High statistics analysis using anisotropic clover lattices: (III) Baryon-baryon interactions
Beane, S; Detmold, W; Lin, H; Luu, T; Orginos, K; Savage, M; Torok, A; Walker-Loud, A
2010-01-19
Low-energy baryon-baryon interactions are calculated in a high-statistics lattice QCD study on a single ensemble of anisotropic clover gauge-field configurations at a pion mass of m{sub {pi}} {approx} 390 MeV, a spatial volume of L{sup 3} {approx} (2.5 fm){sup 3}, and a spatial lattice spacing of b {approx} 0.123 fm. Luescher's method is used to extract nucleon-nucleon, hyperon-nucleon and hyperon-hyperon scattering phase shifts at one momentum from the one- and two-baryon ground-state energies in the lattice volume. The isospin-3/2 N{Sigma} interactions are found to be highly spin-dependent, and the interaction in the {sup 3}S{sub 1} channel is found to be strong. In contrast, the N{Lambda} interactions are found to be spin-independent, within the uncertainties of the calculation, consistent with the absence of one-pion-exchange. The only channel for which a negative energy-shift is found is {Lambda}{Lambda}, indicating that the {Lambda}{Lambda} interaction is attractive, as anticipated from model-dependent discussions regarding the H-dibaryon. The NN scattering lengths are found to be small, clearly indicating the absence of any fine-tuning in the NN-sector at this pion mass. This is consistent with our previous Lattice QCD calculation of NN interactions. The behavior of the signal-to-noise ratio in the baryon-baryon correlation functions, and in the ratio of correlation functions that yields the ground-state energy splitting is explored. In particular, focus is placed on the window of time slices for which the signal-to-noise ratio does not degrade exponentially, as this provides the opportunity to extract quantitative information about multi-baryon systems.
High Statistics Analysis using Anisotropic Clover Lattices: (III) Baryon-Baryon Interactions
Beane, Silas [Univ. of New Hampshire, Durham, NH (United States); Detmold, William [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lin, Huey-Wen [Univ. of Washington, Seattle, WA (United States); Luu, Thomas C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Orginos, Kostas [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Savage, Martin [Univ. of Washington, Seattle, WA (United States); Torok, Aaron M. [Indiana Univ., Bloomington, IN (United States). Dept. of Physics; Walker-Loud, Andre [College of William and Mary, Williamsburg, VA (United States)
2010-03-01
Low-energy baryon-baryon interactions are calculated in a high-statistics lattice QCD study on a single ensemble of anisotropic clover gauge-field configurations at a pion mass of m_pi ~ 390 MeV, a spatial volume of L^3 ~ (2.5 fm)^3, and a spatial lattice spacing of b ~ 0.123 fm. Luscher’s method is used to extract nucleon-nucleon, hyperon-nucleon and hyperon-hyperon scattering phase shifts at one momentum from the one- and two-baryon ground-state energies in the lattice volume. The N-Sigma interactions are found to be highly spin-dependent, and the interaction in the ^3 S _1 channel is found to be strong. In contrast, the N-Lambda interactions are found to be spin-independent, within the uncertainties of the calculation, consistent with the absence of one-pion-exchange. The only channel for which a negative energy-shift is found is Lambda-Lambda, indicating that the Lambda-Lambda interaction is attractive, as anticipated from model-dependent discussions regarding the H-dibaryon. The NN scattering lengths are found to be small, clearly indicating the absence of any fine-tuning in the NN-sector at this pion mass. This is consistent with our previous Lattice QCD calculation of the NN interactions. The behavior of the signal-to-noise ratio in the baryon-baryon correlation functions, and in the ratio of correlation functions that yields the ground-state energy splitting
Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A
2011-07-01
The volume dependence of the octet baryon masses and relations among them are explored with Lattice QCD. Calculations are performed with nf = 2 + 1 clover fermion discretization in four lattice volumes, with spatial extent L ? 2.0, 2.5, 3.0 and 4.0 fm, with an anisotropic lattice spacing of b_s ? 0.123 fm in the spatial direction, and b_t = b_s/3.5 in the time direction, and at a pion mass of m_\\pi ? 390 MeV. The typical precision of the ground-state baryon mass determination is lattice gauge-field configurations. Finally, the volume dependence of the pion and kaon masses are analyzed with two-flavor and three-flavor chiral perturbation theory.
Parameter Tuning of Three-Flavor Dynamical Anisotropic Clover Action
Huey-Wen Lin; Robert G. Edwards; Balint Joo
2007-08-04
In this work, we perform parameter tuning with dynamical anisotropic clover lattices using the Schr\\"odinger functional and stout-smearing in the fermion field. We find that $\\xi_R/\\xi_0$ is relatively close to 1 in our parameter search, which allows us to fix $\\xi_0$ in our runs. We proposed to determine the gauge and fermion anisotropy in a Schr\\"odinger-background small box using Wilson loop ratios and PCAC masses. We demonstrate that these ideas are equivalent to but more efficient than the conventional meson dispersion approach. The spatial and temporal clover coefficients are fixed to the tree-level tadpole-improved clover values, and we demonstrate that they satisfy the nonperturbative condition determined by Schr\\"odinger functional method.
Richards, David G. [Jefferson Lab, Newport News, VA; Orginos, Konstantinos [William and Mary College, Williamsburg, VA; Jefferson Lab, Newport News, VA
2014-06-23
We present an investigation of the excited meson spectrum at the N_f= 3 point obtained on isotropic clover lattices with a plaquette Wilson gauge action, and a NP-improved clover fermion action, at a lattice spacing of a \\simeq 0.08 fm, and compare with corresponding calculations on an anisotropic lattice at fine temporal lattice spacing but a spatial lattice spacing of a_s \\simeq 0.125 fm. The methodology adopted follows that employed in the calculation of the spectrum on anisotropic lattices, and we test the efficacy of that approach for isotropic lattices. In particular, we explore the extent to which rotational symmetry for predominantly single-hadron states is realized. By comparison of the energy levels with that obtained using the anisotropic lattice, we obtain an indication of discretization uncertainties in the single-hadron spectrum.
