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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. Crystallization of amorphous Fe90Zr10 under ball milling.

    PubMed

    Kwon, Young-Soon; Kim, Ji-Soon; Kim, Jin-Chun; Kwon, Yong-Jae; Povstugar, Ivan; Yelsukov, Eugene; Kim, Cheol-Eeh; Lee, Hyung-Soon

    2010-01-01

    The present study deals with structural transformations induced by high-energy ball-milling of an amorphous Fe90Zr10 alloy prepared by melt-spinning. The amorphous melt-spun ribbons were found to undergo crystallization into BCC alpha-Fe(Zr) nanocrystallites under high-energy ball milling. The decomposition degree of the amorphous phase increased with increasing milling time and intensity. Our results suggest that the observed crystallization is a deformation-induced process rather than a thermally induced one.

  4. 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.

  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. 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.

  7. 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.

  8. Evolution of Seawater 44Ca/40Ca Through the Late Cretaceous and Cenozoic

    NASA Astrophysics Data System (ADS)

    Castillo, P. R.; Gopalan, K.; Norris, R. D.; MacIsaac, C.; Liu, X.; MacDougall, J. D.

    2009-12-01

    We analyzed the Ca concentrations and 44Ca/40Ca ratios of surface ocean planktonic (Morozovella, Acarinina, Dentoglobigerina) and benthic (Gavelinella) foraminifera of Late Cretaceous to Late Oligocene ages from DSDP and ODP sites in the Pacific, Atlantic and Indian oceans in order to fill a major gap in the Phanerozoic seawater 44Ca/40Ca curve (Farkass et al., Geochim. Cosmochim. Acta 71, 2007). Our new 44Ca/40Ca data indicate a general increase in foraminiferan-based seawater 44Ca/40Ca from ~-1.3 ‰ δ44Ca/40CaSW in Late Cretaceous to ~0.0 ‰ δ44Ca/40CaSW in Early Miocene (Heuser et al., Paleocean. 20, 2005; Sime et al., Geochim. Cosmochim. Acta 71, 2007). In detail, the 44Ca/40Ca ratio stepped abruptly from ~-1.3 ‰ δ44Ca/40CaSW to a slightly higher value of ~-1.1 ‰ δ44Ca/40CaSW across the Cretaceous-Tertiary (K/T) boundary. A slight positive excursion of ~0.2 ‰ above the background value occurred after the Paleocene Thermal Maximum (55 Ma) but otherwise, the Paleocene to Middle Eocene ratio is relatively stable at ~-1.0 ‰ δ44Ca/40CaSW. The most prominent increase in foraminiferan-based seawater 44Ca/40Ca occurred from Late Eocene to Late Oligocene, roughly coincident with the initial phase of the rapid and steady rise of marine carbonate 87Sr/86Sr ratio in the Tertiary (e.g., DePaolo and Ingram, Science 227, 1985).

  9. 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.

  10. 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.

  11. A new method for 44Ca/40Ca determination using cool plasma MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Fietzke, J.; Eisenhauer, A.; Liebetrau, V.; Bock, B.; Gussone, N.; Nägler, T. F.; Dietzel, M.; Spero, H.; Bijma, J.; Dullo, C.

    2003-04-01

    Here we present a new technique for the direct measurement of 44Ca/40Ca isotope ratios on a MC-ICP-MS (Axiom) using the "cool plasma" technique. By reducing the plasma energy from about 1250 Watts to 400 Watts the isobaric effect resulting from 40Ar^+ can be significantly reduced enabling the simultaneous and precise measurement of 44Ca and 40Ca beam intensities in different Faraday cups. In contrast to the TIMS technique requiring a Ca double spike the isotope measurements on a MC-ICP-MS can be performed by bracketing standards. This reduces the effort for chemical preparations without loss of precision. Isobaric effects of MgO^+ and NaOH^+ interfering with 40Ca and MgOH_2 with 44Ca can be neglected by measuring Ca isotopes near the low mass edge of the peaks. No influences of Sr2+ were found monitoring on 43.5amu. Repeated measurements of two Johnson Matthey CaCO_3 standards (lot No. 4064 and lot No. 9912) revealed values of about -11.29 ppm and 0.57 ppm. These values are in accordance with previous values published by Russel et al. (1978) and Heuser et al. (2002). Repeated measurement of the NIST 915a CaCO_3 standard showed that the variance of a single δ44Ca measurement is about 0.28 ppm (2SD) being comparable with TIMS. MC-ICP-MS based δ44Ca values measured on inorganic precipitates are indistinguishable from earlier measurements of Gussone et al. (in press) based on TIMS δ44Ca measurements confirming that there is a positive δ44Ca-temperature gradient. Our study demonstrates the possibility to measure the whole dispersion of Ca isotopes with a MC-ICP-MS showing that 40Ca can be used for normalization of 44Ca. References Russel W. A. et al. (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochim. Cosmochim. Acta 42, 1075--1090. Heuser A. et al. (2002) Measurement of Calcium Isotopes (δ44Ca) Using a Multicollector TIMS Technique. Int. J. Mass Spec. 220, 387--399. Gussone N. et al. (in press) Model for Kinetic Effects on

  12. Measurement of true calcium absorption in premature infants using intravenous 46Ca and oral 44Ca.

    PubMed

    Hillman, L S; Tack, E; Covell, D G; Vieira, N E; Yergey, A L

    1988-06-01

    We have developed a method for measuring true fractional calcium absorption (alpha) in premature infants using two stable isotopes of calcium and tested it in seven studies in seven infants (birth weight 1543 +/- 65 g, gestation 32.8 +/- 7 wk). A total of 7.5 micrograms/kg 46Ca was given as a single intravenous bolus. Immediately thereafter 1.25 mg/kg of 44Ca was given in a single gavage feeding of standard infant formula (Enfamil). A metabolic isolette was used to obtain 4-h collections of urine for 24 h total. 46Ca and 44Ca were measured in urine by thermal ionization mass spectroscopy and expressed as the ratio to naturally occurring 48Ca. The differences in the 46Ca/48Ca and 44Ca/48Ca ratios from natural levels (delta % excess 46Ca and delta % excess 44Ca) were calculated. Percent absorption (alpha) equals a constant times cumulative delta % excess 44Ca/delta % excess 46Ca. The calculation of alpha is independent of urine volume or concentration. The delta % excess 46Ca, showed the expected multiexponential decline as a function of time, and delta % excess 44Ca usually peaked during a 4- to 8-h urine collection. Calculations of alpha using increasingly long sampling times showed that a plateau had been reached by 12 h. alpha values calculated after 16-24 h in the seven infants at 2 wk of age were 41, 48, 45, 46, 25, 55, and 51%. Repeat studies at 3 wk of age were 46, 60, and 54%. These values are somewhat higher than net percent calcium absorption values reported for standard formula and thus appear very appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. 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.

  14. 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.

  15. PriMux

    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.

  16. 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.

  17. 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.

  18. Microscopic interpretation of the (t, 3He) reaction at 130 MeV on 90Zr and isovector monopole strength

    NASA Astrophysics Data System (ADS)

    Guillot, J.

    2007-08-01

    The 130-MeV primary tritium beam of the AGOR facility with an intensity of up to 108 pps and the Big Bite Spectrometer experimental setup have been used to study the (t, 3He) reaction between 0° and 5° lab angles on 12C and 90Zr targets. The standard ray-tracing procedure has allowed us to obtain excitation-energy spectra up to 30 MeV in six angular bins for each residual nucleus, with an average energy resolution of 350 keV. We have used the DWBA reaction mechanism model to reproduce those spectra and their angular distributions. In this approximation, the form factor was treated as a folding of an effective projectile-nucleon interaction with a transition density. The effective projectile-nucleon interaction has been adjusted to reproduce the 0° cross section of the 1+ ground state of 12B populated in the 12C(t, 3He) reaction. We have employed RPA wave functions of excited states to construct the form factors. This DWBA+RPA analysis is used to compare calculated and experimental cross sections directly and to discuss the giant resonance excitations in the 90Y nucleus. In this talk, we give some details on this analysis. We show that there are important contributions of L = 2 transitions in the observed cross sections for the 1+ final states that explain the previous difficulties in clearly identifying the monopole strength distributions. We then have a better indication of where the L = 0 part is located with this reaction and its microscopic analysis.

  19. 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.

  20. Role of local heating in crystallization of amorphous alloys under ball milling: An experiment on Fe{sub 90}Zr{sub 10}

    SciTech Connect

    Kwon, Y. S.; Kim, J. S.; Povstugar, I. V.; Yelsukov, E. P.; Choi, P. P.

    2007-04-01

    Fe{sub 90}Zr{sub 10} was chosen as a model system to elucidate the roles of mechanical deformation and local heating in the phenomenon of ball-milling-induced crystallization of amorphous alloys. The structural evolution of melt-spun amorphous Fe{sub 90}Zr{sub 10} ribbons under different milling conditions and high-pressure torsion was investigated by means of x-ray diffraction, Moessbauer spectroscopy, and magnetic measurements. Despite a considerable difference in the local temperatures for high-energy and low-energy ball millings, cryomilling (under liquid nitrogen-cooling), and high-pressure torsion, amorphous Fe{sub 90}Zr{sub 10} crystallizes into a supersaturated {alpha}-Fe(Zr) solid solution in all cases. Local heating occurring under high- and low-energy millings only plays a minor role and leads to a slight shift of the crystallization products towards equilibrium state. Mechanical deformation was established as the primary cause of crystallization of the amorphous Fe-Zr alloy under ball milling.

  1. NUCLEAR PHYSICS Resonances-Excitation Calculation Studies Investigation of Δ(3, 3) in Ground State of 90Zr Cold Finite Heavy Nucleus at Equilibrium and Under Large Compression

    NASA Astrophysics Data System (ADS)

    Mohammed, H. E. Abu-Sei'leek

    2011-01-01

    A non-relativistic microscopic mean field theory of finite nuclei is investigated where the nucleus is described as a collection of nucleons and delta resonances. The ground state properties of 90Zr nucleus have been investigated at equilibrium and large amplitude compression using a realistic effective baryon-baryon Hamiltonian based on Reid Soft Core (RSC) potential. The sensitivity of the ground state properties is studied, such as binding energy, nuclear radius, radial density distribution, and single particle energies to the degree of compression. It is found that the most of increasing in the nuclear energy generated under compression is used to create the massive Δ particles. For 90Zr nucleus under compression at 2.5 times density of the normal nuclear density, the excited nucleons to Δ's are increased sharply up to 14% of the total number of constituents. This result is consistent with the values extracted from relativistic heavy-ion collisions. The single particle energy levels are calculated and their behaviors under compression are examined too. A good agreement between results with effective Hamiltonian and the phenomenological shell model for the low lying single-particle spectra is obtained. A considerable reduction in compressibility for the nucleus, and softening of the equation of state with the inclusion of the Δ's in the nuclear dynamics are suggested by the results.

  2. 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, ...

  3. The δ44Ca-temperature calibration on fossil and cultured Globigerinoides sacculifer: New tool for reconstruction of past sea surface temperatures

    NASA Astrophysics Data System (ADS)

    NäGler, T. F.; Eisenhauer, A.; Müller, A.; Hemleben, C.; Kramers, J.

    2000-09-01

    We report direct δ44Ca-temperature calibration on cultured and fossil calcite foraminifera, showing that Ca isotopes are potentially a new proxy for past sea surface temperatures (SST). Samples have been analyzed using a 43Ca-48Ca double spike and thermal ionization mass spectrometry (TIMS). In order to avoid species-dependent isotope fractionation we focused our investigations on a single foraminifera species (Globigerinoides sacculifer), which is known to inhabit shallow euphotic waters in tropical and subtropical oceans. Ca isotope measurements were performed on cultured G. sacculifer that grew in seawater kept at temperatures of 19.5°, 26.5°, and 29.5°C. A δ44Ca change of 0.24 ± 0.02 per 1°C is defined by the weighted linear regression through reproduced δ44Ca data of the three temperatures (95% confidence level). Application of this new method to fossil G. sacculifer of an Equatorial East Atlantic sediment core (GeoB1112; 5°46.7'S, 10°45.0'W, 3125 m) indicates that the δ44Ca difference between marine isotope stage 1 (MIS-1) and MIS-2 is 0.71 ± 0.24. According to the current δ44Ca-temperature calibration this value corresponds to a temperature difference between MIS-1 and MIS-2 of ˜3.0 ± 1.0°C.

  4. GMI in the reentrant spin-glass Fe90Zr10 alloy: Investigation of the spin dynamics in the MHz frequency regime

    NASA Astrophysics Data System (ADS)

    Ribeiro, P. R. T.; Ramírez, J. M. M.; Vidyasagar, R.; Machado, F. L. A.; Rezende, S. M.; Dahlberg, E. Dan

    2016-09-01

    Giant magnetoimpedance (GMI) in the reentrant spin-glass (SG) phase of ferromagnetic Fe90Zr10 is reported. The temperature (T) dependence of the GMI allows the investigation of the spin dynamics in the SG phase in the MHz frequency regime and thus very short relaxation times τ (˜10-8 s). The GMI shows a broad maximum around 150 K and diminishes with decreasing T below the glass temperature Tg of 15 K. The magnetic permeability data obtained from the GMI data show the general features observed in the ac magnetic susceptibility measured at lower frequencies (10 ≤ f ≤ 104 Hz), yielding values of Tf (=Tg(f)) that allow testing the validity of the power-law scaling used for describing the dynamics of SG-phases up to 15 MHz. A log-log plot of τ (=1/f) versus the reduced critical temperature shows two distinct regimes in the time-domain: (1) a critical slowing-down is observed for values τ > 3 × 10-3 s; and (2) for 7 × 10-8 ≤ τ ≤ 3 × 10-3 s. In the latter case a fitting to the power-law yields the value 7.4 for the product of the critical exponents zν, and 1.6 × 10-7 s for the microscopic relaxation time τ0. The product of the exponents is appropriate for an Ising spin glass.

  5. Optimization and application of ICPMS with dynamic reaction cell for precise determination of 44Ca/40Ca isotope ratios.

    PubMed

    Boulyga, Sergei F; Klötzli, Urs; Stingeder, Gerhard; Prohaska, Thomas

    2007-10-15

    An inductively coupled plasma mass spectrometer with dynamic reaction cell (ICP-DRC-MS) was optimized for determining (44)Ca/(40)Ca isotope ratios in aqueous solutions with respect to (i) repeatability, (ii) robustness, and (iii) stability. Ammonia as reaction gas allowed both the removal of (40)Ar+ interference on (40)Ca+ and collisional damping of ion density fluctuations of an ion beam extracted from an ICP. The effect of laboratory conditions as well as ICP-DRC-MS parameters such a nebulizer gas flow rate, rf power, lens potential, dwell time, or DRC parameters on precision and mass bias was studied. Precision (calculated using the "unbiased" or "n - 1" method) of a single isotope ratio measurement of a 60 ng g(-1) calcium solution (analysis time of 6 min) is routinely achievable in the range of 0.03-0.05%, which corresponded to the standard error of the mean value (n = 6) of 0.012-0.020%. These experimentally observed RSDs were close to theoretical precision values given by counting statistics. Accuracy of measured isotope ratios was assessed by comparative measurements of the same samples by ICP-DRC-MS and thermal ionization mass spectrometry (TIMS) by using isotope dilution with a (43)Ca-(48)Ca double spike. The analysis time in both cases was 1 h per analysis (10 blocks, each 6 min). The delta(44)Ca values measured by TIMS and ICP-DRC-MS with double-spike calibration in two samples (Ca ICP standard solution and digested NIST 1486 bone meal) coincided within the obtained precision. Although the applied isotope dilution with (43)Ca-(48)Ca double-spike compensates for time-dependent deviations of mass bias and allows achieving accurate results, this approach makes it necessary to measure an additional isotope pair, reducing the overall analysis time per isotope or increasing the total analysis time. Further development of external calibration by using a bracketing method would allow a wider use of ICP-DRC-MS for routine calcium isotopic measurements, but it

  6. Binding of two PriA-PriB complexes to the primosome assembly site initiates primosome formation.

    PubMed

    Szymanski, Michal R; Jezewska, Maria J; Bujalowski, Wlodzimierz

    2011-08-01

    A direct quantitative analysis of the initial steps in primosome assembly, involving PriA and PriB proteins and the minimal primosome assembly site (PAS) of phage ϕX174, has been performed using fluorescence intensity, fluorescence anisotropy titration, and fluorescence resonance energy transfer techniques. We show that two PriA molecules bind to the PAS at both strong and weak binding sites on the DNA, respectively, without detectable cooperative interactions. Binding of the PriB dimer to the PriA-PAS complex dramatically increases PriA's affinity for the strong site, but only slightly affects its affinity for the weak site. Associations with the strong and weak sites are driven by apparent entropy changes, with binding to the strong site accompanied by a large unfavorable enthalpy change. The PriA-PriB complex, formed independently of the DNA, is able to directly recognize the PAS without the preceding the binding of PriA to the PAS. Thus, the high-affinity state of PriA for PAS is generated through PriA-PriB interactions. The effect of PriB is specific for PriA-PAS association, but not for PriA-double-stranded DNA or PriA-single-stranded DNA interactions. Only complexes containing two PriA molecules can generate a profound change in the PAS structure in the presence of ATP. The obtained results provide a quantitative framework for the elucidation of further steps in primosome assembly and for quantitative analyses of other molecular machines of cellular metabolism.

  7. 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.

  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. Deinococcus radiodurans PriA is a Pseudohelicase.

    PubMed

    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.

  10. 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.

  11. Production of scandium-43 and -47 from a powdery calcium oxide target via the (nat/44)Ca(α,x)-channel.

    PubMed

    Minegishi, Katsuyuki; Nagatsu, Kotaro; Fukada, Masami; Suzuki, Hisashi; Ohya, Tomoyuki; Zhang, Ming-Rong

    2016-10-01

    We produced (43)Sc and (47)Sc via the (nat/44)Ca(α,x)-channel using a vertical beam coupled with a ceramic target box. After activation, the powdery CaO target material was dissolved in HCl in the target box in situ and remotely recovered as a radio-Sc solution. The respective yields of (43)Sc and (47)Sc following isolation via a precipitation method with a typical 0.22µm sterile filter were 54.8MBq/µAh (1.48mCi/µAh) and 780kBq/µAh (21.1µCi/µAh) at the end of separation (approximately 1.5h from the EOB). In addition, we discuss the recycling of target Ca. PMID:27472825

  12. Production of scandium-43 and -47 from a powdery calcium oxide target via the (nat/44)Ca(α,x)-channel.

    PubMed

    Minegishi, Katsuyuki; Nagatsu, Kotaro; Fukada, Masami; Suzuki, Hisashi; Ohya, Tomoyuki; Zhang, Ming-Rong

    2016-10-01

    We produced (43)Sc and (47)Sc via the (nat/44)Ca(α,x)-channel using a vertical beam coupled with a ceramic target box. After activation, the powdery CaO target material was dissolved in HCl in the target box in situ and remotely recovered as a radio-Sc solution. The respective yields of (43)Sc and (47)Sc following isolation via a precipitation method with a typical 0.22µm sterile filter were 54.8MBq/µAh (1.48mCi/µAh) and 780kBq/µAh (21.1µCi/µAh) at the end of separation (approximately 1.5h from the EOB). In addition, we discuss the recycling of target Ca.

  13. 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

  14. 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.

  15. 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

  16. 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).

  17. Stellar 30-keV neutron capture in 94, 96Zr and the 90Zr (γ , n)89Zr photonuclear reaction with a high-power liquid-lithium target

    NASA Astrophysics Data System (ADS)

    Tessler, M.; Paul, M.; Arenshtam, A.; Feinberg, G.; Friedman, M.; Halfon, S.; Kijel, D.; Weissman, L.; Aviv, O.; Berkovits, D.; Eisen, Y.; Eliyahu, I.; Haquin, G.; Kreisel, A.; Mardor, I.; Shimel, G.; Shor, A.; Silverman, I.; Yungrais, Z.

    2015-12-01

    A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target 7Li (p , n)7Be reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1-2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3- 5 ×1010 n /s, more than one order of magnitude larger than present near-threshold 7Li (p , n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94Zr and 96Zr as 28.0 ± 0.6 mb and 12.4 ± 0.5 mb respectively, based on activation measurements. The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets. In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt capture γ rays from the 7Li (p , γ)8Be reaction with yields of ∼ 3 ×108 γs-1mA-1 and ∼ 4 ×108 γs-1mA-1, respectively, evidenced by the 90Zr (γ , n)89Zr photonuclear reaction.

  18. 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,…

  19. 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

  20. 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

  1. Evidence for a cytoplasmic microprocessor of pri-miRNAs.

    PubMed

    Shapiro, Jillian S; Langlois, Ryan A; Pham, Alissa M; Tenoever, Benjamin R

    2012-07-01

    microRNAs (miRNAs) represent a class of noncoding RNAs that fine-tune gene expression through post-transcriptional silencing. While miRNA biogenesis occurs in a stepwise fashion, initiated by the nuclear microprocessor, rare noncanonical miRNAs have also been identified. Here we characterize the molecular components and unique attributes associated with the processing of virus-derived cytoplasmic primary miRNAs (c-pri-miRNAs). RNA in situ hybridization and inhibition of cellular division demonstrated a complete lack of nuclear involvement in c-pri-miRNA cleavage while genetic studies revealed that maturation still relied on the canonical nuclear RNase III enzyme, Drosha. The involvement of Drosha was mediated by a dramatic relocalization to the cytoplasm following virus infection. Deep sequencing analyses revealed that the cytoplasmic localization of Drosha does not impact the endogenous miRNA landscape during infection, despite allowing for robust synthesis of virus-derived miRNAs in the cytoplasm. Taken together, this research describes a unique function for Drosha in the processing of highly structured cytoplasmic RNAs in the context of virus infection.

  2. Three causes of variation in the photochemical reflectance index (PRI) in evergreen conifers.

    PubMed

    Wong, Christopher Y S; Gamon, John A

    2015-04-01

    The photochemical reflectance index (PRI) reflects diurnal xanthophyll cycle activity and is also influenced by seasonally changing carotenoid : Chl pigment ratios. Both changing pigment pools and xanthophyll cycle activity contribute to photoprotection in evergreen conifers exposed to boreal winters, but they operate over different timescales, and their relative contribution to the PRI signal has often been unclear. To clarify these responses and their contribution to the PRI signal, leaf PRI, pigment composition, temperature and irradiance were monitored over 2 yr for two evergreen conifers (Pinus contorta and Pinus ponderosa) in a boreal climate. PRI was affected by three distinct processes operating over different timescales and exhibiting contrasting spectral responses. Over the 2 yr study period, the greatest change in PRI resulted from seasonally changing carotenoid : Chl pigment ratios, followed by a previously unreported shifting leaf albedo during periods of deep cold. Remarkably, the smallest change was attributable to the xanthophyll cycle. To properly distinguish these three effects, interpretation of PRI must consider temporal context, physiological responses to evolving environmental conditions, and spectral response. Consideration of the separate mechanisms affecting PRI over different timescales could greatly improve efforts to monitor changing photosynthetic activity using optical remote sensing. PMID:25408288

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Pri sORF peptides induce selective proteasome-mediated protein processing.

    PubMed

    Zanet, J; Benrabah, E; Li, T; Pélissier-Monier, A; Chanut-Delalande, H; Ronsin, B; Bellen, H J; Payre, F; Plaza, S

    2015-09-18

    A wide variety of RNAs encode small open-reading-frame (smORF/sORF) peptides, but their functions are largely unknown. Here, we show that Drosophila polished-rice (pri) sORF peptides trigger proteasome-mediated protein processing, converting the Shavenbaby (Svb) transcription repressor into a shorter activator. A genome-wide RNA interference screen identifies an E2-E3 ubiquitin-conjugating complex, UbcD6-Ubr3, which targets Svb to the proteasome in a pri-dependent manner. Upon interaction with Ubr3, Pri peptides promote the binding of Ubr3 to Svb. Ubr3 can then ubiquitinate the Svb N terminus, which is degraded by the proteasome. The C-terminal domains protect Svb from complete degradation and ensure appropriate processing. Our data show that Pri peptides control selectivity of Ubr3 binding, which suggests that the family of sORF peptides may contain an extended repertoire of protein regulators.

  8. Escherichia coli PriA protein is essential for inducible and constitutive stable DNA replication.

    PubMed Central

    Masai, H; Asai, T; Kubota, Y; Arai, K; Kogoma, T

    1994-01-01

    Under certain conditions, Escherichia coli cells exhibit either of two altered modes of chromosomal DNA replication. These are inducible stable DNA replication (iSDR), seen in SOS-induced cells, and constitutive stable DNA replication (cSDR), seen in rnhA mutants. Both iSDR and cSDR can continue to occur in the absence of protein synthesis. They are dependent on RecA protein, but do not require DnaA protein or the oriC site. Here we report the requirement for PriA, a protein essential for assembly of the phi X174-type primosome, for both iSDR and cSDR. In priA1(Null)::kan mutant cells, iSDR is not observed after induction by thymine starvation. Replication from one of the origins (oriM1) specific to iSDR is greatly reduced by the priA1::kan mutation. cSDR in rnhA224 mutant cells deficient in RNase HI is also completely abolished by the same priA mutation. In both cases, SDR is restored by introduction of a plasmid carrying a wild-type priA gene. Furthermore, the viability of an rnhA::cat dnaA46 strain is lost at 42 degrees C upon inactivation of the priA gene, indicating the lethal effect of priA inactivation on those cells whose viability depends on cSDR. These results demonstrate that a function of PriA protein is essential for iSDR and cSDR and suggest the involvement of the PriA-dependent phi X174-type primosome in these DnaA/oriC-independent pathways of chromosome replication. Whereas ColE1-type plasmids, known to be independent of DnaA, absolutely require PriA function for replication, DnaA-dependent plasmid replicons such as pSC101, F, R6K, Rts1 and RK2 are able to transform and to be maintained in the priA1::kan strain.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:7525276

  9. The priA gene encoding the primosomal replicative n' protein of Escherichia coli.

    PubMed Central

    Lee, E H; Masai, H; Allen, G C; Kornberg, A

    1990-01-01

    The Escherichia coli gene encoding protein n' has been isolated and named priA for primosomal protein A. Protein n' is absolutely required for the conversion of single-stranded phi X174 DNA to the duplex replicative form in an in vitro-reconstituted system. The gene maps to 88.7 minutes on the chromosome adjacent to the cytR locus. Soluble protein extracts from cells harboring the priA gene on a multicopy plasmid contained 45-fold more n' replication activity than wild-type extracts. Enhanced overproduction of greater than 1000-fold was achieved by replacing the natural Shine-Dalgarno sequence with that of the phage T7 phi 10 gene and placing this priA under the control of the T7 phage promoter and RNA polymerase. The priA sequence reveals a 732-amino acid open reading frame and a nucleotide-binding consensus site consistent with the size and ATPase activity of the purified protein. The gene for protein n has been named priB and the putative gene for protein n", priC. Images PMID:2162050

  10. Effect and evaluation of prying action for top- and seat-angle connections

    NASA Astrophysics Data System (ADS)

    Ahmed, Ali; Hasan, Rafiq

    2015-06-01

    Nonlinear finite element (FE) static analyses of top- and seat-angle connections were performed using ABAQUS standard to investigate the influence of connection parameters and its properties on prying action developed due to the interaction between column flange and top angle's vertical leg. Contact phenomenon between two interfaces with finite sliding and bolt pretension in the initial step of analysis was considered in the FE model. FE analysis results were compared with the experimental ones to examine the applicability of the FE model. Then, the location of plastic hinges in connection assemblages was investigated at the ultimate state of the connection and a parametric study was performed varying connection parameters, material properties of connection assemblages, and magnitude of bolt pretension to visualize their effects on prying force and on the position of prying force on top angle's vertical leg. Current study shows that plastic hinges not only develop at top angle's heel and bolt hole region but also in the bolt shank that differs from some assumptions of power model (Kishi and Chen 1990): (1) top angle thickness and gage distance from angle heel to bolt hole center line have an distinct effect on prying action; and (2) distributed prying force developed near the region of the top edge of tension angle's leg adjacent to column flange can contribute to the failure of the connection. Finally, a mathematical formulation to identify the location of prying force action point is proposed.

  11. The PRiMA-linked Cholinesterase Tetramers Are Assembled from Homodimers

    PubMed Central

    Chen, Vicky P.; Xie, Heidi Q.; Chan, Wallace K. B.; Leung, K. Wing; Chan, Gallant K. L.; Choi, Roy C. Y.; Bon, Suzanne; Massoulié, Jean; Tsim, Karl W. K.

    2010-01-01

    Acetylcholinesterase (AChE) is anchored onto cell membranes by the transmembrane protein PRiMA (proline-rich membrane anchor) as a tetrameric globular form that is prominently expressed in vertebrate brain. In parallel, the PRiMA-linked tetrameric butyrylcholinesterase (BChE) is also found in the brain. A single type of AChE-BChE hybrid tetramer was formed in cell cultures by co-transfection of cDNAs encoding AChET and BChET with proline-rich attachment domain-containing proteins, PRiMA I, PRiMA II, or a fragment of ColQ having a C-terminal GPI addition signal (QN-GPI). Using AChE and BChE mutants, we showed that AChE-BChE hybrids linked with PRiMA or QN-GPI always consist of AChET and BChET homodimers. The dimer formation of AChET and BChET depends on the catalytic domains, and the assembly of tetramers with a proline-rich attachment domain-containing protein requires the presence of C-terminal “t-peptides” in cholinesterase subunits. Our results indicate that PRiMA- or ColQ-linked cholinesterase tetramers are assembled from AChET or BChET homodimers. Moreover, the PRiMA-linked AChE-BChE hybrids occur naturally in chicken brain, and their expression increases during development, suggesting that they might play a role in cholinergic neurotransmission. PMID:20566626

  12. 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.

  13. 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

  14. 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

  15. Requirement for RecFOR-mediated recombination in priA mutant.

    PubMed

    Grompone, Gianfranco; Sanchez, Nicolas; Dusko Ehrlich, S; Michel, Bénédicte

    2004-04-01

    Restart of arrested replication forks is an important process and PriA, the main Escherichia coli replication restart protein, is essential for viability under any condition that increases the frequency of fork arrest. In priA mutant, replication forks are arrested by spontaneously occurring roadblocks and blocked replication forks persist as a result of the defect in replication restart. In the present work, we analysed how recombination proteins contribute to the viability of the priA mutant. RecFOR-mediated homologous recombination occurs in a large fraction of priA mutant cells, indicating a frequent formation of DNA single strand gaps and their recombinational repair. This high level of homologous recombination renders the proteins that resolve Holliday junctions recombination intermediates essential for viability. When homologous recombination is blocked at early steps by recFOR or recA inactivation, exonuclease V-mediated DNA degradation is required for full viability of priA mutants, indicating that unrepaired gaps are broken and that DNA degradation of the broken DNA allows the formation of viable cells. Models for the formation of single strand DNA gaps consequently to a replication restart defect and for gap processing are proposed. PMID:15066040

  16. PRI-Modeler: extracting RNA structural elements from PDB files of protein-RNA complexes.

    PubMed

    Han, Kyungsook; Nepal, Chirag

    2007-05-01

    A complete understanding of protein and RNA structures and their interactions is important for determining the binding sites in protein-RNA complexes. Computational approaches exist for identifying secondary structural elements in proteins from atomic coordinates. However, similar methods have not been developed for RNA, due in part to the very limited structural data so far available. We have developed a set of algorithms for extracting and visualizing secondary and tertiary structures of RNA and for analyzing protein-RNA complexes. These algorithms have been implemented in a web-based program called PRI-Modeler (protein-RNA interaction modeler). Given one or more protein data bank files of protein-RNA complexes, PRI-Modeler analyzes the conformation of the RNA, calculates the hydrogen bond (H bond) and van der Waals interactions between amino acids and nucleotides, extracts secondary and tertiary RNA structure elements, and identifies the patterns of interactions between the proteins and RNAs. This paper presents PRI-Modeler and its application to the hydrogen bond and van der Waals interactions in the most representative set of protein-RNA complexes. The analysis reveals several interesting interaction patterns at various levels. The information provided by PRI-Modeler should prove useful for determining the binding sites in protein-RNA complexes. PRI-Modeler is accessible at http://wilab.inha.ac.kr/primodeler/, and supplementary materials are available in the analysis results section at http://wilab.inha.ac.kr/primodeler/.

