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Sample records for active lone pairs

  1. Ligand Lone-Pair Influence on Hydrocarbon C-H Activation. A Computational Perspective

    SciTech Connect

    Ess, Daniel H.; Gunnoe, T. Brent; Cundari, Thomas R.; Goddard, William A.; Periana, Roy A.

    2010-12-03

    Mid to late transition metal complexes that break hydrocarbon C-H bonds by transferring the hydrogen to a heteroatom ligand while forming a metal-alkyl bond offer a promising strategy for C-H activation. Here we report a density functional (B3LYP, M06, and X3LYP) analysis of cis-(acac)2MX and TpM(L)X (M = Ir, Ru, Os, and Rh; acac = acetylacetonate, Tp = tris(pyrazolyl)borate; X = CH3, OH, OMe, NH2, and NMe2) systems for methane C-H bond activation reaction kinetics and thermodynamics. We address the importance of whether a ligand lone pair provides an intrinsic kinetic advantage through possible electronic dπ-pπ repulsions for M-OR and M-NR2 systems versus M-CH3 systems. This involves understanding the energetic impact of the X ligand group on ligand loss, C-H bond coordination, and C-H bond cleavage steps as well as understanding how the nucleophilicity of the ligand X group, the electrophilicity of the transition metal center, and cis-ligand stabilization effect influence each of these steps. We also explore how spectator ligands and second- versus third-row transition metal centers impact the energetics of each of these C-H activation steps.

  2. Bournonite PbCuSbS3 : Stereochemically Active Lone-Pair Electrons that Induce Low Thermal Conductivity.

    PubMed

    Dong, Yongkwan; Khabibullin, Artem R; Wei, Kaya; Salvador, James R; Nolas, George S; Woods, Lilia M

    2015-10-26

    An understanding of the structural features and bonding of a particular material, and the properties these features impart on its physical characteristics, is essential in the search for new systems that are of technological interest. For several relevant applications, the design or discovery of low thermal conductivity materials is of great importance. We report on the synthesis, crystal structure, thermal conductivity, and electronic-structure calculations of one such material, PbCuSbS3 . Our analysis is presented in terms of a comparative study with Sb2 S3 , from which PbCuSbS3 can be derived through cation substitution. The measured low thermal conductivity of PbCuSbS3 is explained by the distortive environment of the Pb and Sb atoms from the stereochemically active lone-pair s(2) electrons and their pronounced repulsive interaction. Our investigation suggests a general approach for the design of materials for phase-change-memory, thermal-barrier, thermal-rectification and thermoelectric applications, as well as other functions for which low thermal conductivity is purposefully sought.

  3. Orientational Ordering, Tilting and Lone-pair Activity in the Perovskite Methylammonium Tin Bromide, CH3NH3SnBr3

    SciTech Connect

    Swainson, I.; Chi, L; Her, J; Cranswick, L; Stephens, P; Winkler, B; Wilson, D; Milman, V

    2010-01-01

    Synchrotron powder diffraction data from methylammonium tin bromide, CH{sub 3}NH{sub 3}SnBr{sub 3}, taken as a function of temperature, reveal the existence of a phase between 230 and 188 K crystallizing in Pmc2{sub 1}, a = 5.8941 (2), b = 8.3862 (2), c = 8.2406 (2) {angstrom}. Strong ferroelectric distortions of the octahedra, associated with stereochemical activity of the Sn 5s{sup 2} lone pair, are evident. A group analysis and decomposition of the distortion modes of the inorganic framework with respect to the cubic parent is given. The primary order parameters driving this upper transition appear to be an in-phase tilt (rotation) of the octahedra coupled to a ferroelectric mode. The precise nature of the lower-temperature phase remains uncertain, although it appears likely to be triclinic. Density-functional theory calculations on such a triclinic cell suggest that directional bonding of the amine group to the halide cage is coupled to the stereochemical activity of the Sn lone pair via the Br atoms, i.e. that the bonding from the organic component may have a strong effect on the inorganic sublattice (principally via switching the direction of the lone pair with little to no energy cost).

  4. Hybrid germanium iodide perovskite semiconductors: active lone pairs, structural distortions, direct and indirect energy gaps, and strong nonlinear optical properties.

    PubMed

    Stoumpos, Constantinos C; Frazer, Laszlo; Clark, Daniel J; Kim, Yong Soo; Rhim, Sonny H; Freeman, Arthur J; Ketterson, John B; Jang, Joon I; Kanatzidis, Mercouri G

    2015-06-03

    The synthesis and properties of the hybrid organic/inorganic germanium perovskite compounds, AGeI3, are reported (A = Cs, organic cation). The systematic study of this reaction system led to the isolation of 6 new hybrid semiconductors. Using CsGeI3 (1) as the prototype compound, we have prepared methylammonium, CH3NH3GeI3 (2), formamidinium, HC(NH2)2GeI3 (3), acetamidinium, CH3C(NH2)2GeI3 (4), guanidinium, C(NH2)3GeI3 (5), trimethylammonium, (CH3)3NHGeI3 (6), and isopropylammonium, (CH3)2C(H)NH3GeI3 (7) analogues. The crystal structures of the compounds are classified based on their dimensionality with 1–4 forming 3D perovskite frameworks and 5–7 1D infinite chains. Compounds 1–7, with the exception of compounds 5 (centrosymmetric) and 7 (nonpolar acentric), crystallize in polar space groups. The 3D compounds have direct band gaps of 1.6 eV (1), 1.9 eV (2), 2.2 eV (3), and 2.5 eV (4), while the 1D compounds have indirect band gaps of 2.7 eV (5), 2.5 eV (6), and 2.8 eV (7). Herein, we report on the second harmonic generation (SHG) properties of the compounds, which display remarkably strong, type I phase-matchable SHG response with high laser-induced damage thresholds (up to ∼3 GW/cm(2)). The second-order nonlinear susceptibility, χS(2), was determined to be 125.3 ± 10.5 pm/V (1), (161.0 ± 14.5) pm/V (2), 143.0 ± 13.5 pm/V (3), and 57.2 ± 5.5 pm/V (4). First-principles density functional theory electronic structure calculations indicate that the large SHG response is attributed to the high density of states in the valence band due to sp-hybridization of the Ge and I orbitals, a consequence of the lone pair activation.

  5. Lanthanide-Connecting and Lone-Electron-Pair Active Trigonal-Pyramidal-AsO3 Inducing Nanosized Poly(polyoxotungstate) Aggregates and Their Anticancer Activities

    NASA Astrophysics Data System (ADS)

    Zhao, Jun-Wei; Li, Hai-Lou; Ma, Xing; Xie, Zhigang; Chen, Li-Juan; Zhu, Yongsheng

    2016-05-01

    By virtue of the stereochemical effect of the lone-electron pair located on the trigonal-pyramidal-AsO3 groups and the one-pot self-assembly strategy in the conventional aqueous solution, a series of novel lanthanide-bridging and lone-electron-pair active trigonal-pyramidal-AsO3 inducing nanosized poly(polyoxotungstate) aggregates [H2N(CH3)2]6 Na24H16{[Ln10W16(H2O)30O50](B-α-AsW9O33)8}·97H2O [Ln = EuIII (1), SmIII (2), GdIII (3), TbIII (4), DyIII (5), HoIII (6), ErIII (7), TmIII (8)] were prepared and further characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. The most remarkable structural feature is that the polyanionic skeleton of {[Ln10W16(H2O)30O50](B-α-AsW9O33)8}46‑ is constructed from eight trivacant Keggin [B-α-AsW9O33]9‑ fragments through ten Ln centers and sixteen bridging W atoms in the participation of fifty extraneous oxygen atoms. Notably, 4 and 8 can be stable in the aqueous solution not only for eight days but also in the range of pH = 3.9–7.5. Moreover, the cytotoxicity tests of 4 and 8 toward human cervical cancer (HeLa) cells, human breast cancer (MCF–7) cells and mouse fibroblast (L929) cells were performed by the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and the cell apoptosis processes were characterized by calcein AM/PI staining experiments, annexin V-FITC/PI staining experiments and morphological changes.

  6. Lanthanide-Connecting and Lone-Electron-Pair Active Trigonal-Pyramidal-AsO3 Inducing Nanosized Poly(polyoxotungstate) Aggregates and Their Anticancer Activities

    PubMed Central

    Zhao, Jun-Wei; Li, Hai-Lou; Ma, Xing; Xie, Zhigang; Chen, Li-Juan; Zhu, Yongsheng

    2016-01-01

    By virtue of the stereochemical effect of the lone-electron pair located on the trigonal-pyramidal-AsO3 groups and the one-pot self-assembly strategy in the conventional aqueous solution, a series of novel lanthanide-bridging and lone-electron-pair active trigonal-pyramidal-AsO3 inducing nanosized poly(polyoxotungstate) aggregates [H2N(CH3)2]6 Na24H16{[Ln10W16(H2O)30O50](B-α-AsW9O33)8}·97H2O [Ln = EuIII (1), SmIII (2), GdIII (3), TbIII (4), DyIII (5), HoIII (6), ErIII (7), TmIII (8)] were prepared and further characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric (TG) analyses and single-crystal X-ray diffraction. The most remarkable structural feature is that the polyanionic skeleton of {[Ln10W16(H2O)30O50](B-α-AsW9O33)8}46− is constructed from eight trivacant Keggin [B-α-AsW9O33]9− fragments through ten Ln centers and sixteen bridging W atoms in the participation of fifty extraneous oxygen atoms. Notably, 4 and 8 can be stable in the aqueous solution not only for eight days but also in the range of pH = 3.9–7.5. Moreover, the cytotoxicity tests of 4 and 8 toward human cervical cancer (HeLa) cells, human breast cancer (MCF–7) cells and mouse fibroblast (L929) cells were performed by the 3-(4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and the cell apoptosis processes were characterized by calcein AM/PI staining experiments, annexin V-FITC/PI staining experiments and morphological changes. PMID:27193961

  7. Scent-marking in lone wolves and newly formed pairs

    USGS Publications Warehouse

    Rothman, R.J.; Mech, L.D.

    1979-01-01

    Scent-marking was studied in wolves (Canis lupus) along 133 km of tracks in northern Minnesota during winters of 1975 to 1976 and 1976 to 1977 and in two captive packs and four captive pairs for various periods. Lone wolves, which possess neither mates nor territories, rarely marked by raised-leg urination and defaecated and urinated less along roads and trails, where territorial pairs and packs generally marked. Newly formed pairs marked the most, eventually decreasing their rates to those of established packs. Generally, wolves that scent-marked also bred, whereas non-marking wolves usually did not breed. Scent-marking apparently is important to the success of courtship in new pairs and to reproductive synchrony in established pairs, as well as serving a territorial function.

  8. A photoactive titanate with a stereochemically active Sn lone pair: Electronic and crystal structure of Sn{sub 2}TiO{sub 4} from computational chemistry

    SciTech Connect

    Burton, Lee A.; Walsh, Aron

    2012-12-15

    TiO{sub 2} remains the most widely studied metal oxide for photocatalytic reactions. The standard approach to reduce the band gap of titania, for increasing the absorption of visible light, is anion modification. For example the formation of an oxynitride compound, where the nitrogen 2p states decrease the binding energy of the valence band. We demonstrate that cation modification can produce a similar effect through the formation of a ternary oxide combining Ti and an ns{sup 2} cation, Sn(II). In Sn{sub 2}TiO{sub 4}, the underlying Ti 3d conduction states remain largely unmodified and an electronic band gap of 2.1 eV (590 nm) is predicted by hybrid density functional theory. Our analysis indicates a strong potential for Sn{sub 2}TiO{sub 4} in visible-light driven photocatalysis, which should prove superior to the alternative (SnO{sub 2}){sub 1-x}(TiO{sub 2}){sub x} solid-solution. - Graphical abstract: Sn{sub 2}TiO{sub 4} is predicted to be a semiconductor with potential for bipolar conductivity and visible-light photocatalysis. Highlights: Black-Right-Pointing-Pointer Tin titanate adopts the Pb{sub 3}O{sub 4} crystal structure with a sterically active Sn(II) lone pair. Black-Right-Pointing-Pointer Tin titanate is thermodynamically stable with respect to TiO{sub 2} and SnO. Black-Right-Pointing-Pointer Tin titanate is predicted have a band gap of 590 nm, ideal for photocatalytic applications.

  9. Temperature-controlled syntheses of substituted 1,2,4-triazolelead(II) complexes: active lone pair and N-H...X (X = Cl, Br, I) hydrogen bonds.

    PubMed

    Cheng, Jian-Kai; Zhang, Jian; Yin, Pei-Xiu; Lin, Qi-Pu; Li, Zhao-Ji; Yao, Yuan-Gen

    2009-11-02

    Three isomorphous lead(II) complexes with a new {N(3)SX}-coordinated (X = Cl, Br, I) mode have been synthesized and characterized by X-ray diffraction. The structural analyses reveal that the coordination environment around the center metal is distinctly influenced by the stereochemical 6s(2) lone pair and N-H...X hydrogen bonds. Additionally, doubly deprotonated trzS(2-) (HtrzSH = 1,2,4-triazole-3-thiol) generated in situ via deamination and dehydrazination of ahtrzS(-) (ahtrzSH = 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole) was first observed in a semiconducting three-dimensional coordination network at higher reaction temperature.

  10. Lone-pair interactions and photodissociation of compressed nitrogen trifluoride

    NASA Astrophysics Data System (ADS)

    Kurzydłowski, D.; Wang, H. B.; Troyan, I. A.; Eremets, M. I.

    2014-08-01

    High-pressure behavior of nitrogen trifluoride (NF3) was investigated by Raman and IR spectroscopy at pressures up to 55 GPa and room temperature, as well as by periodic calculations up to 100 GPa. Experimentally, we find three solid-solid phase transitions at 9, 18, and 39.5 GPa. Vibrational spectroscopy indicates that in all observed phases NF3 remains in the molecular form, in contrast to the behavior of compressed ammonia. This finding is confirmed by density functional theory calculations, which also indicate that the phase transitions of compressed NF3 are governed by the interplay between lone-pair interactions and efficient molecule packing. Although nitrogen trifluoride is molecular in the whole pressure range studied, we show that it can be photodissociated by mid-IR laser radiation. This finding paves the way for the use of NF3 as an oxidizing and fluorinating agent in high-pressure reactions.

  11. Supramolecular architectures based on As(lone pair)···π(aryl) interactions.

    PubMed

    Zukerman-Schpector, Julio; Otero-de-la-Roza, Alberto; Luaña, Víctor; Tiekink, Edward R T

    2011-07-21

    As(lone pair)···π interactions provide stability to their crystal structures often leading to supramolecular chains and prevailing over As···X secondary contacts. The interaction (ca 8 kJ mol(-1)) arises from polarisation induced in the aryl ring by the As-lone pair plus the weak sharing of these electrons with the ring-C atoms.

  12. Effect of lone-pair stereoactivity on polyhedral volume and structural flexibility: application to Te(IV)O6 octahedra.

    PubMed

    Christy, Andrew G; Mills, Stuart J

    2013-10-01

    The Distortion Theorem implies that the irregularity of bond distances in a distorted coordination polyhedron causes an increase of mean bond distance. Examination of 40 polyhedra containing the lone-pair cation Te(IV) shows that this does not imply an increase in polyhedral volume. Volumes of these polyhedra are 10.3-23.7 Å(3), compared with the 12.83 Å(3) expected for a hypothetical regular octahedron. There is little correlation between volume and measures of polyhedral distortion such as quadratic elongation, bond-angle variance or vector bond valence. However, the oxygens of our polyhedra lie very close to a sphere of best fit, centred at ~ 1 Å from the Te(IV) atom. The Te(IV)-centre distance is an index of lone-pair stereoactivity and is linearly related to the radius Rsph of the sphere; this is explained by a more localized lone pair repelling the anions more strongly, leading to a longer non-bonded distance between the lone pair and anions. Polyhedral volume still varies considerably for a given Rsph, because the oxygen ligands may be distributed over the whole sphere surface, or confined to a small portion of it. The uniformity of this distribution can be estimated from the distance between the sphere centre and the centroid of the O6 polyhedron. Te(IV)-centre and centroid-centre distances alone then account for 95% of the variation observed in volume for polyhedra which are topologically octahedral. Six of the polyhedra studied that are outliers are closer in shape to pentagonal pyramids than octahedra. These have short distances from the central Te(IV) cation to other Te(IV) and/or to large, polarizable cations, suggesting additional weak bonding interactions between these species and the central lone pair. The flexibility of lone-pair polyhedra is further enhanced by the ability of a single polyhedron to accommodate different cations with different degrees of lone-pair activity, which facilitates more diverse solid solution behaviour than would

  13. Site distortions created by the stereoactive lone pair of Tin(II) in highly symmetric structures

    NASA Astrophysics Data System (ADS)

    Dénès, Georges; Madamba, M. Cecilia; Merazig, Hocine; Muntasar, Abdualhafed; Zhu, Zhimeng

    2016-10-01

    Several fluoride compounds containing divalent tin that have a fluorite (CaF2-type) unit cell have been prepared and studied. Some are stoichiometric compounds while others are solid solutions. The cubic symmetry of the unit-cell (no lattice distortion and no superstructure) and the unique metal ion site of the fluorite structure make it that tin and the other metal have to be disordered on the normal metal site of the fluorite unit-cell. However, that site has the m3m-Oh point symmetry, and the metal ion is located in the center of a cube having fluoride ions in all its corners. Therefore, the same coordination should apply to tin. However, tin(II) possesses a non-bonding pair of electrons called a "lone pair", and in order for tin(II) to have a cubic symmetry, its lone pair has to be located on the unhybridized 5s orbital, that is spherical and thus does not distort the coordination. In such a case, the lone pair is said to be "non-stereoactive". This would make tin present in the form of the Sn2+ stannous ion, and therefore Sn-F bonding must be ionic. However, tin(II) fluorides are known to be always covalent with a hybridized lone pair on tin, which has therefore a reduced coordination number and therefore a highly distorted polyhedron of coordination. Such a hybridized lone pair is said to be "stereoactive". Tin-119 Mössbauer spectroscopy was used to probe the bonding type and it showed that bonding is covalent, the lone pair is hybridized and the tin coordination is dramatically distorted. A model based on a double disorder was made that accounts for the apparent contradiction between the crystallographic and the Mössbauer results.

  14. Impact of Lone-Pair Electrons on Thermal Conductivity in CuSbS2 Compound

    NASA Astrophysics Data System (ADS)

    Du, Baoli; Zhang, Ruizhi; Chen, Kan; Reece, Michael; Material research institute Team

    Compounds with intrinsically low lattice thermal conductivity are of practical importance for thermoelectric energy conversion. Recent studies suggest that s2 lone pair orbital electrons are a key contributing factor to the anomalously low lattice thermal conductivity of chalcogenide compounds that contain a nominally trivalent group VA element. CuSbS2 has an orthorhombic structure with space group Pnma. The pyramidal SbS5 units are separated by CuS4 tetrahedron so that the base of the square pyramidal units are aligned to face one another, thus directing the Sb lone pair electron density into the void separating the SbS5 units. Different from tetrahedrite, all the Cu atoms are bonded in the CuS4 tetrahedron. So, it has a perfect structure to study the influence of electron lone pair on thermal conductivity without the impact from trigonal coordinated Cu. In this work, the trivalent transition metal atom Fe and IIIA atom Ga without lone-pair electrons were chosen to substitute Sb in CuSbS2. The changes in the bonding environment by foreign atoms and their influences on the thermal properties have been studied and correlated. Marie Curie International Incoming Fellowship of the European Community Human Potential Program under Contract No. PIIF-GA-2013-622847.

  15. Persistence of polar distortion with electron doping in lone-pair driven ferroelectrics

    NASA Astrophysics Data System (ADS)

    He, Xu; Jin, Kui-juan

    2016-12-01

    Free electrons can screen out long-range Coulomb interaction and destroy the polar distortion in some ferroelectric materials, whereas the coexistence of polar distortion and metallicity were found in several non-central-symmetric metals (NCSMs). Therefore, the mechanisms and designing of NCSMs have attracted great interest. In this work, by first-principles calculation, we found the polar distortion in the lone-pair driven ferroelectric material PbTiO3 cannot only persist but also increase with electron doping. We further analyzed the mechanisms of the persisting of the polar distortion. We found that the Ti site polar instability is suppressed, but the Pb site polar instability is intact with the electron doping. The Pb-site instability is due to the lone-pair mechanism which can be viewed as a pseudo-Jahn-Teller effect, a mix of the ground state and the excited state by ion displacement from the central symmetric position. The lone-pair mechanism is not strongly affected by the electron doping because neither the ground state nor the excited state involved is at the Fermi energy. The enhancement of the polar distortion is related to the increasing of the Ti ion size by doping. These results show that the long-pair stereoactive ions can be used for designing NCSMs.

  16. Role of lone-pair electrons in producing minimum thermal conductivity in nitrogen-group chalcogenide compounds.

    PubMed

    Skoug, Eric J; Morelli, Donald T

    2011-12-02

    Fully dense crystalline solids with extremely low lattice thermal conductivity (κ(L)) are of practical importance for applications including thermoelectric energy conversion and thermal barrier coatings. Here we show that lone-pair electrons can give rise to minimum κ(L) in chalcogenide compounds that contain a nominally trivalent group VA element. Electrostatic repulsion between the lone-pair electrons and neighboring chalcogen ions creates anharmonicity in the lattice, the strength of which is determined by the morphology of the lone-pair orbital and the coordination number of the group VA atom.

  17. Lone-pair interactions and photodissociation of compressed nitrogen trifluoride.

    PubMed

    Kurzydłowski, D; Wang, H B; Troyan, I A; Eremets, M I

    2014-08-14

    High-pressure behavior of nitrogen trifluoride (NF3) was investigated by Raman and IR spectroscopy at pressures up to 55 GPa and room temperature, as well as by periodic calculations up to 100 GPa. Experimentally, we find three solid-solid phase transitions at 9, 18, and 39.5 GPa. Vibrational spectroscopy indicates that in all observed phases NF3 remains in the molecular form, in contrast to the behavior of compressed ammonia. This finding is confirmed by density functional theory calculations, which also indicate that the phase transitions of compressed NF3 are governed by the interplay between lone‑pair interactions and efficient molecule packing. Although nitrogen trifluoride is molecular in the whole pressure range studied, we show that it can be photodissociated by mid-IR laser radiation. This finding paves the way for the use of NF3 as an oxidizing and fluorinating agent in high-pressure reactions.

  18. Lone-pair interactions and photodissociation of compressed nitrogen trifluoride

    SciTech Connect

    Kurzydłowski, D.; Wang, H. B.; Eremets, M. I.; Troyan, I. A.

    2014-08-14

    High-pressure behavior of nitrogen trifluoride (NF{sub 3}) was investigated by Raman and IR spectroscopy at pressures up to 55 GPa and room temperature, as well as by periodic calculations up to 100 GPa. Experimentally, we find three solid-solid phase transitions at 9, 18, and 39.5 GPa. Vibrational spectroscopy indicates that in all observed phases NF{sub 3} remains in the molecular form, in contrast to the behavior of compressed ammonia. This finding is confirmed by density functional theory calculations, which also indicate that the phase transitions of compressed NF{sub 3} are governed by the interplay between lone‑pair interactions and efficient molecule packing. Although nitrogen trifluoride is molecular in the whole pressure range studied, we show that it can be photodissociated by mid-IR laser radiation. This finding paves the way for the use of NF{sub 3} as an oxidizing and fluorinating agent in high-pressure reactions.

  19. Molecular Balances Based on Aliphatic CH-π and Lone-Pair-π Interactions.

    PubMed

    Nijamudheen, A; Jose, Deepthi; Shine, A; Datta, Ayan

    2012-06-07

    CH···π and lone-pair···π interactions are estimated for a series of conformationally dynamic bicyclic N-aryliimides. On the basis of their strengths and mutual synergy/competition, the molecules prefer a folded/unfolded conformation. Calculations suggest strategies to selectively isolate the folded form by increasing the strength of the attractive CH···π interaction or removing the lone-pair···π repulsion. While the barrier for the folded ⇄ unfolded transformation is too large to conformationally lock the molecules in either of the conformers, the dynamics for hopping of the alkyl group across rings and tumbling over the rings are found to be facile in the folded conformation.

  20. The impact of lone pair-π interactions on photochromic properties in 1-D naphthalene diimide coordination networks.

    PubMed

    Liu, Jian-Jun; Guan, Ying-Fang; Chen, Yong; Lin, Mei-Jin; Huang, Chang-Cang; Dai, Wen-Xin

    2015-10-21

    Lone pair-π interaction is an important but less studied binding force. Generally, it is too weak to influence the physical properties of supramolecular systems. Herein we reported the first example exhibiting the impact of lone pair-π interactions on photochromic properties of naphthalene diimide based coordination networks. In three isostructural 1-D networks, [(DPNDI)ZnX2] (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide, X = Cl for 1, X = Br for 2 and X = I for 3), they exhibit different electron-transfer photochromic behaviors due to different lone pair-π interactions between the capped halogen atoms and electron-deficient DPNDI moieties. Specifically, 1 and 2 but not 3 are photochromic, which is attributed to a stronger lone pair-π interaction in 3 than those in 1 and 2. This study anticipates breaking a new path for designing novel photochromic materials through such unnoticeable supramolecular interactions.

  1. Bonds, bands, and band gaps in tetrahedrally bonded ternary compounds: The role of group V lone pairs

    NASA Astrophysics Data System (ADS)

    Do, Dat T.; Mahanti, S. D.

    2014-04-01

    An interesting class of tetrahedrally coordinated ternary compounds has attracted considerable interest because of their potential as good thermoelectrics. These compounds, denoted as I3-V-VI4, contain three monovalent-I (Cu, Ag), one nominally pentavalent-V (P, As, Sb, Bi), and four hexavalent-VI (S, Se, Te) atoms; and can be visualized as ternary derivatives of the II-VI zincblende or wurtzite semiconductors, obtained by starting from four unit cells of (II-VI) and replacing four type II atoms by three type I and one type V atoms. We find that nominally pentavalent-V atoms are effectively trivalent and their lone (ns2) pairs play an active role in opening up a gap. The lowest conduction band is a strongly hybridized anti-bonding combination of the lone pair and chalcogen (VI) p-states. The magnitude of the gap is sensitive to the nature of the exchange interaction (local vs non-local) and the V-VI distance. We also find that the electronic structure near the gap can be reproduced extremely well within a local theory if one can manipulate the position of the filled d bands of Cu and Ag by an effectively large U.

  2. The influence of intramolecular sulfur-lone pair interactions on small-molecule drug design and receptor binding.

    PubMed

    Hudson, B M; Nguyen, E; Tantillo, D J

    2016-04-28

    Sulfur-lone pair interactions are important conformational control elements in sulfur-containing heterocycles that abound in pharmaceuticals, natural products, agrochemicals, polymers and other important classes of organic molecules. Nonetheless, the role of intramolecular sulfur-lone pair interactions in the binding of small molecules to receptors is often overlooked. Here we analyze the magnitudes and origins of these interactions for a variety of biologically relevant small molecules using quantum chemical and automated docking calculations. In most cases examined in this study, the lowest energy conformation of the small molecule displays a sulfur-lone pair close contact. However, docking studies, both published and new, often predict that conformations without sulfur-lone pair contacts have the best binding affinity for their respective receptors. This is a serious problem. Since many of these predicted bound conformations are not actually energetically accessible, pursuing design (e.g., drug design) around these binding modes necessarily will lead, serendipity aside, to dead end designs. Our results constitute a caution that one best not neglect these interactions when predicting the binding affinities of potential ligands (drugs or not) for hosts (enzymes, receptors, DNA, RNA, synthetic hosts). Moreover, a better understanding and awareness of sulfur-lone pair interactions should facilitate the rational modulation of host-guest interactions involving sulfur-containing molecules.

  3. Lone-Pair-Electron-Driven Ionic Displacements in a Ferroelectric Metal-Organic Hybrid.

    PubMed

    Zhao, Wen-Ping; Shi, Chao; Stroppa, Alessandro; Di Sante, Domenico; Cimpoesu, Fanica; Zhang, Wen

    2016-10-17

    A displacive-type mechanism, which accounts for the occurrence of ferroelectricity in most inorganic ferroelectrics, is rarely found in molecule-based ferroelectrics. Its role is often covered by the predominant order-disorder one. Herein, we report a lone-pair-electron-driven displacive-type ferroelectric organic-inorganic hybrid compound, [H2dmdap][SbCl5] (1; dmdap = N,N-dimethyl-1,3-diaminopropane). The structure of 1 features a typical zigzag chain of [SbCl5]∞ containing cis-connected anionic octahedra. The compound undergoes a second-order paraelectric-ferroelectric phase transition at 143 K (P21/c ↔ Pc) with a saturation polarization of 1.36 μC·cm(-2) and a coercive field of 3.5 kV·cm(-1) at 119 K. Theoretical study discloses the ferroelectricity mainly originating from the relative displacements of the Sb and Cl ions in the crystal lattice, which are driven by the 5s(2) lone-pair electrons of the Sb(III) center. Furthermore, on the basis of analysis, possible routes are suggested to enhance ferroelectric polarization in this class of compounds.

  4. Experimental Evidence of Lone Pairs - π System Interaction: the Rotational Spectrum of Chlorotrifluoroethylene - Water Complex

    NASA Astrophysics Data System (ADS)

    Evangelisti, L.; Gou, Q.; Feng, G.; Caminati, W.

    2013-06-01

    Chemists have always been interested in labeling the interactions between the molecules, i.e. from covalent to ionic bond or van der Waals force. Certainly the most important non-covalent bond is the hydrogen bond, also of fundamental importance in biology. More recently also weak Hbond, sometimes in competion with halogen bonding, have been investigated because they have assumed a fundamental importance. Here, we show the lone pairs - π interaction prevails on the latter ones. We measured the molecular beam Fourier transform microwave spectra of five isotopologues of the 1:1 adduct of chlorotrifluoroethylene with water. Besides the rotational constants, the quadrupole coupling constants of the chlorine atom have been determined. Quantum chemistry calculations, at the MP2/6-311++G(d,p) level, have been carried out in order to obtain information about the structure and relative stability of the conformers under study.

  5. Lone-pair-π interactions: analysis of the physical origin and biological implications.

    PubMed

    Novotný, Jan; Bazzi, Sophia; Marek, Radek; Kozelka, Jiří

    2016-07-28

    Lone-pair-π (lp-π) interactions have been suggested to stabilize DNA and protein structures, and to participate in the formation of DNA-protein complexes. To elucidate their physical origin, we have carried out a theoretical multi-approach analysis of two biologically relevant model systems, water-indole and water-uracil complexes, which we compared with the structurally similar chloride-tetracyanobenzene (TCB) complex previously shown to contain a strong charge-transfer (CT) binding component. We demonstrate that the CT component in lp-π interactions between water and indole/uracil is significantly smaller than that stabilizing the Cl(-)-TCB reference system. The strong lp(Cl(-))-π(TCB) orbital interaction is characterized by a small energy gap and an efficient lp-π* overlap. In contrast, in lp-π interactions between water and indole or uracil, the corresponding energy gap is larger and the overlap less efficient. As a result, water-uracil and water-indole interactions are weak forces composed by smaller contributions from all energy components: electrostatics, polarization, dispersion, and charge transfer. In addition, indole exhibits a negative electrostatic potential at its π-face, making lp-π interactions less favorable than O-Hπ hydrogen bonding. Consequently, some of the water-tryptophan contacts observed in X-ray structures of proteins and previously interpreted as lp-π interactions [Luisi, et al., Proteins, 2004, 57, 1-8], might in fact arise from O-Hπ hydrogen bonding.

  6. Effects of interlayer Sn-Sn lone pair interaction on the band gap of bulk and nanosheet SnO

    NASA Astrophysics Data System (ADS)

    Umezawa, Naoto; Zhou, Wei

    2015-03-01

    Effects of interlayer lone-pair interactions on the electronic structure of SnO are firstly explored by the density-functional theory. Our comprehensive study reveals that the band gap of SnO opens as increase in the interlayer Sn-Sn distance. The effect is rationalized by the character of band edges which consists of bonding and anti-bonding states from interlayer lone pair interactions. The band edges for several nanosheets and strained double-layer SnO are estimated. We conclude that the double-layer SnO is a promising material for visible-light driven photocatalyst for hydrogen evolution. This work is supported by the Japan Science and Technology Agency (JST) Precursory Research for Embryonic Science and Technology (PRESTO) program.

  7. On the satisfaction of backbone‐carbonyl lone pairs of electrons in protein structures

    PubMed Central

    2016-01-01

    Abstract Protein structures are stabilized by a variety of noncovalent interactions (NCIs), including the hydrophobic effect, hydrogen bonds, electrostatic forces and van der Waals’ interactions. Our knowledge of the contributions of NCIs, and the interplay between them remains incomplete. This has implications for computational modeling of NCIs, and our ability to understand and predict protein structure, stability, and function. One consideration is the satisfaction of the full potential for NCIs made by backbone atoms. Most commonly, backbone‐carbonyl oxygen atoms located within α‐helices and β‐sheets are depicted as making a single hydrogen bond. However, there are two lone pairs of electrons to be satisfied for each of these atoms. To explore this, we used operational geometric definitions to generate an inventory of NCIs for backbone‐carbonyl oxygen atoms from a set of high‐resolution protein structures and associated molecular‐dynamics simulations in water. We included more‐recently appreciated, but weaker NCIs in our analysis, such as n→π* interactions, Cα‐H bonds and methyl‐H bonds. The data demonstrate balanced, dynamic systems for all proteins, with most backbone‐carbonyl oxygen atoms being satisfied by two NCIs most of the time. Combinations of NCIs made may correlate with secondary structure type, though in subtly different ways from traditional models of α‐ and β‐structure. In addition, we find examples of under‐ and over‐satisfied carbonyl‐oxygen atoms, and we identify both sequence‐dependent and sequence‐independent secondary‐structural motifs in which these reside. Our analysis provides a more‐detailed understanding of these contributors to protein structure and stability, which will be of use in protein modeling, engineering and design. PMID:26833776

  8. Thiophosphates Containing Ag(+) and Lone-Pair Cations with Interchiral Double Helix Show Both Ionic Conductivity and Phase Transition.

    PubMed

    Fan, Yu-Hang; Zeng, Hui-Yi; Jiang, Xiao-Ming; Zhang, Ming-Jian; Liu, Bin-Wen; Guo, Guo-Cong; Huang, Jin-Shun

    2017-01-17

    Quaternary metal thiophosphates containing second-order Jahn-Teller distorted d(10) Ag(+) and lone-pair cations, Ag3Bi(PS4)2 (1), Ag7Sn(PS4)3 (2), and Ag7Pb(PS4)3 (3), were obtained by solid-state synthesis. The structural frameworks of 2 and 3 feature an infinite 1-D interchiral double helix ∞(1)(Ag3P2S11), which is rare in inorganic compounds. Compound 3 undergoes a significant first-order structural phase transition from monoclinic to hexagonal at ∼204 °C. This can be ascribed to the significant mismatch in the expansion coefficients between Pb-S (Ag-S) and P-S bonds evaluated by bond valence theory. The three compounds are Ag(+) ionic conductors, and Ag(+) ion migration pathways are proposed by calculating maps of low bond valence mismatch. Moreover, the optical properties of the three compounds were studied, and electronic structure calculations were performed. The combination of second-order Jahn-Teller distorted d(10) cation and lone-pair cation provides a new strategy to explore new metal thiophosphates with interesting structures and promising properties.

  9. Lone pair⋯π interactions involving carbonyl π-systems: Experimental and theoretical study of the complexes of COF2 and COFCl with dimethyl ether

    NASA Astrophysics Data System (ADS)

    Geboes, Yannick; De Proft, Frank; Herrebout, Wouter A.

    2016-09-01

    In this theoretical and experimental study, the ability of carbonyl fluoride (COF2) and carbonyl chloride fluoride (COFCl) to form noncovalent interactions with the Lewis base dimethyl ether (DME) is assessed. From ab initio calculations, two stable complexes are found for COF2·DME, both formed through a lone pair⋯π interaction. FTIR measurements on liquefied noble gas solutions, supported by ab initio calculations, statistical thermodynamical calculations and Monte Carle Free Energy Perturbation calculations, show that a 1:1 lone pair⋯π bonded complex is found in solution, with an experimental complexation enthalpy of -14.5(3) kJ mol-1. For COFCl·DME three lone pair⋯π complexes, as well as a Cl⋯O halogen bonded complex, are found from ab initio calculations. Experimentally, clear complex bands for 1:1 lone pair⋯π complexes are observed, with an experimental complexation enthalpy of -11.4(2) kJ mol-1. Furthermore, indications of the presence of a small amount of the halogen bonded complex are also observed.

  10. Communication: Oscillating charge migration between lone pairs persists without significant interaction with nuclear motion in the glycine and Gly-Gly-NH-CH{sub 3} radical cations

    SciTech Connect

    Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A.

    2014-05-28

    Coupled electron-nuclear dynamics has been studied, using the Ehrenfest method, for four conformations of the glycine molecule and a single conformation of Gly-Gly-NH-CH{sub 3}. The initial electronic wavepacket was a superposition of eigenstates corresponding to ionization from the σ lone pairs associated with the carbonyl oxygens and the amine nitrogen. For glycine, oscillating charge migration (when the nuclei were frozen) was observed for the 4 conformers studied with periods ranging from 2 to 5 fs, depending on the energy gap between the lone pair cationic states. When coupled nuclear motion was allowed (which was mainly NH{sub 2} partial inversion), the oscillations hardly changed. For Gly-Gly-NH-CH{sub 3}, charge migration between the carbonyl oxygens and the NH{sub 2} lone pair can be observed with a period similar to glycine itself, also without interaction with nuclear motion. These simulations suggest that charge migration between lone pairs can occur independently of the nuclear motion.

  11. Theoretical Study on the Dual Behavior of XeO3 and XeF4 toward Aromatic Rings: Lone Pair-π versus Aerogen-π Interactions.

    PubMed

    Bauzá, Antonio; Frontera, Antonio

    2015-12-01

    In this study, several lone pair-π and aerogen-π complexes between XeO3 and XeF4 and aromatic rings with different electronic natures (benzene, trifluorobenzene, and hexafluorobenzene) are optimized at the RI-MP2/aug-cc-pVTZ level of theory. All complexes are characterized as true minima by frequency analysis calculations. The donor/acceptor role of the ring in the complexes is analyzed using the natural bond orbital computational tool, showing a remarkable contribution of orbital interactions to the global stabilization of the aerogen-π complexes. Finally, Bader's AIM analysis of several complexes is performed to further characterize the lone pair-π and aerogen-π interactions.

  12. One-dimensional lone electron pair micelles in the crystal structure of Pb{sub 5}(SiO{sub 4})(VO{sub 4}){sub 2}

    SciTech Connect

    Krivovichev, S.V.; Armbruster, T.; Depmeier, W

    2004-09-01

    The structure of Pb{sub 5}(SiO{sub 4})(VO{sub 4}){sub 2} (hexagonal, P6{sub 3}/m, a = 9.9865(11), c = 7.3599(12) A, V = 635.67(14) A{sup 3}, Z = 2) has been solved by direct methods and refined to R{sub 1} = 0.051 on the basis of 440 unique observed reflections with vertical bar F{sub o} vertical bar{>=}4{sigma}{sub F}. The compound belongs to the apatite structure type. The Pb coordination polyhedra are distorted due to the presence of stereoactive lone electron pairs {psi}. The structure contains channels running along the c axis and centered at (00z). The channels are most probably occupied by the lone electron pairs of the Pb{sup 2+} cations and thus represent lone electron pair micelles. The existence of such micelles in the structure may well be the reason for the electrogyratory effect and protonic conductivity observed in crystals of the title compound.

  13. Pairing Learners in Pair Work Activity

    ERIC Educational Resources Information Center

    Storch, Neomy; Aldosari, Ali

    2013-01-01

    Although pair work is advocated by major theories of second language (L2) learning and research findings suggest that pair work facilitates L2 learning, what is unclear is how to best pair students in L2 classes of mixed L2 proficiency. This study investigated the nature of pair work in an English as a Foreign Language (EFL) class in a college in…

  14. Probing the Lone Pair···π-Hole Interaction in Perfluorinated Heteroaromatic Rings: The Rotational Spectrum of Pentafluoropyridine·Water.

    PubMed

    Calabrese, Camilla; Gou, Qian; Maris, Assimo; Caminati, Walther; Melandri, Sonia

    2016-04-21

    The rotational spectrum of the weakly bound complex pentafluoropyridine·water has been investigated with pulsed jet Fourier transform microwave spectroscopy. From the analysis of the rotational parameters of the parent species and of three water isotopologues, the structural arrangement of the adduct has been unambiguously established. The results show that the full ring fluorination of pyridine has a dramatic effect on its binding properties: It inverts the electron density distribution above the ring, creating a π-hole, with respect to the typical π-cloud of benzene and pyridine. In the complex the water moiety lies above the aromatic ring with the oxygen lone pairs pointing toward its center. This lone pair···π-hole interaction stabilizes the adduct, and it is more stable than the in-plane O-H···N hydrogen bond normally found in the complexes involving nitrogen heterocyclic aromatic rings. Evidence of a large amplitude motion involving the weakly bound water molecule has also been observed and discussed.

  15. ns2np4 (n = 4, 5) lone pair triplets whirling in M*F2E3 (M* = Kr, Xe): Stereochemistry and ab initio analyses

    NASA Astrophysics Data System (ADS)

    Galy, Jean; Matar, Samir F.

    2017-02-01

    The stereochemistry of ns2np4 (n = 4, 5) lone pair LP characterizing noble gas Kr and Xe (labeled M*) in M*F2 difluorides is examined within coherent crystal chemistry and ab initio visualizations. M*2+ in such oxidation state brings three lone pairs (E) and difluorides are formulated M*F2E3. The analyses use electron localization function (ELF) obtained within density functional theory calculations showing the development of the LP triplets whirling {E3} quantified in the relevant chemical systems. Detailed ELF data analyses allowed showing that in α KrF2E3 and isostructural XeF2E3 difluorides the three E electronic clouds merge or hybridize into a torus and adopt a perfect gyration circle with an elliptical section, while in β KrF2 the network architecture deforms the whole torus into an ellipsoid shape. Original precise metrics are provided for the torus in the different compounds under study. In KrF2 the geometric changes upon β → α phase transition is schematized and mechanisms for the transformation with temperature or pressure are proposed. The results are further highlighted by electronic band structure calculations which show similar features of equal band gaps of 3 eV in both α and β KrF2 and a reorganization of frontier orbitals due to the different orientations of the F-Kr-F linear molecule in the two tetragonal structures.

  16. σ-Hole Opposite to a Lone Pair: Unconventional Pnicogen Bonding Interactions between ZF3 (Z=N, P, As, and Sb) Compounds and Several Donors.

    PubMed

    Bauzá, Antonio; Mooibroek, Tiddo J; Frontera, Antonio

    2016-06-03

    The ability of several pnicogen sp(3) derivatives ZF3 (Z=N, P, As, Sb) to interact with electron-rich entities by means of the opposite face to the lone pair (lp) is investigated at the RI-MP2/aug-cc-pVQZ level of theory. The strength of the interaction ranges from -1 to -87 kJ mol(-1) , proving its favorable nature, especially when the lp is coordinated to a metal center, whereby the strength of the interaction is significantly enhanced. NBO analysis showed that orbital effects are modest contributors to the global stabilization of the pnicogen σ-hole bonded complexes studied. Finally, a selection of Cambridge Structural Database examples are shown that demonstrate the impact of this counterintuitive binding mode in the solid state.

  17. Electron lone pair distortion facilitated metal-insulator transition in β-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires

    SciTech Connect

    Wangoh, L.; Quackenbush, N. F.; Marley, P. M.; Banerjee, S.; Sallis, S.; Fischer, D. A.; Woicik, J. C.; Piper, L. F. J.

    2014-05-05

    The electronic structure of β-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires has been studied with x-ray photoelectron spectroscopy techniques. The recent synthesis of defect-free β-Pb{sub 0.33}V{sub 2}O{sub 5} nanowires resulted in the discovery of an abrupt voltage-induced metal insulator transition. First principle calculations predicted an additional V-O-Pb hybridized “in-gap” state unique to this vanadium bronze playing a significant role in facilitating the transition. We confirm the existence, energetic position, and orbital character of the “in-gap” state. Moreover, we reveal that this state is a hybridized Pb 6s–O 2p antibonding lone pair state resulting from the asymmetric coordination of the Pb{sup 2+} ions.

  18. On the importance of unprecedented lone pair-salt bridge interactions in Cu(II)-malonate-2-amino-5-chloropyridine-perchlorate ternary system.

    PubMed

    Mitra, Monojit; Manna, Prankrishna; Das, Amrita; Seth, Saikat Kumar; Helliwell, Madeleine; Bauzá, Antonio; Choudhury, Somnath Ray; Frontera, Antonio; Mukhopadhyay, Subrata

    2013-07-18

    A Cu(II)-malonate complex with formula {(C5H6N2Cl)12[Cu(1)(C3H2O4)2][Cu(2)(C3H2O4)2(H2O)2][Cu(4)(C3H2O4)2][Cu(3)(C3H2O4)2(H2O)2](ClO4)4}n (1) [C5H6N2Cl = protonated 2-amino-5-chloropyridine, C3H4O4 = malonic acid, ClO4(-) = perchlorate] has been synthesized from purely aqueous media simple by mixing the reactants in their stoichiometric ratio, and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, copper(II) malonate units form infinite 1D polymeric chains, which are interlinked by hydrogen bonds to generate 2D sheets. These 2D sheets are joined side by side primarily by various hydrogen bonds to form a 3D structure. A multitude of salt bridges are formed in this structure, connecting the protonated 2-amino-5-chloropyridines and the malonate ligands of the polymeric polyanion. Examining this characteristic of the solid-state architecture, we noticed several salt-bridge (sb)···π interactions and an unexplored interaction between the lone pair (lp) of one malonate oxygen atom and a planar salt bridge. The combination of this interaction with various other weak intermolecular forces results in a remarkably extended supramolecular network combining a wide variety of interactions involving π-systems (Cl···π, π···π) and salt bridges (sb···π and lp···sb). We describe the energetic and geometric features of this lone pair-salt-bridge interaction and explore its impact on the resultant supramolecular organization using theoretical DFT-D3 calculations.

  19. Defect properties of Sb- and Bi-doped CuInSe{sub 2}: The effect of the deep lone-pair s states

    SciTech Connect

    Park, Ji-Sang; Yang, Ji-Hui; Ramanathan, Kannan; Wei, Su-Huai

    2014-12-15

    Bi or Sb doping has been used to make better material properties of polycrystalline Cu{sub 2}(In,Ga)Se{sub 2} as solar cell absorbers, including the experimentally observed improved electrical properties. However, the mechanism is still not clear. Using first-principles method, we investigate the stability and electronic structure of Bi- and Sb-related defects in CuInSe{sub 2} and study their effects on the doping efficiency. Contrary to previous thinking that Bi or Sb substituted on the anion site, we find that under anion-rich conditions, the impurities can substitute on cation sites and are isovalent to In because of the formation of the impurity lone pair s states. When the impurities substitute for Cu, the defects act as shallow double donors and help remove the deep In{sub Cu} level, thus resulting in the improved carrier life time. On the other hand, under anion-poor conditions, impurities at the Se site create amphoteric deep levels that are detrimental to the device performance.

  20. Anion induced formation of supramolecular associations involving lone pair-π and anion-π interactions in Co(II) malonate complexes: experimental observations, Hirshfeld surface analyses and DFT studies.

    PubMed

    Manna, Prankrishna; Seth, Saikat Kumar; Das, Amrita; Hemming, Joanna; Prendergast, Richard; Helliwell, Madeleine; Choudhury, Somnath Ray; Frontera, Antonio; Mukhopadhyay, Subrata

    2012-03-19

    Three Co(II)-malonate complexes, namely, (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](NO(3))(2) (1), (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](ClO(4))(2) (2), and (C(5)H(7)N(2))(4)[Co(C(3)H(2)O(4))(2)(H(2)O)(2)](PF(6))(2) (3) [C(5)H(7)N(2) = protonated 2-aminopyridine, C(3)H(4)O(4) = malonic acid, NO(3)(-) = nitrate, ClO(4)(-) = perchlorate, PF(6)(-) = hexafluorophosphate], have been synthesized from purely aqueous media, and their crystal structures have been determined by single crystal X-ray diffraction. A thorough analysis of Hirshfeld surfaces and fingerprint plots facilitates a comparison of intermolecular interactions in 1-3, which are crucial in building supramolecular architectures. When these complexes are structurally compared with their previously reported analogous Ni(II) or Mg(II) compounds, a very interesting feature regarding the role of counteranions has emerged. This phenomenon can be best described as anion-induced formation of extended supramolecular networks of the type lone pair-π/π-π/π-anion-π/π-lone pair and lone pair-π/π-π/π-anion involving various weak forces like lone pair-π, π-π, and anion-π interactions. The strength of these π contacts has been estimated using DFT calculations (M06/6-31+G*), and the formation energy of the supramolecular networks has been also evaluated. The influence of the anion (NO(3)(-), ClO(4)(-), and PF(6)(-)) on the total interaction energy of the assembly is also studied.

  1. Lone pair ... pi interactions between water oxygens and aromatic residues: quantum chemical studies based on high-resolution protein structures and model compounds.

    PubMed

    Jain, Alok; Ramanathan, Venkatnarayan; Sankararamakrishnan, Ramasubbu

    2009-03-01

    The pi electron cloud of aromatic centers is known to be involved in several noncovalent interactions such as C--H...pi, O--H...pi, and pi...pi interactions in biomolecules. Lone-pair (lp) ... pi interactions have gained attention recently and their role in biomolecular structures is being recognized. In this article, we have carried out systematic analysis of high-resolution protein structures and identified more than 400 examples in which water oxygen atoms are in close contact (distance < 3.5 A) with the aromatic centers of aromatic residues. Three different methods were used to build hydrogen atoms and we used a consensus approach to find out potential candidates for lp...pi interactions between water oxygen and aromatic residues. Quantum mechanical calculations at MP2/6-311++G(d,p) level on model systems based on protein structures indicate that majority of the identified examples have energetically favorable interactions. The influence of water hydrogen atoms was investigated by sampling water orientations as a function of two parameters: distance from the aromatic center and the angle between the aromatic plane and the plane formed by the three water atoms. Intermolecular potential surfaces were constructed using six model compounds representing the four aromatic amino acids and 510 different water orientations for each model compound. Ab initio molecular orbital calculations at MP2/6-311++G(d,p) level show that the interaction energy is favorable even when hydrogen atoms are farthest from the aromatic plane while water oxygen is pointing toward the aromatic center. The strength of such interaction depends upon the distance of water hydrogen atoms from the aromatic substituents. Our calculations clearly show that the lp...pi interactions due to the close approach of water oxygen and aromatic center are influenced by the positions of water hydrogen atoms and the aromatic substituents.

  2. Lonely killers

    PubMed Central

    2011-01-01

    The majority of the most effective monoclonal antibodies (mAbs) currently in the clinics bind to cancer or immune cells. Classic mechanisms of cell killing by therapeutic mAbs include antibody-dependent cell-mediated cytotoxicity, complement-dependent cytotoxicity and induction of apoptosis by engagement of specific cell ligands. A few reports have described mAbs whose cytotoxic activity is Fc-independent and that do not induce the morphological and biochemical changes associated with the apoptosis-type of cell death. Even fewer works describe mAbs able to directly induce membrane lesions. Here, we discuss the available data on those molecules and their cell killing activity, with particular attention to the case of a mAb specific for the tumor-associated N-glycolyl (Neu5Gc)-GM3 ganglioside [GM3(Neu5Gc)]. Some similarities are found in the cell death pathways triggered by these mAbs, but data are not abundant. We conclude that the usefulness of mAbs with a direct cytotoxic activity for immunotherapeutic strategies deserves deeper research. PMID:22123064

  3. Emerging risk factors and the dose–response relationship between physical activity and lone atrial fibrillation: a prospective case–control study

    PubMed Central

    Calvo, Naiara; Ramos, Pablo; Montserrat, Silvia; Guasch, Eduard; Coll-Vinent, Blanca; Domenech, Mònica; Bisbal, Felipe; Hevia, Sara; Vidorreta, Silvia; Borras, Roger; Falces, Carles; Embid, Cristina; Montserrat, Josep Maria; Berruezo, Antonio; Coca, Antonio; Sitges, Marta; Brugada, Josep; Mont, Lluís

    2016-01-01

    Aims The role of high-intensity exercise and other emerging risk factors in lone atrial fibrillation (Ln-AF) epidemiology is still under debate. The aim of this study was to analyse the contribution of each of the emerging risk factors and the impact of physical activity dose in patients with Ln-AF. Methods and results Patients with Ln-AF and age- and sex-matched healthy controls were included in a 2:1 prospective case–control study. We obtained clinical and anthropometric data transthoracic echocardiography, lifetime physical activity questionnaire, 24-h ambulatory blood pressure monitoring, Berlin questionnaire score, and, in patients at high risk for obstructive sleep apnoea (OSA) syndrome, a polysomnography. A total of 115 cases and 57 controls were enrolled. Conditional logistic regression analysis associated height [odds ratio (OR) 1.06 [1.01–1.11

  4. Locating the Place and Meaning of Physical Activity in the Lives of Young People from Low-Income, Lone-Parent Families

    ERIC Educational Resources Information Center

    Quarmby, Thomas; Dagkas, Symeon

    2013-01-01

    Background: In the United Kingdom (UK), it is predicted that economic cuts and a subsequent increase in child poverty will affect those already on the lowest incomes and, in particular, those living in lone-parent families. As a result, the informal pedagogic encounters within the family that contribute to the development of physical…

  5. The Lone Wolf Threat: A Different Approach

    DTIC Science & Technology

    2016-03-24

    5  CHAPTER 3: A PROFILE OF THE LONE WOLF: KEY FACTORS .................... 9  Psychological ...be examined through four case studies in Chapter Four. These factors are characterized as psychological , social, cognitive capacity, financial...conduct a lone wolf terrorist act to develop a general profile. Psychological Psychological temperaments of the lone wolf are those atypical to

  6. Lone Mountain processing boosts recovery

    SciTech Connect

    Baumgarth, T.; Bethell, P.; Gupta, B.K.

    2005-08-01

    A new deslime column flotation circuit installed at Arch Coal's Lone Mountain preparation plant in St. Charles, Va., USA recovers an additional 20 tph. The article describes how this column technology was selected. It explains the circuit design, start-up and post upgrade distant testing. 4 figs., 4 tabs.

  7. Influence of 6s{sup 2} lone pair electrons of Bi{sup 3+} on its preferential site occupancy in fluorapatite, NaCa{sub 3}Bi(PO{sub 4}){sub 3}F – An insight from Eu{sup 3+} luminescent probe

    SciTech Connect

    Lakshminarasimhan, N. Varadaraju, U.V.

    2014-12-15

    Graphical abstract: Eu{sup 3+} structural probe – difference in Eu{sup 3+} PL emission in (a) NaCa{sub 3}Bi{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F and (b) NaCa{sub 3}La{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F suggests Bi{sup 3+} with preferential site occupancy at M(II) site directing Eu{sup 3+} to M(I) site. - Highlights: • Eu{sup 3+} luminescent probe used for establishing the role of 6s{sup 2} lone pair electrons of Bi{sup 3+} in fluorapatite. • Difference in Eu{sup 3+} PL emission spectral features in NaCa{sub 3}Bi{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F and NaCa{sub 3}La{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F. • Preferential site occupancy of Bi{sup 3+} in M(II) site directs Eu{sup 3+} to M(I) site in NaCa{sub 3}Bi{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F. - Abstract: Eu{sup 3+} luminescence was used as a structural probe in understanding the preferential site occupancy of lone pair cation, Bi{sup 3+}, in fluorapatite by comparing the photoluminescence (PL) emission spectral features with that of in analogous La{sup 3+} based fluorapatite. The fluorapatites, NaCa{sub 3}Bi{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F and NaCa{sub 3}La{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F, were synthesized by conventional high temperature solid state reaction method and characterized by powder X-ray diffraction (XRD) and FT-IR spectroscopy. The Eu{sup 3+} PL results revealed a difference in the emission spectral features in NaCa{sub 3}Bi{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F and NaCa{sub 3}La{sub 0.95}Eu{sub 0.05}(PO{sub 4}){sub 3}F. This difference in Eu{sup 3+} PL emission can be attributed to the difference in its site occupancy in the studied fluorapatites.

  8. Bombing Alone: Tracing the Motivations and Antecedent Behaviors of Lone-Actor Terrorists*,†,‡

    PubMed Central

    Gill, Paul; Horgan, John; Deckert, Paige

    2014-01-01

    This article analyzes the sociodemographic network characteristics and antecedent behaviors of 119 lone-actor terrorists. This marks a departure from existing analyses by largely focusing upon behavioral aspects of each offender. This article also examines whether lone-actor terrorists differ based on their ideologies or network connectivity. The analysis leads to seven conclusions. There was no uniform profile identified. In the time leading up to most lone-actor terrorist events, other people generally knew about the offender’s grievance, extremist ideology, views, and/or intent to engage in violence. A wide range of activities and experiences preceded lone actors’ plots or events. Many but not all lone-actor terrorists were socially isolated. Lone-actor terrorists regularly engaged in a detectable and observable range of activities with a wider pressure group, social movement, or terrorist organization. Lone-actor terrorist events were rarely sudden and impulsive. There were distinguishable behavioral differences between subgroups. The implications for policy conclude this article. PMID:24313297

  9. Bombing alone: tracing the motivations and antecedent behaviors of lone-actor terrorists,.

    PubMed

    Gill, Paul; Horgan, John; Deckert, Paige

    2014-03-01

    This article analyzes the sociodemographic network characteristics and antecedent behaviors of 119 lone-actor terrorists. This marks a departure from existing analyses by largely focusing upon behavioral aspects of each offender. This article also examines whether lone-actor terrorists differ based on their ideologies or network connectivity. The analysis leads to seven conclusions. There was no uniform profile identified. In the time leading up to most lone-actor terrorist events, other people generally knew about the offender's grievance, extremist ideology, views, and/or intent to engage in violence. A wide range of activities and experiences preceded lone actors' plots or events. Many but not all lone-actor terrorists were socially isolated. Lone-actor terrorists regularly engaged in a detectable and observable range of activities with a wider pressure group, social movement, or terrorist organization. Lone-actor terrorist events were rarely sudden and impulsive. There were distinguishable behavioral differences between subgroups. The implications for policy conclude this article.

  10. Interpersonal Problems of People Who Describe Themselves as Lonely.

    ERIC Educational Resources Information Center

    French, Rita de Sales; Horowitz, Leonard M.

    1979-01-01

    The complaint "I am lonely" summarizes specific interpersonal difficulties in socializing. The UCLA Loneliness Scale identifies lonely and not-lonely students who described their major interpersonal problems by performing a Q-sort with a standardized set of problems. Results show that lonely people consistently report problems of…

  11. Lone-Actor Terrorist Target Choice.

    PubMed

    Gill, Paul; Corner, Emily

    2016-09-01

    Lone-actor terrorist attacks have risen to the forefront of the public's consciousness in the past few years. Some of these attacks were conducted against public officials. The rise of hard-to-detect, low-tech attacks may lead to more public officials being targeted. This paper explores whether different behavioral traits are apparent within a sample of lone-actor terrorists who plotted against high-value targets (including public officials) than within a sample of lone actors who plotted against members of the public. Utilizing a unique dataset of 111 lone-actor terrorists, we test a series of hypotheses related to attack capability and operational security. The results indicate that very little differentiates those who attack high-value targets from those who attack members of the public. We conclude with a series of illustrations to theorize why this may be the case. Copyright © 2016 John Wiley & Sons, Ltd.

  12. 3-Picoline mediated self-assembly of M(II)-malonate complexes (M = Ni/Co/Mn/Mg/Zn/Cu) assisted by various weak forces involving lone pair-π, π-π, and anion···π-hole interactions.

    PubMed

    Mitra, Monojit; Manna, Prankrishna; Bauzá, Antonio; Ballester, Pablo; Seth, Saikat Kumar; Ray Choudhury, Somnath; Frontera, Antonio; Mukhopadhyay, Subrata

    2014-12-18

    Five M(II)-malonate complexes having a common formula (C(6)H(9)N(2))(4)[M(II)(C(3)H(2)O(4))(2)(H(2)O)(2)](PF(6))(2).(H(2)O)(2) (1-5) [where C(6)H(9)N(2) = protonated 3-picoline, M(II) = Ni/Co/Mn/Mg/Zn, C(3)H(4)O(4) = malonic acid, and PF(6)(-) = hexafluorophospahte], have been synthesized and their crystal structures have been determined. Complexes 1-5 were found to be isostructural and protonated 3-picoline has primarily mediated the self-assembly process. Role of a discrete water dimer in complexes 1-5 was also studied. Weaker π-interactions have also played crucial role in stabilizing 1D chain constructed by discrete [M(II)(C(3)H(2)O(4))(2)(H(2)O)(2)] units. An additional copper complex namely, (C(6)H(9)N(2))(4)[Cu(C(3)H(2)O(4))(2)](PF(6))(2) (6) has been synthesized from the same reagents and was found to have a completely different structure from the others. Structures of all the complexes are fully described and compared here. Moreover, the lone pair-π and π-π noncovalent interactions have been analyzed by means of DFT calculations, mainly focusing our attention to the influence of the coordinating metal on the strength of the interactions and the interplay between hydrogen bonding and π-interactions. We also present here Hirshfeld surface analysis to investigate the close intermolecular contacts.

  13. State Regulation, Family Breakdown, and Lone Motherhood

    PubMed Central

    Meek, Jeff

    2014-01-01

    Using a range of parish records, records from the Registrar General of Scotland, charity organizations, and media reports, this article contributes to the historiography which evaluates the effects of World War I in Britain as well as the history of lone mothers and their children. It highlights how during the war, women, especially lone mothers, made significant gains through the welfare system, changing approaches to illegitimacy and the plentiful nature of women’s work but also how in doing so this brought them under greater surveillance by the state, local parishes, and charity organizations. Moreover, as this article will demonstrate, many of the gains made by women were short-lived and in fact the war contributed to high levels of family breakdown and gendered and intergenerational poverty endured by lone mothers and their children. PMID:26538794

  14. Lone, Mobile Left Atrial Hydatid Cyst

    PubMed Central

    Ugurlu, Mehmet; Baktir, Ahmet Oguz; Tekin, Ali Ihsan; Tok, Ahmet; Yagmur, Bayram

    2016-01-01

    Echinococcosis is endemic in various regions of Turkey. Cardiac involvement in echinococcosis is rare, and lone cardiac hydatid cysts are even more unusual. Because cardiac hydatid disease can be fatal, even asymptomatic patients are optimally referred for surgical treatment. We present a rare case of a lone, primary, mobile hydatid cyst in the left atrium of a 62-year-old woman. The cyst caused dyspnea from left ventricular inflow obstruction. In addition to reporting the patient's fatal case, we discuss cardiac hydatid cysts in terms of the scant medical literature. PMID:27303247

  15. Low-temperature crystal structures of stibnite implying orbital overlap of Sb 5s2 inert pair electrons

    NASA Astrophysics Data System (ADS)

    Kyono, A.; Kimata, M.; Matsuhisa, M.; Miyashita, Y.; Okamoto, K.

    The crystal structure of stibnite [Sb2S3, Pnma, a=11.314(2), b=3.837(2), c=11.234(3) Å, V= 487.7(3) Å3 at 293 K] was refined in situ at 230, 173, and 128 K. It is a major characteristic of the structure that the Sb-S secondary bonds enclosing Sb 5s2 inert lone-pair electrons at 293 K are significantly shorter than the corresponding sum of the Sb and S van der Waals radii. Concerning the temperature dependence, although both the polyhedral volume and the cation eccentricity of the two SbS7 polyhedra exhibit continuous contractions with decreasing temperature, the sphericity values remain constant, indicating isotropic shrinkage. Consequently, the geometries of Sb 5s2 inert lone-pair electrons and ligand atoms remain unchanged at low temperatures. This is because the crystal structure of stibnite at low temperature induces contraction with attractive interactions, which is called the orbital overlap between Sb 5s2 inert lone-pair electrons and ligand orbitals to maintain the coordination environment. In this case, Sb 5s2 lone-pair electrons are not inert, but active. Such orbital overlaps of inert lone-electron pairs can provide a reasonable explanation for shorter secondary bonds and lower band gap energy of the binary compounds containing heavy elements such as Sb, Te, Pb, and Bi, which are key factors in tracing the origins of color, luster, and semiconductivity of their minerals or compounds.

  16. Why do the lonely stay lonely? Chronically lonely adolescents' attributions and emotions in situations of social inclusion and exclusion.

    PubMed

    Vanhalst, Janne; Soenens, Bart; Luyckx, Koen; Van Petegem, Stijn; Weeks, Molly S; Asher, Steven R

    2015-11-01

    The goal of this study was to identify mechanisms associated with chronic loneliness by examining the effect of adolescents' accumulated history of loneliness on responses to new social situations. Specifically, this study investigated whether attributions and emotions in situations of social inclusion and exclusion differ between chronically lonely adolescents and adolescents with a different loneliness history. A total of 730 adolescents (Mage at Wave 1 = 15.43 years) participated in a 4-wave longitudinal study with annual loneliness assessments. A chronic loneliness trajectory was identified, in addition to low-stable, moderate-stable, moderate-increasing, and high-decreasing loneliness trajectories. At Wave 4, vignettes depicting social inclusion and exclusion were presented, and participants rated a set of attributions and emotions following each vignette. Compared with individuals following other trajectories, chronically lonely adolescents were characterized by hypersensitivity to social exclusion (i.e., higher levels of negative emotions) and hyposensitivity to social inclusion (i.e., lower levels of enthusiasm). Further, chronically lonely adolescents had a stronger tendency to attribute social inclusion to circumstantial factors and social exclusion to internal and stable characteristics. This maladaptive attribution style partially mediated their emotional experiences. Together, results indicate that chronically lonely individuals respond to social situations in ways that may perpetuate rather than reduce their loneliness.

  17. The Lone Wolf Threat: A Different Approach

    DTIC Science & Technology

    2016-03-24

    intelligence communities and law enforcement agencies can employ asymmetric strategic approaches to aid in interdicting the lone wolf terrorist. 15...and a Golden Moment is identified in which intelligence communities and law enforcement agencies can employ asymmetric strategic approaches to aid ...and model presented in the thesis will further aid homeland security entities in combating this asymmetric threat. 40    CHAPTER 7: CONCLUSION

  18. The pursuit of happiness can be lonely.

    PubMed

    Mauss, Iris B; Savino, Nicole S; Anderson, Craig L; Weisbuch, Max; Tamir, Maya; Laudenslager, Mark L

    2012-10-01

    Few things seem more natural and functional than wanting to be happy. We suggest that, counter to this intuition, valuing happiness may have some surprising negative consequences. Specifically, because striving for personal gains can damage connections with others and because happiness is usually defined in terms of personal positive feelings (a personal gain) in western contexts, striving for happiness might damage people's connections with others and make them lonely. In 2 studies, we provide support for this hypothesis. Study 1 suggests that the more people value happiness, the lonelier they feel on a daily basis (assessed over 2 weeks with diaries). Study 2 provides an experimental manipulation of valuing happiness and demonstrates that inducing people to value happiness leads to relatively greater loneliness, as measured by self-reports and a hormonal index (progesterone). In each study, key potential confounds, such as positive and negative affect, were ruled out. These findings suggest that wanting to be happy can make people lonely.

  19. Numerical Analysis on Adsorption Characteristics of Activated Carbon/Ethanol Pair in Finned Tube Type Adsorber

    NASA Astrophysics Data System (ADS)

    Makimoto, Naoya; Kariya, Keishi; Koyama, Shigeru

    The cycle performance of adsorption cooling system depends on the thermophysical properties of the adsorbent/refrigerant pair and configuration of the adsorber/desorber heat exchanger. In this study, a twodimensional analysis is carried out in order to clarify the performance of the finned tube type adsorber/desorber heat exchanger using a highly porous activated carbon powder (ACP)/ethanol pair. The simulation results show that the average cooling capacity per unit volume of adsorber/desorber heat exchanger and coefficient of performance (COP) can be improved by optimizing fin thickness, fin height, fin pitch and tube diameter. The performance of a single stage adsorption cooling system using ACP/ethanol pair is also compared with that of activated carbon fiber (ACF)/ethanol pair. It is found that the cooling capacities of each adsorbent/refrigerant pair increase with the decrease of adsorption/desorption time and the cooling capacity of ACP/ethanol pair is approximately 2.5 times as much as that of ACF/ethanol pair. It is also shown that COP of ACP/ethanol pair is superior to that of ACF/ethanol pair.

  20. Fundamental aspects of recoupled pair bonds. I. Recoupled pair bonds in carbon and sulfur monofluoride

    SciTech Connect

    Dunning, Thom H. Xu, Lu T.; Takeshita, Tyler Y.

    2015-01-21

    The number of singly occupied orbitals in the ground-state atomic configuration of an element defines its nominal valence. For carbon and sulfur, with two singly occupied orbitals in their {sup 3}P ground states, the nominal valence is two. However, in both cases, it is possible to form more bonds than indicated by the nominal valence—up to four bonds for carbon and six bonds for sulfur. In carbon, the electrons in the 2s lone pair can participate in bonding, and in sulfur the electrons in both the 3p and 3s lone pairs can participate. Carbon 2s and sulfur 3p recoupled pair bonds are the basis for the tetravalence of carbon and sulfur, and 3s recoupled pair bonds enable sulfur to be hexavalent. In this paper, we report generalized valence bond as well as more accurate calculations on the a{sup 4}Σ{sup −} states of CF and SF, which are archetypal examples of molecules that possess recoupled pair bonds. These calculations provide insights into the fundamental nature of recoupled pair bonds and illustrate the key differences between recoupled pair bonds formed with the 2s lone pair of carbon, as a representative of the early p-block elements, and recoupled pair bonds formed with the 3p lone pair of sulfur, as a representative of the late p-block elements.

  1. Identification of orthologous target pairs with shared active compounds and comparison of organism-specific activity patterns.

    PubMed

    Dimova, Dilyana; Stumpfe, Dagmar; Bajorath, Jürgen

    2015-11-01

    A systematic search for active small molecules shared by orthologous targets was carried out, leading to the identification of 803 compound-based orthologous target pairs covering a total of 938 orthologues, 358 unique targets and 98 organisms. Many orthologous target pairs were found to have substantial compound coverage, enabling the introduction of an orthologous target pairs classification including 'organism cliffs' and 'potency-retaining' pairs. A total of 158 orthologous target pairs involving human orthologues were identified, which were typically associated with drug discovery-relevant targets, organism combinations and compound data. Orthologous target pairs with human orthologues included 83 potency-retaining orthologous target pairs covering a variety of targets and organisms. On the basis of these orthologous target pairs, the compound search was further extended and 1149 potent compounds were identified that only had reported activities for non-human orthologues of 48 therapeutic targets, but not their human counterparts, hence providing a large pool of candidate compounds for further evaluation. The complete set of orthologous target pairs identified in our analysis, the orthologous target pairs classification including associated data and all candidate compounds are made freely available.

  2. The violent true believer as a "lone wolf" - psychoanalytic perspectives on terrorism.

    PubMed

    Reid Meloy, J; Yakeley, Jessica

    2014-01-01

    The existing research on lone wolf terrorists and case experience are reviewed and interpreted through the lens of psychoanalytic theory. A number of characteristics of the lone wolf are enumerated: a personal grievance and moral outrage; the framing of an ideology; failure to affiliate with an extremist group; dependence on a virtual community found on the Internet; the thwarting of occupational goals; radicalization fueled by changes in thinking and emotion - including cognitive rigidity, clandestine excitement, contempt, and disgust - regardless of the particular ideology; the failure of sexual pair bonding and the sexualization of violence; the nexus of psychopathology and ideology; greater creativity and innovation than terrorist groups; and predatory violence sanctioned by moral (superego) authority. A concluding psychoanalytic formulation is offered.

  3. LONE PEAK WILDERNESS STUDY AREA, UTAH.

    USGS Publications Warehouse

    Bromfield, Calvin S.; Patten, Lowell L.