Nonperturbative tests of the renormalization of mixed clover-staggered currents in lattice QCD
Chakraborty, Bipasha; Donald, Gordon; Dowdall, Rachel; Koponen, Jonna; Lepage, G Peter
2014-01-01
The Fermilab Lattice and MILC collaborations have shown in one-loop lattice QCD perturbation theory that the renormalization constants of vector and axial-vector mixed clover-asqtad currents are closely related to the product of those for clover-clover and asqtad-asqtad (local) vector currents. To be useful for future higher precision calculations this relationship must be valid beyond one-loop and very general. We test its validity nonperturbatively using clover and Highly Improved Staggered (HISQ) strange quarks, utilising the absolute normalization of the HISQ temporal axial current. We find that the renormalization of the mixed current differs from the square root of the product of the pure HISQ and pure clover currents by $2-3\\%$. We also compare discretization errors between the clover and HISQ formalisms.
Resummation of Cactus Diagrams in the Clover Improved Lattice Formulation of QCD
Panagopoulos, H
1999-01-01
We extend to the clover improved lattice formulation of QCD the resummation of cactus diagrams, i.e. a certain class of tadpole-like gauge invariant diagrams. Cactus resummation yields an improved perturbative expansion. We apply it to the lattice renormalization of some two-fermion operators improving their one-loop perturbative estimates.
Relativistic Bottomonium Spectrum from Anisotropic Lattices
Liao, X.; Manke, T.
2001-01-01
We report on a first relativistic calculation of the quenched bottomonium spectrum from anisotropic lattices. Using a very fine discretisation in the temporal direction we were able to go beyond the non-relativistic approximation and perform a continuum extrapolation of our results from five different lattice spacings (0.04-0.17 fm) and two anisotropies (4 and 5). We investigate several systematic errors within the quenched approximation and compare our results with those from non-relativisti...
Variably saturated flow described with the anisotropic Lattice Boltzmann methods
Ginzburg, I.
2006-01-01
This paper addresses the numerical solution of highly nonlinear parabolic equations with Lattice Boltzmann techniques. They are first developed for generic advection and anisotropic dispersion equations (AADE). Collision configurations handle the anisotropic diffusion forms by using either anisotropic eigenvalue sets or anisotropic equilibrium functions. The coordinate transformation from the orthorhombic (rectangular) discretization grid to the cuboid computational grid is equivalen...
Relativistic Heavy Quark Spectrum On Anisotropic Lattices
Liao, X
2003-01-01
We report a fully relativistic quenched calculation of the heavy quark spectrum, including both charmonium and bottomonium, using anisotropic lattice QCD. We demonstrate that a fully relativistic treatment of a heavy quark system is well-suited to address the large systematic errors in non-relativistic calculations. In addition, the anisotropic lattice formulation is a very efficient framework for calculations requiring high temporal resolutions. A detailed excited charmonium spectrum is obtained, including both the exotic hybrids (with JPC = 1−+ , 0+−, 2+−) and orbitally excited mesons (with orbital angular momentum up to 3). Using three different lattice spacings (0.197, 0.131, and 0.092 fm), we perform a continuum extrapolation of the spectrum. The lowest lying exotic hybrid 1−+ lies at 4.428(41) GeV, slightly above the D**D (S + P wave) threshold of 4.287 GeV. Another two exotic hybrids 0+− and 2 +− are determined to be 4.70(17) GeV and 4.895(88)...
Penta-quark in Anisotropic Lattice QCD
Ishii, N; Iida, H; Oka, M; Okiharu, F; Suganuma, H
2005-01-01
Penta-quark (5Q) baryons are studied using anisotropic lattice QCD for high-precision measurement of temporal correlators. A non-NK-type interpolating field is employed to study the 5Q states with J^P=1/2^{\\pm} and I=0. In J^P=1/2^+ channel, the lowest-lying state is found at m_{5Q} \\simeq 2.25 GeV, which is too massive to be identified as the Theta^+(1540). In J^P=1/2^- channel, the lowest-lying state is found at m_{5Q} \\simeq 1.75 GeV. To distinguish a compact 5Q resonance state from an NK scattering state, a new method with ``hybrid boundary condition (HBC)'' is proposed. As a result of the HBC analysis, the observed state in the negative-parity channel turns out to be an $NK$ scattering state.
Effective Dirac Hamiltonian for anisotropic honeycomb lattices: Optical properties
Oliva-Leyva, M.; Naumis, Gerardo G.
2016-01-01
We derive the low-energy Hamiltonian for a honeycomb lattice with anisotropy in the hopping parameters. Taking the reported Dirac Hamiltonian for the anisotropic honeycomb lattice, we obtain its optical conductivity tensor and its transmittance for normal incidence of linearly polarized light. Also, we characterize its dichroic character due to the anisotropic optical absorption. As an application of our general findings, which reproduce the previous case of uniformly strained graphene, we study the optical properties of graphene under a nonmechanical distortion.