  17. 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.

  18. Tertiary structure mapping of the pri-miRNA miR-17~92.

    PubMed

    Chaulk, Steven G; Fahlman, Richard P

    2014-01-01

    The understanding of RNA in regulating gene expression has exploded over the past 15 years. MicroRNAs (miRNAs) have vastly expanded the role of RNA in gene regulation beyond spliceosomal, ribosomal, and messenger RNAs. Approximately one half of miRNAs are polycistronic, where two or more miRNAs are encoded on a single pri-miRNA transcript, termed a miRNA cluster. The six miRNAs of the miR-17~92 cluster are contained within a ~800 nucleotide region within intron 3 of the cl13orf25 ~7 kb pri-miRNA transcript. We recently reported on the tertiary structured domain of miR-17~92 and its role in modulating miRNA biogenesis. The key finding was that the cluster structure explained the differential processing of the miRNA hairpins by Drosha. This work demonstrated the need to consider pri-miRNA tertiary structure in miRNA biogenesis. Since biochemical structure probing is typically performed on relatively short RNAs (≤200 nucleotides), we had to adapt these methodologies for application on large RNAs (~800 nucleotide miR-17~92 pri-miRNA). We present here our adaptation of a protection footprinting method using ribonucleases to probe the structure of the ~800 nucleotide miR-17~92 pri-miRNA. We outline the technical difficulties involved in probing large RNAs and data visualization using denaturing polyacrylamide gel electrophoresis and how we adapted the existing approaches to probe large RNAs. The methodology outlined here is generally applicable to large RNAs including long noncoding RNAs (lncRNA).

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

    PubMed

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

    2012-12-01

    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.

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

    PubMed Central

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

    2012-01-01

    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. PMID:23151633

  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. 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.

  3. Essential role of the iron-sulfur cluster binding domain of the primase regulatory subunit Pri2 in DNA replication initiation.

    PubMed

    Liu, Lili; Huang, Mingxia

    2015-03-01

    DNA primase catalyzes de novo synthesis of a short RNA primer that is further extended by replicative DNA polymerases during initiation of DNA replication. The eukaryotic primase is a heterodimeric enzyme comprising a catalytic subunit Pri1 and a regulatory subunit Pri2. Pri2 is responsible for facilitating optimal RNA primer synthesis by Pri1 and mediating interaction between Pri1 and DNA polymerase α for transition from RNA synthesis to DNA elongation. All eukaryotic Pri2 proteins contain a conserved C-terminal iron-sulfur (Fe-S) cluster-binding domain that is critical for primase catalytic activity in vitro. Here we show that mutations at conserved cysteine ligands for the Pri2 Fe-S cluster markedly decrease the protein stability, thereby causing S phase arrest at the restrictive temperature. Furthermore, Pri2 cysteine mutants are defective in loading of the entire DNA pol α-primase complex onto early replication origins resulting in defective initiation. Importantly, assembly of the Fe-S cluster in Pri2 is impaired not only by mutations at the conserved cysteine ligands but also by increased oxidative stress in the sod1Δ mutant lacking the Cu/Zn superoxide dismutase. Together these findings highlight the critical role of Pri2's Fe-S cluster domain in replication initiation in vivo and suggest a molecular basis for how DNA replication can be influenced by changes in cellular redox state.

  4. mirTarPri: Improved Prioritization of MicroRNA Targets through Incorporation of Functional Genomics Data

    PubMed Central

    Li, Ronghong; Ye, Jingrun; Zhao, Zuxianglan; Li, Yan; Huang, Teng; Li, Xia

    2013-01-01

    MicroRNAs (miRNAs) are a class of small (19–25 nt) non-coding RNAs. This important class of gene regulator downregulates gene expression through sequence-specific binding to the 3′untranslated regions (3′UTRs) of target mRNAs. Several computational target prediction approaches have been developed for predicting miRNA targets. However, the predicted target lists often have high false positive rates. To construct a workable target list for subsequent experimental studies, we need novel approaches to properly rank the candidate targets from traditional methods. We performed a systematic analysis of experimentally validated miRNA targets using functional genomics data, and found significant functional associations between genes that were targeted by the same miRNA. Based on this finding, we developed a miRNA target prioritization method named mirTarPri to rank the predicted target lists from commonly used target prediction methods. Leave-one-out cross validation has proved to be successful in identifying known targets, achieving an AUC score up to 0. 84. Validation in high-throughput data proved that mirTarPri was an unbiased method. Applying mirTarPri to prioritize results of six commonly used target prediction methods allowed us to find more positive targets at the top of the prioritized candidate list. In comparison with other methods, mirTarPri had an outstanding performance in gold standard and CLIP data. mirTarPri was a valuable method to improve the efficacy of current miRNA target prediction methods. We have also developed a web-based server for implementing mirTarPri method, which is freely accessible at http://bioinfo.hrbmu.edu.cn/mirTarPri. PMID:23326485

  5. Prion-like nanofibrils of small molecules (PriSM): A new frontier at the intersection of supramolecular chemistry and cell biology.

    PubMed

    Zhou, Jie; Du, Xuewen; Xu, Bing

    2015-01-01

    Formed by non-covalent interactions and not defined at genetic level, the assemblies of small molecules in biology are complicated and less explored. A common morphology of the supramolecular assemblies of small molecules is nanofibrils, which coincidentally resembles the nanofibrils formed by proteins such as prions. So these supramolecular assemblies are termed as prion-like nanofibrils of small molecules (PriSM). Emerging evidence from several unrelated fields over the past decade implies the significance of PriSM in biology and medicine. This perspective aims to highlight some recent advances of the research on PriSM. This paper starts with description of the intriguing similarities between PriSM and prions, discusses the paradoxical features of PriSM, introduces the methods for elucidating the biological functions of PriSM, illustrates several examples of beneficial aspects of PriSM, and finishes with the promises and current challenges in the research of PriSM. We anticipate that the research of PriSM will contribute to the fundamental understanding at the intersection of supramolecular chemistry and cell biology and ultimately lead to a new paradigm of molecular (or supramolecular) therapeutics for biomedicine.

  6. Prion-like nanofibrils of small molecules (PriSM): A new frontier at the intersection of supramolecular chemistry and cell biology

    PubMed Central

    Zhou, Jie; Du, Xuewen; Xu, Bing

    2015-01-01

    Abstract Formed by non-covalent interactions and not defined at genetic level, the assemblies of small molecules in biology are complicated and less explored. A common morphology of the supramolecular assemblies of small molecules is nanofibrils, which coincidentally resembles the nanofibrils formed by proteins such as prions. So these supramolecular assemblies are termed as prion-like nanofibrils of small molecules (PriSM). Emerging evidence from several unrelated fields over the past decade implies the significance of PriSM in biology and medicine. This perspective aims to highlight some recent advances of the research on PriSM. This paper starts with description of the intriguing similarities between PriSM and prions, discusses the paradoxical features of PriSM, introduces the methods for elucidating the biological functions of PriSM, illustrates several examples of beneficial aspects of PriSM, and finishes with the promises and current challenges in the research of PriSM. We anticipate that the research of PriSM will contribute to the fundamental understanding at the intersection of supramolecular chemistry and cell biology and ultimately lead to a new paradigm of molecular (or supramolecular) therapeutics for biomedicine. PMID:25738892

  7. 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.

  8. Structural basis of the 3'-end recognition of a leading strand in stalled replication forks by PriA.

    PubMed

    Sasaki, Kaori; Ose, Toyoyuki; Okamoto, Naoaki; Maenaka, Katsumi; Tanaka, Taku; Masai, Hisao; Saito, Mihoko; Shirai, Tsuyoshi; Kohda, Daisuke

    2007-05-16

    In eubacteria, PriA helicase detects the stalled DNA replication forks. This critical role of PriA is ascribed to its ability to bind to the 3' end of a nascent leading DNA strand in the stalled replication forks. The crystal structures in complexes with oligonucleotides and the combination of fluorescence correlation spectroscopy and mutagenesis reveal that the N-terminal domain of PriA possesses a binding pocket for the 3'-terminal nucleotide residue of DNA. The interaction with the deoxyribose 3'-OH is essential for the 3'-terminal recognition. In contrast, the direct interaction with 3'-end nucleobase is unexpected, considering the same affinity for oligonucleotides carrying the four bases at the 3' end. Thus, the N-terminal domain of PriA recognizes the 3'-end base in a base-non-selective manner, in addition to the deoxyribose and 5'-side phosphodiester group, of the 3'-terminal nucleotide to acquire both sufficient affinity and non-selectivity to find all of the stalled replication forks generated during DNA duplication. This unique feature is prerequisite for the proper positioning of the helicase domain of PriA on the unreplicated double-stranded DNA. PMID:17464287

  9. 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

  10. 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

  11. 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

  12. PriFi: using a multiple alignment of related sequences to find primers for amplification of homologs.

    PubMed

    Fredslund, Jakob; Schauser, Leif; Madsen, Lene H; Sandal, Niels; Stougaard, Jens

    2005-07-01

    Using a comparative approach, the web program PriFi (http://cgi-www.daimi.au.dk/cgi-chili/PriFi/main) designs pairs of primers useful for PCR amplification of genomic DNA in species where prior sequence information is not available. The program works with an alignment of DNA sequences from phylogenetically related species and outputs a list of possibly degenerate primer pairs fulfilling a number of criteria, such that the primers have a maximal probability of amplifying orthologous sequences in other phylogenetically related species. Operating on a genome-wide scale, PriFi automates the first steps of a procedure for developing general markers serving as common anchor loci across species. To accommodate users with special preferences, configuration settings and criteria can be customized.

  13. 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

  14. The Photochemical Reflectance Index (PRI) 20 years later: what have we learned?

    NASA Astrophysics Data System (ADS)

    Gamon, J. A.

    2012-12-01

    The Photochemical Reflectance Index (PRI) was originally derived as a measure of diurnal xanthophyll cycle activity and photosynthetic light-use efficiency (LUE). Based on experimental studies of plant canopies in the early 1990's, PRI is derived from reflectance at two wavelengths: 531 nm (the xanthophyll cycle wavelength) and a reference wavelength (unaffected by the xanthophyll cycle). Like any index approach, it has key advantages and disadvantages. Advantages include data reduction and a demonstrated correlation with biochemical and physiological processes tied to photosynthetic light regulation. Disadvantages include sensitivity to a number of confounding factors that include pigment pool sizes, vegetation canopy structure, and sun and view angle effects. Despite these challenges, many studies have shown some promise in using this index for airborne or satellite assessment of photosynthetic activity. This presentation will review key challenges in using this index for global assessment of photosynthetic activity, and will propose avenues for further research that might strengthen our understanding of the dynamic 531 nm reflectance signal. Alternative and complementary approaches to this index will also be briefly discussed.

  15. 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.

  16. Explaining the variability of the photochemical reflectance index (PRI) at the canopy-scale: Disentangling the effects of phenological and physiological changes.

    PubMed

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

    2015-10-01

    Assessing photosynthesis rates at the ecosystem scale and over large regions is important for tracking the global carbon cycle and remote sensing has provided new and useful approaches for performing this assessment. The photochemical reflectance index (PRI) is a good estimator of short-term light-use efficiency (LUE) at the leaf scale; however, confounding factors appear at larger temporal and spatial scales. In this study, canopy-scale PRI variability was investigated for three species (Fagus sylvatica L., Quercus robur L. and Pinus sylvestris L.) growing under contrasting soil moisture conditions. Throughout the growing season, no significant differences in chlorophyll content and in violaxanthin, antheraxanthin and zeaxanthin were found between species or treatments. The daily PRI vs PAR (photosynthetically active radiation) relationships were determined using continuous measurements obtained at high frequency throughout the entire growing season, from early spring budburst to later autumn senescence, and were used to deconvolute the physiological PRI variability related to LUE variations due to phenological variability and related to temporal changes in the biochemical and structural canopy attributes. The PRI vs PAR relationship is used to show that the canopy-scale PRI measured at low radiation depends on the chlorophyll content of the canopy. The range of PRI variations at an intra-daily scale and the dynamics of the xanthophyll pool do not vary between days, which suggests that the PRI responds to a xanthophyll ratio. The PAR values at PRI saturation are mainly related to the canopy chlorophyll content during budburst and senescence and to the soil moisture content when the chlorophyll content is no longer a limiting factor. This parameter is significantly lower in the oak species that experience less stress from variations in soil moisture and is species dependant. These results provide new insights regarding the analysis and the meaning of PRI

  17. 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

  18. PriA mediates DNA replication pathway choice at recombination intermediates.

    PubMed

    Xu, Liewei; Marians, Kenneth J

    2003-03-01

    We report the reconstitution of the initial steps of the double-strand break-repair pathway where joint molecule formation between a duplex DNA fragment and a circular template by the combined action of RecA, RecBCD, and the single-stranded DNA binding protein provides the substrate for replication fork formation by the restart primosome and the DNA polymerase III holoenzyme. We show that PriA dictates the pathway of replication from the recombination intermediate by inhibiting a nonspecific, strand displacement DNA synthesis reaction and favoring the formation of a bona fide replication fork. Furthermore, we find that RecO and RecR significantly stimulate this recombination-directed DNA replication reaction, and that this stimulation is modulated by the presence of RecF, suggesting that the latter protein may also act as a regulator of the pathway of resolution of the recombination intermediate. PMID:12667462

  19. 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

  20. Role of pri-miRNA tertiary structure in miR-17~92 miRNA biogenesis.

    PubMed

    Chaulk, Steven G; Thede, Gina L; Kent, Oliver A; Xu, Zhizhong; Gesner, Emily M; Veldhoen, Richard A; Khanna, Suneil K; Goping, Ing Swie; MacMillan, Andrew M; Mendell, Joshua T; Young, Howard S; Fahlman, Richard P; Glover, J N Mark

    2011-01-01

    MicroRNAs (miRNAs) regulate gene expression in a variety of biological pathways such as development and tumourigenesis. miRNAs are initially expressed as long primary transcripts (pri-miRNAs) that undergo sequential processing by Drosha and then Dicer to yield mature miRNAs. miR-17~92 is a miRNA cluster that encodes 6 miRNAs and while it is essential for development it also has reported oncogenic activity. To date, the role of RNA structure in miRNA biogenesis has only been considered in terms of the secondary structural elements required for processing of pri-miRNAs by Drosha. Here we report that the miR-17~92 cluster has a compact globular tertiary structure where miRNAs internalized within the core of the folded structure are processed less efficiently than miRNAs on the surface of the structure. Increased miR-92 expression resulting from disruption of the compact miR-17~92 structure results in increased repression of integrin α5 mRNA, a known target of miR-92a. In summary, we describe the first example of pri-miRNA structure modulating differential expression of constituent miRNAs.

  1. 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

  2. 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

  3. Overlapping functions for recF and priA in cell viability and UV-inducible SOS expression are distinguished by dnaC809 in Escherichia coli K-12.

    PubMed

    Sandler, S J

    1996-02-01

    The recF and priA genes have roles in DNA repair and homologous recombination. Mutations in these genes also cause decreases in cell viability and alterations in UV-inducible sulAp-lacZ (SOS) expression. To find out if the two genes are in the same or different pathways for viability and SOS expression, the phenotypes of the double mutant strains were studied. The recF priA double mutant showed a lower viability and SOS expression level than either of the single mutants. In the case of cell viability, recF missense mutations decreased viability of a priA2::kan strain two to five-fold whereas recF null priA2::kan double mutants were not viable at all. dnaC809, a mutation that suppresses the UV-sensitive (UVs and Rec- phenotypes of priA2::kan, restored cell viability, but not UV-inducible SOS expression, to a priA recF strain. Since recF is epistatic with recO and recR (recOR) for UV resistance, recOR mutations were also tested with priA2::kan. No overlap was found between recOR and priA for viability and SOS expression. It is concluded that priA and recF have two different overlapping functions in viability and SOS expression that are distinguishable by the effects of dnaC809. The role of recF in a priA2::kan strain in cell viability is a new function for recF and unlike recF's other roles in DNA repair and recombination, is independent of recOR. A new role for priA in UV-inducible SOS expression in a recF mutant is also defined. PMID:8820655

  4. 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

  5. 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

  6. 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

  7. The Use of Fetal Bovine Dermal Scaffold (PriMatrix) in the Management of Full-Thickness Hand Burns

    PubMed Central

    Karcich, Jenika; Granick, Mark S.; Marano, Michael A.

    2014-01-01

    Objective: Management of full-thickness burn wounds represents a challenge when reconstructive options are not applicable. Fetal bovine dermal matrix is a bioactive collagen scaffold that assimilates into wounds and stimulates vascularization and dermal regeneration. Methods: We present the use of fetal bovine dermal scaffold PriMatrix in the treatment of a patient who sustained scald-immersion full-thickness burns of her bilateral hands that failed conventional wound therapy. Results: A 71-year-old woman with advanced Parkinson's disease sustained self-induced 5% mixed second- and third-degree scald-immersion burns of her bilateral hands and fingers. The patient underwent extensive debridement that resulted in partially avascular wounds measuring 66 cm2 and 72 cm2 with exposed extensor tendons and no evidence of bleeding. Meshed homograft was applied, but her hands remained partly avascular. PriMatrix fetal bovine dermal scaffold was applied to provide tissue remodeling over the bones, which allowed successful skin grafting and complete wound healing. Conclusions: Our experience shows fetal bovine dermal scaffold to be an effective method in management of complicated burn wounds in selected cases. Further studies need to be implemented to confer this conclusion. PMID:25328569

  8. Modulation of recombination and DNA repair by the RecG and PriA helicases of Escherichia coli K-12.

    PubMed Central

    Al-Deib, A A; Mahdi, A A; Lloyd, R G

    1996-01-01

    The RecG protein of Escherichia coli is a structure-specific DNA helicase that targets strand exchange intermediates in genetic recombination and drives their branch migration along the DNA. Strains carrying null mutations in recG show reduced recombination and DNA repair. Suppressors of this phenotype, called srgA, were located close to metB and shown to be alleles of priA. Suppression depends on the RecA, RecBCD, RecF, RuvAB, and RuvC recombination proteins. Nine srgA mutations were sequenced and shown to specify mutant PriA proteins with single amino acid substitutions located in or close to one of the conserved helicase motifs. The mutant proteins retain the ability to catalyze primosome assembly, as judged by the viability of recG srgA and srgA strains and their ability to support replication of plasmids based on the ColE1 replicon. Multicopy priA+ plasmids increase substantially the recombination- and repair-deficient phenotype of recG strains and confer similar phenotypes on recG srgA double mutants but not on ruvAB or wild-type strains. The multicopy effect is eliminated by K230R, C446G, and C477G substitutions in PriA. It is concluded that the 3'-5' DNA helicase/translocase activity of PriA inhibits recombination and that this effect is normally countered by RecG. PMID:8955297

  9. Replication restart in UV-irradiated Escherichia coli involving pols II, III, V, PriA, RecA and RecFOR proteins.

    PubMed

    Rangarajan, Savithri; Woodgate, Roger; Goodman, Myron F

    2002-02-01

    In Escherichia coli, UV-irradiated cells resume DNA synthesis after a transient inhibition by a process called replication restart. To elucidate the role of several key proteins involved in this process, we have analysed the time dependence of replication restart in strains carrying a combination of mutations in lexA, recA, polB (pol II), umuDC (pol V), priA, dnaC, recF, recO or recR. We find that both pol II and the origin-independent primosome-assembling function of PriA are essential for the immediate recovery of DNA synthesis after UV irradiation. In their absence, translesion replication or 'replication readthrough' occurs approximately 50 min after UV and is pol V-dependent. In a wild-type, lexA+ background, mutations in recF, recO or recR block both pathways. Similar results were obtained with a lexA(Def) recF strain. However, lexA(Def) recO or lexA(Def) recR strains, although unable to facilitate PriA-pol II-dependent restart, were able to perform pol V-dependent readthrough. The defects in restart attributed to mutations in recF, recO or recR were suppressed in a recA730 lexA(Def) strain expressing constitutively activated RecA (RecA*). Our data suggest that in a wild-type background, RecF, O and R are important for the induction of the SOS response and the formation of RecA*-dependent recombination intermediates necessary for PriA/Pol II-dependent replication restart. In con-trast, only RecF is required for the activation of RecA that leads to the formation of pol V (UmuD'2C) and facilitates replication readthrough. PMID:11929519

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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

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

    DOE PAGES

    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.

  16. Multilevel hierarchy of phase separation processes in La5/8-yPryCa3/8MnO3

    NASA Astrophysics Data System (ADS)

    García-Muñoz, J. L.; Collado, A.; Aranda, M. A. G.; Ritter, C.

    2011-07-01

    We investigate two successive hierarchized phase segregations in La5/8-yPryCa3/8MnO3, which generate ferromagnetic metallic volumes (V1FM and V2FM) having different physical origins, stabilities, and parent electronic phases. The singular percolative transition around TC2 ≈ 100 K is due to a second electronic phase separation (PS), which is specific to the charge-order insulating regions segregated at the first PS process. These findings shed new light on the metastability, atypical dynamics, the nonvolatile magnetoresistance, or the supercooling glass transition in this complex magnetic system.

  17. 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

  18. Quantitative analysis of histidine decarboxylase gene (hdcA) transcription and histamine production by Streptococcus thermophilus PRI60 under conditions relevant to cheese making.

    PubMed

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

    2011-04-01

    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.

  19. 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

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

    PubMed

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

    2003-02-01

    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

  1. 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

  2. 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

  3. 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

  4. Temperature dependence of δ7Li, δ44Ca and Li/Ca during growth of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Marriott, Caedmon S.; Henderson, Gideon M.; Belshaw, Nick S.; Tudhope, Alexander W.

    2004-05-01

    Lithium and calcium isotope ratios, together with the Li/Ca element ratio, have been measured in calcites precipitated inorganically at temperatures ranging from 5 to 30 °C, and on seasonal growth bands from a coral. These measurements indicate the potential uses of these three environmental proxies. Carbonate Li isotopes are lighter than the solution from which they grow, probably due to equilibrium fractionation. This fractionation is not significantly influenced by temperature and, because Li is not involved in any known biological process, this suggests that carbonates will provide a recorder for the past Li-isotope composition of natural waters and hence for past weathering conditions. As has been observed previously for inorganic aragonite, the Ca-isotopes in inorganic calcite are lighter than the growth solution, and are only weakly dependent on temperature. This confirms that the temperature dependence observed in some species of foraminifera [Geochem. Geophys. Geosyst. 1 (2001)] reflects additional isotope fractionation due to biological processes during mineralization. Ca isotopes may therefore provide a powerful tool with which to investigate the processes of biomineralization. Finally, Li/Ca ratios in inorganic and biogenic carbonates increase as temperatures decrease with a sensitivity of ≈4% per °C. This temperature dependence of Li/Ca may prove useful to assess past temperatures in cold environments such as the deep ocean.

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

    PubMed Central

    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

  6. 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

  7. Two common SNPs in pri-miR-125a alter the mature miRNA expression and associate with recurrent pregnancy loss in a Han-Chinese population.

    PubMed

    Hu, Yi; Liu, Chun-Mei; Qi, Lu; He, Tian-Zhu; Shi-Guo, Liu; Hao, Chan-Juan; Cui, Yi; Zhang, Ning; Xia, Hong-Fei; Ma, Xu

    2011-01-01

    Although there are plenty of evidence that single-nucleotide polymorphisms (SNPs) that fall within coding sequences of genes are involved in recurrent pregnancy loss (RPL), it is still unknown whether the polymorphisms in microRNAs (miRNAs) are related with RPL. In this study, we established this kind of association by confirming significant differences in genotype distribution of rs41275794 (P= 0.0005) and rs12976445 (P= 0.001) within the pri-miR-125a in 217 Han Chinese patients of RPL compared with 431 controls. Based on this observation, two-locus haplotypes were constructed and the A-T haplotype was found to be associated with an increased risk of RPL (OR=2.84, 95%C.I. 1.98-4.07, P=0.0000000057). Further analysis showed that the levels of pre- and mature- miR-125a were down-regulated in the cells transfected with the A-T haplotype, which was consistent with in vivo detection that the level of mature miR-125a was lower in 30 pregnant women with A-T haplotype than that with G-C haplotype. During in vitro RNA processing assays, we found a similar decrease in the amount of pre-miR-125a and decline in binding capacity of nuclear factors to pri-miR-125a with A-T haplotype. More importantly, the reduction in miR-125a, as a consequence of A-T haplotype, further led to less efficient inhibition of target genes, LIFR and ERBB2, which play important roles in the embryo implantation and decidualization. Thus, our data collectively suggest that two common polymorphisms in pre-miR-125a might contribute to the genetic predisposition to RPL by disrupting the production of miR-125a, which consequently interfered in the expression and function of target genes of miR-125a.

  8. vsiRNAs derived from the miRNA-generating sites of pri-tae-miR159a based on the BSMV system play positive roles in the wheat response to Puccinia striiformis f. sp. tritici through the regulation of taMyb3 expression.

    PubMed

    Feng, Hao; Zhang, Qiong; Li, Huayi; Wang, Xiaojie; Wang, Xiaodong; Duan, Xiaoyuan; Wang, Bing; Kang, Zhensheng

    2013-07-01

    Plants live in a complex environment, exposed to stresses, such as unsuitable climates, pests and pathogenic microorganisms. Pathogens are one of the most serious factors that threaten plant growth. Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most destructive diseases worldwide. Virus-induced gene silencing (VIGS) is a popular tool for the functional analysis of wheat genes, generating abundant small RNAs (sRNAs). sRNAs are key components in gene regulatory networks, silencing corresponding genes at the post-transcriptional level. In this study, we transduced pri-tae-miR159a into plant tissues using the barley stripe mosaic virus (BSMV) system, and demonstrated that vsiRNAs were generated from the same miRNAs generating sites of pri-tae-miR159a, with the function of Dicer RNase III-like classes of endonucleases (DCL4). In addition, the accumulation of vsiRNAs in wheat leaves challenged with Pst Chinese yellow rust 23 (CYR23), resulted in a resistant phenotype, and in the compatible interaction, the sporation of Pst was limited. Whereas, infection with a control construct had no effect on the resistance or susceptibility. The results of the histological observation also supported these phenotype changes. Interestingly, vsiRNAs were also involved in the interactions between wheat and Pst through the tae-miR159-mediated regulation of taMyb3 expression. Moreover, these results also supported the speculation that vsiRNAs were generated from the same sites of pri-tae-miR159a. These studies indicated that vsiRNAs from miRNAs generating sites of pri-tae-miR159a based on the BSMV system play positive roles in the wheat response to Pst through the regulation of taMyb3 expression.

  9. 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.

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

    PubMed Central

    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

  11. 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.

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

    DOE PAGES

    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

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    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), 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.

  14. 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.

  15. 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.

  16. 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.…

  17. 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…

  18. 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.

  19. 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

  20. 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

  1. 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…

  2. Sensor4PRI: a sensor platform for the protection of railway infrastructures.

    PubMed

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

    2015-02-27

    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.

  3. 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...

  4. 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…

  5. 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

  6. 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

    ... are largely irreversible and that can be expected to result in a long-term or permanent reduction in.... Erosion by water and wind and the associated changes that result in permanent or long-term reductions in...— (i) Improving efficiency in use; (ii) Reducing loss and waste; (iii) Increasing the recycling...

  7. 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...

  8. 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

  9. 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,…

  10. Enhanced production of single copy backbone-free transgenic plants in multiple crop species using binary vectors with a pRi replication origin in Agrobacterium tumefaciens.

    PubMed

    Ye, Xudong; Williams, Edward J; Shen, Junjiang; Johnson, Susan; Lowe, Brenda; Radke, Sharon; Strickland, Steve; Esser, James A; Petersen, Michael W; Gilbertson, Larry A

    2011-08-01

    Single transgene copy, vector backbone-free transgenic crop plants are highly desired for functional genomics and many biotechnological applications. We demonstrate that binary vectors that use a replication origin derived from the Ri plasmid of Agrobacterium rhizogenes (oriRi) increase the frequency of single copy, backbone-free transgenic plants in Agrobacterium tumefaciens mediated transformation of soybean, canola, and corn, compared to RK2-derived binary vectors (RK2 oriV). In large scale soybean transformation experiments, the frequency of single copy, backbone-free transgenic plants was nearly doubled in two versions of the oriRi vectors compared to the RK2 oriV control vector. In canola transformation experiments, the oriRi vector produced more single copy, backbone-free transgenic plants than did the RK2 oriV vector. In corn transformation experiments, the frequency of single copy backbone-free transgenic plants was also significantly increased when using the oriRi vector, although the transformation frequency dropped. These results, derived from transformation experiments using three crops, indicate the advantage of oriRi vectors over RK2 oriV binary vectors for the production of single copy, backbone-free transgenic plants using Agrobacterium-mediated transformation.

  11. SNP-SNP interactions of three new pri-miRNAs with the target gene PGC and multidimensional analysis of H. pylori in the gastric cancer/atrophic gastritis risk in a Chinese population

    PubMed Central

    Xu, Qian; Wu, Ye-feng; Li, Ying; He, Cai-yun; Sun, Li-ping; Liu, Jing-wei; Yuan, Yuan

    2016-01-01

    Gastric cancer (GC) is a multistep complex disease involving multiple genes, and gene–gene interactions have a greater effect than a single gene in determining cancer susceptibility. This study aimed to explore the interaction of the let-7e rs8111742, miR-365b rs121224, and miR-4795 rs1002765 single nucleotide polymorphisms (SNPs) with SNPs of the predicted target gene PGC and Helicobacter pylori status in GC and atrophic gastritis (AG) risk. Three miRNA SNPs and seven PGC SNPs were detected in 2448 cases using the Sequenom MassArray platform. Two pairwise combinations of miRNA and PGC SNPs were associated with increased AG risk (let-7e rs8111742 – PGC rs6458238 and miR-4795 rs1002765 – PGC rs9471643). Singly, miR-365b rs121224 and PGC rs6912200 had no effect individually but in combination they demonstrated an epistatic interaction associated with AG risk. Similarly, let-7e rs8111742 and miR-4795 rs1002765 SNPs interacted with H. pylori infection to increase GC risk (rs8111742: Pinteraction = 0.024; rs1002765: Pinteraction = 0.031, respectively). A three-dimensional interaction analysis found miR-4795 rs1002765, PGC rs9471643, and H. pylori infection positively interacted to increase AG risk (Pinteraction = 0.027). Also, let-7e rs8111742, PGC rs6458238, and H. pylori infection positively interacted to increase GC risk (Pinteraction = 0.036). Furthermore, both of these three-dimensional interactions had a dosage–effect correspondence (Ptrend < 0.001) and were verified by MDR. In conclusion, the miRNAs SNPs (let-7e rs8111742 and miR-4795 rs1002765) might have more superior efficiency when combined with PGC SNPs and/or H. pylori for GC or AG risk than a single SNP on its own. PMID:26988755

  12. 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

  13. Correlation of 48Ca, 50Ti, and 138La Heterogeneity in the Allende Refractory Inclusions

    NASA Astrophysics Data System (ADS)

    Chen, Hsin-Wei; Lee, Typhoon; Lee, Der-Chuen; Chen, Jiang-Chang

    2015-06-01

    Precise determinations of 48Ca anomalies in Allende calcium-aluminum-rich inclusions (CAIs) are reported in this work. There are endemic positive 48Ca/44Ca anomalies in all analyzed CAIs after normalization to 42Ca/44Ca, and it is clearly shown that there is no simple correlation between 48Ca/44Ca and 50Ti/48Ti anomalies, in agreement with Jungck et al. Compared to the 48Ca/44Ca versus 50Ti/48Ti correlation line defined by differentiated meteorites, reported by Chen et al., the CAIs plot to elevated 50Ti/48Ti. Assuming the 48Ca/44Ca anomalies of both CAIs and differentiated meteorites came from the same source, excess 50Ti anomalies in CAIs can be calculated by subtracting the part associated with 48Ca/44Ca. These excesses show a linear correlation with 138La anomalies, a neutrino-process nuclide. According to current stellar nucleosynthetic models, we therefore suggest that the solar system 48Ca, 50Ti, and 138La isotopic variations are made of mixtures between grains condensed from ejecta of neutron-rich accretion-induced SNe Ia and the O/Ne-O/C zone of core-collapse SNe II.

