOE PAGESBeta

    McMurray, Jake W.; Silva, Chinthaka M.

    2015-12-09

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U1-yPryO2± x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. Furthermore, the models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  10. Experimental oxygen potentials for U1-yPryO2±x and thermodynamic assessment of the U-Pr-O system

    NASA Astrophysics Data System (ADS)

    McMurray, J. W.; Silva, C. M.

    2016-03-01

    Thermogravimetric analysis (TGA) was used to determine the oxygen potentials of fluorite urania-praseodymia (U1-yPryO2±x) solid solutions for y = 0.10 and 0.20 between 1000 and 1500 °C. A thermodynamic assessment of U-Pr-O system was performed using the CALPHAD (CALculation of PHAse Diagrams) method. The models well reproduce the TGA measurements and the computed phase relations are in good agreement with those proposed from an X-ray diffraction investigation.

  11. Quantitative Analysis of Histidine Decarboxylase Gene (hdcA) Transcription and Histamine Production by Streptococcus thermophilus PRI60 under Conditions Relevant to Cheese Making▿†

    PubMed Central

    Rossi, Franca; Gardini, Fausto; Rizzotti, Lucia; La Gioia, Federica; Tabanelli, Giulia; Torriani, Sandra

    2011-01-01

    This study evaluated the influence of parameters relevant for cheese making on histamine formation by Streptococcus thermophilus. Strains possessing a histidine decarboxylase (hdcA) gene represented 6% of the dairy isolates screened. The most histaminogenic, S. thermophilus PRI60, exhibited in skim milk a high basal level of expression of hdcA, upregulation in the presence of free histidine and salt, and repression after thermization. HdcA activity persisted in cell extracts, indicating that histamine might accumulate after cell lysis in cheese. PMID:21378060

  12. Agrobacterium rhizogenes pRi8196 T-DNA: mapping and DNA sequence of functions involved in mannopine synthesis and hairy root differentiation.

    PubMed Central

    Hansen, G; Larribe, M; Vaubert, D; Tempé, J; Biermann, B J; Montoya, A L; Chilton, M D; Brevet, J

    1991-01-01

    This paper presents the map and DNA sequence analysis of pRi8196 transferred DNA (T-DNA) genes encoding root-inducing and mannopine synthesis functions. A canonical 24-base-pair border repeat as well as two "pseudoborders" are present at the functional right T-DNA border. To the left of this border are homologs of the mas1' and mas2' genes of TR pRiA4. Next to these are five open reading frames (ORFs) homologous to ORFs 10-14 of TL of pRiA4. ORFs 10-12 (rolA, rolB, and rolC) are less related to their pRiA4 homologs than are the other large ORFs analyzed here. In contrast to T-DNA genes of pRiA4, pRi8196 T-DNA ORFs 11 and 12 (rolB and rolC) are sufficient to induce hairy roots on carrot disks. Images PMID:1909028

  13. Sun-induced Chlorophyll fluorescence and PRI improve remote sensing GPP estimates under varying nutrient availability in a typical Mediterranean savanna ecosystem

    NASA Astrophysics Data System (ADS)

    Perez-Priego, O.; Guan, J.; Rossini, M.; Fava, F.; Wutzler, T.; Moreno, G.; Carvalhais, N.; Carrara, A.; Kolle, O.; Julitta, T.; Schrumpf, M.; Reichstein, M.; Migliavacca, M.

    2015-07-01

    This study investigates the performances of different optical indices to estimate gross primary production (GPP) of herbaceous stratum in a Mediterranean savanna with different Nitrogen (N) and Phosphorous (P) availability. Sun-induced chlorophyll Fluorescence yield computed at 760 nm (Fy760), scaled-photochemical reflectance index (sPRI), MERIS terrestrial-chlorophyll index (MTCI) and Normalized difference vegetation index (NDVI) were computed from near-surface field spectroscopy measurements collected using high spectral resolution spectrometers covering the visible near-infrared regions. GPP was measured using canopy-chambers on the same locations sampled by the spectrometers. We hypothesized that light-use efficiency (LUE) models driven by remote sensing quantities (RSM) can better track changes in GPP caused by nutrient supplies compared to those driven exclusively by meteorological data (MM). Particularly, we compared the performances of different RSM formulations - relying on the use of Fy760 or sPRI as proxy for LUE and NDVI or MTCI as fraction of absorbed photosynthetically active radiation (fAPAR) - with those of classical MM. Results showed significantly higher GPP in the N fertilized experimental plots during the growing period. These differences in GPP disappeared in the drying period when senescence effects masked out potential differences due to plant N content. Consequently, although MTCI was tightly related to plant N content (r2 = 0.86, p < 0.01), it was poorly related to GPP (r2 = 0.45, p < 0.05). On the contrary sPRI and Fy760 correlated well with GPP during the whole measurement period. Results revealed that the relationship between GPP and Fy760 is not unique across treatments but it is affected by N availability. Results from a cross validation analysis showed that MM (AICcv = 127, MEcv = 0.879) outperformed RSM (AICcv = 140, MEcv = 0.8737) when soil moisture was used to constrain the seasonal dynamic of LUE. However, residual analyses

  14. The RdgC protein of Escherichia coli binds DNA and counters a toxic effect of RecFOR in strains lacking the replication restart protein PriA

    PubMed Central

    Moore, Timothy; McGlynn, Peter; Ngo, Hien-Ping; Sharples, Gary J.; Lloyd, Robert G.

    2003-01-01

    PriA protein provides a means to load the DnaB replicative helicase at DNA replication fork and D loop structures, and is therefore a key factor in the rescue of stalled or broken forks and subsequent replication restart. We show that the nucleoid-associated RdgC protein binds non-specifically to single-stranded (ss) DNA and double-stranded DNA. It is also essential for growth of a strain lacking PriA, indicating that it might affect replication fork progression or fork rescue. dnaC suppressors of priA overcome this inviability, especially when RecF, RecO or RecR is inactivated, indicating that RdgC avoids or counters a toxic effect of these proteins. Mutations modifying ssDNA-binding (SSB) protein also negate this toxic effect, suggesting that the toxicity reflects inappropriate loading of RecA on SSB-coated ssDNA, leading to excessive or untimely RecA activity. We suggest that binding of RdgC to DNA limits RecA loading, avoiding problems at replication forks that would otherwise require PriA to promote replication restart. Mutations in RNA polymerase also reduce the toxic effect of RecFOR, providing a further link between DNA replication, transcription and repair. PMID:12554673

  15. The PRY/SPRY/B30.2 Domain of Butyrophilin 1A1 (BTN1A1) Binds to Xanthine Oxidoreductase

    PubMed Central

    Jeong, Jaekwang; Rao, Anita U.; Xu, Jinling; Ogg, Sherry L.; Hathout, Yetrib; Fenselau, Catherine; Mather, Ian H.

    2009-01-01

    Butyrophilin 1A1 (BTN1A1) and xanthine oxidoreductase (XOR) are highly expressed in the lactating mammary gland and are secreted into milk associated with the milk fat globule membrane (MFGM). Ablation of the genes encoding either protein causes severe defects in the secretion of milk lipid droplets, suggesting that the two proteins may function in the same pathway. Therefore, we determined whether BTN1A1 and XOR directly interact using protein binding assays, surface plasmon resonance analysis, and gel filtration. Bovine XOR bound with high affinity in a pH- and salt-sensitive manner (KD = 101 ± 31 nm in 10 mm HEPES, 150 mm NaCl, pH 7.4) to the PRY/SPRY/B30.2 domain in the cytoplasmic region of bovine BTN1A1. Binding was stoichiometric, with one XOR dimer binding to either two BTN1A1 monomers or one dimer. XOR bound to BTN1A1 orthologs from mice, humans, or cows but not to the cytoplasmic domains of the closely related human paralogs, BTN2A1 or BTN3A1, or to the B30.2 domain of human RoRet (TRIM 38), a protein in the TRIM family. Analysis of the protein composition of the MFGM of wild type and BTN1A1 null mice showed that most of the XOR in mice lacking BTN1A1 was released from the MFGM in a soluble form when the milk lipid droplets were disrupted to prepare membrane, compared with wild-type mice, in which most of the XOR remained membrane-bound. Thus BTN1A1 functions in vivo to stabilize the association of XOR with the MFGM by direct interactions through the PRY/SPRY/B30.2 domain. The potential significance of BTN1A1/XOR interactions in the mammary gland and other tissues is discussed. PMID:19531472

  16. A SNP in pri-miR-10a is associated with recurrent spontaneous abortion in a Han-Chinese population

    PubMed Central

    Zhang, Lu; Lv, Xiao-Dan; Su, Xing; Tian, Shi; Liu, Chun-Mei; Ma, Xu; Xia, Hong-Fei

    2016-01-01

    MicroRNA-10a (miR-10a) has a wide range of functions in nearly all mammalian tissues and is involved in the occurrence of many diseases. However, it remains unknown whether miR-10a is associated with human recurrent spontaneous abortion (RSA). In this study, we found that rs3809783 A > T in miR-10a coding region was significantly associated with the increase of the risk of human unexplained RSA (URSA) acquisition in a Han-Chinese population. The T allele of rs3809783 hindered the production of mature miR-10a. A to T substitution in miR-10a rs3809783 repressed cell proliferation and migratory capacity. Further investigation discovered that Bcl-2-interacting mediator (Bim) was the functional target of miR-10a and inversely regulated Bim expression. Dual-luciferase assay indicated that A allele in miR-10a rs3809783 could more effectively suppress Bim expression than T allele. In addition, A to T substitution in miR-10a rs3809783 attenuated the sensibility of cells to progesterone and its antagonist mifepristone. Collectively, our data suggest that rs3809783 A > T in pri-miR-10a may be conductive to the genetic predisposition to RSA by disrupting the production of mature miR-10a and reinforcing the expression of Bim. PMID:26824181

  17. A SNP in pri-miR-10a is associated with recurrent spontaneous abortion in a Han-Chinese population.

    PubMed

    Li, Ying; Wang, Xue-Qin; Zhang, Lu; Lv, Xiao-Dan; Su, Xing; Tian, Shi; Liu, Chun-Mei; Ma, Xu; Xia, Hong-Fei

    2016-02-16

    MicroRNA-10a (miR-10a) has a wide range of functions in nearly all mammalian tissues and is involved in the occurrence of many diseases. However, it remains unknown whether miR-10a is associated with human recurrent spontaneous abortion (RSA). In this study, we found that rs3809783 A > T in miR-10a coding region was significantly associated with the increase of the risk of human unexplained RSA (URSA) acquisition in a Han-Chinese population. The T allele of rs3809783 hindered the production of mature miR-10a. A to T substitution in miR-10a rs3809783 repressed cell proliferation and migratory capacity. Further investigation discovered that Bcl-2-interacting mediator (Bim) was the functional target of miR-10a and inversely regulated Bim expression. Dual-luciferase assay indicated that A allele in miR-10a rs3809783 could more effectively suppress Bim expression than T allele. In addition, A to T substitution in miR-10a rs3809783 attenuated the sensibility of cells to progesterone and its antagonist mifepristone. Collectively, our data suggest that rs3809783 A > T in pri-miR-10a may be conductive to the genetic predisposition to RSA by disrupting the production of mature miR-10a and reinforcing the expression of Bim. PMID:26824181

  18. Optimization of growth conditions for (La1-yPry)1-x CaxMnO3 thin films on annealed oxide substrates

    NASA Astrophysics Data System (ADS)

    Schaefer, Brian; Grant, Daniel; Biswas, Amlan

    2014-03-01

    Consistent growth of flat, epitaxial thin films is essential for uncovering the unique transport characteristics of rare-earth manganite systems. We have developed pulsed laser deposition growth conditions for (La1-yPry)1-x CaxMnO3 (LPCMO, y = 0.4, 0.5, 0.6) thin films on annealed NdGaO3 (NGO) and SrTiO3 (STO) substrates. The extra annealing step for NGO and STO produces atomically flat substrates with well-defined terraces of unit cell step height. Films grown on these annealed substrates demonstrate better lattice matching compared to films grown on as-received substrates. Consequently, annealing substrates before film growth leads to higher quality thin films with a more controllable thickness. We demonstrate that these optimized growth parameters yield LPCMO thin films that are also atomically flat, as confirmed by atomic force microscopy. We are using these thin films to restrict phase growth to reduced dimensions and to study the origin of thermodynamic phase competition due to first order transitions in manganites. NSF DMR-0804452

  19. A Simple and High-Throughput Analysis of Amatoxins and Phallotoxins in Human Plasma, Serum and Urine Using UPLC-MS/MS Combined with PRiME HLB μElution Platform

    PubMed Central

    Zhang, Shuo; Zhao, Yunfeng; Li, Haijiao; Zhou, Shuang; Chen, Dawei; Zhang, Yizhe; Yao, Qunmei; Sun, Chengye

    2016-01-01

    Amatoxins and phallotoxins are toxic cyclopeptides found in the genus Amanita and are among the predominant causes of fatal food poisoning in China. In the treatment of Amanita mushroom poisoning, an early and definite diagnosis is necessary for a successful outcome, which has prompted the development of protocols for the fast and confirmatory determination of amatoxins and phallotoxins in human biological fluids. For this purpose, a simple, rapid and sensitive multiresidue UPLC-MS/MS method for the simultaneous determination of α-amanitin, β-amanitin, γ-amanitin, phalloidin (PHD) and phallacidin (PCD) in human plasma, serum and urine was developed and validated. The diluted plasma, serum and urine samples were directly purified with a novel PRiME technique on a 96-well μElution plate platform, which allowed high-throughput sample processing and low reagent consumption. After purification, a UPLC-MS/MS analysis was performed using positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode. This method fulfilled the requirements of a validation test, with good results for the limit of detection (LOD), lower limit of quantification (LLOQ), accuracy, intra- and inter-assay precision, recovery and matrix effects. All of the analytes were confirmed and quantified in authentic plasma, serum and urine samples obtained from cases of poisoning using this method. Using the PRiME μElution technique for quantification reduces labor and time costs and represents a suitable method for routine toxicological and clinical emergency analysis. PMID:27153089

  20. A Simple and High-Throughput Analysis of Amatoxins and Phallotoxins in Human Plasma, Serum and Urine Using UPLC-MS/MS Combined with PRiME HLB μElution Platform.

    PubMed

    Zhang, Shuo; Zhao, Yunfeng; Li, Haijiao; Zhou, Shuang; Chen, Dawei; Zhang, Yizhe; Yao, Qunmei; Sun, Chengye

    2016-01-01

    Amatoxins and phallotoxins are toxic cyclopeptides found in the genus Amanita and are among the predominant causes of fatal food poisoning in China. In the treatment of Amanita mushroom poisoning, an early and definite diagnosis is necessary for a successful outcome, which has prompted the development of protocols for the fast and confirmatory determination of amatoxins and phallotoxins in human biological fluids. For this purpose, a simple, rapid and sensitive multiresidue UPLC-MS/MS method for the simultaneous determination of α-amanitin, β-amanitin, γ-amanitin, phalloidin (PHD) and phallacidin (PCD) in human plasma, serum and urine was developed and validated. The diluted plasma, serum and urine samples were directly purified with a novel PRiME technique on a 96-well μElution plate platform, which allowed high-throughput sample processing and low reagent consumption. After purification, a UPLC-MS/MS analysis was performed using positive electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode. This method fulfilled the requirements of a validation test, with good results for the limit of detection (LOD), lower limit of quantification (LLOQ), accuracy, intra- and inter-assay precision, recovery and matrix effects. All of the analytes were confirmed and quantified in authentic plasma, serum and urine samples obtained from cases of poisoning using this method. Using the PRiME μElution technique for quantification reduces labor and time costs and represents a suitable method for routine toxicological and clinical emergency analysis. PMID:27153089

  1. An autoregulatory network between menin and pri-miR-24-1 is required for the processing of its specific modulator miR-24-1 in BON1 cells.

    PubMed

    Luzi, Ettore; Marini, Francesca; Ciuffi, Simone; Galli, Gianna; Brandi, Maria Luisa

    2016-05-24

    Multiple endocrine neoplasia type 1 (MEN1) is a rare hereditary cancer complex syndrome manifesting a variety of endocrine and non-endocrine neoplasms and lesions. MEN1 is characterized by tumours of the parathyroids, of the neuroendocrine cells of the gastroenteropancreatic tract, and of the anterior pituitary. The MEN1 gene, a tumour suppressor gene, encodes the menin protein. Loss of heterozygosity (LOH) at 11q13 is typical of MEN1 tumours in agreement with Knudson's two-hit hypothesis. We previously showed that the MEN1 parathyroid tumorigenesis is under the control of an "incoherent feedback loop" between miR-24-1 and the menin protein that generates a "Gene Regulatory Network" (GRN) that mimics the second hit of Knudson's hypothesis and that could buffer the effect of the stochastic factors that contribute to the onset and progression of this disease. Here we show, in the BON1 cell line derived from lymphnode metastasis of a human carcinoid tumour of the pancreas, that menin binds specifically to the primary RNA sequence pri-miR-24-1 by promoting the miR-24-1 biogenesis. Network simulation showed a new feed-forward loop between menin, microRNA-24-1 and Musashi-1 proteins. This result shows a novel mechanism whereby menin, a RNA-binding protein, facilitates the processing of its specific miRNA by regulating the dynamics of the menin-miR-24 Gene Regulatory Network at the level of pri-miRNA processing. PMID:27098433

  2. Preliminary evidence for association of genetic variants in pri-miR-34b/c and abnormal miR-34c expression with attention deficit and hyperactivity disorder.

    PubMed

    Garcia-Martínez, I; Sánchez-Mora, C; Pagerols, M; Richarte, V; Corrales, M; Fadeuilhe, C; Cormand, B; Casas, M; Ramos-Quiroga, J A; Ribasés, M

    2016-01-01

    Attention deficit and hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder characterized by impairment to sustain attention and inability to control impulses and activity level. The etiology of ADHD is complex, with an estimated heritability of 70-80%. Under the hypothesis that alterations in the processing or target binding of microRNAs (miRNAs) may result in functional alterations predisposing to ADHD, we explored whether common polymorphisms potentially affecting miRNA-mediated regulation are involved in this psychiatric disorder. We performed a comprehensive association study focused on 134 miRNAs in 754 ADHD subjects and 766 controls and found association between the miR-34b/c locus and ADHD. Subsequently, we provided preliminary evidence for overexpression of the miR-34c-3p mature form in peripheral blood mononuclear cells of ADHD subjects. Next, we tested the effect on gene expression of single-nucleotide polymorphisms within the ADHD-associated region and found that rs4938923 in the promoter of the pri-miR-34b/c tags cis expression quantitative trait loci for both miR-34b and miR-34c and has an impact on the expression levels of 681 transcripts in trans, including genes previously associated with ADHD. This gene set was enriched for miR-34b/c binding sites, functional categories related to the central nervous system, such as axon guidance or neuron differentiation, and serotonin biosynthesis and signaling canonical pathways. Our results provide preliminary evidence for the contribution to ADHD of a functional variant in the pri-miR-34b/c promoter, possibly through dysregulation of the expression of mature forms of miR-34b and miR-34c and some target genes. These data highlight the importance of abnormal miRNA function as a potential epigenetic mechanism contributing to ADHD. PMID:27576168

  3. Cobalt silicide formation on a Si(1 0 0) substrate in the presence of an interfacial (Fe90Zr10) interlayer

    NASA Astrophysics Data System (ADS)

    Abrass, Hameda A.; Theron, C. C.; Njoroge, E. G.; van der Berg, N. G.; Botha, A. J.; Yan, X.-L.; Terblans, J. J.

    2015-09-01

    The reaction between a thin film (126 nm) of Co and Si has been studied at 450 °C for 24 h under high vacuum conditions, in the presence of a FeZr barrier layer. Without a diffusion barrier layer between Co and Si, Co2Si forms at 350 °C as the initial phase while CoSi2 forms at 550 °C. The FeZr barrier layer changed the flux of atoms arriving at the reaction interface. Co reacted with the Si from the substrate and formed a mixed layer of CoSi and CoSi2 in the interlayer region. The use of the FeZr diffusion barrier has been demonstrated to lower the temperature formation of CoSi2 to 450 °C. The reactions were characterised by Rutherford backscattering spectrometry, Auger electron spectroscopy depth profiling, X-ray diffraction using CoKα radiation and scanning electron microscopy.

  4. Substrate-dependent post-annealing effects on the strain state and electrical transport of epitaxial La5/8-yPryCa3/8MnO3 films

    NASA Astrophysics Data System (ADS)

    Hu, Sixia; Huang, Haoliang; Yang, Yuanjun; Luo, Zhenlin; Yang, Mengmeng; Wang, Haibo; Dong, Yongqi; Hong, Bing; He, Hao; Bao, Jun; Gao, Chen

    2014-06-01

    Large scale electronic phase separation (EPS) between ferromagnetic metallic and charge-ordered insulating phases in La5/8-yPryCa3/8MnO3 (y = 0.3) (LPCMO) is very sensitive to the structural changes. This work investigates the effects of post-annealing on the strain states and electrical transport properties of LPCMO films epitaxially grown on (001)pc SrTiO3 (tensile strain), LaAlO3 (compressive strain) and NdGaO3 (near-zero strain) substrates. Before annealing, all the films are coherent-epitaxial and insulating through the measured temperature range. Obvious change of film lattice is observed during the post-annealing: the in-plane strain in LPCMO/LAO varies from -1.5% to -0.1% while that in LPCMO/STO changes from 1.6% to 1.3%, and the lattice of LPCMO/NGO keeps constant because of the good lattice-match between LPCMO and NGO. Consequently, the varied film strain leads to the emergence of metal-insulator transitions (MIT) and shift of the critical transition temperature in the electrical transport. These results demonstrate that lattice-mismatch combined with post-annealing is an effective approach to tune strain in epitaxial LPCMO films, and thus to control the EPS and MIT in the films.

  5. Are the SSB-Interacting Proteins RecO, RecG, PriA and the DnaB-Interacting Protein Rep Bound to Progressing Replication Forks in Escherichia coli?

    PubMed

    Bentchikou, Esma; Chagneau, Carine; Long, Emilie; Matelot, Mélody; Allemand, Jean-François; Michel, Bénédicte

    2015-01-01

    In all organisms several enzymes that are needed upon replication impediment are targeted to replication forks by interaction with a replication protein. In most cases these proteins interact with the polymerase clamp or with single-stranded DNA binding proteins (SSB). In Escherichia coli an accessory replicative helicase was also shown to interact with the DnaB replicative helicase. Here we have used cytological observation of Venus fluorescent fusion proteins expressed from their endogenous loci in live E. coli cells to determine whether DNA repair and replication restart proteins that interact with a replication protein travel with replication forks. A custom-made microscope that detects active replisome molecules provided that they are present in at least three copies was used. Neither the recombination proteins RecO and RecG, nor the replication accessory helicase Rep are detected specifically in replicating cells in our assay, indicating that either they are not present at progressing replication forks or they are present in less than three copies. The Venus-PriA fusion protein formed foci even in the absence of replication forks, which prevented us from reaching a conclusion. PMID:26244508

  6. Multiple magnetic transitions, dynamical magnetic liquid and magnetic glass in La1-x-yPryCaxMnO3 (x≈0.42, y≈0.40) thin films: A thickness dependent study

    NASA Astrophysics Data System (ADS)

    Agarwal, Vasudha; Kandpal, Lalit M.; Siwach, P. K.; Awana, V. P. S.; Singh, H. K.

    2015-11-01

    The influence of substrate induced strain and its relaxation on the evolution of the multiple magnetic transitions and ensuing modifications in the degree of phase separation, the nature of the dynamical magnetic liquid, the randomly frozen glass and insulator-metal transitions have been investigated in single crystalline La1-x-yPryCaxMnO3 (x≈0.42, y≈0.40) in t~20-140 nm thick films deposited on LaAlO3 (001) substrates. The ferromagnetic (FM) transition temperature (TC) first decreases as the film thickness is increased from t~20 nm to t~60 nm and then increases with increasing film thickness. In contrast the charge ordering (CO), antiferromagnetic (AFM) and glass transition temperatures shift towards higher values with increasing film thickness. The field cooled cooling (FCC) and field cooled warming (FCW) magnetization (M-T) of films having t≥60 nm shows pronounced hysteresis and ΔTC=TCFCW-TCFCC decreases concomitantly from 46 K to 35 K as the thickness increases from ~60 to ~140 nm. The thinnest film shows insulator to metal transitions (IMT) only at magnetic field H>40 kOe. Films with t≥TC show sharp hysteretic IMT, with ΔTIM=TIMW-TIMC decreasing from ~70 K to ~50 K as the thickness increases from ~60 nm to ~140 nm. Such strong hysteresis is a characteristic of first order phase transition and also a signature of magnetic liquid like phase created by the magnetic frustration created by the delicate balance between FM and AFM/CO phases. The H induced AFM/CO to FM transition reduces ΔTIM and at higher fields the phase transition appears akin to the second order. The observed difference in the magnetic and transport properties have been explained in terms of the substrate induced strain at lower film thickness and its relaxation at higher thickness.

  7. Impact of nanostructuring on the magnetic and magnetocaloric properties of microscale phase-separated La5/8–yPryCa3/8MnO₃ manganites

    DOE PAGESBeta

    Bingham, N. S.; Lampen, P.; Phan, M. H.; Hoang, T. D.; Chinh, H. D.; Zhang, C. L.; Cheong, S. W.; Srikanth, H.

    2012-08-16

    Bulk manganites of the form La5/8–yPryCa3/8MnO₃ (LPCMO) exhibit a complex phase diagram due to coexisting charge-ordered antiferromagnetic (CO/AFM), charge-disordered paramagnetic (PM), and ferromagnetic (FM) phases. Because phase separation in LPCMO occurs on the microscale, reducing particle size to below this characteristic length is expected to have a strong impact on the magnetic properties of the system. Through a comparative study of the magnetic and magnetocaloric properties of single-crystalline (bulk) and nanocrystalline LPCMO (y=3/8) we show that the AFM, CO, and FM transitions seen in the single crystal can also be observed in the large particle sizes (400 and 150 nm),more » while only a single PM to FM transition is found for the small particles (55 nm). Magnetic and magnetocaloric measurements reveal that decreasing particle size affects the balance of competing phases in LPCMO and narrows the range of fields over which PM, FM, and CO phases coexist. The FM volume fraction increases with size reduction, until CO is suppressed below some critical size, ~100 nm. With size reduction, the saturation magnetization and field sensitivity first increase as long-range CO is inhibited, then decrease as surface effects become increasingly important. The trend that the FM phase is stabilized on the nanoscale is contrasted with the stabilization of the charge-disordered PM phase occurring on the microscale, demonstrating that in terms of the characteristic phase separation length, a few microns and several hundred nanometers represent very different regimes in LPCMO.« less

  8. Heavy actinide production from the interactions of sup 40 Ar with sup 248 Cm and a comparison with the sup 44 Ca- sup 248 Cm system

    SciTech Connect

    Leyba, J.D.; Henderson, R.A.; Hall, H.L.; Gannett, C.M.; Chadwick, R.B.; Czerwinski, K.R.; Kadkhodayan, B.A.; Kreek, S.A.; Haynes, G.R.; Gregorich, K.E.; Lee, D.M.; Nurmia, M.J.; Hoffman, D.C. Nuclear Science Division, Lawrence Berkeley Laboratory, University of California, Berkeley, Berkeley, California 94720)

    1990-05-01

    Excitation functions have been measured for isotopes of Bk, Cf, Es, and Fm produced from the interactions of 207- to 286-MeV {sup 40}Ar ions with {sup 248}Cm. The measured isotopic distributions were found to be essentially symmetric with full widths at half maximum between 2.0 and 3.5 mass units. These results are comparable to those obtained in previous studies using {sup 40,44,48}Ca with {sup 248}Cm. The maxima of the isotopic distributions from the {sup 40}Ar-{sup 248}Cm system show shifts, to both heavier and lighter mass numbers, of 0 to 2 mass units relative to the corresponding maxima of the isotopic distributions from the {sup 40,44,48}Ca-{sup 248}Cm systems.

  9. Variations in the Sr/Ca, δ44Ca and δ18O composition of calcite as a function of solution chemistry and crystal growth rate

    NASA Astrophysics Data System (ADS)

    Watkins, J. M.; DePaolo, D. J.; Ryerson, F. J.

    2012-12-01

    The trace element and isotopic composition of calcite can be used to probe the temperatures and rates of mineral formation as well as the degree of post-mineralization alteration. The accuracy with which these effects can be interpreted is limited by our ability to distinguish signatures arising from equilibrium partitioning versus kinetic or mass transport effects. Our focus in this work is on mass transport effects in aqueous environments, and specifically, the growth rate-dependence of trace element and isotopic incorporation into calcite. This requires experiments in which the degree of supersaturation, or the solution chemistry, is held constant and the rate of crystal growth can be determined. In our experiments, N2+CO2 gas mixture is bubbled through a beaker containing 1300 mL of solution (30 mM CaCl2 + 5 mM NH4Cl + 0.1 mM SrCl2). The degree of supersaturation with respect to calcite is controlled by the pCO2 of the gas mixture, which is constantly replenished from a gas source. As CO2 from the gas dissolves into solution, calcite crystals grow on the beaker walls and the pH of the solution is maintained by use of an autotitrator with NaOH as the titrant. During an experiment we control the temperature, pH, the pCO2 of the gas inflow, and the gas inflow rate. At the same time we monitor the total alkalinity, the pCO2 of the gas outflow, the gas outflow rate, and the amount of NaOH added. The rate of calcite precipitation can be determined in three ways: (1) the change in total alkalinity due to Ca2+ removal, mass balance of C in the system, and (3) post-run measurement of [Ca2+] in aliquots of solution taken during an experiment. We present results from experiments where growth rates are estimated to range from 0.5 to 16 mmol/m2/hr. Our experiments thus far have yielded calcite crystals that are out of calcium and oxygen isotopic equilibrium with the parent solution. Crystals are enriched in the light isotope of Ca by 0.4 to 1.8‰. The light isotope enrichment increases with growth rate and is correlated with Sr/Ca in calcite. These results are in excellent agreement with the results of Tang et al. (2008) for crystals grown at 25°C and suggest that mass discrimination is controlled by mass transport kinetics at the mineral-solution interface. Oxygen isotopes are more complicated because of the addition of CO2 to the bulk solution. For crystals grown from our stock solution, the O composition is highly variable and not correlated with growth rate. We attribute this to relatively slow kinetics of O isotope exchange between gaseous or dissolved CO2 and water. For crystals grown in the presence of 0.01 grams of bovine carbonic anhydrase (CA), an enzyme which catalyzes the interconversion of CO2 and H2O to bicarbonate and protons, the O isotope composition of calcite appears to be independent of growth rate. Hence addition of CA to solution might offer a means of determining the equilibrium fractionation factor for oxygen isotopes in carbonate minerals. We will present results from additional experiments that test how CA and other organic molecules in solution affect the growth rate and mass discrimination during mineral precipitation.

  10. Modeling of colossal magnetoresistance in La0.67Ca0.33MnO3/Pr0.67Ca0.33MnO3 superlattices: Comparison with individual (La1-yPry)0.67Ca0.33MnO3 films

    NASA Astrophysics Data System (ADS)

    Hühn, S.; Jungbauer, M.; Michelmann, M.; Massel, F.; Koeth, F.; Ballani, C.; Moshnyaga, V.

    2013-05-01

    Colossal magnetoresistance (CMR) and nm-scale electronic inhomogeneity close to the first order phase transition in perovskite manganites, e.g., (La1-yPry)0.67Ca0.33MnO3 still remain a puzzling phenomenon. We experimentally model a metal-insulator phase coexistence by growing a short period (LCMOn/PCMOn)m superlattices (SLs) with the same thickness for both components. CMR effect was studied as a function of the individual layer thickness n = 2-8 and then compared with chemically homogeneous (La1-yPry)0.67Ca0.33MnO3 LPCMO films. We show that SLs can be superimposed in the phase diagram of LPCMO. The results also point out the importance of the nm-scale electronic rather than chemical separation for realization of the CMR effect as well as limits the lowest boundary for the thickness of an individual manganite material to n ˜4u.c.

  11. Canopy level chlorophyll flouresence and PRI in a cornfield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Determining the health and vigor of vegetation using high spectral resolution remote sensing techniques is a critical component in monitoring productivity from both natural and managed ecosystems and their feedbacks to climate. Two spectrally based indices now used in field studies to assess whether...

  12. Introns of plant pri-miRNAs enhance miRNA biogenesis

    PubMed Central

    Bielewicz, Dawid; Kalak, Malgorzata; Kalyna, Maria; Windels, David; Barta, Andrea; Vazquez, Franck; Szweykowska-Kulinska, Zofia; Jarmolowski, Artur

    2013-01-01

    Plant MIR genes are independent transcription units that encode long primary miRNA precursors, which usually contain introns. For two miRNA genes, MIR163 and MIR161, we show that introns are crucial for the accumulation of proper levels of mature miRNA. Removal of the intron in both cases led to a drop-off in the level of mature miRNAs. We demonstrate that the stimulating effects of the intron mostly reside in the 5′ss rather than on a genuine splicing event. Our findings are biologically significant as the presence of functional splice sites in the MIR163 gene appears mandatory for pathogen-triggered accumulation of miR163 and proper regulation of at least one of its targets. PMID:23681439

  13. The Politics of Parental Involvement: How Opportunity Hoarding and Prying Shape Educational Opportunity

    ERIC Educational Resources Information Center

    Lyken-Segosebe, Dawn; Hinz, Serena E.

    2015-01-01

    As more state legislatures join the debate on school-choice and parent-trigger legislation, their discussions draw attention to an evolving landscape outside school walls where parental action shapes educational opportunity. Parents wield their political, social, economic, and cultural capital to secure the best educational outcomes for their…

  14. Directional hyperspectral observations to detect plant stress with the PRI and SIF in a cornfield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We examined the impact of drought stress and temperature on plant hyperspectral, fluorescence, and photosynthetic responses during the 2012 growing season at an experimental USDA (United States Department of Agriculture) cornfield in Beltsville, MD USA. The manipulations included 4 nitrogen (N) appl...

  15. Ca-Pri a Cellular Automata Phenomenological Research Investigation: Simulation Results

    NASA Astrophysics Data System (ADS)

    Iannone, G.; Troisi, A.

    2013-05-01

    Following the introduction of a phenomenological cellular automata (CA) model capable to reproduce city growth and urban sprawl, we develop a toy model simulation considering a realistic framework. The main characteristic of our approach is an evolution algorithm based on inhabitants preferences. The control of grown cells is obtained by means of suitable functions which depend on the initial condition of the simulation. New born urban settlements are achieved by means of a logistic evolution of the urban pattern while urban sprawl is controlled by means of the population evolution function. In order to compare model results with a realistic urban framework we have considered, as the area of study, the island of Capri (Italy) in the Mediterranean Sea. Two different phases of the urban evolution on the island have been taken into account: a new born initial growth as induced by geographic suitability and the simulation of urban spread after 1943 induced by the population evolution after this date.

  16. Pushing, Pulling, and Prying: Renewing Senior Faculty Performance through College Dean Efforts

    ERIC Educational Resources Information Center

    Miller, Michael T.; Newman, Richard E.

    2011-01-01

    The quality of college faculty members is directly linked to the institutional experience that students encounter, and as such, administrators and leaders are deeply concerned about the productivity, professionalism, and ability of their faculty. One result has been an extreme investment in faculty development and renewal activities, including…

  17. Sensor4PRI: A Sensor Platform for the Protection of Railway Infrastructures

    PubMed Central

    Cañete, Eduardo; Chen, Jaime; Díaz, Manuel; Llopis, Luis; Rubio, Bartolomé

    2015-01-01

    Wireless Sensor Networks constitute pervasive and distributed computing systems and are potentially one of the most important technologies of this century. They have been specifically identified as a good candidate to become an integral part of the protection of critical infrastructures. In this paper we focus on railway infrastructure protection and we present the details of a sensor platform designed to be integrated into a slab track system in order to carry out both installation and maintenance monitoring activities. In the installation phase, the platform helps operators to install the slab tracks in the right position. In the maintenance phase, the platform collects information about the structural health and behavior of the infrastructure when a train travels along it and relays the readings to a base station. The base station uses trains as data mules to upload the information to the internet. The use of a train as a data mule is especially suitable for collecting information from remote or inaccessible places which do not have a direct connection to the internet and require less network infrastructure. The overall aim of the system is to deploy a permanent economically viable monitoring system to improve the safety of railway infrastructures. PMID:25734648

  18. Fearing Prying U.S. Eyes, Canada's Colleges Crack Down On Computing

    ERIC Educational Resources Information Center

    Carnevale, Dan

    2007-01-01

    The USA Patriot Act is having far-reaching effects on the kinds of data that wind up on some academics' computers in Canada. Canadian colleges, responding to provincial laws passed in reaction to the Patriot Act, are preventing professors from entering the United States with students' private data on their laptops and limiting the locations of…

  19. Prying the Gates Wide Open: Academic Freedom and Gender Equality at Brown University, 1974-1977

    ERIC Educational Resources Information Center

    Porwancher, Andrew

    2013-01-01

    In 1974, Brown University's Department of Anthropology denied tenure to assistant professor Louise Lamphere. Convinced that her dismissal was the product of sex discrimination, Lamphere filed suit against Brown. Lamphere and three other female scholars who joined her suit successfully pressed Brown into an out-of-court settlement in 1977.…

  20. 7 CFR 14.6 - Criteria for determining the pri- mary purpose of payments with respect to potential exclusion...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... income. (a) Soil conservation. (1) Payments shall be considered to be made primarily for the purpose of soil conservation if they are intended to finance activities, measures, or practices to reduce soil deterioration. (2) Soil deterioration refers to impairments of the physical or chemical properties of soil...

  1. A Multimethod Assessment of Juvenile Psychopathy: Comparing the Predictive Utility of the PCL:YV, YPI, and NEO PRI

    PubMed Central

    Cauffman, Elizabeth; Kimonis, Eva R.; Dmitrieva, Julia; Monahan, Kathryn C.

    2009-01-01

    The current study compares 3 distinct approaches for measuring juvenile psychopathy and their utility for predicting short- and long-term recidivism among a sample of 1,170 serious male juvenile offenders. The assessment approaches compared a clinical interview method (the Psychopathy Checklist: Youth Version [PCL:YV]; Forth, Kosson, & Hare, 2003), a new self-report measure (the Youth Psychopathic Traits Inventory; Andershed, Kerr, Stattin, & Levander, 2002), and a personality-based approach (the NEO Psychopathy Resemblance Index; Lynam & Widiger, 2007). Results indicate a modest overlap between the 3 measures (rs = .26–.36); however, youths were often identified as psychopathic by 1 measure but not by others. Measures were weakly correlated with reoffending during subsequent 6- and 12-month periods. Findings suggest that although such scores may be useful indicators of the need for heightened monitoring in the short term, care should be taken when making predictions about long-term recidivism among adolescents. Moreover, the lack of long-term predictive power for the PCL:YV and the inconsistent psychopathy designations obtained with different measures raise serious questions about the use of such measures as the basis for legal or clinical treatment decisions. PMID:19947787

  2. Limited access to HIV prevention in French prisons (ANRS PRI2DE): implications for public health and drug policy

    PubMed Central

    2011-01-01

    Background Overpopulation, poor hygiene and disease prevention conditions in prisons are major structural determinants of increased infectious risk within prison settings but evidence-based national and WHO guidelines provide clear indications on how to reduce this risk. We sought to estimate the level of infectious risk by measuring how French prisons adhere to national and WHO guidelines. Methods A nationwide survey targeting the heads of medical (all French prisons) and psychiatric (26 French prisons) units was conducted using a postal questionnaire and a phone interview mainly focusing on access to prevention interventions, i.e. bleach, opioid substitution treatment (OST), HBV vaccination and post-exposure prophylaxis (PEP) for French prisoners. Two scores were built reflecting adherence to national and WHO international guidelines, ranging from 0 (no adherence) to 10 (maximum adherence) and 0 to 9 respectively. Results A majority (N = 113 (66%)) of the 171 prisons answered the questionnaires, representing 74% coverage (46,786 prisoners) of the French prison population: 108 were medical units and 12 were psychiatric units. Inmate access to prevention was poor. The median[IQR] score measuring adherence to national guidelines was quite low (4.5[2.5; 5.5]) but adherence to WHO guidelines was even lower 2.5[1.5; 3.5]; PEP was absent despite reported risky practices. Unsuitable OST delivery practices were frequently observed. Conclusions A wide gap exists between HIV prevention policies and their application in prisons. Similar assessments in other countries may be needed to guide a global policy reform in prison settings. Adequate funding together with innovative interventions able to remove structural and ideological barriers to HIV prevention are now needed to motivate those in charge of prison health, to improve their working environment and to relieve French prisoners from their currently debilitating conditions. PMID:21619573

  3. 7 CFR 14.6 - Criteria for determining the pri- mary purpose of payments with respect to potential exclusion...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... the productive capacity of the soil are forms of soil deterioration. (b) Water conservation. (1) Water conservation includes actions that, for a given level of water supply, reduce the demand for or use of water by... be made primarily for the purpose of water conservation if they are intended to finance...

  4. A Multimethod Assessment of Juvenile Psychopathy: Comparing the Predictive Utility of the PCL:YV, YPI, and NEO PRI

    ERIC Educational Resources Information Center

    Cauffman, Elizabeth; Kimonis, Eva R.; Dmitrieva, Julia; Monahan, Kathryn C.

    2009-01-01

    The current study compares 3 distinct approaches for measuring juvenile psychopathy and their utility for predicting short- and long-term recidivism among a sample of 1,170 serious male juvenile offenders. The assessment approaches compared a clinical interview method (the Psychopathy Checklist: Youth Version [PCL:YV]; Forth, Kosson, & Hare,…

  5. On the excitation energy of deep-hole states in medium-heavy-mass spherical nuclei

    NASA Astrophysics Data System (ADS)

    Kolomiytsev, G. V.; Igashov, S. Yu.; Urin, M. H.

    2016-01-01

    Within the particle-hole dispersive optical model it is shown that the spreading effect determines a significant part of the anomalously large excitation energy of deep-hole states in the 90Zr and 208Pb parent nuclei.

  6. Chemical and Charge Imbalance Induced by Radionuclide Decay: Effects on Waste Form Structure

    SciTech Connect

    Van Ginhoven, Renee M.; Jaffe, John E.; Jiang, Weilin; Strachan, Denis M.

    2011-04-01

    This is a milestone document covering the activities to validate theoretical calculations with experimental data for the effect of the decay of 90Sr to 90Zr on materials properties. This was done for a surragate waste form strontium titanate.

  7. The Long, the Short, and the Unstructured: A Unifying Model of miRNA Biogenesis.

    PubMed

    Denzler, Rémy; Stoffel, Markus

    2015-10-01

    In this issue, Fang and Bartel (2015) report the identification of novel sequence and structural features of human pri-miRNAs, which--together with previously identified sequence motifs--define a unifying model of mammalian pri-miRNAs and advances the de novo design of artificial pri-miRNAs. PMID:26431024

  8. Biological control of calcium isotopic abundances in the global calcium cycle

    SciTech Connect

    Skulan, J.; DePaolo, D.J.; Owens, T.L. |

    1997-06-01

    Measurements of {sup 44}Ca/{sup 40}Ca, expressed as {delta}{sup 44}Ca, were made on igneous rocks and on shell and bone material from modern organisms to investigate the magnitude and origins of calcium isotopic fractionation in nature. The results document a span of 4{per_thousand} in {delta}{sup 44}Ca, measured with the double spike technique to a precision of {+-}0.15{per_thousand}. Volcanic rocks, including basalt and rhyolite, show little variability and cluster near {delta}{sup 44}Ca = 0 {+-}0.2. Systematic analysis of biological samples indicates that biological processing of calcium discriminates against heavy isotopes, and that biological fractionation is the primary generator of calcium isotopic fractionation in nature. Preliminary data suggest that calcium becomes isotopically lighter as it moves through food chains. Calcium carbonate shells of marine microorganisms and deep-sea carbonate ooze have {delta}{sup 44}Ca about 1.0{per_thousand}, lower than seawater; this fractionation causes seawater to be enriched in heavy calcium ({delta}{sup 44}Ca = +0.9) relative to igneous rocks. Marine organisms consequently are isotopically heavier than their terrestrial counterparts at similar trophic level. The calcium isotopic composition of living and fossil organisms may record information on diet and environment. 22 refs., 3 figs., 2 tabs.

  9. Controlling factors of Ca isotope fractionation in scleractinian corals evaluated by temperature, pH and light controlled culture experiments

    NASA Astrophysics Data System (ADS)

    Inoue, Mayuri; Gussone, Nikolaus; Koga, Yasuko; Iwase, Akihiro; Suzuki, Atsushi; Sakai, Kazuhiko; Kawahata, Hodaka

    2015-10-01

    In this study, the 44Ca/40Ca ratios of Porites australiensis grown under three different culture experiments composed of temperature, pH and light controlled culture experiments are measured. The temperature dependent isotope fractionation of 0.02‰/°C deduced from this study is similar to inorganic aragonite, but the degree of isotope fractionation is about +0.4‰ offset in corals. These observations agree with earlier results on different coral species, suggesting Ca isotope fractionation during Ca transmembrane transport in corals. While in cultured corals a significant temperature dependence of δ44Ca is observed, the relationships between calcium isotope fractionation and pH as well as light intensity are negligible. Therefore variation of δ44Ca in Porites corals is mainly controlled by temperature. A combination of δ44Ca and Sr/Ca of corals in temperature controlled experiments cannot be explained by Rayleigh type fractionation directly from a fluid, which is seawater-like in terms of δ44Ca and Sr/Ca. Through coral-specific biomineralization processes, overall mean δ44Ca of scleractinian corals including previous studies are different from biogenic aragonites secreted by sclerosponges and pteropods, but are comparable with those of bivalves as well as calcitic coccolithophores and foraminifers. These findings are important for better understanding biomineralization in corals and in order to constrain the Ca isotopic composition of oceanic Ca sinks in response to climate changes and associated with shifts of calcite and aragonite seas.

  10. Antiproliferative Activity and in Vivo Toxicity of Double-Point Modified Analogs of 1,25-Dihydroxyergocalciferol

    PubMed Central

    Trynda, Justyna; Turlej, Eliza; Milczarek, Magdalena; Pietraszek, Anita; Chodyński, Michał; Kutner, Andrzej; Wietrzyk, Joanna

    2015-01-01

    Analogs of 1,25-dihydroxyergocalciferol, modified in the side-chain and in the A-ring, were tested for their antiproliferative activity against a series of human cancer cell lines in vitro and in vivo toxicity. The proliferation inhibition caused by the analogs was higher than that of the parent compounds, while the toxicity, measured as the serum calcium level, was lower. All analogs were able to induce, in HL-60 and MV4-11 leukemic cells, G0/G1 cell cycle arrest and differentiation expressed as morphological signs typical for monocytes. The analogs also induced the expression of CD11b and/or CD14 cell-differentiation markers. The most potent analogs, PRI-5105, PRI-5106, PRI-5201 and PRI-5202, were also able to induce vitamin D receptor (VDR) protein expression, mainly in the cytoplasmic fraction of HL-60 or MV4-11 cells. The most active analogs were the 19-nor ones with an extended and rigidified side-chain (PRI-5201 and PRI-5202), as in the former analogs PRI-1906 and PRI-1907. Epimerization at C-24 (PRI-5101) or introduction of an additional hydroxyl at C-23 (PRI-5104) reduced the toxicity of the analog with retained antiproliferative activity. PMID:26492238

  11. Studies of Neutron-Deficient Nuclei Near the Z = 82 Shell Closure via Cold Fusion Reactions

    NASA Astrophysics Data System (ADS)

    Carpenter, M. P.; Kondev, F. G.; Janssens, R. V. F.; Seweryniak, D.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Zhu, S.; Camera, F.; Bracco, A.; Million, B.; Leoni, S.; Jenkins, D. G.; Wadsworth, R.

    2009-03-01

    Over the last decade, we have performed in-beam experiments using Gammasphere+FMA to measure excited states in proton-rich Au, Hg, Tl and Pb isotopes. In these studies, the use of the FMA is essential in order to differentiate evaporation residues from the large fission background which dominates the reaction cross-section. In addition, we have found that using near-symmetric reactions at bombarding energies near the Coloumb barrier is beneficial in performing these studies. By keeping the bombarding energy low, fission is minimized and the reaction products are concentrated in only a few channels. New results have recently been obtained using the 90Zr+92Mo reaction to study shape co-existence in 181Tl via the lp evaporation channel. In addition, we have measured the total γ-ray energy and multiplicity associated with the surviving compund system, 179Au, following the fusion reaction, 90Zr+89Y.

  12. New Skyrme interaction with improved spin-isospin properties

    NASA Astrophysics Data System (ADS)

    Roca-Maza, X.; Colò, G.; Sagawa, H.

    2012-09-01

    A correct determination of the spin-isospin properties of the nuclear effective interaction should lead to, among other improvements, an accurate description of the Gamow-Teller resonance (GTR). These nuclear excitations impact on a variety of physical processes: from the response in charge-exchange reactions of nuclei naturally present in the Earth, to the description of the stellar nucleosynthesis and of the pre-supernova explosion core-collapse evolution of massive stars in the Universe. A reliable description of the GTR provides also stringent tests for neutrinoless double-β decay calculations. We present a new Skyrme interaction as accurate as previous forces in the description of finite nuclei and of uniform matter properties around saturation density, and that accounts well for the GTR in 48Ca, 90Zr, and 208Pb, and the isobaric analog resonance and spin dipole resonance in 90Zr and 208Pb.

  13. In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range.

    PubMed

    Pan, Lulu; Wang, Fenglong; Wang, Wenfeng; Chai, Guozhi; Xue, Desheng

    2016-01-01

    In this paper, we investigate the high frequency performance of Co90Zr10/SiO2/Co90Zr10 trilayers. It is demonstrated that the in-plane isotropic microwave performance is theoretically derived from the solution of the Landau-Lifshitz-Gilbert equation and experimentally achieved in that sandwich structured film. The valuable isotropic behavior comes from the superposition of two uncouple ferromagnetic layers in which the uniaxial magnetic anisotropic fields are equivalent but mutually orthogonal. Moreover, the isotropic microwave performance can be tuned to higher resonance frequency up to 5.3 GHz by employing the oblique deposition technique. It offers a convenient and effective way to achieve an unusual in-plane isotropic microwave performance with high permeability in GHz, holding promising applications for the magnetic devices in the high frequency information technology. PMID:26883790

  14. In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range

    NASA Astrophysics Data System (ADS)

    Pan, Lulu; Wang, Fenglong; Wang, Wenfeng; Chai, Guozhi; Xue, Desheng

    2016-02-01

    In this paper, we investigate the high frequency performance of Co90Zr10/SiO2/Co90Zr10 trilayers. It is demonstrated that the in-plane isotropic microwave performance is theoretically derived from the solution of the Landau-Lifshitz-Gilbert equation and experimentally achieved in that sandwich structured film. The valuable isotropic behavior comes from the superposition of two uncouple ferromagnetic layers in which the uniaxial magnetic anisotropic fields are equivalent but mutually orthogonal. Moreover, the isotropic microwave performance can be tuned to higher resonance frequency up to 5.3 GHz by employing the oblique deposition technique. It offers a convenient and effective way to achieve an unusual in-plane isotropic microwave performance with high permeability in GHz, holding promising applications for the magnetic devices in the high frequency information technology.

  15. In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range

    PubMed Central

    Pan, Lulu; Wang, Fenglong; Wang, Wenfeng; Chai, Guozhi; Xue, Desheng

    2016-01-01

    In this paper, we investigate the high frequency performance of Co90Zr10/SiO2/Co90Zr10 trilayers. It is demonstrated that the in-plane isotropic microwave performance is theoretically derived from the solution of the Landau-Lifshitz-Gilbert equation and experimentally achieved in that sandwich structured film. The valuable isotropic behavior comes from the superposition of two uncouple ferromagnetic layers in which the uniaxial magnetic anisotropic fields are equivalent but mutually orthogonal. Moreover, the isotropic microwave performance can be tuned to higher resonance frequency up to 5.3 GHz by employing the oblique deposition technique. It offers a convenient and effective way to achieve an unusual in-plane isotropic microwave performance with high permeability in GHz, holding promising applications for the magnetic devices in the high frequency information technology. PMID:26883790

  16. DGCR8 recognizes primary transcripts of microRNAs through highly cooperative binding and formation of higher-order structures

    PubMed Central

    Faller, Michael; Toso, Daniel; Matsunaga, Michio; Atanasov, Ivo; Senturia, Rachel; Chen, Yanqiu; Zhou, Z. Hong; Guo, Feng

    2010-01-01

    DiGeorge critical region 8 (DGCR8) is essential for maturation of microRNAs (miRNAs) in animals. In the cleavage of primary transcripts of miRNAs (pri-miRNAs) by the Drosha nuclease, the DGCR8 protein directly binds and recognizes pri-miRNAs through a mechanism currently controversial. Our previous data suggest that DGCR8 trimerizes upon cooperative binding to pri-mir-30a. However, a separate study proposed a model in which a DGCR8 molecule contacts one or two pri-miRNA molecules using its two double-stranded RNA binding domains. Here, we extensively characterized the interaction between DGCR8 and pri-miRNAs using biochemical and structural methods. First, a strong correlation was observed between the association of DGCR8 with pri-mir-30a and the rate of pri-miRNA processing in vitro. Second, we show that the high binding cooperativity allows DGCR8 to distinguish pri-miRNAs from a nonspecific competitor with subtle differences in dissociation constants. The highly cooperative binding of DGCR8 to a pri-miRNA is mediated by the formation of higher-order structures, most likely a trimer of DGCR8 dimers, on the pri-miRNA. These properties are not limited to its interaction with pri-mir-30a. Furthermore, the amphipathic C-terminal helix of DGCR8 is important both for trimerization of DGCR8 on pri-miRNAs and for the cleavage of pri-miRNAs by Drosha. Finally, our three-dimensional model from electron tomography analysis of the negatively stained DGCR8–pri-mir-30a complex directly supports the trimerization model. Our study provides a molecular basis for recognition of pri-miRNAs by DGCR8. We further propose that the higher-order structures of the DGCR8–pri-miRNA complexes trigger the cleavage of pri-miRNAs by Drosha. PMID:20558544

  17. Electron beam evaporation of molybdenum, yttrium and zirconium targets for heavy-ion nuclear physics

    SciTech Connect

    Greene, J.P.; Thomas, G.E.

    1990-01-01

    Self-supporting targets of {sup 92,98}Mo, Y and {sup 90}Zr with thickness of 100 and 200 {mu}g/cm{sup 2} were prepared by electron beam gun evaporation. Substrate heating proved crucial for the production of these foils. The numerous parting agents explored will be discussed. Targets of {sup 92,98}Mo were also prepared on carbon backings of various thickness. 19 refs., 2 figs.

  18. Realistic simulations of the AGATA Demonstrator+PRISMA Spectrometer

    SciTech Connect

    Ince, E.; Erduran, M. N.; Farnea, E.; Latina, A.

    2008-11-11

    The performance of the AGATA Demonstrator Array coupled to the PRISMA magnetic spectrometer have been evaluated in a consistent way using detailed Monte Carlo simulations of the two devices. Results for the {sup 90}Zr+{sup 208}Pb at 560 MeV reaction are presented and discussed here, proving that the Doppler correction capabilities of the AGATA+PRISMA setup will be very close to the intrinsic energy resolution of the germanium detectors.

  19. First Charge-Exchange Measurements with SHARAQ

    SciTech Connect

    Miki, K.; Sakai, H.

    2011-10-28

    The isovector spin monopole resonances (IVSMR) of the {beta}{sup +} type were observed for the first time in the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the {sup 208}Pb and {sup 90}Zr(t,{sup 3}He) reactions were obtained at the excitation energy of 0{<=}E{sub x}{<=}70 MeV and the scattering angles of 0 deg. {<=}{theta}{<=}3 deg. The monopole component was identified by making a difference between the zero-degree and backward-angle spectra. The signatures of the IVSMR are observed at an excitation energy of 12 MeV(20 MeV) in {sup 208}Pb({sup 90}Zr)(t,{sup 3}He) reaction, which agrees fairly well with the theoretical predictions.

  20. Light Charged-Particle Production Activation Cross Sections of Zr Isotopes from 14 to 20 MeV

    SciTech Connect

    Semkova, V.; Plompen, A.J.M.; Smith, D.L.

    2005-05-24

    Results of new cross-section measurements are presented for the following neutron-induced reactions: 90Zr(n,{alpha})87mSr, 90Zr(n,p)90mY, 91Zr(n,p)91mY, 91Zr(n,x)90mY, 92Zr(n,p)92Y, 92Zr(n,x)91mY, 94Zr(n,{alpha})91Sr, and 94Zr(n,p)94Y in the energy range from 14 to 21 MeV. Use was made of the activation technique in combination with high-resolution {gamma}-ray spectrometry. The irradiations were carried out at the 7-MV Van de Graaff accelerator at IRMM, Geel. Quasi-monoenergetic neutrons were produced via the 3H(d,n)4He reaction at 1, 2, 3, and 4 MeV incident deuteron energy. Both natural and samples enriched in 90Zr, 91Zr, and 92Zr were used to enhance the reaction yield or to facilitate correction for interfering reactions leading to the same product. The measured results are compared with work by other authors, TALYS-0.57 and EMPIRE-II model calculations, and current evaluated data files. Cross sections for all of the investigated reactions have been measured for the first time above 16 MeV.

  1. Calculations of Compound Nucleus Spin-Parity Distributions Populated via the (p,t) Reaction in Support of Surrogate Neutron Capture Measurements

    NASA Astrophysics Data System (ADS)

    Benstead, J.; Tostevin, J. A.; Escher, J. E.; Burke, J. T.; Hughes, R. O.; Ota, S.; Casperson, R. J.; Thompson, I. J.

    2016-06-01

    The surrogate reaction method may be used to determine the cross section for neutron induced reactions not accessible through standard experimental techniques. This is achieved by creating the same compound nucleus as would be expected in the desired reaction, but through a different incident channel, generally a direct transfer reaction. So far, the surrogate technique has been applied with reasonable success to determine the fission cross section for a number of actinides, but has been less successful when applied to other reactions, e.g. neutron capture, due to a `spin-parity mismatch'. This mismatch, between the spin and parity distributions of the excited levels of the compound nucleus populated in the desired and surrogate channels, leads to differing decay probabilities and hence reduces the validity of using the surrogate method to infer the cross section in the desired channel. A greater theoretical understanding of the expected distribution of levels excited in both the desired and surrogate channels is therefore required in order to attempt to address this mismatch and allow the method to be utilised with greater confidence. Two neutron transfer reactions, e.g. (p,t), which allow the technique to be utilised for isotopes further removed from the line of stability, are the subject of this study. Results are presented for the calculated distribution of compound nucleus states populated in 90Zr, via the 90Zr(p,t)90Zr reaction, and are compared against measured data at an incident proton energy of 28.56 MeV.

  2. Targeting Acetylcholinesterase to Membrane Rafts

    PubMed Central

    Xie, Heidi Q.; Liang, Dong; Leung, K. Wing; Chen, Vicky P.; Zhu, Kevin Y.; Chan, Wallace K. B.; Choi, Roy C. Y.; Massoulié, Jean; Tsim, Karl W. K.

    2010-01-01

    In the mammalian brain, acetylcholinesterase (AChE) is anchored in cell membranes by a transmembrane protein PRiMA (proline-rich membrane anchor). We present evidence that at least part of the PRiMA-linked AChE is integrated in membrane microdomains called rafts. A significant proportion of PRiMA-linked AChE tetramers from rat brain was recovered in raft fractions; this proportion was markedly higher at low rather than at high concentrations of cold Triton X-100. The detergent-resistant fraction increased during brain development. In NG108-15 neuroblastoma cells transfected with cDNAs encoding AChET and PRiMA, PRiMA-linked G4 AChE was found in membrane rafts and showed the same sensitivity to cold Triton X-100 extraction as in the brain. The association of PRiMA-linked AChE with rafts was weaker than that of glycosylphosphatidylinositol-anchored G2 AChE or G4 QN-HC-linked AChE. It was found to depend on the presence of a cholesterol-binding motif, called CRAC (cholesterol recognition/interaction amino acid consensus), located at the junction of transmembrane and cytoplasmic domains of both PRiMA I and II isoforms. The cytoplasmic domain of PRiMA, which differs between PRiMA I and PRiMA II, appeared to play some role in stabilizing the raft localization of G4 AChE, because the Triton X-100-resistant fraction was smaller with the shorter PRiMA II isoform than that with the longer PRiMA I isoform. PMID:20147288

  3. The NF90-NF45 Complex Functions as a Negative Regulator in the MicroRNA Processing Pathway▿ †

    PubMed Central

    Sakamoto, Shuji; Aoki, Kazuma; Higuchi, Takuma; Todaka, Hiroshi; Morisawa, Keiko; Tamaki, Nobuyuki; Hatano, Etsuro; Fukushima, Atsuki; Taniguchi, Taketoshi; Agata, Yasutoshi

    2009-01-01

    The positive regulatory machinery in the microRNA (miRNA) processing pathway is relatively well characterized, but negative regulation of the pathway is largely unknown. Here we show that a complex of nuclear factor 90 (NF90) and NF45 proteins functions as a negative regulator in miRNA biogenesis. Primary miRNA (pri-miRNA) processing into precursor miRNA (pre-miRNA) was inhibited by overexpression of the NF90 and NF45 proteins, and considerable amounts of pri-miRNAs accumulated in cells coexpressing NF90 and NF45. Treatment of cells overexpressing NF90 and NF45 with an RNA polymerase II inhibitor, α-amanitin, did not reduce the amounts of pri-miRNAs, suggesting that the accumulation of pri-miRNAs is not due to transcriptional activation. In addition, the NF90 and NF45 complex was not found to interact with the Microprocessor complex, which is a processing factor of pri-miRNAs, but was found to bind endogenous pri-miRNAs. NF90-NF45 exhibited higher binding activity for pri-let-7a than pri-miR-21. Of note, depletion of NF90 caused a reduction of pri-let-7a and an increase of mature let-7a miRNA, which has a potent antiproliferative activity, and caused growth suppression of transformed cells. These findings suggest that the association of the NF90-NF45 complex with pri-miRNAs impairs access of the Microprocessor complex to the pri-miRNAs, resulting in a reduction of mature miRNA production. PMID:19398578

  4. Frequency and fate of microRNA editing in human brain

    PubMed Central

    Kawahara, Yukio; Megraw, Molly; Kreider, Edward; Iizasa, Hisashi; Valente, Louis; Hatzigeorgiou, Artemis G.; Nishikura, Kazuko

    2008-01-01

    Primary transcripts of certain microRNA (miRNA) genes (pri-miRNAs) are subject to RNA editing that converts adenosine to inosine (A→I RNA editing). However, the frequency of the pri-miRNA editing and the fate of edited pri-miRNAs remain largely to be determined. Examination of already known pri-miRNA editing sites indicated that adenosine residues of the UAG triplet sequence might be edited more frequently. In the present study, therefore, we conducted a large-scale survey of human pri-miRNAs containing the UAG triplet sequence. By direct sequencing of RT–PCR products corresponding to pri-miRNAs, we examined 209 pri-miRNAs and identified 43 UAG and also 43 non-UAG editing sites in 47 pri-miRNAs, which were highly edited in human brain. In vitro miRNA processing assay using recombinant Drosha-DGCR8 and Dicer-TRBP (the human immuno deficiency virus transactivating response RNA-binding protein) complexes revealed that a majority of pri-miRNA editing is likely to interfere with the miRNA processing steps. In addition, four new edited miRNAs with altered seed sequences were identified by targeted cloning and sequencing of the miRNAs that would be processed from edited pri-miRNAs. Our studies predict that ∼16% of human pri-miRNAs are subject to A→I editing and, thus, miRNA editing could have a large impact on the miRNA-mediated gene silencing. PMID:18684997

  5. In-vitro and in-vivo evaluation of the anticancer activity of diruthenium-2, a new trithiolato arene ruthenium complex [(η6-p-MeC6H4Pri)2Ru2(μ-S-p-C6H4OH)3]Cl.