Anisotropic lattice QCD studies of penta-quarks and tetra-quarks
Ishii, N; Iida, H; Oka, M; Okiharu, F; Suganuma, H; Tsumura, K
2006-01-01
Anisotropic lattice QCD studies of penta-quarks(5Q) with J^P=1/2^\\pm and 3/2^{\\pm} are presented at the quenched level together with tetra-quarks(4Q). The standard gauge action at \\beta=5.75 and O(a) improved quark (clover) action with \\kappa=0.1410(0.010)0.1440 are employed on the anisotropic lattice with the renormalized anisotropy a_s/a_t = 4. The ``hybrid boundary condition(HBC)'' is adopted to discriminate a compact resonance state from scattering states. Only massive 5Q states are found for J^P=1/2^+ and 3/2^{\\pm}, which cannot be identified as \\Theta^+(1540). A low-lying 5Q state is found for J^P=1/2^- at m_{5Q}\\simeq 1.75 GeV, which however turns out to be an NK scattering state through the HBC analysis. A preliminary result for 4Q states is presented suggesting an existence of a compact 4Q resonance at m_{4Q} \\simeq 1.1 GeV in the idealized SU(4)_f chiral limit.
Quark–gluon plasma phenomenology from anisotropic lattice QCD
The FASTSUM collaboration has been carrying out simulations of Nf = 2 + 1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics
Quark–gluon plasma phenomenology from anisotropic lattice QCD
Skullerud, Jon-Ivar; Kelly, Aoife [Department of Mathematical Physics, Maynooth University, Maynooth, Co Kildare (Ireland); Aarts, Gert; Allton, Chris; Amato, Alessandro; Evans, P. Wynne M.; Hands, Simon [Department of Physics, Swansea University, Swansea SA2 8PP, Wales (United Kingdom); Burnier, Yannis [Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne, CH–1015 Lausanne (Switzerland); Giudice, Pietro [Institut für Theoretische Physik, Universität Münster, D–48149 Münster (Germany); Harris, Tim; Ryan, Sinéad M. [School of Mathematics, Trinity College, Dublin 2 (Ireland); Kim, Seyong [Department of Physics, Sejong University, Seoul 143-747 (Korea, Republic of); Lombardo, Maria Paola [INFN–Laboratori Nazionali di Frascati, I–00044 Frascati (RM) (Italy); Oktay, Mehmet B. [Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242 (United States); Rothkopf, Alexander [Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, D–69120 Heidelberg (Germany)
2016-01-22
The FASTSUM collaboration has been carrying out simulations of N{sub f} = 2 + 1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.
Quark-gluon plasma phenomenology from anisotropic lattice QCD
Skullerud, Jon-Ivar; Allton, Chris; Amato, Alessandro; Burnier, Yannis; Evans, P Wynne M; Giudice, Pietro; Hands, Simon; Harris, Tim; Kelly, Aoife; Kim, Seyong; Lombardo, Maria Paola; Oktay, Mehmet B; Rothkopf, Alexander; Ryan, Sinéad M
2015-01-01
The FASTSUM collaboration has been carrying out simulations of N_f=2+1 QCD at nonzero temperature in the fixed-scale approach using anisotropic lattices. Here we present the status of these studies, including recent results for electrical conductivity and charge diffusion, and heavy quarkonium (charm and beauty) physics.
Spin 3/2 Penta-quarks in anisotropic lattice QCD
Ishii, N; Nemoto, Y; Oka, M; Suganuma, H
2005-01-01
A high-precision mass measurement for the pentaquark (5Q) Theta^+ in J^P=3/2^{\\pm} channel is performed in anisotropic quenched lattice QCD using a large number of gauge configurations as N_{conf}=1000. We employ the standard Wilson gauge action at beta=5.75 and the O(a) improved Wilson (clover) quark action with kappa=0.1210(0.0010)0.1240 on a 12^3 \\times 96 lattice with the renormalized anisotropy as a_s/a_t = 4. The Rarita-Schwinger formalism is adopted for the interpolating fields. Several types of the interpolating fields with isospin I=0 are examined such as (a) the NK^*-type, (b) the (color-)twisted NK^*-type, (c) a diquark-type. The chiral extrapolation leads to only massive states, i.e., m_{5Q} \\simeq 2.1-2.2 GeV in J^P=3/2^- channel, and m_{5Q} = 2.4-2.6 GeV in J^P=3/2^+ channel. The analysis with the hybrid boundary condition(HBC) is performed to investigate whether these states are compact 5Q resonances or not. No low-lying compact 5Q resonance states are found below 2.1GeV.
Multiple anisotropic collisions for advection-diffusion Lattice Boltzmann schemes
Ginzburg, Irina
2013-01-01
This paper develops a symmetrized framework for the analysis of the anisotropic advection-diffusion Lattice Boltzmann schemes. Two main approaches build the anisotropic diffusion coefficients either from the anisotropic anti-symmetric collision matrix or from the anisotropic symmetric equilibrium distribution. We combine and extend existing approaches for all commonly used velocity sets, prescribe most general equilibrium and build the diffusion and numerical-diffusion forms, then derive and compare solvability conditions, examine available anisotropy and stable velocity magnitudes in the presence of advection. Besides the deterioration of accuracy, the numerical diffusion dictates the stable velocity range. Three techniques are proposed for its elimination: (i) velocity-dependent relaxation entries; (ii) their combination with the coordinate-link equilibrium correction; and (iii) equilibrium correction for all links. Two first techniques are also available for the minimal (coordinate) velocity sets. Even then, the two-relaxation-times model with the isotropic rates often gains in effective stability and accuracy. The key point is that the symmetric collision mode does not modify the modeled diffusion tensor but it controls the effective accuracy and stability, via eigenvalue combinations of the opposite parity eigenmodes. We propose to reduce the eigenvalue spectrum by properly combining different anisotropic collision elements. The stability role of the symmetric, multiple-relaxation-times component, is further investigated with the exact von Neumann stability analysis developed in diffusion-dominant limit.