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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.

  20. Skip the Alignment: Degenerate, Multiplex Primer and Probe Design Using K-mer Matching Instead of Alignments

    PubMed Central

    Hysom, David A.; Naraghi-Arani, Pejman; Elsheikh, Maher; Carrillo, A. Celena; Williams, Peter L.; Gardner, Shea N.

    2012-01-01

    PriMux is a new software package for selecting multiplex compatible, degenerate primers and probes to detect diverse targets such as viruses. It requires no multiple sequence alignment, instead applying k-mer algorithms, hence it scales well for large target sets and saves user effort from curating sequences into alignable groups. PriMux has the capability to predict degenerate primers as well as probes suitable for TaqMan or other primer/probe triplet assay formats, or simply probes for microarray or other single-oligo assay formats. PriMux employs suffix array methods for efficient calculations on oligos 10-∼100 nt in length. TaqMan® primers and probes for each segment of Rift Valley fever virus were designed using PriMux, and lab testing comparing signatures designed using PriMux versus those designed using traditional methods demonstrated equivalent or better sensitivity for the PriMux-designed signatures compared to traditional signatures. In addition, we used PriMux to design TaqMan® primers and probes for unalignable or poorly alignable groups of targets: that is, all segments of Rift Valley fever virus analyzed as a single target set of 198 sequences, or all 2863 Dengue virus genomes for all four serotypes available at the time of our analysis. The PriMux software is available as open source from http://sourceforge.net/projects/PriMux. PMID:22485178

  1. The DGCR8 RNA-binding heme domain recognizes primary microRNAs by clamping the hairpin

    PubMed Central

    Quick-Cleveland, Jen; Jacob, Jose P.; Weitz, Sara H.; Shoffner, Grant; Senturia, Rachel; Guo, Feng

    2014-01-01

    SUMMARY Canonical primary microRNA transcripts (pri-miRNAs) are characterized by a ~30-bp hairpin flanked by single-stranded regions. These pri-miRNAs are recognized and cleaved by the Microprocessor complex consisting of the Drosha nuclease and its obligate RNA-binding partner DGCR8. It is not well understood how the Microprocessor specifically recognizes pri-miRNA substrates. Here we show that in addition to the well-known double-stranded RNA-binding domains, DGCR8 uses a dimeric heme-binding domain to directly contact pri-miRNAs. This RNA-binding heme domain (Rhed) directs two DGCR8 dimers to bind each pri-miRNA hairpin. The two Rhed-binding sites are located at both ends of the hairpin. The Rhed and its RNA-binding surface are important for pri-miRNA processing activity. Additionally, the heme cofactor is required for formation of processing-competent DGCR8-pri-miRNA complexes. Our study reveals a unique protein-RNA interaction central to pri-miRNA recognition. We propose a unifying model in which two DGCR8 dimers clamp a pri-miRNA hairpin using their Rheds. PMID:24910438

  2. 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.

  3. 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.

  4. Multinucleon transfer reactions for the {sup 28}Si+{sup 90,94}Zr systems in the region below and near the Coulomb barrier

    SciTech Connect

    Kalkal, Sunil; Mandal, S.; Garg, Ritika; Saxena, Mansi; Goyal, Savi; Verma, S.; Kumar, Suresh; Singh, R.; Madhavan, N.; Jhingan, A.; Nath, S.; Gehlot, J.; Mohanto, Gayatri; Prasad, E.; Sandal, Rohit; Behera, B. R.; Pramanik, U. D.; Sinha, A. K.

    2011-05-15

    Measurements on multinucleon transfer reactions for {sup 28}Si+{sup 90,94}Zr systems were performed at sub- and near-barrier energies. The fact that {sup 90}Zr has a closed neutron shell (N = 50) and {sup 94}Zr has four neutrons outside the closed shell, allows us to investigate the effects of shell closure and pairing correlation on multinucleon transfer mechanism. The experiment was performed with pulsed {sup 28}Si beam using the Heavy Ion Reaction Analyzer (HIRA) at Inter University Accelerator Centre (IUAC), New Delhi. Based on the Q-value considerations, it turned out that pickup channels were neutron transfer whereas stripping channels were proton transfer. For the {sup 28}Si+{sup 90}Zr system, the values of the slope parameter for two-neutron pickup turned out to be less than that for one-neutron pickup. The values of the slope parameter were almost the same for two-, three-, and four-neutron pickup channels in the case of the {sup 28}Si+{sup 94}Zr system. The transfer probabilities in the case of the {sup 28}Si+{sup 94}Zr system were much larger than those for the {sup 28}Si+{sup 90}Zr system, further supporting the fact that there is a correlation between the transfer channels and sub-barrier fusion cross-section enhancement. An odd-even staggering was observed in the extracted transfer probabilities at the barrier radius implying the role of pairing correlation in transfer reactions.

  5. The Application of an Index of Efficiency to a Reading Mastery Test.

    ERIC Educational Resources Information Center

    Dziuban, Charles D.; And Others

    The Harris Index of Efficiency was used to evaluate the criterion setting (66%) of the Prescriptive Reading Inventory (PRI), a criterion referenced reading test. The subjects, who were involved in a larger experimental study that used the PRI as a criterion measure, were 92 third and fifth grade students. Initial assessment with the Comprehensive…

  6. 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.

  7. Deconvolution of pigment and physiologically related photochemical reflectance index variability at the canopy scale over an entire growing season.

    PubMed

    Hmimina, G; Merlier, E; Dufrêne, E; Soudani, K

    2015-08-01

    The sensitivity of the photochemical reflectance index (PRI) to leaf pigmentation and its impacts on its potential as a proxy for light-use efficiency (LUE) have recently been shown to be problematic at the leaf scale. Most leaf-to-leaf and seasonal variability can be explained by such a confounding effect. This study relies on the analysis of PRI light curves that were generated at the canopy scale under natural conditions to derive a precise deconvolution of pigment-related and physiologically related variability in the PRI. These sources of variability were explained by measured or estimated physiologically relevant variables, such as soil water content, that can be used as indicators of water availability and canopy chlorophyll content. The PRI mainly reflected the variability in the pigment content of the canopy. However, the corrected PRI, which was obtained by subtracting the pigment-related seasonal variability from the PRI measurement, was highly correlated with the upscaled LUE measurements. Moreover, the sensitivity of the PRI to the leaf pigment content may mask the PRI versus LUE relationship or result in an artificial relationship that reflects the relationship of chlorophyll versus LUE, depending on the species phenology.

  8. Partnership for Rural Improvement: New Dimensions. Annual Report 1980-1981.

    ERIC Educational Resources Information Center

    Hagood, Richard A.

    In 1980-1981, extended funding from the Kellogg Foundation and a total budget of $561,316 allowed the Partnership for Rural Improvement (PRI) to add to its program while continuing to emphasize project development, organizational development, interorganizational coordination, and training and education. PRI began to use task forces as a method of…

  9. 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…

  10. 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

  11. 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

  12. Dynamics of spectral bio-indicators and their correlations with light use efficiency using directional observations at a Douglas-fir forest

    NASA Astrophysics Data System (ADS)

    Cheng, Yen-Ben; Middleton, Elizabeth M.; Hilker, Thomas; Coops, Nicholas C.; Black, T. Andrew; Krishnan, Praveena

    2009-09-01

    The carbon science community must rely on satellite remote sensing to obtain global estimates of photosynthetic activity, typically expressed as net primary production (NPP), gross primary production (GPP) or light use efficiency (LUE). The photochemical reflectance index (PRI), calculated as a normalized difference reflectance index using a physiologically active green band (~531 nm) and another physiologically insensitive green reference band (~570 nm), denoted as PRI(570), has been confirmed in many studies as being strongly related to LUE. Here, we examined the potential of utilizing PRI(570) observations under different illumination conditions for canopy LUE estimation of a forest. In order to evaluate this, directional hyperspectral reflectance measurements were collected continuously throughout the daytime periods using an automated spectroradiometer in conjunction with tower-based eddy covariance fluxes and environmental measurements at a coastal conifer forest in British Columbia, Canada throughout the 2006 growing season. A parameter calculated as the PRI(570) difference (dPRI(570)) between shaded versus sunlit canopy foliage sectors showed a strong correlation to tower-based LUE. The seasonal pattern for this correlation produced a dramatic change from high negative (r ~ -0.80) values in the springtime and early fall to high positive values (r ~ 0.80) during the summer months, which could represent the seasonality of physiological characteristics and environmental factors. Although the PRI(570) successfully tracked canopy LUE, one or both of its green bands (~531 and 570 nm) used to calculate the PRI are unavailable on most existing and planned near-term satellites. Therefore, we examined the potential to use 24 other spectral indexes for LUE monitoring that might be correlated to PRI, and thereby a substitute for it. We also continued our previous investigations into the influence of illumination conditions on the observed PRI(570) and other indexes

  13. Remote Sensing of Light Use Efficiency in a Boreal Forest and Peatland in James Bay, Quebec

    NASA Astrophysics Data System (ADS)

    Rogers, Cheryl

    The photochemical reflectance index (PRI) is a remotely sensed vegetation index that detects a decrease in spectral reflectance at 531nm associated with xanthophyll cycle activity. PRI has been shown to track light use efficiency (LUE) in a number of plant species. PRI shows great promise in improving our ability to sense photosynthetic fluxes of CO2 remotely. However, it has not been tested in all environments, and its applicability is particularly uncertain for peatland environments dominated by mosses. This research investigates the ability of PRI to track LUE in a boreal forest and peatland, and examines the spectral signal associated with xanthophyll cycle activity in heterogeneous peatland plots. This research also investigates the relationship between PRI and leaf area index (LAI) over space and time in a peatland. We found most plots examined in the peatland site did not exhibit a spectral signal associated with xanthophyll cycle activity when exposed to a transition from dark conditions to full sunlight. This transition should lead to a de-epoxidation of xanthophylls in leaf tissues and a decrease in reflectance at 531nm. Plots that did show the decrease in reflectance at 531nm after this change in light conditions also displayed a decrease in PRI. This indicates that PRI effectively detects the 531nm signal as well as xanthophyll cycle activity and light stress in these plots. However, the variability in the strength of the spectral response to changing light conditions may confound the PRI signal in practice, and make it difficult to interpret results of airborne or satellite data. We also found PRI at the peatland site to be sensitive to and directly correlated with spatial variability in LAI, and negatively correlated with temporal variability in LAI. These characteristics may result in further difficulties applying PRI in peatlands. PRI and LUE were correlated at both the forest and peatland site, however at both sites the PRI signal saturated around

  14. Titanium-44 and Light Sulfur in Presolar Silicon Carbide Grains with Heavy Silicon: Proof of a Supernova Origin

    NASA Astrophysics Data System (ADS)

    Hoppe, P.; Fujiya, W.

    2011-03-01

    We report here on C, Mg-Al, Si, S, and Ca-Ti isotope measurements on presolar SiC grains with heavy Si. Heavy Si together with light S and large excesses in 44Ca, resulting from in situ decay of 44Ti, are a proof for a SN origin of these grains.

  15. 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

  16. 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

  17. Microprocessor dynamics and interactions at endogenous imprinted C19MC microRNA genes.

    PubMed

    Bellemer, Clément; Bortolin-Cavaillé, Marie-Line; Schmidt, Ute; Jensen, Stig Mølgaard Rask; Kjems, Jørgen; Bertrand, Edouard; Cavaillé, Jérôme

    2012-06-01

    Nuclear primary microRNA (pri-miRNA) processing catalyzed by the DGCR8-Drosha (Microprocessor) complex is highly regulated. Little is known, however, about how microRNA biogenesis is spatially organized within the mammalian nucleus. Here, we image for the first time, in living cells and at the level of a single microRNA cluster, the intranuclear distribution of untagged, endogenously-expressed pri-miRNAs generated at the human imprinted chromosome 19 microRNA cluster (C19MC), from the environment of transcription sites to single molecules of fully released DGCR8-bound pri-miRNAs dispersed throughout the nucleoplasm. We report that a large fraction of Microprocessor concentrates onto unspliced C19MC pri-miRNA deposited in close proximity to their genes. Our live-cell imaging studies provide direct visual evidence that DGCR8 and Drosha are targeted post-transcriptionally to C19MC pri-miRNAs as a preformed complex but dissociate separately. These dynamics support the view that, upon pri-miRNA loading and most probably concomitantly with Drosha-mediated cleavages, Microprocessor undergoes conformational changes that trigger the release of Drosha while DGCR8 remains stably bound to pri-miRNA.

  18. 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.

  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. 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

  2. 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.

  3. 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.

  4. 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

  5. Integrating Chlorophyll fapar and Nadir Photochemical Reflectance Index from EO-1/Hyperion to Predict Cornfield Daily Gross Primary Production

    NASA Technical Reports Server (NTRS)

    Zhang, Qingyuan; Middleton, Elizabeth M.; Cheng, Yen-Ben; Huemmrich, K. Fred; Cook, Bruce D.; Corp, Lawrence A.; Kustas, William P.; Russ, Andrew L.; Prueger, John H.; Yao, Tian

    2016-01-01

    The concept of light use efficiency (Epsilon) and the concept of fraction of photosynthetically active ration (PAR) absorbed for vegetation photosynthesis (PSN), i.e., fAPAR (sub PSN), have been widely utilized to estimate vegetation gross primary productivity (GPP). It has been demonstrated that the photochemical reflectance index (PRI) is empirically related to e. An experimental US Department of Agriculture (USDA) cornfield in Maryland was selected as our study field. We explored the potential of integrating fAPAR(sub chl) (defined as the fraction of PAR absorbed by chlorophyll) and nadir PRI (PRI(sub nadir)) to predict cornfield daily GPP. We acquired nadir or near-nadir EO-1/Hyperion satellite images that covered the cornfield and took nadir in-situ field spectral measurements. Those data were used to derive the PRI(sub nadir) and fAPAR (sub chl). The fAPAR (sub chl) is retrieved with the advanced radiative transfer model PROSAIL2 and the Metropolis approach, a type of Markov Chain Monte Carlo (MCMC) estimation procedure. We define chlorophyll light use efficiency Epsilon (sub chl) as the ratio of vegetation GPP as measured by eddy covariance techniques to PAR absorbed by chlorophyll (Epsilon(sub chl) = GPP/APAR (sub chl). Daily Epsilon (sub chl) retrieved with the EO-1 Hyperion images was regressed with a linear equation of PRI (sub nadir) Epsilon (sub chl) = Alpha × PRI (sub nadir) + Beta). The satellite Epsilon(sub chl- PRI (sub nadir) linear relationship for the cornfield was implemented to develop an integrated daily GPP model [GPP = (Alpha × PRI(sub nadir) + Beta) × fAPAR (sub chl) × PAR], which was evaluated with fAPAR (sub chl) and PRI (sub nadir) retrieved from field measurements. Daily GPP estimated with this fAPAR (sub chl-) PRI (nadir) integration model was strongly correlated with the observed tower in-situ daily GPP (R(sup 2) = 0.93); with a root mean square error (RMSE) of 1.71 g C mol-(sup -1) PPFD and coefficient of variation (CV) of 16

  6. 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.

  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. 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.

  9. 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.

  10. Spin-Isospin Resonances: A Self-Consistent Covariant Description

    SciTech Connect

    Liang Haozhao; Nguyen Van Giai; Meng Jie

    2008-09-19

    For the first time a fully self-consistent charge-exchange relativistic RPA based on the relativistic Hartree-Fock (RHF) approach is established. The self-consistency is verified by the so-called isobaric analog state (IAS) check. The excitation properties and the nonenergy weighted sum rules of two important charge-exchange excitation modes, the Gamow-Teller resonance (GTR) and the spin-dipole resonance (SDR), are well reproduced in the doubly magic nuclei {sup 48}Ca, {sup 90}Zr and {sup 208}Pb without readjustment of the particle-hole residual interaction. The dominant contribution of the exchange diagrams is demonstrated.

  11. Explanation of 3He and triton rates in the alpha breakup inclusive cross sections

    NASA Astrophysics Data System (ADS)

    Shyam, R.; Baur, G.; Budzanowski, A.; Bojowald, J.; Dabrowski, H.; Mayer-Böricke, C.; Oelert, W.; Riepe, G.; Rogge, M.; Turek, P.; Rösel, F.; Trautmann, D.

    1983-05-01

    (α, 3He) and (α, t) continuum inclusive spectra are measured on target nuclei ranging from 58Ni to 209Bi. Systematic differences in the absolute magnitudes of the 3He and triton spectra are found. To explain these differences the distorted-wave Born approximation calculations in the post form for inclusive breakup reactions are performed. It is shown that Coulomb effects are responsible for these differences. NUCLEAR REACTIONS (α, t), (α, 3He) breakup reactions: measured d2σd Ω dE; targets: 58Ni, 90Zr, 120Sn, 209Bi; post form DWBA breakup theory.

  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. 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.

  14. 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.

  15. Analysis of Deuteron-Nucleus Scattering Using Sao Paulo Potential

    NASA Astrophysics Data System (ADS)

    Ibraheem, Awad A.

    2016-09-01

    Deuteron elastic and inelastic scattering from 6Li, 12C, 16O, 24Mg, 32S, 50V, 58Ni, 70Ge, 90Zr, and 116Sn targets at different incident energies have been analyzed. Both Phenomenological Woods-Saxon and double-folding optical model potentials have been used. The folding calculations were based upon the Sao Paulo potential. A semi-microscopic representation has been proposed to study the effect of the dynamic polarization potential. Comparisons between our results and measured angular distributions of the differential cross sections showed a pronounced success of our theoretical predictions. The corresponding reaction cross sections have also been investigated.

  16. Ca isotopic fractionation patterns in forest ecosystems

    NASA Astrophysics Data System (ADS)

    Kurtz, A. C.; Takagi, K.

    2012-12-01

    Calcium stable isotope ratios are an emerging tracer of the biogeochemical cycle of Ca that are just beginning to see significant application to forest ecosystems. The primary source of isotopic fractionation in these systems is discrimination against light Ca during uptake by plant roots. Cycling of vegetation-fractionated Ca establishes isotopically distinct Ca pools within a forest ecosystem. In some systems, the shallow soil exchangeable Ca pool is isotopically heavy relative to Ca inputs. This has been explained by preferential removal of light Ca from the soil. In other systems, the soil exchange pool is isotopically light relative to inputs, which is explained by recycling of plant-fractionated light Ca back into soil. Thus vegetation uptake of light Ca has been called on to account for both isotopically heavy and light Ca in the shallow soil exchange pools. We interpret patterns in ecosystem δ44Ca with the aid of a simple box model of the forest Ca cycle. We suggest that the δ44Ca of exchangeable Ca in the shallow soil pool primarily reflects the relative magnitude of three key fluxes in a forest Ca cycle, 1) the flux of external Ca into the system via weathering or atmospheric deposition, 2) the uptake flux of Ca from soils into the vegetation pool, and 3) the return flux of Ca to shallow soils via remineralization of leaf litter. Two observations that emerge from our model may aid in the application of Ca isotopes to provide insight into the forest Ca cycle. First, regardless of the magnitude of both vegetation Ca uptake and isotopic fractionation, the δ44Ca of the soil exchange pool will equal the input δ44Ca unless the plant uptake and remineralization fluxes are out of balance. A second observation is that the degree to which the shallow soil exchange pool δ44Ca can differ from the input ratio is controlled by the relative rates of biological uptake and external Ca input. Significant differences between soil exchange and input δ44Ca are seen only

  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. TUNS user guide supplement: Data dictionary

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Provided is a data dictionary for the Technology Utilization Network System (TUNS) providing for each element name the long name, data type, data size, descriptive name and description, data of PRI clause, legal values, and location used.

  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. Relationship between photochemical efficiency of photosystem II and the photochemical reflectance index of mango tree: merging data from different illuminations, seasons and leaf colors.

    PubMed

    Weng, Jen-Hsien; Jhaung, Lee-Hau; Lin, Rong-Jhih; Chen, Hong-Yi

    2010-04-01

    In order to elucidate the effects of chlorophyll concentration and seasonal temperature on the relationship between photosystem II (PSII) efficiency and the photochemical reflectance index (PRI) of leaves under different light intensity, mango (Mangifera indica), a low-temperature-sensitive species, was used for the study. From early winter to summer, we selected several days to measure chlorophyll fluorescence and leaf spectral reflectance of mango leaves with dark green to yellow green colors, under natural sunlight from predawn to sunset and under six levels (0, 200, 400, 800, 1200 and 2000 mumol m(-2) s(-1)) of artificial illumination. When leaves were exposed to light, both PRI and PSII efficiency decreased with the increase in illumination, yet the PSII efficiency-PRI relationship varied with temperature and leaf color. Both predawn PRI and the X-intercept of the PSII efficiency-PRI regression equations were higher in dark green leaves and on the day with higher minimum air temperature, and lower on opposite conditions. These were due to the influence of chlorophyll on the reflection of wavebands for detecting PRI, and leaves retained a higher degree of epoxidation state of xanthophyll cycle pigments in cold predawn. Therefore, when data obtained at different seasons and with different leaf colors were pooled for analysis, PRI was not closely related to PSII efficiency. Yet, either in the darkness of predawn or under a given level of illumination, PSII efficiency always showed a significant positive correlation with PRI, with data from different leaf colors and seasons merged for statistics analysis. Because both the intercept and slope of the PSII efficiency-PRI equation showed a negative regression with photosynthetic photon flux (PPF), an empirical regression model, i.e., PSII efficiency = c + d . PPF + e . (PPF)(2) + f . PRI + g . PPF . PRI, could be fitted for multiple regression analysis. Based on the close correlation between the estimated and measured

  2. Vitamin D analogs combined with 5-fluorouracil in human HT-29 colon cancer treatment

    PubMed Central

    MILCZAREK, MAGDALENA; FILIP-PSURSKA, BEATA; ŚWIĘTNICKI, WIESŁAW; KUTNER, ANDRZEJ; WIETRZYK, JOANNA

    2014-01-01

    In the present study, we evaluated the antitumor effect of two synthetic analogs of vitamin D, namely PRI-2191 [(24R)-1,24-dihydroxyvitamin D3] and PRI-2205 (5,6-trans calcipotriol), in combined human colon HT-29 cancer treatment with 5-fluorouracil (5-FU). Mice bearing HT-29 tumors transplanted subcutaneously or orthotopically were injected with vitamin D analogs and 5-FU in various schedules. A statistically significant inhibition of subcutaneous or orthotopic tumor growth was observed as a result of combined therapy. In HT-29 tumors and in cells from in vitro culture, we observed increased vitamin D receptor (VDR) expression after treatment with either PRI-2205 or 5-FU alone, or in combination. Moreover, PRI-2205 decreased the percentage of cells from intestinal tumors in G2/M and S stages and increased sub-G1. Increased VDR expression was also observed after combined treatment of mice with 5-FU and PRI-2191. Moreover, our docking studies showed that PRI-2205 has stronger affinity for VDR, DBP and CAR/RXR ligand binding domains than PRI-2191. PRI-2191 analog, used with 5-FU, increased the percentage of subcutaneous tumor cells in G0/G1 and decreased the percentage in G2/M, S and sub-G1 populations as compared to 5-FU alone. In in vitro studies, we observed increased expression of p21 and p-ERK1/2 diminution via use of both analogs as compared to use of 5-FU alone. Simultaneously, PRI-2191 antagonizes some pro-apoptotic activities of 5-FU in vitro. However, in spite of these disadvantageous effects in terms of apoptosis, the therapeutic effect expressed as tumor growth retardation by PRI-2191 is significant. Our results suggest that the mechanism of potentiation of 5-FU antitumor action by both analogs is realized via increased p21 expression and decreased p-ERK1/2 level which may lead to diminution of thymidylate synthase expression. Higher binding affinity for VDR, DBP, but also for CAR\\RXR ligand binding domain of PRI-2205 may, in part, explain its very low

  3. 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

  4. 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

  5. Steric effects on the mode of aggregation and reactivity of clusters formed from the lithiation of trisamidothiophosphates.

    PubMed

    Chivers, T; Krahn, M; Parvez, M; Schatte, G

    2001-10-01

    Lithiation of SP[N(H)R]3 with LiBun produces the dimers [(THF)LiSP(NR)(NHR)2]2 (R = Pri) or ([LiSP(NR)-(NHR)2][(THF)LiSP(NR)2(NHR)])2 (R = But) with central Li2N2 or Li2S2 rings, respectively; further lithiation yields the dianion [SP(NR)2(NHR)]2- (R = Pri) or leads to sulfur extrusion when R = But. PMID:12240220

  6. HP1BP3, a Chromatin Retention Factor for Co-transcriptional MicroRNA Processing.

    PubMed

    Liu, Haoming; Liang, Chunyang; Kollipara, Rahul K; Matsui, Masayuki; Ke, Xiong; Jeong, Byung-Cheon; Wang, Zhiqiang; Yoo, Kyoung Shin; Yadav, Gaya P; Kinch, Lisa N; Grishin, Nicholas V; Nam, Yunsun; Corey, David R; Kittler, Ralf; Liu, Qinghua

    2016-08-01

    Recent studies suggest that the microprocessor (Drosha-DGCR8) complex can be recruited to chromatin to catalyze co-transcriptional processing of primary microRNAs (pri-miRNAs) in mammalian cells. However, the molecular mechanism of co-transcriptional miRNA processing is poorly understood. Here we find that HP1BP3, a histone H1-like chromatin protein, specifically associates with the microprocessor and promotes global miRNA biogenesis in human cells. Chromatin immunoprecipitation (ChIP) studies reveal genome-wide co-localization of HP1BP3 and Drosha and HP1BP3-dependent Drosha binding to actively transcribed miRNA loci. Moreover, HP1BP3 specifically binds endogenous pri-miRNAs and facilitates the Drosha/pri-miRNA association in vivo. Knockdown of HP1BP3 compromises pri-miRNA processing by causing premature release of pri-miRNAs from the chromatin. Taken together, these studies suggest that HP1BP3 promotes co-transcriptional miRNA processing via chromatin retention of nascent pri-miRNA transcripts. This work significantly expands the functional repertoire of the H1 family of proteins and suggests the existence of chromatin retention factors for widespread co-transcriptional miRNA processing.

  7. 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

  8. 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

    2015-11-13

    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.

  9. 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

  10. [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

  11. 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.

  12. 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

  13. 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

  14. Effect of the electron decay of metallic fission products on the chemical and phase compositions of an irradiated uranium-plutonium fuel

    NASA Astrophysics Data System (ADS)

    Bondarenko, G. G.; Bulatov, G. S.; Gedgovd, K. N.; Lyubimov, D. Yu.; Yakushkin, M. M.

    2009-10-01

    A complex structure is shown to form in the uranium-plutonium nitride U0.8Pu0.2N irradiated by fast neutrons. It consists of a uranium-based solid solution; plutonium, zirconium, yttrium, and lanthanide nitrides; and individual condensed phases such as U2N3, BaTe, CeRu2, LaSe, Rh3Te2, USe, Ba3N2, CsI, Sr3N2, metallic molybdenum, and U(Ru, Rh, Pd)3 intermetallic compounds. The amount and composition of these phases are calculated at temperatures of 900 and 1900 K in the process of depletion to 18% heavy atoms (U + Pu). The variation of the composition of the irradiated uranium-plutonium nitride is studied upon the electron decay of metallic radionuclides. The kinetics of the transformations of 89Sr3N2 and 90Sr3N2 to 89YN + 89Y and 90ZrN + 90Zr, respectively, is calculated.

  15. 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.

  16. (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.

  17. 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.

  18. Microscopic Theory of Heavy-Ion Interaction Potentials.

    NASA Astrophysics Data System (ADS)

    Katoot, Mohammad Walid

    Heavy-ion interaction potentials are calculated in a realistic, fully microscopic theory. The theory is based on the nonrelativistic quantum theory of many-body systems and is formulated in the language of second quantization; it utilizes a molecular set of basis states (two-center shell model) rather than selfconsistent wavefunctions. These basis states depend on two collective parameters: internuclear distance and fragment deformation. In constructing the ground state of the interacting many-body system, we assume, for simplicity, that the nucleons remain in the lowest possible molecular energy levels throughout the reaction. This adiabaticity assumption appears to be justified at bombarding energies near the Coulomb barrier. For computational reasons, the effective nucleon -nucleon interaction is described by a Skyrme force without spin-orbit coupling. The 5 parameters of the Skyrme interaction are fitted to measured binding energies. Heavy-ion interaction potentials are calculated for the following systems: ('28)Si + ('28)Si, ('40)Ca + ('40)Ca, ('90)Zr + ('90)Zr and ('238)U + ('238)U. At large internuclear distances, our theory approaches the double -folding model, which reproduces elastic and inelastic scattering data. However, at smaller distances, it is much more realistic than these phenomenological models, because (a) exchange energy and kinetic energy contributions are calculated consistently and (b) shell effects are taken into account. Possible improvements of the theory are discussed in the last chapter.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. Variations in the marine Ca cycle over the past 20 Ma

    SciTech Connect

    Fantle, Matthew S.; DePaolo, D.

    2005-03-23

    A 20 million year marine Ca isotope record is constructedbased on measurements of 36 nannofossil ooze samples from DSDP Site 590.The Ca isotopic composition (d44Ca, relative to our b bulk EarthQaverage) of carbonate ooze samples varies between ?0.2 and ?0.9, and theinferred d44Ca of seawater calcium varies between +1.1 and +0.4 (modernseawater value is +0.95 on our scale). Fluctuations in the seawater Caisotope ratio occur in 2 to 4 million year intervals and indicate thatthe supply and removal of Ca from the oceans are seldom in balance. TheCa isotope record is used to reconstruct past weathering fluxes andmarine calcium concentrations. The inferred marine concentration of Cafluctuates by about F20 percent on 2-4 million year time scales and byabout F50 percent over the 20 million year record. These variations arepresumably superimposed on the previously inferred 100 million yearvariations. The seawater Ca concentration was about 0.5 times present at20 Ma and generally increased until 6 Ma (1.7 times present). Localmaxima in seawater calcium concentrations occur at 6.4 and 4 Ma,preceding periods of enhanced marine productivity and high massaccumulation rates at Site 590. While the calculated calciumconcentrations are sensitive to the assumed d44Ca value for theweathering flux, the 2-4 million year features of the derived curves arenot.

  5. 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.

  6. Successful disabling of the 5' UTR of HCV using adeno-associated viral vectors to deliver modular multimeric primary microRNA mimics.