    PubMed

    Muthná, Darina; Tomšík, Pavel; Havelek, Radim; Köhlerová, Renata; Kasilingam, Vidhya; Čermáková, Eva; Stíbal, David; Řezáčová, Martina; Süss-Fink, Georg

    2016-08-01

    In the present study, we investigated the anticancer action of the trithiolato arene ruthenium complex, [(η-p-MeC6H4Pr)2Ru2(μ-S-p-C6H4OH)3]Cl, named diruthenium-2, both in vitro and in vivo. The mechanism of antiproliferative, cytotoxic, and DNA-damaging activity, and the effect on expressions of cell cycle regulatory proteins were investigated using a WST-1-based proliferation assay, lactate dehydrogenase leakage assay, comet assay, flow cytometry, and western blot analysis. In-vivo anticancer activity was evaluated using Ehrlich tumor-bearing NMRI mice. Diruthenium-2 inhibited the growth of all cancer cell lines used, the most sensitive being gastric (AGS), breast cancer (BT-549, MCF-7, MDA-MB-231), and leukemic (HL-60, MOLT-4) cells. In MCF-7 cells, it caused a G1/S cell cycle arrest, along with an increase in the expression of protein p21 and cyclin B1. We also observed increased levels of MRN complex proteins, which, together with the results from the comet assay, indicate the formation of DNA double-strand breaks. In tumor-bearing mice, diruthenium-2 at doses of 3 and 5 mg/kg inhibits the growth of solid Ehrlich tumor, although weaker than cisplatin. However, it did not prolong the post-therapeutic survival. Our results suggest the in-vitro potential of diruthenium-2 should be further evaluated in studies using other in-vivo models. PMID:27187018

  6. Peeking inside the "Black Box" of the Flynn Effect: Evidence from Three Wechsler Instruments

    ERIC Educational Resources Information Center

    Zhou, Xiaobin; Zhu, Jianjun; Weiss, Lawrence G.

    2010-01-01

    This study investigated the Wechsler Performance IQ (PIQ) or Perceptual Reasoning Index (PRI)/ Perceptual Organization Index (POI) change over time and its relation to ability levels. PIQ or PRI/ POI was analyzed because of the known sensitivity of nonverbal scales to the Flynn effect. Scores were analyzed using two methods. First, analysis of…

  7. A Hand-Off Mechanism for Primosome Assembly in Replication Restart

    SciTech Connect

    Lopper, Matthew; Boonsombat, Ruethairat; Sandler, Steven J.; Keck, James L.

    2008-11-12

    Collapsed DNA replication forks must be reactivated through origin-independent reloading of the replication machinery (replisome) to ensure complete duplication of cellular genomes. In E. coli, the PriA-dependent pathway is the major replication restart mechanism and requires primosome proteins PriA, PriB, and DnaT for replisome reloading. However, the molecular mechanisms that regulate origin-independent replisome loading are not fully understood. Here, we demonstrate that assembly of primosome protein complexes represents a key regulatory mechanism, as inherently weak PriA-PriB and PriB-DnaT interactions are strongly stimulated by single-stranded DNA. Furthermore, the binding site on PriB for single-stranded DNA partially overlaps the binding sites for PriA and DnaT, suggesting a dynamic primosome assembly process in which single-stranded DNA is handed off from one primosome protein to another as a repaired replication fork is reactivated. This model helps explain how origin-independent initiation of DNA replication is restricted to repaired replication forks, preventing overreplication of the genome.

  8. Meta-Analysis of the Effect of Practical Reasoning Instruction on Student Outcome in Home Economics Education in Korea

    ERIC Educational Resources Information Center

    Yu, Nan Sook

    2012-01-01

    This meta-analysis reviewed the effect of practical reasoning instruction (PRI) on student outcome in Home Economics education in Korea. In this meta-analysis, 25 studies with 35 effect sizes were analyzed. The results of this review indicated that PRI is more effective than traditional instruction on student outcomes. A medium and significant…

  9. Recycled Carbonate-Rich Sediments in the Hawaiian Plume: Evidence from Ca Isotopes

    NASA Astrophysics Data System (ADS)

    Huang, S.; Farkas, J.; Jacobsen, S. B.

    2011-12-01

    Recycling of marine sediments into the Earth's mantle is an important way introducing mantle geochemical heterogeneity. Here we report high-precision 44Ca/40Ca measurements (2σm < 0.06%) of Hawaiian shield stage tholeiites. Our data reveal ~0.3% variation in their 44Ca/40Ca, which comprises ~20% of the 44Ca/40Ca variation observed in global carbonates. The 44Ca/40Ca variation is correlated with Sr/Nb and 87Sr/86Sr, and this pattern is best explained by adding up to 4% ancient carbonate into the Hawaiian plume. Mass-balance calculations show that up to 40% of the Ca budget and 65% of the Sr budget in some Hawaiian (Makapuu-stage Koolau) lavas are derived from recycled carbonates. Our finding demonstrates, for the first time with the application of Ca isotopes, that ancient recycled carbonates are important components of mantle plumes which feed some of the largest terrestrial volcanoes. Thus, recycling of carbonates into the mantle is an essential part of the global Ca and C cycles.

  10. Stable calcium isotopic compositions of Hawaiian shield lavas: Evidence for recycling of ancient marine carbonates into the mantle

    NASA Astrophysics Data System (ADS)

    Huang, Shichun; Farkaš, Juraj; Jacobsen, Stein B.

    2011-09-01

    We report high-precision 44Ca/ 40Ca measurements (2 σm < 0.06‰) of Hawaiian shield stage tholeiites. Our data reveal ˜0.3‰ variation in their 44Ca/ 40Ca, which comprises ˜20% of the 44Ca/ 40Ca variation observed in global carbonates. The 44Ca/ 40Ca variation is correlated with Sr/Nb and 87Sr/ 86Sr, and this pattern is best explained by adding up to 4% ancient carbonate into the Hawaiian plume. Mass-balance calculations show that up to 40% of the Ca budget and 65% of the Sr budget in some Hawaiian (Makapuu-stage Koolau) lavas are derived from recycled carbonates. Our finding demonstrates, for the first time with the application of Ca isotopes, that ancient recycled carbonates are important components of mantle plumes which feed some of the largest terrestrial volcanoes. Thus, recycling of carbonates into the mantle is an essential part of the global Ca and C cycles.

  11. Calcium isotope fractionation in groundwater: Molecular scale processes influencing field scale behavior

    NASA Astrophysics Data System (ADS)

    Druhan, Jennifer L.; Steefel, Carl I.; Williams, Kenneth H.; DePaolo, Donald J.

    2013-10-01

    It is the purpose of this study to demonstrate that the molecular scale reaction mechanisms describing calcite precipitation and calcium isotope fractionations under highly controlled laboratory conditions also reproduce field scale measurements of δ44Ca in groundwater systems. We present data collected from an aquifer during active carbonate mineral precipitation and develop a reactive transport model capturing the observed chemical and isotopic variations. Carbonate mineral precipitation and associated fluid δ44Ca data were measured in multiple clogged well bores during organic carbon amended biogenic reduction of a uranium contaminated aquifer in western Colorado, USA. Secondary mineral formation induced by carbonate alkalinity generated during the biostimulation process lead to substantial permeability reduction in multiple electron-donor injection wells at the field site. These conditions resulted in removal of aqueous calcium from a background concentration of 6 mM to <1 mM while δ44Ca enrichment ranged from 1‰ to greater than 2.5‰. The relationship between aqueous calcium removal and isotopic enrichment did not conform to Rayleigh model behavior. Explicit treatment of the individual isotopes of calcium within the CrunchFlow reactive transport code demonstrates that the system did not achieve isotopic reequilibration over the time scale of sample collection. Measured fluid δ44Ca values are accurately reproduced by a linear rate law when the Ca2+:CO32- activity ratio remains substantially greater than unity. Variation in the measured δ44Ca between wells is shown to originate from a difference in carbonate alkalinity generated in each well bore. The influence of fluid Ca2+:CO32- ratio on the precipitation rate and δ44Ca is modeled by coupling the CrunchFlow reactive transport code to an ion by ion growth model. This study presents the first coupled ion-by-ion and reactive transport model for isotopic enrichment and demonstrates that reproducing field

  12. Biological and ecological insights into Ca isotopes in planktic foraminifers as a palaeotemperature proxy

    NASA Astrophysics Data System (ADS)

    Kasemann, Simone A.; Schmidt, Daniela N.; Pearson, Paul N.; Hawkesworth, Chris J.

    2008-07-01

    Sea surface temperature (SST) is a critical variable in the Earth's climate system since it influences atmospheric circulation, the hydrological cycle and, via ocean surface density, drives ocean circulation. A detailed reconstruction of past SST's is therefore a central goal of palaeoceanographic studies. Although calcium isotopes in foraminiferal carbonate have been introduced as a new proxy for SST reconstruction, there is considerable debate about their robustness and general applicability. To resolve some of these questions, we have investigated the extent to which other environmental parameters e.g. the calcification temperature, depth stratification, growth rates and/or environmental adaptation may influence the δ44Ca values of planktic foraminifers in modern and Eocene samples. Geographically distributed data sets are affected by the exchange of cryptic species, i.e. morphologically similar but genetically distinct species, and by a mixing of optimal versus less optimal adaptation. Thus, we have compared species within individual samples to evaluate whether the well documented depth stratification of foraminifers is reflected in their calcium isotopes. The Eocene data set shows a general agreement between δ44Ca and δ18O-derived calcification temperatures which supports a temperature effect on Ca isotope incorporation. The vertical temperature gradient using the different depth habitats of several foraminiferal species indicates a δ44Ca temperature dependence of ~ 0.034‰ °C - 1 similar to inorganic calcite (0.015‰ °C - 1 ) and cultured O. universa (0.019‰ °C - 1 ). The gradient resembles the global sediment δ44Ca compilation, but it is significantly smaller than the temperature calibration of 0.22 ± 0.02‰ °C - 1 for cultured G. sacculifer. The modern data set shows a general correlation between δ44Ca and depth habitat reflecting a similar temperature gradient to the Eocene sample set. In contrast, the lower absolute δ44Ca values for the

  13. Biological Evaluation of Double Point Modified Analogues of 1,25-Dihydroxyvitamin D₂ as Potential Anti-Leukemic Agents.

    PubMed

    Corcoran, Aoife; Nadkarni, Sharmin; Yasuda, Kaori; Sakaki, Toshiyuki; Brown, Geoffrey; Kutner, Andrzej; Marcinkowska, Ewa

    2016-01-01

    Structurally similar double-point modified analogues of 1,25-dihydroxyvitamin D₂ (1,25D₂) were screened in vitro for their pro-differentiating activity against the promyeloid cell line HL60. Their affinities towards human full length vitamin D receptor (VDR) and metabolic stability against human vitamin D 24-hydroxylase (CYP24A1) were also tested. The analogues (PRI-1730, PRI-1731, PRI-1732, PRI-1733 and PRI-1734) contained 5,6-trans modification of the A-ring and of the triene system, additional hydroxyl or unsaturation at C-22 in the side chain and reversed absolute configuration (24-epi) at C-24 of 1,25D₂. As presented in this paper, introduction of selected structural modifications simultaneously in two distinct parts of the vitamin D molecule resulted in a divergent group of analogues. Analogues showed lower VDR affinity in comparison to that of the parent hormones, 1,25D₂ and 1,25D₃, and they caused effective HL60 cell differentiation only at high concentrations of 100 nM and above. Unexpectedly, introducing of a 5,6-trans modification combined with C-22 hydroxyl and 24-epi configuration switched off entirely the cell differentiation activity of the analogue (PRI-1734). However, this analogue remained a moderate substrate for CYP24A1, as it was metabolized at 22%, compared to 35% for 1,25D₂. Other analogues from this series were either less (12% for PRI-1731 and PRI-1733) or more (52% for PRI-1732) resistant to the enzymatic deactivation. Although the inactive analogue PRI-1734 failed to show VDR antagonism, when tested in HL60 cells, its structure might be a good starting point for our design of a vitamin D antagonist. PMID:26840307

  14. Biological Evaluation of Double Point Modified Analogues of 1,25-Dihydroxyvitamin D2 as Potential Anti-Leukemic Agents

    PubMed Central

    Corcoran, Aoife; Nadkarni, Sharmin; Yasuda, Kaori; Sakaki, Toshiyuki; Brown, Geoffrey; Kutner, Andrzej; Marcinkowska, Ewa

    2016-01-01

    Structurally similar double-point modified analogues of 1,25-dihydroxyvitamin D2 (1,25D2) were screened in vitro for their pro-differentiating activity against the promyeloid cell line HL60. Their affinities towards human full length vitamin D receptor (VDR) and metabolic stability against human vitamin D 24-hydroxylase (CYP24A1) were also tested. The analogues (PRI-1730, PRI-1731, PRI-1732, PRI-1733 and PRI-1734) contained 5,6-trans modification of the A-ring and of the triene system, additional hydroxyl or unsaturation at C-22 in the side chain and reversed absolute configuration (24-epi) at C-24 of 1,25D2. As presented in this paper, introduction of selected structural modifications simultaneously in two distinct parts of the vitamin D molecule resulted in a divergent group of analogues. Analogues showed lower VDR affinity in comparison to that of the parent hormones, 1,25D2 and 1,25D3, and they caused effective HL60 cell differentiation only at high concentrations of 100 nM and above. Unexpectedly, introducing of a 5,6-trans modification combined with C-22 hydroxyl and 24-epi configuration switched off entirely the cell differentiation activity of the analogue (PRI-1734). However, this analogue remained a moderate substrate for CYP24A1, as it was metabolized at 22%, compared to 35% for 1,25D2. Other analogues from this series were either less (12% for PRI-1731 and PRI-1733) or more (52% for PRI-1732) resistant to the enzymatic deactivation. Although the inactive analogue PRI-1734 failed to show VDR antagonism, when tested in HL60 cells, its structure might be a good starting point for our design of a vitamin D antagonist. PMID:26840307

  15. The Effect of Analogues of 1α,25-Dihydroxyvitamin D₂ on the Regrowth and Gene Expression of Human Colon Cancer Cells Refractory to 5-Fluorouracil.

    PubMed

    Neska, Jacek; Swoboda, Paweł; Przybyszewska, Małgorzata; Kotlarz, Agnieszka; Bolla, Narasimha Rao; Miłoszewska, Joanna; Grygorowicz, Monika Anna; Kutner, Andrzej; Markowicz, Sergiusz

    2016-01-01

    This study aimed to evaluate the capacity of hypocalcemic analogues of 1α,25-dihydroxyvitamin D₂ (1,25D2) and 1α,25-dihydroxyvitamin D₃ (1,25D3) to inhibit regrowth and regulate the stemness-related gene expression in colon cancer cells undergoing renewal after exposure to 5-fluorouracil (5-FU). All of the tested analogues of 1,25D2 equally potently decreased the clonogenicity and the proliferative activity of HT-29 cells which survived the exposure to 5-FU, but differently regulated gene expression of these cells during their renewal. 1,25D2 and analogues (PRI-1907 and PRI-1917), as well as 1,25D3 and analogue PRI-2191, decreased the relative expression level of several stemness-related genes, such as NANOG, OCT3/4, PROM1, SOX2, ALDHA1, CXCR4, in HT-29/5-FU cells during their renewal, in comparison to untreated HT-29/5-FU cells. The other 1,25D2 analogues (PRI-1906 and PRI-1916) were not capable of downregulating the expression of these stemness-related genes as the analogues PRI-1907 and PRI-1917 did. All of the tested vitamin D analogues upregulated CDH1, the gene encoding E-cadherin associated with epithelial phenotype. Out of the series of analogues studied, side-chain branched analogues of 1,25D2 (PRI-1907, PRI-1917) and the analogue of 1,25D3 (PRI-2191) might be used to target cancer cells with stem-like phenotypes that survive conventional chemotherapy. PMID:27314328

  16. The Effect of Analogues of 1α,25-Dihydroxyvitamin D2 on the Regrowth and Gene Expression of Human Colon Cancer Cells Refractory to 5-Fluorouracil

    PubMed Central

    Neska, Jacek; Swoboda, Paweł; Przybyszewska, Małgorzata; Kotlarz, Agnieszka; Bolla, Narasimha Rao; Miłoszewska, Joanna; Grygorowicz, Monika Anna; Kutner, Andrzej; Markowicz, Sergiusz

    2016-01-01

    This study aimed to evaluate the capacity of hypocalcemic analogues of 1α,25-dihydroxyvitamin D2 (1,25D2) and 1α,25-dihydroxyvitamin D3 (1,25D3) to inhibit regrowth and regulate the stemness-related gene expression in colon cancer cells undergoing renewal after exposure to 5-fluorouracil (5-FU). All of the tested analogues of 1,25D2 equally potently decreased the clonogenicity and the proliferative activity of HT-29 cells which survived the exposure to 5-FU, but differently regulated gene expression of these cells during their renewal. 1,25D2 and analogues (PRI-1907 and PRI-1917), as well as 1,25D3 and analogue PRI-2191, decreased the relative expression level of several stemness-related genes, such as NANOG, OCT3/4, PROM1, SOX2, ALDHA1, CXCR4, in HT-29/5-FU cells during their renewal, in comparison to untreated HT-29/5-FU cells. The other 1,25D2 analogues (PRI-1906 and PRI-1916) were not capable of downregulating the expression of these stemness-related genes as the analogues PRI-1907 and PRI-1917 did. All of the tested vitamin D analogues upregulated CDH1, the gene encoding E-cadherin associated with epithelial phenotype. Out of the series of analogues studied, side-chain branched analogues of 1,25D2 (PRI-1907, PRI-1917) and the analogue of 1,25D3 (PRI-2191) might be used to target cancer cells with stem-like phenotypes that survive conventional chemotherapy. PMID:27314328

  17. Influences of calcium availability and tree species on Ca isotope fractionation in soil and vegetation

    USGS Publications Warehouse

    Page, B.D.; Bullen, T.D.; Mitchell, M.J.

    2008-01-01

    The calcium (Ca) isotope system is potentially of great use for understanding biogeochemical processes at multiple scales in forest ecosystems, yet remains largely unexplored for this purpose. In order to further our understanding of Ca behavior in forests, we examined two nearly adjacent hardwood-dominated catchments with differing soil Ca concentrations, developed from crystalline bedrock, to determine the variability of 44Ca/ 40Ca ratios (expressed as ??44Ca) within soil and vegetation pools. For both sugar maple and American beech, the Ca isotope compositions of the measured roots and calculated bulk trees were considerably lighter than those of soil pools at these sites, suggesting that the trees were able to preferentially take up light Ca at the root-soil interface. The Ca isotope compositions of three of four root samples were among the lightest values yet reported for terrestrial materials (??44Ca ???-3.95???). Our results further indicate that Ca isotopes were fractionated along the transpiration streams of both tree species with roots having the least ??44Ca values and leaf litter the greatest. An approximately 2??? difference in ??44Ca values between roots and leaf litter of both tree species suggests a persistent fractionation mechanism along the transpiration stream, likely related to Ca binding in wood tissue coupled with internal ion exchange. Finally, our data indicate that differing tree species demand for Ca and soil Ca concentrations together may influence Ca isotope distribution within the trees. Inter-catchment differences in Ca isotope distributions in soils and trees were minor, indicating that the results of our study may have broad transferability to studies of forest ecosystems in catchments developed on crystalline substrates elsewhere. ?? 2008 Springer Science+Business Media B.V.

  18. Fractionation of stable Ca isotopes in a shallow groundwater aquifer

    NASA Astrophysics Data System (ADS)

    Wiegand, B. A.

    2006-12-01

    Calcium has six stable isotopes, which fractionate during biological and inorganic processes, and thus may provide an important tracer in hydrological studies. To evaluate the potential use of Ca isotopes in determining sources and biogeochemical processes, groundwater from a shallow aquifer in NW Germany was investigated. 44Ca/40Ca ratios (expressed as Δ44Ca) of dissolved Ca2+ in water were analyzed by thermal ionization mass spectrometry using a ^{42}Ca-^{48}Ca double spike to correct for fractionation during the analytical procedure. 44Ca/40Ca ratios were normalized to seawater (Δ44Ca = 0), which was used as a standard. Groundwater samples were collected from monitoring wells in depths between 1.5 and 50 meters below surface. The aquifer is composed of Quaternary unconsolidated sediments. pH values increase from 4.5 in shallow wells to 7.6 at deeper levels, indicating low buffering capacities due to long-term decalcification processes in near-surface horizons. Near-surface groundwater is strongly undersaturated with respect to calcite whereas deep groundwater is close to saturation with calcite. Deep groundwater and several shallow wells are characterized by anoxic conditions while in parts of the aquifer oxic conditions prevail. Δ44Ca values of groundwater range between 0.2 and -1.4 ‰, indicating changes in the sources that are contributing to the dissolved Ca2+ loads, and biogeochemical fractionation processes. The main sources of calcium in the groundwater include mineral weathering and atmospheric deposition. Ca isotopes may be fractionated by secondary minerals precipitation, ion-exchange processes, and biological processes. In this presentation, possible scenarios will be discussed. Acknowledgements: Thanks to Dr. P. Groth, Dr. A. Mehling and the personnel of the Harzwasserwerke GmbH, Germany.

  19. A Calcium Isotope Record Across the Permian-Triassic Boundary From an Isolated Carbonate Platform in South China

    NASA Astrophysics Data System (ADS)

    Payne, J. L.; Turchyn, A. V.; Paytan, A.; Depaolo, D.; Lehrmann, D. J.; Yu, Y.; Wei, J.

    2008-12-01

    We measured the calcium isotope composition (δ44Ca) of marine carbonate sediments spanning the Permian-Triassic boundary on a carbonate platform in the Nanpanjiang Basin of southern China. The δ44Ca of the sediments exhibits a transient negative excursion of approximately 0.3‰ across the end-Permian extinction horizon. Isotopically light values persist through the basal Triassic Hindeodus parvus conodont zone. Strata within the overlying Isarcicella isarcica zone exhibit heavier values, similar to those observed in pre-extinction strata. The excursion could reflect either a change in the local fractionation between seawater Ca and carbonate minerals or a shift in the δ44Ca composition of seawater. Because the dominant mode of carbonate deposition shifted from skeletal to microbial across the boundary, a local change in fractionation is difficult to rule out. However, δ44Ca values return to pre-extinction values within strata still lacking any significant skeletal contribution, suggesting that the isotope excursion may instead record a global shift in δ44Ca of seawater. If the values measured do reflect an excursion in the isotope composition of calcium in the oceans, they imply an increase of 25 to 30% in the marine calcium concentration over a few hundred thousand years or less. Such an increase could result from ocean acidification via the addition of CO2 (and possibly SO2) to the ocean and atmosphere. Such a scenario could also account for the coeval negative excursion in δ13C and the preferential extinction of heavily calcified marine invertebrates.

  20. Natural calcium isotonic composition of urine as a marker of bone mineral balance

    USGS Publications Warehouse

    Skulan, J.; Bullen, T.; Anbar, A.D.; Puzas, J.E.; Shackelford, L.; LeBlanc, A.; Smith, S.M.

    2007-01-01

    Background: We investigated whether changes in the natural isotopic composition of calcium in human urine track changes in net bone mineral balance, as predicted by a model of calcium isotopic behavior in vertebrates. If so, isotopic analysis of natural urine or blood calcium could be used to monitor short-term changes in bone mineral balance that cannot be detected with other techniques. Methods: Calcium isotopic compositions are expressed as ??44Ca, or the difference in parts per thousand between the 44Ca/40Ca of a sample and the 44Ca/ 40Ca of a standard reference material. ??44Ca was measured in urine samples from 10 persons who participated in a study of the effectiveness of countermeasures to bone loss in spaceflight, in which 17 weeks of bed rest was used to induce bone loss. Study participants were assigned to 1 of 3 treatment groups: controls received no treatment, one treatment group received alendronate, and another group performed resistive exercise. Measurements were made on urine samples collected before, at 2 or 3 points during, and after bed rest. Results: Urine ??44Ca values during bed rest were lower in controls than in individuals treated with alendronate (P <0.05, ANOVA) or exercise (P <0.05), and lower than the control group baseline (P <0.05, Mest). Results were consistent with the model and with biochemical and bone mineral density data. Conclusion: Results confirm the predicted relationship between bone mineral balance and calcium isotopes, suggesting that calcium isotopic analysis of urine might be refined into a clinical and research tool. ?? 2007 American Association for Clinical Chemistry.

  1. Effects of ocean acidification on the marine calcium isotope record at the Paleocene-Eocene Thermal Maximum

    NASA Astrophysics Data System (ADS)

    Griffith, Elizabeth M.; Fantle, Matthew S.; Eisenhauer, Anton; Paytan, Adina; Bullen, Thomas D.

    2015-06-01

    Carbonates are used extensively to reconstruct paleoclimate and paleoceanographic conditions over geologic time scales. However, these archives are susceptible to diagenetic alteration via dissolution, recrystallization and secondary precipitation, particularly during ocean acidification events when intense dissolution can occur. Despite the possible effects of diagenesis on proxy fidelity, the impacts of diagenesis on the calcium isotopic composition (δ44Ca) of carbonates are unclear. To shed light on this issue, bulk carbonate δ44Ca was measured at high resolution in two Pacific deep sea sediment cores (ODP Sites 1212 and 1221) with considerably different dissolution histories over the Paleocene-Eocene Thermal Maximum (PETM, ∼ 55 Ma). The δ44Ca of marine barite was also measured at the deeper Site 1221, which experienced severe carbonate dissolution during the PETM. Large variations (∼ 0.8 ‰) in bulk carbonate δ44Ca occur in the deeper of the two sites at depths corresponding to the peak carbon isotope excursion, which correlate with a large drop in carbonate weight percent. Such an effect is not observed in either the 1221 barite record or the bulk carbonate record at the shallower Site 1212, which is also less affected by dissolution. We contend that ocean chemical changes associated with abrupt and massive carbon release into the ocean-atmosphere system and subsequent ocean acidification at the PETM affected the bulk carbonate δ44Ca record via diagenesis in the sedimentary column. Such effects are considerable, and need to be taken into account when interpreting Ca isotope data and, potentially, other geochemical proxies over extreme climatic events that drive sediment dissolution.

  2. Zirconium Evaluations for ENDF/B-VII.2 for the Fast Region

    NASA Astrophysics Data System (ADS)

    Brown, D. A.; Arcilla, R.; Capote, R.; Mughabghab, S. F.; Herman, M. W.; Trkov, A.; Kim, H. I.

    2014-04-01

    We have performed a new combined set of evaluations for 90-96Zr, including new resolved resonance parameterizations from Said Mughabghab for 90,91,92,94,96Zr and fast region calculations made with EMPIRE-3.1. Because 90Zr is a magic nucleus, stable Zr isotopes are nearly spherical. A new soft-rotor optical model potential is used allowing calculations of the inelastic scattering on low-lying coupled levels of vibrational nature. A soft rotor model describes dynamical deformations of the nucleus around the spherical shape and is implemented in EMPIRE/OPTMAN code. The same potential is used with rigid rotor couplings for odd-A nuclei. This then led to improved elastic angular distributions, helping to resolve improper leakage in the older ENDF/B-VII.1β evaluation in KAPL proprietary, ZPR and TRIGA benchmarks. Another consequence of 90Zr being a magic nucleus is that the level densities in both 90Zr and 91Zr are unusually low causing the (n,el) and (n,tot) cross sections to exhibit large fluctuations above the resolved resonance region. To accommodate these fluctuations, we performed a simultaneous constrained generalized least-square fit to (n,tot) for all isotopic and elemental Zr data in EXFOR, using EMPIRE's TOTRED scaling factor. TOTRED rescales total cross sections so that the optical model calculations are unaltered by the rescaling and the correct competition between channels is maintained. In this fit, all (n,tot) data in EXFOR was used for Ein>100 keV, provided the target isotopic makeup could be correctly understood, including spectrum averaged data and data with broad energy resolution. As a result of our fitting procedure, we will have full cross material and cross reaction covariance for all Zr isotopes and reactions.

  3. Role of projectile breakup effects and intrinsic degrees of freedom on fusion dynamics

    NASA Astrophysics Data System (ADS)

    Singh Gautam, Manjeet

    2016-05-01

    This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model (EDWSP model). In the case of the 28Si + 90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 28Si + 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron (multi-neutron) transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 28Si + 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li + 90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li + 90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakup of the projectile (6Li) before reaching the fusion barrier, as a consequence of low binding energy. Supported by Dr. D. S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  4. Alpha decay of {sup 181}Pb

    SciTech Connect

    Davids, C.N.; Henderson, D.J.; Hermann, R.

    1995-08-01

    The {alpha}-decay energy of {sup 181}Pb was measured as 7211(10) keV and 7044(15). In the first study the isotope was produced in {sup 90}Zr bombardments of {sup 94}Mo and, after traversing a velocity filter, implanted in a position-sensitive Si detector; no half life for {sup 181}Pb was reported. In the second study the isotope was produced in {sup 40}Ca bombardments of {sup 144}Sm and transported to a position in front of a Si(Au) surface barrier detector with a fast He-gas-jet capillary system; an estimate of 50 ms was determined for the {sup 181}Pb half life. Recently we investigated {sup 181}Pb {alpha} decay at ATLAS as part of a survey experiment in which a l-pnA beam of 400-MeV {sup 92}Mo was used to irradiate targets of {sup 89}Y, {sup 90,92,94}Zr, and {sup 92}Mo to examine yields for one- and two-nucleon evaporation products from symmetric cold-fusion reactions. Recoiling nuclei of interest were passed through the Fragment Mass Analyzer and implanted in a double-sided silicon strip detector for {alpha}-particle assay. With the {sup 90}Zr target we observed a group at 7065(20) keV which was correlated with A = 181 recoils and had a half life of 45(20) ms. Our new results for {sup 181}Pb therefore agreed with those of the second study. There was no indication in the {sup 90}Zr + {sup 92}Mo data of the 7211(10)-keV {alpha} particles seen by Keller et al. The interested reader is referred to the 1993 atomic mass evaluation wherein the input {alpha}-decay energies and resultant masses of the light Pb isotopes (including {sup 181}Pb) are discussed.

  5. Defects and Minor Phases in O+ and Zr+ Ion Co-implanted SrTiO3

    SciTech Connect

    Jiang, Weilin; Bowden, Mark E.; Zhu, Zihua; Jozwik, Przemyslaw A.; Jagielski, Jacek; Stonert, A.

    2012-01-04

    This article reports on a comprehensive experimental study of 16O+ and 90Zr+ ion co-implanted SrTiO3 (STO) single crystals. In this study, STO is used as a model material to simulate a waste form for disposal of radioactive 90Sr that decays to 90Y and subsequently to 90Zr by emission of beta particles. Sequential implantation of 16O+ and 90Zr+ ions was performed at 550 K to balance the charge and to avoid full amorphization of STO. A number of experimental methods have been employed to characterize the implanted sample, including multiaxial ion channeling analysis and high-resolution x-ray diffraction. Results show that a high defect concentration was generated and accumulated in STO during the ion implantation, but the crystal structure was not rendered fully amorphous even for an atomic percentage of implanted O and Zr up to 1.5 at.% each. Thermal annealing at 1273 K leads to significant defect recovery at the surface with little recovery occurring at the damage peak, where a modest recovery is observed upon further annealing at 1423 K. Some of the implanted Zr species are well aligned with the STO <001> axis, but all are barely located at the substitutional sites. A minor phase with a tetragonal structure is observed in the Zr distributed region, which has the <001> axis parallel to that of the STO host. The tetragonal phase survives annealing at 1423 K with only a small decrease in the c value. A general assessment of this model waste form is also provided in this report.

  6. Vibrational Properties of Nanograins and Interfaces in Nanocrystalline Materials

    SciTech Connect

    Stankov, S.; Sergueev, I.; Chumakov, A. I.; Rueffer, R.; Yue, Y. Z.; Hu, L.; Miglierini, M.; Sepiol, B.; Svec, P.

    2008-06-13

    The vibrational dynamics of nanocrystalline Fe{sub 90}Zr{sub 7}B{sub 3} was studied at various phases of crystallization. The density of phonon states (DOS) of the nanograins was separated from that of the interfaces for a wide range of grain sizes and interface thicknesses. The DOS of the nanograins does not vary with their size and down to 2 nm grains still closely resembles that of the bulk. The anomalous enhancement of the phonon states at low and high energies originates from the DOS of the interfaces and scales linearly to their atomic fraction.

  7. A process for the separation and purification of yttrium-90 for medical applications

    DOEpatents

    Horwitz, P.E.; Dietz, M.L.

    1993-01-01

    An extraction chromatographic method for the preparation of {sup 90}Y of high chemical and radiochemical purity is disclosed. After an initial purification of a {sup 90}Sr stock solution and a suitable period of {sup 90}Y ingrowth, the solution is passed through a series of strontium-selective chromatographic columns, each of which lowers the {sup 90}Sr content of the mixture by a factor of about 10{sup 3}. The {sup 90}Y remaining is freed from any residual {sup 90}Sr, from its {sup 90}Zr daughter, and from any remaining impurities by passing the sample through a final column designed to selectively retain yttrium.

  8. Fine Structure of the Gamow-Teller Resonance in {sup 90}Nb and Level Density of 1{sup +} States

    SciTech Connect

    Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V.Yu.; Richter, A.; Shevchenko, A.; Wambach, J.; Adachi, T.; Fujita, Y.; Shimbara, Y.; Berg, G.P.A.; Fujita, K.; Hatanaka, K.; Kamiya, J.; Nakanishi, K.; Sakamoto, N.; Sakemi, Y.; Shimizu, Y.; Wakasa, T.; Fujita, H.; Smit, F.D.

    2006-01-13

    The fine structure of the Gamow-Teller resonance in a medium-heavy nucleus is observed for the first time in a high-resolution {sup 90}Zr({sup 3}He,t){sup 90}Nb experiment at the Research Center for Nuclear Physics, Osaka. Using a novel wavelet analysis technique, it is possible to extract characteristic energy scales and to quantify their relative importance for the generation of the fine structure. This method combined with the selectivity of the reaction permits an extraction of the level density of 1{sup +} states in {sup 90}Nb.

  9. Process for the separation and purification of yttrium-90 for medical applications

    DOEpatents

    Horwitz, Philip E.; Dietz, Mark L.

    1994-01-01

    An extraction chromatographic method for the preparation of .sup.90 Y of high chemical and radiochemical purity is disclosed. After an initial purification of a .sup.90 Sr stock solution and a suitable period of .sup.90 Y ingrowth, the solution is passed through a series of strontium-selective chromatographic columns, each of which lowers the .sup.90 Sr content of the mixture by a factor of about 10.sup.3. The .sup.90 Y remaining is freed from any residual .sup.90 Sr, from its .sup.90 Zr daughter, and from any remaining impurities by passing the sample through a final column designed to selectively retain yttrium.

  10. Effects of weakly coupled channels on quasielastic barrier distributions

    SciTech Connect

    Piasecki, E.; Kisielinski, M.; Swiderski, L.; Keeley, N.; Rusek, K.; Strojek, I.; Gawlikowicz, W.; JastrzePbski, J.; Kordyasz, A.; Trzcinska, A.; Kliczewski, S.; Kowalczyk, M.; Khlebnikov, S.; Koshchiy, E.; Kozulin, E.; Loktev, T.; Smirnov, S.; Krogulski, T.; Mutterer, M.; Piasecki, K.

    2009-11-15

    Heavy-ion collisions often produce fusion barrier distributions with structures displaying a fingerprint of couplings to highly collective excitations. Similar distributions can be obtained from large-angle quasielastic scattering, although in this case, the role of the many weak direct-reaction channels is unclear. For {sup 20}Ne+{sup 90}Zr, we have observed the barrier structures expected for the highly deformed neon projectile; however, for {sup 20}Ne+{sup 92}Zr, we find significant extra absorption into a large number of noncollective inelastic channels. This leads to smearing of the barrier distribution and a consequent reduction in the ''resolving power'' of the quasielastic method.

  11. Process for the separation and purification of yttrium-90 for medical applications

    DOEpatents

    Horwitz, P.E.; Dietz, M.L.

    1994-11-29

    An extraction chromatographic method for the preparation of [sup 90]Y of high chemical and radiochemical purity is disclosed. After an initial purification of a [sup 90]Sr stock solution and a suitable period of [sup 90]Y ingrowth, the solution is passed through a series of strontium-selective chromatographic columns, each of which lowers the [sup 90]Sr content of the mixture by a factor of about 10[sup 3]. The [sup 90]Y remaining is freed from any residual [sup 90]Sr, from its [sup 90]Zr daughter, and from any remaining impurities by passing the sample through a final column designed to selectively retain yttrium. 5 figures.

  12. NEUTRON CROSS SECTION COVARIANCES FROM THERMAL ENERGY TO 20 MeV.

    SciTech Connect

    ROCHMAN,D.; HERMAN, M.; OBLOZINSKY, P.; MUGHABGHAB, S.F.; PIGNI, M.; KAWANO, T.

    2007-04-27

    We describe new method for energy-energy covariance calculation from the thermal energy up to 20 MeV. It is based on three powerful basic components: (i) Atlas of Neutron Resonances in the resonance region; (ii) the nuclear reaction model code EMPIRE in the unresolved resonance and fast neutron regions, and (iii) the Bayesian code KALMAN for correlations and error propagation. Examples for cross section uncertainties and correlations on {sup 90}Zr and {sup 193}Ir illustrate this approach in the resonance and fast neutron regions.

  13. Homodimerization of HYL1 ensures the correct selection of cleavage sites in primary miRNA

    PubMed Central

    Yang, Xi; Ren, Wenqing; Zhao, Qiuxia; Zhang, Peng; Wu, Feijie; He, Yuke

    2014-01-01

    MicroRNA (miRNA) plays an important role in the control of gene expression. HYPONASTIC LEAVES1 (HYL1) is a double-stranded RNA-binding protein that forms a complex with DICER-LIKE1 (DCL1) and SERRATE (SE) to process primary miRNA (pri-miRNA) into mature miRNA. Although HYL1 has been shown to partner with DCL1 to enhance miRNA accuracy, the mechanism by which HYL1 selects the DCL1-targeted cleavage sites in pri-miRNA has remained unknown. By mutagenesis of HYL1 and analysis of in vivo pri-miRNA processing, we investigated the role of HYL1 in pri-miRNA cleavage. HYL1 forms homodimers in which the residues Gly147 and Leu165 in the dsRBD2 domain are shown to be critical. Disruption of HYL1 homodimerization causes incorrect cleavage at sites in pri-miRNA without interrupting the interaction of HYL1 with DCL1 and accumulation of pri-miRNAs in HYL1/pri-miRNA complexes, leading to a reduction in the efficiency and accuracy of miRNAs that results in strong mutant phenotypes of the plants. HYL1 homodimers may function as a molecular anchor for DCL1 to cleave at a distance from the ssRNA–dsRNA junction in pri-miRNA. These results suggest that HYL1 ensures the correct selection of pri-miRNA cleavage sites through homodimerization and thus contributes to gene silencing and plant development. PMID:25294831

  14. Structural determinants of miR156a precursor processing in temperature-responsive flowering in Arabidopsis

    PubMed Central

    Kim, Wanhui; Kim, Hee-Eun; Jun, A Rim; Jung, Myeong Gyo; Jin, Suhyun; Lee, Joon-Hwa; Ahn, Ji Hoon

    2016-01-01

    MicroRNAs originate from primary transcripts (pri-miRNAs) containing hairpin structures. Plant pri-miRNAs have highly variable structures and little is known about the information encoded in their secondary structures. Arabidopsis miR156 is an ambient temperature-responsive miRNA and plays an important role in regulating flowering time. To identify the structural determinants for miR156 processing, we analyzed the effects of mutations introduced in the upper stem of pri-miR156a on its temperature-dependent processing and flowering time. The levels of pri-miR156a and mature miR156 were opposite at different temperatures. Mutations in the upper stem, especially the region closer to the miR156a/miR156a* duplex, reduced miR156 processing at 23 °C and 16 °C and caused a less severe phenotype compared with the un-mutated construct. Mutation in the second stem near the first cleavage site of pri-miR156a affected miR156 processing at 23 °C, but not at 16 °C. This was also seen in pri-miR172a, another ambient temperature-responsive miRNA. Replacement of the upper stem of pri-miR156a with that of pri-miR172a severely affected miR156 processing and flowering time. These results suggested that the upper stem of pri-miR156a is important for miR156 processing at different temperatures. In particular, the second stem adjacent to the first cleavage site plays a role in the regulation of ambient temperature-responsive flowering. PMID:27335452

  15. Identification and analysis of residues contained on β → α loops of the dual-substrate (βα)8 phosphoribosyl isomerase A specific for its phosphoribosyl anthranilate isomerase activity

    PubMed Central

    Noda-García, Lianet; Camacho-Zarco, Aldo R; Verdel-Aranda, Karina; Wright, Helena; Soberón, Xavier; Fülöp, Vilmos; Barona-Gómez, Francisco

    2010-01-01

    A good model to experimentally explore evolutionary hypothesis related to enzyme function is the ancient-like dual-substrate (βα)8 phosphoribosyl isomerase A (PriA), which takes part in both histidine and tryptophan biosynthesis in Streptomyces coelicolor and related organisms. In this study, we determined the Michaelis–Menten enzyme kinetics for both isomerase activities in wild-type PriA from S. coelicolor and in selected single-residue monofunctional mutants, identified after Escherichia coli in vivo complementation experiments. Structural and functional analyses of a hitherto unnoticed residue contained on the functionally important β → α loop 5, namely, Arg139, which was postulated on structural grounds to be important for the dual-substrate specificity of PriA, is presented for the first time. Indeed, enzyme kinetics analyses done on the mutant variants PriA_Ser81Thr and PriA_Arg139Asn showed that these residues, which are contained on β → α loops and in close proximity to the N-terminal phosphate-binding site, are essential solely for the phosphoribosyl anthranilate isomerase activity of PriA. Moreover, analysis of the X-ray crystallographic structure of PriA_Arg139Asn elucidated at 1.95 Å herein strongly implicates the occurrence of conformational changes in this β → α loop as a major structural feature related to the evolution of the dual-substrate specificity of PriA. It is suggested that PriA has evolved by tuning a fine energetic balance that allows the sufficient degree of structural flexibility needed for accommodating two topologically dissimilar substrates—within a bifunctional and thus highly constrained active site—without compromising its structural stability. PMID:20066665

  16. Lock and key to transcription: σ-DNA interaction.

    PubMed

    Liu, Xin; Bushnell, David A; Kornberg, Roger D

    2011-12-01

    How does RNA polymerase recognize a promoter in duplex DNA? How are the DNA strands pried apart to enable RNA synthesis? A crystal structure by Feklistov and Darst unexpectedly reveals that these two processes are interconnected. PMID:22153066

  17. Solution Method of Multi-Product Two-Stage Logistics Problem with Constraints of Delivery Course

    NASA Astrophysics Data System (ADS)

    Ataka, Shinichiro; Gen, Mitsuo

    The logistics network design is one of the important phase of Supply Chain Management (SCM) and it is the problem that should be optimized for long-term promotion of efficiency of the whole supply chain. Usually a plant produces different type of products. Even if it is a factory of the same company, delivery is different by a kind of a produced product. The restrictions which this model has are deeply concerned with TP in the real world. In this paper, we consider the logistics network design problems with multi-products and constraints for delivery course. To solve the problem, we used a hybrid priority-based Genetic Algorithm (h-priGA), and we tried the comparison experiment with priority-based Genetic Algorithm (priGA)and h-priGA, we show it about the effectiveness of h-priGA.

  18. ASSESSMENT OF BEST AVAILABLE TECHNOLOGY ECONOMICALLY ACHIEVABLE FOR SYNTHETIC RUBBER MANUFACTURING WASTEWATER

    EPA Science Inventory

    An assessment of The Best Available Technology Economically Achievable (BATEA) for treatment of synthetic rubber manufacturing wastewaters has been conducted. This assessment was based on feasibility tests with actual wastewater samples, both end-of-pipe (untreated) and after pri...

  19. Developing a Roadmap for Integrating Computational and In Vitro Approaches in Risk-Based Chemical Safety Decisions (SSCT-SweTox)

    EPA Science Inventory

    Multiple drivers shape the types of chemical assessments performed within many regulatory agencies including economic considerations, data availability, and the ultimate application of the assessment. The result is that chemical assessments are “fit-for-purpose” ranging from pri...

  20. Two-coordinate terminal zinc hydride complexes: synthesis, structure and preliminary reactivity studies.

    PubMed

    Dawkins, Michael J C; Middleton, Ewart; Kefalidis, Christos E; Dange, Deepak; Juckel, Martin M; Maron, Laurent; Jones, Cameron

    2016-08-18

    The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = -N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R'-2,6,4; R = Me, R' = Pr(i) (L'); R = Pr(i), R' = Me (L*); R = Pr(i), R' = Pr(i) (L(†))) have been prepared and shown by crystallographic studies to have near linear N-Zn-H fragments. The results of computational studies imply that any PhZn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds. PMID:27499232

  1. Ca isotope cycling in a forested ecosystem

    NASA Astrophysics Data System (ADS)

    Holmden, Chris; Bélanger, Nicolas

    2010-02-01

    Reports of large Ca isotope fractionations between trees and soils prompted this study of a Boreal forest ecosystem near La Ronge, Saskatchewan, to improve understanding of this phenomenon. The results on five tree species (black spruce, trembling aspen, white spruce, jack pine, balsam poplar) confirm that nutrient Ca uptake by plants favors the light isotopes, thus driving residual Ca in plant available soil pools towards enrichment in the heavy isotopes. Substantial within-tree fraction occurs in tissues formed along the transpiration stream, with low δ 44Ca values in fine roots (2 mm), intermediate values in stemwood, and high values in foliage. Separation factors between different plant tissues are similar between species, but the initial fractionation step in the tips of the fine roots is species specific, and/or sensitive to the local soil environment. Soil water δ 44Ca values appear to increase with depth to at least 35 cm below the top of the forest floor, which is close to the deepest level of fine roots. The heavy plant fractionated signature of Ca in the finely rooted upper soils filters downward where it is retained on ion exchange sites, leached into groundwater, and discharged into surface waters. The relationship between Ca uptake by tree fine roots and the pattern of δ 44Ca enrichment with soil depth was modeled for two Ca pools: the forest floor (litter) and the underlying (upper B) mineral soil. Six study plots were investigated along two hillside toposequences trending upwards from a first order stream. We used allometric equations describing the Ca distribution in boreal tree species to calculate weighted average δ 44Ca values for the stands in each plot and estimate Ca uptake rates. The δ 44Ca value of precipitation was measured, and soil weathering signatures deduced, by acid leaching of lower B mineral soils. Steady state equations were used to derive a set of model Ca fluxes and fractionation factors for each plot. The model reproduces

  2. Fusion of {sup 48}Ca+{sup 90,96}Zr above and below the Coulomb barrier

    SciTech Connect

    Stefanini, A.M.; Behera, B.R.; Corradi, L.; Fioretto, E.; Gadea, A.; Wu, Y.W.; Scarlassara, F.; Beghini, S.; Montagnoli, G.; Silvestri, R.; Trotta, M.; Szilner, S.; Zhang, H.Q.; Liu, Z.H.; Ruan, M.; Yang, F.; Rowley, N.

    2006-03-15

    Fusion-evaporation cross sections were measured in the two systems {sup 48}Ca+{sup 90,96}Zr in an energy range from well below to well above the Coulomb barrier. The sub-barrier fusion of {sup 48}Ca+{sup 90}Zr is reproduced by coupled-channels calculations including the lowest quadrupole and octupole vibrations of {sup 90}Zr, and using a Woods-Saxon potential with a standard diffuseness parameter a = 0.68 fm. However, the fusion cross sections are overestimated above the barrier. The low-energy slope of the excitation function for {sup 48}Ca+{sup 96}Zr is steeper. This implies a larger diffuseness parameter a = 0.85 fm. Fusion cross sections are well fit in the whole energy range, and the effect of the strong octupole vibration in {sup 96}Zr is predominant. The extracted fusion barrier distributions are reasonably well reproduced by calculations for both systems. A comparison with previous data for {sup 40}Ca+{sup 90,96}Zr is made in an attempt to clarify the role of transfer couplings in sub-barrier fusion.

  3. Investigation of reactions relevant for the γ process using in-beam γ-ray spectroscopy

    NASA Astrophysics Data System (ADS)

    Netterdon, L.; Endres, J.; Mayer, J.; Sauerwein, A.; Scholz, P.; Zilges, A.

    2016-01-01

    The reaction 89Y(p, γ)90Zr was studied at five proton energies close to the Gamow window. This reaction is of astrophysical importance, since it is located in a mass region, where the p-nuclei abundances are not well reproduced by network calculations. For this purpose, the in-beam technique utilizing the high-efficiency high-purity germanium (HPGe) detector array HORUS at the Tandem ion accelerator at the University of Cologne was used. The excellent agreement of the measured total cross sections with previous data shows, that the setup in Cologne is well suited for such measurements. An additional interesting outcome of this measurement are partial cross sections of the de-excitation of the 90 Zr compund nucleus up to the 15th excited state, an observable only accessible in this kind of high-resolution inbeam experiments. The experimental setup and preliminary results of the total and partial cross sections obtained for the 89Y(p, γ) reaction are presented. Additionally, we show results of a first test measurement of the a-capture reaction on the p-nucleus 92Mo using the in-beam technique with HPGe detectors.

  4. Analysis of 6Li Scattering at 240 MeV Using Different Nuclear Potentials

    NASA Astrophysics Data System (ADS)

    Al-Ghamdi, A. H.; Ibraheem, Awad A.

    2016-06-01

    Angular distributions of the elastic and inelastic scattering cross sections of 6Li projectile on different heavy ion target nuclei including the 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn at energy of 240 MeV have been analyzed by using two different folded potentials based on the CDM3Y6 and São Paulo potentials for the real part of the optical potential, while the imaginary parts have a phenomenological Woods-Saxon shape. Coupled channel calculations for the low-lying 2+ state at 1.369, 1.779, 3.832, 1.454, 2.186, and 1.29 MeV for 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn, respectively, have been carried out, and the best fit values for B(EL) with the above models have been extracted by fitting the inelastic scattering cross section and compared with the values of previous works. The total reaction cross section and real and imaginary volume integrals have also been investigated.

  5. Pygmy resonances and radiative nucleon captures for stellar nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Tsoneva, N.; Goriely, S.; Lenske, H.; Schwengner, R.

    2015-04-01

    The impact of low-energy multipole excitations and pygmy resonances on radiative neutron and proton-capture cross sections in nuclei close to the β -stability line is investigated. For this purpose, a microscopic theoretical approach based on self-consistent density functional theory and quasiparticle-random-phase-approximation formalism extended with multiphonon degrees of freedom is implemented in a statistical reaction model. The advantage of the method is the microscopic nuclear structure input for unified description of low-energy multiphonon excitations and pygmy and giant resonances. This is found to be important for the understanding of the fine structure and dynamics of the nuclear response function at low energies, which strongly influences nuclear reaction rates of astrophysical relevance. Calculations of the radiative capture cross sections of the reactions 85Kr (n ,γ )86Kr , 87Sr (n ,γ )88Sr , and 89Y (p ,γ )90Zr are discussed in comparison with experimental data. For the reactions 89Zr (n ,γ )90Zr and 91Mo (n ,γ )92Mo theoretical predictions of the reaction cross sections are made.

  6. (α ,γ ) cross section measurements in the region of light p nuclei

    NASA Astrophysics Data System (ADS)

    Quinn, S. J.; Spyrou, A.; Simon, A.; Battaglia, A.; Bowers, M.; Bucher, B.; Casarella, C.; Couder, M.; DeYoung, P. A.; Dombos, A. C.; Görres, J.; Kontos, A.; Li, Q.; Long, A.; Moran, M.; Paul, N.; Pereira, J.; Robertson, D.; Smith, K.; Smith, M. K.; Stech, E.; Talwar, R.; Tan, W. P.; Wiescher, M.

    2015-10-01

    The 90Zr(α ,γ )94Mo,92Zr(α ,γ )96Mo, and 74Ge(α ,γ )78Se reaction cross sections were measured for the first time in an effort to expand the existing experimental database for (α ,γ ) reactions relevant for the production of p nuclei in the universe. In particular, the 90Zr(α ,γ )94Mo reaction was identified by a sensitivity study for its potential impact on the γ -process mass flow in the region of light p nuclei. The measurements were performed for energies Eα=9.5 - 12.0 MeV at the University of Notre Dame using the SuN detector and the γ -summing technique. The results are compared to theoretical calculations from the talys and non-smoker nuclear reaction codes, and it is shown that the data greatly reduce the uncertainty in the cross section for the measured energies. The talys parameters that provide the best description of the experimental data are reported.

  7. p-process nucleosynthesis via proton-capture reactions in thermonuclear supernovae explosions

    NASA Astrophysics Data System (ADS)

    Endres, Anne; Arda, C.; Erbacher, P.; Glorius, J.; Göbel, K.; Hinrichs, O.; Mevius, E.; Reich, M.; Sonnabend, K.; Thomas, B.; Thomas, T.

    2015-05-01

    Model calculations within the framework of the so-called γ process show an underproduction of the p nucleus with the highest isotopic abundace 92Mo. This discrepancy can be narrowed by taking into account the alternative production site of a type Ia supernova explosion. Here, the nucleus 92Mo can be produced by a sequence of proton-capture reactions. The amount of 92Mo nuclei produced via this reaction chain is most sensitive to the reactions 90Zr(p,γ) and 91Nb(p,γ). Both rates have to be investigated experimentally to study the impact of this nucleosynthesis aspect on the long-standing 92Mo-problem. We have already measured the proton-capture reaction on 90Zr using high-resolution in-beam γ-ray spectroscopy. In this contribution, we will present our preliminary results of the total cross sections as well as the partial cross sections. Furthermore, we plan to measure the 91Nb(p,γ) reaction soon. Due to the radioactive target material, the 91Nb nuclei have to be produced prior to the experiment. The current status of this production will be presented in this contribution.

  8. Direct Neutron Capture Calculations with Covariant Density Functional Theory Inputs

    NASA Astrophysics Data System (ADS)

    Zhang, Shi-Sheng; Peng, Jin-Peng; Smith, Michael S.; Arbanas, Goran; Kozub, Ray L.

    2014-09-01

    Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Predictions of direct neutron capture are of vital importance for simulations of nucleosynthesis in supernovae, merging neutron stars, and other astrophysical environments. We calculate the direct capture cross sections for E1 transitions using nuclear structure information from a covariant density functional theory as input for the FRESCO coupled-channels reaction code. We find good agreement of our predictions with experimental cross section data on the double closed-shell targets 16O, 48Ca, and 90Zr, and the exotic nucleus 36S. Extensions of the technique for unstable nuclei and for large-scale calculations will be discussed. Supported by the U.S. Dept. of Energy, Office of Nuclear Physics.

  9. Binding of NF-kappaB p65 subunit to the promoter elements is involved in LPS-induced transactivation of miRNA genes in human biliary epithelial cells

    PubMed Central

    Zhou, Rui; Hu, Guoku; Gong, Ai-Yu; Chen, Xian-Ming

    2010-01-01

    The majority of human miRNA genes is transcribed by polymerase II and can be classified as class II genes similar to protein-coding genes. Whereas current research on miRNAs has focused on the physiological and pathological functions, the molecular mechanisms underlying their transcriptional regulation are largely unknown. We recently reported that lipopolysaccharide (LPS) alters mature miRNA expression profile in human biliary epithelial cells. In this study, we tested the role of transcription factor NF-κB in LPS-induced transcription of select miRNA genes. Of the majority of LPS-up-regulated mature miRNAs in cultured human biliary epithelial cells, potential NF-κB binding sites were identified in the putative promoter elements of their corresponding genes. Inhibition of NF-κB activation by SC-514, an IKK2 inhibitor, blocked LPS-induced up-regulation of a subset of pri-miRNAs, including pri-miR-17-92, pri-miR-125b-1, pri-miR-21, pri-miR-23b-27b-24-1, pri-miR-30b, pri-miR-130a and pri-miR-29a. Moreover, direct binding of NF-κB p65 subunit to the promoter elements of mir-17-92, mir-125b-1, mir-21, mir-23b-27b-24-1, mir-30b and mir-130a genes was identified by chromatin immunoprecipitation analysis and confirmed by the luciferase reporter assay. Thus, a subset of miRNA genes is regulated in human biliary epithelial cells through NF-κB activation induced by LPS, suggesting a role of the NF-κB pathway in the transcriptional regulation of miRNA genes. PMID:20144951

  10. N6-methyl-adenosine (m6A) marks primary microRNAs for processing

    PubMed Central

    Alarcón, Claudio R.; Lee, Hyeseung; Goodarzi, Hani; Halberg, Nils

    2015-01-01

    The first step in the biogenesis of microRNAs is the processing of primary microRNAs (pri-miRNAs) by the microprocessor complex, composed of the RNA binding protein DGCR8 and the ribonuclease type III DROSHA1–4. This initial event requires the recognition of the junction between the stem and the flanking single-stranded RNA of the pri-miRNA hairpin by DGCR8 followed by recruitment of DROSHA, which cleaves the RNA duplex to yield the pre-miRNA product5. While the mechanisms underlying pri-miRNA processing have been elucidated, the mechanism by which DGCR8 recognizes and binds pri-miRNAs as opposed to other secondary structures present in transcripts is not understood. We find that methyltransferase like 3 (METTL3) methylates pri-miRNAs, marking them for recognition and processing by DGCR8. Consistent with this, METTL3 depletion reduced the binding of DGCR8 to pri-miRNAs and resulted in the global reduction of mature miRNAs and concomitant accumulation of unprocessed pri-miRNAs. In vitro processing reactions confirmed the sufficiency of the m6A mark in promoting pri-miRNA processing. Finally, gain-of-function experiments revealed that METTL3 is sufficient to enhance miRNA maturation in a global and non-cell-type specific manner. Our findings reveal that the m6A mark acts as a key post-transcriptional modification that promotes the initiation of miRNA biogenesis. PMID:25799998

  11. Calcium isotopic composition of mantle peridotites

    NASA Astrophysics Data System (ADS)

    Huang, F.; Kang, J.; Zhang, Z.

    2015-12-01

    Ca isotopes are useful to decipher mantle evolution and the genetic relationship between the Earth and chondrites. It has been observed that Ca isotopes can be fractionated at high temperature [1-2]. However, Ca isotopic composition of the mantle peridotites and fractionation mechanism are still poorly constrained. Here, we report Ca isotope composition of 12 co-existing pyroxene pairs in 10 lherzolites, 1 harzburgite, and 1 wehrlite xenoliths collected from Hainan Island (South Eastern China). Ca isotope data were measured on a Triton-TIMS using the double spike method at the Guangzhou Institute of Geochemistry, CAS. The long-term external error is 0.12‰ (2SD) based on repeated analyses of NIST SRM 915a and geostandards. δ44Ca of clinopyroxenes except that from the wehrlite ranges from 0.85‰ to 1.14‰, while opx yields a wide range from 0.98‰ up to 2.16‰. Co-existing pyroxene pairs show large ∆44Caopx-cpx (defined as δ44Caopx-δ44Cacpx) ranging from 0 to 1.23‰, reflecting equilibrium fractionation controlled by variable Ca contents in the opx. Notably, clinopyroxene of wehrlite shows extremely high δ44Ca (3.22‰). δ44Ca of the bulk lherzolites and harzburgites range from 0.86‰ to 1.14‰. This can be explained by extracting melts with slightly light Ca isotopic compositions. Finally, the high δ44Ca of the wehrlite (3.22‰) may reflect metasomatism by melt which has preferentially lost light Ca isotopes due to chemical diffusion during upwelling through the melt channel. [1] Amini et al (2009) GGR 33; [2] Huang et al (2010) EPSL 292.

  12. Are 44Ti-producing supernovae exceptional?

    NASA Astrophysics Data System (ADS)

    The, L.-S.; Clayton, D. D.; Diehl, R.; Hartmann, D. H.; Iyudin, A. F.; Leising, M. D.; Meyer, B. S.; Motizuki, Y.; Schönfelder, V.

    2006-05-01

    According to standard models supernovae produce radioactive 44Ti, which should be visible in gamma-rays following decay to 44Ca for a few centuries. 44Ti production is believed to be the source of cosmic 44Ca, whose abundance is well established. Yet, gamma-ray telescopes have not seen the expected young remnants of core collapse events. The 44Ti mean life of τ ≃ 89 y and the Galactic supernova rate of ≃3/100 y imply ≃several detectable 44Ti gamma-ray sources, but only one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which produce much 44Ti are expected to occur primarily in the inner part of the Galaxy, where young massive stars are most abundant. Because the Galaxy is transparent to gamma-rays, this should be the dominant location of expected gamma-ray sources. Yet the Cas A SNR as the only one source is located far from the inner Galaxy (at longitude 112°). We evaluate the surprising absence of detectable supernovae from the past three centuries. We discuss whether our understanding of SN explosions, their 44Ti yields, their spatial distributions, and statistical arguments can be stretched so that this apparent disagreement may be accommodated within reasonable expectations, or if we have to revise some or all of the above aspects to bring expectations in agreement with the observations. We conclude that either core collapse supernovae have been improbably rare in the Galaxy during the past few centuries, or 44Ti-producing supernovae are atypical supernovae. We also present a new argument based on 44Ca/40Ca ratios in mainstream SiC stardust grains that may cast doubt on massive-He-cap type I supernovae as the source of most galactic 44Ca.

  13. Cellular Response to a Novel Fetal Acellular Collagen Matrix: Implications for Tissue Regeneration

    PubMed Central

    Rennert, Robert C.; Garg, Ravi K.; Gurtner, Geoffrey C.

    2013-01-01

    Introduction. PriMatrix (TEI Biosciences Inc., Boston, MA, USA) is a novel acellular collagen matrix derived from fetal bovine dermis that is designed for use in partial- and full-thickness wounds. This study analyzes the cellular response to PriMatrix in vivo, as well as the ability of this matrix to facilitate normal tissue regeneration. Methods. Five by five mm squares of rehydrated PriMatrix were implanted in a subcutaneous fashion on the dorsum of wild-type mice. Implant site tissue was harvested for histology, immunohistochemistry (IHC), and flow cytometric analyses at multiple time points until day 28. Results. PriMatrix implants were found to go through a biological progression initiated by a transient infiltrate of inflammatory cells, followed by mesenchymal cell recruitment and vascular development. IHC analysis revealed that the majority of the implanted fetal dermal collagen fibers persisted through day 28 but underwent remodeling and cellular repopulation to form tissue with a density and morphology consistent with healthy dermis. Conclusions. PriMatrix implants undergo progressive in vivo remodeling, facilitating the regeneration of histologically normal tissue through a mild inflammatory and progenitor cell response. Regeneration of normal tissue is especially important in a wound environment, and these findings warrant further investigation of PriMatrix in this setting. PMID:23970899

  14. Pose Estimation using 1D Fourier Transform and Euclidean Distance Matching of CAD Model and Inspected Model Part

    NASA Astrophysics Data System (ADS)

    Zulkoffli, Zuliani; Abu Bakar, Elmi

    2016-02-01

    This paper present pose estimation relation of CAD model object and Projection Real Object (PRI). Image sequence of PRI and CAD model rotate on z axis at 10 degree interval in simulation and real scene used in this experiment. All this image is go through preprocessing stage to rescale object size and image size and transform all the image into silhouette. Correlation of CAD and PRI image is going through in this stage. Magnitude spectrum shows a reliable value in range 0.99 to 1.00 and Phase spectrum correlation shows a fluctuate graph in range 0.56 - 0.97. Euclidean distance correlation graph for CAD and PRI shows 2 zone of similar value due to almost symmetrical object shape. Processing stage of retrieval inspected PRI image in CAD database was carried out using range phase spectrum and maximum magnitude spectrum value within ±10% tolerance. Additional processing stage of retrieval inspected PRI image using Euclidean distance within ±5% tolerance also carried out. Euclidean matching shows a reliable result compared to range phase spectrum and maximum magnitude spectrum value by sacrificing more than 5 times processing time.