    1984-01-01

    On the basis of a mineral survey, three areas in the Lone Peak Wilderness study area, Utah are classed as having mineral-resource potential. These include the Silver Creek district, near the east boundary of the area, the Alpine district near the southwest boundary, and the White Pine Fork area in the northeast part of the area. The Silver Creek and Alpine districts have probable potential for small deposits of silver, lead, zinc and, in addition, the Silver Creek district has a probable potential for small tungsten deposits. Of more significance, the White Pine Fork area has a probable potential for porphyry-type molybdenum resources.

  4. Sex differences in Portuguese lonely hearts advertisements.

    PubMed

    Neto, Félix

    2005-10-01

    Advertisements from "Lonely Hearts" columns in the major daily Portuguese newspaper (Jornal de Notícias) were used to test hypotheses about the mate preferences of men and women. A total of 484 advertisements were coded for demographic descriptors and offers of and appeals for attractiveness, financial security, sincerity, expressiveness, and instrumentality, e.g., intelligence and ambition. Some results supported social exchange and evolutionary predictions: men sought younger women and offered security; women sought older men with status and resources. However, other results challenged such predictions: attractiveness and expressiveness did not differ by sex.

  5. Modeling meiotic chromosome pairing: nuclear envelope attachment, telomere-led active random motion, and anomalous diffusion

    NASA Astrophysics Data System (ADS)

    Marshall, Wallace F.; Fung, Jennifer C.

    2016-04-01

    The recognition and pairing of homologous chromosomes during meiosis is a complex physical and molecular process involving a combination of polymer dynamics and molecular recognition events. Two highly conserved features of meiotic chromosome behavior are the attachment of telomeres to the nuclear envelope and the active random motion of telomeres driven by their interaction with cytoskeletal motor proteins. Both of these features have been proposed to facilitate the process of homolog pairing, but exactly what role these features play in meiosis remains poorly understood. Here we investigate the roles of active motion and nuclear envelope tethering using a Brownian dynamics simulation in which meiotic chromosomes are represented by a Rouse polymer model subjected to tethering and active forces at the telomeres. We find that tethering telomeres to the nuclear envelope slows down pairing relative to the rates achieved by unattached chromosomes, but that randomly directed active forces applied to the telomeres speed up pairing dramatically in a manner that depends on the statistical properties of the telomere force fluctuations. The increased rate of initial pairing cannot be explained by stretching out of the chromosome conformation but instead seems to correlate with anomalous diffusion of sub-telomeric regions.

  6. Modeling meiotic chromosome pairing: nuclear envelope attachment, telomere-led active random motion, and anomalous diffusion

    PubMed Central

    Marshall, Wallace F.; Fung, Jennifer C.

    2016-01-01

    The recognition and pairing of homologous chromosomes during meiosis is a complex physical and molecular process involving a combination of polymer dynamics and molecular recognition events. Two highly conserved features of meiotic chromosome behavior are the attachment of telomeres to the nuclear envelope and the active random motion of telomeres driven by their interaction with cytoskeletal motor proteins. Both of these features have been proposed to facilitate the process of homolog pairing, but exactly what role these features play in meiosis remains poorly understood. Here we investigate the roles of active motion and nuclear envelope tethering using a Brownian dynamics simulation in which meiotic chromosomes are represented by a Rouse polymer model subjected to tethering and active forces at the telomeres. We find that tethering telomeres to the nuclear envelope slows down pairing relative to the rates achieved by un-attached chromosomes, but that randomly-directed active forces applied to the telomeres speeds up pairing dramatically in a manner that depends on the statistical properties of the telomere force fluctuations. The increased rate of initial pairing cannot be explained by stretching out of the chromosome conformation but instead seems to correlate with anomalous diffusion of sub-telomeric regions. PMID:27046097

  7. A survey of the lone pair effect on the ring geometry of 1,2,4-triazoles and analogous 1,2,3-triazoles and imidazoles. The structures of 1-methyl-5-amino-3-methylthio-1,2,4-triazole, 1-phenyl-5-amino-3-methylthio-1,2,4-triazole and 1-(4-methylbenzyl)-3-amino-5-methylthio-1,2,4-triazole

    NASA Astrophysics Data System (ADS)

    Kálmán, A.; Argay, Gy.

    1983-11-01

    The structures of the title compounds have been established by X-ray crystallography from diffractometer data. Crystals of the first ( I), C 4H 8N 4S, are monoclinic, space group P2 1/ c, with a = 8.166(2), b = 10.481(1), c = 8.585(1) Å, β = 109.33(2)°, Z = 4, D c = 1.381 g cm -3. Crystals of the second ( II), C 9H 10N 4S, are monoclinic, space group P2 1/ c, with a = 11.850(4), b = 7.898(1), c = 23.981 (6) Å, β = 117.23(2)°, Z = 8, D c = 1.373 g cm -3. Crystals of the third ( III), C 11H 14N 4S 1 are also monoclinic, space group P2 1/ c with a = 12.829(3), b = 8.348(1), c = 11.088(4) Å, β = 94.40(4)°, Z = 4, Dc = 1.314 g cm -3. The structures, determined by direct methods ( I, III) and Patterson synthesis ( II) were refined to R = 0.039 for 1070 reflections of I, R = 0.040 for 2792 reflections of II and R = 0.041 for 1900 reflections of III. The characteristic features of the planar five-membered rings are studied in comparison with the analogous 1,2,3-triazoles and imidazoles. It is shown that these planar rings exhibit only two patterns of the endocyclic bond angles induced dominantly by the number and relative position of the N-lone pairs. A similar effect of the double bonds (attached to C atoms) is also discussed.

  8. MOTOR DEVELOPMENT AND PHYSICAL ACTIVITY: A LONGITUDINAL DISCORDANT TWIN-PAIR STUDY

    PubMed Central

    Aaltonen, Sari; Latvala, Antti; Rose, Richard J.; Pulkkinen, Lea; Kujala, Urho M.; Kaprio, Jaakko; Silventoinen, Karri

    2015-01-01

    Introduction Previous longitudinal research suggests that motor proficiency in early life predicts physical activity in adulthood. Familial effects including genetic and environmental factors could explain the association, but no long-term follow-up studies have taken into account potential confounding by genetic and social family background. The present twin study investigated whether childhood motor skill development is associated with leisure-time physical activity levels in adulthood independent of family background. Methods Altogether, 1 550 twin pairs from the FinnTwin12 study and 1 752 twin pairs from the FinnTwin16 study were included in the analysis. Childhood motor development was assessed by the parents’ report of whether one of the co-twins had been ahead of the other in different indicators of motor skill development in childhood. Leisure-time physical activity (MET hours/day) was self-reported by the twins in young adulthood and adulthood. Statistical analyses included conditional and ordinary linear regression models within twin pairs. Results Using all activity-discordant twin pairs, the within-pair difference in a sum score of motor development in childhood predicted the within-pair difference in the leisure-time physical activity level in young adulthood (p<0.001). Within specific motor development indicators, learning to stand unaided earlier in infancy predicted higher leisure-time MET values in young adulthood statistically significantly in both samples (FinnTwin12 p=0.02, FinnTwin16 p=0.001) and also in the pooled dataset of the FinnTwin12 and FinnTwin16 studies (p<0.001). Having been more agile than the co-twin as a child predicted higher leisure-time MET values up to adulthood (p=0.03). Conclusions More advanced childhood motor development is associated with higher leisure-time MET values in young adulthood at least partly independent of family background, in both men and women. PMID:26378945

  9. EFFECTS OF DIFFERENT REST INTERVALS BETWEEN ANTAGONIST PAIRED SETS ON REPETITION PERFOMANCE AND MUSCLE ACTIVATION.

    PubMed

    de Freitas Maia, Marianna; Willardson, Jeffrey M; Paz, Gabriel Andrade; Miranda, Humberto

    2014-03-11

    Recent evidence suggests that exercising the antagonist musculature acutely enhances subsequent performance for the agonist musculature. The purpose of the current study was to examine the effects of different rest intervals between sets for exercises that involve antagonistic muscle groups; a technique referred to as antagonist paired sets (APS). Fifteen recreationally-trained men were tested for knee extension (KE) exercise performance, with or without prior knee flexion (KF) exercise for the antagonist musculature. The following protocols were performed in random order and with 10 repetition maximum (10RM) loads for the KF and KE exercises: 1) traditional protocol (TP) - one set of KE only to repetition failure; 2) paired sets with minimal allowable rest (PMR) - one set of KF followed immediately by a set of KE; 3) P30 - 30 seconds rest between paired sets of KF and KE; 4) P1 - 1-minute rest between paired sets; 5) P3 - 3-minutes rest between paired sets; and 6) P5 - 5-minutes rest between paired sets. The number of repetitions performed and EMG activity of vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles were recorded during the KE set in each protocol. It was demonstrated that significantly greater KE repetitions were completed during the PMR, P30 and P1 protocols versus the TP protocol. Significantly greater EMG activity was demonstrated for the RF muscle during the KE exercise in the PMR and P30 versus the TP, P3 and P5, respectively. In addition, significantly greater EMG activity was demonstrated for the VM muscle during the PMR versus all other protocols. The results of the current study indicate that no rest or relatively shorter rest intervals (30 sec and 1 min) between APS might be more effective to elicit greater agonist repetition enhancement and muscle activation.

  10. Effects of different rest intervals between antagonist paired sets on repetition performance and muscle activation.

    PubMed

    Maia, Marianna F; Willardson, Jeffrey M; Paz, Gabriel A; Miranda, Humberto

    2014-09-01

    Recent evidence suggests that exercising the antagonist musculature acutely enhances subsequent performance for the agonist musculature. The purpose of this study was to examine the effects of different rest intervals between sets for exercises that involve antagonistic muscle groups, a technique referred to as antagonist paired sets (APS). Fifteen recreationally trained men were tested for knee extension (KE) exercise performance, with or without previous knee flexion (KF) exercise for the antagonist musculature. The following protocols were performed in random order with 10 repetition maximum loads for the KF and KE exercises: (a) traditional protocol (TP)-1 set of KE only to repetition failure; (b) paired sets with minimal allowable rest (PMR)-1 set of KF followed immediately by a set of KE; (c) P30-30-second rest between paired sets of KF and KE; (d) P1-1-minute rest between paired sets; (e) P3-3-minute rest between paired sets; and (f) P5-5-minute rest between paired sets. The number of repetitions performed and electromyographic (EMG) activity of vastus lateralis, vastus medialis (VM), and rectus femoris (RF) muscles were recorded during the KE set in each protocol. It was demonstrated that significantly greater KE repetitions were completed during the PMR, P30, and P1 protocols vs. the TP protocol. Significantly greater EMG activity was demonstrated for the RF muscle during the KE exercise in the PMR and P30 vs. the TP, P3, and P5, respectively. In addition, significantly greater EMG activity was demonstrated for the VM muscle during the PMR vs. all other protocols. The results of this study indicate that no rest or relatively shorter rest intervals (30 seconds and 1 minute) between APS might be more effective to elicit greater agonist repetition enhancement and muscle activation.

  11. A false dichotomy? Mental illness and lone-actor terrorism.

    PubMed

    Corner, Emily; Gill, Paul

    2015-02-01

    We test whether significant differences in mental illness exist in a matched sample of lone- and group-based terrorists. We then test whether there are distinct behavioral differences between lone-actor terrorists with and without mental illness. We then stratify our sample across a range of diagnoses and again test whether significant differences exist. We conduct a series of bivariate, multivariate, and multinomial statistical tests using a unique dataset of 119 lone-actor terrorists and a matched sample of group-based terrorists. The odds of a lone-actor terrorist having a mental illness is 13.49 times higher than the odds of a group actor having a mental illness. Lone actors who were mentally ill were 18.07 times more likely to have a spouse or partner who was involved in a wider movement than those without a history of mental illness. Those with a mental illness were more likely to have a proximate upcoming life change, more likely to have been a recent victim of prejudice, and experienced proximate and chronic stress. The results identify behaviors and traits that security agencies can utilize to monitor and prevent lone-actor terrorism events. The correlated behaviors provide an image of how risk can crystalize within the individual offender and that our understanding of lone-actor terrorism should be multivariate in nature.

  12. Quantitative structure-activity relationship models of chemical transformations from matched pairs analyses.

    PubMed

    Beck, Jeremy M; Springer, Clayton

    2014-04-28

    The concepts of activity cliffs and matched molecular pairs (MMP) are recent paradigms for analysis of data sets to identify structural changes that may be used to modify the potency of lead molecules in drug discovery projects. Analysis of MMPs was recently demonstrated as a feasible technique for quantitative structure-activity relationship (QSAR) modeling of prospective compounds. Although within a small data set, the lack of matched pairs, and the lack of knowledge about specific chemical transformations limit prospective applications. Here we present an alternative technique that determines pairwise descriptors for each matched pair and then uses a QSAR model to estimate the activity change associated with a chemical transformation. The descriptors effectively group similar transformations and incorporate information about the transformation and its local environment. Use of a transformation QSAR model allows one to estimate the activity change for novel transformations and therefore returns predictions for a larger fraction of test set compounds. Application of the proposed methodology to four public data sets results in increased model performance over a benchmark random forest and direct application of chemical transformations using QSAR-by-matched molecular pairs analysis (QSAR-by-MMPA).

  13. Chemical Genetics: receptor-ligand pairs for rapid manipulation of neuronal activity

    PubMed Central

    Wulff, Peer; Arenkiel, Benjamin R.

    2012-01-01

    Towards the functional dissection of neuronal circuits, a number of new genetic tools have been developed that enable rapid and reversible manipulation of genetically defined neuronal subtypes in intact mammalian brain circuits. Alongside the breakthrough technology of optogenetics, receptor-ligand pairs provide complementary approaches to modulate neuronal activity using chemical-genetics. PMID:22119143

  14. Identity in Activity: Examining Teacher Professional Identity Formation in the Paired-Placement of Student Teachers

    ERIC Educational Resources Information Center

    Dang, Thi Kim Anh

    2013-01-01

    This paper examines the evolution of the professional identities of student teachers (STs) in a paired-placement teaching practicum in Vietnam. The study draws on activity theory, its notion of contradiction, and Vygotsky's concepts of ZPD and "perezhivanie", to identify the factors driving the intricate learning process. Opportunities…

  15. 75 FR 81442 - Revocation of Class E Airspace; Lone Star, TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-28

    ... Federal Aviation Administration 14 CFR Part 71 Revocation of Class E Airspace; Lone Star, TX AGENCY... airspace at Lone Star, TX. Abandonment of the former Lone Star Steel Company ] Airport and cancellation of... the Lone Star, TX, area. The FAA is taking this action to ensure the efficient use of airspace...

  16. 75 FR 64972 - Proposed Revocation of Class E Airspace; Lone Star, TX

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-21

    ... Federal Aviation Administration 14 CFR Part 71 Proposed Revocation of Class E Airspace; Lone Star, TX...: This action proposes to remove Class E airspace at Lone Star, TX. Abandonment of the former Lone Star... eliminated the need for controlled airspace in the Lone Star, TX, area. The FAA is taking this action...

  17. 26. LONE CONE AND OLD ROAD GRADE TO LEFT SEEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. LONE CONE AND OLD ROAD GRADE TO LEFT SEEN FROM PARKING LOT ADJACENT TO LAUNDROMAT AT MOREFIELD CAMPGROUND STORE, FACING NW. - Mesa Verde National Park Main Entrance Road, Cortez, Montezuma County, CO

  18. Brain Activation during Memory Encoding in Type 2 Diabetes Mellitus: A Discordant Twin Pair Study

    PubMed Central

    Wood, Amanda G.; Chen, Jian; Moran, Christopher; Phan, Thanh; Beare, Richard; Cooper, Kimberley; Litras, Stacey; Srikanth, Velandai

    2016-01-01

    Type 2 diabetes mellitus increases the risk of dementia and neuronal dysfunction may occur years before perceptible cognitive decline. We aimed to study the impact of type 2 diabetes on brain activation during memory encoding in middle-aged people, controlling for age, sex, genes, and early-shared environment. Twenty-two twin pairs discordant for type 2 diabetes mellitus (mean age 60.9 years) without neurological disease were recruited from the Australian Twin Registry (ATR) and underwent functional magnetic resonance imaging (fMRI) during a memory encoding task, cognitive tests, and structural MRI. Type 2 diabetes was associated with significantly reduced activation in left hemisphere temporoparietal regions including angular gyrus, supramarginal gyrus, and middle temporal gyrus and significantly increased activation in bilateral posteriorly distributed regions. These findings were present in the absence of within-pair differences in standard cognitive test scores, brain volumes, or vascular lesion load. Differences in activation were more pronounced among monozygotic (MZ) pairs, with MZ individuals with diabetes also displaying greater frontal activation. These results provide evidence for preclinical memory-related neuronal dysfunction in type 2 diabetes. They support the search for modifiable later-life environmental factors or epigenetic mechanisms linking type 2 diabetes and cognitive decline. PMID:27314047

  19. The Mystery of the Lonely Neutron Star

    NASA Astrophysics Data System (ADS)

    2000-09-01

    The VLT Reveals Bowshock Nebula around RX J1856.5-3754 Deep inside the Milky Way, an old and lonely neutron star plows its way through interstellar space. Known as RX J1856.5-3754 , it measures only ~ 20 km across. Although it is unusually hot for its age, about 700,000 °C, earlier observations did not reveal any activity at all, contrary to all other neutron stars known so far. In order to better understand this extreme type of object, a detailed study of RX J1856.5-3754 was undertaken by Marten van Kerkwijk (Institute of Astronomy of the University of Utrecht, The Netherlands) and Shri Kulkarni (California Institute of Technology, Pasadena, California, USA). To the astronomers' delight and surprise, images and spectra obtained with the ESO Very Large Telescope (VLT) now show a small nearby cone-shaped ("bowshock") nebula. It shines in the light from hydrogen atoms and is obviously a product of some kind of interaction with this strange star. Neutron stars - remnants of supernova explosions Neutron stars are among the most extreme objects in the Universe. They are formed when a massive star dies in a "supernova explosion" . During this dramatic event, the core of the star suddenly collapses under its own weight and the outer parts are violently ejected into surrounding space. One of the best known examples is the Crab Nebula in the constellation Taurus (The Bull). It is the gaseous remnant of a star that exploded in the year 1054 and also left behind a pulsar , i.e., a rotating neutron star [1]. A supernova explosion is a very complex event that is still not well understood. Nor is the structure of a neutron star known in any detail. It depends on the extreme properties of matter that has been compressed to incredibly high densities, far beyond the reach of physics experiments on Earth [2]. The ultimate fate of a neutron star is also unclear. From the observed rates of supernova explosions in other galaxies, it appears that several hundred million neutron stars

  20. Nonlinear parametrically excited vibration and active control of gear pair system with time-varying characteristic

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Wang, Jin-Jin; Liu, Jin-Jie; Li, Ya-Qian

    2015-10-01

    In the present work, we investigate the nonlinear parametrically excited vibration and active control of a gear pair system involving backlash, time-varying meshing stiffness and static transmission error. Firstly, a gear pair model is established in a strongly nonlinear form, and its nonlinear vibration characteristics are systematically investigated through different approaches. Several complicated phenomena such as period doubling bifurcation, anti period doubling bifurcation and chaos can be observed under the internal parametric excitation. Then, an active compensation controller is designed to suppress the vibration, including the chaos. Finally, the effectiveness of the proposed controller is verified numerically. Project supported by the National Natural Science Foundation of China (Grant No. 61104040), the Natural Science Foundation of Hebei Province, China (Grant No. E2012203090), and the University Innovation Team of Hebei Province Leading Talent Cultivation Project, China (Grant No. LJRC013).

  1. Lewis Acid Pairs for the Activation of Biomass-derived Oxygenates in Aqueous Media

    SciTech Connect

    Roman, Yuriy

    2015-09-14

    The objective of this project is to understand the mechanistic aspects behind the cooperative activation of oxygenates by catalytic pairs in aqueous media. Specifically, we will investigate how the reactivity of a solid Lewis acid can be modulated by pairing the active site with other catalytic sites at the molecular level, with the ultimate goal of enhancing activation of targeted functional groups. Although unusual catalytic properties have been attributed to the cooperative effects promoted by such catalytic pairs, virtually no studies exist detailing the use heterogeneous water-tolerant Lewis pairs. A main goal of this work is to devise rational pathways for the synthesis of porous heterogeneous catalysts featuring isolated Lewis pairs that are active in the transformation of biomass-derived oxygenates in the presence of bulk water. Achieving this technical goal will require closely linking advanced synthesis techniques; detailed kinetic and mechanistic investigations; strict thermodynamic arguments; and comprehensive characterization studies of both materials and reaction intermediates. For the last performance period (2014-2015), two technical aims were pursued: 1) C-C coupling using Lewis acid and base pairs in Lewis acidic zeolites. Tin-, zirconium-, and hafnium containing zeolites (e.g., Sn-, Zr-, and Hf-Beta) are versatile solid Lewis acids that selectively activate carbonyl functional groups. In this aim, we demonstrate that these zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. 2) One-pot synthesis of MWW zeolite nanosheets for activation of bulky substrates. Through

  2. Motor cortex plasticity induced by paired associative stimulation is enhanced in physically active individuals.

    PubMed

    Cirillo, John; Lavender, Andrew P; Ridding, Michael C; Semmler, John G

    2009-12-15

    Recent evidence indicates that regular physical activity enhances brain plasticity (i.e. the ability to reorganise neural connections) and improves neurocognitive function. However, the effect of regular physical activity on human motor cortex function is unknown. The purpose of this study was to examine motor cortex plasticity for a small hand muscle in highly active and sedentary individuals. Electromyographic recordings were obtained from the left abductor pollicis brevis (APB) muscle of 14 active and 14 sedentary subjects (aged 18-38 yrs). The extent of physical activity was assessed by questionnaire, where the physically active subjects performed >150 min per day moderate-to-vigorous aerobic activity on at least 5 days per week, whereas the sedentary group performed <20 min per day of physical activity on no more than 3 days per week. Transcranial magnetic stimulation (TMS) of the right hemisphere was used to assess changes in APB motor-evoked potentials (MEPs), input-output curve (IO curve), short-interval intracortical inhibition (SICI) and cortical silent period (CSP). Neuroplastic changes were induced using paired-associative stimulation (PAS), which consisted of 90 paired stimuli (0.05 Hz for 30 min) of median nerve electrical stimulation at the wrist followed 25 ms later by TMS to the hand area of motor cortex. The IO curve slope was 35% steeper in individuals with increased physical activity (combined before and after PAS, P < 0.05), suggesting increased motor cortex excitability, although there was no difference in SICI or CSP between groups. PAS induced an increase in MEP amplitude in the physically active subjects (54% increase compared with before, P < 0.01), but no significant facilitation in the sedentary subjects. We conclude that participation in regular physical activity may offer global benefits to motor cortex function that enhances neuroplasticity, which could improve motor learning and neurorehabilitation in physically active individuals.

  3. Decentralized harmonic active vibration control of a flexible plate using piezoelectric actuator-sensor pairs.

    PubMed

    Baudry, Matthieu; Micheau, Philippe; Berry, Alain

    2006-01-01

    We have investigated decentralized active control of periodic panel vibration using multiple pairs combining PZT actuators and PVDF sensors distributed on the panel. By contrast with centralized MIMO controllers used to actively control the vibrations or the sound radiation of extended structures, decentralized control using independent local control loops only requires identification of the diagonal terms in the plant matrix. However, it is difficult to a priori predict the global stability of such decentralized control. In this study, the general situation of noncollocated actuator-sensor pairs was considered. Frequency domain gradient and Newton-Raphson adaptation of decentralized control were analyzed, both in terms of performance and stability conditions. The stability conditions are especially derived in terms of the adaptation coefficient and a control effort weighting coefficient. Simulations and experimental results are presented in the case of a simply supported panel with four PZT-PVDF pairs distributed on it. Decentralized vibration control is shown to be highly dependent on the frequency, but can be as effective as a fully centralized control even when the plant matrix is not diagonal-dominant or is not strictly positive real (not dissipative).

  4. Active vibration control of beams using filtered-velocity feedback controllers with moment pair actuators

    NASA Astrophysics Data System (ADS)

    Shin, Changjoo; Hong, Chinsuk; Jeong, Weui Bong

    2013-06-01

    In this study, filtered-velocity feedback (FVF) control is proposed to stabilize a control system with a non-collocated sensor/actuator configuration. This method is applied to actively control a clamped beam with a sensor/moment pair actuator. Since the sensor/moment pair actuator is a non-collocated configuration, the control system experiences structural instability at high frequencies. Due to the roll-off property of the FVF controller, the high frequency structural instability problem can be overcome. Due to the second-order filter characteristics of the FVF controller, similar to a low pass filter, multimode disturbances can be controlled at the modes below the cut-off frequency. To verify the performance of the controller, the FVF controller is tuned to around 2 kHz, and the structural responses are successfully reduced by numerical and experimental approaches.

  5. Nonthermal electron-positron pairs and cold matter in the central engines of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.

    1992-01-01

    The nonthermal e(+/-) pair model of the central engine of active galactic nuclei (AGNs) is discussed. The model assumes that nonthermal e(+/-) pairs are accelerated to highly relativistic energies in a compact region close to the central black hole and in the vicinity of some cold matter. The model has a small number of free parameters and explains a large body of AGN observations from EUV to soft gamma-rays. In particular, the model explains the existence of the UV bump, the soft X-rays excess, the canonical hard X-ray power law, the spectral hardening above about 10 keV, and some of the variability patterns in the soft and hard X-rays. In addition, the model explains the spectral steepening above about 50 keV seen in NGC 4151.

  6. A community computational challenge to predict the activity of pairs of compounds

    PubMed Central

    Bansal, Mukesh; Yang, Jichen; Karan, Charles; Menden, Michael P; Costello, James C; Tang, Hao; Xiao, Guanghua; Li, Yajuan; Allen, Jeffrey; Zhong, Rui; Chen, Beibei; Kim, Minsoo; Wang, Tao; Heiser, Laura M; Realubit, Ronald; Mattioli, Michela; Alvarez, Mariano J; Shen, Yao; Gallahan, Daniel; Singer, Dinah; Saez-Rodriguez, Julio; Xie, Yang; Stolovitzky, Gustavo; Califano, Andrea

    2015-01-01

    Recent therapeutic successes have renewed interest in drug combinations, but experimental screening approaches are costly and often identify only small numbers of synergistic combinations. The DREAM consortium launched an open challenge to foster the development of in silico methods to computationally rank 91 compound pairs, from the most synergistic to the most antagonistic, based on gene-expression profiles of human B cells treated with individual compounds at multiple time points and concentrations. Using scoring metrics based on experimental dose-response curves, we assessed 32 methods (31 community-generated approaches and SynGen), four of which performed significantly better than random guessing. We highlight similarities between the methods. Although the accuracy of predictions was not optimal, we find that computational prediction of compound-pair activity is possible, and that community challenges can be useful to advance the field of in silico compound-synergy prediction. PMID:25419740

  7. Activation of Carbon Dioxide by Silyl Triflate-Based Frustrated Lewis Pairs.

    PubMed

    Weicker, Sarah A; Stephan, Douglas W

    2015-09-07

    Silyl triflates of the form R4-n Si(OTf)n (n=1, 2; OTf=OSO3 CF3 ) are shown to activate carbon dioxide when paired with bulky alkyl-substituted Group 15 bases. Combinations of silyl triflates and 2,2,6,6-tetramethylpiperidine react with CO2 to afford silyl carbamates via a frustrated Lewis pair-type mechanism. With trialkylphosphines, the silyl triflates R3 Si(OTf) reversibly bind CO2 affording [R'3 P(CO2 )SiR3 ][OTf] whereas when Ph2 Si(OTf)2 is used one or two molecules of CO2 can be sequestered. The latter bis-CO2 product is favoured at low temperatures and by excess phosphine.

  8. Cooperative activation of Xenopus rhodopsin transcription by paired-like transcription factors

    PubMed Central

    2014-01-01

    Background In vertebrates, rod photoreceptor-specific gene expression is regulated by the large Maf and Pax-like transcription factors, Nrl/LNrl and Crx/Otx5. The ubiquitous occurrence of their target DNA binding sites throughout rod-specific gene promoters suggests that multiple transcription factor interactions within the promoter are functionally important. Cooperative action by these transcription factors activates rod-specific genes such as rhodopsin. However, a quantitative mechanistic explanation of transcriptional rate determinants is lacking. Results We investigated the contributions of various paired-like transcription factors and their cognate cis-elements to rhodopsin gene activation using cultured cells to quantify activity. The Xenopus rhodopsin promoter (XOP) has a bipartite structure, with ~200 bp proximal to the start site (RPP) coordinating cooperative activation by Nrl/LNrl-Crx/Otx5 and the adjacent 5300 bp upstream sequence increasing the overall expression level. The synergistic activation by Nrl/LNrl-Crx/Otx5 also occurred when XOP was stably integrated into the genome. We determined that Crx/Otx5 synergistically activated transcription independently and additively through the two Pax-like cis-elements, BAT1 and Ret4, but not through Ret1. Other Pax-like family members, Rax1 and Rax2, do not synergistically activate XOP transcription with Nrl/LNrl and/or Crx/Otx5; rather they act as co-activators via the Ret1 cis-element. Conclusions We have provided a quantitative model of cooperative transcriptional activation of the rhodopsin promoter through interaction of Crx/Otx5 with Nrl/LNrl at two paired-like cis-elements proximal to the NRE and TATA binding site. Further, we have shown that Rax genes act in cooperation with Crx/Otx5 with Nrl/LNrl as co-activators of rhodopsin transcription. PMID:24499263

  9. Bimodal Distribution of Geyser Preplay Eruptions: Lone Star Geyser, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Namiki, A.; Hurwitz, S.; Murphy, F.; Manga, M.

    2014-12-01

    Geyser eruption intervals are determined by rates of water and heat discharge into shallow subsurface reservoirs and the conduit. In some geysers, small amounts of water discharge prior to a main eruption ('Preplay') can affect eruption intervals. Water discharge during preplay reduces the hydrostatic pressure, which in turn, induces boiling of water that is at, or near the critical temperature. Ascending steam slugs from depth can also lead to shorter eruption intervals (Namiki et al., 2014). In April 2014, we carried a five day experiment at Lone Star Geyser, Yellowstone National Park. Eruptions and their preplays were recorded with an infrared sensor that measured temperature variations immediately above the geyser cone (3.4~m high), temperature loggers that measured water temperature at the base of the cone and in the outflow channels, and visual observations. At Lone Star Geyser, during the preplay phase of the eruption, mainly liquid water is erupted, whereas the main phase of the eruption begins with the liquid-water dominated eruption and turns into the steam discharge. The temperature rise in an outflow channel indicates the occurrence of preplays and initiation of the main eruption. The acquired data suggests that the preplay patterns of Lone Star Geyser are vigorous and complex, consistent with previous observations (Karlstrom et al., 2013). Our new observations reveal two typical styles: 1) vigorous preplays with few events (<5) and long intervals (>20~minutes) that last approximately 40~minutes, and 2) less vigorous preplays that include several events (>5) with short intervals (few minutes), and continue approximately for one hour. Probability distributions of preplay durations show two peaks indicating the bimodal activity. The bimodality of Lone Star preplays may be a result of subtle change of temperature distribution in a convecting reservoir which has been observed in laboratory experiments (Toramaru and Maeda, 2013).

  10. Microbial communities and interactions in the lone star tick, Amblyomma americanum.

    PubMed

    Clay, K; Klyachko, O; Grindle, N; Civitello, D; Oleske, D; Fuqua, C

    2008-10-01

    To quantify microbial composition and interactions, we identified prokaryotic communities in the lone star tick (Amblyomma americanum) based on 16S rRNA gene sequences and direct probing. The lone star tick is the vector of emerging diseases and host to additional symbionts of unknown activity, and is representative of other blood-sucking arthropods. We evaluated the potential for vertical (transovarial) transmission by molecular analysis of microbial symbionts from egg and larval clutches. Direct probing of adults (N = 8 populations from the southeastern and midwestern USA, 900 ticks total) revealed three vertically transmitted symbionts: a Coxiella symbiont occurred at 100% frequency, Rickettsia species occurred in 45-61% of all ticks in every population and an Arsenophonus symbiont occurred in 0-90% of ticks per population. Arsenophonus and Rickettsia exhibited significant heterogeneity in frequency among populations. The human pathogens Ehrlichia chafeensis and Borrelia lonestari were rare in most populations. Additional microbes were detected sporadically. Most ticks (78%) were co-infected by two or three microbes but statistical analysis indicated no significant deviation from random co-occurrence. Our findings indicate that microbial communities within lone star ticks are diverse, and suggest that direct probing for a wider range of prokaryotes and application of quantitative polymerase chain reaction (PCR) may provide further insights into microbial interactions within disease vectors. Our results also emphasize the close phylogenetic relationship between tick symbionts and human pathogens, and consistent differences in their prevalence.

  11. Motives for and barriers to physical activity in twin pairs discordant for leisure time physical activity for 30 years.

    PubMed

    Aaltonen, S; Leskinen, T; Morris, T; Alen, M; Kaprio, J; Liukkonen, J; Kujala, U

    2012-02-01

    Long-term persistent physical activity is important in the prevention of chronic diseases, but a large number of people do not participate in physical activity to obtain health benefits. The purpose of this study was to examine the motives and perceived barriers to long-term engagement in leisure time physical activity. Same-sex twin pairs (N=16, mean age 60) discordant for physical activity over 30 years were identified from the Finnish Twin Cohort. We evaluated participants' physical activity motivation with the 73-item Recreational Exercise Motivation Measure and assessed barriers to physical activity with a 25-item questionnaire. The characteristics of physical activity motivation and perceived barriers between the active and inactive co-twins were analysed using paired tests. Motives related to the sub-dimensions of enjoyment and physical fitness and psychological state were the most important reasons for participation in physical activity among all the twin individuals analysed. The sub-dimensions mastery (p=0.018, Cohen's d=0.76), physical fitness (p=0.029, Cohen's d=0.69), and psychological state (p=0.039, Cohen's d=0.65) differed significantly between active and inactive co-twins. More than half of the participants reported no reasons for not being physically active. If reasons existed, participation in physical activity was deterred mostly by pain and various health problems. This study found no differences in perceived barriers between active and inactive co-twins. We conclude from our results that the main factors promoting persistent leisure time physical activity were participants' wish to improve or maintain their physical skills or techniques, a feeling that exercise would improve their mental and physical health and that they found the activity enjoyable. This study helps us understand the importance of the role of motives and the minor role of perceived barriers for engagement in persistent physical activity.

  12. Improved complementary polymer pair system: switching for enzyme activity by PEGylated polymers.

    PubMed

    Kurinomaru, Takaaki; Tomita, Shunsuke; Kudo, Shinpei; Ganguli, Sumon; Nagasaki, Yukio; Shiraki, Kentaro

    2012-03-06

    The development of technology for on/off switching of enzyme activity is expected to expand the applications of enzyme in a wide range of research fields. We have previously developed a complementary polymer pair system (CPPS) that enables the activity of several enzymes to be controlled by a pair of oppositely charged polymers. However, it failed to control the activity of large and unstable α-amylase because the aggregation of the complex between anionic α-amylase and cationic poly(allylamine) (PAA) induced irreversible denaturation of the enzyme. To address this issue, we herein designed and synthesized a cationic copolymer with a poly(ethylene glycol) backbone, poly(N,N-diethylaminoethyl methacrylate)-block-poly(ethylene glycol) (PEAMA-b-PEG). In contrast to PAA, α-amylase and β-galactosidase were inactivated by PEAMA-b-PEG with the formation of soluble complexes. The enzyme/PEAMA-b-PEG complexes were then successfully recovered from the complex by the addition of anionic poly(acrylic acid) (PAAc). Thus, dispersion of the complex by PEG segment in PEAMA-b-PEG clearly plays a crucial role for regulating the activities of these enzymes, suggesting that PEGylated charged polymer is a new candidate for CPPS for large and unstable enzymes.

  13. Wobble Pairs of the HDV Ribozyme Play Specific Roles in Stabilization of Active Site Dynamics

    PubMed Central

    Sripathi, Kamali N.; Banáš, Pavel; Reblova, Kamila; Šponer, Jiři; Otyepka, Michal

    2015-01-01

    The hepatitis delta virus (HDV) is the only known human pathogen whose genome contains a catalytic RNA motif (ribozyme). The overall architecture of the HDV ribozyme is that of a double-nested pseudoknot, with two GU pairs flanking the active site. Although extensive studies have shown that mutation of either wobble results in decreased catalytic activity, little work has focused on linking these mutations to specific structural effects on catalytic fitness. Here we use molecular dynamics simulations based on an activated structure to probe the active site dynamics as a result of wobble pair mutations. In both wild-type and mutant ribozymes, the in-line fitness of the active site (as a measure of catalytic proficiency) strongly depends on the presence of a C75(N3H3+)N1(O5′) hydrogen bond, which positions C75 as the general acid for the reaction. Our mutational analyses show that each GU wobble supports catalytically fit conformations in distinct ways; the reverse G25U20 wobble promotes high in-line fitness, high occupancy of the C75(N3H3+)G1(O5′) general-acid hydrogen bond and stabilization of the G1U37 wobble, while the G1U37 wobble acts more locally by stabilizing high in-line fitness and the C75(N3H3+)G1(O5′) hydrogen bond. We also find that stable type I A-minor and P1.1 hydrogen bonding above and below the active site, respectively, prevent local structural disorder from spreading and disrupting global conformation. Taken together, our results define specific, often redundant architectural roles for several structural motifs of the HDV ribozyme active site, expanding the known roles of these motifs within all HDV-like ribozymes and other structured RNAs. PMID:25631765

  14. The Myth of the Lone Physician: Toward a Collaborative Alternative

    PubMed Central

    Saba, George W.; Villela, Teresa J.; Chen, Ellen; Hammer, Hali; Bodenheimer, Thomas

    2012-01-01

    Cultural values and beliefs about the primary care physician bolster the myth of the lone physician: a competent professional who is esteemed by colleagues and patients for his or her willingness to sacrifice self, accept complete responsibility for care, maintain continuity and accessibility, and assume the role of lone decision maker in clinical care. Yet the reality of current primary care models is often fragmented, impersonal care for patients and isolation and burnout for many primary care physicians. An alternative to the mythological lone physician would require a paradigm shift that places the primary care physician within the context of a highly functioning health care team. This new mythology better fulfills the collaborative, interprofessional, patient-centered needs of new models of care, and might help to ensure that the work of primary care physicians remains compassionate, gratifying, and meaningful. PMID:22412010

  15. Changing notions of lone motherhood in twentieth-century Finland.

    PubMed

    May, Vanessa

    2011-01-01

    Through written life stories of lone mothers, this article examines changes in lone motherhood in twentieth-century Finland. While the older life-story writers' narratives are clearly influenced by an 'ethos of survival' and the regulation of female sexuality, the younger writers relate their experiences with the help of scripts on gender equality and the psychological importance of 'good' parenting. These narrative shifts point to important changes in cultural scripts on women's positions in families, on the labour market, and in society.

  16. A LONE code for the sparse control of quantum systems

    NASA Astrophysics Data System (ADS)

    Ciaramella, G.; Borzì, A.

    2016-03-01

    In many applications with quantum spin systems, control functions with a sparse and pulse-shaped structure are often required. These controls can be obtained by solving quantum optimal control problems with L1-penalized cost functionals. In this paper, the MATLAB package LONE is presented aimed to solving L1-penalized optimal control problems governed by unitary-operator quantum spin models. This package implements a new strategy that includes a globalized semi-smooth Krylov-Newton scheme and a continuation procedure. Results of numerical experiments demonstrate the ability of the LONE code in computing accurate sparse optimal control solutions.

  17. Galaxy and Mass Assembly (GAMA): active galactic nuclei in pairs of galaxies

    NASA Astrophysics Data System (ADS)

    Gordon, Yjan A.; Owers, Matt S.; Pimbblet, Kevin A.; Croom, Scott M.; Alpaslan, Mehmet; Baldry, Ivan K.; Brough, Sarah; Brown, Michael J. I.; Cluver, Michelle E.; Conselice, Christopher J.; Davies, Luke J. M.; Holwerda, Benne W.; Hopkins, Andrew M.; Gunawardhana, Madusha L. P.; Loveday, Jonathan; Taylor, Edward N.; Wang, Lingyu

    2017-03-01

    There exist conflicting observations on whether or not the environment of broad- and narrow-line active galatic nuclei (AGN) differ and this consequently questions the validity of the AGN unification model. The high spectroscopic completeness of the Galaxy and Mass Assembly (GAMA) survey makes it ideal for a comprehensive analysis of the close environment of galaxies. To exploit this, and conduct a comparative analysis of the environment of broad- and narrow-line AGN within GAMA, we use a double-Gaussian emission line fitting method to model the more complex line profiles associated with broad-line AGN. We select 209 type 1 (i.e. unobscured), 464 type 1.5-1.9 (partially obscured), and 281 type 2 (obscured) AGN within the GAMA II data base. Comparing the fractions of these with neighbouring galaxies out to a pair separation of 350 kpc h-1 and Δz < 0.012 shows no difference between AGN of different type, except at separations less than 20 kpc h-1 where our observations suggest an excess of type 2 AGN in close pairs. We analyse the properties of the galaxies neighbouring our AGN and find no significant differences in colour or the star formation activity of these galaxies. Further to this, we find that Σ5 is also consistent between broad- and narrow-line AGN. We conclude that the observations presented here are consistent with AGN unification.

  18. Pairing broadband noise with cortical stimulation induces extensive suppression of ascending sensory activity

    NASA Astrophysics Data System (ADS)

    Markovitz, Craig D.; Hogan, Patrick S.; Wesen, Kyle A.; Lim, Hubert H.

    2015-04-01

    Objective. The corticofugal system can alter coding along the ascending sensory pathway. Within the auditory system, electrical stimulation of the auditory cortex (AC) paired with a pure tone can cause egocentric shifts in the tuning of auditory neurons, making them more sensitive to the pure tone frequency. Since tinnitus has been linked with hyperactivity across auditory neurons, we sought to develop a new neuromodulation approach that could suppress a wide range of neurons rather than enhance specific frequency-tuned neurons. Approach. We performed experiments in the guinea pig to assess the effects of cortical stimulation paired with broadband noise (PN-Stim) on ascending auditory activity within the central nucleus of the inferior colliculus (CNIC), a widely studied region for AC stimulation paradigms. Main results. All eight stimulated AC subregions induced extensive suppression of activity across the CNIC that was not possible with noise stimulation alone. This suppression built up over time and remained after the PN-Stim paradigm. Significance. We propose that the corticofugal system is designed to decrease the brain’s input gain to irrelevant stimuli and PN-Stim is able to artificially amplify this effect to suppress neural firing across the auditory system. The PN-Stim concept may have potential for treating tinnitus and other neurological disorders.

  19. Pairing broadband noise with cortical stimulation induces extensive suppression of ascending sensory activity

    PubMed Central

    Markovitz, Craig D.; Hogan, Patrick S.; Wesen, Kyle A.; Lim, Hubert H.

    2015-01-01

    Objective The corticofugal system can alter coding along the ascending sensory pathway. Within the auditory system, electrical stimulation of the auditory cortex (AC) paired with a pure tone can cause egocentric shifts in the tuning of auditory neurons, making them more sensitive to the pure tone frequency. Since tinnitus has been linked with hyperactivity across auditory neurons, we sought to develop a new neuromodulation approach that could suppress a wide range of neurons rather than enhance specific frequency-tuned neurons. Approach We performed experiments in the guinea pig to assess the effects of cortical stimulation paired with broadband noise (PN-Stim) on ascending auditory activity within the central nucleus of the inferior colliculus (CNIC), a widely studied region for AC stimulation paradigms. Main results All eight stimulated AC regions induced extensive suppression of activity across the CNIC that was not possible with noise stimulation alone. This suppression built up over time and remained after the PN-Stim paradigm. Significance We propose that the corticofugal system is designed to decrease the brain’s input gain to irrelevant stimuli and PN-Stim is able to artificially amplify this effect to suppress neural firing across the auditory system. The PN-Stim concept may have potential for treating tinnitus and other neurological disorders. PMID:25686163

  20. [Research on Chinese medicine pairs (III)--Their bio-active components].

    PubMed

    Li, Wei-Xia; Tang, Yu-Ping; Liu, Li; Liu, Pei; Su, Shu-Lan; Qian, Da-Wei; Duan, Jin-Ao

    2013-12-01

    The total effect of Chinese medicine pair (CMP) was not the simply addition of two single herbs, but the interaction of their different components. Therefore, the research on the bio-active components of CMP is the basis of CMP compatibility study, and has important significance for revealing the compatibility effect and action mechanism, and creating traditional Chinese medicine (TCM) new drugs. This paper summed up the latest research progress of CMP on the basis of the bio-active components variation regularity of CMP from chemical solutions and content changes in vitro and the actions of CMP on bodies in vivo, in order to further drive the modern basic and applied research of CMP, and to reveal the scientific essence of CMP compatibility.

  1. Exploring the "Lone Wolf" Phenomenon in Student Teams

    ERIC Educational Resources Information Center

    Barr, Terri Feldman; Dixon, Andrea L.; Gassenheimer, Jule B.

    2005-01-01

    The proliferation of projects using student teams has motivated researchers to examine factors that affect both team process and outcomes. This research introduces an individual difference variable found in the business environment that has not been examined in a classroom context. The lone wolf appears to play a role in how teams function and…

  2. Water discharge from Lone Star Geyser, Yellowstone NP, WY

    NASA Astrophysics Data System (ADS)

    Murphy, F.; Randolph-Flagg, N. G.; Hurwitz, S.

    2014-12-01

    During four days in April, 2014 we made a series of measurements at Lone Star Geyser in Yellowstone National Park, WY. This work included the continuous measurement of liquid water discharge from the geyser and some nearby not springs, and concurrent meteorological measurements. The discharge of the geyser and the hot springs was measured in channels that carry the water to the Firehole River. We found that average measured discharge varies from day to night, likely due to melting of geyser-generated and meteoric snow during warmer daylight hours and freezing of erupted liquid and vapor during the night. The nearby hot springs contribute a nearly constant flow of about 3 l/s to the Firehole River, while during eruptions the total discharge increases to a maximum of about 25 l/s. Two small geysers within 5 meters of the Lone Star Geyser cone were observed to erupt during a time when Lone Star Geyser was not erupting. The water discharged from these small geysers is a very small fraction of that from Lone Star Geyser.

  3. Investigating Hypervigilance for Social Threat of Lonely Children

    ERIC Educational Resources Information Center

    Qualter, Pamela; Rotenberg, Ken; Barrett, Louise; Henzi, Peter; Barlow, Alexandra; Stylianou, Maria; Harris, Rebecca A.

    2013-01-01

    The hypothesis that lonely children show hypervigilance for social threat was examined in a series of three studies that employed different methods including advanced eye-tracking technology. Hypervigilance for social threat was operationalized as hostility to ambiguously motivated social exclusion in a variation of the hostile attribution…

  4. Attributional Style of the Lonely and the Depressed.

    ERIC Educational Resources Information Center

    Anderson, Craig A.; And Others

    Attribution theory suggests that attributional styles may contribute to the motivational and performance deficits frequently observed in depressed and lonely populations. An Attributional Style Assessment Test (ASAT) was created and administered to college students, along with the Beck Depression Inventory and the UCLA Loneliness Scale.…

  5. Rickettsia rickettsii transmission by a lone star tick, North Carolina.

    PubMed

    Breitschwerdt, Edward B; Hegarty, Barbara C; Maggi, Ricardo G; Lantos, Paul M; Aslett, Denise M; Bradley, Julie M

    2011-05-01

    Only indirect or circumstantial evidence has been published to support transmission of Rickettsia rickettsii by Amblyomma americanum (lone star) ticks in North America. This study provides molecular evidence that A. americanum ticks can function, although most likely infrequently, as vectors of Rocky Mountain spotted fever for humans.

  6. An econometric analysis of smoking prevalence among lone mothers.

    PubMed

    Dorsett, R

    1999-08-01

    This paper uses panel data to examine the determinants of smoking among lone mothers over the period 1991-1996. Consideration is given to the initial conditions problem encountered when modelling dynamic panel probit models, and a recently suggested approach is applied to address this problem.

  7. Changing ionization conditions in SDSS galaxies with active galactic nuclei as a function of environment from pairs to clusters

    SciTech Connect

    Khabiboulline, Emil T.; Steinhardt, Charles L.; Silverman, John D.; Ellison, Sara L.; Mendel, J. Trevor; Patton, David R.

    2014-11-01

    We study how active galactic nucleus (AGN) activity changes across environments from galaxy pairs to clusters using 143,843 galaxies with z < 0.2 from the Sloan Digital Sky Survey. Using a refined technique, we apply a continuous measure of AGN activity, characteristic of the ionization state of the narrow-line emitting gas. Changes in key emission-line ratios ([N II] λ6548/Hα, [O III] λ5007/Hβ) between different samples allow us to disentangle different environmental effects while removing contamination. We confirm that galaxy interactions enhance AGN activity. However, conditions in the central regions of clusters are inhospitable for AGN activity even if galaxies are in pairs. These results can be explained through models of gas dynamics in which pair interactions stimulate the transfer of gas to the nucleus and clusters suppress gas availability for accretion onto the central black hole.

  8. Differential water mite parasitism, phenoloxidase activity, and resistance to mites are unrelated across pairs of related damselfly species.

    PubMed

    Mlynarek, Julia J; Iserbyt, Arne; Nagel, Laura; Forbes, Mark R

    2015-01-01

    Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assessed relations between actual levels of parasitism and resistance to parasites seen in nature across multiple host species. The main goal of this study was to determine whether interspecific variation in resistance against ectoparasitic larval water mites either was predictive of interspecific variation in parasitism for ten closely related species of damselflies (grouped into five "species pairs"), or was predicted by interspecific variation in a commonly used measure of innate immunity (total Phenoloxidase or potential PO activity). Two of five species pairs had interspecific differences in proportions of individuals resisting larval Arrenurus water mites, only one of five species pairs had species differences in prevalence of larval Arrenurus water mites, and another two of five species pairs showed species differences in mean PO activity. Within the two species pairs where species differed in proportion of individuals resisting mites the species with the higher proportion did not have correspondingly higher PO activity levels. Furthermore, the proportion of individuals resisting mites mirrored prevalence of parasitism in only one species pair. There was no interspecific variation in median intensity of mite infestation within any species pair. We conclude that a species' relative ability to resist particular parasites does not explain interspecific variation in parasitism within species pairs and that neither resistance nor parasitism is reflected by interspecific variation in total PO or potential PO activity.

  9. Structural dynamics and activity of nanocatalysts inside fuel cells by in operando atomic pair distribution studies

    NASA Astrophysics Data System (ADS)

    Petkov, Valeri; Prasai, Binay; Shan, Shiyao; Ren, Yang; Wu, Jinfang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian

    2016-05-01

    Here we present the results from a study aimed at clarifying the relationship between the atomic structure and activity of nanocatalysts for chemical reactions driving fuel cells, such as the oxygen reduction reaction (ORR). In particular, using in operando high-energy X-ray diffraction (HE-XRD) we tracked the evolution of the atomic structure and activity of noble metal-transition metal (NM-TM) nanocatalysts for ORR as they function at the cathode of a fully operational proton exchange membrane fuel cell (PEMFC). Experimental HE-XRD data were analysed in terms of atomic pair distribution functions (PDFs) and compared to the current output of the PEMFC, which was also recorded during the experiments. The comparison revealed that under actual operating conditions, NM-TM nanocatalysts can undergo structural changes that differ significantly in both length-scale and dynamics and so can suffer losses in their ORR activity that differ significantly in both character and magnitude. Therefore we argue that strategies for reducing ORR activity losses should implement steps for achieving control not only over the length but also over the time-scale of the structural changes of NM-TM NPs that indeed occur during PEMFC operation. Moreover, we demonstrate how such a control can be achieved and thereby the performance of PEMFCs improved considerably. Last but not least, we argue that the unique capabilities of in operando HE-XRD coupled to atomic PDF analysis to characterize active nanocatalysts inside operating fuel cells both in a time-resolved manner and with atomic level resolution, i.e. in 4D, can serve well the ongoing search for nanocatalysts that deliver more with less platinum.Here we present the results from a study aimed at clarifying the relationship between the atomic structure and activity of nanocatalysts for chemical reactions driving fuel cells, such as the oxygen reduction reaction (ORR). In particular, using in operando high-energy X-ray diffraction (HE

  10. Structural dynamics and activity of nanocatalysts inside fuel cells by in operando atomic pair distribution studies.

    PubMed

    Petkov, Valeri; Prasai, Binay; Shan, Shiyao; Ren, Yang; Wu, Jinfang; Cronk, Hannah; Luo, Jin; Zhong, Chuan-Jian

    2016-05-19

    Here we present the results from a study aimed at clarifying the relationship between the atomic structure and activity of nanocatalysts for chemical reactions driving fuel cells, such as the oxygen reduction reaction (ORR). In particular, using in operando high-energy X-ray diffraction (HE-XRD) we tracked the evolution of the atomic structure and activity of noble metal-transition metal (NM-TM) nanocatalysts for ORR as they function at the cathode of a fully operational proton exchange membrane fuel cell (PEMFC). Experimental HE-XRD data were analysed in terms of atomic pair distribution functions (PDFs) and compared to the current output of the PEMFC, which was also recorded during the experiments. The comparison revealed that under actual operating conditions, NM-TM nanocatalysts can undergo structural changes that differ significantly in both length-scale and dynamics and so can suffer losses in their ORR activity that differ significantly in both character and magnitude. Therefore we argue that strategies for reducing ORR activity losses should implement steps for achieving control not only over the length but also over the time-scale of the structural changes of NM-TM NPs that indeed occur during PEMFC operation. Moreover, we demonstrate how such a control can be achieved and thereby the performance of PEMFCs improved considerably. Last but not least, we argue that the unique capabilities of in operando HE-XRD coupled to atomic PDF analysis to characterize active nanocatalysts inside operating fuel cells both in a time-resolved manner and with atomic level resolution, i.e. in 4D, can serve well the ongoing search for nanocatalysts that deliver more with less platinum.

  11. Active destabilization of base pairs by a DNA glycosylase wedge initiates damage recognition.

    PubMed

    Kuznetsov, Nikita A; Bergonzo, Christina; Campbell, Arthur J; Li, Haoquan; Mechetin, Grigory V; de los Santos, Carlos; Grollman, Arthur P; Fedorova, Olga S; Zharkov, Dmitry O; Simmerling, Carlos

    2015-01-01

    Formamidopyrimidine-DNA glycosylase (Fpg) excises 8-oxoguanine (oxoG) from DNA but ignores normal guanine. We combined molecular dynamics simulation and stopped-flow kinetics with fluorescence detection to track the events in the recognition of oxoG by Fpg and its mutants with a key phenylalanine residue, which intercalates next to the damaged base, changed to either alanine (F110A) or fluorescent reporter tryptophan (F110W). Guanine was sampled by Fpg, as evident from the F110W stopped-flow traces, but less extensively than oxoG. The wedgeless F110A enzyme could bend DNA but failed to proceed further in oxoG recognition. Modeling of the base eversion with energy decomposition suggested that the wedge destabilizes the intrahelical base primarily through buckling both surrounding base pairs. Replacement of oxoG with abasic (AP) site rescued the activity, and calculations suggested that wedge insertion is not required for AP site destabilization and eversion. Our results suggest that Fpg, and possibly other DNA glycosylases, convert part of the binding energy into active destabilization of their substrates, using the energy differences between normal and damaged bases for fast substrate discrimination.

  12. Pair and Cluster Formation in Hybrid Active-Passive Matter Suspensions

    NASA Astrophysics Data System (ADS)

    Krafnick, Ryan; Garcia, Angel

    2015-03-01

    Systems composed of self-propelling entities, dubbed active matter, are ubiquitous in nature, from flocks of birds and schools of fish to swarms of bacteria and catalytic nanomotors. These systems (both biological and industrial) have applications ranging from micron-scale cargo manipulation and directed transport to water remediation and material processing. When added to a solution with passive (non-self-propelling) particles, active matter leads to new and altered system properties. For example, the diffusion of passive particles increases by orders of magnitude in typical systems, leading to a raised effective temperature. Additionally, particles that normally repel each other exhibit effective attractions which can lead to pair formation and clustering. The nature of these effects depends on both the mechanical collisions of swimmers and the hydrodynamic flow fields they propagate. We computationally examine the effect and dependence of various system parameters, such as particle shape and density, on these properties. This work was funded by NIH grant GM086801 and NSF grant MCB-1050966.

  13. NGC 5252: a pair of radio-emitting active galactic nuclei?

    NASA Astrophysics Data System (ADS)

    Yang, Xiaolong; Yang, Jun; Paragi, Zsolt; Liu, Xiang; An, Tao; Bianchi, Stefano; Ho, Luis C.; Cui, Lang; Zhao, Wei; Wu, Xiaocong

    2017-01-01

    The X-ray source CXO J133815.6+043255 has counterparts in the UV, optical, and radio bands. Based on the multiband investigations, it has been recently proposed by Kim et al. as a rarely seen off-nucleus ultraluminous X-ray (ULX) source with a black hole mass of ≥104 M⊙ in the nearby Seyfert galaxy NGC 5252. To explore its radio properties at very high angular resolution, we performed very long-baseline interferometry (VLBI) observations with the European VLBI Network (EVN) at 1.7 GHz. We find that the radio counterpart is remarkably compact among the known ULXs. It does not show a resolved structure with a resolution of a few milliarcsecond (mas), and the total recovered flux density is comparable to that measured in earlier sub-arcsecond-resolution images. The compact radio structure, the relatively flat spectrum, and the high radio luminosity are consistent with a weakly accreting supermassive black hole in a low-luminosity active galactic nucleus. The nucleus of NGC 5252 itself has similar radio properties. We argue that the system represents a relatively rare pair of active galactic nuclei, where both components emit in the radio.

  14. Local complete active space second-order perturbation theory using pair natural orbitals (PNO-CASPT2)

    NASA Astrophysics Data System (ADS)

    Menezes, Filipe; Kats, Daniel; Werner, Hans-Joachim

    2016-09-01

    We present a CASPT2 method which exploits local approximations to achieve linear scaling of the computational effort with the molecular size, provided the active space is small and local. The inactive orbitals are localized, and the virtual space for each electron pair is spanned by a domain of pair-natural orbitals (PNOs). The configuration space is internally contracted, and the PNOs are defined for uniquely defined orthogonal pairs. Distant pair energies are obtained by multipole approximations, so that the number of configurations that are explicitly treated in the CASPT2 scales linearly with molecular size (assuming a constant active space). The PNOs are generated using approximate amplitudes obtained in a pair-specific semi-canonical basis of projected atomic orbitals (PAOs). The evaluation and transformation of the two-electron integrals use the same parallel local density fitting techniques as recently described for linear-scaling PNO-LMP2 (local second-order Møller-Plesset perturbation theory). The implementation of the amplitude equations, which are solved iteratively, employs the local integrated tensor framework. The efficiency and accuracy of the method are tested for excitation energies and correlation energies. It is demonstrated that the errors introduced by the local approximations are very small. They can be well controlled by few parameters for the distant pair approximation, initial PAO domains, and the PNO domains.

  15. Local complete active space second-order perturbation theory using pair natural orbitals (PNO-CASPT2).

    PubMed

    Menezes, Filipe; Kats, Daniel; Werner, Hans-Joachim

    2016-09-28

    We present a CASPT2 method which exploits local approximations to achieve linear scaling of the computational effort with the molecular size, provided the active space is small and local. The inactive orbitals are localized, and the virtual space for each electron pair is spanned by a domain of pair-natural orbitals (PNOs). The configuration space is internally contracted, and the PNOs are defined for uniquely defined orthogonal pairs. Distant pair energies are obtained by multipole approximations, so that the number of configurations that are explicitly treated in the CASPT2 scales linearly with molecular size (assuming a constant active space). The PNOs are generated using approximate amplitudes obtained in a pair-specific semi-canonical basis of projected atomic orbitals (PAOs). The evaluation and transformation of the two-electron integrals use the same parallel local density fitting techniques as recently described for linear-scaling PNO-LMP2 (local second-order Møller-Plesset perturbation theory). The implementation of the amplitude equations, which are solved iteratively, employs the local integrated tensor framework. The efficiency and accuracy of the method are tested for excitation energies and correlation energies. It is demonstrated that the errors introduced by the local approximations are very small. They can be well controlled by few parameters for the distant pair approximation, initial PAO domains, and the PNO domains.

  16. Differential Water Mite Parasitism, Phenoloxidase Activity, and Resistance to Mites Are Unrelated across Pairs of Related Damselfly Species

    PubMed Central

    Mlynarek, Julia J.; Iserbyt, Arne; Nagel, Laura; Forbes, Mark R.

    2015-01-01

    Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assessed relations between actual levels of parasitism and resistance to parasites seen in nature across multiple host species. The main goal of this study was to determine whether interspecific variation in resistance against ectoparasitic larval water mites either was predictive of interspecific variation in parasitism for ten closely related species of damselflies (grouped into five “species pairs”), or was predicted by interspecific variation in a commonly used measure of innate immunity (total Phenoloxidase or potential PO activity). Two of five species pairs had interspecific differences in proportions of individuals resisting larval Arrenurus water mites, only one of five species pairs had species differences in prevalence of larval Arrenurus water mites, and another two of five species pairs showed species differences in mean PO activity. Within the two species pairs where species differed in proportion of individuals resisting mites the species with the higher proportion did not have correspondingly higher PO activity levels. Furthermore, the proportion of individuals resisting mites mirrored prevalence of parasitism in only one species pair. There was no interspecific variation in median intensity of mite infestation within any species pair. We conclude that a species’ relative ability to resist particular parasites does not explain interspecific variation in parasitism within species pairs and that neither resistance nor parasitism is reflected by interspecific variation in total PO or potential PO activity. PMID:25658982

  17. Evaluation of antioxidant activity and electronic structure of aspirin and paracetamol

    NASA Astrophysics Data System (ADS)

    Motozaki, W.; Nagatani, Y.; Kimura, Y.; Endo, K.; Takemura, T.; Kurmaev, E. Z.; Moewes, A.

    2011-01-01

    We present a study of electronic structure, chemical bonding, and antioxidant activity of phenolic antioxidants (aspirin and paracetamol). X-ray photoelectron and emission spectra of the antioxidants have been simulated by deMon density functional theory (DFT) calculations of the molecules. The chemical bonding of aspirin is characterized by the formation of oxygen 'lone-pair' π-orbitals which can neutralize free radicals and thus be related to antioxidant properties of the drug. In the case of paracetamol the additional nitrogen 'lone pair' is formed which can explain toxicity of the drug. We propose an evaluation method of antioxidant activity based on the relationship between experimental half-wave oxidation potential ( Ep/2 ) and calculated ionization potentials ( IP) by the DFT calculations, and can conclude that paracetamol has the higher antioxidant activity than aspirin.

  18. Early Life Manipulations of the Nonapeptide System Alter Pair Maintenance Behaviors and Neural Activity in Adult Male Zebra Finches

    PubMed Central

    Baran, Nicole M.; Tomaszycki, Michelle L.; Adkins-Regan, Elizabeth

    2016-01-01

    Adult zebra finches (T. guttata) form socially monogamous pair bonds characterized by proximity, vocal communication, and contact behaviors. In this experiment, we tested whether manipulations of the nonapeptide hormone arginine vasotocin (AVT, avian homolog of vasopressin) and the V1a receptor (V1aR) early in life altered species-typical pairing behavior in adult zebra finches of both sexes. Although there was no effect of treatment on the tendency to pair in either sex, males in different treatments exhibited profoundly different profiles of pair maintenance behavior. Following a brief separation, AVT-treated males were highly affiliative with their female partner but sang very little compared to Controls. In contrast, males treated with a V1aR antagonist sang significantly less than Controls, but did not differ in affiliation. These effects on behavior in males were also reflected in changes in the expression of V1aR and immediate early gene activity in three brain regions known to be involved in pairing behavior in birds: the medial amygdala, medial bed nucleus of the stria terminalis, and the lateral septum. AVT males had higher V1aR expression in the medial amygdala than both Control and antagonist-treated males and immediate early gene activity of V1aR neurons in the medial amygdala was positively correlated with affiliation. Antagonist treated males showed decreased activity in the medial amygdala. In addition, there was a negative correlation between the activity of V1aR cells in the medial bed nucleus of the stria terminalis and singing. Treatment also affected the expression of V1aR and activity in the lateral septum, but this was not correlated with any behaviors measured. These results provide evidence that AVT and V1aR play developmental roles in specific pair maintenance behaviors and the neural substrate underlying these behaviors in a bird. PMID:27065824

  19. Cultural differences in children's pair collaboration: Engaging fluidly versus managing individual agendas in a computer programming activity

    NASA Astrophysics Data System (ADS)

    Ruvalcaba, Omar

    This dissertation analyzes cultural aspects of fluidity in children's collaboration during a computer programming activity. Pairs of 8- to- 11-year-old children, 25 U.S. Mexican-heritage and 25 European American, were invited to work on a computer programming activity. Ten minutes of their collaboration were analyzed for cultural differences in how much time the pairs spent collaborating fluidly or working using individual agendas. Pairs of children from both cultural backgrounds spent substantial time collaborating by building on each other's ideas with proposals. However, U.S. Mexican-heritage pairs spent significantly more time in fluid synchrony, with anticipation of each other's contributions, compared to European American pairs, who spent more time resisting partner contributions, negotiating whose idea should be used, and bossing their partner to implement their plan. Thus, children of both backgrounds collaborated; however, the Mexican-heritage children collaborated more and their collaboration included a particularly fluid, seamless approach that was rare among European American children.

  20. Synergistic Effects of Six Chronic Disease Pairs on Decreased Physical Activity: The SMILE Cohort Study

    PubMed Central

    Dörenkamp, Sarah; Mesters, Ilse; Vos, Rein; Schepers, Jan; van den Akker, Marjan; Teijink, Joep; de Bie, Rob

    2016-01-01

    Little is known about whether and how two chronic diseases interact with each other in modifying the risk of physical inactivity. The aim of the present study is to identify chronic disease pairs that are associated with compliance or noncompliance with the Dutch PA guideline recommendation and to study whether specific chronic disease pairs indicate an extra effect on top of the effects of the diseases individually. Cross-sectional data from 3,386 participants of cohort study SMILE were used and logistic regression analysis was performed to study the joint effect of the two diseases of each chronic disease pair for compliance with the Dutch PA guideline. For six chronic disease pairs, patients suffering from both diseases belonging to these disease pairs in question show a higher probability of noncompliance to the Dutch PA guideline, compared to what one would expect based on the effects of each of the two diseases alone. These six chronic disease pairs were chronic respiratory disease and severe back problems; migraine and inflammatory joint disease; chronic respiratory disease and severe kidney disease; chronic respiratory disease and inflammatory joint disease; inflammatory joint disease and rheumatoid arthritis; and rheumatoid arthritis and osteoarthritis of the knees, hips, and hands. PMID:27274994

  1. Does a Combination of Metaphor and Pairing Activity Help Programming Performance of Students with Different Self-Regulated Learning Level?

    ERIC Educational Resources Information Center

    Hui, Tie Hui; Umar, Irfan Naufal

    2011-01-01

    This study aims to investigate the effects of metaphors and pairing activity on programming performance of students with different self-regulated-learning (SRL) level. A total of 84 computing students were involved in this seven-week study, and they were randomly assigned either to a group that received a combination of metaphor and pair…

  2. Remedial investigation and feasibility study Point Lonely Radar Installation, Alaska. Volume 1. Appendices a - c. Final report, January 1995-April 1996

    SciTech Connect

    1996-04-01

    This report presents the findings of Remedial Investigations and Feasibility Studies at sites located at the Point Lonely radar installation in northern Alaska. The sites were characterized based on sampling and analyses conducted during Remedial Investigation activities performed during August and September 1993.

  3. Existence of Corotating and Counter-Rotating Vortex Pairs for Active Scalar Equations

    NASA Astrophysics Data System (ADS)

    Hmidi, Taoufik; Mateu, Joan

    2017-03-01

    In this paper, we study the existence of corotating and counter-rotating pairs of simply connected patches for Euler equations and the {(SQG)_{α}} equations with {α in (0,1)}. From the numerical experiments implemented for Euler equations in Deem and Zabusky (Phys Rev Lett 40(13):859-862, 1978), Pierrehumbert (J Fluid Mech 99:129-144, 1980), Saffman and Szeto (Phys Fluids 23(12):2339-2342, 1980) it is conjectured the existence of a curve of steady vortex pairs passing through the point vortex pairs. There are some analytical proofs based on variational principle (Keady in J Aust Math Soc Ser B 26:487-502, 1985; Turkington in Nonlinear Anal Theory Methods Appl 9(4):351-369, 1985); however, they do not give enough information about the pairs, such as the uniqueness or the topological structure of each single vortex. We intend in this paper to give direct proofs confirming the numerical experiments and extend these results for the {(SQG)_{α}} equation when {α in (0,1)}. The proofs rely on the contour dynamics equations combined with a desingularization of the point vortex pairs and the application of the implicit function theorem.

  4. Enzyme hyperactivity in AOT water-in-oil microemulsions is induced by 'lone' sodium counterions in the water-pool.

    PubMed

    Oldfield, Christopher; Freedman, Robert B; Robinson, Brian H

    2005-01-01

    Water-in-oil microemulsions are thermodynamically stable single-phase dispersions of water and surfactant within a continuous oil phase. The classical ternary system, based on the surfactant sodium bis(2-ethylhexyl)sulfosuccinate ('AOT'), water and an alkane such as n-heptane, is an optically transparent monodispersion of spherical water-droplets coated with a close-packed surfactant monolayer and the droplet radius is, to a good first approximation, directly proportional to the molar water: surfactant ratio, R. Enzymes dissolved in the water droplets retain activity and stability. These systems have attracted interest as media for biotransformations. Principally based upon studies in AOT-stabilized w/o microemulsions, a peculiar feature of the kinetics of enzyme-catalyzed reactions has long been apparent: the reaction rate characteristically increases from around zero at R=3, through a maximum, in the range R= 10-20, and thereafter decreases again, so that plots of rate vs. R are characteristically 'bell-shaped'. Furthermore, at optimal R, enzymes seem to be 'hyperactive', i.e., they are more active, by a modest but significant factor of 2-3-fold, than in aqueous solution. In this paper we propose the hypothesis that this kind of R-dependence arises because of the presence of freely mobile lone surfactant counterions (Na+) within the water-pool. These ions have no charge partners within the water pool and consequently have a high electrochemical potential. According to our model, lone counterions facilitate the hydrolysis of ester or amide substrates, for example, by stabilizing the tetrahedral intermediate formed during the reaction through ion-pairing with the carbonyl oxygen of the substrate, thus facilitating transfer of negative charge from the carbonyl carbon as it is attacked by the incoming nucleophile. An expression for the relationship between the concentration of free counterions in the water-pool and the compositional parameter R leads directly

  5. Centromere Pairing in Early Meiotic Prophase Requires Active Centromeres and Precedes Installation of the Synaptonemal Complex in Maize[W

    PubMed Central

    Zhang, Jing; Pawlowski, Wojciech P.; Han, Fangpu

    2013-01-01

    Pairing of homologous chromosomes in meiosis is critical for their segregation to daughter cells. In most eukaryotes, clustering of telomeres precedes and facilitates chromosome pairing. In several species, centromeres also form pairwise associations, known as coupling, before the onset of pairing. We found that, in maize (Zea mays), centromere association begins at the leptotene stage and occurs earlier than the formation of the telomere bouquet. We established that centromere pairing requires centromere activity and the sole presence of centromeric repeats is not sufficient for pairing. In several species, homologs of the ZIP1 protein, which forms the central element of the synaptonemal complex in budding yeast (Saccharomyces cerevisiae), play essential roles in centromere coupling. However, we found that the maize ZIP1 homolog ZYP1 installs in the centromeric regions of chromosomes after centromeres form associations. Instead, we found that maize STRUCTURAL MAINTENANCE OF CHROMOSOMES6 homolog forms a central element of the synaptonemal complex, which is required for centromere associations. These data shed light on the poorly understood mechanism of centromere interactions and suggest that this mechanism may vary somewhat in different species. PMID:24143803

  6. Ion pairs and their role in modulating stability of cold- and warm-active uracil DNA glycosylase.

    PubMed

    Olufsen, Magne; Papaleo, Elena; Smalås, Arne Oskar; Brandsdal, Bjørn Olav

    2008-05-15

    MD simulations and continuum electrostatics calculations have been used to study the observed differences in thermostability of cold- and warm-active uracil DNA glycosylase (UDG). The present study focuses on the role of ion pairs and how they affect the thermal stability of the two enzymes. Analysis of the MD generated structural ensembles show that cod UDG (cUDG) and human UDG (hUDG) have 11 and 12 ion pairs which are present in at least 30% of the conformations. The electrostatic contribution of the ion pairs, computed using continuum electrostatics, is slightly more favorable in cUDG at 298 K. This is primarily attributed to more optimized interactions between the ion pairs and nearby dipoles/charges in cUDG. More global salt bridges are found in hUDG and are more stabilizing when compared to cUDG, possibly playing a role in maintaining overall stability and reducing conformational entropy. Both enzymes contain one three-member ionic network, but the one found in hUDG is far more stabilizing. Our results also suggest that care should be taken when performing statistical analysis of crystal structures with respect to ion pairs, and that crystallization conditions must be carefully examined when performing such analysis.