Yoon, B; Engelhardt, M; Green, J; Gupta, R; Hägler, P; Musch, B; Negele, J; Pochinsky, A; Syritsyn, S
2016-01-01
We present a lattice QCD calculation of transverse momentum dependent parton distribution functions (TMDs) of protons using staple-shaped Wilson lines. For time-reversal odd observables, we calculate the generalized Sivers and Boer-Mulders transverse momentum shifts in SIDIS and DY cases, and for T-even observables we calculate the transversity related to the tensor charge and the generalized worm-gear shift. The calculation is done on two different n_f=2+1 ensembles: domain-wall fermion (DWF) with lattice spacing 0.084 fm and pion mass of 297 MeV, and clover fermion with lattice spacing 0.114 fm and pion mass of 317 MeV. The results from those two different discretizations are consistent with each other.
Overlap fermions are particularly well suited to study the finite temperature dynamics of the chiral symmetry restoration transition of QCD, which might be just an analytic crossover. Using gauge field configurations on a 243 x 10 lattice with Nf=2 flavours of dynamical Wilson-clover quarks generated by the DIK collaboration, we compute the lowest 50 eigenmodes of the overlap Dirac operator and try to locate the transition by fermionic means. We analyse the spectral density, local chirality and localisation properties of the low-lying modes and illustrate the changing topological and (anti-) selfdual structure of the underlying gauge fields across the transition. (orig.)
Lattice-Boltzmann hydrodynamics of anisotropic active matter
de Graaf, Joost; Menke, Henri; Mathijssen, Arnold J. T. M.; Fabritius, Marc; Holm, Christian; Shendruk, Tyler N.
2016-04-01
A plethora of active matter models exist that describe the behavior of self-propelled particles (or swimmers), both with and without hydrodynamics. However, there are few studies that consider shape-anisotropic swimmers and include hydrodynamic interactions. Here, we introduce a simple method to simulate self-propelled colloids interacting hydrodynamically in a viscous medium using the lattice-Boltzmann technique. Our model is based on raspberry-type viscous coupling and a force/counter-force formalism, which ensures that the system is force free. We consider several anisotropic shapes and characterize their hydrodynamic multipolar flow field. We demonstrate that shape-anisotropy can lead to the presence of a strong quadrupole and octupole moments, in addition to the principle dipole moment. The ability to simulate and characterize these higher-order moments will prove crucial for understanding the behavior of model swimmers in confining geometries.
Mott transition and magnetism on the anisotropic triangular lattice
Acheche, S.; Reymbaut, A.; Charlebois, M.; Sénéchal, D.; Tremblay, A.-M.S.
2016-01-01
Spin-liquid behavior was recently suggested experimentally in the moderately one-dimensional organic compound $\\kappa$-H$_3$(Cat-EDT-TTF)$_2$. This compound can be modeled by the one-band Hubbard model on the anisotropic triangular lattice with $t^\\prime/t \\simeq 1.5$, where $t'$ is the minority hopping. It thus becomes important to extend previous studies, that were performed in the range $0 \\leq t'/t \\leq 1.2$, to find out whether there is a regime where Mott insulating behavior can be foun...
Measuring the aspect ratio renormalization of anisotropic-lattice gluons
Using tadpole-improved actions we investigate the consistency between different methods of measuring the aspect ratio renormalization of anisotropic-lattice gluons for bare aspect ratios χ0=4,6,10 and inverse lattice spacing in the range as-1=660--840 MeV. The tadpole corrections to the action, which are established self-consistently, are defined for two cases, mean link tadpoles in the Landau gauge and gauge invariant mean plaquette tadpoles. Parameters in the latter case exhibited no dependence on the spatial lattice size L, while in the former, parameters showed only a weak dependence on L easily extrapolated to L=∞. The renormalized anisotropy χR was measured using both the torelon dispersion relation and the sideways potential method. There is general agreement between these approaches, but there are discrepancies which are evidence for the presence of lattice artifact contributions. For the torelon these are estimated to be O(αSas2/R2), where R is the flux-tube radius. We also present some new data that suggest that rotational invariance is established more accurately for the mean-link action than the plaquette action
Correlations in the Ising antiferromagnet on the anisotropic kagome lattice
We study the correlation function of middle spins, i.e. of spins on intermediate sites between two adjacent parallel lattice axes, of the spatially anisotropic Ising antiferromagnet on the kagome lattice. It is given rigorously by a Toeplitz determinant. The large-distance behaviour of this correlation function is obtained by analytic methods. For shorter distances we evaluate the Toeplitz determinant numerically. The correlation function is found to vanish exactly on a line Jd(T) in the T − J (temperature versus coupling constant) phase diagram. This disorder line divides the phase diagram into two regions. For J d(T) the correlations display the features of an unfrustrated two-dimensional Ising magnet, whereas for J > Jd(T) the correlations between the middle spins are seen to be strongly influenced by the short-range antiferromagnetic order that prevails among the spins of the adjacent lattice axes. While for J d(T) there is a region with ferrimagnetic long-range order, the model remains disordered for J > Jd(T) down to T = 0
Anisotropic square lattice Potts ferromagnet: renormalization group treatment
The choice of a convenient self-dual cell within a real space renormalization group framework enables a satisfactory treatment of the anisotropic square lattice q-state Potts ferromagnet criticality. The exact critical frontier and dimensionality crossover exponent PHI as well as the expected universality behaviour (renormalization flow sense) are recovered for any linear scaling factor b and all values of q(q -< 4). The b = 2 and b = 3 approximate correlation lenght critical exponent ν is calculated for all values of q and compared with den Nijs conjecture. The same calculation is performed, for all values of b, for the exponent ν(d=1) associated to the one-dimensional limit and the exact result ν (d=1) = 1 is recovered in the limit b → infinite. (Author)
Penta-Quark Anti-Decuplet in Anisotropic Lattice QCD
Ishii, N; Iida, H; Oka, M; Okiharu, F; Suganuma, H
2005-01-01
The penta-quark(5Q) Theta^+(1540) is studied in anisotropic lattice QCD with renormalized anisotropy a_s/a_t=4 for a high-precision measurement. Both the positive and the negative parity 5Q baryons are studied using a non-NK type interpolating field with I=0 and J=1/2. After the chiral extrapolation, the lowest positive parity state is found at m_{Theta}\\simeq 2.25 GeV, which is too heavy to be identified with Theta^+(1540). In the negative parity channel, the lowest energy state is found at m_{Theta}\\simeq 1.75 GeV. Although it is rather close to the empirical value, it is considered to be an NK scattering state rather than a localized resonance state.