  15. Global Prioritization of Disease Candidate Metabolites Based on a Multi-omics Composite Network

    PubMed Central

    Yao, Qianlan; Xu, Yanjun; Yang, Haixiu; Shang, Desi; Zhang, Chunlong; Zhang, Yunpeng; Sun, Zeguo; Shi, Xinrui; Feng, Li; Han, Junwei; Su, Fei; Li, Chunquan; Li, Xia

    2015-01-01

    The identification of disease-related metabolites is important for a better understanding of metabolite pathological processes in order to improve human medicine. Metabolites, which are the terminal products of cellular regulatory process, can be affected by multi-omic processes. In this work, we propose a powerful method, MetPriCNet, to predict and prioritize disease candidate metabolites based on integrated multi-omics information. MetPriCNet prioritized candidate metabolites based on their global distance similarity with seed nodes in a composite network, which integrated multi-omics information from the genome, phenome, metabolome and interactome. After performing cross-validation on 87 phenotypes with a total of 602 metabolites, MetPriCNet achieved a high AUC value of up to 0.918. We also assessed the performance of MetPriCNet on 18 disease classes and found that 4 disease classes achieved an AUC value over 0.95. Notably, MetPriCNet can also predict disease metabolites without known disease metabolite knowledge. Some new high-risk metabolites of breast cancer were predicted, although there is a lack of known disease metabolite information. A predicted disease metabolic landscape was constructed and analyzed based on the results of MetPriCNet for 87 phenotypes to help us understand the genetic and metabolic mechanism of disease from a global view. PMID:26598063

  16. Crystal structure of DnaT84–153-dT10 ssDNA complex reveals a novel single-stranded DNA binding mode

    PubMed Central

    Liu, Zheng; Chen, Peng; Wang, Xuejuan; Cai, Gang; Niu, Liwen; Teng, Maikun; Li, Xu

    2014-01-01

    DnaT is a primosomal protein that is required for the stalled replication fork restart in Escherichia coli. As an adapter, DnaT mediates the PriA-PriB-ssDNA ternary complex and the DnaB/C complex. However, the fundamental function of DnaT during PriA-dependent primosome assembly is still a black box. Here, we report the 2.83 Å DnaT84–153-dT10 ssDNA complex structure, which reveals a novel three-helix bundle single-stranded DNA binding mode. Based on binding assays and negative-staining electron microscopy results, we found that DnaT can bind to phiX 174 ssDNA to form nucleoprotein filaments for the first time, which indicates that DnaT might function as a scaffold protein during the PriA-dependent primosome assembly. In combination with biochemical analysis, we propose a cooperative mechanism for the binding of DnaT to ssDNA and a possible model for the assembly of PriA-PriB-ssDNA-DnaT complex that sheds light on the function of DnaT during the primosome assembly and stalled replication fork restart. This report presents the first structure of the DnaT C-terminal complex with ssDNA and a novel model that explains the interactions between the three-helix bundle and ssDNA. PMID:25053836

  17. Vitamin D Analogs Potentiate the Antitumor Effect of Imatinib Mesylate in a Human A549 Lung Tumor Model

    PubMed Central

    Maj, Ewa; Filip-Psurska, Beata; Świtalska, Marta; Kutner, Andrzej; Wietrzyk, Joanna

    2015-01-01

    In previous papers, we presented data on studies on the anticancer activity of the vitamin D3 analogs, named PRI-2191 and PRI-2205, in different cancer models. In this study, we showed the improved antiproliferative activity of a combination of imatinib mesylate (Gleevec, GV) and cytostatic agents in in vitro studies, when used with a third compound, namely PRI-2191, in an A549 human lung cancer model. Furthermore, we analyzed the influence of both PRI-2191, as well as PRI-2205 on the anticancer activity of GV in mice bearing A549 tumors. The route of PRI-2191 analog administration showed a significant impact on the outcome of GV treatment: subcutaneous injection was more efficient and less toxic than oral gavage. Moreover, both vitamin D compounds increased the anticancer activity of GV; however, they might also potentiate some adverse effects. We also evaluated in tumor tissue the expression of VEGF, PDGF-BB, vitamin D receptor, CYP27B1, CYP24, p53 and Bcl-2, as well as PDGF receptors: α and β. We observed the upregulation of p53 expression and the downregulation of Bcl-2, as well as VEGF in A549 tumors as a result of the tested treatment. However, vitamin D analogs did not significantly influence the expression of these proteins. PMID:26580599

  18. Vitamin D Analogs Potentiate the Antitumor Effect of Imatinib Mesylate in a Human A549 Lung Tumor Model.

    PubMed

    Maj, Ewa; Filip-Psurska, Beata; Świtalska, Marta; Kutner, Andrzej; Wietrzyk, Joanna

    2015-01-01

    In previous papers, we presented data on studies on the anticancer activity of the vitamin D₃ analogs, named PRI-2191 and PRI-2205, in different cancer models. In this study, we showed the improved antiproliferative activity of a combination of imatinib mesylate (Gleevec, GV) and cytostatic agents in in vitro studies, when used with a third compound, namely PRI-2191, in an A549 human lung cancer model. Furthermore, we analyzed the influence of both PRI-2191, as well as PRI-2205 on the anticancer activity of GV in mice bearing A549 tumors. The route of PRI-2191 analog administration showed a significant impact on the outcome of GV treatment: subcutaneous injection was more efficient and less toxic than oral gavage. Moreover, both vitamin D compounds increased the anticancer activity of GV; however, they might also potentiate some adverse effects. We also evaluated in tumor tissue the expression of VEGF, PDGF-BB, vitamin D receptor, CYP27B1, CYP24, p53 and Bcl-2, as well as PDGF receptors: α and β. We observed the upregulation of p53 expression and the downregulation of Bcl-2, as well as VEGF in A549 tumors as a result of the tested treatment. However, vitamin D analogs did not significantly influence the expression of these proteins. PMID:26580599

  19. Integrating Solar Induced Fluorescence and the Photochemical Reflectance Index for Estimating Gross Primary Production in a Cornfield

    NASA Technical Reports Server (NTRS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Zhang, Qingyuan; Huemmrich, Karl F.; Campbell, Petya K. E.; Corp, Lawrence A.; Cook, Bruce D.; Kustas, William P.; Daughtry, Criag S.

    2013-01-01

    The utilization of remotely sensed observations for light use efficiency (LUE) and tower-based gross primary production (GPP) estimates was studied in a USDA cornfield. Nadir hyperspectral reflectance measurements were acquired at canopy level during a collaborative field campaign conducted in four growing seasons. The Photochemical Reflectance Index (PRI) and solar induced chlorophyll fluorescence (SIF), were derived. SIF retrievals were accomplished in the two telluric atmospheric oxygen absorption features centered at 688 nm (O2-B) and 760 nm (O2-A). The PRI and SIF were examined in conjunction with GPP and LUE determined by flux tower-based measurements. All of these fluxes, environmental variables, and the PRI and SIF exhibited diurnal as well as day-to-day dynamics across the four growing seasons. Consistent with previous studies, the PRI was shown to be related to LUE (r2 = 0.54 with a logarithm fit), but the relationship varied each year. By combining the PRI and SIF in a linear regression model, stronger performances for GPP estimation were obtained. The strongest relationship (r2 = 0.80, RMSE = 0.186 mg CO2/m2/s) was achieved when using the PRI and SIF retrievals at 688 nm. Cross-validation approaches were utilized to demonstrate the robustness and consistency of the performance. This study highlights a GPP retrieval method based entirely on hyperspectral remote sensing observations.

  20. [Estimation of light-use efficiency of China' s mid-subtropical planted coniferous forest based on flux measurements and spectral observations].

    PubMed

    Chen, Die-cong; Wang, Shao-qiang; Huang, Kun; Zhou, Lei; Yu, Quan-zhou; Wang, Hui-min; Sun, Lei-gang

    2015-11-01

    The photochemical reflectance index (PRI) calculated from spectral reflectance has universally become a proxy for the light-use efficiency (LUE), which significantly improves the LUE-based estimation of ecosystem gross primary productivity on a large scale through upscaling. In this study, we observed the vegetation spectral reflectance of a planted subtropical coniferous forest from the top of a flux tower at Qianyanzhou Station, one of the ChinaFLUX sites, in September and December 2013, and simultaneously measured CO2 flux and meteorological variables for correlation and regression analysis. Results showed that PRI had a better correlation with LUE (R2 = 0.20, P< 0.001) than that of normalized difference vegetation index (NDVI), i.e., PRI was preferred in LUE retrieval. During the whole observation period, PRI and soil water content (SWC)-based bivariate regression model correlated well with LUE (R2 = 0.29, P < 0.001 and R2 = 0.30, P < 0.01 for daytime and midday observation, respectively), but in autumn the bivariate regression model of PRI and vapor pressure deficit (VPD) had a higher correlation with LUE (R2 = 0.448, P < 0.001) for midday observation, which showed that environmental factors, i.e., SWC and VPD, had a potential in improving the LUE retrieval from PRI, but the choice of appropriate environmental factors depended on season. PMID:26915199

  1. Ca cycling and isotopic fluxes in forested ecosystems in Hawaii

    USGS Publications Warehouse

    Wiegand, B.A.; Chadwick, O.A.; Vitousek, P.M.; Wooden, J.L.

    2005-01-01

    Biogeochemical processes fractionate Ca isotopes in plants and soils along a 4 million year developmental sequence in the Hawaiian Islands. We observed that plants preferentially take up 40Ca relative to 44Ca, and that biological fractionation and changes in the relative contributions from volcanic and marine sources produce a significant increase in 44Ca in soil exchangeable pools. Our results imply moderate fluxes enriched in 44Ca from strongly nutrient-depleted old soils, in contrast with high 40Ca fluxes in young and little weathered environments. In addition, biological fractionation controls divergent geochemical pathways of Ca and Sr in the plant-soil system. While Ca depletes progressively with increasing soil age, Sr/Ca ratios increase systematically. Sr isotope ratios provide a valuable tracer for provenance studies of alkaline earth elements in forested ecosystems, but its usefulness is limited when deciphering biogeochemical processes involved in the terrestrial Ca cycle. Ca isotopes in combination with Sr/ Ca ratios reveal more complex processes involved in the biogeochemistry of Ca and Sr. Copyright 2005 by the American Geophysical Union.

  2. Quantum design using a multiple internal reflections method in a study of fusion processes in the capture of alpha-particles by nuclei

    NASA Astrophysics Data System (ADS)

    Maydanyuk, Sergei P.; Zhang, Peng-Ming; Belchikov, Sergei V.

    2015-08-01

    A high precision method to determine fusion in the capture of α-particles by nuclei is presented. For α-capture by 40Ca and 44Ca, such an approach gives (1) the parameters of the α-nucleus potential and (2) fusion probabilities. This method found new parametrization and fusion probabilities and decreased the error by 41.72 times for α +40Ca and 34.06 times for α +44Ca in a description of experimental data in comparison with existing results. We show that the sharp angular momentum cutoff proposed by Glas and Mosel is a rough approximation, Wong's formula and the Hill-Wheeler approach determine the penetrability of the barrier without a correct consideration of the barrier shape, and the WKB approach gives reduced fusion probabilities. Based on our fusion probability formula, we explain the difference between experimental cross-sections for α +40Ca and α +44Ca, which is connected with the theory of coexistence of the spherical and deformed shapes in the ground state for nuclei near the neutron magic shell N = 20. To provide deeper insight into the physics of nuclei with the new magic number N = 26, the cross-section for α +46Ca is predicted for future experimental tests. The role of nuclear deformations in calculations of the fusion probabilities is analyzed.

  3. Monitoring water stress and fruit quality in an orange orchard under regulated deficit irrigation using narrow-band structural and physiological remote sensing indices

    NASA Astrophysics Data System (ADS)

    Stagakis, S.; González-Dugo, V.; Cid, P.; Guillén-Climent, M. L.; Zarco-Tejada, P. J.

    2012-07-01

    This paper deals with the monitoring of water status and the assessment of the effect of stress on citrus fruit quality using structural and physiological remote sensing indices. Four flights were conducted over a citrus orchard in 2009 using an unmanned aerial vehicle (UAV) carrying a multispectral camera with six narrow spectral bands in the visible and near infrared. Physiological indices such as the Photochemical Reflectance Index (PRI570), a new structurally robust PRI formulation that uses the 515 nm as the reference band (PRI515), and a chlorophyll ratio (R700/R670) were compared against the Normalized Difference Vegetation Index (NDVI), Renormalized Difference Vegetation Index (RDVI) and Modified Triangular Vegetation Index (MTVI) canopy structural indices for their performance in tracking water status and the effects of sustained water stress on fruit quality at harvest. The irrigation setup in the commercial orchard was compared against a treatment scheduled to satisfy full requirements (based on estimated crop evapotranspiration) using two regulated deficit irrigation (RDI) strategies. The water status of the trees throughout the experiment was monitored with frequent field measurements of stem water potential (Ψx), while titratable acidity (TA) and total soluble solids (TSS) were measured at harvest on selected trees from each irrigation treatment. The high spatial resolution of the multispectral imagery (30 cm pixel size) enabled identification of pure tree crown components, extracting the tree reflectance from shaded, sunlit and aggregated pixels. The physiological and structural indices were then calculated from each tree at the following levels: (i) pure sunlit tree crown, (ii) entire crown, aggregating the within-crown shadows, and (iii) simulating a lower resolution pixel, including tree crown, sunlit and shaded soil pixels. The resulting analysis demonstrated that both PRI formulations were able to track water status, except when water stress

  4. Retrieval of the photochemical reflectance index for assessing xanthophyll cycle activity: a comparison of near-surface optical sensors

    NASA Astrophysics Data System (ADS)

    Harris, A.; Gamon, J. A.; Pastorello, G. Z.; Wong, C. Y. S.

    2014-11-01

    Unattended optical sensors are increasingly being deployed on eddy covariance flux towers and are often used to complement existing vegetation and micrometeorological measurements to enable assessment of biophysical states and biogeochemical processes over a range of spatial scales. Of particular interest are sensors that can measure the photochemical reflectance index (PRI), which can provide information pertaining to leaf pigments and photosynthetic activity. This interest has facilitated the production of a new range of lower-cost multispectral sensors specifically designed to measure temporal changes in the PRI signal. However, little is known about the characteristics (spectral, radiometric and temporal) of many of these PRI sensors, making it difficult to compare data obtained from these sensors across time, geographical locations and instruments. Furthermore, direct testing of the capability of these sensors to actually detect the conversion of the xanthophyll cycle, which is the original biological basis of the PRI diurnal signal, is largely absent, often resulting in an unclear interpretation of the signal, particularly given the wide range of factors now known to influence PRI. Through a series of experiments, we assess the sensitivity of one of the leading brands of PRI sensor (Skye SKR 1800) to changes in vegetation photosynthetic activity in response to changing irradiance. We compare the results with those obtained using a more expensive industry-standard visible to near-infrared hyperspectral spectrometer (PP Systems UniSpec) and determine the radiometric compatibility of measurements made by the different instruments. Results suggest that the SKR 1800 instrument is able to track rapid (seconds to minutes) and more gradual diurnal changes in photosynthetic activity associated with xanthophyll cycle pigment conversion. Measurements obtained from both the high and lower cost instrument were significantly linearly correlated but were subject to a large

  5. Magnesium and calcium isotopic characteristics of Tengchong volcanics: Recycling of marine carbonates into the SE Tibetan mantle

    NASA Astrophysics Data System (ADS)

    Liu, F.; Zhang, Z.; Liu, Y.; Zhu, H.; Kang, J.; Zhang, C.; Sun, W.; Wang, G. Q.

    2015-12-01

    Post-collisional high-K calc-alkaline volcanic rocks are widely distributed in Tengchong in the southeastern margin of Tibetan Plateau. Previous considerable petrological and Sr-Nd-Pb isotopic researches undoubtedly indicate that the mantle beneath Tengchong is heterogeneous and enriched. However, the genesis of such a kind of mantle is still poor understood and needs more constrains. One of the key points lead to the answer to this question is that, is there any recycled carbonate involved? Therefore, Magnesium and calcium isotopic compositions of mantle-derived volcanics should be investigated because they are good candidates to be potentially used to trace recycling of ancient marine carbonates into the mantle. In this study, we report high-precision Mg and Ca isotopic compositions for calc-alkaline volcanic rocks in Tengchong. These volcanic rocks show significantly lighter δ26Mg values (-0.44 to -0.36‰) than the mantle value (-0.25±0.07‰). Similarly, they display lighter δ44Ca values (0.65-0.80‰) than the mantle value (1.05±0.04‰). Because neither δ26Mg nor δ44Ca are correlated with SiO2 (50.8-61.6 wt.%) contents, and there is no relationships between δ26Mg or δ44Ca and typical trace element abundance ratios (e.g. Sm/Yb, Ba/Y), we conclude that magma differentiation or partial melting would lead to limited Mg and Ca isotopes fractionation. Thus, low δ26Mg and δ44Ca signatures of Tengchong volcanic rocks probably reflect that the δ26Mg and δ44Ca characteristics of the underneath mantle source, and are resulted from adding ancient marine carbonates into the primitive mantle which has low Mg and Ca isotopic compositions. Our model simulation using a two end-member mixing between Mg-Ca isotopic compositions of primitive mantle and ancient marine carbonate indicates that carbonates involved in the mantle source is mainly dolostone with minor limestone. Combined with the geotectonic evolution history in Tengchong, we propose that the enriched

  6. Calcium content and calcium exchange in dark-adapted toad rods.

    PubMed Central

    Fain, G L; Schröder, W H

    1985-01-01

    We have used laser-activated micro mass analysis (l.a.m.m.a.) and energy-dispersive X-ray analysis (e.d.x.) to measure Ca content and Ca movements in 'red' rod photoreceptors in the dark-adapted retina of the toad, Bufo marinus. Measurements with both l.a.m.m.a. and e.d.x. show that intact rod outer segments contain 4-5 mmol total Ca/l wet tissue volume, or 1-2 Ca per rhodopsin. We could detect no significant variation in the total Ca as a function of distance across or up and down the outer segment. In the inner segment, Ca could be detected only within the mitochondria-rich ellipsoid body, where the total Ca concentration was of the order of 100-400 mumol/l wet tissue volume. To measure the exchange of Ca in outer segments from intact photoreceptors, we exposed the dark-adapted retina to Ringer containing the stable isotope 44Ca. Since l.a.m.m.a. can measure separately the concentrations of each of the isotopes of the elements, and since native rods contain almost exclusively 40Ca, the increase in 44Ca and decrease in 40Ca could be used as a measure of Ca influx and efflux. Ca exchange in intact rod outer segments in darkness is very slow. The rate of accumulation of 44Ca was only 10(5) Ca/rod.s, or about 10% of the total outer segment Ca/h. This slow rate of exchange is apparently not the result of restricted movement of Ca across the plasma membrane. Ca exchange was also measured in outer segments which were either partially or entirely detached from the rest of the photoreceptor. In broken-off outer segments, Ca exchange is faster than in the intact organelles, and in 1 h, half of the 44Ca exchanges for 40Ca. When the retina was incubated in Ringer for which all of the Na was substituted with Li or choline, there was an increase in the rate of 44Ca accumulation in intact outer segments, probably due to an inhibition of Na-Ca counter transport across the plasma membrane. Our measurements indicate that the great majority of the Ca in the rod appears to be

  7. Stable Ca, H and O Isotopes in the Modern Death Valley Hydrological System, California

    NASA Astrophysics Data System (ADS)

    Yang, W.; Depaolo, D.; Ingram, L.; Owens, T.

    2006-12-01

    We have characterized waters and sediment from Death Valley to investigate the fractionation of Ca isotopes and how it relates to evaporation effects and precipitation of Ca minerals in a natural system. The ultimate objective is to determine whether there can be substantial Ca isotope fractionation in the absence of significant biological activity, which would determine whether Ca isotopes could be useful as a biomarker on Mars. In this study, we collected water samples from the Death Valley region in May of 2006, and we have also data from a sediment core at Badwater. The δ18O and δ^{}D values of waters vary from -13.9 to +1.6 ‰ and from -109 to -21 ‰ respectively. The spring waters, discharged from the regional groundwater systems and collected at their sources, have low δ18O and δ^{}D values falling on the meteoric water line (MWL). Salt pan brines fall on the upper end of the local evaporation trend (Yang at al., 1997), indicating strong evaporation. The surface spring waters collected from small shallow ponds at the edges of the salt pans show significant variation from the MWL which are the result of evaporation and mixing with the concentrated salt pan brines. The δ44Ca values of the spring waters vary slightly from -0.39 to -0.25 ‰ regardless of their locations and types of water chemistry, which is close to the local bedrock values; whereas the δ44Ca values of the two concentrated Badwater salt pan brine samples are about +0.4 ‰. There is about 0.7 ‰ difference in δ44Ca between the evaporated brine-Ca (chloride-Ca) and the inflow source-Ca, which apparently results from the precipitation of calcium carbonate and sulfate during extreme evaporation. This effect is consistent with the precipitated Ca salts being enriched in the light Ca isotopes as is observed in laboratory precipitation experiments. Calcite and sulfate minerals from the 186-meter Badwater saline sediment core were also measured. The calcite is slightly lower in δ44Ca

  8. Ca Isotopic Ratios in Igneous Rocks: Some Preliminary Results

    NASA Astrophysics Data System (ADS)

    Huang, S.; Farkas, J.; Jacobsen, S. B.

    2009-12-01

    Calcium (Ca) is the 5th most abundant element on the Earth, and it is an important geochemical and cosmochemical tracer. It has six isotopes and only H and He have a larger percentage mass difference (Δm/m) between the heaviest and the lightest isotopes. Systematic Ca isotopic studies have mostly focused on low-temperature geochemical processes, and most Ca isotopic analyses have been applied on modern and ancient marine carbonates and sulphates, documenting large and systematic isotopic variations, which were used to infer the chemical evolution of seawater. Detailed work on igneous rocks is very limited. Here we show two examples of how stable Ca isotopic ratios can be a useful geochemical tool in understanding igneous processes. Ca isotopic fractionation between coexisting clinopyroxene and orthopyroxene from mantle peridotites: We report Ca isotopic ratios on co-existing clino- and ortho-pyroxenes from Kilbourne Hole and San Carlos mantle peridotites. The 44Ca/40Ca in orthopyroxenes is ~0.5 per mil heavier than that in co-existing clinopyroxenes. Combined with published Ca isotopic data on low-temperature Ca-bearing minerals (calcite, aragonite and barite), we show that the fractionation of Ca isotopes between Ca-bearing minerals (at both low-temperature and high-temperature) is primarily controlled by the strength of Ca-O bond in the minerals. The mineral with shorter (i.e., stronger) Ca-O bond yields heavier Ca isotopic ratio. Using our measured 44Ca/40Ca in mantle pyroxenes and the relative proportions of major Ca-bearing minerals in the upper mantle, the estimated 44Ca/40Ca of the upper mantle is 1.1 per mil heavier relative to the NIST 915a, ~0.1 to 0.2 per mil higher than basalts. Ca isotopic variation in Hawaiian shield lavas: Large geochemical and isotopic variations have been observed in lavas forming the large tholeiitic shields of Hawaiian volcanoes, with lavas from the surface of the Koolau volcano (Makapuu-stage) defining one compositional and

  9. Ca Isotope Fractionation During Gypsum Precipitation in a Sulfidic Cave

    NASA Astrophysics Data System (ADS)

    Fantle, M. S.; Macalady, J. L.; Eisenhauer, A.

    2009-12-01

    In sulfidic caves, limestone dissolution above the water table is assocated with sulfuric acid corrosion and attendant precipitation of CaSO4 crusts. Since sulfuric acid is produced by microbially-mediated sulfide oxidation, such systems present unique opportunities to study the effects of microbial processes on Ca isotope systematics. The current study presents preliminary measurements of the Ca isotopic composition of gypsum, calcite, and water samples collected in and around Grotta Bella cave in the Frasassi cave system (central Italy). The environment sampled in this limestone-hosted cave is situated close to flowing sulfidic groundwater (air [H2S]meas ~3 ppm) and is actively forming gypsum in close association with microbial communities ("snottites") dominated by Acidithiobacillus sp [1]. The pH ranges from >2.3 in gypsum crust accumulating on the cave walls to 0-2 at the surface of snottites, while pH in waters sampled outside the cave is between 7 and 8. The current rate of limestone dissolution is ~0.15 mmol CaCO3/cm2/a [2]. This study reports the Ca isotopic composition (δ44Ca, rel. to bulk Earth) of stream and seep water, limestone, and gypsum samples in and around Grotta Bella. Calcium isotopes were measured on a Finnigan Triton TI thermal ionization mass spectrometer at GEOMAR using a 43Ca-48Ca double spike. Field-acidified stream waters and dissolved gypsum were chromatographically purified using MCI Gel (Biorad) while bulk limestone samples were dissolved in nitric acid and loaded onto single Re filaments without additional purification. The δ44Ca values of stream waters and springs are relatively restricted (~0.2‰) and generally the same as bulk limestone. Actively-precipitating CaSO4 minerals, however, show a range of δ44Ca values from limestone-like to values almost 1‰ lighter than corresponding wallrock. Decreasing δ44Ca values in these gypsum minerals correspond to gradients in pH and mineral grain size. The smallest gypsum grains

  10. The State of the Ca Isotope Proxy

    NASA Astrophysics Data System (ADS)

    Fantle, M. S.; Tipper, E.

    2012-12-01

    At the Earth's surface, Ca is a critical element at a variety of scales. It is both a biological nutrient and water-soluble, and is a major constituent of the dominant mineral sink for carbon in the ocean. Additionally, the 5‰ range in the stable isotope ratios of Ca (44Ca/40Ca) suggests that Ca isotopes may be a promising tracer of the Ca cycle, specifically the oceanic budget over time. Despite ~15 years of concentrated effort on high-precision Ca isotope measurements, the utility of Ca isotopes as a proxy remains far from clear. A variety of basic questions have yet to be resolved, both in the marine and terrestrial realms. To provide perspective, the current work presents a data compilation of over 60 published Ca isotope studies. The compilation includes δ44/40CaSRM-915a measurements of the modern Ca cycle, including rivers and groundwater, dust, soils and soil pore fluids, vegetation, rainwater, silicate minerals/rocks, and marine carbonates. The focus of this work is to quantify the leverage of inputs to change the isotopic composition of the ocean. One of the tenets of the weathering proxy is that there is little isotopic leverage to change seawater. If this assumption is valid, then significant variations in the isotopic composition of seawater can be explained to some extent by mass flux imbalances between Ca inputs and outputs, requiring the Ca cycle to be out of steady state for significant periods of time. Despite evidence that Ca fractionates in the modern system during continental cycling, the δ44Ca range of riverine inputs to the ocean is very narrow (especially when compared to the spread in marine carbonates). Thus, there appears to be minimal isotopic leverage amongst inputs to shift the ocean δ44Ca. In order to develop our understanding of the Ca isotope proxy, we identify two probable mechanisms for shifting ocean δ44Ca and evaluate them using a series of simple box models. In the terrestrial realm, plants exhibit a wide range of

  11. Estimating Light Use Efficiency Of A Pine And Beech Forest From Leaf To Ecosystem Scale Using The Photochemical Reflectance Index

    NASA Astrophysics Data System (ADS)

    Vanikiotis, Theofilos; Markos, Nikos; Stagakis, Stavros; Tzotsos, Angelos; Sykioti, Olga; Kyparissis, Aris

    2013-12-01

    The prospect of accurately tracking photosynthetic processes using satellite observations is very important for understanding and monitoring global carbon cycle and climate change. The present study investigates the efficiency of the Photochemical Reflectance Index (PRI) in detecting light use efficiency (ɛ) in different spatial scales. The study sites concern two dense and homogenous forests in the region of Epirus (Greece), one evergreen coniferous forest dominated by Pinus nigra species and one deciduous forest dominated by Fagus sylvatica. Field and laboratory measurements of canopy structure (Leaf Area Index - LAI, needle and shoot structure characteristics), leaf pigment concentrations, leaf photosynthesis and water potential were performed throughout the growth period. These measurements were used for an accurate description of the ecophysiological characteristics of the two species and thus the parameterization of a Canopy Photosynthesis Model in order to estimate canopy photosynthesis. During the same period, leaf and canopy reflectance measurements were performed in the field to test and evaluate PRI regarding it's efficiency to track ɛ in leaf and canopy scale. In order to investigate the potential application of PRI for estimating ɛ in a broader spatial scale, satellite hyperspectral or superspectral sensors can be used. Compact High Resolution Imaging Spectrometer (CHRIS) and Moderate Resolution Imaging Spectroradiometer (MODIS) are currently available for this purpose and their performances were tested within the present study. An agreement between the fluctuations of CHRIS PRI and the field measured canopy PRI has been found, with both of them appearing to track the ɛ fluctuation efficiently. However, MODIS PRI shows no intense fluctuation and no relationship with ɛ and field measured PRI, probably due to lack of atmospheric correction and the effects of viewing and illumination geometry.

  12. Alternate partial root-zone irrigation reduces bundle-sheath cell leakage to CO2 and enhances photosynthetic capacity in maize leaves

    PubMed Central

    Wang, Zhenchang; Kang, Shaozhong; Jensen, Christian R.; Liu, Fulai

    2012-01-01

    The physiological basis for the advantage of alternate partial root-zone irrigation (PRI) over common deficit irrigation (DI) in improving crop water use efficiency (WUE) remains largely elusive. Here leaf gas exchange characteristics and photosynthetic CO2–response and light–response curves for maize (Zea mays L.) leaves exposed to PRI and DI were analysed under three N-fertilization rates, namely 75, 150, and 300 mg N kg−1 soil. Measurements of net photosynthetic rate (An) and stomatal conductance (gs) showed that, across the three N-fertilization rates, the intrinsic WUE was significantly higher in PRI than in DI leaves. Analysis of the CO2–response curve revealed that both carboxylation efficiency (CE) and the CO2-saturated photosynthetic rate (Asat) were significantly higher in PRI than in DI leaves across the three N-fertilization rates; whereas the N-fertilization rates did not influence the shape of the curves. The enhanced CE and Asat in the PRI leaves was accompanied by significant decreases in carbon isotope discrimination (Δ13C) and bundle-sheath cell leakiness to CO2 (Φ). Analysis of the light–response curve indicated that, across the three N-fertilization rates, the quantum yield (α) and light-saturated gross photosynthetic rate (Amax) were identical for the two irrigation treatments; whilst the convexity (κ) of the curve was significantly greater in PRI than in DI leaves, which coincided with the greater CE and Asat derived from the CO2–response curve at a photosynthetic photon flux density of 1500 μmol m−2 s−1. Collectively, the results suggest that, in comparison with the DI treatment, PRI improves photosynthetic capacity parameters CE, Asat, and κ of maize leaves and that contributes to the greater intrinsic WUE in those plants. PMID:22121199

  13. The Association between the PR Interval and Left Ventricular Measurements in the Multiethnic Study of Atherosclerosis

    PubMed Central

    Husby, Michael P.; Soliman, Elsayed Z.; Goldberger, Jeffrey J.; Liu, Kiang; Lloyd-Jones, Don; Durazo-Arvizu, Ramon; Kramer, Holly

    2015-01-01

    Introduction. Few studies have examined the association between the PR interval (PRi) and subclinical cardiovascular disease measures. Methods and Results. The Multiethnic Study of Atherosclerosis (MESA) is a population-based study of 6814 men and women aged 45–84 years without clinical cardiovascular disease and 4962 had complete baseline data on cardiac magnetic resonance imaging measures of LV dimension and ejection fraction and surface electrocardiogram. Linear regression models were constructed to determine the adjusted association between the PRi and measures of LV stroke volume, LV mass, LV end-systolic and end-diastolic volumes, and ejection fraction. Overall, mean age was 61.5 years, and 47.6% were male and race/ethnicity was white in 39.1%, Chinese in 13.1%, African-American in 25.7%, and Hispanic in 22.2%. The PRi ranged from 88 to 308 ms with a median value of 162 ms. As a continuous variable, every standard deviation unit (25 ms) increment in PRi was associated with a 2.00 mL (95% CI 1.52, 2.48) higher stroke volume, a 3.08 g (95% CI 2.30, 3.86) higher LV mass, a 1.36 g/m2 (95% CI 0.96, 1.76) higher LV mass index, and 1.31 mL (95% CI 0.88, 1.73) higher end-systolic and 3.31 mL (95% CI 2.58, 4.03) higher end-diastolic volumes after adjustment for all covariates. No significant association was noted between the PRi and LV ejection fraction. Conclusions. A prolonged PRi is associated with LV measures and may in part explain the link between a prolonged PRi and cardiovascular outcomes. PMID:26558133

  14. Determination of primary combustion source organic carbon-to-elemental carbon (OC / EC) ratio using ambient OC and EC measurements: secondary OC-EC correlation minimization method

    NASA Astrophysics Data System (ADS)

    Wu, Cheng; Zhen Yu, Jian

    2016-05-01

    Elemental carbon (EC) has been widely used as a tracer to track the portion of co-emitted primary organic carbon (OC) and, by extension, to estimate secondary OC (SOC) from ambient observations of EC and OC. Key to this EC tracer method is to determine an appropriate OC / EC ratio that represents primary combustion emission sources (i.e., (OC / EC)pri) at the observation site. The conventional approaches include regressing OC against EC within a fixed percentile of the lowest (OC / EC) ratio data (usually 5-20 %) or relying on a subset of sampling days with low photochemical activity and dominated by local emissions. The drawback of these approaches is rooted in its empirical nature, i.e., a lack of clear quantitative criteria in the selection of data subsets for the (OC / EC)pri determination. We examine here a method that derives (OC / EC)pri through calculating a hypothetical set of (OC / EC)pri and SOC followed by seeking the minimum of the coefficient of correlation (R2) between SOC and EC. The hypothetical (OC / EC)pri that generates the minimum R2(SOC,EC) then represents the actual (OC / EC)pri ratio if variations of EC and SOC are independent and (OC / EC)pri is relatively constant in the study period. This Minimum R Squared (MRS) method has a clear quantitative criterion for the (OC / EC)pri calculation. This work uses numerically simulated data to evaluate the accuracy of SOC estimation by the MRS method and to compare with two commonly used methods: minimum OC / EC (OC / ECmin) and OC / EC percentile (OC / EC10 %). Log-normally distributed EC and OC concentrations with known proportion of SOC are numerically produced through a pseudorandom number generator. Three scenarios are considered, including a single primary source, two independent primary sources, and two correlated primary sources. The MRS method consistently yields the most accurate SOC estimation. Unbiased SOC estimation by OC / ECmin and OC / EC10 % only occurs when the left tail of

  15. Light Use Efficiency and Photochemical Reflectance Index: do we have a common basis defining them? Implications for productivity estimation (Invited)

    NASA Astrophysics Data System (ADS)

    Gitelson, A. A.; Gamon, J. A.

    2013-12-01

    There are at least three commonly used definitions of photosynthetic Light Use Efficiency (LUE) based on: (a) incident radiation (LUEinc); (b) total absorbed light (LUEtotal); and (c) radiation absorbed by photosynthetically active vegetation (LUEps). Consequently, LUE values reported do not have a common basis, bringing confusion and limiting the utility of reported LUE values for comparative analyses. Not surprisingly, the value of LUE reported in literature varies by a factor of three. Similarly, the Photochemical Reflectance Index (PRI) has different operational definitions, resulting in a wide range of reported values for comparable conditions. The objectives of this paper are to investigate (a) temporal behavior of each definition of LUE; and (b) factors affecting PRI, often used as a surrogate of LUE at leaf and canopy levels. We focused on annual and winter-deciduous vegetation where total chlorophyll content is closely tied to the seasonal dynamics of GPP. In these conditions, LUEinc is closely related to total plant chlorophyll (Chl) content. LUEtotal oscillates around a constant value during the vegetative stage, depending mainly on plant physiological status, PAR composition and magnitude, while in reproductive and senescence stages it relates closely to Chl content. LUEps may vary 2- to 3-fold during the growing season with no clear seasonal pattern, and does not seem to be related to any biophysical characteristic studied; rather, it depends on the physiological status of vegetation, PAR composition and magnitude as well as air temperature and soil moisture. At the leaf level, PRI depends greatly on pigment content and composition and relates closely to the ratio of Chl to carotenoid content. At the canopy and stand levels, both total plant Chl content and green LAI are responsible for more than 95% of PRI variation, demonstrating that PRI is confounded by pigment pool sizes and canopy structure in these conditions. Importantly, the close relationship

  16. Risk management in magnetic resonance: failure mode, effects, and criticality analysis.

    PubMed

    Petrillo, Antonella; Fusco, Roberta; Granata, Vincenza; Filice, Salvatore; Raiano, Nicola; Amato, Daniela Maria; Zirpoli, Maria; di Finizio, Alessandro; Sansone, Mario; Russo, Anna; Covelli, Eugenio Maria; Pedicini, Tonino; Triassi, Maria

    2013-01-01

    The aim of the study was to perform a risk management procedure in "Magnetic Resonance Examination" process in order to identify the critical phases and sources of radiological errors and to identify potential improvement projects including procedures, tests, and checks to reduce the error occurrence risk. In this study we used the proactive analysis "Failure Mode Effects Criticality Analysis," a qualitative and quantitative risk management procedure; has calculated Priority Risk Index (PRI) for each activity of the process; have identified, on the PRI basis, the most critical activities and, for them, have defined improvement projects; and have recalculated the PRI after implementation of improvement projects for each activity. Time stop and audits are performed in order to control the new procedures. The results showed that the most critical tasks of "Magnetic Resonance Examination" process were the reception of the patient, the patient schedule drafting, the closing examination, and the organization of activities. Four improvement projects have been defined and executed. PRI evaluation after improvement projects implementation has shown that the risk decreased significantly following the implementation of procedures and controls defined in improvement projects, resulting in a reduction of the PRI between 43% and 100%. PMID:24171173

  17. Tracking diurnal variation in photosynthetic down-regulation using low cost spectroscopic instrumentation.

    PubMed

    van Leeuwen, Martin; Kremens, Robert L; van Aardt, Jan

    2015-01-01

    Photosynthetic light-use efficiency (LUE) has gained wide interest as an input to modeling forest gross primary productivity (GPP). The photochemical reflectance index (PRI) has been identified as a principle means to inform LUE-based models, using airborne and satellite-based observations of canopy reflectance. More recently, low-cost electronics have become available with the potential to provide for dense in situ time-series measurements of PRI. A recent design makes use of interference filters to record light transmission within narrow wavebands. Uncertainty remains as to the dynamic range of these sensors and performance under low light conditions, the placement of the reference band, and methodology for reflectance calibration. This paper presents a low-cost sensor design and is tested in a laboratory set-up, as well in the field. The results demonstrate an excellent performance against a calibration standard (R2 = 0.9999) and at low light conditions. Radiance measurements over vegetation demonstrate a reversible reduction in green reflectance that was, however, seen in both the reference and signal wavebands. Time-series field measurements of PRI in a Douglas-fir canopy showed a weak correlation with eddy-covariance-derived LUE and a significant decline in PRI over the season. Effects of light quality, bidirectional scattering effects, and possible sensor artifacts on PRI are discussed. PMID:25951342

  18. Risk Management in Magnetic Resonance: Failure Mode, Effects, and Criticality Analysis

    PubMed Central

    Granata, Vincenza; Filice, Salvatore; Raiano, Nicola; Amato, Daniela Maria; Zirpoli, Maria; di Finizio, Alessandro; Sansone, Mario; Russo, Anna; Covelli, Eugenio Maria; Pedicini, Tonino; Triassi, Maria

    2013-01-01

    The aim of the study was to perform a risk management procedure in “Magnetic Resonance Examination” process in order to identify the critical phases and sources of radiological errors and to identify potential improvement projects including procedures, tests, and checks to reduce the error occurrence risk. In this study we used the proactive analysis “Failure Mode Effects Criticality Analysis,” a qualitative and quantitative risk management procedure; has calculated Priority Risk Index (PRI) for each activity of the process; have identified, on the PRI basis, the most critical activities and, for them, have defined improvement projects; and have recalculated the PRI after implementation of improvement projects for each activity. Time stop and audits are performed in order to control the new procedures. The results showed that the most critical tasks of “Magnetic Resonance Examination” process were the reception of the patient, the patient schedule drafting, the closing examination, and the organization of activities. Four improvement projects have been defined and executed. PRI evaluation after improvement projects implementation has shown that the risk decreased significantly following the implementation of procedures and controls defined in improvement projects, resulting in a reduction of the PRI between 43% and 100%. PMID:24171173

  19. Remotely-sensed detection of effects of extreme droughts on gross primary production

    PubMed Central

    Vicca, Sara; Balzarolo, Manuela; Filella, Iolanda; Granier, André; Herbst, Mathias; Knohl, Alexander; Longdoz, Bernard; Mund, Martina; Nagy, Zoltan; Pintér, Krisztina; Rambal, Serge; Verbesselt, Jan; Verger, Aleixandre; Zeileis, Achim; Zhang, Chao; Peñuelas, Josep

    2016-01-01

    Severe droughts strongly impact photosynthesis (GPP), and satellite imagery has yet to demonstrate its ability to detect drought effects. Especially changes in vegetation functioning when vegetation state remains unaltered (no browning or defoliation) pose a challenge to satellite-derived indicators. We evaluated the performance of different satellite indicators to detect strong drought effects on GPP in a beech forest in France (Hesse), where vegetation state remained largely unaffected while GPP decreased substantially. We compared the results with three additional sites: a Mediterranean holm oak forest (Puéchabon), a temperate beech forest (Hainich), and a semi-arid grassland (Bugacpuszta). In Hesse, a three-year reduction in GPP following drought was detected only by the Enhanced Vegetation Index (EVI). The Photochemical Reflectance Index (PRI) also detected this drought effect, but only after normalization for absorbed light. In Puéchabon normalized PRI outperformed the other indicators, while the short-term drought effect in Hainich was not detected by any tested indicator. In contrast, most indicators, but not PRI, captured the drought effects in Bugacpuszta. Hence, PRI improved detection of drought effects on GPP in forests and we propose that PRI normalized for absorbed light is considered in future algorithms to estimate GPP from space. PMID:27301671

  20. Tracking Diurnal Variation in Photosynthetic Down-Regulation Using Low Cost Spectroscopic Instrumentation

    PubMed Central

    van Leeuwen, Martin; Kremens, Robert L.; van Aardt, Jan

    2015-01-01

    Photosynthetic light-use efficiency (LUE) has gained wide interest as an input to modeling forest gross primary productivity (GPP). The photochemical reflectance index (PRI) has been identified as a principle means to inform LUE-based models, using airborne and satellite-based observations of canopy reflectance. More recently, low-cost electronics have become available with the potential to provide for dense in situ time-series measurements of PRI. A recent design makes use of interference filters to record light transmission within narrow wavebands. Uncertainty remains as to the dynamic range of these sensors and performance under low light conditions, the placement of the reference band, and methodology for reflectance calibration. This paper presents a low-cost sensor design and is tested in a laboratory set-up, as well in the field. The results demonstrate an excellent performance against a calibration standard (R2 = 0.9999) and at low light conditions. Radiance measurements over vegetation demonstrate a reversible reduction in green reflectance that was, however, seen in both the reference and signal wavebands. Time-series field measurements of PRI in a Douglas-fir canopy showed a weak correlation with eddy-covariance-derived LUE and a significant decline in PRI over the season. Effects of light quality, bidirectional scattering effects, and possible sensor artifacts on PRI are discussed. PMID:25951342

  1. Bronchodilator response following methacholine-induced bronchoconstriction predicts acute asthma exacerbations.

    PubMed

    Park, Heung-Woo; Song, Woo-Jung; Chang, Yoon-Suk; Cho, Sang-Heon; Datta, Soma; Weiss, Scott T; Tantisira, Kelan G

    2016-07-01

    Methacholine bronchial provocation test provides the concentration of methacholine causing a 20% decrease in forced expiratory volume in 1 s (FEV1) from baseline (PC20). The dose-response slope (DRS), and other continuous indices of responsiveness (CIR; the percentage decline from the post-diluent baseline FEV1 after the last dose of methacholine), and per cent recovery index (PRI; the percentage increase from the maximally reduced FEV1 after bronchodilator inhalation) are alternative measures. The clinical relevance of these indices in predicting acute asthma exacerbations has not been fully evaluated.In two prospective cohorts of childhood and elderly asthmatics, baseline PC20, DRS, CIR and PRI were measured and evaluated as predictors of acute asthma exacerbations.We found that PRI was significantly related to the presence of asthma exacerbations during the first year of follow-up in both cohorts of childhood (p=0.025) and elderly asthmatics (p=0.003). In addition, PRI showed a significant association with the total number of steroid bursts during 4.3 years of follow-up in the cohort of childhood asthmatics (p=0.04).We demonstrated that PRI, an index of reversibility following methacholine-induced bronchoconstriction, was a good clinical predictor of acute exacerbations of asthma in both childhood and elderly asthmatics. PMID:27076579

  2. The photochemical reflectance index provides an optical indicator of spring photosynthetic activation in evergreen conifers.

    PubMed

    Wong, Christopher Y S; Gamon, John A

    2015-04-01

    In evergreens, the seasonal down-regulation and reactivation of photosynthesis is largely invisible and difficult to assess with remote sensing. This invisible phenology may be changing as a result of climate change. To better understand the mechanism and timing of these hidden physiological transitions, we explored several assays and optical indicators of spring photosynthetic activation in conifers exposed to a boreal climate. The photochemical reflectance index (PRI), chlorophyll fluorescence, and leaf pigments for evergreen conifer seedlings were monitored over 1 yr of a boreal climate with the addition of gas exchange during the spring. PRI, electron transport rate, pigment levels, light-use efficiency and photosynthesis all exhibited striking seasonal changes, with varying kinetics and strengths of correlation, which were used to evaluate the mechanisms and timing of spring activation. PRI and pigment pools were closely timed with photosynthetic reactivation measured by gas exchange. The PRI provided a clear optical indicator of spring photosynthetic activation that was detectable at leaf and stand scales in conifers. We propose that PRI might provide a useful metric of effective growing season length amenable to remote sensing and could improve remote-sensing-driven models of carbon uptake in evergreen ecosystems. PMID:25641209

  3. Remotely-sensed detection of effects of extreme droughts on gross primary production.

    PubMed

    Vicca, Sara; Balzarolo, Manuela; Filella, Iolanda; Granier, André; Herbst, Mathias; Knohl, Alexander; Longdoz, Bernard; Mund, Martina; Nagy, Zoltan; Pintér, Krisztina; Rambal, Serge; Verbesselt, Jan; Verger, Aleixandre; Zeileis, Achim; Zhang, Chao; Peñuelas, Josep

    2016-01-01

    Severe droughts strongly impact photosynthesis (GPP), and satellite imagery has yet to demonstrate its ability to detect drought effects. Especially changes in vegetation functioning when vegetation state remains unaltered (no browning or defoliation) pose a challenge to satellite-derived indicators. We evaluated the performance of different satellite indicators to detect strong drought effects on GPP in a beech forest in France (Hesse), where vegetation state remained largely unaffected while GPP decreased substantially. We compared the results with three additional sites: a Mediterranean holm oak forest (Puéchabon), a temperate beech forest (Hainich), and a semi-arid grassland (Bugacpuszta). In Hesse, a three-year reduction in GPP following drought was detected only by the Enhanced Vegetation Index (EVI). The Photochemical Reflectance Index (PRI) also detected this drought effect, but only after normalization for absorbed light. In Puéchabon normalized PRI outperformed the other indicators, while the short-term drought effect in Hainich was not detected by any tested indicator. In contrast, most indicators, but not PRI, captured the drought effects in Bugacpuszta. Hence, PRI improved detection of drought effects on GPP in forests and we propose that PRI normalized for absorbed light is considered in future algorithms to estimate GPP from space. PMID:27301671

  4. Remotely-sensed detection of effects of extreme droughts on gross primary production

    NASA Astrophysics Data System (ADS)

    Vicca, Sara; Balzarolo, Manuela; Filella, Iolanda; Granier, André; Herbst, Mathias; Knohl, Alexander; Longdoz, Bernard; Mund, Martina; Nagy, Zoltan; Pintér, Krisztina; Rambal, Serge; Verbesselt, Jan; Verger, Aleixandre; Zeileis, Achim; Zhang, Chao; Peñuelas, Josep

    2016-06-01

    Severe droughts strongly impact photosynthesis (GPP), and satellite imagery has yet to demonstrate its ability to detect drought effects. Especially changes in vegetation functioning when vegetation state remains unaltered (no browning or defoliation) pose a challenge to satellite-derived indicators. We evaluated the performance of different satellite indicators to detect strong drought effects on GPP in a beech forest in France (Hesse), where vegetation state remained largely unaffected while GPP decreased substantially. We compared the results with three additional sites: a Mediterranean holm oak forest (Puéchabon), a temperate beech forest (Hainich), and a semi-arid grassland (Bugacpuszta). In Hesse, a three-year reduction in GPP following drought was detected only by the Enhanced Vegetation Index (EVI). The Photochemical Reflectance Index (PRI) also detected this drought effect, but only after normalization for absorbed light. In Puéchabon normalized PRI outperformed the other indicators, while the short-term drought effect in Hainich was not detected by any tested indicator. In contrast, most indicators, but not PRI, captured the drought effects in Bugacpuszta. Hence, PRI improved detection of drought effects on GPP in forests and we propose that PRI normalized for absorbed light is considered in future algorithms to estimate GPP from space.

  5. Structural insight into HIV-1 capsid recognition by rhesus TRIM5α

    PubMed Central

    Yang, Haitao; Ji, Xiaoyun; Zhao, Gongpu; Ning, Jiying; Zhao, Qi; Aiken, Christopher; Gronenborn, Angela M.; Zhang, Peijun; Xiong, Yong

    2012-01-01

    Tripartite motif protein isoform 5 alpha (TRIM5α) is a potent antiviral protein that restricts infection by HIV-1 and other retroviruses. TRIM5α recognizes the lattice of the retrovirus capsid through its B30.2 (PRY/SPRY) domain in a species-specific manner. Upon binding, TRIM5α induces premature disassembly of the viral capsid and activates the downstream innate immune response. We have determined the crystal structure of the rhesus TRIM5α PRY/SPRY domain that reveals essential features for capsid binding. Combined cryo-electron microscopy and biochemical data show that the monomeric rhesus TRIM5α PRY/SPRY, but not the human TRIM5α PRY/SPRY, can bind to HIV-1 capsid protein assemblies without causing disruption of the capsid. This suggests that the PRY/SPRY domain alone constitutes an important pattern-sensing component of TRIM5α that is capable of interacting with viral capsids of different curvatures. Our results provide molecular insights into the mechanisms of TRIM5α-mediated retroviral restriction. PMID:23091002

  6. Remote sensing of assimilating branch light use efficiency using the photochemical reflectance index in Haloxylon ammodendron forest

    NASA Astrophysics Data System (ADS)

    Nyongesah, Maina John; Quan, Wang; Lu, Xu

    2016-04-01

    Five healthy Haloxylon ammodendron trees were randomly selected to monitor the photochemical reflectance index (PRI) and its relation to light use efficiency (LUE) in shaded and sunlit assimilating branches. Linear regression was performed where the results revealed that LUE decreased with seasonal courses with vivid midday depression regardless of light variation within canopies. PRI and LUE decoupled in early spring when the foliage was deeply downregulated, with high correlation (R2=0.8, p<0.001) during most parts of the year. Measured and estimated LUE were highly correlated for the July to September dataset (R2=0.73, p<0.001) compared to May to June datasets (R2=0.35, p<0.001). The estimated LUE for young assimilating branches could be obtained with a high RMSE of 0.01, compared to mature branches with an RMSE of 0.003. The measured LUE values were ˜20% higher than estimated LUE during the period from May to June, and values were slightly lower at the end of the growing season. This was attributed to differences in the physiological and biochemical mechanisms controlling the seasonal dynamics of PRI. Therefore, PRI is the best estimator of LUE when age-related changes and canopy light partitioning are considered in assimilating organs. Combined use of PRI with pigments could improve the remote evaluation of LUE.

  7. Progress of Covariance Evaluation at the China Nuclear Data Center

    SciTech Connect

    Xu, R.; Zhang, Q.; Zhang, Y.; Liu, T.; Ge, Z.; Lu, H.; Sun, Z.; Yu, B.; Tang, G.

    2015-01-15

    Covariance evaluations at the China Nuclear Data Center focus on the cross sections of structural materials and actinides in the fast neutron energy range. In addition to the well-known Least-squares approach, a method based on the analysis of the sources of experimental uncertainties is especially introduced to generate a covariance matrix for a particular reaction for which multiple measurements are available. The scheme of the covariance evaluation flow is presented, and an example of n+{sup 90}Zr is given to illuminate the whole procedure. It is proven that the accuracy of measurements can be properly incorporated into the covariance and the long-standing small uncertainty problem can be avoided.

  8. The γ-ray spectrometer HORUS and its applications for nuclear astrophysics

    NASA Astrophysics Data System (ADS)

    Netterdon, L.; Derya, V.; Endres, J.; Fransen, C.; Hennig, A.; Mayer, J.; Müller-Gatermann, C.; Sauerwein, A.; Scholz, P.; Spieker, M.; Zilges, A.

    2014-08-01

    A dedicated setup for the in-beam measurement of absolute cross-sections of astrophysically relevant charged-particle induced reactions is presented. These, usually very low, cross-sections at energies of astrophysical interest are important to improve the modeling of the nucleosynthesis processes of heavy nuclei. Particular emphasis is put on the production of the p nuclei during the astrophysical γ process. The recently developed setup utilizes the high-efficiency γ-ray spectrometer HORUS, which is located at the 10 MV FN tandem ion accelerator of the Institute for Nuclear Physics in Cologne. The design of this setup will be presented and results of the recently measured 89Y(p,γ)90Zr reaction will be discussed. The excellent agreement with existing data shows that the HORUS spectrometer is a powerful tool to determine total and partial cross-sections using the in-beam method with high-purity germanium detectors.

  9. Progress in applyiong the FKK multistep reaction theory to intermediate-energy data evaluation

    SciTech Connect

    Chadwick, M.B.; Young, P.G.

    1994-07-01

    Recent developments to the physics modeling in the FKK-GNASH code system are reviewed. We describe modifications to include a linking of multistep direct and multistep compound processes, which are important when the incident energy is less than about 30 MeV. A model for multiple preequilibrium emission is given, and compared with experimental measurements of proton reactions on {sup 90}Zr at 160 MeV. We also give some preliminary observations concerning FKK calculations which use both normal and non-normal DWBA matrix elements. We describe the application of the FKK-GNASH code to a range of nuclear data applications, including intermediate energy reactions of importance in the accelerator transmutation of waste, and fast neutron and proton cancer radiation treatment. We outline areas where further work is needed for the accurate modeling of nuclear reactions using the FKK theory.

  10. Collective aspects of /sup 91/Zr by (d,d/sup prime/) scattering at 17 MeV

    SciTech Connect

    Horodynski-Matsushigue, L.B.; Borello-Lewin, T.; Dietzsch, O.

    1986-05-01

    The /sup 91/Zr(d,d')/sup 91/Zr( reaction has been investigated at 17 MeV incident energy. Up to 4.8 MeV excitation, 73 levels, some of them new, were identified. Angular distributions associated to approx.40 levels were attributed to pure L = 2, 3, or 5 excitations, concentrated in energy regions where the /sup 90/Zr core exhibits 2/sup +/, 3/sup -/, and 5/sup -/ states. The partial deformation parameters ..beta../sub L//sup prime/ obtained show agreement with those from low energy proton scattering for L = 2, but there is a systematic difference for L = 3 and L = 5, which is discussed. Attention is drawn to the high excitation probability of the first excited state of /sup 91/Zr, as measured by the ..beta../sub 2/approx. =0.18 value obtained, a factor of approx.2 above all other values for nuclei with A = 90 +- 2.

  11. Improved Properties of Pb Based BLZT Ferroelectric Ceramics

    SciTech Connect

    Kumar, Parveen; Singh, Sangeeta; Juneja, J. K.; Raina, K. K.; Prakash, Chandra

    2011-11-22

    Present report is concerning with investigation of effect of different sintering profiles on Pb based BLZT ceramics. The material powder of selected composition (Ba{sub 0.795}La{sub 0.005}Pb{sub 0.20}Ti{sub 0.90}Zr{sub 0.10}O{sub 3}) was prepared by solid state reaction route and then powder was compacted in the form of circular discs. The discs were then sintered at different temperatures (1325 deg. C for 4h, 1325 deg. C for 15min+1200 deg. C for 4h). Improved dielectric and ferroelectric properties were observed for samples sintered at 1200 deg. C. Shifting in T{sub c} to higher temperature could be related to enhanced tetragonality, which was further confirmed by X-ray diffraction analysis. All these improvements evidences that there is less Pb loss in case of modified sintering profile.

  12. Development of Enhanced, Permanently-Installed, Neutron Activation Diagnostic Hardware for NIF

    NASA Astrophysics Data System (ADS)

    Edwards, E. R.; Jedlovec, D. R.; Carrera, J. A.; Yeamans, C. B.

    2016-05-01

    Neutron activation diagnostics are baseline neutron yield and flux measurement instruments at the National Ignition Facility. Up to 19 activation samples are distributed around the target chamber. Currently the samples must be removed to be counted, creating a 1-2 week data turn-around time and considerable labor costs. An improved system consisting of a commercially available LaBr3(Ce) scintillator and Power over Ethernet electronics is under development. A machined zirconium-702 cap over the detector is the activation medium to measure the 90Zr(n,2n)89Zr reaction. The detectors are located at the current neutron activation diagnostic sites and monitored remotely. Because they collect data in real time yield values are returned within a few hours after a NIF shot.

  13. Structure above the t1 / 2 = 6.85-h, 21/2+ isomer in 93Mo

    NASA Astrophysics Data System (ADS)

    Chiara, C. J.; Carroll, J. J.; Lane, G. J.; Hota, S. S.; Mitchell, A. J.; Palalani, N.; Reed, M. W.

    2016-03-01

    Excited states in 93Mo were populated in the 90Zr(7Li, p 3 n) reaction at the Heavy-Ion Accelerator Facility of the Australian National University. The CAESAR array of nine coaxial HPGe detectors and two low-energy photon spectrometers (LEPSs) was used to detect the emitted gamma rays. Relative yields for population of the 21/2+, 93mMo state and neighboring reaction channels were determined from gamma-singles data for beam energies of 5 to 8 MeV/ A. The level structure above the isomer has been expanded through gamma-gamma coincidence measurements. These results will be compared with high-spin structure of neighboring nuclei and with shell-model calculations. Supported in part by the U.S. Army Research Laboratory under Cooperative Agreement W911NF-12-2-0019.

  14. {gamma}-ray spectroscopy of the neutron-rich nuclei {sup 89}Rb, {sup 92}Y, and {sup 93}Y with multinucleon transfer reactions

    SciTech Connect

    Bucurescu, D.; Ionescu-Bujor, M.; Iordachescu, A.; Mihai, C.; Suliman, G.; Rusu, C.; Marginean, N.; Ur, C. A.; Marginean, R.; De Angelis, G.; Corradi, L.; Vedova, F. Della; Fioretto, E.; Gadea, A.; Guiot, B.; Napoli, D.; Stefanini, A. M.; Valiente-Dobon, J. J.; Bazzacco, D.; Beghini, S.

    2007-12-15

    The positive-parity yrast states in the {sup 89}Rb, {sup 92}Y, and {sup 93}Y nuclei were studied using {gamma}-ray spectroscopy with heavy-ion induced reactions. In the multinucleon transfer reactions {sup 208}Pb+{sup 90}Zr (590 MeV) and {sup 238}U+{sup 82}Se (505 MeV), several {gamma}-ray transitions were identified in these nuclei by means of coincidences between recoiling ions identified with the PRISMA spectrometer and {gamma} rays detected with the CLARA {gamma}-ray array in thin target experiments. Level schemes were subsequently determined from triple-{gamma} coincidences recorded with the GASP array in a thick target experiment, in the reactions produced by a 470 MeV {sup 82}Se beam with a {sup 192}Os target. The observed level schemes are compared to shell-model calculations.

  15. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    SciTech Connect

    Kuzyakin, R. A. Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-15

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the {sup 16}O + {sup 112}Cd, {sup 152}Sm, and {sup 184}W; {sup 19}F +{sup 175}Lu; {sup 28}Si +{sup 94,100}Mo and {sup 154}Sm; {sup 40}Ca +{sup 96}Zr; {sup 48}Ca+ {sup 90}Zr; and {sup 64}Ni +{sup 58,64}Ni, {sup 92,96}Zr, and {sup 100}Mo reactions are in good agreement with available experimental data.

  16. Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrier

    NASA Astrophysics Data System (ADS)

    Kuzyakin, R. A.; Sargsyan, V. V.; Adamian, G. G.; Antonenko, N. V.

    2013-06-01

    Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the 16O + 112Cd, 152Sm, and 184W; 19F +175Lu; 28Si +94,100Mo and 154Sm; 40Ca +96Zr; 48Ca+ 90Zr; and 64Ni +58,64Ni, 92,96Zr, and 100Mo reactions are in good agreement with available experimental data.

  17. Role of momentum transfer in the quenching of the Gamow-Teller strength

    SciTech Connect

    Marketin, T.; Martinez-Pinedo, G.; Paar, N.; Vretenar, D.

    2012-10-20

    A recent analysis of (p,n) and (n,p) reaction data from {sup 90}Zr was performed recently, where a significant amount of Gamow-Teller strength was found above the resonance, an energy region previously unreachable by experimental setups. The extracted strengths in the {beta}{sub -} and the {beta}{sub +} channel indicate that approximately 10% of the total strength necessary to satisfy the model independent Ikeda sum rule is missing. One possible source of this discrepancy is the treatment of the isovector spin monopole (IVSM) mode of excitation which has been found to occurr at high excitation energies. Employing the relativistic Hartree-Bogoliubov (RHB) model and the protonneutron relativistic quasiparticle random phase approximation (pn-RQRPA) to calculate the nuclear response, we explore the contribution of the IVSM mode to the total L= 0 strength and apply our results to the available data.

  18. Are there nuclear structure effects on the isoscalar giant monopole resonance near A = 90?

    NASA Astrophysics Data System (ADS)

    Gupta, Yogesh; Garg, Umesh; Howard, K.; Senyigit, M.; Itoh, M.; Ando, S.; Uchiyama, A.; Aoki, T.; Iwamoto, C.; Adachi, S.; Tamii, A.; Fujiwara, M.; Kadono, C.; Akimune, H.; Matsuda, Y.; Nakahara, T.; Kawabata, T.; Tsumura, M.; Furuno, T.; Harakeh, M.; Kalantar-Nayestanaki, N.

    2015-10-01

    The excitation energy of the isoscalar giant monopole resonance (ISGMR) exhibits, in general, a very smooth behavior (Ex ~A 1 / 3) over the periodic Table. In recent work the Texas A&M group has reported that ISGMR energies for 92Zr and 92Mo are appreciably higher than that for 90Zr, suggesting significant nuclear structure effects on ISGMR and, hence, on the nuclear compressibility. We have measured inelastic scattering of 385-MeV a particles on 90,92Zr, 92Mo at extremely forward angles, including 0°, using the ``Grand Raiden'' spectrometer at RCNP, Japan. Results of detailed multipole decomposition analyses to extract the ISGMR strength distributions in the three nuclei will be presented. Supported in part by the National Science Foundation (Grant No. PHY1419765).

