3,295 research outputs found

    Optimal positioning in derivative securities

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    Transition Metal Chemistry of Oxime-Containing Ligands, Part XIV. Iron(II) Complexes of syn-Phenyl-2-pyridylketoxime and syn-Methy 1-2-pyridylketoxime

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    Iron(II) complexes of the type [Fe(HL)2X2] (where HL = syn-phenyl-2-pyridylketoxime (Hppk) or syn-methyl-2-pyridylketoxime (Hmpk) and X = c1-, Br-, I-, Ncs- or NCse-) were synthesized and characterized by elemental analysis, molar conductance, molecular weight determination, X-ray powder diffraction patterns, magnetic susceptibility, Mossbauer, reflectance and IR spectral measurements. On the basis of these physical properties a halo-bridged dimeric cis- octahedral structure is suggested for the iron(II) halo complexes, whereas the remaining complexes appear to be monomeric with a cis- octahedral structur e

    Transition Metal Chemistry of Oxime-Containing Ligands, Part XIV. Iron(II) Complexes of syn-Phenyl-2-pyridylketoxime and syn-Methy 1-2-pyridylketoxime

    Get PDF
    Iron(II) complexes of the type [Fe(HL)2X2] (where HL = syn-phenyl-2-pyridylketoxime (Hppk) or syn-methyl-2-pyridylketoxime (Hmpk) and X = c1-, Br-, I-, Ncs- or NCse-) were synthesized and characterized by elemental analysis, molar conductance, molecular weight determination, X-ray powder diffraction patterns, magnetic susceptibility, Mossbauer, reflectance and IR spectral measurements. On the basis of these physical properties a halo-bridged dimeric cis- octahedral structure is suggested for the iron(II) halo complexes, whereas the remaining complexes appear to be monomeric with a cis- octahedral structur e

    Unifying Black-Scholes type formulae which involve Brownian last passage times up to a finite horizon

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    The authors recently discovered some interesting relations between the Black-Scholes formula and last passage times of the Brownian exponential martingales, which invites one to seek analogous results for last passage times up to a finite horizon. This is achieved in the present paper, where Yuri's formula, as originally presented in Akahori, Imamura and yano (2008), is also derived

    Dynamics of broken symmetry nodal and anti-nodal excitations in Bi_{2} Sr_{2} CaCu_{2} O_{8+\delta} probed by polarized femtosecond spectroscopy

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    The dynamics of excitations with different symmetry is investigated in the superconducting (SC) and normal state of the high-temperature superconductor Bi2_{2}Sr2_{2}CaCu2_{2}O8+δ_{8+\delta} (Bi2212) using optical pump-probe (Pp) experiments with different light polarizations at different doping levels. The observation of distinct selection rules for SC excitations, present in A1g_{{\rm 1g}} and B1g_{{\rm 1g}} symmetries, and for the PG excitations, present in A1g_{{\rm 1g}} and B2g_{{\rm 2g}} symmetries, by the probe and absence of any dependence on the pump beam polarization leads to the unequivocal conclusion of the existence of a spontaneous spatial symmetry breaking in the pseudogap (PG) state

    Two Modes of Solid State Nucleation - Ferrites, Martensites and Isothermal Transformation Curves

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    When a crystalline solid such as iron is cooled across a structural transition, its final microstructure depends sensitively on the cooling rate. For instance, an adiabatic cooling across the transition results in an equilibrium `ferrite', while a rapid cooling gives rise to a metastable twinned `martensite'. There exists no theoretical framework to understand the dynamics and conditions under which both these microstructures obtain. Existing theories of martensite dynamics describe this transformation in terms of elastic strain, without any explanation for the occurence of the ferrite. Here we provide evidence for the crucial role played by non-elastic variables, {\it viz.}, dynamically generated interfacial defects. A molecular dynamics (MD) simulation of a model 2-dimensional (2d) solid-state transformation reveals two distinct modes of nucleation depending on the temperature of quench. At high temperatures, defects generated at the nucleation front relax quickly giving rise to an isotropically growing `ferrite'. At low temperatures, the defects relax extremely slowly, forcing a coordinated motion of atoms along specific directions. This results in a twinned critical nucleus which grows rapidly at speeds comparable to that of sound. Based on our MD results, we propose a solid-state nucleation theory involving the elastic strain and non-elastic defects, which successfully describes the transformation to both a ferrite and a martensite. Our work provides useful insights on how to formulate a general dynamics of solid state transformations.Comment: 3 pages, 4 B/W + 2 color figure

    Mitogen-activated protein kinase (MAPK) blockade of bovine preimplantation embryogenesis requires inhibition of both p38 and extracellular signal-regulated kinase (ERK) pathways.

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    Blastocyst formation, as a critical period during development, is an effective indicator of embryonic health and reproductive efficiency. Out of a number of mechanisms underlying blastocyst formation, highly conserved mitogen-activated protein kinase (MAPK) signaling has emerged as a major mechanism involved in regulating murine preimplantation embryo development. The objective of our study was to ascertain the role of MAPK signaling in regulating bovine development to the blastocyst stage. Using reverse transcriptase PCR and immunohistochemical staining procedures we have demonstrated that mRNA transcripts and polypeptides encoding p38 MAPK pathway constituents are detectable in preimplantation bovine embryos from the one-cell to the blastocyst stage. Further, the effects on bovine embryo development following inhibition of p38 alpha/beta and extracellular signal-regulated kinase (ERK) signaling by treatment with SB220025 and U0126, respectively, were investigated. Eight-cell bovine embryos (50 per group; three replicates) were placed into treatments consisting of synthetic oviductal fluid (SOF) medium: SOF + SB202474 (inactive analogue), SOF + SB220025, SOF + U0124 (inactive analogue), SOF + U0126, and SOF + SB220025 + U0126. Inhibition of p38 MAPK or ERK signaling individually did not affect development to the blastocyst stage. However, when both pathways were blocked simultaneously there was a significant reduction (P \u3c 0.05) in blastocyst formation, cell number and immunofluorescence of phosphorylated downstream pathway constituents. We have determined that, in variance to what was observed during murine preimplantation development, bovine early embryos progress at normal frequencies to the blastocyst stage in the presence of p38 MAPK inhibitors

    Bovine oocytes and early embryos express Staufen and ELAVL RNA-binding proteins.

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    RNA-binding proteins (RBP) influence RNA editing, localization, stability and translation and may contribute to oocyte developmental competence by regulating the stability and turnover of oogenetic mRNAs. The expression of Staufen 1 and 2 and ELAVL1, ELAVL2 RNA-binding proteins during cow early development was characterized. Cumulus-oocyte complexes were collected from slaughterhouse ovaries, matured, inseminated and subjected to embryo culture in vitro. Oocyte or preimplantation embryo pools were processed for RT-PCR and whole-mount immunofluorescence analysis of mRNA expression and protein distribution. STAU1 and STAU2 and ELAVL1 mRNAs and proteins were detected throughout cow preimplantation development from the germinal vesicle (GV) oocyte to the blastocyst stage. ELAVL2 mRNAs were detectable from the GV to the morula stage, whereas ELAVL2 protein was in all stages examined and localized to both cytoplasm and nuclei. The findings provide a foundation for investigating the role of RBPs during mammalian oocyte maturation and early embryogenesis
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