Lattice models of directed and semiflexible polymers in anisotropic environment
Haydukivska, K.; Blavatska, V.
2015-10-01
We study the conformational properties of polymers in presence of extended columnar defects of parallel orientation. Two classes of macromolecules are considered: the so-called partially directed polymers with preferred orientation along direction of the external stretching field and semiflexible polymers. We are working within the frames of lattice models: partially directed self-avoiding walks (PDSAWs) and biased self-avoiding walks (BSAWs). Our numerical analysis of PDSAWs reveals, that competition between the stretching field and anisotropy caused by presence of extended defects leads to existing of three characteristic length scales in the system. At each fixed concentration of disorder we found a transition point, where the influence of extended defects is exactly counterbalanced by the stretching field. Numerical simulations of BSAWs in anisotropic environment reveal an increase of polymer stiffness. In particular, the persistence length of semiflexible polymers increases in presence of disorder.
Lattice models of directed and semiflexible polymers in anisotropic environment
We study the conformational properties of polymers in presence of extended columnar defects of parallel orientation. Two classes of macromolecules are considered: the so-called partially directed polymers with preferred orientation along direction of the external stretching field and semiflexible polymers. We are working within the frames of lattice models: partially directed self-avoiding walks (PDSAWs) and biased self-avoiding walks (BSAWs). Our numerical analysis of PDSAWs reveals, that competition between the stretching field and anisotropy caused by presence of extended defects leads to existing of three characteristic length scales in the system. At each fixed concentration of disorder we found a transition point, where the influence of extended defects is exactly counterbalanced by the stretching field. Numerical simulations of BSAWs in anisotropic environment reveal an increase of polymer stiffness. In particular, the persistence length of semiflexible polymers increases in presence of disorder. (paper)
Penta-quark baryon in anisotropic lattice QCD
Ishii, N; Iida, H; Oka, M; Okiharu, F; Suganuma, H
2005-01-01
The penta-quark(5Q) baryon is studied in anisotropic quenched lattice QCD with renormalized anisotropy a_s/a_t=4 for a high-precision mass measurement. The standard Wilson action at beta=5.75 and the O(a) improved Wilson quark action with kappa=0.1210(0.0010)0.1240 are employed on a 12^3 \\times 96 lattice. Contribution of excited states is suppressed by using a smeared source. We investigate both the positive- and negative-parity 5Q baryons with I=0 and spin J=1/2 using a non-NK-type interpolating field. After chiral extrapolation, the lowest positive-parity state is found to have a mass, m_{Theta}=2.25 GeV, which is much heavier than the experimentally observed Theta^+(1540). The lowest negative-parity 5Q appears at m_{Theta}=1.75 GeV, which is near the s-wave NK threshold. To distinguish spatially-localized 5Q resonances from NK scattering states, we propose a new general method imposing a ``Hybrid Boundary Condition (HBC)'', where the NK threshold is artificially raised without affecting compact five-quark...
Green's function approach to the anisotropic Kondo-necklace lattice
Full text: We have studied the effect of anisotropy on the quantum phase transition of the 2D anisotropic Kondo necklace lattice [1] within a Green's function approach [2]. In the disordered phase the ground state is the product of all singlet bonds between itinerant and localized spins. It is separated by a finite energy gap from the triplet excited states. The quantum phase transition to the antiferromagnetically ordered phase takes place where the gap vanishes. In this approach we use the bond operator formalism introduced in Ref.[3] where each bond is represented by the singlet and triplet operators. The Kondo necklace Hamiltonian in the bond operator representation is composed of the kinetic energy and pairing part (H2), the two particle interaction (H4) of the boson gas and a term which includes three boson operators (H3). In order to ensure that the physical states are either singlets or triplets we impose the hard-core condition by introducing an infinite on-site repulsion between triplet bosons (HU). The scattering vertex in the ladder approximation satisfies the Bethe-Salpeter equation [4]. By calculating the scattering vertex function we obtain the self energy contribution of the Hamiltonian HU. We have added the second order contribution of the self energy of H3 to the self energy of HU. It should be noted that the non conservation of triplet boson numbers requires the inclusion of the anomalous Green's functions. We treat H4 in mean-field theory, by splitting the quartic operator into all possible pairs. Finally we obtain the renormalization of coefficients in the H2 Hamiltonian and calculate the energy gap. Indeed at the critical point a condensation of triplet bosons occurs. We have numerically found the critical point of this model and compared our results with the corresponding mean field values [5]. Moreover, the critical exponent of the energy gap can be obtained more accurately than the mean field results. (authors)
Dipolar matter-wave solitons in two-dimensional anisotropic discrete lattices
Chen, Huaiyu; Liu, Yan; Zhang, Qiang; Shi, Yuhan; Pang, Wei; Li, Yongyao
2016-05-01
We numerically demonstrate two-dimensional (2D) matter-wave solitons in the disk-shaped dipolar Bose-Einstein condensates (BECs) trapped in strongly anisotropic optical lattices (OLs) in a disk's plane. The considered OLs are square lattices which can be formed by interfering two pairs of plane waves with different intensities. The hopping rates of the condensates between two adjacent lattices in the orthogonal directions are different, which gives rise to a linearly anisotropic system. We find that when the polarized orientation of the dipoles is parallel to disk's plane with the same direction, the combined effects of the linearly anisotropy and the nonlocal nonlinear anisotropy strongly influence the formations, as well as the dynamics of the lattice solitons. Particularly, the isotropy-pattern solitons (IPSs) are found when these combined effects reach a balance. Motion, collision, and rotation of the IPSs are also studied in detail by means of systematic simulations. We further find that these IPSs can move freely in the 2D anisotropic discrete system, hence giving rise to an anisotropic effective mass. Four types of collisions between the IPSs are identified. By rotating an external magnetic field up to a critical angular velocity, the IPSs can still remain localized and play as a breather. Finally, the influences from the combined effects between the linear and the nonlocal nonlinear anisotropy with consideration of the contact and/or local nonlinearity are discussed too.