  19. New type of asymmetric fission in proton-rich nuclei.

    PubMed

    Andreyev, A N; Elseviers, J; Huyse, M; Van Duppen, P; Antalic, S; Barzakh, A; Bree, N; Cocolios, T E; Comas, V F; Diriken, J; Fedorov, D; Fedosseev, V; Franchoo, S; Heredia, J A; Ivanov, O; Köster, U; Marsh, B A; Nishio, K; Page, R D; Patronis, N; Seliverstov, M; Tsekhanovich, I; Van den Bergh, P; Van De Walle, J; Venhart, M; Vermote, S; Veselsky, M; Wagemans, C; Ichikawa, T; Iwamoto, A; Möller, P; Sierk, A J

    2010-12-17

    A very exotic process of β-delayed fission of 180Tl is studied in detail by using resonant laser ionization with subsequent mass separation at ISOLDE (CERN). In contrast to common expectations, the fission-fragment mass distribution of the post-β-decay daughter nucleus 180Hg (N/Z=1.25) is asymmetric. This asymmetry is more surprising since a mass-symmetric split of this extremely neutron-deficient nucleus would lead to two 90Zr fragments, with magic N=50 and semimagic Z=40. This is a new type of asymmetric fission, not caused by large shell effects related to fragment magic proton and neutron numbers, as observed in the actinide region. The newly measured branching ratio for β-delayed fission of 180Tl is 3.6(7) × 10(-3)%, approximately 2 orders of magnitude larger than in an earlier study. PMID:21231583

  20. Cross sections for (n, 2n), (n, p) and (n, ) reactions on osmium isotopes in the neutron energy range of 13.5-14.8 MeV.

    PubMed

    Zhao, Liangyong; Yuan, Jilong; Tuo, Fei; Zhang, Yanbin; Kong, Xiangzhong; Liu, Rong; Jiang, Li

    2008-10-01

    Cross sections for (n, 2n), (n, p) and (n, alpha) reactions on the osmium isotopes were measured in the neutron energies 13.5-14.8 MeV by the activation technique with the monitor reaction (93)Nb(n, 2n)(92 m)Nb. Our measurements were carried out by gamma-detection using a coaxial high-purity germanium (HPGe) detector. Natural high-purity osmium powder (99.9%) was fabricated as the samples. The neutron energies were determined by the cross-section ratios for (93)Nb(n, 2n)(92 m)Nb and (90)Zr(n, 2n)(89 m+g)Zr reactions. The fast neutrons were produced by the T(d, n)(4)He reaction. The results obtained were compared with previous data. PMID:18468910

  1. Relative isotopic abundances of zirconium in R Cygni and V CANCRI

    NASA Astrophysics Data System (ADS)

    Zook, A. C.

    1985-02-01

    The relative abundances of the isotopes of Zr in the S stars R Cyg and V Cnc are calculated by determining isotopic splitting at the head of the 1Pi - 1Sigma (0, 1) band of ZrO in spectra obtained at resolution 30 pm on hypersensitized 127-O4 plates with a Varo tube on the 51-cm camera at the Coude focus of the 3-m telescope at Lick Observatory. The data reduction techniques and the fit to the model synthetic spectra of Kurucz (1970) are described, and the ratio (Zr-90):(Zr-91):(Zr-92):(Zr-93):(Zr-94):(Zr-96) is given as 47:10:17:6:20:00 percent. The presence of the long-lived unstable isotope Zr-93 is interpreted as evidence for recent nucleosynthesis, and the abundances found are shown to be consistent with s-process nucleosynthesis.

  2. Technological developments for strontium-90 determination using AMS

    NASA Astrophysics Data System (ADS)

    Satou, Yukihiko; Sueki, Keisuke; Sasa, Kimikazu; Matsunaka, Tetsuya; Takahashi, Tsutomu; Shibayama, Nao; Izumi, Daiki; Kinoshita, Norikazu; Matsuzaki, Hiroyuki

    2015-10-01

    Accelerator mass spectrometry (AMS) is one of method used for 90Sr determination. It would enable rapid 90Sr measurements from environmental samples such as water, soil, and milk. However, routine analysis of 90Sr using AMS has not yet been achieved because of difficulties associated with isobaric separation and production of intense negative ion beams characterized by currents from hundreds of nanoamperes to several microamperes. We have developed a rapid procedure for preparing samples with optimum compositions for use with AMS, which enables production of intense Sr beam currents from an ion source. Samples of SrF2 were prepared from a standard Sr solution and agricultural soil. The time required to prepare a SrF2 sample from a soil sample was 10 h. Negative 88SrF3- ions were successfully extracted at 500 nA from mixed samples of SrF2 and PbF2. In the present work, negative ions of 90Zr, included as an impurity, were accelerated with a tandem accelerator operated at a terminal voltage of 5 MV. Ions characterized by a charge state of 6+ were channeled into a gas counter. An atomic ratio of 90Zr/88Sr of 3 × 10-8 was estimated for the soil sample. No signal was detected from the assay of PbF2, which was pressed in an aluminum cathode, for a mass number of 90. PbF2 revealed good performance in the production of negative SrF3- molecular ion beams and detection of 90Sr with a gas counter.

  3. Nucleosynthesis in Electron Capture Supernovae of Asymptotic Giant Branch Stars

    NASA Astrophysics Data System (ADS)

    Wanajo, S.; Nomoto, K.; Janka, H.-T.; Kitaura, F. S.; Müller, B.

    2009-04-01

    We examine nucleosynthesis in the electron capture supernovae of progenitor asymptotic giant branch stars with an O-Ne-Mg core (with the initial stellar mass of 8.8 M sun). Thermodynamic trajectories for the first 810 ms after core bounce are taken from a recent state-of-the-art hydrodynamic simulation. The presented nucleosynthesis results are characterized by a number of distinct features that are not shared with those of other supernovae from the collapse of stars with iron core (with initial stellar masses of more than 10 M sun). First is the small amount of 56Ni (0.002-0.004 M sun) in the ejecta, which can be an explanation for the observed properties of faint supernovae such as SNe 2008S and 1997D. In addition, the large Ni/Fe ratio is in reasonable agreement with the spectroscopic result of the Crab nebula (the relic of SN 1054). Second is the large production of 64Zn, 70Ge, light p-nuclei (74Se, 78Kr, 84Sr, and 92Mo), and in particular, 90Zr, which originates from the low Ye (0.46-0.49, the number of electrons per nucleon) ejecta. We find, however, that only a 1%-2% increase of the minimum Ye moderates the overproduction of 90Zr. In contrast, the production of 64Zn is fairly robust against a small variation of Ye . This provides the upper limit of the occurrence of this type of events to be about 30% of all core-collapse supernovae.

  4. High-lying excited states in Gamow Teller strength and their roles in neutrino reactions

    NASA Astrophysics Data System (ADS)

    Cheoun, Myung-Ki; Ha, Eunja; Kajino, Toshitaka

    2012-10-01

    The Gamow Teller (GT) transition strengths deduced from charge exchange reactions (CEXRs) are very helpful for understanding the nuclear reaction induced by neutrinos, in particular, by the solar neutrino. For further study of supernovae (SNe) neutrinos in the cosmos, one needs to study high-lying GT states around a few tens of MeV region as well as other multipole transitions because of the high energy tail in the neutrino spectra emitted from the neutrino sphere. In this report, we address the importance of the high-lying GT excited states, whose data now become available from various CEXR experiments. For example, GT(± strengths up to 70MeV are successfully extracted by 90Zr( n, p) and 90Zr( p, n) reactions. Our discussions are extended to investigate roles of the high-lying states beyond a few low-lying states known in the old experiment on the reaction induced by SNe neutrinos particularly on 40Ar target. The nucleus was originally exploited to identify the solar neutrino emitted from 8B produced in the pp-chains on the Sun, and now lots of applications for more energetic neutrino detection are under progress. The expected large difference between the cross-sections of νe^{} and bar{{ν}}e^{} reactions on 40Ar , whose differences were anticipated because of the large Q-value in the bar{{ν}}e^{} reaction, is significantly diminished compared to previous results. Our calculations are carried out by the Quasi-particle Random Phase Approximation (QRPA), which takes the neutron-proton pairing into account to the standard proton-neutron QRPA (pnQRPA) where only proton-proton and neutron-neutron pairing correlations are considered.

  5. The viability of the Parenting Representations Interview for assessing and measuring change in parents of adolescents.

    PubMed

    Scharf, Miri; Mayseless, Ofra; Kivenson-Baron, Inbal

    2015-01-01

    Parents' representations include parents' views of their adolescent, of their own parenting and of the parent-adolescent relationship. Two longitudinal studies of parents and their adolescent sons and daughters support the validity of scales coding mothers in the Parenting Representations Interview-Adolescence (PRI-A). The studies, conducted in Israel during the transition from home to military service, demonstrated that three dimensions derived from the PRI-A: positive representations of adolescents, negative emotionality and inadequate boundaries were associated with adolescents' AAI variables, relatedness-autonomy behaviors with mothers, and with other indicators, such as adolescents' wellbeing, romantic intimacy and individuation. Examining parenting representations could help practitioners pinpoint targets for intervention and evaluate the changes that families go through during psychotherapy, as well as the therapeutic process and its outcomes. The findings support the viability of the PRI for use in attachment based interventions for adolescents. PMID:25703357

  6. Impulsive sounds change European seabass swimming patterns: Influence of pulse repetition interval.

    PubMed

    Neo, Y Y; Ufkes, E; Kastelein, R A; Winter, H V; Ten Cate, C; Slabbekoorn, H

    2015-08-15

    Seismic shootings and offshore pile-driving are regularly performed, emitting significant amounts of noise that may negatively affect fish behaviour. The pulse repetition interval (PRI) of these impulsive sounds may vary considerably and influence the behavioural impact and recovery. Here, we tested the effect of four PRIs (0.5-4.0s) on European seabass swimming patterns in an outdoor basin. At the onset of the sound exposures, the fish swam faster and dived deeper in tighter shoals. PRI affected the immediate and delayed behavioural changes but not the recovery time. Our study highlights that (1) the behavioural changes of captive European seabass were consistent with previous indoor and outdoor studies; (2) PRI could influence behavioural impact differentially, which may have management implications; (3) some acoustic metrics, e.g. SELcum, may have limited predictive power to assess the strength of behavioural impacts of noise. Noise impact assessments need to consider the contribution of sound temporal structure. PMID:26088542

  7. Primary MicroRNA Processing Assay Reconstituted Using Recombinant Drosha and DGCR8

    PubMed Central

    Barr, Ian; Guo, Feng

    2016-01-01

    In animals, the Microprocessor complex cleaves primary transcripts of microRNAs (pri-miRNAs) to produce precursor microRNAs in the nucleus. The core components of Microprocessor include the Drosha ribonuclease and its RNA-binding partner protein DiGeorge critical region 8 (DGCR8). DGCR8 has been shown to tightly bind an Fe(III) heme cofactor, which activates its pri-miRNA processing activity. Here we describe how to reconstitute pri-miRNA processing using recombinant human Drosha and DGCR8 proteins. In particular, we present the procedures for expressing and purifying DGCR8 as an Fe(III) heme-bound dimer, the most active form of this protein, and for estimating its heme content. PMID:24166303

  8. A Short Open Reading Frame Encompassing the MicroRNA173 Target Site Plays a Role in trans-Acting Small Interfering RNA Biogenesis.

    PubMed

    Yoshikawa, Manabu; Iki, Taichiro; Numa, Hisataka; Miyashita, Kyoko; Meshi, Tetsuo; Ishikawa, Masayuki

    2016-05-01

    trans-Acting small interfering RNAs (tasiRNAs) participate in the regulation of organ morphogenesis and determination of developmental timing in plants by down-regulating target genes through mRNA cleavage. The production of tasiRNAs is triggered by microRNA173 (miR173) and other specific microRNA-mediated cleavage of 5'-capped and 3'-polyadenylated primary TAS transcripts (pri-TASs). Although pri-TASs are not thought to encode functional proteins, they contain multiple short open reading frames (ORFs). For example, the primary TAS2 transcript (pri-TAS2) contains 11 short ORFs, and the third ORF from the 5' terminus (ORF3) encompasses the miR173 target site. Here, we show that nonsense mutations in ORF3 of pri-TAS2 upstream of the miR173 recognition site suppress tasiRNA accumulation and that ORF3 is translated in vitro. Glycerol gradient centrifugation analysis of Arabidopsis (Arabidopsis thaliana) plant extracts revealed that pri-TAS2 and its miR173-cleaved 5' and 3' fragments are fractionated together in the polysome fractions. These and previous results suggest that the 3' fragment of pri-TAS2, which is a source of tasiRNAs, forms a huge complex containing SGS3, miR173-programmed AGO1 RNA-induced silencing complex, the 5' fragment, and ribosomes. This complex overaccumulated, moderately accumulated, and did not accumulate in rdr6, sde5, and sgs3 mutants, respectively. The sgs3 sde5 and rdr6 sde5 double mutants showed phenotypes similar to those of sgs3 and sde5 single mutants, respectively, with regard to the TAS2-related RNA accumulation, suggesting that the complex is formed in an SGS3-dependent manner, somehow modified and stabilized by SDE5, and becomes competent for RDR6 action. Ribosomes in this complex likely play an important role in this process. PMID:26966170

  9. Comparative effects of deficit irrigation and alternate partial root-zone irrigation on xylem pH, ABA and ionic concentrations in tomatoes

    PubMed Central

    Wang, Yaosheng; Liu, Fulai; Jensen, Christian Richardt

    2012-01-01

    Comparative effects of partial root-zone irrigation (PRI) and deficit irrigation (DI) on xylem pH, ABA, and ionic concentrations of tomato (Lycopersicon esculentum L.) plants were investigated in two split-root pot experiments. Results showed that PRI plants had similar or significantly higher xylem pH, which was increased by 0.2 units relative to DI plants. Nitrate and total ionic concentrations (cations+anions), and the proportion of cations influenced xylem pH such that xylem pH increases as nitrate and total ionic concentrations decrease, and the proportion of cations increases. In most cases, the xylem ABA concentration was similar for PRI and DI plants, and a clear association between increases in xylem pH with increasing xylem ABA concentration was only found when the soil water content was relatively low. The concentrations of anions, cations, and the sum of anions and cations in PRI were higher than in the DI treatment when soil water content was relatively high in the wetted soil compartment. However, when water content in both soil compartments of the PRI pots were very low before the next irrigation, the acquisition of nutrients by roots was reduced, resulting in lower concentrations of anions and cations in the PRI than in the DI treatment. It is therefore essential that the soil water content in the wet zone should be maintained relatively high while that in the drying soil zone should not be very low, both conditions are crucial to maintain high soil and plant water status while sustaining ABA signalling of the plants. PMID:22162869

  10. miR-34a expression, epigenetic regulation, and function in human placental diseases

    PubMed Central

    Doridot, Ludivine; Houry, Dorothée; Gaillard, Harald; Chelbi, Sonia T; Barbaux, Sandrine; Vaiman, Daniel

    2014-01-01

    Preeclampsia (PE) is the major pregnancy-induced hypertensive disorder responsible for maternal and fetal morbidity and mortality that can be associated with intrauterine growth restriction (IUGR). PE and IUGR are thought to be due to a placental defect, occurring early during pregnancy. Several placental microRNAs (miRNAs) have been shown to be deregulated in the context of placental diseases and could thus play a role in the pathophysiology of PE. Here, we show that pri-miR-34a is overexpressed in preeclamptic placentas and that its placental expression is much higher during the first trimester of pregnancy than at term, suggesting a possible developmental role. We explored pri-miR-34a regulation and showed that P53, a known activator of miR-34a, is reduced in all pathological placentas and that hypoxia can induce pri-miR-34a expression in JEG-3 cells. We also studied the methylation status of the miR-34a promoter and revealed hypomethylation in all preeclamptic placentas (associated or not with IUGR), whereas hypoxia induced a hypermethylation in JEG-3 cells at 72 h. Despite the overexpression of pri-miR-34a in preeclampsia, there was a striking decrease of the mature miR-34a in this condition, suggesting preeclampsia-driven alteration of pri-miR-34a maturation. SERPINA3, a protease inhibitor involved in placental diseases, is elevated in IUGR and PE. We show here that miR-34a overexpression in JEG-3 downregulates SERPINA3. The low level of mature miR-34a could thus be an important mechanism contributing to SERPINA3 upregulation in placental diseases. Overall, our results support a role for miR-34a in the pathophysiology of preeclampsia, through deregulation of the pri-miRNA expression and its altered maturation. PMID:24081307

  11. bmo-miR-0001 and bmo-miR-0015 down-regulate expression of Bombyx mori fibroin light chain gene in vitro*

    PubMed Central

    Chen, Chen; Fan, Yang-yang; Wang, Xin; Song, Fei; Jiang, Tao; Qian, Ping; Tang, Shun-ming; Shen, Xing-jia

    2016-01-01

    Based on bioinformatic analysis, we selected two novel microRNAs (miRNAs), bmo-miR-0001 and bmo-miR-0015, from high-throughput sequencing of the Bombyx mori larval posterior silk gland (PSG). Firstly, we examined the expression of bmo-miR-0001 and bmo-miR-0015 in 12 different tissues of the 5th instar Day-3 larvae of the silkworm. The results showed that the expression levels of both bmo-miR-0001 and bmo-miR-0015 were obviously higher in the PSG than in other tissues, implying there is a spatio-temporal condition for bmo-miR-0001 and bmo-miR-0015 to regulate the expression of BmFib-L. To test this hypothesis, we constructed pri-bmo-miR-0001 expressing the plasmid pcDNA3.0 [ie1-egfp-pri-bmo-miR-0001-SV40] and pri-bmo-miR-0015 expressing the plasmid pcDNA3.0 [ie1-egfp-pri-bmo-miR-0015-SV40]. Finally, the BmN cells were harvested and luciferase activity was detected. The results showed that luciferase activity was reduced significantly (P<0.05) in BmN cells co-transfected by pcDNA3.0 [ie1-egfp-pri-bmo-miR-0001-SV40] or pcDNA3.0 [ie1-egfp-pri-bmo-miR-0015-SV40] with pGL3.0 [A3-luc-Fib-L-3'UTR-SV40], suggesting that both bmo-miR-0001 and bmo-miR-0015 can down-regulate the expression of BmFib-L in vitro. PMID:26834013

  12. Evaluation of the photochemical reflectance index in AVIRIS imagery

    NASA Technical Reports Server (NTRS)

    Gamon, John A.; Roberts, Dar A.; Green, Robert O.

    1995-01-01

    In this paper, we evaluate the potential for extracting the 'photochemical reflectance index' (PRI; previously called the 'physiological reflectance index') from AVIRIS data. This index, which is derived from narrow-band reflectance at 531 and 570 nm, has proven to be a useful indicator of photosynthetic function at the leaf and canopy scales. At the leaf level, PRI varies with photosynthetic capacity, radiation-use efficiency, and vegetation type (unpublished data). This finding is consistent with the hypothesis that vegetation types exhibiting chronically reduced photosynthesis during periods of stress (e.g. drought-tolerant evergreens) invest proportionally more in photoprotective processes than vegetation with high photosynthetic capacity (e.g. crops or deciduous perennials). Vertical transects in tropical and boreal forest canopies have indicated declines in PRI associated with downregulation of photosynthesis at the canopy tops under sunny, dry midday conditions (unpublished data). This reduced PRI in upper canopy levels provides a further basis for examining this signal with the 'view from above' afforded by aircraft overflights. Although many factors could confound interpretation of a subtle physiological signal at the landscape scale, we conducted a preliminary examination of PRI extracted from existing, AVIRIS imagery of Stanford University's Jasper Ridge Biological Preserve obtained on the June 2nd, 1992, overflight. The goal was to use the hyperspectral capabilities of AVIRIS to evaluate the potential of this index for obtaining useful physiological data at the landscape scale. The expectation based on leaf- and canopy-level studies was that regions containing vegetation of reduced photosynthetic capacity (e.g. chaparral or evergreen woodland) would exhibit lower PRI values than regions of high capacity (e.g. deciduous woodland).

  13. Relation between clopidogrel active metabolite levels and different platelet aggregation methods in patients receiving clopidogrel and aspirin.

    PubMed

    Liang, Yan; Johnston, Marilyn; Hirsh, Jack; Pare, Guillaume; Li, Chunjian; Mehta, Shamir; Teo, Koon K; Sloane, Debi; Yi, Qilong; Zhu, Jun; Eikelboom, John W

    2012-11-01

    Clopidogrel is a prodrug that undergoes bioconversion via cytochrome P450 system to form an active metabolite (AM) that binds to the platelet ADP receptor. The antiplatelet effect of clopidogrel is commonly assessed by measuring the aggregatory response to 5 μM ADP by light transmission aggregation (LTA) or multiple electrode aggregometry (MEA) or by the vasodilator-stimulated phosphoprotein platelet reactivity index (VASP-PRI). To determine which of these three tests of platelet ADP receptor pathway inhibition most closely correlates with clopidogrel AM levels. We analyzed blood samples from 82 patients with coronary artery disease who were randomized to receive double-dose or standard dose clopidogrel for 2 weeks. We measured peak clopidogrel AM levels, platelet aggregation in response to ADP and VASP-PRI on days 1, and repeated all the measures on days 7 and 14. Linear regression analysis was used to examine the correlation between clopidogrel AM and LTA, MEA and VASP-PRI. Bland-Altman plots were used to explore the agreement between tests of the antiplatelet effects of clopidogrel. Clopidogrel AM on day 1 correlated most closely with VASP-PRI (r = -0.5767) and demonstrated weaker correlations with LTA (r = -0.4656) and MEA (r = -0.3384) (all p < 0.01). Intra-class correlation (ICC) between VASP-PRI and LTA was 0.6446; VASP-PRI and MEA was 0.4720; and LTA and MEA was 0.4693. Similar results were obtained on days 7 and 14. Commonly used pharmacodynamic measures of clopidogrel response are only moderately correlated with clopidogrel AM levels and may not be suitable to measure the adequacy of clopidogrel therapy. PMID:22797934

  14. Application of Ca stable isotopes to long-term changes in the Ca cycle of a Northern Hardwood forest

    NASA Astrophysics Data System (ADS)

    Kurtz, A. C.; Takagi, K.; Bailey, S. W.; Bullen, T. D.

    2015-12-01

    The Hubbard Brook Ecosystem Study (New Hampshire, USA) presents an unusual opportunity for the application of innovative isotope methods in forest biogeochemistry. Changes in biogeochemical cycling resulting from decades of acid deposition, subsequent reductions in acid deposition, and a series of experimental treatments (harvesting, Ca amendment) have been studied continuously for 60 years at this site. Importantly, researchers have archived soil, water, and vegetation samples for much of the site's history. Our work seeks to complement earlier mass balance studies of Ca cycling by measuring Ca isotope ratios on archived samples. In the first component of our study, we examined the Ca isotopic response to an experimental clearcut in the early 1980's. Earlier work showed that the clearcut promoted dramatic loss of Ca from the watershed, indicated by a 5-fold increase in streamwater Ca concentrations. The mechanism for this loss was unclear as no resolvable changes in soil Ca pools were observed. Our work shows that streamwater dissolved Ca becomes isotopically lighter as Ca concentrations increase. These data are best accounted for by an increase in Ca loss from the soil cation exchange complex. Soil exchangeable δ44Ca itself evolves towards lighter values in the years following the experimental harvest. We interpret this as replenishment of the soil exchange complex by release of isotopically light Ca from root biomass. In the second component of our study, we examine decadal-scale changes in streamwater and soil Ca in an un-manipulated biogeochemical reference watershed. Historical data from Hubbard Brook show that streamwater Ca concentrations began decreasing sharply in the early 1970's, attributed to decreased deposition of both acidity and Ca with the passage of the Clean Air Act. Preliminary data indicate no resolvable change in the average δ44Ca of streamwater, with variability mostly attributable to discharge (flowpath control). Preliminary data

  15. ISOCHRONS IN PRESOLAR GRAPHITE GRAINS FROM ORGUEIL

    SciTech Connect

    Zinner, Ernst; Jadhav, Manavi

    2013-05-10

    Primitive meteorites contain tiny dust grains that condensed in stellar outflows and explosions. These stardust grains can be extracted from their host meteorites and studied in detail in the laboratory. We investigated depth profiles of the Al-Mg, Ca-K, and Ti-Ca isotopic systems obtained during NanoSIMS isotopic analysis of presolar graphite grains from the CI carbonaceous meteorite Orgueil. Large {sup 26}Al/{sup 27}Al, {sup 41}Ca/{sup 40}Ca, and {sup 44}Ti/{sup 48}Ti ratios, inferred from {sup 26}Mg, {sup 41}K, and {sup 44}Ca excesses from the decay of the short-lived radioisotopes {sup 26}Al, {sup 41}Ca, and {sup 44}Ti, indicate a supernova (SN) origin. From the depth distribution of the radiogenic isotopes and the stable isotopes of their parent elements we constructed isochron-type correlation plots. The plots indicate quantitative retention of radiogenic {sup 26}Mg, {sup 41}K, and {sup 44}Ca in most grains. Deviations from straight lines in the Al-Mg and Ca-K plots can be explained by contamination with {sup 27}Al and isotopically normal Ca, respectively. For the Ti-Ca system in some grains, the lack of parent-daughter correlation indicates either redistribution of radiogenic {sup 44}Ca or heterogeneity in the initial {sup 44}Ti/{sup 48}Ti ratio. We also obtained Si isotopic depth profiles in three graphite grains with large {sup 29}Si and {sup 30}Si excesses, for which a SN origin has been proposed. In two grains no Si-rich subgrains are observed; in the third grain with an apparent Si-rich subgrain the anomalous Si isotopic ratios in the subgrain are the same as in the rest of the graphite host. Our studies show that by measuring depth profiles, information on presolar grains can be obtained that cannot be obtained by whole-grain analysis.

  16. Sr, Ca, and C isotope systematic in small tropical catchments, La Selva, Costa Rica

    NASA Astrophysics Data System (ADS)

    Wiegand, B. A.; Schwendenmann, L.

    2010-12-01

    Sr, Ca, and C isotopes were analyzed to assess sources and biogeochemical processes affecting surface and groundwater composition of four small catchments located at La Selva Biological Station, Costa Rica. 87Sr/86Sr ratios were employed to quantify inputs from mineral weathering and atmospheric sources. δ13C values of dissolved organic carbon (DOC) and δ44Ca values provide information on biological processes that affect water chemistry. Sr2+ and Ca2+ concentrations of surface and groundwater show large variations due to intermixture of bedrock groundwater with local groundwater [1]. Low 87Sr/86Sr ratios suggest weathering of volcanic rocks as the primary solute source in bedrock groundwater, while atmospheric and in situ weathering contributions are predominant in local groundwater. Contributions of bedrock groundwater constitute > 60 % in the Salto, Saltito and Arboleda catchments, whereas the Taconazo catchment receives atmospheric inputs of > 95 % in addition to local weathering contributions. Surface water and groundwater wells show δ13C-DOC values between -24 ‰ and -30 ‰ due to transfer of organic carbon from the soil zone. δ44Ca values of dissolved Ca2+ in surface and groundwater are considerably fractionated from the input sources rainwater and bedrock groundwater. Light δ44Ca values are preferentially distributed in stream water and shallow groundwater horizons and contrast with heavy Ca isotopes in deeper groundwater wells. Biological processes including plant uptake and decomposition in combination with cation exchange processes in the soils may explain the fractionation of Ca isotopes. [1]Genereux et al., 2009. Water Resour. Res, 45, W08413, doi:10.1029/2008WR007630

  17. Mechanical Model of Steel-concrete Composite Joint under Sagging Bending Moment

    NASA Astrophysics Data System (ADS)

    Pisarek, Zdzisław

    2012-06-01

    In buildings with steel-concrete composite floors, joints are designed to transmit mainly hogging bending moment. In case of the large horizontal loads due to wind, earthquake or accidental events, sagging bending moments in a joint can also occur. Additionally, large deformations of the structure cause tying and prying effects. In the paper, a mechanical model based on "component method" for evaluation of characteristics of the composite joint is presented. The influence of tying and prying actions on distribution of the internal forces in a joint is also analyzed. The procedure for calculation of the characteristics of the composite joint with bolted endplate connection is elaborated too.

  18. Co-occurrence of analogous enzymes determines evolution of a novel (βα)8-isomerase sub-family after non-conserved mutations in flexible loop.

    PubMed

    Verduzco-Castro, Ernesto A; Michalska, Karolina; Endres, Michael; Juárez-Vazquez, Ana L; Noda-García, Lianet; Chang, Changsoo; Henry, Christopher S; Babnigg, Gyorgy; Joachimiak, Andrzej; Barona-Gómez, Francisco

    2016-05-01

    We investigate the evolution of co-occurring analogous enzymes involved in L-tryptophan and L-histidine biosynthesis in Actinobacteria Phylogenetic analysis of trpF homologues, a missing gene in certain clades of this lineage whose absence is complemented by a dual-substrate HisA homologue, termed PriA, found that they fall into three categories: (i) trpF-1, an L-tryptophan biosynthetic gene horizontally acquired by certain Corynebacterium species; (ii) trpF-2, a paralogue known to be involved in synthesizing a pyrrolopyrrole moiety and (iii) trpF-3, a variable non-conserved orthologue of trpF-1 We previously investigated the effect of trpF-1 upon the evolution of PriA substrate specificity, but nothing is known about the relationship between trpF-3 and priA After in vitro steady-state enzyme kinetics we found that trpF-3 encodes a phosphoribosyl anthranilate isomerase. However, mutation of this gene in Streptomyces sviceus did not lead to auxothrophy, as expected from the biosynthetic role of trpF-1 Biochemical characterization of a dozen co-occurring TrpF-2 or TrpF-3, with PriA homologues, explained the prototrophic phenotype, and unveiled an enzyme activity trade-off between TrpF and PriA. X-ray structural analysis suggests that the function of these PriA homologues is mediated by non-conserved mutations in the flexible L5 loop, which may be responsible for different substrate affinities. Thus, the PriA homologues that co-occur with TrpF-3 represent a novel enzyme family, termed PriB, which evolved in response to PRA isomerase activity. The characterization of co-occurring enzymes provides insights into the influence of functional redundancy on the evolution of enzyme function, which could be useful for enzyme functional annotation. PMID:26929404

  19. Coherent radar observations of a storm sudden commencement having a preliminary reverse impulse

    SciTech Connect

    McDiarmid, D.R.; Nielsen, E. )

    1987-01-01

    Observations of the February 4, 1983, storm sudden commencement (ssc) by the STARE and SABRE radar systems are presented. The observing stations were in the dusk sector, where the ssc was accompanied by a preliminary reverse impulse (PRI). The radar data show the PRI to be a consequence of the ssc compression wave producing an initial antisunward flow. The polarization of the ssc electric field in the ionosphere is seen to have both longitudinal and latitudinal structure. The observations are discussed in terms of the propagation of the ssc disturbance throughout the magnetosphere.

  20. Utilizing In Situ Directional Hyperspectral Measurements to Validate Bio-Indicator Simulations for a Corn Crop Canopy

    NASA Technical Reports Server (NTRS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Huemmrich, Karl F.; Zhang, Qingyuan; Campbell, Petya K. E.; Corp, Lawrence A.; Russ, Andrew L.; Kustas, William P.

    2010-01-01

    Two radiative transfer canopy models, SAIL and the two-layer Markov-Chain Canopy Reflectance Model (MCRM), were coupled with in situ leaf optical properties to simulate canopy-level spectral band ratio vegetation indices with the focus on the photochemical reflectance index in a cornfield. In situ hyperspectral measurements were made at both leaf and canopy levels. Leaf optical properties were obtained from both sunlit and shaded leaves. Canopy reflectance was acquired for eight different relative azimuth angles (psi) at three different view zenith angles (Theta (sub v)), and later used to validate model outputs. Field observations of photochemical reflectance index (PRI) for sunlit leaves exhibited lower values than shaded leaves, indicating higher light stress. Canopy PRI expressed obvious sensitivity to viewing geometry, as a function of both Theta (sub v) and psi . Overall, simulations from MCRM exhibited better agreements with in situ values than SAIL. When using only sunlit leaves as input, the MCRM-simulated PRI values showed satisfactory correlation and RMSE, as compared to in situ values. However, the performance of the MCRM model was significantly improved after defining a lower canopy layer comprised of shaded leaves beneath the upper sunlit leaf layer. Four other widely used band ratio vegetation indices were also studied and compared with the PRI results. MCRM simulations were able to generate satisfactory simulations for these other four indices when using only sunlit leaves as input; but unlike PRI, adding shaded leaves did not improve the performance of MCRM. These results support the hypothesis that the PRI is sensitive to physiological dynamics while the others detect static factors related to canopy structure. Sensitivity analysis was performed on MCRM in order to better understand the effects of structure related parameters on the PRI simulations. Leaf area index (LAI) showed the most significant impact on MCRM-simulated PRI among the parameters

  1. The Photochemical Reflectance Index from Directional Cornfield Reflectances: Observations and Simulations

    NASA Technical Reports Server (NTRS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Zhang, Qingyuan; Corp, Lawrence A.; Dandois, Jonathan; Kustas, William P.

    2012-01-01

    The two-layer Markov chain Analytical Canopy Reflectance Model (ACRM) was linked with in situ hyperspectral leaf optical properties to simulate the Photochemical Reflectance Index (PRI) for a corn crop canopy at three different growth stages. This is an extended study after a successful demonstration of PRI simulations for a cornfield previously conducted at an early vegetative growth stage. Consistent with previous in situ studies, sunlit leaves exhibited lower PRI values than shaded leaves. Since sunlit (shaded) foliage dominates the canopy in the reflectance hotspot (coldspot), the canopy PRI derived from field hyperspectral observations displayed sensitivity to both view zenith angle and relative azimuth angle at all growth stages. Consequently, sunlit and shaded canopy sectors were most differentiated when viewed along the azimuth matching the solar principal plane. These directional PRI responses associated with sunlit/shaded foliage were successfully reproduced by the ACRM. As before, the simulated PRI values from the current study were closer to in situ values when both sunlit and shaded leaves were utilized as model input data in a two-layer mode, instead of a one-layer mode with sunlit leaves only. Model performance as judged by correlation between in situ and simulated values was strongest for the mature corn crop (r = 0.87, RMSE = 0.0048), followed by the early vegetative stage (r = 0.78; RMSE = 0.0051) and the early senescent stage (r = 0.65; RMSE = 0.0104). Since the benefit of including shaded leaves in the scheme varied across different growth stages, a further analysis was conducted to investigate how variable fractions of sunlit/shaded leaves affect the canopy PRI values expected for a cornfield, with implications for 20 remote sensing monitoring options. Simulations of the sunlit to shaded canopy ratio near 50/50 +/- 10 (e.g., 60/40) matching field observations at all growth stages were examined. Our results suggest in the importance of the

  2. Calcium-48 isotopic anomalies in bulk chondrites and achondrites: Evidence for a uniform isotopic reservoir in the inner protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Dauphas, Nicolas; Chen, James H.; Zhang, Junjun; Papanastassiou, Dimitri A.; Davis, Andrew M.; Travaglio, Claudia

    2014-12-01

    Thermal ionization mass spectrometry (TIMS) was used to measure the calcium isotopic compositions of carbonaceous, ordinary, enstatite chondrites as well as eucrites and aubrites. We find that after correction for mass-fractionation by internal normalization to a fixed 42Ca/44Ca ratio, the 43Ca/44Ca and 46Ca/44Ca ratios are indistinguishable from terrestrial ratios. In contrast, the 48Ca/44Ca ratios show significant departure from the terrestrial composition (from -2 ε in eucrites to +4 ε in CO and CV chondrites). Isotopic anomalies in ε48Ca correlate with ε50Ti: ε 48Ca=(1.09±0.11)×ε 50Ti+(0.03±0.14). Further work is needed to identify the carrier phase of 48Ca-50Ti anomalies but we suggest that it could be perovskite and that the stellar site where these anomalies were created was also responsible for the nucleosynthesis of the bulk of the solar system inventory of these nuclides. The Earth has identical 48Ca isotopic composition to enstatite chondrites (EH and EL) and aubrites. This adds to a long list of elements that display nucleosynthetic anomalies at a bulk planetary scale but show identical or very similar isotopic compositions between enstatite chondrites, aubrites, and Earth. This suggests that the inner protoplanetary disk was characterized by a uniform isotopic composition (IDUR for Inner Disk Uniform Reservoir), sampled by enstatite chondrites and aubrites, from which the Earth drew most of its constituents. The terrestrial isotopic composition for 17O, 48Ca, 50Ti, 62Ni, and 92Mo is well reproduced by a mixture of 91% enstatite, 7% ordinary, and 2% carbonaceous chondrites. The Earth was not simply made of enstatite chondrites but it formed from the same original material that was later modified by nebular and disk processes. The Moon-forming impactor probably came from the same region as the other embryos that made the Earth, explaining the strong isotopic similarity between lunar and terrestrial rocks.

  3. Unlocking Student Data Could Lead to "App Economy" for Colleges: Colleges Are Pressured to Open Up Student Data

    ERIC Educational Resources Information Center

    DeSantis, Nick

    2012-01-01

    College campuses are hothouses of data, including course schedules, degree requirements, and grades. But much of the information remains spread out across software systems or locked on university servers. Start-up companies want to pry the information loose from campus servers in order to offer personalized services that could transform the…

  4. Utilizing in situ Directional Hyperpectral Measurements to Validate Bio-Indicator Simulations for a Corn Crop Canaopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two radiative transfer canopy models, SAIL and the Markov-Chain Canopy Reflectance Model (MRCM), were coupled with in situ leaf optical properties to simulate canopy-level spectral band ratio vegetation indices with the focus on the Photochemical Reflectance Index (PRI) in a cornfield. In situ hyper...

  5. Alternative splicing affects the subcellular localization of Drosha

    PubMed Central

    Link, Steffen; Grund, Stefanie E.; Diederichs, Sven

    2016-01-01

    The RNase III enzyme Drosha is a key factor in microRNA (miRNA) biogenesis and as such indispensable for cellular homeostasis and developmental processes. Together with its co-factor DGCR8, it converts the primary transcript (pri-miRNA) into the precursor hairpin (pre-miRNA) in the nucleus. While the middle and the C-terminal domain are crucial for pri-miRNA processing and DGCR8 binding, the function of the N-terminus remains cryptic. Different studies have linked this region to the subcellular localization of Drosha, stabilization and response to stress. In this study, we identify alternatively spliced Drosha transcripts that are devoid of a part of the arginine/serine-rich (RS-rich) domain and expressed in a large set of human cells. In contrast to their expected habitation, we find two isoforms also present in the cytoplasm, while the other two isoforms reside exclusively in the nucleus. Their processing activity for pri-miRNAs and the binding to co-factors remains unaltered. In multiple cell lines, the endogenous mRNA expression of the Drosha isoforms correlates with the localization of endogenous Drosha proteins. The pri-miRNA processing efficiency is not significantly different between groups of cells with or without cytoplasmic Drosha expression. In summary, we discovered novel isoforms of Drosha with differential subcellular localization pointing toward additional layers of complexity in the regulation of its activity. PMID:27185895

  6. The conservation-production interface in rangelands: Acknowledging tradeoffs and moving towards win-win solutions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Provision of wildlife habitat in rangelands, particularly for birds of conservation concern, is increasingly recognized as an important ecosystem service. Accommodating human use is also a key component of ecosystem management. Most remaining grassland bird habitat in the western Great Plains is pri...

  7. STA1, an Arabidopsis pre-mRNA processing factor 6 homolog, is a new player involved in miRNA biogenesis

    PubMed Central

    Ben Chaabane, Samir; Liu, Renyi; Chinnusamy, Viswanathan; Kwon, Yerim; Park, Joo-hyuk; Kim, Seo Yeon; Zhu, Jian-Kang; Yang, Seong Wook; Lee, Byeong-ha

    2013-01-01

    MicroRNAs (miRNAs) are small regulatory RNAs that have important regulatory roles in numerous developmental and metabolic processes in most eukaryotes. In Arabidopsis, DICER-LIKE1 (DCL1), HYPONASTIC LEAVES 1, SERRATE, HUA ENHANCER1 and HASTY are involved in processing of primary miRNAs (pri-miRNAs) to yield precursor miRNAs (pre-miRNAs) and eventually miRNAs. In addition to these components, mRNA cap-binding proteins, CBP80/ABA HYPERSENSITIVE1 and CBP20, also participate in miRNA biogenesis. Here, we show that STABILIZED1 (STA1), an Arabidopsis pre-mRNA processing factor 6 homolog, is also involved in the biogenesis of miRNAs. Similar to other miRNA biogenesis-defective mutants, sta1-1 accumulated significantly lower levels of mature miRNAs and concurrently higher levels of pri-miRNAs than wild type. The dramatic reductions of mature miRNAs were associated with the accumulation of their target gene transcripts and developmental defects. Furthermore, sta1-1 impaired splicing of intron containing pri-miRNAs and decreased transcript levels of DCL1. These results suggest that STA1 is involved in miRNA biogenesis directly by functioning in pri-miRNA splicing and indirectly by modulating the DCL1 transcript level. PMID:23268445

  8. Inhibition of Cyclic Adenosine Monophosphate (cAMP)-response Element-binding Protein (CREB)-binding Protein (CBP)/β-Catenin Reduces Liver Fibrosis in Mice

    PubMed Central

    Osawa, Yosuke; Oboki, Keisuke; Imamura, Jun; Kojika, Ekumi; Hayashi, Yukiko; Hishima, Tsunekazu; Saibara, Toshiji; Shibasaki, Futoshi; Kohara, Michinori; Kimura, Kiminori

    2015-01-01

    Wnt/β-catenin is involved in every aspect of embryonic development and in the pathogenesis of many human diseases, and is also implicated in organ fibrosis. However, the role of β-catenin-mediated signaling on liver fibrosis remains unclear. To explore this issue, the effects of PRI-724, a selective inhibitor of the cAMP-response element-binding protein-binding protein (CBP)/β-catenin interaction, on liver fibrosis were examined using carbon tetrachloride (CCl4)- or bile duct ligation (BDL)-induced mouse liver fibrosis models. Following repetitive CCl4 administrations, the nuclear translocation of β-catenin was observed only in the non-parenchymal cells in the liver. PRI-724 treatment reduced the fibrosis induced by CCl4 or BDL. C-82, an active form of PRI-724, inhibited the activation of isolated primary mouse quiescent hepatic stellate cells (HSCs) and promoted cell death in culture-activated HSCs. During the fibrosis resolution period, an increase in F4/80+ CD11b+ and Ly6Clow CD11b+ macrophages was induced by CCl4 and was sustained for two weeks thereafter, even after having stopped CCl4 treatment. PRI-724 accelerated the resolution of CCl4-induced liver fibrosis, and this was accompanied by increased matrix metalloproteinase (MMP)-9, MMP-2, and MMP-8 expression in intrahepatic leukocytes. In conclusion, targeting the CBP/β-catenin interaction may become a new therapeutic strategy in treating liver fibrosis. PMID:26870800

  9. Tool Removes Coil-Spring Thread Inserts

    NASA Technical Reports Server (NTRS)

    Collins, Gerald J., Jr.; Swenson, Gary J.; Mcclellan, J. Scott

    1991-01-01

    Tool removes coil-spring thread inserts from threaded holes. Threads into hole, pries insert loose, grips insert, then pulls insert to thread it out of hole. Effects essentially reverse of insertion process to ease removal and avoid further damage to threaded inner surface of hole.

  10. Atmospheric Modeling

    EPA Science Inventory

    Although air quality models have been applied historically to address issues specific to ambient air quality standards (i.e., one criteria pollutant at a time) or welfare (e.g.. acid deposition or visibility impairment). they are inherently multipollutant based. Therefore. in pri...

  11. Free Amino Acid Profiles from 'Pinot Noir' Grapes are Influenced by Vine N-status and Sample Preparation Method

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study examined the impact of extraction method on ammonia, free amino acids, and YAN (yeast assimilable nitrogen) concentrations in 'Pinot noir' berries obtained from a vine nutrition study (altered supply of N, P, or K). Berries were either juiced or exhaustively extracted as whole berries pri...

  12. In vitro Reconstitution Assay of miRNA Biogenesis by Arabidopsis DCL1

    PubMed Central

    Wang, Tian; Castillo-González, Claudia; You, Lan; Li, Rui; Wen, Liwei; Zhu, Hongliang; Zhang, Xiuren

    2016-01-01

    microRNAs (miRNAs) are small non-coding RNAs, regulating most if not all, biological processes in eukaryotic organisms. miRNAs are initially processed from primary transcripts (pri-miRNAs) to produce miRNA precursors (pre-miRNAs), that are further processed into miRNA and its complementary strands (miRNA/*). In Arabidopsis, and possibly other plants, the processing from pri-miRNAs to pre-miRNAs and from pre-miRNAs to miRNA/* are both implemented through Dicer-like 1 (DCL1) complexes. Recently, we demonstrated isolation of DCL1 complexes of unprecedented quality from in planta. We further successfully reconstituted DCL1 cleavage assays in vitro that were able to fully recapitulate in vivo miRNA biogenesis. Here we provide a detailed protocol of DCL1 reconstitution assays. The protocol comprises three major parts (Figure 1): 1) Preparation of pri- and pre-miRNA transcripts (Procedures A-C); 2) Purification of the recombinant Arabidopsis DCL1 machinery from Nicotiana benthamiana (N. benthamiana) through immunoprecipitation (IP) (Procedures D and E); and 3) in vitro processing of radioisotope-labeled pri- or pre-miRNAs using the isolated DCL1 complexes (Procedure F). It is our desire that the protocol be a powerful tool for the RNAi community to study mechanistic issues or to develop RNA silencing technologies.

  13. CONTINUOUS STIRRED TANK REACTOR INVESTIGATION OF THE GAS-PHASE REACTION OF HYDROXYL RADICALS AND TOLUENE

    EPA Science Inventory

    A continuous stirred tank reactor (CSTR) was used to study the gas phase reaction between HO and toluene. HO was generated by the in situ photolysis of nitrous acid. Flow reactor operation at steady state conditions with a residence time of 20 minutes allowed investigation of pri...

  14. The photochemical reflectance index from directional cornfield reflectances: Observations and simulations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The two-layer Markov chain Analytical Canopy Reflectance Model (ACRM) was linked with in situ hyperspectral leaf optical properties to simulate the Photochemical Reflectance Index (PRI) for a corn crop canopy at three different growth stages. This is an extended study after a successful demonstratio...

  15. Predicting Photosynthetic Fluxes from Spectral Reflectance of Leaves and Canopies

    NASA Technical Reports Server (NTRS)

    Gamon, John A.

    1997-01-01

    The central hypothesis of this study has been that photosynthetic efficiency and capacity can be predicted from 'physiological reflectance indices' derived from spectral reflectance of leaves and canopies. I have approached this topic with a combination of laboratory and field experiments, and have also explored the potential of deriving a meaningful physiological index from imaging spectrometry (e.g. AVIRIS). A few highlights are presented below. The main emphasis has been on the 'Photochemical Reflectance Index' (PRI), derived from reflectance at 531 nm and 570 nm. Unlike most 'conventional' vegetation indices (e.g. NDVI), PRI changes rapidly both with illumination and physiological state, because it detects the interconversion of xanthophyll cycle pigments, which serve as photoregulatory pigments and control energy distribution for the photosynthetic system. This approach has differed dramatically from most remote sensing in that it has emphasized temporal variation in narrow-band spectral signatures, instead of spatial patterns of broadband indices. Our primary conclusion has been that PRI works well as an index of photosynthetic light-use efficiency at the leaf scale, much in the same way as the fluorescence index DeltaF/Fm. However, unlike DeltaF/Fm which must be measured at close scales, PRI can be sampled at a range of spatial scales, presenting the possibility of monitoring photosynthetic fluxes remotely.

  16. Research and Teaching. The Science Identity of College Students: Exploring the Intersection of Gender, Race, and Ethnicity

    ERIC Educational Resources Information Center

    Hazari, Zahra; Sadler, Philip M.; Sonnert, Gerhard

    2013-01-01

    This study explores students' self-perceptions across science subjects (biology, chemistry, and physics) by gender and underrepresented minority group membership. The data are drawn from the Persistence Research in Science and Engineering (PRiSE) project, which surveyed 7,505 students (enrolled in college English courses required for all…

  17. IMPACT OF URBAN AND INDUSTRIAL EMISSIONS ON MESOSCALE PRECIPITATION QUALITY

    EPA Science Inventory

    Results from an 'acid rain' field study around the city of Philadelphia are presented. The study involved the sampling of wet deposition at a network of 40 sites within a distance of 60 km from the Delaware River. Emphasis was placed on event-type rain sampling of frontal and pri...

  18. The Roles of Arabidopsis CDF2 in Transcriptional and Posttranscriptional Regulation of Primary MicroRNAs

    PubMed Central

    Sun, Zhenfei; Guo, Tongtong; Liu, Yin; Liu, Qi; Fang, Yuda

    2015-01-01

    The precise regulation of microRNA (miRNA) transcription and processing is important for eukaryotic development. Plant miRNAs are first transcribed as stem-loop primary miRNAs (pri-miRNAs) by RNA polymerase II,then cleaved in the nucleus into mature miRNAs by Dicer-like 1 (DCL1). We identified a cycling DOF transcription factor, CDF2, which interacts with DCL1 and regulates the accumulation of a population of miRNAs. CDF2 binds directly to the promoters of some miRNAs and works as a transcription activator or repressor for these miRNA genes. CDF2 binds preferentially to the pri-miRNAs regulated by itself and affects DCL1-mediated processing of these pri-miRNAs. Genetically, CDF2 works in the same pathway as miR156 or miR172 to control flowering. We conclude that CDF2 regulates a group of pri-miRNAs at both the transcriptional and posttranscriptional levels to maintain proper levels of their mature miRNAs to control plant development. PMID:26473486

  19. 77 FR 4858 - 60-Day Notice of Proposed Information Collection: DS 5507, Affidavit of Physical Presence or...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-31

    ... . Mail (paper, disk, or CD-ROM submissions): U.S. Department of State, CA/OCS/PRI, SA-29, 4th Floor...- 29, 4th Floor, Washington, DC 20520 or at ASKPRI@state.gov . SUPPLEMENTARY INFORMATION: We are... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF STATE...

  20. MIDDLE REACH OF THE SNAKE RIVER: WATER QUALITY AND BENTHIC BIOMONITORING

    EPA Science Inventory

    This study examined spatial and temporal trends in water quality, sestonic and benthic algal concentrations, and benthic macroinvertebrate taxa richness, population density, and biomass at nine stations along the Middle Snake River from Pillar Falls to Upper Salmon Falls Dam. Pri...

  1. Relationship of antral follicle counts to fertility and ovarian AMH mRNA levels in beef cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In mammalian females, reproductive senescence is associated with decreased numbers of follicles in the ovary. Anti-Mullerian Hormone (AMH) of ovarian origin has been proposed to be a biomarker of the number of follicles in the ovary and of fertility in women, as well as to control activation of pri...

  2. REGIONAL PARTICULATE MODEL - 1. MODEL DESCRIPTION AND PRELIMINARY RESULTS

    EPA Science Inventory

    The gas-phase chemistry and transport mechanisms of the Regional Acid Deposition Model have been modified to create the Regional Particulate Model, a three-dimensional Eulerian model that simulates the chemistry, transport, and dynamics of sulfuric acid aerosol resulting from pri...

  3. STRUCTURE-ACTIVITY APPROACHES IN THE SCREENING OF ENVIRONMENTAL AGENTS FOR DEVELOPMENTAL TOXICITY

    EPA Science Inventory

    In drug development, SARs are an integral part of the process of finding efficacious and non-toxic analogues, and in vitro test systems which detect the biological activity of a particular chemical class have found an important role in SAR research. n contrast, SARs are not a pri...

  4. 49 CFR 239.101 - Emergency preparedness plan.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... operations on elevated structures, including drawbridges, and in electrified territory. (iii) Parallel... action to coordinate emergency efforts where adjacent rail modes of transportation run parallel to either... minimum: (A) One fire extinguisher per passenger car; (B) One pry bar per passenger car; and (C)...

  5. Evaluation of Ethanol Extracted Surface Antigens of Mycobacterium bovis for Diagnosis of Bovine Tuberculosis in Livestock Cattle and Wild Deer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Bovine tuberculosis (TB), caused by Mycobacterium bovis, is a zoonotic disease resulting in chronic granulomatous lymphadenitis, particularly in the lungs and lung-associated lymph nodes. Although bovine TB has been nearly eradicated in many developed countries, the disease persists pri...

  6. ADHD and College Students: Exploratory and Confirmatory Factor Structures With Student and Parent Data

    ERIC Educational Resources Information Center

    Glutting, Joseph J.; Youngstrom, Eric A.; Watkins, Marley W.

    2005-01-01

    Exploratory factor analyses (EFAs) and confirmatory factor analyses (CFAs) were used to investigate the structure of the Student Report Inventory (SRI) and Parent Report Inventory (PRI) of the College Attention-Deficit/Hyperactivity Disorder (ADHD) Response Evaluation. The sample was composed of 1,080 college students and their parents and was…

  7. Dual purpose use of preterm piglets as a model of pediatric GI disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Necrotizing enterocolitis (NEC) is the most common gastrointestinal complication in human neonates, yet the pathogenesis of this disease remains poorly understood. A fundamental approach to understanding the etiology and underlying biology of NEC is the use of in vivo experimental animal models, pri...

  8. Genome Sequence of the Emerging Plant Pathogen Dickeya solani Strain RNS 08.23.3.1A

    PubMed Central

    Khayi, Slimane; Mondy, Samuel; Beury-Cirou, Amélie; Moumni, Mohieddine; Hélias, Valérie

    2014-01-01

    Here we present the genome sequence of Dickeya solani strain RNS 08.23.3.1A (PRI3337), isolated from Solanum tuberosum. Dickeya solani, recently described on potato cultures in Europe, is a proposed new taxon closely related to the Dickeya dianthicola and Dickeya dadantii species. PMID:24482527

  9. Gone but Not Forgotten

    ERIC Educational Resources Information Center

    Monastersky, Richard

    2006-01-01

    Neanderthals, those long-lost cousins of modern humans, will not remain lost for long, at least from the prying eyes of geneticists. Two teams of scientists announced that for the first time they had analyzed DNA from the nuclei of cells preserved in 37,000-year-old Neanderthal fossils. That, they say, lays the groundwork for determining the…

  10. ENVIRONMENTAL QUALITY INFORMATION SYSTEM - EQULS® - ITER

    EPA Science Inventory

    This project consisted of an evaluation of the Environmental Quality Information System (EQuIS) software designed by Earthsoft, Inc. as an environmental data management and analysis platform for monitoring and remediation projects. In consultation with the EQuIS vendor, six pri...

  11. Improved high-throughput bioassay for Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    As we gain more information through functional genomic studies of Rhyzopertha dominica (F.), we need a high throughput bioassay system to screen potential biopesticides. R. dominica is an internal feeder during immature stages and presents unique challenges with traditional bioassay methods. Our pri...

  12. Rbfox3 Controls the Biogenesis of a Subset of MicroRNAs

    PubMed Central

    Kim, Kee K.; Yang, Yanqin; Zhu, Jun; Adelstein, Robert S.; Kawamoto, Sachiyo

    2014-01-01

    RNA-binding proteins (RBPs) regulate numerous aspects of gene expression, thus identification of endogenous targets of RBPs is important for understanding their functions in cells. Here we identified transcriptome-wide targets of Rbfox3 in neuronally differentiated P19 cells and mouse brain using Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation (PAR-CLIP). Although Rbfox3 is known to regulate pre-mRNA splicing through binding to the UGCAUG motif, PAR-CLIP analysis revealed diverse Rbfox3 targets including primary-microRNAs (pri-miRNAs) which lack the UGCAUG motif. Induced expression and depletion of Rbfox3 led to changes in the expression levels of a subset of PAR-CLIP-detected miRNAs. In vitro analyses revealed that Rbfox3 functions as a positive and a negative regulator at the stage of pri-miRNA processing to precursor-miRNA. Rbfox3 binds directly to pri-miRNAs and regulates the recruitment of the microprocessor complex to pri-miRNAs. Our study proposes a novel function for Rbfox3 in miRNA biogenesis. PMID:25240799

  13. Integrative analysis of 111 reference human epigenomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The reference human genome sequence set the stage for studies of genetic variation and its association with human disease, but epigenomic studies lack a similar reference. To address this need, the NIH Roadmap Epigenomics Consortium generated the largest collection so far of human epigenomes for pri...

  14. Development and Validation of Rapid Assessment Indices of Condition for Coastal for Coastal Wetlands in Southern New England, USA

    EPA Science Inventory

    Vegetation, soils, on-site disturbances, and watershed land use and land cover were assessed at 81 coastal wetland sites using the New England Rapid Asssessment Method (NERAM). Condition indices (CIs) were derived from various combinations of the multi-dimensional data using pri...

  15. EPA'S STUDY OF THE GENERATION AND CONTROL OF AIR POLLUTANTS FROM THE COMBUSTION OF ORIMULSION

    EPA Science Inventory

    The paper discusses an EPA study of the grneration and control of air pollutants from the combustion of Orimulsion, a high-sulfur liquid petroleum fuel composed of approximately 70% Venezuelan bitumen, 30% water, and trace amounts of surfactant. (NOTE: It is being used as the pri...

  16. Characteristics of Criterion-Referenced Instruments: Implications for Materials Selection for the Learning Disabled.

    ERIC Educational Resources Information Center

    Blasi, Joyce F.

    Discussed are characteristics of criterion referenced reading tests for use with learning disabled (LD) children, and analyzed are the Basic Educational Skills Inventory (BESI), the Prescriptive Reading Inventory (PRI), and the Cooper-McGuire Diagnostic Work-Analysis Test (CooperMcGuire). Criterion referenced tests are defined; and problems in…

  17. Beyond the Narrative Mode in the Composition Classroom: Embracing a Return to the Personal Essay

    ERIC Educational Resources Information Center

    Haugen, Hayley Mitchell

    2013-01-01

    Knoblauch and Brannon might suggest I pry loose the grip that ancient rhetorical tradition has on my modern classroom, but I'm not convinced I can so easily abandon the ancient rhetoricians. Learning to embrace the different, more creative, and less frequently acknowledged elements of this tradition may be the way for me to go instead. The ancient…

  18. WISC-IV and WISC-III Profiles in Children with ADHD

    ERIC Educational Resources Information Center

    Mayes, Susan Dickerson; Calhoun, Susan L.

    2006-01-01

    Wechsler Intelligence Scale for Children, 3rd and 4th editions (WISC-III n = 586 and WISC-IV n = 118), profiles were compared for children with ADHD and normal intelligence. Mean Verbal Comprehension Index (VCI) and Perceptual Organization/Perceptual Reasoning Index (POI/PRI) scores were significantly higher than Freedom From…

  19. SEASONAL AND REGIONAL VARIATIONS OF PRIMARY AND SECONDARY ORGANIC AEROSOLS OVER THE CONTINENTAL UNITED STATES: SEMI-EMPIRICAL ESTIMATES AND MODEL EVALUATION

    EPA Science Inventory

    Seasonal and regional variations of primary (OCpri) and secondary (OCsec) organic carbon aerosols across the continental U.S. for the year 2001 were examined by a semi-empirical technique using observed OC and elemental carbon (EC) data from 142 routine moni...

  20. Development and comparison of a Primer-Probe Energy Transfer based assay and a 5' conjugated Minor Groove Binder assay for sensitive real-time PCR detection of infectious laryngotracheitis virus.

    PubMed

    McMenamy, M J; McKillen, J; Hjertner, B; Kiss, I; Yacoub, A; Leijon, M; Duffy, C; Belák, S; Welsh, M; Allan, G

    2011-08-01

    In this study the design and development of two real-time PCR assays for the rapid, sensitive and specific detection of infectious laryngotracheitis virus (ILTV) DNA is described. A Primer-Probe Energy Transfer (PriProET) assay and 5' conjugated Minor Groove Binder (MGB) method are compared and contrasted. Both have been designed to target the thymidine kinase gene of the ILTV genome. Both PriProET and MGB assays are capable of detecting 20 copies of a DNA standard per reaction and are linear from 2×10(8) to 2×10(2)copies/μl. Neither PriProET, nor MGB reacted with heterologous herpesviruses, indicating a high specificity of the two methods as novel tools for virus detection and identification. This study demonstrates the suitability of PriProET and 5' conjugated MGB probes as real-time PCR chemistries for the diagnosis of respiratory diseases caused by ILTV. PMID:21539859

  1. Spectral Bio-indicator Simulations for Tracking Photosynthetic Activities in a Corn Field

    NASA Technical Reports Server (NTRS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Huemmrich, K. Fred; Zhang, Qingyuan; Corp, Lawrence; Campbell, Petya; Kustas, William

    2011-01-01

    Accurate assessment of vegetation canopy optical properties plays a critical role in monitoring natural and managed ecosystems under environmental changes. In this context, radiative transfer (RT) models simulating vegetation canopy reflectance have been demonstrated to be a powerful tool for understanding and estimating spectral bio-indicators. In this study, two narrow band spectroradiometers were utilized to acquire observations over corn canopies for two summers. These in situ spectral data were then used to validate a two-layer Markov chain-based canopy reflectance model for simulating the Photochemical Reflectance Index (PRI), which has been widely used in recent vegetation photosynthetic light use efficiency (LUE) studies. The in situ PRI derived from narrow band hyperspectral reflectance exhibited clear responses to: 1) viewing geometry which affects the asset of light environment; and 2) seasonal variation corresponding to the growth stage. The RT model (ACRM) successfully simulated the responses to the variable viewing geometry. The best simulations were obtained when the model was set to run in the two layer mode using the sunlit leaves as the upper layer and shaded leaves as the lower layer. Simulated PRI values yielded much better correlations to in situ observations when the cornfield was dominated by green foliage during the early growth, vegetative and reproductive stages (r = 0.78 to 0.86) than in the later senescent stage (r = 0.65). Further sensitivity analyses were conducted to show the important influences of leaf area index (LAI) and the sunlit/shaded ratio on PRI observations.

  2. Superinfection exclusion of the ruminant pathogen anaplasma marginale in the tick vector is dependent on time between exposures to the strains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The remarkable genetic diversity of vector-borne pathogens allows for the establishment of superinfection in the mammalian host. To have a long-term impact on population strain structure, the introduced strains must also be transmitted by a vector population that has been exposed to the existing pri...

  3. Factors that Affect the Physical Science Career Interest of Female Students: Testing Five Common Hypotheses

    ERIC Educational Resources Information Center

    Hazari, Zahra; Potvin, Geoff; Lock, Robynne M.; Lung, Florin; Sonnert, Gerhard; Sadler, Philip M.

    2013-01-01

    There are many hypotheses regarding factors that may encourage female students to pursue careers in the physical sciences. Using multivariate matching methods on national data drawn from the Persistence Research in Science and Engineering (PRiSE) project ("n" = 7505), we test the following five commonly held beliefs regarding what…

  4. PEPTIC ULCER DISEASE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Peptic ulcer disease (PUD) is an ulcerative condition of the stomach or duodenum that may be accompanied by mucosal inflammation. PUD is classified as primary when it occurs in healthy children and as secondary when underlying disorders associated with injury, illness, or drug therapy co-exists. Pri...

  5. Separation Of Metals Bonded With Two-Sided Tape

    NASA Technical Reports Server (NTRS)

    Kelly, Michael L.

    1993-01-01

    Procedure developed to separate, without pulling, bending, or prying, objects temporarily bonded together with two-sided tape. Ultrasonic cleaning in hot kerosene enables separation without damage. Procedure applicable in removal of protective backing from metals as received, or in removing temporary bonding tape from metal specimens.

  6. Inhibition of Cyclic Adenosine Monophosphate (cAMP)-response Element-binding Protein (CREB)-binding Protein (CBP)/β-Catenin Reduces Liver Fibrosis in Mice.