  7. The Clinical Threat Assessment of the Lone-Actor Terrorist.

    PubMed

    Meloy, J Reid; Genzman, Jacqueline

    2016-12-01

    The Terrorist Radicalization Assessment Protocol (TRAP-18) is a structured professional judgment instrument for the assessment of individuals who present a concern for lone-actor terrorism. It consists of eight proximal warning behaviors and 10 distal characteristics. Previous research has demonstrated its interrater reliability and some concurrent and postdictive validity. In this article, TRAP-18 is retrospectively applied to the case of US Army psychiatrist and jihadist Malik Nidal Hasan, who committed a mass murder at Fort Hood, Texas in 2009. The strengths and limitations of TRAP-18 as a structured professional judgment instrument for mental health clinicians are discussed, and clinical risk management suggestions are made.

  8. Investigations on therapeutic glucocerebrosidases through paired detection with fluorescent activity-based probes

    PubMed Central

    Kallemeijn, Wouter W.; Scheij, Saskia; Hoogendoorn, Sascha; Witte, Martin D.; Herrera Moro Chao, Daniela; van Roomen, Cindy P. A. A.; Ottenhoff, Roelof; Overkleeft, Herman S.; Boot, Rolf G.; Aerts, Johannes M. F. G.

    2017-01-01

    Deficiency of glucocerebrosidase (GBA) causes Gaucher disease (GD). In the common non-neuronopathic GD type I variant, glucosylceramide accumulates primarily in the lysosomes of visceral macrophages. Supplementing storage cells with lacking enzyme is accomplished via chronic intravenous administration of recombinant GBA containing mannose-terminated N-linked glycans, mediating the selective uptake by macrophages expressing mannose-binding lectin(s). Two recombinant GBA preparations with distinct N-linked glycans are registered in Europe for treatment of type I GD: imiglucerase (Genzyme), contains predominantly Man(3) glycans, and velaglucerase (Shire PLC) Man(9) glycans. Activity-based probes (ABPs) enable fluorescent labeling of recombinant GBA preparations through their covalent attachment to the catalytic nucleophile E340 of GBA. We comparatively studied binding and uptake of ABP-labeled imiglucerase and velaglucerase in isolated dendritic cells, cultured human macrophages and living mice, through simultaneous detection of different GBAs by paired measurements. Uptake of ABP-labeled rGBAs by dendritic cells was comparable, as well as the bio-distribution following equimolar intravenous administration to mice. ABP-labeled rGBAs were recovered largely in liver, white-blood cells, bone marrow and spleen. Lungs, brain and skin, affected tissues in severe GD types II and III, were only poorly supplemented. Small, but significant differences were noted in binding and uptake of rGBAs in cultured human macrophages, in the absence and presence of mannan. Mannan-competed binding and uptake were largest for velaglucerase, when determined with single enzymes or as equimolar mixtures of both enzymes. Vice versa, imiglucerase showed more prominent binding and uptake not competed by mannan. Uptake of recombinant GBAs by cultured macrophages seems to involve multiple receptors, including several mannose-binding lectins. Differences among cells from different donors (n = 12

  9. Repression activity of Tailless on h 1 and eve 1 pair-rule stripes.

    PubMed

    Andrioli, Luiz Paulo; Dos Santos, Wesley Silva; Aguiar, Francisco Dos Santos; Digiampietri, Luciano Antonio

    2016-10-20

    We investigated the hypothesis that several transcriptional repressors are necessary to set the boundaries of anterior pair-rule stripes in Drosophila. Specifically, we tested whether Tailless (Tll) is part of a repression mechanism that correctly sets the anterior boundaries of hairy 1 (h 1) and even-skipped 1 (eve 1) stripes. Single mutant tll embryos displayed subtle deviations from the normal positions of h 1 and eve 1 stripes. Moreover, we observed stronger stripe deviations in embryos lacking both Tll and Sloppy-paired 1 (Slp 1), a common repressor for anterior pair-rule stripes. Using h 1 and eve 1 reporter constructs in the genetic assays, we provided further evidence that interference with normal mechanisms of stripe expression is mediated by Tll repression. Indeed, Tll represses both h 1 and eve 1 reporter stripes when misexpressed. Investigating the expression of other anterior gap genes in different genetic backgrounds and in the misexpression assays strengthened Tll direct repression in the regulation of h 1 and eve 1. Our results are consistent with tll being a newly-identified component of a combinatorial network of repressor genes that control pair-rule stripe formation in the anterior blastoderm of Drosophila.

  10. EGI-EUDAT integration activity - Pair data and high-throughput computing resources together

    NASA Astrophysics Data System (ADS)

    Scardaci, Diego; Viljoen, Matthew; Vitlacil, Dejan; Fiameni, Giuseppe; Chen, Yin; sipos, Gergely; Ferrari, Tiziana

    2016-04-01

    EGI (www.egi.eu) is a publicly funded e-infrastructure put together to give scientists access to more than 530,000 logical CPUs, 200 PB of disk capacity and 300 PB of tape storage to drive research and innovation in Europe. The infrastructure provides both high throughput computing and cloud compute/storage capabilities. Resources are provided by about 350 resource centres which are distributed across 56 countries in Europe, the Asia-Pacific region, Canada and Latin America. EUDAT (www.eudat.eu) is a collaborative Pan-European infrastructure providing research data services, training and consultancy for researchers, research communities, research infrastructures and data centres. EUDAT's vision is to enable European researchers and practitioners from any research discipline to preserve, find, access, and process data in a trusted environment, as part of a Collaborative Data Infrastructure (CDI) conceived as a network of collaborating, cooperating centres, combining the richness of numerous community-specific data repositories with the permanence and persistence of some of Europe's largest scientific data centres. EGI and EUDAT, in the context of their flagship projects, EGI-Engage and EUDAT2020, started in March 2015 a collaboration to harmonise the two infrastructures, including technical interoperability, authentication, authorisation and identity management, policy and operations. The main objective of this work is to provide end-users with a seamless access to an integrated infrastructure offering both EGI and EUDAT services and, then, pairing data and high-throughput computing resources together. To define the roadmap of this collaboration, EGI and EUDAT selected a set of relevant user communities, already collaborating with both infrastructures, which could bring requirements and help to assign the right priorities to each of them. In this way, from the beginning, this activity has been really driven by the end users. The identified user communities are

  11. Influence of lead(II) lone pairs on the serpentine structures for heterometallic alkoxides

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1995-05-10

    Heterometallic alkoxides, M{sub a}M{sub b}{prime}(OR){sub m}, most often adopts closed polyhedral structures, in part to give suitably high coordination numbers to all metals. In general, the ratio m/(a + b) is typically low (because one or more of M and M{prime} are low valent) so that {mu}{sub 2}- and {mu}{sub 3}-OR functionalities are required, and a closed polyhedron best accommodates such demands. Thus the metals of KZr{sub 2}(O{sup i}Pr){sub 9}{sup 2} and [BaZr{sub 2}(O{sup i}Pr){sub 10}]{sub 2}{sup 3} form triangles, those of K{sub 2}Zr{sub 2}(O{sup t}Bu){sub 10}{sup 4} form a diamond, and those of K{sub 4}Zr{sub 2}O(O{sup i}Pr){sub 10}{sup 2} form an octahedron. The authors report here the very different outcome of combining Zr(IV) with the soft divalent metal Pb(II). These results demonstrate that rational synthetic control of two different stoichiometries can be effected in heterometallic alkoxide chemistry.

  12. Rabbit Ears Concepts of Water Lone Pairs: A Reply to Comments of Hiberty, Danovich, and Shaik

    ERIC Educational Resources Information Center

    Clauss, A. D.; Ayoub, M.; Moore, J. W.; Landis, C. R.; Weinhold, F.

    2015-01-01

    This article is a response to a commentary entitled "Comment on 'Rabbit-Ears Hybrids, VSEPR Sterics, and Other Orbital Anachronisms': A Reply to a Criticism," which focuses on the fundamental question of whether there exists a unique set of supposedly "real," or "best," orbitals for a given molecule. The authors of…

  13. Brain activation by an olfactory stimulus paired with juvenile play in female rats.

    PubMed

    Paredes-Ramos, P; McCarthy, M M; Bowers, J M; Miquel, M; Manzo, J; Coria-Avila, G A

    2014-06-22

    We have previously shown that reward experienced during social play at juvenile age can be paired with artificial odors, and later in adulthood facilitate olfactory conditioned partner preferences (PP) in female rats. Herein, we examined the expression of FOS immunoreactivity (FOS-IR) following exposure to the odor paired with juvenile play (CS+). Starting at day P31 females received daily 30-min periods of social play with lemon-scented (paired group) or unscented females (unpaired group). At day P42, they were tested for play-PP with two juvenile males, one bearing the CS+ (lemon) and one bearing a novel odor (almond). Females were ovariectomized, hormone-primed and at day P55 tested for sexual-PP between two adult stud males scented with lemon or almond. In both tests, females from the paired group displayed conditioned PP (play or sexual) toward males bearing the CS+. In the present experiments females were exposed at day P59 to the CS+ during 60 min and their brains processed for FOS-IR. One group of female rats (Play+Sex) underwent play-PP and sexual-PP, whereas a second group of females (Play-only) underwent exclusively play-PP but not sexual-PP. Results showed that in the Play-only experiment exposure to the CS+ induced more FOS-IR in the medial prefrontal cortex, orbitofrontal cortex, dorsal striatum, and ventral tegmental area as compared to females from the unpaired group. In the Play+Sex experiment, more FOS-IR was observed in the piriform cortex, dorsal striatum, lateral septum, nucleus accumbens shell, bed nucleus of the stria terminalis and medial amygdala as compared to females from the unpaired group. Taken together, these results indicate mesocorticolimbic brain areas direct the expectation and/or choice of conditioned partners in female rats. In addition, transferring the meaning of play to sex preference requires different brain areas.

  14. Zinc regulates the activity of kinase-phosphatase pair (BasPrkC/BasPrpC) in Bacillus anthracis.

    PubMed

    Arora, Gunjan; Sajid, Andaleeb; Arulanandh, Mary Diana; Misra, Richa; Singhal, Anshika; Kumar, Santosh; Singh, Lalit K; Mattoo, Abid R; Raj, Rishi; Maiti, Souvik; Basu-Modak, Sharmila; Singh, Yogendra

    2013-10-01

    Bacillus anthracis Ser/Thr protein kinase PrkC (BasPrkC) is important for virulence of the bacterium within the host. Homologs of PrkC and its cognate phosphatase PrpC (BasPrpC) are the most conserved mediators of signaling events in diverse bacteria. BasPrkC homolog in Bacillus subtilis regulates critical processes like spore germination and BasPrpC modulates the activity of BasPrkC by dephosphorylation. So far, biochemical and genetic studies have provided important insights into the roles of BasPrkC and BasPrpC; however, regulation of their activities is not known. We studied the regulation of BasPrkC/BasPrpC pair and observed that Zn(2+) metal ions can alter their activities. Zn(2+) promotes BasPrkC kinase activity while inhibits the BasPrpC phosphatase activity. Concentration of Zn(2+) in growing B. anthracis cells was found to vary with growth phase. Zn(2+) was found to be lowest in log phase cells while it was highest in spores. This variation in Zn(2+) concentration is significant for understanding the antagonistic activities of BasPrkC/BasPrpC pair. Our results also show that BasPrkC activity is modulated by temperature changes and kinase inhibitors. Additionally, we identified Elongation Factor Tu (BasEf-Tu) as a substrate of BasPrkC/BasPrpC pair and assessed the impact of their regulation on BasEf-Tu phosphorylation. Based on these results, we propose Zn(2+) as an important regulator of BasPrkC/BasPrpC mediated phosphorylation cascades. Thus, this study reveals additional means by which BasPrkC can be activated leading to autophosphorylation and substrate phosphorylation.

  15. Targeted mutagenesis of multiple and paralogous genes in Xenopus laevis using two pairs of transcription activator-like effector nucleases.

    PubMed

    Sakane, Yuto; Sakuma, Tetsushi; Kashiwagi, Keiko; Kashiwagi, Akihiko; Yamamoto, Takashi; Suzuki, Ken-Ichi T

    2014-01-01

    Transcription activator-like effector nucleases (TALENs) have been extensively used in genome editing in various organisms. In some cases, however, it is difficult to efficiently disrupt both paralogous genes using a single pair of TALENs in Xenopus laevis because of its polyploidy. Here, we report targeted mutagenesis of multiple and paralogous genes using two pairs of TALENs in X. laevis. First, we show simultaneous targeted mutagenesis of three genes, tyrosinase paralogues (tyra and tyrb) and enhanced green fluorescent protein (egfp) by injection of two TALENs pairs in transgenic embryos carrying egfp. Consistent with the high frequency of both severe phenotypic traits, albinism and loss of GFP fluorescence, frameshift mutation rates of tyr paralogues and egfp reached 40-80%. Next, we show early introduction of TALEN-mediated mutagenesis of these target loci during embryogenesis. Finally, we also demonstrate that two different pairs of TALENs can simultaneously introduce mutations to both paralogues encoding histone chaperone with high efficiency. Our results suggest that targeted mutagenesis of multiple genes using TALENs can be applied to analyze the functions of paralogous genes with redundancy in X. laevis.

  16. Enzymatically Regulated Peptide Pairing and Catalysis for the Bioanalysis of Extracellular Prometastatic Activities of Functionally Linked Enzymes

    NASA Astrophysics Data System (ADS)

    Li, Hao; Huang, Yue; Yu, Yue; Li, Tianqi; Li, Genxi; Anzai, Jun-Ichi

    2016-05-01

    Diseases such as cancer arise from systematical reconfiguration of interactions of exceedingly large numbers of proteins in cell signaling. The study of such complicated molecular mechanisms requires multiplexed detection of the inter-connected activities of several proteins in a disease-associated context. However, the existing methods are generally not well-equipped for this kind of application. Here a method for analyzing functionally linked protein activities is developed based on enzyme controlled pairing between complementary peptide helix strands, which simultaneously enables elaborate regulation of catalytic activity of the paired peptides. This method has been used to detect three different types of protein modification enzymes that participate in the modification of extracellular matrix and the formation of invasion front in tumour. In detecting breast cancer tissue samples using this method, up-regulated activity can be observed for two of the assessed enzymes, while the third enzyme is found to have a subtle fluctuation of activity. These results may point to the application of this method in evaluating prometastatic activities of proteins in tumour.

  17. Enzymatically Regulated Peptide Pairing and Catalysis for the Bioanalysis of Extracellular Prometastatic Activities of Functionally Linked Enzymes

    PubMed Central

    Li, Hao; Huang, Yue; Yu, Yue; Li, Tianqi; Li, Genxi; Anzai, Jun-ichi

    2016-01-01

    Diseases such as cancer arise from systematical reconfiguration of interactions of exceedingly large numbers of proteins in cell signaling. The study of such complicated molecular mechanisms requires multiplexed detection of the inter-connected activities of several proteins in a disease-associated context. However, the existing methods are generally not well-equipped for this kind of application. Here a method for analyzing functionally linked protein activities is developed based on enzyme controlled pairing between complementary peptide helix strands, which simultaneously enables elaborate regulation of catalytic activity of the paired peptides. This method has been used to detect three different types of protein modification enzymes that participate in the modification of extracellular matrix and the formation of invasion front in tumour. In detecting breast cancer tissue samples using this method, up-regulated activity can be observed for two of the assessed enzymes, while the third enzyme is found to have a subtle fluctuation of activity. These results may point to the application of this method in evaluating prometastatic activities of proteins in tumour. PMID:27140831

  18. Hydrophobic ion pairing as a method for enhancing structure and activity of lyophilized subtilisin BPN' suspended in isooctane.

    PubMed

    Kendrick, B S; Meyer, J D; Matsuura, J E; Carpenter, J F; Manning, M C

    1997-11-01

    The use of enzymes in low water environments permits reactions to occur that are difficult or impossible in aqueous solution. In this manner, proteases can be used to form, rather than hydrolyze, ester and amide linkages. Presumably, the native-like structure of the enzyme must remain intact for catalysis to transpire. However, little is known regarding the integrity of the overall structure of lyophilized proteins suspended in organic media. In this study, the structural changes that occur during the freeze-drying process and those effected by suspension in the organic solvent were examined. Using Fourier-transform infrared spectroscopy, the secondary structure of lyophilized subtilisin BPN' was monitored and correlated to the level of enzymatic activity when suspended in isooctane. In addition, the ability of ionic detergents to stabilize subtilisin BPN' via ion pairing was evaluated. It was found that subtilisin unfolds to some degree during lyophilization, whether it is ion paired or not. Furthermore, there are structural changes observed when the enzyme is placed in isooctane, although the effects are less with ion-paired subtilisin. This higher level of retention of secondary structure results in increased enzymatic activity.

  19. Light-activated Cryptochrome Reacts with Molecular Oxygen to Form a Flavin–Superoxide Radical Pair Consistent with Magnetoreception*

    PubMed Central

    Müller, Pavel; Ahmad, Margaret

    2011-01-01

    Cryptochromes are flavin-based photoreceptors occurring throughout the biological kingdom, which regulate growth and development in plants and are involved in the entrainment of circadian rhythms of both plants and animals. A number of recent theoretical works suggest that cryptochromes might also be the receptors responsible for the sensing of the magnetic field of the earth (e.g. in insects, migratory birds, or migratory fish). Cryptochromes undergo forward light-induced reactions involving electron transfer to excited state flavin to generate radical intermediates, which correlate with biological activity. Here, we give evidence of a mechanism for the reverse reaction, namely dark reoxidation of protein-bound flavin in Arabidopsis thaliana cryptochrome (AtCRY1) by molecular oxygen that involves formation of a spin-correlated FADH•–superoxide radical pair. Formation of analogous radical pairs in animal cryptochromes might enable them to function as magnetoreceptors. PMID:21467031

  20. Light-activated cryptochrome reacts with molecular oxygen to form a flavin-superoxide radical pair consistent with magnetoreception.

    PubMed

    Müller, Pavel; Ahmad, Margaret

    2011-06-17

    Cryptochromes are flavin-based photoreceptors occurring throughout the biological kingdom, which regulate growth and development in plants and are involved in the entrainment of circadian rhythms of both plants and animals. A number of recent theoretical works suggest that cryptochromes might also be the receptors responsible for the sensing of the magnetic field of the earth (e.g. in insects, migratory birds, or migratory fish). Cryptochromes undergo forward light-induced reactions involving electron transfer to excited state flavin to generate radical intermediates, which correlate with biological activity. Here, we give evidence of a mechanism for the reverse reaction, namely dark reoxidation of protein-bound flavin in Arabidopsis thaliana cryptochrome (AtCRY1) by molecular oxygen that involves formation of a spin-correlated FADH(•)-superoxide radical pair. Formation of analogous radical pairs in animal cryptochromes might enable them to function as magnetoreceptors.

  1. Dihydrogen and Acetylene Activation by a Gold(I)/Platinum(0) Transition Metal Only Frustrated Lewis Pair.

    PubMed

    Campos, Jesús

    2017-03-01

    The first example of a frustrated Lewis pair (FLP) solely constructed around transition metal centers is described in this work. We have focused on the established capacity of Au(I) and Pt(0) complexes to act as Lewis acidic and basic fragments, respectively, while employing sufficiently bulky P(t)Bu3 and terphenyl phosphine ligands. This avoids formation of metallic Lewis adducts and confers the Au(I)/Pt(0) pair a remarkable capacity to activate dihydrogen and acetylene molecules in a fashion that closely resembles that of traditional main group FLP systems. As a consequence, unusual heterobimetallic Au(I)/Pt(II) complexes containing hydride (-H), acetylide (-C≡CH), and vinylene (-HC═CH-) bridges have been isolated.

  2. Equivalent activation of the hippocampus by face-face and face-laugh paired associate learning and recognition.

    PubMed

    Holdstock, J S; Crane, J; Bachorowski, J-A; Milner, B

    2010-11-01

    The human hippocampus is known to play an important role in relational memory. Both patient lesion studies and functional-imaging studies have shown that it is involved in the encoding and retrieval from memory of arbitrary associations. Two recent patient lesion studies, however, have found dissociations between spared and impaired memory within the domain of relational memory. Recognition of associations between information of the same kind (e.g., two faces) was spared, whereas recognition of associations between information of different kinds (e.g., face-name or face-voice associations) was impaired by hippocampal lesions. Thus, recognition of associations between information of the same kind may not be mediated by the hippocampus. Few imaging studies have directly compared activation at encoding and recognition of associations between same and different types of information. Those that have have shown mixed findings and been open to alternative interpretation. We used fMRI to compare hippocampal activation while participants studied and later recognized face-face and face-laugh paired associates. We found no differences in hippocampal activation between our two types of stimulus materials during either study or recognition. Study of both types of paired associate activated the hippocampus bilaterally, but the hippocampus was not activated by either condition during recognition. Our findings suggest that the human hippocampus is normally engaged to a similar extent by study and recognition of associations between information of the same kind and associations between information of different kinds.

  3. [Factors of lonely living in old psychiatric patients].

    PubMed

    Druz, V F; Oleinikova, I N

    2000-01-01

    70 lonely patients 60-83 years old were examined. Loneliness in the disintegrated first group (54 patients) resulted from the disintegrated family (the patients were early married). The loneliness in the second group was determined by the absence of their own family (16 patients). The main factors leading to loneliness were such diseases as schizophrenia and epilepsy, paranoic disorders of persecutive character directed to the nearest family, hypochondric depression, psychopathic-like disturbances, mental defect, personality disorders in premorbid state. Among social-psychologic factors the following ones had a significance: underestimation of the mental disorders in patients by their relatives, conflicts in the family, the patient's negative orientation to marriage, their deep emotional interrelation with the parents in young and mature age, alcoholism of married couple and special psychopathic features of the relatives. The events relating with the old age (loss of elderly couple), separation with adult children and parents, bad domestic living conditions were of less significance.

  4. An Optically Active Polymer for Broad-Spectrum Enantiomeric Recognition of Chiral Acids.

    PubMed

    Yan, Jijun; Kang, Chuanqing; Bian, Zheng; Ma, Xiaoye; Jin, Rizhe; Du, Zhijun; Gao, Lianxun

    2017-03-14

    Recognition of enantiomers of chiral acids by anion-π or lone pair-π interactions has not yet been investigated but is a significant and attractive challenge. This study reports an optically active polymer-based supramolecular system with capabilities of discriminating enantiomers of various chiral acids. The polymer featuring alternate π-acidic naphthalenediimides (NDIs) and methyl l-phenylalaninates in the backbone exhibits an unprecedented slow self-assembly process that is susceptible to perturbation by various chiral acids. Thus, the combination of anion-π or lone pair-π interactions and sensitivity of the polymeric self-assembly process to external chiral species endows the system with recognition capabilities. This is the first time that anion-π or lone pair-π interactions have been applied in the recognition of enantiomers of various chiral acids with a single system. The results shed light on new strategies for material design by integrating π-acidic aromatic systems and chiral building blocks to afford relevant advanced functions.

  5. Lonely people are no longer lonely on social networking sites: the mediating role of self-disclosure and social support.

    PubMed

    Lee, Kyung-Tag; Noh, Mi-Jin; Koo, Dong-Mo

    2013-06-01

    Most previous studies assert the negative effect of loneliness on social life and an individual's well-being when individuals use the Internet. To expand this previous research tradition, the current study proposes a model to test whether loneliness has a direct or indirect effect on well-being when mediated by self-disclosure and social support. The results show that loneliness has a direct negative impact on well-being but a positive effect on self-disclosure. While self-disclosure positively influences social support, self-disclosure has no impact on well-being, and social support positively influences well-being. The results also show a full mediation effect of social support in the self-disclosure to well-being link. The results imply that even if lonely people's well-being is poor, their well-being can be enhanced through the use of SNSs, including self-presentation and social support from their friends.

  6. Health-Related Findings Among Twin Pairs Discordant for Leisure-Time Physical Activity for 32 Years: The TWINACTIVE Study Synopsis.

    PubMed

    Leskinen, Tuija; Kujala, Urho M

    2015-06-01

    We are lacking very long-term and controlled intervention studies investigating the effects of habitual physical activity on health-related factors. To address this gap, we performed a natural experiment by identifying same-sex twin pairs in which the co-twins of each pair differed with respect to leisure-time physical-activity habits throughout their adult life. Our criterion for the discordance was that the same co-twin had a higher leisure time-activity volume than that of the other member of the pair at the majority -- if not all -- of the follow-up time points according to reported/interviewed physical-activity data. Overall, we identified and conducted multidimensional health-related measurements (including fitness, body composition, cardiometabolic risk factor levels, bone and arterial status, and exercise motivation) of 16 twin pairs (seven monozygotic (MZ) and nine dizygotic (DZ) pairs, mean age 60 years) who had persistent discordance in leisure-time physical-activity habits over three decades (TWINACTIVE study). In our discordant-pair study design, after adjusting for sequence-level genes, both systemic-level metabolic, and site-specific structural findings differed significantly in the pairwise analysis in MZ pairs only. These findings included intrapair differences in accumulated fat depots and structure of heart, arteries, and bones. In addition, our study revealed intrapair differences in metabolic and regulatory pathways, which may partly explain the mechanistic links between long-term physical activity, phenotypic changes, and decreased risk of cardiometabolic diseases.

  7. Effect of Paired-Pulse Electrical Stimulation on the Activity of Cortical Circuits

    PubMed Central

    Saito, Kei; Onishi, Hideaki; Miyaguchi, Shota; Kotan, Shinichi; Fujimoto, Shuhei

    2015-01-01

    Objective: We investigated the transient effect of short-duration paired-pulse electrical stimulation (ppES) on corticospinal excitability and the after-effect of long-duration ppES on excitability, short-latency afferent inhibition (SAI), and afferent facilitation (AF). Methods: A total of 28 healthy subjects participated in two different experiments. In Experiment 1, motor-evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles before and immediately after short-duration ppES (5 s) at various inter-pulse intervals (2, 3, 4, 5, 6, 7, 10, 15, 20, and 30 ms). In Experiment 2, MEPs, SAI, and AF were measured before, immediately, and 20 and 40 min after long-duration ppES (20 min, inter-pulse interval of 5 and 15 ms) and peripheral electrical stimulation (20 min, 10 and 20 Hz). Results: Short-duration ppES with inter-pulse intervals of 5 and 20 ms significantly increased MEP measured in APB but not in ADM. Long-duration ppES with an inter-pulse interval of 5 ms significantly decreased SAI but not MEPs in APB. In contrast, long-duration ppES did not affect ADM. Conclusion: The afferent inputs induced by ppES-5 ms were effective for transiently increasing MEP and sustaining SAI reduction. PMID:26733847

  8. Active vibration reduction of a flexible structure bonded with optimised piezoelectric pairs using half and quarter chromosomes in genetic algorithms

    NASA Astrophysics Data System (ADS)

    Daraji, A. H.; Hale, J. M.

    2012-08-01

    The optimal placement of sensors and actuators in active vibration control is limited by the number of candidates in the search space. The search space of a small structure discretized to one hundred elements for optimising the location of ten actuators gives 1.73 × 1013 possible solutions, one of which is the global optimum. In this work, a new quarter and half chromosome technique based on symmetry is developed, by which the search space for optimisation of sensor/actuator locations in active vibration control of flexible structures may be greatly reduced. The technique is applied to the optimisation for eight and ten actuators located on a 500×500mm square plate, in which the search space is reduced by up to 99.99%. This technique helps for updating genetic algorithm program by updating natural frequencies and mode shapes in each generation to find the global optimal solution in a greatly reduced number of generations. An isotropic plate with piezoelectric sensor/actuator pairs bonded to its surface was investigated using the finite element method and Hamilton's principle based on first order shear deformation theory. The placement and feedback gain of ten and eight sensor/actuator pairs was optimised for a cantilever and clamped-clamped plate to attenuate the first six modes of vibration, using minimization of linear quadratic index as an objective function.

  9. Paired Ig-Like Type 2 Receptor-Derived Agonist Ligands Ameliorate Inflammatory Reactions by Downregulating β1 Integrin Activity

    PubMed Central

    Lee, Kyoung-Jin; Lim, Dongyoung; Yoo, Yeon Ho; Park, Eun-Ji; Lee, Sun-Hee; Yadav, Birendra Kumar; Lee, Yong-Ki; Park, Jeong Hyun; Kim, Daejoong; Park, Kyeong Han; Hahn, Jang-Hee

    2016-01-01

    The paired immunoglobulin-like type 2 receptor (PILR) family consists of two functionally opposite members, inhibitory PILRα and activating PILRβ receptors. PILRs are widely expressed in various immune cells and interact with their ligands, especially CD99 expressed on activated T cells, to participate in immune responses. Here we investigated whether PILR-derived agonists inhibit β1 integrin activity as ligands for CD99. PILR-derived peptides as well as PILR-Fc fusion proteins prevented cell adhesion to fibronectin through the regulation of β1 integrin activity. Especially, PILRpep3, a representative 3-mer peptide covering the conserved motifs of the PILR extracellular domain, prevented the clustering and activation of β1 integrin by dephosphorylating FAK and vinculin, which are major components of focal adhesion. In addition, PILRpep3 inhibited transendothelial migration of monocytes as well as endothelial cell tube formation. Furthermore, upon intraperitoneal injection of PILRpep3 into mice with collagen-induced arthritis, the inflammatory response of rheumatoid arthritis was strongly suppressed. Taken together, these results suggest that PILR-derived agonist ligands may prevent the inflammatory reactions of rheumatoid arthritis by activating CD99. PMID:27306643

  10. Active tuning of vibration and wave propagation in elastic beams with periodically placed piezoelectric actuator/sensor pairs

    NASA Astrophysics Data System (ADS)

    Li, Fengming; Zhang, Chuanzeng; Liu, Chunchuan

    2017-04-01

    A novel strategy is proposed to actively tune the vibration and wave propagation properties in elastic beams. By periodically placing the piezoelectric actuator/sensor pairs along the beam axis, an active periodic beam structure which exhibits special vibration and wave propagation properties such as the frequency pass-bands and stop-bands (or band-gaps) is developed. Hamilton's principle is applied to establish the equations of motion of the sub-beam elements i.e. the unit-cells, bonded by the piezoelectric patches. A negative proportional feedback control strategy is employed to design the controllers which can provide a positive active stiffness to the beam for a positive feedback control gain, which can increase the stability of the structural system. By means of the added positive active stiffness, the periodicity or the band-gap property of the beam with periodically placed piezoelectric patches can be actively tuned. From the investigation, it is shown that better band-gap characteristics can be achieved by using the negative proportional feedback control. The band-gaps can be obviously broadened by properly increasing the control gain, and they can also be greatly enlarged by appropriately designing the structural sizes of the controllers. The control voltages applied on the piezoelectric actuators are in reasonable and controllable ranges, especially, they are very low in the band-gaps. Thus, the vibration and wave propagation behaviors of the elastic beam can be actively controlled by the periodically placed piezoelectric patches.

  11. Pick a Pair. Pancake Pairs

    ERIC Educational Resources Information Center

    Miller, Pat

    2005-01-01

    Cold February weather and pancakes are a traditional pairing. Pancake Day began as a way to eat up the foods that were abstained from in Lent--traditionally meat, fat, eggs and dairy products. The best-known pancake event is The Pancake Day Race in Buckinghamshire, England, which has been run since 1445. This column describes pairs of books that…

  12. Early base-pair fluctuations and the activation of mRNA splicing

    NASA Astrophysics Data System (ADS)

    Fernández, Ariel

    1991-05-01

    By means of multiprocessed Monte Carlo simulations we study the amplification in time structural fluctuations in sequential RNA folding concomitant with transcription. The simulations allow for an exploration of configuration space subject to the realistic time-constraints of RNA synthesis. The treatment focuses on the splicing YC4 intron as a study case. We show how an early disruption in the folding may result in a terminal structure which is active for splicing, bringing together the two cleavage sites at both ends of the intron.

  13. A 3 base pair deletion in TBX1 leads to reduced protein expression and transcriptional activity

    PubMed Central

    Xu, Yuejuan; Fang, Shaohai; Zhang, Erge; Pu, Tian; Cao, Ruixue; Fu, Qihua; Li, Fen; Chen, Sun; Sun, Kun; Xu, Rang

    2017-01-01

    Transcription factor TBX1 plays a pivotal role in heart development and has been implicated in 22q11.2 deletion syndrome. The structure of this protein has been elucidated, and several mutations have been identified that disrupt TBX1 localization, DNA/protein-binding, or mRNA expression. This study reports a mutation in the TBX1 gene that leads to significantly reduced expression of the mutant protein. A total of 773 conotruncal heart defect patients and 516 unrelated healthy control individuals were enrolled, none of which harbored a 22q11.2 deletion or duplication. We identified a mutation, c.303-305delGAA, located in the third exon of TBX1 that does not disrupt TBX1 mRNA expression or DNA binding activity, but results in decreased TBX1 protein levels and transcriptional activity. Through protein degradation studies we demonstrated that TBX1 is degraded primarily in proteasomes. Although the c.303-305delGAA mutation leads to low levels of the mutant protein, we found that increased protein degradation was not the cause, and we hypothesize that an alternate mechanism, such as translational inhibition, may be the cause. PMID:28272434

  14. A comparison of vitamin D activity in paired non-malignant and malignant human breast tissues.

    PubMed

    Suetani, Rachel J; Ho, Kristen; Jindal, Shalini; Manavis, Jim; Neilsen, Paul M; Pishas, Kathleen I; Rippy, Elisabeth; Bochner, Melissa; Kollias, James; Gill, P Grantley; Morris, Howard A; Callen, David F

    2012-10-15

    Links between a low vitamin D status and an increased risk of breast cancer have been observed in epidemiological studies. These links have been investigated in human tissue homogenates and cultured cell lines. We have used non-malignant, malignant and normal reduction mammoplasty breast tissues to investigate the biological and metabolic consequences of the application of vitamin D to intact ex vivo human breast tissue. Tissues were exposed to 1α,25(OH)(2)D(3) (1,25D; active metabolite) and 25(OH)D (25D; pre-metabolite). Changes in mRNA expression and protein expression after vitamin D exposure were analysed. Results indicate that while responses in normal and non-malignant breast tissues are similar between individuals, different tumour tissues are highly variable with regards to their gene expression and biological response. Collectively, malignant breast tissue responds well to active 1,25D, but not to the inactive pre-metabolite 25D. This may have consequences for the recommendation of vitamin D supplementation in breast cancer patients.

  15. Identifying a Selective Substrate and Inhibitor Pair for the Evaluation of CYP2J2 Activity

    PubMed Central

    Lee, Caroline A.; Jones, J. P.; Katayama, Jonathan; Kaspera, Rüdiger; Jiang, Ying; Freiwald, Sascha; Smith, Evan; Walker, Gregory S.

    2012-01-01

    CYP2J2, an arachidonic acid epoxygenase, is recognized for its role in the first-pass metabolism of astemizole and ebastine. To fully assess the role of CYP2J2 in drug metabolism, a selective substrate and potent specific chemical inhibitor are essential. In this study, we report amiodarone 4-hydoxylation as a specific CYP2J2-catalyzed reaction with no CYP3A4, or other drug-metabolizing enzyme, involvement. Amiodarone 4-hydroxylation enabled the determination of liver relative activity factor and intersystem extrapolation factor for CYP2J2. Amiodarone 4-hydroxylation correlated with astemizole O-demethylation but not with CYP2J2 protein content in a sample of human liver microsomes. To identify a specific CYP2J2 inhibitor, 138 drugs were screened using terfenadine and astemizole as probe substrates with recombinant CYP2J2. Forty-two drugs inhibited CYP2J2 activity by ≥50% at 30 μM, but inhibition was substrate-dependent. Of these, danazol was a potent inhibitor of both hydroxylation of terfenadine (IC50 = 77 nM) and O-demethylation of astemizole (Ki = 20 nM), and inhibition was mostly competitive. Danazol inhibited CYP2C9, CYP2C8, and CYP2D6 with IC50 values of 1.44, 1.95, and 2.74 μM, respectively. Amiodarone or astemizole were included in a seven-probe cocktail for cytochrome P450 (P450) drug-interaction screening potential, and astemizole demonstrated a better profile because it did not appreciably interact with other P450 probes. Thus, danazol, amiodarone, and astemizole will facilitate the ability to determine the metabolic role of CYP2J2 in hepatic and extrahepatic tissues. PMID:22328583

  16. Identifying a selective substrate and inhibitor pair for the evaluation of CYP2J2 activity.

    PubMed

    Lee, Caroline A; Jones, J P; Katayama, Jonathan; Kaspera, Rüdiger; Jiang, Ying; Freiwald, Sascha; Smith, Evan; Walker, Gregory S; Totah, Rheem A

    2012-05-01

    CYP2J2, an arachidonic acid epoxygenase, is recognized for its role in the first-pass metabolism of astemizole and ebastine. To fully assess the role of CYP2J2 in drug metabolism, a selective substrate and potent specific chemical inhibitor are essential. In this study, we report amiodarone 4-hydoxylation as a specific CYP2J2-catalyzed reaction with no CYP3A4, or other drug-metabolizing enzyme, involvement. Amiodarone 4-hydroxylation enabled the determination of liver relative activity factor and intersystem extrapolation factor for CYP2J2. Amiodarone 4-hydroxylation correlated with astemizole O-demethylation but not with CYP2J2 protein content in a sample of human liver microsomes. To identify a specific CYP2J2 inhibitor, 138 drugs were screened using terfenadine and astemizole as probe substrates with recombinant CYP2J2. Forty-two drugs inhibited CYP2J2 activity by ≥50% at 30 μM, but inhibition was substrate-dependent. Of these, danazol was a potent inhibitor of both hydroxylation of terfenadine (IC(50) = 77 nM) and O-demethylation of astemizole (K(i) = 20 nM), and inhibition was mostly competitive. Danazol inhibited CYP2C9, CYP2C8, and CYP2D6 with IC(50) values of 1.44, 1.95, and 2.74 μM, respectively. Amiodarone or astemizole were included in a seven-probe cocktail for cytochrome P450 (P450) drug-interaction screening potential, and astemizole demonstrated a better profile because it did not appreciably interact with other P450 probes. Thus, danazol, amiodarone, and astemizole will facilitate the ability to determine the metabolic role of CYP2J2 in hepatic and extrahepatic tissues.

  17. (±)-Japonones A and B, two pairs of new enantiomers with anti-KSHV activities from Hypericum japonicum

    PubMed Central

    Hu, Linzhen; Zhu, Hucheng; Li, Lei; Huang, Jinfeng; Sun, Weiguang; Liu, Junjun; Li, Hua; Luo, Zengwei; Wang, Jianping; Xue, Yongbo; Zhang, Yu; Zhang, Yonghui

    2016-01-01

    Two pairs of new enantiomers with unusual 5,5-spiroketal cores, termed (±)-japonones A and B [(±)-1 and (±)-2], were obtained from Hypericum japonicum Thunb. The absolute configurations of (±)-1 and (±)-2 were characterized by extensive analyses of spectroscopic data and calculated electronic circular dichroism (ECD) spectra, the application of modified Mosher’s methods, and the assistance of quantum chemical predictions (QCP) of 13C NMR chemical shifts. Among these metabolites, (+)-1 exhibited some inhibitory activity on Kaposi’s sarcoma associated herpesvirus (KSHV). Virtual screening of (±)-1 and (±)-2 were conducted using the Surflex-Dock module in the Sybyl software, and (+)-1 exhibited ability to bind with ERK to form key interactions with residues Lys52, Pro56, Ile101, Asp165, Gly167 and Val99. PMID:27270221

  18. (±)-Japonones A and B, two pairs of new enantiomers with anti-KSHV activities from Hypericum japonicum

    NASA Astrophysics Data System (ADS)

    Hu, Linzhen; Zhu, Hucheng; Li, Lei; Huang, Jinfeng; Sun, Weiguang; Liu, Junjun; Li, Hua; Luo, Zengwei; Wang, Jianping; Xue, Yongbo; Zhang, Yu; Zhang, Yonghui

    2016-06-01

    Two pairs of new enantiomers with unusual 5,5-spiroketal cores, termed (±)-japonones A and B [(±)-1 and (±)-2], were obtained from Hypericum japonicum Thunb. The absolute configurations of (±)-1 and (±)-2 were characterized by extensive analyses of spectroscopic data and calculated electronic circular dichroism (ECD) spectra, the application of modified Mosher’s methods, and the assistance of quantum chemical predictions (QCP) of 13C NMR chemical shifts. Among these metabolites, (+)-1 exhibited some inhibitory activity on Kaposi’s sarcoma associated herpesvirus (KSHV). Virtual screening of (±)-1 and (±)-2 were conducted using the Surflex-Dock module in the Sybyl software, and (+)-1 exhibited ability to bind with ERK to form key interactions with residues Lys52, Pro56, Ile101, Asp165, Gly167 and Val99.

  19. The numerical condition of electron correlation theories when only active pairs of electrons are spin-unrestricted.

    PubMed

    Lawler, Keith V; Parkhill, John A; Head-Gordon, Martin

    2009-05-14

    The use of spin-unrestriction with high-quality correlation theory, such as coupled-cluster (CC) methods, is a common practice necessary to obtain high-quality potential energy surfaces. While this typically is a useful approach, we find that in the unrestricted limit of ROHF fragments (the unrestricted in active pair orbitals) the CC equations are singular if only the strongly correlated electrons are considered. Unstable amplitudes which do not represent the physics of the problem are easily found and could be unwittingly accepted without inspection. We use stability analysis and the condition number of the CC doubles Jacobian matrix to examine the problem, and present results for several molecular systems with a variety of unrestricted cluster models. Finally a regularization of the CC equations is proposed, using a dynamic penalty function, which allows us to apply CC, and Lagrangian gradient formulas even in the singular limit.

  20. On the Origin of Muscle Synergies: Invariant Balance in the Co-activation of Agonist and Antagonist Muscle Pairs

    PubMed Central

    Hirai, Hiroaki; Miyazaki, Fumio; Naritomi, Hiroaki; Koba, Keitaro; Oku, Takanori; Uno, Kanna; Uemura, Mitsunori; Nishi, Tomoki; Kageyama, Masayuki; Krebs, Hermano Igo

    2015-01-01

    Investigation of neural representation of movement planning has attracted the attention of neuroscientists, as it may reveal the sensorimotor transformation essential to motor control. The analysis of muscle synergies based on the activity of agonist–antagonist (AA) muscle pairs may provide insight into such transformations, especially for a reference frame in the muscle space. In this study, we examined the AA concept using the following explanatory variables: the AA ratio, which is related to the equilibrium-joint angle, and the AA sum, which is associated with joint stiffness. We formulated muscle synergies as a function of AA sums, positing that muscle synergies are composite units of mechanical impedance. The AA concept can be regarded as another form of the equilibrium-point (EP) hypothesis, and it can be extended to the concept of EP-based synergies. We introduce, here, a novel tool for analyzing the neurological and motor functions underlying human movements and review some initial insights from our results about the relationships between muscle synergies, endpoint stiffness, and virtual trajectories (time series of EP). Our results suggest that (1) muscle synergies reflect an invariant balance in the co-activation of AA muscle pairs; (2) each synergy represents the basis for the radial, tangential, and null movements of the virtual trajectory in the polar coordinates centered on the specific joint at the base of the body; and (3) the alteration of muscle synergies (for example, due to spasticity or rigidity following neurological injury) results in significant distortion of endpoint stiffness and concomitant virtual trajectories. These results indicate that muscle synergies (i.e., the balance of muscle mechanical impedance) are essential for motor control. PMID:26636079

  1. Reinstatement of pain-related brain activation during the recognition of neutral images previously paired with nociceptive stimuli.

    PubMed

    Forkmann, Katarina; Wiech, Katja; Sommer, Tobias; Bingel, Ulrike

    2015-08-01

    Remembering an event partially reactivates cortical and subcortical brain regions that were engaged during its experience and encoding. Such reinstatement of neuronal activation has been observed in different sensory systems, including the visual, auditory, olfactory, and somatosensory domain. However, so far, this phenomenon of incidental memory has not been explored in the context of pain. In this functional magnetic resonance imaging study, we investigated the neural reinstatement of pain-related and tone-related activations during the recognition of neutral images that had been encoded during (1) painful stimulation, (2) auditory stimulation of comparable unpleasantness, or (3) no additional stimulation. Stimulus-specific reinstatement was tested in 24 healthy male and female participants who performed a visual categorization task (encoding) that was immediately followed by a surprise recognition task. Neural responses were acquired in both sessions. Our data show a partial reinstatement of brain regions frequently associated with pain processing, including the left posterior insula, bilateral putamen, and right operculum, during the presentation of images previously paired with painful heat. This effect was specific to painful stimuli. Moreover, the bilateral ventral striatum showed stronger responses for remembered pain-associated images as compared with tone-associated images, suggesting a higher behavioral relevance of remembering neutral pictures previously paired with pain. Our results support the biological relevance of pain in that only painful but not equally unpleasant auditory stimuli were able to "tag" neutral images during their simultaneous presentation and reactivate pain-related brain regions. Such mechanisms might contribute to the development or maintenance of chronic pain and deserve further investigation in clinical populations.

  2. On the Origin of Muscle Synergies: Invariant Balance in the Co-activation of Agonist and Antagonist Muscle Pairs.

    PubMed

    Hirai, Hiroaki; Miyazaki, Fumio; Naritomi, Hiroaki; Koba, Keitaro; Oku, Takanori; Uno, Kanna; Uemura, Mitsunori; Nishi, Tomoki; Kageyama, Masayuki; Krebs, Hermano Igo

    2015-01-01

    Investigation of neural representation of movement planning has attracted the attention of neuroscientists, as it may reveal the sensorimotor transformation essential to motor control. The analysis of muscle synergies based on the activity of agonist-antagonist (AA) muscle pairs may provide insight into such transformations, especially for a reference frame in the muscle space. In this study, we examined the AA concept using the following explanatory variables: the AA ratio, which is related to the equilibrium-joint angle, and the AA sum, which is associated with joint stiffness. We formulated muscle synergies as a function of AA sums, positing that muscle synergies are composite units of mechanical impedance. The AA concept can be regarded as another form of the equilibrium-point (EP) hypothesis, and it can be extended to the concept of EP-based synergies. We introduce, here, a novel tool for analyzing the neurological and motor functions underlying human movements and review some initial insights from our results about the relationships between muscle synergies, endpoint stiffness, and virtual trajectories (time series of EP). Our results suggest that (1) muscle synergies reflect an invariant balance in the co-activation of AA muscle pairs; (2) each synergy represents the basis for the radial, tangential, and null movements of the virtual trajectory in the polar coordinates centered on the specific joint at the base of the body; and (3) the alteration of muscle synergies (for example, due to spasticity or rigidity following neurological injury) results in significant distortion of endpoint stiffness and concomitant virtual trajectories. These results indicate that muscle synergies (i.e., the balance of muscle mechanical impedance) are essential for motor control.

  3. Experimental study on activated carbon-nitrogen pair in a prototype pressure swing adsorption refrigeration system

    NASA Astrophysics Data System (ADS)

    Anupam, Kumar; Palodkar, Avinash V.; Halder, G. N.

    2016-04-01

    Pressure swing adsorption of nitrogen onto granular activated carbon in the single-bed adsorber-desorber chamber has been studied at six different pressures 6-18 kgf/cm2 to evaluate their performance as an alternative refrigeration technique. Refrigerating effect showed a linear rise with an increase in the operating pressure. However, the heat of adsorption and COP exhibited initial rise with the increasing operating pressure but decreased later after reaching a maximum value. The COP initially increases with operating pressures however, with the further rise of operating pressure it steadily decreased. The highest average refrigeration, maximum heat of adsorption and optimum coefficient of performance was evaluated to be 415.38 W at 18 kgf/cm2, 92756.35 J at 15 kgf/cm2 and 1.32 at 12 kgf/cm2, respectively. The system successfully produced chilled water at 1.7 °C from ambient water at 28.2 °C.

  4. Is a lone right hemisphere enough? Neurolinguistic architecture in a case with a very early left hemispherectomy.

    PubMed

    Danelli, Laura; Cossu, Giuseppe; Berlingeri, Manuela; Bottini, Gabriella; Sberna, Maurizio; Paulesu, Eraldo

    2013-01-01

    We studied the linguistic profile and neurolinguistic organization of a 14-year-old adolescent (EB) who underwent a left hemispherectomy at the age of 2.5 years. After initial aphasia, his language skills recovered within 2 years, with the exception of some word finding problems. Over the years, the neuropsychological assessments showed that EB's language was near-to-normal, with the exception of lexical competence, which lagged slightly behind for both auditory and written language. Moreover, EB's accuracy and speed in both reading and writing words and non-words were within the normal range, whereas difficulties emerged in reading loan words and in tasks with homophones. EB's functional magnetic resonance imaging (fMRI) patterns for several linguistic and metalinguistic tasks were similar to those observed in the dominant hemisphere of controls, suggesting that his language network conforms to a left-like linguistic neural blueprint. However, a stronger frontal recruitment suggests that linguistic tasks are more demanding for him. Finally, no specific reading activation was found in EB's occipitotemporal region, a finding consistent with the surface dyslexia-like behavioral pattern of the patient. While a lone right hemisphere may not be sufficient to guarantee full blown linguistic competences after early hemispherectomy, EB's behavioral and fMRI patterns suggest that his lone right hemisphere followed a left-like blueprint of the linguistic network.

  5. Familial risk and ADHD-specific neural activity revealed by case-control, discordant twin pair design.

    PubMed

    Godinez, Detre A; Willcutt, Erik G; Burgess, Gregory C; Depue, Brendan E; Andrews-Hanna, Jessica R; Banich, Marie T

    2015-09-30

    Individuals with ADHD, as well as their family members who do not meet clinical criteria, have shown deficits in executive function. However, it remains unclear whether underlying neural alterations are familial or ADHD-specific. To investigate this issue, neural activation underlying executive function was assessed using functional magnetic resonance imaging during performance of a Stroop task in three groups of individuals: 20 young adults who were diagnosed with ADHD in childhood, their 20 dizygotic co-twins without ADHD in childhood, and 20 unrelated controls selected from dizygotic twin pairs in which neither twin had ADHD in childhood (total n=60). Implicating the frontoparietal network as a location of effects specific to ADHD, activation in the superior frontal (Brodmann's Area - BA 6) and parietal regions (BA 40) was significantly reduced in twins with childhood ADHD compared to both their control co-twins and unrelated control twins. Consistent with familial influences, activity in the anterior cingulate and insula was significantly reduced in both the twins with ADHD and their co-twins compared to the unrelated controls. These results show that both ADHD-specific and familial influences related to an ADHD diagnosis impact neural systems underlying executive function.

  6. Analysis of the Activation and Heterolytic Dissociation of H2 by Frustrated Lewis Pairs: NH3/BX3 (X = H, F, and Cl)

    SciTech Connect

    Camaioni, Donald M.; Ginovska-Pangovska, Bojana; Schenter, Gregory K.; Kathmann, Shawn M.; Autrey, Thomas

    2012-07-05

    We present results of our computational study aimed at understanding the mechanism of H2 activation and heterolytic dissociation by 'frustrated' Lewis pairs (FLPs). We studied the pairs of ammonia (NH3) with BH3, BF3, and most extensively, BCl3. While these pairs are capable of forming a strong dative bond, electronic structure theories make it possible to explore the potential surface in regions away from the dative complex relevant to H2 activation by frustrated Lewis pairs. We analyzed in great detail the changes that occur along the minimum energy path between the FLP and the product ion pair complex. For X = Cl, the mechanism involves a precursor complex, H3N-H2-BCl3, with a B-H-H angle of {approx}80{sup o} and nearly linear N-H-H angle. At the transition state (TS), the H2 bond is weakened but not broken, and the BCl3 moiety has undergone significant pyramidal distortion. As such, the FLP is prepared to accept the incipient proton and hydride ion on the product-side. The interaction energy of the H2 with the acid/base pair and the different contributions for the precursor and TS complex from an energy decomposition analysis expose the dominant factors affecting the reactivity. We find that structural reorganization of precursor complex plays a significant role in the 'activation' and that charge-transfer interactions are the dominant stabilizing force in the activated complex. The electric field clearly has a role in polarizing H2, but its contribution to the overall interaction energy seems to be smaller. Our detailed study of the nature of the bonding and the different types of interaction between the prototypical Lewis pair and H2 provides insight into the important components that should be taken into account when designing related systems to activate hydrogen.

  7. Characterization of DNA binding and pairing activities associated with the native SFPQ·NONO DNA repair protein complex.

    PubMed

    Udayakumar, Durga; Dynan, William S

    2015-08-07

    Nonhomologous end joining (NHEJ) is a major pathway for repair of DNA double-strand breaks. We have previously shown that a complex of SFPQ (PSF) and NONO (p54(nrb)) cooperates with Ku protein at an early step of NHEJ, forming a committed preligation complex and stimulating end-joining activity by 10-fold or more. SFPQ and NONO show no resemblance to other repair factors, and their mechanism of action is uncertain. Here, we use an optimized microwell-based assay to characterize the in vitro DNA binding behavior of the native SFPQ·NONO complex purified from human (HeLa) cells. SFPQ·NONO and Ku protein bind independently to DNA, with little evidence of cooperativity and only slight mutual interference at high concentration. Whereas Ku protein requires free DNA ends for binding, SFPQ·NONO does not. Both Ku and SFPQ·NONO have pairing activity, as measured by the ability of DNA-bound protein to capture a second DNA fragment in a microwell-based assay. Additionally, SFPQ·NONO stimulates DNA-dependent protein kinase autophosphorylation, consistent with the ability to promote formation of a synaptic complex formation without occluding the DNA termini proper. These findings suggest that SFPQ·NONO promotes end joining by binding to internal DNA sequences and cooperating with other repair proteins to stabilize a synaptic pre-ligation complex.

  8. Transmission of bacterial agents from lone star ticks to white-tailed deer.

    PubMed

    Varela-Stokes, Andrea S

    2007-05-01

    Amblyomma americanum (L.), the lone star tick, is an aggressive ixodid tick that has been implicated as a vector for several bacteria. Among these bacteria are the disease agents Ehrlichia chaffeensis and Ehrlichia ewingii, and the putative disease agent "Borrelia lonestari." The hypothesis in this study was that wild lone star ticks from northeastern Georgia are capable of transmitting all three agents to white-tailed deer, Odocoileus virginianus, a known reservoir host for E. chaffeensis. In this study, transmission of all three agents from wild caught lone star ticks to captive reared white-tailed deer was demonstrated by polymerase chain reaction (PCR), culture, or serology. Two of three deer showed evidence of E. chaffeensis and E. ewingii infection by polymerase chain reaction assay; all three deer showed evidence of B. lonestari by PCR assay. E. chaffeensis was isolated in culture from both PCR-positive deer on multiple days. All three deer seroconverted to E. chaffeensis, whereas one deer seroconverted to B. lonestari. This study supports the role of lone star ticks and white-tailed deer as a vector and reservoir host for E. chaffeensis and E. ewingii and suggests for the first time, transmission of B. lonestari from lone star ticks to white-tailed deer.

  9. Distribution, nesting activities, and age-class of territorial pairs of golden eagles at the Altamont Pass Wind Resource Area, California, 2014–16

    USGS Publications Warehouse

    Kolar, Patrick S.; Wiens, J. David

    2017-03-22

    The substantial numbers of golden eagles (Aquila chrysaetos) killed by collisions with oldgeneration wind turbines each year at the Altamont Pass Wind Resource Area (APWRA) in California has been well documented from previous studies. Few eagle nests have been documented in the APWRA, however, and adults and subadults 3+ years of age killed by turbines were generally not associated with nearby territories. We searched a subset of randomly selected survey plots for territorial pairs of golden eagles and associated nesting attempts within the APWRA as part of a broader investigation of population dynamics in the surrounding northern Diablo Range. In contrast to limited historical observations from 1988 to 2013, our surveys documented up to 15 territorial pairs within 3.2 kilometers (km) of wind turbines at the APWRA annually, 9 of which were not previously documented or only observed intermittently during historical surveys. We found evidence of nesting activity by adult pairs at least once during our study at six of these territories. We also determined that 23–36 percent of territories identified within 3.2 km of the APWRA had a subadult pair member, but that no pairs with a subadult member attempted to nest. These data will be useful to developers, wildlife managers, and future raptor studies in the area to evaluate and minimize the potential effects of wind energy or other development activities on previously unknown territorial pairs in the area.

  10. Structure of the 2-Aminopurine-Cytosine Base Pair Formed in the Polymerase Active Site of the RB69 Y567A-DNA Polymerase

    SciTech Connect

    Reha-Krantz, Linda J.; Hariharan, Chithra; Subuddhi, Usharani; Xia, Shuangluo; Zhao, Chao; Beckman, Jeff; Christian, Thomas; Konigsberg, William

    2011-11-21

    The adenine base analogue 2-aminopurine (2AP) is a potent base substitution mutagen in prokaryotes because of its enhanceed ability to form a mutagenic base pair with an incoming dCTP. Despite more than 50 years of research, the structure of the 2AP-C base pair remains unclear. We report the structure of the 2AP-dCTP base pair formed within the polymerase active site of the RB69 Y567A-DNA polymerase. A modified wobble 2AP-C base pair was detected with one H-bond between N1 of 2AP and a proton from the C4 amino group of cytosine and an apparent bifurcated H-bond between a proton on the 2-amino group of 2-aminopurine and the ring N3 and O2 atoms of cytosine. Interestingly, a primer-terminal region rich in AT base pairs, compared to GC base pairs, facilitated dCTP binding opposite template 2AP. We propose that the increased flexibility of the nucleotide binding pocket formed in the Y567A-DNA polymerase and increased 'breathing' at the primer-terminal junction of A+T-rich DNA facilitate dCTP binding opposite template 2AP. Thus, interactions between DNA polymerase residues with a dynamic primer-terminal junction play a role in determining base selectivity within the polymerase active site of RB69 DNA polymerase.

  11. Carbon sink activity is stronger under grazing than under mowing: results from a paired eddy flux towers experiment

    NASA Astrophysics Data System (ADS)

    Pintér, Krisztina; Balogh, János; Koncz, Péter; Hidy, Dóra; Cserhalmi, Dóra; Papp, Marianna; Fóti, Szilvia; Nagy, Zoltán

    2014-05-01

    Effect of grazing vs. mowing on carbon balance of a grassland was investigated by a paired eddy towers (one of them measuring the grazed, the another the mowed treatment) experiment at the Bugacpuszta sandy grassland site (HU-Bug, 46.69° N, 19.6° E, 114m asl, 10.4 ° C annual mean temperature, 562 mm annual precipitation sum) located in the Hungarian Plain. Eddy covariance measurements started in July, 2002. The area of the mowed treatment is 1 ha, it is located within the grazed treatment (500 ha). Electric fence was set up around the selected area in spring of 2011. Study years include 2011, 2012 and 2013. The pasture is managed extensively (average grazing pressure of 0.5 cattle per hectare), the cattle herd regularly took several kilometres during a grazing day. Annual net ecosystem exchange (NEE) of the grassland is strongly limited by precipitation, there were 2 source years within the 11 years (2003-2013) of measurements, during which the average annual balance was -109 gCm-2year-1 with standard deviation of 106 gCm-2year-1. Carbon sink activity of the grassland was stronger in the grazed treatment than in the mowed treatment during the three year study period (paired t-test, P=0.058). In the grazed treatment the average sink strength was -142.8 ±40 gCm-2year-1, while in the mowed treatment the average sink strength was -61.5 ±46.5 gCm-2year-1. Differences of carbon balances between the treatments were positively correlated to the annual sum of evapotranspiration (ET), while ETs of the treatments were almost identical (differences within a 10mm year-1 range) in each study year. Water use efficiency in the mowed treatment was 44% of that in the grazed treatment (P=0.045) as a result of the differences in sink capacity. The higher sensitivity to drought by the mowed treatment manifested in decreased sink capacity during summer and in decreased regeneration capacity during autumn rains as shown by the cumulative NEE in the different years. Minor but

  12. Accommodation of an N-(deoxyguanosin-8-yl)-2-acetylaminofluorene adduct in the active site of human DNA polymerase iota: Hoogsteen or Watson-Crick base pairing?

    PubMed

    Donny-Clark, Kerry; Shapiro, Robert; Broyde, Suse

    2009-01-13

    Bypass across DNA lesions by specialized polymerases is essential for maintenance of genomic stability. Human DNA polymerase iota (poliota) is a bypass polymerase of the Y family. Crystal structures of poliota suggest that Hoogsteen base pairing is employed to bypass minor groove DNA lesions, placing them on the spacious major groove side of the enzyme. Primer extension studies have shown that poliota is also capable of error-free nucleotide incorporation opposite the bulky major groove adduct N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-AAF). We present molecular dynamics simulations and free energy calculations suggesting that Watson-Crick base pairing could be employed in poliota for bypass of dG-AAF. In poliota with Hoogsteen-paired dG-AAF the bulky AAF moiety would reside on the cramped minor groove side of the template. The Hoogsteen-capable conformation distorts the active site, disrupting interactions necessary for error-free incorporation of dC opposite the lesion. Watson-Crick pairing places the AAF rings on the spacious major groove side, similar to the position of minor groove adducts observed with Hoogsteen pairing. Watson-Crick-paired structures show a well-ordered active site, with a near reaction-ready ternary complex. Thus our results suggest that poliota would utilize the same spacious region for lesion bypass of both major and minor groove adducts. Therefore, purine adducts with bulk on the minor groove side would use Hoogsteen pairing, while adducts with the bulky lesion on the major groove side would utilize Watson-Crick base pairing as indicated by our MD simulations for dG-AAF. This suggests the possibility of an expanded role for poliota in lesion bypass.

  13. The AVR2-SIX5 gene pair is required to activate I-2-mediated immunity in tomato.

    PubMed

    Ma, Lisong; Houterman, Petra M; Gawehns, Fleur; Cao, Lingxue; Sillo, Fabiano; Richter, Hanna; Clavijo-Ortiz, Myriam J; Schmidt, Sarah M; Boeren, Sjef; Vervoort, Jacques; Cornelissen, Ben J C; Rep, Martijn; Takken, Frank L W

    2015-10-01

    Plant-invading microbes betray their presence to a plant by exposure of antigenic molecules such as small, secreted proteins called 'effectors'. In Fusarium oxysporum f. sp. lycopersici (Fol) we identified a pair of effector gene candidates, AVR2-SIX5, whose expression is controlled by a shared promoter. The pathogenicity of AVR2 and SIX5 Fol knockouts was assessed on susceptible and resistant tomato (Solanum lycopersicum) plants carrying I-2. The I-2 NB-LRR protein confers resistance to Fol races carrying AVR2. Like Avr2, Six5 was found to be required for full virulence on susceptible plants. Unexpectedly, each knockout could breach I-2-mediated disease resistance. So whereas Avr2 is sufficient to induce I-2-mediated cell death, Avr2 and Six5 are both required for resistance. Avr2 and Six5 interact in yeast two-hybrid assays as well as in planta. Six5 and Avr2 accumulate in xylem sap of plants infected with the reciprocal knockouts, showing that lack of I-2 activation is not due to a lack of Avr2 accumulation in the SIX5 mutant. The effector repertoire of a pathogen determines its host specificity and its ability to manipulate plant immunity. Our findings challenge an oversimplified interpretation of the gene-for-gene model by showing requirement of two fungal genes for immunity conferred by one resistance gene.

  14. The Association of Lone-Motherhood with Smoking Cessation and Relapse: Prospective Results from an Australian National Study

    PubMed Central

    Siahpush, Mohammad; Shaikh, Raees A.; Tibbits, Melissa; Huang, Terry T-K; Singh, Gopal K.

    2013-01-01

    The aims were to examine the association of lone-motherhood with smoking cessation and relapse, and to investigate the extent to which this association was accounted for by socioeconomic status (education, occupation, and income), social support, and mental health. We used data from 10 yearly waves (2001 to 2010) of the Household Income and Labour Dynamics in Australia (HILDA) survey. Response rate in the first wave was 66%. Logistic regression was used to examine the effect of lone-motherhood and other covariates on smoking cessation (n = 2,878) and relapse (n = 3,242). Results showed that the age-adjusted odds of smoking cessation were 32% smaller among lone mothers than partnered mothers (p = 0.004). The age-adjusted odds of relapse was 172% greater among lone mothers than partnered mothers (p < 0.001). We found that socioeconomic status, social support, and mental health account for some of the association of lone motherhood and cessation and relapse. While efforts to reduce the smoking prevalence among lone mothers should focus on their material deprivation, availability of social support, and addressing mental health issues, other factors unique to the lives of lone mothers also need to be taken into account. More research is needed to discover other factors that can explain the association of lone-motherhood and smoking behavior. PMID:23880726

  15. ACTIVE GALACTIC NUCLEUS PAIRS FROM THE SLOAN DIGITAL SKY SURVEY. II. EVIDENCE FOR TIDALLY ENHANCED STAR FORMATION AND BLACK HOLE ACCRETION

    SciTech Connect

    Liu Xin; Shen Yue; Strauss, Michael A.

    2012-01-20

    Active galactic nuclei (AGNs) are occasionally seen in pairs, suggesting that tidal encounters are responsible for the accretion of material by both central supermassive black holes (BHs). In Paper I of this series, we selected a sample of AGN pairs with projected separations r{sub p} < 100 h{sup -1}{sub 70} kpc and velocity offsets <600 km s{sup -1} from the Seventh Data Release of the Sloan Digital Sky Survey and quantified their frequency. In this paper, we address the BH accretion and recent star formation properties in their host galaxies. AGN pairs experience stronger BH accretion, as measured by their [O III] {lambda}5007 luminosities (corrected for contribution from star formation) and Eddington ratios, than do control samples of single AGNs matched in redshift and host-galaxy stellar mass. Their host galaxies have stronger post-starburst activity and younger mean stellar ages, as indicated by stronger H{delta} absorption and smaller 4000 A break in their spectra. The BH accretion and recent star formation in the host galaxies both increase with decreasing projected separation in AGN pairs, for r{sub p} {approx}< 10-30 h{sup -1}{sub 70} kpc. The intensity of BH accretion, the post-starburst strength, and the mean stellar ages are correlated between the two AGNs in a pair. The luminosities and Eddington ratios of AGN pairs are correlated with recent star formation in their host galaxies, with a scaling relation consistent with that observed in single AGNs. Our results suggest that galaxy tidal interactions enhance both BH accretion and host-galaxy star formation in close AGN pairs, even though the majority of low-redshift AGNs are not coincident with on-going interactions.

  16. Latest Pleistocene and Holocene slip rates on the Lone Mountain fault: Evidence for accelerating slip in the Silver Peak-Lone Mountain extensional complex

    NASA Astrophysics Data System (ADS)

    Lifton, Zachery M.; Frankel, Kurt L.; Newman, Andrew V.

    2015-03-01

    Determining the constancy of fault slip rates over time is critical in characterizing strain distribution across plate boundaries such as the Pacific-North American plate boundary in the western U.S. We present results from the Lone Mountain fault, a normal fault within the southern Walker Lane, that suggest slip rates there may have increased approximately twofold since the late Pleistocene. We combine detailed field surficial mapping, topographic surveying, and 10Be cosmogenic nuclide exposure ages to calculate new late Pleistocene and Holocene slip rates on the Lone Mountain fault. Alluvial fans with ages of 14.6 ± 1.4 ka and 8.0 ± 0.9 ka are vertically offset 10.2 ± 0.6 m and 4.7 ± 0.6 m, respectively, yielding vertical slip rates of 0.7 ± 0.1 mm/yr and 0.6 ± 0.1 mm/yr. These slip rates are faster than the rates of 0.1 to 0.4 mm/yr from earlier in the Pleistocene, defining a pattern of accelerating slip on the Lone Mountain fault over a timescale of 104 years. The possibility of accelerating slip rates in parts of the Walker Lane partially reconciles the observed discrepancy between long- and short-term slip rates in this region and elucidates the distribution of strain across an evolving plate boundary.

  17. Negotiating the Risk of Debt-Financed Higher Education: The Experience of Lone Parent Students

    ERIC Educational Resources Information Center

    Hinton-Smith, Tamsin

    2016-01-01

    Widening participation has opened higher education (HE) to diverse learners, but in doing so has created challenges negotiating situations of disadvantaged positioning compared with peers conforming more closely to the ideal "bachelor boy" student. As one of the most financially vulnerable groups of students, lone parents occupy a doubly…

  18. Success as a Lone Arranger: Setting Priorities and Getting the Job Done

    ERIC Educational Resources Information Center

    Pevar, Susan

    2005-01-01

    The archivist who works alone in a repository, rather than as part of a team-the so-called "Lone Arranger"--has the responsibility of handling all areas of archives management, including appraising, accessioning, processing, arrangement and description, reference, and outreach. This essay describes one real-life situation, in which the…

  19. Forget the Alamo: Thinking about History in John Sayles' "Lone Star"

    ERIC Educational Resources Information Center

    Adams, Anna

    2007-01-01

    John Sayles' film "Lone Star" is an excellent vehicle for teaching about the production and interpretation of history in a high school or introductory level college history class. The film illustrates that history is subjective, that the sorting and arrangement of evidence is what makes history, and that history is not necessarily an inevitable…

  20. If you know a lonely older person, try tea and empathy.

    PubMed

    Rance, Mary

    2016-11-30

    One third of people say they are aware of lonely older people in their communities and one in four are aware but do not know how to offer adequate help. These are two of the startling findings from our latest research.

  1. Cooper Pair Insulators

    NASA Astrophysics Data System (ADS)

    Valles, James

    One of the recent advances in the field of the Superconductor to Insulator Transition (SIT) has been the discovery and characterization of the Cooper Pair Insulator phase. This bosonic insulator, which consists of localized Cooper pairs, exhibits activated transport and a giant magneto-resistance peak. These features differ markedly from the weakly localized transport that emerges as pairs break at a ``fermionic'' SIT. I will describe how our experiments on films nano-patterned with a nearly triangular array of holes have enabled us to 1) distinguish bosonic insulators from fermionic insulators, 2) show that Cooper pairs, rather than quasi-particles dominate the transport in the Cooper Pair insulator phase, 3) demonstrate that very weak, sub nano-meter thickness inhomogeneities control whether a bosonic or fermionic insulator forms at an SIT and 4) reveal that Cooper pairs disintegrate rather than becoming more tightly bound deep in the localized phase. We have also developed a method, using a magnetic field, to tune flux disorder reversibly in these films. I will present our latest results on the influence of magnetic flux disorder and random gauge fields on phenomena near bosonic SITs. This work was performed in collaboration with M. D. Stewart, Jr., Hung Q. Nguyen, Shawna M. Hollen, Jimmy Joy, Xue Zhang, Gustavo Fernandez, Jeffrey Shainline and Jimmy Xu. It was supported by NSF Grants DMR 1307290 and DMR-0907357.

  2. Proven in vitro evolution of protease cathepsin E-inhibitors and -activators at pH 4.5 using a paired peptide method.

    PubMed

    Kitamura, Koichiro; Komatsu, Masayuki; Biyani, Madhu; Futakami, Masae; Kawakubo, Tomoyo; Yamamoto, Kenji; Nishigaki, Koichi

    2012-12-01

    Improving a particular function of molecules is often more difficult than identifying such molecules ab initio. Here, a method to acquire higher affinity and/or more functional peptides was developed as a progressive library selection method. The primary library selection products were utilized to build a secondary library composed of blocks of 4 amino acids, of which selection led to peptides with increased activity. These peptides were further converted to randomly generate paired peptides. Cathepsin E-inhibitors thus obtained exhibited the highest activities and affinities (pM order). This was also the case with cathepsin E-activating peptides, proving the methodological effectiveness. The primary, secondary, and tertiary library selections can be regarded as module-finding, module-shuffling, and module-pairing, respectively, which resembles the progression of the natural evolution of proteins. The mode of peptide binding to their target proteins is discussed in analogy to antibodies and epitopes of an antigen.