Equation of state for pure SU(3) gauge theory on anisotropic lattices
We present results for the equation of state for pure SU(3) gauge theory obtained on anisotropic lattices with the anisotropy ξ ≡ as/at = 2. The pressure and energy density are calculated on Nt/ξ = 4, 5 and 6 lattices with the integral method. They are found to satisfy the leading 1/Nt2 scaling from our coarsest lattice Nt/ξ = 4. This enables us to carry out well controlled continuum extrapolations. We find that the pressure and energy density agree with those obtained using the isotropic plaquette action, but have smaller and more reliable errors
Photorefractive writing and probing of anisotropic linear and nonlinear lattices
We study experimentally the writing of one- and two-dimensional photorefractive lattices, focusing on the often overlooked transient regime. Our measurements agree well with theory, in particular concerning the ratio of the drift to diffusion terms. We then study the transverse dynamics of coherent waves propagating in the lattices, in a few novel and simple configurations. For defocusing linear waves with broad transverse spectrum, we remark that both the intensity distributions in real space (‘discrete diffraction’) and Fourier space (‘Brillouin zone spectroscopy’) reflect the Bragg planes and band structure. For nonlinear waves, we observe modulational instability and discrete solitons formation in time domain. We discuss also the non-ideal effects inherent to the photo-induction technique: anisotropy, residual nonlinearity, diffusive term, non-stationarity. (paper)
Anisotropic intrinsic lattice thermal conductivity of phosphorene from first principles
Qin, Guangzhao; Yan, Qing-Bo; Qin, Zhenzhen; Yue, Sheng-Ying; Hu, Ming; Su, Gang
2014-01-01
Phosphorene, the single layer counterpart of black phosphorus, is a novel two-dimensional semiconductor with high carrier mobility and a large fundamental direct band gap, which has attracted tremendous interest recently. Its potential applications in nano-electronics and thermoelectrics call for a fundamental study of the phonon transport. Here, we calculate the intrinsic lattice thermal conductivity of phosphorene by solving the phonon Boltzmann transport equation (BTE) based on first-princ...
Survival of charmonia above Tc in anisotropic lattice QCD
We find a strong evidence for the survival of J/Ψ and ηc as spatially-localized cc-bar (quasi-)bound states above the QCD critical temperature Tc, by investigating the boundary-condition dependence of their energies and spectral functions. In a finite-volume box, there arises a boundary-condition dependence for spatially spread states, while no such dependence appears for a partially compact states. In lattice QCD, we find almost no spatial boundary-condition dependence for the energy of the cc-bar system in J/Ψ and ηc channels for T ≅ (1.11 - 2.07)Tc. We also investigate the spectral function of charmonia above Tc in lattice QCD using the maximum entropy method (MEM) in terms of the boundary-condition dependence. There is no spatial boundary-condition dependence for the low-lying peaks corresponding to J/Ψ and ηc around 3 GeV at 1.62 Tc. These facts indicate the survival of J/Ψ and ηc as compact cc-bar (quasi-)bound states for Tc c. (author)
Discrete solitons and vortices in anisotropic hexagonal and honeycomb lattices
Hoq, Q. E.; Kevrekidis, P. G.; Bishop, A. R.
2016-02-01
In the present work, we consider the self-focusing discrete nonlinear Schrödinger equation on hexagonal and honeycomb lattice geometries. Our emphasis is on the study of the effects of anisotropy, motivated by the tunability afforded in recent optical and atomic physics experiments. We find that multi-soliton and discrete vortex states undergo destabilizing bifurcations as the relevant anisotropy control parameter is varied. We quantify these bifurcations by means of explicit analytical calculations of the solutions, as well as of their spectral linearization eigenvalues. Finally, we corroborate the relevant stability picture through direct numerical computations. In the latter, we observe the prototypical manifestation of these instabilities to be the spontaneous rearrangement of the solution, for larger values of the coupling, into localized waveforms typically centered over fewer sites than the original unstable structure. For weak coupling, the instability appears to result in a robust breathing of the relevant waveforms.