    PubMed

    Osawa, Yosuke; Oboki, Keisuke; Imamura, Jun; Kojika, Ekumi; Hayashi, Yukiko; Hishima, Tsunekazu; Saibara, Toshiji; Shibasaki, Futoshi; Kohara, Michinori; Kimura, Kiminori

    2015-11-01

    Wnt/β-catenin is involved in every aspect of embryonic development and in the pathogenesis of many human diseases, and is also implicated in organ fibrosis. However, the role of β-catenin-mediated signaling on liver fibrosis remains unclear. To explore this issue, the effects of PRI-724, a selective inhibitor of the cAMP-response element-binding protein-binding protein (CBP)/β-catenin interaction, on liver fibrosis were examined using carbon tetrachloride (CCl4)- or bile duct ligation (BDL)-induced mouse liver fibrosis models. Following repetitive CCl4 administrations, the nuclear translocation of β-catenin was observed only in the non-parenchymal cells in the liver. PRI-724 treatment reduced the fibrosis induced by CCl4 or BDL. C-82, an active form of PRI-724, inhibited the activation of isolated primary mouse quiescent hepatic stellate cells (HSCs) and promoted cell death in culture-activated HSCs. During the fibrosis resolution period, an increase in F4/80(+) CD11b(+) and Ly6C(low) CD11b(+) macrophages was induced by CCl4 and was sustained for two weeks thereafter, even after having stopped CCl4 treatment. PRI-724 accelerated the resolution of CCl4-induced liver fibrosis, and this was accompanied by increased matrix metalloproteinase (MMP)-9, MMP-2, and MMP-8 expression in intrahepatic leukocytes. In conclusion, targeting the CBP/β-catenin interaction may become a new therapeutic strategy in treating liver fibrosis. PMID:26870800

  7. Predicting the establishment and spread of plant disease from regulatory sampling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive plant diseases can have devastating consequences on the local plant populations, in both agricultural and natural landscapes. Knowledge of the spatial patterns of pathogen spread can be used to guide more time- and cost-effective disease management strategies. Based on disease dispersal pri...

  8. Adaptation of a Visual Readability Instrument to Multimedia Format.

    ERIC Educational Resources Information Center

    Vrasidas, Charalambos; Lantz, Chris

    This paper describes a study in which a Picture Readability Index (PRI) was used to investigate initial and extended perceptions of photographs. Readability criteria for evaluating instructional text seems to have been in place for a long time, yet instructional visuals like photographs and illustrations have typically been subject to no such…

  9. SEASONAL AND REGIONAL VARIATIONS OF PRIMARY AND SECONDARY ORGANIC AEROSOLS OVER THE CONTINENTAL UNITED STATES: OBSERVATION-BASED ESTIMATES AND MODEL EVALUATION

    EPA Science Inventory

    Due to the lack of an analytical technique for directly quantifying the atmospheric concentrations of primary (OCpri) and secondary (OCsec) organic carbon aerosols, different indirect methods have been developed to estimate their concentrations. In this stu...

  10. Exposure to ozone modulates human airway protease/antiprotease balance contributing to increased influenza A infection

    EPA Science Inventory

    Exposure to oxidant air pollution is associated with Increased respiratory morbiditses and susceptibility to Infections Ozone is a commonly encountered oxidant air pollutant, yet Its effects on influenza infections in humans are not known ‘the greater Mexico City area was the pri...

  11. Bioassessment Tools for Stony Corals: Field Testing of Monitoring Protocols in the US Virgin Islands (St. Croix)

    EPA Science Inventory

    Survey protocols for assessing coral reef condition were field tested at 61 reef stations in St. Croix, US Virgin Islands (USVI) during 2006. Three observations for stony corals were recorded: species, size, and percent live tissue. Stony corals were selected because they are pri...

  12. CORN FLAVOR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Corn is a large part of the modern diet through sweeteners, oil, processed foods, and animal-derived foods. In addition, corn is eaten directly in bread and cereal-type foods, snack foods, and foods made from masa flour. Corn gluten meal is a byproduct of grain processed by wet milling. Although pri...

  13. Production of bermudagrass for bio-fuels: effect of two genotypes on pyrolysis product yield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bermudagrass is the perennial grass used as forage for livestock and harvested as hay on 10 to 15 million acres in Southern United States. It has potential as an energy crop for the production of biofuels through the lignocellulosic conversion program. Coastal was released in 1943 and was the pri...

  14. Molecular Technique to Fingerprint Aspergillus flavus Causing Aflatoxin Contamination in Food

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A retrotransposon, AFLAV (A. flavus retrotransposon), has been recently characterized in A. flavus. Complete DNA sequence of 7784 bp containing the AFLAV has been submitted to GenBank (accession number AY485785). Multicopies of this transposon are dispersed in the chromosomes of A. flavus. PCR pri...

  15. Collaboration and Integration in Rural Development.

    ERIC Educational Resources Information Center

    Lassey, William R.; Hagood, Richard A.

    Reporting on a rural planning and development program that proposes to develop, install, and evaluate alternative models for more effective collaboration and integration of the complex bureaucracies with responsibility for rural regions, this paper describes "Partnership for Rural Improvement" (PRI). Focusing on 11 counties in northcentral and…

  16. Interactive effects of deficit irrigation, elevated temperature, and elevated [CO2] on peanut growth in low irrigation production settings

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improving crop water use (both agronomic and biological) is critical to most cropping areas around the world. The persistance of adverse climate conditions and predicted decreased availability of fresh water for crop production are the largest challenges to agriculture in the coming decades. Our pri...

  17. Cobalt(III) Protoporphyrin Activates the DGCR8 Protein and Can Compensate microRNA Processing Deficiency.

    PubMed

    Barr, Ian; Weitz, Sara H; Atkin, Talia; Hsu, PeiKen; Karayiorgou, Maria; Gogos, Joseph A; Weiss, Shimon; Guo, Feng

    2015-06-18

    Processing of microRNA primary transcripts (pri-miRNAs) is highly regulated and defects in the processing machinery play a key role in many human diseases. In 22q11.2 deletion syndrome (22q11.2DS), heterozygous deletion of DiGeorge critical region gene 8 (DGCR8) causes a processing deficiency, which contributes to abnormal brain development. The DGCR8 protein is the RNA-binding partner of Drosha RNase, both essential for processing canonical pri-miRNAs. To identify an agent that can compensate reduced DGCR8 expression, we screened for metalloporphyrins that can mimic the natural DGCR8 heme cofactor. We found that Co(III) protoporphyrin IX (PPIX) stably binds DGCR8 and activates it for pri-miRNA processing in vitro and in HeLa cells. Importantly, treating cultured Dgcr8(+/-) mouse neurons with Co(III)PPIX can compensate the pri-miRNA processing defects. Co(III)PPIX is effective at concentrations as low as 0.2 μM and is not degraded by heme degradation enzymes, making it useful as a research tool and a potential therapeutic. PMID:26091172

  18. DETECTION OF POLYMORPHISM USING CAPS AND DCAPS MARKERS IN TWO CHICKPEA GENOTYPES.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cleaved amplified polymorphic sequence (CAPS) and derived cleaved amplified polymorphic sequence markers (dCAPS) are sequence based and co-dominant markers. Primers were designed from the ends of bacterial artificial chromosome clones 4m10 and 15o9 as well as a partial sequence of aldolase using Pri...

  19. Diurnal and seasonal dynamics of canopy-level solar-induced chlorophyll fluorescence and spectral reflectance indices in a cornfield

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A collaborative field campaign was undertaken to examine the temporal dynamics of canopy-level solar-induced fluorescence (SIF) and the Photochemical Reflectance Index (PRI) in conjunction with photosynthetic light use efficiency (LUE) obtained from fluxes measured at an instrumented tower. We condu...

  20. 12 CFR 19.170 - Discovery depositions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... before the scheduled hearing date, except with permission of the administrative law judge for good cause... electronic sound recording device; (ii) Upon agreement of the parties, by any other method; or (iii) For good...) Involves unwarranted attempts to pry into a party's preparation for trial; or (4) Is being conducted in...

  1. Trends in experimental high-energy physics

    SciTech Connect

    Sanford, T.W.L.

    1982-06-01

    Data from a scan of papers in Physical Review Letters and Physical Review are used to demonstrate that American high-energy physicists show a pattern of accelerator and instrumentation usage characteristic of that expected from the logistic-substitution model of Marchetti and of Fischer and Pry.

  2. Vegetation index differencing for broad-scale assessment of productivity under prolonged drought and sequential high rainfall conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to evaluate large tracts of land with in a consistent manner using readily available moderate resolution satellite data is a highly valuable tool for land resource managers. Herein we present a multi-scale approach using remotely sensed imagery that holds the potential to effectively pri...

  3. Alternative splicing affects the subcellular localization of Drosha.

    PubMed

    Link, Steffen; Grund, Stefanie E; Diederichs, Sven

    2016-06-20

    The RNase III enzyme Drosha is a key factor in microRNA (miRNA) biogenesis and as such indispensable for cellular homeostasis and developmental processes. Together with its co-factor DGCR8, it converts the primary transcript (pri-miRNA) into the precursor hairpin (pre-miRNA) in the nucleus. While the middle and the C-terminal domain are crucial for pri-miRNA processing and DGCR8 binding, the function of the N-terminus remains cryptic. Different studies have linked this region to the subcellular localization of Drosha, stabilization and response to stress. In this study, we identify alternatively spliced Drosha transcripts that are devoid of a part of the arginine/serine-rich (RS-rich) domain and expressed in a large set of human cells. In contrast to their expected habitation, we find two isoforms also present in the cytoplasm, while the other two isoforms reside exclusively in the nucleus. Their processing activity for pri-miRNAs and the binding to co-factors remains unaltered. In multiple cell lines, the endogenous mRNA expression of the Drosha isoforms correlates with the localization of endogenous Drosha proteins. The pri-miRNA processing efficiency is not significantly different between groups of cells with or without cytoplasmic Drosha expression. In summary, we discovered novel isoforms of Drosha with differential subcellular localization pointing toward additional layers of complexity in the regulation of its activity. PMID:27185895

  4. Health Instruction Packages: Consumer--Birth Control.

    ERIC Educational Resources Information Center

    Pries, Rose Mary; And Others

    Designed for the general public, these three learning modules utilize text, illustrations, and exercises to describe various methods of birth control. The first module, "All about Contraception for the Teenage New Mother" by Rose Mary Pries, discusses the desirability of planned pregnancy and reviews the effectiveness and side effects of birth…

  5. Mexico: Democracy and the Future

    ERIC Educational Resources Information Center

    Bruhn, Kathleen

    2009-01-01

    During most of the twentieth century, Mexico was governed by one of the longest-ruling authoritarian parties in the contemporary world. Even as most Latin American countries democratized in the 1980s, Mexico remained under the control of the Institutional Revolutionary Party (PRI). It was not until the 2000 presidential election that a two-party…

  6. Extraction of pulse repetition intervals from sperm whale click trains for ocean acoustic data mining.

    PubMed

    Zaugg, Serge; van der Schaar, Mike; Houégnigan, Ludwig; André, Michel

    2013-02-01

    The analysis of acoustic data from the ocean is a valuable tool to study free ranging cetaceans and anthropogenic noise. Due to the typically large volume of acquired data, there is a demand for automated analysis techniques. Many cetaceans produce acoustic pulses (echolocation clicks) with a pulse repetition interval (PRI) remaining nearly constant over several pulses. Analyzing these pulse trains is challenging because they are often interleaved. This article presents an algorithm that estimates a pulse's PRI with respect to neighboring pulses. It includes a deinterleaving step that operates via a spectral dissimilarity metric. The sperm whale (SW) produces trains with PRIs between 0.5 and 2 s. As a validation, the algorithm was used for the PRI-based identification of SW click trains with data from the NEMO-ONDE observatory that contained other pulsed sounds, mainly from ship propellers. Separation of files containing SW clicks with a medium and high signal to noise ratio from files containing other pulsed sounds gave an area under the receiver operating characteristic curve value of 0.96. This study demonstrates that PRI can be used for the automated identification of SW clicks and that deinterleaving via spectral dissimilarity contributes to algorithm performance. PMID:23363108

  7. High-precision measurement of variations in calcium isotope ratios in urine by multiple collector inductively coupled plasma mass spectrometry

    USGS Publications Warehouse

    Morgan, J.L.L.; Gordon, G.W.; Arrua, R.C.; Skulan, J.L.; Anbar, A.D.; Bullen, T.D.

    2011-01-01

    We describe a new chemical separation method to isolate Ca from other matrix elements in biological samples, developed with the long-term goal of making high-precision measurement of natural stable Ca isotope variations a clinically applicable tool to assess bone mineral balance. A new two-column procedure utilizing HBr achieves the purity required to accurately and precisely measure two Ca isotope ratios (44Ca/42Ca and 44Ca/43Ca) on a Neptune multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS) in urine. Purification requirements for Sr, Ti, and K (Ca/Sr > 10000; Ca/Ti > 10000000; and Ca/K > 10) were determined by addition of these elements to Ca standards of known isotopic composition. Accuracy was determined by (1) comparing Ca isotope results for samples and standards to published data obtained using thermal ionization mass spectrometry (TIMS), (2) adding a Ca standard of known isotopic composition to a urine sample purified of Ca, and (3) analyzing mixtures of urine samples and standards in varying proportions. The accuracy and precision of δ44/42Ca measurements of purified samples containing 25 μg of Ca can be determined with typical errors less than ±0.2‰ (2σ).

  8. The Study of ( n,d) Reaction Cross Sections for Some Medium Weight Targets up to 30 MeV

    NASA Astrophysics Data System (ADS)

    Aydin, A.; Şahan, M.; Tel, E.; Şahan, H.; Uğur, F. A.

    2011-08-01

    In this study, neutron incident reaction cross sections for some medium target nuclei ( 44 Ca, 65 Cu, 54 Fe, 56 Fe, 57 Fe, 58 Ni, 60 Ni and 67 Zn) have been investigated for the ( n,d) reaction cross sections. These new calculations on the excitation functions of 44 Ca(n,d) 43 K, 65 Cu(n,d) 44 Ni, 54 Fe(n,d) 53 Mn, 56 Fe(n,d) 55 Mn, 57 Fe(n,d) 56 Mn, 58 Ni(n,d) 57 Co, 60 Ni(n,d) 59 Co and 67 Zn(n,d) 66 Cu reactions have been carried out up to 30 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The PEQ calculations involve the new evaluated the Geometry Dependent Hybrid model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. By using the new cross sections formulae for ( n,d) reactions developed by Aydin et al., the obtained results have been discussed and compared with the available experimental data taken from EXFOR database.

  9. Spectral determination of concentrations of functionally diverse pigments in increasingly complex arctic tundra canopies.

    PubMed

    Boelman, Natalie T; Magney, Troy S; Logan, Barry A; Griffin, Kevin L; Eitel, Jan U H; Greaves, Heather; Prager, Case M; Vierling, Lee A

    2016-09-01

    As the Arctic warms, tundra vegetation is becoming taller and more structurally complex, as tall deciduous shrubs become increasingly dominant. Emerging studies reveal that shrubs exhibit photosynthetic resource partitioning, akin to forests, that may need accounting for in the "big leaf" net ecosystem exchange models. We conducted a lab experiment on sun and shade leaves from S. pulchra shrubs to determine the influence of both constitutive (slowly changing bulk carotenoid and chlorophyll pools) and facultative (rapidly changing xanthophyll cycle) pigment pools on a suite of spectral vegetation indices, to devise a rapid means of estimating within canopy resource partitioning. We found that: (1) the PRI of dark-adapted shade leaves (PRIo) was double that of sun leaves, and that PRIo was sensitive to variation among sun and shade leaves in both xanthophyll cycle pool size (V + A + Z) (r (2) = 0.59) and Chla/b (r (2) = 0.64); (2) A corrected PRI (difference between dark and illuminated leaves, ΔPRI) was more sensitive to variation among sun and shade leaves in changes to the epoxidation state of their xanthophyll cycle pigments (dEPS) (r (2) = 0.78, RMSE = 0.007) compared to the uncorrected PRI of illuminated leaves (PRI) (r (2) = 0.34, RMSE = 0.02); and (3) the SR680 index was correlated with each of (V + A + Z), lutein, bulk carotenoids, (V + A + Z)/(Chla + b), and Chla/b (r (2) range = 0.52-0.69). We suggest that ΔPRI be employed as a proxy for facultative pigment dynamics, and the SR680 for the estimation of constitutive pigment pools. We contribute the first Arctic-specific information on disentangling PRI-pigment relationships, and offer insight into how spectral indices can assess resource partitioning within shrub tundra canopies. PMID:27193900

  10. Stable Ca Isotopes in Tamarix aphylla Tree Rings, Death Valley, California

    NASA Astrophysics Data System (ADS)

    Yang, W.; Depaolo, D. J.; Ingram, B. L.; Owens, T. L.

    2008-12-01

    As a dune stabilizer and windbreak, Tamarix aphylla is an exotic perennial and evergreen tree in Death Valley. Its tap roots can reach down to 30 m depth and sub-superficial side roots may reach 50 m horizontally. The species can store large amounts of water in its roots and undergoes high evapotranspiration. Since Tamarix aphylla is a perennial tree growing in desert environments and its roots reach deep to the water table, it could be a proxy for desert ecological and hydrologic systems through time. We measured Ca isotopes in the soluble fraction of 8 tree ring samples from a 50-year-old specimen growing on an alluvial fan in Death Valley near Furnace Creek. Previous studies (Yang et al, GCA 60, 1996) indicate that this tree's rings contain high sulfur concentrations (4-6% expressed as sulfate) with chemical composition of CaSO4 (0.15-0.62 H2O). The δ34S values of soluble sulfate increase from +13.5 to +18 permil VCDT from the core to the bark, which are interpreted as reflecting deeper sulfate sources as the tree grew. The δ13C variations of the tree-ring cellulose (-27.6 to -24.0 permil VPDB) reflect changes in the local precipitation and show that Tamarix aphylla undergoes C3 photosynthesis. The δ44Ca for the soluble sulfate Ca through the tree-ring section, which covers a time period from 1945 to 1993, have an average value -2.52 permil (-3.4 permil relative to seawater). Only small variations are observed, from -2.69 to -2.28; the highest value (for 1990) occurs near the end of an extended drought. These are the first measurements of tree rings, but the low δ44Ca values are consistent with previous measurements of beech roots and stems from a temperate forest (Page et al., Biogeochem. 88, 2008). In our case, the tree has only one Ca source, which is expected to be isotopically uniform and similar to both local rainfall and limestones (δ44Ca ~ -0.6 permil), and with the minimal vegetation and extensive deep root system it is unlikely that there is a

  11. MicroRNA Expression during Bovine Oocyte Maturation and Fertilization

    PubMed Central

    Gilchrist, Graham C.; Tscherner, Allison; Nalpathamkalam, Thomas; Merico, Daniele; LaMarre, Jonathan

    2016-01-01

    Successful fertilization and subsequent embryo development rely on complex molecular processes starting with the development of oocyte competence through maturation. MicroRNAs (miRNAs) are small non-coding RNA molecules that function as gene regulators in many biological systems, including the oocyte and embryo. In order to further explore the roles of miRNAs in oocyte maturation, we employed small RNA sequencing as a screening tool to identify and characterize miRNA populations present in pools of bovine germinal vesicle (GV) oocytes, metaphase II (MII) oocytes, and presumptive zygotes (PZ). Each stage contained a defined miRNA population, some of which showed stable expression while others showed progressive changes between stages that were subsequently confirmed by quantitative reverse transcription polymerase chain reaction (RT-PCR). Bta-miR-155, bta-miR-222, bta-miR-21, bta-let-7d, bta-let-7i, and bta-miR-190a were among the statistically significant differentially expressed miRNAs (p < 0.05). To determine whether changes in specific primary miRNA (pri-miRNA) transcripts were responsible for the observed miRNA changes, we evaluated pri-miR-155, -222 and let-7d expression. Pri-miR-155 and -222 were not detected in GV oocytes but pri-miR-155 was present in MII oocytes, indicating transcription during maturation. In contrast, levels of pri-let-7d decreased during maturation, suggesting that the observed increase in let-7d expression was likely due to processing of the primary transcript. This study demonstrates that both dynamic and stable populations of miRNAs are present in bovine oocytes and zygotes and extend previous studies supporting the importance of the small RNA landscape in the maturing bovine oocyte and early embryo. PMID:26999121

  12. Seasonal Changes in Remote Vegetation Indices and Net Photosynthesis of Japanese Larch Needles

    NASA Astrophysics Data System (ADS)

    Nishida, K.; Nakaji, T.; Oguma, H.; Fujinuma, Y.

    2004-12-01

    We investigated the seasonal pattern of four kinds of remote vegetation indices (NDVI, PRI, [(1/rRedEdge)-(1/rNIR)] and [(1/rGreen)-(1/rNIR)]) and their correlation to photosynthetic activity in the needle leaves of Japanese larch. In the 42-year-old larch forest (Tomakomai, Japan), the diurnal courses of spectral reflectance and gas exchange rates of larch needles were periodically investigated during early June to late October in 2003. In the Tomakomai larch forest, expansion of short-shoot needles was started from mid-May, and yellow color change of the needle leaves was observed in late October. The seasonal pattern of index value differed among the vegetation indices. For example, daytime mean NDVI showed constant value from late June to early October. The [(1/rRedEdge)-(1/rNIR)] and PRI were increased during summer, and their peak were observed in July and August, respectively. Although the values of NDVI, PRI and [(1/rRedEdge)-(1/rNIR)] were depressed in late October with autumn senescence of the needles, the [(1/rGreen)-(1/rNIR)] in larch needles was not changed even in yellow colored needles. Consequently, correlation of these vegetation indices and seasonal changed photosynthetic parameters such as net photosynthetic rate (Pn) and photosynthetic light use efficiency (LUE) also differed among the indices. Although the PRI, NDVI and [(1/rRedEdge)-(1/rNIR)] positively correlated with daily maximum Pn and daily means of Pn and LUE, no correlation was found between [(1/rGreen)-(1/rNIR)] and the measured photosynthetic parameters. Based on the results of Pearson_fs correlation test, PRI and [(1/rRedEdge)-(1/rNIR)] were considered to be most useful index for the estimations of seasonal changes in Pn and LUE, respectively.

  13. MicroRNA Expression during Bovine Oocyte Maturation and Fertilization.

    PubMed

    Gilchrist, Graham C; Tscherner, Allison; Nalpathamkalam, Thomas; Merico, Daniele; LaMarre, Jonathan

    2016-01-01

    Successful fertilization and subsequent embryo development rely on complex molecular processes starting with the development of oocyte competence through maturation. MicroRNAs (miRNAs) are small non-coding RNA molecules that function as gene regulators in many biological systems, including the oocyte and embryo. In order to further explore the roles of miRNAs in oocyte maturation, we employed small RNA sequencing as a screening tool to identify and characterize miRNA populations present in pools of bovine germinal vesicle (GV) oocytes, metaphase II (MII) oocytes, and presumptive zygotes (PZ). Each stage contained a defined miRNA population, some of which showed stable expression while others showed progressive changes between stages that were subsequently confirmed by quantitative reverse transcription polymerase chain reaction (RT-PCR). Bta-miR-155, bta-miR-222, bta-miR-21, bta-let-7d, bta-let-7i, and bta-miR-190a were among the statistically significant differentially expressed miRNAs (p < 0.05). To determine whether changes in specific primary miRNA (pri-miRNA) transcripts were responsible for the observed miRNA changes, we evaluated pri-miR-155, -222 and let-7d expression. Pri-miR-155 and -222 were not detected in GV oocytes but pri-miR-155 was present in MII oocytes, indicating transcription during maturation. In contrast, levels of pri-let-7d decreased during maturation, suggesting that the observed increase in let-7d expression was likely due to processing of the primary transcript. This study demonstrates that both dynamic and stable populations of miRNAs are present in bovine oocytes and zygotes and extend previous studies supporting the importance of the small RNA landscape in the maturing bovine oocyte and early embryo. PMID:26999121

  14. Overexpression of NF90-NF45 Represses Myogenic MicroRNA Biogenesis, Resulting in Development of Skeletal Muscle Atrophy and Centronuclear Muscle Fibers

    PubMed Central

    Todaka, Hiroshi; Higuchi, Takuma; Yagyu, Ken-ichi; Sugiyama, Yasunori; Yamaguchi, Fumika; Morisawa, Keiko; Ono, Masafumi; Fukushima, Atsuki; Tsuda, Masayuki; Taniguchi, Taketoshi

    2015-01-01

    MicroRNAs (miRNAs) are involved in the progression and suppression of various diseases through translational inhibition of target mRNAs. Therefore, the alteration of miRNA biogenesis induces several diseases. The nuclear factor 90 (NF90)-NF45 complex is known as a negative regulator in miRNA biogenesis. Here, we showed that NF90-NF45 double-transgenic (dbTg) mice develop skeletal muscle atrophy and centronuclear muscle fibers in adulthood. Subsequently, we found that the levels of myogenic miRNAs, including miRNA 133a (miR-133a), which promote muscle maturation, were significantly decreased in the skeletal muscle of NF90-NF45 dbTg mice compared with those in wild-type mice. However, levels of primary transcripts of the miRNAs (pri-miRNAs) were clearly elevated in NF90-NF45 dbTg mice. This result indicated that the NF90-NF45 complex suppressed miRNA production through inhibition of pri-miRNA processing. This finding was supported by the fact that processing of pri-miRNA 133a-1 (pri-miR-133a-1) was inhibited via binding of NF90-NF45 to the pri-miRNA. Finally, the level of dynamin 2, a causative gene of centronuclear myopathy and concomitantly a target of miR-133a, was elevated in the skeletal muscle of NF90-NF45 dbTg mice. Taken together, we conclude that the NF90-NF45 complex induces centronuclear myopathy through increased dynamin 2 expression by an NF90-NF45-induced reduction of miR-133a expression in vivo. PMID:25918244

  15. Seasonal photosynthetic activity in evergreen conifer leaves monitored with spectral reflectance

    NASA Astrophysics Data System (ADS)

    Wong, C. Y.; Gamon, J. A.

    2013-12-01

    Boreal evergreen conifers must maintain photosynthetic systems in environments where temperatures vary greatly across seasons from high temperatures in the summer to freezing levels in the winter. This involves seasonal downregulation and photoprotection during periods of extreme temperatures. To better understand this downregulation, seasonal dynamics of photosynthesis of lodgepole (Pinus contorta D.) and ponderosa pine (Pinus ponderosa D.) were monitored in Edmonton, Canada over two years. Spectral reflectance at the leaf and stand scales was measured weekly and the Photochemical Reflectance Index (PRI), often used as a proxy for chlorophyll and carotenoid pigment levels and photosynthetic light-use efficiency (LUE), was used to track the seasonal dynamics of photosynthetic activity. Additional physiological measurements included leaf pigment content, chlorophyll fluorescence, and gas exchange. All the metrics indicate large seasonal changes in photosynthetic activity, with a sharp transition from winter downregulation to active photosynthesis in the spring and a more gradual fall transition into winter. The PRI was a good indicator of several other variables including seasonally changing photosynthetic activity, chlorophyll fluorescence, photosynthetic LUE, and pigment pool sizes. Over the two-year cycle, PRI was primarily driven by changes in constitutive (chlorophyll:carotenoid) pigment levels correlated with seasonal photosynthetic activity, with a much smaller variation caused by diurnal changes in xanthophyll cycle activity (conversion between violaxanthin & zeaxanthin). Leaf and canopy scale PRI measurements exhibited parallel responses during the winter-spring transition. Together, our findings indicate that evergreen conifers photosynthetic system possesses a remarkable degree of resilience in response to large temperature changes across seasons, and that optical remote sensing can be used to observe the seasonal effects on photosynthesis and

  16. On the Use of Leaf Spectral Indices to Assess Water Status and Photosynthetic Limitations in Olea europaea L. during Water-Stress and Recovery

    PubMed Central

    Sun, Pengsen; Wahbi, Said; Tsonev, Tsonko; Haworth, Matthew; Liu, Shirong; Centritto, Mauro

    2014-01-01

    Diffusional limitations to photosynthesis, relative water content (RWC), pigment concentrations and their association with reflectance indices were studied in olive (Olea europaea) saplings subjected to water-stress and re-watering. RWC decreased sharply as drought progressed. Following rewatering, RWC gradually increased to pre-stress values. Photosynthesis (A), stomatal conductance (gs), mesophyll conductance (gm), total conductance (gt), photochemical reflectance index (PRI), water index (WI) and relative depth index (RDI) closely followed RWC. In contrast, carotenoid concentration, the carotenoid to chlorophyll ratio, water content reflectance index (WCRI) and structural independent pigment index (SIPI) showed an opposite trend to that of RWC. Photosynthesis scaled linearly with leaf conductance to CO2; however, A measured under non-photorespiratory conditions (A1%O2) was approximately two times greater than A measured at 21% [O2], indicating that photorespiration likely increased in response to drought. A1%O2 also significantly correlated with leaf conductance parameters. These relationships were apparent in saturation type curves, indicating that under non-photorespiratory conditions, CO2 conductance was not the major limitations to A. PRI was significant correlated with RWC. PRI was also very sensitive to pigment concentrations and photosynthesis, and significantly tracked all CO2 conductance parameters. WI, RDI and WCRI were all significantly correlated with RWC, and most notably to leaf transpiration. Overall, PRI correlated more closely with carotenoid concentration than SIPI; whereas WI tracked leaf transpiration more effectively than RDI and WCRI. This study clearly demonstrates that PRI and WI can be used for the fast detection of physiological traits of olive trees subjected to water-stress. PMID:25136798

  17. The estrogen receptor-α-induced microRNA signature regulates itself and its transcriptional response

    PubMed Central

    Castellano, Leandro; Giamas, Georgios; Jacob, Jimmy; Coombes, R. Charles; Lucchesi, Walter; Thiruchelvam, Paul; Barton, Geraint; Jiao, Long R.; Wait, Robin; Waxman, Jonathan; Hannon, Gregory J.; Stebbing, Justin

    2009-01-01

    Following estrogenic activation, the estrogen receptor-α (ERα) directly regulates the transcription of target genes via DNA binding. MicroRNAs (miRNAs) modulated by ERα have the potential to fine tune these regulatory systems and also provide an alternate mechanism that could impact on estrogen-dependent developmental and pathological systems. Through a microarray approach, we identify the subset of microRNAs (miRNAs) modulated by ERα, which include upregulation of miRNAs derived from the processing of the paralogous primary transcripts (pri-) mir-17–92 and mir-106a-363. Characterization of the mir-17–92 locus confirms that the ERα target protein c-MYC binds its promoter in an estrogen-dependent manner. We observe that levels of pri-mir-17–92 increase earlier than the mature miRNAs derived from it, implicating precursor cleavage modulation after transcription. Pri-mir-17–92 is immediately cleaved by DROSHA to pre-miR-18a, indicating that its regulation occurs during the formation of the mature molecule from the precursor. The clinical implications of this novel regulatory system were confirmed by demonstrating that pre-miR-18a was significantly upregulated in ERα-positive compared to ERα-negative breast cancers. Mechanistically, miRNAs derived from these paralogous pri-miRNAs (miR-18a, miR-19b, and miR-20b) target and downregulate ERα, while a subset of pri-miRNA-derived miRNAs inhibit protein translation of the ERα transcriptional p160 coactivator, AIB1. Therefore, different subsets of miRNAs identified act as part of a negative autoregulatory feedback loop. We propose that ERα, c-MYC, and miRNA transcriptional programs invoke a sophisticated network of interactions able to provide the wide range of coordinated cellular responses to estrogen. PMID:19706389

  18. 89 Zr(n, γ) from a surrogate reaction approach

    NASA Astrophysics Data System (ADS)

    Ota, Shuya; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I.; Austin, R. A. E.; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Benstead, J.; Ross, T.

    2014-09-01

    While recent studies have demonstrated the validity of the surrogate reaction approach for studying fission cross sections of short-lived actinides, its applicability for (n, γ) is still under investigation. We studied the γ-decay of 90Zr produced by 91Zr(p,d) in order to infer the 89Zr(n, γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 30-60° with the STARS (Silicon Telescope Array for Reaction Studies) array of three segmented Micron S2 silicon detectors. Compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the LiTeR (Livermore Texas Richmond) array of five Compton-suppressed HPGe clovers. We will present results of γ-emission probabilities of 89Zr(n, γ) and some theoretical discussions. While recent studies have demonstrated the validity of the surrogate reaction approach for studying fission cross sections of short-lived actinides, its applicability for (n, γ) is still under investigation. We studied the γ-decay of 90Zr produced by 91Zr(p,d) in order to infer the 89Zr(n, γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 30-60° with the STARS (Silicon Telescope Array for Reaction Studies) array of three segmented Micron S2 silicon detectors. Compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the LiTeR (Livermore Texas Richmond) array of five Compton-suppressed HPGe clovers. We will present results of γ-emission probabilities of 89Zr(n, γ) and some theoretical discussions. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory

  19. Multi-parameter assessment of platelet inhibition and its stability during aspirin and clopidogrel therapy

    PubMed Central

    Timur, A. Anil; Murugesan, Gurunathan; Zhang, Li; Barnard, John; Bhatt, Deepak L.; Kottke-Marchant, Kandice

    2014-01-01

    Introduction Poor response to antiplatelet drugs is associated with adverse outcomes. We assessed platelet inhibition and its stability and tested correlation and agreement between platelet function assays. Methods Peripheral blood from 58 patients on both aspirin and clopidogrel who underwent percutaneous coronary intervention (PCI) was collected at hospital discharge (visit-1) and at 30–90 days (visit-2). Platelet function was measured using light transmission aggregometry (LTA-AA and LTA-ADP), VerifyNow (Aspirin; ARU and P2Y12; PRU), ex vivo TxB2, urinary 11dhTxB2, and VASP (PRI) assays. Data were analyzed as continuous, quartiles and binary. Patients were defined as aspirin poor responder (PR) with ARU ≥550, LTA-AA maximum ≥20%, TxB2 ≥1 ng/mL or 11dhTxB2 ≥1,500 pg/mg of creatinine and as clopidogrel PR with PRU ≥240, PRU ≥208, LTA-ADP maximum ≥40%, PRI ≥50%, or PRI ≥66%. Results Aspirin PR was 3–33% and clopidogrel PR was 10–35% in visit-1. LTA-AA, 11dhTxB2, and all clopidogrel-response measures showed correlation and agreement between visit-1 and visit-2. The highest agreement between two visits was revealed by PRU ≥240 and PRI ≥66% (PRU-κ=0.7, 95% CI=0.47, 0.93; PRI-κ=0.69, 95% CI=0.42, 0.95, p-values<0.001). Comparison of platelet function assays in a single visit (Visit-1) revealed a poor correlation between LTA-AA and 11dhTxB2 assays and no agreement among aspirin-response assays. The highest correlation and agreement were obtained between VerifyNow P2Y12 and VASP assays (rho=0.7, p-value<0.001 and PRU ≥208-PRI-κ=0.41–0.42, 95% CI=0.13, 0.69, p-values<0.001). Conclusions Platelet inhibition is stable during aspirin and clopidogrel treatment. Clopidogrel-response assays correlate and agree with each other better than aspirin-response assays. PMID:24852729

  20. Effects of resource availability on plant reflectance and physiology

    NASA Astrophysics Data System (ADS)

    Stylinski, Cathlyn Davis

    Remote sensing is an important means of examining net CO2 exchange between terrestrial ecosystems and the atmosphere and the effects of elevated [CO2] on plant productivity at multiple spatial and temporal scales. In particular, indices derived from narrow-waveband reflectance that are sensitive to dynamic physiological attributes may reveal periods of photosynthetic downregulation and may improve plant productivity models. Here we examined the relationship between photosynthesis, photoprotective xanthophyll cycle pigments, and the Photochemical Reflectance Index (PRI) for mature woody Mediterranean plants under two conditions: natural drought and exposure to atmospheric CO2 enrichment. We also examined plants under severe water stress to test and compare the effects of physiology and structure on PRI, the Normalized Difference Vegetation Index (NDVI), and the Water Band Index (WBI). PRI varied primarily with leaf physiology, and NDVI primarily with stand structure. WBI was affected by both attributes and, unlike PRI, did not scale well from leaves to whole stands. PRI was well linked to photoprotective xanthophyll cycle pigments and electron transport. Both PRI and these pigments varied with seasonal changes in midday photosynthesis, demonstrating that the xanthophyll cycle is an important form of photoprotection for evergreen Mediterranean species undergoing photosynthetic downregulation. By contrast, NDVI was not sensitive to physiological changes but was well correlated with green canopy cover. These results suggest that the "big-leaf hypothesis" (which states that canopies can be characterized by a single reference leaf) cannot be applied to all physiological indices. Furthermore, in agreement with the "functional convergence hypothesis" (which states that plant physiology and structure change to match CO2 fixation capacity), our results indicate a coordinated regulation of photosystem two activity and carbon uptake. However, they also demonstrate that this

  1. A typology of pain coping strategies in pediatric patients with chronic abdominal pain.

    PubMed

    Walker, Lynn S; Baber, Kari Freeman; Garber, Judy; Smith, Craig A

    2008-07-15

    This study aimed to identify clinically meaningful profiles of pain coping strategies used by youth with chronic abdominal pain (CAP). Participants (n=699) were pediatric patients (ages 8-18 years) and their parents. Patients completed the Pain Response Inventory (PRI) and measures of somatic and depressive symptoms, disability, pain severity and pain efficacy, and perceived competence. Parents rated their children's pain severity and coping efficacy. Hierarchical cluster analysis based on the 13 PRI subscales identified pain coping profiles in Sample 1 (n=311) that replicated in Sample 2 (n=388). Evidence was found of external validity and distinctiveness of the profiles. The findings support a typology of pain coping that reflects the quality of patients' pain mastery efforts and interpersonal relationships associated with pain coping. Results are discussed in relation to developmental processes, attachment styles, and treatment implications. PMID:17928144

  2. Symmetry relations in the generalized Lorenz-Mie theory for lossless negative refractive index media

    NASA Astrophysics Data System (ADS)

    André Ambrosio, Leonardo

    2016-09-01

    In this paper we present a theoretical analysis of the generalized Lorenz-Mie theory for negative refractive index (NRI) media and spherical scatterers, extending the well-known concepts and definitions found in the literature involving dielectric or positive refractive index (PRI) particles. The consequences of a negative phase velocity and an anti-parallelism of the wave vector with respect to the Poynting vector are investigated and interpreted in this framework and, together with the symmetries found for the beam-shape coefficients when compared to the conventional PRI case, it is shown that the description of plane waves, Gaussian beams and, more generally, on-axis azimuthally symmetric waves along a NRI medium, their fields and all physical properties can be conveniently correlated with that of dielectric media once the electromagnetic response functions are replaced by their corresponding dielectric counterparts.

  3. Methylation by NSun2 Represses the Levels and Function of MicroRNA 125b

    PubMed Central

    Yuan, Shuai; Tang, Hao; Xing, Junyue; Fan, Xiuqin; Cai, Xiaoyu; Li, Qiu; Han, Pei; Luo, Yuhong; Zhang, Zhuojun; Jiang, Bin; Dou, Yali; Gorospe, Myriam

    2014-01-01

    Methylation is a prevalent posttranscriptional modification of RNAs. However, whether mammalian microRNAs are methylated is unknown. Here, we show that the tRNA methyltransferase NSun2 methylates primary (pri-miR-125b), precursor (pre-miR-125b), and mature microRNA 125b (miR-125b) in vitro and in vivo. Methylation by NSun2 inhibits the processing of pri-miR-125b2 into pre-miR-125b2, decreases the cleavage of pre-miR-125b2 into miR-125, and attenuates the recruitment of RISC by miR-125, thereby repressing the function of miR-125b in silencing gene expression. Our results highlight the impact of miR-125b function via methylation by NSun2. PMID:25047833

  4. small ORFs: A new class of essential genes for development.

    PubMed

    Albuquerque, João Paulo; Tobias-Santos, Vitória; Rodrigues, Aline Cáceres; Mury, Flávia Borges; da Fonseca, Rodrigo Nunes

    2015-01-01

    Genes that contain small open reading frames (smORFs) constitute a new group of eukaryotic genes and are expected to represent 5% of the Drosophila melanogaster transcribed genes. In this review we provide a historical perspective of their recent discovery, describe their general mechanism and discuss the importance of smORFs for future genomic and transcriptomic studies. Finally, we discuss the biological role of the most studied smORF so far, the Mlpt/Pri/Tal gene in arthropods. The pleiotropic action of Mlpt/Pri/Tal in D. melanogaster suggests a complex evolutionary scenario that can be used to understand the origins, evolution and integration of smORFs into complex gene regulatory networks. PMID:26500431

  5. small ORFs: A new class of essential genes for development

    PubMed Central

    Albuquerque, João Paulo; Tobias-Santos, Vitória; Rodrigues, Aline Cáceres; Mury, Flávia Borges; da Fonseca, Rodrigo Nunes

    2015-01-01

    Genes that contain small open reading frames (smORFs) constitute a new group of eukaryotic genes and are expected to represent 5% of the Drosophila melanogaster transcribed genes. In this review we provide a historical perspective of their recent discovery, describe their general mechanism and discuss the importance of smORFs for future genomic and transcriptomic studies. Finally, we discuss the biological role of the most studied smORF so far, the Mlpt/Pri/Tal gene in arthropods. The pleiotropic action of Mlpt/Pri/Tal in D. melanogaster suggests a complex evolutionary scenario that can be used to understand the origins, evolution and integration of smORFs into complex gene regulatory networks. PMID:26500431

  6. Two Fundamental Principles of Nature's Interactions

    NASA Astrophysics Data System (ADS)

    Ma, Tian; Wang, Shouhong

    2014-03-01

    In this talk, we present two fundamental principles of nature's interactions, the principle of interaction dynamics (PID) and the principle of representation invariance (PRI). Intuitively, PID takes the variation of the action functional under energy-momentum conservation constraint. PID offers a completely different and natural way of introducing Higgs fields. PRI requires that physical laws be independent of representations of the gauge groups. These two principles give rise to a unified field model for four interactions, which can be naturally decoupled to study individual interactions. With these two principles, we are able to derive 1) a unified theory for dark matter and dark energy, 2) layered strong and weak interaction potentials, and 3) the energy levels of subatomic particles. Supported in part by NSF, ONR and Chinese NSF.

  7. Magneto-optic imaging inspection of selected corrosion specimens

    NASA Astrophysics Data System (ADS)

    Bobo, Stephen N.

    1992-07-01

    A feasibility demonstration was conducted at the facilities of Physical Research Instrumentation Company (PRI) in Redmond, Washington. The purpose of the demonstration was to compare the effectiveness of the PRI Model 301-1 magneto-optic imaging (MOI) system with conventional eddy current methods of detecting corrosion in aircraft test panels, previously identified by eddy current scanning. The study indicated that MOI may not be able to detect gradual differences in thinning that are less than 10 percent of base metal thickness. Also, with MOI, it appears to be more difficult to provide quantitative estimates of residual thickness than is the case with eddy current scanning. On the other hand, MOI visualization of the extent of corrosion is simple and free of the labor intensive point-by-point mapping, which is required by eddy current scanning.

  8. The preparation and calibration of calcium synthetic isotope mixtures

    NASA Astrophysics Data System (ADS)

    Berglund, M.; Hennessy, C.; Richter, S.; Fortunato, G.; Wunderli, S.

    2010-12-01

    Calcium is one of the most-abundant elements but still there is no calibrated measurement of its isotopic composition. In this work a set of six mixtures were gravimetrically prepared from highly enriched calcium isotopes. The purification of the enriched calcium material was done by vacuum distillation. Solutions of the now highly enriched metallic 40Ca, 42Ca, 44Ca and 48Ca where prepared in an inert atmosphere. Mixtures were then made gravimetrically with the isotope ratios in Table 1. The measurements of the mixtures were done by a total evaporation method for isotopic analysis by multi-collector thermal ionization mass spectrometry (TIMS). This work describes the preparation, measurement and the calibrated results of the mixtures and mother solutions.Table 1: Isotope ratios of calcium isotope mixtures

  9. Developing a Clinically Useful Calcium Isotope Biomarker

    NASA Technical Reports Server (NTRS)

    Romaniello, Stephen J.; Anbar, Ariel D.; Gordon, Gwyneth W.; Skulan, Joseph L.; Smith, Scott M.; Zwart, Sara R.; Monge, Jorge; Fonseca, Rafael

    2016-01-01

    Naturally-occurring Ca is mixture of six isotopes Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48). Biological reaction rates and equilibrium constants depend slightly, but measurably, on atomic mass, causing the relative abundances of Ca isotopes to vary between different tissues. During bone formation, light isotopes of Ca are preferentially incorporated into bone, leaving soft tissue depleted in light isotopes. In contrast, bone resorption exhibits no isotopic preference, and thus transfers the light isotope signature of bone back to soft tissue. This balance makes the Ca isotope composition of soft tissue (e.g. serum, urine) a highly sensitive, quantitative tracer for whole-body bone mineral balance (BMB).

  10. Isospin Mixing in 80Zr: From Finite to Zero Temperature

    NASA Astrophysics Data System (ADS)

    Ceruti, S.; Camera, F.; Bracco, A.; Avigo, R.; Benzoni, G.; Blasi, N.; Bocchi, G.; Bottoni, S.; Brambilla, S.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Mentana, A.; Million, B.; Morales, A. I.; Nicolini, R.; Pellegri, L.; Pullia, A.; Riboldi, S.; Wieland, O.; Birkenbach, B.; Bazzacco, D.; Ciemala, M.; Désesquelles, P.; Eberth, J.; Farnea, E.; Görgen, A.; Gottardo, A.; Hess, H.; Judson, D. S.; Jungclaus, A.; Kmiecik, M.; Korten, W.; Maj, A.; Menegazzo, R.; Mengoni, D.; Michelagnoli, C.; Modamio, V.; Montanari, D.; Myalski, S.; Napoli, D.; Quintana, B.; Reiter, P.; Recchia, F.; Rosso, D.; Sahin, E.; Salsac, M. D.; Söderström, P.-A.; Stezowski, O.; Theisen, Ch.; Ur, C.; Valiente-Dobón, J. J.; Zieblinski, M.

    2015-11-01

    The isospin mixing was deduced in the compound nucleus 80Zr at an excitation energy of E*=54 MeV from the γ decay of the giant dipole resonance. The reaction 40Ca + 40Ca at Ebeam=136 MeV was used to form the compound nucleus in the isospin I =0 channel, while the reaction 37Cl + 44Ca at Ebeam=95 MeV was used as the reference reaction. The γ rays were detected with the AGATA demonstrator array coupled with LaBr3 :Ce detectors. The temperature dependence of the isospin mixing was obtained and the zero-temperature value deduced. The isospin-symmetry-breaking correction δC used for the Fermi superallowed transitions was extracted and found to be consistent with β -decay data.

  11. Calcium isotope separation by chemical exchange with polymer-bound crown compounds

    SciTech Connect

    Jepson, B.E.

    1990-01-01

    Chromatographic separation of calcium isotopes by chemical exchange with polymer-bound 18-crown-6 was investigated. The breakthrough technique of column chromatography was employed to determine the influence of solvent composition and ligand-tether structure on separation coefficients and heterogeneous calcium complex stability. The separation coefficient, {epsilon}, was found to be strongly dependent upon solvent composition. An {epsilon} of 0. 0025{plus minus}0.0002 (95% C.L.) for the {sup 44}Ca/{sup 40}Ca isotope pair was obtained with a 70/30 (by volume) methanol/chloroform solvent mixture at 20.0{degree}C. Differences in the structure of the tether binding the crown ring to the polymer had no influence on {epsilon} at that solvent composition. 8 refs., 5 figs., 1 tab.

  12. Microstructural probing of ferritic/martensitic steels using internal transmutation-based positron source

    NASA Astrophysics Data System (ADS)

    Krsjak, Vladimir; Dai, Yong

    2015-10-01

    This paper presents the use of an internal 44Ti/44Sc radioisotope source for a direct microstructural characterization of ferritic/martensitic (f/m) steels after irradiation in targets of spallation neutron sources. Gamma spectroscopy measurements show a production of ∼1MBq of 44Ti per 1 g of f/m steels irradiated at 1 dpa (displaced per atom) in the mixed proton-neutron spectrum at the Swiss spallation neutron source (SINQ). In the decay chain 44Ti → 44Sc → 44Ca, positrons are produced together with prompt gamma rays which enable the application of different positron annihilation spectroscopy (PAS) analyses, including lifetime and Doppler broadening spectroscopy. Due to the high production yield, long half-life and relatively high energy of positrons of 44Ti, this methodology opens up new potential for simple, effective and inexpensive characterization of radiation induced defects in f/m steels irradiated in a spallation target.

  13. Experimental identification of mechanisms controlling calcium isotopic fractionations by the vegetation.

    NASA Astrophysics Data System (ADS)

    Cobert, Florian; Schimtt, Anne-Désirée.; Bourgeade, Pascale; Stille, Peter; Chabaux, François; Badot, Pierre-Marie; Jaegler, Thomas

    2010-05-01

    This study aims to better understand the role of vegetation on the Ca cycle at the level of the critical zone of the Earth, in order to specify the mechanisms controlling the Ca absorption by plants at the rock/plant interface. To do this, we performed experiments using hydroponic plant cultures in a way that we could control the co-occuring geochemical and physiological process and determine the impact of the nutritive solution on the Ca cycle within plants. A dicotyledon and calcicole plant with rapid growth, the French bean (Phaseolus vulgaris L.), has been chosen to have access to one complete growth cycle. Several experiments have been conducted with two Ca concentrations, 6 (L) and 60 (H) ppm and two pH values (4 and 6) in the nutritive solution, for which the Ca concentration was maintained constant, so its Ca content is considered as infinite. A second experiment (non infinite L6) allowed Ca depletion in the solution through time; therefore, response effects on the Ca isotopic signatures in the plant organs and in the nutritive solution were observed. We determined Ca concentrations and isotopic ratios in the nutritive solution and in different organs (main roots, secondary roots, old and young stems, old and young leaves and fruits) at two different growth stages (10 days and 6 weeks). Preliminary results show that: (1) the roots (main and secondary) were enriched in the light isotope (40Ca) compared to the nutritive solution, and leaves were enriched in the heavy isotope (44Ca) compared to stems. These results are in accord with previously published field studies (Wigand et al., 2005; Page et al., 2008; Cenki-Tok et al., 2009; Holmden and Bélanger, 2010). Leaves and secondary roots were however enriched in the heavy isotope (44Ca) compared to bean pods, stems and main roots. These results could be related to kinetic fractionation processes occurring either during the Ca root uptake, or during the Ca transport within the plant, or physiological mechanisms

  14. Cross section measurements via residual nuclear decays: Analysis methods

    SciTech Connect

    Zhou Fengqun; Gao Lei; Li Kuohu; Song Yueli; Zhang Fang; Kong Xiangzhong; Luo Junhua

    2009-11-15

    We develop an approach to calculating the pure cross section of the ground state of artificial radioactive nuclides that subtracts the effect of an excited state on the ground state. We apply a formalism to obtaining pure cross sections by subtracting the effect of excited states in the reactions {sup 122}Te(n,2n){sup 121}Te{sup g} and {sup 128}Te(n,2n){sup 127}Te{sup g}, induced by neutrons of about 14 MeV. The cross sections are measured by an activation relative to the {sup 93}Nb(n,2n){sup 92}Nb{sup m} reaction and are compared with results that take into account the effect of the excited state. Measurements are carried out by {gamma} detection using a coaxial high-purity germanium (HPGe) detector. As samples, spectroscopically pure Te powder is used. The fast neutrons are produced by the {sup 3}H(d,n){sup 4}He reaction. The neutron energies in these measurements are determined using the method of cross-section ratios between the {sup 90}Zr(n,2n){sup 89}Zr{sup m+g} and {sup 93}Nb(n,2n){sup 92}Nb{sup m} reactions.

  15. Towards a Microscopic Reaction Description Based on Energy Density Functionals

    SciTech Connect

    Nobre, G A; DIetrich, F S; Escher, J E; Thompson, I J; Dupuis, M; Terasaki, J; Engel, J

    2011-09-26

    A microscopic calculation of reaction cross sections for nucleon-nucleus scattering has been performed by explicitly coupling the elastic channel to all particle-hole excitations in the target and one-nucleon pickup channels. The particle-hole states may be regarded as doorway states through which the flux flows to more complicated configurations, and subsequently to long-lived compound nucleus resonances. Target excitations for {sup 40,48}Ca, {sup 58}Ni, {sup 90}Zr and {sup 144}Sm were described in a random-phase framework using a Skyrme functional. Reaction cross sections obtained agree very well with experimental data and predictions of a state-of-the-art fitted optical potential. Couplings between inelastic states were found to be negligible, while the pickup channels contribute significantly. The effect of resonances from higher-order channels was assessed. Elastic angular distributions were also calculated within the same method, achieving good agreement with experimental data. For the first time observed absorptions are completely accounted for by explicit channel coupling, for incident energies between 10 and 70 MeV, with consistent angular distribution results.

  16. Accelerator mass spectrometry of strontium-90 for homeland security, environmental monitoring and human health

    NASA Astrophysics Data System (ADS)

    Tumey, Scott J.; Brown, Thomas A.; Hamilton, Terry E.; Hillegonds, Darren J.

    2008-05-01

    Strontium-90 is one of the most hazardous materials managed by agencies charged with protecting the public from radiation. Traditional radiometric methods have been limited by low sample throughput and slow turnaround times. Mass spectrometry offers the advantage of shorter analysis times and the ability to measure samples immediately after processing, however conventional mass spectrometric techniques are susceptible to molecular isobaric interferences that limit their overall sensitivity. In contrast, accelerator mass spectrometry is insensitive to molecular interferences and we have therefore begun developing a method for determination of 90Sr by accelerator mass spectrometry. Despite a pervasive interference from 90Zr, our initial development has yielded an instrumental background of ∼108 atoms (75 mBq) per sample. Further refinement of our system (e.g. redesign of our detector, use of alternative target materials) is expected to push the background below 106 atoms, close to the theoretical limit for AMS. Once we have refined our system and developed suitable sample preparation protocols, we will utilize our capability in applications to homeland security, environmental monitoring and human health.

  17. Examination of the surrogate ratio method for the determination of the 93Zr(n ,γ )94Zr cross section with Zr,9290(18O,16O)Zr,9492 reactions

    NASA Astrophysics Data System (ADS)

    Yan, S. Q.; Li, Z. H.; Wang, Y. B.; Nishio, K.; Makii, H.; Su, J.; Li, Y. J.; Nishinaka, I.; Hirose, K.; Han, Y. L.; Orlandi, R.; Shen, Y. P.; Guo, B.; Zeng, S.; Lian, G.; Chen, Y. S.; Bai, X. X.; Qiao, L. H.; Liu, W. P.

    2016-07-01

    The relative γ -decay probability ratios of the neutron resonance states in 94Zr and 92Zr populated via two-neutron transfer reactions, 92Zr(18O,16O)94Zr and 90Zr(18O,16O)92Zr , have been measured to test the validity of the surrogate ratio method (SRM) in determining the (n , γ ) reaction cross section. The cross sections of the 93Zr(n ,γ )94Zr reaction are derived from the experimentally obtained ratios and the cross sections of the 91Zr(n ,γ )92Zr reaction in the equivalent neutron energy range of En=0 -8 MeV . The deduced cross sections of 93Zr(n ,γ )94Zr reaction agree with the directly measured ones in the low-energy region, and with the evaluated ENDF/B-VII.1 data at higher energies of En>3 MeV . The agreement supports the concept of the SRM method to indirectly determine the (n ,γ ) reaction cross sections.

  18. Final state interaction in (3He, 2He) reactions

    NASA Astrophysics Data System (ADS)

    Congedo, T. V.; Lee-Fan, I. S.; Cohen, B. L.

    1980-09-01

    The two protons from 2He breakup following (3He, 2He) reactions were detected in coincidence, and energy and angular correlations between them were studied and compared with predictions of the final state interaction theories of Watson and Migdal and Phillips, Griffy, and Biedenharn. The angular correlation between the breakup protons drops off much faster than predicted by these theories; a final state interaction empirically derived to fit the angular correlation is sharply peaked at a breakup energy ~ 0.6 MeV and is quite narrow. Energy distributions of the protons have a dip at the center for small correlation angles which disappears at larger angles. This is well predicted by all final state interaction theories but the slopes of these distributions are much better fit by the empirical final state interaction than by Watson and Migdal or by Phillips, Griffy, and Biedenharn. By maintaining a constant small correlation angle (proton detectors close together), 2He angular distributions were measured and found to be in good agreement with distorted-wave Born approximation predictions. NUCLEAR REACTIONS 64Ni(3He, 2p), E=13 MeV; measured σ(θ), pp correlation; deduced pp FSI; calculated 2He detection efficiency. 9Be(3He, 2p), E=13 MeV; measured σ(θ). 27Al, 90Zr(3He, 2p) measured pp correlation. 51V, 65Cu, 89Y(3He, 2p), E=13 MeV, 17 MeV, measured σ(θ), DWBA analysis.

  19. Transfer couplings and hindrance far below the barrier for 40 Ca + 96 Zr

    DOE PAGESBeta

    Stefanini, A. M.; Montagnoli, G.; Esbensen, H.; Corradi, L.; Courtin, S.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; et al

    2015-01-29

    The sub-barrier fusion excitation function of 40Ca + 96Zr has been measured down to cross sections ≃2.4µb, i.e. two orders of magnitude smaller than obtained in the previous experiment, where the sub-barrier fusion of this system was found to be greatly enhanced with respect to 40Ca + 90Zr, and the need of coupling to transfer channels was suggested. The purpose of this work was to investigate the behavior of 40Ca + 96Zr fusion far below the barrier. The smooth trend of the excitation function has been found to continue, and the logarithmic slope increases very slowly. No indication of hindrancemore » shows up, and a comparison with 48Ca + 96Zr is very useful in this respect. A new CC analysis of the complete excitation function has been performed, including explicitly one- and two-nucleon Q >0 transfer channels. Such transfer couplings bring significant cross section enhancements, even at the level of a few µb. Locating the hindrance threshold, if any, in 40Ca + 96Zr would require challenging measurements of cross sections in the sub-µb range.« less

  20. Cement As a Waste Form for Nuclear Fission Products: The Case of (90)Sr and Its Daughters.

    PubMed

    Dezerald, Lucile; Kohanoff, Jorge J; Correa, Alfredo A; Caro, Alfredo; Pellenq, Roland J-M; Ulm, Franz J; Saúl, Andrés

    2015-11-17

    One of the main challenges faced by the nuclear industry is the long-term confinement of nuclear waste. Because it is inexpensive and easy to manufacture, cement is the material of choice to store large volumes of radioactive materials, in particular the low-level medium-lived fission products. It is therefore of utmost importance to assess the chemical and structural stability of cement containing radioactive species. Here, we use ab initio calculations based on density functional theory (DFT) to study the effects of (90)Sr insertion and decay in C-S-H (calcium-silicate-hydrate) in order to test the ability of cement to trap and hold this radioactive fission product and to investigate the consequences of its β-decay on the cement paste structure. We show that (90)Sr is stable when it substitutes the Ca(2+) ions in C-S-H, and so is its daughter nucleus (90)Y after β-decay. Interestingly, (90)Zr, daughter of (90)Y and final product in the decay sequence, is found to be unstable compared to the bulk phase of the element at zero K but stable when compared to the solvated ion in water. Therefore, cement appears as a suitable waste form for (90)Sr storage. PMID:26513644

  1. Isoscalar Giant Dipole Resonance within Fermi Liquid Drop Model

    NASA Astrophysics Data System (ADS)

    Pochivalov, Oleksiy; Shlomo, Shalom

    2006-04-01

    Recent highly accurate experimental data on Isoscalar Giant Dipole (ISGDR) and Monopole (ISGMR) Resonances in nuclei renewed interest in correct microscopic description of collective excitations. Hartree-Fock based Random-Phase-Approximation (HF-RPA) is a successful method of describing collective excitations in nuclei. However, recent fully self-consistent HF-RPA calculations, which reproduce the centroid energies of the ISGMR, systematically overestimate by 1.5-2.5 MeV results for the ISGDR energy comparing with experimentally obtained data. Also, the HF-RPA model does not provide description of the widths of giant resonances. We consider these issues within the semi-classical generalization of the mean field theory, namely, Fermi-Liquid-Drop-Model (FLDM). In this presentation, we provide description of the FLDM formalism in its application to ISGDR and ISGMR calculations. We present results of FLDM calculations for centroid energy and widths of the ISGDR and ISGMR in the four nuclei, namely, 90Zr, 116Sn, 144Sm, and 208Pb and compare with available experimental data.

  2. Chemical diffusion in ZrNb system

    NASA Astrophysics Data System (ADS)

    Patil, R. V.; Kale, G. B.; Garg, S. P.

    1995-05-01

    The temperature and concentration dependence of interdiffusion coefficients in zirconium-niobium system has been established in the temperature range between 1593 and 1993 K by employing an electron probe micro analyser. The interdiffusion coefficients are found to increase with increase in zirconium content in the alloy and can be described by the relation D˜(C) = A (T)e5.6C Here, A( T) is the temperature dependent parameter and has the value of tracer diffusion coefficient at infinite dilution. C is the mole fraction of the component. The temperature dependence of interdiffusion coefficients can be represented by the Arrhenius expression of the type D˜(C) = D˜A 0eQ˜/RT The activation energy ( Q˜c) and frequency factor ( D˜0) values in the composition range between 5 and 90% Zr lie in the range of 216 to 276 kJ/mol, and 10 -7 to 10 -5 m 2/s, respectively. An attempt has also been made to evaluate the impurity diffusion data by using interdiffusion values.

  3. Crystalline hosts to accommodate the transmutation of Cs and Sr

    NASA Astrophysics Data System (ADS)

    Vance, E. R.; Roy, R.; Pepin, J.; Agrawal, D. K.

    1982-04-01

    Certain deleterious effects on a solid nuclear waste form, though not yet quantitatively defined, could occur due to transmutations such as 137Cs+ yields 137 Ba2+ and 90Sr2+ yields 90Zr4+ (t sub /1/2/ = 30 yr in both cases). The relevant causes of such possible effects are the changes in ionic valence and size. This report explicitly formulates a chemical mitigation strategy: if the transmuting species can be incorporated in a multiple-cation host, in which one of the inert cations is a variable-valence transition metal, the valence change aspect of transmutation can be mitigated by a complementary valence change of the transition metal ion. The present work consisted of chemically simulating the transmutation, the goal being to find a Cs- and Sr-bearing single-phase host that would remain single-phase after the transmutation had occurred. Of several structures tried, perovskite appears to be the most promising, as the A-site can accommodate the approximately 20% size change that occurs when Cs decays to Ba. Ta and Nb were used as the variable-valence ions in the B site. Although not explicity studied here, magnetoplumbite seems likely to accommodate the Cs yields Ba transmutation. The application of the results to unpartitioned and partitioned nuclear wastes is discussed.

  4. Octupole collectivity in 94Zr

    NASA Astrophysics Data System (ADS)

    Toh, Y.; Oshima, M.; Koizumi, M.; Osa, A.; Kimura, A.; Sugawara, M.; Goto, J.

    2009-01-01

    The Zr isotopes between 90Zr and 96Zr are expected to be spherical based on the almost complete subshell closures at Z = 40 and N = 50, 56. On the other hand, they have low-lying 3- states and show the characteristics of low frequency octupole oscillation which arise as a superposition of particle-hole excitations. A 380 MeV 94Zr beam from the tandem accelerator at the Japan Atomic Energy Agency (JAEA) was excited on a self-supporting natPb target. The gamma-ray detector array GEMINI-II was used to detect deexcitation gamma rays. The scattered beam (94Zr) was detected with a position-sensitive particle detector system. The gamma-ray intensities were used as an input to the least-squares search code GOSIA to determine the E3 matrix element of the first 3- excited state of 94Zr. The B(E3;0+→3-) value of 0.21(6) e2b3 in 94Zr has been obtained by Coulomb excitation experiment.