    PubMed

    Bourhill, Tarryn; Arbuthnot, Patrick; Ely, Abdullah

    2016-09-01

    Chronic hepatitis C virus (HCV) infection is a major health concern and is strongly associated with cirrhosis, hepatocellular carcinoma and liver-related mortality. The HCV genome is the template for both protein translation and viral replication and, being RNA, is amenable to direct genetic silencing by RNA interference (RNAi). HCV is a highly mutable virus and is capable of escaping RNAi-mediated silencing. This has highlighted the importance of developing RNAi-based therapy that simultaneously targets multiple regions of the HCV genome. To develop a multi-targeting RNAi activator, a novel approach for the generation of anti-HCV gene therapy was investigated. Five artificial primary miRNA (pri-miR) were each designed to mimic the naturally occurring monomeric pri-miR-31. Potent knockdown of an HCV reporter was seen with four of the five constructs and were processed according to the intended design. The design of the individual pri-miR mimics enabled the modular assembly into multimeric mimics of any possible conformation. Consequently the four potent pri-miR mimics were used to generate polycistronic cassettes, which showed impressive silencing of an HCV target. To further their application as a gene therapy, recombinant adeno-associated viral (rAAV) vectors that express the polycistronic pri-miR mimics were generated. All AAV-delivered anti-HCV pri-miR mimics significantly knocked down the expression of an HCV target and showed inhibition of HCV replicon replication. Here we describe a protocol for the generation of therapeutic rAAVs that express modular polycistronic pri-miR cassettes allowing for rapid alteration and generation of tailored therapeutic constructs against HCV. PMID:27181212

  7. The core microprocessor component DiGeorge syndrome critical region 8 (DGCR8) is a nonspecific RNA-binding protein.

    PubMed

    Roth, Braden M; Ishimaru, Daniella; Hennig, Mirko

    2013-09-13

    MicroRNA (miRNA) biogenesis follows a conserved succession of processing steps, beginning with the recognition and liberation of an miRNA-containing precursor miRNA hairpin from a large primary miRNA transcript (pri-miRNA) by the Microprocessor, which consists of the nuclear RNase III Drosha and the double-stranded RNA-binding domain protein DGCR8 (DiGeorge syndrome critical region protein 8). Current models suggest that specific recognition is driven by DGCR8 detection of single-stranded elements of the pri-miRNA stem-loop followed by Drosha recruitment and pri-miRNA cleavage. Because countless RNA transcripts feature single-stranded-dsRNA junctions and DGCR8 can bind hundreds of mRNAs, we explored correlations between RNA binding properties of DGCR8 and specific pri-miRNA substrate processing. We found that DGCR8 bound single-stranded, double-stranded, and random hairpin transcripts with similar affinity. Further investigation of DGCR8/pri-mir-16 interactions by NMR detected intermediate exchange regimes over a wide range of stoichiometric ratios. Diffusion analysis of DGCR8/pri-mir-16 interactions by pulsed field gradient NMR lent further support to dynamic complex formation involving free components in exchange with complexes of varying stoichiometry, although in vitro processing assays showed exclusive cleavage of pri-mir-16 variants bearing single-stranded flanking regions. Our results indicate that DGCR8 binds RNA nonspecifically. Therefore, a sequential model of DGCR8 recognition followed by Drosha recruitment is unlikely. Known RNA substrate requirements are broad and include 70-nucleotide hairpins with unpaired flanking regions. Thus, specific RNA processing is likely facilitated by preformed DGCR8-Drosha heterodimers that can discriminate between authentic substrates and other hairpins.

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

    PubMed

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

    2012-02-01

    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 CO(2)-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 (A(n)) and stomatal conductance (g(s)) showed that, across the three N-fertilization rates, the intrinsic WUE was significantly higher in PRI than in DI leaves. Analysis of the CO(2)-response curve revealed that both carboxylation efficiency (CE) and the CO(2)-saturated photosynthetic rate (A(sat)) 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 A(sat) in the PRI leaves was accompanied by significant decreases in carbon isotope discrimination (Δ(13)C) and bundle-sheath cell leakiness to CO(2) (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 (A(max)) 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 A(sat) derived from the CO(2)-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, A(sat), and κ of maize leaves and that contributes to the greater intrinsic WUE in those plants.

  9. Successful disabling of the 5' UTR of HCV using adeno-associated viral vectors to deliver modular multimeric primary microRNA mimics.

    PubMed

    Bourhill, Tarryn; Arbuthnot, Patrick; Ely, Abdullah

    2016-09-01

    Chronic hepatitis C virus (HCV) infection is a major health concern and is strongly associated with cirrhosis, hepatocellular carcinoma and liver-related mortality. The HCV genome is the template for both protein translation and viral replication and, being RNA, is amenable to direct genetic silencing by RNA interference (RNAi). HCV is a highly mutable virus and is capable of escaping RNAi-mediated silencing. This has highlighted the importance of developing RNAi-based therapy that simultaneously targets multiple regions of the HCV genome. To develop a multi-targeting RNAi activator, a novel approach for the generation of anti-HCV gene therapy was investigated. Five artificial primary miRNA (pri-miR) were each designed to mimic the naturally occurring monomeric pri-miR-31. Potent knockdown of an HCV reporter was seen with four of the five constructs and were processed according to the intended design. The design of the individual pri-miR mimics enabled the modular assembly into multimeric mimics of any possible conformation. Consequently the four potent pri-miR mimics were used to generate polycistronic cassettes, which showed impressive silencing of an HCV target. To further their application as a gene therapy, recombinant adeno-associated viral (rAAV) vectors that express the polycistronic pri-miR mimics were generated. All AAV-delivered anti-HCV pri-miR mimics significantly knocked down the expression of an HCV target and showed inhibition of HCV replicon replication. Here we describe a protocol for the generation of therapeutic rAAVs that express modular polycistronic pri-miR cassettes allowing for rapid alteration and generation of tailored therapeutic constructs against HCV.

  10. 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.

  11. 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

  12. 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

  13. 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

  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. 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

  16. Overexpression of adenosine deaminase acting on RNA 1 in chordoma tissues is associated with chordoma pathogenesis by reducing miR-125a and miR-10a expression

    PubMed Central

    KUANG, LEI; LV, GUOHUA; WANG, BING; LI, LEI; DAI, YULIANG; LI, YAWEI

    2015-01-01

    Chordoma is a rare, slow-growing primary malignant neoplasm of the axial skeleton, which arises from the remnants of the notochord. Emerging evidence suggests that microRNAs (miRs) are dysregulated in chordoma tissues and crucially involved in chordoma pathogenesis. In the present study, the expression of 11 candidate miRs were analyzed in chordoma tissues and miR-10a and miR-125a were found to be significantly downregulated compared with controls. Notably, the expression of the primary transcripts, pri-miR-125a and pri-miR-10a was unaltered, suggesting that disturbed microRNA expression may be induced by altered pri-miRNA processing. Previous studies have indicated that disturbed adenosine deaminase acting on RNA (ADAR) expression is able to alter mRNA and miRNA adenosine to inosine (A-to-I) levels associated with cancer pathogenesis. Therefore, the expression of ADAR1 and ADAR2 was analyzed in chordoma tissues. It was found that ADAR1 was significantly overexpressed, which was accompanied by enhanced pre-miR-10a and pri-miR-125a A-to-I editing. These findings suggest that ADAR2 overexpression causes enhanced pre-miR-10a and pri-miR-125a A-to-I editing, which alters mature miR-10a and miR-125a expression and may contribute to chordoma pathogenesis. PMID:25673044

  17. The Menu of Features that Define Primary MicroRNAs and Enable De Novo Design of MicroRNA Genes.

    PubMed

    Fang, Wenwen; Bartel, David P

    2015-10-01

    MicroRNAs (miRNAs) are small regulatory RNAs processed from stem-loop regions of primary transcripts (pri-miRNAs), with the choice of stem loops for initial processing largely determining what becomes a miRNA. To identify sequence and structural features influencing this choice, we determined cleavage efficiencies of >50,000 variants of three human pri-miRNAs, focusing on the regions intractable to previous high-throughput analyses. Our analyses revealed a mismatched motif in the basal stem region, a preference for maintaining or improving base pairing throughout the remainder of the stem, and a narrow stem-length preference of 35 ± 1 base pairs. Incorporating these features with previously identified features, including three primary-sequence motifs, yielded a unifying model defining mammalian pri-miRNAs in which motifs help orient processing and increase efficiency, with the presence of more motifs compensating for structural defects. This model enables generation of artificial pri-miRNAs, designed de novo, without reference to any natural sequence yet processed more efficiently than natural pri-miRNAs. PMID:26412306

  18. The thermodynamic characteristics of vaporization in the NaI-PrI3 system

    NASA Astrophysics Data System (ADS)

    Motalov, V. B.; Kudin, L. S.; Markus, T.

    2009-05-01

    The vaporization of the NaI-PrI3 quasi-binary system was studied by high-temperature mass spectrometry over the whole concentration range. At 623-994 K, saturated vapor contained not only (NaI) n and (PrI3) n molecules ( n = 1, 2) and Na+(NaI) n ( n = 0-4) and I-(PrI3) n ( n = 1-2) ions but also mixed molecular and ionic associates recorded for the first time (NaPrI4, Na2PrI5, NaPrI{3/+}, Na2PrI{4/+}, Na3PrI{5/+}, Na4PrI{6/+}, NaPrI{5/-}, and NaPr2I{8/-}). The partial vapor pressures of molecules were calculated, and the equilibrium constants of the dissociation of neutral and charged associates were measured. The enthalpies of molecular and ion-molecular reactions were determined, and the enthalpies of formation of gaseous molecules and ions were obtained.

  19. 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.

  20. 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

    2016-06-15

    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.

  1. 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

  2. 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

  3. 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

  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. 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

  6. Ca Isotope Fractionation in the Hawaiian Ecosystem

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    Investigations of the nutrient budgets in Hawaiian soils show the sources of major cations to be weathering of volcanic rock, marine aerosols, and Asian dust inputs. Especially at deeply weathered sites older than 150 ka, soils show strong depletion of the macronutrient calcium. Most of the calcium supply in these soils is of atmospheric origin (marine aerosols and continental dust). In contrast, younger soils are mainly supplied by calcium from weathering of volcanic bedrock. Based on the results of previous studies using strontium isotopic signatures and Sr/Ca ratios (e.g. Kennedy et al. 1998, Chadwick et al. 1999, Whipkey et al. 2000, Stewart et al. 2001) we have conducted research focusing on the isotope composition of calcium as a new tool for the investigation of sources of calcium and biogeochemical processes effecting Ca isotope fractionation in the plant-soil system. The study combines δ 44Ca with 87Sr/86Sr and Sr/Ca data of soils (bulk compositions and extractable Ca and Sr from soil exchange sites) and different plant species including native Ohia trees (Metrosideros polymorpha) from a soil chronosequence along the Hawaiian Island chain. The study sites differ in age of the underlying substrate from 0.3 ka to 4,100 ka, but show similar recent climate (mean annual temperature of 16 ° C) and amount of precipitation (about 2,500 mm/y). 44Ca/40Ca ratios were measured on a MAT262 at Stanford University, using a 42Ca-48Ca double spike, and are reported as δ 44Ca values relative to seawater (δ 44Ca = 0 ‰ ). Results of the extractable, plant available calcium from six soil sites show δ 44Ca values in the range of +1.2 ‰ to -1.3 ‰ with generally more negative values related to younger soil sites where calcium is mainly derived from weathering of volcanic rocks. Bulk soil samples, however, show δ 44Ca values between -0.1 ‰ and -2.5 ‰ , indicating differences in composition as a result of contributions from volcanic minerals, continental dust, and

  7. 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

  8. 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

  9. 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

  10. Extraction of weak transition strengths via the (3He, t) reaction at 420 MeV.

    PubMed

    Zegers, R G T; Adachi, T; Akimune, H; Austin, Sam M; van den Berg, A M; Brown, B A; Fujita, Y; Fujiwara, M; Galès, S; Guess, C J; Harakeh, M N; Hashimoto, H; Hatanaka, K; Hayami, R; Hitt, G W; Howard, M E; Itoh, M; Kawabata, T; Kawase, K; Kinoshita, M; Matsubara, M; Nakanishi, K; Nakayama, S; Okumura, S; Ohta, T; Sakemi, Y; Shimbara, Y; Shimizu, Y; Scholl, C; Simenel, C; Tameshige, Y; Tamii, A; Uchida, M; Yamagata, T; Yosoi, M

    2007-11-16

    Differential cross sections for transitions of known weak strength were measured with the (3He, t) reaction at 420 MeV on targets of 12C, 13C, 18O, 26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn, and 208Pb. Using these data, it is shown that the proportionalities between strengths and cross sections for this probe follow simple trends as a function of mass number. These trends can be used to confidently determine Gamow-Teller strength distributions in nuclei for which the proportionality cannot be calibrated via beta-decay strengths. Although theoretical calculations in the distorted-wave Born approximation overestimate the data, they allow one to understand the main experimental features and to predict deviations from the simple trends observed in some of the transitions.

  11. {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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Dirac Calculations for Proton Inelastic Scattering at Intermediate Energies

    NASA Astrophysics Data System (ADS)

    El-Nohy, N. A.; El-Hammamy, M. N.; Aly, N. E.; Abdel-Moneim, A. M.; Hamza, A. F.

    2016-09-01

    Relativistic proton inelastic scattering from different targets (16O, 24Mg, 28Si, 40Ca, 54Fe, 58Ni, 90Zr, 154Sm, 176Yb, and 208Pb) at intermediate energies is analyzed in the framework of phenomenological optical potentials based on the Dirac formalism. Parameters of the Dirac phenomenological potential with Woods Saxon (WS) shape are obtained. The first order vibrational collective model with one phonon is used to calculate the transition optical potentials to the first low-lying excited state (2+) of the investigated target nuclei. Also, the variation of deformation length (δ) with energy and mass number is studied. It is noticed that the deformation length increases slightly with energy at intermediate range.

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

    PubMed

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

    2012-03-01

    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.

  1. 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

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

    PubMed

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

    2012-03-01

    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

  3. Tracking seasonal changes of leaf and canopy light use efficiency in a Phlomis fruticosa Mediterranean ecosystem using field measurements and multi-angular satellite hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Stagakis, Stavros; Markos, Nikos; Sykioti, Olga; Kyparissis, Aris

    2014-11-01

    Numerous normalized difference spectral indices (NDSIs) derived from leaf measurements and CHRIS/PROBA hyperspectral and multi-angular satellite images were examined for their capacity to track seasonal variations of leaf (εleaf) and canopy (εcan) light use efficiency of a Mediterranean phryganic ecosystem. A series of seasonal field ecophysiological measurements, i.e. leaf area index (LAI), leaf photosynthesis and leaf reflectance, were conducted on the Phlomis fruticosa shrubs at the days of CHRIS acquisitions over the study site. Leaf scale analysis confirmed background theory on the relationship of the photochemical reflectance index (PRI) with εleaf and provided a detailed view of the wavelengths that can be used in PRI formulation for the specific species. In canopy scale analysis, PRI and some alternative formulations of this index based on CHRIS bands, presented the most significant relationships with εcan, indicating that this index preserves its efficiency in satellite observations for the specific ecosystem. Additionally, spectral indices related to chlorophyll and water content were found to present good relationships with εcan. Taking into account the functional relationship between εcan and chlorophyll content, a combination of the xanthophyll de-epoxidation band (531 nm) with 701 nm CHRIS band in a NDSI is suggested as an alternative to the original PRI formulation that could improve seasonal εcan estimations. The satellite observation geometry effects on the determination of εcan were not very intense for the studied ecosystem. However, the most effective viewing direction was proved to be the backward scattering, while zenith observations were the least efficient for the specific ecosystem, most probably due to increased background effects. Even though the sensitivity of the original PRI formulation to εcan was reduced in forward scattering viewing directions, when 531 nm xanthophyll de-epoxidation band was replaced with higher wavelength

  4. Photochemistry, remotely sensed physiological reflectance index and de-epoxidation state of the xanthophyll cycle in Quercus coccifera under intense drought.

    PubMed

    Peguero-Pina, José Javier; Morales, Fermín; Flexas, Jaume; Gil-Pelegrín, Eustaquio; Moya, Ismael

    2008-05-01

    Quercus coccifera L. is a Mediterranean sclerophyllous shrub with a high capacity to resist intense drought stress. Therefore, it could be used in the study of physiological changes suffered by plants at very low water potentials. A remote sensing sensor was used to measure continuously the physiological reflectance index (PRI; defined as the changes in reflectance at 531 nm with respect to those at 570 nm; PRI = [(R531 - R570)/(R531 + R570)] at canopy level and under field conditions in an artificial carpet of seedlings of Q. coccifera during a drought cycle. Correlations between leaf level-measured chlorophyll fluorescence parameters as well as the de-epoxidation state of the xanthophyll cycle [(A + Z)/(V + A + Z)] and canopy level-measured PRI were reasonably good (R (2) = 0.57-0.63, P < 0.01), and quite interesting for water stress remote sensing purposes. The instrument's temporal resolution allowed us to follow the rapid response of PRI to changing photosynthetic active radiation, and to resolve, in response to cloud-induced changes in light intensity, a fast and a slow PRI component. We report the disappearance of the rapid one under conditions of intense drought in response to a sudden increase in light intensity. The underlying photoprotection mechanisms that Q. coccifera shows in response to intense drought stress periods seem to be related to the existence of a low intrathylakoid lumenal pH at the end of the drought cycle. Under intense drought, these mechanisms allow this species to avoid oxidative damage, which was evidenced by the maintenance of an unaltered photosynthetic pigment composition and constant photosystem II efficiency in the mornings. It is concluded that, contrary to early reports, PRI is a sensible, indirect, non-destructive water stress indicator, even in plants experiencing intense drought.

  5. Chlorophyll index, photochemical reflectance index and chlorophyll fluorescence measurements of rice leaves supplied with different N levels.

    PubMed

    Shrestha, Suchit; Brueck, Holger; Asch, Folkard

    2012-08-01

    Rapid and non-destructive diagnosis of plant N status is highly required in order to optimise N fertilizer management and use-efficiency. Additionally to handheld devices for measurements of chlorophyll indices (e.g., SPAD meter) parameters of canopy reflectance via remote sensing approaches are intensively investigated and the photochemical reflectance index (PRI) appears to be a reliable indicator for changes of the epoxidation state of xanthophyll cycle pigments. In order to assess the suitability of a handheld PRI as an additional tool for N diagnosis, rice plants were grown in a nutrient solution experiment with seven N-supply levels (0.18-5.71 mM) and CI (SPAD) and PRI values and chlorophyll fluorescence parameters measured 20 and 28 days after onset of treatments. N-supply had effects on both CI (SPAD) and PRI values with a more reliable differentiation between levels. Maximum quantum yield of PSII (F(v)/F(m)), actual efficiency of PSII photochemistry (Ф(PSII)) and regulated non-photochemical quenching (Ф(NPQ)) did not differ significantly between N levels. Non-photochemical quenching (NPQ) and fast- relaxing NPQ (NPQ(F)) were significantly affected by N-supply. NPQ and NPQ(F), but not the slow-relaxing component (NPQ(S)), were correlated with CI (SPAD) and PRI values. This finding which has not been reported for N-supply effects so far is indirect evidence that low N-supply induced xanthophyll cycle activity and that PRI values are able to indicate this at least in plants subject to severe N deficiency.

  6. 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).

  7. Vitamin D analogs enhance the anticancer activity of 5-fluorouracil in an in vivo mouse colon cancer model

    PubMed Central

    2013-01-01

    Background Active vitamin D analogs that are less toxic than calcitriol can be useful in the combined treatment of patients suffering from colon cancer. In the present study we demonstrate, for the first time in an in vivo model system, the biological effect of combined therapy using 5-fluorouracil (5-FU) along with vitamin D analog PRI-2191 (tacalcitol, 1,24-dihydroxyvitamin D3) or PRI-2205 (5,6-trans-isomer of calcipotriol) on colon cancer. Methods We investigated the influence of vitamin D analogs on the anticancer activity of 5-FU or capecitabine in the treatment of mice bearing MC38 mouse colon tumors implanted subcutaneously or orthotopically. The cell cycle distribution, E-cadherin expression and caspase 3/7 activity in vitro were also evaluated. Results We observed that both PRI-2191 and PRI-2205 significantly enhanced the antitumor activity of 5-FU; but these results depend on the treatment regimen. Applying the optimal schedule of combined therapy we observed a significant decrease in tumor growth, metastasis and also a prolongation of the survival time of mice, in comparison with the administrations of 5-FU given alone. Both combinations indicated a synergistic effect and did not cause toxicity. Moreover, analogs applied after completed course of administration of 5-FU, prolonged the antitumor effect of the drug. Furthermore, when the prodrug of 5-FU, capecitabine, was used, potentiation of its activity was also observed. Conclusions Our data suggest that vitamin D analogs (especially PRI-2191) might be potentially applied to clinical use in order to enhance the anticancer effect of 5-FU and also prolong its activity against colon cancer. The activity of PRI-2191 is realized through stopping the cells in the G0/G1 cell cycle phase and increasing the expression of E-cadherin. PMID:23777514

  8. Application of the Zr/Hf ratio in the determination of hafnium in geochemical samples by high-resolution inductively coupled plasma mass spectrometry.

    PubMed

    Liu, Ya Xuan; Li, Qing Xia; Ma, Na; Sun, Xiao Ling; Bai, Jin Feng; Zhang, Qin

    2014-12-01

    Hafnium content and its change are of significance in geochemistry and cosmochemistry; however, the determination of hafnium has always been problematic in analytical chemistry. In this paper, a new idea is proposed for the determination of hafnium in geochemical samples, including rocks, soils, and stream sediments. Through the comparison of two conventional open-type acid digestion methods (HF-HNO3-HClO4 and HF-HNO3-H2SO4), it was found that although neither of these methods could fully digest the zirconium and hafnium in a sample, the zirconium and hafnium digestion behaviors in one sample were consistent in the 60 experimental geochemical reference materials with different properties, so the experimentally determined Zr/Hf ratio in solution could be used to calculate the hafnium content in a sample. In addition, possible mass spectral interferences during the determination of zirconium and hafnium by high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) were studied, and it was found that the mass spectral interferences of the selected isotopes (90)Zr and (178)Hf could be neglected. The mass spectral behaviors of (90)Zr and (178)Hf were also very consistent during the determination by HR-ICPMS. Since the hafnium content was calculated using the ratio value, all of the errors (including the errors in weighing process, the accidental errors during operation and the instrument fluctuation in the determination) of the Zr/Hf ratio could be effectively reduced or even eliminated. The relative standard deviation of the actual samples was lower than 3.2%, and the detection limit of the method (considering the dilution effect and matrix effect during measurement of the Zr/Hf ratio and zirconium content) was 0.04 μg/g. The proposed method could satisfy the requirement for the determination of hafnium in geochemical samples.

  9. Electric dipole response of nuclei studied by proton inelastic scattering: neutron thickness, symmetry energy, and pygmy dipole resonance

    NASA Astrophysics Data System (ADS)

    Tamii, Atsushi; RCNP E282/E316/E326/E350/E376/E377 Collaboration

    2014-09-01

    Electric dipole (E1) responses of heavy nuclei have been studied by high-resolution measurement of proton inelastic scattering at forward angles including zero degrees. Here the proton scattering at 300 MeV is used as an electromagnetic probe to extract precisely the distribution of E1 reduced transition probability B(E1). The measurement has been done on various stable nuclei such as 208Pb, 120Sn, 90Zr, 154Sm, and 96Mo. The dipole polarizability and pygmy dipole resonance (PDR) strength has been extracted. Those quantities are considered to have strong correlations to the neutron skin thickness and the first order density dependence of the symmetry energy of the nuclear equation of state. We will present the experimental methods and highlights of the results as well as the preliminary ones of recent analyses. Electric dipole (E1) responses of heavy nuclei have been studied by high-resolution measurement of proton inelastic scattering at forward angles including zero degrees. Here the proton scattering at 300 MeV is used as an electromagnetic probe to extract precisely the distribution of E1 reduced transition probability B(E1). The measurement has been done on various stable nuclei such as 208Pb, 120Sn, 90Zr, 154Sm, and 96Mo. The dipole polarizability and pygmy dipole resonance (PDR) strength has been extracted. Those quantities are considered to have strong correlations to the neutron skin thickness and the first order density dependence of the symmetry energy of the nuclear equation of state. We will present the experimental methods and highlights of the results as well as the preliminary ones of recent analyses. JSPS No. 25105509.

  10. 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

  11. 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

  12. 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.

  13. 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.

  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. 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

  16. The isotopic composition of cosmic ray calcium

    NASA Technical Reports Server (NTRS)

    Krombel, K. E.; Wiedenbeck, M. E.

    1985-01-01

    Data from the high energy cosmic ray experiment on the international sun earth explorer 3 (ISEE-3) spacecraft have been used to study the isotopic composition of cosmic ray calcium at an energy of approx. 260 MeV/amu. The arriving calcium is found to consist of (32 + or - 6)%. A propagation model consistent with both the light and the subiron secondary element abundances was used for the interpretation of the observed calcium composition. The measured 42Ca+43Ca+44Ca abundance is consistent with the calculated secondary production, while the 40Ca abundance implies a source ratio of 40Ca/Fe = (7.0 + or - 1.7)%.

  17. 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.

  18. 12 CFR 263.53 - Discovery depositions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... part, unnecessary, unreasonable, oppressive, excessive in scope or unduly burdensome, he or she may... administrative law judge may terminate or limit the scope and manner of the deposition upon a finding that..., irrelevant or immaterial matters; or (3) Unreasonably attempt to pry into a party's preparation for trial....

  19. 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

  20. 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.

  1. 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...

  2. 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…

  3. 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

  4. Microprocessor activity controls differential miRNA biogenesis In Vivo.

    PubMed

    Conrad, Thomas; Marsico, Annalisa; Gehre, Maja; Orom, Ulf Andersson

    2014-10-23

    In miRNA biogenesis, pri-miRNA transcripts are converted into pre-miRNA hairpins. The in vivo properties of this process remain enigmatic. Here, we determine in vivo transcriptome-wide pri-miRNA processing using next-generation sequencing of chromatin-associated pri-miRNAs. We identify a distinctive Microprocessor signature in the transcriptome profile from which efficiency of the endogenous processing event can be accurately quantified. This analysis reveals differential susceptibility to Microprocessor cleavage as a key regulatory step in miRNA biogenesis. Processing is highly variable among pri-miRNAs and a better predictor of miRNA abundance than primary transcription itself. Processing is also largely stable across three cell lines, suggesting a major contribution of sequence determinants. On the basis of differential processing efficiencies, we define functionality for short sequence features adjacent to the pre-miRNA hairpin. In conclusion, we identify Microprocessor as the main hub for diversified miRNA output and suggest a role for uncoupling miRNA biogenesis from host gene expression.

  5. 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...

  6. The thermodynamic characteristics of vaporization of praseodymium triiodide

    NASA Astrophysics Data System (ADS)

    Motalov, V. B.; Kudin, L. S.; Markus, T.

    2009-03-01

    The vaporization of praseodymium triiodide was studied by high-temperature mass spectrometry. Monomeric (PrI3) and dimeric (Pr2I6) molecules and the PrI{4/-} and Pr2I{7/-} negative ions were recorded in saturated vapor over the temperature range 842-1048 K. The partial pressures of neutral vapor components were determined. The enthalpies of sublimation Δs H o(298.15 K) in the form of monomers (291 ± 10 kJ/mol) and dimers (400 ± 30 kJ/mol) were calculated by the second and third laws of thermodynamics. The equilibrium constants of ion-molecular reactions were measured and the enthalpies of the reactions determined. The enthalpies of formation Δf H o(298.15 K) of molecules and ions in the gas phase were calculated (-373 ± 11, -929 ± 31, -865 ± 25, and -1433 ± 48 kJ/mol for PrI3, Pr2I6, PrI{4/-}, and Pr2I{7/-}, respectively).

  7. 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...

  8. Effects of local injection of prilocaine-felypressin on the myocardial oxygen balance in dogs.

    PubMed

    Miyachi, Kenji; Ichinohe, Tatsuya; Kaneko, Yuzuru

    2003-08-01

    The authors investigated the effects of felypressin (Fely), a non-adrenergic vasoconstrictor, used together with prilocaine on myocardial oxygen balance. Six open-chest dogs were studied under urethane and alpha-chloralose anesthesia. Systolic arterial pressure, diastolic arterial pressure, mean pulmonary arterial pressure and pulmonary capillary wedge pressure, heart rate, coronary blood flow (CBF), internal and external myocardial oxygen tension (int- or ext-PmO2), and cardiac output were observed. Three doses of Citanest-Octapressin, which contains 3% prilocaine and 0.03 IU ml(-1) Fely (Pri-Fely) - 0.09, 0.18, and 0.3 ml kg(-1)- were injected into the tongue. Observations were performed up to 60 min after the injection. The CBF and int-PmO2 was reduced following the injection of each of the three doses of Pri-Fely. There were negative correlations between the Pri-Fely dose per body weight and the maximum reductions in CBF (r = -0.52, P < 0.05), in int-PmO2 (r = -0.78, P < 0.05), and in ext-PmO2 (r = -0.55, P < 0.05), respectively [corrected]. These results suggest that an administration of Fely at doses more than 2.7-5.4 mIU kg(-1) (3-6 cartridges of Pri-Fely) may induce an imbalance between the oxygen supply and demand in myocardial tissues of patients with cardiovascular diseases.

  9. 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...

  10. Development of one-step Loop-Mediated Isothermal Amplification (LAMP) for the detection of norovirus in oysters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The aim of this study was to develop a simple and rapid technique for detecting human norovirus (NoV). The loop-mediated isothermal amplification (LAMP) technique was evaluated and found to be sensitive, highly specific, and useful for routine oyster testing. Reverse transcription-LAMP (RT-LAMP) 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. 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.

  13. Spectral bio-indicator simulations for tracking photosynthetic activities in a corn field

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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 light environment; and 2) seasonal variation corresponding to the growth stage. The RT model (ACRM) successfully simulated the responses to the 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.

  14. 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…

  15. 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…

  16. 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...

  17. 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

  18. 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.

  19. 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…

  20. 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...

  1. 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...

  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. 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

  4. Development and Validation of the Pain Response Inventory for Children.

    ERIC Educational Resources Information Center

    Walker, Lynn S.; Smith, Craig A.; Garber, Judy; Van Slyke, Deborah A.

    1997-01-01

    Confirmatory factor analysis was used to derive and cross-validate the factor structure of the Pain Response Inventory (PRI), a measure of children's coping responses to recurrent pain, with 688 school children, 120 children with abdominal pain, and 175 former abdominal pain patients. Results suggest that different health outcomes are predicted by…

  5. 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.

  6. 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...

  7. Assessing Data Accuracy When Involving Students in Authentic Paleontological Research.

    ERIC Educational Resources Information Center

    Harnik, Paul G.; Ross, Robert M.

    2003-01-01

    Regards Student-Scientist Partnerships (SSPs) as beneficial collaborations for both students and researchers. Introduces the Paleontological Research Institution (PRI), which developed and pilot tested an SSP that involved grade 4-9 students in paleontological research on Devonian marine fossil assemblages. Reports formative data assessment and…

  8. 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...

  9. 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…

  10. 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.

  11. 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…

  12. 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...

  13. Effects of N fertilization on the relationship between photosynthetic light use efficiency and photochemical reflectance index of wetland vegetation

    NASA Astrophysics Data System (ADS)

    Cheng, Qian; Wu, Xiuju

    2010-11-01

    Monitoring of light use efficient (LUE) over space and time is a critical component of climate change research as it is a major determinant of the amount of carbon accumulated by terrestrial ecosystems. PRI (Photochemical reflectance index) has provide a fast and reliable method for estimating photosynthetic light use efficiency across species. The aim of this study was to evaluate the use of ground-based canopy reflectance measurements to detect changes in physiology of wetland vegetation in response to experimental nitrogen (N) treatment. In this paper, Bulrush with different nitrogen fertilization were selected to research the influence of varied fertilization levels on the relationship between PRI and LUE. The results proved that leaf chlorophyll contents as well as canopy PRI increased with the increase in nitrogen fertilization. For different nitrogen fertilization of Bulrush, the regression coefficients R2 varied respectively. Therefore, PRI not only can be a reliable indicator of LUE but also can reflect the growing situation of Bulrush with different precisions of LUE assessment.

  14. 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…

  15. 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…

  16. 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…

  17. 12 CFR 19.170 - Discovery depositions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 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...

  18. 12 CFR 19.170 - Discovery depositions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 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...

  19. 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

  20. Depressive Mood Induction: The Reactivity of Positive Affect.

    ERIC Educational Resources Information Center

    Zevon, Michael A.; And Others

    Mood induction procedures have been widely used as laboratory analogues of depression. This study evaluated the effectiveness of the Velten depression mood induction (VMI) procedure and a personal recall depression induction (PRI) procedure. In contrast to prior research, mood was assessed in terms of two independent dimensions: positive affect…

  1. 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...