Anisotropic lattice thermal conductivity in chiral tellurium from first principles
Using ab initio based calculations, we have calculated the intrinsic lattice thermal conductivity of chiral tellurium. We show that the interplay between the strong covalent intrachain and weak van der Waals interchain interactions gives rise to the phonon band gap between the lower and higher optical phonon branches. The underlying mechanism of the large anisotropy of the thermal conductivity is the anisotropy of the phonon group velocities and of the anharmonic interatomic force constants (IFCs), where large interchain anharmonic IFCs are associated with the lone electron pairs. We predict that tellurium has a large three-phonon scattering phase space that results in low thermal conductivity. The thermal conductivity anisotropy decreases under applied hydrostatic pressure
Anisotropic lattice thermal conductivity in chiral tellurium from first principles
Peng, Hua; Kioussis, Nicholas; Stewart, Derek A.
2015-12-01
Using ab initio based calculations, we have calculated the intrinsic lattice thermal conductivity of chiral tellurium. We show that the interplay between the strong covalent intrachain and weak van der Waals interchain interactions gives rise to the phonon band gap between the lower and higher optical phonon branches. The underlying mechanism of the large anisotropy of the thermal conductivity is the anisotropy of the phonon group velocities and of the anharmonic interatomic force constants (IFCs), where large interchain anharmonic IFCs are associated with the lone electron pairs. We predict that tellurium has a large three-phonon scattering phase space that results in low thermal conductivity. The thermal conductivity anisotropy decreases under applied hydrostatic pressure.
The uncorrelated bond percolation problem is studied in three planar systems where there are two distinct occupancy probabilities. Two different real space renormalization group approaches (referred as the 'canonical' (CRG) and the 'parametric' (PRG) ones) are applied to the anisotropic first-neighbour square lattice, and both of them exhibit the expected tendency towards the exactly known phase boundary (p+q=1). Then, within the context of PRG calculations for increasingly large cells, an extrapolation method is introduced, which leads to analytic proposals for the other two lattices, namely p+q = 1/2 for the first-and second-neighbour square lattice (p and q are, respectively, the first and second neighbour occupancy probabilities), and 3 (p-1/2) = 4 [(1-q)2 + (1-q)3] (p and q are, respectively, the occupancy probabilities of the topologically different bonds which are in a 1:2 ratio) for the 4- 8 lattice. (Author)
Anisotropic magneto-resistance in Ni80Fe20 antidot arrays with different lattice configurations
Highlights: • Detailed study of the magnetisation processes in antidot lattices. • Combined magnetic (MFM), magneto-transport (AMR) and numerical investigations. • Accounting for the experimentally observed differences in AMR signal amplitude in longitudinal and transverse configurations through numerical simulations. - Abstract: Ni80Fe20 antidot arrays having different lattice geometrical properties and irregularities were prepared via electron beam lithography and self-assembling of polystyrene nanospheres. All the samples were experimentally characterised by magnetic force microscopy and room-temperature magneto-resistance measurements in different configurations. The analysis, supported by micromagnetic simulations, has been focused on the effect of lattice geometry on the magneto-resistance behaviour of these systems. The detailed investigation through micromagnetic simulations of the magnetic domain configuration as a function of the applied field allows a complete understanding of the qualitative and quantitative difference of anisotropic magneto-resistance properties that have been measured in samples with different lattice geometries and in different measurement configurations
Quenched Charmed Meson Spectra Using Tadpole Improved Quark Action on Anisotropic Lattices
LIU Liu-Ming; SU Shi-Quan; LI Xin; LIU Chuan
2005-01-01
@@ Charmed meson charmonium spectra are studied with improved quark actions on anisotropic lattices. We measured the pseudo-scalar and vector meson dispersion relations for four lowest lattice momentum modes with quark mass values ranging from the strange quark to charm quark with three different values of gauge coupling β and four different values of bare speed of light v. With the bare speed of light parameter v tuned in a mass-dependent way, we study the mass spectra of D, Ds, ηc, D*, Ds* and J/ψ mesons. The results extrapolated to the continuum limit are compared with the experiment, and a qualitative agreement is found.
Solution of the Transport Equations for two-Medium Slab Lattice with Anisotropic Scattering
The transport equations for two-medium slab lattice are studied. The neutron density distributions and the disadvantage factor for thermal neutrons in water moderated, highly enriched uranium and uranium oxide fuel lattices were obtained with its external surface with reflection coefficient R ? 1. Three coupled integral equations for the fluxes in the fuel and moderator are obtained. The Galerkin-method is used to solve the coupled integral equations for two-medium. The calculations are carried out for isotropic and anisotropic scattering in the moderator region and isotropic scattering in the fuel region. Numerical results are compared with the published calculations
Anisotropic Hubbard model on a triangular lattice - spin dynamics in HoMnO3
Saptarshi Ghosh; Avinash Singh
2008-01-01
The recent neutron scattering data for spin-wave dispersion in HoMnO3 are well-described by an anisotropic Hubbard model on a triangular lattice with a planar (XY) spin anisotropy. Best fit indicates that magnetic excitations in HoMnO3 correspond to the strong-coupling limit / > ∼ 15, with planar exchange energy = 42/ ≃ 2.5 meV and planar anisotropy ≃ 0.35 meV.
Lattice dynamical appraisal of the anisotropic Debye-Waller factors in graphite lattice
The Debye-Waller factors in graphite for the atomic motions within the basal plane and also across the basal planes have been calculated using the various lattice dynamical models available to date and a critical comparison is made with the existing experimental data from X ray and neutron scattering studies. The present study reveals the need for further investigation on the nature of atomic motion across the basal planes. (author). 15 refs, 1 tab
Spin superfluidity in the anisotropic XY model in the triangular lattice
Lima, L. S.
2016-07-01
We use the SU(3) Schwinger's boson theory to study the spin transport properties in the two-dimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: = = t . Our results show a metallic spin transport for ω > 0 and a superfluid spin transport in the limit of DC conductivity, ω → 0 , where σ(ω) tends to infinity in this limit of ω.