  3. Varying DNA base-pair size in subangstrom increments: evidence for a loose, not large, active site in low-fidelity Dpo4 polymerase.

    PubMed

    Mizukami, Shin; Kim, Tae Woo; Helquist, Sandra A; Kool, Eric T

    2006-03-07

    We describe the first systematic test of steric effects in the active site of a Y-family DNA polymerase, Dpo4. It has been hypothesized that low-fidelity repair polymerases in this family more readily accept damaged or mismatched base pairs because of a sterically more open active site, which might place lower geometric constraints on the incipient pair. We have tested the origin of low fidelity by use of five nonpolar thymidine analogues that vary in size by a total of 1.0 A over the series. The efficiency and fidelity of base-pair synthesis was measured by steady-state kinetics for single-nucleotide insertions. Analogues were examined both as incoming deoxynucleoside triphosphate (dNTP) derivatives and as template bases. The results showed that Dpo4 preferred to pair the thymidine shape mimics with adenine and, surprisingly, the preferred size was at the center of the range, the same optimum size as recently found for the high-fidelity Klenow fragment (Kf) of Escherichia coli DNA Pol I. However, the size preference with Dpo4 was quite small, varying by a factor of only 30-35 from most to least efficient thymidine analogue. This is in marked contrast to Kf, which showed a rigid size preference, varying by 1100-fold from best to worst. The fidelity for the non-hydrogen-bonding analogues in pairing with A over T, C, or G was much lower in Dpo4 than in the previous high-fidelity enzyme. The data establish that, unlike Kf, Dpo4 has very low steric selectivity and that steric effects alone cannot explain the fidelity (albeit low) that Dpo4 has for a correct base pair; the findings suggest that hydrogen bonds may be important in determining the fidelity of this enzyme. The results suggest that the low steric selectivity of this enzyme is the result of a conformationally flexible or loose active site that adapts with small energetic cost to different base-pair sizes (as measured by the glycosidic C1'-C1' distance), rather than a spatially large active site.

  4. Room-Temperature Activation of Hydrogen by Semi-immobilized Frustrated Lewis Pairs in Microporous Polymer Networks.

    PubMed

    Trunk, Matthias; Teichert, Johannes F; Thomas, Arne

    2017-03-15

    Porous polymer networks based on sterically encumbered triphenylphosphine motifs, mimicking the basic sites employed in frustrated Lewis pair (FLP) chemistry, were synthesized via Yamamoto polymerization and their interactions with the strong Lewis acid B(C6F5)3 probed. The combinations yield semi-immobilized FLPs, which are able to cleave dihydrogen heterolytically at ambient temperature and low hydrogen pressure.

  5. Analysis of the activation and heterolytic dissociation of H2 by frustrated Lewis pairs: NH3/BX3 (X = H, F, and Cl).

    PubMed

    Camaioni, Donald M; Ginovska-Pangovska, Bojana; Schenter, Gregory K; Kathmann, Shawn M; Autrey, Tom

    2012-07-05

    We performed a computational study of H(2) activation and heterolytic dissociation promoted by prototype Lewis acid/base pairs NH(3)/BX(3) (X = H, F, and Cl) to understand the mechanism in frustrated Lewis pairs (FLPs). Although the NH(3)/BX(3) pairs form strong dative bonds, electronic structure theories make it possible to explore the potential energy surface away from the dative complex, in regions relevant to H(2) activation in FLPs. A weakly bound precursor complex, H(3)N·H(2)·BX(3), was found in which the H(2) molecule interacts side-on with B and end-on with N. The BX(3) group is pyramidal in the case of X = H, similar to the geometry of BH(5), but planar in the complexes with X = F and Cl. The latter complexes convert to ion pairs, [NH(4)(+)][BHX(3)(-)] with enthalpy changes of 7.3 and -9.4 kcal/mol, respectively. The minimum energy paths between the FLP and the product ion pair of the chloro and fluoro complexes were calculated and analyzed in great detail. At the transition state (TS), the H(2) bond is weakened and the BX(3) moiety has undergone significant pyramidal distortion. As such, the FLP is prepared to accept the incipient proton and hydride ion on the product-side. The interaction energy of the H(2) with the acid/base pair and the different contributions for the precursor and TS complex from an energy decomposition analysis expose the dominant factors affecting the reactivity. We find that structural reorganization of the precursor complex plays a significant role in the activation and that charge-transfer interactions are the dominant stabilizing force in the activated complex. The electric field clearly has a role in polarizing H(2), but its contribution to the overall interaction energy is small compared to that from the overlap of the p(N), σ(H-H), σ*(H-H), and p(B) orbitals at the TS. Our detailed analysis of the interaction of H(2) with the FLP provides insight into the important components that should be taken into account when

  6. Note: Magnetic targeting for enhancement of the activation efficiency of G protein-coupled receptor with a two-pair coil system.

    PubMed

    Cao, Quanliang; Han, Xiaotao; Chun, Lei; Liu, Jianfeng; Li, Liang

    2016-01-01

    Insufficient contact of drug with target cells is a primary reason for limited efficiency of G protein-coupled receptor activation. To overcome this limitation, a simple approach based on magnetic targeting for enhancing drug delivery towards the cell surfaces using magnetic nanoparticles and a two-pair coil system consisting of Helmholtz and Maxwell coils was reported. As a proof of the concept, comparative experiments on G protein-coupled receptor activation process were carried out and results show that the efficiency of G protein-coupled receptor activation can be increased about 6 times in the experiments with the aid of the proposed magnetic targeting system.

  7. Study of thermally activated radical pair separation in the anthraquinone/triethylamine photoredox system by fourier transform EPR

    SciTech Connect

    Beckert, D.; Plueschau, M.; Dinse, K.P.

    1992-04-16

    By using fourier tranform electron paramagnetic resonance, the free radicals in the photoreduction of anthraquinone by triethylamine in alcohol solutions have been investigated. The detrapping kinetics have been described using some analytical form of the potential and the thermally averaged distance distribution of trapped radical pairs. This analytical form relates the binding potential, the diffusion constant, and the equilibrium distance. 12 refs., 4 figs., 3 tabs.

  8. Evaluation of DEET and eight essential oils for repellency against nymphs of the lone star tick, Amblyomma americanum (Acari: Ixodidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eight commercially available essential oils (oregano, clove, thyme, vetiver, sandalwood, cinnamon, cedarwood, and peppermint) were evaluated for repellency against host-seeking nymphs of the lone star tick, Amblyomma americanum. Concentration- repellency response was established using the vertical ...

  9. A welfare trap? The duration and dynamics of social assistance use among lone mothers in Canada.

    PubMed

    Cooke, Martin

    2009-08-01

    In the late 1990s, the Canadian social assistance policy changed to focus on reducing "dependency" or long-term receipt. Using data from the Survey of Labour and Income Dynamics (1996-2001) and event history models, we investigate the duration of social assistance receipt for lone mothers and other household heads. We find that lone mothers' education and labor force experience were less important predictors for their duration on social assistance than their previous marital history. Although receipt was generally short term, we find evidence of negative duration dependence, or a "welfare trap," after controlling for unobserved heterogeneity. This indicates one way in which a welfare receipt is not only the result of particular life course trajectories but also shapes lives.

  10. Scale-up potential of ion-pair high-performance liquid chromatography method to produce biologically active inositol phosphates.

    PubMed

    Hamada, Jamel S

    2002-01-25

    This study was undertaken to evaluate the possibility that an analytical ion-pair HPLC procedure used to determine phytic acid (IP6) and its degradation products (IP3-IP5) can be transformed to a preparative purification method. A commercial phytic acid (CPA) preparation was separated into its component fractions of IP3, IP4, IPS, and IP6 on two C18 columns (1.8 and 4.2 ml) using 51% methanol containing 0.6-1% tetrabutylammonium hydroxide as ion-pair reagent and 0-0.025 M formic acid (pH 4.3) as eluent at 1.7 and 3.0 cm/min linear velocity, respectively, and 40 degrees C. Elution was monitored at 40 degrees C by a refractive index detector. Reproducible separation of CPA into four well-resolved peaks on these columns was possible after optimizing method variables, particularly the concentration of ion-pair reagent in the injected sample (>1.5%). The same separations were obtained after CPA loads were scaled up 25 times on a steel column (15 cm x 19 mm I.D.), packed with Ethyl C2 sorbent (10 microm) and on a 25 cm x 21.2 mm I.D. C18 column, but at a reduced linear velocity to increase the resolution. Therefore, this optimization of separation not only is useful for analysis of phytic acid and its degradation products but also it provides key parameters for scale up for further fractionation and characterization.

  11. Finding the Wolves in Sheeps Clothing: Ways to Distinguish and Deter Lone-Wolf Terrorists

    DTIC Science & Technology

    2015-03-01

    Hasan), the Boston Marathon bombers, and Anders Behring Breivik ofNotway. By exatnining the nnique circumstances of each case, this thesis detennines...lone-wolf ten·orism, countelten·orism, Nidal Hasan, Boston Marathon bombing, ten·orism, Anders PAGES Breivik 17. SECURITY 18. SECURITY CLASSIFICATION...2009 (Major Nidal Hasan), the Boston Marathon bombers, and Anders Behring Breivik of Norway. By examining the unique circumstances of each case, this

  12. Special Flood Hazard Evaluation Report, Lone Oak Ditch Village of Whitehouse, Lucas County, Ohio

    DTIC Science & Technology

    1992-01-01

    Modify the Impact of Flooding on Individuals and the Community 11 CONCLUSION 11 GLOSSARY 12 REFERENCES 14 TABLES Number Title Page I Summary of...County) I VICINITY MAP Although Flood Insurance Rate Maps have been developed for the community , detailed analyses were not used to study the stream...relationships for each flooding source affecting the community . For this study, Lone Oak Ditch was divided into three hydrologic reaches. Reach 1

  13. Miscellaneous investigations series: Bedrock geologic map of the Lone Mountain pluton area, Esmeralda County, Nevada

    SciTech Connect

    Maldonado, F.

    1984-12-31

    The joint attitudes were measured in the field and plotted on aerial photos at a scale of 1:24,000. The pluton is intensely jointed, primarily as a result of cooling and movement of the magma within a northwest-trending stress field. Foliation, in general, is poorly developed, and quality varies from area to area, but it is best developed close to the contacts with the metasedimentary rocks. A prominent northwest foliation direction was observed that parallels the northwest elongation of the exposed pluton. Faults in the pluton are difficult to identify because of the homogeneity of the rock. Several faults were mapped in the northern part of the area where they have a northeast trend and intersect the northwest-trending lamprophyre dikes with little apparent displacement. A major fault that bounds the northern part of the pluton is downthrown to the north and strikes northeast. This fault offsets the alluvium, the metasedimentary rocks, and the pluton and forms fault scraps as high as 10 m. Aeromagnetic data (US Geological Survey, 1979) suggest the following: (1) the local magnetic highs in the central part of the Lone Mountain pluton are probably related to topographic highs (peaks) where the flight lines are closer to the pluton; (2) a magnetic low in the northeastern part of Lone Mountain coincides with the pluton-country rock contact, which may be very steep; (3) the contours for the southwestern part of the mapped area indicate that the pluton-country rock contact is not as steep as that in the northeastern part and that the pluton probably coalesces at depth with the Weepah pluton, a pluton exposed south of the mapped area; and (4) the contours for the area of the Lone Mountain pluton express a northwest-trending gradient that parallels the northwest elongation of the Lone Mountain pluton and the northwest-trending stress field. 10 refs.

  14. InSAR detection of aquifer recovery: Case studies of Koehn Lake (central California) and Lone Tree Gold Mine (Basin and Range)

    NASA Astrophysics Data System (ADS)

    Wdowinski, S.; Greene, F.; Amelung, F.

    2013-12-01

    Anthropogenic intervention in groundwater flow and aquifer storage often results in vertical movements of Earth's surface, which are well detected by InSAR observations. Most anthropogenic intervention occurs due to groundwater extraction for both agriculture and human consumption and results in land subsidence. However in some cases, ending anthropogenic intervention can lead to aquifer recovery and, consequently, surface uplift. In this study we present two such cases of aquifer recovery. The first case is the aquifer beneath Koehn Lake in Central California, which was overused to meet agricultural demands until the 1990's. The second case is the Lone Tree Gold Mine in Nevada that during active mining in the 1991-2006 groundwater pumping disrupted the aquifer and cause subsidence. But after mining ceased, groundwater flow was recovered and resulted in uplift. In both cases we studied the surface uplift using InSAR time series observations. We conduct an ERS and Envisat InSAR survey over Koehn Lake in California and Lone Tree Gold Mine in Nevada between 1992 and 2010. We followed the SBAS algorithm to generate a time-series of ground displacements and average velocities of pixels, which remain coherent through time in the SAR dataset. A total of 100 and 80 combined ERS and Envisat SAR dates are inverted for Koehn Lake and Lone Tree Gold Mine respectively. Results for the Koehn Lake area indicate a rapid uplift of about 3.5 mm/yr between 1992-2000 and a slower uplift rate of 1.6 mm/yr between 2000-2004, suggesting a decrease in the recovery process. The observed uplift correlates well with groundwater level increase in the Koehn Lake area. Results for the Lone Tree Gold Mine show a constant subsidence (~ 1 cm/yr) due to groundwater extraction between 1992-2006, but uplift of ~1 cm/yr since the beginning of 2007. In both case studies, InSAR observations reveal that the aquifer recovery is accompanied by surface uplift. We plan to use the InSAR observations and the

  15. Health inequalities between lone and couple mothers and policy under different welfare regimes - the example of Italy, Sweden and Britain.

    PubMed

    Burstrom, Bo; Whitehead, Margaret; Clayton, Stephen; Fritzell, Sara; Vannoni, Francesca; Costa, Giuseppe

    2010-03-01

    This study examines the welfare state arrangements and social policy, living conditions and health among lone and couple mothers in three contrasting policy environments: Italy, Sweden and Britain. These countries fall into distinctive family policy categories. Data were drawn from representative national household interview surveys. The findings highlight both similarities and differences. Lone mothers had significantly worse health than couple mothers in all three countries, were more likely to suffer material disadvantage and were much more likely to be smokers. They could be considered a disadvantaged group in particular need in all three countries, irrespective of the policy regime. It is the differences between countries, however, in the experiences of lone and couple mothers that indicate that the prevailing policy regime really does matter. There were telling differences in the prevalence of lone motherhood, their composition, rates of joblessness, poverty and health status of lone mothers in relation to couple mothers in each country. These may be traced back to the main policy regimes of each country, but also partly reflect culture and traditions. The study illustrates an emerging approach to investigating the health inequalities impact of complex social policy contexts. The experiences of lone mothers as a group may serve as a 'litmus' test of how each family policy system is operating and offer an early warning of adverse impacts when policies change.

  16. Learning from “Knocks in Life”: Food Insecurity among Low-Income Lone Senior Women

    PubMed Central

    Green-LaPierre, Rebecca J.; Williams, Patricia L.; Glanville, N. Theresa; Norris, Deborah; Hunter, Heather C.; Watt, Cynthia G.

    2012-01-01

    Building on earlier quantitative work where we showed that lone senior households reliant on public pensions in Nova Scotia (NS), Canada lacked the necessary funds for a basic nutritious diet, here we present findings from a qualitative study involving in-depth interviews with eight low-income lone senior women living in an urban area of NS. Using a phenomenological inquiry approach, in-depth interviews were used to explore lone senior women's experiences accessing food with limited financial resources. Drawing upon Bronfenbrenner's Ecological Systems Theory, we explored their perceived ability to access a nutritionally adequate and personally acceptable diet, and the barriers and enablers to do so; as well in light of our previous quantitative research, we explored their perceptions related to adequacy of income, essential expenses, and their strategies to manage personal finances. Seven key themes emerged: world view, income adequacy, transportation, health/health problems, community program use, availability of family and friends, and personal food management strategies. World view exerted the largest influence on seniors' personal perception of food security status. The implications of the findings and policy recommendations to reduce the nutritional health inequities among this vulnerable subset of the senior population are considered. PMID:22997580

  17. A combined "electrochemical-frustrated lewis pair" approach to hydrogen activation: surface catalytic effects at platinum electrodes.

    PubMed

    Lawrence, Elliot J; Blagg, Robin J; Hughes, David L; Ashley, Andrew E; Wildgoose, Gregory G

    2015-01-07

    Herein, we extend our "combined electrochemical-frustrated Lewis pair" approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical-frustrated Lewis pair (FLP) system involving the B(C6 F5 )3 /[HB(C6 F5 )3 ](-) redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6 F5 )3 to B(C6 Cl5 )3 , the mechanism of electrochemical-FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [PtH] adatoms and transient [HB(C6 F5 )3 ](⋅) electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis.

  18. A Combined "Electrochemical-Frustrated Lewis Pair" Approach to Hydrogen Activation: Surface Catalytic Effects at Platinum Electrodes.

    PubMed

    Lawrence, Elliot J; Blagg, Robin J; Hughes, David L; Ashley, Andrew E; Wildgoose, Gregory G

    2014-11-06

    Herein, we extend our "combined electrochemical-frustrated Lewis pair" approach to include Pt electrode surfaces for the first time. We found that the voltammetric response of an electrochemical-frustrated Lewis pair (FLP) system involving the B(C6 F5 )3 /[HB(C6 F5 )3 ](-) redox couple exhibits a strong surface electrocatalytic effect at Pt electrodes. Using a combination of kinetic competition studies in the presence of a H atom scavenger, 6-bromohexene, and by changing the steric bulk of the Lewis acid borane catalyst from B(C6 F5 )3 to B(C6 Cl5 )3 , the mechanism of electrochemical-FLP reactions on Pt surfaces was shown to be dominated by hydrogen-atom transfer (HAT) between Pt, [PtH] adatoms and transient [HB(C6 F5 )3 ](⋅) electrooxidation intermediates. These findings provide further insight into this new area of combining electrochemical and FLP reactions, and proffers additional avenues for exploration beyond energy generation, such as in electrosynthesis.

  19. Impact of Caregiving for a Child With Cancer on Parental Health Behaviors, Relationship Quality, and Spiritual Faith: Do Lone Parents Fare Worse?

    PubMed Central

    Wiener, Lori; Viola, Adrienne; Kearney, Julia; Mullins, Larry L.; Sherman-Bien, Sandra; Zadeh, Sima; Farkas-Patenaude, Andrea; Pao, Maryland

    2016-01-01

    Caregiving stress has been associated with changes in the psychological and physical health of parents of children with cancer, including both partnered and single parents. While parents who indicate “single” on a demographic checklist are typically designated as single parents, a parent can be legally single and still have considerable support caring for an ill child. Correspondingly, an individual can be married/partnered and feel alone when caring for a child with serious illness. In the current study, we report the results from our exploratory analyses of parent self-reports of behavior changes during their child’s treatment. Parents (N = 263) of children diagnosed with cancer were enrolled at 10 cancer centers. Parents reported significant worsening of all their own health behaviors surveyed, including poorer diet and nutrition, decreased physical activity, and less time spent engaged in enjoyable activities 6 to 18 months following their child’s diagnosis. More partnered parents found support from friends increased or stayed the same since their child’s diagnosis, whereas a higher proportion of lone parents reported relationships with friends getting worse. More lone parents reported that the quality of their relationship with the ill child’s siblings had gotten worse since their child’s diagnosis. Spiritual faith increased for all parents. PMID:26668211

  20. For Parents Particularly--"Only the Lonely": The Latchkey Child.

    ERIC Educational Resources Information Center

    O'Brien, Shirley J.

    1989-01-01

    Discusses ways in which call-in hotlines provide assistance to latchkey children. Describes ways in which parents can provide a feeling of safety for latchkey children and cure feelings of loneliness and boredom through structured activities.(RJC)

  1. Ambiphilic Frustrated Lewis Pair Exhibiting High Robustness and Reversible Water Activation: Towards the Metal-Free Hydrogenation of Carbon Dioxide.

    PubMed

    Rochette, Étienne; Courtemanche, Marc-André; Pulis, Alexander P; Bi, Wenhua; Fontaine, Frédéric-Georges

    2015-06-29

    The synthesis and structural characterization of a phenylene-bridged Frustrated Lewis Pair (FLP) having a 2,2,6,6‑tetramethylpiperidine (TMP) as the Lewis base and a 9-borabicyclo[3.3.1]nonane (BBN) as the Lewis acid is reported. This FLP exhibits unique robustness towards the products of carbon dioxide hydrogenation. The compound shows reversible splitting of water, formic acid and methanol while no reaction is observed in the presence of excess formaldehyde. The molecule is incredibly robust, showing little sign of degradation after heating at 80 °C in benzene with 10 equiv. of formic acid for 24 h. The robustness of the system could be exploited in the design of metal-free catalysts for the hydrogenation of carbon dioxide.

  2. Differences in muscle and adipose tissue gene expression and cardio-metabolic risk factors in the members of physical activity discordant twin pairs.

    PubMed

    Leskinen, Tuija; Rinnankoski-Tuikka, Rita; Rintala, Mirva; Seppänen-Laakso, Tuulikki; Pöllänen, Eija; Alen, Markku; Sipilä, Sarianna; Kaprio, Jaakko; Kovanen, Vuokko; Rahkila, Paavo; Oresic, Matej; Kainulainen, Heikki; Kujala, Urho M

    2010-09-16

    High physical activity/aerobic fitness predicts low morbidity and mortality. Our aim was to identify the most up-regulated gene sets related to long-term physical activity vs. inactivity in skeletal muscle and adipose tissues and to obtain further information about their link with cardio-metabolic risk factors. We studied ten same-sex twin pairs (age range 50-74 years) who had been discordant for leisure-time physical activity for 30 years. The examinations included biopsies from m. vastus lateralis and abdominal subcutaneous adipose tissue. RNA was analyzed with the genome-wide Illumina Human WG-6 v3.0 Expression BeadChip. For pathway analysis we used Gene Set Enrichment Analysis utilizing active vs. inactive co-twin gene expression ratios. Our findings showed that among the physically active members of twin pairs, as compared to their inactive co-twins, gene expression in the muscle tissue samples was chronically up-regulated for the central pathways related to energy metabolism, including oxidative phosphorylation, lipid metabolism and supportive metabolic pathways. Up-regulation of these pathways was associated in particular with aerobic fitness and high HDL cholesterol levels. In fat tissue we found physical activity-associated increases in the expression of polyunsaturated fatty acid metabolism and branched-chain amino acid degradation gene sets both of which associated with decreased 'high-risk' ectopic body fat and plasma glucose levels. Consistent with other findings, plasma lipidomics analysis showed up-regulation of the triacylglycerols containing the polyunsaturated fatty acids. Our findings identified skeletal muscle and fat tissue pathways which are associated with the long-term physical activity and reduced cardio-metabolic disease risk, including increased aerobic fitness. In particular, improved skeletal muscle oxidative energy and lipid metabolism as well as changes in adipocyte function and redistribution of body fat are associated with reduced

  3. The simultaneous determination of active ingredients in cough-cold mixtures by isocratic reversed-phase ion-pair high-performance liquid chromatography.

    PubMed

    Lau, O W; Chan, K; Lau, Y K; Wong, W C

    1989-01-01

    A simple, rapid and accurate method for the simultaneous determination of active ingredients in cough-cold mixtures using isocratic reversed-phase ion-pair high-performance liquid chromatography has been developed. It involves the use of an octadecylsilane column as the stationary phase with methanol, water, tetrahydrofuran, phosphoric acid mixtures as mobile phase including sodium dioctylsulphosuccinate as the ion-pair agent. The pH of the mobile phase was adjusted to 4.6 by means of phosphoric acid and ammonium hydroxide solutions. The proposed method involves the simple dilution of the samples with the mobile phase and the addition of metoclopramide hydrochloride as the internal standard. The active ingredients under investigation were chlorpheniramine, codeine, diphenhydramine, ephedrine, ethylmorphine, phenylephrine, phenylpropanolamine and pholcodine, which exist as various combinations in cough-cold mixtures. The optimum composition of the mobile phase and the optimum flow rate were determined and are reported. The method was applied to the determination of active ingredients in seven commercially available cough-cold mixtures.

  4. Fundamental aspects of recoupled pair bonds. II. Recoupled pair bond dyads in carbon and sulfur difluoride

    SciTech Connect

    Dunning, Thom H. Takeshita, Tyler Y.; Xu, Lu T.

    2015-01-21

    Formation of a bond between a second ligand and a molecule with a recoupled pair bond results in a recoupled pair bond dyad. We examine the recoupled pair bond dyads in the a{sup 3}B{sub 1} states of CF{sub 2} and SF{sub 2}, which are formed by the addition of a fluorine atom to the a{sup 4}Σ{sup −} states of CF and SF, both of which possess recoupled pair bonds. The two dyads are very different. In SF{sub 2}, the second FS–F bond is very strong (D{sub e} = 106.3 kcal/mol), the bond length is much shorter than that in the SF(a{sup 4}Σ{sup −}) state (1.666 Å versus 1.882 Å), and the three atoms are nearly collinear (θ{sub e} = 162.7°) with only a small barrier to linearity (0.4 kcal/mol). In CF{sub 2}, the second FC–F bond is also very strong (D{sub e} = 149.5 kcal/mol), but the bond is only slightly shorter than that in the CF(a{sup 4}Σ{sup −}) state (1.314 Å versus 1.327 Å), and the molecule is strongly bent (θ{sub e} = 119.0°) with an 80.5 kcal/mol barrier to linearity. The a{sup 3}B{sub 1} states of CF{sub 2} and SF{sub 2} illustrate the fundamental differences between recoupled pair bond dyads formed from 2s and 3p lone pairs.

  5. Determination of UV active inorganic anions in potable and high salinity water by ion pair reversed phase liquid chromatography.

    PubMed

    Sadiq Khan, Sadaf; Riaz, M

    2014-05-01

    Reversed phase column was dynamically modified into anion exchange column using various types of tetraalkylammonium salts as ion pair reagents (IPRs) for the separation and quantification of toxic anions such as nitrite, bromate, bromide and nitrate in potable and high salinity water. Various chromatographic parameters such as types and concentration of IPRs, concentration of organic modifier, phosphate buffer and mobile phase pH were optimized for the base-line separation of anions. The lowest detection limits (LDLs) were 0.2 for nitrate and nitrite, 0.6 µg ml(-1)for bromate and bromide respectively for potable water samples. NaCl and Na₂SO₄ were incorporated in the mobile phase for the analysis of high salinity water samples to minimize matrix interferences. This has resulted in change in elution order of anions, better tolerance of matrix anions such as chloride and sulphate. The developed method was successfully utilized for analysis of anions in potable, high salinity and sea water samples.

  6. A pair of transposon-derived proteins function in a histone acetyltransferase complex for active DNA demethylation

    PubMed Central

    Duan, Cheng-Guo; Wang, Xingang; Xie, Shaojun; Pan, Li; Miki, Daisuke; Tang, Kai; Hsu, Chuan-Chih; Lei, Mingguang; Zhong, Yingli; Hou, Yueh-Ju; Wang, Zhijuan; Zhang, Zhengjing; Mangrauthia, Satendra K; Xu, Huawei; Zhang, Heng; Dilkes, Brian; Tao, W Andy; Zhu, Jian-Kang

    2017-01-01

    Transposons are generally kept silent by epigenetic mechanisms including DNA methylation. Here, we identified a pair of Harbinger transposon-derived proteins (HDPs), HDP1 and HDP2, as anti-silencing factors in Arabidopsis. hdp1 and hdp2 mutants displayed an enhanced silencing of transgenes and some transposons. Phylogenetic analyses revealed that HDP1 and HDP2 were co-domesticated from the Harbinger transposon-encoded transposase and DNA-binding protein, respectively. HDP1 interacts with HDP2 in the nucleus, analogous to their transposon counterparts. Moreover, HDP1 and HDP2 are associated with IDM1, IDM2, IDM3 and MBD7 that constitute a histone acetyltransferase complex functioning in DNA demethylation. HDP2 and the methyl-DNA-binding protein MBD7 share a large set of common genomic binding sites, indicating that they jointly determine the target specificity of the histone acetyltransferase complex. Thus, our data revealed that HDP1 and HDP2 constitute a functional module that has been recruited to a histone acetyltransferase complex to prevent DNA hypermethylation and epigenetic silencing. PMID:27934869

  7. a Faint and Lonely Brown Dwarf in the Solar Vicinity

    NASA Astrophysics Data System (ADS)

    1997-04-01

    La Silla, each covering a sky area of 5 o.5 x 5 o.5. When comparing plates of the same sky field obtained at time intervals of several years [1] , she was able to detect, among the hundreds of thousands of stellar images on the plates, a few faint ones whose positions had changed a little in the meantime. The search technique is based on the fact that such a shift is a good indicator of the object being relatively nearby. It must therefore also be intrinsically faint, i.e. a potential White Dwarf candidate. On every pair of plates, approximately twenty faint moving objects were detected with proper motions [2] of more than 0.25 arcsec per year. Indeed, follow-up spectroscopic observations showed that about 20 percent of these or about four per plate were White Dwarfs. Until now, a total of forty new White Dwarfs have been discovered during this very successful project, i.e. over ten times more than originally expected. And then - a Brown Dwarf! Caption to ESO PR Photo 11/97 [JPEG, 144k] ESO Press Photo 11/97 When checking two plates with a time inverval of 11 years, Maria Teresa Ruiz earlier this year discovered a very faint object in the southern constellation of Hydra (The Water-Snake), moving at 0.35 arcsec per year (cf. ESO Press Photo 11/97). In order to establish its true nature, she obtained its spectrum (in the visual to near-infrared region from wavelengths 450-1000 nm) on March 15 using the ESO 3.6-m telescope and the EFOSC1 spectrograph. Caption to ESO PR Photo 12/97 [GIF, 35k] ESO Press Photo 12/97 To her great surprise, the spectrum was of a type never seen before and certainly not that of a White Dwarf or any other easily identifiable type of star (cf. ESO Press Photo 12/97). In particular, there were no signs of spectral bands of titanium oxide (TiO) or vanadium oxide (VO) which are common in very cool stars, nor of the spectral lines seen in White Dwarfs. On the other hand, an absorption line of the short-lived element lithium was identified, as well

  8. A 15-base-pair element activates the SPS4 gene midway through sporulation in Saccharomyces cerevisiae.

    PubMed Central

    Hepworth, S R; Ebisuzaki, L K; Segall, J

    1995-01-01

    Sporulation of the yeast Saccharomyces cerevisiae represents a simple developmental process in which the events of meiosis and spore wall formation are accompanied by the sequential activation of temporally distinct classes of genes. In this study, we have examined expression of the SPS4 gene, which belongs to a group of genes that is activated midway through sporulation. We mapped the upstream boundary of the regulatory region of SPS4 by monitoring the effect of sequential deletions of 5'-flanking sequence on expression of plasmid-borne versions of SPS4 introduced into a MATa/MAT alpha delta sps4/delta sps4 strain. This analysis indicated that the 5' boundary of the regulatory region was within 50 bp of the putative TATA box of the gene. By testing various oligonucleotides that spanned this boundary and the downstream sequence for their ability to activate expression of a heterologous promoter, we found that a 15-bp sequence sufficed to act as a sporulation-specific upstream activation sequence. This 15-bp fragment, designated UASSPS4, activated expression of a CYC1-lacZ reporter gene midway through sporulation and was equally active in both orientations. Extending the UAS fragment to include the adjacent 14-bp enhanced its activity 10-fold. We show that expression of SPS4 is regulated in a manner distinct from that of early meiotic genes: mutation of UME6 did not lead to vegetative expression of SPS4, and sporulation-specific expression was delayed by mutation of IME2. In vivo and in vitro assays suggested that a factor present in vegetative cells bind to the UASSPS4 element. We speculate that during sporulation this factor is modified to serve as an activator of the SPS4 gene or, alternatively, that it recruits an activator to the promoter. PMID:7791799

  9. Genetic variation at the delta-sarcoglycan (SGCD) locus elevates heritable sympathetic nerve activity in human twin pairs.

    PubMed

    Hightower, C Makena; Zhang, Kuixing; Miramontes-González, José P; Rao, Fangwen; Wei, Zhiyun; Schork, Andrew J; Nievergelt, Caroline M; Biswas, Nilima; Mahata, Manjula; Elkelis, Nina; Taupenot, Laurent; Stridsberg, Mats; Ziegler, Michael G; O'Connor, Daniel T

    2013-12-01

    The Syrian Cardiomyopathic Hamster (BIO-14.6/53.58 strains) model of cardiac failure, resulting from naturally occurring deletion at the SGCD (delta-sarcoglycan) locus, displays widespread disturbances in catecholamine metabolism. Rare Mendelian myopathy disorders of human SGCD occur, although common naturally occurring SGCD genetic variation has not been evaluated for effects on human norepinephrine (NE) secretion. This study investigated the effect of SGCD genetic variation on control of NE secretion in healthy twin pairs. Genetic associations profiled SNPs across the SGCD locus. Trait heritability (h(2)) and genetic covariance (pleiotropy; shared h(2)) were evaluated. Sympathochromaffin exocytosis in vivo was probed in plasma by both catecholamines and Chromogranin B (CHGB). Plasma NE is substantially heritable (p = 3.19E-16, at 65.2 ± 5.0% of trait variance), sharing significant (p < 0.05) genetic determination with circulating and urinary catecholamines, CHGB, eGFR, and several cardio-metabolic traits. Participants with higher pNE showed significant (p < 0.05) differences in several traits, including increased BP and hypertension risk factors. Peak SGCD variant rs1835919 predicted elevated systemic vascular compliance, without changes in specifically myocardial traits. We used a chimeric-regulated secretory pathway photoprotein (CHGA-EAP) to evaluate the effect of SGCD on the exocytotic pathway in transfected PC12 cells; in transfected cells, expression of SGCD augmented CHGA trafficking into the exocytotic regulated secretory pathway. Thus, our investigation determined human NE secretion to be a highly heritable trait, influenced by common genetic variation within the SGCD locus. Circulating NE aggregates with BP and hypertension risk factors. In addition, coordinate NE and CHGB elevation by rs1835919 implicates exocytosis as the mechanism of release.

  10. Keeping it in the family: the self-rated health of lone mothers in different European welfare regimes.

    PubMed

    Van de Velde, Sarah; Bambra, Clare; Van der Bracht, Koen; Eikemo, Terje Andreas; Bracke, Piet

    2014-11-01

    This study examines whether health inequalities exist between lone and cohabiting mothers across Europe, and how these may differ by welfare regime. Data from the European Social Survey were used to compare self-rated general health, limiting long-standing illness and depressive feelings by means of a multi-level logistic regression. The 27 countries included in the analyses are classified into six welfare regimes (Anglo-Saxon, Bismarckian, Southern, Nordic, Central East Europe (CEE) (new EU) and CEE (non-EU). Lone motherhood is defined as mothers not cohabiting with a partner, regardless of their legal marital status. The results indicate that lone mothers are more at risk of poor health than cohabiting mothers. This is most pronounced in the Anglo-Saxon regime for self-rated general health and limiting long-standing illness, while for depressive feelings it is most pronounced in the Bismarckian welfare regime. While the risk difference is smallest in the CEE regimes, both lone and cohabiting mothers also reported the highest levels of poor health compared with the other regimes. The results also show that a vulnerable socioeconomic position is associated with ill-health in lone mothers and that welfare regimes differ in the degree to which they moderate this association.

  11. Do low-income lone mothers compromise their nutrition to feed their children?

    PubMed Central

    McIntyre, Lynn; Glanville, N. Theresa; Raine, Kim D.; Dayle, Jutta B.; Anderson, Bonnie; Battaglia, Noreen

    2003-01-01

    Background Women who live in disadvantaged circumstances in Canada exhibit dietary intakes below recommended levels, but their children often do not. One reason for this difference may be that mothers modify their own food intake to spare their children nutritional deprivation. The objective of our study was to document whether or not low-income lone mothers compromise their own diets to feed their children. Methods We studied 141 low-income lone mothers with at least 2 children under the age of 14 years who lived in Atlantic Canada. Women were identified through community organizations using a variety of recruitment strategies. The women were asked weekly for 1 month to recall their food intake over the previous 24 hours; they also reported their children's (n = 333) food intake. Mothers also completed a questionnaire about “food insecurity,” that is, a lack of access to adequate, nutritious food through socially acceptable means, during each interview. Results Household food insecurity was reported by 78% of mothers during the study month. Mothers' dietary intakes and the adequacy of intake were consistently poorer than their children's intake overall and over the course of a month. The difference in adequacy of intake between mothers and children widened from Time 1, when the family had the most money to purchase food, to Time 4, when the family had the least money. The children experienced some improvement in nutritional intake at Time 3, which was possibly related to food purchases for them associated with receipt of the Child Tax Benefit Credit or the Goods and Services Tax Credit. Interpretation Our study demonstrates that low-income lone mothers compromise their own nutritional intake in order to preserve the adequacy of their children's diets. PMID:12642423

  12. Risk of Lyme disease: perceptions of residents of a Lone Star tick-infested community.

    PubMed Central

    Armstrong, P. M.; Brunet, L. R.; Spielman, A.; Telford, S. R.

    2001-01-01

    BACKGROUND: Lone Star ticks (Amblyomma americanum) have been suggested as a vector of the agent of Lyme disease (Borrelia burgdorferi sensu lato) in the USA, based on associations with an infection manifesting mainly as erythema migrans. In laboratory experiments, however, they failed to transmit B. burgdorferi sensu stricto. METHODS: In this study, carried out from 1994 to 1996, we determined the seroprevalences of B. burgdorferi (1.2%), Ehrlichia chaffeensis (7%), E. phagocytophila (0%), Rickettsia rickettsii (0%), R. typhi (0%), Coxiella burneti (0%), Francisella tularensis (0%), and Babesia microti (0%) by standard serological methods for 325 residents (97% of the total population) of Gibson Island, coastal Maryland, USA, where 15% of the residents reported having had Lyme disease within a recent 5-year span. FINDINGS: Of the 167 seronegative individuals who were followed up prospectively for 235 person-years of observation, only 2 (0.85%) seroconverted for B. burgdorferi. Of 1556 ticks submitted from residents, 95% were identified as Lone Star ticks; only 3% were deer ticks (Ixodes dammini), the main American vector of Lyme disease. B. burgdorferi s.s. infected 20% of host-seeking immature deer ticks, and borreliae ("B. lonestari") were detected in 1-2% of Lone Star ticks. Erythema migrans was noted in 65% of self-reports of Lyme disease, but many such reports indicated that the rash was present while the tick was still attached, suggesting a reaction to the bite itself rather than true Lyme disease. Sera from individuals reporting Lyme disease generally failed to react to B. burgdorferi or any other pathogen antigens. CONCLUSION: The residents of Gibson Island had an exaggerated perception of the risk of Lyme disease because they were intensely infested with an aggressively human-biting and irritating nonvector tick. In addition, a Lyme disease mimic of undescribed etiology (named Masters' disease) seems to be associated with Lone Star ticks, and may confound

  13. Marked counteranion effects on single-site olefin polymerization processes. Correlations of ion pair structure and dynamics with polymerization activity, chain transfer, and syndioselectivity.

    PubMed

    Chen, Ming-Chou; Roberts, John A S; Marks, Tobin J

    2004-04-14

    Counteranion effects on the rate and stereochemistry of syndiotactic propylene enchainment by the archetypal C(s)-symmetric precatalyst [Me(2)C(Cp)(Flu)]ZrMe(2) (1; Cp = C(5)H(4); Flu = C(13)H(8), fluorenyl) are probed using the cocatalysts MAO (2), B(C(6)F(5))(3) (3)(,) B(2-C(6)F(5)C(6)F(4))(3) (4)(,) Ph(3)C(+)B(C(6)F(5))(4)(-) (5), and Ph(3)C(+)FAl(2-C(6)F(5)C(6)F(4))(3)(-) (6), offering greatly different structural and ion pairing characteristics. Reaction of 1 with 3 affords [Me(2)C(Cp)(Flu)]ZrMe(+) MeB(C(6)F(5))(3)(-) (7). In the case of 4, this reaction leads to formation the micro-methyl dinuclear diastereomers [([Me(2)C(Cp)(Flu)]ZrMe)(2)(micro-Me)](+) MeB(2-C(6)F(5)C(6)F(4))(3)(-) (8). A similar reaction with 6 results in diastereomeric [Me(2)C(Cp)(Flu)]ZrMe(+) FAl(2-C(6)F(5)C(6)F(4))(3)(-) (10) ion pairs. The molecular structures of 7 and 10 have been determined by single-crystal X-ray diffraction. Reorganization pathways available to these species have been examined using EXSY and dynamic NMR, revealing that the cation-MeB(C(6)F(5))(3)(-) interaction is considerably weaker/more mobile than in the FAl(2-C(6)F(5)C(6)F(4))(3)(-)-derived analogue. Polymerizations mediated by 1 in toluene over the temperature range of -10 degrees to +60 degrees C and at 1.0-5.0 atm propylene pressure (at 60 degrees C) reveal that activity, product syndiotacticity, m and mm stereodefect generation, and chain transfer processes are highly sensitive to the nature of the ion pairing. Thus, the complexes activated with 4 and 5, having the weakest ion pairing, yield the highest estimated propagation rates, while with 6, having the strongest pairing, yields the lowest. The strongly coordinating, immobile FAl(2-C(6)F(5)C(6)F(4))(3)(-) anion produces the highest/least temperature-dependent product syndiotacticity, lowest/least temperature-dependent m stereodefect abundance, and highest product molecular weight. These polypropylene microstructural parameters, and also M(w), are least

  14. Medial and lateral perforant path evoked potentials are selectively modulated by pairing with glutamatergic activation of locus coeruleus in the dentate gyrus of the anesthetized rat.

    PubMed

    Edison, Hilary T; Harley, Carolyn W

    2012-03-01

    Norepinephrine (NE) in vitro produces long-lasting potentiation of medial perforant path input and depression of lateral perforant path input to dentate gyrus in the rat. Similar, but highly transient, effects have been reported in vivo using paragigantocellular stimulation to release NE. The present study uses alternate stimulation of the medial perforant path and lateral olfactory tract (eliciting a lateral perforant path-evoked potential) to examine the effects of glutamatergic activation of locus coeruleus (LC) on the two pathways for up to 3 h post-LC activation. In the first experiment, the expected potentiation of the medial perforant path population spike in dentate gyrus was observed, but without accompanying depression of the lateral perforant path-mediated evoked potential (lateral olfactory tract stimulation, 60 s ISI). In a second experiment, with more frequent pairing of input with NE release (10 s ISI), significant potentiation of lateral perforant path-mediated input to dentate gyrus occurred, but potentiation of medial perforant path input was not seen. A third experiment with a 30 s ISI again produced potentiation of lateral perforant path-mediated input without potentiation of the medial perforant path population spike. The size of effects with the 30 s ISI was intermediate between that seen with 10 s and 60 s ISI. Potentiation of lateral perforant path over medial perforant path input has previously been reported with acute nicotinic activation of the LC. This outcome also resembles heterosynaptic modulation previously reported with tetanic potentiation. The data argue for a competitive relationship between medial and lateral perforant path inputs to dentate gyrus and suggest pairing with increased NE produces a bias favoring one or the other pathway depending on parameters such as strength and frequency. NE potentiating effects on lateral perforant path input here may also have occurred in entorhinal cortex (EC) given the system-wide NE release

  15. DETERMINATION OF THE POINT-SPREAD FUNCTION FOR THE FERMI LARGE AREA TELESCOPE FROM ON-ORBIT DATA AND LIMITS ON PAIR HALOS OF ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Ackermann, M.; Ajello, M.; Allafort, A.; Bechtol, K.; Bloom, E. D.; Borgland, A. W.; Bottacini, E.; Buehler, R.; Asano, K.; Atwood, W. B.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Bastieri, D.; Bonamente, E.; Brandt, T. J.; Brigida, M.; Bruel, P. E-mail: mar0@uw.edu [Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS and others

    2013-03-01

    The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from Almost-Equal-To 20 MeV to >300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of {gamma} rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broader than the pre-launch PSF. We checked for dependence of the PSF on the class of {gamma}-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. We found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low- and high-redshift BL Lac AGNs and the TeV blazars 1ES0229+200 and 1ES0347-121.

  16. Lonely Barchans

    NASA Technical Reports Server (NTRS)

    2006-01-01

    3 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows two barchan dunes in the north polar region of Mars. The orientation of the dunes, with the steep faces pointed toward the southeast (lower right), indicates that the winds responsible for their formation blew from the northwest (upper left). At the time this image was acquired by MOC, the dunes and surrounding plains were covered by seasonal carbon dioxide frost.

    Location near: 73.8oN, 40.8oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  17. Lone Star

    ERIC Educational Resources Information Center

    Eisele-Dyrli, Kurt

    2010-01-01

    In education, Texas has been a source of both controversy and innovation. According to Don McAdams, founder and president of the Houston-based school-board training and consulting firm Center for the Reform of School Systems, every state is different and unique in its education system, but Texas is one state that is really different and unique.…

  18. Impact of genetic discoveries on the classification of lone atrial fibrillation.

    PubMed

    Roberts, Jason D; Gollob, Michael H

    2010-02-23

    Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, represents a major burden to patients and health care systems through its sequelae of heart failure and stroke. Its age-dependent increase in prevalence has led to worrisome predictions of an expanding burden secondary to our aging population. This growing epidemic is further exacerbated by a current lack of highly effective therapies for the arrhythmia stemming from our incomplete understanding of its complex pathophysiology. Recent genetic studies, triggered in part by evidence of a hereditary component of AF, have begun to identify predisposing genes and offer further insights into the mechanisms of lone AF. A variety of ion channels and most recently a circulating hormone have been implicated. The apparent genetic diversity underlying the arrhythmia has served to emphasize the heterogeneity of factors that govern its initiation and maintenance. The different causative genes seem to predispose to AF through distinct putative mechanisms, including enhanced and delayed atrial action potential repolarization, cellular hyperexcitability, and conduction velocity heterogeneity. Classification of lone AF into mechanistic subgroups serves to emphasize its heterogeneity and has the potential to guide developmental and clinical treatment strategies. The frequent recalcitrant nature of the arrhythmia to contemporary pharmacological and invasive therapies may be overcome through an ability to identify, through genetics, the mechanistic subclass of AF for an individual patient. Proper identification of the culprit pathophysiology may permit administration of a targeted form of therapy that carries maximal efficacy and minimal risk in a manner consistent with the vision of pharmacogenomics.

  19. Barriers to Social Participation among Lonely Older Adults: The Influence of Social Fears and Identity

    PubMed Central

    Goll, Johanna C.; Charlesworth, Georgina; Scior, Katrina; Stott, Joshua

    2015-01-01

    Introduction Loneliness among older adults is a major public health problem that may be associated with processes of social participation and identity. This study therefore sought to examine the relationship between social participation and identity in a sample of lonely older adults living independently in London, England. Method An inductive qualitative approach, based on semi-structured interviews and thematic analysis, was employed. Results Participants commonly spoke of barriers to social participation that have been reported elsewhere, including illness/disability, loss of contact with friends/relatives, lack of a supportive community, and lack of acceptable social opportunities. However, novel findings were also derived. In particular, participants commonly minimised the difficulties they faced alone, and described attempts to avoid social opportunities. These behaviours were linked to fears about engaging in social participation opportunities, including fears of social rejection and/or exploitation, and fears of losing valued aspects of identity. Discussion It is concluded that social participation amongst lonely older people will not improve through the removal of previously reported barriers alone; instead, older peoples’ beliefs, fears and identities must be addressed. Suggestions for implementing these findings within community organisations are provided. PMID:25706933

  20. Lone star tick abundance, fire, and bison grazing in tall-grass prairie

    USGS Publications Warehouse

    Cully, J.F.

    1999-01-01

    Lone star ticks (Amblyomma americanum L.) were collected by drag samples of 1 km transects on 12 watersheds at Konza Prairie Research Natural Area near Manhattan, Kans., during summer 1995-1996. Watersheds were treated to 2 experimental treatments: 3 burn intervals (1-year, 4-year, and 20-year) and 2 grazing treatments (grazed by bison (Bos bison L.) or ungrazed). The objectives were to determine whether fire interval, time since most recent burn, and the presence of large ungulate grazers would cause changes in lone star tick abundance in tallgrass prairie in central Kansas. Watersheds burned at 1-year intervals had fewer larvae and adults than watersheds burned at 4-year or 20-year intervals. Watersheds burned during the year of sampling had fewer ticks than watersheds burned one or more years in the past. For watersheds burned 1 or more years in the past there was no effect from time since burn. The presence of bison did not affect tick abundance. Spring burning is an effective method to reduce tick populations in tallgrass prairie during the year of the burn.

  1. Post-incarceration Recidivism of Lone versus Group Juvenile Homicide Offenders.

    PubMed

    Khachatryan, Norair; Heide, Kathleen M; Rad, Jordyn; Hummel, Erich V

    2016-11-01

    Killings by juvenile homicide offenders (JHOs) who use accomplices have been increasing since the 1980s and currently represent approximately half of juvenile arrests for murder in the United States. Nevertheless, prior research has not compared JHOs who kill alone with JHOs who kill in groups. The present research followed up 30 years later on a sample of 59 male murderers and attempted murderers sentenced to adult prison. This study was designed to analyze whether lone and group JHOs differed on pre-incarceration, incarceration, and post-incarceration variables. Significant findings indicated that compared with lone offenders, group JHOs had a higher mean of pre-homicide arrests and were more likely to be Black, have a pre-homicide delinquent record, commit a crime-related homicide offense, and target a stranger. With respect to post-homicide variables, group JHOs were more likely to be released from prison and more likely to be rearrested. The two types of JHOs did not differ significantly in relation to the number of post-release violent offenses. Preliminary implications of the findings and avenues for future investigation are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

  2. SDetection of vector-borne agents in lone star ticks, Amblyomma americanum (Acari: Ixodidae), from Mississippi.

    PubMed

    Castellaw, A H; Showers, J; Goddard, J; Chenney, E F; Varela-Stokes, A S

    2010-05-01

    In this study, we evaluated Amblyomma americanum (lone star tick) in Mississippi for the presence of Ehrlichia chaffeensis, causative agent of human monocytic ehrlichiosis; Ehrlichia ewingii, causative agent of human and canine granulocytic ehrlichiosis; Borrelia lonestari, putative agent of southern tick-associated rash illness; Francisella tularensis, the agent of tularemia; and Rickettsia spp., particularly R. amblyommii, a suspected pathogen. We collected adult A. americanum from four regions of Mississippi: Northeast, Northwest, Southeast, and East. Of the ticks collected, 192 were dissected and DNA was extracted for nested polymerase chain reaction (PCR) assays to detect the above bacteria. In all, 3% of tick extracts had evidence of Borrelia sp., 4% for E. chaffeensis, 6% for E. ewingii, and 44% for a Rickettsia species. As determined by sequencing, most Rickettsia spp. were R. amblyommii. In addition, extracts from 42 pools (total of 950) of larval A. americanum collected in Southwest Mississippi were tested for the presence of E. chaffeensis and Rickettsia species. Of these extracts from pools, nine of 37 (24%) were PCR positive for a Rickettsia sp., most often, R. amblyommii; none had evidence of E. chaffeensis, supporting the ability of lone star ticks to transovarially transmit R. amblyommii, but not E. chaffeensis. This study demonstrates E. chaffeensis, E. ewingii, "B. lonestari", and R. amblyommii in A. americanum by PCR for the first time in Mississippi. Understanding the prevalence and epidemiology of these agents in Mississippi should increase awareness of tick-borne disease in the medical community.

  3. Activity of guard cell anion channel SLAC1 is controlled by drought-stress signaling kinase-phosphatase pair

    PubMed Central

    Geiger, Dietmar; Scherzer, Sönke; Mumm, Patrick; Stange, Annette; Marten, Irene; Bauer, Hubert; Ache, Peter; Matschi, Susanne; Liese, Anja; Al-Rasheid, Khaled A. S.; Romeis, Tina; Hedrich, Rainer

    2009-01-01

    In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1 appeared to be the key ion channel in this signaling pathway but remained electrically silent when expressed heterologously. Using split YFP assays, we identified OST1 as an interaction partner of SLAC1 and ABI1. Upon coexpression of SLAC1 with OST1 in Xenopus oocytes, SLAC1-related anion currents appeared similar to those observed in guard cells. Integration of ABI1 into the SLAC1/OST1 complex, however, prevented SLAC1 activation. Our studies demonstrate that SLAC1 represents the slow, deactivating, weak voltage-dependent anion channel of guard cells controlled by phosphorylation/dephosphorylation. PMID:19955405

  4. Note on Ehrlichia chaffeensis, Ehrlichia ewingii, and "Borrelia lonestari" infection in lone star ticks (Acari: Ixodidae), Nebraska, USA.

    PubMed

    Maegli, Amanda; Loy, J Dustin; Cortinas, Roberto

    2016-02-01

    The lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae), is established in southeastern Nebraska yet the prevalence of tick-associated microorganisms is not known. An initial PCR-based analysis for Ehrlichia chaffeensis, Ehrlichia ewingii, and Borrelia infection in host-seeking adult ticks collected in southeast Nebraska was conducted. A total of 251 adult ticks collected in six sites in southeast Nebraska were tested. E. chaffeensis, E. ewingii, and Borrelia spp. were present, and the prevalence of each was approximately 1.6%. This study demonstrates that Ehrlichia spp. are present in Nebraska lone star tick populations.

  5. Composition of The Essential Oil From Danggui-zhiqiao Herb-Pair and Its Analgesic Activity and Effect on Hemorheology in Rats With Blood Stasis Syndrome

    PubMed Central

    Wang, Yuanqing; Yan, Jianye; Li, Shunxiang; Wang, Wei; Cai, Xiong; Huang, Dan; Gong, Limin; Li, Xin

    2016-01-01

    Background: Angelica sinensis and Aurantii fructu used in a pair, named Danggui-Zhiqiao herb-pair (DZHP), which was rich in essential oil and has been adopted to promote blood circulation, dispel blood stasis, and relieve pain in traditional Chinese medicine (TCM) Objective: To analyze the composition and pharmacological effects of essential oil from DZHP Materials and Methods: The composition of the essential oil from DZHP was analyzed by gas chromatography/mass spectrometry (GC/MS). Its analgesic activity was evaluated by acetic acid-induced writhing test and hot plate test. The hemorheology test was carried out to evaluate the effect on hemorheology in rats with blood stasis syndrome Results: Twenty-eight components were identified and the main components were α-pinene (3.07%), β-pinene (2.0%), β-myrcene (3.71%), D-limonene (49.28%), γ-terpinen (9.53%), α-terpinolene (1.80%), α-terpineol (2.02%), β-bisabolene (1.13%), butylidenephthalide (1.43%), and Z-ligustilide (16.08%). The pharmacology test showed that the essential oil significantly inhibited the number of writhes induced by acetic acid with inhibition rate of 44.64% and significantly increased hot-plate latency compared with control group from 30 to 90 min after oral administration of drugs in mice. It could significantly decrease plasma viscosity, whole blood relative index at high and low shear rate, whole blood reduced viscosity at high and low shear rate, and erythrocyte rigidity index in hemorheology test Conclusion: The composition of the essential oil of DZHP was determined successfully and it had analgesic and promoting blood circulation activities. SUMMARY Angelica sinensis and Aurantii fructu used in a pair, named Danggui-Zhiqiao herb-pair (DZHP), which was rich in Essential oil and has been adopted to promote blood circulation, dispel blood stasis and relieve pain in traditional Chinese medicine (TCM).Twenty-eight components were identified and the main components were α-pinene (3

  6. Base pairing and base mis-pairing in nucleic acids

    NASA Technical Reports Server (NTRS)

    Wang, A. H. J.; Rich, A.

    1986-01-01

    In recent years we have learned that DNA is conformationally active. It can exist in a number of different stable conformations including both right-handed and left-handed forms. Using single crystal X-ray diffraction analysis we are able to discover not only additional conformations of the nucleic acids but also different types of hydrogen bonded base-base interactions. Although Watson-Crick base pairings are the predominant type of interaction in double helical DNA, they are not the only types. Recently, we have been able to examine mismatching of guanine-thymine base pairs in left-handed Z-DNA at atomic resolution (1A). A minimum amount of distortion of the sugar phosphate backbone is found in the G x T pairing in which the bases are held together by two hydrogen bonds in the wobble pairing interaction. Because of the high resolution of the analysis we can visualize water molecules which fill in to accommodate the other hydrogen bonding positions in the bases which are not used in the base-base interactions. Studies on other DNA oligomers have revealed that other types of non-Watson-Crick hydrogen bonding interactions can occur. In the structure of a DNA octamer with the sequence d(GCGTACGC) complexed to an antibiotic triostin A, it was found that the two central AT base pairs are held together by Hoogsteen rather than Watson-Crick base pairs. Similarly, the G x C base pairs at the ends are also Hoogsteen rather than Watson-Crick pairing. Hoogsteen base pairs make a modified helix which is distinct from the Watson-Crick double helix.

  7. Delaying feedback by three seconds benefits retention of face-name pairs: the role of active anticipatory processing.

    PubMed

    Carpenter, Shana K; Vul, Edward

    2011-10-01

    In three experiments, we used face-name learning to examine the puzzling feedback delay benefit--the tendency for feedback to be more effective when it is delayed rather than presented immediately. In Experiment 1, we found that feedback presented after a 3-s blank screen was more effective than feedback presented immediately, even after controlling for the exposure time to the material. In Experiment 2, we replicated the benefit of a feedback delay even when participants were given extra time to view the feedback or to try to retrieve the answer, indicating that this benefit is specific to a delay before feedback. Finally, in Experiment 3, we showed that the 3-s delay is beneficial only if it involves a blank screen, not if the delay is filled with an unrelated distracter task. These results suggest that the feedback delay benefit in this paradigm could arise from an active anticipatory process that occurs during the delay.

  8. Direct synthesis of a geminal zwitterionic phosphonium/hydridoborate system--developing an alternative tool for generating frustrated Lewis pair hydrogen activation systems.

    PubMed

    Yu, Jiangang; Kehr, Gerald; Daniliuc, Constantin G; Bannwarth, Christoph; Grimme, Stefan; Erker, Gerhard

    2015-05-28

    A convenient way to a new class of geminal Mes2PH(+)/B(C6F5)2H(-) pairs is presented. It utilizes triflic acid addition to trans-Mes2PCH=CHB(C6F5)2 followed by triflate/hydride exchange. Thermally induced ring-closure gave a phosphonium/boratacyclopropane zwitterion 8 which formed the Mes2PH(CHMe)B(C6F5)2H P/B FLP-H2 product 10 by subsequent treatment with triflic acid and a silane, or alternatively with dihydrogen at 90 °C. The product 10 is an active catalyst for the hydrogenation of a variety of unsaturated organic substrates, including a quinoline derivative. Treatment of compound 8 with HB(C6F5)2 gave a bifunctional borane 14 which selectively reduced carbon monoxide to the formyl stage.

  9. The role of adolescent nutrition and physical activity in the prediction of verbal intelligence during early adulthood: a genetically informed analysis of twin pairs.

    PubMed

    Jackson, Dylan B; Beaver, Kevin M

    2015-01-05

    A large body of research has revealed that nutrition and physical activity influence brain functioning at various stages of the life course. Nevertheless, very few studies have explored whether diet and exercise influence verbal intelligence as youth transition from adolescence into young adulthood. Even fewer studies have explored the link between these health behaviors and verbal intelligence while accounting for genetic and environmental factors that are shared between siblings. Employing data from the National Longitudinal Study of Adolescent Health, the current study uses a sample of same-sex twin pairs to test whether youth who engage in poorer fitness and nutritional practices are significantly more likely to exhibit reduced verbal intelligence during young adulthood. The results suggests that, independent of the effects of genetic and shared environmental factors, a number of nutritional and exercise factors during adolescence influence verbal intelligence during adulthood. Limitations are noted and suggestions for future research are outlined.

  10. The Role of Adolescent Nutrition and Physical Activity in the Prediction of Verbal Intelligence during Early Adulthood: A Genetically Informed Analysis of Twin Pairs

    PubMed Central

    Jackson, Dylan B.; Beaver, Kevin M.

    2015-01-01

    A large body of research has revealed that nutrition and physical activity influence brain functioning at various stages of the life course. Nevertheless, very few studies have explored whether diet and exercise influence verbal intelligence as youth transition from adolescence into young adulthood. Even fewer studies have explored the link between these health behaviors and verbal intelligence while accounting for genetic and environmental factors that are shared between siblings. Employing data from the National Longitudinal Study of Adolescent Health, the current study uses a sample of same-sex twin pairs to test whether youth who engage in poorer fitness and nutritional practices are significantly more likely to exhibit reduced verbal intelligence during young adulthood. The results suggests that, independent of the effects of genetic and shared environmental factors, a number of nutritional and exercise factors during adolescence influence verbal intelligence during adulthood. Limitations are noted and suggestions for future research are outlined. PMID:25568969

  11. Disrupting a key hydrophobic pair in the oligomerization interface of the actinoporins impairs their pore-forming activity.

    PubMed

    Mesa-Galloso, Haydeé; Delgado-Magnero, Karelia H; Cabezas, Sheila; López-Castilla, Aracelys; Hernández-González, Jorge E; Pedrera, Lohans; Alvarez, Carlos; Peter Tieleman, D; García-Sáez, Ana J; Lanio, Maria E; Ros, Uris; Valiente, Pedro A

    2017-03-01

    Crystallographic data of the dimeric and octameric forms of fragaceatoxin C (FraC) suggested the key role of a small hydrophobic protein-protein interaction surface for actinoporins oligomerization and pore formation in membranes. However, site-directed mutagenesis studies supporting this hypothesis for others actinoporins are still lacking. Here, we demonstrate that disrupting the key hydrophobic interaction between V60 and F163 (FraC numbering scheme) in the oligomerization interface of FraC, equinatoxin II (EqtII), and sticholysin II (StII) impairs the pore formation activity of these proteins. Our results allow for the extension of the importance of FraC protein-protein interactions in the stabilization of the oligomeric intermediates of StII and EqtII pointing out that all of these proteins follow a similar pathway of membrane disruption. These findings support the hybrid pore proposal as the universal model of actinoporins pore formation. Moreover, we reinforce the relevance of dimer formation, which appears to be a functional intermediate in the assembly pathway of some different pore-forming proteins.

  12. Action potential fidelity during normal and epileptiform activity in paired soma-axon recordings from rat hippocampus.

    PubMed

    Meeks, Julian P; Jiang, Xiaoping; Mennerick, Steven

    2005-07-15

    Although action potential initiation and propagation are fundamental to nervous system function, there are few direct electrophysiological observations of propagating action potentials in small unmyelinated fibres, such as the axons within mammalian hippocampus. To circumvent limitations of previous studies that relied on extracellular stimulation, we performed dual recordings: whole-cell recordings from hippocampal CA3 pyramidal cell somas and extracellular recordings from their axons, up to 800 micro m away. During brief spike trains under normal conditions, axonal spikes were more resistant to amplitude reduction than somatic spikes. Axonal amplitude depression was greatest at the axon initial segment < 150 microm from the soma, and initiation occurred approximately 75 microm from the soma. Although prior studies, which failed to verify spike initiation, suggested substantial axonal depression during seizure-associated extracellular K+([K+]o) rises, we found that 8 mm [K+]o caused relatively small decreases in axonal spike amplitude during brief spike trains. However, during sustained, epileptiform spiking induced in 8 mm [K+]o, axonal waveforms decreased significantly in peak amplitude. During epileptiform spiking, bursts of two or more action potentials > 20 Hz failed to propagate in most cases. In normal [K+]o at 25 and 32 degrees C, spiking superimposed on sustained somatic depolarization, but not spiking alone, produced similar axonal changes as the epileptiform activity. These results highlight the likely importance of steady-state inactivation of axonal channels in maintaining action potential fidelity. Such changes in axonal propagation properties could encode information and/or serve as an endogenous brake on seizure propagation.

  13. A Dibasic Amino Acid Pair Conserved in the Activation Loop Directs Plasma Membrane Localization and Is Necessary for Activity of Plant Type I/II Phosphatidylinositol Phosphate Kinase1[W

    PubMed Central

    Mikami, Koji; Saavedra, Laura; Hiwatashi, Yuji; Uji, Toshiki; Hasebe, Mitsuyasu; Sommarin, Marianne

    2010-01-01

    Phosphatidylinositol phosphate kinase (PIPK) is an enzyme involved in the regulation of cellular levels of phosphoinositides involved in various physiological processes, such as cytoskeletal organization, ion channel activation, and vesicle trafficking. In animals, research has focused on the modes of activation and function of PIPKs, providing an understanding of the importance of plasma membrane localization. However, it still remains unclear how this issue is regulated in plant PIPKs. Here, we demonstrate that the carboxyl-terminal catalytic domain, which contains the activation loop, is sufficient for plasma membrane localization of PpPIPK1, a type I/II B PIPK from the moss Physcomitrella patens. The importance of the carboxyl-terminal catalytic domain for plasma membrane localization was confirmed with Arabidopsis (Arabidopsis thaliana) AtPIP5K1. Our findings, in which substitution of a conserved dibasic amino acid pair in the activation loop of PpPIPK1 completely prevented plasma membrane targeting and abolished enzymatic activity, demonstrate its critical role in these processes. Placing our results in the context of studies of eukaryotic PIPKs led us to conclude that the function of the dibasic amino acid pair in the activation loop in type I/II PIPKs is plant specific. PMID:20427464

  14. [Simultaneous determination of five active components of compound α-ketoacid tablet in human urine by ion-pair reversed-phase high performance liquid chromatography].

    PubMed

    Huang, Xiaoya; Zhong, Yuan; Huang, Zhongping; Jin, Chen; Wang, Lili; Pan, Zaifa

    2015-02-01

    A simple and sensitive method for the simultaneous determination of five active components, D, L-α-hydroxymethionine calcium (HMACa), α-ketovaline calcium (KVCa), D, L-α-ketoisoleucine calcium (KILCa), α-ketoleucine calcium (KLCa) and α-ketophenylalanine calcium (KPACa) of compound α-ketoacid tablet in human urine by ion-pair reversed-phase high performance liquid chromatography (RP-HPLC) was developed and validated. The separation conditions, such as the concentration of ion-pair reagent, the pH value of the mobile phase and the concentration of the buffer were optimized. All the five analytes were separated well on a C18 column (250 mm x 4.6 mm, 5 µm) with diode array detection at 210 nm and the column temperature of 35 °C. The mobile phases were acetonitrile and 20 mmol/L phosphate buffer (containing 15 mmol/L tetrabutylammonium hydroxide; pH 7) at the flow rate of 1. 0 mL/min with gradient elution. The calibration curves for the five components were linear in the range from 20 to 200 mg/L (r≥ 0. 9990). The limits of detection (LODs, S/N= 3) were 3.0, 5. 0, 3. 6, 5.7 and 2. 5 mg/L, and the limits of quantification (LOQs, S/N= 10) were 9. 6, 16.7, 12.0, 19.0 and 8.3 mg/L for HMACa, KVCa, KILCa, KLCa and KPACa, respectively. The intra-day and inter-day precisions were less than 7%, and the average recoveries were between 86.79% and 112. 00% in the human urine with RSDs lower than 9% (n= 5). The method proved precise, specific and reproducible, and can be used for the determination of the five components in urine.

  15. In vitro membrane feeding of the lone star tick (Amblyomma americanum) and its use in evaluation of acaricidal compounds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The lone star tick, Amblyomma americanum, is one of important Ixodid tick species that are known ectoparasites and disease vectors affecting animal and human health in the United States. New pesticides or repellents with novel mode of action would help control resistant ticks and protect humans from...

  16. Starting School and Leaving Welfare: The Impact of Public Education on Lone Parents' Welfare Receipt. CEE DP 121

    ERIC Educational Resources Information Center

    Brewer, Mike; Crawford, Claire

    2010-01-01

    The report makes use of rich administrative data (the Work and Pensions Longitudinal Study) which records children's exact date of birth and home postcode (used to identify the admissions policy in each lone parent's local authority). It improves on previous studies by estimating the precise timing (relative to the date on which part-time nursery…

  17. Reconciliation of work and care among lone mothers of adults with intellectual disabilities: the role and limits of care capital.

    PubMed

    Chou, Yueh-Ching; Kröger, Teppo

    2014-07-01

    In this study, the concept of social capital is applied to an exploration of Guanxi (social networking to create good relationships) among working lone mothers of adults with intellectual disabilities (ID) in Taiwan. Using in-depth interviews, this study explores the role of social capital, here referred to as 'care capital', in making it possible for working lone mothers to combine their roles as family carers and workers. Eleven divorced or widowed mothers combining their paid work with long-term care responsibilities were recruited from a survey or through NGOs and were interviewed at their home between October 2008 and July 2010. An interpretative phenomenological approach was adopted for data analysis. The findings revealed that the mothers' care capital was extremely limited and was lost, gained and lost again during their life-cycles of long-term care-giving. Guanxi, especially in relation to their employers, proved to be the sole source of care capital for these mothers, making reconciliation between work and care responsibilities possible. In the absence of formal or informal support, religion and the mother-child relationship seemed also to become a kind of care capital for these lone mothers, helping them to get by with their life-long care responsibilities. For formal social and healthcare services, not just in Taiwan but in every country, it is important to develop support for lone mothers of adults with ID who have long-term care responsibilities and low levels of care capital and thus face care poverty.

  18. Solvent, drying time, and the responses of lone star ticks (acari: ixodidae) to the repellents deet and picaridin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Behavioral bioassays remain a standard tool in the discovery, development, and registration of repellents. Tick repellent bioassays tend to be rather uncomplicated, but several factors can influence their outcomes. Using lone star tick, Amblyomma americanum (L.), nymphs in climbing bioassays, we tes...

  19. Parental marital disruption and intergenerational transfers: an analysis of lone elderly parents and their children.

    PubMed

    Pezzin, L E; Schone, B S

    1999-08-01

    Although one of the most marked demographic trends observed over the twentieth century is the increased rate of divorce, relatively little research has explored the effects of these changing marital patterns in the context of an aging society. Using a sample of lone elderly parents and their adult children, we analyze the direct and indirect effects of marital disruption on four important dimensions of intergenerational transfers: coresidence, financial assistance, adult children's provision of informal care, and parental purchase of paid care. Our findings suggest that divorce has deleterious effects on intergenerational transfers, particularly for elderly fathers. Remarriage further reduces exchange. Our results reveal that parents engage in lower levels of transfers with stepchildren relative to biological children. Moreover, intergenerational transfers are sensitive to characteristics of biological children but not to those of stepchildren. Taken together, these results suggest that exchange at the end of the life course continues to be adversely affected by marital disruption.

  20. Validation of the DeLone and McLean Information Systems Success Model

    PubMed Central

    2017-01-01

    Objectives This study is an adaptation of the widely used DeLone and McLean information system success model in the context of hospital information systems in a developing country. Methods A survey research design was adopted in the study. A structured questionnaire was used to collect data from 442 health information management personnel in five Nigerian teaching hospitals. A structural equation modeling technique was used to validate the model's constructs. Results It was revealed that system quality significantly influenced use (β = 0.53, p < 0.001) and user satisfaction (β = 0.17, p < 0.001). Information quality significantly influenced use (β = 0.24, p < 0.001) and user satisfaction (β = 0.17, p < 0.001). Also, service quality significantly influenced use (β = 0.22, p < 0.001) and user satisfaction (β = 0.51, p < 0.001). However, use did not significantly influence user satisfaction (β = 0.00, p > 0.05), but it significantly influenced perceived net benefits (β = 0.21, p < 0.001). Furthermore, user satisfaction did not significantly influence perceived net benefits (β = 0.00, p > 0.05). Conclusions The study validates the DeLone and McLean information system success model in the context of a hospital information system in a developing country. Importantly, system quality and use were found to be important measures of hospital information system success. It is, therefore, imperative that hospital information systems are designed in such ways that are easy to use, flexible, and functional to serve their purpose. PMID:28261532

  1. Identification of protective antigens by RNA interference for control of the lone star tick, Amblyomma americanum.

    PubMed

    de la Fuente, José; Manzano-Roman, Raúl; Naranjo, Victoria; Kocan, Katherine M; Zivkovic, Zorica; Blouin, Edmour F; Canales, Mario; Almazán, Consuelo; Galindo, Ruth C; Step, Douglas L; Villar, Margarita

    2010-02-17

    The lone star tick, Amblyomma americanum, vectors pathogens of emerging diseases of humans and animals in the United States. Currently, measures are not available for effective control of A. americanum infestations. Development of vaccines directed against tick proteins may reduce tick infestations and the transmission of tick-borne pathogens. However, the limiting step in tick vaccine development has been the identification of tick protective antigens. Herein, we report the application of RNA interference (RNAi) for screening an A. americanum cDNA library for discovery of tick protective antigens that reduce tick survival and weights after feeding. Four cDNA clones, encoding for putative threonyl-tRNA synthetase (2C9), 60S ribosomal proteins L13a (2D10) and L13e (2B7), and interphase cytoplasm foci protein 45 (2G7), were selected for vaccine studies in cattle, along with subolesin, a tick protective protein identified previously. In vaccinated cattle, an overall efficacy (E)>30% was obtained when considering the vaccine effect on both nymphs and adults, but only 2D10, 2G7 and subolesin affected both tick stages. The highest efficacy of control for adult ticks (E>55%) was obtained in cattle vaccinated with recombinant 2G7 or subolesin. These collective results demonstrated the feasibility of developing vaccines for the control of lone star tick infestations. The use of RNAi for identification of tick protective antigens proved to be a rapid and cost-effective tool for discovery of candidate vaccine antigens, and this approach could likely be applied to other parasites of veterinary and medical importance.