  5. Photonuclear and radiative capture reaction rates for Nuclear Astrophysics

    NASA Astrophysics Data System (ADS)

    Beard, Mary; Frauendorf, S.; Kaempfer, B.; Scwengner, R.; Wiescher, M.

    2011-10-01

    The vast majority of nuclei heavier than iron are synthesisized via the capture of neutrons. There are however 35 naturally occurring nuclei, including isotopes of Mo and La, located on the neutron-deficient size of the valley of stability. It has been proposed that these nuclei, referred to as p-nuclei, are produced via sequential photo-dissociation reactions in the oxygen-neon shell burning regions of a pre-supernova star. As such, cross sections for p-nuclei production are particularly sensitive to the gamma-ray strength function, which, though dominated by the giant dipole resonance, may contain extra strength contributions near to the neutron threshold. Recently new (γ, γ') cross section measurements have been performed at the ELBE facility at Helmholtz-Zentrum Dresden-Rossendorf for the nuclei ^92-100Mo, ^88Sr, ^90Zr and ^139La probing the photo-absorption cross section over an energy range 4.5 - 6 MeV, up to the neutron separation threshold. The use of these measurements as a test of existing gamma-ray strength function models, and the consequent impact on p-nuclei production rates, will be discussed.

  6. Accelerated chemical aging of crystalline nuclear waste forms: A density functional theory study of 109Cdx 109Ag1-x S

    NASA Astrophysics Data System (ADS)

    Dorado, B.; Uberuaga, B. P.; Marks, N. A.; Stanek, C. R.

    2015-06-01

    Recently, a combined experimental-theoretical approach to assess the effect of daughter product formation on the stability of crystalline compounds comprised of radioisotopes has been developed. This methodology was motivated by the potential impact on crystalline nuclear waste form stability of a significant fraction of the constituent atoms undergoing transmutation. What is particularly novel about this approach is the experimental use of very short-lived isotopes to accelerate the chemical evolution that occurs during decay. In this paper, we present results of density functional theory (DFT) calculations that have been performed in support of corresponding experiments on the 109Cdx 109Ag1-x S material system. 109Cd has been selected in order to simulate the decay of important "short-lived" fission products 137Cs or 90Sr (which decay via β - to 137Ba and 90Zr respectively with ≈ 30-year half-lives). By comparison, 109Cd decays by electron capture with a half-life of 109 days to 109Ag. DFT results predict the formation of heretofore unobserved CdxAg1-x S structures, which support corresponding experiments and ultimately may have implications for waste form stability.

  7. Determination of 90Sr and Pu isotopes in contaminated groundwater samples by inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Zoriy, Miroslav V.; Ostapczuk, Peter; Halicz, Ludwik; Hille, Ralf; Becker, J. Sabine

    2005-04-01

    A sensitive analytical method for determining the artificial radionuclides 90Sr, 239Pu and 240Pu at the ultratrace level in groundwater samples from the Semipalatinsk Test Site area in Kazakhstan by double-focusing sector field inductively coupled plasma mass spectrometry (ICP-SFMS) was developed. In order to avoid possible isobaric interferences at m/z 90 for 90Sr determination (e.g. 90Zr+, 40Ar50Cr+, 36Ar54Fe+, 58Ni16O2+, 180Hf2+, etc.), the measurements were performed at medium mass resolution under cold plasma conditions. Pu was separated from uranium by means of extraction chromatography using Eichrom TEVA resin with a recovery of 83%. The limits of detection for 90Sr, 239Pu and 240Pu in water samples were determined as 11, 0.12 and 0.1 fg ml-1, respectively. Concentrations of 90Sr and 239Pu in contaminated groundwater samples ranged from 18 to 32 and from 28 to 856 fg ml-1, respectively. The 240Pu/239Pu isotopic ratio in groundwater samples was measured as 0.17. This isotope ratio indicates that the most probable source of contamination of the investigated groundwater samples was the nuclear weapons tests at the Semipalatinsk Test Site conducted by the USSR in the 1960s.

  8. Deformed Structures and Shape Coexistence in Zr-98

    NASA Astrophysics Data System (ADS)

    Olaizola, Bruno; 8pi Collaboration

    2015-10-01

    The nuclear structure of the zirconium isotopes evolves from a mid-open neutron shell deformed region (80Zr), through a closed shell (90Zr), to a closed subshell (96Zr), and then to a sudden reappearance of deformation (100Zr). This rapid onset of deformation across the Zr isotopes is unprecedented, and the issue of how collectivity appears and disappears in these isotopes is of special interest. Until recently, only 98Zr (and maybe 100Zr) had indirect and weak evidence for shape coexistence, with only speculative interpretation of the experiments. Recent results from high precision B(E2) measurements provided direct evidence of shape coexistence in 94Zr and suggested that it may happen in many other nuclei in this region. In order to provide direct evidence of shape coexistence in 98Zr a high-statistical-quality γγ experiment was carried out with the 8 π spectrometer at ISAC-TRIUMF. The array consists of 20 Compton-suppressed hyper-pure germanium detectors plus β particle and conversion electron detectors. Excited states up to ~ 5 MeV in 98Zr were populated in the β- decay of 98Y Jπ = (0-) and 98mY J = (4,5). Preliminary results on key branching ratios will be presented. This work was supported by the Natural Sciences and Engineering Research Council of Canada and the National Research Council of Canada.

  9. Environmental 90Sr measurements

    USGS Publications Warehouse

    Paul, M.; Berkovits, D.; Cecil, L.D.; Feldstein, H.; Hershkowitz, A.; Kashiv, Y.; Vogt, S.

    1997-01-01

    90Sr (T1/2 = 28.5 years) is a long-lived radionuclide produced in nuclear fission. Fast radiochemical detection of 90Sr in environmental samples is not feasible using current analytical methods. Accelerator Mass Spectrometry (AMS) measurements of 90Sr were made with the Rehovot 14UD Pelletron accelerator at a terminal voltage of 11 or 12 MV using our standard detection system. Injection of hydride ions (SrH3-) was chosen owing to high beam intensity and low Coulomb explosion effects. 90Sr ions were identified and discriminated from isobaric 90Zr by measuring time of flight, total energy and three independent energy-loss signals in an ionization chamber. A reference sample and a ground-water sample were successfully measured. The detection limit determined for a laboratory blank by the residual counts in the 90Sr region is 90Sr/Sr = 3 ?? 10-13, corresponding in practice to (2-4) ?? 10790Sr atoms or about 0.5-1 pCi/L in environmental water samples.

  10. Neutron Capture Cross Section of 90Zr: Bottleneck in the s-Process Reaction Flow

    SciTech Connect

    Tagliente, G.; Koehler, Paul Edward; Collaboration, n_TOF

    2008-03-01

    The neutron capture cross sections of the Zr isotopes have important implications in nuclear astrophysics and for reactor design. The small cross section of the neutron magic nucleus {sup 90}Zr, which accounts for more than 50% of natural zirconium represents one of the key isotopes for the stellar s-process, because it acts as a bottleneck in the neutron capture chain between the Fe seed and the heavier isotopes. The same element, Zr, also is an important component of the structural materials used in traditional and advanced nuclear reactors. The (n,{gamma}) cross section has been measured at CERN, using the n{_}TOF spallation neutron source. In total, 45 resonances could be resolved in the neutron energy range below 70 keV, 10 being observed for the first time thanks to the high resolution and low backgrounds at n{_}TOF. On average, the {Lambda}{sub {gamma}}widths obtained in resonance analyses with the R-matrix code SAMMY were 15% smaller than reported previously. By these results, the accuracy of the Maxwellian averaged cross section for s-process calculations has been improved by more than a factor of 2.

  11. A study on nuclear properties of Zr, Nb, and Ta nuclei used as structural material in fusion reactor

    NASA Astrophysics Data System (ADS)

    Sahan, Halide; Tel, Eyyup; Sahan, Muhittin; Aydin, Abdullah; Hakki Sarpun, Ismail; Kara, Ayhan; Doner, Mesut

    2015-07-01

    Fusion has a practically limitless fuel supply and is attractive as an energy source. The main goal of fusion research is to construct and operate an energy generating system. Fusion researches also contains fusion structural materials used fusion reactors. Material issues are very important for development of fusion reactors. Therefore, a wide range of fusion structural materials have been considered for fusion energy applications. Zirconium (Zr), Niobium (Nb) and Tantalum (Ta) containing alloys are important structural materials for fusion reactors and many other fields. Naturally Zr includes the 90Zr (%51.5), 91Zr (%11.2), 92Zr (%17.1), 94Zr (%17.4), 96Zr (%2.80) isotopes and 93Nb and 181Ta include the 93Nb (%100) and 181Ta (%99.98), respectively. In this study, the charge, mass, proton and neutron densities and the root-mean-square (rms) charge radii, rms nuclear mass radii, rms nuclear proton, and neutron radii have been calculated for 87-102Zr, 93Nb, 181Ta target nuclei isotopes by using the Hartree-Fock method with an effective Skyrme force with SKM*. The calculated results have been compared with those of the compiled experimental taken from Atomic Data and Nuclear Data Tables and theoretical values of other studies.

  12. Description of fusion and evaporation residue formation cross sections in reactions leading to the formation of element Z =122 within the Langevin approach

    NASA Astrophysics Data System (ADS)

    Litnevsky, V. L.; Kosenko, G. I.; Ivanyuk, F. A.

    2016-06-01

    We describe the evolution of the compact system formed by the touching of two colliding ions in reactions 58Fe+248Cm → 306-x122 + xn, 64Ni+244Pu → 308-x122 + xn, and 90Zr+208Pb → 298-x122 + xn. The description is carried out within the dynamical multidimensional stochastic approach, based on Langevin equations for the shape degrees of freedom of colliding ions and the compact system. For the approach stage we take into account the shell structure of colliding ions, their orientation in the space, and the effect of tunneling of ions through the Coulomb barrier. By describing the evolution of the compact system formed after the touching of incident ions, the shell structure of the compact system is also taken into account. Within this approach we have calculated the compound nucleus and evaporation residue formation cross sections. These can be compared with the experimental data. We have also clarified the impact of the tunneling effect in the entrance channel on the fusion and evaporation residue cross sections.

  13. Determination of 90Sr in contaminated environmental samples by tuneable bandpass dynamic reaction cell ICP-MS.

    PubMed

    Taylor, V F; Evans, R D; Cornett, R J

    2007-01-01

    A rapid method for the extraction and determination of 90Sr in natural water, plant and sediment samples was developed using extraction chromatography and dynamic reaction cell ICP-MS, with O2 as a reaction gas. While isobaric interference from the stable isotope 90Zr was efficiently removed by this method, interferences produced from in-cell reactions with Fe+ and Ni+ required suppression by tuneable bandpass, and in sediments, additional chromatographic separation. Method detection limits were 0.1 pg g-1 (0.5 Bq g-1), 0.04 pg g-1(0.2 Bq g-1), and 3 pg L-1 (5 Bq L-1) for sediments, plant and water samples, respectively, and 90Sr concentrations determined by ICP-MS were in good agreement with activities determined by Cerenkov counting and with certified reference values. While mass spectrometric determination does not rival detection limits achievable by radiometric counting, radiometric determination of 90Sr, a pure beta-emitter, is hindered by long analysis times (several weeks); the comparatively fast analysis achieved via ICP-MS enables same-day preparation and analysis of samples, making this an important technique for the environmental monitoring of areas contaminated by radioactivity. PMID:17111103

  14. What Do s- and p-Wave Neutron Average Radiative Widths Reveal

    SciTech Connect

    Mughabghab, S.F.

    2010-04-30

    A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

  15. Neutron activation diagnostics at the National Ignition Facility (invited).

    PubMed

    Bleuel, D L; Yeamans, C B; Bernstein, L A; Bionta, R M; Caggiano, J A; Casey, D T; Cooper, G W; Drury, O B; Frenje, J A; Hagmann, C A; Hatarik, R; Knauer, J P; Johnson, M Gatu; Knittel, K M; Leeper, R J; McNaney, J M; Moran, M; Ruiz, C L; Schneider, D H G

    2012-10-01

    Neutron yields are measured at the National Ignition Facility (NIF) by an extensive suite of neutron activation diagnostics. Neutrons interact with materials whose reaction cross sections threshold just below the fusion neutron production energy, providing an accurate measure of primary unscattered neutrons without contribution from lower-energy scattered neutrons. Indium samples are mounted on diagnostic instrument manipulators in the NIF target chamber, 25-50 cm from the source, to measure 2.45 MeV deuterium-deuterium fusion neutrons through the (115)In(n,n')(115 m) In reaction. Outside the chamber, zirconium and copper are used to measure 14 MeV deuterium-tritium fusion neutrons via (90)Zr(n,2n), (63)Cu(n,2n), and (65)Cu(n,2n) reactions. An array of 16 zirconium samples are located on port covers around the chamber to measure relative yield anisotropies, providing a global map of fuel areal density variation. Neutron yields are routinely measured with activation to an accuracy of 7% and are in excellent agreement both with each other and with neutron time-of-flight and magnetic recoil spectrometer measurements. Relative areal density anisotropies can be measured to a precision of less than 3%. These measurements reveal apparent bulk fuel velocities as high as 200 km/s in addition to large areal density variations between the pole and equator of the compressed fuel. PMID:23126840

  16. Measurements of the cross section for the (182)W(n,p)(182(m+g))Ta and (184)(n,p)(184)Ta reactions in the 14MeV energy range using the activation technique.

    PubMed

    Song, Yueli; Zhou, Fengqun; Tian, Mingli; Li, Yong; Yuan, Shuqing; Lan, Changlin

    2015-04-01

    The cross section for the (182)W(n,p)(182(m+g))Ta and (184)W(n,p)(184)Ta reactions has been measured in the neutron energy range of 13.5-14.7MeV using the activation technique and a coaxial HPGe γ-ray detector. In our experiment, the fast neutrons were produced by the T(d,n)(4)He reaction at the ZF-300-II Intense Neutron Generator at Lanzhou University. Natural wolfram foils of 99.9% purity were used as target materials. The neutron flux was determined using the monitor reaction (93)Nb(n,2n)(92m)Nb and the neutron energies were determined using the method of cross-section ratio measurements employing the (90)Zr(n,2n)(89)Zr to (93)Nb(n,2n)(92m)Nb reactions. The results of this work are compared with experimental data found in the literature and the estimates obtained from a published empirical formula based on the statistical model with Q-value dependence and odd-even effects taken into consideration. PMID:25617709

  17. Accelerator mass spectrometry of Strontium-90 for homeland security, environmental monitoring, and human health

    SciTech Connect

    Tumey, S J; Brown, T A; Hamilton, T F; Hillegonds, D J

    2008-03-03

    Strontium-90 is one of the most hazardous materials managed by agencies charged with protecting the public from radiation. Traditional radiometric methods have been limited by low sample throughput and slow turnaround times. Mass spectrometry offers the advantage of shorter analysis times and the ability to measure samples immediately after processing, however conventional mass spectrometric techniques are susceptible to molecular isobaric interferences that limit their overall sensitivity. In contrast, accelerator mass spectrometry is insensitive to molecular interferences and we have therefore begun developing a method for determination of {sup 90}Sr by accelerator mass spectrometry. Despite a pervasive interference from {sup 90}Zr, our initial development has yielded an instrumental background of {approx} 10{sup 8} atoms (75 mBq) per sample. Further refinement of our system (e.g., redesign of our detector, use of alternative target materials) is expected to push the background below 10{sup 6} atoms, close to the theoretical limit for AMS. Once we have refined our system and developed suitable sample preparation protocols, we will utilize our capability in applications to homeland security, environmental monitoring, and human health.

  18. bmo-miR-0001 and bmo-miR-0015 down-regulate expression of Bombyx mori fibroin light chain gene in vitro.

    PubMed

    Chen, Chen; Fan, Yang-yang; Wang, Xin; Song, Fei; Jiang, Tao; Qian, Ping; Tang, Shun-ming; Shen, Xing-jia

    2016-02-01

    Based on bioinformatic analysis, we selected two novel microRNAs (miRNAs), bmo-miR-0001 and bmo-miR-0015, from high-throughput sequencing of the Bombyx mori larval posterior silk gland (PSG). Firstly, we examined the expression of bmo-miR-0001 and bmo-miR 12 different tissues of the 5th instar Day-3 larvae of the silkworm. The results showed that the expression levels of both bmo-miR-0001 and bmo-miR-0015 were obviously higher in the PSG than in other tissues, implying there is a spatio-temporal condition for bmo-miR-0001 and bmo-miR-0015 to regulate the expression of BmFib-L. To test this hypothesis, we constructed pri-bmo-miR-0001 expressing the plasmid pcDNA3.0 and pri-bmo-miR-0015 expressing the plasmid pcDNA3.0 [ie1-egfp-pri-bmo-miR-0015-SV40]. Finally, the BmN cells were harvested and luciferase activity was detected. The results showed that luciferase activity was reduced significantly (P<0.05) in BmN cells co-transfected by pcDNA3.0 [ie1-egfp-pri-bmo-miR-0001-SV40] or pcDNA3.0 with pGL3.0 [A3-luc-Fib-L-3'UTR-SV40], suggesting that both bmo-miR-0001 and bmo-miR-0015 can down-regulate the expression of BmFib-L in vitro. PMID:26834013

  19. Dehydroepiandrosterone Activation of G-protein-coupled Estrogen Receptor Rapidly Stimulates MicroRNA-21 Transcription in Human Hepatocellular Carcinoma Cells.

    PubMed

    Teng, Yun; Radde, Brandie N; Litchfield, Lacey M; Ivanova, Margarita M; Prough, Russell A; Clark, Barbara J; Doll, Mark A; Hein, David W; Klinge, Carolyn M

    2015-06-19

    Little is known about the regulation of the oncomiR miR-21 in liver. Dehydroepiandrosterone (DHEA) regulates gene expression as a ligand for a G-protein-coupled receptor and as a precursor for steroids that activate nuclear receptor signaling. We report that 10 nm DHEA increases primary miR-21 (pri-miR-21) transcription and mature miR-21 expression in HepG2 cells in a biphasic manner with an initial peak at 1 h followed by a second, sustained response from 3-12 h. DHEA also increased miR-21 in primary human hepatocytes and Hep3B cells. siRNA, antibody, and inhibitor studies suggest that the rapid DHEA-mediated increase in miR-21 involves a G-protein-coupled estrogen receptor (GPER/GPR30), estrogen receptor α-36 (ERα36), epidermal growth factor receptor-dependent, pertussis toxin-sensitive pathway requiring activation of c-Src, ERK1/2, and PI3K. GPER antagonist G-15 attenuated DHEA- and BSA-conjugated DHEA-stimulated pri-miR-21 transcription. Like DHEA, GPER agonists G-1 and fulvestrant increased pri-miR-21 in a GPER- and ERα36-dependent manner. DHEA, like G-1, increased GPER and ERα36 mRNA and protein levels. DHEA increased ERK1/2 and c-Src phosphorylation in a GPER-responsive manner. DHEA increased c-Jun, but not c-Fos, protein expression after 2 h. DHEA increased androgen receptor, c-Fos, and c-Jun recruitment to the miR-21 promoter. These results suggest that physiological concentrations of DHEA activate a GPER intracellular signaling cascade that increases pri-miR-21 transcription mediated at least in part by AP-1 and androgen receptor miR-21 promoter interaction. PMID:25969534

  20. Language Impairment in Children Perinatally Infected with HIV Compared to Children Who Were HIV-Exposed and Uninfected

    PubMed Central

    Rice, Mabel L.; Buchanan, Ashley L.; Siberry, George K; Malee, Kathleen M.; Zeldow, Bret; Frederick, Toni; Purswani, Murli U.; Hoffman, Howard J.; Sirois, Patricia A.; Smith, Renee; Torre, Peter; Allison, Susannah M; Williams, Paige L.

    2011-01-01

    Objective To investigate risk for language impairment in children perinatally infected or exposed to HIV. Methods We evaluated the prevalence of language impairment (LI) in 7–16 year old children with perinatal HIV infection (HIV+) compared to children HIV-exposed and uninfected (HEU), using a comprehensive standardized language test (CELF-4). LI was classified as primary LI (Pri-LI) (monolingual English exposure and no cognitive or hearing impairment), concurrent LI (Con-LI) (cognitive or hearing impairment), or no LI. Associations of demographic, caregiver, HIV disease and antiretroviral treatment (ART) factors with LI category were evaluated using univariate and multivariable logistic regression models. Results Of 468 children with language assessments, 184 (39%) had LI. No difference was observed by HIV infection status for overall LI or for Pri-LI or Con-LI; mean (SD) CELF-4 scores were 88.5 (18.4) for HIV+ vs 87.5 (17.9) for HEU. After adjustment, Black children had higher odds of Pri-LI vs no LI (aOR=2.43, p=0.03). Children who were Black, Hispanic, had a caregiver with low education or low IQ, or a non-biological parent as caregiver had higher odds of Con-LI vs no LI. Among HIV+ children, viral load >400 copies/ml (aOR=3.04, p<0.001), CDC Class C (aOR=2.19, p=0.02) and ART initiation <6 months of age (aOR=2.12, p=0.02) were associated with higher odds of Con-LI vs. no LI. Conclusions Children perinatally exposed to HIV are at high risk for LI, but such risk was not increased for youth with HIV. Risk factors differed for Pri-LI and Con-LI. PMID:22179050

  1. Morin, Jean-Baptiste (1583-1656)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Doctor, alchemist and astrologer, born in Villefranche, Beaujolais, France, became professor of mathematics at the Collège Royal, published a defense of ARISTOTLE, attacked GALILEO, being convinced that the Earth was fixed in space. Morin proposed an impractical method to solve the longitude problem, based on measuring absolute time by the position of the Moon. He put the method in for a pri...

  2. Business-led efforts to control costs.

    PubMed

    Kenkel, P J

    1991-07-29

    Business-led initiatives to compare medical quality and prices are becoming commonplace as employers seek ways to cap medical expenses. But employers are meeting with varying degrees of cooperation from hospitals. The tale of two cities' efforts to pry open the secrets of controlling costs provides a vivid contrast in the way purchasers have tried to solve the cost-containment puzzle. PMID:10111874

  3. Subacute Changes in Cleavage Processing of Amyloid Precursor Protein and Tau following Penetrating Traumatic Brain Injury.

    PubMed

    Cartagena, Casandra M; Mountney, Andrea; Hwang, Hye; Swiercz, Adam; Rammelkamp, Zoe; Boutte, Angela M; Shear, Deborah A; Tortella, Frank C; Schmid, Kara E

    2016-01-01

    Traumatic brain injury (TBI) is an established risk factor for the development of Alzheimer's disease (AD). Here the effects of severe penetrating TBI on APP and tau cleavage processing were investigated in a rodent model of penetrating ballistic-like brain injury (PBBI). PBBI was induced by stereotactically inserting a perforated steel probe through the right frontal cortex of the anesthetized rat and rapidly inflating/deflating the probe's elastic tubing into an elliptical shaped balloon to 10% of total rat brain volume causing temporary cavitation injury. Separate animals underwent probe injury (PrI) alone without balloon inflation. Shams underwent craniectomy. Brain tissue was collected acutely (4h, 24h, 3d) and subacutely (7d) post-injury and analyzed by immunoblot for full length APP (APP-FL) and APP beta c-terminal fragments (βCTFs), full length tau (tau-FL) and tau truncation fragments and at 7d for cytotoxic Beta amyloid (Aβ) peptides Aβ40 and Aβ42 analysis. APP-FL was significantly decreased at 3d and 7d following PBBI whereas APP βCTFs were significantly elevated by 4h post-injury and remained elevated through 7d post-injury. Effects on βCTFs were mirrored with PrI, albeit to a lesser extent. Aβ40 and Aβ42 were significantly elevated at 7d following PBBI and PrI. Tau-FL decreased substantially 3d and 7d post-PBBI and PrI. Importantly, a 22 kDa tau fragment (tau22), similar to that found in AD, was significantly elevated by 4h and remained elevated through 7d post-injury. Thus both APP and tau cleavage was dramatically altered in the acute and subacute periods post-injury. As cleavage of these proteins has also been implicated in AD, TBI pathology shown here may set the stage for the later development of AD or other tauopathies. PMID:27428544

  4. Higher body weight patients on clopidogrel maintenance therapy have lower active metabolite concentrations, lower levels of platelet inhibition, and higher rates of poor responders than low body weight patients.

    PubMed

    Wagner, Henrik; Angiolillo, Dominick J; Ten Berg, Jurrien M; Bergmeijer, Thomas O; Jakubowski, Joseph A; Small, David S; Moser, Brian A; Zhou, Chunmei; Brown, Patricia; James, Stefan; Winters, Kenneth J; Erlinge, David

    2014-01-01

    Body weight is a predictor of clopidogrel response. However, no prospective studies have compared pharmacodynamic (PD) and pharmacokinetic (PK) data based on body weight. We compared PD and PK effects of clopidogrel 75 mg in low body weight (LBW, <60 kg) and higher body weight (HBW, ≥60 kg) patients with stable coronary artery disease. LBW (n = 34, 56.4 ± 3.7 kg) and HBW (n = 38, 84.7 ± 14.9 kg) aspirin-treated patients received clopidogrel 75 mg for 10-14 days. The area under the concentration-time curve of active metabolite (Clop-AM) calculated through the last quantifiable concentration up to 4 h postdose, AUC(0-tlast), was calculated by noncompartmental methods. Light transmission aggregometry (LTA) (maximum platelet aggregation and inhibition of platelet aggregation to 20 μM adenosine diphosphate (ADP), and residual platelet aggregation to 5 μM ADP), VerifyNow(®) P2Y12 reaction units (PRU), and vasodilator-associated stimulated phosphoprotein phosphorylation platelet reactivity index (VASP-PRI) were performed. Mean AUC(0-tlast) was lower in HBW than LBW patients: 12.8 versus 17.9 ng h/mL. HBW patients had higher platelet reactivity as measured by LTA (all p ≤ 0.01), PRU (207 ± 68 vs. 152 ± 57, p < 0.001), and VASP-PRI (56 ± 18 vs. 39 ± 17, p < 0.001). More HBW patients exhibited high on-treatment platelet reactivity (HPR) using PRU (35 vs. 9%) and VASP-PRI (65 vs. 27%). Body weight correlated with PRU and VASP-PRI (both p < 0.001), and inversely with log transformed AUC(0-tlast) (p < 0.001). In conclusion, HBW patients had lower levels of Clop-AM, and higher platelet reactivity and rates of HPR than LBW subjects, contributing to their suboptimal response to clopidogrel. PMID:24043374

  5. NUCLEAR ESPIONAGE: Report Details Spying on Touring Scientists.

    PubMed

    Malakoff, D

    2000-06-30

    A congressional report released this week details dozens of sometimes clumsy attempts by foreign agents to obtain nuclear secrets from U.S. nuclear scientists traveling abroad, ranging from offering scientists prostitutes to prying off the backs of their laptop computers. The report highlights the need to better prepare traveling researchers to safeguard secrets and resist such temptations, say the two lawmakers who requested the report and officials at the Department of Energy, which employs the scientists. PMID:17769833

  6. Evolution of substrate specificity in a recipient's enzyme following horizontal gene transfer.

    PubMed

    Noda-García, Lianet; Camacho-Zarco, Aldo R; Medina-Ruíz, Sofía; Gaytán, Paul; Carrillo-Tripp, Mauricio; Fülöp, Vilmos; Barona-Gómez, Francisco

    2013-09-01

    Despite the prominent role of horizontal gene transfer (HGT) in shaping bacterial metabolism, little is known about the impact of HGT on the evolution of enzyme function. Specifically, what is the influence of a recently acquired gene on the function of an existing gene? For example, certain members of the genus Corynebacterium have horizontally acquired a whole l-tryptophan biosynthetic operon, whereas in certain closely related actinobacteria, for example, Mycobacterium, the trpF gene is missing. In Mycobacterium, the function of the trpF gene is performed by a dual-substrate (βα)8 phosphoribosyl isomerase (priA gene) also involved in l-histidine (hisA gene) biosynthesis. We investigated the effect of a HGT-acquired TrpF enzyme upon PriA's substrate specificity in Corynebacterium through comparative genomics and phylogenetic reconstructions. After comprehensive in vivo and enzyme kinetic analyses of selected PriA homologs, a novel (βα)8 isomerase subfamily with a specialized function in l-histidine biosynthesis, termed subHisA, was confirmed. X-ray crystallography was used to reveal active-site mutations in subHisA important for narrowing of substrate specificity, which when mutated to the naturally occurring amino acid in PriA led to gain of function. Moreover, in silico molecular dynamic analyses demonstrated that the narrowing of substrate specificity of subHisA is concomitant with loss of ancestral protein conformational states. Our results show the importance of HGT in shaping enzyme evolution and metabolism. PMID:23800623

  7. Synthesis and coordination chemistry of tridentate (PNN) amine enamido phosphine ligands with ruthenium.

    PubMed

    Wambach, T C; Lenczyk, C; Patrick, B O; Fryzuk, M D

    2016-04-01

    Tridentate amine-imine-phosphine ligands, R2PC5H7NC2H4NEt2 [(R)PNN(H)], where R = Pr(i) or Bu(t) are synthesized using a straightforward protocol of condensation, deprotonation, and addition of a chlorodialkylphosphine. Multinuclear NMR spectroscopy shows the ligands exist exclusively in the enamine tautomeric form in solution. Treating these ligands with RuHCl(PPr(i)3)2(CO) forms the desired coordination compounds, RuHCl[(R)PNN(H)](CO), where the imine tautomeric form of the ligands coordinates to ruthenium. Deuterium labelling experiments show Ru-H/N-D scrambling occurs during ligand coordination. Treating the RuHCl[(R)PNN(H)](CO) precursors with potassium tert-butoxide allows for the synthesis of two new ruthenium enamido-phosphine complexes, RuH[(R)PNN](CO), which were fully characterized. The structure of one of the derivatives was confirmed by X-ray crystallography (R = Pr(i)). The reactivity of the enamido-phosphine complexes with H2 and benzyl alcohol is also reported. For the enamido phosphine complex where R = Pr(i), the reaction with H2 is reversible and forms (RuH(CO)[(Pri)PNN(H)])2(μ-H)2, a hydride-bridged dimer that results from cooperative activation of H2. The reactivity of both amine-enamido-phosphine ruthenium compounds with benzyl alcohol establishes that the complexes are catalyst precursors for acceptorless dehydrogenation (AD), although the turnover frequencies measured using both catalyst precursors are modest. PMID:26916542

  8. A systematic study of actinide production from the interactions of heavy ions with sup 248 Cm

    SciTech Connect

    Leyba, J.D.

    1990-09-07

    Production cross sections for heavy actinides produced from the interactions of {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca ions with {sup 248}Cm were measured at energies ranging from 0.98 to 1.35 X Coulomb barrier. The recoiling reaction products were collected in copper or gold catcher foils located near the {sup 248}Cm target. Separate fractions of Bk, Cf, Es, Fm, and Md were obtained from a radiochemical separation procedure. For the {sup 12}C system, a He/KCl jet was used to transport the recoiling No activities of interest to a rotating wheel system. The isotopic distributions of the actinide products were found to be essentially symmetric about the maximum with full-widths-at-half-maximum of approximately 2.5 mass units. Isotopic distributions of the {sup 12}C, {sup 31}P, {sup 40}Ar, and {sup 44}Ca systems were found to be very similar to the {sup 40,48}Ca systems studied previously. The maxima of the isotopic distributions generally occurred for those reaction channels which involved the exchange of the fewest number of nucleons between the target and projectile for which the calculated excitation energy was a positive quantity. Additionally, the maxima of the excitation functions occurred at those projectile energies which were consistent with the calculated reaction barriers based upon a binary reaction mechanism. The experimental data from the four systems investigated were compared to several models of heavy ion interactions including a damped reaction mechanism, compound nucleus formation and subsequent particle evaporation, and classical partial wave calculations for binary systems.

  9. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    NASA Astrophysics Data System (ADS)

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  10. Isotopic Fractionation of Mg2+(aq), Ca2+(aq), and Fe2+(aq) with Carbonate Minerals

    SciTech Connect

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-15

    Density functional electronic structure calculations are used to compute the equilibrium constant (the isotope fractionation factor) for 26Mg/24Mg and 44Ca/40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 103ln(K) at 25 °C, of -5.3, -1.1, and +1.1 for 26Mg/24Mg exchange between calcite (CaCO3), magnesite (MgCO3), and dolomite (Ca0.5Mg0.5CO3), respectively, and Mg2+(aq), with positive values indicating enrichment in the mineral phase. For 44Ca/40Ca exchange between calcite and Ca2+(aq), the calculations predict values of +1.5 for Ca2+(aq) in six-fold coordination and +4.1 for Ca2+(aq) in seven-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO3)610- and M2+(H2O)6 embedded in a set of fixed atoms representing the 2nd shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using 2 the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe3+-hematite and Fe2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe3+(aq) and Fe2+(aq) species.

  11. Genotoxicity of the anticonvulsant drug phenytoin (PHT): a follow-up study of PHT-untreated epileptic patients. II. Mitotic index (MI) and proliferation kinetics.

    PubMed

    Kaul, A; Goyle, S

    1999-01-01

    The mitotic index and proliferation rate index were investigated to determine the effect of phenytoin (PHT) in cultured blood lymphocytes of epileptics prior to and following administration of PHT over a period of 9 months (grouped in multiples of 3 months) and 40 control subjects (age range 10-30 years). Treatment with PHT brought inhibition of the mitotic index (MI) and proliferation rate index (PRI), which were significantly higher in treated subjects or which were more expressive in treated lymphocytes (P < 0.001) for all the three durations of treatment. In addition, statistically significant heterogeneity of first, second, and third metaphases between the treated, untreated, and control subjects was found. Mean PRI values were used to estimate cell cycle delays, showing the highest effect in treated lymphocytes (P < 0.001). There was no considerable variation between the control and untreated (P > 0.05). The study demonstrates that PHT may be potentially genotoxic and hence the usefulness of MI and PRI in monitoring epileptics on anticonvulsant treatment. PMID:10321412

  12. Non-replicative helicases at the replication fork.

    PubMed

    Heller, Ryan C; Marians, Kenneth J

    2007-07-01

    Reactivation of stalled or collapsed replication forks is an essential process in bacteria. Restart systems operate to restore the 5'-->3' replicative helicase, DnaB, to the lagging-strand template. However, other non-replicative 3'-->5' helicases play an important role in the restart process as well. Here we examine the DNA-binding specificity of three of the latter group, PriA, Rep, and UvrD. Only PriA and Rep display structure-specific fork binding. Interestingly, their specificity is opposite: PriA binds a leading-strand fork, presumably reflecting its restart activity in directing loading of DnaB to the lagging-strand template. Rep binds a lagging-strand fork, presumably reflecting its role in partially displacing Okazaki fragments that originate near the fork junction. This activity is necessary for generating a single-stranded landing pad for DnaB. While UvrD shows little structure-specificity, there is a slight preference for lagging-strand forks, suggesting that there might be some redundancy between Rep and UvrD and possibly explaining the observed synthetic lethality that occurs when mutations in the genes encoding these two proteins are combined. PMID:17382604

  13. Analysis of Seismic Activity of the last 15 Years Nearby Puerto Rico and Caribbean Region.

    NASA Astrophysics Data System (ADS)

    Huerta-Lopez, C. I.; Torres-Ortíz, D. M.; Fernández-Heredia, A. I.; Martínez-Cruzado, J. A.

    2015-12-01

    An earthquake catalog of the seismicity occurred during the last 15 years in the Caribbean region, nearby the vicinity of Puerto Rico Island (PRI) was compiled in order to capture the big picture of the regional seismic activity ratio and in particular at the epicentral regions of several historical and instrumentally recorded (during 2008-20015) large to moderate magnitude earthquakes occurred nearby PRI in onshore and offshore, which include the M6.4 earthquake of 01/13/2014, the largest earthquake recorded instrumentally nearby PRI. From the point of view of joint temporal-spatial distribution of epicenters, episodic temporal-spatial seismic activity is clearly seen as temporal-spatial concentrations during certain time intervals in different regions. These localized concentrations of epicenters that occur during certain time intervals in well localized/concentrated regions may suggest "seismic gaps" that shows no regular time interval, neither spatial pattern. In the epicentral region of the M6.4 01/13/2014 earthquake and the historical Mona Passage M7.5 earthquake of 10/11/1918, episodic concentrations in time and space of small magnitude earthquakes epicenters is evident, however do not show temporal pattern. Preliminary results of statistical analysis of an ongoing research in terms of the parameter b (Gutenberg-Richter relationship), and the Omori's law with the aim to relate the tectonic framework of the region (or sub-regions) such as structural heterogeneity stress are here presented/discussed.

  14. Life cycle of a data warehousing project in healthcare.

    PubMed

    Verma, R; Harper, J

    2001-01-01

    Hill Physicians Medical Group (and its medical management firm, PriMed Management) early on recognized the need for a data warehouse. Management demanded that data from many sources be integrated, cleansed, and formatted. As a first step, an operational data store (ODS) was built and populated with data from the main transactional system; encounter data were added. The ODS has served its purpose well and has whetted management's appetite for more information and faster, more reliable access, all in one location. PriMed hired Annams Systems Consulting (Annams) for this effort. A team was formed, made up of consultants from Annams and members of PriMed's information services (IS) team. The "classical" approach is being taken: enhancing the ODS, which is largely normalized in structure, and integrating data from various sources, along with enforcing business rules. The team is designing and implementing data marts and a "star schema" style of data modeling--a useful tool for management to evaluate results before investing further. PMID:11452573

  15. The use of artificial microRNA technology to control gene expression in Arabidopsis thaliana.

    PubMed

    Eamens, Andrew L; McHale, Marcus; Waterhouse, Peter M

    2014-01-01

    In plants, double-stranded RNA (dsRNA) is an effective trigger of RNA silencing, and several classes of endogenous small RNA (sRNA), processed from dsRNA substrates by DICER-like (DCL) endonucleases, are essential in controlling gene expression. One such sRNA class, the microRNAs (miRNAs) control the expression of closely related genes to regulate all aspects of plant development, including the determination of leaf shape, leaf polarity, flowering time, and floral identity. A single miRNA sRNA silencing signal is processed from a long precursor transcript of nonprotein-coding RNA, termed the primary miRNA (pri-miRNA). A region of the pri-miRNA is partially self-complementary allowing the transcript to fold back onto itself to form a stem-loop structure of imperfectly dsRNA. Artificial miRNA (amiRNA) technology uses endogenous pri-miRNAs, in which the miRNA and miRNA* (passenger strand of the miRNA duplex) sequences have been replaced with corresponding amiRNA/amiRNA* sequences that direct highly efficient RNA silencing of the targeted gene. Here, we describe the rules for amiRNA design, as well as outline the PCR and bacterial cloning procedures involved in the construction of an amiRNA plant expression vector to control target gene expression in Arabidopsis thaliana. PMID:24057368

  16. Monitoring Spring Recovery of Photosynthesis and Spectral Reflectance in Temperate Evergreen and Mixed Deciduous Forests

    NASA Astrophysics Data System (ADS)

    Wong, C. Y.; Arain, M. A.; Ensminger, I.

    2015-12-01

    Evergreen conifers in boreal and temperate regions undergo strong seasonal changes in photoperiod and temperatures, which characterizes their photosynthetic activity with high activity in the growing season and downregulation during the winter season. Monitoring the timing of the transitions in evergreens is difficult since it's a largely invisible process, unlike deciduous trees that have a visible budding and senescence sequence. Spectral reflectance and the photochemical reflectance index (PRI), often used as a proxy for photosynthetic light-use efficiency, provides a promising tool to track the transition of evergreens between inactive and active photosynthetic states. To better understand the relationship between PRI and photosynthetic activity and to contrast this relationship between plant functional types, the spring recovery of an evergreen forest and mixed deciduous forest was monitored using spectral reflectance, chlorophyll fluorescence and gas exchange. All metrics indicate photosynthetic recovery during the spring season. These findings indicate that PRI can be used to observe the spring recovery of photosynthesis in evergreen conifers but may not be best suited for deciduous trees. These findings have implications for remote sensing, which provides a promising long-term monitoring system of whole ecosystems, which is important since their roles in the carbon cycle may shift in response to climate change.

  17. Characterization of function and regulation of miR-24-1 and miR-31

    SciTech Connect

    Sun Fenyong; Wang Jiayi; Pan Qiuhui; Yu Yongchun; Zhang Yue; Wan Yang; Wang Ju; Li Xiaoyan; Hong An

    2009-03-13

    To date, numerous microRNAs (miRNAs) have been discovered. However, the function of these miRNAs is largely unknown. While our knowledge of miRNA post-transcriptional processing has greatly expanded in recent years, we have a limited understanding of the regulation and transcription of miRNA genes. In this study, we characterized two BMP-2 upregulated miRNAs, miR-24-1 and miR-31, in mesenchymal stem cells and showed their opposing function in controlling cellular proliferation, and adipogenesis. Furthermore, we are the first to identify and characterize mouse intronic miR-23b{approx}27b{approx}24-1 and intergenic miR-31 genes. Moreover, we found that pri-miR-23b, pri-miR-27b, and pri-miR-24-1 are transcribed independently and their expression profiles are unique when cells are treated with BMP-2, even though they are located closely together.

  18. Miravirsen (SPC3649) can inhibit the biogenesis of miR-122

    PubMed Central

    Gebert, Luca F. R.; Rebhan, Mario A. E.; Crivelli, Silvia E. M.; Denzler, Rémy; Stoffel, Markus; Hall, Jonathan

    2014-01-01

    MicroRNAs (miRNAs) are short noncoding RNAs, which bind to messenger RNAs and regulate protein expression. The biosynthesis of miRNAs includes two precursors, a primary miRNA transcript (pri-miRNA) and a shorter pre-miRNA, both of which carry a common stem-loop bearing the mature miRNA. MiR-122 is a liver-specific miRNA with an important role in the life cycle of hepatitis C virus (HCV). It is the target of miravirsen (SPC3649), an antimiR drug candidate currently in clinical testing for treatment of HCV infections. Miravirsen is composed of locked nucleic acid (LNAs) ribonucleotides interspaced throughout a DNA phosphorothioate sequence complementary to mature miR-122. The LNA modifications endow the drug with high affinity for its target and provide resistance to nuclease degradation. While miravirsen is thought to work mainly by hybridizing to mature miR-122 and blocking its interaction with HCV RNA, its target sequence is also present in pri- and pre-miR-122. Using new in vitro and cellular assays specifically developed to discover ligands that suppress biogenesis of miR-122, we show that miravirsen binds to the stem-loop structure of pri- and pre-miR-122 with nanomolar affinity, and inhibits both Dicer- and Drosha-mediated processing of miR-122 precursors. This inhibition may contribute to the pharmacological activity of the drug in man. PMID:24068553

  19. Self-Management, Amitriptyline, and Amitripyline plus Triamcinolone in the Management of Vulvodynia

    PubMed Central

    Wan, Jim; Bachmann, Gloria; Rosen, Ray

    2009-01-01

    Abstract Objective To conduct a prospective study to determine the efficacy of self-management interventions, amitriptyline, and amitriptyline plus topical triamcinolone in reducing vulvar pain in women with vulvodynia. Methods This was a randomized, prospective study of 53 women between the ages of 18 and 72 with vulvodynia. Participants undertook one of three treatment interventions for a period of 12 weeks: self-management, oral amitriptyline (10–20 mg/day), or topical triamcinolone plus oral amitriptyline (10–20 mg/day). The McGill Pain Questionnaire (MPQ) was used to measure changes in qualitative pain using the pain rating index (PRI) and in quantitative pain using the present pain intensity (PPI) scale. Results Of the 53 randomized subjects, 43 completed the trial. There were no statistically significant differences in PRI or PPI scores among the three treatment groups. Significant within-group differences were observed in the self-management group on the PRI and in the amitriptyline group on the PPI. Conclusions This first randomized, prospective trial suggests that self-management has a modest effect and that low-dose amitriptyline (with and without topical triamcinolone) is not effective in reducing pain in women with vulvodynia. PMID:19183087

  20. Association analysis of photoperiodic flowering time genes in west and central African sorghum [Sorghum bicolor (L.) Moench

    PubMed Central

    2012-01-01

    Background Photoperiod-sensitive flowering is a key adaptive trait for sorghum (Sorghum bicolor) in West and Central Africa. In this study we performed an association analysis to investigate the effect of polymorphisms within the genes putatively related to variation in flowering time on photoperiod-sensitive flowering in sorghum. For this purpose a genetically characterized panel of 219 sorghum accessions from West and Central Africa was evaluated for their photoperiod response index (PRI) based on two sowing dates under field conditions. Results Sorghum accessions used in our study were genotyped for single nucleotide polymorphisms (SNPs) in six genes putatively involved in the photoperiodic control of flowering time. Applying a mixed model approach and previously-determined population structure parameters to these candidate genes, we found significant associations between several SNPs with PRI for the genes CRYPTOCHROME 1 (CRY1-b1) and GIGANTEA (GI). Conclusions The negative values of Tajima's D, found for the genes of our study, suggested that purifying selection has acted on genes involved in photoperiodic control of flowering time in sorghum. The SNP markers of our study that showed significant associations with PRI can be used to create functional markers to serve as important tools for marker-assisted selection of photoperiod-sensitive cultivars in sorghum. PMID:22394582

  1. Design of a small molecule against an oncogenic noncoding RNA.

    PubMed

    Velagapudi, Sai Pradeep; Cameron, Michael D; Haga, Christopher L; Rosenberg, Laura H; Lafitte, Marie; Duckett, Derek R; Phinney, Donald G; Disney, Matthew D

    2016-05-24

    The design of precision, preclinical therapeutics from sequence is difficult, but advances in this area, particularly those focused on rational design, could quickly transform the sequence of disease-causing gene products into lead modalities. Herein, we describe the use of Inforna, a computational approach that enables the rational design of small molecules targeting RNA to quickly provide a potent modulator of oncogenic microRNA-96 (miR-96). We mined the secondary structure of primary microRNA-96 (pri-miR-96) hairpin precursor against a database of RNA motif-small molecule interactions, which identified modules that bound RNA motifs nearby and in the Drosha processing site. Precise linking of these modules together provided Targaprimir-96 (3), which selectively modulates miR-96 production in cancer cells and triggers apoptosis. Importantly, the compound is ineffective on healthy breast cells, and exogenous overexpression of pri-miR-96 reduced compound potency in breast cancer cells. Chemical Cross-Linking and Isolation by Pull-Down (Chem-CLIP), a small-molecule RNA target validation approach, shows that 3 directly engages pri-miR-96 in breast cancer cells. In vivo, 3 has a favorable pharmacokinetic profile and decreases tumor burden in a mouse model of triple-negative breast cancer. Thus, rational design can quickly produce precision, in vivo bioactive lead small molecules against hard-to-treat cancers by targeting oncogenic noncoding RNAs, advancing a disease-to-gene-to-drug paradigm. PMID:27170187

  2. Prorating WAIS - IV summary scores for patients with relapsing-remitting multiple sclerosis.

    PubMed

    Ryan, Joseph J; Umfleet, Laura Glass; Gontkovsky, Samuel T

    2016-11-01

    We evaluated the utility of prorating appropriate combinations of two, six and eight Wechsler Adult Intelligence Scale - Fourth Edition (WAIS - IV) subtests for estimating the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Full Scale IQ (FSIQ) and General Ability Index (GAI) in a sample of individuals diagnosed with multiple sclerosis (MS). Forty-eight outpatients completed the WAIS - IV and Wechsler Memory Scale - Fourth Edition (WMS - IV) as part of a comprehensive neuropsychological battery. Means for age, education and duration of diagnosis were 42.35, 14.21 and 8.30 years, respectively. Paired t-tests showed no significant differences between prorated and standard means for VCI (93.46 vs. 93.73), PRI (90.19 vs. 89.44), FSIQ (88.53 vs. 88.47) or GAI (90.56 vs. 90.65). Correlations between prorated and standard composites were ≥0.89 in every instance. Correlations between the standard and prorated composites and education, disability status and WMS - IV indexes did not reveal a single contrast, where the correlations were significantly different. The present findings support the use of the two-subtest VCI and PRI composites and the eight-subtest FSIQ and four-subtest GAI in the assessment of patients with MS. PMID:26422128

  3. In-vivo quantification of primary microRNA processing by Drosha with a luciferase based system

    SciTech Connect

    Allegra, Danilo; Mertens, Daniel

    2011-03-25

    Research highlights: {yields} Posttranscriptional regulation of miRNA processing is difficult to quantify. {yields} Our in-vivo processing assay can quantify Drosha cleavage in live cells. {yields} It is based on luciferase reporters fused with pri-miRNAs. {yields} The assay validates the processing defect caused by a mutation in pri-16-1. {yields} It is a sensitive method to quantify pri-miRNA cleavage by Drosha in live cells. -- Abstract: The RNAse III Drosha is responsible for the first step of microRNA maturation, the cleavage of primary miRNA to produce the precursor miRNA. Processing by Drosha is finely regulated and influences the amount of mature microRNA in a cell. We describe in the present work a method to quantify Drosha processing activity in-vivo, which is applicable to any microRNA. With respect to other methods for measuring Drosha activity, our system is faster and scalable, can be used with any cellular system and does not require cell sorting or use of radioactive isotopes. This system is useful to study regulation of Drosha activity in physiological and pathological conditions.

  4. Modified Omega-k Algorithm for High-Speed Platform Highly-Squint Staggered SAR Based on Azimuth Non-Uniform Interpolation

    PubMed Central

    Zeng, Hong-Cheng; Chen, Jie; Liu, Wei; Yang, Wei

    2015-01-01

    In this work, the staggered SAR technique is employed for high-speed platform highly-squint SAR by varying the pulse repetition interval (PRI) as a linear function of range-walk. To focus the staggered SAR data more efficiently, a low-complexity modified Omega-k algorithm is proposed based on a novel method for optimal azimuth non-uniform interpolation, avoiding zero padding in range direction for recovering range cell migration (RCM) and saving in both data storage and computational load. An approximate model on continuous PRI variation with respect to sliding receive-window is employed in the proposed algorithm, leaving a residual phase error only due to the effect of a time-varying Doppler phase caused by staggered SAR. Then, azimuth non-uniform interpolation (ANI) at baseband is carried out to compensate the azimuth non-uniform sampling (ANS) effect resulting from continuous PRI variation, which is further followed by the modified Omega-k algorithm. The proposed algorithm has a significantly lower computational complexity, but with an equally effective imaging performance, as shown in our simulation results. PMID:25664433

  5. Microprocessor mediates transcriptional termination in long noncoding microRNA genes

    PubMed Central

    Dhir, Ashish; Dhir, Somdutta; Proudfoot, Nick J.; Jopling, Catherine L.

    2015-01-01

    MicroRNA (miRNA) play a major role in the post-transcriptional regulation of gene expression. Mammalian miRNA biogenesis begins with co-transcriptional cleavage of RNA polymerase II (Pol II) transcripts by the Microprocessor complex. While most miRNA are located within introns of protein coding genes, a substantial minority of miRNA originate from long non coding (lnc) RNA where transcript processing is largely uncharacterized. We show, by detailed characterization of liver-specific lnc-pri-miR-122 and genome-wide analysis in human cell lines, that most lnc-pri-miRNA do not use the canonical cleavage and polyadenylation (CPA) pathway, but instead use Microprocessor cleavage to terminate transcription. This Microprocessor inactivation leads to extensive transcriptional readthrough of lnc-pri-miRNA and transcriptional interference with downstream genes. Consequently we define a novel RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells. PMID:25730776

  6. Isotope Tracer Studies of Diffusion in Sillicates and of Geological Transport Processes Using Actinide Elements

    SciTech Connect

    Wasserburg, Gerald J

    2008-07-31

    The objectives were directed toward understanding the transport of chemical species in nature, with particular emphasis on aqueous transport in solution, in colloids, and on particles. Major improvements in measuring ultra-low concentrations of rare elements were achieved. We focused on two areas of studies: (1) Field, laboratory, and theoretical studies of the transport and deposition of U, Th isotopes and their daughter products in natural systems; and (2) Study of calcium isotope fractionation effects in marine carbonates and in carbonates precipitated in the laboratory, under controlled temperature, pH, and rates of precipitation. A major study of isotopic fractionation of Ca during calcite growth from solution has been completed and published. It was found that the isotopic shifts widely reported in the literature and attributed to biological processes are in fact due to a small equilibrium fractionation factor that is suppressed by supersaturation of the solution. These effects were demonstrated in the laboratory and with consideration of the solution conditions in natural systems, where [Ca{sup 2+}] >> [CO{sub 3}{sup 2-}] + [HCO{sub 3}{sup -}]. The controlling rate is not the diffusion of Ca, as was earlier proposed, but rather the rate of supply of [CO{sub 3}{sup 2-}] ions to the interface. This now opens the issues of isotopic fractionation of many elements to a more physical-chemical approach. The isotopic composition of Ca {Delta}({sup 44}Ca/{sup 40}Ca) in calcite crystals has been determined relative to that in the parent solutions by TIMS using a double spike. Solutions were exposed to an atmosphere of NH{sub 3} and CO{sub 2}, provided by the decomposition of (NH4)2CO3. Alkalinity, pH, and concentrations of CO{sub 3}{sup 2-}, HCO{sub 3}{sup -}, and CO{sub 2} in solution were determined. The procedures permitted us to determine {Delta}({sup 44}Ca/{sup 40}Ca) over a range of pH conditions, with the associated ranges of alkalinity. Two solutions with

  7. Evolution of Tethyan phosphogenesis along the northern edges of the Arabian--African shield during the Cretaceous--Eocene as deduced from temporal variations of Ca and Nd isotopes and rates of P accumulation

    NASA Astrophysics Data System (ADS)

    Soudry, D.; Glenn, C. R.; Nathan, Y.; Segal, I.; VonderHaar, D.

    2006-09-01

    The evolution of Tethyan phosphogenesis during the Cretaceous-Eocene is examined to try to explain fluctuations of phosphogenesis through time, and whether or not they reflect long-term changes in ocean circulation or in continental weathering. Twenty-seven time-stratigraphic phosphate levels in various Tethyan sites, covering a time span of about 90 Myr from the Hauterivian to the Eocene, were analyzed for 44Ca/ 42Ca and 143Nd/ 144Nd in their carbonate fluorapatite (CFA) fraction. P and Ca accumulation rates and bulk sedimentation rates were quantified throughout the Cretaceous-Eocene Negev sequence to examine how changes in 44Ca/ 42Ca and 143Nd/ 144Nd are reflected in the intensity of phosphogenesis. A clear-cut change occurs in ɛNd( T) and δ44Ca and in the rates of P and Ca accumulation and bulk sedimentation through the time analyzed. ɛNd( T) is much lower in the Hauterivian-Lower Cenomanian (- 12.8 to - 10.9) than in the Upper Cenomanian-Eocene (- 7.8 to - 5.9). Much lower δ44Ca values occur in the Hauterivian-Turonian (- 0.22 to + 0.02) than in the Coniacian-Eocene (+ 0.23 to + 0.40). P accumulation rates in the Negev steeply increase from < 200 μmol cm - 2 k yr - 1 in the Albian-Coniacian to ˜ 1500 μmol cm - 2 k yr - 1 in the Campanian, whereas a strong decrease is concomitantly recorded in the rates of Ca accumulation and bulk sedimentation. In addition, distinct ɛNd( T) values are shown by the phosphorites of the Negev (- 6.7 to - 6.4) and Egypt (- 9.1 to - 7.6) during the Campanian, and by those of the Negev (- 7.8 to - 6.3) and North Africa (- 10.1 to - 8.9) during the Maastrichtian-Eocene. The culmination of P accumulation rates in the Negev during the Campanian, occurring with a high in ɛNd( T) and δ44Ca and a low in sedimentation rates, indicates that paleoceanographic and paleogeographical factors mostly governed phosphorite accumulation in this area. The abrupt ɛNd( T) rise after the Cenomanian is attributed to increased incursion of

  8. Effects of partial root-zone irrigation on hydraulic conductivity in the soil-root system of maize plants.

    PubMed

    Hu, Tiantian; Kang, Shaozhong; Li, Fusheng; Zhang, Jianhua

    2011-08-01

    Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil-root system (L(sr)) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with L(sr) in both the whole and irrigated root zones for all three irrigation methods but not with L(sr) in the non-irrigated root zone of FPRI. The total L(sr) in the irrigated root zone of two PRIs was increased by 49.0-92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of L(sr) in a half root zone to L(sr) in the whole root zone was ∼50%. For FPRI, the L(sr) in the irrigated root zone was close to that of the whole root zone. As for APRI, the L(sr) in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the L(sr) in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The L(sr) in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency. PMID:21527627

  9. Effects of partial root-zone irrigation on hydraulic conductivity in the soil–root system of maize plants

    PubMed Central

    Hu, Tiantian; Kang, Shaozhong; Li, Fusheng; Zhang, Jianhua

    2011-01-01

    Effects of partial root-zone irrigation (PRI) on the hydraulic conductivity in the soil–root system (Lsr) in different root zones were investigated using a pot experiment. Maize plants were raised in split-root containers and irrigated on both halves of the container (conventional irrigation, CI), on one side only (fixed PRI, FPRI), or alternately on one of two sides (alternate PRI, APRI). Results show that crop water consumption was significantly correlated with Lsr in both the whole and irrigated root zones for all three irrigation methods but not with Lsr in the non-irrigated root zone of FPRI. The total Lsr in the irrigated root zone of two PRIs was increased by 49.0–92.0% compared with that in a half root zone of CI, suggesting that PRI has a significant compensatory effect of root water uptake. For CI, the contribution of Lsr in a half root zone to Lsr in the whole root zone was ∼50%. For FPRI, the Lsr in the irrigated root zone was close to that of the whole root zone. As for APRI, the Lsr in the irrigated root zone was greater than that of the non-irrigated root zone. In comparison, the Lsr in the non-irrigated root zone of APRI was much higher than that in the dried zone of FPRI. The Lsr in both the whole and irrigated root zones was linearly correlated with soil moisture in the irrigated root zone for all three irrigation methods. For the two PRI treatments, total water uptake by plants was largely determined by the soil water in the irrigated root zone. Nevertheless, the non-irrigated root zone under APRI also contributed to part of the total crop water uptake, but the continuously non-irrigated root zone under FPRI gradually ceased to contribute to crop water uptake, suggesting that it is the APRI that can make use of all the root system for water uptake, resulting in higher water use efficiency. PMID:21527627

  10. TU-F-12A-03: Using 18F-FDG-PET-CT and Deformable Registration During Head-And-Neck Cancer (HNC) Intensity Modulated Radiotherapy (IMRT) to Predict Treatment Response

    SciTech Connect

    Vergalasova, I; Mowery, Y; Yoo, D; Brizel, D; Das, S

    2014-06-15

    Purpose: To evaluate the effect of deformable vs. rigid registration of pre-treatment 18F-FDG-PET-CT to intra-treatment 18F-FDG-PET-CT on different standardized uptake value (SUV) parameters and investigate which parameters correlate best with post-treatment response in patients undergoing IMRT for HNC. Methods: Pre-treatment and intra-treatment PET-CT (after 20Gy) scans were acquired, in addition to a 12 week post-treatment PET-CT to assess treatment response. Primary and lymph node gross tumor volumes (GTV-PRI and GTV-LN) were contoured on the pre-treatment CT. These contours were then mapped to intra-treatment PET images via rigid and deformable registration. Absolute changes from pre- to intra-treatment scans for rigid and deformable registration were extracted for the following parameters: SUV-MAX, SUV-MEAN, SUV-20%, SUV-40%, and SUV-60% (SUV-X% is the minimum SUV to the highest-intensity X% volume). Results: Thirty-eight patients were evaluated, with 27 available for classification as complete or incomplete response (CR/ICR). The pre-treatment average tumor volumes for the patients were 24.05cm{sup 3} for GTV-PRI and 23.4cm{sup 3} for GTV-LN. For GTV-PRI, there was no statistically significant difference between rigid vs. deformable registration across all ΔSUV parameters. For GTV-LN contours, all parameters were significantly different except for ΔSUV-MAX. For deformably-registered GTV-PRI, changes in the following metrics were significantly different for CR vs. ICR: SUV-MEAN(p=0.003), SUV-20%(p=0.02), SUV-40%(p=0.02), and SUV-60%(p=0.008). The following cutoff values separated CR from ICR with high sensitivity and specificity: ΔSUV-MEAN=1.49, ΔSUV-20%=2.39, ΔSUV-40%=1.80 and ΔSUV-60%=1.31. Corresponding areas under the Receiver Operating Characteristics curve were 0.90, 0.81, 0.81, and 0.85, respectively. Conclusion: Rigidly and deformably registered contours yielded statistically similar SUV parameters for GTV-PRI, but not GTV-LN. This implies that

  11. Dirac-Hartree-Bogoliubov calculation for spherical and deformed hot nuclei: Temperature dependence of the pairing energy and gaps, nuclear deformation, nuclear radii, excitation energy, and entropy

    NASA Astrophysics Data System (ADS)

    Lisboa, R.; Malheiro, M.; Carlson, B. V.

    2016-02-01

    Background: Unbound single-particle states become important in determining the properties of a hot nucleus as its temperature increases. We present relativistic mean field (RMF) for hot nuclei considering not only the self-consistent temperature and density dependence of the self-consistent relativistic mean fields but also the vapor phase that takes into account the unbound nucleon states. Purpose: The temperature dependence of the pairing gaps, nuclear deformation, radii, binding energies, entropy, and caloric curves of spherical and deformed nuclei are obtained in self-consistent RMF calculations up to the limit of existence of the nucleus. Method: We perform Dirac-Hartree-Bogoliubov (DHB) calculations for hot nuclei using a zero-range approximation to the relativistic pairing interaction to calculate proton-proton and neutron-neutron pairing energies and gaps. A vapor subtraction procedure is used to account for unbound states and to remove long range Coulomb repulsion between the hot nucleus and the gas as well as the contribution of the external nucleon gas. Results: We show that p -p and n -n pairing gaps in the S10 channel vanish for low critical temperatures in the range Tcp≈0.6 -1.1 MeV for spherical nuclei such as 90Zr, 124Sn, and 140Ce and for both deformed nuclei 150Sm and 168Er. We found that superconducting phase transition occurs at Tcp=1.03 Δp p(0 ) for 90Zr, Tcp=1.16 Δp p(0 ) for 140Ce, Tcp=0.92 Δp p(0 ) for 150Sm, and Tcp=0.97 Δp p(0 ) for 168Er. The superfluidity phase transition occurs at Tcp=0.72 Δn n(0 ) for 124Sn, Tcp=1.22 Δn n(0 ) for 150Sm, and Tcp=1.13 Δn n(0 ) for 168Er. Thus, the nuclear superfluidity phase—at least for this channel—can only survive at very low nuclear temperatures and this phase transition (when the neutron gap vanishes) always occurs before the superconducting one, where the proton gap is zero. For deformed nuclei the nuclear deformation disappear at temperatures of about Tcs=2.0 -4.0 MeV , well above the

  12. Cross Sections Calculations of ( d, t) Nuclear Reactions up to 50 MeV

    NASA Astrophysics Data System (ADS)

    Tel, E.; Yiğit, M.; Tanır, G.

    2013-04-01

    In nuclear fusion reactions two light atomic nuclei fuse together to form a heavier nucleus. Fusion power is the power generated by nuclear fusion processes. In contrast with fission power, the fusion reaction processes does not produce radioactive nuclides. The fusion will not produce CO2 or SO2. So the fusion energy will not contribute to environmental problems such as particulate pollution and excessive CO2 in the atmosphere. Fusion powered electricity generation was initially believed to be readily achievable, as fission power had been. However, the extreme requirements for continuous reactions and plasma containment led to projections being extended by several decades. In 2010, more than 60 years after the first attempts, commercial power production is still believed to be unlikely before 2050. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. In the fusion reactor, tritium self-sufficiency must be maintained for a commercial power plant. Therefore, for self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. Working out the systematics of ( d, t) nuclear reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. Since the experimental data of charged particle induced reactions are scarce, self-consistent calculation and analyses using nuclear theoretical models are very important. In this study, ( d, t) cross sections for target nuclei 19F, 50Cr, 54Fe, 58Ni, 75As, 89Y, 90Zr, 107Ag, 127I, 197Au and 238U have been investigated up to 50 MeV deuteron energy. The excitation functions for ( d, t) reactions have been calculated by pre-equilibrium reaction mechanism. Calculation results have been also compared with the available measurements in

  13. New approach to analyzing and evaluating cross sections for partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.