  2. 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...

  3. 47 CFR 54.802 - Obligations of local exchange carriers and the Administrator.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... purposes of computing support under this subpart, the aggregated residential/single-line business class... and other related residential class lines. Similarly, the multi-line business class lines reported include multi-line business, centrex, ISDN PRI and other related business class lines assessed the...

  4. 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...

  5. 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...

  6. 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…

  7. 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...

  8. 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...

  9. 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…

  10. Validated stability-indicating HPLC method for the determination of pridinol mesylate. Kinetics study of its degradation in acid medium.

    PubMed

    Bianchini, Romina M; Castellano, Patricia M; Kaufman, Teodoro S

    2008-12-01

    The stability of pridinol mesylate (PRI) was investigated under different stress conditions, including hydrolytic, oxidative, photolytic and thermal, as recommended by the ICH guidelines. Relevant degradation was found to take place under acidic (0.1N HCl) and photolytic (visible and long-wavelength UV-light) conditions, both yielding the product resulting from water elimination (ELI), while submission to an oxidizing environment gave the N-oxidation derivative (NOX). The standards of these degradation products were synthesized and characterized by IR, (1)H and (13)C NMR spectroscopy. A simple, sensitive and specific HPLC method was developed for the quantification of PRI, ELI and NOX in bulk drug, and the conditions were optimized by means of a statistical design strategy. The separation employs a C(18) column and a 51:9:40 (v/v/v) mixture of MeOH, 2-propanol and potassium phosphate solution (50mM, pH 6.0), as mobile phase, delivered at 1.0 ml min(-1); the analytes were detected and quantified at 220 nm. The method was validated, demonstrating to be accurate and precise (repeatability and intermediate precision levels) within the corresponding linear ranges of PRI (0.1-1.5 mg ml(-1); r=0.9983, n=18) and both impurities (0.1-1.3% relative to PRI, r=0.9996 and 0.9995 for ELI and NOX, respectively, n=18). Robustness against small modifications of pH and percentage of the aqueous mobile phase was ascertained and the limits of quantification of the analytes were also determined (0.4 and 0.5 microg ml(-1); 0.04% and 0.05% relative to PRI for ELI and NOX, respectively). Peak purity indices (>0.9997), obtained with the aid of diode-array detection, and satisfactory resolution (R(s)>2.0) between PRI and its impurities established the specificity of the determination, all these results proving the stability-indicating capability of the method. The kinetics of the degradation of PRI in acid medium was also studied, determining that this is a first-order process with regards

  11. 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

  12. 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.

  13. Anti-malarial Drugs Primaquine and Chloroquine Have Different Sensitization Effects with Anti-mitotic Drugs in Resistant Cancer Cells.

    PubMed

    Choi, Ae-Ran; Kim, Ju-Hwa; Woo, Yeon Hwa; Kim, Hyung Sik; Yoon, Sungpil

    2016-04-01

    The purpose of this study was to identify conditions that would increase the sensitivity of drug-resistant cancer cells. Previously, two anti-malarial drugs, chloroquine (CHL) and primaquine (PRI), showed different sensitization effects for vinblastine (VIB)-resistant cancer cells. Herein, we tested co-treatment of cells with CHL or PRI and other microtubule-targeting cancer drugs, namely, vinorelbine (VIO), paclitaxel (PAC), docetaxel (DOC), vincristine (VIC), or halaven (HAL). We found that PRI sensitized P-glycoprotein (P-gp)-overexpressing drug-resistant KBV20C cells to all six anti-mitotic drugs to a similar extent. CHL had a similar sensitization effect only for co-treatment with PAC, DOC, VIC, and HAL, while the sensitization effect was less marked for co-treatment with VIB or VIO. FACS analysis and western blot analysis revealed that G2arrest and apoptosis showed only a slight increase on co-treatment with VIB or VIO and CHL. We also found that phospho-histone H3 and pRb were markedly increased only by PRI-VIB co-treatment, but not by CHL-VIB co-treatment. This suggests that reduction in the expression of these proteins correlates with decreased G2arrest in CHL-VIB co-treatment. We further compared the effect of another anti-malarial drug, mefloquine (MEF), in combination with the six anti-mitotic drugs. We found that MEF and PRI had similar sensitization effects in co-treatment with these anti-mitotic drugs. PRI and MEF had generally similar sensitization effects in co-treatment with anti-mitotic drugs, suggesting that they do not have any preferred anti-mitotic drug partner in co-treatment. This indicates that only CHL shows specificity in co-treatment with anti-mitotic drugs in resistant cancer cells. Our results may contribute to the choice of anti-mitotic drugs to be used in co-treatment of resistant cancer cells with the anti-malarial drugs, CHL, PRI, and MEF. PMID:27069141

  14. 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

  15. Occurrence of glycosidically conjugated 1-phenylethanol and its hydrolase β-primeverosidase in tea (Camellia sinensis) flowers.

    PubMed

    Zhou, Ying; Dong, Fang; Kunimasa, Aiko; Zhang, Yuqian; Cheng, Sihua; Lu, Jiamin; Zhang, Ling; Murata, Ariaki; Mayer, Frank; Fleischmann, Peter; Watanabe, Naoharu; Yang, Ziyin

    2014-08-13

    A previous study found that 1-phenylethanol (1PE) was a major endogenous volatile compound in tea (Camellia sinensis) flowers and can be transformed to glycosically conjugated 1PE (1PE-Gly). However, occurrences of 1PE-Gly in plants remain unknown. In this study, four 1PE-Glys have been isolated from tea flowers. Three of them were determined as (R)-1PE β-d-glucopyranoside ((R)-1PE-Glu), (S)-1PE-Glu, and (S)-1PE β-primeveroside ((S)-1PE-Pri), respectively, on the basis of NMR, MS, LC-MS, and GC-MS evidence. The other one was identified as (R)-1PE-Pri on the basis of LC-MS and GC-MS data. Moreover, these 1PE-Glys were chemically synthesized as the authentic standards to further confirm their occurrences in tea flowers. 1PE-Glu had a higher molar concentration than 1PE-Pri in each floral stage and organ. The ratio of (R) to (S) differed between 1PE-Glu and 1PE-Pri. In addition, a 1PE-Gly hydrolase β-primeverosidase recombinant protein produced in Escherichia coli exhibited high hydrolysis activity toward (R)-1PE-Pri. However, β-primeverosidase transcript level was not highly expressed in the anther part, which accumulated the highest contents of 1PE-Gly and 1PE. This suggests that 1PE-Gly may not be easily hydrolyzed to liberate 1PE in tea flowers. This study provides evidence of occurrences of 1PE-Glys in plants for the first time.

  16. 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

  17. 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.

  18. 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

  19. 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

  20. On the use of leaf spectral indices to assess water status and photosynthetic limitations in Olea europaea L. during water-stress and recovery.

    PubMed

    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.

  1. 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).

  2. 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

  3. The kinase ABL phosphorylates the microprocessor subunit DGCR8 to stimulate primary microRNA processing in response to DNA damage.

    PubMed

    Tu, Chi-Chiang; Zhong, Yan; Nguyen, Louis; Tsai, Aaron; Sridevi, Priya; Tarn, Woan-Yuh; Wang, Jean Y J

    2015-06-30

    The DNA damage response network stimulates microRNA (miRNA) biogenesis to coordinate repair, cell cycle checkpoints, and apoptosis. The multistep process of miRNA biogenesis involves the cleavage of primary miRNAs by the microprocessor complex composed of the ribonuclease Drosha and the RNA binding protein DGCR8. We found that the tyrosine kinase ABL phosphorylated DGCR8, a modification that was required for the induction of a subset of miRNAs after DNA damage. Focusing on the miR-34 family, ABL stimulated the production of miR-34c, but not miR-34a, through Drosha/DGCR8-dependent processing of primary miR-34c (pri-miR-34c). This miRNA-selective effect of ABL required the sequences flanking the precursor miR-34c (pre-miR-34c) stem-loop. In pri-miRNA processing, DGCR8 binds the pre-miR stem-loop and recruits Drosha to the miRNA. RNA cross-linking assays showed that DGCR8 and Drosha interacted with pri-miR-34c, but we found an inverse correlation between ABL-stimulated processing and DGCR8 association with pri-miR-34c. When coexpressed in HEK293T cells, ABL phosphorylated DGCR8 at Tyr(267). Ectopic expression of a Y267F-DGCR8 mutant reduced the recruitment of Drosha to pri-miR-34c and prevented ABL or Drosha from stimulating the processing of pri-miR-34c. In mice engineered to express a nuclear import-defective mutant of ABL, miR-34c, but not miR-34a, expression was reduced in the kidney, and apoptosis of the renal epithelial cells was impaired in response to cisplatin. These results reveal a new pathway in the DNA damage response wherein ABL-dependent tyrosine phosphorylation of DGCR8 stimulates the processing of selective primary miRNAs.

  4. The kinase ABL phosphorylates the microprocessor subunit DGCR8 to stimulate primary microRNA processing in response to DNA damage

    PubMed Central

    Tu, Chi-Chiang; Zhong, Yan; Nguyen, Louis; Tsai, Aaron; Sridevi, Priya; Tarn, Woan Yu; Wang, Jean Y. J.

    2015-01-01

    The DNA damage response network stimulates microRNA (miRNA) biogenesis to coordinate repair, cell cycle checkpoints and apoptosis. The multistep process of miRNA biogenesis involves the cleavage of primary miRNAs by the microprocessor complex comprised of the RNase Drosha and the RNA-binding protein DGCR8. We found that the tyrosine kinase ABL phosphorylated DGCR8, a modification that was required for the induction of a subset of miRNAs after DNA damage. Focusing on the miR-34 family, ABL stimulated the production of miR-34c but not miR-34a through Drosha/DGCR8-dependent processing of primary miR-34c (pri-miR-34c). This miRNA-selective effect of ABL required the sequences flanking the precursor miR-34c (pre-miR-34c) stem-loop. In pri-miRNA processing, DGCR8 binds the pre-miRNA stem-loop and recruits Drosha to the miRNA. RNA crosslinking assays showed that DGCR8 and Drosha interacted with pri-miR-34c, but we found an inverse correlation between ABL-stimulated processing and DGCR8 association with pri-miR-34c. When co-expressed in HEK293T cells, ABL phosphorylated DGCR8 at Tyr267. Ectopic expression of a Y267F-DGCR8 mutant reduced the recruitment of Drosha to pri-miR-34c and prevented ABL or Drosha from stimulating the processing of pri-miR-34c. In mice engineered to express a nuclear import-defective mutant of ABL, miR-34c but not miR-34a expression was reduced in the kidney and apoptosis of the renal epithelial cells was impaired in response to cisplatin. These results reveal a new pathway in the DNA damage response wherein ABL-dependent tyrosine phosphorylation of DGCR8 stimulates the processing of selective primary miRNAs. PMID:26126715

  5. Determination of (90)Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS).

    PubMed

    Feuerstein, J; Boulyga, S F; Galler, P; Stingeder, G; Prohaska, T

    2008-11-01

    A rapid method is reported for the determination of (90)Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of (90)Zr, which is present in soils at concentrations higher by more than six orders of magnitude than (90)Sr. Zirconium was separated from strontium in two steps to reduce the interference by (90)Zr(+) ions by a factor of more than 10(7): (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from (88)Sr on mass 90 u was found to be about 3 x 10(-9). Detection limits of 4 fg g(-1) (0.02 Bq g(-1)) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 microg g(-1) Sr and 50 ng g(-1) Zr a detection limit of 0.2 pg g(-1) soil (1 Bq g(-1) soil) was determined. (90)Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66+/-0.27, 13.48+/-0.68 and 12.9+/-1.5 pg g(-1) corresponding to specific activities of 23.7+/-1.3, 68.6+/-3.5 and 65.6+/-7.8 Bq g(-1), respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level (90)Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g(-1). PMID:18760512

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. Complementation of Hyponastic Leaves1 by Double-Strand RNA-Binding Domains of Dicer-Like1 in Nuclear Dicing Bodies1[W][OPEN

    PubMed Central

    Liu, Qi; Yan, Qingqing; Liu, Yin; Hong, Fang; Sun, Zhenfei; Shi, Leilei; Huang, Ying; Fang, Yuda

    2013-01-01

    MicroRNAs (miRNAs) are a class of small regulatory RNAs that are found in almost all of the eukaryotes. Arabidopsis (Arabidopsis thaliana) miRNAs are processed from primary miRNAs (pri-miRNAs), mainly by the ribonuclease III-like enzyme DICER-LIKE1 (DCL1) and its specific partner, HYPONASTIC LEAVES1 (HYL1), a double-strand RNA-binding protein, both of which contain two double-strand RNA-binding domains (dsRBDs). These dsRBDs are essential for miRNA processing, but the functions of them are not clear. Here, we report that the two dsRBDs of DCL1 (DCL1-D1D2), and to some extent the second dsRBD (DCL1-D2), complement the hyl1 mutant, but not the first dsRBD of DCL1 (DCL1-D1). DCL1-D1 is diffusely distributed throughout the nucleoplasm, whereas DCL1-D2 and DCL1-D1D2 concentrate in nuclear dicing bodies in which DCL1 and HYL1 colocalize. We show further that protein-protein interaction is mainly mediated by DCL1-D2, while DCL1-D1 plays a major role in binding of pri-miRNAs. These results suggest parallel roles between C-terminal dsRBDs of DCL1 and N-terminal dsRBDs of HYL1 and support a model in which Arabidopsis pri-miRNAs are recruited to dicing bodies through functionally divergent dsRBDs of microprocessor for accurate processing of plant pri-miRNAs. PMID:23886622

  16. Reviewing the effect of reflexology on the pain and certain features and outcomes of the labor on the primiparous women

    PubMed Central

    Valiani, Mahboubeh; Shiran, Elaheh; Kianpour, Maryam; Hasanpour, Marziyeh

    2010-01-01

    BACKGROUND: Reflexology is one of the non-pharmacological pain relief methods, and since it is a non-invasive, inexpensive and applicable technique, it can be used by a skilled and trained midwife. This study aimed to review the effect of reflexology on the pain and outcomes of the labor. METHODS: In this quasi-experimental study, 88 primiparous mothers referred to selected hospitals of Isfahan for vaginal delivery were selected using simple random sampling method and then randomized in two groups. Data collection tools were the demographic data questionnaire, profile and outcomes of the labor and the short-form of the McGill Questionnaire for Pain Rating Index (PRI) assessment. The intervention was general and specific reflexology in the active phase of labor. PRI was assessed before the intervention and four times after the intervention (3-5 cm, 6-8 cm and 9-10 cm dilatations and second stage of labor. RESULTS: There was no significant difference between groups before intervention. In the reflexology group, there was a significant difference between the PRI before and after the 4 stages intervention (p < 0.001). PRI was different significantly between studied groups after intervention (p < 0.001). The length of active phase of labor was different significantly between the two groups; but this difference was not significant during the second (p = 0.29), and the third (p = 0.27) stages. The difference between the 1st minute and the 5th minute Apgar score (p < 0.001) and rate of hemorrhage between the two groups were different significantly (p = 0.02). CONCLUSIONS: Reflexology can lead to decrease in the labor pain. Therefore, regarding to the safety of this technique, it can be replaced as an alternative for pharmacological methods. PMID:22069404

  17. Signaling by p38 MAPK stimulates nuclear localization of the microprocessor component p68 for processing of selected primary microRNAs.

    PubMed

    Hong, Sungguan; Noh, Hyangsoon; Chen, Haoming; Padia, Ravi; Pan, Zhixing K; Su, Shi-Bing; Jing, Qing; Ding, Han-Fei; Huang, Shuang

    2013-03-12

    The importance of microRNAs (miRNAs) in biological and disease processes necessitates a better understanding of the mechanisms that regulate miRNA abundance. We showed that the activities of the mitogen-activated protein kinase (MAPK) p38 and its downstream effector kinase MAPK-activated protein kinase 2 (MK2) were necessary for the efficient processing of a subset of primary miRNAs (pri-miRNAs). Through yeast two-hybrid screening, we identified p68 (also known as DDX5), a key component of the Drosha complex that processes pri-miRNAs, as an MK2-interacting protein, and we found that MK2 phosphorylated p68 at Ser(197) in cells. In wild-type mouse embryonic fibroblasts (MEFs) treated with a p38 inhibitor or in MK2-deficient (MK2(-/-)) MEFs, expression of a phosphomimetic mutant p68 fully restored pri-miRNA processing, suggesting that MK2-mediated phosphorylation of p68 was essential for this process. We found that, whereas p68 was present in the nuclei of wild-type MEFs, it was found mostly in the cytoplasm of MK2(-/-) MEFs. Nuclear localization of p68 depended on MK2-mediated phosphorylation of Ser(197). In addition, inhibition of p38 MAPK promoted the growth of wild-type MEFs and breast cancer MCF7 cells by enhancing the abundance of c-Myc through suppression of the biogenesis of the miRNA miR-145, which targets c-Myc. Because pri-miRNA processing occurs in the nucleus, our findings suggest that the p38 MAPK-MK2 signaling pathway promotes miRNA biogenesis by facilitating the nuclear localization of p68.

  18. Overexpression of primary microRNA 221/222 in acute myeloid leukemia

    PubMed Central

    2013-01-01

    Background Acute myeloid leukemia (AML) is a hematopoietic malignancy with a dismal outcome in the majority of cases. A detailed understanding of the genetic alterations and gene expression changes that contribute to its pathogenesis is important to improve prognostication, disease monitoring, and therapy. In this context, leukemia-associated misexpression of microRNAs (miRNAs) has been studied, but no coherent picture has emerged yet, thus warranting further investigations. Methods The expression of 636 human miRNAs was compared between samples from 52 patients with AML and 13 healthy individuals by highly specific locked nucleic acid (LNA) based microarray technology. The levels of individual mature miRNAs and of primary miRNAs (pri-miRs) were determined by quantitative reverse transcriptase (qRT) PCR. Transfections and infections of human cell lines were performed using standard procedures. Results 64 miRNAs were significantly differentially expressed between AML and controls. Further studies on the clustered miRNAs 221 and 222, already known to act as oncogenes in other tumor types, revealed a deficiency of human myeloid cell lines to process vector derived precursor transcripts. Moreover, endogenous pri-miR-221/222 was overexpressed to a substantially higher extent than its mature products in most primary AML samples, indicating that its transcription was enhanced, but processing was rate limiting, in these cells. Comparison of samples from the times of diagnosis, remission, and relapse of AML demonstrated that pri-miR-221/222 levels faithfully reflected the stage of disease. Conclusions Expression of some miRNAs is strongly regulated at the posttranscriptional level in AML. Pri-miR-221/222 represents a novel molecular marker and putative oncogene in this disease. PMID:23895238

  19. A novel function for the DEAD-box RNA helicase DDX-23 in primary microRNA processing in Caenorhabditis elegans.

    PubMed

    Chu, Yu-De; Chen, Hsin-Kai; Huang, Tao; Chan, Shih-Peng

    2016-01-15

    Primary microRNAs (pri-miRNAs) are cleaved by the nuclear RNase III Drosha to produce hairpin-shaped precursor miRNAs (pre-miRNAs). In humans, this process is known to be facilitated by the DEAD-box helicases p68 (DDX5) and p72 (DDX17). In this study, we performed a candidate-based RNAi screen in C. elegans to identify DEAD/H-box proteins involved in miRNA biogenesis. In a let-7(mg279) sensitized genetic background, knockdown of a homolog of yeast splicing factor Prp28p, DDX-23, or a homolog of human helicases p68 and p72, DDX-17, enhanced let-7 loss-of-function phenotypes, suggesting that these helicases play a role in let-7 processing and/or function. In both ddx-23(RNAi) and ddx-17(RNAi), levels of mature let-7 were decreased while pri-let-7 was found to accumulate, indicating that the helicases likely act at the level of pri-let-7 processing. DDX-23 and DDX-17 were also required for the biogenesis of other known heterochronic miRNAs, including lin-4 and the let-7 family members miR-48, miR-84 and miR-241. Their function was not confined to the heterochronic pathway, however, since they were both necessary for down-regulation of cog-1 by the spatial patterning miRNA, lsy-6. Here, we present a novel function for C. elegans DDX-23 in pri-miRNA processing, and also suggest a conserved role for DDX-17 in this process.

  20. First Steps Towards Dissolution of NaSO4- by Water

    SciTech Connect

    Wang, Xue B.; Woo, Hin-koon; Jagoda-Cwiklik, Barbra; Jungwirth, Pavel; Wang, Lai S.

    2006-10-07

    NaSO4-(H2O)n (n = 0–4) clusters have been generated in the gas phase as model systems to simulate the first dissolution steps of sulfate salts in water; photoelectron spectroscopy and theoretical calculations indicate that the first three water molecules strongly interact with both Na+ and SO4 2-, forming a threewater solvation ring to pry apart the Na+SO4 2- contact ion pair.

  1. Handoff from recombinase to replisome: insights from transposition.

    PubMed

    Nakai, H; Doseeva, V; Jones, J M

    2001-07-17

    Bacteriophage Mu replicates as a transposable element, exploiting host enzymes to promote initiation of DNA synthesis. The phage-encoded transposase MuA, assembled into an oligomeric transpososome, promotes transfer of Mu ends to target DNA, creating a fork at each end, and then remains tightly bound to both forks. In the transition to DNA synthesis, the molecular chaperone ClpX acts first to weaken the transpososome's interaction with DNA, apparently activating its function as a molecular matchmaker. This activated transpososome promotes formation of a new nucleoprotein complex (prereplisome) by yet unidentified host factors [Mu replication factors (MRF alpha 2)], which displace the transpososome in an ATP-dependent reaction. Primosome assembly proteins PriA, PriB, DnaT, and the DnaB--DnaC complex then promote the binding of the replicative helicase DnaB on the lagging strand template of the Mu fork. PriA helicase plays an important role in opening the DNA duplex for DnaB binding, which leads to assembly of DNA polymerase III holoenzyme to form the replisome. The MRF alpha 2 transition factors, assembled into a prereplisome, not only protect the fork from action by nonspecific host enzymes but also appear to aid in replisome assembly by helping to activate PriA's helicase activity. They consist of at least two separable components, one heat stable and the other heat labile. Although the MRF alpha 2 components are apparently not encoded by currently known homologous recombination genes such as recA, recF, recO, and recR, they may fulfill an important function in assembling replisomes on arrested replication forks and products of homologous strand exchange. PMID:11459960

  2. Replication restart: a pathway for (CTG).(CAG) repeat deletion in Escherichia coli.

    PubMed

    Kim, Seung-Hwan; Pytlos, Małgorzata J; Sinden, Richard R

    2006-03-20

    (CTG)n.(CAG)n repeats undergo deletion at a high rate in plasmids in Escherichia coli in a process that involves RecA and RecB. In addition, DNA replication fork progression can be blocked during synthesis of (CTG)n.(CAG)n repeats. Replication forks stalled at (CTG)n.(CAG)n repeats may be rescued by replication restart that involves recombination as well as enzymes involved in replication and DNA repair, and this process may be responsible for the high rate of repeat deletion in E. coli. To test this hypothesis (CAG)n.(CTG)n deletion rates were measured in several E. coli strains carrying mutations involved in replication restart. (CAG)n.(CTG)n deletion rates were decreased, relative to the rates in wild type cells, in strains containing mutations in priA, recG, ruvAB, and recO. Mutations in priB and priC resulted in small reductions in deletion rates. In a recF strain, rates were decreased when (CAG)n comprised the leading template strand, but rates were increased when (CTG)n comprised the leading template. Deletion rates were increased slightly in a recJ strain. The mutational spectra for most mutant strains were altered relative to those in parental strains. In addition, purified PriA and RecG proteins showed unexpected binding to single-stranded, duplex, and forked DNAs containing (CAG)n and/or (CTG)n loop-outs in various positions. The results presented are consistent with an interpretation that the high rates of trinucleotide repeat instability observed in E. coli result from the attempted restart of replication forks stalled at (CAG)n.(CTG)n repeats. PMID:16472829

  3. Complex feedback regulations govern the expression of miRNA396 and its GRF target genes.

    PubMed

    Hewezi, Tarek; Baum, Thomas J

    2012-07-01

    The beet cyst nematode, Heterodera schachtii, is a sedentary root parasite that induces the formation of a specialized root feeding structure, the syncytium. We previously have shown that coordinated regulation of miR396 and its target genes GRF1 and GRF3 in the syncytium is required for proper formation. To gain a better understanding of this coordinated regulation, we used quantitative real-time PCR to assess the abundance of primary (pri)-miRNA396a, pri-miRNA396b and mature miRNA396 in transgenic Arabidopsis plants overexpressing either wild-type variants of the GRF1 or GRF3 coding sequences or miR396-resistant variants. We also included a grf1/grf2/grf3 triple mutant in these analyses. We observed significant decreases in the abundance of pri-miRNA396a, pri-miRNA396b and mature miR396 in the transgenic plants overexpressing GRF1 or GRF3, particularly with the miRNA396-resistant variants. In contrast, the primary transcripts and mature miRNA396 abundance were significantly increased in the grf1/grf2/grf3 triple knockout mutant. These results demonstrate that homeostasis between miR396 and the target genes GRF1 and GRF3 is established through reciprocal feedback regulation, in which GRF1/GRF3 and miR396 negatively regulate each other's expression. In addition, we found that constitutive expression of GRF1 or GRF3 decreases the mRNA abundance of other GRFs, even those that are not targeted by miR396, as well as their own endogenous transcripts, which documents further regulatory facets of this equilibrium. PMID:22751317

  4. 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.

  5. 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...

  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. Determination of component mobilities in bimineralic reaction rims using isotopically doped starting materials

    NASA Astrophysics Data System (ADS)

    Joachim, Bastian; Abart, Rainer; Höschen, Carmen; Heinrich, Wilhelm

    2013-04-01

    Rim growth experiments were performed between monticellite (CaMgSiO4) single crystals and wollastonite (CaSiO3) powder at 900° C and 1.2 GPa to produce bimineralic diopside (CaMgSi2O6) + merwinite (Ca3MgSi2O8) reaction rims. Symmetrical makeup of the internal rim microstructure implies that rims grow from the original interface towards both reactants at identical rates, indicating that solely MgO-diffusion controls overall rim growth with logD (MgO) = -16.3 ± 0.2 m2s-1 (Joachim et al. 2012). Presence of ppm-amounts of water significantly affects the internal rim microstructure. At "very dry" condition, a lamellar microstructure of alternating palisade-shaped diopside and merwinite grains elongated normal to the reaction front is generated, indicating that CaO and SiO2-mobilities are significantly smaller compared to the MgO-mobility. In presence of minute amounts of water a segregated multilayer microstructure with almost perfectly monomineralic merwinite - diopside - merwinite layers oriented parallel to the reaction front develops, indicating a sufficient additional mobility of either CaO or SiO2 compared to MgO. We used isotopically doped wollastonite (44Ca29SiO3) to identify, which component mobility, CaO or SiO2, is enhanced in presence of ppm amounts of water. Both, 44Ca stemming from the wollastonite as well as 40Ca stemming from the monticellite are distributed across the entire rim. In addition to that, small amounts of 40Ca are found within the wollastonite and substantial amounts of 44Ca are found in the monticellite starting material. In contrast to that, 28Si and 29Si remain in the regions that were originally occupied by their respective source materials monticellite and wollastonite, indicating that the SiO2-mobility is comparatively low. This suggests that the presence of small amounts of water significantly enhances the relative mobility of CaO. Consequently minute amounts of water may not only affect overall rim growth kinetics but also the

  8. 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.

  9. A Biogenesis Step Upstream of Microprocessor Controls miR-17∼92 Expression.

    PubMed

    Du, Peng; Wang, Longfei; Sliz, Piotr; Gregory, Richard I

    2015-08-13

    The precise control of miR-17∼92 microRNA (miRNA) is essential for normal development, and overexpression of certain miRNAs from this cluster is oncogenic. Here, we find that the relative expression of the six miRNAs processed from the primary (pri-miR-17∼92) transcript is dynamically regulated during embryonic stem cell (ESC) differentiation. Pri-miR-17∼92 is processed to a biogenesis intermediate, termed "progenitor-miRNA" (pro-miRNA). Pro-miRNA is an efficient substrate for Microprocessor and is required to selectively license production of pre-miR-17, pre-miR-18a, pre-miR-19a, pre-miR-20a, and pre-miR-19b from this cluster. Two complementary cis-regulatory repression domains within pri-miR-17∼92 are required for the blockade of miRNA processing through the formation of an autoinhibitory RNA conformation. The endonuclease CPSF3 (CPSF73) and the spliceosome-associated ISY1 are responsible for pro-miRNA biogenesis and expression of all miRNAs within the cluster except miR-92. Thus, developmentally regulated pro-miRNA processing is a key step controlling miRNA expression and explains the posttranscriptional control of miR-17∼92 expression in development.

  10. Microprocessor mediates transcriptional termination of long noncoding RNA transcripts hosting microRNAs.

    PubMed

    Dhir, Ashish; Dhir, Somdutta; Proudfoot, Nick J; Jopling, Catherine L

    2015-04-01

    MicroRNAs (miRNAs) play a major part in the post-transcriptional regulation of gene expression. Mammalian miRNA biogenesis begins with cotranscriptional cleavage of RNA polymerase II (Pol II) transcripts by the Microprocessor complex. Although most miRNAs are located within introns of protein-coding transcripts, a substantial minority of miRNAs originate from long noncoding (lnc) RNAs, for which 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 lncRNA transcripts containing miRNAs (lnc-pri-miRNAs) do not use the canonical cleavage-and-polyadenylation pathway but instead use Microprocessor cleavage to terminate transcription. Microprocessor inactivation leads to extensive transcriptional readthrough of lnc-pri-miRNA and transcriptional interference with downstream genes. Consequently we define a new RNase III-mediated, polyadenylation-independent mechanism of Pol II transcription termination in mammalian cells.

  11. Sister chromatid exchange in human lymphocytes induced by propoxur following plant activation by Vicia faba.

    PubMed

    Gómez-Arroyo, S; Calderón-Segura, M E; Villalobos-Pietrini, R

    1995-01-01

    Because the carbamate insecticide propoxur induced sister chromatid exchanges (SCE) in Vicia faba but was ineffective in producing SCE in lymphocytes in culture, it was hardly suspected that plant metabolism was involved. Experiments were conducted in which metabolic activation was afforded by Vicia faba roots, and SCE in human lymphocytes in vitro was used to assess cytogenetic damage. Several concentrations of propoxur (250, 500, 1,000, 1,500, and 2,000 ppm) were applied for 4 hr to the roots of Vicia faba. Extracts prepared from these treatments were added to the lymphocyte cultures and a significant increase of SCE frequencies with a concentration-response relationship could be detected. The lymphocyte proliferation kinetics and the proliferation rate index (PRI) were not affected (except in the highest concentration, of 2,000 ppm). This general behavior was in agreement with the presence of an enzymatic system (S10 fraction) in Vicia roots capable of metabolizing or activating the propoxur. With 2,000 ppm, cell necrosis was produced in Vicia; therefore, this extract did not induce SCE in lymphocytes. However, lymphocyte proliferation kinetics were delayed and PRI was significantly decreased. Ethanol, a promutagen activated by this plant, was applied directly to the lymphocyte cultures as a positive control, and the response was negative. On the other hand, the extracts of roots treated with ethanol increased the SCE to more than twice that of the negative control, but the lymphocyte proliferation kinetics and PRI were not affected.

  12. 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.

  13. 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.

  14. MicroRNA miR-92a-1 biogenesis and mRNA targeting is modulated by a tertiary contact within the miR-17∼92 microRNA cluster

    PubMed Central

    Chaulk, Steven G.; Xu, Zhizhong; Glover, Mark J. N.; Fahlman, Richard P.