  2. Ion pair receptors†

    PubMed Central

    Kim, Sung Kuk

    2010-01-01

    Compared with simple ion receptors, which are able to bind either a cation or an anion, ion pair receptors bearing both a cation and an anion recognition site offer the promise of binding ion pairs or pairs of ions strongly as the result of direct or indirect cooperative interactions between co-bound ions. This critical review focuses on the recent progress in the design of ion pair receptors and summarizes the various binding modes that have been used to accommodate ion pairs (110 references). PMID:20737073

  3. Accommodation of an N-(deoxyguanosin-8-yl)-2-acetylaminofluorene adduct in the active site of human DNA polymerase ι: Hoogsteen or Watson-Crick base pairing?†

    PubMed Central

    Donny-Clark, Kerry; Shapiro, Robert; Broyde, Suse

    2009-01-01

    Bypass across DNA lesions by specialized polymerases is essential for maintenance of genomic stability. Human DNA polymerase ι (polι) is a bypass polymerase of the Y family. Crystal structures of polι suggest that Hoogsteen base pairing is employed to bypass minor groove DNA lesions, placing them on the spacious major groove side of the enzyme. Primer extension studies have shown that polι is also capable of error-free nucleotide incorporation opposite the bulky major groove adduct N-(deoxyguanosin-8-yl)-2-acetyl-aminofluorene (dG-AAF). We present molecular dynamics simulations and free energy calculations suggesting that Watson-Crick base pairing could be employed in polι for bypass of dG-AAF. In polι with Hoogsteen paired dG-AAF the bulky AAF moiety would reside on the cramped minor groove side of the template. The Hoogsteen-capable conformation distorts the active site, disrupting interactions necessary for error-free incorporation of dC opposite the lesion. Watson-Crick pairing places the AAF rings on the spacious major groove side, similar to the position of minor groove adducts observed with Hoogsteen pairing. Watson-Crick paired structures show a well-ordered active site, with a near reaction-ready ternary complex. Thus our results suggest that polι would utilize the same spacious region for lesion bypass of both major and minor groove adducts. Therefore, purine adducts with bulk on the minor groove side would use Hoogsteen pairing, while adducts with the bulky lesion on the major groove side would utilize Watson-Crick base pairing as indicated by our MD simulations for dG-AAF. This suggests the possibility of an expanded role for polι in lesion bypass. PMID:19072536

  4. Pick a Pair. Being Bony

    ERIC Educational Resources Information Center

    Miller, Pat

    2004-01-01

    This column suggests pairings of fiction and nonfiction books to meet curricular needs and help students to compare/contrast the texts as they may be asked on state tests. The author of this paper focuses on activities surrounding Halloween. Since many schools are discouraged from teaching about Halloween, this can be a great time to investigate…

  5. A Highly Reactive Geminal P/B Frustrated Lewis Pair: Expanding the Scope to C−X (X=Cl, Br) Bond Activation

    PubMed Central

    Samigullin, Kamil; Georg, Isabelle; Bolte, Michael; Lerner, Hans‐Wolfram

    2016-01-01

    Abstract The geminal frustrated Lewis pair tBu2PCH2B(Fxyl)2 (1; Fxyl=3,5‐(CF3)2C6H3) is accessible in 65 % yield from tBu2PCH2Li and (Fxyl)2BF. According to NMR spectroscopy and X‐ray crystallography, 1 is monomeric both in solution and in the solid state. The intramolecular P⋅⋅⋅B distance of 2.900(5) Å and the full planarity of the borane site exclude any significant P/B interaction. Compound 1 readily activates a broad variety of substrates including H2, EtMe2SiH, CO2/CS2, Ph2CO, and H3CCN. Terminal alkynes react with heterolysis of the C−H bond. Haloboranes give cyclic adducts with strong P−BX3 and weak R3B−X bonds. Unprecedented transformations leading to zwitterionic XP/BCX3 adducts occur on treatment of 1 with CCl4 or CBr4 in Et2O. In less polar solvents (C6H6, n‐pentane), XP/BCX3 adduct formation is accompanied by the generation of significant amounts of XP/BX adducts. FLP 1 catalyzes the hydrogenation of PhCH=NtBu and the hydrosilylation of Ph2CO with EtMe2SiH. PMID:26833900

  6. Evaluation of effects of pharmaceutical processing on structural disorders of active pharmaceutical ingredient crystals using nanoindentation and high-resolution total scattering pair distribution function analysis.

    PubMed

    Chen, Shuang; Sheikh, Ahmad Y; Ho, Raimundo

    2014-12-01

    Pharmaceutical unit operations such as milling and compaction can often generate disordered regions in crystals of active pharmaceutical ingredients (APIs). This may lead to changes in a number of important pharmaceutical properties including dissolution, stability, hygroscopicity, and so on. It is therefore important for pharmaceutical industry to evaluate the effects of pharmaceutical processing on API structural orders, and to investigate and develop analytical tools that are capable of accurately detecting and assessing subtle process-induced structural disorders in pharmaceutical crystals. In this study, nanoindentation was first used to determine the intrinsic mechanical properties including hardness and Young's modulus of two API crystals, compounds 1 and 2. These crystals of different mechanical properties were then milled and compacted under various conditions. The resulting structural disorders in these crystals were subsequently evaluated using synchrotron-based high-resolution total scattering pair distribution function (TS-PDF) analysis. Furthermore, principal component analysis was applied to the PDF data to assess the relative extents of disorders in the API crystals, which showed a good correlation with the process conditions. The study demonstrates that high-resolution TS-PDF analysis coupled with nanoindentation measurement is a valuable and effective tool for detecting and assessing process-induced subtle structural disorders in API crystals.

  7. A non-intrusive fluid-wave actuator and sensor pair for the active control of fluid-borne vibrations in a pipe

    NASA Astrophysics Data System (ADS)

    Brennan, M. J.; Elliott, S. J.; Pinnington, R. J.

    1996-06-01

    This paper describes the design of a non-intrusive fluid-wave actuator and sensor pair for use in an active control system to control fluid-borne vibrations in pipework systems. Piping systems can be excited by sources such as pumps and compressors and vibrational energy can propagate both in the pipe wall and the fluid. The transducers developed in this paper are designed only for the control of the fluid-borne vibrational energy. A theoretical framework is developed that integrates the transducers into the pipe and couples them to the motion of the fluid inside the pipe. A hydraulic actuator driven with a magnetostrictive element and fitted to a water-filled perspex pipe has been designed and tested. The sensor was made from piezoelectric elements fitted around the outer circumference of the pipe. Experimental results show that the actuator is capable of suppressing a propagating fluid-wave, but in doing so it increases the vibration of the pipe-wall in the vicinity of the actuator. When the sensor is employed as an error sensor together with the actuator in the frequency range 10 - 1000 Hz, a reduction in the fluid-wave amplitude of around 20 dB is possible.

  8. A pair of chiral flavonolignans as novel anti-cyanobacterial allelochemicals derived from barley straw (Hordeum vulgare): characterization and comparison of their anti-cyanobacterial activities.

    PubMed

    Xiao, Xi; Huang, Haomin; Ge, Zhiwei; Rounge, Trine B; Shi, Jiyan; Xu, Xinhua; Li, Ruobing; Chen, Yingxu

    2014-05-01

    The inhibitory effect of barley straw (Hordeum vulgare) on cyanobacteria has been observed in many field and laboratory studies for over 30 years, although the compounds responsible for this anti-cyanobacterial effect have remained unknown. In this study, a pair of chiral flavonolignans were isolated from barley straw extract using a bioassay-guided isolation procedure against Microcystis sp. The structures of the allelopathic compounds were elucidated by NMR (nuclear magnetic resonance) and HPLC-MS (high performance liquid chromatography-mass spectrometry), and turned out to be salcolin A and B. The enantiomers differ in their anti-cyanobacterial abilities. Both enantiomers exhibited inhibitory effects on Microcystis sp., and the EC50 (concentration for 50% of maximal effect) of salcolin A and B were 6.02 × 10(-5) and 9.60 × 10(-5 ) mol l(-1) , respectively. Furthermore, the modes of actions of the enantiomers were investigated and compared at a single cell level by flow cytometry. Salcolin A was found to induce an increase on cyanobacterial intracellular ROS (reactive oxygen species) levels and to inhibit esterase activity, whereas salcolin B caused leakages of cyanobacterial cytoplasms. Thus, salcolin A was more 'algistatic', and salcolin B was more 'algicidal'. This study suggests that salcolin is the key allelochemical in barley straw's inhibitory effect on cyanobacteria and could be used as an agent in the future control of cyanobacterial harmful algae blooms.

  9. Exploring electron pair behaviour in chemical bonds using the extracule density.

    PubMed

    Proud, Adam J; Mackenzie, Dalton E C K; Pearson, Jason K

    2015-08-21

    We explore explicit electron pair behaviour within the chemical bond (and lone pairs) by calculating the probability distribution for the center-of-mass (extracule) of an electron pair described by single localized orbitals. Using Edmiston-Ruedenberg localized orbitals in a series of 61 chemical systems, we demonstrate the utility of the extracule density as an interpretive tool in chemistry. By accessing localized regions of chemical space we simplify the interpretation of the extracule density and afford a quantum mechanical interpretation of "chemically intuitive" features of electronic structure. Specifically, we describe the localized effects on chemical bonds due to changes in electronegativities of bonded neighbours, bond strain, and non-covalent interactions. We show that the extracule density offers unique insight into electronic structure and allows one to readily quantify the effects of changing the chemical environment.

  10. Catalytic CO2 activation assisted by rhenium hydride/B(C6F5)3 frustrated Lewis pairs--metal hydrides functioning as FLP bases.

    PubMed

    Jiang, Yanfeng; Blacque, Olivier; Fox, Thomas; Berke, Heinz

    2013-05-22

    Reaction of 1 with B(C6F5)3 under 1 bar of CO2 led to the instantaneous formation of the frustrated Lewis pair (FLP)-type species [ReHBr(NO)(PR3)2(η(2)-O═C═O-B(C6F5)3)] (2, R = iPr a, Cy b) possessing two cis-phosphines and O(CO2)-coordinated B(C6F5)3 groups as verified by NMR spectroscopy and supported by DFT calculations. The attachment of B(C6F5)3 in 2a,b establishes cooperative CO2 activation via the Re-H/B(C6F5)3 Lewis pair, with the Re-H bond playing the role of a Lewis base. The Re(I) η(1)-formato dimer [{Re(μ-Br)(NO)(η(1)-OCH═O-B(C6F5)3)(PiPr3)2}2] (3a) was generated from 2a and represents the first example of a stable rhenium complex bearing two cis-aligned, sterically bulky PiPr3 ligands. Reaction of 3a with H2 cleaved the μ-Br bridges, producing the stable and fully characterized formato dihydrogen complex [ReBrH2(NO)(η(1)-OCH═O-B(C6F5)3)(PiPr3)2] (4a) bearing trans-phosphines. Stoichiometric CO2 reduction of 4a with Et3SiH led to heterolytic splitting of H2 along with formation of bis(triethylsilyl)acetal ((Et3SiO)2CH2, 7). Catalytic reduction of CO2 with Et3SiH was also accomplished with the catalysts 1a,b/B(C6F5)3, 3a, and 4a, showing turnover frequencies (TOFs) between 4 and 9 h(-1). The stoichiometric reaction of 4a with the sterically hindered base 2,2,6,6-tetramethylpiperidine (TMP) furnished H2 ligand deprotonation. Hydrogenations of CO2 using 1a,b/B(C6F5)3, 3a, and 4a as catalysts gave in the presence of TMP TOFs of up to 7.5 h(-1), producing [TMPH][formate] (11). The influence of various bases (R2NH, R = iPr, Cy, SiMe3, 2,4,6-tri-tert-butylpyridine, NEt3, PtBu3) was studied in greater detail, pointing to two crucial factors of the CO2 hydrogenations: the steric bulk and the basicity of the base.

  11. Superconductivity: The persistence of pairs

    SciTech Connect

    Edelman, Alex; Littlewood, Peter

    2015-05-20

    Superconductivity stems from a weak attraction between electrons that causes them to form bound pairs and behave much like bosons. These so-called Cooper pairs are phase coherent, which leads to the astonishing properties of zero electrical resistance and magnetic flux expulsion typical of superconducting materials. This coherent state may be qualitatively understood within the Bose–Einstein condensate (BEC) model, which predicts that a gas of interacting bosons will become unstable below a critical temperature and condense into a phase of matter with a macroscopic, coherent population in the lowest energy state, as happens in 4He or cold atomic gases. The successful theory proposed by Bardeen, Cooper and Schrieffer (BCS) predicts that at the superconducting transition temperature Tc, electrons simultaneously form pairs and condense, with no sign of pairing above Tc. Theorists have long surmised that the BCS and BEC models are opposite limits of a single theory and that strong interactions or low density can, in principle, drive the system to a paired state at a temperature Tpair higher than Tc, making the transition to the superconducting state BEC-like (Fig. 1). Yet most superconductors to date are reasonably well described by BCS theory or its extensions, and there has been scant evidence in electronic materials for the existence of pairing independent of the full superconducting state (though an active debate rages over the cuprate superconductors). Writing in Nature, Jeremy Levy and colleagues have now used ingenious nanostructured devices to provide evidence for electron pairing1. Perhaps surprisingly, the material they have studied is a venerable, yet enigmatic, low-temperature superconductor, SrTiO3.

  12. Matched-pair classification

    SciTech Connect

    Theiler, James P

    2009-01-01

    Following an analogous distinction in statistical hypothesis testing, we investigate variants of machine learning where the training set comes in matched pairs. We demonstrate that even conventional classifiers can exhibit improved performance when the input data has a matched-pair structure. Online algorithms, in particular, converge quicker when the data is presented in pairs. In some scenarios (such as the weak signal detection problem), matched pairs can be generated from independent samples, with the effect not only doubling the nominal size of the training set, but of providing the structure that leads to better learning. A family of 'dipole' algorithms is introduced that explicitly takes advantage of matched-pair structure in the input data and leads to further performance gains. Finally, we illustrate the application of matched-pair learning to chemical plume detection in hyperspectral imagery.

  13. Vortex pairs on surfaces

    SciTech Connect

    Koiller, Jair

    2009-05-06

    A pair of infinitesimally close opposite vortices moving on a curved surface moves along a geodesic, according to a conjecture by Kimura. We outline a proof. Numerical simulations are presented for a pair of opposite vortices at a close but nonzero distance on a surface of revolution, the catenoid. We conjecture that the vortex pair system on a triaxial ellipsoid is a KAM perturbation of Jacobi's geodesic problem. We outline some preliminary calculations required for this study. Finding the surfaces for which the vortex pair system is integrable is in order.

  14. Lone Atrial Fibrillation Is Associated With Impaired Left Ventricular Energetics That Persists Despite Successful Catheter Ablation

    PubMed Central

    Wijesurendra, Rohan S.; Liu, Alexander; Eichhorn, Christian; Ariga, Rina; Levelt, Eylem; Clarke, William T.; Rodgers, Christopher T.; Karamitsos, Theodoros D.; Bashir, Yaver; Ginks, Matthew; Rajappan, Kim; Betts, Tim; Ferreira, Vanessa M.; Neubauer, Stefan

    2016-01-01

    Background: Lone atrial fibrillation (AF) may reflect a subclinical cardiomyopathy that persists after sinus rhythm (SR) restoration, providing a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics in patients with AF but no significant comorbidities. Methods: Fifty-three patients with symptomatic paroxysmal or persistent AF and without significant valvular disease, uncontrolled hypertension, coronary artery disease, uncontrolled thyroid disease, systemic inflammatory disease, diabetes mellitus, or obstructive sleep apnea (ie, lone AF) undergoing ablation and 25 matched control subjects in SR were investigated. Magnetic resonance imaging quantified LV ejection fraction (LVEF), peak systolic circumferential strain (PSCS), and left atrial volumes and function, whereas phosphorus-31 magnetic resonance spectroscopy evaluated ventricular energetics (ratio of phosphocreatine to ATP). AF burden was determined before and after ablation by 7-day Holter monitoring; intermittent ECG event monitoring was also undertaken after ablation to investigate for asymptomatic AF recurrence. Results: Before ablation, both LV function and energetics were significantly impaired in patients compared with control subjects (LVEF, 61% [interquartile range (IQR), 52%–65%] versus 71% [IQR, 69%–73%], P<0.001; PSCS, –15% [IQR, –11 to –18%] versus −18% [IQR, –17% to –19%], P=0.002; ratio of phosphocreatine to ATP, 1.81±0.35 versus 2.05±0.29, P=0.004). As expected, patients also had dilated and impaired left atria compared with control subjects (all P<0.001). Early after ablation (1–4 days), LVEF and PSCS improved in patients recovering SR from AF (LVEF, 7.0±10%, P=0.005; PSCS, –3.5±4.3%, P=0.001) but were unchanged in those in SR during both assessments (both P=NS). At 6 to 9 months after ablation, AF burden reduced significantly (from 54% [IQR, 1.5%–100%] to

  15. Brief Report: Problem Solving and Maternal Distress at the Time of a Child's Diagnosis of Cancer in Two-Parent Versus Lone-Parent Households

    PubMed Central

    Iobst, Emily A.; Alderfer, Melissa A.; Sahler, Olle Jane Z.; Askins, Martha A.; Fairclough, Diane L.; Katz, Ernest R.; Butler, Robert W.; Dolgin, Michael J.

    2009-01-01

    Objective To examine negative affectivity and problem-solving abilities for lone mothers and those who are married/partnered subsequent to a child's diagnosis with cancer. Methods Negative affectivity and problem-solving strategies were assessed for 464 mothers (87 lone and 377 married/partnered) within 2–16 weeks of their child's diagnosis with cancer. Results The two groups of mothers did not differ significantly on measures of perceived posttraumatic stress or problem-solving; lone mothers reported significantly more symptoms of depression. This difference was no longer significant when maternal education was taken into account. Conclusions Negative affectivity and problem-solving abilities were similar for lone mothers and those that are married/partnered shortly after their child has been diagnosed with cancer. Findings are discussed within the context of contemporary strategies to assess marital status as proxy variable for various underlying constructs. PMID:19129268

  16. Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Bindhu, M. R.; Sathe, V.; Umadevi, M.

    2013-11-01

    Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

  17. Detection of Ehrlichia chaffeensis in adult and nymphal stage lone star ticks (Amblyomma americanum) from Long Island, New York

    USGS Publications Warehouse

    Mixson, T.R.; Ginsberg, H.S.; Campbell, S.R.; Sumner, J.W.; Paddock, C.D.

    2004-01-01

    The lone star tick, Amblyomma americanum (L.), has increased in abundance in several regions of the northeastern United States, including areas of Long Island, NY. Adult and nymphal stage A. americanum collected from several sites on Long Island were evaluated for infection with Ehrlichia chaffeensis, the causative agent of human monocytic ehrlichiosis (HME), by using a nested polymerase chain reaction assay. Fifty-nine (12.5%) of ,17.3 adults and eight of 11.3 pools of five nymphs each (estimated minimum prevalence of infection 1.4%) contained DNA of E. chaffeensis. These data, coupled with the documented expansion of lone star tick populations in the northeastern United States, confirm that E. chaffeensis is endemic to many areas of Long Island and that HME should be considered among the differential diagnoses of the many distinct tick-borne diseases that occur in this region.

  18. Cooper pairs and bipolarons

    NASA Astrophysics Data System (ADS)

    Lakhno, Victor

    2016-11-01

    It is shown that Cooper pairs are a solution of the bipolaron problem for model Fröhlich Hamiltonian. The total energy of a pair for the initial Fröhlich Hamiltonian is found. Differences between the solutions for the model and initial two-particle problems are discussed.

  19. The Nation That Cried Lone Wolf: A Data-Driven Analysis of Individual Terrorists in the United States Since 9/11

    DTIC Science & Technology

    2012-03-01

    2003 (testimony of Robert S. Mueller, III, Director, FBI). Walt Disney . (Producer), & Gillett, B. (Director). (1933). Three little pigs [Motion...lone-wolf terrorism as an effective method against the western world (al-Suri, 2010). U.S. officials have acknowledged the increased threat and...terrorism in the United States. Domestic lone-wolf terrorists are typically unknown to law enforcement prior to conducting attacks and the nature of

  20. Cooper Pairs in Insulators?!

    ScienceCinema

    James Valles

    2016-07-12

    Nearly 50 years elapsed between the discovery of superconductivity and the emergence of the microscopic theory describing this zero resistance state. The explanation required a novel phase of matter in which conduction electrons joined in weakly bound pairs and condensed with other pairs into a single quantum state. Surprisingly, this Cooper pair formation has also been invoked to account for recently uncovered high-resistance or insulating phases of matter. To address this possibility, we have used nanotechnology to create an insulating system that we can probe directly for Cooper pairs. I will present the evidence that Cooper pairs exist and dominate the electrical transport in these insulators and I will discuss how these findings provide new insight into superconductor to insulator quantum phase transitions. 

  1. Maternal education, lone parenthood, material hardship, maternal smoking, and longstanding respiratory problems in childhood: testing a hierarchical conceptual framework

    PubMed Central

    Spencer, N.

    2005-01-01

    Background: Maternal smoking and low socioeconomic status are known to be associated with each other and with longstanding respiratory problems in childhood but their interrelation has received little attention. In this paper, the interrelations is studied using a conceptual hierarchical framework among children aged 0–11 years in a representative sample of British households with children. Method: With data from the family and children study, this paper tested a conceptual hierarchical framework, in which maternal education acting through lone parenthood would influence material hardship and all three would have effects on maternal smoking increasing the risk of children's longstanding respiratory problems. Results: Among children 0–2, maternal education and material hardship had indirect effects on respiratory problems mediated through more proximal variables. After adjustment for maternal education, the effect of lone parenthood was partially mediated through material hardship and maternal smoking. Adjustment for socioeconomic status variables attentuated but did not eliminate the effect of maternal smoking (odds ratio = 2.04, 95% confidence interval = 1.30, 3.20). Among children 3–11, the effect of maternal education was partially mediated through proximal variables. Lone parenthood and material hardship had indirect effects only. Adjustment for confounding eliminated the effect of maternal smoking (odds ratio = 1.06, 95% confidence interval = 0.88, 1.26). Conclusions: Reducing childhood longstanding respiratory problems will require attention to background socioeconomic status factors in addition to maternal smoking. PMID:16166356

  2. Report on Pairing-based Cryptography

    PubMed Central

    Moody, Dustin; Peralta, Rene; Perlner, Ray; Regenscheid, Andrew; Roginsky, Allen; Chen, Lily

    2015-01-01

    This report summarizes study results on pairing-based cryptography. The main purpose of the study is to form NIST’s position on standardizing and recommending pairing-based cryptography schemes currently published in research literature and standardized in other standard bodies. The report reviews the mathematical background of pairings. This includes topics such as pairing-friendly elliptic curves and how to compute various pairings. It includes a brief introduction to existing identity-based encryption (IBE) schemes and other cryptographic schemes using pairing technology. The report provides a complete study of the current status of standard activities on pairing-based cryptographic schemes. It explores different application scenarios for pairing-based cryptography schemes. As an important aspect of adopting pairing-based schemes, the report also considers the challenges inherent in validation testing of cryptographic algorithms and modules. Based on the study, the report suggests an approach for including pairing-based cryptography schemes in the NIST cryptographic toolkit. The report also outlines several questions that will require further study if this approach is followed. PMID:26958435

  3. Sexually dimorphic mate preference in Japan : An analysis of lonely hearts advertisements.

    PubMed

    Oda, R

    2001-09-01

    Lonely hearts advertisements (LHA) published in Japan were examined in a comparative study on sexually dimorphic mate preference. I analyzed 944 LHA written by Japanese (730 by males and 214 by females) seeking short-term relationships and 780 LHA (577 by males and 203 by females) seeking long-term relationships. Some universal patterns of mate preference were confirmed and others were not. Female advertisers in both categories sought more traits than they offered; they also sought more traits than male advertisers. Males tended to offer their financial and social status, and females tended to seek those traits. More females requested family commitment than males. While there was no sex difference in offering and seeking physical appearance and health, females tended to request photographs of their potential mates. Males were more likely than females to be willing to accept children from previous relationships, although there was no significant difference in refusing such children. More females seeking long-term mates requested family commitment than females seeking short-term mates. In both males and females, more advertisers seeking long-term mates offered family commitment than advertisers seeking short-term mates. Some predictions for contingent preference were also examined. One prediction confirmed was that females offering physical appearance and health sought more traits than those not doing so. However, males offering financial and social status did not make higher demands than those who did not, which does not support one prediction.

  4. Eruptions at Lone Star geyser, Yellowstone National Park, USA: 2. Constraints on subsurface dynamics

    NASA Astrophysics Data System (ADS)

    Vandemeulebrouck, Jean; Sohn, Robert A.; Rudolph, Maxwell L.; Hurwitz, Shaul; Manga, Michael; Johnston, Malcolm J. S.; Soule, S. Adam; McPhee, Darcy; Glen, Jonathan M. G.; Karlstrom, Leif; Murphy, Fred

    2014-12-01

    We use seismic, tilt, lidar, thermal, and gravity data from 32 consecutive eruption cycles of Lone Star geyser in Yellowstone National Park to identify key subsurface processes throughout the geyser's eruption cycle. Previously, we described measurements and analyses associated with the geyser's erupting jet dynamics. Here we show that seismicity is dominated by hydrothermal tremor (~5-40 Hz) attributed to the nucleation and/or collapse of vapor bubbles. Water discharge during eruption preplay triggers high-amplitude tremor pulses from a back azimuth aligned with the geyser cone, but during the rest of the eruption cycle it is shifted to the east-northeast. Moreover, ~4 min period ground surface displacements recur every 26 ± 8 min and are uncorrelated with the eruption cycle. Based on these observations, we conclude that (1) the dynamical behavior of the geyser is controlled by the thermo-mechanical coupling between the geyser conduit and a laterally offset reservoir periodically filled with a highly compressible two-phase mixture, (2) liquid and steam slugs periodically ascend into the shallow crust near the geyser system inducing detectable deformation, (3) eruptions occur when the pressure decrease associated with overflow from geyser conduit during preplay triggers an unstable feedback between vapor generation (cavitation) and mass discharge, and (4) flow choking at a constriction in the conduit arrests the runaway process and increases the saturated vapor pressure in the reservoir by a factor of ~10 during eruptions.

  5. The Lone Ranger Mission: Understanding Synthetic Polymer Microbe Interactions In the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Mielke, R.; Neal, A.; Stam, C. N.; Ferry, J. G.; Schlegel, R.; Tsapin, A. I.; Park, S.; Bhartia, R.; Salas, E.; Hug, W.; Behar, A. E.; Nadeau, J.

    2011-12-01

    Pollution is one of the most ubiquitous and insidious problems currently facing the oceans. As synthetic polymer debris degrades, it becomes increasingly accessible to organisms that forage or absorb food particles. However, research on this significant environmental pollution problem has not been able to keep up with the scope of the issue, since some of the first studies published in 1972 by Edward Carpenter. In January 2011, The Lone Ranger Atlantic Expedition, a collaboration between Blue Ocean Sciences (BOS) and the Schmidt Ocean Institute (SOI) transected the Atlantic Ocean covering 3,100 nautical miles sampling the first 15cm of the water column to investigate microbial interactions with synthetic polymer marine debris. Using established and novel techniques of Fourier transform infrared spectroscopy (FT-IR), scanning transmission electron microscopy (STEM), environmental scanning electron microscopy (ESEM), and gas chromatography-mass spectrometry (GC-MS), we were able to image and locate material degradation of pre-production, association of microbial biofilms, and accumulation of persistent organic pollutants (POP's) on environmental microplastics. We then used Spectroscopic Organic Analysis and ArcGIS mapping systems to observe the material degradation and the associated biofilm lattice on the environmental microplastics. This data sheds light on possible mechanisms of material weathering of synthetic polymers in deep ocean environments and new methods for identifying POP's association with them. These new techniques are highly transferable to many studies on material biofilm interactions in the environment.

  6. Eruptions at Lone Star geyser, Yellowstone National Park, USA: 2. Constraints on subsurface dynamics

    USGS Publications Warehouse

    Vandemeulebrouck, Jean; Sohn, Robert A.; Rudolph, Maxwell L.; Hurwitz, Shaul; Manga, Michael; Johnston, Malcolm J.S.; Soule, S. Adam; McPhee, Darcy K.; Glen, Jonathan M.G.; Karlstrom, Leif; Murphy, Fred

    2014-01-01

    We use seismic, tilt, lidar, thermal, and gravity data from 32 consecutive eruption cycles of Lone Star geyser in Yellowstone National Park to identify key subsurface processes throughout the geyser's eruption cycle. Previously, we described measurements and analyses associated with the geyser's erupting jet dynamics. Here we show that seismicity is dominated by hydrothermal tremor (~5–40 Hz) attributed to the nucleation and/or collapse of vapor bubbles. Water discharge during eruption preplay triggers high-amplitude tremor pulses from a back azimuth aligned with the geyser cone, but during the rest of the eruption cycle it is shifted to the east-northeast. Moreover, ~4 min period ground surface displacements recur every 26 ± 8 min and are uncorrelated with the eruption cycle. Based on these observations, we conclude that (1) the dynamical behavior of the geyser is controlled by the thermo-mechanical coupling between the geyser conduit and a laterally offset reservoir periodically filled with a highly compressible two-phase mixture, (2) liquid and steam slugs periodically ascend into the shallow crust near the geyser system inducing detectable deformation, (3) eruptions occur when the pressure decrease associated with overflow from geyser conduit during preplay triggers an unstable feedback between vapor generation (cavitation) and mass discharge, and (4) flow choking at a constriction in the conduit arrests the runaway process and increases the saturated vapor pressure in the reservoir by a factor of ~10 during eruptions.

  7. Henry James's "The Ambassadors": the promise to lonely adolescents that there will be a future.

    PubMed

    Young, Barbara

    2009-01-01

    Adolescence is a lonely time for all of us, as we shift our emotional attachment from our parents to our own autonomous selves and to those people outside our families who will be essential to our emotional growth. Perhaps because Henry James's novel The Ambassadors (1903) deals so masterfully with this subject, it promised the author that there would be a future beyond her senior year in college. The novel has two protagonists: a young American who has arrived at his maturity in Paris, and a middle-aged man who lives in a gray, ungratifying world because he has missed the opportunity to complete his unfolding into an independent sexual being. For background material, James called upon two periods from his own life: his unhappy adolescence, which he overcame by making a life for himself as a writer in England, and his continuing emotional growth at the time he wrote the novel, at the age of 56. The author deals with both adolescence itself and with the ways in which we use the coping skills and creative strengths we developed in adolescence to enrich our lives and sustain ourselves at times of crisis.

  8. Paired Straight Hearth Furnace

    SciTech Connect

    2009-04-01

    This factsheet describes a research project whose goals are to design, develop, and evaluate the scalability and commercial feasibility of the PSH Paired Straight Hearth Furnace alternative ironmaking process.

  9. 90 Seconds of Discovery: Frustrated Lewis Pairs

    SciTech Connect

    Kathmann, Shawn; Schenter, Greg; Autrey, Tom

    2014-02-14

    Hydrogen activating catalysts play an important role in producing valuable chemicals, such as biofuels and ammonia. As a part of efforts to develop the next generation of these catalysts, PNNL researchers have found potential in Frustrated Lewis Pairs.

  10. 90 Seconds of Discovery: Frustrated Lewis Pairs

    ScienceCinema

    Kathmann, Shawn; Schenter, Greg; Autrey, Tom

    2016-07-12

    Hydrogen activating catalysts play an important role in producing valuable chemicals, such as biofuels and ammonia. As a part of efforts to develop the next generation of these catalysts, PNNL researchers have found potential in Frustrated Lewis Pairs.

  11. Characterization of Lone Pine, California, tremolite asbestos and preparation of research material

    USGS Publications Warehouse

    Harper, Martin; Van Gosen, Bradley S.; Crankshaw, Owen S; Doorn, Stacy S; Ennis, J. Todd; Harrison, Sara E

    2014-01-01

    Well-characterized amphibole asbestos mineral samples are required for use as analytical standards and in future research projects. Currently, the National Institute for Standards and Technology Standard Reference Material samples of asbestos are listed as ‘Discontinued’. The National Institute for Occupational Safety and Health (NIOSH) has a goal under the Asbestos Roadmap of locating and characterizing research materials for future use. Where an initial characterization analysis determines that a collected material is appropriate for use as a research material in terms of composition and asbestiform habit, sufficient amounts of the material will be collected to make it publicly available. An abandoned mine near Lone Pine, California, contains a vein of tremolite asbestos, which was the probable source of a reference material that has been available for the past 17 years from the Health and Safety Laboratory (HSL) in the UK. Newly collected fibrous vein material from this mine was analyzed at Research Triangle Institute (RTI International) with some additional analysis by the US Geological Survey’s Denver Microbeam Laboratory. The analysis at RTI International included: (i) polarized light microscopy (PLM) with a determination of principal optical properties; (ii) X-ray diffraction; (iii) transmission electron microscopy, including energy dispersive X-ray spectroscopy and selected-area electron diffraction; and (iv) spindle stage analysis using PLM to determine whether individual fibers and bundles of the samples were polycrystalline or single-crystal cleavage fragments. The overall findings of the study indicated that the material is tremolite asbestos with characteristics substantially similar to the earlier distributed HSL reference material. A larger quantity of material was prepared by sorting, acid-washing and mixing for sub-division into vials of ~10g each. These vials have been transferred from NIOSH to RTI International, from where they can be

  12. Characterization of the bacterial communities of life stages of free living lone star ticks (Amblyomma americanum).

    PubMed

    Williams-Newkirk, Amanda Jo; Rowe, Lori A; Mixson-Hayden, Tonya R; Dasch, Gregory A

    2014-01-01

    The lone star tick (Amblyomma americanum) is an abundant and aggressive biter of humans, domestic animals, and wildlife in the southeastern-central USA and an important vector of several known and suspected zoonotic bacterial pathogens. However, the biological drivers of bacterial community variation in this tick are still poorly defined. Knowing the community context in which tick-borne bacterial pathogens exist and evolve is required to fully understand the ecology and immunobiology of the ticks and to design effective public health and veterinary interventions. We performed a metagenomic survey of the bacterial communities of questing A. americanum and tested 131 individuals (66 nymphs, 24 males, and 41 females) from five sites in three states. Pyrosequencing was performed with barcoded eubacterial primers targeting variable 16S rRNA gene regions 5-3. The bacterial communities were dominated by Rickettsia (likely R. amblyommii) and an obligate Coxiella symbiont, together accounting for 6.7-100% of sequences per tick. DNAs from Midichloria, Borrelia, Wolbachia, Ehrlichia, Pseudomonas, or unidentified Bacillales, Enterobacteriaceae, or Rhizobiales groups were also detected frequently. Wolbachia and Midichloria significantly co-occurred in Georgia (p<0.00001), but not in other states. The significance of the Midichloria-Wolbachia co-occurrence is unknown. Among ticks collected in Georgia, nymphs differed from adults in both the composition (p = 0.002) and structure (p = 0.002) of their bacterial communities. Adults differed only in their community structure (p = 0.002) with males containing more Rickettsia and females containing more Coxiella. Comparisons among adult ticks collected in New York and North Carolina supported the findings from the Georgia collection despite differences in geography, collection date, and sample handling, implying that the differences detected are consistent attributes. The data also suggest that some members of the

  13. Broadband Seismic Observations of Lone Star Geyser, Yellowstone National Park, Wyoming, USA

    NASA Astrophysics Data System (ADS)

    Nayak, A.; Hurwitz, S.; Johnson, H. E., III; Manga, M.; Gomez, F. G.

    2014-12-01

    Geysers are natural phenomena that episodically erupt water and steam. Geophysical observations at geysers are analyzed to shed light on subsurface multi-phase mass and heat exchange processes and geometries controlling geyser eruptions, which are still are not completely understood. Lone Star Geyser (LSG) in Yellowstone National Park, Wyoming, USA erupts every ~3 hours, with brief episodes (~5-10 min) of water and steam fountaining (preplays) leading up to the main eruption (~28 min), and the discharge evolves from a water-dominated phase to a steam-dominated phase as the main eruption proceeds in time. We describe observations from multiple seismometers deployed around LSG as part of a comprehensive geophysical survey conducted in April 2014. 3-component seismograms were continuously recorded at 250 samples per second by 6 Nanometrics Trillium 120 P/PA broadband seismometers (lower corner frequency at 120 seconds) and Taurus dataloggers at distances ~10 to 25 m from the geyser cone for a period of 3 days. We identify distinct episodes of hydrothermal tremor associated with preplay events and main eruptions. We find that the dominant tremor frequencies during main eruptions are consistently higher (> 10.0 Hz) than those during preplays (> 1.0 Hz) indicating slightly different source locations or processes controlling the two phenomena. Unlike seismic observations at the Old Faithful Geyser, we also observe subtle harmonic tremor and spectral gliding in the frequency range ~1.0-8.0 Hz towards the end of both main eruption and preplay tremor episodes. We interpret long-period pulses on horizontal components of the seismometers located close to the geyser and synchronous with preplays, as pseudo-tilts resulting from deformation of the sinter terrace. We also compare the evolution of hydrothermal tremor in time with synchronous changes in temperature, acoustic emission and discharge for interpretation of the possible tremor source processes.

  14. Kepler-424 b: A "Lonely" Hot Jupiter that Found a Companion

    NASA Astrophysics Data System (ADS)

    Endl, Michael; Caldwell, Douglas A.; Barclay, Thomas; Huber, Daniel; Isaacson, Howard; Buchhave, Lars A.; Brugamyer, Erik; Robertson, Paul; Cochran, William D.; MacQueen, Phillip J.; Havel, Mathieu; Lucas, Phillip; Howell, Steve B.; Fischer, Debra; Quintana, Elisa; Ciardi, David R.

    2014-11-01

    Hot Jupiter systems provide unique observational constraints for migration models in multiple systems and binaries. We report on the discovery of the Kepler-424 (KOI-214) two-planet system, which consists of a transiting hot Jupiter (Kepler-424b) in a 3.31 day orbit accompanied by a more massive outer companion in an eccentric (e = 0.3) 223 day orbit. The outer giant planet, Kepler-424c, is not detected transiting the host star. The masses of both planets and the orbital parameters for the second planet were determined using precise radial velocity (RV) measurements from the Hobby-Eberly Telescope (HET) and its High Resolution Spectrograph (HRS). In stark contrast to smaller planets, hot Jupiters are predominantly found to be lacking any nearby additional planets; they appear to be "lonely". This might be a consequence of these systems having a highly dynamical past. The Kepler-424 planetary system has a hot Jupiter in a multiple system, similar to \\upsilon Andromedae. We also present our results for Kepler-422 (KOI-22), Kepler-77 (KOI-127), Kepler-43 (KOI-135), and Kepler-423 (KOI-183). These results are based on spectroscopic data collected with the Nordic Optical Telescope (NOT), the Keck 1 telescope, and HET. For all systems, we rule out false positives based on various follow-up observations, confirming the planetary nature of these companions. We performed a comparison with planetary evolutionary models which indicate that these five hot Jupiters have heavy element contents between 20 and 120 M ⊕. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  15. Characterization of Lone Pine, California, tremolite asbestos and preparation of research material.

    PubMed

    Harper, Martin; Van Gosen, Bradley; Crankshaw, Owen S; Doorn, Stacy S; Ennis, Todd J; Harrison, Sara E

    2015-01-01

    Well-characterized amphibole asbestos mineral samples are required for use as analytical standards and in future research projects. Currently, the National Institute for Standards and Technology Standard Reference Material samples of asbestos are listed as 'Discontinued'. The National Institute for Occupational Safety and Health (NIOSH) has a goal under the Asbestos Roadmap of locating and characterizing research materials for future use. Where an initial characterization analysis determines that a collected material is appropriate for use as a research material in terms of composition and asbestiform habit, sufficient amounts of the material will be collected to make it publicly available. An abandoned mine near Lone Pine, California, contains a vein of tremolite asbestos, which was the probable source of a reference material that has been available for the past 17 years from the Health and Safety Laboratory (HSL) in the UK. Newly collected fibrous vein material from this mine was analyzed at Research Triangle Institute (RTI International) with some additional analysis by the US Geological Survey's Denver Microbeam Laboratory. The analysis at RTI International included: (i) polarized light microscopy (PLM) with a determination of principal optical properties; (ii) X-ray diffraction; (iii) transmission electron microscopy, including energy dispersive X-ray spectroscopy and selected-area electron diffraction; and (iv) spindle stage analysis using PLM to determine whether individual fibers and bundles of the samples were polycrystalline or single-crystal cleavage fragments. The overall findings of the study indicated that the material is tremolite asbestos with characteristics substantially similar to the earlier distributed HSL reference material. A larger quantity of material was prepared by sorting, acid-washing and mixing for sub-division into vials of ~10g each. These vials have been transferred from NIOSH to RTI International, from where they can be obtained on

  16. Eruptions at Lone Star Geyser, Yellowstone National Park, USA, part 1: energetics and eruption dynamics

    USGS Publications Warehouse

    Karlstrom, Leif; Hurwitz, Shaul; Sohn, Robert; Vandemeulebrouck, Jean; Murphy, Fred; Rudolph, Maxwell L.; Johnston, Malcolm J.S.; Manga, Michael; McCleskey, R. Blaine

    2013-01-01

    Geysers provide a natural laboratory to study multiphase eruptive processes. We present results from a four–day experiment at Lone Star Geyser in Yellowstone National Park, USA. We simultaneously measured water discharge, acoustic emissions, infraredintensity, and visible and infrared video to quantify the energetics and dynamics of eruptions, occurring approximately every three hours. We define four phases in the eruption cycle: 1) a 28 ± 3 minute phase with liquid and steam fountaining, with maximum jet velocities of 16–28 m s− 1, steam mass fraction of less than ∼ 0.01. Intermittently choked flow and flow oscillations with periods increasing from 20 to 40 s are coincident with a decrease in jet velocity and an increase of steam fraction; 2) a 26 ± 8 minute post–eruption relaxation phase with no discharge from the vent, infrared (IR) and acoustic power oscillations gliding between 30 and 40 s; 3) a 59 ± 13 minute recharge period during which the geyser is quiescent and progressively refills, and 4) a 69 ± 14 minute pre–play period characterized by a series of 5–10 minute–long pulses of steam, small volumes of liquid water discharge and 50–70 s flow oscillations. The erupted waters ascend froma 160 − 170° C reservoir and the volume discharged during the entire eruptive cycle is 20.8 ± 4.1 m3. Assuming isentropic expansion, we calculate a heat output from the geyser of 1.4–1.5 MW, which is < 0.1% of the total heat output from Yellowstone Caldera.

  17. A Coxiella-Like Endosymbiont Is a Potential Vitamin Source for the Lone Star Tick

    PubMed Central

    Smith, Todd A; Driscoll, Timothy; Gillespie, Joseph J; Raghavan, Rahul

    2015-01-01

    Amblyomma americanum (Lone star tick) is an important disease vector in the United States. It transmits several human pathogens, including the agents of human monocytic ehrlichiosis, tularemia, and southern tick-associated rash illness. Blood-feeding insects (Class Insecta) depend on bacterial endosymbionts to provide vitamins and cofactors that are scarce in blood. It is unclear how this deficiency is compensated in ticks (Class Arachnida) that feed exclusively on mammalian blood. A bacterium related to Coxiella burnetii, the agent of human Q fever, has been observed previously within cells of A. americanum. Eliminating this bacterium (CLEAA, Coxiella-like endosymbiont of A. americanum) with antibiotics reduced tick fecundity, indicating that it is an essential endosymbiont. In an effort to determine its role within this symbiosis, we sequenced the CLEAA genome. While highly reduced (656,901 bp) compared with C. burnetii (1,995,281 bp), the CLEAA genome encodes most major vitamin and cofactor biosynthesis pathways, implicating CLEAA as a vitamin provisioning endosymbiont. In contrast, CLEAA lacks any recognizable virulence genes, indicating that it is not a pathogen despite its presence in tick salivary glands. As both C. burnetii and numerous “Coxiella-like bacteria” have been reported from several species of ticks, we determined the evolutionary relationship between the two bacteria. Phylogeny estimation revealed that CLEAA is a close relative of C. burnetii, but was not derived from it. Our results are important for strategies geared toward controlling A. americanum and the pathogens it vectors, and also contribute novel information regarding the metabolic interdependencies of ticks and their nutrient-provisioning endosymbionts. PMID:25618142

  18. Characterization of Lone Pine, California, Tremolite Asbestos and Preparation of Research Material

    PubMed Central

    Harper, Martin; Van Gosen, Bradley; Crankshaw, Owen S.; Doorn, Stacy S.; Ennis, Todd J.; Harrison, Sara E.

    2016-01-01

    Well-characterized amphibole asbestos mineral samples are required for use as analytical standards and in future research projects. Currently, the National Institute for Standards and Technology Standard Reference Material samples of asbestos are listed as ‘Discontinued’. The National Institute for Occupational Safety and Health (NIOSH) has a goal under the Asbestos Roadmap of locating and characterizing research materials for future use. Where an initial characterization analysis determines that a collected material is appropriate for use as a research material in terms of composition and asbestiform habit, sufficient amounts of the material will be collected to make it publicly available. An abandoned mine near Lone Pine, California, contains a vein of tremolite asbestos, which was the probable source of a reference material that has been available for the past 17 years from the Health and Safety Laboratory (HSL) in the UK. Newly collected fibrous vein material from this mine was analyzed at Research Triangle Institute (RTI International) with some additional analysis by the US Geological Survey’s Denver Microbeam Laboratory. The analysis at RTI International included: (i) polarized light microscopy (PLM) with a determination of principal optical properties; (ii) X-ray diffraction; (iii) transmission electron microscopy, including energy dispersive X-ray spectroscopy and selected-area electron diffraction; and (iv) spindle stage analysis using PLM to determine whether individual fibers and bundles of the samples were polycrystalline or single-crystal cleavage fragments. The overall findings of the study indicated that the material is tremolite asbestos with characteristics substantially similar to the earlier distributed HSL reference material. A larger quantity of material was prepared by sorting, acid-washing and mixing for sub-division into vials of ~10 g each. These vials have been transferred from NIOSH to RTI International, from where they can be

  19. Characterization of the Bacterial Communities of Life Stages of Free Living Lone Star Ticks (Amblyomma americanum)

    PubMed Central

    Williams-Newkirk, Amanda Jo; Rowe, Lori A.; Mixson-Hayden, Tonya R.; Dasch, Gregory A.

    2014-01-01

    The lone star tick (Amblyomma americanum) is an abundant and aggressive biter of humans, domestic animals, and wildlife in the southeastern-central USA and an important vector of several known and suspected zoonotic bacterial pathogens. However, the biological drivers of bacterial community variation in this tick are still poorly defined. Knowing the community context in which tick-borne bacterial pathogens exist and evolve is required to fully understand the ecology and immunobiology of the ticks and to design effective public health and veterinary interventions. We performed a metagenomic survey of the bacterial communities of questing A. americanum and tested 131 individuals (66 nymphs, 24 males, and 41 females) from five sites in three states. Pyrosequencing was performed with barcoded eubacterial primers targeting variable 16S rRNA gene regions 5–3. The bacterial communities were dominated by Rickettsia (likely R. amblyommii) and an obligate Coxiella symbiont, together accounting for 6.7–100% of sequences per tick. DNAs from Midichloria, Borrelia, Wolbachia, Ehrlichia, Pseudomonas, or unidentified Bacillales, Enterobacteriaceae, or Rhizobiales groups were also detected frequently. Wolbachia and Midichloria significantly co-occurred in Georgia (p<0.00001), but not in other states. The significance of the Midichloria-Wolbachia co-occurrence is unknown. Among ticks collected in Georgia, nymphs differed from adults in both the composition (p = 0.002) and structure (p = 0.002) of their bacterial communities. Adults differed only in their community structure (p = 0.002) with males containing more Rickettsia and females containing more Coxiella. Comparisons among adult ticks collected in New York and North Carolina supported the findings from the Georgia collection despite differences in geography, collection date, and sample handling, implying that the differences detected are consistent attributes. The data also suggest that some members of the

  20. Boron as an Electron-Pair Donor for B⋅⋅⋅Cl Halogen Bonds.

    PubMed

    Alkorta, Ibon; Elguero, José; Del Bene, Janet E

    2016-10-05

    MP2/aug'-cc-pVTZ calculations were performed to investigate boron as an electron-pair donor in halogen-bonded complexes (CO)2 (HB):ClX and (N2 )2 (HB):ClX, for X=F, Cl, OH, NC, CN, CCH, CH3 , and H. Equilibrium halogen-bonded complexes with boron as the electron-pair donor are found on all of the potential surfaces, except for (CO)2 (HB):ClCH3 and (N2 )2 (HB):ClF. The majority of these complexes are stabilized by traditional halogen bonds, except for (CO)2 (HB):ClF, (CO)2 (HB):ClCl, (N2 )2 (HB):ClCl, and (N2 )2 (HB):ClOH, which are stabilized by chlorine-shared halogen bonds. These complexes have increased binding energies and shorter B-Cl distances. Charge transfer stabilizes all complexes and occurs from the B lone pair to the σ* Cl-A orbital of ClX, in which A is the atom of X directly bonded to Cl. A second reduced charge-transfer interaction occurs in (CO)2 (HB):ClX complexes from the Cl lone pair to the π* C≡O orbitals. Equation-of-motion coupled cluster singles and doubles (EOM-CCSD) spin-spin coupling constants, (1x) J(B-Cl), across the halogen bonds are also indicative of the changing nature of this bond. (1x) J(B-Cl) values for both series of complexes are positive at long distances, increase as the distance decreases, and then decrease as the halogen bonds change from traditional to chlorine-shared bonds, and begin to approach the values for the covalent bonds in the corresponding ions [(CO)2 (HB)-Cl](+) and [(N2 )2 (HB)-Cl](+) . Changes in (11) B chemical shieldings upon complexation correlate with changes in the charges on B.

  1. Reversal of the Detrimental Effects of Post-Stroke Social Isolation by Pair-Housing is Mediated by Activation of BDNF-MAPK/ERK in Aged Mice

    PubMed Central

    Verma, Rajkumar; Harris, Nia M.; Friedler, Brett D.; Crapser, Joshua; Patel, Anita R.; Venna, Venugopal; McCullough, Louise D.

    2016-01-01

    Social isolation (SI) increases stroke-related mortality and morbidity in clinical populations. The detrimental effects of SI have been successfully modeled in the laboratory using young animals. Mechanistically, the negative effects of SI in young animals are primarily mediated by an enhanced inflammatory response to injury and a reduction in neurotrophic factors. However, the response to brain injury differs considerably in the aged. Given that SI is more prevalent in aged populations, we hypothesized that isolation, even when initiated after stroke, would delay recovery in aged mice. We found that aged isolated male mice had significantly increased infarct volume, neurological deficits, and serum IL-6 levels three days after stroke compared to pair housed (PH) mice. Using RT2 Profiler PCR Array and real-time quantitative PCR we found several important synaptic plasticity genes were differentially expressed in post-stroke SI mice. Furthermore, paired mice showed improved memory and neurobehavioral recovery four weeks after injury. Mechanistic and histological studies showed that the beneficial effects of pair housing are partially mediated by BDNF via downstream MAPK/ERK signaling and restoration of axonal basic myelin protein levels. PMID:27125783

  2. 1,2-Diphosphonium dication: a strong P-based Lewis acid in frustrated lewis pair (FLP)-activations of B-H, Si-H, C-H, and H-H bonds.

    PubMed

    Holthausen, Michael H; Bayne, Julia M; Mallov, Ian; Dobrovetsky, Roman; Stephan, Douglas W

    2015-06-17

    A highly Lewis acidic diphosphonium dication [(C10H6)(Ph2P)2](2+) (1), in combination with a Lewis basic phosphine, acts as a purely phosphorus-based frustrated Lewis pair (FLP) and abstracts hydride from [HB(C6F5)3](-) and Et3SiH demonstrating the remarkable hydridophilicity of 1. The P-based FLP is also shown to activate H2 and C-H bonds.

  3. On Adiabatic Pair Creation

    NASA Astrophysics Data System (ADS)

    Pickl, Peter; Dürr, Detlef

    2008-08-01

    We give here a rigorous proof of the well known prediction of pair creation as it arises from the Dirac equation with an external time dependent potential. Pair creation happens with probability one if the potential changes adiabatically in time and becomes overcritical, which means that an eigenvalue curve (as a function of time) bridges the gap between the negative and positive spectral continuum. The potential can be thought of as being zero at large negative and large positive times. The rigorous treatment of this effect has been lacking since the pioneering work of Beck, Steinwedel and Süßmann [1] in 1963 and Gershtein and Zeldovich [8] in 1970.

  4. Minimal Pairs: Minimal Importance?

    ERIC Educational Resources Information Center

    Brown, Adam

    1995-01-01

    This article argues that minimal pairs do not merit as much attention as they receive in pronunciation instruction. There are other aspects of pronunciation that are of greater importance, and there are other ways of teaching vowel and consonant pronunciation. (13 references) (VWL)

  5. Synthesis and physicochemical characterization of two lead(II) complexes with O-, N-donor ligands. Lone pair functionality and crystal structure.

    PubMed

    Masternak, Joanna; Barszcz, Barbara; Hodorowicz, Maciej; Khavryuchenko, Oleksiy V; Majka, Alina

    2015-02-05

    A dinuclear [Pb2(4-CHO-5-MeIm)6(NO3)2](NO3)2 (1) and a polynuclear [Pb(2-pzc)2(H2O)]n (2) complexes (where 5(4)-carbaldehyde-4(5)-methylimidazole (5(4)-CHO-4(5)-MeIm) and pyrazine-2-carboxylic acid (2-pzcH)) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. Structural determination for complex 1 reveals a cationic species [Pb(4-CHO-5-MeIm)3]2+ connected through bridging nitrate(V) ions. There are also an uncoordinated nitrate ions as counterions. Complex 2 is a three-dimensional architecture consisting of Pb6O12 building units. The pyrazine-2-carboxylato ligand behaves as a chelating agent and a bi-connective bridge. The coordination polyhedra around lead(II) ion could be described as a distorted docecahedron (1) or monocapped trigonal prism (2). The luminescent properties of 1 and 2 investigated in the solid state at room temperature indicate structure-dependent photoluminescent properties. The DFT calculations and the X-ray structural data point on rather hemidirected type of coordination around Pb(II) ions of 1 and 2.

  6. π-Delocalization in the vicinal lone pairs of hydrazines: Electronic effects in derivatives of 1-(2-nitrophenyl)-1-phenylhydrazine

    NASA Astrophysics Data System (ADS)

    Poisson, Joël; Butler, Ian S.; Bohle, D. Scott

    2016-07-01

    Several highly colored, crystalline derivatives of 1-(2-nitrophenyl)-1-phenylhydrazine have been synthesized and characterized by UV-Vis, 1H- and 13C-NMR, mass and IR spectroscopic methods, as well as by single-crystal X-ray diffraction and combustion elemental analysis. The study indicates that the electronic dependence of one nitrogen atom on the other in these systems becomes more pronounced with a decrease in the difference of their formal hybridization. While 1,1-di-aromatic substitution leads to a formal sp2 hybridization at one nitrogen atom, introduction of a π-bond in the form of a Schiff base or an acetylamide function at the second nitrogen atom leads to different hydrazine conformations and N-N bond lengths. One interpretation of these results is that, in many cases, a greater contribution from σ-bonding from two sp2 hybridized nitrogen atoms leads to stronger and shorter N-N bonds than do the often proposed N-N π-bonding double bonds in the absence of significant intermolecular forces.

  7. The Microbiome of Ehrlichia-Infected and Uninfected Lone Star Ticks (Amblyomma americanum)

    PubMed Central

    Trout Fryxell, R. T.; DeBruyn, J. M.

    2016-01-01

    The Lone Star tick, Amblyomma americanum, transmits several bacterial pathogens including species of Anaplasma and Ehrlichia. Amblyomma americanum also hosts a number of non-pathogenic bacterial endosymbionts. Recent studies of other arthropod and insect vectors have documented that commensal microflora can influence transmission of vector-borne pathogens; however, little is known about tick microbiomes and their possible influence on tick-borne diseases. Our objective was to compare bacterial communities associated with A. americanum, comparing Anaplasma/Ehrlichia -infected and uninfected ticks. Field-collected questing specimens (n = 50) were used in the analyses, of which 17 were identified as Anaplasma/Ehrlichia infected based on PCR amplification and sequencing of groEL genes. Bacterial communities from each specimen were characterized using Illumina sequencing of 16S rRNA gene amplicon libraries. There was a broad range in diversity between samples, with inverse Simpson’s Diversity indices ranging from 1.28–89.5. There were no statistical differences in the overall microbial community structure between PCR diagnosed Anaplasma/Ehrlichia-positive and negative ticks, but there were differences based on collection method (P < 0.05), collection site (P < 0.05), and sex (P < 0.1) suggesting that environmental factors may structure A. americanum microbiomes. Interestingly, there was not always agreement between Illumina sequencing and PCR diagnostics: Ehrlichia was identified in 16S rRNA gene libraries from three PCR-negative specimens; conversely, Ehrlichia was not found in libraries of six PCR-positive ticks. Illumina sequencing also helped identify co-infections, for example, one specimen had both Ehrlichia and Anaplasma. Other taxa of interest in these specimens included Coxiella, Borrelia, and Rickettsia. Identification of bacterial community differences between specimens of a single tick species from a single geographical site indicates that intra

  8. Protected Flux Pairing Qubit

    NASA Astrophysics Data System (ADS)

    Bell, Matthew; Zhang, Wenyuan; Ioffe, Lev; Gershenson, Michael

    2014-03-01

    We have studied the coherent flux tunneling in a qubit containing two submicron Josephson junctions shunted by a superinductor (a dissipationless inductor with an impedance much greater than the resistance quantum). The two low energy quantum states of this device, 0 and 1, are represented by even and odd number of fluxes in the loop, respectively. This device is dual to the charge pairing Josephson rhombi qubit. The spectrum of the device, studied by microwave spectroscopy, reflects the interference between coherent quantum phase slips in the two junctions (the Aharonov-Casher effect). The time domain measurements demonstrate the suppression of the qubit's energy relaxation in the protected regime, which illustrates the potential of this flux pairing device as a protected quantum circuit. Templeton Foundation, NSF, and ARO.

  9. Junctionless Cooper pair transistor

    NASA Astrophysics Data System (ADS)

    Arutyunov, K. Yu.; Lehtinen, J. S.

    2017-02-01

    Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one-dimensional superconductor: momentary zeroing of the modulus and simultaneous 'slip' of the phase by ±2π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current-voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.

  10. Polymerization by classical and frustrated Lewis pairs.

    PubMed

    Chen, Eugene Y-X

    2013-01-01

    Main-group classical and frustrated Lewis pairs (CLPs and FLPs) comprising strong Lewis acids (LAs) and strong Lewis bases (LBs) are highly active for polymerization of conjugated polar alkenes, affording typically high molecular weight polymers with relatively narrow molecular weight distributions. Especially effective systems are the Lewis pairs (LPs) consisting of the strong LA Al(C6F5)3 and strong LBs, such as achiral phosphines and chiral chelating diphosphines, N-heterocyclic carbenes, and phosphazene superbases, for polymerization of methacrylates and acrylamides as well as renewable α-methylene-γ-butyrolactones. Chain initiation involves cooperative addition of LPs to the monomer to generate zwitterionic active species, and chain propagation proceeds via a bimetallic, activated-monomer addition mechanism. Transition metal nucleophile/electrophile pairs comprising neutral metallocene bis(ester enolate)s and strong LAs E(C6F5)3 (E = Al, B) generate two drastically different polymerization systems, depending on the LA. With E = Al, catalyst activation and chain initiating events lead to dually active ion-pairs, thereby effecting ion-pairing polymerization that affords polymers with unique stereo-multiblock microstructures. With E = B, on the other hand, the FLP-induced catalyst activation generates metallacyclic cations paired with the hydridoborate anion [HB(C6F5)3](-); uniquely, such ion-pairs effect catalytic polymerization of conjugated polar alkenes by an H-shuttling mechanism, with the cation catalyzing chain growth and the anion promoting chain transfer by shuttling the hydride between the cation and anion centers through the neutral borane.

  11. Stereo Pair, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This view of northern Patagonia, at Los Menucos, Argentina shows remnants of relatively young volcanoes built upon an eroded plain of much older and contorted volcanic, granitic, and sedimentary rocks. The large purple, brown, and green 'butterfly' pattern is a single volcano that has been deeply eroded. Large holes on the volcano's flanks indicate that they may have collapsed soon after eruption, as fluid molten rock drained out from under its cooled and solidified outer shell. At the upper left, a more recent eruption occurred and produced a small volcanic cone and a long stream of lava, which flowed down a gully. At the top of the image, volcanic intrusions permeated the older rocks resulting in a chain of small dark volcanic peaks. At the top center of the image, two halves of a tan ellipse pattern are offset from each other. This feature is an old igneous intrusion that has been split by a right-lateral fault. The apparent offset is about 6.6 kilometers (4 miles). Color, tonal, and topographic discontinuities reveal the fault trace as it extends across the image to the lower left. However, young unbroken basalt flows show that the fault has not been active recently.

    This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive

  12. Pair of Craters

    NASA Technical Reports Server (NTRS)

    2005-01-01

    14 July 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a 1.5 meters per pixel (5 ft/pixel) view of a pair of small meteor impact craters in the Arena Colles region of Mars, located north of Isidis Planitia.

    Location near: 22.7oN, 278.5oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  13. Expression of bovine genes associated with local and systemic immune response to infestation with the Lone Star tick, Amblyomma americanum.

    PubMed

    Brannan, Jaime L; Riggs, Penny K; Olafson, Pia U; Ivanov, Ivan; Holman, Patricia J

    2014-10-01

    The Lone Star tick, Amblyomma americanum Linnaeus 1758 (Acari; Ixodidae), causes considerable production losses to the southern U.S. cattle industry due to reduced weight, infertility, secondary infections at bite wound sites, damaged hides, and potentially death, as these ticks tend to infest livestock in large numbers. Increasing environmental concerns, along with the potential for chemical residue in food products, have led to more emphasis on alternative tick control strategies, such as selective breeding practices and anti-tick vaccines. To enable progress toward these goals, a better understanding of bovine host immune mechanisms elicited by ticks is needed. In this study, 7 calves were phenotyped as susceptible, moderately resistant, or highly resistant to adult A. americanum ticks. Tick bite-site biopsies and blood leukocytes were collected at multiple time points throughout 3 successive tick infestations. Gene expression at tick bite-site biopsies was assessed by microarray analysis over 3 time points for each phenotype group. Quantitative reverse transcriptase-PCR expression analysis evaluated 11 candidate genes in tick bite-site biopsies, and 6 in blood leukocytes. Regression curve estimates calculated from the expression values generated by qRT-PCR in tick bite-sites identified correlations between several candidate genes. Increased expression of IGHG1, IL6, IL1α, and IL1RN in bovine tick bite-site biopsies suggests that Th2 differentiation may be important for the local bovine response to A. americanum ticks. Strong correlations in expression for IL1α and IL1β, for IL1α and IL1RN, and for IL1α and TLR4 were found in biopsies from the tick-resistant phenotypes. The up-regulation of IL12 and IL23 in blood leukocytes from Lone Star tick-infested calves of all phenotypes suggests a possible systemic recruitment of memory T cells. This study provides novel insight concerning the bovine immune response to Lone Star ticks and a basis for future

  14. Surface deformation and seismic signatures associated with the eruption cycle of Lone Star Geyser, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Gomez, F. G.; Johnson, H. E., III; LeWinter, A. L.; Finnegan, D. C.; Sandvol, E. A.; Nayak, A.; Hurwitz, S.

    2014-12-01

    Geysers are important subjects for studying processes involved with multi-phase eruptions. As part of a larger field effort, this study applies imaging geodesy and seismology to study eruptive cycles of the Lone Star Geyser in Yellowstone National Park. Lone Star Geyser is an ideal candidate for such study, as it erupts with a nearly regular period of approximately 3 hours. The geyser includes a 5 m diameter cone that rises 2 meters above the sinter terrace, and the entire system can be viewed from a nearby hillside. Fieldwork was accomplished during April 2014. Ground-based interferometric radar (GBIR) and terrestrial laser scanning (TLS) were used to image possible surface deformations associated with Lone Star Geyer's eruption cycles. Additional observations were provided by global positioning system (GPS) measurements and six broad-band seismometers deployed in the immediate vicinity of the geyser. The GBIR and TLS were deployed approximately 65 meters from the sinter cone of the geyser. The GBIR involves a ku-band radar (1.7 cm wavelength) that is sensitive to approximately half-millimeter changes in the line-of-sight distance. Radar images were acquired every minute for 3 or more eruptions per day. Temporally redundant, overlapping interferograms were used to improve the sensitivity and interpolate a minute-wise time series of line-of-sight displacement, and efforts were made to account for possible path-delay effects resulting from water vapor around the geyser cone. Repeat (every minute) high-speed TLS scans were acquired for multiple eruption cycles over the course of two-days. Resulting measurement point spacing on the sinter cone was ~3cm. The TLS point-clouds were geo-referenced using static surveyed reflectors and scanner positions. In addition to measuring ground deformation, filtering and classification of the TLS point cloud was used to construct a mask that allows radar interferometry to exclude non-ground areas (vegetation, snow, sensors

  15. Type III burst pair

    NASA Astrophysics Data System (ADS)

    Ning, Zongjun; Fu, Qijun; Lu, Quankang

    2000-05-01

    We present a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0-2.0 GHz) of the Beijing Astronomical Observatory (BAO). Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. We call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is a nice interpretation of type III burst pair since the plasma beta β~=0.01 is much less than 1 and the beams have velocity of about 1.07×10^8 cm s^-1 after leaving the reconnection region if we assume that the ambient magnetic field strength is about 100 G.

  16. Type III burst pair.

    NASA Astrophysics Data System (ADS)

    Zongjun, Ning; Fu, Qijun; Quankang, Lu

    2000-05-01

    Presents a special solar radio burst detected on 5 January 1994 using the multi-channel (50) spectrometer (1.0 - 2.0 GHz) of the Beijing Astronomical Observatory. Sadly, the whole event could not be recorded since it had a broader bandwidth than the limit range of the instrument. The important part was obtained, however. The event is composed of a normal drift type III burst on the lower frequency side and a reverse drift type III burst appearing almost simultaneously on the high side. The authors call the burst type III a burst pair. It is a typical characteristic of two type III bursts that they are morphologically symmetric about some frequency from 1.64 GHz to 1.78 GHz on the dynamic spectra records, which indicates that there are two different electron beams from the same acceleration region travelling simultaneously in opposite directions (upward and downward). A magnetic reconnection mode is an interpretation of type III burst pair.

  17. The B-H...H-P dihydrogen bonding in ion pair complexes [(CF(3))(3)BH(-)][HPH(3-n)(Me)(n)(+)] (n = 0-3) and its implication in H(2) elimination and activation reactions.

    PubMed

    Gao, Shulin; Wu, Wei; Mo, Yirong

    2009-07-16

    The B-H(delta-)...(delta+)H-P dihydrogen bonding (DHB) in ion pair complexes [(CF(3))(3)BH(-)][HPH(3-n)(Me)(n)(+)] (n = 0-3) and its role in the combination of proton and hydride with the release of H(2) or, reversibly, the heterolytic activation of H(2) by Lewis pairs (CF(3))(3)BPH(3-n)(Me)(n) have been theoretically investigated at the MP2 and DFT levels. It is found that the B-H...H-P bonds behave similarly to those in neutral pairs and ion-molecule complexes in most respects, such as the linearity of the H...H-P moiety, the characteristics of the electron transfer and rearrangement, and the topological properties of the DHB critical point, except that in certain cases, a blue-shifting of the H-bond vibrational frequency is observed. In [(CF(3))(3)BH(-)][HPH(3-n)(Me)(n)(+)], the proton shifting within the complexes leads to the formation of the dihydrogen complex B(CF(3))(3)(eta(2)-H(2)), which is followed by a subsequent H(2) release. The stability of B(CF(3))(3)(eta(2)-H(2)) (D(e)/D(0) = 10.8/6.0 kcal/mol) makes the proton-hydride combination proceed in a fashion similar to the protonation reactions in transition-metal hydrides rather than those in group 13 hydrides EH(4)(-) (E = B, Al, Ga). As for the H(2)-splitting reaction R(3)BPR'(3) + H(2) --> [R(3)BH(-)][HPR'(3)(+)], classical Lewis pair (CLP) (CF(3))(3)BPH(3) exhibits a high barrier and results in an unstable ion pair product [(CF(3))(3)BH(-)][HPH(3)(+)] compared with the "frustrated Lewis pair" (FLP) (C(6)F(5))(3)BP(tBu)(3). A detailed analysis of the mechanistic aspects of H(2) activation by (CF(3))(3)BPH(3) and (C(6)F(5))(3)BP(tBu)(3), supported by another CLP (CF(3))(3)BP(tBu)(3) which has a binding energy comparable to (CF(3))(3)BPH(3) but a reaction exothermicity comparable to (C(6)F(5))(3)BP(tBu)(3), allows us to suggest that the low stability of FLP (C(6)F(5))(3)BP(tBu)(3) is the determining factor for the low reaction barrier. The relative stability and other properties of the ion pair products

  18. Using Interviews and Peer Pairs to Better Understand How School Environments Affect Young Children's Playground Physical Activity Levels: A Qualitative Study

    ERIC Educational Resources Information Center

    Parrish, Anne-Maree; Yeatman, Heather; Iverson, Don; Russell, Ken

    2012-01-01

    School break times provide a daily opportunity for children to be active; however, research indicates this time is underutilized. Reasons for low children's playground activity levels have primarily focused on physical barriers. This research aimed to contribute to physical environmental findings affecting children's playground physical activity…

  19. Expression of bovine genes associated with a local and systemic immune response to infestation by the Lone Star tick, Amblyomma americanum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Lone Star tick, Amblyomma americanum, causes considerable production losses to the Southern U.S. cattle industry due to reduced weight, infertility, secondary infections at bite wounds, damaged hides, and potentially death, as these ticks tend to infest livestock in large numbers. Chemical resid...

  20. Formulations of Deet, Picaridin and IR3535 Applied to Skin Repel Nymphs of the Lone Star Tick (Acari: Ixodidae) for 12 Hours

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacies of a 20% 1-methyl-propyl-2-(hydroxyethyl)-1-piperidinecarboxylate (picaridin) spray, 20% 3-(N-acetyl-N-butyl)aminopropionic acid ethyl ester (IR3535) spray, 20% picaridin lotion, 10% IR3535 lotion, and 33% N,N-diethyl-3-methylbenzamide (deet) cream in repelling nymphal lone star ticks...

  1. Efficacy of amitraz-impregnated collars on white-tailed deer (Artiodactyla: Cervidae) in reducing free-living populations of lone star ticks (Acari: Ixodidae)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over a seven year period, we monitored the effect of a commercially available, amitraz impregnated anti-tick collar in controlling free-living populations of lone star ticks, Amblyomma americanum (L.) when manually fitted around necks of white-tailed deer, Odocoileus virginianus (Zimmermann). Study...

