584 research outputs found

    Drought-stressed, irrigated, and additive-treated corn silages for growing cattle

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    Cattle fed drought-stressed corn silage gained about 10% slower but were just as efficient as cattle fed irrigated corn silage. Because the irrigated corn out yielded the drought corn (17.4 VS. 8.2 tons per acre), the irrigated silage gave a much higher cattle gain per acre (1928 VS. 940 1b). Silo Guard II®-treated silage had an advantage in DM recovery and feed conversion over its control and produced 4.6 more pounds of cattle gain per ton of crop ensiled. Cattle fed H/M Inoculant®- treated silage gained significantly faster than cattle fed the control, however, the treated silage gave only slight improvements in DM recovery and gain per ton of crop ensiled

    High resolution X-ray scattering studies of structural phase transitions in underdoped La2x_{2-x}Bax_xCuO4_4

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    We have studied structural phase transitions in high quality underdoped La2x_{2-x}Bax_xCuO4_4 single crystals using high resolution x-ray scattering techniques. Critical properties associated with the continuous High Temperature Tetragonal (HTT, I4/mmmI4/mmm) to Middle Temperature Orthorhombic (MTO, CmcaCmca) phase transition were investigated in single crystal samples with x=0.125, 0.095, and 0.08 and we find that all behavior is consistent with three dimensional XY criticality, as expected from theory. Power law behavior in the orthorhombic strain, 2(a-b)/(a+b), is observed over a remarkably wide temperature range, spanning most of the MTO regime in the phase diagram. Low temperature measurements investigating the Low Temperature Tetragonal (LTT, P42/ncmP4_{2}/ncm) phase, below the strongly discontinuous MTO\toLTT phase transition, in x=0.125 and x=0.095 samples show that the LTT phase is characterized by relatively broad Bragg scattering, compared with that observed at related wavevectors in the HTT phase. This shows that the LTT phase is either an admixture of tetragonal and orthorhombic phases, or that it is orthorhombic with very small orthorhombic strain, consistent with the ``less orthorhombic" low temperature structure previously reported in mixed La2x_{2-x}Srxy_{x-y}Bay_yCuO4_4 single crystals. We compare the complex temperature-composition phase diagram for the location of structural and superconducting phase transitions in underdoped La2x_{2-x}Bax_xCuO4_4 and find good agreement with results obtained on polycrystalline samples.Comment: 8 pages, 7 figures, 1 tabl

    Soft phonons and structural phase transitions in La1.875_{1.875}Ba0.125_{0.125}CuO4_{4}

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    Soft phonon behavior associated with a structural phase transition from the low-temperature-orthorhombic (LTO) phase (BmabBmab symmetry) to the low-temperature-tetragonal (LTT) phase (P42/ncmP4_{2}/ncm symmetry) was investigated in La1.875_{1.875}Ba0.125_{0.125}CuO4_{4} using neutron scattering. As temperature decreases, the TO-mode at ZZ-point softens and approaches to zero energy around Td2=62T_{\rm d2}=62 K, where the LTO -- LTT transition occurs. Below Td2T_{\rm d2}, the phonon hardens quite rapidly and it's energy almost saturates below 50 K. At Td2T_{\rm d2}, the energy dispersion of the soft phonon along in-plane direction significantly changes while the dispersion along out-of-plane direction is almost temperature independent. Coexistence between the LTO phase and the LTT phase, seen in both the soft phonon spectra and the peak profiles of Bragg reflection, is discussed in context of the order of structural phase transitions.Comment: 6 pages, 8 figure

    Inelastic neutron and x-ray scattering as probes of the sign structure of the Fe-pnictide superconducting gap

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    Neutron spin-flip scattering observations of a resonance in the superconducting state is often taken as evidence of an unconventional superconducting state in which the gap changes sign Δ(k+Q)=Δ(k)\Delta(k+Q)=-\Delta(k) for momentum transfers QQ which play an important role in the pairing. Recently questions regarding this identification for the Fe-pnictide superconductors have been raised and it has been suggested that Δ(k+Q)=Δ(k)\Delta(k+Q)=\Delta(k). Here we propose that inelastic neutron or x-ray scattering measurements of the spectral weight of a phonon of momentum QQ can distinguish between these two pairing scenarios.Comment: 4 pages, 4 figure

    Diagonal static spin correlation in the low temperature orthorhombic Pccn phase of La1.55Nd0.4Sr0.05CuO4