    2014-01-01

    While functional mature microRNAs (miRNAs) are small ∼22 base oligonucleotides that target specific mRNAs, miRNAs are initially expressed as long transcripts (pri-miRNAs) that undergo sequential processing to yield the mature miRNAs. We have previously reported that the pri-miR-17∼92 cluster adopts a compact globular folded structure that internalizes a 3′ core domain resulting in reduced miRNA maturation and subsequent mRNA targeting. Using a site-specific photo-cross-linker we have identified a tertiary contact within the 3′ core domain of the pri-miRNA between a non-miRNA stem-loop and the pre-miR-19b hairpin. This tertiary contact is involved in the formation of the compact globular fold of the cluster while its disruption enhances miR-92a expression and mRNA targeting. We propose that this tertiary contact serves as a molecular scaffold to restrict expression of the proposed antiangiogenic miR-92a, allowing for the overall pro-angiogenic effect of miR-17∼92 expression. PMID:24520115

  15. MicroRNA miR-92a-1 biogenesis and mRNA targeting is modulated by a tertiary contact within the miR-17~92 microRNA cluster.

    PubMed

    Chaulk, Steven G; Xu, Zhizhong; Glover, Mark J N; Fahlman, Richard P

    2014-04-01

    While functional mature microRNAs (miRNAs) are small ∼22 base oligonucleotides that target specific mRNAs, miRNAs are initially expressed as long transcripts (pri-miRNAs) that undergo sequential processing to yield the mature miRNAs. We have previously reported that the pri-miR-17∼92 cluster adopts a compact globular folded structure that internalizes a 3' core domain resulting in reduced miRNA maturation and subsequent mRNA targeting. Using a site-specific photo-cross-linker we have identified a tertiary contact within the 3' core domain of the pri-miRNA between a non-miRNA stem-loop and the pre-miR-19b hairpin. This tertiary contact is involved in the formation of the compact globular fold of the cluster while its disruption enhances miR-92a expression and mRNA targeting. We propose that this tertiary contact serves as a molecular scaffold to restrict expression of the proposed antiangiogenic miR-92a, allowing for the overall pro-angiogenic effect of miR-17∼92 expression.

  16. 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

  17. Importance of the RNA secondary structure for the relative accumulation of clustered viral microRNAs

    PubMed Central

    Contrant, Maud; Fender, Aurélie; Chane-Woon-Ming, Béatrice; Randrianjafy, Ramy; Vivet-Boudou, Valérie; Richer, Delphine; Pfeffer, Sébastien

    2014-01-01

    Micro (mi)RNAs are small non-coding RNAs with key regulatory functions. Recent advances in the field allowed researchers to identify their targets. However, much less is known regarding the regulation of miRNAs themselves. The accumulation of these tiny regulators can be modulated at various levels during their biogenesis from the transcription of the primary transcript (pri-miRNA) to the stability of the mature miRNA. Here, we studied the importance of the pri-miRNA secondary structure for the regulation of mature miRNA accumulation. To this end, we used the Kaposi's sarcoma herpesvirus, which encodes a cluster of 12 pre-miRNAs. Using small RNA profiling and quantitative northern blot analysis, we measured the absolute amount of each mature miRNAs in different cellular context. We found that the difference in expression between the least and most expressed viral miRNAs could be as high as 60-fold. Using high-throughput selective 2′-hydroxyl acylation analyzed by primer extension, we then determined the secondary structure of the long primary transcript. We found that highly expressed miRNAs derived from optimally structured regions within the pri-miRNA. Finally, we confirmed the importance of the local structure by swapping stem-loops or by targeted mutagenesis of selected miRNAs, which resulted in a perturbed accumulation of the mature miRNA. PMID:24831544

  18. Genetic transformation of Bacopa monnieri by wild type strains of Agrobacterium rhizogenes stimulates production of bacopa saponins in transformed calli and plants.

    PubMed

    Majumdar, Sukanya; Garai, Saraswati; Jha, Sumita

    2011-05-01

    We have developed an efficient transformation system for Bacopa monnieri, an important Indian medicinal plant, using Agrobacterium rhizogenes strains LBA 9402 and A4. Transformed roots induced by strain LBA 9402 spontaneously dedifferentiated to callus while excised roots induced by strain A4 spontaneously showed induction of shoot buds within 10 days. PCR and RT-PCR analysis revealed the presence and expression of the rolAB and rolC genes at the transcription level in pRi A4 transformed cultures indicating that the TL-DNA was integrated retained and expressed in the A4-Ri transformed shoots. Transformed calli showed the presence of rolAB or rol A, TR and ags genes. Transformed plants showed morphological features typically seen in transgenic plants produced by A. rhizogenes. Growth and biomass accumulation was significantly higher in the transformed shoots (twofold) and roots (fourfold) than in the non-transformed (WT) plants. In pRi A4-transformed plants, the content of bacopasaponin D, bacopasaponin F, bacopaside II and bacopaside V was enhanced significantly as compared to WT plants of similar age while bacoside A3 and bacopasaponin C content was comparable with that of WT plants. Significant increase in content of five bacopa saponins could be detected in pRi 9402-transformed callus cultures. There is an overall stimulatory effect on accumulation of bacopa saponins in transformed plants and cells of B. monnieri establishing the role of endogenous elicitation by Ri T-DNA of A. rhizogenes.

  19. 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.

  20. Changes of White Matter Diffusion Anisotropy in Response to a 6-Week iPad Application-Based Occupational Therapy Intervention in Children with Surgically Treated Hydrocephalus: A Pilot Study.

    PubMed

    Yuan, Weihong; Harpster, Karen; Jones, Blaise V; Shimony, Joshua S; McKinstry, Robert C; Weckherlin, Nicole; Powell, Stephanie S; Barnard, Holly; Engsberg, Jack; Kadis, Darren S; Dodd, Jonathan; Altaye, Mekibib; Limbrick, David D; Holland, Scott K; Simpson, Sarah M; Bidwell, Sarah; Mangano, Francesco T

    2016-10-01

    Objective Our aims were (1) to test whether diffusion tensor imaging (DTI) could detect underlying white matter (WM) changes after a 6-week iPad application-based occupational therapy (OT) intervention in children with surgically treated hydrocephalus (HCP); and (2) to explore the association between WM changes and performance outcomes. Methods Five children (age range: 6.05-9.10 years) with surgically treated HCP completed an intensive iPad-based OT intervention targeting common domains of long-term deficits in children with HCP. The intervention included 6 weekly sessions in an OT clinic supplementing home-based program (1 hour/day, 4 days/week). DTI and neuropsychological assessments were performed before and after the intervention. Observation After the therapy, significant increases in fractional anisotropy (FA) and/or decreases in radial diffusivity were found in extensive WM areas. All participants demonstrated an increased perceptual reasoning index (PRI, Wechsler Abbreviated Scale of Intelligence: 2nd edition, PRI gains = 14.20 ± 7.56, p = 0.014). A significant positive correlation was found between PRI increase and the increase of FA in the right posterior limb of the internal capsule and the right external capsule (both p < 0.05). Conclusion This study provides initial evidence of DTI's sensitivity to detect subtle WM changes associated with performance improvements in response to a 6-week OT intervention in children with HCP.

  1. Changes of White Matter Diffusion Anisotropy in Response to a 6-week iPad Application-based Occupational Therapy Intervention in Children with Surgically Treated Hydrocephalus: a Pilot Study

    PubMed Central

    Yuan, Weihong; Harpster, Karen; Jones, Blaise V.; Shimony, Joshua S.; McKinstry, Robert C.; Weckherlin, Nicole; Powell, Stephanie S.; Barnard, Holly; Engsberg, Jack; Kadis, Darren S.; Dodd, Jonathan; Altaye, Mekibib; Limbrick, David D.; Holland, Scott K.; Simpson, Sarah M.; Bidwell, Sarah; Mangano, Francesco T.

    2016-01-01

    Our aims were (1) to test whether diffusion tensor imaging (DTI) could detect underlying white matter (WM) changes after a 6-week iPad application-based occupational therapy (OT) intervention in children with surgically treated hydrocephalus (HCP); and (2) to explore the association between WM changes and performance outcomes. Five children (age 6.05-9.10 yrs) with surgically treated HCP completed an intensive iPad-based OT intervention targeting common domains of long-term deficits in children with HCP. The intervention included 6 weekly sessions in an OT clinic supplementing home-based program (1 hour/day, 4 days/week). DTI and neuropsychological assessments were performed before and after the intervention. After the therapy, significant increases in fractional anisotropy (FA) and/or decreases in radial diffusivity (RD) were found in extensive WM areas. All participants demonstrated an increased Perceptual Reasoning Index (PRI, Wechsler Abbreviated Scale of Intelligence - Second Edition, PRI gains = 14.20±7.56, p=0.014). A significant positive correlation was found between PRI increase and the increase of FA in the right posterior limb of the internal capsule and the right external capsule (both p<0.05). This study provides initial evidence of DTI's sensitivity to detect subtle WM changes associated with performance improvements in response to a 6-week OT intervention in children with HCP. PMID:27438376

  2. The efficacy of bilateral balanced and canine guidance occlusal splints in the treatment of temporomandibular joint disorder.

    PubMed

    Al-Rafah, Eman M; Alammari, Manal R; Banasr, Fahad H

    2014-06-01

    Studies on the effects of stabilization splints on the neuromuscular system in patients with functional disorders indicate that the splints reestablish symmetric and reduced postural activity in the temporal and masseter muscles and significantly reduce the masseter muscle activity. This study was conducted on sixteen male dentulous patients who were suffering from subjective and objective signs of Temporomanbdibular Disorders (TMD). The patients were randomly divided into two groups, eight patients in each according to the fabrication of the occlusal design of the stabilization splint. All patients were subjected to clinical examination using Helkimo Dysfunction Index (HDI) and Pantographic examination through Pantographic Reproducibility Index (PRI) to assess the degree of TMD before and after splint therapy. The obtained results reported a significant improvement in the TMD symptoms as monitored by HDI scores and PRI scores in both groups after three months of using the different occlusal design stabilizing splint with Bilateral balanced and canine guidance stabilization splints during excursive movements. Also the results showed a significant and progressive improvement in the TMD symptoms between 3 weeks (p=0.08) and 3 months (p=0.001) after using the occlusal splint with canine guidance during excursive movements compared with bilateral balanced guidance as manifested by the coordination of mandibular movements by the pantographic tracings through Pantographic Reproducibility Index (PRI).

  3. The RNA-binding protein HOS5 and serine/arginine-rich proteins RS40 and RS41 participate in miRNA biogenesis in Arabidopsis.

    PubMed

    Chen, Tao; Cui, Peng; Xiong, Liming

    2015-09-30

    MicroRNAs are a class of small regulatory RNAs that are generated from primary miRNA (pri-miRNA) transcripts with a stem-loop structure. Accuracy of the processing of pri-miRNA into mature miRNA in plants can be enhanced by SERRATE (SE) and HYPONASTIC LEAVES 1 (HYL1). HYL1 activity is regulated by the FIERY2 (FRY2)/RNA polymerase II C-terminal domain phosphatase-like 1 (CPL1). Here, we discover that HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5) and two serine/arginine-rich splicing factors RS40 and RS41, previously shown to be involved in pre-mRNA splicing, affect the biogenesis of a subset of miRNA. These proteins are required for correct miRNA strand selection and the maintenance of miRNA levels. FRY2 dephosphorylates HOS5 whose phosphorylation status affects its subnuclear localization. HOS5 and the RS proteins bind both intronless and intron-containing pri-miRNAs. Importantly, all of these splicing-related factors directly interact with both HYL1 and SE in nuclear splicing speckles. Our results indicate that these splicing factors are directly involved in the biogenesis of a group of miRNA.

  4. Anticipating chromosomal replication fork arrest: SSB targets repair DNA helicases to active forks.

    PubMed

    Lecointe, François; Sérèna, Céline; Velten, Marion; Costes, Audrey; McGovern, Stephen; Meile, Jean-Christophe; Errington, Jeffrey; Ehrlich, S Dusko; Noirot, Philippe; Polard, Patrice

    2007-10-01

    In bacteria, several salvage responses to DNA replication arrest culminate in reassembly of the replisome on inactivated forks to resume replication. The PriA DNA helicase is a prominent trigger of this replication restart process, preceded in many cases by a repair and/or remodeling of the arrested fork, which can be performed by many specific proteins. The mechanisms that target these rescue effectors to damaged forks in the cell are unknown. We report that the single-stranded DNA binding (SSB) protein is the key factor that links PriA to active chromosomal replication forks in vivo. This targeting mechanism determines the efficiency by which PriA reaches its specific DNA-binding site in vitro and directs replication restart in vivo. The RecG and RecQ DNA helicases, which are involved in intricate replication reactivation pathways, also associate with the chromosomal replication forks by similarly interacting with SSB. These results identify SSB as a platform for linking a 'repair toolbox' with active replication forks, providing a first line of rescue responses to accidental arrest.

  5. 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

  6. The RNA-binding protein HOS5 and serine/arginine-rich proteins RS40 and RS41 participate in miRNA biogenesis in Arabidopsis

    PubMed Central

    Chen, Tao; Cui, Peng; Xiong, Liming

    2015-01-01

    MicroRNAs are a class of small regulatory RNAs that are generated from primary miRNA (pri-miRNA) transcripts with a stem-loop structure. Accuracy of the processing of pri-miRNA into mature miRNA in plants can be enhanced by SERRATE (SE) and HYPONASTIC LEAVES 1 (HYL1). HYL1 activity is regulated by the FIERY2 (FRY2)/RNA polymerase II C-terminal domain phosphatase-like 1 (CPL1). Here, we discover that HIGH OSMOTIC STRESS GENE EXPRESSION 5 (HOS5) and two serine/arginine-rich splicing factors RS40 and RS41, previously shown to be involved in pre-mRNA splicing, affect the biogenesis of a subset of miRNA. These proteins are required for correct miRNA strand selection and the maintenance of miRNA levels. FRY2 dephosphorylates HOS5 whose phosphorylation status affects its subnuclear localization. HOS5 and the RS proteins bind both intronless and intron-containing pri-miRNAs. Importantly, all of these splicing-related factors directly interact with both HYL1 and SE in nuclear splicing speckles. Our results indicate that these splicing factors are directly involved in the biogenesis of a group of miRNA. PMID:26227967

  7. Dipole strength in {sup 89}Y up to the neutron-separation energy

    SciTech Connect

    Benouaret, N.; Schwengner, R.; Rusev, G.; Doenau, F.; Beyer, R.; Erhard, M.; Junghans, A. R.; Kosev, K.; Nair, C.; Schilling, K. D.; Wagner, A.; Grosse, E.; Bendjaballah, N.

    2009-01-15

    Photoexcitation of the N=50 nucleus {sup 89}Y has been performed at the bremsstrahlung facility at the superconducting electron accelerator ELBE at electron energies of E{sub e}{sup kin}=9.5 and 13.2 MeV. About 250 levels up to the neutron-separation energy were identified. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. The photoabsorption cross section derived in this way up to the neutron-separation energy is combined with the photoabsorption cross section obtained from ({gamma}, n) data and provides information about the extension of the giant dipole resonance toward energies below the neutron-separation energy. An enhancement of E1 strength has been found in the range from about 6 to 11 MeV. The experimental photoabsorption cross sections of {sup 89}Y and of the neighboring N=50 isotones {sup 88}Sr and {sup 90}Zr are compared with predictions of the quasiparticle-random-phase approximation.

  8. Spin-isovector giant resonances induced by (n,p) reactions on heavy nuclei

    NASA Astrophysics Data System (ADS)

    Long, S. A.; Spicer, B. M.; Raywood, K. J.; Abegg, R.; Alford, W. P.; Celler, A.; Frekers, D.; Green, P. E.; Häusser, O.; Helmer, R. L.; Henderson, R. S.; Hicks, K. H.; Jackson, K. P.; Jeppesen, R. G.; King, N. S.; Miller, C. A.; Moinester, M. A.; Officer, V. C.; Shute, G. G.; Trudel, A.; Vetterli, M. C.; Yavin, A. I.; Yen, S.

    1998-06-01

    Double differential cross sections from the 120Sn(n,p)120In and 181Ta(n,p)181Hf reactions at 298 MeV and the 238U(n,p)238Pa reaction at 318 MeV have been measured for excitation energies up to 50 MeV in the residual nucleus. These data, together with the previously published data from the 90Zr(n,p)90Y and 208Pb(n,p)208Tl reactions at 198 MeV, have been analyzed for spin-isovector resonances of multipolarities less than 7, using the multipole decomposition method. The strengths due to spin-isovector excitations of multipolarity less than 4 have been extracted. The anomalous behavior of the extracted spin-isovector quadrupole strength with target mass number is discussed with reference to the calculations of Leonardi et al. The cross section due to quasifree processes was calculated and subtracted from the data. The data after this subtraction were reanalyzed for spin-isovector resonances and the strengths due to multipolarities up to 3 were extracted. The strengths due to spin-isovector dipole and octupole excitations were compared to values calculated, for 1ħω transitions only, using the sum rules of Macfarlane. The behavior with target mass number is well represented by these sum rules.

  9. 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.

  10. 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.

  11. 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.

  12. Optical properties of Tb3+-doped GeO2-ZrO2 thin films prepared by sol-gel method

    NASA Astrophysics Data System (ADS)

    Sanada, Tomoe; Abe, Masashi; Yamamoto, Kazuhiro; Wada, Noriyuki; Kojima, Kazuo

    2013-09-01

    Thin films of the system yTb2O3-xGeO2-(100-x)ZrO2 were prepared by sol-gel and dip-coating techniques, and their optical properties were investigated by measuring luminescence and excitation spectra, luminescence quantum yield (QY) values, and luminescence decay curves. The influences of crystallization and composition of the films on optical properties were also examined from X-ray diffraction patterns. In yTb2O3-xGeO2-(100-x)ZrO2 films with x = 0-10, the crystallization temperature showed a tendency to increase with increasing y and x values. Strong luminescence was observed both in amorphous or cubic ZrO2 films with y ⩾ 5 and x = 0 and in amorphous films with y ⩾ 5 and x = 5 or 10, and the strongest QY values were observed in yTb2O3-5GeO2-95ZrO2 and yTb2O3-10GeO2-90ZrO2 amorphous films heat treated at 400 or 500 °C.

  13. 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.

  14. 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.

  15. 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.

  16. Neutron activation diagnostics at the National Ignition Facility (invited)

    SciTech Connect

    Bleuel, D. L.; Yeamans, C. B.; Bernstein, L. A.; Bionta, R. M.; Caggiano, J. A.; Drury, O. B.; Hagmann, C. A.; Hatarik, R.; Knittel, K. M.; McNaney, J. M.; Moran, M.; Schneider, D. H. G.; Casey, D. T.; Frenje, J. A.; Johnson, M. Gatu; Cooper, G. W.; Knauer, J. P.; Leeper, R. J.; Ruiz, C. L.

    2012-10-15

    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 {sup 115}In(n,n'){sup 115m} In reaction. Outside the chamber, zirconium and copper are used to measure 14 MeV deuterium-tritium fusion neutrons via {sup 90}Zr(n,2n), {sup 63}Cu(n,2n), and {sup 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.

  17. Transfer couplings and hindrance far below the barrier for 40 Ca + 96 Zr

    DOE PAGES

    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

  18. 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

  19. 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

  20. Energy dependence of the nucleus-nucleus potential close to the Coulomb barrier

    SciTech Connect

    Washiyama, Kouhei; Lacroix, Denis

    2008-08-15

    The nucleus-nucleus interaction potentials in heavy-ion fusion reactions are extracted from the microscopic time-dependent Hartree-Fock theory for the mass symmetric reactions {sup 16}O + {sup 16}O, {sup 40}Ca + {sup 40}Ca, and {sup 48}Ca + {sup 48}Ca and the mass asymmetric reactions {sup 16}O + {sup 40,} {sup 48}Ca, {sup 40}Ca + {sup 48}Ca, {sup 16}O + {sup 208}Pb, and {sup 40}Ca + {sup 90}Zr. When the c.m. energy is much higher than the Coulomb barrier energy, potentials deduced with the microscopic theory identify with the frozen density approximation. As the c.m. energy decreases and approaches the Coulomb barrier, potentials become energy dependent. This dependence indicates dynamical reorganization of internal degrees of freedom and leads to a reduction of the 'apparent' barrier felt by the two nuclei during fusion of the order of 2-3% compared to the frozen density case. Several examples illustrate that the potential landscape changes rapidly when the c.m. energy is in the vicinity of the Coulomb barrier energy. The energy dependence is expected to have a significant role on fusion around the Coulomb barrier.

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. Measurement of isospin mixing at a finite temperature in 80Zr via giant dipole resonance decay

    NASA Astrophysics Data System (ADS)

    Corsi, A.; Wieland, O.; Barlini, S.; Bracco, A.; Camera, F.; Kravchuk, V. L.; Baiocco, G.; Bardelli, L.; Benzoni, G.; Bini, M.; Blasi, N.; Brambilla, S.; Bruno, M.; Casini, G.; Ciemala, M.; Cinausero, M.; Crespi, F. C. L.; D'Agostino, M.; Degerlier, M.; Giaz, A.; Gramegna, F.; Kmiecik, M.; Leoni, S.; Maj, A.; Marchi, T.; Mazurek, K.; Meczynski, W.; Million, B.; Montanari, D.; Morelli, L.; Myalski, S.; Nannini, A.; Nicolini, R.; Pasquali, G.; Poggi, G.; Vandone, V.; Vannini, G.

    2011-10-01

    Isospin mixing in the hot compound nucleus 80Zr was studied by measuring and comparing the γ-ray emission from the fusion reactions 40Ca+40Ca at Ebeam=200 MeV and 37Cl+44Ca at Ebeam=153 MeV. The γ yield associated with the giant dipole resonance is found to be different in the two reactions because, in self-conjugate nuclei, the E1 selection rules forbid the decay between states with isospin I=0. The degree of mixing is deduced from statistical-model analysis of the γ-ray spectrum emitted by the compound nucleus 80Zr with the standard parameters deduced from the γ decay of the nucleus 81Rb. The results are used to deduce the zero-temperature value, which is then compared with the latest predictions. The Coulomb spreading width is found to be independent of temperature.

  6. Experimental investigation of Ca isotopic fractionation during abiotic gypsum precipitation

    NASA Astrophysics Data System (ADS)

    Harouaka, K.; Eisenhauer, A.; Fantle, M. S.

    2012-12-01

    Experiments investigating Ca isotopic fractionation during gypsum precipitation were undertaken in order to elucidate the mechanisms and conditions that govern Ca isotopic fractionation during mineral precipitation. Both stirred and unstirred free drift gypsum precipitation experiments were conducted under controlled temperature conditions; precipitation kinetics were monitored by both a Ca ISE and EDTA titrations, while pH and temperature were measured using a pH electrode and an automatic temperature compensation probe, respectively. The initial ionic strength of all experiments was 0.6 M and the initial saturation states and Ca:SO4 ratios ranged from 4.7 to 1.6, and 3 to 0.33, respectively. The effective isotopic fractionation Δ44Ca, defined as δ44Cacrystal - δ44Casolution (where isotopic ratios were expressed relative to SRM-915a), of the experimental gypsum had a range of 1.43‰ (-2.25 to -0.82‰). The weight-averaged surface area normalized rates ranged from 3.7x10^4 to 1.6x10^2μmol/m^2/h. The crystal size and morphology, determined by SEM images, BET surface area and particle size measurements, correlated with the precipitation rates, where fast rates produced small (10-20 μm) platelet like crystals and slow rates produced large needle like crystals (>1000 μm). In general, the experiments demonstrated a negative dependence of Δ44Ca on precipitation rate, which agrees with the results of previous calcite precipitation experiments [1]. Moreover, the gypsum experiments exhibited a negative dependence of Δ4Ca on crystal size, such that small platelet like crystals were more isotopically fractionated (Δ4Ca~-2 ‰) than larger needle crystals (Δ44Ca~-1‰). Extended experiments were also carried out, where crystals from both stirred and unstirred reactors remained in solution after the apparent attainment of chemical equilibrium for an additional two weeks. These experiments suggest that small platelet crystals may re-equilibrate isotopically with the

  7. Isospin mixing at finite temperature in 80Zr

    NASA Astrophysics Data System (ADS)

    Corsi, A.; Bracco, A.; Camera, F.; Crespi, F. C. L.; Giaz, A.; Leoni, S.; Montanari, D.; Nicolini, R.; Vandone, V.; Wieland, O.; Benzoni, G.; Blasi, N.; Brambilla, S.; Million, B.; Kravchuk, V. L.; Cinausero, M.; Degerlier, M.; Gramegna, F.; Marchi, T.; Barlini, S.; Bardelli, L.; Bini, M.; Casini, G.; Nannini, A.; Pasquali, G.; Poggi, G.; Baiocco, G.; Bruno, M.; D'Agostino, M.; Morelli, L.; Vannini, G.; Ciemala, M.; Kmiecik, M.; Maj, A.; Mazurek, K.; Meczynski, W.; Myalski, S.

    2012-09-01

    The degree of isospin mixing in the hot compound nucleus 80Zr has been extracted by statistical-model analysis of the γ-decay spectrum emitted in fusion reactions 40Ca+40Ca at Ebeam = 200 MeV and 37Cl+44Ca at Ebeam = 153 MeV. In the case of 40Ca+40Ca reaction an hindrance of first-step γ-decay is expected because in self-conjugate nuclei the E1 selection rules forbid the decay between states with isospin I=0. The results obtained at finite temperature (T ~ 2 MeV) have been used to extrapolate the degree of mixing at zero temperature

  8. 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.

  9. Calcium-41 as a long-term biological tracer for bone resorption

    NASA Astrophysics Data System (ADS)

    Elmore, David; Bhattacharyya, Maryka H.; Sacco-Gibson, Nancy; Peterson, David P.

    1990-12-01

    The use of 41Ca (half-life 1 × 10 5 yr) as a tracer for studying calcium metabolism in living systems is compared to the shorter-lived radionuclides 45Ca (165 d) and 47Ca (45 d) and the stable isotopes 42Ca and 44Ca. The feasibility of using accelerator mass spectrometry (AMS) measurements of 41Ca for studying multi-year calcium resorption in humans was tested as part of a companion study that used 45Ca to measure the effects of dietary cadmium on calcium metabolism in dogs. It was shown that Ca resorbed from prelabeled bones correlates well with 45Ca for a period of 28 weeks. The advantage of 41Ca is that, even with a negligible radiation dose, it can be measured by AMS long after the 45Ca becomes unmeasurable.

  10. 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).

  11. Behaviour of Sr, Ca, Nd and Li Isotopes During Granite Weathering: the Margeride Massif, France

    NASA Astrophysics Data System (ADS)

    Negrel, P.; Bullen, T. D.; Millot, R.

    2008-12-01

    The Massif Central region of France contains numerous mineral water springs with salinities up to 6 g/L. These high salinities develop due to water-rock interaction processes accompanying weathering of granitic rocks such as the Margeride massif, a 5 km-deep laccolith having an age of 323 ± 12 Ma and consisting mainly of granitoid and gneiss. In order to better constrain weathering processes, we have determined the Sr, Nd, Ca and Li-isotope compositions of the Margeride granite, weathered granite (arene) and saprolite, sediment and soil overlying the granite, and groundwater samples (e.g., mineral water springs) associated with the massif. 87Sr/86Sr ratios increase in the order apatite-plagioclase-K-feldspar-arene- sediments and soils-biotite, and are well correlated with Rb/Sr ratios. Mineral waters have 87Sr/86Sr ratios similar to that of plagioclase, but have higher Rb/Sr ratios. 44Ca/40Ca ratios of plagioclase and apatite are similar to that of the whole rock, while those of K-feldspar and biotite are significantly less. 44Ca/40Ca ratios of arene, soil and sediment are similar to or less than that of K- feldspar, reflecting complete loss of Ca from plagioclase and apatite during weathering. In contrast, 44Ca/40Ca ratios for the mineral waters are similar to or substantially greater than that of plagioclase, reflecting extensive calcium carbonate precipitation during ascent of the waters along the rock fracture network. 44Ca/40Ca ratios of the waters are as much as 3.5 per mil greater than that of seawater, and thus contain the heaviest Ca yet reported for terrestrial materials. 7Li/6Li ratios differ by a few per mil among the granite minerals; of the weathering products, arene and soils have the least 7Li/6Li ratios, while river bank sediment and arene surface sediment have progressively greater ratios. 7Li/6Li ratios of the mineral waters have the greatest values, reflecting preferential retention of 6Li in the weathering products. 143Nd/144Nd ratios are

  12. 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.

  13. 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

  14. 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

  15. Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes.

    PubMed

    Santamaria-Fernandez, Rebeca; Wolff, Jean-Claude

    2010-07-30

    The potential of high-precision calcium and lead isotope ratio measurements using laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to aid distinction between four genuine and five counterfeit pharmaceutical packaging samples and further classification of counterfeit packaging samples has been evaluated. We highlight the lack of reference materials for LA-MC-ICP-MS isotope ratio measurements in solids. In this case the problem is minimised by using National Institute of Standards and Technology Standard Reference Material (NIST SRM) 915a calcium carbonate (as solid pellets) and NIST SRM610 glass disc for sample bracketing external standardisation. In addition, a new reference material, NIST SRM915b calcium carbonate, has been characterised in-house for Ca isotope ratios and is used as a reference sample. Significant differences have been found between genuine and counterfeit samples; the method allows detection of counterfeits and aids further classification of packaging samples. Typical expanded uncertainties for measured-corrected Ca isotope ratio values ((43)Ca/(44)Ca and (42)Ca/(44)Ca) were found to be below 0.06% (k = 2, 95% confidence) and below 0.2% for measured-corrected Pb isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb). This is the first time that Ca isotope ratios have been measured in packaging materials using LA coupled to a multicollector (MC)-ICP-MS instrument. The use of LA-MC-ICP-MS for direct measurement of Ca and Pb isotopic variations in cardboard/ink in packaging has definitive potential to aid counterfeit detection and classification. PMID:20552700

  16. Application of laser ablation multicollector inductively coupled plasma mass spectrometry for the measurement of calcium and lead isotope ratios in packaging for discriminatory purposes.

    PubMed

    Santamaria-Fernandez, Rebeca; Wolff, Jean-Claude

    2010-07-30

    The potential of high-precision calcium and lead isotope ratio measurements using laser ablation coupled to multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) to aid distinction between four genuine and five counterfeit pharmaceutical packaging samples and further classification of counterfeit packaging samples has been evaluated. We highlight the lack of reference materials for LA-MC-ICP-MS isotope ratio measurements in solids. In this case the problem is minimised by using National Institute of Standards and Technology Standard Reference Material (NIST SRM) 915a calcium carbonate (as solid pellets) and NIST SRM610 glass disc for sample bracketing external standardisation. In addition, a new reference material, NIST SRM915b calcium carbonate, has been characterised in-house for Ca isotope ratios and is used as a reference sample. Significant differences have been found between genuine and counterfeit samples; the method allows detection of counterfeits and aids further classification of packaging samples. Typical expanded uncertainties for measured-corrected Ca isotope ratio values ((43)Ca/(44)Ca and (42)Ca/(44)Ca) were found to be below 0.06% (k = 2, 95% confidence) and below 0.2% for measured-corrected Pb isotope ratios ((207)Pb/(206)Pb and (208)Pb/(206)Pb). This is the first time that Ca isotope ratios have been measured in packaging materials using LA coupled to a multicollector (MC)-ICP-MS instrument. The use of LA-MC-ICP-MS for direct measurement of Ca and Pb isotopic variations in cardboard/ink in packaging has definitive potential to aid counterfeit detection and classification.

  17. 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.

  18. A new approach on measuring calcium isotopic compositions using 42Ca-43Ca double spike on Triton-TIMS

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Zhu, H.; Liu, Y.; Zhu, J.; Kang, J.; Tan, D.; Liu, F.; Wang, G.