  2. Efficacy of amitraz-impregnated collars on white-tailed deer in reducing free-living populations of lone star ticks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Over a seven year period, we monitored the effect of a commercially available, amitraz impregnated anti-tick collar in controlling free-living populations of lone star ticks, Amblyomma americanum (L.) when manually fitted around the neck of white-tailed deer, Odocoileus virginianus (Zimmermann). St...

  3. Active chi-like sequences are present in the ITS1 region of polyembryonic adult Collyriclum faba trematodes encysted in pairs.

    PubMed

    Heneberg, Petr; Sitko, Jiljí; Bizos, Jiří; Kocková, Lucie; Malá, Milena; Literák, Ivan

    2014-09-01

    Collyriclum faba (Plagiochiida: Collyriclidae) adults occur in pairs within subcutaneous cysts. Here, we tested the extensive C. faba infrapopulation for five DNA loci known to display variability among Central European C. faba individuals. The infrapopulation tested shared 100% similarity in four of the five mitochondrial and nuclear DNA loci tested. Contrariwise, the internal transcribed spacer 1 (ITS1) loci in all but one individual differed from each other. We found only 0.0-1.5 base substitutions per 1,000 sites within the cysts, while we found 0.7-9.0 substitutions between the cysts of the single host and 3.0-9.0 substitutions when comparing C. faba individuals isolated from different host individuals. We observed the most of the ITS1 variability within 48 bp repetitive sequences featured by the chi-like sequence 5'-GCTTGTCTGCC-3' at their beginning. Similarly to the extensive C. faba infrapopulation examined, we determined the presence of highly variable number of repetitive sequences within the ITS1 locus of C. faba isolated from multiple host species and from various geographic locations. While similar variability was observed earlier in mutually unrelated specimens of several Schistosomatidae and Microphallidae species, here, we for the first time document it among multiple individuals of a single infracommunity possessing single mitochondrial haplotype. Lower ITS1 evolutionary divergence rates observed between individuals within the cysts when compared to those between the cysts suggest that the recombination occurs at multiple stages of the life cycle. We propose DNA recombination involving chi-like sequences to serve as a general feature shared by multiple families of digenetic trematodes to increase genetic diversity of their polyembryonic populations infecting their definitive hosts.

  4. The p21-activated kinase PAK is negatively regulated by POPX1 and POPX2, a pair of serine/threonine phosphatases of the PP2C family.

    PubMed

    Koh, Cheng-Gee; Tan, E-Jean; Manser, Edward; Lim, Louis

    2002-02-19

    The Rho GTPases are involved in many signaling pathways and cellular functions, including the organization of the actin cytoskeleton, regulation of transcription, cell motility, and cell division. The p21 (Cdc42/Rac)-activated kinase PAK mediates a number of biological effects downstream of these Rho GTPases (reviewed by [1]). The phosphorylation state of mammalian PAK is highly regulated: upon binding of GTPases, PAK is potently activated by autophosphorylation at multiple sites, although the mechanisms of PAK downregulation are not known. We now report two PP2C-like serine/threonine phosphatases (POPX1 and POPX2) that efficiently inactivate PAK. POPX1 was isolated as a binding partner for the PAK interacting guanine nucleotide exchange factor PIX. The dephosphorylating activity of POPX correlates with an ability to block the in vivo effects of active PAK. Consonant with these effects on PAK, POPX can also inhibit actin stress fiber breakdown and morphological changes driven by active Cdc42(V12). The association of the POPX phosphatases with PAK complexes may allow PAK to cycle rapidly between active and inactive states; it represents a unique regulatory component of the signaling pathways of the PAK kinase family.

  5. Analysis of the quality of hospital information systems in Isfahan teaching hospitals based on the DeLone and McLean model

    PubMed Central

    Saghaeiannejad-Isfahani, Sakineh; Saeedbakhsh, Saeed; Jahanbakhsh, Maryam; Habibi, Mahboobeh

    2015-01-01

    Background: Quality is one of the most important criteria for the success of an information system, which refers to its desirable features of the processing system itself. The aim of this study was the analysis of system quality of hospital information systems (HIS) in teaching hospitals of Isfahan based on the DeLone and McLean model. Materials and Methods: This research was an applied and analytical-descriptive study. It was performed in teaching hospitals of Isfahan in 2010. The research population consisted of the HIS's users, system designers and hospital information technology (IT) authorities who were selected by random sampling method from users’ group (n = 228), and system designers and IT authorities (n = 52) using census method. The data collection tool was two researcher-designed questionnaires. Questionnaires’ reliability was estimated by using Cronbach's alpha was calculated. It was 97.1% for the system designers and IT authorities’ questionnaire and 92.3% for system users’ questionnaire. Results: Findings showed that the mean of system quality score in a variety of HIS and among different hospitals was significantly different and not the same (P value ≥ 0.05). In general, Kosar (new version) system and Rahavard Rayaneh system have dedicated the highest and the lowest mean scores to themselves. The system quality criterion overall mean was 59.6% for different HIS and 57.5% among different hospitals respectively. Conclusion: According to the results of the research, it can be stated that based on the applied model, the investigated systems were relatively desirable in terms of quality. Thus, in order to achieve a good optimal condition, it is necessary to pay particular attention to the improving factors of system quality, type of activity, type of specialty and hospital ownership type. PMID:25767816

  6. Efficacy of amitraz applied to white-tailed deer by the '4-poster' topical treatment device in controlling free-living lone star ticks (Acari: Ixodidae).

    PubMed

    Pound, J M; Miller, J A; George, J E

    2000-11-01

    White-tailed deer treated themselves with a commercial pour-on acaricide formulation containing 2% amitraz as they fed from an ARS-patented '4-poster' topical treatment device. Whole kernel corn attracted deer to a single device placed in each of two deer-fenced pastures. In the treatment pasture, the rollers of the treatment device were charged with the acaricide, whereas the rollers of the device in the other pasture remained untreated. Deer were allowed to use the '4-posters' during periods of tick activity beginning in early to midspring and lasting through late summer to early fall for three consecutive years. Pretreatment sampling of adults and nymphs with dry-ice traps and larval masses with flip cloths showed no significant differences in population indices between the two pastures; however, after the third year of treatment, control of nymphal and adult ticks in the treated pasture was 91.9 and 93.7%, respectively, when compared with the untreated pasture. Control of larval masses increased from 68.4% in year 1 to 96.4% in year 2, but declined to 88.0% in year 3, probably because of the presence of feral hogs. This study demonstrated that application of amitraz to white-tailed deer through free-choice interaction with a '4-poster' device significantly reduced the abundance of free-living lone star ticks in a deer-fenced experimental pasture. Moreover, the yearly pattern of incremental increases in control and the final percentage control values for all three parasitic life stages in this topical application study were similar in magnitude to that observed in a previously conducted study in which the systemic acaricide ivermectin was used to reduce populations of free-living ticks by controlling ticks on deer.

  7. Comparison of flagging, walking, trapping, and collecting from hosts as sampling methods for northern deer ticks, Ixodes dammini, and lone-star ticks, Amblyomma americanum (Acari:Ixodidae).

    PubMed

    Ginsberg, H S; Ewing, C P

    1989-09-01

    Ticks were sampled by flagging, collecting from the investigator's clothing (walking samples), trapping with dry-ice bait, and collecting from mammal hosts on Fire Island, NY, U.S.A. The habitat distribution of adult deer ticks, Ixodes dammini, was the same in simultaneous collections from the investigator's clothing and from muslin flags. Walking and flagging samples can both be biased by differences between investigators, so the same person should do comparative samples whenever possible. Walking samples probably give a more accurate estimate than flagging samples of the human risk of encountering ticks. However, ticks (such as immature I. dammini) that seek hosts in leaf litter and ground-level vegetation are poorly sampled by walking collections. These ticks can be sampled by flagging at ground level. Dry-ice-baited tick-traps caught far more lone-star ticks, Amblyomma americanum, than deer ticks, even in areas where deer ticks predominated in flagging samples. In comparisons of tick mobility in the lab, nymphal A. americanum were more mobile than nymphal I. dammini in 84% of the trials. Therefore, the trapping bias may result from increased trap encounter due to more rapid movement by A. americanum, although greater attraction to carbon dioxide may also play a role. Tick traps are useful for intraspecific between-habitat comparisons. Early in their seasonal activity period, larval I. dammini were better represented in collections from mouse hosts than in flagging samples. Apparently, sampling from favored hosts can detect ticks at low population levels, but often cannot be used to get accurate estimates of pathogen prevalence in questing ticks.

  8. Feasibility of Pairing Behavioral Activation With Exercise for Women With Type 2 Diabetes and Depression: The Get It Study Pilot Randomized Controlled Trial

    PubMed Central

    Schneider, Kristin L.; Panza, Emily; Handschin, Barbara; Ma, Yunsheng; Busch, Andrew M.; Waring, Molly E.; Appelhans, Bradley M.; Whited, Matthew C.; Keeney, Jacey; Kern, Daniel; Blendea, Mihaela; Ockene, Ira; Pagoto, Sherry L.

    2016-01-01

    Major depressive disorder is often comorbid with diabetes and associated with worse glycemic control. Exercise improves glycemic control and depression, and thus could be a parsimonious intervention for patients with comorbid diabetes and major depression. Because patients with diabetes and comorbid depression are often sedentary and lack motivation to exercise, we developed a group exercise intervention that integrates strategies from behavioral activation therapy for depression to increase motivation for and enjoyment of exercise. We conducted a 6-month pilot randomized controlled trial to test the feasibility of the behavioral activation exercise intervention (EX) for women with diabetes and depression. Of the 715 individuals who contacted us about the study, 29 participants were randomized to the EX condition or an enhanced usual care condition (EUC), which represents 4.1% of participants who initially contacted us. Inclusion criteria made recruitment challenging and limits the feasibility of recruiting women with diabetes and depression for a larger trial of the intervention. Retention was 96.5% and 86.2% at 3 and 6 months. Participants reported high treatment acceptability; use of behavioral activation strategies and exercise class attendance was acceptable. No condition differences were observed for glycemic control, depressive symptoms, and physical activity, though depressive symptoms and self-reported physical activity improved over time. Compared to participants in the EUC condition, participants in the EX condition reported greater exercise enjoyment and no increase in avoidance behavior over time. Using behavioral activation strategies to increase exercise is feasible in a group exercise setting. However, whether these strategies can be delivered in a less intensive manner to a broader population of sedentary adults, for greater initiation and maintenance of physical activity, deserves further study. PMID:26956652

  9. Feasibility of Pairing Behavioral Activation With Exercise for Women With Type 2 Diabetes and Depression: The Get It Study Pilot Randomized Controlled Trial.

    PubMed

    Schneider, Kristin L; Panza, Emily; Handschin, Barbara; Ma, Yunsheng; Busch, Andrew M; Waring, Molly E; Appelhans, Bradley M; Whited, Matthew C; Keeney, Jacey; Kern, Daniel; Blendea, Mihaela; Ockene, Ira; Pagoto, Sherry L

    2016-03-01

    Major depressive disorder is often comorbid with diabetes and associated with worse glycemic control. Exercise improves glycemic control and depression, and thus could be a parsimonious intervention for patients with comorbid diabetes and major depression. Because patients with diabetes and comorbid depression are often sedentary and lack motivation to exercise, we developed a group exercise intervention that integrates strategies from behavioral activation therapy for depression to increase motivation for and enjoyment of exercise. We conducted a 6-month pilot randomized controlled trial to test the feasibility of the behavioral activation exercise intervention (EX) for women with diabetes and depression. Of the 715 individuals who contacted us about the study, 29 participants were randomized to the EX condition or an enhanced usual care condition (EUC), which represents 4.1% of participants who initially contacted us. Inclusion criteria made recruitment challenging and limits the feasibility of recruiting women with diabetes and depression for a larger trial of the intervention. Retention was 96.5% and 86.2% at 3 and 6months. Participants reported high treatment acceptability; use of behavioral activation strategies and exercise class attendance was acceptable. No condition differences were observed for glycemic control, depressive symptoms, and physical activity, though depressive symptoms and self-reported physical activity improved over time. Compared to participants in the EUC condition, participants in the EX condition reported greater exercise enjoyment and no increase in avoidance behavior over time. Using behavioral activation strategies to increase exercise is feasible in a group exercise setting. However, whether these strategies can be delivered in a less intensive manner to a broader population of sedentary adults, for greater initiation and maintenance of physical activity, deserves further study.

  10. Multiprocessor switch with selective pairing

    DOEpatents

    Gara, Alan; Gschwind, Michael K; Salapura, Valentina

    2014-03-11

    System, method and computer program product for a multiprocessing system to offer selective pairing of processor cores for increased processing reliability. A selective pairing facility is provided that selectively connects, i.e., pairs, multiple microprocessor or processor cores to provide one highly reliable thread (or thread group). Each paired microprocessor or processor cores that provide one highly reliable thread for high-reliability connect with a system components such as a memory "nest" (or memory hierarchy), an optional system controller, and optional interrupt controller, optional I/O or peripheral devices, etc. The memory nest is attached to a selective pairing facility via a switch or a bus

  11. Twenty-one-base-pair insertion polymorphism creates an enhancer element and potentiates SLC6A1 GABA transporter promoter activity

    PubMed Central

    Hirunsatit, Rungnapa; George, Elizabeth D.; Lipska, Barbara K.; Elwafi, Hani M.; Sander, Lisa; Yrigollen, Carolyn M.; Gelernter, Joel; Grigorenko, Elena L.; Lappalainen, Jaakko; Mane, Shrikant; Nairn, Angus C.; Kleinman, Joel E.; Simen, Arthur A.

    2009-01-01

    Objective Sodium-dependent and chloride-dependent γ-aminobutyric acid (GABA) transporter 1 (SLC6A1) is the target of a number of drugs of clinical importance and is a major determinant of synaptic GABA concentrations. We resequenced the human SLC6A1 gene previously and discovered a novel 21 bp insertion in the predicted promoter region that creates a second tandem copy of the sequence. Here we sought to determine the functional relevance of this variation. Methods We used reporter assays, mobility shift assays, quantitative PCR, and proteomics methods as well as postmortem expression analysis for this work. Results Reporter assays showed that the insertion allele significantly increases promoter activity in multiple cell lines. The zinc finger transcription factor ZNF148 was found to significantly transactivate the promoter and increase expression when overexpressed but could not account for the differences in activity between the two alleles of the promoter. Copy number of the insertion sequence was associated with exponentially increasing activity of a downstream promoter, suggesting that the insertion sequence has enhancer activity when present in multiple copies. SLC6A1 promoter genotype was found to predict SLC6A1 RNA expression in human postmortem hippocampal samples. These results suggest that the insertion polymorphism leads to increased SLC6A1 promoter activity because, in part, of creation of an enhancer element when present as multiple copies. Genotyping individuals from Tanzania in this study suggested that the insertion allele has its origin in Africa. Conclusion On account of the effect of the insertion on promoter activity, this relatively common polymorphism may prove useful in predicting clinical response to pharmacological modulators of SLC6A1 as well as GABAergic function in individuals of African descent. PMID:19077666

  12. Coupling of Activity at Neighbouring Volcanoes in Iceland: Ground Deformation and Activity at the Bárðarbunga-Tungnafellsjökull and Eyjafjallajökull-Katla Volcano Pairs

    NASA Astrophysics Data System (ADS)

    Parks, M.; Heimisson, E. R.; Sigmundsson, F.; Hooper, A. J.; Ofeigsson, B.; Vogfjord, K. S.; Arnadottir, T.; Dumont, S.; Drouin, V.; Bagnardi, M.; Spaans, K.; Hreinsdottir, S.; Friðriksdóttir, H. M.; Jonsdottir, K.; Guðmundsson, G.; Hensch, M.; Hjaltadottir, S.; Hjartardottir, A. R.; Einarsson, P.; Gudmundsson, M. T.; Hognadottir, T.; Lafemina, P.; Geirsson, H.; Sturkell, E.; Magnússon, E.

    2015-12-01

    Interferometric Synthetic Aperture Radar (InSAR) techniques are used to generate a time series of high-resolution deformation measurements, in the vicinity of two pairs of closely spaced volcanoes in Iceland: Bárðarbunga and Tungnafellsjökull, as well as Eyjafjallajökull and Katla. Following the declaration of Icelandic Volcanoes as a Permanent Geohazard Supersite in 2013, a considerable amount of SAR data was made available for both past and future satellite acquisitions, including new X-band images and historic C-band images. InSAR time series have been formed using these data and compared to other geodetic and microseismic measurements to determine the most likely processes responsible for recently observed deformation and/or seismicity. A comprehensive network of seismometers and continuous GPS stations are already deployed at these volcanoes and a series of campaign GPS measurements have been undertaken since 2010. We present an overview of the temporal variation in InSAR observations and these complementary field based measurements at Bárðarbunga and Tungnafellsjökull from 2014-2015 (covering the recent eruption at Holuhraun and contemporaneous slow collapse of the Bárðarbunga caldera), and Eyjafjallajökull and Katla volcanoes from 2010 onwards, after the 2010 explosive eruption of Eyjafjallajökull. We undertake a joint InSAR-GPS inversion using a Markov-chain Monte Carlo approach. The best-fit source geometries responsible for both the inflation of a 50 km long dyke and simultaneous deflation of the Bárðarbunga central volcano during the 2014-2015 unrest and eruption are found. Using these we calculate the stress changes associated with the Bárðarbunga deformation events and compare our results to the location of earthquake swarms in the vicinity of neighbouring Tungnafellsjökull, where seismic activity increased significantly following the onset of unrest at Bárðarbunga in August 2014. We also determine the optimal source parameters for

  13. Stereo Pair, Pasadena, California

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This stereoscopic image pair is a perspective view that shows the western part of the city of Pasadena, California, looking north toward the San Gabriel Mountains. Portions of the cities of Altadena and La Canada Flintridge are also shown. The cluster of large buildings left of center, at the base of the mountains, is the Jet Propulsion Laboratory. This image shows the power of combining data from different sources to create planning tools to study problems that affect large urban areas. In addition to the well-known earthquake hazards, Southern California is affected by a natural cycle of fire and mudflows. Data shown in this image can be used to predict both how wildfires spread over the terrain and how mudflows are channeled down the canyons.

    The image was created from three datasets: the Shuttle Radar Topography Mission (SRTM) supplied the elevation, U. S. Geological Survey digital aerial photography provided the image detail, and the Landsat Thematic Mapper provided the color. The United States Geological Survey's Earth Resources Observations Systems (EROS) Data Center, Sioux Falls, South Dakota, provided the Landsat data and the aerial photography. The image can be viewed in 3-D by viewing the left image with the right eye and the right image with the left eye (cross-eyed viewing), or by downloading and printing the image pair, and viewing them with a stereoscope.

    The Shuttle Radar Topography Mission (SRTM), launched on February 11, 2000, used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. The mission was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, an additional C-band imaging antenna and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration

  14. Two synthetic Sp1-binding sites functionally substitute for the 21-base-pair repeat region to activate simian virus 40 growth in CV-1 cells.

    PubMed Central

    Lednicky, J; Folk, W R

    1992-01-01

    The 21-bp repeat region of simian virus 40 (SV40) activates viral transcription and DNA replication and contains binding sites for many cellular proteins, including Sp1, LSF, ETF, Ap2, Ap4, GT-1B, H16, and p53, and for the SV40 large tumor antigen. We have attempted to reduce the complexity of this region while maintaining its growth-promoting capacity. Deletion of the 21-bp repeat region from the SV40 genome delays the expression of viral early proteins and DNA replication and reduces virus production in CV-1 cells. Replacement of the 21-bp repeat region with two copies of DNA sequence motifs bound with high affinities by Sp1 promotes SV40 growth in CV-1 cells to nearly wild-type levels, but substitution by motifs bound less avidly by Sp1 or bound by other activator proteins does not restore growth. This indicates that Sp1 or a protein with similar sequence specificity is primarily responsible for the function of the 21-bp repeat region. We speculate about how Sp1 activates both SV40 transcription and DNA replication. Images PMID:1328672

  15. Pygmy stars: first pair.

    PubMed

    Zwicky, F

    1966-07-01

    The binary LP 101-15/16 having the proper motion of 1.62 seconds of arc per year has been studied with the prime-focus spectrograph of the 200-inch (508 cm) telescope. Indications are that LP 101-15/16 is the first pair of pygmy stars ever discovered. One of its components, LP 101-16, is probably a blue pygmy star which is at least four magnitudes fainter than the ordinary white dwarfs. Also, two of the Balmer lines in absorption appear to be displaced toward the red by amounts which indicate the existence of an Einstein gravitational red shift corresponding to about 1000 km sec-1. On the other hand LP 101-15 is red and shows an entirely new type of spectrum, which suggests that it may be a first representative of a type of red pygmy star which is 2.5 magnitudes fainter than the M-type dwarf stars of the main sequence.

  16. One base pair change abolishes the T cell-restricted activity of a kB-like proto-enhancer element from the interleukin 2 promoter.

    PubMed Central

    Briegel, K; Hentsch, B; Pfeuffer, I; Serfling, E

    1991-01-01

    The inducible, T cell-specific enhancers of murine and human Interleukin 2 (Il-2) genes contain the kB-like sequence GGGATTTCACC as an essential cis-acting enhancer motif. When cloned in multiple copies this so-called TCEd (distal T cell element) acts as an inducible proto-enhancer element in E14 T lymphoma cells, but not in HeLa cells. In extracts of induced, Il-2 secreting El4 cells three individual protein factors bind to TCEd DNA. The binding of the most prominent factor, named TCF-1 (T cell factor 1), is correlated with the proto-enhancer activity of TCEd. TCF-1 consists of two polypeptides of about 50 kD and 105 kD; the former seems to be related to the 50 kD polypeptide of NF-kB. Purified NF-kB is also able to bind to the TCEd, but TCF-1 binds stronger than NF-kB to TCEd DNA. The conversion of the TCEd to a 'perfect' NF-kB binding site leads to a tighter binding of NF-kB to TCEd DNA and, as a functional consequence, to the activity of the 'converted' TCEd motifs in HeLa cells. Thus, the substitution of the underlined A residue to a C within the GGGATTTCACC motif abolishes its T cell-restricted activity and leads to its functioning in both El4 cells and HeLa cells. These results indicate that lymphocyte-specific factors binding to the TCEd are involved in the control of T cell specific-transcription of the Il-2 gene. Images PMID:1945879

  17. The Penrose photoproduction scenario for NGC 4151: A black hole gamma-ray emission mechanism for active galactic nuclei and Seyfert galaxies. [Compton scattering and pair production

    NASA Technical Reports Server (NTRS)

    Leiter, D.

    1979-01-01

    A consistent theoretical interpretation is given for the suggestion that a steepening of the spectrum between X-ray and gamma ray energies may be a general, gamma-ray characteristic of Seyfert galaxies, if the diffuse gamma ray spectrum is considered to be a superposition of unresolved contributions, from one or more classes of extragalactic objects. In the case of NGC 4151, the dominant process is shown to be Penrose Compton scattering in the ergosphere of a Kerr black hole, assumed to exist in the Seyfert's active galactic nucleus.

  18. The 'pair of sugar tongs' site on the non-catalytic domain C of barley alpha-amylase participates in substrate binding and activity.

    PubMed

    Bozonnet, Sophie; Jensen, Morten T; Nielsen, Morten M; Aghajari, Nushin; Jensen, Malene H; Kramhøft, Birte; Willemoës, Martin; Tranier, Samuel; Haser, Richard; Svensson, Birte

    2007-10-01

    Some starch-degrading enzymes accommodate carbohydrates at sites situated at a certain distance from the active site. In the crystal structure of barley alpha-amylase 1, oligosaccharide is thus bound to the 'sugar tongs' site. This site on the non-catalytic domain C in the C-terminal part of the molecule contains a key residue, Tyr380, which has numerous contacts with the oligosaccharide. The mutant enzymes Y380A and Y380M failed to bind to beta-cyclodextrin-Sepharose, a starch-mimic resin used for alpha-amylase affinity purification. The K(d) for beta-cyclodextrin binding to Y380A and Y380M was 1.4 mm compared to 0.20-0.25 mm for the wild-type, S378P and S378T enzymes. The substitution in the S378P enzyme mimics Pro376 in the barley alpha-amylase 2 isozyme, which in spite of its conserved Tyr378 did not bind oligosaccharide at the 'sugar tongs' in the structure. Crystal structures of both wild-type and S378P enzymes, but not the Y380A enzyme, showed binding of the pseudotetrasaccharide acarbose at the 'sugar tongs' site. The 'sugar tongs' site also contributed importantly to the adsorption to starch granules, as Kd = 0.47 mg.mL(-1) for the wild-type enzyme increased to 5.9 mg.mL(-1) for Y380A, which moreover catalyzed the release of soluble oligosaccharides from starch granules with only 10% of the wild-type activity. beta-cyclodextrin both inhibited binding to and suppressed activity on starch granules for wild-type and S378P enzymes, but did not affect these properties of Y380A, reflecting the functional role of Tyr380. In addition, the Y380A enzyme hydrolyzed amylose with reduced multiple attack, emphasizing that the 'sugar tongs' participates in multivalent binding of polysaccharide substrates.

  19. Can associative information be strategically separated from item information in word-pair recognition?

    PubMed

    Jou, Jerwen

    2010-12-01

    Subjects learned word pairs either once or three times but were instructed to ignore the association of the two words in each pair and only to memorize the individual words at study and recognize them at test. The test word pairs included intact pairs, rearranged pairs made up of old words exchanged among the studied pairs, and new pairs consisting of one old and one new word. Subjects were instructed to respond yes to both intact and rearranged pairs and no to new pairs. Results showed that the rearranged test pairs, as compared with intact pairs, produced longer reaction times, lower discrimination (d'), and lower remember judgments. In addition, more learning either did not reduce or actually increased the pairing effect. These results are difficult to reconcile with the notion that associative information is retrieved in a slow, controlled, and effortful process but are consistent with the encoding specificity principle and the global activation theory of recognition.

  20. SDSS DR2 Merging pairs

    NASA Astrophysics Data System (ADS)

    Allam, S. S.; Tucker, D. L.; SDSS Collaboration

    2004-05-01

    We present and analyze a catalog of 9,000 Merging pairs candidates to g=21 from the imaging data of the Sloan Digital Sky Survey (SDSS) Second Data Release (DR2). Candidates were selected using an automated algorithm (Allam et al. 2004) that is efficient in its selection of galaxy pairs. We highlight possible science applications of such a large photometric sample of merging pais and discuss future improvements, including incorporating magnitudes and pushing to higher redshifts and fainter pairs.

  1. Controversies in kidney paired donation.

    PubMed

    Gentry, Sommer E; Montgomery, Robert A; Segev, Dorry L

    2012-07-01

    Kidney paired donation represented 10% of living kidney donation in the United States in 2011. National registries around the world and several separate registries in the United States arrange paired donations, although with significant variations in their practices. Concerns about ethical considerations, clinical advisability, and the quantitative effectiveness of these approaches in paired donation result in these variations. For instance, although donor travel can be burdensome and might discourage paired donation, it was nearly universal until convincing analysis showed that living donor kidneys can sustain many hours of cold ischemia time without adverse consequences. Opinions also differ about whether the last donor in a chain of paired donation transplants initiated by a nondirected donor should donate immediately to someone on the deceased donor wait-list (a domino or closed chain) or should be asked to wait some length of time and donate to start another sequence of paired donations later (an open chain); some argue that asking the donor to donate later may be coercive, and others focus on balancing the probability that the waiting donor withdraws versus the number of additional transplants if the chain can be continued. Other controversies in paired donation include simultaneous versus nonsimultaneous donor operations, whether to enroll compatible pairs, and interactions with desensitization protocols. Efforts to expand public awareness of and participation in paired donation are needed to generate more transplant opportunities.

  2. Health Monitoring for Reliability Testing of Metallic Sandwich Panels Using Integrated Active Sensing with Dual Actuator-Sensor Pairs and the Method of Virtual Forces to Identify Damage

    NASA Astrophysics Data System (ADS)

    Ellmer, Claudia; Adams, Douglas E.; White, Jonathan R.; Jata, Kumar

    2008-02-01

    A vibration-based health monitoring technique is implemented to detect simulated damage in a sandwich metallic honeycomb under combined acoustic and thermal loading. Two types of damage are introduced into a gamma titanium aluminide panel; simulated oxidation damage in the form of a local mass addition and simulated bolt damage with a change in bolt torque. An active sensing approach is used to measure frequency response functions between a piezo-stack actuator with force measurement and high-frequency accelerometers. The measured frequency response function matrix is then used to estimate the virtual force due to damage. Temperatures up to 300 °F and sound pressures up to 110 dB are considered. It is shown that the measurement of damage changes with combined loading. For example, temperature changes cause bolt damage to be more apparent in the virtual force due to the effects of temperature on the attachment boundary conditions and to the temperature gradient across the panel causing global bending. Similarly, acoustic loading is shown to enhance the detection of simulated mass damage due to larger motions produced on the panel.

  3. Type 2 Active Galactic Nuclei with Double-Peaked [O III] Lines: Narrow-Line Region Kinematics or Merging Supermassive Black Hole Pairs?

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Shen, Yue; Strauss, Michael A.; Greene, Jenny E.

    2010-01-01

    We present a sample of 167 type 2 active galactic nuclei (AGNs) with double-peaked [O III] λλ4959,5007 narrow emission lines, selected from the Seventh Data Release of the Sloan Digital Sky Survey. The double-peaked profiles can be well modeled by two velocity components, blueshifted and redshifted from the systemic velocity. Half of these objects have a more prominent redshifted component. In cases where the Hβ emission line is strong, it also shows two velocity components whose line-of-sight (LOS) velocity offsets are consistent with those of [O III]. The relative LOS velocity offset between the two components is typically a few hundred km s-1, larger by a factor of ~1.5 than the line full width at half maximum of each component. The offset correlates with the host stellar velocity dispersion σ*. The host galaxies of this sample show systematically larger σ*, stellar masses, and concentrations, and older luminosity-weighted mean stellar ages than a regular type 2 AGN sample matched in redshift, [O III] λ5007 equivalent width, and luminosity; they show no significant difference in radio properties. These double-peaked features could be due to narrow-line region kinematics, or binary black holes. The statistical properties do not show strong preference for or against either scenario, and spatially resolved optical imaging, spectroscopy, radio or X-ray follow-up are needed to draw firm conclusions.

  4. Non-random pairing of CD46 isoforms with skewing towards BC2 and C2 in activated and memory/effector T cells

    PubMed Central

    Hansen, Aida S.; Bundgaard, Bettina B.; Møller, Bjarne K.; Höllsberg, Per

    2016-01-01

    CD46 is a glycoprotein with important functions in innate and adaptive immune responses. Functionally different isoforms are generated by alternative splicing at exons 7–9 (BC and C isoforms) and exon 13 (CYT-1 and CYT-2 isoforms) giving rise to BC1, BC2, C1 and C2. We developed a novel real-time PCR assay that allows quantitative comparisons between these isoforms. Their relative frequency in CD4+ T cells from 100 donors revealed a distribution with high interpersonally variability. Importantly, the distribution between the isoforms was not random and although splicing favoured inclusion of exon 8 (BC isoforms), exclusion of exon 8 (C isoforms) was significantly linked to exclusion of exon 13 (CYT-2 isoforms). Despite inter-individual differences, CD4+ and CD8+ T cells, B cells, NK cells and monocytes expressed similar isoform profiles intra-individually. However, memory/effector CD4+ T cells had a significantly higher frequency of CYT-2 when compared with naïve CD4+ T cells. Likewise, in vitro activation of naïve and total CD4+ T cells increased the expression of CYT-2. This indicates that although splicing factors determine a certain expression profile in an individual, the profile can be modulated by external stimuli. This suggests a mechanism by which alterations in CD46 isoforms may temporarily regulate the immune response. PMID:27739531

  5. Correlating size and composition-dependent effects with magnetic, Mössbauer, and pair distribution function measurements in a family of catalytically active ferrite nanoparticles

    DOE PAGES

    Wong, Stanislaus; Papaefthymiou, Georgia C.; Lewis, Crystal S.; ...

    2015-05-06

    The magnetic spinel ferrites, MFe₂O₄ (wherein 'M' = a divalent metal ion such as but not limited to Mn, Co, Zn, and Ni), represent a unique class of magnetic materials in which the rational introduction of different 'M's can yield correspondingly unique and interesting magnetic behaviors. Herein we present a generalized hydrothermal method for the synthesis of single-crystalline ferrite nanoparticles with 'M' = Mg, Fe, Co, Ni, Cu, and Zn, respectively, which can be systematically and efficaciously produced simply by changing the metal precursor. Our protocol can moreover lead to reproducible size control by judicious selection of various surfactants. Asmore » such, we have probed the effects of both (i) size and (ii) chemical composition upon the magnetic properties of these nanomaterials using complementary magnetometry and Mössbauer spectroscopy techniques. The structure of the samples was confirmed by atomic PDF analysis of X-ray and electron powder diffraction data as a function of particle size. These materials retain the bulk spinel structure to the smallest size (i.e., 3 nm). In addition, we have explored the catalytic potential of our ferrites as both (a) magnetically recoverable photocatalysts and (b) biological catalysts, and noted that many of our as-prepared ferrite systems evinced intrinsically higher activities as compared with their iron oxide analogues.« less

  6. Correlating size and composition-dependent effects with magnetic, Mössbauer, and pair distribution function measurements in a family of catalytically active ferrite nanoparticles

    SciTech Connect

    Wong, Stanislaus; Papaefthymiou, Georgia C.; Lewis, Crystal S.; Han, Jinkyu; Zhang, Cheng; Li, Qiang; Shi, Chenyang; Abeykoon, A. M.Milinda; Billinge, Simon J.L.; Stach, Eric; Thomas, Justin; Guerrero, Kevin; Munayco, Pablo; Munayco, Jimmy; Scorzelli, Rosa B.; Burnham, Philip; Viescas, Arthur J; Tiano, Amanda L.

    2015-05-06

    The magnetic spinel ferrites, MFe₂O₄ (wherein 'M' = a divalent metal ion such as but not limited to Mn, Co, Zn, and Ni), represent a unique class of magnetic materials in which the rational introduction of different 'M's can yield correspondingly unique and interesting magnetic behaviors. Herein we present a generalized hydrothermal method for the synthesis of single-crystalline ferrite nanoparticles with 'M' = Mg, Fe, Co, Ni, Cu, and Zn, respectively, which can be systematically and efficaciously produced simply by changing the metal precursor. Our protocol can moreover lead to reproducible size control by judicious selection of various surfactants. As such, we have probed the effects of both (i) size and (ii) chemical composition upon the magnetic properties of these nanomaterials using complementary magnetometry and Mössbauer spectroscopy techniques. The structure of the samples was confirmed by atomic PDF analysis of X-ray and electron powder diffraction data as a function of particle size. These materials retain the bulk spinel structure to the smallest size (i.e., 3 nm). In addition, we have explored the catalytic potential of our ferrites as both (a) magnetically recoverable photocatalysts and (b) biological catalysts, and noted that many of our as-prepared ferrite systems evinced intrinsically higher activities as compared with their iron oxide analogues.

  7. Highly sensitive detection of caspase-3 activities via a nonconjugated gold nanoparticle-quantum dot pair mediated by an inner-filter effect.

    PubMed

    Li, Jingwen; Li, Xinming; Shi, Xiujuan; He, Xuewen; Wei, Wei; Ma, Nan; Chen, Hong

    2013-10-09

    We describe here a simple fluorometric assay for the highly sensitive detection of caspase-3 activities on the basis of the inner-filter effect of gold nanoparticles (AuNPs) on CdTe quantum dots (QDs). The method takes advantage of the high molar absorptivity of the plasmon band of gold nanoparticles as well as the large absorption band shift from 520 to 680 nm upon nanoparticle aggregation. When labeled with a peptide possessing the caspase-3 cleavage sequence (DEVD), the monodispersed Au-Ps (peptide-modified AuNPs) exhibited a tendency to aggregate when exposed to caspase-3, which induced the absorption band transition from 520 to 680 nm and turned on the fluorescence of the CdTe QDs for caspase-3 sensing. Under optimum conditions, a high sensitivity towards caspase-3 was achieved with a detection limit as low as 18 pM, which was much lower than the corresponding assays based on absorbance or other approaches. Overall, we demonstrated a facile and sensitive approach for caspase-3 detection, and we expected that this method could be potentially generalized to design more fluorescent assays for sensing other bioactive entities.

  8. Electronic pairing in exotic superconductors

    SciTech Connect

    Cox, D.L. ); Maple, M.B. )

    1995-02-01

    Superconductivity in heavy-fermion materials and high T[sub c] cuprates may involve electronic pairing with unconventional symmetries and mechanisms. Although there has been no smoking-gun proof, numerous pieces of circumstantial evidence combined with heuristic theoretical arguments make a compelling case that these materials have pairs with exotic symmetry bound by nonphonon glue. 20 refs., 5 figs.

  9. Homologous pairing and the role of pairing centers in meiosis.

    PubMed

    Tsai, Jui-He; McKee, Bruce D

    2011-06-15

    Homologous pairing establishes the foundation for accurate reductional segregation during meiosis I in sexual organisms. This Commentary summarizes recent progress in our understanding of homologous pairing in meiosis, and will focus on the characteristics and mechanisms of specialized chromosome sites, called pairing centers (PCs), in Caenorhabditis elegans and Drosophila melanogaster. In C. elegans, each chromosome contains a single PC that stabilizes chromosome pairing and initiates synapsis of homologous chromosomes. Specific zinc-finger proteins recruited to PCs link chromosomes to nuclear envelope proteins--and through them to the microtubule cytoskeleton--thereby stimulating chromosome movements in early prophase, which are thought to be important for homolog sorting. This mechanism appears to be a variant of the 'telomere bouquet' process, in which telomeres cluster on the nuclear envelope, connect chromosomes through nuclear envelope proteins to the cytoskeleton and lead chromosome movements that promote homologous synapsis. In Drosophila males, which undergo meiosis without recombination, pairing of the largely non-homologous X and Y chromosomes occurs at specific repetitive sequences in the ribosomal DNA. Although no other clear examples of PC-based pairing mechanisms have been described, there is evidence for special roles of telomeres and centromeres in aspects of chromosome pairing, synapsis and segregation; these roles are in some cases similar to those of PCs.

  10. Stereo Pair: Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    This view of northern Patagonia, near El Cain, Argentina shows complexly eroded volcanic terrain, with basalt mesas, sinkholes, landslide debris, playas, and relatively few integrated drainage channels. Surrounding this site (but also extending far to the east) is a broad plateau capped by basalt, the Meseta de Somuncura. Here, near the western edge of the plateau, erosion has broken through the basalt cap in a variety of ways. On the mesas, water-filled sinkholes (lower left) are most likely the result of the collapse of old lava tubes. Along the edges of the mesas (several locations) the basalt seems to be sliding away from the plateau in a series of slices. Water erosion by overland flow is also evident, particularly in canyons where vegetation blankets the drainage channels (green patterns, bottom of image). However, overland water flow does not extend very far at any location. This entire site drains to local playas, some of which are seen here (blue). While the water can reach the playas and then evaporate, what becomes of the eroded rock debris? Wind might excavate some of the finer eroded debris, but the fate of much of the missing bedrock remains mysterious.

    This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7 satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The

  11. Modeling the present and future geographic distribution of the Lone star tick, Amblyomma americanum (Ixodida: Ixodidae), in the continental United States

    USGS Publications Warehouse

    Springer, Yuri P; Jarnevich, Catherine S.; Barnett, David T.; Monaghan, Andrew J.; Eisen, Rebecca J

    2015-01-01

    The Lone star tick (Amblyomma americanum L.) is the primary vector for pathogens of significant public health importance in North America, yet relatively little is known about its current and potential future distribution. Building on a published summary of tick collection records, we used an ensemble modeling approach to predict the present-day and future distribution of climatically suitable habitat for establishment of the Lone star tick within the continental United States. Of the nine climatic predictor variables included in our five present-day models, average vapor pressure in July was by far the most important determinant of suitable habitat. The present-day ensemble model predicted an essentially contiguous distribution of suitable habitat extending to the Atlantic coast east of the 100th western meridian and south of the 40th northern parallel, but excluding a high elevation region associated with the Appalachian Mountains. Future ensemble predictions for 2061–2080 forecasted a stable western range limit, northward expansion of suitable habitat into the Upper Midwest and western Pennsylvania, and range contraction along portions of the Gulf coast and the lower Mississippi river valley. These findings are informative for raising awareness of A. americanum-transmitted pathogens in areas where the Lone Star tick has recently or may become established.

  12. United States Air Force 611th Air Support Group/Civil Engineering Squadron, Elmendorf AFB, Alaska. Risk assessment Point Lonely Radar Installation, Alaska. Final report

    SciTech Connect

    Karmi, S.

    1996-04-01

    This document contains the baseline human health risk assessment and the ecological risk assessment (ERA) for the Point Lonely Distant Early Warning (DEW) Line radar installation. Twelve sites at the Point Lonely radar installation underwent remedial investigations (RIs) during the summer of 1993. The Vehicle Storage Area (SS14) was combined with the Inactive Landfill because the two sites were essentially co-located and were sampled during the RI as a single unit. Therefore, 11 sites are discussed in this risk assessment. The presence of chemical contamination in the soil, sediments, and surface water at the installation was evaluated and reported in the Point Lonely Remedial Investigation/Feasibility Study (RI/FS). The analytical data reported in the RI/FS form the basis for the human health and ecological risk assessments. The primary chemicals of concern (COCs) at the 11 sites are diesel and gasoline from past spills and/or leaks, chlorinated solvents, and manganese. The 11 sites investigated and the types of samples collected at each site are presented.

  13. Management of lone star ticks (Acari: Ixodidae) in recreational areas with acaricide applications, vegetative management, and exclusion of white-tailed deer.

    PubMed

    Bloemer, S R; Mount, G A; Morris, T A; Zimmerman, R H; Barnard, D R; Snoddy, E L

    1990-07-01

    A project on management of lone star ticks, Amblyomma americanum (L.), at Land Between the Lakes, a Tennessee Valley Authority recreational area in Kentucky-Tennessee, during 1984-1988, demonstrated the effectiveness and economics of three control technologies. Acaricide applications (chlorpyrifos at 0.28 kg [AI]/ha), vegetative management (mowing and removal of 40% overstory and 90-100% of midstory, understory, and leaf litter), and host management (white-tailed deer exclusion from a 71-ha campground with a single-line fence) provided 75, 70, and 64% mean controls of all life stages of the lone star tick, respectively. Combinations of acaricide applications + vegetative management, acaricide applications + host management, and acaricide applications + vegetative management + host management produced 94, 89, and 96% mean control of all life stages, respectively. The costs of acaricide applications (two per year), vegetative management (two mowings per year), and white-tailed deer exclusion (single-line fence) were $45, $150, and $30/ha/yr, respectively. Results of this project are used to design management strategies that could be considered for use against lone star ticks in recreational areas.

  14. Modeling the Present and Future Geographic Distribution of the Lone Star Tick, Amblyomma americanum (Ixodida: Ixodidae), in the Continental United States

    PubMed Central

    Springer, Yuri P.; Jarnevich, Catherine S.; Barnett, David T.; Monaghan, Andrew J.; Eisen, Rebecca J.

    2015-01-01

    The Lone star tick (Amblyomma americanum L.) is the primary vector for pathogens of significant public health importance in North America, yet relatively little is known about its current and potential future distribution. Building on a published summary of tick collection records, we used an ensemble modeling approach to predict the present-day and future distribution of climatically suitable habitat for establishment of the Lone star tick within the continental United States. Of the nine climatic predictor variables included in our five present-day models, average vapor pressure in July was by far the most important determinant of suitable habitat. The present-day ensemble model predicted an essentially contiguous distribution of suitable habitat extending to the Atlantic coast east of the 100th western meridian and south of the 40th northern parallel, but excluding a high elevation region associated with the Appalachian Mountains. Future ensemble predictions for 2061–2080 forecasted a stable western range limit, northward expansion of suitable habitat into the Upper Midwest and western Pennsylvania, and range contraction along portions of the Gulf coast and the lower Mississippi river valley. These findings are informative for raising awareness of A. americanum-transmitted pathogens in areas where the Lone Star tick has recently or may become established. PMID:26217042

  15. Examining the functionality of the DeLone and McLean information system success model as a framework for synthesis in nursing information and communication technology research.

    PubMed

    Booth, Richard G

    2012-06-01

    In this review, studies examining information and communication technology used by nurses in clinical practice were examined. Overall, a total of 39 studies were assessed spanning a time period from 1995 to 2008. The impacts of the various health information and communication technology evaluated by individual studies were synthesized using the DeLone and McLean's six-dimensional framework for evaluating information systems success (ie, System Quality, Information Quality, Service Quality, Use, User Satisfaction, and Net Benefits). Overall, the majority of researchers reported results related to the overall Net Benefits (positive, negative, and indifferent) of the health information and communication technology used by nurses. Attitudes and user satisfaction with technology were also commonly measured attributes. The current iteration of DeLone and McLean model is effective at synthesizing basic elements of health information and communication technology use by nurses. Regardless, the current model lacks the sociotechnical sensitivity to capture deeper nurse-technology relationalities. Limitations and recommendations are provided for researchers considering using the DeLone and McLean model for evaluating health information and communication technology used by nurses.

  16. Presence, genetic variability, and potential significance of "Candidatus Midichloria mitochondrii" in the lone star tick Amblyomma americanum.

    PubMed

    Williams-Newkirk, Amanda Jo; Rowe, Lori A; Mixson-Hayden, Tonya R; Dasch, Gregory A

    2012-11-01

    We used next generation sequencing to detect the bacterium "Candidatus Midichloria mitochondrii" for the first time in lone star ticks (Amblyomma americanum) from the eastern United States. 177 individuals and 11 tick pools from seven sites in four states were tested by pyrosequencing with barcoded 16S rRNA gene eubacterial primers targeting variable regions 5-3. Average infection prevalence was 0.15 across all surveyed populations (range 0-0.29) and only the site with the smallest sample size (n = 5) was negative. Three genotypes differing by 2.6-4.1 % in a 271 bp region of 16S rRNA gene were identified. Two variants co-occurred in sites in North Carolina and New York, but were not observed in the same tick at those sites. The third genotype was found only in Georgia. Phylogenetic analysis of this fragment indicated that the three variants are more closely related to "Candidatus Midichloria mitochondrii" genotypes from other tick species than to each other. This variation suggests that multiple independent introductions occurred in A. americanum which may provide insight into bacterial spread within its ecosystem and parasitism on this tick. Whether the presence of this bacterium affects acquisition or maintenance of other pathogens and symbionts in A. americanum or the survival, biology and evolution of the tick itself is unknown.

  17. Alder, Nitrogen, and Lake Ecology: Terrestrial-Aquatic Linkages in the Postglacial History of Lone Spruce Pond, Southwestern Alaska

    PubMed Central

    Axford, Yarrow; Kaufman, Darrell S.

    2017-01-01

    Diatoms, combined with a multiproxy study of lake sediments (organic matter, N, δ15N, δ13C, biogenic silica, grain size, Cladocera and chironomids, Alnus pollen) from Lone Spruce Pond, Alaska detail the late-glacial to Holocene history of the lake and its response to regional climate and landscape change over the last 14.5 cal ka BP. We show that the immigration of alder (Alnus viridis) in the early Holocene marks the rise of available reactive nitrogen (Nr) in the lake as well as the establishment of a primarily planktonic diatom community. The later establishment of diatom Discostella stelligera is coupled to a rise of sedimentary δ15N, indicating diminished competition for this nutrient. This terrestrial-aquatic linkage demonstrates how profoundly vegetation may affect soil geochemistry, lake development, and lake ecology over millennial timescales. Furthermore, the response of the diatom community to strengthened stratification and N levels in the past confirms the sensitivity of planktonic diatom communities to changing thermal and nutrient regimes. These past ecosystem dynamics serve as an analogue for the nature of threshold-type ecological responses to current climate change and atmospheric nitrogen (Nr) deposition, but also for the larger changes we should anticipate under future climate, pollution, and vegetation succession scenarios in high-latitude and high-elevation regions. PMID:28076393

  18. Evaluation of DEET and eight essential oils for repellency against nymphs of the lone star tick, Amblyomma americanum (Acari: Ixodidae).

    PubMed

    Meng, Hao; Li, Andrew Y; Costa Junior, Livio M; Castro-Arellano, Ivan; Liu, Jingze

    2016-02-01

    DEET and Eight commercially available essential oils (oregano, clove, thyme, vetiver, sandalwood, cinnamon, cedarwood, and peppermint) were evaluated for repellency against host-seeking nymphs of the lone star tick, Amblyomma americanum. Concentration-repellency response was established using the vertical paper bioassay technique for each essential oil and compared with that of N,N-diethyl-3-methyl benzamide (DEET), a standard repellent compound present in many commercial repellent formulations. The effective concentration of DEET that repels 50% of ticks (EC50) was estimated at 0.02 mg/cm(2), while EC50s of the essential oils fall between 0.113 and 0.297 mg/cm(2). Based on EC50 estimates, oregano essential oil was the most effective among all essential oils tested, followed by clove, thyme, vetiver, sandalwood, cinnamon, cedarwood, and peppermint oils. None of the tested essential oils demonstrated a level of tick repellency found with DEET. Results from this study illustrated the challenge in search for more effective natural tick repellents.

  19. Communication: Improved pair approximations in local coupled-cluster methods

    NASA Astrophysics Data System (ADS)

    Schwilk, Max; Usvyat, Denis; Werner, Hans-Joachim

    2015-03-01

    In local coupled cluster treatments the electron pairs can be classified according to the magnitude of their energy contributions or distances into strong, close, weak, and distant pairs. Different approximations are introduced for the latter three classes. In this communication, an improved simplified treatment of close and weak pairs is proposed, which is based on long-range cancellations of individually slowly decaying contributions in the amplitude equations. Benchmark calculations for correlation, reaction, and activation energies demonstrate that these approximations work extremely well, while pair approximations based on local second-order Møller-Plesset theory can lead to errors that are 1-2 orders of magnitude larger.

  20. Comparing Pair and Small Group Interactions on Oral Tasks

    ERIC Educational Resources Information Center

    Lasito,; Storch, Neomy

    2013-01-01

    Although pair and small group activities are commonly used in second language (L2) classrooms, there are very few studies which can inform teachers about whether it is best to have students work in pairs or in small groups. In this study, conducted in a junior high school in Indonesia with learners of English as a Foreign Language (EFL), we…

  1. Electron positron pair winds and the Eddington limit

    NASA Technical Reports Server (NTRS)

    Leighly, K. M.; Tsuruta, S.

    1989-01-01

    The dynamics of pair winds in the environment of the central engine of Active Galactic Nuclei (AGN) are investigated assuming super Eddington accretion onto black holes. If the accretion is assumed to be spherically symmetric with the accreting matter occurring in discrete cool blobs, and pairs are produced by a nonthermal mechanism, these pairs are blown out by radiation pressure if the coupling between the pairs and accreting blobs is not complete. The coupling also determines the escaping luminosity. If the maximal coupling constraint is relaxed, then a qualitative argument shows that the classical Eddington limit may be exceeded. When the pairs are considered to be noninteracting particles, the outflow is optically thin. Frame dependent effects are considered. Equations are derived considering pair production in the rest frame of the wind and also in the rest frame of the accreting cool blobs. The hydrodynamic equations are integrated numerically.

  2. The Paired-box Homeodomain Transcription Factor Pax6 Binds to the Upstream Region of the TRAP Gene Promoter and Suppresses Receptor Activator of NF-κB Ligand (RANKL)-induced Osteoclast Differentiation*

    PubMed Central

    Kogawa, Masakazu; Hisatake, Koji; Atkins, Gerald J.; Findlay, David M.; Enoki, Yuichiro; Sato, Tsuyoshi; Gray, Peter C.; Kanesaki-Yatsuka, Yukiko; Anderson, Paul H.; Wada, Seiki; Kato, Naoki; Fukuda, Aya; Katayama, Shigehiro; Tsujimoto, Masafumi; Yoda, Tetsuya; Suda, Tatsuo; Okazaki, Yasushi; Matsumoto, Masahito

    2013-01-01

    Osteoclast formation is regulated by balancing between the receptor activator of nuclear factor-κB ligand (RANKL) expressed in osteoblasts and extracellular negative regulatory cytokines such as interferon-γ (IFN-γ) and interferon-β (IFN-β), which can suppress excessive bone destruction. However, relatively little is known about intrinsic negative regulatory factors in RANKL-mediated osteoclast differentiation. Here, we show the paired-box homeodomain transcription factor Pax6 acts as a negative regulator of RANKL-mediated osteoclast differentiation. Electrophoretic mobility shift and reporter assays found that Pax6 binds endogenously to the proximal region of the tartrate acid phosphatase (TRAP) gene promoter and suppresses nuclear factor of activated T cells c1 (NFATc1)-induced TRAP gene expression. Introduction of Pax6 retrovirally into bone marrow macrophages attenuates RANKL-induced osteoclast formation. Moreover, we found that the Groucho family member co-repressor Grg6 contributes to Pax6-mediated suppression of the TRAP gene expression induced by NFATc1. These results suggest that Pax6 interferes with RANKL-mediated osteoclast differentiation together with Grg6. Our results demonstrate that the Pax6 pathway constitutes a new aspect of the negative regulatory circuit of RANKL-RANK signaling in osteoclastogenesis and that the augmentation of Pax6 might therefore represent a novel target to block pathological bone resorption. PMID:23990468

  3. Pairing Correlations at High Spins

    NASA Astrophysics Data System (ADS)

    Ma, Hai-Liang; Dong, Bao-Guo; Zhang, Yan; Fan, Ping; Yuan, Da-Qing; Zhu, Shen-Yun; Zhang, Huan-Qiao; Petrache, C. M.; Ragnarsson, I.; Carlsson, B. G.

    The pairing correcting energies at high spins in 161Lu and 138Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

  4. The First Row Anomaly and Recoupled Pair Bonding in the Halides of the Late p-Block Elements

    PubMed Central

    2012-01-01

    The dramatic differences between the properties of molecules formed from the late p-block elements of the first row of the periodic table (N–F) and those of the corresponding elements in subsequent rows is well recognized as the first row anomaly. Certain properties of the atoms, such as the relative energies and spatial extents of the ns and np orbitals, can explain some of these differences, but not others. In this Account, we summarize the results of our recent computational studies of the halides of the late p-block elements. Our studies point to a single underlying cause for many of these differences: the ability of the late p-block elements in the second and subsequent rows of the periodic table to form recoupled pair bonds and recoupled pair bond dyads with very electronegative ligands. Recoupled pair bonds form when an electron in a singly occupied ligand orbital recouples the pair of electrons in a doubly occupied lone pair orbital on the central atom, leading to a central atom-ligand bond. Recoupled pair bond dyads occur when a second ligand forms a bond with the orbital left over from the initial recoupled pair bond. Recoupled pair bonds and recoupled pair bond dyads enable the late p-block elements to form remarkably stable hypervalent compounds such as PF5 and SF6 and lead to unexpected excited states in smaller halides of the late p-block elements such as SF and SF2. Recoupled pair bonding also causes the Fn–1X–F bond energies to oscillate dramatically once the normal valences of the central atoms have been satisfied. In addition, recoupled pair bonding provides a lower-energy pathway for inversion in heavily fluorinated compounds (PF3 and PF2H, but not PH2F and PH3) and leads to unusual intermediates and products in reactions involving halogens and late p-block element compounds, such as (CH3)2S + F2. Although this Account focuses on the halides of the second row, late p-block elements, recoupled pair bonds and recoupled pair bond dyads are

  5. The first row anomaly and recoupled pair bonding in the halides of the late p-block elements.

    PubMed

    Dunning, Thom H; Woon, David E; Leiding, Jeff; Chen, Lina

    2013-02-19

    The dramatic differences between the properties of molecules formed from the late p-block elements of the first row of the periodic table (N-F) and those of the corresponding elements in subsequent rows is well recognized as the first row anomaly. Certain properties of the atoms, such as the relative energies and spatial extents of the ns and np orbitals, can explain some of these differences, but not others. In this Account, we summarize the results of our recent computational studies of the halides of the late p-block elements. Our studies point to a single underlying cause for many of these differences: the ability of the late p-block elements in the second and subsequent rows of the periodic table to form recoupled pair bonds and recoupled pair bond dyads with very electronegative ligands. Recoupled pair bonds form when an electron in a singly occupied ligand orbital recouples the pair of electrons in a doubly occupied lone pair orbital on the central atom, leading to a central atom-ligand bond. Recoupled pair bond dyads occur when a second ligand forms a bond with the orbital left over from the initial recoupled pair bond. Recoupled pair bonds and recoupled pair bond dyads enable the late p-block elements to form remarkably stable hypervalent compounds such as PF(5) and SF(6) and lead to unexpected excited states in smaller halides of the late p-block elements such as SF and SF(2). Recoupled pair bonding also causes the F(n-1)X-F bond energies to oscillate dramatically once the normal valences of the central atoms have been satisfied. In addition, recoupled pair bonding provides a lower-energy pathway for inversion in heavily fluorinated compounds (PF(3) and PF(2)H, but not PH(2)F and PH(3)) and leads to unusual intermediates and products in reactions involving halogens and late p-block element compounds, such as (CH(3))(2)S + F(2). Although this Account focuses on the halides of the second row, late p-block elements, recoupled pair bonds and recoupled pair

  6. Paired and interacting galaxies: Conference summary

    NASA Technical Reports Server (NTRS)

    Norman, Colin A.

    1990-01-01

    The author gives a summary of the conference proceedings. The conference began with the presentation of the basic data sets on pairs, groups, and interacting galaxies with the latter being further discussed with respect to both global properties and properties of the galactic nuclei. Then followed the theory, modelling and interpretation using analytic techniques, simulations and general modelling for spirals and ellipticals, starbursts and active galactic nuclei. Before the conference the author wrote down the three questions concerning pairs, groups and interacting galaxies that he hoped would be answered at the meeting: (1) How do they form, including the role of initial conditions, the importance of subclustering, the evolution of groups to compact groups, and the fate of compact groups; (2) How do they evolve, including issues such as relevant timescales, the role of halos and the problem of overmerging, the triggering and enhancement of star formation and activity in the galactic nuclei, and the relative importance of dwarf versus giant encounters; and (3) Are they important, including the frequency of pairs and interactions, whether merging and interactions are very important aspects of the life of a normal galaxy at formation, during its evolution, in forming bars, shells, rings, bulges, etc., and in the formation and evolution of active galaxies? Where possible he focuses on these three central issues in the summary.

  7. Intramolecular competition between n-pair and π-pair hydrogen bonding: Microwave spectrum and internal dynamics of the pyridine-acetylene hydrogen-bonded complex

    NASA Astrophysics Data System (ADS)

    Mackenzie, Rebecca B.; Dewberry, Christopher T.; Coulston, Emma; Cole, George C.; Legon, Anthony C.; Tew, David P.; Leopold, Kenneth R.

    2015-09-01

    a-type rotational spectra of the hydrogen-bonded complex formed from pyridine and acetylene are reported. Rotational and 14N hyperfine constants indicate that the complex is planar with an acetylenic hydrogen directed toward the nitrogen. However, unlike the complexes of pyridine with HCl and HBr, the acetylene moiety in HCCH—NC5H5 does not lie along the symmetry axis of the nitrogen lone pair, but rather, forms an average angle of 46° with the C2 axis of the pyridine. The a-type spectra of HCCH—NC5H5 and DCCD—NC5H5 are doubled, suggesting the existence of a low lying pair of tunneling states. This doubling persists in the spectra of HCCD—NC5H5, DCCH—NC5H5, indicating that the underlying motion does not involve interchange of the two hydrogens of the acetylene. Single 13C substitution in either the ortho- or meta-position of the pyridine eliminates the doubling and gives rise to separate sets of spectra that are well predicted by a bent geometry with the 13C on either the same side ("inner") or the opposite side ("outer") as the acetylene. High level ab initio calculations are presented which indicate a binding energy of 1.2 kcal/mol and a potential energy barrier of 44 cm-1 in the C2v configuration. Taken together, these results reveal a complex with a bent hydrogen bond and large amplitude rocking of the acetylene moiety. It is likely that the bent equilibrium structure arises from a competition between a weak hydrogen bond to the nitrogen (an n-pair hydrogen bond) and a secondary interaction between the ortho-hydrogens of the pyridine and the π electron density of the acetylene.

  8. Frustrated Lewis pair chemistry: development and perspectives.

    PubMed

    Stephan, Douglas W; Erker, Gerhard

    2015-05-26

    Frustrated Lewis pairs (FLPs) are combinations of Lewis acids and Lewis bases in solution that are deterred from strong adduct formation by steric and/or electronic factors. This opens pathways to novel cooperative reactions with added substrates. Small-molecule binding and activation by FLPs has led to the discovery of a variety of new reactions through unprecedented pathways. Hydrogen activation and subsequent manipulation in metal-free catalytic hydrogenations is a frequently observed feature of many FLPs. The current state of this young but rapidly expanding field is outlined in this Review and the future directions for its broadening sphere of impact are considered.

  9. Pair extended coupled cluster doubles

    SciTech Connect

    Henderson, Thomas M.; Scuseria, Gustavo E.; Bulik, Ireneusz W.

    2015-06-07

    The accurate and efficient description of strongly correlated systems remains an important challenge for computational methods. Doubly occupied configuration interaction (DOCI), in which all electrons are paired and no correlations which break these pairs are permitted, can in many cases provide an accurate account of strong correlations, albeit at combinatorial computational cost. Recently, there has been significant interest in a method we refer to as pair coupled cluster doubles (pCCD), a variant of coupled cluster doubles in which the electrons are paired. This is simply because pCCD provides energies nearly identical to those of DOCI, but at mean-field computational cost (disregarding the cost of the two-electron integral transformation). Here, we introduce the more complete pair extended coupled cluster doubles (pECCD) approach which, like pCCD, has mean-field cost and reproduces DOCI energetically. We show that unlike pCCD, pECCD also reproduces the DOCI wave function with high accuracy. Moreover, pECCD yields sensible albeit inexact results even for attractive interactions where pCCD breaks down.

  10. Satellite observations of transionospheric pulse pairs

    SciTech Connect

    Holden, D.N.; Munson, C.P.; Devenport, J.C.

    1995-04-15

    The BLACKBEARD payload aboard the ALEXIS satellite has been making broadband observations in the VHF band of the radio spectrum. Since November of 1993 several hundred unusual signals have been recorded. The peculiar nature of these bursts of radio noise is that they have a duration of approximately 10 {mu}sec, are typically 20 to 40 dB brighter than the average background, and occur in pairs separated by approximately 50 {mu}sec. The authors have dubbed these emissions TransIonospheric Pulse Pairs, or TIPP events. They do not know what the source of these emissions is, but the dispersion of these signals is consistent with an origin at or near the earth`s surface. The satellite field of view and time of day when TIPP events are generally detected are consistent with regions of thunderstorm activity such as south-central Africa or Indonesia. 4 refs., 5 figs.

  11. Satellite observations of transionospheric pulse pairs

    NASA Astrophysics Data System (ADS)

    Holden, D. N.; Munson, C. P.; Devenport, J. C.

    1995-04-01

    The BLACKBEARD payload aboard the ALEXIS satellite has been making broadband observations in the VHF band of the radio spectrum. Since November of 1993 several hundred unusual signals have been recorded. The peculiar nature of these bursts of radio noise is that they have a duration of approximately 10 microseconds, are typically 20 to 40 dB brighter than the average background, and occur in pairs separated by approximately 50 microseconds. We have dubbed these emissions TransIonospheric Pulse Pairs, or TIPP events. We do not know what the source of these emissions is, but the dispersion of these signals is consistent with an origin at or near the earth's surface. The satellite field of view and time of day when TIPP events are generally detected are consistent with regions of thunderstorm activity such as south-central Africa or Indonesia.

  12. PAIR (Planning and Analysis of Inspection Resources)

    SciTech Connect

    Teichmann, T.; Santaniello, A.; Fishbone, L.G.

    1994-03-01

    The safeguards inspection effort of the International Atomic Energy Agency consists of the efforts for the Physical Inventory Verifications to close the annual material balance, Interim Inventory Verifications, conducted mainly to satisfy the Timeliness Criteria, Flow Verifications to verify the transfer of material, and Containment and Surveillance activities, which help preserve continuity of knowledge concerning the material. Estimating the requiring overall future inspection effort under a variety of conditions is an important part of Agency planning. As exemplified by the sample results provides a straightforward means to analyze `What if` situations in safeguards implementation. It thereby permits managers and analysts to study future scenarios and their effect on human resources. It is planned to introduce into PAIR a direct capability for studying costs associated with these hypothetical changes in safeguards implementation. In this way PAIR could more easily assist the Safeguards Department in its current program of investigating new safeguards approaches.

  13. Pair-Starved Pulsar Magnetospheres

    NASA Technical Reports Server (NTRS)

    Muslimov, Alex G.; Harding, Alice K.

    2009-01-01

    We propose a simple analytic model for the innermost (within the light cylinder of canonical radius, approx. c/Omega) structure of open-magnetic-field lines of a rotating neutron star (NS) with relativistic outflow of charged particles (electrons/positrons) and arbitrary angle between the NS spin and magnetic axes. We present the self-consistent solution of Maxwell's equations for the magnetic field and electric current in the pair-starved regime where the density of electron-positron plasma generated above the pulsar polar cap is not sufficient to completely screen the accelerating electric field and thus establish thee E . B = 0 condition above the pair-formation front up to the very high altitudes within the light cylinder. The proposed mode1 may provide a theoretical framework for developing the refined model of the global pair-starved pulsar magnetosphere.

  14. Invisibly Sanitizable Signature without Pairings

    NASA Astrophysics Data System (ADS)

    Yum, Dae Hyun; Lee, Pil Joong

    Sanitizable signatures allow sanitizers to delete some pre-determined parts of a signed document without invalidating the signature. While ordinary sanitizable signatures allow verifiers to know how many subdocuments have been sanitized, invisibly sanitizable signatures do not leave any clue to the sanitized subdocuments; verifiers do not know whether or not sanitizing has been performed. Previous invisibly sanitizable signature scheme was constructed based on aggregate signature with pairings. In this article, we present the first invisibly sanitizable signature without using pairings. Our proposed scheme is secure under the RSA assumption.

  15. Use of a new rat chondrosarcoma cell line to delineate a 119-base pair chondrocyte-specific enhancer element and to define active promoter segments in the mouse pro-alpha 1(II) collagen gene.

    PubMed

    Mukhopadhyay, K; Lefebvre, V; Zhou, G; Garofalo, S; Kimura, J H; de Crombrugghe, B

    1995-11-17

    We show that a new rat chondrosarcoma (RCS) cell line established in long-term culture from the Swarm tumor displayed a stable differentiated chondrocyte-like phenotype. Indeed, these cells produced the collagen types II, IX, and XI and alcian blue-stainable cartilage-specific proteoglycans, but no type I or type III collagen. To functionally characterize their chondrocytic nature, the cells were stably transfected with a type II collagen/beta geo chimeric gene which confers essentially perfect chondrocyte-specific expression in transgenic mice. RCS cells expressed both beta-galactosidase and G418 resistance, in comparison with similarly transfected 10T1/2 and NIH/3T3 fibroblasts which did not. These cells were then used to perform a systematic deletion analysis of the first intron of the mouse type II collagen gene (Col2a1) using transient expression experiments to determine which segments stimulated expression of a luciferase reporter gene in RCS cells but not in 10T1/2 fibroblasts. Cloning of two tandem copies of a 156-base pair (bp) intron 1 fragment (+2188 to +2343) in a construction containing a 314-bp Col2a1 promoter caused an almost 200-fold increase in promoter activity in RCS cells but no increase in 10T1/2 cells. DNase I footprint analysis over this 156-bp fragment revealed two adjacent protected regions, FP1 and FP2, located in the 3'-half of this segment, but no differences were seen with nuclear extracts of RCS cells and 10T1/2 fibroblasts. Deletion of FP2 to leave a 119-bp segment decreased enhancer activity by severalfold, but RCS cell specificity was maintained. Further deletions indicated that sequences both in the 5' part of the 119-bp fragment and in FP1 were needed simultaneously for RCS cell-specific enhancer activity. A series of deletions in the promoter region of the mouse Col2a1 gene progressively reduced activity when these promoters were tested by themselves in transient expression experiments. However, these promoter deletions were all

  16. Missing energies at pair creation

    NASA Technical Reports Server (NTRS)

    El-Ela, A. A.; Hassan, S.; Bagge, E. R.

    1985-01-01

    Wilson cloud chamber measurements of the separated spectra of positrons and electrons produced by gamma quanta of 6.14 MeV differ considerably from the theoretically predicted spectra by BETHE and HEITLER, but are in good agreement with those of a modified theory of pair creation.

  17. Pairing Linguistic and Music Intelligences

    ERIC Educational Resources Information Center

    DiEdwardo, MaryAnn Pasda

    2005-01-01

    This article describes how music in the language classroom setting can be a catalyst for developing reading, writing, and understanding skills. Studies suggest that pairing music and linguistic intelligences in the college classroom improves students' grades and abilities to compose theses statements for research papers in courses that emphasize…

  18. Persistent Ion Pairing in Aqueous Hydrochloric Acid

    SciTech Connect

    Baer, Marcel D.; Fulton, John L.; Balasubramanian, Mahalingam; Schenter, Gregory K.; Mundy, Christopher J.

    2014-07-03

    For strong acids, like hydrochloric acid, the complete dissociation into an excess proton and conjugated base as well as the formation of independent solvated charged fragments is assumed. The existence of a chloride-Hyronium (Cl-H3O+) contact ion pairs even in moderate concentration hydrochloric acid (2.5 m) demonstrates that the counter ions do not behave merely as spectators. Through the use of modern extended X-ray absorption fine structure (EXAFS) measurements in conjunction with state-of-the-art density functional theory (DFT) simulations, we are able to obtain an unprecedented view into the molecular structure of medium to high concentrated electrolytes. Here we report that the Cl-H3O+ contact ion pair structure persists throughout the entire concentration range studied and that these structures differ significantly from moieties studied in micro-solvated hydrochloric acid clusters. Characterizing distinct populations of these ion pairs gives rise to a novel molecular level description of how to think about the activity of the proton that impacts our picture of the pH scale. Funding for CJM, GKS, and JLF was provided by DOE Office of Science, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences, and Biosciences. Funding for MDB was provided throught the Laboratory Directed Research and Development program at Pacific Northwest National Laboratory. MB was funded through Argonne National Laboratory.

  19. Lonely at the Top?

    ERIC Educational Resources Information Center

    Valdata, Patricia

    2006-01-01

    College or university presidents (or chancellors, depending on the institution) get paid the big bucks to worry about the big picture: capital campaigns, attracting and retaining students, creating and sustaining quality academic programs, shared governance. It's a demanding job even when everything goes well, but when problems arise, challenges…

  20. Life detection using glucose and tetrasaccharide enantiomer pairs.

    PubMed

    Warmflash, David; Chu, Huanyi; Siefert, Johnathan; Fox, George E

    2009-04-01

    A life-detection system based on the expectation that any viable organism will utilize stereoisomers of a given compound asymmetrically is examined. Aqueous extracts of common soil, Mars regolith simulant JSC Mars-1, and suspensions of E. coli and S. cerevisiae were incubated with stereoisomer pairs. The enantiomeric pairs were either D- and L-glucose or a pair of chiral tetrasaccharides. Following an incubation period of 10 days, stereoisomeric selectivity is detectable with the glucose pair by mass spectrometry in extracts made from soil at 0.5 g/ml, in extracts made from JSC Mars-1 at 2.5 g/ml, and in cell suspensions down to 1.0 x 10(7) cells/ml. For the tetrasaccharide pair, stereoisomeric selectivity was detected in extracts made from 0.5 g/ml or more of common soil but not in JSC Mars-1 simulant. The effective sensitivity in extracts was 2.5 x 10(7) cells/ml or better for the glucose pair and 5.0 x 10(8) cells/ml or better for the tetrasaccharide pair. The sensitivity of the glucose pair was such that it could detect life in samples that would be found to be devoid of organic matter by the GCMS system carried by the Viking landers. The results demonstrate the utility of the approach in the search for biological activity on Mars. However, sensitivity is a function of the enantiomer pair used, and this might also be different for hypothetical martian organisms. Therefore, it will be necessary to characterize additional stereoisomeric pairs and, ultimately, to include several in a single test environment.