    2012-11-15

    The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions-first of all, ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions-is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F{sub 1}, F{sub 2}, F{sub 3}, Horizontal-Ellipsis ; by definition, their values cannot exceed 1.0, 0.5, 0.33, Horizontal-Ellipsis , respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, {sigma}{sup expt}({gamma}, xn) = {sigma}{sup expt}({gamma}, n) + 2{sigma}{sup expt}({gamma}, 2n) + 3{sigma}{sup expt}({gamma}, 3n) + Horizontal-Ellipsis , which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F{sub theor}{sup 1}, F{sub theor}{sup 2}, F{sub theor}{sup 3}, Horizontal-Ellipsis on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial reactions-{sigma}{sup eval}({gamma}, in) = F{sub i}{sup theor}{sigma}{sup expt}({gamma}, xn)-were evaluated for the {sup 90}Zr, {sup 115}In, {sup 112,114,116,117,118,119,120,122,124}Sn, {sup 159}Tb, and {sup 197}Au nuclei.

  14. A Re-Analysis of Historical Los Alamos Critical Assembly Reaction Rate Measurements

    NASA Astrophysics Data System (ADS)

    Kahler, A. C.; MacInnes, M.; Chadwick, M. B.

    2016-02-01

    Starting in the 1950s and continuing into the early 1970s, a number of foil irradiations and fission chamber measurements were made in a variety of Fast critical assemblies at Los Alamos National Laboratory. These include (i) Godiva, a bare HEU spherical assembly; (ii) Flattop-25, a spherical assembly consisting of an HEU core and a natural uranium reflector; (iii) Jezebel, a bare 239Pu assembly; and (iv) Flattop-Pu, a spherical assembly consisting of a 239Pu core and a natural uranium reflector. In most instances the irradiations occur at or near the center of the assembly, but in selected instances data were obtained for a radial traverse extending into the Flattop reflector region. Measurements were made for a number of threshold reactions, including 45Sc(n,2n)44mSc, 51V(n,α)48Sc, 75As(n,2n)74As, 89Y(n,2n)88Y, 90Zr(n,2n)89Zr, 103Rh(n,2n)102gRh, 107Ag(n,2n)106mAg, 169Tm(n,2n)168Tm, 175Lu(n,2n)174Lu, 191Ir(n,2n)190Ir, 197Au(n,2n)196Au, 203Tl(n,2n)202Tl, 204Pb(n,2n)203Pb and 238U(n,2n)237U. Fission ratio data for 238U(n,f)/235U(n,f) and 239Pu(n,f)/235U(n,f) were also obtained. We report C/E values from MCNP6 calculations using ENDF/B-VII.1 and IRDFF-v1.03 cross section data.

  15. Integrated Nucleosynthesis in Neutrino Driven Winds

    SciTech Connect

    Roberts, L F; Woosley, S E; Hoffman, R D

    2010-03-26

    Although they are but a small fraction of the mass ejected in core-collapse supernovae, neutrino-driven winds (NDWs) from nascent proto-neutron stars (PNSs) have the potential to contribute significantly to supernova nucleosynthesis. In previous works, the NDW has been implicated as a possible source of r-process and light p-process isotopes. In this paper we present time-dependent hydrodynamic calculations of nucleosynthesis in the NDW which include accurate weak interaction physics coupled to a full nuclear reaction network. Using two published models of PNS neutrino luminosities, we predict the contribution of the NDW to the integrated nucleosynthetic yield of the entire supernova. For the neutrino luminosity histories considered, no true r-process occurs in the most basic scenario. The wind driven from an older 1.4M{sub {circle_dot}} model for a PNS is moderately neutron-rich at late times however, and produces {sup 87}Rb, {sup 88}Sr, {sup 89}Y, and {sup 90}Zr in near solar proportions relative to oxygen. The wind from a more recently studied 1.27M{sub {circle_dot}} PNS is proton-rich throughout its entire evolution and does not contribute significantly to the abundance of any element. It thus seems very unlikely that the simplest model of the NDW can produce the r-process. At most, it contributes to the production of the N = 50 closed shell elements and some light p-nuclei. In doing so, it may have left a distinctive signature on the abundances in metal poor stars, but the results are sensitive to both uncertain models for the explosion and the masses of the neutron stars involved.

  16. The rp-Process in Neutrino-driven Winds

    NASA Astrophysics Data System (ADS)

    Wanajo, Shinya

    2006-08-01

    Recent hydrodynamic simulations of core-collapse supernovae with accurate neutrino transport suggest that the bulk of the early neutrino-heated ejecta is proton rich, in which the production of some interesting proton-rich nuclei is expected. As suggested in recent nucleosynthesis studies, the rapid proton-capture (rp) process takes place in such proton-rich environments by bypassing the waiting point nuclei with β+-lives of a few minutes via the faster capture of neutrons continuously supplied from the neutrino absorption by protons. In this study, the nucleosynthesis calculations are performed with a wide range of neutrino luminosities and electron fractions (Ye), using semianalytic models of proto-neutron-star winds. The masses of proto-neutron stars are taken to be 1.4 and 2.0 Msolar, where the latter is regarded as the test for somewhat high-entropy winds (about a factor of 2). For Ye>0.52, the neutrino-induced rp-process takes place in many wind trajectories, and p-nuclei up to A~130 are synthesized in interesting amounts. However, 92Mo is somewhat underproduced compared to other p-nuclei with similar mass numbers. For 0.4690Zr that originates from the α-process at higher temperature. The nucleosynthetic yields are averaged over the ejected masses of winds, and further, over the Ye distribution predicted by a recent hydrodynamic simulation of a core-collapse supernova. Comparison of the Ye- and mass-averaged yields to the solar compositions implies that the neutrino-driven winds can potentially be the origin of light p-nuclei up to A~110, including 92,94Mo and 96,98Ru, that cannot be explained by other astrophysical sites.

  17. Integrated Nucleosynthesis in Neutrino-driven Winds

    NASA Astrophysics Data System (ADS)

    Roberts, L. F.; Woosley, S. E.; Hoffman, R. D.

    2010-10-01

    Although they are but a small fraction of the mass ejected in core-collapse supernovae, neutrino-driven winds (NDWs) from nascent proto-neutron stars (PNSs) have the potential to contribute significantly to supernova nucleosynthesis. In previous works, the NDW has been implicated as a possible source of r-process and light p-process isotopes. In this paper, we present time-dependent hydrodynamic calculations of nucleosynthesis in the NDW which include accurate weak interaction physics coupled to a full nuclear reaction network. Using two published models of PNS neutrino luminosities, we predict the contribution of the NDW to the integrated nucleosynthetic yield of the entire supernova. For the neutrino luminosity histories considered, no true r-process occurs in the most basic scenario. The wind driven from an older 1.4 M sun model for a PNS is moderately neutron-rich at late times however, and produces 87Rb, 88Sr, 89Y, and 90Zr in near solar proportions relative to oxygen. The wind from a more recently studied 1.27 M sun PNS is proton-rich throughout its entire evolution and does not contribute significantly to the abundance of any element. It thus seems very unlikely that the simplest model of the NDW can produce the r-process. At most, it contributes to the production of the N = 50 closed shell elements and some light p-nuclei. In doing so, it may have left a distinctive signature on the abundances in metal-poor stars, but the results are sensitive to both uncertain models for the explosion and the masses of the neutron stars involved.

  18. Zirconium—Hafnium Isotope Evidence from Meteorites for the Decoupled Synthesis of Light and Heavy Neutron-rich Nuclei

    NASA Astrophysics Data System (ADS)

    Akram, W.; Schönbächler, M.; Sprung, P.; Vogel, N.

    2013-11-01

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope 96Zr (<=1ɛ in 96Zr/90Zr) for bulk chondrites and CAIs (~2ɛ). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the 96Zr isotope variations are of nucleosynthetic origin. The 96Zr enrichments are coupled with 50Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A <= 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. 96Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M ⊙) SNII.

  19. ZIRCONIUM—HAFNIUM ISOTOPE EVIDENCE FROM METEORITES FOR THE DECOUPLED SYNTHESIS OF LIGHT AND HEAVY NEUTRON-RICH NUCLEI

    SciTech Connect

    Akram, W.; Schönbächler, M.; Sprung, P.; Vogel, N.

    2013-11-10

    Recent work based on analyses of meteorite and terrestrial whole-rock samples showed that the r- and s- process isotopes of Hf were homogeneously distributed throughout the inner solar system. We report new Hf isotope data for Calcium-Aluminum-rich inclusions (CAIs) of the CV3 carbonaceous chondrite Allende, and novel high-precision Zr isotope data for these CAIs and three carbonaceous chondrites (CM, CO, CK). Our Zr data reveal enrichments in the neutron-rich isotope {sup 96}Zr (≤1ε in {sup 96}Zr/{sup 90}Zr) for bulk chondrites and CAIs (∼2ε). Potential isotope effects due to incomplete sample dissolution, galactic and cosmic ray spallation, and the nuclear field shift are assessed and excluded, leading to the conclusion that the {sup 96}Zr isotope variations are of nucleosynthetic origin. The {sup 96}Zr enrichments are coupled with {sup 50}Ti excesses suggesting that both nuclides were produced in the same astrophysical environment. The same CAIs also exhibit deficits in r-process Hf isotopes, which provides strong evidence for a decoupling between the nucleosynthetic processes that produce the light (A ≤ 130) and heavy (A > 130) neutron-rich isotopes. We propose that the light neutron-capture isotopes largely formed in Type II supernovae (SNeII) with higher mass progenitors than the supernovae that produced the heavy r-process isotopes. In the context of our model, the light isotopes (e.g. {sup 96}Zr) are predominantly synthesized via charged-particle reactions in a high entropy wind environment, in which Hf isotopes are not produced. Collectively, our data indicates that CAIs sampled an excess of materials produced in a normal mass (12-25 M{sub ☉}) SNII.

  20. Dipole-Strength Distributions up to the Giant Dipole Resonance Deduced from Photon Scattering

    NASA Astrophysics Data System (ADS)

    Schwengner, R.; Rusev, G.; Benouaret, N.; Beyer, R.; Dönau, F.; Erhard, M.; Grosse, E.; Junghans, A. R.; Kosev, K.; Klug, J.; Nair, C.; Nankov, N.; Schilling, K. D.; Wagner, A.

    2008-04-01

    Dipole-strength distributions up to the neutron-separation energies of the even-mass Mo isotopes from 92Mo to 100Mo and of the N = 50 isotones 88Sr, 89Y, 90Zr have been investigated in photon-scattering experiments using the bremsstrahlung facility at the superconducting electron accelerator ELBE of the Forschungszentrum Dresden-Rossendorf. A measurement using polarised bremsstrahlung impinging on 88Sr revealed that all resolved transitions with energies greater than 6 MeV in this nuclide except for one are E1 transitions. The intensity distributions obtained from the measured spectra after a correction for detector response and a subtraction of atomic background in the target contain a continuum part in addition to the resolved peaks. It turns out that the dipole strength in the resolved peaks amounts to about 30% of the total dipole strength while the continuum contains about 70%. In order to estimate the distribution of inelastic transitions and to correct the ground-state transitions for their branching ratios simulations of γ-ray cascades were performed. The photoabsorption cross sections obtained in this way connect smoothly to (γ, n) cross sections and give novel information about the strength on the low-energy tails of the Giant Dipole Resonances below the neutron-separation energies. The experimental cross sections are compared with predictions of a Quasiparticle-Random-Phase Approximation in a deformed basis. The calculations describe the experimentally observed increase of the dipole strengths with increasing neutron number of the Mo isotopes as a consequence of increasing nuclear deformation.

  1. Formation and geochemical significance of micrometallic aggregates including fissiogenic platinum group elements in the Oklo natural reactor, Gabon

    NASA Astrophysics Data System (ADS)

    Kikuchi, Makiko; Hidaka, Hiroshi; Gauthier-Lafaye, François

    2010-08-01

    Metallic aggregates with a size of a few tens μm and consisting mainly of Ru, Rh, Pd, Te, Pb, As, Sb, S and Bi were found in the acid residue of SD37-S2/CD uraninite taken from Oklo natural reactor zone (RZ) 13. Quantitative analyses of major elements using an electron probe microanalyzer and in situ isotopic analyses of Zr, Mo, Ru, Pb and U using a sensitive high-resolution ion microprobe were performed on the metallic aggregates to determine the geochemical behaviors of fission products and actinides and to ascertain the processes of formation of the aggregates in the RZs. The chemical compositions of the aggregates investigated in this study are significantly different from those reported previously, showing lower Pb content and no correlation between the contents of Pb and S in the individual grains. The 235U/ 238U ratios in metallic aggregates vary significantly from 0.00478 to 0.01466, indicating chemical fractionation between U and Pu during the formation of the aggregates. The Pb isotopic data indicate that most of the Pb in the aggregates decayed from 2.05 Ga-old uraninite that existed in the RZ originally and that there was chemical fractionation between U and Pb in some aggregates. The Zr and Mo isotopic ratios, 90Zr/ 91Zr and 95Mo/ 97Mo, for most of the aggregates had small variations, which can be simply explained by constant separate mixing of fissiogenic and nonfissiogenic components. On the other hand, a large variation in the 99Ru/ 101Ru ratio (0.324-1.73) cannot be explained only by a two component mixing theory; thus, chemical fractionation between Tc and Ru during the reactor criticality is suggested. The large variations in the 235U/ 238U and 99Ru/ 101Ru isotopic ratios suggest that the aggregates formed under various redox conditions owing to the radiolysis of water.

  2. Capture cross sections for the astrophysical p process

    NASA Astrophysics Data System (ADS)

    Quinn, Stephen J.

    This dissertation includes the design and development of the Summing NaI (SuN) 4pi gamma-ray detector at the National Superconducting Cyclotron Laboratory to measure proton and alpha radiative capture reactions relevant in the astrophysical p process. Discussions of p-process nucleosynthesis, the relevant nuclear reaction theory, experimental details, and analysis procedures are included. All reaction measurements were performed at the Nuclear Science Laboratory of the University of Notre Dame. The commissioning experiments in both regular and inverse kinematics were done using known resonances in the 27Al(p,gamma)28Si and 58Ni(p,gamma) 59Cu reactions, and the results agree well with previous literature values. The success of these proof-of-principle measurements marks the first time that the gamma-summing technique has been implemented in inverse kinematics. Furthermore, in an effort to investigate the synthesis of the light p-process nuclei, the 74Ge(p,gamma)75As, 74Ge(alpha,gamma) 78Se, and 90,92Zr(alpha,gamma)94,96Mo reactions were measured and compared to theoretical calculations using the nuclear statistical model. It was found that the new 74Ge(p,gamma) 75As measurements cause an enhancement in the overproduction of 74Se in p-process models, and that the updated 90Zr(alpha,gamma) 94Mo reaction rate seems to confirms the p-process branching point at 94Mo. Finally, the 58Ni(alpha,gamma) 62Zn reaction was measured for its role in nucleosynthesis in type Ia supernovae. The measurements here lower the reaction rate used in astrophysical models, which leads to a 5% reduction in the calculated abundances of several isotopes. All of the measurements in this dissertation greatly reduce the uncertainty in the reaction cross section.

  3. Global investigation of the fine structure of the isoscalar giant quadrupole resonance

    SciTech Connect

    Shevchenko, A.; Burda, O.; Kalmykov, Y.; Neumann-Cosel, P. von; Ponomarev, V. Yu.; Richter, A.; Wambach, J.; Carter, J.; Sideras-Haddad, E.; Cooper, G. R. J.; Fearick, R. W.; Foertsch, S. V.; Lawrie, J. J.; Neveling, R.; Smit, F. D.; Fujita, H.; Fujita, Y.; Lacroix, D.

    2009-04-15

    Fine structure in the region of the isoscalar giant quadrupole resonance (ISGQR) in {sup 58}Ni, {sup 89}Y, {sup 90}Zr, {sup 120}Sn, {sup 166}Er, and {sup 208}Pb has been observed in high-energy-resolution ({delta}E{sub 1/2}{approx_equal}35-50 keV) inelastic proton scattering measurements at E{sub 0}=200 MeV at iThemba LABS. Calculations of the corresponding quadrupole excitation strength functions performed within models based on the random-phase approximation (RPA) reveal similar fine structure when the mixing of one-particle one-hole states with two-particle two-hole states is taken into account. A detailed comparison of the experimental data is made with results from the quasiparticle-phonon model (QPM) and the extended time-dependent Hartree-Fock (ETDHF) method. For {sup 208}Pb, additional theoretical results from second RPA and the extended theory of finite Fermi systems (ETFFS) are discussed. A continuous wavelet analysis of the experimental and the calculated spectra is used to extract dominant scales characterizing the fine structure. Although the calculations agree with qualitative features of these scales, considerable differences are found between the model and experimental results and amongst different models. Within the framework of the QPM and ETDHF calculations it is possible to decompose the model spaces into subspaces approximately corresponding to different damping mechanisms. It is demonstrated that characteristic scales mainly arise from the collective coupling of the ISGQR to low-energy surface vibrations.

  4. Experimental study of the 66Ni(d ,p ) 67Ni one-neutron transfer reaction

    NASA Astrophysics Data System (ADS)

    Diriken, J.; Patronis, N.; Andreyev, A.; Antalic, S.; Bildstein, V.; Blazhev, A.; Darby, I. G.; De Witte, H.; Eberth, J.; Elseviers, J.; Fedosseev, V. N.; Flavigny, F.; Fransen, Ch.; Georgiev, G.; Gernhauser, R.; Hess, H.; Huyse, M.; Jolie, J.; Kröll, Th.; Krücken, R.; Lutter, R.; Marsh, B. A.; Mertzimekis, T.; Muecher, D.; Orlandi, R.; Pakou, A.; Raabe, R.; Randisi, G.; Reiter, P.; Roger, T.; Seidlitz, M.; Seliverstov, M.; Sotty, C.; Tornqvist, H.; Van De Walle, J.; Van Duppen, P.; Voulot, D.; Warr, N.; Wenander, F.; Wimmer, K.

    2015-05-01

    The quasi-SU(3) sequence of the positive parity ν g9 /2,d5 /2,s1 /2 orbitals above the N =40 shell gap are assumed to induce strong quadrupole collectivity in the neutron-rich Fe (Z =26 ) and Cr (Z =24 ) isotopes below the nickel region. In this paper the position and strength of these single-particle orbitals are characterized in the neighborhood of 68Ni (Z =28 ,N =40 ) through the 66Ni(d ,p )67Ni one-neutron transfer reaction at 2.95 MeV/nucleon in inverse kinematics, performed at the REX-ISOLDE facility in CERN. A combination of the Miniball γ -array and T-REX particle-detection setup was used and a delayed coincidence technique was employed to investigate the 13.3-μ s isomer at 1007 keV in 67Ni. Excited states up to an excitation energy of 5.8 MeV have been populated. Feeding of the ν g9 /2 (1007 keV) and ν d5 /2 (2207 keV and 3277 keV) positive-parity neutron states and negative parity (ν p f ) states have been observed at low excitation energy. The extracted relative spectroscopic factors, based on a distorted-wave Born approximation analysis, show that the ν d5 /2 single-particle strength is mostly split over these two excited states. The results are also compared to the distribution of the proton single-particle strength in the 90Zr region (Z =40 ,N =50 ) .

  5. Global optical potential for nucleus-nucleus systems from 50 MeV/u to 400 MeV/u

    NASA Astrophysics Data System (ADS)

    Furumoto, T.; Horiuchi, W.; Takashina, M.; Yamamoto, Y.; Sakuragi, Y.

    2012-04-01

    We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of 50-400 MeV/u. The GOP is derived from the microscopic folding model with the complex G-matrix interaction CEG07 and the global density presented by the São Paulo group. The folding model accounts for realistic complex optical potentials of nucleus-nucleus systems well and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, 8-22C, 12-24O, 16-38Ne, 20-40Mg, 22-48Si, 26-52S, 30-62Ar, and 34-70Ca, scattered by stable target nuclei of 12C, 16O, 28Si, 40Ca 58Ni, 90Zr, 120Sn, and 208Pb at incident energies of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers, and the projectile atomic number, while the range parameters depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.

  6. Photo-neutron Cross Section Calculations of Several Structural Fusion Materials

    NASA Astrophysics Data System (ADS)

    Kaplan, A.; Özdoğan, H.; Aydın, A.; Tel, E.

    2013-06-01

    In this study, the theoretical photo-neutron cross-sections produced by (γ,n) reactions for several structural fusion materials such as 51V, 55Mn, 58Ni, 90,91,92,94Zr, and 181Ta have been investigated in the incident energy range of 7-40 MeV. Reaction cross-sections as a function of photon energy have been calculated theoretically using the PCROSS and TALYS 1.2 computer codes. TALYS 1.2 default and pre-equilibrium models have been used to calculate the pre-equilibrium photo-neutron cross-sections. For the reaction equilibrium component, PCROSS Weisskopf-Ewing model calculations have been preferred. The calculated results have been compared with each other and against the experimental data in the existing databases EXFOR and TENDL-2011. PCROSS Weisskopf-Ewing model calculations show a similar structure with experimental data but they are higher than the experimental values for all reactions except for 90Zr(γ,n)89Zr reaction. Generally, TALYS 1.2 default and pre-equilibrium model cross-section calculations are the best agreement with the experimental data for all reactions except for 58Ni(γ,n)57Ni reaction along the incident photon energy in this study. The TALYS 1.2 curves fit the TENDL-2011 data the best. If photo-neutron cross-section data is needed for an isotope where there is no experimental data available for comparison, TALYS 1.2 pre-equilibrium option has been recommended.

  7. Ca-Mg-Sr-Nd Isotopes in Granitic Rocks of the Lhasa Terrane, Southern Tibet

    NASA Astrophysics Data System (ADS)

    Peterson, B. T.; Simon, J. I.; Depaolo, D. J.; Christensen, J. N.; Harrison, T. M.

    2010-12-01

    Magnesium (Mg) and Calcium (Ca) isotopes are fractionated by aqueous precipitation and incongruent silicate weathering, resulting in sedimentary reservoirs with characteristic isotopic compositions. Limestones and dolomites are isotopically light in both elements, whereas shales/pelites can have heavy Mg and light Ca. The isotopic character of these reservoirs may persist through anatexis (Shen, et al., PNAS 106(49), 2009). Mg and Ca isotopes could therefore be used to gain new insights into the sources of granitic magmas and hence the mechanisms by which the continental crust forms and evolves. Radiogenic 40Ca gives additional information about the K/Ca ratios of magma sources, and Sr and Nd isotopes provide complementary age and lithology information. To evaluate the potential of Ca and Mg isotopes for studying granite petrogenesis we made measurements on a suite of granitic intrusive rocks of Jurassic to Miocene age in southern Tibet that exhibit large variations in Nd (ɛNd = +5 to -12) and Sr isotopes (87Sr/86Sr = 0.704 to 0.722). Our samples represent a transect northward from the Indus-Yalu Suture (IS), west of Lhasa. Rocks close to the IS have mantle-like Nd and Sr isotopic compositions, whereas those farther to the north have low ɛNd and higher 87Sr/86Sr, and include Mesozoic, Paleogene and Neogene peraluminous (2-mica) granites (DePaolo, et al., Goldschmidt, 2008; Kapp, et al., JGR 110, 2005; Hou et al., EPSL 220, 2004). Radiogenic 40Ca is detectable in peraluminous (2-mica) granites and correlates with high 87Sr/86Sr, but does not correlate with Nd isotopes, indicating that 2-mica granite magmas come from both low-K and high-K sources. Stable isotopes of both Ca and Mg show substantial variation. Relative to bulk silicate Earth (BSE, which we define as δ=0 for discussion) δ44Ca values vary from 0 to -0.7, and δ26Mg varies from -0.3 to +0.6. Thus to first order Ca is light and Mg is heavy relative to BSE. For samples with mantle-like Nd and Sr, δ44Ca

  8. Validation of Isotope Data in the World of Interdisciplinary Science: A Cautionary Tale

    NASA Astrophysics Data System (ADS)

    Bullen, T.; Skulan, J.; Anbar, A.

    2007-05-01

    Isotope geoscientists, as well as their colleagues in the geologic, hydrologic and biologic science communities, generally have great confidence in both the precision and accuracy of their isotopic data. Moreover, isotope geoscientists are increasingly realizing the potential of their isotope tracing techniques to be used in applied studies in other research disciplines, such as clinical medicine and forensic science. However, researchers in these other disciplines may not have the same confidence in the quality of isotope data as applied to their field of study, due to either lack of familiarity with the techniques or cultural differences in research approach. For example, in a recent attempt to publish a manuscript in which we described the use of Ca stable isotopes in urine to assess the effects of bedrest on bone loss in human subjects, we were confronted by a reviewer who challenged the validity of our isotope data as measured in the urine matrix. In response to this reviewer's concerns, we developed a supplemental study to demonstrate that we were indeed obtaining `the right answer` on the urine samples with the double-spiking, thermal ionization mass spectrometry technique used for the study. First, using the two urine samples from the dataset that had the lightest and heaviest Ca isotope compositions observed in the study (i.e., δ44Ca of -1.72‰ and +0.36‰ relative to seawater), we generated a series of mixtures of the lighter sample with seawater (δ44Ca = 0‰) and the heavier sample with NIST SRM 915a (δ44Ca = -2.01‰). In each case, the amount of standard added to each sample was minute, thus maintaining the urine matrix. Measured Ca isotope compositions agreed with those calculated assuming a simple mixing relationship, confirming the lack of a matrix effect on the accuracy of the data. Second, in order to test the robustness of the double spiking approach, we analyzed the two urine samples under optimally-spiked, under-spiked and over

  9. Experimental investigation of Ca isotopic fractionation during abiotic gypsum precipitation

    NASA Astrophysics Data System (ADS)

    Harouaka, Khadouja; Eisenhauer, Anton; Fantle, Matthew S.

    2014-03-01

    Experiments investigating Ca isotopic fractionation during gypsum precipitation were undertaken in order to elucidate the mechanisms and conditions that govern isotopic fractionation during mineral precipitation. Both stirred and unstirred free drift gypsum precipitation experiments were conducted at constant initial ionic strength (0.6 M) and variable initial saturation states (4.8-1.5) and Ca2+:SO42- ratios (3 and 0.33). Experimental durations varied between 0.5 and 190 h, while temperature (25.9-24.0 °C), pH (5.8-5.4) and ionic strength (0.6-0.5) were relatively constant. In all experiments, 20-80% of the initial dissolved Ca reservoir was precipitated. Isotopically light Ca preferentially partitioned into the precipitated gypsum; the effective isotopic fractionation factor (Δ44/40Cas-f = δ44/40Casolid - δ44/40Cafluid) of the experimental gypsum ranged from -2.25‰ to -0.82‰. The log weight-averaged, surface area normalized precipitation rates correlated with saturation state and varied between 4.6 and 2.0 μmol/m2/h. The crystal size and aspect ratios, determined by SEM images, BET surface area, and particle size measurements, co-varied with precipitation rate, such that fast growth produced small (10-20 μm), tabular crystals and slow growth produced larger (>1000 μm), needle shaped crystals. Mass balance derived δ44Cas and Δ44Cas-f, calculated using the initial fluid δ44Ca and the mass fraction of Ca removed during precipitation (fCa) as constraints, suggest that the precipitate was not always sampled homogeneously due to the need to preserve the sample for SEM, surface area, and particle size analyses. The fractionation factor (αs-f), derived from Rayleigh model fits to the fluid and calculated bulk solid, ranged from 0.9985 to 0.9988 in stirred experiments and 0.9987 to 0.9992 in unstirred experiments. The αs-f demonstrated no clear dependence on either precipitation rate or initial saturation state in stirred reactors, but exhibited a positive

  10. ADAR2-Mediated Editing of miR-214 and miR-122 Precursor and Antisense RNA Transcripts in Liver Cancers

    PubMed Central

    Liu, Wan-Hsin; Chen, Chao-Hung; Yeh, Kun-Huei; Li, Chiao-Ling; Wu, Yi-Jinn; Chen, Ding-Shinn; Chen, Pei-Jer; Yeh, Shiou-Hwei

    2013-01-01

    A growing list of microRNAs (miRNAs) show aberrant expression patterns in hepatocellular carcinoma (HCC), but the regulatory mechanisms largely remain unclear. RNA editing catalyzed by members of the adenosine deaminase acting on the RNA (ADAR) family could target the miRNA precursors and affect the biogenesis process. Therefore, we investigate whether RNA editing could be one mechanism contributing to the deregulation of specific miRNAs in HCC. By overexpression of individual ADARs in hepatoma cells, RNA editing on the precursors of 16 miRNAs frequently deregulated in HCC was screened by a sensitive high-resolution melting platform. The results identified RNA precursors of miR-214 and miR-122 as potential targets edited by ADAR2. A subset of HCC showing elevated ADAR2 verified the major editings identified in ARAR2 overexpressed hepatoma cells, either with A-to-I or U-to-C changes. The unusual U-to-C editing at specific residues was demonstrated as being attributed to the A-to-I editing on the RNA transcripts complementary to the pri-miRNAs. The editing event caused a decrease of the RNA transcript complementary to pri-miR-214, which led to the decrease of pri-miR-214 and miR-214 and resulted in the increased protein level of its novel target gene Rab15. In conclusion, the current study discovered ADAR2-mediated editing of the complementary antisense transcripts as a novel mechanism for regulating the biogenesis of specific miRNAs during hepatocarcinogenesis. PMID:24386085

  11. Computationally predicting protein-RNA interactions using only positive and unlabeled examples.

    PubMed

    Cheng, Zhanzhan; Zhou, Shuigeng; Guan, Jihong

    2015-06-01

    Protein-RNA interactions (PRIs) are considerably important in a wide variety of cellular processes, ranging from transcriptional and post-transcriptional regulations of gene expression to the active defense of host against virus. With the development of high throughput technology, large amounts of PRI information is available for computationally predicting unknown PRIs. In recent years, a number of computational methods for predicting PRIs have been developed in the literature, which usually artificially construct negative samples based on verified nonredundant datasets of PRIs to train classifiers. However, such negative samples are not real negative samples, some even may be unknown positive samples. Consequently, the classifiers trained with such training datasets cannot achieve satisfactory prediction performance. In this paper, we propose a novel method PRIPU that employs biased-support vector machine (SVM) for predicting Protein-RNA Interactions using only Positive and Unlabeled examples. To the best of our knowledge, this is the first work that predicts PRIs using only positive and unlabeled samples. We first collect known PRIs as our benchmark datasets and extract sequence-based features to represent each PRI. To reduce the dimension of feature vectors for lowering computational cost, we select a subset of features by a filter-based feature selection method. Then, biased-SVM is employed to train prediction models with different PRI datasets. To evaluate the new method, we also propose a new performance measure called explicit positive recall (EPR), which is specifically suitable for the task of learning positive and unlabeled data. Experimental results over three datasets show that our method not only outperforms four existing methods, but also is able to predict unknown PRIs. Source code, datasets and related documents of PRIPU are available at: http://admis.fudan.edu.cn/projects/pripu.htm . PMID:25790785

  12. Remote estimation of net CO2 emission from boreal ecosystems

    NASA Astrophysics Data System (ADS)

    Rogers, C. A.; Strachan, I. B.

    2010-12-01

    Hydroelectricity is the main source of power in the province of Quebec, Canada. While hydroelectricity is considered to be a relatively green source of energy, reservoir creation is a land use change that involves flooding terrestrial ecosystems and thus a loss of greenhouse gas (GHG) uptake as well as direct GHG emission from decomposing vegetation. Both the lost sink for GHGs and direct emission from the reservoir surface must be included in estimating the net GHG emission attributable to the reservoir’s construction. These emissions can be determined using techniques such as eddy covariance, however, such methods are often costly and time consuming, and require frequent access to remote locations. Remote sensing is able to provide spatially continuous data over large areas, minimizing the need for ground based measurements. We tested the ability of the photochemical reflectance index (PRI) and normalized difference vegetation index (NDVI) to predict fluxes of carbon dioxide in areas representative of boreal forests and peatlands flooded by the Eastmain 1 hydroelectric reservoir in the James Bay region of Quebec, Canada. We collected spectral measurements from hand-held and helicopter-based platforms, as well as continuously monitored the indices PRI and NDVI from tower-mounted sensors at a forest and peatland site. We then compared the vegetation indices to net fluxes of carbon dioxide measured by eddy covariance at each site. PRI was related to fluxes at both the forest and peatland sites, suggesting it is possible to remotely estimate carbon dioxide uptake by vegetation in boreal forests and peatlands and thus greenhouse gas emissions resulting from land use changes in boreal regions, such as reservoir inundation.

  13. Identification of hairy root loci in the T-regions of Agrobacterium rhizogenes Ri plasmids.

    PubMed

    Boulanger, F; Berkaloff, A; Richaud, F

    1986-07-01

    Agrobacterium rhizogenes induces root formation at the wound site of inoculation in plants and inserts a fragment of its plasmid (Ri) into the plant nuclear DNA. Parts of the transferred region (T-region) of the Ri plasmid of A. rhizogenes strain A4 or 8196 are cloned in Escherichia coli. Insertions of the E. coli lacZ coding region into the hybrid plasmids were made in vivo using transduction by miniMu. Twenty insertions localized in the TL-DNA of pRiA4 (or pRi1855) and 2 inserts in the T-DNA of pRi8196 were obtained in E. coli. One of the TL-DNA insertions is saved up because it is linked to an internal T-DNA deletion; the others because they confer a lactose plus phenotype on E. coli; this indicates that the T-DNA harbours sequences that are expressed in E. coli. Fifteen of these T-DNA insertions were transfered to Agrobacterium where they substitute the corresponding wild-type T-DNA of the Ri plasmid by homologous recombination. These strains corresponding to insertion-directed mutagenesis were used to inoculate Daucus carota slices and stems and leaves of Kalanchoe daigremontiana. The two insertions strains obtained in the T-DNA of pRi8196 are avirulent on K. daigremontiana; but their phenotypes differ on D. carota slices, suggesting that insertions affect distinct loci on the T-DNA involved in hairy root formation. Only one insertion out of the twenty obtained in the TL-DNA of pRiA4 (or 1855) induces a loss of virulence on leaves of K. daigremontiana. However the TL-DNA deletion harbouring strain induces a loss of virulence on D. carota and K. daigremontiana (stems and leaves), confirming the importance of the TL-DNA for hairy root induction. re]19850711 rv]19851230 ac]19860114. PMID:24307326

  14. Disaggregation of Remotely Sensed Soil Moisture in Heterogeneous Landscapes Using Holistic Structure-Based Models

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Subit; Judge, Jasmeet; Bongiovanni, Tara; Rangarajan, Anand; Ranka, Sanjay

    2016-08-01

    In this study, a novel machine learning algorithm is presented for disaggregation of satellite soil moisture (SM) based on self-regularized regressive models (SRRM) using high-resolution correlated information from auxiliary sources. It includes regularized clustering that assigns soft memberships to each pixel at fine-scale followed by a kernel regression that computes the value of the desired variable at all pixels. Coarse-scale remotely sensed SM were disaggregated from 10km to 1km using land cover, precipitation, land surface temperature, leaf area index, and in-situ observations of SM. This algorithm was evaluated using multi-scale synthetic observations in NC Florida for heterogeneous agricultural land covers. It was found that the root mean square error (RMSE) for 96% of the pixels was less than 0.02 $m^3/m^3$. The clusters generated represented the data well and reduced the RMSE by upto 40% during periods of high heterogeneity in land-cover and meteorological conditions. The Kullback Leibler divergence (KLD) between the true SM and the disaggregated estimates is close to 0, for both vegetated and baresoil landcovers. The disaggregated estimates were compared to those generated by the Principle of Relevant Information (PRI) method. The RMSE for the PRI disaggregated estimates is higher than the RMSE for the SRRM on each day of the season. The KLD of the disaggregated estimates generated by the SRRM is at least four orders of magnitude lower than those for the PRI disaggregated estimates, while the computational time needed was reduced by three times. The results indicate that the SRRM can be used for disaggregating SM with complex non-linear correlations on a grid with high accuracy.

  15. Hysteretic pinching of human secondary osteons subjected to torsion.

    PubMed

    Ascenzi, Maria-Grazia; Di Comite, Mariasevera; Mitov, Plamen; Kabo, John Michael

    2007-01-01

    The mechanical behavior of bone tissue's ultra- and micro- structure is fundamental to assessment of macroscopic bone mechanics. This paper explores the ultra-structural characteristics of human femoral tissue responsible for energy absorption of secondary osteons under mechanical loading. A novel mathematical interpretation of single osteon mechanics elucidates the behavior of the collagen-apatite interface. Fully calcified single osteon specimens were mechanically tested quasi-statically under cyclic torsional loading about their longitudinal axis. On each hysteretic diagram, all cycles after the initial monotonic cycle appear pinched and share two points. Stiffness degradation and pinching degradation were investigated on the torque versus deflection-angle-per-unit-length diagrams as the number of cycles increases, in relation to the appearance of osteons in cross-section under circularly polarized light microscopy. Material science's Bauschinger effect, originally defined for metals and later extended to structures reinforced with metal bars, is adapted to describe pinching. Material science's prying effect, defined as amplification of eccentric tensile load through lever action, is employed to explain pinching. The presence of the two points shared by all complete cycles is analyzed in terms of the mathematical fixed point theorem. The results allow formulation of the following conjectures: (1) the prying of carbonated apatite crystallites at the interface with the 40 nm long bands of non-calcified collagen fibrils causes pinching; (2) the prying effect increases with the increasing percentage of collagen-apatite elements that form a larger angle with the osteon axis; and (3) micro-cracks increase more in number than in length as the number of cycles increases. PMID:17399724

  16. University woodwind students’ experiences with playing-related injuries and their management: a pilot study

    PubMed Central

    Stanhope, Jessica; Milanese, Steve; Grimmer, Karen

    2014-01-01

    Background This study aimed to determine the experiences of university classical woodwind students with playing-related injuries (PRIs), the impact of these PRIs, the management selected by students with PRIs, and the perceived effectiveness of this management. Materials and methods All classical woodwind students enrolled in vocational education training or undergraduate courses at a university were sent an email with a link to an online survey. Only those aged 18 years and older were eligible. The survey obtained data regarding demographic information, details of PRI experienced (location, if they lasted for more than 3 months, and if they were current), and the impact of these, as well as the types of management strategies tried and their perceived effectiveness. Data were analyzed using descriptive statistics, and comments were reported descriptively. Results Fourteen students returned the survey; however, one of these only completed the questions regarding demographics, and was therefore excluded. A total of 62% of participants reported having experienced a PRI. Common locations for PRI were the wrist/hand/fingers, lower back, and neck. Reducing practice time by half and missing playing commitments were the most commonly reported consequences of PRIs. Playing-related management strategies were most frequently trialed, with these and passive nonplaying-related strategies perceived to be the most effective. Conclusion PRIs are common in this population, with a range of consequences reported. While it is encouraging that students had tried and found effective playing-related management strategies, active nonplaying-related strategies should be encouraged, particularly in preference to passive nonplaying-related strategies. This was a small-scale study, and the results are only applicable to the institution investigated; therefore, similar larger-scale studies are recommended to determine the generalizability of these findings. PMID:24634587

  17. RecG Directs DNA Synthesis during Double-Strand Break Repair

    PubMed Central

    Azeroglu, Benura; Mawer, Julia S. P.; Cockram, Charlotte A.; White, Martin A.; Hasan, A. M. Mahedi; Filatenkova, Milana; Leach, David R. F.

    2016-01-01

    Homologous recombination provides a mechanism of DNA double-strand break repair (DSBR) that requires an intact, homologous template for DNA synthesis. When DNA synthesis associated with DSBR is convergent, the broken DNA strands are replaced and repair is accurate. However, if divergent DNA synthesis is established, over-replication of flanking DNA may occur with deleterious consequences. The RecG protein of Escherichia coli is a helicase and translocase that can re-model 3-way and 4-way DNA structures such as replication forks and Holliday junctions. However, the primary role of RecG in live cells has remained elusive. Here we show that, in the absence of RecG, attempted DSBR is accompanied by divergent DNA replication at the site of an induced chromosomal DNA double-strand break. Furthermore, DNA double-stand ends are generated in a recG mutant at sites known to block replication forks. These double-strand ends, also trigger DSBR and the divergent DNA replication characteristic of this mutant, which can explain over-replication of the terminus region of the chromosome. The loss of DNA associated with unwinding joint molecules previously observed in the absence of RuvAB and RecG, is suppressed by a helicase deficient PriA mutation (priA300), arguing that the action of RecG ensures that PriA is bound correctly on D-loops to direct DNA replication rather than to unwind joint molecules. This has led us to put forward a revised model of homologous recombination in which the re-modelling of branched intermediates by RecG plays a fundamental role in directing DNA synthesis and thus maintaining genomic stability. PMID:26872352

  18. Premagnetization for Enhancing the Reactivity of Multiple Zerovalent Iron Samples toward Various Contaminants.

    PubMed

    Li, Jinxiang; Qin, Hejie; Guan, Xiaohong

    2015-12-15

    Premagnetization was applied to enhance the removal of various oxidative contaminants (including amaranth (AR27), lead ion (Pb(2+)), cupric ion (Cu(2+)), selenite (Se(4+)), silver ion (Ag(+)), and chromate (Cr(6+))) by zerovalent iron (ZVI) from different origins under well-controlled experimental conditions. The rate constants of contaminants by premagnetized ZVI (Mag-ZVI) samples were 1.2-12.2-fold greater than those by pristine ZVI (Pri-ZVI) samples. Generally, there was a linear correlation between the specific reaction rate constants (kSA) of one particular contaminant removal by various Pri-ZVI or Mag-ZVI samples and those of the other contaminant, which could be successfully employed to predict the kSA of one contaminant by one ZVI sample if kSA of the other contaminant by this ZVI sample was available. The specific rate constant of Fe(II) release at pH 4.0 was proposed in this study to stand for the intrinsic reactivity of a ZVI sample. All Mag-ZVI samples had higher intrinsic reactivity than their counterparts without premagnetization. There were strong correlations between the intrinsic reactivity of various Pri-ZVI/Mag-ZVI samples and the removal rate constants of a specific contaminant by these ZVI samples not only at pH 4.0 when the intrinsic reactivity was determined but also at other pH levels. This correlation could be employed to predict the removal rate constant of this contaminant by a ZVI sample that was not included in the original data set once the intrinsic reactivity of the ZVI sample was known. PMID:26575344

  19. Interaction Between Object-Based Attention and Pertinence Values Shapes the Attentional Priority Map of a Multielement Display

    PubMed Central

    2016-01-01

    Previous studies have shown that the perceptual organization of the visual scene constrains the deployment of attention. Here we investigated how the organization of multiple elements into larger configurations alters their attentional weight, depending on the “pertinence” or behavioral importance of the elements’ features. We assessed object-based effects on distinct aspects of the attentional priority map: top-down control, reflecting the tendency to encode targets rather than distracters, and the spatial distribution of attention weights across the visual scene, reflecting the tendency to report elements belonging to the same rather than different objects. In 2 experiments participants had to report the letters in briefly presented displays containing 8 letters and digits, in which pairs of characters could be connected with a line. Quantitative estimates of top-down control were obtained using Bundesen’s Theory of Visual Attention (1990). The spatial distribution of attention weights was assessed using the “paired response index” (PRI), indicating responses for within-object pairs of letters. In Experiment 1, grouping along the task-relevant dimension (targets with targets and distracters with distracters) increased top-down control and enhanced the PRI; in contrast, task-irrelevant grouping (targets with distracters) did not affect performance. In Experiment 2, we disentangled the effect of target-target and distracter-distracter grouping: Pairwise grouping of distracters enhanced top-down control whereas pairwise grouping of targets changed the PRI. We conclude that object-based perceptual representations interact with pertinence values (of the elements’ features and location) in the computation of attention weights, thereby creating a widespread pattern of attentional facilitation across the visual scene. PMID:26752732

  20. Assessing intra-annual vegetation regrowth after fire using the pixel based regeneration index

    NASA Astrophysics Data System (ADS)

    Lhermitte, S.; Verbesselt, J.; Verstraeten, W. W.; Veraverbeke, S.; Coppin, P.

    Several remote sensing studies have discussed the potential of satellite imagery as an alternative for extensive field sampling to quantify fire-vegetation impact over large areas. Most studies depend on Landsat image availability with infrequent image acquisition dates and consequently are limited for assessing intra-annual fire-vegetation dynamics or comparing different fire plots and dates. The control pixel based regeneration index (pRI) derived from SPOT-VEGETATION (VGT) normalized difference vegetation index (NDVI) is used in this study as an alternative to the traditional bi-temporal Landsat approach based on the normalized burn ratio (NBR). The major advantage of the pRI is the use of unburnt control plots which allow the expression of the intra-annual variation due to regeneration processes without external influences. In the comparison of Landsat and VGT data, (i) the inter-annual differences between the bi-temporal and control plot approach were contrasted and (ii) metrics of pRI were derived and compared with the inter-annual dynamics of both VGT and Landsat data. Results of these comparisons, demonstrate the overall similarity between NBR and NDVI data, stress the importance of the elimination of external influences (e.g., phenological variations), and emphasize the failure of including post-fire vegetation responses in bi-temporal Landsat assessments, especially in quickly recovering ecotypes with a strong annual phenological cycle such as savanna. This highlights the importance of using high frequency multi-temporal approaches to estimate fire-vegetation impact in temporally dynamic vegetation types.

  1. Biomass selection for optimal anaerobic treatment of olive mill wastewater.

    PubMed

    Sabbah, I; Yazbak, A; Haj, J; Saliba, A; Basheer, S

    2005-01-01

    This research was conducted to identify the most efficient biomass out of five different types of biomass sources for anaerobic treatment of Olive Mill Wastewater (OMW). This study was first focused on examining the selected biomass in anaerobic batch systems with sodium acetate solutions (control study). Then, the different types of biomass were tested with raw OMW (water-diluted) and with pretreated OMW by coagulation-flocculation using Poly Aluminum Chloride (PACl) combined with hydrated lime (Ca(OH)2). Two types of biomass from wastewater treatment systems of a citrus juice producing company "PriGat" and from a citric acid manufacturing factory "Gadot", were found to be the most efficient sources of microorganisms to anaerobically treat both sodium acetate solution and OMW. Both types of biomass were examined under different concentration ranges (1-40 g l(-1)) of OMW in order to detect the maximal COD tolerance for the microorganisms. The results show that 70-85% of COD removal was reached using Gadot biomass after 8-10 days when the initial concentration of OMW was up to 5 g l(-1), while a similar removal efficiency was achieved using OMW of initial COD concentration of 10 g l(-1) in 2-4 days of contact time with the PriGat biomass. The physico-chemical pretreatment of OMW was found to enhance the anaerobic activity for the treatment of OMW with initial concentration of 20 g l(-1) using PriGat biomass. This finding is attributed to reducing the concentrations of polyphenols and other toxicants originally present in OMW upon the applied pretreatment process. PMID:15747599

  2. P2Y12 receptor inhibition and effect of morphine in patients undergoing primary PCI for ST-segment elevation myocardial infarction. The PRIVATE-ATLANTIC study.

    PubMed

    Silvain, Johanne; Storey, Robert F; Cayla, Guillaume; Esteve, Jean-Baptiste; Dillinger, Jean-Guillaume; Rousseau, Hélène; Tsatsaris, Anne; Baradat, Caroline; Salhi, Néjoua; Hamm, Christian W; Lapostolle, Frédéric; Lassen, Jens Flensted; Collet, Jean-Philippe; Ten Berg, Jurriën M; Van't Hof, Arnoud W; Montalescot, Gilles

    2016-08-01

    PRIVATE-ATLANTIC (P2Y12 Receptor Inhibition with VASP Testing using Elisa kit during the ATLANTIC study) is a pre-specified substudy of the randomised, double-blind ATLANTIC trial in patients with ST-segment elevation myocardial infarction, designed to help interpret the main trial results. The primary objective of ATLANTIC was to assess coronary reperfusion prior to percutaneous coronary intervention (PCI) with pre- vs in-hospital ticagrelor 180 mg loading dose (LD). PRIVATE-ATLANTIC assessed platelet inhibition in 37 patients by measurement of vasodilator-associated stimulated phosphoprotein (VASP) platelet reactivity index (PRI) and VerifyNow platelet reactivity units (PRU) before angiogram (T1), immediately after PCI (T2), 1 (T3), and 6 (T4) hours (h) after PCI, and before next study drug administration (T5). The median time difference between the two ticagrelor LD was 41 minutes. Platelet reactivity was unaffected at T1 when measured by VASP-PRI (89.8 vs 93.9 % for pre- and in-hospital ticagrelor, respectively; p = 0.18) or PRU (239 vs 241; p = 0.82). Numerical differences were apparent at T2 and maximal at T3. Morphine administration significantly delayed onset of platelet inhibition at T3 (VASP-PRI 78.2 vs 23.4 % without morphine; p = 0.0116) and T4 (33.1 vs 11.0 %; p = 0.0057). In conclusion, platelet inhibition in ATLANTIC was unaffected by pre-hospital ticagrelor administration at the time of initial angiogram due to the short transfer delay. The maximum difference in platelet inhibition was detected 1 h after PCI (T3). Morphine administration was associated with delayed onset of action of ticagrelor and appeared more important than timing of ticagrelor administration. PMID:27196998

  3. Interaction between object-based attention and pertinence values shapes the attentional priority map of a multielement display.

    PubMed

    Gillebert, Celine R; Petersen, Anders; Van Meel, Chayenne; Müller, Tanja; McIntyre, Alexandra; Wagemans, Johan; Humphreys, Glyn W

    2016-06-01

    Previous studies have shown that the perceptual organization of the visual scene constrains the deployment of attention. Here we investigated how the organization of multiple elements into larger configurations alters their attentional weight, depending on the "pertinence" or behavioral importance of the elements' features. We assessed object-based effects on distinct aspects of the attentional priority map: top-down control, reflecting the tendency to encode targets rather than distracters, and the spatial distribution of attention weights across the visual scene, reflecting the tendency to report elements belonging to the same rather than different objects. In 2 experiments participants had to report the letters in briefly presented displays containing 8 letters and digits, in which pairs of characters could be connected with a line. Quantitative estimates of top-down control were obtained using Bundesen's Theory of Visual Attention (1990). The spatial distribution of attention weights was assessed using the "paired response index" (PRI), indicating responses for within-object pairs of letters. In Experiment 1, grouping along the task-relevant dimension (targets with targets and distracters with distracters) increased top-down control and enhanced the PRI; in contrast, task-irrelevant grouping (targets with distracters) did not affect performance. In Experiment 2, we disentangled the effect of target-target and distracter-distracter grouping: Pairwise grouping of distracters enhanced top-down control whereas pairwise grouping of targets changed the PRI. We conclude that object-based perceptual representations interact with pertinence values (of the elements' features and location) in the computation of attention weights, thereby creating a widespread pattern of attentional facilitation across the visual scene. (PsycINFO Database Record PMID:26752732

  4. Animal models of ulcerative colitis and their application in drug research

    PubMed Central

    Low, Daren; Nguyen, Deanna D; Mizoguchi, Emiko

    2013-01-01

    The specific pathogenesis underlying inflammatory bowel disease is complex, and it is even more difficult to decipher the pathophysiology to explain for the similarities and differences between two of its major subtypes, Crohn’s disease and ulcerative colitis (UC). Animal models are indispensable to pry into mechanistic details that will facilitate better preclinical drug/therapy design to target specific components involved in the disease pathogenesis. This review focuses on common animal models that are particularly useful for the study of UC and its therapeutic strategy. Recent reports of the latest compounds, therapeutic strategies, and approaches tested on UC animal models are also discussed. PMID:24250223

  5. Drum lid removal tool

    DOEpatents

    Pella, Bernard M.; Smith, Philip D.

    2010-08-24

    A tool for removing the lid of a metal drum wherein the lid is clamped over the drum rim without protruding edges, the tool having an elongated handle with a blade carried by an angularly positioned holder affixed to the midsection of the handle, the blade being of selected width to slice between lid lip and the drum rim and, when the blade is so positioned, upward motion of the blade handle will cause the blade to pry the lip from the rim and allow the lid to be removed.

  6. Neptunium and plutonium complexes with a sterically encumbered triamidoamine (TREN) scaffold

    DOE PAGESBeta

    Brown, Jessie L.; Gaunt, Andrew J.; King, David M.; Liddle, Stephen T.; Reilly, Sean D.; Scott, Brian L.; Wooles, Ashley J.

    2016-03-11

    Here, the syntheses and characterization of isostructural neptunium(IV) and plutonium(IV) complexes [MIV(TRENTIPS)(Cl)] [An = Np, Pu; TRENTIPS = {N(CH2CH2NSiPri3)3}3] are reported, along with the demonstration that they are likely reduced to the corresponding neptunium(III) and plutonium(III) products [MIII(TRENTIPS)]; this chemistry provides new platforms from which to target a plethora of unprecedented molecular functionalities in transuranic chemistry and the neptunium(IV) molecule is the first structurally characterized neptunium(IV)–amide complex.

  7. Subacute Changes in Cleavage Processing of Amyloid Precursor Protein and Tau following Penetrating Traumatic Brain Injury

    PubMed Central

    Mountney, Andrea; Hwang, Hye; Swiercz, Adam; Rammelkamp, Zoe; Boutte, Angela M.; Shear, Deborah A.; Tortella, Frank C.; Schmid, Kara E.

    2016-01-01

    Traumatic brain injury (TBI) is an established risk factor for the development of Alzheimer’s disease (AD). Here the effects of severe penetrating TBI on APP and tau cleavage processing were investigated in a rodent model of penetrating ballistic-like brain injury (PBBI). PBBI was induced by stereotactically inserting a perforated steel probe through the right frontal cortex of the anesthetized rat and rapidly inflating/deflating the probe’s elastic tubing into an elliptical shaped balloon to 10% of total rat brain volume causing temporary cavitation injury. Separate animals underwent probe injury (PrI) alone without balloon inflation. Shams underwent craniectomy. Brain tissue was collected acutely (4h, 24h, 3d) and subacutely (7d) post-injury and analyzed by immunoblot for full length APP (APP-FL) and APP beta c-terminal fragments (βCTFs), full length tau (tau-FL) and tau truncation fragments and at 7d for cytotoxic Beta amyloid (Aβ) peptides Aβ40 and Aβ42 analysis. APP-FL was significantly decreased at 3d and 7d following PBBI whereas APP βCTFs were significantly elevated by 4h post-injury and remained elevated through 7d post-injury. Effects on βCTFs were mirrored with PrI, albeit to a lesser extent. Aβ40 and Aβ42 were significantly elevated at 7d following PBBI and PrI. Tau-FL decreased substantially 3d and 7d post-PBBI and PrI. Importantly, a 22 kDa tau fragment (tau22), similar to that found in AD, was significantly elevated by 4h and remained elevated through 7d post-injury. Thus both APP and tau cleavage was dramatically altered in the acute and subacute periods post-injury. As cleavage of these proteins has also been implicated in AD, TBI pathology shown here may set the stage for the later development of AD or other tauopathies. PMID:27428544

  8. Draft Genome Sequence of Agrobacterium rhizogenes Strain NCPPB2659

    PubMed Central

    Valdes Franco, Jose A.; Collier, Ray; Wang, Yi; Huo, Naxin; Gu, Yong

    2016-01-01

    This work reports the draft genome sequence of Agrobacterium rhizogenes strain NCPPB2659 (also known as strain K599). The assembled genome contains 5,277,347 bp, composed of one circular chromosome, the pRi2659 virulence plasmid, and 17 scaffolds pertaining to the linear chromosome. The wild-type strain causes hairy root disease in dicots and has been used to make transgenic hairy root cultures and composite plants (nontransgenic shoots with transgenic roots). Disarmed variants of the strain have been used to produce stable transgenic monocot and dicot plants. PMID:27469966

  9. Abnormal carbene-silicon halide complexes.

    PubMed

    Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; Schaefer, Henry F; Robinson, Gregory H

    2016-04-14

    Reaction of the anionic N-heterocyclic dicarbene (NHDC), [:C{[N(2,6-Pr(i)2C6H3)]2CHCLi}]n (1), with SiCl4 gives the trichlorosilyl-substituted (at the C4 carbon) N-heterocyclic carbene complex (7). Abnormal carbene-SiCl4 complex (8) may be conveniently synthesized by combining 7 with HCl·NEt3. In addition, 7 may react with CH2Cl2 in warm hexane, giving the abnormal carbene-complexed SiCl3(+) cation (9). The nature of the bonding in 9 was probed with complementary DFT computations. PMID:26605692

  10. Draft Genome Sequence of Agrobacterium rhizogenes Strain NCPPB2659.

    PubMed

    Valdes Franco, Jose A; Collier, Ray; Wang, Yi; Huo, Naxin; Gu, Yong; Thilmony, Roger; Thomson, James G

    2016-01-01

    This work reports the draft genome sequence of Agrobacterium rhizogenes strain NCPPB2659 (also known as strain K599). The assembled genome contains 5,277,347 bp, composed of one circular chromosome, the pRi2659 virulence plasmid, and 17 scaffolds pertaining to the linear chromosome. The wild-type strain causes hairy root disease in dicots and has been used to make transgenic hairy root cultures and composite plants (nontransgenic shoots with transgenic roots). Disarmed variants of the strain have been used to produce stable transgenic monocot and dicot plants. PMID:27469966

  11. JWST Primary Mirror Technology Development

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    Mirror Technology was identified as a (if not the) critical capability necessary to achieve the Level 1 science goals. A never before demonstrated space telescope capability was required: 6 to 8 meter class pri mary mirror, diffraction limited at 2 micrometers and operates at temperatures below 50K. Launch vehicle constraints placed significant architectural constraints: deployed/segmented primary mirror (4.5 meter fairing diameter) 20 kg/m2 areal density (PM 1000 kg mass) Such mirror technology had never been demonstrated - and did not exist

  12. Recent development of two new UV Raman standoff explosive detection systems

    NASA Astrophysics Data System (ADS)

    Waterbury, Rob; Babnick, Robert; Cooper, Justin L.; Ford, Alan R.; Herrera, Francisco; Hopkins, Adam J.; Pohl, Ken; Profeta, Luisa T. M.; Sandoval, Juan; Vunck, Darius

    2016-05-01

    Alakai Defense Systems has created two new short range UV Raman standoff explosive detection sensors. These are called the Critical Infrastructure Protection System (CIPS) and Portable Raman Improvised Explosive Detection System (PRIED) and work at standoff ranges of 10cm and 1-10m respectively. Both these systems are designed to detect neartrace quantities of explosives and Homemade Explosives. A short description of the instruments, design trades, and CONOPS of each design is presented. Data includes a wide variety of explosives, precursors, TIC/TIM's, narcotics, and CWA simulants

  13. D-1A nose fairing separation fitting load test

    NASA Technical Reports Server (NTRS)

    Vanvleet, J. O.

    1976-01-01

    Structural testing of the D-1A Centaur nose fairing was completed to determine the loads imposed during flight on the latch bolts of the fairing separation system. This testing was conducted to supplement and/or verify the analytic techniques used in calculating bolt loads for the D-1A, and to gain insight into the general structural behavior of separation latch systems. It was shown that the assumed bolt load magnification due to prying action of the latch fittings on the bolt does occur, but is strongly dependent on fairing shell stiffness.

  14. Linking solar induced fluorescence and the photochemical reflectance index to carbon assimilation in a cornfield

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Middleton, E.; Zhang, Q.; Corp, L.; Campbell, P. K.; Huemmrich, K. F.; Kustas, W.; Daughtry, C. S.; Dulaney, W. P.; Russ, A.

    2012-12-01

    Determining the health and vigor of vegetation using high spectral resolution remote sensing techniques is a critical component in monitoring productivity from both natural and managed ecosystems and their feedbacks to climate. This presentation summarizes a field campaign conducted in a USDA-ARS experimental cornfield site located in Beltsville, MD, USA over a five-year period. The site is equipped with an instrumented tower which makes continuous eddy covariance measurements of CO2 along with incoming PAR. Hyperspectral reflectance observations were acquired over corn canopies with a USB4000 Miniature Fiber Optic Spectrometer (Ocean Optics Inc., Dunedin, Florida, USA) at multiple times a day at various stages through the growing season. On all field days, supporting plant information and leaf level data were acquired (e.g., CO2 gas exchange) as well as biophysical field data, including leaf area index (LAI), mid-day canopy PAR transmission, soil reflectivity, and soil moisture. The canopy optical measurements enabled retrievals of the photochemical reflectance index (PRI) and solar induced fluorescence (SIF) centered at O2-A and -B bands. These two spectrally based bio-indicators have been widely utilized in studies to assess whether vegetation is performing near-optimally or exhibiting symptoms of environmental stress (e.g., drought or nutrient deficiency, non-optimal temperatures, etc.). Both SIF and PRI expressed diurnal dynamics and seasonal changes that followed environmental conditions and physiological status of the cornfield. We further investigated the correlation between these two retrievals and the flux tower based carbon assimilation observations (i.e. gross ecosystem production, GEP). We were able to successfully model the variation of GEP (r2=0.81; RMSE=0.18 mg CO2/m2/s) by utilizing both SIF and PRI. Several cross-validation algorithms were applied to the model to demonstrate the robustness and consistency of the model. Our results suggest great

  15. Platelet inhibition with prasugrel in patients with acute myocardial infarction undergoing therapeutic hypothermia after cardiopulmonary resuscitation.

    PubMed

    Flierl, Ulrike; Röntgen, Philipp; Zauner, Florian; Tongers, Jörn; Berliner, Dominik; Bauersachs, Johann; Schäfer, Andreas

    2016-05-01

    Acute myocardial infarction (AMI) is the leading cause for out-of-hospital cardiac arrest. Therapeutic hypothermia improves neurological outcome in combination with early revascularisation, but seems to affect clopidogrel responsiveness. The more potent thienopyridine prasugrel has not yet been sufficiently evaluated during therapeutic hypothermia. We investigated 23 consecutive AMI patients (61 ± 11 years) following out-of-hospital resuscitation undergoing revascularisation and therapeutic hypothermia. Prasugrel efficacy was assessed by the platelet-reactivity-index (PRI) before and 2, 4, 6, 12, 24, 48, and 72 hours (h) following a loading dose of 60 mg via a gastric tube. Mean PRI (± SD) was 70 ± 12 % prior to loading and 60 ± 16 % (2 h, ns), 52 ± 21 % (4 h, p< 0.01), 42 ± 26 % (6 h, p< 0.01), 37 ± 21 % (12 h, p< 0.01), 27 ± 23 % (24 h, p< 0.01), 18 ± 14 % (48 h, p< 0.01), and 13 ± 10 % (72 h, p< 0.01) after loading. Sufficient platelet inhibition occurred later compared to stable AMI patients (6 h vs 2 h); however, high on-treatment platelet reactivity significantly decreased over time and was non-existent after 72 h (PRI> 50 %: 2 h: 72 %, 4 h: 52 %, 6 h: 43 %, 12 h: 29 %, 24 h: 17 %, 48 h: 5 %, 72 h: 0 %). There was no relation between 30-day mortality rate (26 %) and PRI values. Prasugrel significantly reduced platelet reactivity even during vasopressor use, analgosedation and therapeutic hypothermia. Despite a significant delay compared to stable AMI patients, sufficient platelet inhibition was reached in 83 % of patients within 24 h. Therefore, prasugrel administration via gastric tube might be a useful therapeutic strategy in these patients at high risk, providing potent and effective P2Y12 inhibition. PMID:26790884

  16. Ensenanza de la Astronomia a Traves de Metodos no Tradicionales

    NASA Astrophysics Data System (ADS)

    Tignanelli, H. L.