    2013-12-01

    Geochemical investigations on non-traditional stable calcium isotopic compositions of natural samples would greatly provide useful information on understanding the details in all kinds of geological processes, such as to trace the geological reservoirs, to reconstruct the calcium isotopic compositions of paleo sea water and to discover paleoclimate changes, etc. With the development of modern instruments and new chemical separation procedures, it is possible to accurately measure δ44Ca using double spike technique on TIMS/MC-ICP-MS nowadays; however, robust methods are quite few in China. Here we gave an evaluation on selecting the double spike pairs, the best mixture ratio of the two single spikes and made our own 42Ca-43Ca double spike; we also developed and improved new chemical procedures for separating Ca from different kinds of natural sample matrixes, and set up a method for running Ca on the Triton TIMS. Our results confirmed that the calcium fractionation during TIMS runs follows the exponential law. The best sample/spike mixture ratio range was also carefully calculated based on the double spike information and samples were spiked strictly to make it fall in this range. Based on our new approach, a set of standards including 915a, seawater and a couple of USGS standards were measured in our laboratory in China. Recent results show that δ44Ca of 915a, seawater, BHVO-1, BIR-1 and Nod-P-1 yield an average value -0.04×0.13 (2 std. dev.) (n=19), 1.88×0.10 (n=10), 0.82×0.06 (n=10), 0.81×0.13 (n=10) and 0.77×0.10 (n=10) respectively with a whole procedure blank usually ranges from 50-150ng. The data are similar to those in literatures. In addition, our chemical procedures could also be highly employed for separating Mg, Sr and Ba simultaneously from sample matrixes.

  19. 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.

  20. Isotope Anomalies in the Fe-group Elements in Meteorites and Connections to Nucleosynthesis in AGB Stars

    NASA Astrophysics Data System (ADS)

    Wasserburg, G. J.; Trippella, O.; Busso, M.

    2015-05-01

    We study the effects of neutron captures in AGB stars on “Fe-group” elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in 54Cr, 58Fe, and 64Ni in solar system materials, which are commonly attributed to supernovae (SNe). However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5 {{M}⊙ } and 3 {{M}⊙ } AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of 54Cr, 58Fe, and 64Ni, while the other isotopes are little altered; hence, the observations may be explained by AGB processing. The results are robust and not dependent on the detailed initial isotopic composition. Consequences for other “Fe group” elements are then explored. They include 50Ti excesses and some production of 46,47,49Ti. In many circumstellar condensates, Ti quantitatively reflects these effects of AGB neutron captures. Scatter in the data results from small variations (granularity) in the isotopic composition of the local ISM. For Si, the main effects are instead due to variations in the local ISM from different SN sources. The problem of Ca is discussed, particularly with regard to 48Ca. The measured data are usually represented assuming terrestrial values for 42Ca/44Ca. Materials processed in AGB stars or sources with variable initial 42Ca/44Ca ratios can give apparent 48Ca excesses/deficiencies, attributed to SNe. The broader issue of galactic chemical evolution is also discussed in view of the isotopic granularity in the ISM.

  1. Experimental study of the quasifission, fusion-fission, and de-excitation of Cf compound nuclei

    NASA Astrophysics Data System (ADS)

    Khuyagbaatar, J.; Hinde, D. J.; Carter, I. P.; Dasgupta, M.; Düllmann, Ch. E.; Evers, M.; Luong, D. H.; du Rietz, R.; Wakhle, A.; Williams, E.; Yakushev, A.

    2015-05-01

    Background: The fusion-evaporation reaction at energies around the Coulomb barrier is presently the only way to produce the heaviest elements. However, formation of evaporation residues is strongly hindered due to the competing fusion-fission and quasifission processes. Presently, a full understanding of these processes and their relationships has not been reached. Purpose: This work aims to use new fission measurements and existing evaporation residue and fission excitation function data for reactions forming Cf isotopes to investigate the dependence of the quasifission probability and characteristics on the identities of the two colliding nuclei in heavy element formation reactions. Method: Using the Australian National University's 14UD electrostatic accelerator and CUBE detector array, fission fragments from the 12C +235U , 34S +208Pb , 36S +206Pb , 36S +208Pb , and 44Ca +198Pt reactions were measured. Mass and angle distributions of fission fragments were extracted and compared to investigate the presence and characteristics of quasifission. Results: Mass-angle-correlated fission fragments were observed for the 44Ca +198Pt reaction; no correlation was observed in the other reactions measured. Flat-topped fission-fragment mass distributions were observed for 12C +235U at compound-nucleus excitation energies from 28 to 52 MeV. Less pronounced flat-topped distributions were observed, with very similar shapes, for all three sulfur-induced reactions at excitation energies lower than 45 MeV. Conclusions: A high probability of long-time-scale quasifission seems necessary to explain both the fission and evaporation residue data for the 34S +208Pb and 36S +206Pb reactions. Flat-topped mass distributions observed for 12C - and 34 ,36S -induced reactions are suggested to originate both from late-chance fusion-fission at low excitation energies and the persistence of shell effects at the higher energies associated with quasifission.

  2. Biological fractionation of stable Ca isotopes in Göttingen minipigs as a physiological model for Ca homeostasis in humans.

    PubMed

    Heuser, Alexander; Eisenhauer, Anton; Scholz-Ahrens, Katharina E; Schrezenmeir, Jürgen

    2016-12-01

    In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ(44/40)Ca = [((44)Ca/(40)Ca)sample/((44)Ca/(40)Ca)reference]-1) of diet, faeces, blood, bones and urine from Göttingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (-CaD). In contrast to Con and GIO whose average δ(44/40)Cafaeces values (0.39 ± 0.13‰ and 0.28 ± 0.08‰, respectively) tend to be lower than their diet (0.47 ± 0.02‰), δ(44/40)Cafaeces of -CaD (-0.27 ± 0.21‰) was significantly lower than their δ(44/40)Cadiet (0.37 ± 0.03‰), but also lower than δ(44/40)Cafaeces of Con and GIO. We suggest that the low δ(44/40)Cafaeces of -CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ(44/40)Cafaeces of Con and GIO. The δ(44/40)Caurine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Göttingen minipigs we found a Ca isotope fractionation between blood and bones (Δ(44/40)Cablood-bone) of 0.68 ± 0.15‰.

  3. Seasonal trends of spectral indexes for monitoring GPP in a Mediterranean cork oak savanna

    NASA Astrophysics Data System (ADS)

    Cerasoli, S.; Silva, J. M. N.; Carvalhais, N.; Silva, F.; López, G.; Pereira, J. M. C.; Pereira, J. S.

    2012-04-01

    It is nowadays clear that the inclusion of spectral indexes into biogeochemical models can greatly improve actual estimates of gross primary productivity (GPP) at local and global scale. Several vegetation indexes can be obtained by the reflectance of light at specific wavelengths. Among them, the Normalized Vegetation Index (NDVI), the Enhanced Vegetation Index (EVI) and the Photochemical Reflectance Index (PRI) were found suitable to represent different characteristics of ecosystems strictly related with GPP, such as biomass and photosynthetic capacity (NDVI, EVI) or radiation use efficiency (PRI). In Mediterranean cork oak savannas, characterized by high heterogeneity, the application of spectral indexes derived from coarse spatial resolution remotely sensed data (e.g. MODIS imagery) to represent the performance of the whole ecosystem is complex. A better knowledge of the variability of vegetation indexes for specific vegetation types, assessed in fieldwork, is fundamental to the interpretation of the same indexes obtained with satellite data and a key step through the integration of such indexes into biogeochemical models. We consider three different vegetation types: trees, grasses and shrubs, concurring to the overall ecosystem carbon budget in Mediterranean cork oak savannas. Since April 2011, reflectance measurements were performed in the range of 300-2500nm by the use of a handheld hyperspectral spectroradiometer (FieldSpec3, ASD Inc. CO, USA) in several species of the three vegetation types in a cork oak savanna eddy covariance site located in central Portugal. Measurements were always performed around solar noon and repeated approximately every two weeks. Several vegetation indexes were calculated. All indexes showed clear differences among vegetation types and among species. Marked seasonal trends were identified for grasses and shrubs, clearly related with the onset of dry summer conditions. Both NDVI and EVI decreased in grasses from April to the

  4. The nature of Earth's building materials as revealed by calcium isotopes

    NASA Astrophysics Data System (ADS)

    Valdes, M. C.; Moreira, M. A.; Boyet, M.; Foriel, J.; Moynier, F.

    2013-12-01

    Isotopic ratios have traditionally been used as tracers of the genetic link between meteorites and the Earth. Of the major primitive meteorite groups, enstatite chondrites (EC) are the most similar to Earth with regard to the isotopic composition of most elements (e.g. Javoy et al., 2010). In contrast to many isotope systems, calcium (Ca) exhibits significant mass-dependent variation between Earth and EC, though the magnitude of the difference is debated. Simon and DePaolo (2010) find a 0.4‰ difference between EC and Earth while Huang and Jacobsen (2012) find EC and Earth to be identical within error bars. Here we have developed a new method to resolve the difference in Ca isotopic composition at the 0.1 permil level. The method has been applied to a range of terrestrial and meteoritic samples, including seven EC, 12 carbonaceous chondrites (CC) representing most subgroups (CI, CV, CO, CM, CB, CR), six ordinary chondrites (OC), five lunar basalts, and six terrestrial rock standards. In addition, we measured 13 ocean island basalt (OIB) samples from a series of compositional ranges (EM1, EM2, HIMU) to better estimate the Ca isotopic composition of the mantle. Calcium was purified by a combination of Eichrom DGA and Sr-Spec resins and the isotope ratios 42Ca/44Ca and 43Ca/44Ca were measured by standard bracketing normalized to NIST SRM 915b in medium or high resolution on a Thermo-Fisher Neptune Plus MC-ICP-MS at Washington University in St. Louis. All data reported below follow a mass-dependent fractionation law with δ42/44Ca ≈ 2 × δ43/44Ca. As is convention in Ca isotope studies performed on TIMS, we present the data as δ44/40Ca (calculated as -2 × δ42/44Ca) and renormalize to SRM 915a. We find the δ44/40Ca value of NIST SRM 915b relative to SRM 915a to be 0.69 × 0.01 (2se), which is in excellent agreement with previously reported values. Our results show that geostandards are in good agreement with previous data (e.g. δ44CaBHVO-1 = 0.88 × 0.02‰, 2

  5. 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

  6. 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

  7. RNA-binding protein DUS16 plays an essential role in primary miRNA processing in the unicellular alga Chlamydomonas reinhardtii.

    PubMed

    Yamasaki, Tomohito; Onishi, Masayuki; Kim, Eun-Jeong; Cerutti, Heriberto; Ohama, Takeshi

    2016-09-20

    Canonical microRNAs (miRNAs) are embedded in duplexed stem-loops in long precursor transcripts and are excised by sequential cleavage by DICER nuclease(s). In this miRNA biogenesis pathway, dsRNA-binding proteins play important roles in animals and plants by assisting DICER. However, these RNA-binding proteins are poorly characterized in unicellular organisms. Here we report that a unique RNA-binding protein, Dull slicer-16 (DUS16), plays an essential role in processing of primary-miRNA (pri-miRNA) transcripts in the unicellular green alga Chlamydomonas reinhardtii In animals and plants, dsRNA-binding proteins involved in miRNA biogenesis harbor two or three dsRNA-binding domains (dsRBDs), whereas DUS16 contains one dsRBD and also an ssRNA-binding domain (RRM). The null mutant of DUS16 showed a drastic reduction in most miRNA species. Production of these miRNAs was complemented by expression of full-length DUS16, but the expression of RRM- or dsRBD-truncated DUS16 did not restore miRNA production. Furthermore, DUS16 is predominantly localized to the nucleus and associated with nascent (unspliced form) pri-miRNAs and the DICER-LIKE 3 protein. These results suggest that DUS16 recognizes pri-miRNA transcripts cotranscriptionally and promotes their processing into mature miRNAs as a component of a microprocessor complex. We propose that DUS16 is an essential factor for miRNA production in Chlamydomonas and, because DUS16 is functionally similar to the dsRNA-binding proteins involved in miRNA biogenesis in animals and land plants, our report provides insight into this mechanism in unicellular eukaryotes. PMID:27582463

  8. Pharmacodynamic effects of standard dose prasugrel versus high dose clopidogrel in non-diabetic obese patients with coronary artery disease.

    PubMed

    Darlington, Andrew; Tello-Montoliu, Antonio; Rollini, Fabiana; Ueno, Masafumi; Ferreiro, José Luis; Patel, Ronakkumar; Desai, Bhaloo; Guzman, Luis A; Bass, Theodore A; Angiolillo, Dominick J

    2014-02-01

    Increased body weight is independently associated with impaired clopidogrel pharmacodynamic (PD) response. Prasugrel has more potent PD effects compared with clopidogrel, although its PD effects in obese patients are unknown. The aim of this prospective, randomised, study was to compare the PD effects of standard-dose prasugrel [60 mg loading dose (LD)/10 mg daily maintenance dose (MD)] with high-dose clopidogrel (900 mg LD/150 mg daily MD) in non-diabetic obese [body mass index (BMI) ≥30 kg/m²] patients, with coronary artery disease (CAD) on aspirin therapy. PD assessments (baseline, 2 hours post-LD and 6 ± 2 days after MD) were conducted using four platelet function assays, and the platelet reactivity index (PRI) assessed by VASP was used for sample size estimation. A total of 42 patients with a BMI of 36.42 ± 5.6 kg/m² completed the study. There were no differences in baseline PD measures between groups. At 2 hours post-LD, prasugrel was associated with lower PRI compared with clopidogrel (24.3 ± 5.5 vs 58.7 ± 5.7, p≤0.001), with consistent findings for all assays. At one-week, PRI values on prasugrel MD were lower than clopidogrel MD without reaching statistical significance (34.7 ± 5.8 vs 42.9 ± 5.8, p=0.32), with consistent findings for all assays. Accordingly, rates of high on-treatment platelet reactivity were markedly reduced after prasugrel LD, but not after MD. In conclusion, in non-diabetic obese patients with CAD, standard prasugrel dosing achieved more potent PD effects than high-dose clopidogrel in the acute phase of treatment, but this was not sustained during maintenance phase treatment. Whether an intensified prasugrel regimen is required in obese patients warrants investigation.

  9. Influence of 3,4-dichloroaniline (3,4-DCA) on benthic invertebrates in indoor experimental streams.

    PubMed

    Schmitz, A; Nagel, R

    1995-02-01

    The influence of 3,4-dichloroaniline (3,4-DCA) on benthic invertebrates has been examined. Acute toxicity tests were carried out with the following species: Pristina longiseta, Aelosoma variegatum (Oligochaeta), Hydrozetes lacustris (Acarina), Planorbarius corneus, and Gyraulus albus (Planorbidae). LC50 values (96 hr) were obtained for Pri. longiseta (2.5 mg/liter) and for Hy. lacustris (4.7 mg/liter). For all other species ranges of toxicity (maximal concentration with 0% dead to minimum concentration with 100% dead) were determined. These ranges were 0.8-20 mg/liter 3,4-DCA for Pri. longiseta, 1.6-20 mg/liter, 3,4-DCA for Hy. lacustris, 10-20 mg/liter 3,4-DCA for G. albus, 50-100 mg/liter 3,4-DCA for Pl. corneus, and 10 mg/liter 3,4-DCA (maximal concentration with 0% dead; minimum concentration with 100% dead was not determined) for Ae. variegatum. In two experimental streams, the recolonization of benthic organisms into defined sample areas was studied. Therefore, a phase without chemical treatment was compared with a following exposure phase. Test concentrations were 0.2 and 1.4 mg/liter 3,4-DCA (nominal concentrations). Significant effects were the complete extinction of Pri. longiseta in 0.2 mg/liter 3,4-DCA within the first 3 weeks of exposure, as well as the reduction of immigrating individuals of another species of Pristina in both test concentrations, and of Hy. lacustris and Stentor sp. in 1.4 mg/liter 3,4-DCA.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7540538

  10. Analysis of Heme Iron Coordination in DGCR8: The Heme-Binding Component of the Microprocessor Complex.

    PubMed

    Girvan, Hazel M; Bradley, Justin M; Cheesman, Myles R; Kincaid, James R; Liu, Yilin; Czarnecki, Kazimierz; Fisher, Karl; Leys, David; Rigby, Stephen E J; Munro, Andrew W

    2016-09-13

    DGCR8 is the RNA-binding partner of the nuclease Drosha. Their complex (the "Microprocessor") is essential for processing of long, primary microRNAs (pri-miRNAs) in the nucleus. Binding of heme to DGCR8 is essential for pri-miRNA processing. On the basis of the split Soret ultraviolet-visible (UV-vis) spectrum of ferric DGCR8, bis-thiolate sulfur (cysteinate, Cys(-)) heme iron coordination of DGCR8 heme iron was proposed. We have characterized DGCR8 heme ligation using the Δ276 DGCR8 variant and combined electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), electron nuclear double resonance, resonance Raman, and electronic absorption spectroscopy. These studies indicate DGCR8 bis-Cys heme iron ligation, with conversion from bis-thiolate (Cys(-)/Cys(-)) axial coordination in ferric DGCR8 to bis-thiol (CysH/CysH) coordination in ferrous DGCR8. Pri-miRNA binding does not perturb ferric DGCR8's optical spectrum, consistent with the axial ligand environment being separated from the substrate-binding site. UV-vis absorption spectra of the Fe(II) and Fe(II)-CO forms indicate discrete species exhibiting peaks with absorption coefficients substantially larger than those for ferric DGCR8 and that previously reported for a ferrous form of DGCR8. Electron-nuclear double resonance spectroscopy data exclude histidine or water as axial ligands for ferric DGCR8 and favor bis-thiolate coordination in this form. UV-vis MCD and near-infrared MCD provide data consistent with this conclusion. UV-vis MCD data for ferrous DGCR8 reveal features consistent with bis-thiol heme iron coordination, and resonance Raman data for the ferrous-CO form are consistent with a thiol ligand trans to the CO. These studies support retention of DGCR8 cysteine coordination upon reduction, a conclusion distinct from those of previous studies of a different ferrous DGCR8 isoform.

  11. A heterotrimer model of the complete Microprocessor complex revealed by single-molecule subunit counting.

    PubMed

    Herbert, Kristina M; Sarkar, Susanta K; Mills, Maria; Delgado De la Herran, Hilda C; Neuman, Keir C; Steitz, Joan A

    2016-02-01

    During microRNA (miRNA) biogenesis, the Microprocessor complex (MC), composed minimally of Drosha, an RNaseIII enzyme, and DGCR8, a double-stranded RNA-binding protein, cleaves the primary-miRNA (pri-miRNA) to release the pre-miRNA stem-loop structure. Size-exclusion chromatography of the MC, isolated from mammalian cells, suggested multiple copies of one or both proteins in the complex. However, the exact stoichiometry was unknown. Initial experiments suggested that DGCR8 bound pri-miRNA substrates specifically, and given that Drosha could not be bound or cross-linked to RNA, a sequential model for binding was established in which DGCR8 bound first and recruited Drosha. Therefore, many laboratories have studied DGCR8 binding to RNA in the absence of Drosha and have shown that deletion constructs of DGCR8 can multimerize in the presence of RNA. More recently, it was demonstrated that Drosha can bind pri-miRNA substrates in the absence of DGCR8, casting doubt on the sequential model of binding. In the same study, using a single-molecule photobleaching assay, fluorescent protein-tagged deletion constructs of DGCR8 and Drosha assembled into a heterotrimeric complex on RNA, comprising two DGCR8 molecules and one Drosha molecule. To determine the stoichiometry of Drosha and DGCR8 within the MC in the absence of added RNA, we also used a single-molecule photobleaching assay and confirmed the heterotrimeric model of the human MC. We demonstrate that a heterotrimeric complex is likely preformed in the absence of RNA and exists even when full-length proteins are expressed and purified from human cells, and when hAGT-derived tags are used rather than fluorescent proteins.

  12. 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

  13. The complete nucleotide sequence of a plant root-inducing (Ri) plasmid indicates its chimeric structure and evolutionary relationship between tumor-inducing (Ti) and symbiotic (Sym) plasmids in Rhizobiaceae.

    PubMed

    Moriguchi, K; Maeda, Y; Satou, M; Hardayani, N S; Kataoka, M; Tanaka, N; Yoshida, K

    2001-03-30

    The Ri (root-inducing) plasmid in Agrobacterium rhizogenes and Ti (tumor-inducing) plasmid in Agrobacterium tumefaciens have provided the fundamental basis for the construction of plant vectors and transgenic plants. Recently, the determination of the first complete nucleotide sequence of the Ti plasmid (pTi-SAKURA) has been successful. To understand the general structure of these oncogenic T-DNA transfer plasmids, the whole nucleotide sequence of a mikimopine-type Ri plasmid, pRi1724, was analyzed. The plasmid is 217,594 bp in size, and has 173 open reading frames (ORFs) in total, which are asymmetrically distributed. Except for 27 ORFs, which are unknown, 173 ORFs were classified into 12 groups as follows: three for DNA replication, nine for plasmid modification, 22 for conjugation, 26 for virulence, 11 for T-DNA gene, 19 for mikimopine/mikimopine-lactam transport, ten for an unknown opine metabolism, seven for transcriptional regulator, five for sugar transport, five for glycerol metabolism, four for chemoreceptor and 32 for others. The elucidated chimeric structure of pRi1724 interestingly indicates that the evolution of Rhizobiaceae plasmids seems to have kept interactions among the plasmids; especially, the genes and elements for a conjugal transfer of pRi1724 had clearly closer kinship to those of a Sym (symbiotic) plasmid, pNGR234a in Rhizobium sp. than those of Ti plasmids. By using sequencing and Northern analysis, we examined the metabolic pathway and gene expression of mikimopine, which is probably an Ri-specific opine. PMID:11273700

  14. Fleecy amyloid deposits in the internal layers of the human entorhinal cortex are comprised of N-terminal truncated fragments of Abeta.

    PubMed

    Thal, D R; Sassin, I; Schultz, C; Haass, C; Braak, E; Braak, H

    1999-02-01

    The deposition of amyloid in the brain is a hallmark of Alzheimer disease (AD). Amyloid deposits consist of accumulations of beta-amyloid (Abeta), which is a 39-43 amino-acid peptide cleaved from the Abeta-protein precursor (APP). Another cleavage product of APP is the P3-peptide, which consists of the amino acids 17-42 of the Abeta-peptide. In order to study the deposition of N-terminal truncated forms of Abeta in the human entorhinal cortex, serial sections from 16 autopsy cases with AD-related pathology were immunostained with antibodies against Abeta1-40, Abeta1-42, Abeta17-23, and Abeta8-17, as well as with the Campbell-Switzer silver impregnation for amyloid. In the external entorhinal layers (pre-beta and pre-gamma), sharply delineated diffuse plaques were seen. They were labeled by silver impregnation and by all Abeta-antibodies used. By comparison, in the internal layers (pri-alpha, pri-beta, and pri-gamma) blurred, ill-defined clouds of amyloid existed, in addition to sharply delineated diffuse plaques. These clouds of amyloid were termed "fleecy amyloid." Immunohistochemically, fleecy amyloid was stained by Abeta17-23 and Abeta1-42 antibodies, but not with antibodies against Abeta8-17 and Abeta1-40. Using the Campbell-Switzer technique, the fleecy amyloid deposits were found to be fine argyrophilic amyloid fibrils. Thus, the internal entorhinal layers are susceptible to a distinct type of amyloid, namely fleecy amyloid. This fleecy amyloid obviously corresponds to N-terminal truncated fragments of Abeta1-42, probably representing the P3-peptide. These N-terminal truncated fragments of Abeta are capable of creating fine fibrillar "amyloid."

  15. Fleecy amyloid deposits in the internal layers of the human entorhinal cortex are comprised of N-terminal truncated fragments of Abeta.

    PubMed

    Thal, D R; Sassin, I; Schultz, C; Haass, C; Braak, E; Braak, H

    1999-02-01

    The deposition of amyloid in the brain is a hallmark of Alzheimer disease (AD). Amyloid deposits consist of accumulations of beta-amyloid (Abeta), which is a 39-43 amino-acid peptide cleaved from the Abeta-protein precursor (APP). Another cleavage product of APP is the P3-peptide, which consists of the amino acids 17-42 of the Abeta-peptide. In order to study the deposition of N-terminal truncated forms of Abeta in the human entorhinal cortex, serial sections from 16 autopsy cases with AD-related pathology were immunostained with antibodies against Abeta1-40, Abeta1-42, Abeta17-23, and Abeta8-17, as well as with the Campbell-Switzer silver impregnation for amyloid. In the external entorhinal layers (pre-beta and pre-gamma), sharply delineated diffuse plaques were seen. They were labeled by silver impregnation and by all Abeta-antibodies used. By comparison, in the internal layers (pri-alpha, pri-beta, and pri-gamma) blurred, ill-defined clouds of amyloid existed, in addition to sharply delineated diffuse plaques. These clouds of amyloid were termed "fleecy amyloid." Immunohistochemically, fleecy amyloid was stained by Abeta17-23 and Abeta1-42 antibodies, but not with antibodies against Abeta8-17 and Abeta1-40. Using the Campbell-Switzer technique, the fleecy amyloid deposits were found to be fine argyrophilic amyloid fibrils. Thus, the internal entorhinal layers are susceptible to a distinct type of amyloid, namely fleecy amyloid. This fleecy amyloid obviously corresponds to N-terminal truncated fragments of Abeta1-42, probably representing the P3-peptide. These N-terminal truncated fragments of Abeta are capable of creating fine fibrillar "amyloid." PMID:10029103

  16. 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.

  17. Arabidopsis RNA-binding Protein FCA Regulates MicroRNA172 Processing in Thermosensory Flowering*

    PubMed Central

    Jung, Jae-Hoon; Seo, Pil Joon; Ahn, Ji Hoon; Park, Chung-Mo

    2012-01-01

    Ambient temperature fluctuates diurnally and seasonally. It profoundly influences the timing of flowering in plants. The floral integrator FLOWERING LOCUS T (FT) mediates ambient temperature signals via the thermosensory pathway in Arabidopsis flowering. microRNA172 (miR172), which promotes flowering by inducing FT, also responds to changes in ambient temperature. However, it is largely unknown how miR172 integrates ambient temperature signals into the flowering genetic network. Here, we show that Arabidopsis RNA-binding protein FCA promotes the processing of primary microRNA172 transcripts (pri-miR172) in response to changes in ambient temperature. Ambient temperature regulates miR172 biogenesis primarily at the pri-miR172 processing step. miR172 abundance is elevated at 23 °C but not at 16 °C. miR172 accumulation at 23 °C requires functional FCA. FCA binds to the flanking sequences of the stem-loop within the pri-miR172 transcripts via the RNA recognition motif. FCA also binds to the primary transcripts of other temperature-responsive miRNAs, such as miR398 and miR399. Notably, levels of FCA mRNAs and proteins increase at 23 °C but remain low at 16 °C, supporting the role of FCA in temperature perception. Our data show that FCA regulation of miR172 processing is an early event in the thermosensory flowering pathway. We propose that the FCA-miR172 regulon provides an adaptive strategy that fine tunes the onset of flowering under fluctuating ambient temperature conditions. PMID:22431732

  18. 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

  19. 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

  20. RecG Directs DNA Synthesis during Double-Strand Break Repair.

    PubMed

    Azeroglu, Benura; Mawer, Julia S P; Cockram, Charlotte A; White, Martin A; Hasan, A M Mahedi; Filatenkova, Milana; Leach, David R F

    2016-02-01

    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.

  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.

  2. 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

  3. Co-sorption of ofloxacin and Cu(II) in soils before and after organic matter removal.

    PubMed

    Wu, Di; Li, Hao; Liao, Shaohua; Sun, Xiaolong; Peng, Hongbo; Zhang, Di; Pan, Bo

    2014-05-15

    Various mechanisms play roles simultaneously for antibiotic sorption on solid particles. Previous studies simply emphasized mechanisms that match the increased or decreased antibiotic sorption by metal ions, without a general concept including these diverse mechanisms in their co-sorption. We observed both increased and decreased OFL and Cu(II) sorption in their co-sorption system. The comparison of the sorption coefficients of primary adsorbate (Kd(pri)) and co-adsorbate (Kd(co)) suggested that enhanced sorption occurred at high Kd(pri) region (low primary adsorbate concentration). Competitive sorption was observed when Kd(pri) was decreased to a certain value depending on solid particle properties. We thus summarized that if the adsorbates were introduced with low concentrations, OFL (such as hydrophobic region in solid particles) and Cu(II) (such as inner-sphere complexation sites) occupied their unique high-energy sorption sites. Cu(II) complexed with the adsorbed OFL, and OFL bridged by the adsorbed Cu(II) promoted the sorption for both chemicals. With the increased concentrations, the adsorbates spread to some common sorption sites with low sorption energy, such as cation exchange and electrostatic attraction region. The overlapping of Cu(II) and OFL on these sorption sites resulted in competitive sorption at high concentrations. The previously reported apparently increased or decreased sorption in antibiotic-metal ion co-sorption system may be only a part of the whole picture. Extended study on the turning point of decreased and increased sorption relating to water chemistry conditions and solid particle properties will provide more useful information to predict antibiotic-metal ion co-sorption.

  4. 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

  5. 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.

  6. BDNF promotes connections of corticospinal neurons onto spared descending interneurons in spinal cord injured rats.

    PubMed

    Vavrek, R; Girgis, J; Tetzlaff, W; Hiebert, G W; Fouad, K

    2006-06-01

    Although regeneration of injured axons is inhibited within the adult CNS, moderate recovery can be found in patients and animals with incomplete spinal cord injury (SCI). This can be partly attributed to sprouting of spared and injured axons, rostral and caudal to the lesion, respectively. Recently, it has been reported that following a thoracic SCI such sprouting can result in indirect reconnections of the lesioned axons to caudal targets via propriospinal interneurons (PrI). Here, we attempted to further promote this spontaneous repair mechanism by applying the neurotrophic factor BDNF (brain-derived neurotrophic factor), in the vicinity of the cell bodies of lesioned corticospinal neurons or NT-3, intrathecally to the cervical spinal cord. We performed a dorsal over-hemisection at the thoracic spinal cord sparing only the left ventrolateral quadrant. This type of lesion did not promote sprouting of injured corticospinal axons or re-routing via commissural PrI. Also, in rats that received NT-3 at the cervical enlargement, no increase in sprouting was found. However, animals receiving BDNF at the cell bodies of lesioned corticospinal neurons showed a significant increase in collateral sprouting and in the number of contacts with PrI. This was not observed when BDNF was administered to unlesioned animals. Although no statistical difference in the horizontal ladder walking was found between the groups, the increase in collateral sprouting and in the number of contacts correlated with the functional recovery. Hence, cell body treatment can promote plasticity of the injured CNS and may be a valuable treatment approach in conjunction with local regeneration promoting strategies. PMID:16632552

  7. The design of a space-borne multispectral canopy lidar to estimate global carbon stock and gross primary productivity

    NASA Astrophysics Data System (ADS)

    Jack, Jim; Rumi, Emal; Henry, David; Woodhouse, Iain; Nichol, Caroline; Macdonald, Malcolm

    2011-11-01

    Understanding the dynamics of the global carbon cycle is one of the most challenging issues for the scientific community. The ability to measure the magnitude of terrestrial carbon sinks as well as monitoring the short and long term changes is vital for environmental decision making. Forests form a significant part of the terrestrial biosystem and understanding the global carbon cycle, Above Ground Biomass (AGB) and Gross Primary Productivity (GPP) are critical parameters. Current estimates of AGB and GPP are not adequate to support models of the global carbon cycle and more accurate estimates would improve predictions of the future and estimates of the likely behaviour of these sinks. Various vegetation indices have been proposed for the characterisation of forests including canopy height, canopy area, Normalised Difference Vegetation Index (NDVI) and Photochemical Reflectance Index (PRI). Both NDVI and PRI are obtained from a measure of reflectivity at specific wavelengths and have been estimated from passive measurements. The use of multi-spectral LiDAR to measure NDVI and PRI and their vertical distribution within the forest represents a significant improvement over current techniques. This paper describes an approach to the design of an advanced Multi- Spectral Canopy LiDAR, using four wavelengths for measuring the vertical profile of the canopy simultaneously. It is proposed that the instrument be placed on a satellite orbiting the Earth on a sun synchronous polar orbit to provide samples on a rectangular grid at an approximate separation of 1km with a suitable revisit frequency. The systems engineering concept design will be presented.