  1. Collisions of Vortex Filament Pairs

    NASA Astrophysics Data System (ADS)

    Banica, Valeria; Faou, Erwan; Miot, Evelyne

    2014-12-01

    We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

  2. Asymmetric Ion-Pairing Catalysis

    PubMed Central

    Brak, Katrien

    2014-01-01

    Charged intermediates and reagents are ubiquitous in organic transformations. The interaction of these ionic species with chiral neutral, anionic, or cationic small molecules has emerged as a powerful strategy for catalytic, enantioselective synthesis. This review describes developments in the burgeoning field of asymmetric ion-pairing catalysis with an emphasis on the insights that have been gleaned into the structural and mechanistic features that contribute to high asymmetric induction. PMID:23192886

  3. Septin pairs, a complex choreography.

    PubMed

    Ewers, Helge

    2011-06-13

    Septins form a filamentous collar at the mother-bud neck in budding yeast. In cytokinesis, this collar splits into two rings and the septin complexes undergo a dramatic reorientation. Using fluorescence polarization microscopy, DeMay et al. (2011. J. Cell Biol. doi:10.1083/jcb.201012143) now demonstrate that septin complexes assemble as paired filaments in vivo and reveal new insights into septin organization during cytokinesis.

  4. Nuclear and extended infrared emission in paired and isolated galaxies

    NASA Technical Reports Server (NTRS)

    Cutri, Roc M.

    1990-01-01

    The empirical connection between gravitational and collisional interactions among galaxies and enhanced activity has been well-documented. However, the physical mechanisms which are responsible for triggering the various forms of activity have not been determined. The author presents the preliminary results of a study of the nuclear and integrated infrared properties of galaxies chosen from the Catalog of Isolated Pairs of Galaxies in the Northern Hemisphere (Karachentsev 1972; hereafter CPG) and the Catalog of Isolated Galaxies (Karachentseva 1973; hereafter KI). Observations of these large, unbiased samples of paired and isolated galaxies are analyzed with the hope of identifying which aspects of galaxy encounters are most closely coupled to the presence of activity.

  5. SRTM Stereo Pair: Fiji Islands

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Sovereign Democratic Republic of the Fiji Islands, commonly known as Fiji, is an independent nation consisting of some 332 islands surrounding the Koro Sea in the South Pacific Ocean. This topographic image shows Viti Levu, the largest island in the group. With an area of 10,429 square kilometers (about 4000 square miles), it comprises more than half the area of the Fiji Islands. Suva, the capital city, lies on the southeast shore. The Nakauvadra, the rugged mountain range running from north to south, has several peaks rising above 900 meters (about 3000 feet). Mount Tomanivi, in the upper center, is the highest peak at 1324 meters (4341 feet). The distinct circular feature on the north shore is the Tavua Caldera, the remnant of a large shield volcano that was active about 4 million years ago. Gold has been mined on the margin of the caldera since the 1930s. The Nadrau plateau is the low relief highland in the center of the mountain range. The coastal plains in the west, northwest and southeast account for only 15 percent of Viti Levu's area but are the main centers of agriculture and settlement.

    This stereoscopic view was generated using preliminary topographic data from the Shuttle Radar Topography Mission. A computer-generated artificial light source illuminates the elevation data from the top (north) to produce a pattern of light and shadows. Slopes facing the light appear bright, while those facing away are shaded. Also, colors show the elevation as measured by SRTM. Colors range from green at the lowest elevations to pink at the highest elevations. This image contains about 1300 meters (4300 feet) of total relief. The stereoscopic effect was created by first draping the shading and colors back over the topographic data and then generating two differing perspectives, one for each eye. The 3-D perception is achieved by viewing the left image with the right eye and the right image with the left eye (cross-eyed viewing), or by downloading and printing the

  6. Phenomenology of transionospheric pulse pairs

    NASA Astrophysics Data System (ADS)

    Massey, R. S.; Holden, D. N.

    1995-09-01

    Recent observations of transient radio impulses by an Earth-orbiting satellite appear to be quite unlike any previously reported. They appear as pairs of brief (a few microseconds), noiselike bursts, separated by a few tens of microseconds, and are dispersed in a way that implies subionospheric origin. Over 300 of these events have now been observed. These "transionospheric pulse pairs" (TIPPs) have not yet been associated with any known source, although thunderstorms are suspected. The observations, made by the Blackbeard instrument on the ALEXIS satellite, are digitized records of the electric field in a passband from about 25 to 100 MHz. Ground-based observations of lightning in this band appear quite different, even accounting for ionospheric dispersion: bursts of short pulses last hundreds of microseconds and have much lower power (when propagated to the satellite) than TIPP events. Signals that resemble the ground-based data have been observed by Blackbeard but, being much weaker, are much less likely to trigger the instrument than are the strong pulse pair events. In this paper we analyze 97 of the early TIPP observations. We compute several parameters that describe the events: the location of the satellite at the time of reception, the energy in each pulse, the separation between pulses, the duration of each pulse, and the dispersion of each pulse. The statistical distributions of these parameters provide clues to and constraints on possible source mechanisms. The possibility that the pulses might be the direct and reflected signals from a high-altitude source is considered and cannot be rejected by the data.

  7. Paired circularly polarized heterodyne ellipsometer

    SciTech Connect

    Yu, C.-J.; Lin, C.-E.; Yu, L.-P.; Chou, C

    2009-02-01

    We develop a paired circularly polarized heterodyne ellipsometer (PCPHE), in which a heterodyne interferometer based on a two-frequency circularly polarized laser beam is set up. It belongs to an amplitude-sensitive ellipsometer that is able to provide not only a wider dynamic range of polarization modulation frequency but also a higher detection sensitivity than that of a conventional photometric ellipsometer. A real-time and precise measurement of ellipsometric parameters, which demonstrated an accuracy of less than 1 nm on thickness measurement of SiO2 thin film deposited on silicon substrate, can be applied with the PCPHE.

  8. Halogen bonding. The role of the polarizability of the electron-pair donor.

    PubMed

    Duarte, Darío J R; Sosa, Gladis L; Peruchena, Nélida M; Alkorta, Ibon

    2016-03-14

    The nature of F-BrX-R interactions (with X = F, Cl, Br, I and R = -H, -F) has been investigated through theoretical calculation of molecular potential electrostatic (MEP), molecular polarizability, atoms in molecules (AIM) analysis and energetic decomposition analysis (EDA). A detailed analysis of the MEPs reveals that considering only the static electrostatic interactions is not sufficient to explain the nature of these interactions. The molecular polarizabilities of X-R molecules suggest that the deformation capacity of the electronic cloud of the lone pairs of the X atom plays an important role in the stability of these complexes. The topological analysis of the L(r) = -¼∇(2)ρ(r) function and the detailed analysis of the atomic quadrupole moments reveal that the BrX interactions are electrostatic in nature. The electron acceptor Br atom causes a polarization of the electronic cloud (electronic induction) on the valence shell of the X atom. Finally, the electrostatic forces and charge transfer play an important role not only in the stabilization of the complex, but also in the determination of the molecular geometry of equilibrium. The dispersive and polarization forces do not influence the equilibrium molecular geometry.

  9. Rashba Splitting of Cooper Pairs

    NASA Astrophysics Data System (ADS)

    Shekhter, R. I.; Entin-Wohlman, O.; Jonson, M.; Aharony, A.

    2016-05-01

    We investigate theoretically the properties of a weak link between two superconducting leads, which has the form of a nonsuperconducting nanowire with a strong Rashba spin-orbit coupling caused by an electric field. In the Coulomb-blockade regime of single-electron tunneling, we find that such a weak link acts as a "spin splitter" of the spin states of Cooper pairs tunneling through the link, to an extent that depends on the direction of the electric field. We show that the Josephson current is sensitive to interference between the resulting two transmission channels, one where the spins of both members of a Cooper pair are preserved and one where they are both flipped. As a result, the current is a periodic function of the strength of the spin-orbit interaction and of the bending angle of the nanowire (when mechanically bent); an identical effect appears due to strain-induced spin-orbit coupling. In contrast, no spin-orbit induced interference effect can influence the current through a single weak link connecting two normal metals.

  10. Single spots, unipolar magnetic regions, and pairs of spots: 2. The development of sunspot pairs and the Hale boundary

    NASA Astrophysics Data System (ADS)

    Akasofu, Syun-Ichi

    2015-04-01

    Sunspot pairs develop in connection with cell networks at or near the boundaries of positive and negative unipolar magnetic (UM) field regions. In this paper, we confirm his findings by recent data. In this connection, Svalgaard and Wilcox (1976) found also that solar activities occur only at one side of UM boundaries, called the "Hale boundary," on the basis of their observation of the interplanetary magnetic field. It is shown in this paper that the Hale boundary can be recognized also on the photosphere. Further, it is shown that new UM regions grow at the beginning of a new sunspot cycle, and active regions and sunspot pairs tend to develop at or near newly developing Hale boundaries. Thus, it is suggested that UM regions and specifically Hale boundaries are very important for the formation of active regions, sunspots, and sunspot pairs. These facts suggest also that UM regions are not merely remnants of decaying old spots and active regions. Some of the essential features of sunspot pairs, as well as their relationship to the Hale boundary in both even and odd cycles are presented in one figure, illustrating several requirements for a theory of the formation of single spots and sunspot pairs.

  11. Optical conductivity from pair density waves

    NASA Astrophysics Data System (ADS)

    Dai, Zhehao; Lee, Patrick A.

    2017-01-01

    We present a theory of optical conductivity in systems with finite-momentum Cooper pairs. In contrast to the BCS pairing where ac conductivity is purely imaginary in the clean limit, there is nonzero ac absorption across the superconducting gap for finite-momentum pairing if we break the Galilean symmetry explicitly in the electronic Hamiltonian. Vertex correction is crucial for maintaining the gauge invariance in the mean-field formalism and dramatically changes the optical conductivity in the direction of the pairing momentum. We carried out a self-consistent calculation and gave an explicit formula for optical conductivity in a simple case. This result applies to the Fulde-Ferrell-Larkin-Ovchinnikov state and candidates with pair density waves proposed for high-Tc cuprates. It may help detect pair density waves and determine the pairing gap as well as the direction of the pairing momentum in experiments.

  12. First-principles study of Frenkel pair recombination in tungsten

    NASA Astrophysics Data System (ADS)

    Qin, Shi-Yao; Jin, Shuo; Li, Yu-Hao; Zhou, Hong-Bo; Zhang, Ying; Lu, Guang-Hong

    2017-02-01

    The recombination of one Frenkel pair in tungsten has been investigated through first-principles simulation. Two different recombination types have been identified: instantaneous and thermally activated. The small recombination barriers for thermally activated recombination cases indicate that recombination can occur easily with a slightly increased temperature. For both of the two recombination types, recombination occurs through the self-interstitial atom moving towards the vacancy. The recombination process can be direct or through replacement sequences, depending on the vertical distance between the vacancy and the <1 1 1> line of self-interstitial atom pair.

  13. A bridge between a lonely soul and the surrounding world: A study on existential consequences of being closely related to a person with aphasia.

    PubMed

    Nyström, Maria

    2011-01-01

    This study illuminates existential consequences of being closely related to a person suffering from aphasia. Seventeen close relatives were interviewed and their narratives were interpreted with inspiration from Ricoeur, Levinas, Husserl, Winnicot, and Maurice Merleau-Ponty. The emerging interpretations resulted in four themes that illuminate a life characterized by lost freedom, staying, a new form of relationship, and growing strong together with others. An overarching theme suggests that a life together with an aphasic person means being used as a bridge between the aphasic person and the surrounding world. Moreover, it illuminates that a close relative to a person with aphasia is a person who does not leave, despite a heavy burden of lonely responsibility. It is concluded that community services need to fulfill their responsibility of providing support to informal caregivers as suggested by the Swedish lawmakers.

  14. A bridge between a lonely soul and the surrounding world: A study on existential consequences of being closely related to a person with aphasia

    PubMed Central

    Nyström, Maria

    2011-01-01

    This study illuminates existential consequences of being closely related to a person suffering from aphasia. Seventeen close relatives were interviewed and their narratives were interpreted with inspiration from Ricoeur, Levinas, Husserl, Winnicot, and Maurice Merleau-Ponty. The emerging interpretations resulted in four themes that illuminate a life characterized by lost freedom, staying, a new form of relationship, and growing strong together with others. An overarching theme suggests that a life together with an aphasic person means being used as a bridge between the aphasic person and the surrounding world. Moreover, it illuminates that a close relative to a person with aphasia is a person who does not leave, despite a heavy burden of lonely responsibility. It is concluded that community services need to fulfill their responsibility of providing support to informal caregivers as suggested by the Swedish lawmakers. PMID:22114621

  15. Homolog pairing and segregation in Drosophila meiosis.

    PubMed

    McKee, B D

    2009-01-01

    Pairing of homologous chromosomes is fundamental to their reliable segregation during meiosis I and thus underlies sexual reproduction. In most eukaryotes homolog pairing is confined to prophase of meiosis I and is accompanied by frequent exchanges, known as crossovers, between homologous chromatids. Crossovers give rise to chiasmata, stable interhomolog connectors that are required for bipolar orientation (orientation to opposite poles) of homologs during meiosis I. Drosophila is unique among model eukaryotes in exhibiting regular homolog pairing in mitotic as well as meiotic cells. I review the results of recent molecular studies of pairing in both mitosis and meiosis in Drosophila. These studies show that homolog pairing is continuous between pre-meiotic mitosis and meiosis but that pairing frequencies and patterns are altered during the mitotic-meiotic transition. They also show that, with the exception of X-Y pairing in male meiosis, which is mediated specifically by the 240-bp rDNA spacer repeats, chromosome pairing is not restricted to specific sites in either mitosis or meiosis. Instead, virtually all chromosome regions, both heterochromatic and euchromatic, exhibit autonomous pairing capacity. Mutations that reduce the frequencies of both mitotic and meiotic pairing have been recently described, but no mutations that abolish pairing completely have been discovered, and the genetic control of pairing in Drosophila remains to be elucidated.

  16. Traditional and ion-pair halogen-bonded complexes between chlorine and bromine derivatives and a nitrogen-heterocyclic carbene.

    PubMed

    Donoso-Tauda, Oscar; Jaque, Pablo; Elguero, José; Alkorta, Ibon

    2014-10-09

    A theoretical study of the halogen-bonded complexes (A-X···C) formed between halogenated derivatives (A-X; A = F, Cl, Br, CN, CCH, CF3, CH3, H; and X = Cl, Br) and a nitrogen heterocyclic carbene, 1,3-dimethylimidazole-2-ylidene (MeIC) has been performed using MP2/aug'-cc-pVDZ level of theory. Two types of A-X:MeIC complexes, called here type-I and -II, were found and characterized. The first group is described by long C-X distances and small binding energies (8-54 kJ·mol(-1)). In general, these complexes show the traditional behavior of systems containing halogen-bonding interactions. The second type is characterized by short C-X distances and large binding energies (148-200 kJ·mol(-1)), and on the basis of the topological analysis of the electron density, they correspond to ion-pair halogen-bonded complexes. These complexes can be seen as the interaction between two charged fragments: A(-) and (+)[X-CIMe] with a high electrostatic contribution in the binding energy. The charge transfer between lone pair A(LP) to the σ* orbital of C-X bond is also identified as a significant stabilizing interaction in type-II complexes.

  17. Intramolecular competition between n-pair and π-pair hydrogen bonding: Microwave spectrum and internal dynamics of the pyridine–acetylene hydrogen-bonded complex

    SciTech Connect

    Mackenzie, Rebecca B.; Dewberry, Christopher T.; Leopold, Kenneth R. E-mail: david.tew@bristol.ac.uk; Coulston, Emma; Cole, George C.; Legon, Anthony C. E-mail: david.tew@bristol.ac.uk Tew, David P. E-mail: david.tew@bristol.ac.uk

    2015-09-14

    a-type rotational spectra of the hydrogen-bonded complex formed from pyridine and acetylene are reported. Rotational and {sup 14}N hyperfine constants indicate that the complex is planar with an acetylenic hydrogen directed toward the nitrogen. However, unlike the complexes of pyridine with HCl and HBr, the acetylene moiety in HCCH—NC{sub 5}H{sub 5} does not lie along the symmetry axis of the nitrogen lone pair, but rather, forms an average angle of 46° with the C{sub 2} axis of the pyridine. The a-type spectra of HCCH—NC{sub 5}H{sub 5} and DCCD—NC{sub 5}H{sub 5} are doubled, suggesting the existence of a low lying pair of tunneling states. This doubling persists in the spectra of HCCD—NC{sub 5}H{sub 5}, DCCH—NC{sub 5}H{sub 5}, indicating that the underlying motion does not involve interchange of the two hydrogens of the acetylene. Single {sup 13}C substitution in either the ortho- or meta-position of the pyridine eliminates the doubling and gives rise to separate sets of spectra that are well predicted by a bent geometry with the {sup 13}C on either the same side (“inner”) or the opposite side (“outer”) as the acetylene. High level ab initio calculations are presented which indicate a binding energy of 1.2 kcal/mol and a potential energy barrier of 44 cm{sup −1} in the C{sub 2v} configuration. Taken together, these results reveal a complex with a bent hydrogen bond and large amplitude rocking of the acetylene moiety. It is likely that the bent equilibrium structure arises from a competition between a weak hydrogen bond to the nitrogen (an n-pair hydrogen bond) and a secondary interaction between the ortho-hydrogens of the pyridine and the π electron density of the acetylene.

  18. The Importance of Discourse Style in Pairing Students for Interactive Communicative Tasks.

    ERIC Educational Resources Information Center

    Spelman, Mary

    A study analyzed the discourse of four pairs of students participating in dyadic interactive communicative tasks (ICTs) to discover if and how their discourse styles influenced the dynamics of interaction. Students were paired according to their teacher's evaluation of their discourse style as active or non-active, and were designated sender or…

  19. Evans hole and non linear optical activity in Bis(melaminium) sulphate dihydrate: A vibrational spectral study.

    PubMed

    Suresh Kumar, V R; Binoy, J; Dawn Dharma Roy, S; Marchewka, M K; Jayakumar, V S

    2015-01-01

    Bis(melaminium) sulphate dihydrate (BMSD), an interesting melaminium derivative for nonlinear optical activity, has been subjected to vibrational spectral analysis using FT IR and FT Raman spectra. The analysis has been aided by the Potential Energy Distribution (PED) of vibrational spectral bands, derived using density functional theory (DFT) at B3LYP/6-31G(d) level. The geometry is found to correlate well with the XRD structure and the band profiles for certain vibrations in the finger print region have been theoretically explained using Evans hole. The detailed Natural Bond Orbital (NBO) analysis of the hydrogen bonding in BMSD has also been carried out to understand the correlation between the stabilization energy of hyperconjugation of the lone pair of donor with the σ(∗) orbital of hydrogen-acceptor bond and the strength of hydrogen bond. The theoretical calculation shows that BMSD has NLO efficiency, 2.66 times that of urea. The frontier molecular orbital analysis points to a charge transfer, which contributes to NLO activity, through N-H…O intermolecular hydrogen bonding between the melaminium ring and the sulphate. The molecular electrostatic potential (MEP) mapping has also been performed for the detailed analysis of the mutual interactions between melaminium ring and sulphate ion.

  20. FIR statistics of paired galaxies

    NASA Technical Reports Server (NTRS)

    Sulentic, Jack W.

    1990-01-01

    Much progress has been made in understanding the effects of interaction on galaxies (see reviews in this volume by Heckman and Kennicutt). Evidence for enhanced emission from galaxies in pairs first emerged in the radio (Sulentic 1976) and optical (Larson and Tinsley 1978) domains. Results in the far infrared (FIR) lagged behind until the advent of the Infrared Astronomy Satellite (IRAS). The last five years have seen numerous FIR studies of optical and IR selected samples of interacting galaxies (e.g., Cutri and McAlary 1985; Joseph and Wright 1985; Kennicutt et al. 1987; Haynes and Herter 1988). Despite all of this work, there are still contradictory ideas about the level and, even, the reality of an FIR enhancement in interacting galaxies. Much of the confusion originates in differences between the galaxy samples that were studied (i.e., optical morphology and redshift coverage). Here, the authors report on a study of the FIR detection properties for a large sample of interacting galaxies and a matching control sample. They focus on the distance independent detection fraction (DF) statistics of the sample. The results prove useful in interpreting the previously published work. A clarification of the phenomenology provides valuable clues about the physics of the FIR enhancement in galaxies.

  1. Pulsational Pair-instability Supernovae

    NASA Astrophysics Data System (ADS)

    Woosley, S. E.

    2017-02-01

    The final evolution of stars in the mass range 70–140 {\\text{}}{M}ȯ is explored. Depending upon their mass loss history and rotation rates, these stars will end their lives as pulsational pair-instability supernovae (PPISN) producing a great variety of observational transients with total durations ranging from weeks to millennia and luminosities from 1041 to over 1044 erg s‑1. No nonrotating model radiates more than 5× {10}50 erg of light or has a kinetic energy exceeding 5× {10}51 erg, but greater energies are possible, in principle, in magnetar-powered explosions, which are explored. Many events resemble SNe Ibn, SNe Icn, and SNe IIn, and some potential observational counterparts are mentioned. Some PPISN can exist in a dormant state for extended periods, producing explosions millennia after their first violent pulse. These dormant supernovae contain bright Wolf–Rayet stars, possibly embedded in bright X-ray and radio sources. The relevance of PPISN to supernova impostors like Eta Carinae, to superluminous supernovae, and to sources of gravitational radiation is discussed. No black holes between 52 and 133 {\\text{}}{M}ȯ are expected from stellar evolution in close binaries.

  2. Ordered pairing in liquid metallic hydrogen

    NASA Technical Reports Server (NTRS)

    Carlsson, A. E.; Ashcroft, N. W.

    1983-01-01

    We study two possible types of pairing involving the protons of a proposed low-temperature liquid phase metallic hydrogen. Electron-proton pairing, which can result in an insulating phase, is investigated by using an approximate solution of an Eliashberg-type equation for the anomalous self-energy. A very low estimate of the transition temperature is obtained by including proton correlations in the effective interaction. For proton-proton pairing, we derive a new proton pair potential based on the Abrikosov wave function. This potential includes the electron-proton interaction to all orders and has a much larger well depth than is obtained with linear screening methods. This suggests the possibility of either a superfluid paired phase analogous to that in He-3, or alternatively a phase with true molecular pairing.

  3. Ensemble treatments of thermal pairing in nuclei

    NASA Astrophysics Data System (ADS)

    Hung, Nguyen Quang; Dang, Nguyen Dinh

    2009-10-01

    A systematic comparison is conducted for pairing properties of finite systems at nonzero temperature as predicted by the exact solutions of the pairing problem embedded in three principal statistical ensembles, namely the grandcanonical ensemble, canonical ensemble and microcanonical ensemble, as well as the unprojected (FTBCS1+SCQRPA) and Lipkin-Nogami projected (FTLN1+SCQRPA) theories that include the quasiparticle number fluctuation and coupling to pair vibrations within the self-consistent quasiparticle random-phase approximation. The numerical calculations are performed for the pairing gap, total energy, heat capacity, entropy, and microcanonical temperature within the doubly-folded equidistant multilevel pairing model. The FTLN1+SCQRPA predictions are found to agree best with the exact grand-canonical results. In general, all approaches clearly show that the superfluid-normal phase transition is smoothed out in finite systems. A novel formula is suggested for extracting the empirical pairing gap in reasonable agreement with the exact canonical results.

  4. Chiral organoborane Lewis pairs derived from pyridylferrocene.

    PubMed

    Chen, Jiawei; Lalancette, Roger A; Jäkle, Frieder

    2014-07-14

    In an effort to develop a new class of redox-active chiral Lewis pairs, pyridine and borane moieties with different steric and electronic properties were introduced onto a planar chiral 1,2-disubstituted ferrocene framework. Metathesis of lithiated, stannylated, or mercuriated pyridylferrocenes with boron halides afforded (pR)-2-[bis(pentafluorophenyl)boryl]-1-(3,5-dimethylpyrid-2-yl)ferrocene (4-Pf), (pR)-2-[dimesitylboryl]-1-(3,5-dimethylpyrid-2-yl)ferrocene (4-Mes), (pS)-2-(bis(pentafluorophenyl)boryl)-1-(2-trimethylsilylpyrid-6-yl)ferrocene (5-Pf), or (pS)-2-[dimesitylboryl]-1-(2-trimethylsilylpyrid-6-yl)ferrocene (5-Mes). The borylated products were analyzed by multinuclear NMR spectroscopy, HRMS, and single-crystal X-ray diffraction. Chiral HPLC and optical-rotation measurements were employed to assess the stereoselectivity of the borylation process and to establish the correct stereochemical assignments. The strength of the B-N interactions were investigated in solution and in the solid state. Compounds 4-Pf and 4-Mes formed robust 'closed' B-N heterocyclic systems that proved to be perfectly stable to air and moisture, whereas 5-Pf established a dynamic equilibrium, in which the B-N heterocycle was observed exclusively at room temperature, but opened up at high temperature according to (19)F NMR exchange spectroscopy data. As a consequence, 5-Pf reacted readily with a molecule of water to generate a ring-opened pyridinium borate. The combination of bulky borane and bulky pyridyl groups in 5-Mes led to a completely 'open' frustrated Lewis pair system with uncomplexed pyridine and borane groups, even at room temperature. Electrochemical studies were performed and the effect of preparative ferrocene oxidation on the structural features was also explored.

  5. Conformational and isomeric preferences of six-membered inorganic heterocycles [EtNP(E)(OR)]3 (E = Lone Pair, O, S, or Se): a synthetic, spectroscopic, structural, and computational study.

    PubMed

    Murugavel, Ramaswamy; Prabusankar, Ganesan; Sharma, Ashish; Sunoj, Raghavan B; Butcher, Ray J

    2009-03-02

    A silicophosphonate bearing four hydroxyl groups, [RSi(OH){OP(O)(H)(OH)}](2)O (2; R = (2,6-(i)Pr(2)C(6)H(3))N(SiMe(3))), has been isolated from the reaction between RSi(OH)(3) and [EtNPCl](3). In contrast, the reaction between the sodium salt of substituted phenols and [EtNPCl](3) yields [EtNP(OAr)](3) [Ar = -C(6)H(3)(i)Pr(2)-2,6 (3), -C(6)H(2)Me(3)-2,4,6 (4), -C(6)H(3)Me(2)-2,6 (5), -C(10)H(7)-1 (6), and -C(6)H(4)(t)Bu-4 (7)]. The cis isomers 3a-7a preferentially crystallize out from the cis/trans isomeric mixture. Single-crystal X-ray diffraction studies carried out for 3a, 4a, and 5a reveal that the P(3)N(3) ring adopts a flattened-chair conformation with the aryloxy substituent on all three phosphorus atoms occupying the axial position. Oxidation of the cis isomers 3 and 5 by H(2)O(2), sulfur, and selenium yields the trichalcogenides [EtNP(E)(OC(6)H(3)(i)Pr(2)-2,6)](3) (E = O (8), S (10), Se (12)) and [EtNP(E)(OC(6)H(3)Me(2)-2,6)](3) (E = O (9), S (11), Se (13)). The reaction leading to the formation of the triselenide 12 also produces small quantities of the diselenide [Et(3)N(3)P(3)(OR)(3)Se(2)] (R = -C(6)H(3)(i)Pr(2)-2,6) (14). The P(3)N(3) ring in these lambda(5)-phosphazanes is highly distorted and resembles more of a twist-boat conformation. The DFT calculations on model systems [HNP(S)(OMe)](3) (15) and [HNP(Se)(OMe)](3) (16) indicate five low-lying unique conformers A-E. The chair conformer with a triaxial-OMe group is identified as the lowest-energy conformer in both cases.

  6. Dynamical evolution of comet pairs

    NASA Astrophysics Data System (ADS)

    Sosa, Andrea; Fernández, Julio A.

    2016-10-01

    Some Jupiter family comets in near-Earth orbits (thereafter NEJFCs) show a remarkable similarity in their present orbits, like for instance 169P/NEAT and P/2003 T12 (SOHO), or 252P/LINEAR and P/2016 BA14 (PANSTARRS). By means of numerical integrations we studied the dynamical evolution of these objects. In particular, for each pair of presumably related objects, we are interested in assessing the stability of the orbital parameters for several thousand years, and to find a minimum of their relative spatial distance, coincident with a low value of their relative velocity. For those cases for which we find a well defined minimum of their relative orbital separation, we are trying to reproduce the actual orbit of the hypothetical fragment by modeling a fragmentation of the parent body. Some model parameters are the relative ejection velocity (a few m/s), the orbital point at which the fragmentation could have happened (e.g. perihelion), and the elapsed time since fragmentation. In addition, some possible fragmentation mechanisms, like thermal stress, rotational instability, or collisions, could be explored. According to Fernández J.A and Sosa A. 2015 (Planetary and Space Science 118,pp.14-24), some NEJFCs might come from the outer asteroid belt, and then they would have a more consolidated structure and a higher mineral content than that of comets coming from the trans-Neptunian belt or the Oort cloud. Therefore, such objects would have a much longer physical lifetime in the near-Earth region, and could become potential candidates to produce visible meteor showers (as for example 169P/NEAT which has been identified as the parent body of the alpha-Capricornid meteoroid stream, according to Jenniskens, P., Vaubaillon, J., 2010 (Astron. J. 139), and Kasuga, T., Balam, D.D., Wiegert, P.A., 2010 (Astron. J. 139).

  7. Lax pairs for deformed Minkowski spacetimes

    NASA Astrophysics Data System (ADS)

    Kyono, Hideki; Sakamoto, Jun-ichi; Yoshida, Kentaroh

    2016-01-01

    We proceed to study Yang-Baxter deformations of 4D Minkowski spacetime based on a conformal embedding. We first revisit a Melvin background and argue a Lax pair by adopting a simple replacement law invented in 1509.00173. This argument enables us to deduce a general expression of Lax pair. Then the anticipated Lax pair is shown to work for arbitrary classical r-matrices with Poincaré generators. As other examples, we present Lax pairs for pp-wave backgrounds, the Hashimoto-Sethi background, the Spradlin-Takayanagi-Volovich background.

  8. Dual origin of pairing in nuclei

    NASA Astrophysics Data System (ADS)

    Idini, A.; Potel, G.; Barranco, F.; Vigezzi, E.; Broglia, R. A.

    2016-11-01

    The pairing correlations of the nucleus 120Sn are calculated by solving the Nambu-Gor'kov equations, including medium polarization effects resulting from the interweaving of quasiparticles, spin and density vibrations, taking into account, within the framework of nuclear field theory (NFT), processes leading to self-energy and vertex corrections and to the induced pairing interaction. From these results one can not only demonstrate the inevitability of the dual origin of pairing in nuclei, but also extract information which can be used at profit to quantitatively disentangle the contributions to the pairing gap Δ arising from the bare and from the induced pairing interaction. The first is the strong 1 S 0 short-range NN potential resulting from meson exchange between nucleons moving in time reversal states within an energy range of hundreds of MeV from the Fermi energy. The second results from the exchange of vibrational modes between nucleons moving within few MeV from the Fermi energy. Short- ( v p bare) and long-range ( v p ind) pairing interactions contribute essentially equally to nuclear Cooper pair stability. That is to the breaking of gauge invariance in open-shell superfluid nuclei and thus to the order parameter, namely to the ground state expectation value of the pair creation operator. In other words, to the emergent property of generalized rigidity in gauge space, and associated rotational bands and Cooper pair tunneling between members of these bands.

  9. Conformational changes in redox pairs of protein structures

    PubMed Central

    Fan, Samuel W; George, Richard A; Haworth, Naomi L; Feng, Lina L; Liu, Jason Y; Wouters, Merridee A

    2009-01-01

    Disulfides are conventionally viewed as structurally stabilizing elements in proteins but emerging evidence suggests two disulfide subproteomes exist. One group mediates the well known role of structural stabilization. A second redox-active group are best known for their catalytic functions but are increasingly being recognized for their roles in regulation of protein function. Redox-active disulfides are, by their very nature, more susceptible to reduction than structural disulfides; and conversely, the Cys pairs that form them are more susceptible to oxidation. In this study, we searched for potentially redox-active Cys Pairs by scanning the Protein Data Bank for structures of proteins in alternate redox states. The PDB contains over 1134 unique redox pairs of proteins, many of which exhibit conformational differences between alternate redox states. Several classes of structural changes were observed, proteins that exhibit: disulfide oxidation following expulsion of metals such as zinc; major reorganisation of the polypeptide backbone in association with disulfide redox-activity; order/disorder transitions; and changes in quaternary structure. Based on evidence gathered supporting disulfide redox activity, we propose disulfides present in alternate redox states are likely to have physiologically relevant redox activity. PMID:19598234

  10. Polarization of drifting pairs at decameter waves

    NASA Astrophysics Data System (ADS)

    Brazhenko, A. I.; Melnik, V. N.; Konovalenko, A. A.; Abranin, E. P.; Dorovskyy, V. V.; Vashchishin, R. V.; Frantsuzenko, A. V.; Rucker, H. O.; Lecacheux, A.

    2006-08-01

    The results of polarization researches of drifting pairs (DP) observed during Type III bursts storm in July[S:,:S][Author ID2: at Fri Jul 14 10:33:00 2006 ] 11-21, 2002 with radio telescope URAN-2 are presented. The array of the radio telescope consists of 512 broadband cross dipoles, that enables to receive signals of two polarizations, has the area about of 28000 m^2 and works in 9-30 MHz range. Circular polarization measurements were made at frequency 24.75 MHz in frequency band 10 μHz with time resolution 10 ms. Some hundreds bursts, both forward and reverse DPs, which have been registered with radio telescope UTR-2 in the frequency range 18-32 μHz, were analyzed. For the first time we find that DP polarizations strongly depend on the location of the active area associated with these bursts. When an active area is near to the central meridian, polarizations of both DP components have the same signs and their values are up to 30%. In other days in most cases polarizations of both components have opposite signs and only for some bursts polarization reaches 10%. In all cases both DP components have comparable polarization degrees.

  11. Individual employee's perceptions of " Group-level Safety Climate" (supervisor referenced) versus " Organization-level Safety Climate" (top management referenced): Associations with safety outcomes for lone workers.

    PubMed

    Huang, Yueng-Hsiang; Lee, Jin; McFadden, Anna C; Rineer, Jennifer; Robertson, Michelle M

    2017-01-01

    Research has shown that safety climate is among the strongest predictors of safety behavior and safety outcomes in a variety of settings. Previous studies have established that safety climate is a multi-faceted construct referencing multiple levels of management within a company, most generally: the organization level (employee perceptions of top management's commitment to and prioritization of safety) and group level (employee perceptions of direct supervisor's commitment to and prioritization of safety). Yet, no research to date has examined the potential interaction between employees' organization-level safety climate (OSC) and group-level safety climate (GSC) perceptions. Furthermore, prior research has mainly focused on traditional work environments in which supervisors and workers interact in the same location throughout the day. Little research has been done to examine safety climate with regard to lone workers. The present study aims to address these gaps by examining the relationships between truck drivers' (as an example of lone workers) perceptions of OSC and GSC, both potential linear and non-linear relationships, and how these predict important safety outcomes. Participants were 8095 truck drivers from eight trucking companies in the United States with an average response rate of 44.8%. Results showed that employees' OSC and GSC perceptions are highly correlated (r= 0.78), but notable gaps between the two were observed for some truck drivers. Uniquely, both OSC and GSC scores were found to have curvilinear relationships with safe driving behavior, and both scores were equally predictive of safe driving behavior. Results also showed the two levels of climate significantly interacted with one another to predict safety behavior such that if either the OSC or GSC scores were low, the other's contribution to safety behavior became stronger. These findings suggest that OSC and GSC may function in a compensatory manner and promote safe driving behavior even

  12. Contiguous triple spinal dysraphism associated with Chiari malformation Type II and hydrocephalus: an embryological conundrum between the unified theory of Pang and the unified theory of McLone.

    PubMed

    Dhandapani, Sivashanmugam; Srinivasan, Anirudh

    2016-01-01

    Triple spinal dysraphism is extremely rare. There are published reports of multiple discrete neural tube defects with intervening normal segments that are explained by the multisite closure theory of primary neurulation, having an association with Chiari malformation Type II consistent with the unified theory of McLone. The authors report on a 1-year-old child with contiguous myelomeningocele and lipomyelomeningocele centered on Type I split cord malformation with Chiari malformation Type II and hydrocephalus. This composite anomaly is probably due to select abnormalities of the neurenteric canal during gastrulation, with a contiguous cascading impact on both dysjunction of the neural tube and closure of the neuropore, resulting in a small posterior fossa, probably bringing the unified theory of McLone closer to the unified theory of Pang.

  13. Pairing, pseudogap and Fermi arcs in cuprates

    SciTech Connect

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; Gu, Genda

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scattering creates “artificial” Fermi arcs for Tc ≤ T ≤ Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.

  14. Pair condensation in a finite Fermi system

    SciTech Connect

    Sambataro, M.

    2007-05-15

    The lowest seniority-zero eigenstates of an exactly solvable multilevel pairing Hamiltonian for a finite Fermi system are examined at different pairing regimes. After briefly reviewing the form of the eigenstates in the Richardson formalism, we discuss a different representation of these states in terms of the collective pairs resulting from the diagonalization of the Hamiltonian in a space of two degenerate time-reversed fermions. We perform a two-fold analysis by working both in the fermionic space of these collective pairs and in a space of corresponding elementary bosons. On the fermionic side, we monitor the variations which occur, with increasing the pairing strength, in the structure of both these collective pairs and the lowest eigenstates. On the bosonic side, after reviewing a fermion-boson mapping procedure, we construct exact images of the fermion eigenstates and study their wave function. The analysis allows a close examination of the phenomenon of pair condensation in a finite Fermi system and gives new insights into the evolution of the lowest (seniority-zero) excited states of a pairing Hamiltonian from the unperturbed regime up to a strongly interacting one.

  15. Exploring Pair Programming Benefits for MIS Majors

    ERIC Educational Resources Information Center

    Dongo, Tendai; Reed, April H.; O'Hara, Margaret

    2016-01-01

    Pair programming is a collaborative programming practice that places participants in dyads, working in tandem at one computer to complete programming assignments. Pair programming studies with Computer Science (CS) and Software Engineering (SE) majors have identified benefits such as technical productivity, program/design quality, academic…

  16. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  17. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  18. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  19. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  20. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  1. Top Quark Pair Production at the Tevatron

    SciTech Connect

    Nielsen, Jason

    2005-05-17

    The measurement of the top quark pair production crosssection inproton-antiproton collisions at 1.96 TeV is a test ofquantumchromodynamics and could potentially be sensitive to newphysics beyondthe standard model. I report on the latest t-tbarcross section resultsfrom the CDF and DZero experiments in various finalstate topologies whicharise from decays of top quark pairs.

  2. Pairing in a dry Fermi sea

    NASA Astrophysics Data System (ADS)

    Maier, T. A.; Staar, P.; Mishra, V.; Chatterjee, U.; Campuzano, J. C.; Scalapino, D. J.

    2016-06-01

    In the traditional Bardeen-Cooper-Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and -k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. Here we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. In contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin-fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability.

  3. PAIR: the predicted Arabidopsis interactome resource.

    PubMed

    Lin, Mingzhi; Shen, Xueling; Chen, Xin

    2011-01-01

    The predicted Arabidopsis interactome resource (PAIR, http://www.cls.zju.edu.cn/pair/), comprised of 5990 experimentally reported molecular interactions in Arabidopsis thaliana together with 145,494 predicted interactions, is currently the most comprehensive data set of the Arabidopsis interactome with high reliability. PAIR predicts interactions by a fine-tuned support vector machine model that integrates indirect evidences for interaction, such as gene co-expressions, domain interactions, shared GO annotations, co-localizations, phylogenetic profile similarities and homologous interactions in other organisms (interologs). These predictions were expected to cover 24% of the entire Arabidopsis interactome, and their reliability was estimated to be 44%. Two independent example data sets were used to rigorously validate the prediction accuracy. PAIR features a user-friendly query interface, providing rich annotation on the relationships between two proteins. A graphical interaction network browser has also been integrated into the PAIR web interface to facilitate mining of specific pathways.

  4. Solubilization and fractionation of paired helical filaments.

    PubMed

    González, P J; Correas, I; Avila, J

    1992-09-01

    Paired helical filaments isolated from brains of two different patients with Alzheimer's disease were extensively treated with the ionic detergent, sodium dodecyl sulphate. Filaments were solubilized at different extents, depending on the brain examined, thus suggesting the existence of two types of paired helical filaments: sodium dodecyl sulphate-soluble and insoluble filaments. In the first case, the number of structures resembling paired helical filaments greatly decreased after the detergent treatment, as observed by electron microscopy. Simultaneously, a decrease in the amount of sedimentable protein was also observed upon centrifugation of the sodium dodecyl sulfate-treated paired helical filaments. A sodium dodecyl sulphate-soluble fraction was isolated as a supernatant after low-speed centrifugation of the sodium dodecyl sulphate-treated paired helical filaments. The addition of the non-ionic detergent Nonidet-P40 to this fraction resulted in the formation of paired helical filament-like structures. When the sodium dodecyl sulphate-soluble fraction was further fractionated by high-speed centrifugation, three subfractions were observed: a supernatant, a pellet and a thin layer between these two subfractions. No paired helical filaments were observed in any of these subfractions, even after addition of Nonidet P-40. However, when they were mixed back together, the treatment with Nonidet P-40 resulted in the visualization of paired helical filament-like structures. These results suggest that at least two different components are needed for the reconstitution of paired helical filaments as determined by electron microscopy. The method described here may allow the study of the components involved in the formation of paired helical filaments and the identification of possible factors capable of blocking this process.

  5. On structure and methylene blue degradation activity of an Aurivillius-type photocatalyst of Bi4V2O11 nanoparticles

    NASA Astrophysics Data System (ADS)

    Lu, Yuting; Pu, Yinfu; Wang, Jing; Qin, Chuangxiang; Chen, Cuili; Seo, Hyo Jin

    2015-08-01

    Aurivillius-type photocatalyst of Bi4V2O11 nanoparticles with an average particle size of 45 nm was prepared by the modified Pechini method. The sample was investigated by X-ray powder diffraction (XRD) and the structural refinement. The nanoparticles were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopic (XPS) and UV-vis absorption spectrum. Bi4V2O11 nanoparticles show an efficient absorption in the UV-vis light wavelength region with a narrowed band gap energy of 2.08 eV and an indirect allowed electronic transition. The photocatalytic activities of Bi4V2O11 nanoparticles were evaluated by photodegradation of methylene blue (MB) under visible-light irradiation in air atmosphere. These results indicate that Bi4V2O11 could be a potential photocatalyst driven by visible-light. Hybridization of the 6s and 6p orbitals of Bi3+ and the resulting lone electron pair yields interesting properties. The effective photocatalytic activity was discussed on the base of the crystal structure characteristic such as polar (VO3.5□0.5)2- anionic groups, Aurivillius-type (Bi2O2)2+ layers and long distance of the nearest V-V in the lattices, etc.

  6. Distribution and infection frequency of 'Candidatus Rickettsia amblyommii' in Maryland populations of the lone star tick (Amblyomma americanum) and culture in an Anopheles gambiae mosquito cell line.

    PubMed

    Zhang, Xing; Ren, Xiaoxia; Norris, Douglas E; Rasgon, Jason L

    2012-02-01

    Amblyomma americanum (the lone star tick) is a broadly distributed tick that transmits multiple pathogens of humans and domestic animals. 'Candidatus Rickettsia amblyommii' is a spotted-fever group rickettsial species that is potentially associated with human disease. In 2008 and 2009, we assayed over 500 unfed adult ticks from 19 Maryland populations for the presence of 'Candidatus R. amblyommii'. Infection frequencies ranged from 33% to 100%, with an average infection rate of 60% in 2008 and 69% in 2009. Infection frequencies did not differ statistically between sexes. To develop a system in which to study 'Candidatus R. amblyommii' in the laboratory, we used a cell line developed from Anopheles gambiae mosquitoes (Sua5B) to isolate and culture 'Candidatus R. amblyommii' from field-collected A. americanum ticks from 2 localities in Maryland. After infection, Sua5B cells were infected for more than 40 passages. Infection was confirmed by Rickettsia-specific PCR, gene sequencing, and Rickettsia-specific fluorescence in situ hybridization (FISH). These data show that 'Candidatus R. amblyommii' is widespread in Maryland A. americanum populations and that Sua5B cells are a useful tool for culturing Rickettsia infections from wild ticks.

  7. The lone S41 family C-terminal processing protease in Staphylococcus aureus is localized to the cell wall and contributes to virulence.

    PubMed

    Carroll, Ronan K; Rivera, Frances E; Cavaco, Courtney K; Johnson, Grant M; Martin, David; Shaw, Lindsey N

    2014-08-01

    Staphylococcus aureus is a versatile pathogen of humans and a continued public health concern due to the rise and spread of multidrug-resistant strains. As part of an ongoing investigation into the pathogenic mechanisms of this organism we previously demonstrated that an intracellular N-terminal processing protease is required for S. aureus virulence. Following on from this, here we examine the role of CtpA, the lone C-terminal processing protease of S. aureus. CtpA, a member of the S41 family, is a serine protease whose homologues in Gram-negative bacteria have been implicated in a range of biological functions, including pathogenesis. We demonstrate that S. aureus CtpA is localized to the bacterial cell wall and expression of the ctpA gene is maximal upon exposure to conditions encountered during infection. Disruption of the ctpA gene leads to decreased heat tolerance and increased sensitivity when exposed to components of the host immune system. Finally we demonstrate that the ctpA(-) mutant strain is attenuated for virulence in a murine model of infection. Our results represent the first characterization of a C-terminal processing protease in a pathogenic Gram-positive bacterium and show that it plays a critical role during infection.

  8. Efficacy of amitraz-impregnated collars on white-tailed deer (Artiodactyla: Cervidae) in reducing free-living populations of lone star ticks (Acari: Ixodidae).

    PubMed

    Pound, J M; Lohmeyer, K H; Davey, R B; Miller, J A; George, J E

    2012-12-01

    Over a 7 yr period, we monitored the effect of a commercially available, amitraz impregnated anti-tick collar in controlling free-living populations of lone star ticks, Amblyomma americanum (L.) when manually fitted around necks of white-tailed deer, Odocoileus virginianus (Zimmermann). Study animals in treatment and control groups were confined in 38.8 ha game-fenced and densely vegetated treatment plots in South Texas. Tick densities during years 1 and 7 served as untreated pre- and posttreatment comparisons and treatments occurred during years 2 through 5. Reductions in tick densities in the treatment plot were compared against tick densities in a control plot having similar vegetation and numbers of untreated deer. During years of treatment, indices of control pressure ranged from 18.2 to 82.6 for nymphs and 16.9-78.7 for adults, and efficacy, expressed as percentage control during the final year of treatment, was 77.2 and 85.0%, respectively, for nymphal and adult ticks. These data show that acaricidal collar treatments provide efficacies very similar to those achieved with the existing ivermectin-medicated bait and '4-Poster' topical treatment technologies to control ticks feeding on wild white-tailed deer.

  9. Detecting a preformed pair phase: Response to a pairing forcing field

    NASA Astrophysics Data System (ADS)

    Tagliavini, A.; Capone, M.; Toschi, A.

    2016-10-01

    The normal state of strongly coupled superconductors is characterized by the presence of "preformed" Cooper pairs well above the superconducting critical temperature. In this regime, the electrons are paired, but they lack the phase coherence necessary for superconductivity. The existence of preformed pairs implies the existence of a characteristic energy scale associated with a pseudogap. Preformed pairs are often invoked to interpret systems where some signatures of pairing are present without actual superconductivity, but an unambiguous theoretical characterization of a preformed-pair system is still lacking. To fill this gap, we consider the response to an external pairing field of an attractive Hubbard model, which hosts one of the cleanest realizations of a preformed pair phase, and a repulsive model where s -wave superconductivity cannot be realized. Using dynamical mean-field theory to study this response, we identify the characteristic features which distinguish the reaction of a preformed pair state from a normal metal without any precursor of pairing. The theoretical detection of preformed pairs is associated with the behavior of the second derivative of the order parameter with respect to the external field, as confirmed by analytic calculations in limiting cases. Our findings provide a solid test bed for the interpretation of state-of-the-art calculations for the normal state of the doped Hubbard model in terms of d -wave preformed pairs and, in perspective, of nonequilibrium experiments in high-temperature superconductors.

  10. Slow-light enhanced correlated photon pair generation in a silicon photonic crystal waveguide.

    PubMed

    Xiong, C; Monat, Christelle; Clark, Alex S; Grillet, Christian; Marshall, Graham D; Steel, M J; Li, Juntao; O'Faolain, Liam; Krauss, Thomas F; Rarity, John G; Eggleton, Benjamin J

    2011-09-01

    We report the generation of correlated photon pairs in the telecom C-band at room temperature from a dispersion-engineered silicon photonic crystal waveguide. The spontaneous four-wave mixing process producing the photon pairs is enhanced by slow-light propagation enabling an active device length of less than 100 μm. With a coincidence to accidental ratio of 12.8 at a pair generation rate of 0.006 per pulse, this ultracompact photon pair source paves the way toward scalable quantum information processing realized on-chip.

  11. Phenomenology of transionospheric pulse pairs: Further observations

    SciTech Connect

    Massey, R.S.; Holden, D.N.; Shao, X.

    1998-11-01

    We report on further observations of transionospheric pulse pairs (TIPPs), which are the most powerful transient radio signals observed by the Blackbeard broadband digital radio receiver on the ALEXIS satellite. The source of these signals is unknown but appears to be associated with thunderstorm activity. The signals do not resemble those reported for known lightning processes. We have previously reported observations of these events in the frequency band 28{endash}95 MHz. In this paper we report observations of TIPPs in the 117- to 166-MHz band, with the subsatellite point situated over the contiguous United States. The main results are that the measured pulse parameter statistics are nearly the same as reported for the low-frequency events, with the exception that the pulse separation distribution is biased toward smaller values in the high-frequency observations. The radiated power does not drop off appreciably even at 166 MHz, which further constrains the possible size and timescale of the source(s). We also report results of experiments designed to measure the apparent reflectivity of dry, flat ground at frequencies around 100 MHz. We find that the apparent reflectivity can exceed 90{percent}. This result helps to explain how the second pulse in a TIPP can have so much energy relative to the first. {copyright} 1998 American Geophysical Union

  12. Phenomenology of transionospheric pulse pairs: Further observations

    NASA Astrophysics Data System (ADS)

    Massey, Robert S.; Holden, Daniel N.; Shao, Xuan-Min

    1998-11-01

    We report on further observations of transionospheric pulse pairs (TIPPs), which are the most powerful transient radio signals observed by the Blackbeard broadband digital radio receiver on the ALEXIS satellite. The source of these signals is unknown but appears to be associated with thunderstorm activity. The signals do not resemble those reported for known lightning processes. We have previously reported observations of these events in the frequency band 28-95 MHz. In this paper we report observations of TIPPs in the 117- to 166-MHz band, with the subsatellite point situated over the contiguous United States. The main results are that the measured pulse parameter statistics are nearly the same as reported for the low-frequency events, with the exception that the pulse separation distribution is biased toward smaller values in the high-frequency observations. The radiated power does not drop off appreciably even at 166 MHz, which further constrains the possible size and timescale of the source(s). We also report results of experiments designed to measure the apparent reflectivity of dry, flat ground at frequencies around 100 MHz. We find that the apparent reflectivity can exceed 90%. This result helps to explain how the second pulse in a TIPP can have so much energy relative to the first.

  13. Nonlinear backbone torsional pair correlations in proteins

    NASA Astrophysics Data System (ADS)

    Long, Shiyang; Tian, Pu

    2016-10-01

    Protein allostery requires dynamical structural correlations. Physical origin of which, however, remain elusive despite intensive studies during last two and half decades. Based on analysis of molecular dynamics (MD) simulation trajectories for ten proteins with different sizes and folds, we found that nonlinear backbone torsional pair (BTP) correlations, which are mainly spatially long-ranged and are dominantly executed by loop residues, exist extensively in most analyzed proteins. Examination of torsional motion for correlated BTPs suggested that such nonlinear correlations are mainly associated aharmonic torsional state transitions and in some cases strongly anisotropic local torsional motion of participating torsions, and occur on widely different and relatively longer time scales. In contrast, correlations between backbone torsions in stable α helices and β strands are mainly linear and spatially short-ranged, and are more likely to associate with harmonic local torsional motion. Further analysis revealed that the direct cause of nonlinear contributions are heterogeneous linear correlations. These findings implicate a general search strategy for novel allosteric modulation sites of protein activities.

  14. Nonlinear backbone torsional pair correlations in proteins

    PubMed Central

    Long, Shiyang; Tian, Pu

    2016-01-01

    Protein allostery requires dynamical structural correlations. Physical origin of which, however, remain elusive despite intensive studies during last two and half decades. Based on analysis of molecular dynamics (MD) simulation trajectories for ten proteins with different sizes and folds, we found that nonlinear backbone torsional pair (BTP) correlations, which are mainly spatially long-ranged and are dominantly executed by loop residues, exist extensively in most analyzed proteins. Examination of torsional motion for correlated BTPs suggested that such nonlinear correlations are mainly associated aharmonic torsional state transitions and in some cases strongly anisotropic local torsional motion of participating torsions, and occur on widely different and relatively longer time scales. In contrast, correlations between backbone torsions in stable α helices and β strands are mainly linear and spatially short-ranged, and are more likely to associate with harmonic local torsional motion. Further analysis revealed that the direct cause of nonlinear contributions are heterogeneous linear correlations. These findings implicate a general search strategy for novel allosteric modulation sites of protein activities. PMID:27708342

  15. Ab Initio Atomic Simulations of Antisite Pair Recovery in Cubic Silicon Carbide

    SciTech Connect

    Gao, Fei; Du, Jincheng; Bylaska, Eric J.; Posselt, Matthias; Weber, William J.

    2007-05-28

    The thermal stability of an antisite pair in 3C-SiC is studied using ab initio molecular dynamics within the framework of density functional theory. The lifetime of the antisite pair configuration is calculated for temperatures between 1800 and 2250 K, and the effective activation energy for antisite pair recombination is determined to be 2.52 eV. The recombination energy path and static energy barrier are also calculated using the nudged elastic band method, along with the dimer method to accurately locate the transition states. The consistency of the results suggests that the antisite pair cannot be correlated with the DI photoluminescence center, as proposed by previously theoretical interpretations. An extended exchange mechanism is found for the antisite pair recombination, and this may be a dominant mechanism for antisite pair recombination and diffusion of impurities in compound semiconductors.

  16. A Curious Pair of Galaxies

    NASA Astrophysics Data System (ADS)

    2009-03-01

    The ESO Very Large Telescope has taken the best image ever of a strange and chaotic duo of interwoven galaxies. The images also contain some surprises -- interlopers both far and near. ESO PR Photo 11a/09 A Curious Pair of Galaxies ESO PR Video 11a/09 Arp 261 zoom in ESO PR Video 11b/09 Pan over Arp 261 Sometimes objects in the sky that appear strange, or different from normal, have a story to tell and prove scientifically very rewarding. This was the idea behind Halton Arp's catalogue of Peculiar Galaxies that appeared in the 1960s. One of the oddballs listed there is Arp 261, which has now been imaged in more detail than ever before using the FORS2 instrument on ESO's Very Large Telescope. The image proves to contain several surprises. Arp 261 lies about 70 million light-years distant in the constellation of Libra, the Scales. Its chaotic and very unusual structure is created by the interaction of two galaxies that are engaged in a slow motion, but highly disruptive close encounter. Although individual stars are very unlikely to collide in such an event, the huge clouds of gas and dust certainly do crash into each other at high speed, leading to the formation of bright new clusters of very hot stars that are clearly seen in the picture. The paths of the existing stars in the galaxies are also dramatically disrupted, creating the faint swirls extending to the upper left and lower right of the image. Both interacting galaxies were probably dwarfs not unlike the Magellanic Clouds orbiting our own galaxy. The images used to create this picture were not actually taken to study the interacting galaxies at all, but to investigate the properties of the inconspicuous object just to the right of the brightest part of Arp 261 and close to the centre of the image. This is an unusual exploding star, called SN 1995N, that is thought to be the result of the final collapse of a massive star at the end of its life, a so-called core collapse supernova. SN 1995N is unusual because

  17. Weird Stellar Pair Puzzles Scientists

    NASA Astrophysics Data System (ADS)

    2008-05-01

    Astronomers have discovered a speedy spinning pulsar in an elongated orbit around an apparent Sun-like star, a combination never seen before, and one that has them puzzled about how the strange system developed. Orbital Comparison Comparing Orbits of Pulsar and Its Companion to our Solar System. CREDIT: Bill Saxton, NRAO/AUI/NSF Click on image for full caption information and available graphics. "Our ideas about how the fastest-spinning pulsars are produced do not predict either the kind of orbit or the type of companion star this one has," said David Champion of the Australia Telescope National Facility. "We have to come up with some new scenarios to explain this weird pair," he added. Astronomers first detected the pulsar, called J1903+0327, as part of a long-term survey using the National Science Foundation's Arecibo radio telescope in Puerto Rico. They made the discovery in 2006 doing data analysis at McGill University, where Champion worked at the time. They followed up the discovery with detailed studies using the Arecibo telescope, the NSF's Robert C. Byrd Green Bank Telescope (GBT) in West Virginia, the Westerbork radio telescope in the Netherlands, and the Gemini North optical telescope in Hawaii. The pulsar, a city-sized superdense stellar corpse left over after a massive star exploded as a supernova, is spinning on its axis 465 times every second. Nearly 21,000 light-years from Earth, it is in a highly-elongated orbit that takes it around its companion star once every 95 days. An infrared image made with the Gemini North telescope in Hawaii shows a Sun-like star at the pulsar's position. If this is an orbital companion to the pulsar, it is unlike any companions of other rapidly rotating pulsars. The pulsar, a neutron star, also is unusually massive for its type. "This combination of properties is unprecedented. Not only does it require us to figure out how this system was produced, but the large mass may help us understand how matter behaves at extremely

  18. Pure Pairing Modes in Trapped Fermion Systems

    NASA Astrophysics Data System (ADS)

    Capuzzi, P.; Hernández, E. S.; Szybisz, L.

    2013-05-01

    We present numerical predictions for the shape of the pairing fluctuations in harmonically trapped atomic 6Li with two spin projections, based on the fluiddynamical description of cold fermions with pairing interactions. In previous works it has been shown that when the equilibrium of a symmetric mixture is perturbed, the linearized fluiddynamic equations decouple into two sets, one containing the sound mode of fermion superfluids and the other the pairing mode. The latter corresponds to oscillations of the modulus of the complex gap and is driven by the kinetic energy densities of the particles and of the pairs. Assuming proportionality between the heat flux and the energy gradient, the particle kinetic energy undergoes a diffusive behavior and the diffusion parameter is the key parameter for the relaxation time scale. We examine a possible range of values for this parameter and find that the shape of the pairing oscillation is rather insensitive to the precise value of the transport coefficient. Moreover, the pairing fluctuation is largely confined to the center of the trap, and the energy of the pairing mode is consistent with the magnitude of the equilibrium gap.

  19. Pair supersolid with atom-pair hopping on the state-dependent triangular lattice

    NASA Astrophysics Data System (ADS)

    Zhang, Wanzhou; Yin, Ruoxi; Wang, Yancheng

    2013-11-01

    We systematically study an extended Bose-Hubbard model with atom hopping and atom-pair hopping in the presence of a three-body constraint on the triangular lattice. By means of large-scale quantum Monte Carlo simulations, the ground-state phase diagram is studied. We find a first-order transition between the atomic superfluid phase and the pair superfluid phase when the ratio of the atomic hopping and the atom-pair hopping is adapted. The first-order transition remains unchanged under various conditions. We then focus on the interplay among the atom-pair hopping, the on-site repulsion, and the nearest-neighbor repulsion. With on-site repulsion present, we observe first-order transitions between the Mott insulators and pair superfluid driven by the pair hopping. With the nearest-neighbor repulsion turning on, three typical solid phases with 2/3, 1, and 4/3 filling emerge at small atom-pair hopping region. A stable pair supersolid phase is found at small on-site repulsion. This is due to the three-body constraint and the pair hopping, which essentially make the model a quasihardcore boson system. Thus the pair supersolid state emerges basing on the order-by-disorder mechanism, by which hardcore bosons avoid classical frustration on the triangular lattice. Without on-site repulsion, the transitions between the pair supersolid and the atom superfluid or pair superfluid are first order, except for the particle-hole symmetric point. With weak on-site repulsion and atom hopping turning on, the transition between the pair supersolid and pair superfluid phase becomes continuous. The transition between solid and pair supersolid is three-dimensional XY university, with dynamical exponent z=1 and correlation exponent ν=0.67155. The thermal melting of pair supersolid belongs to the two-dimensional Ising university. We check both energetic and mechanical balance of pair supersolid phase. Lowering the three-body constraint, no pair supersolid is found due to the absence of

  20. Pair creation in heavy ion channeling

    NASA Astrophysics Data System (ADS)

    Belov, N. A.; Harman, Z.

    2016-04-01

    Heavy ions channeled through crystals with multi-GeV kinetic energies can create electron-positron pairs. In the framework of the ion, the energy of virtual photons arising from the periodic crystal potential may exceed the threshold 2mec2. The repeated periodic collisions with the crystal ions yield high pair production rates. When the virtual photon frequency matches a nuclear transition in the ion, the production rate can be resonantly increased. In this two-step excitation-pair conversion scheme, the excitation rates are coherently enhanced, and scale approximately quadratically with the number of crystal sites along the channel.

  1. Pair Creation at Large Inherent Angles

    SciTech Connect

    Chen, P.; Tauchi, T.; Schroeder, D.V.; /SLAC

    2007-04-25

    In the next-generation linear colliders, the low-energy e{sup +}e{sup -} pairs created during the collision of high-energy e{sup +}e{sup -} beams would cause potential deleterious background problems to the detectors. At low collider energies, the pairs are made essentially by the incoherent process, where the pair is created by the interaction of beamstrahlung photons on the individual particles in the oncoming beam. This problem was first identified by Zolotarev, et al[1]. At energies where the beamstrahlung parameter {Upsilon} lies approximately in the range 0.6 {approx}< {Upsilon} {approx}< 100, pair creation from the beamstrahlung photons is dominated by a coherent process, first noted by Chen[2]. The seriousness of this pair creation problem lies in the transverse momenta that the pair particles carry when leaving the interaction point (IP) with large angles. One source of transverse momentum is from the kick by the field of the oncoming beam which results in an outcoming angle {theta} {proportional_to} 1/{radical}x, where x is the fractional energy of the particle relative to the initial beam particle energy[2,3]. As was shown in Ref. 131, there in fact exists an energy threshold for the coherent pairs, where x{sub th} {approx}> 1/2{Upsilon}. Thus within a tolerable exiting angle, there exists an upper limit for {Upsilon} where all coherent pairs would leave the detector through the exhaust port[4]. A somewhat different analysis has been done by Schroeder[5]. In the next generation of linear colliders, as it occurs, the coherent pairs can be exponentially suppressed[2] by properly choosing the {Upsilon}({approx}< 0.6). When this is achieved, the incoherent pairs becomes dominant. Since the central issue is the transverse momentum for particles with large angles, we notice that there is another source for it. Namely, when the pair particles are created at low energies, the intrinsic angles of these pairs when produced may already be large. This issue was

  2. Repellency of the Origanum onites L. Essential Oil and Constituents to the Lone Star Tick and Yellow Fever Mosquito

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The oregano, Origanum onites L., essential oil (EO) was tested in laboratory behavioral bioassays for repellent activity against Amblyomma americanum (L.) and Aedes aegypti (L.). The O. onites EO was characterized using GC-FID and GC-MS. Carvacrol (75.70 %), linalool (9.0 %), p-cymene (4.33 %) and t...

  3. Validating silicon polytrodes with paired juxtacellular recordings: method and dataset

    PubMed Central

    Lopes, Gonçalo; Frazão, João; Nogueira, Joana; Lacerda, Pedro; Baião, Pedro; Aarts, Arno; Andrei, Alexandru; Musa, Silke; Fortunato, Elvira; Barquinha, Pedro; Kampff, Adam R.

    2016-01-01

    Cross-validating new methods for recording neural activity is necessary to accurately interpret and compare the signals they measure. Here we describe a procedure for precisely aligning two probes for in vivo “paired-recordings” such that the spiking activity of a single neuron is monitored with both a dense extracellular silicon polytrode and a juxtacellular micropipette. Our new method allows for efficient, reliable, and automated guidance of both probes to the same neural structure with micrometer resolution. We also describe a new dataset of paired-recordings, which is available online. We propose that our novel targeting system, and ever expanding cross-validation dataset, will be vital to the development of new algorithms for automatically detecting/sorting single-units, characterizing new electrode materials/designs, and resolving nagging questions regarding the origin and nature of extracellular neural signals. PMID:27306671

  4. Nudged Elastic Band Simulations of Kink Pairs in Tungsten

    SciTech Connect

    Cereceda, D.; Marian, J.

    2015-01-16

    Atomistic techniques have been used to calculate energy barriers for dislocation motion that control the strength (yield stress and flow stress) of the material. In particular, the calculations focus on the change in enthalpy as a straight dislocation moves through the crystal lattice (the Peierls barrier) and kink pair formation enthalpy that controls the thermally activated double-kink mechanism important at low to moderate stresses. A novel means of assessing kink widths within atomistic simulations is introduced.

  5. Paired Stimulation to Promote Lasting Augmentation of Corticospinal Circuits

    PubMed Central

    2016-01-01

    After injury, electrical stimulation of the nervous system can augment plasticity of spared or latent circuits through focal modulation. Pairing stimulation of two parts of a spared circuit can target modulation more specifically to the intended circuit. We discuss 3 kinds of paired stimulation in the context of the corticospinal system, because of its importance in clinical neurorehabilitation. The first uses principles of Hebbian plasticity: by altering the stimulation timing of presynaptic neurons and their postsynaptic targets, synapse function can be modulated up or down. The second form uses synchronized presynaptic inputs onto a common synaptic target. We dub this a “convergent” mechanism, because stimuli have to converge on a common target with coordinated timing. The third form induces focal modulation by tonic excitation of one region (e.g., the spinal cord) during phasic stimulation of another (e.g., motor cortex). Additionally, endogenous neural activity may be paired with exogenous electrical stimulation. This review addresses what is known about paired stimulation of the corticospinal system of both humans and animal models, emphasizes how it qualitatively differs from single-site stimulation, and discusses the gaps in knowledge that must be addressed to maximize its use and efficacy in neurorehabilitation. PMID:27800189

  6. Multi-user distribution of polarization entangled photon pairs

    NASA Astrophysics Data System (ADS)

    Trapateau, J.; Ghalbouni, J.; Orieux, A.; Diamanti, E.; Zaquine, I.

    2015-10-01

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  7. Multi-user distribution of polarization entangled photon pairs

    SciTech Connect

    Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I.; Ghalbouni, J.

    2015-10-14

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  8. Anyon pairing via phonon-mediated interaction

    NASA Astrophysics Data System (ADS)

    Kandemir, B. S.

    2006-08-01

    In this paper, we study the pairing of anyons subjected to an external uniform magnetic field and confined in a two-dimensional parabolic quantum dot within the framework of Fröhlich large bipolaron theory, motivated by the Wilczek’s prescription that treats anyons as composites having both charges and fictitious flux tubes. In this model, electrons bound to Aharanov-Bohm type flux tubes and surrounded by a cloud of virtual LO phonons interact with each other through the long range Coulomb and statistical potentials. In order to discuss the effects of both spatial confinement potential and external uniform magnetic field on the boundaries of the stability region of such a pairing in real space, we perform a self-consistent treatment of the ground-state energies of both an interacting anyon pair and two noninteracting anyons. Our results suggest that two interacting anyons can be bound into a condensate anyon pair through a phonon-mediated interaction.

  9. Temporal Multimode Storage of Entangled Photon Pairs

    NASA Astrophysics Data System (ADS)

    Tiranov, Alexey; Strassmann, Peter C.; Lavoie, Jonathan; Brunner, Nicolas; Huber, Marcus; Verma, Varun B.; Nam, Sae Woo; Mirin, Richard P.; Lita, Adriana E.; Marsili, Francesco; Afzelius, Mikael; Bussières, Félix; Gisin, Nicolas

    2016-12-01

    Multiplexed quantum memories capable of storing and processing entangled photons are essential for the development of quantum networks. In this context, we demonstrate and certify the simultaneous storage and retrieval of two entangled photons inside a solid-state quantum memory and measure a temporal multimode capacity of ten modes. This is achieved by producing two polarization-entangled pairs from parametric down-conversion and mapping one photon of each pair onto a rare-earth-ion-doped (REID) crystal using the atomic frequency comb (AFC) protocol. We develop a concept of indirect entanglement witnesses, which can be used as Schmidt number witnesses, and we use it to experimentally certify the presence of more than one entangled pair retrieved from the quantum memory. Our work puts forward REID-AFC as a platform compatible with temporal multiplexing of several entangled photon pairs along with a new entanglement certification method, useful for the characterization of multiplexed quantum memories.

  10. Spectra from pair-equilibrium plasmas

    NASA Technical Reports Server (NTRS)

    Zdziarski, A. A.

    1984-01-01

    A numerical model of relativistic nonmagnetized plasma with uniform temperature and electron density distributions is considered, and spectra from plasma in pair equilibrium are studied. A range of dimensionless temperature (T) greater than about 0.2 is considered. The spectra from low pair density plasmas in pair equilibrium vary from un-Comptonized bremsstrahlung spectra at Thomson cross section tau(N) much less than one to Comptonized bremsstrahlung spectra with tau(N) over one. For high pair density plasmas the spectra are flat for T greater than about one, and have broad intensity peaks at energy roughly equal to 3T for T less than one. In the latter region the total luminosity is approximately twice the annihilation luminosity. All spectra are flat in the X-ray region, in contradiction to observed AGN spectra. For dimensionless luminosity greater than about 100, the cooling time becomes shorter than the Thomson time.

  11. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  12. Mixed parity pairing in a dipolar gas

    NASA Astrophysics Data System (ADS)

    Bruun, G. M.; Hainzl, C.; Laux, M.

    2016-10-01

    We show that fermionic dipoles in a two-layer geometry form Cooper pairs with both singlet and triplet components when they are tilted with respect to the normal of the planes. The mixed parity pairing arises because the interaction between dipoles in the two different layers is not inversion symmetric. We use an efficient eigenvalue approach to calculate the zero-temperature phase diagram of the system as a function of the dipole orientation and the layer distance. The phase diagram contains purely triplet as well as mixed singlet and triplet superfluid phases. We show in detail how the pair wave function for dipoles residing in different layers smoothly changes from singlet to triplet symmetry as the orientation of the dipoles is changed. Our results indicate that dipolar quantum gases can be used to unambiguously observe mixed parity pairing.

  13. Pairing phenomena in strongly correlated Fermi liquids

    NASA Astrophysics Data System (ADS)

    Krotscheck, E.; Smith, R. A.; Jackson, A. D.

    1981-12-01

    The correlated-basis-function method is extended to deal with pairing phenomena in strongly correlated Fermi liquids. With a variational ansatz for the model wave function we derive the "correlated" analog of the conventional Bardeen-Cooper-Schrieffer (or Balian-Werthamer), Anderson-Brinkman-Morel theory of pairing. A suitable (and well-controlled) set of approximations brings the theory into a form identical to the conventional theories, but with the bare interaction replaced by a weak effective interaction and the bare single-particle energies replaced by an effective single-particle spectrum. As usual, liquid 3He provides a very stringent test of the theory, as both the interaction and the experimental facts are pretty clear. The variational estimates for the pairing interaction are improved by nonorthogonal perturbation theory. We find the expected enhancement of the attraction in P waves, although the restriction to effective two-body interactions appears to be insufficient to generate P-wave pairing.

  14. Polarization proximity effect in isolator crystal pairs.

    PubMed

    Linzon, Y; Ferrera, M; Razzari, L; Pignolet, A; Morandotti, R

    2008-12-01

    We experimentally study the polarization dynamics (orientation and ellipticity) of near-infrared light transmitted through magneto-optical yttrium iron garnet isolator crystal pairs using a modified balanced detection scheme. When the pair separation is in the submillimeter range, we observed a proximity effect in which the saturation field is reduced by up to 20%. One-dimensional calculations suggest that the proximity effect originates from magnetostatic interactions between the dipole moments of the isolator crystals.