    1990-11-01

    REUMEN: Se presentan los aspects pri nc ipales de a ense? anza de la astronor:. a para -; s. En esta cc .unicaci #n, 5 ha especial mfasis em Ia descripci':"n de las caracteristicas y las posibi lidades peda gicas de los no tradicionales de aprendiZaje. E' : In the following the principal aspects of teaching of astrono ..y for children) are oresented. In this paper, special emphasis has been given to desc rib the characteristics and pedagogical possibilities of the non traditional methods of learning. : TEACHING

  17. Radiogenic Ingrowth of 40CA from Decay of 40K Provides a Powerful Tracer for Understanding the Origins of Felsic Magmas

    NASA Technical Reports Server (NTRS)

    Mills, Ryan D.; Simon, Justin I.; Depaolo, Donald J.; Bachmann, Olivier

    2013-01-01

    Over time high K/Ca continental crust produces a unique Ca isotopic reservoir, with measurable 40Ca excesses compared to Earth's mantle (?Ca=0). Thus, values of ?Cai > 1 indicate a significant crustal contribution to a magma. Values of ?Cai (<1) indistinguishable from mantle Ca indicate that the Ca in those magmas is either directly from the mantle, or is from partial melting of newly formed crust. So, whereas 40Ca excesses clearly define crustal contributions, mantle-like 40Ca/44Ca ratios are not as definitive. Here we present Ca isotopic measurements of intermediate to felsic igneous rocks from the western United States, and two crustal xenoliths found within the Fish Canyon Tuff (FCT). The two crustal xenoliths found within the 28.2 Ma FCT of the southern Rocky Mountain volcanic field (SRMVF) yield ?Ca values of 4 and 7.5, respectively. The 40Ca excesses of these possible source rocks are due to long-term in situ 40K decay and suggest that they are Precambrian in age. However, the FCT (?Cai 0.3) is within uncertainty of the mantle 40Ca/44Ca. Together, these data indicate that little Precambrian crust was involved in the petrogenesis of the FCT. Nd isotopic analyses of the FCT imply that it was generated from 10- 75% of an enriched component, and the Ca isotopic data appear to restrict that component to newly formed lower crust, or enriched mantle. However, the Ca isotopic data do permit assimilation of some crust with low Ca/Nd; decreasing the 143Nd/144Nd without adding much excess 40Ca to the FCT. Several other large tuffs from the SRMVF and from Yellowstone have ?Cai indistinguishable from the mantle. However, a few large tuffs from the SRMVF show significant 40Ca excesses. These tuffs (Wall Mountain, Blue Mesa, and Grizzly Peak) are likely sourced from near, or within the Colorado Mineral Belt. New isotopic measurements of Mesozoic and Tertiary granites from across the northern Great Basin show a range of ?Cai from 0 to 3. In these samples ?Cai is generally

  18. Multi-proxy study of Ocean Anoxic Event 2 (Cenomanian-Turonian) yields new perspective on the drivers for Mesozoic anoxic events

    NASA Astrophysics Data System (ADS)

    Sageman, B. B.; Hurtgen, M.; Jacobson, A. D.; Selby, D. S.

    2015-12-01

    Mesozoic ocean anoxic events have long been a focus of intense study because they appear to reflect a large-scale oscillation of the marine redox state from oxic to anoxic, and at least locally sulfidic. The consensus view on the cause of these events has changed over the past 39 years, since they were first defined. A global net increase in primary production is now widely accepted as the key driver, and the evidence for a volcanic trigger of this process is strong. However, the exact pathway from volcanism to OAE is less certain. Some authors favor the direct role of a massive load of reduced compounds in LIP hydrothermal fluxes for consuming available marine oxygen. Others prefer the indirect pathway of oxygen consumption by enhanced organic matter flux, which requires a major increase in nutrient budgets. Metallic micronutrients in the hydrothermal fluxes have been hypothesized, as have increases in riverine phosphorus fluxes due to enhanced weathering that would result from volcanic CO2 driven warming. Our recent work on the OAE2 interval has led to some new ideas about these hypothesized drivers. In particular, refinement of the Late Cenomanian time scale, and comparison of the geochemical records of d13C, d34S, Osi, P phases, and d44Ca between selected sections in North America and Europe has suggested the following sequence of events: 1) Osi data indicate that the onset of a major volcanic event precedes the positive shift in C-isotopes by at least 40 to possibly 180 kyr; 2) a positive shift in d44Ca data interpreted to indicate ocean acidification is coincident with the volcanic event; 3) the positive shift in C-isotopes is interpreted to reflect the accumulated burial of marine organic matter sufficient to shift the C-reservoir to heavier values; thus, our data suggest that up to 180 kyr was required for the shift in nutrient supply, productivity increase, and organic matter burial. Two mechanisms that conceivably match the lagged character of the event

  19. The effects of diagenesis and dolomitization on Ca and Mg isotopes in marine platform carbonates: Implications for the geochemical cycles of Ca and Mg

    NASA Astrophysics Data System (ADS)

    Fantle, Matthew S.; Higgins, John

    2014-10-01

    The Ca, Mg, O, and C isotopic and trace elemental compositions of marine limestones and dolostones from ODP Site 1196A, which range in depth (∼58 to 627 mbsf) and in depositional age (∼5 and 23 Ma), are presented. The objectives of the study are to explore the potential for non-traditional isotope systems to fingerprint diagenesis, to quantify the extent to which geochemical proxies are altered during diagenesis, and to investigate the importance of diagenesis within the global Ca and Mg geochemical cycles. The data suggest that Ca, which has a relatively high solid to fluid mass ratio, can be isotopically altered during diagenesis. In addition, the alteration of Ca correlates with the alteration of Mg in such a way that both can serve as useful tools for deciphering diagenesis in ancient rocks. Bulk carbonate δ44Ca values vary between 0.60 and 1.31‰ (SRM-915a scale); the average limestone δ44Ca is 0.97 ± 0.24‰ (1SD), identical within error to the average dolostone (1.03 ± 0.15 1SD ‰). Magnesium isotopic compositions (δ26Mg, DSM-3 scale) range between -2.59‰ and -3.91‰, and limestones (-3.60 ± 0.25‰) and dolostones (-2.68 ± 0.07‰) are isotopically distinct. Carbon isotopic compositions (δ13C, PDB scale) vary between 0.86‰ and 2.47‰, with average limestone (1.96 ± 0.31‰) marginally offset relative to average dolostone (1.68 ± 0.57‰). The oxygen isotopic compositions (δ18O, PDB scale) of limestones (-1.22 ± 0.94‰) are substantially lower than the dolostones measured (2.72 ± 1.07‰). The isotopic data from 1196A suggest distinct and coherent trends in isotopic and elemental compositions that are interpreted in terms of diagenetic trajectories. Numerical modeling supports the contention that such trends can be interpreted as diagenetic, and suggests that the appropriate distribution coefficient (KMg) associated with limestone diagenesis is ∼1 to 5 × 10-3, distinctly lower than those values (>0.015) reported in laboratory

  20. Calcium isotopic composition of mantle xenoliths and minerals from Eastern China

    NASA Astrophysics Data System (ADS)

    Kang, Jin-Ting; Zhu, Hong-Li; Liu, Yu-Fei; Liu, Fang; Wu, Fei; Hao, Yan-Tao; Zhi, Xia-Chen; Zhang, Zhao-Feng; Huang, Fang

    2016-02-01

    This study presents calcium isotope data for co-existing clinopyroxenes (cpx), orthopyroxenes (opx), and olivine (ol) in mantle xenoliths to investigate Ca isotopic fractionation in the upper mantle. δ44/40Ca (δ44/40Ca (‰) = (44Ca/40Ca)SAMPLE/(44Ca/40Ca)SRM915a - 1) in opx varies from 0.95 ± 0.05‰ to 1.82 ± 0.01‰ and cpx from 0.71 ± 0.06‰ to 1.03 ± 0.12‰ (2se). δ44/40Ca in ol (P-15) is 1.16 ± 0.08‰, identical to δ44/40Ca of the co-existing opx (1.12 ± 0.09‰, 2se). The Δ44/40Caopx-cpx (Δ44/40Caopx-cpx = δ44/40Caopx-δ44/40Cacpx) shows a large variation ranging from -0.01‰ to 1.11‰ and it dramatically increases with decreasing of Ca/Mg (atomic ratio) in opx. These observations may reflect the effect of opx composition on the inter-mineral equilibrium fractionation of Ca isotopes, consistent with the theoretical prediction by first-principles theory calculations (Feng et al., 2014). Furthermore, Δ44/40Caopx-cpx decreases when temperature slightly increases from 1196 to 1267 K. However, the magnitude of such inter-mineral isotopic fractionation (1.12‰) is not consistent with the value calculated by the well-known correlation between inter-mineral isotope fractionation factors and 1/T2 (Urey, 1947). Instead, it may reflect the temperature control on crystal chemistry of opx (i.e., Ca content), which further affects Δ44/40Caopx-cpx. The calculated δ44/40Ca of bulk peridotites and pyroxenites range from 0.76 ± 0.06‰ to 1.04 ± 0.12‰ (2se). Notably, δ44/40Ca of bulk peridotites are positively correlated with CaO and negatively with MgO content. Such correlations can be explained by mixing between a fertile mantle end-member and a depleted one with low δ44/40Ca, indicating that Ca isotopes could be a useful tool in studying mantle evolution.

  1. Regeneration of horseradish hairy roots incited by Agrobacterium rhizogenes infection.

    PubMed

    Noda, T; Tanaka, N; Mano, Y; Nabeshima, S; Ohkawa, H; Matsui, C

    1987-07-01

    Surface-sterilized leaf disks of horse-radish (Armoracia lapathifolia) were immersed in a suspension of Agrobacterium rhizogenes harboring the root-inducing plasmid (pRi) and cultured on a solid medium. Within about 10 days after inoculation, adventitious roots (hairy roots) emerged from the leaf disks. No roots emerged from the uninoculated leaf disks. The excised hairy roots grew vigorously in the dark and exhibited extensive lateral branches in the absence of phytohormones. When the hairy roots were moved into the light, numerous adventitious buds thrust out of the roots within about 10 days, and they developed into complete plants (R0 generation). R0 plants revealed leaf wrinkle. Root masses of cultured R0 plants were of two types. One had fibrous roots only and the other had both fibrous and tuberous roots Leaf disks of the R0 plants proliferated adventitious roots (R1 generation) on a solid medium after 1-2 weeks of culture. Phenotypical characters of the R1 roots were the same as those observed with the initial hairy roots. The T-DNA sequences of pRi were detected within DNA isolated from the hairy roots and their regenerants. PMID:24248760

  2. Distinct E-cadherin-based complexes regulate cell behaviour through miRNA processing or Src and p120 catenin activity.

    PubMed

    Kourtidis, Antonis; Ngok, Siu P; Pulimeno, Pamela; Feathers, Ryan W; Carpio, Lomeli R; Baker, Tiffany R; Carr, Jennifer M; Yan, Irene K; Borges, Sahra; Perez, Edith A; Storz, Peter; Copland, John A; Patel, Tushar; Thompson, E Aubrey; Citi, Sandra; Anastasiadis, Panos Z

    2015-09-01

    E-cadherin and p120 catenin (p120) are essential for epithelial homeostasis, but can also exert pro-tumorigenic activities. Here, we resolve this apparent paradox by identifying two spatially and functionally distinct junctional complexes in non-transformed polarized epithelial cells: one growth suppressing at the apical zonula adherens (ZA), defined by the p120 partner PLEKHA7 and a non-nuclear subset of the core microprocessor components DROSHA and DGCR8, and one growth promoting at basolateral areas of cell-cell contact containing tyrosine-phosphorylated p120 and active Src. Recruitment of DROSHA and DGCR8 to the ZA is PLEKHA7 dependent. The PLEKHA7-microprocessor complex co-precipitates with primary microRNAs (pri-miRNAs) and possesses pri-miRNA processing activity. PLEKHA7 regulates the levels of select miRNAs, in particular processing of miR-30b, to suppress expression of cell transforming markers promoted by the basolateral complex, including SNAI1, MYC and CCND1. Our work identifies a mechanism through which adhesion complexes regulate cellular behaviour and reveals their surprising association with the microprocessor. PMID:26302406

  3. A controlled field trial of the effectiveness of acetone-dried and inactivated and heat-phenol-inactivated typhoid vaccines in Yugoslavia*

    PubMed Central

    1964-01-01

    In 1954-60 a Yugoslav Typhoid Commission showed in the first controlled field trial of typhoid vaccines, carried out in Osijek, Yugoslavia, that heat-phenol-inactivated typhoid vaccine gave a relatively high and long-lasting immunity. However, this liquid vaccine preparation was unstable and laboratory potency tests were inconclusive, and it was therefore decided that stable, dried, heat-killed, phenol-preserved vaccine be tested together with an acetone-inactivated and -dried vaccine in controlled field trials, supported in part by the World Health Organization, in Yugoslavia and British Guiana. This is report on the controlled trials organized in two Yugoslav towns, Bitola and Priština. Three comparable groups were formed by random allocation of vaccines among 45 497 volunteers in the two towns. In each town one group received heat-phenol vaccine, the second group acetone-dried vaccine and the third (control) group tetanus toxoid. Two doses were given four weeks apart in the spring of 1960 and the vaccinated persons were followed up for 2 1/2 years. The effectiveness of the vaccines was measured by comparing typhoid morbidity rates in the three groups. It was found during an outbreak of typhoid fever in Priština two years after primary vaccination that both the acetone-dried and the heat-phenol vaccines were effective, the former being superior. PMID:14196811

  4. Structure of the dimerization domain of DiGeorge critical region 8

    SciTech Connect

    Senturia, R.; Faller, M.; Yin, S.; Loo, J.A.; Cascio, D.; Sawaya, M.R.; Hwang, D.; Clubb, R.T.; Guo, F.

    2010-09-27

    Maturation of microRNAs (miRNAs, {approx}22nt) from long primary transcripts [primary miRNAs (pri-miRNAs)] is regulated during development and is altered in diseases such as cancer. The first processing step is a cleavage mediated by the Microprocessor complex containing the Drosha nuclease and the RNA-binding protein DiGeorge critical region 8 (DGCR8). We previously reported that dimeric DGCR8 binds heme and that the heme-bound DGCR8 is more active than the heme-free form. Here, we identified a conserved dimerization domain in DGCR8. Our crystal structure of this domain (residues 298-352) at 1.7 {angstrom} resolution demonstrates a previously unknown use of a WW motif as a platform for extensive dimerization interactions. The dimerization domain of DGCR8 is embedded in an independently folded heme-binding domain and directly contributes to association with heme. Heme-binding-deficient DGCR8 mutants have reduced pri-miRNA processing activity in vitro. Our study provides structural and biochemical bases for understanding how dimerization and heme binding of DGCR8 may contribute to regulation of miRNA biogenesis.

  5. An Open Source 3-D Printed Modular Micro-Drive System for Acute Neurophysiology

    PubMed Central

    Eskandar, Emad N.

    2014-01-01

    Current, commercial, electrode micro-drives that allow independent positioning of multiple electrodes are expensive. Custom designed solutions developed by individual laboratories require fabrication by experienced machinists working in well equipped machine shops and are therefore difficult to disseminate into widespread use. Here, we present an easy to assemble modular micro-drive system for acute primate neurophysiology (PriED) that utilizes rapid prototyping (3-d printing) and readily available off the shelf-parts. The use of 3-d printed parts drastically reduces the cost of the device, making it available to labs without the resources of sophisticated machine shops. The direct transfer of designs from electronic files to physical parts also gives researchers opportunities to easily modify and implement custom solutions to specific recording needs. We also demonstrate a novel model of data sharing for the scientific community: a publicly available repository of drive designs. Researchers can download the drive part designs from the repository, print, assemble and then use the drives. Importantly, users can upload their modified designs with annotations making them easily available for others to use. PMID:24736691

  6. Effects of auricular transcutaneous electrical nerve stimulation on distal extremity pain: a pilot study.

    PubMed

    Longobardi, A G; Clelland, J A; Knowles, C J; Jackson, J R

    1989-01-01

    The purpose of this pilot study was to determine the effectiveness of auricular acupuncture-like transcutaneous electrical nerve stimulation on pain. Fifteen subjects (6 men, 9 women) experiencing distal extremity pain received either one placebo pill or a 10-minute treatment of acupuncture-like TENS bilaterally to five acupuncture points on the auricle. Pain levels were measured before treatment and at 0, 10, and 30 minutes posttreatment using the visual analogue scale (VAS) and the pain rating index (PRI) of the McGill Pain Questionnaire. The VAS showed no statistically significant differences between Experimental Group (n = 8) and Control Group (n = 7) means at pretreatment or posttreatment; however, both groups showed a reduction in VAS means over time. The Experimental and Control Group means on the PRI were significantly different (p less than .05) at all three posttreatment measurements, but not at pretreatment baseline measurement. These results suggest that auricular acupuncture-like TENS could be an alternative for relief of distal extremity pain. Additional clinical studies are necessary to validate the results of this study. PMID:2783492

  7. Puerto Rico Strong Motion Seismic Network

    NASA Astrophysics Data System (ADS)

    Huerta-Lopez, C. I.; Martínez-Cruzado, J. A.; Martínez-Pagan, J.; Santana-Torres, E. X.; Torres-O, D. M.

    2014-12-01

    The Puerto Rico Strong Motion Seismic Network is currently in charge of the operation of: (i) free-field (ff) strong motion stations, (ii) instrumented structures (STR) (Dams, Bridges, Buildings), and (iii) the data acquisition/monitoring and analysis of earthquakes considered strong from the point of view of their intensity and magnitude. All these instruments are deployed in the Puerto Rico Island (PRI), US-, and British-Virgin Islands (BVI), and Dominican Republic (DR). The Puerto Rico Island and the Caribbean region have high potential to be affected by earthquakes that could be catastrophic for the area. The Puerto Rico Strong Motion Seismic Network (actually Puerto Rico Strong Motion Program, PRSMP) has grown since 1970's from 7 ff strong motion stations and one instrumented building with analog accelerographs to 111 ff strong motion stations and 16 instrumented buildings with digital accelerographs: PRI: 88 ff, 16 STR., DR: 13 ff, BVI: 5 ff, 2 STR collecting data via IP (internet), DU (telephone), and stand alone stations The current stage of the PRSMP seismic network, the analysis of moderate earthquakes that were recorded and/or occurred on the island, results of the intensity distribution of selected earthquakes, as well as results of dynamic parameter identification of some of the instrumented structures are here presented.

  8. Hypoxia responsive gene expression is mediated by various subsets of transcription factors and miRNAs that are determined by the actual oxygen availability.

    PubMed

    Licausi, Francesco; Weits, Daan A; Pant, Bikram Datt; Scheible, Wolf-Rüdiger; Geigenberger, Peter; van Dongen, Joost T

    2011-04-01

    • Reduced oxygen availability is not only associated with flooding, but occurs also during growth and development. It is largely unknown how hypoxia is perceived and what signaling cascade is involved in activating adaptive responses. • We analysed the expression of over 1900 transcription factors (TFs) and 180 microRNA primary transcripts (pri-miRNAs) in Arabidopsis roots exposed to different hypoxic conditions by means of quantitative PCR. We also analysed the promoters of genes induced by hypoxia with respect to over-represented DNA elements that can act as potential TF binding sites and their in vivo interaction was verified. • We identified various subsets of TFs that responded differentially through time and in an oxygen concentration-dependent manner. The regulatory potential of selected TFs and their predicted DNA binding elements was validated. Although the expression of pri-miRNAs was differentially regulated under hypoxia, only one corresponding mature miRNA changed accordingly. Putative target transcripts of the miRNAs were not significantly affected. • Our results show that the regulation of hypoxia-induced genes is controlled via simultaneous interaction of various combinations of TFs. Under anoxic conditions, an additional set of TFs is induced. Regulation of gene expression via miRNAs appears to play a minor role during hypoxia. PMID:20840511

  9. The morphology, proliferation rate, and population doubling time factor of adipose-derived mesenchymal stem cells cultured on to non-aqueous SiO2, TiO2, and hybrid sol-gel-derived oxide coatings.

    PubMed

    Marycz, Krzysztof; Krzak-Roś, Justyna; Donesz-Sikorska, Anna; Śmieszek, Agnieszka

    2014-11-01

    In recent years, much attention has been paid to the development of tissue engineering and regenerative medicine, especially when stem cells of various sources are concerned. In addition to the interest in mesenchymal stem cells isolated from bone marrow, recently more consideration has been given to stem cells isolated from adipose tissue (AdMSCs), due to their less invasive method of collection as well as their ease of isolation and culture. However, the development of regenerative medicine requires both the application of biocompatible material and the stem cells to accelerate the regeneration. In this study, we investigated the morphology, proliferation rate index (PRi), and population doubling time factor of adipose-derived mesenchymal stem cells cultured on non-aqueous sol-gel-derived SiO2, TiO2, and SiO2/TiO2 oxide coatings. The results indicated an increase in PRi of AdMSCs when cultured on to titanium dioxide, suggesting its high attractiveness for AdMSCs. In addition, the proper morphology and the shortest doubling time of AdMSCs were observed when cultured on titanium dioxide coating. PMID:24408867

  10. Field Theory for Multi-Particle System

    NASA Astrophysics Data System (ADS)

    Wang, Shouhong; Ma, Tian

    2016-03-01

    The main objectives of this talk are 1) to introduce some basic postulates for quantum multi-particle systems, and 2) to develop a universal field theory for interacting multi-particle systems coupling both particle fields and interacting fields. By carefully examining the nature of interactions between multi-particles, we conclude that multi-particle systems must obey i) the gauge symmetry, ii) the principle of interaction dynamics (PID), and iii) the principle of representation invariance (PRI). Intuitively, PID takes the variation of the action functional under energy-momentum conservation constraint, offers a different and natural way of introducing Higgs fields, and is also required by the presence of dark matter and dark energy and the quark confinement. PRI requires that the SU(N) gauge theory be independent of representations of SU(N). Based on these principles, a few basic postulates for multi-particle systems are introduced in this talk, leading to a field theory for interacting multi-particle systems. A direct consequence of the field theory is the derivation of general atomic spectrum equations. Supported in Part by the Office of Naval Research, by the US National Science Foundation, and by the Chinese National Science Foundation.

  11. Salt Stress Reveals a New Role for ARGONAUTE1 in miRNA Biogenesis at the Transcriptional and Posttranscriptional Levels.

    PubMed

    Dolata, Jakub; Bajczyk, Mateusz; Bielewicz, Dawid; Niedojadlo, Katarzyna; Niedojadlo, Janusz; Pietrykowska, Halina; Walczak, Weronika; Szweykowska-Kulinska, Zofia; Jarmolowski, Artur

    2016-09-01

    Plants as sessile organisms have developed prompt response mechanisms to react to rapid environmental changes. In addition to the transcriptional regulation of gene expression, microRNAs (miRNAs) are key posttranscriptional regulators of the plant stress response. We show here that the expression levels of many miRNAs were regulated under salt stress conditions. This regulation occurred at the transcriptional and posttranscriptional levels. During salinity stress, the levels of miRNA161 and miRNA173 increased, while the expression of pri-miRNA161 and pri-miRNA173 was down-regulated. Under salt stress conditions, miRNA161 and miRNA173 were stabilized in the cytoplasm, and the expressions of MIR161 and MIR173 were negatively regulated in the nucleus. ARGONAUTE1 (AGO1) participated in both processes. We demonstrated that AGO1 cotranscriptionally controlled the expression of MIR161 and MIR173 in the nucleus. Our results suggests that AGO1 interacts with chromatin at MIR161 and MIR173 loci and causes the disassembly of the transcriptional complex, releasing short and unpolyadenylated transcripts. PMID:27385819

  12. Two-Coordinate Magnesium(I) Dimers Stabilized by Super Bulky Amido Ligands.

    PubMed

    Boutland, Aaron J; Dange, Deepak; Stasch, Andreas; Maron, Laurent; Jones, Cameron

    2016-08-01

    A variety of very bulky amido magnesium iodide complexes, LMgI(solvent)0/1 and [LMg(μ-I)(solvent)0/1 ]2 (L=-N(Ar)(SiR3 ); Ar=C6 H2 {C(H)Ph2 }2 R'-2,6,4; R=Me, Pr(i) , Ph, or OBu(t) ; R'=Pr(i) or Me) have been prepared by three synthetic routes. Structurally characterized examples of these materials include the first unsolvated amido magnesium halide complexes, such as [LMg(μ-I)]2 (R=Me, R'=Pr(i) ). Reductions of several such complexes with KC8 in the absence of coordinating solvents have afforded the first two-coordinate magnesium(I) dimers, LMg-MgL (R=Me, Pr(i) or Ph; R'=Pr(i) , or Me), in low to good yields. Reductions of two of the precursor complexes in the presence of THF have given the related THF adduct complexes, L(THF)Mg-Mg(THF)L (R=Me; R'=Pr(i) ) and LMg-Mg(THF)L (R=Pr(i) ; R'=Me) in trace yields. The X-ray crystal structures of all magnesium(I) complexes were obtained. DFT calculations on the unsolvated examples reveal their Mg-Mg bonds to be covalent and of high s-character, while Ph⋅⋅⋅Mg bonding interactions in the compounds were found to be weak at best. PMID:27303934

  13. Evaluating the prevalence and impact of examiner errors on the Wechsler scales of intelligence: A meta-analysis.

    PubMed

    Styck, Kara M; Walsh, Shana M

    2016-01-01

    The purpose of the present investigation was to conduct a meta-analysis of the literature on examiner errors for the Wechsler scales of intelligence. Results indicate that a mean of 99.7% of protocols contained at least 1 examiner error when studies that included a failure to record examinee responses as an error were combined and a mean of 41.2% of protocols contained at least 1 examiner error when studies that ignored errors of omission were combined. Furthermore, graduate student examiners were significantly more likely to make at least 1 error on Wechsler intelligence test protocols than psychologists. However, psychologists made significantly more errors per protocol than graduate student examiners regardless of the inclusion or exclusion of failure to record examinee responses as errors. On average, 73.1% of Full-Scale IQ (FSIQ) scores changed as a result of examiner errors, whereas 15.8%-77.3% of scores on the Verbal Comprehension Index (VCI), Perceptual Reasoning Index (PRI), Working Memory Index (WMI), and Processing Speed Index changed as a result of examiner errors. In addition, results suggest that examiners tend to overestimate FSIQ scores and underestimate VCI scores. However, no strong pattern emerged for the PRI and WMI. It can be concluded that examiner errors occur frequently and impact index and FSIQ scores. Consequently, current estimates for the standard error of measurement of popular IQ tests may not adequately capture the variance due to the examiner. PMID:26011479

  14. An open source 3-d printed modular micro-drive system for acute neurophysiology.

    PubMed

    Patel, Shaun R; Ghose, Kaushik; Eskandar, Emad N

    2014-01-01

    Current, commercial, electrode micro-drives that allow independent positioning of multiple electrodes are expensive. Custom designed solutions developed by individual laboratories require fabrication by experienced machinists working in well equipped machine shops and are therefore difficult to disseminate into widespread use. Here, we present an easy to assemble modular micro-drive system for acute primate neurophysiology (PriED) that utilizes rapid prototyping (3-d printing) and readily available off the shelf-parts. The use of 3-d printed parts drastically reduces the cost of the device, making it available to labs without the resources of sophisticated machine shops. The direct transfer of designs from electronic files to physical parts also gives researchers opportunities to easily modify and implement custom solutions to specific recording needs. We also demonstrate a novel model of data sharing for the scientific community: a publicly available repository of drive designs. Researchers can download the drive part designs from the repository, print, assemble and then use the drives. Importantly, users can upload their modified designs with annotations making them easily available for others to use. PMID:24736691

  15. Model for detection and assessment of abiotic stress caused by uranium mining in European Black Pine landscapes

    NASA Astrophysics Data System (ADS)

    Filchev, Lachezar; Roumenina, Eugenia

    2013-10-01

    The article presents the results obtained from a study for detection and assessment of abiotic stress through pollution with heavy metals, metalloids, and natural radionuclides in European Black Pine (Pinus nigra L.) forests caused by uranium mining using ground-based biogeochemical, biophysical, and field spectrometry data. The forests are located on a territory subject to underground and open uranium mining. An operational model of the study is proposed. The areas subject to technogeochemical load are outlined based on the aggregate pollution index Zc. Laboratory and field spectrometry data were used to detect the signals of abiotic stress at pixel level. The methods used for determination of stressed and unstressed black pine forests are: four vegetation indices (TCARI, MCARI, MTVI 2, and PRI 1) for stress detection, and the position, depth, asymmetry, and shift of the red-edge. Based on the "blue shift" and the depth and position of the red-edge, registered by the laboratory analysis and field spectral reflectance, it is established that coniferous forests subject to abiotic stress show an increase in total chlorophyll content and carotene. It has been found that the vegetation indices MTVI 2 and PRI 1, as well as the combination of vegetation indices and pigments may be used as a direct indicator of abiotic stress in coniferous forests caused by uranium mining.

  16. Enhanced electrical transport by texture modulation and co-doping for Ca3Co4O9+δ materials

    NASA Astrophysics Data System (ADS)

    Liu, Z. Y.; Zhang, F. P.; Zhang, J. X.; Zhang, X.; Lu, Q. M.; Yang, X. Y.

    The powders as well as the texture modulated Ca2.8BaxPryCo4O9+δ (x, y = 0, 0.05, 0.1, 0.15 and 0.2) bulk materials are prepared via solid state reaction, sol-gel and spark plasma sintering method. The powder and bulk materials are analyzed with regard to their phase composition and microscopic character by X-ray diffraction (XRD) and scanning electron microscope (SEM). The thermoelectric transport properties of the bulk materials are measured and investigated. The results show that the plate-like powders with uniform particle size tend to align regularly rather than the powders with anomaly shape and particle size distribution by spark plasma sintering method. The bulk materials co-doped by elements with lower electronegativity tend to form better texture rather than that of the bulk materials co-doped by elements with higher electronegativity via spark plasma sintering method. The resistivities and Seebeck coefficients are in negative accordance to the bulk material texture as a whole, and the carrier transport mechanism is not influenced. The electrical performance is tuned with optimized power factor 462 μW m-1 K-2 at 973 K for Ca2.8BaxPryCo4O9+δ (x = y = 0.1) bulk materials.

  17. Transcriptionally and post-transcriptionally regulated microRNAs in heat stress response in barley

    PubMed Central

    Kruszka, Katarzyna; Pacak, Andrzej; Swida-Barteczka, Aleksandra; Nuc, Przemyslaw; Alaba, Sylwia; Wroblewska, Zuzanna; Karlowski, Wojciech; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2014-01-01

    Heat stress is one of the major abiotic factors that can induce severe plant damage, leading to a decrease in crop plant productivity. Despite barley being a cereal of great economic importance, few data are available concerning its thermotolerance mechanisms. In this work microRNAs (miRNAs) involved in heat stress response in barley were investigated. The level of selected barley mature miRNAs was examined by hybridization. Quantitative real-time PCR (RT-qPCR) was used to monitor the changes in the expression profiles of primary miRNA (pri-miRNA) precursors, as well as novel and conserved target genes during heat stress. The miRNA-mediated cleavage sites in the target transcripts were confirmed by degradome analysis and the 5’ RACE (rapid amplification of cDNA ends) approach. Four barley miRNAs (miR160a, 166a, 167h, and 5175a) were found which are heat stress up-regulated at the level of both mature miRNAs and precursor pri-miRNAs. Moreover, the splicing of introns hosting miR160a and miR5175a is also heat induced. The results demonstrate transcriptional and post-transcriptional regulation of heat-responsive miRNAs in barley. The observed induction of miRNA expression is correlated with the down-regulation of the expression level of their experimentally identified new and conservative target genes. PMID:25183744

  18. N-Phosphino-amidines and -guanidines: synthesis, structure and P,N-chelate chemistry.

    PubMed

    Baiget, Lise; Batsanov, Andrei S; Dyer, Philip W; Fox, Mark A; Hanton, Martin J; Howard, Judith A K; Lane, Philip K; Solomon, Sophia A

    2008-02-28

    The syntheses of the cyclic N-phosphino-amidines and -guanidines Ph2PN(Pri)C(NPri2)N(Pri) ( 1) and Ph2PN(c-Hex)C(R)N(c-Hex) [R = piperazino ( 2), morpholino ( 3), Me ( 4), and Ph ( 5)] are reported. DFT studies have identified the preferred structures for compounds 1-5 with the E-configuration being the most stable form for the N-phosphino-amidines, while the Z-conformation is preferred for the N-phosphino-guanidines something that highlights the potential of such systems to act as kappa2-P,N-chelates. The differences in donor characteristics of 2-5 have been probed through the study of their corresponding P(V) selenide derivatives ( 6-9) and their complexes with the cis-RhCl(CO) (10-12) and cis-PdCl2 (13-17) fragments. In line with the DFT studies both the amidines and guanidines are found to coordinate as kappa2-P,N-chelates, with the latter being moderately weaker donor ligands. The molecular structures of compounds 3 and 4, together with those of the Rh and Pd complexes 10 and 15, respectively, have been determined in the solid state by X-ray crystallography, the latter confirming bidentate kappa2-P,N-chelation. PMID:18274685

  19. Regulation of Senescence by microRNA Biogenesis Factors

    PubMed Central

    Abdelmohsen, Kotb; Srikantan, Subramanya; Kang, Min-Ju; Gorospe, Myriam

    2012-01-01

    Senescence represents a state of indefinite growth arrest in cells that have reached their replicative life span, have become damaged, or express aberrant levels of cancer-related proteins. While senescence is widely considered to represent tumor-suppressive mechanism, the accumulation of senescent cells in tissues of older organisms is believed to underlie age-associated losses in physiologic function and age-related diseases. With the emergence of microRNAs (miRNAs) as a major class of molecular regulators of senescence, we review the transcriptional and post-transcriptional factors that control senescence-associated microRNA biosynthesis. Focusing on their enhancement or repression of senescence, we describe the transcription factors that govern the synthesis of primary (pri-)miRNAs, the proteins that control the nuclear processing of pri-miRNAs into precursor (pre-)miRNAs, including RNA editing enzymes, RNases, and RNA helicases, and the cytoplasmic proteins that affect the final processing of pre-miRNAs into mature miRNAs. We discuss how miRNA biogenesis proteins enhance or repress senescence, and thus influence the senescent phenotype that affects normal tissue function and pathology. PMID:22306790

  20. Investigation of the influence of mallet and chisel techniques on the lingual fracture line and comparison with the use of splitter and separators during sagittal split osteotomy in cadaveric pig mandibles.

    PubMed

    Verweij, Jop P; Mensink, Gertjan; Houppermans, Pascal N W J; Frank, Michael D; van Merkesteyn, J P Richard

    2015-04-01

    In bilateral sagittal split osteotomy the proximal and distal segments of the mandible are traditionally separated using chisels. Modern modifications include prying and spreading the segments with splitters. This study investigates the lingual fracture patterns and status of the nerve after sagittal split osteotomy (SSO) using the traditional chisel technique and compares these results with earlier studies using the splitter technique. Lingual fractures after SSO in cadaveric pig mandibles were analysed using a lingual split scale and split scoring system. Iatrogenic damage to the inferior alveolar nerve was assessed. Fractures started through the caudal cortex more frequently in the chisel group. This group showed more posterior lingual fractures, although this difference was not statistically significant. Nerve damage was present in three cases in the chisel group, but was not observed in the splitter group. A trend was apparent, that SSO using the chisel technique instead of the splitter technique resulted in more posterior lingual fracture lines, although this difference was not statistically significant. Both techniques resulted in reliable lingual fracture patterns. Splitting without chisels could prevent nerve damage, therefore we propose a spreading and prying technique with splitter and separators. However, caution should be exercised when extrapolating these results to the clinic. PMID:25697050

  1. Mutant p53 induces EZH2 expression and promotes epithelial–mesenchymal transition by disrupting p68-Drosha complex assembly and attenuating miR-26a processing

    PubMed Central

    Wang, Hui-Hui; Zhang, Hui-Lin; Zhang, Jian; Yan, Xiao-Fang; Wang, Xiao-Jun; Che, Qi; Ke, Jie-Qi; Chen, Zheng; Tong, Huan; Zhang, Yong-Li; Wang, Fang-Yuan; Li, Yi-Ran; Wan, Xiao-Ping

    2015-01-01

    The tumor suppressor p53 and the transcriptional repressor Enhancer of Zeste Homolog 2 (EZH2) have both been implicated in the regulation of epithelial-mesenchymal transition (EMT) and tumor metastasis via their impacts on microRNA expression. Here, we report that mutant p53 (mutp53) promotes EMT in endometrial carcinoma (EC) by disrupting p68-Drosha complex assembly. Overexpression of mutp53 has the opposite effect of wild-type p53 (WTp53), repressing miR-26a expression by reducing pri-miR-26a-1 processing in p53-null EC cells. Re-expression of miR-26a in mutp53 EC cells decreases cell invasion and promotes mesenchymal-epithelial transition (MET). Rescuing miR-26a expression also inhibits EZH2, N-cadherin, Vimentin, and Snail expression and induces E-cadherin expression both in vitro and in vivo. Moreover, patients with higher serum miR-26a levels have a better survival rate. These results suggest that p53 gain-of-function mutations accelerate EC tumor progression and metastasis by interfering with Drosha and p68 binding and pri-miR-26a-1 processing, resulting in reduced miR-26a expression and EZH2 overexpression. PMID:26587974

  2. Using Indentation to Characterize Water Transport and Structure in Nafion Thin Films

    NASA Astrophysics Data System (ADS)

    Davis, Eric; Nadermann, Nichole; Page, Kirt; Stafford, Christopher; Chan, Edwin

    Perfluorinated ionomers, specifically Nafion, are the state-of-the-art polymer used in fuel cells. For this application, Nafion is utilized in both a bulk (hundreds of microns) and confined (tens of nanometers) state. For Nafion thin films in a confined state, i.e., Nafion as thin film coatings on catalyst particles, in-plane transport may play a critical role in the movement of water and protons through this catalysis layer. In this study, water transport was measured for a series of Nafion thin film thicknesses using poroelastic relaxation indentation (PRI). Unlike traditional through-thickness diffusion measurement techniques for thin polymer films (e.g., quartz crystal microbalance), PRI can be used to probe the in-plane water transport behavior. Relative to bulk Nafion, reduced in-plane water diffusion was observed in thin film Nafion, and below approximately 1 micron, water diffusivity and Nafion film thickness exhibited a logarithmic relationship. Equilibrium swelling measurements of water saturated Nafion thin films were used in conjunction with pore network theory to develop a picture of how the molecular-scale structure of Nafion changes with confinement to nanoscale film thicknesses. Using Indentation to Characterize Water Transport and Structure in Nafion Thin Films.

  3. [Development of the Coparental Regulation Inventory and cross-sectional analysis of mothers' encouragement and criticism].

    PubMed

    Kato, Michiyo; Kurosawa, Tai; Kamiya, Tetsuji

    2014-02-01

    We developed the Coparental Regulation Inventory to assess the regulatory behavior of the mothers in involving fathers with child rearing. We translated and modified the short form of the Parental Regulation Inventory (PRI) for Japanese couples in different stages of child rearing. An online questionnaire was conducted with mothers (n = 500) and fathers (n = 500) whose youngest child was less than 21-years-old. Exploratory factor analysis identified two factors, which were labeled "encouragement" and "criticism". The resulting Coparental Regulation Inventory (the modified PRI) had high internal consistency and test-retest reliability. The construct validity of the scale was supported by its correlation with parenting alliance, marital satisfaction, and the father's involvement. These findings suggest that the scale is an adequate instrument for identifying the behaviors of mothers related to coparenting. In addition, we examined the frequency of encouragement and criticism used by the mother in relation to the child-rearing stage using cross-sectional analysis. In the mothers' reports, mothers with infants and children encouraged fathers more than mothers with early and late adolescents. Mothers with late adolescents criticized fathers less than mothers with infants. In the fathers' reports, mothers gave more encouragement to fathers who had infants than at any other age, whereas the child's age was not related to mothers' criticism perceived by the fathers. PMID:24669497

  4. Estimation of arsenic in agricultural soils using hyperspectral vegetation indices of rice.

    PubMed

    Shi, Tiezhu; Liu, Huizeng; Chen, Yiyun; Wang, Junjie; Wu, Guofeng

    2016-05-01

    This study systematically analyzed the performance of multivariate hyperspectral vegetation indices of rice (Oryza sativa L.) in estimating the arsenic content in agricultural soils. Field canopy reflectance spectra was obtained in the jointing-booting growth stage of rice. Newly developed and published multivariate vegetation indices were initially calculated to estimate soil arsenic content. The well-performing vegetation indices were then selected using successive projections algorithm (SPA), and the SPA selected vegetation indices were adopted to calibrate a multiple linear regression model for estimating soil arsenic content. Results showed that a three-band vegetation index (R716-R568)/(R552-R568) performed best in the newly developed vegetation indices in estimating soil arsenic content. The photochemical reflectance index (PRI) and red edge position (REP) performed well in the published vegetation indices. Moreover, the linear combination of two vegetation indices ((R716-R568)/(R552-R568) and REP) selected using SPA improved the estimation of soil arsenic content. These results indicated that the newly developed three-band vegetation index (R716-R568)/(R552-R568) might be recommended as an indicator for estimating soil arsenic content in the study area. PRI and REP could be used as universal vegetation indices for monitoring soil arsenic contamination. PMID:26844405

  5. On Estimating Provenances of Lunar Highland Materials

    NASA Technical Reports Server (NTRS)

    Haskin, Larry A.; Jolliff, Brad L.

    1998-01-01

    That even relatively small impacts can spread material across the face of the Moon is evident from the rays of Tycho. Tycho ejecta triggered the landslide that produced the light mantle deposit at Apollo 17 and perhaps excavated the Central Valley craters there. Basin-sized impacts appear to follow the same scaling laws as smaller impacts, as indicated by the satisfaction of a geophysical model. These giant impacts rearranged huge amounts of premare material, complicating the determination of provenance of materials collected from the highlands. We have developed a model to estimate the probability that material at a particular location might derive from a given basin or large crater. This model is based on crater scaling laws, and effects of secondary cratering. Because it accounts for the volume of primary ejecta from the basin-forming transient craters and the excavating and mixing effects of these ejecta with the substrate onto which they fall, it gives much thicker deposits than an early work. Our modeling takes into account the distribution of sizes of primary ejecta fragments (PriFrags) to obtain the probability at a given site for a deposit of a particular thickness and with a fraction of PriFrags.

  6. Arabidopsis microRNA expression regulation in a wide range of abiotic stress responses

    PubMed Central

    Barciszewska-Pacak, Maria; Milanowska, Kaja; Knop, Katarzyna; Bielewicz, Dawid; Nuc, Przemyslaw; Plewka, Patrycja; Pacak, Andrzej M.; Vazquez, Franck; Karlowski, Wojciech; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2015-01-01

    Arabidopsis microRNA expression regulation was studied in a wide array of abiotic stresses such as drought, heat, salinity, copper excess/deficiency, cadmium excess, and sulfur deficiency. A home-built RT-qPCR mirEX platform for the amplification of 289 Arabidopsis microRNA transcripts was used to study their response to abiotic stresses. Small RNA sequencing, Northern hybridization, and TaqMan® microRNA assays were performed to study the abundance of mature microRNAs. A broad response on the level of primary miRNAs (pri-miRNAs) was observed. However, stress response at the level of mature microRNAs was rather confined. The data presented show that in most instances, the level of a particular mature miRNA could not be predicted based on the level of its pri-miRNA. This points to an essential role of posttranscriptional regulation of microRNA expression. New Arabidopsis microRNAs responsive to abiotic stresses were discovered. Four microRNAs: miR319a/b, miR319b.2, and miR400 have been found to be responsive to several abiotic stresses and thus can be regarded as general stress-responsive microRNA species. PMID:26089831

  7. The tumor suppressor APC differentially regulates multiple β-catenins through the function of axin and CKIα during C. elegans asymmetric stem cell divisions.

    PubMed

    Baldwin, Austin T; Phillips, Bryan T

    2014-06-15

    The APC tumor suppressor regulates diverse stem cell processes including gene regulation through Wnt-β-catenin signaling and chromosome stability through microtubule interactions, but how the disparate functions of APC are controlled is not well understood. Acting as part of a Wnt-β-catenin pathway that controls asymmetric cell division, Caenorhabditis elegans APC, APR-1, promotes asymmetric nuclear export of the β-catenin WRM-1 by asymmetrically stabilizing microtubules. Wnt function also depends on a second β-catenin, SYS-1, which binds to the C. elegans TCF POP-1 to activate gene expression. Here, we show that APR-1 regulates SYS-1 levels in asymmetric stem cell division, in addition to its known role in lowering nuclear levels of WRM-1. We demonstrate that SYS-1 is also negatively regulated by the C. elegans homolog of casein kinase 1α (CKIα), KIN-19. We show that KIN-19 restricts APR-1 localization, thereby regulating nuclear WRM-1. Finally, the polarity of APR-1 cortical localization is controlled by PRY-1 (C. elegans Axin), such that PRY-1 controls the polarity of both SYS-1 and WRM-1 asymmetries. We propose a model whereby Wnt signaling, through CKIα, regulates the function of two distinct pools of APC - one APC pool negatively regulates SYS-1, whereas the second pool stabilizes microtubules and promotes WRM-1 nuclear export. PMID:24762815

  8. A unique feeding strategy of the extinct marine mammal Kolponomos: convergence on sabretooths and sea otters.

    PubMed

    Tseng, Z Jack; Grohé, Camille; Flynn, John J

    2016-03-16

    Mammalian molluscivores feed mainly by shell-crushing or suction-feeding. The extinct marine arctoid, Kolponomos, has been interpreted as an otter-like shell-crusher based on similar dentitions. However, neither the masticatory biomechanics of the shell-crushing adaptation nor the way Kolponomos may have captured hard-shelled prey have been tested. Based on mandibular symphyseal morphology shared by Kolponomos and sabre-toothed carnivores, we hypothesize a sabretooth-like mechanism for Kolponomos prey-capture, whereby the mandible functioned as an anchor. Torque generated from jaw closure and head flexion was used to dislodge prey by prying, with prey then crushed using cheek teeth. We test this hypothesized feeding sequence using phylogenetically informed biomechanical simulations and shape analyses, and find a strongly supported, shared high mandibular stiffness in simulated prey-capture bites and mandibular shape in Kolponomos and the sabre-toothed cat Smilodon. These two distantly related taxa converged on using mandibles to anchor cranial torqueing forces when prying substrate-bound prey in the former and sabre-driving forces during prey-killing in the latter. Simulated prey-crushing bites indicate that Kolponomos and sea otters exhibit alternative structural stiffness-bite efficiency combinations in mandibular biomechanical adaptation for shell-crushing. This unique feeding system of Kolponomos exemplifies a mosaic of form-function convergence relative to other Carnivora. PMID:26936242

  9. Airborne remote sensing of photosynthetic light use efficiency and carbon uptake along an Arctic transect in Finland

    NASA Astrophysics Data System (ADS)

    Atherton, J.; Hill, T. C.; Prieto-Blanco, A.; Wade, T.; Clement, R.; Moncrieff, J.; Williams, M. D.; Disney, M.; Nichol, C. J.

    2009-12-01

    It is critical to understand the dynamics of ecosystem carbon uptake through seasonal changes and in response to environmental drivers. In this study we utilised aircraft based remote sensing and CO2/H2O flux monitoring systems to quantify changes in photosynthesis along an Arctic transect. The University of Edinburgh's (UK) research aircraft (a Diamond HK 36 TTC-ECO Dimona) was deployed in the Arctic during summer 2008 to carry out a series of transect-flights over a birch-mire mosaic site near Kevo, Finland as part of the Arctic Biosphere Atmosphere Coupling at Multiple Scales (ABACUS) project. The aircraft is equipped with automated dual field-of-view (hyperspectral) radiometers and CO2/H2O flux and meteorological instrumentation. Vegetation indices known to be related to photosynthetic light use efficiency (LUE), including the well established Photochemical Reflectance Index (PRI) and Solar-induced Fluorescence (SiF) as well as the Normalized Difference Vegetation Index (NDVI) were calculated from the spectral data and matched in space to the CO2 flux measurements. We explored spatial relationships between NDVI and CO2 flux, LUE (CO2 flux / Absorbed Photosynthetically Active Radiation) and PRI and finally SiF (calculated using the Fraunhofer infilling method) and relevant environmental drivers. Our results highlight the unique ability of an airborne platform to quantify ecosystem physiology across a landscape and demonstrate how such measurements can bridge the spatial gap between ground and satellite-based observations.

  10. Using molecular tools to decipher the complex world of plant resistance inducers: an apple case study.

    PubMed

    Dugé de Bernonville, Thomas; Marolleau, Brice; Staub, Johan; Gaucher, Matthieu; Brisset, Marie-Noëlle

    2014-11-26

    Exogenous application of plant resistance inducers (PRIs) able to activate plant defenses is an interesting approach for new integrated pest management practices. The full integration of PRIs into agricultural practices requires methods for the fast and objective upstream screening of efficient PRIs and optimization of their application. To select active PRIs, we used a molecular tool as an alternative to methods involving plant protection assays. The expressions of 28 genes involved in complementary plant defense mechanisms were simultaneously determined by quantitative real-time PCR in PRI-treated tissues. Using a set of 10 commercial preparations and considering the pathosystem apple/Erwinia amylovora, this study shows a strong correlation between defense activation and protection efficiency in controlled conditions, thus enabling the easy identification of promising PRIs in fire blight protection. Hence this work clearly highlights the benefits of using a molecular tool to discriminate nonactive PRI preparations and provides useful molecular markers for the optimization of their use in orchard. PMID:25372566

  11. Protecting Data Privacy in Structured P2P Networks

    NASA Astrophysics Data System (ADS)

    Jawad, Mohamed; Serrano-Alvarado, Patricia; Valduriez, Patrick

    P2P systems are increasingly used for efficient, scalable data sharing. Popular applications focus on massive file sharing. However, advanced applications such as online communities (e.g., medical or research communities) need to share private or sensitive data. Currently, in P2P systems, untrusted peers can easily violate data privacy by using data for malicious purposes (e.g., fraudulence, profiling). To prevent such behavior, the well accepted Hippocratic database principle states that data owners should specify the purpose for which their data will be collected. In this paper, we apply such principles as well as reputation techniques to support purpose and trust in structured P2P systems. Hippocratic databases enforce purpose-based privacy while reputation techniques guarantee trust. We propose a P2P data privacy model which combines the Hippocratic principles and the trust notions. We also present the algorithms of PriServ, a DHT-based P2P privacy service which supports this model and prevents data privacy violation. We show, in a performance evaluation, that PriServ introduces a small overhead.

  12. ADAR1 Activation Drives Leukemia Stem Cell Self-Renewal by Impairing Let-7 Biogenesis.

    PubMed

    Zipeto, Maria Anna; Court, Angela C; Sadarangani, Anil; Delos Santos, Nathaniel P; Balaian, Larisa; Chun, Hye-Jung; Pineda, Gabriel; Morris, Sheldon R; Mason, Cayla N; Geron, Ifat; Barrett, Christian; Goff, Daniel J; Wall, Russell; Pellecchia, Maurizio; Minden, Mark; Frazer, Kelly A; Marra, Marco A; Crews, Leslie A; Jiang, Qingfei; Jamieson, Catriona H M

    2016-08-01

    Post-transcriptional adenosine-to-inosine RNA editing mediated by adenosine deaminase acting on RNA1 (ADAR1) promotes cancer progression and therapeutic resistance. However, ADAR1 editase-dependent mechanisms governing leukemia stem cell (LSC) generation have not been elucidated. In blast crisis chronic myeloid leukemia (BC CML), we show that increased JAK2 signaling and BCR-ABL1 amplification activate ADAR1. In a humanized BC CML mouse model, combined JAK2 and BCR-ABL1 inhibition prevents LSC self-renewal commensurate with ADAR1 downregulation. Lentiviral ADAR1 wild-type, but not an editing-defective ADAR1(E912A) mutant, induces self-renewal gene expression and impairs biogenesis of stem cell regulatory let-7 microRNAs. Combined RNA sequencing, qRT-PCR, CLIP-ADAR1, and pri-let-7 mutagenesis data suggest that ADAR1 promotes LSC generation via let-7 pri-microRNA editing and LIN28B upregulation. A small-molecule tool compound antagonizes ADAR1's effect on LSC self-renewal in stromal co-cultures and restores let-7 biogenesis. Thus, ADAR1 activation represents a unique therapeutic vulnerability in LSCs with active JAK2 signaling. PMID:27292188

  13. Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex

    PubMed Central

    Gardner, Benedict M.; Balázs, Gábor; Wooles, Ashley J.; Tuna, Floriana; McInnes, Eric J. L.; McMaster, Jonathan; Lewis, William; Blake, Alexander J.

    2015-01-01

    Abstract The HAsAsH molecule has hitherto only been proposed tentatively as a short‐lived species generated in electrochemical or microwave‐plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(TrenTIPS)}2(μ‐η2:η2‐As2H2)] (3, TrenTIPS=N(CH2CH2NSiPri 3)3; Pri=CH(CH3)2). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back‐bonding‐type interactions from uranium to the HAsAsH π*‐orbital. This experimentally confirms the theoretically predicted excellent π‐acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane‐1,2‐diide form. PMID:27478272

  14. Isolation of Elusive HAsAsH in a Crystalline Diuranium(IV) Complex

    PubMed Central

    Gardner, Benedict M; Balázs, Gábor; Scheer, Manfred; Wooles, Ashley J; Tuna, Floriana; McInnes, Eric J L; McMaster, Jonathan; Lewis, William; Blake, Alexander J; Liddle, Stephen T

    2015-01-01

    The HAsAsH molecule has hitherto only been proposed tentatively as a short-lived species generated in electrochemical or microwave-plasma experiments. After two centuries of inconclusive or disproven claims of HAsAsH formation in the condensed phase, we report the isolation and structural authentication of HAsAsH in the diuranium(IV) complex [{U(TrenTIPS)}2(μ-η2:η2-As2H2)] (3, TrenTIPS=N(CH2CH2NSiPri3)3; Pri=CH(CH3)2). Complex 3 was prepared by deprotonation and oxidative homocoupling of an arsenide precursor. Characterization and computational data are consistent with back-bonding-type interactions from uranium to the HAsAsH π*-orbital. This experimentally confirms the theoretically predicted excellent π-acceptor character of HAsAsH, and is tantamount to full reduction to the diarsane-1,2-diide form. PMID:26510123

  15. Unified Field Theory and Force Formulas of Interactions

    NASA Astrophysics Data System (ADS)

    Ma, Tian; Wang, Shouhong

    2013-04-01

    The main objective of this talk is to drive a unified field model coupling four interactions, based on the principle of interaction dynamics (PID) and the principle of representation invariance (PID). Intuitively, PID takes the variation of the action functional under energy-momentum conservation constraint. PRI requires that physical laws be independent of representations of the gauge groups. One important outcome of this unified field model is a natural duality between the interacting fields (g, A, W^a, S^k), corresponding to graviton, photon, intermediate vector bosons W^± and Z and gluons, and the adjoint bosonic fields (φ,, ^aw, ^ks). This duality predicts two Higgs particles of similar mass with one due to weak interaction and the other due to strong interaction. PID and PRI can be applied directly to individual interactions, leading to 1) modified Einstein equations, giving rise to a unified theory for dark matter and dark energy, 2) three levels of strong interaction potentials for quark, nucleon/hadron, and atom respectively, and 3) a weak interaction potential. These potential/force formulas offer a clear mechanism for both quark confinement and asymptotic freedom.

  16. Distinct E-cadherin-based complexes regulate cell behaviour through miRNA processing or Src and p120 catenin activity

    PubMed Central

    Kourtidis, Antonis; Ngok, Siu P.; Pulimeno, Pamela; Feathers, Ryan W.; Carpio, Lomeli R.; Baker, Tiffany R.; Carr, Jennifer M.; Yan, Irene K.; Borges, Sahra; Perez, Edith A.; Storz, Peter; Copland, John A.; Patel, Tushar; Thompson, E. Aubrey; Citi, Sandra; Anastasiadis, Panos Z.

    2016-01-01

    E-cadherin and p120 catenin (p120) are essential for epithelial homeostasis, but can also exert pro-tumorigenic activities. Here, we resolve this apparent paradox by identifying two spatially and functionally distinct junctional complexes in non-transformed polarized epithelial cells: one growth suppressing at the apical zonula adherens (ZA), defined by the p120 partner PLEKHA7 and a non-nuclear subset of the core microprocessor components DROSHA and DGCR8, and one growth promoting at basolateral areas of cell–cell contact containing tyrosine-phosphorylated p120 and active Src. Recruitment of DROSHA and DGCR8 to the ZA is PLEKHA7 dependent. The PLEKHA7–microprocessor complex co-precipitates with primary microRNAs (pri-miRNAs) and possesses pri-miRNA processing activity. PLEKHA7 regulates the levels of select miRNAs, in particular processing of miR-30b, to suppress expression of cell transforming markers promoted by the basolateral complex, including SNAI1, MYC and CCND1. Our work identifies a mechanism through which adhesion complexes regulate cellular behaviour and reveals their surprising association with the microprocessor. PMID:26302406

  17. Relation of Chlorophyll Fluorescence Sensitive Reflectance Ratios to Carbon Flux Measurements of Montanne Grassland and Norway Spruce Forest Ecosystems in the Temperate Zone

    PubMed Central

    Ač, Alexander; Malenovský, Zbyněk; Urban, Otmar; Hanuš, Jan; Zitová, Martina; Navrátil, Martin; Vráblová, Martina; Olejníčková, Julie; Špunda, Vladimír; Marek, Michal

    2012-01-01

    We explored ability of reflectance vegetation indexes (VIs) related to chlorophyll fluorescence emission (R686/R630, R740/R800) and de-epoxidation state of xanthophyll cycle pigments (PRI, calculated as (R531 − R570)/(R531 − R570)) to track changes in the CO2 assimilation rate and Light Use Efficiency (LUE) in montane grassland and Norway spruce forest ecosystems, both at leaf and also canopy level. VIs were measured at two research plots using a ground-based high spatial/spectral resolution imaging spectroscopy technique. No significant relationship between VIs and leaf light-saturated CO2 assimilation (AMAX) was detected in instantaneous measurements of grassland under steady-state irradiance conditions. Once the temporal dimension and daily irradiance variation were included into the experimental setup, statistically significant changes in VIs related to tested physiological parameters were revealed. ΔPRI and Δ(R686/R630) of grassland plant leaves under dark-to-full sunlight transition in the scale of minutes were significantly related to AMAX (R2 = 0.51). In the daily course, the variation of VIs measured in one-hour intervals correlated well with the variation of Gross Primary Production (GPP), Net Ecosystem Exchange (NEE), and LUE estimated via the eddy-covariance flux tower. Statistical results were weaker in the case of the grassland ecosystem, with the strongest statistical relation of the index R686/R630 with NEE and GPP. PMID:22701368

  18. Absolute calibration of the fast-delivery SAR product processed at Tromso satellite station

    NASA Astrophysics Data System (ADS)

    Weydahl, Dan J.

    1994-12-01

    Tromso Satellite Station (TSS) is the Norwegian national receiving station for ERS-1 SAR data. The TSS Fast Delivery (FD) SAR processor was upgraded during spring 1994 so that the whole processing chain will now be performed in power rather than in voltage. This new FD SAR product from TSS needs absolute calibration, and a calibration constant is therefore estimated. First, a TSS Power-processed ERS-1 SAR image was used. This image covers the ESA transponders in Flevoland. The integration method was used to estimate the backscattered power from the 3 transponders. The Earth ellipsoid, local incidence angle, antenna pattern, range-spread loss, pixel size and RCS were also taken into account in the calculation. The result was a calibration constant of 53.51 dB. An other method is to compare the backscatter from an ESA processed PRI product and a TSS Power-processed FD product acquired at the same place and time. Areas were extracted from two such SAR images, and the pixel values averaged in power. The known calibration constant for the PRI product was used in the comparison of the image products. The calibration constant for the TSS FD product was then found to be 54.20 dB. This is close to the result from using the ESA transponders.

  19. Relating a Spectral Index from MODIS and Tower-based Measurements to Ecosystem Light Use Efficiency for a Fluxnet-Canada Coniferous Forest

    NASA Technical Reports Server (NTRS)

    Middleton, Elizabeth M.; Cheng, Yen-Ben; Hilker, Thomas; Huemmrich, Karl F.; Black, T. Andrew; Krishnan, Praveena; Coops, Nicholas C.

    2008-01-01

    As part of the North American Carbon Program effort to quantify the terrestrial carbon budget of North America, we have been examining the possibility of retrieving ecosystem light use efficiency (LUE, the carbon sequestered per unit photosynthetically active radiation) directly from satellite observations. Our novel approach has been to compare LUE derived from tower fluxes with LUE estimated using spectral indices computed from MODIS satellite observations over forests in the Fluxnet-Canada Research Network, using the MODIS narrow ocean bands acquired over land. We matched carbon flux data collected around the time of the MODIS mid-day overpass for over one hundred relatively clear days in five years (2001-2006) from a mature Douglas fir forest in British Columbia. We also examined hyperspectral reflectance data collected diurnally from the tower in conjunction with the eddy correlation fluxes and meteorological measurements made throughout the 2006 growing season at this site. The tower-based flux data provided an opportunity to examine diurnal and seasonal LUE processes and their relationship to spectral indices at the scale of the forest stand. We evaluated LUE in conjunction with the Photochemical Reflectance Index (PRI), a normalized difference spectral index that uses 531 nm and a reference band to capture responses to high light induced stress afforded by the xanthophyll cycle. Canopy structure information, retrieved from airborne laser scanning radar (LiDAR) observations, was used to partition the forest canopy into sunlit and shaded fractions throughout the day, on numerous days during 2006. At each observation period throughout a day, the PRI was examined for the sunlit, shaded, and intermediate canopy segments defined by their instantaneous position relative to the solar principal plane (SPP). The sunlit sector was associated with the illumination "hotspot" (the reflectance backscatter maximum), the shaded sector with the "cold or dark spot" (the

  20. Microbial Small Talk: Volatiles in Fungal–Bacterial Interactions

    PubMed Central

    Schmidt, Ruth; Etalo, Desalegn W.; de Jager, Victor; Gerards, Saskia; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2016-01-01

    There is increasing evidence that volatile organic compounds (VOCs) play an important role in the interactions between fungi and bacteria, two major groups of soil inhabiting microorganisms. Yet, most of the research has been focused on effects of bacterial volatiles on suppression of plant pathogenic fungi whereas little is known about the responses of bacteria to fungal volatiles. In the current study we performed a metabolomics analysis of volatiles emitted by several fungal and oomycetal soil strains under different nutrient conditions and growth stages. The metabolomics analysis of the tested fungal and oomycetal strains revealed different volatile profiles dependent on the age of the strains and nutrient conditions. Furthermore, we screened the phenotypic responses of soil bacterial strains to volatiles emitted by fungi. Two bacteria, Collimonas pratensis Ter291 and Serratia plymuthica PRI-2C, showed significant changes in their motility, in particular to volatiles emitted by Fusarium culmorum. This fungus produced a unique volatile blend, including several terpenes. Four of these terpenes were selected for further tests to investigate if they influence bacterial motility. Indeed, these terpenes induced or reduced swimming and swarming motility of S. plymuthica PRI-2C and swarming motility of C. pratensis Ter291, partly in a concentration-dependent manner. Overall the results of this work revealed that bacteria are able to sense and respond to fungal volatiles giving further evidence to the suggested importance of volatiles as signaling molecules in fungal–bacterial interactions. PMID:26779150