  8. 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 ) .

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Activation product safety in the ARIES-I reactor design

    SciTech Connect

    Herring, J.S. ); Sze, D.K. ); Wong, C.; Cheng, E.T. ); Grotz, S.P. )

    1990-01-01

    The ARIES design effort has sought to maximize the environmental and safety advantages of fusion through careful selection of materials and careful design. Three goals are that the reactor achieve inherent or passive safety, that no public evacuation plan be necessary and that the waste be disposable as 10CFR61 Class C waste. The ARIES-I reactor consists of a SiC composite structure for the first wall and blanket, cooled by 10 MPa He. The breeder is Li{sub 2}ZrO{sub 3}, although Li{sub 2}O and Li{sub 4}SiO{sub 4} were also considered. The divertor consists of SiC composite tubes coated with 2 mm of tungsten. Due to the minimal afterheat of this blanket design, LOCA calculations indicate maximum temperatures will not cause damage if the plasma is promptly extinguished. Two primary safety issues are the zirconium in the breeder and tungsten on the divertor. Li{sub 2}ZrO{sub 3} was chosen because of its demonstrated high-temperature stability. The other breeders have lower afterheat and activation. Use of zirconium in the breeder will necessitate isotopic tailoring to remove {sup 90}Zr and {sup 94}Zr. The 5.8 tonnes of W on the divertor would also have to be tailored to remove {sup 186}W and/or to concentrate {sup 183}W. Thus the ARIES-I design achieves the passive safety and low-level waste disposal criteria with respect to activation products. Development of low activation materials to replace zirconium and tungsten is needed to avoid requiring an evacuation plan.

  14. 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.

  15. 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.

  16. A design study for the analysis of 90Sr And 135,137Cs by ISA-AMS

    NASA Astrophysics Data System (ADS)

    Alary, Jean-François; Cousins, Lisa M.; Eliades, John; Hao, Changtong; Javahery, Gholamreza; Kieser, William E.; Litherland, Albert E.; Zhao, Xiaolei

    2013-04-01

    Extending the range of Accelerator Mass Spectrometry (AMS) to the fission products 90Sr and 135,137Cs would offer numerous advantages for non-proliferation surveillance activities. A new method for suppressing the interfering isobars 90Zr (and 90Y) and 135,137Ba using low kinetic energy (<20 eV) gas-phase reactions in an AMS injection line can help achieving this goal in a cost effective way [1]. The reactions occur in a radiofrequency quadrupole (RFQ) cell filled with a low pressure gas, part of a device known as the Isobar Separator for Anions (ISA). Combined with fluoridematrix assisted ionization, this method greatly improves the analytical capabilities of AMS for 90Sr and will enable the direct analysis of 135,137Cs below sub-parts per trillion levels. The ISA alone provides interference suppression factors of 4×10-6 for ZrF3-/SrF3- and 2×10-5 for BaF2-/CsF2-. The general performance improvement provided by the ISA, however, critically depends on the capacity of this device to transmit the wanted anions with a high efficiency and with a stable response to the natural variations of AMS targets. Based on recent SIMION-8.1 studies and on results of a parallel study on the attenuation of other anions, we have developed a pre-commercial design for the ISA. In this design, RFQ rods and split-flow turbo molecular pumps are configured to achieve full control of reaction time, ion energy and fragmentation pathways (chemical and kinetic reactions), and to improve beam transmission through the cell. The mechanical layout will be presented in 3D models using Solid Works; SIMION-8.1 simulations were used to illustrate the importance of optical matching of the RFQ and the front-end DC retardation section of the ISA.

  17. 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.

  18. 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.

  19. 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.

  20. Study of direct relationship between atomic structures and glass forming abilities of Cu100-x Zrx (0≤x≤10) liquids by molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Mattern, N.; Eckert, J.

    2012-03-01

    We have studied the phase formation of Cu100-xZrx liquids with x = 0, 0.5, 1, 2, 5, 10, and 25 using molecular dynamics simulations, respectively, in order to find a direct relationship between the atomic structures and the glass forming abilities (GFAs). The difference among the critical cooling rates has been identified by at least two orders of magnitude. We introduce a parameter based on the relative change in the factions of Voronoi polyhedra to evaluate the contributions of different clusters to the glass forming ability. Within the studied composition range, it is revealed that the contributions to glass forming ability obey Cu-centered <0 0 12 0> >Zr-centered <0 1 10 5> >Cu-centered <0 1 9 3> and <0 1 10 2>, whereas the Cu-centered <0 1 10 3>, <0 1 10 4>, <0 2 8 4>, <0 2 8 5> and Zr-centered <0 1 10 6> and <0 1 10 7> are not beneficial to GFA, although their absolute fractions also increase upon cooling. Higher degree of chemical short range order corresponds to better GFA in the Cu100-xZrx system for x ≤ 25. By studying the transport properties, it is found that Zr addition increases the atomic friction and viscosity of the Cu100-xZrx liquids. The viscosity of Cu90Zr10 liquid is twice of that of pure Cu at 900 K. The deviation from Einstein-Stokes relation corresponds to GFA very well, indicating that it is also a good indicator to evaluate the glass forming abilities.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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

  7. 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

  8. Neptunium and plutonium complexes with a sterically encumbered triamidoamine (TREN) scaffold

    DOE PAGES

    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.

  9. 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

  10. Deswelling of ultrathin molecular layer-by-layer polyamide water desalination membranes.

    PubMed

    Chan, Edwin P

    2014-05-01

    The selective layer of pressure-induced water desalination membranes is an ultrathin and highly crosslinked aromatic polyamide (PA) film that separates salt from water based on differences in permeability, which is a product of diffusivity and solubility. Characterizing the transport properties of the selective layer is necessary in understanding its permselective performance. However, measuring transport of ultrathin films in general is nontrivial. Here, Poroelastic Relaxation Indentation (PRI) is employed as a simple deswelling technique for measuring the transport properties of these ultrathin selective layers.

  11. Stabilization of a two-coordinate, acyclic diaminosilylene (ADASi): completion of the series of isolable diaminotetrylenes, :E(NR(2))(2) (E = group 14 element).

    PubMed

    Hadlington, Terrance J; Abdalla, Joseph A B; Tirfoin, Rémi; Aldridge, Simon; Jones, Cameron

    2016-01-28

    An extremely bulky boryl-amide ligand, [N(SiMe3){B(DAB)}](-) (TBoN; DAB = (DipNCH)2, Dip = C6H3Pr(i)2-2,6), has been utilised in the preparation of the first isolable, two-coordinate acyclic diaminosilylene (ADASi), viz. :Si(TBoN)2. This is shown to have a frontier orbital energy separation, and presumed level of reactivity, intermediate between those of the two classes of previously reported isolable two-coordinate, acyclic silylenes. PMID:26666776

  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. Privacy Preservation over Untrusted Mobile Networks

    NASA Astrophysics Data System (ADS)

    Ardagna, Claudio A.; Jajodia, Sushil; Samarati, Pierangela; Stavrou, Angelos

    The proliferation of mobile devices has given rise to novel user-centric applications and services. In current mobile systems, users gain access to remote servers over mobile network operators. These operators are typically assumed to be trusted and to manage the information they collect in a privacy-preserving way. Such information, however, is extremely sensitive and coveted by many companies, which may use it to improve their business. In this context, safeguarding the users’ privacy against the prying eyes of the network operators is an emerging requirement.

  14. In situ spectral measurements improve the efficiency of light use efficiency models to estimate gross primary productivity in Mediterranean cork oak woodland

    NASA Astrophysics Data System (ADS)

    Cerasoli, S.; Silva, J. M.; Carvalhais, N.; Correia, A.; Costa e Silva, F.; Pereira, J. S.

    2013-12-01

    The Light Use Efficiency (LUE) concept is usually applied to retrieve Gross Primary Productivity (GPP) estimates in models integrating spectral indexes, namely Normalized Difference Vegetation Index (NDVI) and Photochemical Reflectance Index (PRI), considered proxies of biophysical properties of vegetation. The integration of spectral measurements into LUE models can increase the robustness of GPP estimates by optimizing particular parameters of the model. NDVI and PRI are frequently obtained by broad band sensors on remote platforms at low spatial resolution (e.g. MODIS). In highly heterogeneous ecosystems such spectral information may not be representative of the dynamic response of the ecosystem to climate variables. In Mediterranean oak woodlands different plant functional types (PFT): trees canopy, shrubs and herbaceous layer, contribute to the overall Gross Primary Productivity (GPP). In situ spectral measurements can provide useful information on each PFT and its temporal variability. The objectives of this study were: i) to analyze the temporal variability of NDVI, PRI and others spectral indices for the three PFT, their response to climate variables and their relationship with biophysical properties of vegetation; ii) to optimize a LUE model integrating selected spectral indexes in which the contribution of each PFT to the overall GPP is estimated individually; iii) to compare the performance of disaggregated GPP estimates and lumped GPP estimates, evaluated against eddy covariance measurements. Ground measurements of vegetation reflectance were performed in a cork oak woodland located in Coruche, Portugal (39°8'N, 8°19'W) where carbon and water fluxes are continuously measured by eddy covariance. Between April 2011 and June 2013 reflectance measurements of the herbaceous layer, shrubs and trees canopy were acquired with a FieldSpec3 spectroradiometer (ASD Inc.) which provided data in the range of 350-2500nm. Measurements were repeated approximately on

  15. 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

  16. 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

  17. The influence of temperature and salinity on the Li/Ca and d7Li of inorganic and biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Marriott, C.; Staubwasser, M.; Crompton, R.; Henderson, G.

    2003-04-01

    Lithium is the sixth most abundant metal in the ocean. It is conservative with a residence time of around 1Ma and has two stable isotopes ^7Li and ^6Li that are not actively involved in biological processes. Isotopic fractionation is observed during incorporation into calcium carbonate but no previous work has systematically examined the controls on this fractionation. We have investigated Li incorporation and isotopic fraction in both inorganically precipitated calcite and coralline aragonite (1). In both cases there is an inverse correlation of Li concentration with temperature and no significant variation in isotopic fractionation. A decrease in D Li/Ca from 0.0092 to 0.0030 is seen over a temperature range of 5--30^oC, whilst an offset of approximately -8.5 ppm is seen in the δ^7Li ratio relative to the growth solution. The temperature dependence of Li/Ca has an increased sensitivity at low temperatures and might therefore be useful in examining changes in bottom water temperature. We are now investigating Li/Ca and δ^7Li of foraminifera. Previous work (2) has suggested little variability in Li/Ca with temperature, although this was for samples from warmer water where Li/Ca is not sensitive. In this study, Uvigerina are examined in a series of core top samples from the Arabian Sea with a depth range of 95--1800m and corresponding temperature range of 5--20^oC. A series of inorganic calcite samples have also been precipitated in order to examine the effect of salinity on Li/Ca, δ^7Li and δ44Ca over a salinity range of 10--50 psu. The distribution coefficient of Li shows a positive correlation with salinity over this range. δ^7Li and δ44Ca measurements for these samples are presently being analysed. (1) Marriott et al., 2002, GCA, 66, A485 (2) Delaney et al., 1985, GCA, 49, 1327

  18. 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

  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. 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

  1. Calcium Isotopes in Marine Sediments and Soils: Paleoceanography, Diagenesis, and Soil Processes

    NASA Astrophysics Data System (ADS)

    Depaolo, D. J.; Fantle, M. S.; Turchyn, A.; Ewing, S.; Yang, W.

    2007-12-01

    Calcium has 6 stable isotopes covering a wide mass range from 40 to 48. Because it is a critical component of the carbon cycle and a major constituent of common minerals like calcite, apatite, and gypsum, there is growing interest in understanding its stable isotope fractionation patterns in nature. The first work on Ca isotopes emphasized fractionation in food chains and in the formation of biogenic mineral matter in vertebrates. More recent studies have emphasized the fractionations observed in marine carbonate deposits, plants, and hydrological systems. Laboratory experiments show that Ca isotopes are fractionated during precipitation of calcite and aragonite from aqueous solution. Comparison with natural carbonate indicates that the fractionations are probably kinetic in origin although the exact mechanisms are not understood. There is little difference between the fractionation observed in inorganic and organic systems; precipitation rate (or solution oversaturation) seems to be the controlling factor, rather than temperature. One promising aspect of Ca isotopes is in their application to marine carbonate diagenesis. Especially when combined with studies of Sr, C, S, U, and O isotopes in deep sea sediments, Ca isotopes can give unique information on calcite dissolution and recrystallization rates. In a pure carbonate section from DSDP site 807A, Ca isotopes in pore fluids are found to differ greatly from seawater values and require that the equilibrium fractionation factor for 44Ca/40Ca between calcite and dissolved carbonate is almost exactly 1.0000. This fractionation corresponds to very slow calcite deposition rates at near-equilibrium conditions, implying that this fractionation factor may be generally applicable to diagenetic calcite precipitation, distinguishing it from biogenic precipitation, for which the factor is about 0.9985. This property can also be used to establish the dissolution rates of young carbonate sediments in the uppermost few meters of

  2. 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.

  3. Analysis of applied forces and electromyography of back and shoulders muscles when performing a simulated hand scaling task.

    PubMed

    Porter, William; Gallagher, Sean; Torma-Krajewski, Janet

    2010-05-01

    Hand scaling is a physically demanding task responsible for numerous overexertion injuries in underground mining. Scaling requires the miner to use a long pry bar to remove loose rock, reducing the likelihood of rock fall injuries. The experiments described in this article simulated "rib" scaling (scaling a mine wall) from an elevated bucket to examine force generation and electromyographic responses using two types of scaling bars (steel and fiberglass-reinforced aluminum) at five target heights ranging from floor level to 176 cm. Ten male and six female subjects were tested in separate experiments. Peak and average force applied at the scaling bar tip and normalized electromyography (EMG) of the left and right pairs of the deltoid and erectores spinae muscles were obtained. Work height significantly affected peak prying force during scaling activities with highest force capacity at the lower levels. Bar type did not affect force generation. However, use of the lighter fiberglass bar required significantly more muscle activity to achieve the same force. Results of these studies suggest that miners scale points on the rock face that are below their knees, and reposition the bucket as often as necessary to do so. PMID:19800050

  4. 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

  5. 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.

  6. 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.

  7. PmiRKB: a plant microRNA knowledge base

    PubMed Central

    Meng, Yijun; Gou, Lingfeng; Chen, Dijun; Mao, Chuanzao; Jin, Yongfeng; Wu, Ping; Chen, Ming

    2011-01-01

    MicroRNAs (miRNAs), one type of small RNAs (sRNAs) in plants, play an essential role in gene regulation. Several miRNA databases were established; however, successively generated new datasets need to be collected, organized and analyzed. To this end, we have constructed a plant miRNA knowledge base (PmiRKB) that provides four major functional modules. In the ‘SNP’ module, single nucleotide polymorphism (SNP) data of seven Arabidopsis (Arabidopsis thaliana) accessions and 21 rice (Oryza sativa) subspecies were collected to inspect the SNPs within pre-miRNAs (precursor microRNAs) and miRNA—target RNA duplexes. Depending on their locations, SNPs can affect the secondary structures of pre-miRNAs, or interactions between miRNAs and their targets. A second module, ‘Pri-miR’, can be used to investigate the tissue-specific, transcriptional contexts of pre- and pri-miRNAs (primary microRNAs), based on massively parallel signature sequencing data. The third module, ‘MiR–Tar’, was designed to validate thousands of miRNA—target pairs by using parallel analysis of RNA end (PARE) data. Correspondingly, the fourth module, ‘Self-reg’, also used PARE data to investigate the metabolism of miRNA precursors, including precursor processing and miRNA- or miRNA*-mediated self-regulation effects on their host precursors. PmiRKB can be freely accessed at http://bis.zju.edu.cn/pmirkb/. PMID:20719744

  8. Salt Stress Reveals a New Role for ARGONAUTE1 in miRNA Biogenesis at the Transcriptional and Posttranscriptional Levels1[OPEN

    PubMed Central

    Niedojadlo, Katarzyna; Niedojadlo, Janusz; Walczak, Weronika; Szweykowska-Kulinska, Zofia; Jarmolowski, Artur

    2016-01-01

    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

  9. Autoregulatory mechanisms controlling the microprocessor.

    PubMed

    Triboulet, Robinson; Gregory, Richard I

    2011-01-01

    The Microprocessor, comprising the ribonuclease Drosha and its essential cofactor, the double-stranded RNA-binding protein, DGCR8, is essential for the first step of the miRNA biogenesis pathway. It specifically cleaves double-stranded RNA within stem-loop structures of primary miRNA transcripts (pri-miRNAs) to generate precursor (pre-miRNA) intermediates. Pre-miRNAs are subsequently processed by Dicer to their mature ∼22 nt form. Thus, Microprocessor is essential for miRNA maturation, and pri-miRNA cleavage by this complex defines one end of the mature miRNA. Moreover, it is emerging that dysregulation of the Microprocessor is associated with various human diseases. It is therefore important to understand the mechanisms by which the expression of the subunits of the Microprocessor is regulated. Recent findings have uncovered a post-transcriptional mechanism that maintains the integrity of the Microprocessor. These studies revealed that the Microprocessor is involved in the processing of the messenger RNA (mRNA) that encodes DGCR8. This regulatory feedback loop, along with the reported role played by DGCR8 in the stabilization of Drosha protein, is part of a newly identified regulatory mechanism controlling Microprocessor activity.

  10. Autoregulatory mechanisms controlling the Microprocessor.

    PubMed

    Triboulet, Robinson; Gregory, Richard I

    2010-01-01

    The Microprocessor, comprising the ribonuclease Drosha and its essential cofactor, the double-stranded RNA-binding protein, DGCR8, is essential for the first step of the miRNA biogenesis pathway. It specifically cleaves double-stranded RNA within stem-loop structures of primary miRNA transcripts (pri-miRNAs) to generate precursor (pre-miRNA) intermediates. Pre-miRNAs are subsequently processed by Dicer to their mature 22 nt form. Thus, Microprocessor is essential for miRNA maturation, and pri-miRNA cleavage by this complex defines one end of the mature miRNA. Moreover, it is emerging that dysregulation of the Microprocessor is associated with various human diseases. It is therefore important to understand the mechanisms by which the expression of the subunits of the Microprocessor is regulated. Recent findings have uncovered a post-transcriptional mechanism that maintains the integrity of the Microprocessor. These studies revealed that the Microprocessor is involved in the processing of the messenger RNA (mRNA) that encodes DGCR8. This regulatory feedback loop, along with the reported role played by DGCR8 in the stabilization of Drosha protein, is part ofa newly identified regulatory mechanism controlling Microprocessor activity.

  11. Functional Anatomy of the Human Microprocessor.

    PubMed

    Nguyen, Tuan Anh; Jo, Myung Hyun; Choi, Yeon-Gil; Park, Joha; Kwon, S Chul; Hohng, Sungchul; Kim, V Narry; Woo, Jae-Sung

    2015-06-01

    MicroRNA (miRNA) maturation is initiated by Microprocessor composed of RNase III DROSHA and its cofactor DGCR8, whose fidelity is critical for generation of functional miRNAs. To understand how Microprocessor recognizes pri-miRNAs, we here reconstitute human Microprocessor with purified recombinant proteins. We find that Microprocessor is an ∼364 kDa heterotrimeric complex of one DROSHA and two DGCR8 molecules. Together with a 23-amino acid peptide from DGCR8, DROSHA constitutes a minimal functional core. DROSHA serves as a "ruler" by measuring 11 bp from the basal ssRNA-dsRNA junction. DGCR8 interacts with the stem and apical elements through its dsRNA-binding domains and RNA-binding heme domain, respectively, allowing efficient and accurate processing. DROSHA and DGCR8, respectively, recognize the basal UG and apical UGU motifs, which ensure proper orientation of the complex. These findings clarify controversies over the action mechanism of DROSHA and allow us to build a general model for pri-miRNA processing.

  12. Cross talk between spliceosome and microprocessor defines the fate of pre-mRNA.

    PubMed

    Mattioli, Chiara; Pianigiani, Giulia; Pagani, Franco

    2014-01-01

    The spliceosome and the microprocessor complex (MPC) are two important processing machineries that act on precursor (pre)-mRNA. Both cleave the pre-mRNA to generate spliced mature transcripts and microRNAs (miRNAs), respectively. While spliceosomes identify in a complex manner correct splice sites, MPCs typically target RNA hairpins (pri-miRNA hairpins). In addition, pre-mRNA transcripts can contain pri-miRNA-like hairpins that are cleaved by the MPC without generating miRNAs. Recent evidence indicates that the position of hairpins on pre-mRNA, their distance from splice sites, and the relative efficiency of cropping and splicing contribute to determine the fate of a pre-mRNA. Depending on these factors, a pre-mRNA can be preferentially used to generate a miRNA, a constitutively or even an alternative spliced transcript. For example, competition between splicing and cropping on splice-site-overlapping miRNAs (SO miRNAs) results in alternative spliced isoforms and influences miRNA biogenesis. In several cases, the outcome of a pre-mRNA transcript and its final handling as miRNA or mRNA substrate can be frequently closely connected to the functional relationships between diverse pre-mRNA processing events. These events are influenced by both gene context and physiopathological conditions.

  13. Transcriptionally and post-transcriptionally regulated microRNAs in heat stress response in barley.

    PubMed

    Kruszka, Katarzyna; Pacak, Andrzej; Swida-Barteczka, Aleksandra; Nuc, Przemyslaw; Alaba, Sylwia; Wroblewska, Zuzanna; Karlowski, Wojciech; Jarmolowski, Artur; Szweykowska-Kulinska, Zofia

    2014-11-01

    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.

  14. Arabidopsis microRNA expression regulation in a wide range of abiotic stress responses.

    PubMed

    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.

  15. 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

  16. Hyperspectral Study of the Arctic Tundra Ecosystem Using an Automated Robotic Cart System

    NASA Astrophysics Data System (ADS)

    Goswami, S.; Gamon, J. A.; Houser, P.; Matharasi, K.; Tweedie, C. E.

    2007-12-01

    Our study in the NSF Biocomplexity project is carried on by collecting spectral data with the help of an automated robotic tram system over the drying arctic lake bed. The robotic cart samples three 300 meter long transects spread across the lake basin automatically, taking reflectance measurements at each meter using a dual detector spectrometer designed to correct for changing sky conditions. Surface reflectance data were collected for three consecutive years for 2005, 2006 and 2007 as part of the project, which provides a baseline dataset of surface conditions. Three spectral indices, Normalized Difference Vegetation Index (NDVI), a measure of vegetation 'greenness', the Photochemical Reflectance Index (PRI), a measure of carotenoid pigment levels, and the Water Band Index (WBI), a measure of vegetation moisture content, are calculated from the optical data collected to study the surface conditions of the lakebed. Comparison of three years NDVI data showed different greenness conditions of the surface. Peak season NDVI values were the lowest in 2005 compared to 2006 and 2007. WBI values for the two dry years 2005 and 2007 were similar for all the tramlines except for the beginning of the season. PRI values for the two dry years 2005 and 2007 had similar trends for all the tramlines except for the beginning of the season. This tram system along with the cyberinfrastucture tools that we are developing gives us the opportunity for developing a technology to the next level to facilitate the research in the field of environmental science and terrestrial ecology.

  17. 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

  18. 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.

  19. 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

  20. Problems following hippocampal irradiation in interventional radiologists - doses and potential effects: a Monte Carlo simulation.

    PubMed

    Chumak, V; Morgun, A; Bakhanova, E; Loganovsky, K; Loganovska, T; Marazziti, D

    2015-12-01

    Metoiu doslidzhennia bulo vyvchyty zakonomirnosti formuvannia doz na gipokamp v umovakh roboty likaria inter ventsiynogo kardiologa u rentgen operatsiyniy metodom Monte Karlo, a takozh vstanovyty Ikhniy zv’iazok z efek tyvnoiu dozoiu (shcho vykorystovuiet'sia u radiatsiynomu zakhysti) ta pokazanniamy indyvidual'nykh dozymetriv, shchob otsinyty ymovirnist' dosiagnennia protiagom kar’iery rivnia dozy, pry iakomu mozhut' sposterigatysia taki radiatsiyni efekty, iak kognityvni porushennia ta inshi nervovo psykhichni rozlady.Materialy i metody: modeliuvannia metodom Monte Karlo doz oprominennia gipokampiv likaria za dopomogoiu gibrydnogo voksel'no matematychnogo fantoma dlia typovykh angiografichnykh proektsiy ta energetychnykh spektriv, vlastyvykh dlia protsedur interventsiynoI kardiologiI.Rezul'taty: pokazano, shcho oprominennia golovy ie syl'no neodnoridnym i zalezhyt' vid rentgenografichnoI pro ektsiI: vidminnist' doz oprominennia livogo ta pravogo gipokampa mozhe stanovyty do dvokh z polovynoiu raziv, za pevnykh umov doza u livomu gipokampi mozhe vdvichi perevyshchuvaty efektyvnu dozu, iaku otsiniuvaly za poshyrenym algorytmom podviynoI dozymetriI.Vysnovky: dozy na gipokamp protiagom stazhu profesiynogo oprominennia mozhut' siagaty velychyn, pry iakykh mo zhut' z’iavytysia kognityvni ta emotsiyno povedinkovi porushennia, tomu glyboke vyvchennia efektiv oprominennia mozku pratsivnykiv interventsiynoI radiologiI ie vkray neobkhidnym.

  1. 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.

  2. An Improved Comprehensive Model for the Apparent Viscosity of Blood

    NASA Astrophysics Data System (ADS)

    Jacobitz, Frank; Anderson, Spencer

    2008-11-01

    An improved comprehensive model for the apparent viscosity of blood is developed and used in simulations of the microcirculation in capillary bundles of rat spinotrapezius muscle fascia. In the microcirculation, the apparent viscosity of blood depends on the local vessel diameter, hematocrit, and shear rate. The proposed comprehensive model extends the apparent viscosity model developed by Pries, Secomb, Gaehtgens, and Gross (Circulation Research, 67, 826-834, 1990), which describes the effect of vessel diameter and hematocrit on the apparent viscosity. A shear thinning term is developed using the experimental data of Lipowsky, Usami, and Chien (Microvascular Research, 19, 297-319, 1980). Curve fits of this data can be combined with equations given in the Pries et al. work to create a system of equations that can be used to find the shear thinning factor. The simulations based on the improved apparent viscosity model use realistic vessel topology for the microvasculature, reconstructed from microscope images of tissue samples, and consider passive and active vessel properties. The numerical method is based on a Hagen-Poiseuille balance in the microvessels and a sparse matrix solver is used to obtain the solution. It was found that the inclusion of the shear factor decreases the overall flowrate in the capillary bundle. Many vessel connections in the fascia are characterized by relatively low shear rates and therefore increased apparent viscosity.

  3. A response regulator promotes Francisella tularensis intramacrophage growth by repressing an anti-virulence factor.

    PubMed

    Ramsey, Kathryn M; Dove, Simon L

    2016-08-01

    The orphan response regulator PmrA is essential for the intramacrophage growth and survival of Francisella tularensis. PmrA was thought to promote intramacrophage growth by binding directly to promoters on the Francisella Pathogenicity Island (FPI) and positively regulating the expression of FPI genes, which encode a Type VI secretion system required for intramacrophage growth. Using both ChIP-Seq and RNA-Seq we identify those regions of the F. tularensis chromosome occupied by PmrA and those genes that are regulated by PmrA. We find that PmrA associates with 252 distinct regions of the F. tularensis chromosome, but exerts regulatory effects at only a few of these locations. Rather than by functioning directly as an activator of FPI gene expression we present evidence that PmrA promotes intramacrophage growth by repressing the expression of a single target gene we refer to as priM (PmrA-repressed inhibitor of intramacrophage growth). Our findings thus indicate that the role of PmrA in facilitating intracellular growth is to repress a previously unknown anti-virulence factor. PriM is the first bacterially encoded factor to be described that can interfere with the intramacrophage growth and survival of F. tularensis. PMID:27169554

  4. 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

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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.

  10. Spatial and temporal variability of canopy GPP within a flux tower footprint

    NASA Astrophysics Data System (ADS)

    Garrity, S. R.; Vierling, L. A.

    2009-12-01

    Gross Primary Productivity (GPP) of plant canopies is strongly related to absorbed photosynthetically active radiation (APAR) and thus canopy structure. Short term canopy GPP responds to variable environmental conditions through alterations in the efficiency with which APAR is used to assimilate carbon and is thus also dependent on accessory pigment ratios and pool sizes. We used spatially distributed measurements of whole canopy transmitted radiation to better understand diurnal and seasonal dynamics of GPP within a flux tower footprint. Our instruments measured transmitted radiation in the Normalized Difference Vegetation Index (NDVI) and Photochemical Reflectance Index (PRI) wavelengths. These measurements served as proxies for canopy structure, short term changes in radiation use efficiency (RUE) and longer term changes in pools of photosynthetically important pigments. We found that aggregated measurements of PRI were related to total canopy RUE at both diurnal and seasonal time scales with the highest correlations occurring during periods when light-related stress was greatest. Diurnal and seasonal variability among spatially distributed measurements was in part explained by species composition and canopy structure. At the seasonal time scale we found evidence that suggested the ratios of photosynthetic pigments were related to canopy development and were important for explaining variability in the relationship between APAR and GPP across the growing season.

  11. 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

  12. 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

  13. 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

  14. Spontaneous and cisplatin-induced recombination in Escherichia coli.

    PubMed

    Nowosielska, Anetta; Calmann, Melissa A; Zdraveski, Zoran; Essigmann, John M; Marinus, M G

    2004-07-01

    To measure cisplatin (cis-diaminodichloroplatinum(II))-induced recombination, we have used a qualitative intrachromosomal assay utilizing duplicate inactive lac operons containing non-overlapping deletions and selection for Lac+ recombinants. The two operons are separated by one Mb and conversion of one of them yields the Lac+ phenotype. Lac+ formation for both spontaneous and cisplatin-induced recombination requires the products of the recA, recBC, ruvA, ruvB, ruvC, priA and polA genes. Inactivation of the recF, recO, recR and recJ genes decreased cisplatin-induced, but not spontaneous, recombination. The dependence on PriA and RecBC suggests that recombination is induced following stalling or collapse of replication forks at DNA lesions to form double strand breaks. The lack of recombination induction by trans-DDP suggests that the recombinogenic lesions for cisplatin are purine-purine intrastrand crosslinks. PMID:15177181

  15. 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

  16. 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

  17. 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

  18. 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.

  19. 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

  20. Sustained inhibition of hepatitis B virus replication in vivo using RNAi-activating lentiviruses.

    PubMed

    Ivacik, D; Ely, A; Ferry, N; Arbuthnot, P

    2015-02-01

    Chronic infection with hepatitis B virus (HBV) puts individuals at high risk for complicating cirrhosis and liver cancer, but available treatment to counter the virus rarely eliminates infection. Although harnessing RNA interference (RNAi) to silence HBV genes has shown the potential, achieving efficient and durable silencing of viral genes remains an important goal. Here we report on the propagation of lentiviral vectors (LVs) that successfully deliver HBV-targeting RNAi activators to liver cells. Mono- and tricistronic artificial primary microRNAs (pri-miRs) derived from pri-miR-31, placed under transcriptional control of the liver-specific modified murine transthyretin (mTTR) promoter, caused efficient inhibition of HBV replication markers. The tricistronic cassette was capable of silencing a mutant viral target and the effects were observed without disrupting the function of an endogenous miR (miR-16). The mTTR promoter stably expressed a reporter transgene in mouse livers over a study period of 1 year. Good silencing of HBV genes, without evidence of toxicity, was demonstrated following intravenous injection of LVs into neonatal HBV transgenic mice. Collectively, these data indicate that LVs may achieve sustained inhibition of HBV replication that is appealing for their therapeutic use.