  15. Alternative DNA base pairing through metal coordination.

    PubMed

    Clever, Guido H; Shionoya, Mitsuhiko

    2012-01-01

    Base-pairing in the naturally occurring DNA and RNA oligonucleotide duplexes is based on π-stacking, hydrogen bonding, and shape complementarity between the nucleobases adenine, thymine, guanine, and cytosine as well as on the hydrophobic-hydrophilic balance in aqueous media. This complex system of multiple supramolecular interactions is the product of a long-term evolutionary process and thus highly optimized to serve its biological functions such as information storage and processing. After the successful implementation of automated DNA synthesis, chemists have begun to introduce artificial modifications inside the core of the DNA double helix in order to study various aspects of base pairing, generate new base pairs orthogonal to the natural ones, and equip the biopolymer with entirely new functions. The idea to replace the hydrogen bonding interactions with metal coordination between ligand-like nucleosides and suitable transition metal ions culminated in the development of a plethora of artificial base-pairing systems termed "metal base-pairs" which were shown to strongly enhance the DNA duplex stability. Furthermore, they show great potential for the use of DNA as a molecular wire in nanoscale electronic architectures. Although single electrons have proven to be transmitted by natural DNA over a distance of several base pairs, the high ohmic resistance of unmodified oligonucleotides was identified as a serious obstacle. By exchanging some or all of the Watson-Crick base pairs in DNA with metal complexes, this problem may be solved. In the future, these research efforts are supposed to lead to DNA-like materials with superior conductivity for nano-electronic applications. Other fields of potential application such as DNA-based supramolecular architecture and catalysis may be strongly influenced by these developments as well. This text is meant to illustrate the basic concepts of metal-base pairing and give an outline over recent developments in this field.

  16. Ultrabright source of entangled photon pairs.

    PubMed

    Dousse, Adrien; Suffczyński, Jan; Beveratos, Alexios; Krebs, Olivier; Lemaître, Aristide; Sagnes, Isabelle; Bloch, Jacqueline; Voisin, Paul; Senellart, Pascale

    2010-07-08

    A source of triggered entangled photon pairs is a key component in quantum information science; it is needed to implement functions such as linear quantum computation, entanglement swapping and quantum teleportation. Generation of polarization entangled photon pairs can be obtained through parametric conversion in nonlinear optical media or by making use of the radiative decay of two electron-hole pairs trapped in a semiconductor quantum dot. Today, these sources operate at a very low rate, below 0.01 photon pairs per excitation pulse, which strongly limits their applications. For systems based on parametric conversion, this low rate is intrinsically due to the Poissonian statistics of the source. Conversely, a quantum dot can emit a single pair of entangled photons with a probability near unity but suffers from a naturally very low extraction efficiency. Here we show that this drawback can be overcome by coupling an optical cavity in the form of a 'photonic molecule' to a single quantum dot. Two coupled identical pillars-the photonic molecule-were etched in a semiconductor planar microcavity, using an optical lithography method that ensures a deterministic coupling to the biexciton and exciton energy states of a pre-selected quantum dot. The Purcell effect ensures that most entangled photon pairs are emitted into two cavity modes, while improving the indistinguishability of the two optical recombination paths. A polarization entangled photon pair rate of 0.12 per excitation pulse (with a concurrence of 0.34) is collected in the first lens. Our results open the way towards the fabrication of solid state triggered sources of entangled photon pairs, with an overall (creation and collection) efficiency of 80%.

  17. Formation of asteroid pairs by rotational fission.

    PubMed

    Pravec, P; Vokrouhlický, D; Polishook, D; Scheeres, D J; Harris, A W; Galád, A; Vaduvescu, O; Pozo, F; Barr, A; Longa, P; Vachier, F; Colas, F; Pray, D P; Pollock, J; Reichart, D; Ivarsen, K; Haislip, J; Lacluyze, A; Kusnirák, P; Henych, T; Marchis, F; Macomber, B; Jacobson, S A; Krugly, Yu N; Sergeev, A V; Leroy, A

    2010-08-26

    Pairs of asteroids sharing similar heliocentric orbits, but not bound together, were found recently. Backward integrations of their orbits indicated that they separated gently with low relative velocities, but did not provide additional insight into their formation mechanism. A previously hypothesized rotational fission process may explain their formation-critical predictions are that the mass ratios are less than about 0.2 and, as the mass ratio approaches this upper limit, the spin period of the larger body becomes long. Here we report photometric observations of a sample of asteroid pairs, revealing that the primaries of pairs with mass ratios much less than 0.2 rotate rapidly, near their critical fission frequency. As the mass ratio approaches 0.2, the primary period grows long. This occurs as the total energy of the system approaches zero, requiring the asteroid pair to extract an increasing fraction of energy from the primary's spin in order to escape. We do not find asteroid pairs with mass ratios larger than 0.2. Rotationally fissioned systems beyond this limit have insufficient energy to disrupt. We conclude that asteroid pairs are formed by the rotational fission of a parent asteroid into a proto-binary system, which subsequently disrupts under its own internal system dynamics soon after formation.

  18. On cooperative instabilities of parallel vortex pairs

    NASA Astrophysics Data System (ADS)

    Bristol, R. L.; Ortega, J. M.; Marcus, P. S.; Savas, Ö.

    2004-10-01

    We present a combined analytical and numerical study of the instabilities of a pair of parallel unequal-strength vortices. We extend the analyses of a vortex in an external strain field (Crow, AIAA J. vol. 8, 1970, p. 2172; Widnall et al., J. Fluid Mech. vol. 66, 1974, p. 35) to include the orbital motion of the vortex pair. For counter-rotating pairs, the classic Crow-type periodic displacement perturbations are unstable for all vortex strength ratios, with fastest-growing wavelengths several times the vortex spacing. For co-rotating pairs, the orbital motion acts to suppress instability due to displacement perturbations. Instabilities in this case arise for elliptic perturbations at wavelengths that scale with the vortex core size. We also examine the influence of a second vortex pair by extending Crouch's (J. Fluid Mech. vol. 350, 1997, p. 311) analysis. Numerical results from a spectral initial-value code with subgrid-scale modelling agree with the growth rates from the theoretical models. Computations reveal the nonlinear evolution at late times, including wrapping and ring-rejection behaviour observed in experiments. A pair of co-rotating Gaussian vortices perturbed by noise develops elliptic instabilities, leading to the formation of vorticity bridges between the two vortices. The bridging is a prelude to vortex merger. Analytic, computational and experimental results agree well at circulation Reynolds numbers of order 10(5) .

  19. Terminal Area Procedures for Paired Runways

    NASA Technical Reports Server (NTRS)

    Lozito, Sandra; Verma, Savita Arora

    2011-01-01

    Parallel runway operations have been found to increase capacity within the National Airspace but poor visibility conditions reduce the use of these operations. The NextGen and SESAR Programs have identified the capacity benefits from increased use of closely-space parallel runway. Previous research examined the concepts and procedures related to parallel runways however, there has been no investigation of the procedures associated with the strategic and tactical pairing of aircraft for these operations. This simulation study developed and examined the pilot and controller procedures and information requirements for creating aircraft pairs for parallel runway operations. The goal was to achieve aircraft pairing with a temporal separation of 15s (+/- 10s error) at a coupling point that was about 12 nmi from the runway threshold. Two variables were explored for the pilot participants: two levels of flight deck automation (current-day flight deck automation and auto speed control future automation) as well as two flight deck displays that assisted in pilot conformance monitoring. The controllers were also provided with automation to help create and maintain aircraft pairs. Results show the operations in this study were acceptable and safe. Subjective workload, when using the pairing procedures and tools, was generally low for both controllers and pilots, and situation awareness was typically moderate to high. Pilot workload was influenced by display type and automation condition. Further research on pairing and off-nominal conditions is required however, this investigation identified promising findings about the feasibility of closely-spaced parallel runway operations.

  20. Seniority zero pair coupled cluster doubles theory.

    PubMed

    Stein, Tamar; Henderson, Thomas M; Scuseria, Gustavo E

    2014-06-07

    Coupled cluster theory with single and double excitations accurately describes weak electron correlation but is known to fail in cases of strong static correlation. Fascinatingly, however, pair coupled cluster doubles (p-CCD), a simplified version of the theory limited to pair excitations that preserve the seniority of the reference determinant (i.e., the number of unpaired electrons), has mean field computational cost and is an excellent approximation to the full configuration interaction (FCI) of the paired space provided that the orbital basis defining the pairing scheme is adequately optimized. In previous work, we have shown that optimization of the pairing scheme in the seniority zero FCI leads to a very accurate description of static correlation. The same conclusion extends to p-CCD if the orbitals are optimized to make the p-CCD energy stationary. We here demonstrate these results with numerous examples. We also explore the contributions of different seniority sectors to the coupled cluster doubles (CCD) correlation energy using different orbital bases. We consider both Hartree-Fock and Brueckner orbitals, and the role of orbital localization. We show how one can pair the orbitals so that the role of the Brueckner orbitals at the CCD level is retained at the p-CCD level. Moreover, we explore ways of extending CCD to accurately describe strongly correlated systems.

  1. Association of the bovine leukocyte antigen major histocompatibility complex class II DRB3*4401 allele with host resistance to the Lone Star tick, Amblyomma americanum.

    PubMed

    Untalan, Pia M; Pruett, John H; Steelman, C Dayton

    2007-04-10

    The MHC of cattle, known as the bovine leukocyte antigen (BoLA) complex, plays an integral role in disease and parasite susceptibility, and immune responsiveness of the host. While susceptibility to tick infestation in cattle is believed to be heritable, genes that may be responsible for the manifestation of this phenotype remain elusive. In an effort to analyze the role that genes within the BoLA complex may play in host resistance to ticks, we have evaluated components of this system within a herd of cattle established at our laboratory that has been phenotyped for ectoparasite susceptibility. Of three microsatellite loci within the BoLA complex analyzed, alleles of two microsatellite loci within the BoLA class IIa cluster (DRB1-118 and DRB3-174) associated with the tick-resistant phenotype, prompting further investigation of gene sequences within the DRB3 region. DRB3 is a class IIa gene, the second exon of which is highly polymorphic since it encodes the antigen recognition site of the DR class II molecule. Analysis of the second exon of the DRB3 gene from the phenotyped calves in our herd revealed a significant association between the DRB3*4401 allele and the tick-resistant phenotype. To our knowledge, this is the first report of a putative association between a class IIa DRB3 sequence and host resistance to the Lone Star tick. Elucidation of the mechanism involved in tick resistance will contribute to improving breeding schemes for parasite resistance, which will be beneficial to the cattle industry.

  2. Frustrated Lewis pairs: from concept to catalysis.

    PubMed

    Stephan, Douglas W

    2015-02-17

    CONSPECTUS: Frustrated Lewis pair (FLP) chemistry has emerged in the past decade as a strategy that enables main-group compounds to activate small molecules. This concept is based on the notion that combinations of Lewis acids and bases that are sterically prevented from forming classical Lewis acid-base adducts have Lewis acidity and basicity available for interaction with a third molecule. This concept has been applied to stoichiometric reactivity and then extended to catalysis. This Account describes three examples of such developments: hydrogenation, hydroamination, and CO2 reduction. The most dramatic finding from FLP chemistry was the discovery that FLPs can activate H2, thus countering the long-existing dogma that metals are required for such activation. This finding of stoichiometric reactivity was subsequently evolved to employ simple main-group species as catalysts in hydrogenations. While the initial studies focused on imines, subsequent studies uncovered FLP catalysts for a variety of organic substrates, including enamines, silyl enol ethers, olefins, and alkynes. Moreover, FLP reductions of aromatic anilines and N-heterocycles have been developed, while very recent extensions have uncovered the utility of FLP catalysts for ketone reductions. FLPs have also been shown to undergo stoichiometric reactivity with terminal alkynes. Typically, either deprotonation or FLP addition reaction products are observed, depending largely on the basicity of the Lewis base. While a variety of acid/base combinations have been exploited to afford a variety of zwitterionic products, this reactivity can also be extended to catalysis. When secondary aryl amines are employed, hydroamination of alkynes can be performed catalytically, providing a facile, metal-free route to enamines. In a similar fashion, initial studies of FLPs with CO2 demonstrated their ability to capture this greenhouse gas. Again, modification of the constituents of the FLP led to the discovery of reaction

  3. Synthesis, structural study and biological activity of new derivatives of chrysin containing a 2-mercaptopyridyl or 5-(trifluoromethyl)-2-mercaptopyridyl fragments

    NASA Astrophysics Data System (ADS)

    Valdez-Calderón, Alejandro; González-Montiel, Simplicio; Martínez-Otero, Diego; Martínez-Torres, Ataulfo; Vásquez-Pérez, José Manuel; Molina-Vera, Carlos; Torres-Valencia, J. Martín; Alvarado-Rodríguez, José G.; Cruz-Borbolla, Julian

    2016-04-01

    New derivatives of chrysin containing 2-mercaptopyridine (2a-2e) or 5-(trifluoromethyl)-2-mercaptopyridine (3a-3e) moieties were prepared from the reaction between bromides (1a-1e) and 2-mercaptopyridine or 5-(trifluoromethyl)-2-mercaptopyridine, respectively. Their structures were elucidated by NMR, IR and elemental analysis. The molecular structure of compounds 1a, 1c-1e, 2b-2e and 3a was determined by single-crystal X-ray diffraction studies. All rings in these structures are nearly coplanar and they showed an intramolecular hydrogen bond between the phenolic hydroxyl H atom and the carbonyl O atom that forms a six membered ring. The crystal packing also showed a wide variety of intermolecular contacts such as C-H⋯A, π-π, C-H⋯π and lone pair⋯π interactions which were supported by quantum theory of atoms in molecules (QTAIM), Hirshfeld surface, and fingerprint plot analyses. Biological activity of all compounds was tested in growth assays of the nematode Caenorhabiditis elegans. Compounds 2e, 3b and 3c inhibited larval development.

  4. Induced spectral gap and pairing correlations from superconducting proximity effect

    NASA Astrophysics Data System (ADS)

    Chiu, Ching-Kai; Cole, William S.; Das Sarma, S.

    2016-09-01

    We theoretically consider superconducting proximity effect, using the Bogoliubov-de Gennes (BdG) theory, in heterostructure sandwich-type geometries involving a normal s -wave superconductor and a nonsuperconducting material with the proximity effect being driven by Cooper pairs tunneling from the superconducting slab to the nonsuperconducting slab. Applications of the superconducting proximity effect may rely on an induced spectral gap or induced pairing correlations without any spectral gap. We clarify that in a nonsuperconducting material the induced spectral gap and pairing correlations are independent physical quantities arising from the proximity effect. This is a crucial issue in proposals to create topological superconductivity through the proximity effect. Heterostructures of three-dimensional topological insulator (TI) slabs on conventional s -wave superconductor (SC) substrates provide a platform, with proximity-induced topological superconductivity expected to be observed on the "naked" top surface of a thin TI slab. We theoretically study the induced superconducting gap on this naked surface. In addition, we compare against the induced spectral gap in heterostructures of SC with a normal metal or a semiconductor with strong spin-orbit coupling and a Zeeman splitting potential (another promising platform for topological superconductivity). We find that for any model for the non-SC metal (including metallic TI) the induced spectral gap on the naked surface decays as L-3 as the thickness (L ) of the non-SC slab is increased in contrast to the slower 1 /L decay of the pairing correlations. Our distinction between proximity-induced spectral gap (with its faster spatial decay) and pairing correlation (with its slower spatial decay) has important implications for the currently active search for topological superconductivity and Majorana fermions in various superconducting heterostructures.

  5. The Role of Aromaticity, Hybridization, Electrostatics, and Covalency in Resonance-Assisted Hydrogen Bonds of Adenine–Thymine (AT) Base Pairs and Their Mimics

    PubMed Central

    Guillaumes, Laia; Simon, Sílvia; Fonseca Guerra, Célia

    2015-01-01

    Invited for this issues cover are Dr. Célia Fonseca Guerra from the VU University of Amsterdam and her collaborators at the University of Girona. The cover picture shows H-bonds in the adenine–thymine Watson–Crick base pair. An essential part of these H-bonds is their covalent component arising from donor–acceptor interactions between N or O lone pairs and the N−H antibonding σ* acceptor orbital. This charge-transfer interaction is represented by green figures walking on the pedestrian crossing, connecting the bases. This covalent component is the reason why H-bonds between DNA and/or unsaturated model bases are significantly stronger than those between analogous saturated bases. This contrasts sharply with the classical picture of predominantly electrostatic H-bonds which is not only incomplete in terms of a proper bonding mechanism, but also fails to explain the trend in stability. For more details, see the Full Paper on p. 318 ff. PMID:26246979

  6. Geometrical parameters of E+S pairs

    NASA Technical Reports Server (NTRS)

    Rampazzo, Roberto; Sulentic, Jack W.

    1990-01-01

    Local environmental conditions (i.e., density and angular momentum properties of protogalactic clouds) are thought to be factors affecting the ultimate morphology of a galaxy. The existence of significant numbers of mixed morphology (E/SO+S) pairs of galaxies would represent a direct challenge to this idea unless all early-type components are formed by mergers. The authors wished to isolate candidate E+S pairs for detailed study. The authors have observed 22 pairs of mixed morphology galaxies (containing at least one early-type component) selected from a catalog of Sulentic (1988: unpublished) based upon the ESO sky survey. The observed sample and relevant morphological and interaction characteristics are summarized in tabular form. The authors report the relevant geometrical properties of the galaxies in another table. They list the maximum values measured for the ellipticity and the a(4)/a shape parameter together with the total measured twisting along the profile beyond the seeing disk (they set an inner limit of 3 arcsed). An asterisk indicates objects in which a(4)/a is neither predominantly boxy nor disky. They found a large number of true mixed pairs with 13/22 E+S pairs in the present sample. The remaining objects include 5 disk pairs (composed of SO and S members) and 3 early-type pairs comprising E and SO members. They estimate that between 25 and 50 percent of the pairs in any complete sample will be of the E+S type. This suggests that 100 to 200 such pairs exist on the sky brighter than m sub pg = 16.0. They found no global evidence for a difference between E members of this sample and those in more general samples (e.g., Bender et al. 1989). In particular, they found that about 30 percent of the early-type galaxies cannot be classified either predominantly boxy or disky because the a(4)/a profile shows both of these features at a comparable level or does not show any significant trend. Isophotal twisting is observed with a range and distribution

  7. Theoretical study of pair density wave superconductors

    NASA Astrophysics Data System (ADS)

    Zheng, Zhichao

    In conventional superconductors, the Cooper pairs are formed from quasiparticles. We explore another type of superconducting state, a pair density wave (PDW) order, which spontaneously breaks some of the translational and point group symmetries. In a PDW superconductor, the order parameter is a periodic function of the center-of-mass coordinate, and the spatial average value of the superconducting order parameter vanishes. In the early 1960s, following the success of the BCS theory of superconductivity, Fulde and Ferrell and Larkin and Ovchinnikov (FFLO) developed theories of inhomogeneous superconducting states. Because of this Zeeman splitting in a magnetic field, the Cooper pairs having a nonzero center-of-mass momentum are more stable than the normal pairing, leading to the FFLO state. Experiments suggest possible occurrence of the FFLO state in the heavy-fermion compound CeCoIn5, and in quasi-low-dimensional organic superconductors. FFLO phases have also been argued to be of importance in understanding ultracold atomic Fermi gases and in the formation of color superconductivity in high density quark matter. In all Fermi superfluids known at the present time, Cooper pairs are composed of particles with spin 1/2. The spin component of a pair wave function can be characterized by its total spin S = 0 (singlet) and S = 1 (triplet). In the discovered broken inversion superconductors CePt3Si, Li2Pt3B, and Li2Pd3B, the magnetic field leads to novel inhomogeneous superconducting states, namely the helical phase and the multiple-q phase. Its order parameter exhibits periodicity similar to FFLO phase, and the consequences of both phases are same: the enhancement of transition temperature as a function of magnetic field. We have studied the PDW phases in broken parity superconductors with vortices included. By studying PDW vortex states, we find the usual Abrikosov vortex solution is unstable against a new solution with fractional vortex pairs. We have also studied the

  8. Repellency of the Origanum onites L. essential oil and constituents to the lone star tick and yellow fever mosquito.

    PubMed

    Carroll, John F; Demirci, Betul; Kramer, Matthew; Bernier, Ulrich R; Agramonte, Natasha M; Baser, K Husnu Can; Tabanca, Nurhayat

    2017-02-16

    The oregano, Origanum onites L., essential oil (EO) was tested in laboratory behavioural bioassays for repellent activity against Amblyomma americanum (L.) and Aedes aegypti (L.). The O. onites EO was characterised using GC-FID and GC-MS. Carvacrol (75.70%), linalool (9.0%), p-cymene (4.33%) and thymol (1.9%) were the most abundant compounds. At a concentration of 0.413 mg oil/cm(2) of filter paper, O. onites EO repelled 100% of the ticks tested and at 0.103 mg oil/cm(2) of filter paper, 66.7% of the ticks were repelled. At 0.075 mg oil/cm(2) filter paper, thymol repelled 66.7% of the ticks compared to 28.7% by carvacrol at that same concentration. Against Ae. aegypti, O. onites EO was repellent at the minimum effective dosage (MED) of 0.011 (±0.00) mg/cm(2) in the cloth patch assay compared to the reference control, N,N-dimethyl-3-methylbenzamide (DEET) with a MED = 0.007 ± (0.003) mg/cm(2).

  9. Pairing in a dry Fermi sea

    SciTech Connect

    Maier, Thomas A.; Staar, Peter; Mishra, V.; Chatterjee, Utpal; Campuzano, J. C.; Scalapino, Douglas J.

    2016-06-17

    In the traditional Bardeen–Cooper–Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and -k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. In this paper, we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. Finally, in contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin–fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability.

  10. Pairing and specific heat in hot nuclei

    NASA Astrophysics Data System (ADS)

    Gambacurta, Danilo; Lacroix, Denis; Sandulescu, N.

    2013-09-01

    The thermodynamics of pairing phase-transition in nuclei is studied in the canonical ensemble and treating the pairing correlations in a finite-temperature variation after projection BCS approach (FT-VAP). Due to the restoration of particle number conservation, the pairing gap and the specific heat calculated in the FT-VAP approach vary smoothly with the temperature, indicating a gradual transition from the superfluid to the normal phase, as expected in finite systems. We have checked that the predictions of the FT-VAP approach are very accurate when compared to the results obtained by an exact diagonalization of the pairing Hamiltonian. The influence of pairing correlations on specific heat is analyzed for the isotopes 161,162Dy and 171,172Yb. It is shown that the FT-VAP approach, applied with a level density provided by mean field calculations and supplemented, at high energies, by the level density of the back-shifted Fermi gas model, can approximate reasonably well the main properties of specific heat extracted from experimental data. However, the detailed shape of the calculated specific heat is rather sensitive to the assumption made for the mean field.

  11. Pairing instabilities of Dirac composite fermions

    NASA Astrophysics Data System (ADS)

    Milovanović, M. V.; Ćirić, M. Dimitrijević; Juričić, V.

    2016-09-01

    Recently, a Dirac (particle-hole symmetric) description of composite fermions in the half-filled Landau level (LL) was proposed [D. T. Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027], and we study its possible consequences on BCS (Cooper) pairing of composite fermions (CFs). One of the main consequences is the existence of anisotropic states in single-layer and bilayer systems, which was previously suggested in Jeong and Park [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015), 10.1103/PhysRevB.91.195119]. We argue that in the half-filled LL in the single-layer case the gapped states may sustain anisotropy, because isotropic pairings may coexist with anisotropic ones. Furthermore, anisotropic pairings with the addition of a particle-hole symmetry-breaking mass term may evolve into rotationally symmetric states, i.e., Pfaffian states of Halperin-Lee-Read (HLR) ordinary CFs. On the basis of the Dirac formalism, we argue that in the quantum Hall bilayer at total filling factor 1, with decreasing distance between the layers, weak pairing of p -wave paired CFs is gradually transformed from Dirac to ordinary, HLR-like, with a concomitant decrease in the CF number. Global characterization of low-energy spectra based on the Dirac CFs agrees well with previous calculations performed by exact diagonalization on a torus. Finally, we discuss features of the Dirac formalism when applied in this context.

  12. On the analysis of phylogenetically paired designs

    PubMed Central

    Funk, Jennifer L; Rakovski, Cyril S; Macpherson, J Michael

    2015-01-01

    As phylogenetically controlled experimental designs become increasingly common in ecology, the need arises for a standardized statistical treatment of these datasets. Phylogenetically paired designs circumvent the need for resolved phylogenies and have been used to compare species groups, particularly in the areas of invasion biology and adaptation. Despite the widespread use of this approach, the statistical analysis of paired designs has not been critically evaluated. We propose a mixed model approach that includes random effects for pair and species. These random effects introduce a “two-layer” compound symmetry variance structure that captures both the correlations between observations on related species within a pair as well as the correlations between the repeated measurements within species. We conducted a simulation study to assess the effect of model misspecification on Type I and II error rates. We also provide an illustrative example with data containing taxonomically similar species and several outcome variables of interest. We found that a mixed model with species and pair as random effects performed better in these phylogenetically explicit simulations than two commonly used reference models (no or single random effect) by optimizing Type I error rates and power. The proposed mixed model produces acceptable Type I and II error rates despite the absence of a phylogenetic tree. This design can be generalized to a variety of datasets to analyze repeated measurements in clusters of related subjects/species. PMID:25750719

  13. Pairing in a dry Fermi sea

    PubMed Central

    Maier, T. A; Staar, P.; Mishra, V.; Chatterjee, U.; Campuzano, J. C.; Scalapino, D. J.

    2016-01-01

    In the traditional Bardeen–Cooper–Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and −k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. Here we report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. In contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin–fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability. PMID:27312569

  14. Terminal Area Procedures for Paired Runways

    NASA Technical Reports Server (NTRS)

    Lozito, Sandy

    2011-01-01

    Parallel Runway operations have been found to increase capacity within the National Airspace (NAS) however, poor visibility conditions reduce this capacity [1]. Much research has been conducted to examine the concepts and procedures related to parallel runways however, there has been no investigation of the procedures associated with the strategic and tactical pairing of aircraft for these operations. This study developed and examined the pilot and controller procedures and information requirements for creating aircraft pairs for parallel runway operations. The goal was to achieve aircraft pairing with a temporal separation of 15s(+/- 10s error) at a coupling point that is about 12 nmi from the runway threshold. Two variables were explored for the pilot participants: Two levels of flight deck automation (current-day flight deck automation, and a prototype future automation) as well as two flight deck displays that assisted in pilot conformance monitoring. The controllers were also provided with automation to help create and maintain aircraft pairs. Data showed that the operations in this study were found to be acceptable and safe. Workload when using the pairing procedures and tools was generally low for both controllers and pilots, and situation awareness (SA) was typically moderate to high. There were some differences based upon the display and automation conditions for the pilots. Future research should consider the refinement of the concepts and tools for pilot and controller displays and automation for parallel runway concepts.

  15. Pairing in a dry Fermi sea

    DOE PAGES

    Maier, Thomas A.; Staar, Peter; Mishra, V.; ...

    2016-06-17

    In the traditional Bardeen–Cooper–Schrieffer theory of superconductivity, the amplitude for the propagation of a pair of electrons with momentum k and -k has a log singularity as the temperature decreases. This so-called Cooper instability arises from the presence of an electron Fermi sea. It means that an attractive interaction, no matter how weak, will eventually lead to a pairing instability. However, in the pseudogap regime of the cuprate superconductors, where parts of the Fermi surface are destroyed, this log singularity is suppressed, raising the question of how pairing occurs in the absence of a Fermi sea. In this paper, wemore » report Hubbard model numerical results and the analysis of angular-resolved photoemission experiments on a cuprate superconductor. Finally, in contrast to the traditional theory, we find that in the pseudogap regime the pairing instability arises from an increase in the strength of the spin–fluctuation pairing interaction as the temperature decreases rather than the Cooper log instability.« less

  16. Probing the tides in interacting galaxy pairs

    NASA Technical Reports Server (NTRS)

    Borne, Kirk D.

    1990-01-01

    Detailed spectroscopic and imaging observations of colliding elliptical galaxies revealed unmistakable diagnostic signatures of the tidal interactions. It is possible to compare both the distorted luminosity distributions and the disturbed internal rotation profiles with numerical simulations in order to model the strength of the tidal gravitational field acting within a given pair of galaxies. Using the best-fit numerical model, one can then measure directly the mass of a specific interacting binary system. This technique applies to individual pairs and therefore complements the classical methods of measuring the masses of galaxy pairs in well-defined statistical samples. The 'personalized' modeling of galaxy pairs also permits the derivation of each binary's orbit, spatial orientation, and interaction timescale. Similarly, one can probe the tides in less-detailed observations of disturbed galaxies in order to estimate some of the physical parameters for larger samples of interacting galaxy pairs. These parameters are useful inputs to the more universal problems of (1) the galaxy merger rate, (2) the strength and duration of the driving forces behind tidally stimulated phenomena (e.g., starbursts and maybe quasi steller objects), and (3) the identification of long-lived signatures of interaction/merger events.

  17. A photochemical activation scheme of inert dinitrogen by dinuclear Ru(II) and Fe(II) complexes.

    PubMed

    Reiher, Markus; Kirchner, Barbara; Hutter, Jürg; Sellmann, Dieter; Hess, Bernd Artur

    2004-09-20

    A general photochemical activation process of inert dinitrogen coordinated to two metal centers is presented on the basis of high-level DFT and ab initio calculations. The central feature of this activation process is the occupation of an antibonding pi* orbital upon electronic excitation from the singlet ground state S0 to the first excited singlet state S1. Populating the antibonding LUMO weakens the triple bond of dinitrogen. After a vertical excitation, the excited complex may structurally relax in the S1 state and approaches its minimum structure in the S1 state. This excited-state minimum structure features the dinitrogen bound in a diazenoid form, which exhibits a double bond and two lone pairs localized at the two nitrogen atoms, ready to be protonated. Reduction and de-excitation then yield the corresponding diazene complex; its generation represents the essential step in a nitrogen fixation and reduction protocol. The consecutive process of excitation, protonation, and reduction may be rearranged in any experimentally appropriate order. The protons needed for the reaction from dinitrogen to diazene can be provided by the ligand sphere of the complexes, which contains sulfur atoms acting as proton acceptors. These protonated thiolate functionalities bring protons close to the dinitrogen moiety. Because protonation does not change the pi*-antibonding character of the LUMO, the universal and well-directed character of the photochemical activation process makes it possible to protonate the dinitrogen complex before it is irradiated. The pi*-antibonding LUMO plays the central role in the activation process, since the diazenoid structure was obtained by excitation from various occupied orbitals as well as by a direct two-electron reduction (without photochemical activation) of the complex; that is, the important bending of N2 towards a diazenoid conformation can be achieved by populating the pi*-antibonding LUMO.

  18. Guanine- 5-carboxylcytosine base pairs mimic mismatches during DNA replication.

    PubMed

    Shibutani, Toshihiro; Ito, Shinsuke; Toda, Mariko; Kanao, Rie; Collins, Leonard B; Shibata, Marika; Urabe, Miho; Koseki, Haruhiko; Masuda, Yuji; Swenberg, James A; Masutani, Chikahide; Hanaoka, Fumio; Iwai, Shigenori; Kuraoka, Isao

    2014-06-09

    The genetic information encoded in genomes must be faithfully replicated and transmitted to daughter cells. The recent discovery of consecutive DNA conversions by TET family proteins of 5-methylcytosine into 5-hydroxymethylcytosine, 5-formylcytosine, and 5-carboxylcytosine (5caC) suggests these modified cytosines act as DNA lesions, which could threaten genome integrity. Here, we have shown that although 5caC pairs with guanine during DNA replication in vitro, G·5caC pairs stimulated DNA polymerase exonuclease activity and were recognized by the mismatch repair (MMR) proteins. Knockdown of thymine DNA glycosylase increased 5caC in genome, affected cell proliferation via MMR, indicating MMR is a novel reader for 5caC. These results suggest the epigenetic modification products of 5caC behave as DNA lesions.

  19. Hard Photodisintegration of a Proton Pair

    DOE PAGES

    Pomerantz, Ishay; Bubis, Nathaniel; Allada, Kalyan; ...

    2010-01-08

    We present the first study of high energy photodisintegration of proton-pairs through the gamma + 3He -> p+p+n channel. Photon energies from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. An s^{-11} scaling of the cross section was observed, as predicted by the constituent counting rule. The onset of the scaling is at a higher energy and the cross section is significantly lower then for pn pair photodisintegration. For photon energies below the scaling region, the scaled cross section was found to present a strongmore » energy-dependent structure not observed in deuteron photodisintegration.« less

  20. Pairing dynamics and the origin of species

    PubMed Central

    Puebla, Oscar; Bermingham, Eldredge; Guichard, Frédéric

    2012-01-01

    Whether sexual selection alone can drive the evolution of assortative mating in the presence of gene flow is a long-standing question in evolutionary biology. Here, we report a role for pairing dynamics of individuals when mate choice is mutual, which is sufficient for the evolution of assortative mating by sexual selection alone in the presence of gene flow. Through behavioural observation, individual-based simulation and population genetic analysis, we evaluate the pairing dynamics of coral reef fish in the genus Hypoplectrus (Serranidae), and the role these dynamics can play for the evolution of assortative mating. When mate choice is mutual and the stability of mating pairs is critical for reproductive success, the evolution of assortative mating in the presence of gene flow is not only possible, but is also a robust evolutionary outcome. PMID:21937496

  1. ION PAIR DISSOCIATION: Spectroscopy and Dynamics

    NASA Astrophysics Data System (ADS)

    Suits, Arthur G.; Hepburn, John W.

    2006-05-01

    Ion pair dissociation processes may be studied using coherent vacuum ultraviolet laser sources in a manner entirely analogous to photoelectron spectroscopy, albeit with the anion playing the role of a heavy electron. If the excitation energy is above the dissociation energy and the kinetic energy of the fragment is measured using ion imaging, this approach is termed ion pair imaging spectroscopy (IPIS) and is related to conventional photoelectron spectroscopy. If the excitation energy is just below the dissociation energy and pulsed-field dissociation is employed, this approach is analogous to mass analyzed threshold ionization (MATI) spectroscopy and is termed threshold ion pair production spectroscopy (TIPPS). These approaches provide a novel means of investigating ion thermochemistry and spectroscopy and superexcited state decay dynamics at high resolution.

  2. The inverse problem for Schwinger pair production

    NASA Astrophysics Data System (ADS)

    Hebenstreit, Florian

    2016-02-01

    The production of electron-positron pairs in time-dependent electric fields (Schwinger mechanism) depends non-linearly on the applied field profile. Accordingly, the resulting momentum spectrum is extremely sensitive to small variations of the field parameters. Owing to this non-linear dependence it is so far unpredictable how to choose a field configuration such that a predetermined momentum distribution is generated. We show that quantum kinetic theory along with optimal control theory can be used to approximately solve this inverse problem for Schwinger pair production. We exemplify this by studying the superposition of a small number of harmonic components resulting in predetermined signatures in the asymptotic momentum spectrum. In the long run, our results could facilitate the observation of this yet unobserved pair production mechanism in quantum electrodynamics by providing suggestions for tailored field configurations.

  3. Pairing dynamics and the origin of species.

    PubMed

    Puebla, Oscar; Bermingham, Eldredge; Guichard, Frédéric

    2012-03-22

    Whether sexual selection alone can drive the evolution of assortative mating in the presence of gene flow is a long-standing question in evolutionary biology. Here, we report a role for pairing dynamics of individuals when mate choice is mutual, which is sufficient for the evolution of assortative mating by sexual selection alone in the presence of gene flow. Through behavioural observation, individual-based simulation and population genetic analysis, we evaluate the pairing dynamics of coral reef fish in the genus Hypoplectrus (Serranidae), and the role these dynamics can play for the evolution of assortative mating. When mate choice is mutual and the stability of mating pairs is critical for reproductive success, the evolution of assortative mating in the presence of gene flow is not only possible, but is also a robust evolutionary outcome.

  4. Pair production in superstrong magnetic fields

    NASA Technical Reports Server (NTRS)

    Daugherty, J. K.; Harding, A. K.

    1983-01-01

    The production of electron-positron pairs by single photons in magnetic fields 10 to the twelth power G was investigated in detail for photon energies near threshold as well as for the asymptotic limit of high photon energy. The exact attenuation coefficient, which is derived and then evaluated numerically, is strongly influenced by the discrete energy states of the electron and positron. Near threshold, it exhibits a sawtooth pattern as a function of photon energy, and its value is significantly below that predicted by the asymptotic expression for the attenuation coefficient. The energy distributions of the created pair are computed numerically near threshold and analytic expressions are derived in the asymptotic limit. These results indicate that as field strength and photon energy increase, it becomes increasingly probable for the pair to divide the photon energy unequally. This effect, as well as the threshold behavior of the attenuation coefficient, could have important consequences for pulsar models.

  5. Hard photodisintegration of a proton pair

    NASA Astrophysics Data System (ADS)

    Pomerantz, I.; Bubis, N.; Allada, K.; Beck, A.; Beck, S.; Berman, B. L.; Boeglin, W.; Camsonne, A.; Canan, M.; Chirapatpimol, K.; Cisbani, E.; Cusanno, F.; de Jager, C. W.; Dutta, C.; Garibaldi, F.; Geagla, O.; Gilman, R.; Glister, J.; Higinbotham, D. W.; Jiang, X.; Katramatou, A. T.; Khrosinkova, E.; Lee, B. W.; LeRose, J. J.; Lindgren, R.; McCullough, E.; Meekins, D.; Michaels, R.; Moffit, B.; Petratos, G. G.; Piasetzky, E.; Qian, X.; Qiang, Y.; Rodriguez, I.; Ron, G.; Saha, A.; Sarty, A. J.; Sawatzky, B.; Schulte, E.; Shneor, R.; Sparveris, N.; Subedi, R.; Strauch, S.; Sulkosky, V.; Wang, Y.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Zhan, X.; Zheng, X.

    2010-02-01

    We present a study of high energy photodisintegration of proton-pairs through the γ+He3→p+p+n channel. Photon energies, Eγ, from 0.8 to 4.7 GeV were used in kinematics corresponding to a proton pair with high relative momentum and a neutron nearly at rest. The s scaling of the cross section, as predicted by the constituent counting rule for two nucleon photodisintegration, was observed for the first time. The onset of the scaling is at a higher energy and the cross section is significantly lower than for deuteron (pn pair) photodisintegration. For Eγ below the scaling region, the scaled cross section was found to present a strong energy-dependent structure not observed in deuteron photodisintegration.

  6. Cooper-pair splitter: towards an efficient source of spin-entangled EPR pairs

    NASA Astrophysics Data System (ADS)

    Schonenberger, Christian

    2011-03-01

    In quantum mechanics the properties of two and more particles can be entangled. In basic science pairs of entangled particles, so called Einstein-Podolsky-Rosen (EPR) pairs, play a special role as toy objects for fundamental studies. They provide such things as ``spooky interaction at distance,'' but they also enable secure encoding and teleportation and are thus important for applications in quantum information technology. Whereas EPR pairs of photons can be generated by parametric down conversion (PDC) in a crystal, a similar source for EPR pairs of electrons does not exists yet. In several theory papers, it has been suggested to use a superconductor for this purpose. The superconducting ground state is formed by a condensate of Cooper-pairs which are electron pairs in a spin-singlet state. Since there are many Cooper pairs in a metallic superconductor like Al, the main tasks are to extract Cooper pairs one by one and to split them into different arms. A controlled and efficient splitting is possible if one makes use of Coulomb interaction. This has recently be demonstrated by two groups [2-4] using hybrid quantum-dot devices with both superconducting and normal metal contacts. In the present talk, I will discuss the Cooper-pair splitter results from the Basel-Budapest-Copenhagen team and compare with the other experiments. As an outlook we discuss approaches that aim at entanglement detection. The Cooper pair splitter holds great promises because very large splitting efficiencies approaching 100% and large pair current rates appear feasible. This work has been done by L. Hofstetter, S. Csonka, A. Geresdi, M. Aagesen, J. Nygard and C. Schönenberger

  7. Variability in the amount of homoeologous pairing among F1 hybrids

    PubMed Central

    Poggio, Lidia; Greizerstein, Eduardo; Ferrari, María

    2016-01-01

    Genes involved in the exclusive pairing of homologous chromosomes have been described in several polyploid species but little is known about the activity of these genes in diploids (which have only one dose of each homoeologous genome). Analysis of the meiotic behaviour of species, natural and artificial hybrids and polyploids of Glandularia suggests that, in allopolyploids where homoeologous genomes are in two doses, regulator genes prevent homoeologous pairing. The different meiotic phenotypes in diploid F1 hybrids between Glandularia pulchella and Glandularia incisa strongly suggest that these pairing regulator genes possess an incomplete penetrance when homoeologous genomes are in only one dose. Moreover, the meiotic analysis of natural and artificial F1 hybrids suggests that the genetic constitution of parental species influences the activity of pairing regulator genes and is mainly responsible for variability in the amount of homoeologous pairing observed in diploid hybrids. In Glandularia, the pairing regulator genes originated in South American diploid species. The cytogenetic characteristics of this genus make it a good model to analyse and explore in greater depth the activity of pairing regulator genes at different ploidy levels. PMID:27255515

  8. Spontaneous pairing and cooperative movements of micro-particles in a two dimensional plasma crystal

    SciTech Connect

    Zhdanov, S. K.; Couëdel, L.; Nosenko, V.; Thomas, H. M.; Morfill, G. E.

    2015-05-15

    In an argon plasma of 20 W rf discharge at a pressure of 1.38 Pa, a stable highly ordered monolayer of microparticles is suspended. We observe spontaneous particle pairing when suddenly reducing the gas pressure. Special types of dynamical activity, in particular, entanglement and cooperative movements of coupled particles have been registered. In the course of the experiment first appeared single vertical pairs of particles, in further they gradually accumulated causing melting of the entire crystal. To record pairing events, the particle suspension is side-view imaged using a vertically extended laser sheet. The long-lasting pre-melting phase assured the credible recording and identification of isolated particle pairs. The high monolayer charge density is crucial to explain the spontaneous pairing events observed in our experiments as the mutual repulsion between the particles comprising the monolayer make its vertical extend thicker.

  9. Age-dependent trajectories differ between within-pair and extra-pair paternity success.

    PubMed

    Hsu, Y-H; Simons, M J P; Schroeder, J; Girndt, A; Winney, I S; Burke, T; Nakagawa, S

    2017-02-24

    Reproductive success is associated with age in many taxa, increasing in early life followed by reproductive senescence. In socially monogamous but genetically polygamous species, this generates the interesting possibility of differential trajectories of within-pair and extra-pair siring success with age in males. We investigate these relationships simultaneously using within-individual analyses with 13 years of data from an insular house sparrow (Passer domesticus) population. As expected, we found that both within- and extra-pair paternity success increased with age, followed by a senescence-like decline. However, the age trajectories of within- and extra-pair paternity successes differed significantly, with the extra-pair paternity success increasing faster, although not significantly, in early life, and showing a delayed decline by 1.5 years on average later in life compared to within-pair paternity success. These different trajectories indicate that the two alternative mating tactics should have age-dependent pay-offs. Males may partition their reproductive effort between within- and extra-pair matings depending on their current age to reap the maximal combined benefit from both strategies. The interplay between these mating strategies and age-specific mortality may explain the variation in rates of extra-pair paternity observed within and between species.

  10. Paired Learning: Tutoring by Non-Teachers. Incorporating "The Paired Reading Bulletin" No. 5.

    ERIC Educational Resources Information Center

    Paired Reading Bulletin, 1989

    1989-01-01

    The eight papers constituting the Proceedings of the fourth National Paired Reading Conference are published in an annual bulletin of the Paired Reading Project, together with seven papers constituting the Supplementary Proceedings of the Peer Tutoring Conference, and nine feature articles, as follows: (1) "Whole-School Policy on Parental…

  11. Communication: Multipole approximations of distant pair energies in local correlation methods with pair natural orbitals

    NASA Astrophysics Data System (ADS)

    Werner, Hans-Joachim

    2016-11-01

    The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.

  12. Communication: Multipole approximations of distant pair energies in local correlation methods with pair natural orbitals.

    PubMed

    Werner, Hans-Joachim

    2016-11-28

    The accuracy of multipole approximations for distant pair energies in local second-order Møller-Plesset perturbation theory (LMP2) as introduced by Hetzer et al. [Chem. Phys. Lett. 290, 143 (1998)] is investigated for three chemical reactions involving molecules with up to 92 atoms. Various iterative and non-iterative approaches are compared, using different energy thresholds for distant pair selection. It is demonstrated that the simple non-iterative dipole-dipole approximation, which has been used in several recent pair natural orbitals (PNO)-LMP2 and PNO-LCCSD (local coupled-cluster with singles and doubles) methods, may underestimate the distant pair energies by up to 50% and can lead to significant errors in relative energies, unless very tight thresholds are used. The accuracy can be much improved by including higher multipole orders and by optimizing the distant pair amplitudes iteratively along with all other amplitudes. A new approach is presented in which very small special PNO domains for distant pairs are used in the iterative approach. This reduces the number of distant pair amplitudes by 3 orders of magnitude and keeps the additional computational effort for the iterative optimization of distant pair amplitudes minimal.

  13. Extracting an entangled photon pair from collectively decohered pairs at a telecommunication wavelength.

    PubMed

    Tsujimoto, Yoshiaki; Sugiura, Yukihiro; Ando, Makoto; Katsuse, Daisuke; Ikuta, Rikizo; Yamamoto, Takashi; Koashi, Masato; Imoto, Nobuyuki

    2015-05-18

    We experimentally demonstrated entanglement extraction scheme by using photons at the telecommunication band for optical-fiber-based quantum communications. We generated two pairs of non-degenerate polarization entangled photons at 780 nm and 1551 nm by spontaneous parametric down-conversion and distributed the two photons at 1551 nm through a collective phase damping channel which gives the same amount of random phase shift on the two photons. Through local operation and classical communication, we extracted an entangled photon pair from two phase-disturbed photon pairs. An observed fidelity of the extracted photon pair to a maximally entangled photon pair was 0.73 ± 0.07 which clearly shows the recovery of entanglement.

  14. Oxytocin-like receptors mediate pair bonding in a socially monogamous songbird

    PubMed Central

    Klatt, James D.; Goodson, James L.

    2013-01-01

    Although many species form socially monogamous pair bonds, relevant neural mechanisms have been described for only a single species, the prairie vole (Microtus ochrogaster). In this species, pair bonding is strongly dependent upon the nonapeptides oxytocin (OT) and vasopressin, in females and males, respectively. Because monogamy has evolved many times in multiple lineages, data from additional species are required to determine whether similar peptide mechanisms modulate bonding when monogamy evolves independently. Here we test the hypothesis that OT-like receptor activation is required for pair bond formation in the socially monogamous zebra finch (Taeniopygia guttata). Males and females were administered chronic intracerebroventricular infusions of saline or an OT receptor antagonist and were observed twice daily for 3 days in a colony environment. A variety of affiliative, aggressive and other behaviours were quantified. The antagonist produced significant and selective effects on pair bonding (latency to pair; number of sessions paired; stable pairing) and the associated behaviour of allopreening. Importantly, findings for males follow the trends of females; this yields main effects of treatment in two-way ANOVAs, although within-sex analyses are significant only for females. These data provide evidence for both convergent evolution and species diversity in the neuroendocrine mechanisms of pair bonding. PMID:23173212

  15. Pairing, pseudogap and Fermi arcs in cuprates

    DOE PAGES

    Kaminski, Adam; Kondo, Takeshi; Takeuchi, Tsunehiro; ...

    2014-04-29

    We use Angle Resolved Photoemission Spectroscopy (ARPES) to study the relationship between the pseudogap, pairing and Fermi arcs in cuprates. High quality data measured over a wide range of dopings reveals a consistent picture of Fermiology and pairing in these materials. The pseudogap is due to an ordered state that competes with superconductivity rather than preformed pairs. Pairing does occur below Tpair ~ 150K and significantly above Tc, but well below T* and the doping dependence of this temperature scale is distinct from that of the pseudogap. The d-wave gap is present below Tpair, and its interplay with strong scatteringmore » creates “artificial” Fermi arcs for Tc ≤ T ≤ Tpair. However, above Tpair, the pseudogap exists only at the antipodal region. This leads to presence of real, gapless Fermi arcs close to the node. The length of these arcs remains constant up to T*, where the full Fermi surface is recovered. As a result, we demonstrate that these findings resolve a number of seemingly contradictory scenarios.« less

  16. Analysis of Paired Comparison Data Using Mx

    ERIC Educational Resources Information Center

    Tsai, Rung-Ching; Wu, Tsung-Lin

    2004-01-01

    By postulating that the random utilities associated with the choice options follow a multivariate normal distribution, Thurstonian models (Thurstone, 1927) provide a straightforward representation of paired comparison data. The use of Monte Carlo Expectation-Maximization (MCEM) algorithms and limited information approaches have been proposed to…

  17. Assessing Paired Orals: Raters' Orientation to Interaction

    ERIC Educational Resources Information Center

    Ducasse, Ana Maria; Brown, Annie

    2009-01-01

    Speaking tasks involving peer-to-peer candidate interaction are increasingly being incorporated into language proficiency assessments, in both large-scale international testing contexts, and in smaller-scale, for example course-related, ones. This growth in the popularity and use of paired and group orals has stimulated research, particularly into…

  18. Pair Negotiation When Developing English Speaking Tasks

    ERIC Educational Resources Information Center

    Bohórquez Suárez, Ingrid Liliana; Gómez Sará, Mary Mily; Medina Mosquera, Sindy Lorena

    2011-01-01

    This study analyzes what characterizes the negotiations of seventh graders at a public school in Bogotá when working in pairs to develop speaking tasks in EFL classes. The inquiry is a descriptive case study that follows the qualitative paradigm. As a result of analyzing the data, we obtained four consecutive steps that characterize students'…

  19. Twisted Pair Of Insulated Wires Senses Moisture

    NASA Technical Reports Server (NTRS)

    Laue, Eric G.; Stephens, James B.

    1989-01-01

    Sensitivity of electronic moisture sensor to low levels of moisture increased by new electrode configuration. Moisture-sensing circuit described in "Low-Cost Humidity Sensor" (NPO-16544). New twisted pair of wires takes place of flat-plate capacitor in circuit. Configuration allows for thermal expansion and contraction of polymer while maintaining nearly constant area of contact between polymer and wires.

  20. Phenomena, dynamics and instabilities of vortex pairs

    NASA Astrophysics Data System (ADS)

    Williamson, C. H. K.; Leweke, T.; Asselin, D. J.; Harris, D. M.

    2014-12-01

    Our motivation for studying the dynamics of vortex pairs stems initially from an interest in the trailing wake vortices from aircraft and the dynamics of longitudinal vortices close to a vehicle surface. However, our motivation also comes from the fact that vortex-vortex interactions and vortex-wall interactions are fundamental to many turbulent flows. The intent of the paper is to present an overview of some of our recent work concerning the formation and structure of counter-rotating vortex pairs. We are interested in the long-wave and short-wave three-dimensional instabilities that evolve for an isolated vortex pair, but also we would like to know how vortex pairs interact with a wall, including both two-dimensional interactions, and also the influence of the surface on the three-dimensional instabilities. The emphasis of this presentation is on physical mechanisms by which vortices interact with each other and with surfaces, principally from an experimental approach, but also coupled with analytical studies.

  1. Paired Field Placements: A Means for Collaboration

    ERIC Educational Resources Information Center

    Gardiner, Wendy; Robinson, Karen Shipley

    2009-01-01

    In this qualitative study, pairs of preservice teachers were placed with single cooperating teachers in a 100-hour urban field placement. The question guiding this research was would preservice teachers collaborate in ways that contributed to their professional development and if so why, how, and to what end? Results from field notes, multiple…

  2. Two New CPM Pairs in Libra

    NASA Astrophysics Data System (ADS)

    Ahad, Abdul

    2014-10-01

    In this paper two new double stars are reported in the constellation of Libra that are currently not in the WDS catalog, the components of which share common proper motions. On observed photometric characteristics, calibration of distances, and other assumptions, all the indications are that both pairs comprise possible wide physical systems.

  3. Diagnostics for conformity of paired quantitative measurements.

    PubMed

    Hawkins, Douglas M

    2002-07-15

    Matched pairs data arise in many contexts - in case-control clinical trials, for example, and from cross-over designs. They also arise in experiments to verify the equivalence of quantitative assays. This latter use (which is the main focus of this paper) raises difficulties not always seen in other matched pairs applications. Since the designs deliberately vary the analyte levels over a wide range, issues of variance dependent on mean, calibrations of differing slopes, and curvature all need to be added to the usual model assumptions such as normality. Violations in any of these assumptions invalidate the conventional matched pairs analysis. A graphical method, due to Bland and Altman, of looking at the relationship between the average and the difference of the members of the pairs is shown to correspond to a formal testable regression model. Using standard regression diagnostics, one may detect and diagnose departures from the model assumptions and remedy them - for example using variable transformations. Examples of different common scenarios and possible approaches to handling them are shown.

  4. Pairing the Adult Learner and Boutique Wineries

    ERIC Educational Resources Information Center

    Holyoke, Laura; Heath-Simpson, Delta

    2013-01-01

    This study explored connections between adult learners and their experiences in the context of small boutique wineries operating in the start-up phase of the organizational life cycle. The research objective was to gain insight regarding the pairing of adult learners with the entering of a specialty industry. Fourteen individuals from four…

  5. A Novel Approach for Collaborative Pair Programming

    ERIC Educational Resources Information Center

    Goel, Sanjay; Kathuria, Vanshi

    2010-01-01

    The majority of an engineer's time in the software industry is spent working with other programmers. Agile methods of software development like eXtreme Programming strongly rely upon practices like daily meetings and pair programming. Hence, the need to learn the skill of working collaboratively is of primary importance for software developers.…

  6. Binaries and triples among asteroid pairs

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Scheirich, Peter; Kušnirák, Peter; Hornoch, Kamil; Galád, Adrián

    2015-08-01

    Despite major achievements obtained during the past two decades, our knowledge of the population and properties of small binary and multiple asteroid systems is still far from advanced. There is a numerous indirect evidence for that most small asteroid systems were formed by rotational fission of cohesionless parent asteroids that were spun up to the critical frequency presumably by YORP, but details of the process are lacking. Furthermore, as we proceed with observations of more and more binary and paired asteroids, we reveal new facts that substantially refine and sometimes change our understanding of the asteroid systems. One significant new finding we have recently obtained is that primaries of many asteroid pairs are actually binary or triple systems. The first such case found is (3749) Balam (Vokrouhlický, ApJL 706, L37, 2009). We have found 9 more binary systems among asteroid pairs within our ongoing NEOSource photometric project since October 2012. They are (6369) 1983 UC, (8306) Shoko, (9783) Tensho-kan, (10123) Fideoja, (21436) Chaoyichi, (43008) 1999 UD31, (44620) 1999 RS43, (46829) 1998 OS14 and (80218) 1999 VO123. We will review their characteristics. These paired binaries as we call them are mostly similar to binaries in the general ("background") population (of unpaired asteroids), but there are a few trends. The paired binaries tend to have larger secondaries with D_2/D_1 = 0.3 to 0.5 and they also tend to be wider systems with 8 of the 10 having orbital periods between 30 and 81 hours, than average among binaries in the general population. There may be also a larger fraction of triples; (3749) Balam is a confirmed triple, having a larger close and a smaller distant satellite, and (8306) Shoko and (10123) Fideoja are suspect triples as they show additional rotational lightcurve components with periods of 61 and 38.8 h that differ from the orbital period of 36.2 and 56.5 h, respectively. The unbound secondaries tend to be of the same size or

  7. Asteroid clusters similar to asteroid pairs

    NASA Astrophysics Data System (ADS)

    Pravec, Petr; Vokrouhlicky, David; Fatka, Petr; Kusnirák, Peter; Hornoch, Kamil; Galád, Adrián

    2016-10-01

    We study five small, tight and young clusters of asteroids. They are placed around following largest (primary) bodies: (11842) Kap'bos, (14627) Emilkowalski, (16598) 1992 YC2, (21509) Lucascavin and (39991) 1998 HR37. Each cluster has 2-4 secondaries that are tightly clustered around the primary body, with distance in the 5-dimensional space of mean orbital elements mostly within 10 m/s, and always < 23 m/s. Backward orbital integrations indicate that they formed between 105 and 106 yr ago. In the P1-q space, where P1 is the primary's spin period and q = Σ Mj/M1 is the total secondary-to-primary mass ratio, the clusters lie in the same range as asteroid pairs formed by rotational fission. We have extended the model of a proto-system separation after rotational fission by Pravec et al. (2010) for application to systems with more than one secondary and found a perfect match for the five tight clusters. We find these clusters to be similar to asteroid pairs and we suggest that they are "extended pairs", having 2-4 escaped secondaries rather than just one secondary as in the case of an asteroid pair. We compare them to six young mini-families (1270) Datura, (2384) Schulhof, (3152) Jones, (6825) Irvine, (10321) Rampo and (20674) 1999 VT1. These mini-families have similar ages, but they have a higher number of members and/or they show a significantly larger spread in the mean orbital elements (dmean on an order of tens m/s) than the five tight clusters. In the P1-q space, all but one of the mini-families lie in the same range as asteroid pairs and the tight clusters; the exception is the mini-family of (3152) Jones which appears to be a collisional family. A possibility that the other five mini-families were also formed by rotational fission as we suggest for the tight clusters ("extended asteroid pairs") is being explored.Reference:Pravec, P., et al. Formation of asteroid pairs by rotational fission. Nature 466, 1085-1088.

  8. On the deactivation mechanisms of adenine-thymine base pair.

    PubMed

    Gobbo, João Paulo; Saurí, Vicenta; Roca-Sanjuán, Daniel; Serrano-Andrés, Luis; Merchán, Manuela; Borin, Antonio Carlos

    2012-04-05

    In this contribution, the multiconfigurational second-order perturbation theory method based on a complete active space reference wave function (CASSCF/CASPT2) is applied to study all possible single and double proton/hydrogen transfers between the nucleobases in the adenine-thymine (AT) base pair, analyzing the role of excited states with different nature [localized (LE) and charge transfer (CT)], and considering concerted as well as step-wise mechanisms. According to the findings, once the lowest excited states, localized in adenine, are populated during UV irradiation of the Watson-Crick base pair, the proton transfer in the N-O bridge does not require high energy in order to populate a CT state. The latter state will immediately relax toward a crossing with the ground state, which will funnel the system to either the canonical structure or the imino-enol tautomer. The base pair is also capable of repairing itself easily since the imino-enol species is unstable to thermal conversion.

  9. Flavor violating processes with sgoldstino pair production

    NASA Astrophysics Data System (ADS)

    Demidov, S. V.; Gorbunov, D. S.

    2012-04-01

    In supersymmetric extensions of the standard model of particle physics (SM), goldstino superpartners—scalar and pseudoscalar sgoldstinos—can be light enough for emerging in decays of SM particles. Sgoldstino interaction with SM fields is suppressed by the scale of supersymmetry breaking in the whole theory. Hence, searches for sgoldstinos give an opportunity to probe the underlying mechanism of supersymmetry breaking. Sgoldstino couplings to SM fields are proportional to the supersymmetry breaking parameters—MSSM soft terms—and therefore can lead to flavor violating processes in quark and lepton sectors. We consider flavor violating processes involving sgoldstino pair production which are driven by sgoldstino couplings proportional to squark and slepton soft mass terms, m˜LL2 and m˜RR2. We find that present limits on off-diagonal entries in squark and slepton squared mass matrices allow t-, b-, c-quark and τ-lepton decays at levels available for study with existing data (BaBar, Belle, CLEOc) and in ongoing experiments (LHCb, CMS, ATLAS). In particular, we obtain the following branching ratios Br(t→cSP)≲10-7, Br(τ→μSP)≲10-7, Br(Bs→SP)≲10-4, Br(B→K(*)SP)≲10-4, Br(D→SP)≲10-7 with sgoldstino subsequent decays into kinematically allowed pairs of SM particles γγ, e+e-, μ+μ-, etc. Remarkably, the prominent signature of sgoldstino pair production is two muon pairs with pair momenta peaked at sgoldstino masses.

  10. Internucleotide J-couplings and chemical shifts of the N-H···N hydrogen-bonds in the radiation-damaged guanine-cytosine base pairs.

    PubMed

    Li, Huifang; Zhang, Laibin; Han, Li; Sun, Wenming; Bu, Yuxiang

    2011-04-30

    Internucleotide (2h)J(NN) spin-spin couplings and chemical shifts (δ((1)H) and Δδ((15)N)) of N-H···N H-bond units in the natural and radiation-damaged G-C base pairs were predicted using the appropriate density functional theory calculations with a large basis set. Four possible series of the damaged G-C pairs (viz., dehydrogenated and deprotonated G-C pairs, GC(•-) and GC(•+) radicals) were discussed carefully in this work. Computational NMR results show that radicalization and anionization of the base pairs can yield strong effect on their (2h)J(NN) spin scalar coupling constants and the corresponding chemical shifts. Thus, variations of the NMR parameters associated with the N-H···N H-bonds may be taken as an important criterion for prejudging whether the natural G-C pair is radiation-damaged or not. Analysis shows that (2h)J(NN) couplings are strongly interrelated with the energy gaps (ΔE(LP→σ*)) and the second-order interaction energies (E(2)) between the donor N lone-pair (LP(N)) and the acceptor σ*(N-H) localized NBO orbitals, and also are sensitive to the electron density distributions over the σ*(N-H) orbital, indicating that (2h)J(NN) couplings across the N-H···N H-bonds are charge-transfer-controlled. This is well supported by variation of the electrostatic potential surfaces and corresponding charge transfer amount between G and C moieties. It should be noted that although the NMR spectra for the damaged G-C pair radicals are unavailable now and the states of the radicals are usually detected by the electron spin resonance, this study provides a correlation of the properties of the damaged DNA species with some of the electronic parameters associated with the NMR spectra for the understanding of the different state character of the damaged DNA bases.

  11. Fate of the Bose insulator in the limit of strong localization and low Cooper-pair density in ultrathin films

    NASA Astrophysics Data System (ADS)

    Hollen, S. M.; Fernandes, G. E.; Xu, J. M.; Valles, J. M.

    2014-10-01

    A Bose insulator composed of a low density of strongly localized Cooper pairs develops at the two-dimensional superconductor to insulator transition (SIT) in a number of thin film systems. Investigations of ultrathin amorphous PbBi films far from the SIT described here provide evidence that the Bose insulator gives way to a second insulating phase with decreasing film thickness. At a critical film thickness dc the magnetoresistance changes sign from positive, as expected for boson transport, to negative, as expected for fermion transport, signs of local Cooper-pair phase coherence effects on transport vanish, and the transport activation energy exhibits a kink. Below dc pairing fluctuation effects remain visible in the high-temperature transport while the activation energy continues to rise. These features show that Cooper pairing persists and suggest that the localized unpaired electron states involved in transport are interspersed among regions of strongly localized Cooper pairs in this strongly localized, low Cooper-pair density phase.

  12. Characteristics of compatible pair participants in kidney paired donation at a single center.

    PubMed

    Weng, Francis L; Grogan, Tracy; Patel, Anup M; Mulgaonkar, Shamkant; Morgievich, Marie M

    2017-03-25

    Compatible pairs of living kidney donors and their intended recipients can enter into kidney paired donation (KPD) and facilitate additional living donor kidney transplants (LDKTs). We examined 11 compatible pairs (the intended recipients and their intended, compatible donors) who participated in KPD, along with the recipients' 11 matched, exchange donors. The 11 pairs participated in 10 separate exchanges (3 were multi-center exchanges) that included 33 total LDKTs (22 additional LDKTs). All the intended donors were blood group O and female, with a mean living kidney donor profile index (LKDPI) of 27.6 (SD 16.8). The matched donors had a mean LKDPI of 9.4 (SD 31.7). Compatible pairs entered KPD for altruistic reasons (N=2) or due to mismatch of age (N=7) or body/kidney size (N=2) between the recipient and intended donor. In four cases, retrospective calculation of the LKDPI revealed that the matched donor had a higher LKDPI than the intended donor. Of the 22 recipients of LDKTs enabled by the compatible pairs, three were highly sensitized, with PRA >80%. In conclusion, most compatible pairs entered into KPD so that the recipient could receive a LDKT transplant from a donor whose age or body/kidney size were more favorable to post-transplant outcomes. This article is protected by copyright. All rights reserved.

  13. Poland: Lone Eagle over Europe

    DTIC Science & Technology

    2012-05-17

    Pilsudski’s Coup to Pilsudski’s Death .................... 32 Section V. 1936-1939: Rise of the Nazi War Machine to Poland’s Failure...40 The Strategic Environment between 1936-1939: Rise of the Nazi War Machine to Poland’s Failure...41 The use of DIME between 1936-1939: Rise of the Nazi

  14. Schwinger pair creation of Kaluza-Klein particles: Pair creation without tunneling

    SciTech Connect

    Friedmann, Tamar; Verlinde, Herman

    2005-03-15

    We study Schwinger pair creation of charged Kaluza-Klein (KK) particles from a static KK electric field. We find that the gravitational backreaction of the electric field on the geometry--which is incorporated via the electric KK-Melvin solution--prevents the electrostatic potential from overcoming the rest mass of the KK particles, thus impeding the tunneling mechanism which is often thought of as responsible for the pair creation. However, we find that pair creation still occurs with a finite rate formally similar to the classic Schwinger result, but via an apparently different mechanism, involving a combination of the Unruh effect and vacuum polarization due to the E-field.

  15. Metal-mediated DNA base pairing: alternatives to hydrogen-bonded Watson-Crick base pairs.

    PubMed

    Takezawa, Yusuke; Shionoya, Mitsuhiko

    2012-12-18

    With its capacity to store and transfer the genetic information within a sequence of monomers, DNA forms its central role in chemical evolution through replication and amplification. This elegant behavior is largely based on highly specific molecular recognition between nucleobases through the specific hydrogen bonds in the Watson-Crick base pairing system. While the native base pairs have been amazingly sophisticated through the long history of evolution, synthetic chemists have devoted considerable efforts to create alternative base pairing systems in recent decades. Most of these new systems were designed based on the shape complementarity of the pairs or the rearrangement of hydrogen-bonding patterns. We wondered whether metal coordination could serve as an alternative driving force for DNA base pairing and why hydrogen bonding was selected on Earth in the course of molecular evolution. Therefore, we envisioned an alternative design strategy: we replaced hydrogen bonding with another important scheme in biological systems, metal-coordination bonding. In this Account, we provide an overview of the chemistry of metal-mediated base pairing including basic concepts, molecular design, characteristic structures and properties, and possible applications of DNA-based molecular systems. We describe several examples of artificial metal-mediated base pairs, such as Cu(2+)-mediated hydroxypyridone base pair, H-Cu(2+)-H (where H denotes a hydroxypyridone-bearing nucleoside), developed by us and other researchers. To design the metallo-base pairs we carefully chose appropriate combinations of ligand-bearing nucleosides and metal ions. As expected from their stronger bonding through metal coordination, DNA duplexes possessing metallo-base pairs exhibited higher thermal stability than natural hydrogen-bonded DNAs. Furthermore, we could also use metal-mediated base pairs to construct or induce other high-order structures. These features could lead to metal-responsive functional

  16. Progress toward positron-electron pair plasma experiments

    SciTech Connect

    Stenson, E. V.; Stanja, J.; Hergenhahn, U.; Saitoh, H.; Niemann, H.; Pedersen, T. Sunn; Marx, G. H.; Schweikhard, L.; Danielson, J. R.; Surko, C. M.; Hugenschmidt, C.

    2015-06-29

    Electron-positron plasmas have been of theoretical interest for decades, due to the unique plasma physics that arises from all charged particles having precisely identical mass. It is only recently, though, that developments in non-neutral plasma physics (both in linear and toroidal geometries) and in the flux of sources for cold positrons have brought the goal of conducting electron-positron pair plasma experiments within reach. The APEX/PAX collaboration is working on a number of projects in parallel toward that goal; this paper provides an overview of recent, current, and upcoming activities.

  17. Crystal structures of amylosucrase from Neisseria polysaccharea in complex with D-glucose and the active site mutant Glu328Gln in complex with the natural substrate sucrose.

    PubMed

    Mirza, O; Skov, L K; Remaud-Simeon, M; Potocki de Montalk, G; Albenne, C; Monsan, P; Gajhede, M

    2001-07-31

    The structure of amylosucrase from Neisseria polysaccharea in complex with beta-D-glucose has been determined by X-ray crystallography at a resolution of 1.66 A. Additionally, the structure of the inactive active site mutant Glu328Gln in complex with sucrose has been determined to a resolution of 2.0 A. The D-glucose complex shows two well-defined D-glucose molecules, one that binds very strongly in the bottom of a pocket that contains the proposed catalytic residues (at the subsite -1), in a nonstrained (4)C(1) conformation, and one that binds in the packing interface to a symmetry-related molecule. A third weaker D-glucose-binding site is located at the surface near the active site pocket entrance. The orientation of the D-glucose in the active site emphasizes the Glu328 role as the general acid/base. The binary sucrose complex shows one molecule bound in the active site, where the glucosyl moiety is located at the alpha-amylase -1 position and the fructosyl ring occupies subsite +1. Sucrose effectively blocks the only visible access channel to the active site. From analysis of the complex it appears that sucrose binding is primarily obtained through enzyme interactions with the glucosyl ring and that an important part of the enzyme function is a precise alignment of a lone pair of the linking O1 oxygen for hydrogen bond interaction with Glu328. The sucrose specificity appears to be determined primarily by residues Asp144, Asp394, Arg446, and Arg509. Both Asp394 and Arg446 are located in an insert connecting beta-strand 7 and alpha-helix 7 that is much longer in amylosucrase compared to other enzymes from the alpha-amylase family (family 13 of the glycoside hydrolases).

  18. Direct Cavity Detection of Majorana Pairs

    NASA Astrophysics Data System (ADS)

    Dartiailh, Matthieu C.; Kontos, Takis; Douçot, Benoit; Cottet, Audrey

    2017-03-01

    No experiment could directly test the particle-antiparticle duality of Majorana fermions, so far. However, this property represents a necessary ingredient towards the realization of topological quantum computing schemes. Here, we show how to complete this task by using microwave techniques. The direct coupling between a pair of overlapping Majorana bound states and the electric field from a microwave cavity is extremely difficult to detect due to the self-adjoint character of Majorana fermions which forbids direct energy exchanges with the cavity. We show theoretically how this problem can be circumvented by using photoassisted tunneling to fermionic reservoirs. The absence of a direct microwave transition inside the Majorana pair in spite of the light-Majorana coupling would represent a smoking gun for the Majorana self-adjoint character.

  19. Near-Unity Cooper Pair Splitting Efficiency

    NASA Astrophysics Data System (ADS)

    Schindele, J.; Baumgartner, A.; Schönenberger, C.

    2012-10-01

    The two electrons of a Cooper pair in a conventional superconductor form a spin singlet and therefore a maximally entangled state. Recently, it was demonstrated that the two particles can be extracted from the superconductor into two spatially separated contacts via two quantum dots in a process called Cooper pair splitting (CPS). Competing transport processes, however, limit the efficiency of this process. Here we demonstrate efficiencies up to 90%, significantly larger than required to demonstrate interaction-dominated CPS, and on the right order to test Bell’s inequality with electrons. We compare the CPS currents through both quantum dots, for which large apparent discrepancies are possible. The latter we explain intuitively and in a semiclassical master equation model. Large efficiencies are required to detect electron entanglement and for prospective electronics-based quantum information technologies.

  20. Extra-pair paternity in waved albatrosses.

    PubMed

    Huyvaert, K P; Anderson, D J; Jones, T C; Duan, W; Parker, P G

    2000-09-01

    We estimated the rate of extra-pair fertilizations (EPFs) in waved albatrosses (Phoebastria irrorata) on Isla Española, Galápagos, Ecuador, using multilocus minisatellite DNA fingerprinting. Waved albatrosses are socially monogamous, long-lived seabirds whose main population is on Española. Aggressive extra-pair copulation (EPC) attempts have been observed in the breeding colony during the days preceding egg-laying. Our genetic analyses of 16 families (single chicks and their attending parents) revealed evidence of EPFs in four families. In all cases males were the excluded parent. These data suggest that waved albatrosses have an unusually high rate of EPF relative to taxa with similar life histories. Future behavioural observations will determine the extent to which forced vs. unforced EPCs contribute to this high EPF rate.