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    Elastic neutron scattering measurements have been performed on Nd, Sr co-doped La1.55Nd0.4Sr0.05CuO4, which exhibits a structural phase transition at Ts ~ 60K from the low temperature orthorhombic Bmab phase (labelled LTO1) to the low temperature orthorhombic Pccn phase (labelled LTO2). At low temperatures, well below Ts, elastic magnetic peaks are observed at the ``diagonal'' incommensurate (IC) positions (0, 1+/-0.055, 0), with modulation direction only along the orthorhombic b-axis just as in Nd-free La1.95Sr0.05CuO4. In the present study, the one-dimensionality of the IC modulation, which is naturally explained by a stripe model, is clearly demonstrated with our "single-domain" crystal. The temperature dependence of the IC peak intensity suggests a substantial contribution from the Nd3+ spins below ~3K. Consistent with this, the L dependence of the magnetic scattering is accurately accounted for by a model in which the contribution of the Nd3+ spins is explicitly included.Comment: 8 pages, 8 figure

    Stripes and spin-incommensurabilities are favored by lattice anisotropies

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    Structural distortions in cuprate materials give a natural origin for anisotropies in electron properties. We study a modified one-band t-J model in which we allow for different hoppings and antiferromagnetic couplings in the two spatial directions (txtyt_x \ne t_y and JxJyJ_x \ne J_y). Incommensurate peaks in the spin structure factor show up only in the presence of a lattice anisotropy, whereas charge correlations, indicating enhanced fluctuations at incommensurate wave vectors, are almost unaffected with respect to the isotropic case.Comment: accepted for publication on Physical Review Letters, one color figur

    Neutron scattering study of soft phonons and diffuse scattering in insulating La1.95_{1.95}Sr0.05_{0.05}CuO4_{4}

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    Soft phonons and diffuse scattering in insulating La2x_{2-x}Srx_{x}CuO4_4 (x=0.05x=0.05) have been studied by the neutron scattering technique. The X-point phonon softens from high temperature towards the structural transition temperature Ts=410T_{s}=410 K, and the Z-point phonon softens again below 200 K. The Z-point phonon softening persists to low temperature, in contrast to the behavior observed in the superconducting x=0.15x=0.15 compound, in which the Z-point phonon hardens below TcT_c. The diffuse scattering associated with the structural phase transition at 410 K appears at commensurate positions. These results highlight interesting differences between superconducting and insulating samples.Comment: 5 pages, 5 figure

    LC3 and STRAP regulate actin filament assembly by JMY during autophagosome formation.

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    During autophagy, actin filament networks move and remodel cellular membranes to form autophagosomes that enclose and metabolize cytoplasmic contents. Two actin regulators, WHAMM and JMY, participate in autophagosome formation, but the signals linking autophagy to actin assembly are poorly understood. We show that, in nonstarved cells, cytoplasmic JMY colocalizes with STRAP, a regulator of JMY's nuclear functions, on nonmotile vesicles with no associated actin networks. Upon starvation, JMY shifts to motile, LC3-containing membranes that move on actin comet tails. LC3 enhances JMY's de novo actin nucleation activity via a cryptic actin-binding sequence near JMY's N terminus, and STRAP inhibits JMY's ability to nucleate actin and activate the Arp2/3 complex. Cytoplasmic STRAP negatively regulates autophagy. Finally, we use purified proteins to reconstitute LC3- and JMY-dependent actin network formation on membranes and inhibition of network formation by STRAP. We conclude that LC3 and STRAP regulate JMY's actin assembly activities in trans during autophagy

    Born Effective Charges of Barium Titanate: band by band decomposition and sensitivity to structural features

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    The Born effective charge tensors of Barium Titanate have been calculated for each of its 4 phases. Large effective charges of Ti and O, also predicted by shell model calculations and made plausible by a simplified model, reflect the partial covalent character of the chemical bond. A band by band decomposition confirms that orbital hybridization is not restricted to Ti and O atoms but also involves Ba which appears more covalent than generally assumed. Our calculations reveal a strong dependence of the effective charges on the atomic positions contrasting with a relative insensitivity on isotropic volume changes.Comment: 13 page

    Application of elastostatic Green function tensor technique to electrostriction in cubic, hexagonal and orthorhombic crystals

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    The elastostatic Green function tensor approach, which was recently used to treat electrostriction in numerical simulation of domain structure formation in cubic ferroelectrics, is reviewed and extended to the crystals of hexagonal and orthorhombic symmetry. The tensorial kernels appearing in the expressions for effective nonlocal interaction of electrostrictive origin are derived explicitly and their physical meaning is illustrated on simple examples. It is argued that the bilinear coupling between the polarization gradients and elastic strain should be systematically included in the Ginzburg-Landau free energy expansion of electrostrictive materials.Comment: 4 page
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