Edge states in a honeycomb lattice: effects of anisotropic hopping and mixed edges
Dahal, Hari P.; Hu, Zi-Xiang; Sinitsyn, N. A.; YANG Kun; Balatsky, A. V.
2009-01-01
We study the edge states in graphene in the presence of a magnetic field perpendicular to the plane of the lattice. Most of the works done so far discuss the edge states in either zigzag or armchair edge graphene considering an isotropic electron hopping. In practice, graphene can have mixture of armchair and zigzag edges and the electron hopping can be anisotropic, which is the subject of this article. We predict that the mixed edges smear the enhanced local density of states (LDOS) at E=0 o...
Vortex pumps in the crossing lattices regime of highly anisotropic layered superconductors
It is now well established that vortex dynamics in samples with a spatially asymmetric pinning potential can lead to rectifying vortex 'diode' behaviour. Spatial asymmetry is not a fundamental requirement for the control of vortex motion, however, and we demonstrate that vortex 'lensing' is possible in highly anisotropic layered superconductors simply under the action of non time-reversible trains of in-plane magnetic field pulses. Our devices depend crucially on the existence of 'crossing' pancake vortex (PV) and Josephson vortex (JV) lattices in Bi2Sr2CaCu2O8+δ (BSCCO) single crystals under tilted magnetic fields. An attractive interaction between these two sub-lattices makes it possible to indirectly manipulate the PV distribution by modifying the JV lattice, and a number of functional devices based on this principle have been proposed. In our experiments a BSCCO single crystal is placed on a Hall probe array, and cooled below T c in a small out-of- plane magnetic field. Trains of sawtooth in-plane field pulses are then applied to the system and different elements of the Hall array used to demonstrate PV lensing or antilensing behaviour, depending on the pulse shape. The mechanism leading to lensing will be discussed and results compared with molecular dynamics simulations
Chai, Zhenhua; Guo, Zhaoli
2016-01-01
In this paper, based on the previous work [B. Shi, Z. Guo, Lattice Boltzmann model for nonlinear convection-diffusion equations, Phys. Rev. E 79 (2009) 016701], we develop a general multiple-relaxation-time (MRT) lattice Boltzmann model for nonlinear anisotropic convection-diffusion equation (NACDE), and show that the NACDE can be recovered correctly from the present model through the Chapman-Enskog analysis. We then test the MRT model through some classic CDEs, and find that the numerical results are in good agreement with analytical solutions or some available results. Besides, the numerical results also show that similar to the single-relaxation-time (SRT) lattice Boltzmann model or so-called BGK model, the present MRT model also has a second-order convergence rate in space. Finally, we also perform a comparative study on the accuracy and stability of the MRT model and BGK model by using two examples. In terms of the accuracy, both the theoretical analysis and numerical results show that a \\emph{numerical}...
Cluster Mott insulators and two Curie-Weiss regimes on an anisotropic kagome lattice
Chen, Gang; Kee, Hae-Young; Kim, Yong Baek
2016-06-01
Motivated by recent experiments on the quantum-spin-liquid candidate material LiZn2Mo3O8 , we study a single-band extended Hubbard model on an anisotropic kagome lattice with the 1/6 electron filling. Due to the partial filling of the lattice, the intersite repulsive interaction is necessary to generate Mott insulators, where electrons are localized in clusters rather than at lattice sites. It is shown that these cluster Mott insulators are generally U(1) quantum spin liquids with spinon Fermi surfaces. The nature of charge excitations in cluster Mott insulators can be quite different from conventional Mott insulator and we show that there exists a cluster Mott insulator where charge fluctuations around the hexagonal cluster induce a plaquette charge order (PCO). The spinon excitation spectrum in this spin-liquid cluster Mott insulator is reconstructed due to the PCO so that only 1/3 of the total spinon excitations are magnetically active. Based on these results, we propose that the two Curie-Weiss regimes of the spin susceptibility in LiZn2Mo3O8 may be explained by finite-temperature properties of the cluster Mott insulator with the PCO as well as fractionalized spinon excitations. Existing and possible future experiments on LiZn2Mo3O8 , and other Mo-based cluster magnets are discussed in light of these theoretical predictions.
Meson and baryon spectroscopy on the lattice
David Richards
2010-12-01
Recent progress at understanding the excited state spectrum of mesons and baryons is described. I begin by outlining the application of the variational method to compute the spectrum, and the program of anisotropic clover lattice generation designed for hadron spectroscopy. I present results for the excited meson spectrum, with continuum quantum numbers of the states clearly delineated. I conclude with recent results for the low lying baryon spectrum, and the prospects for future calculations.
The Ising antiferromagnetic in the presence of a magnetic field on an anisotropic square lattice is studied by Monte Carlo simulation. We obtained the phase diagram in the T-H plane investigating the reentrant behavior around of the critical field Hc=2Jy. Using the Binder cumulant we locate the critical temperature Tc as a function of H. In order to test our simulation, for null field we obtain the critical behavior of Tc as a function of r=Jy/Jx and is in excellent agreement with exact solution of Onsager. Our results indicate a second-order transition for all values of H and particular case r=1 (independent of the ratio r≠0), where not reentrant behavior was observed.
Lima, L. S.
2016-07-01
We use the SU(3) Schwinger's boson theory to study the spin transport properties of the two-dimensional anisotropic frustrated Heisenberg model in a honeycomb lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents a single-ion anisotropy and J1 and J2 exchange interactions. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: = = t. Our results show a metallic spin transport for ω > 0 and a superconductor spin transport in the limit of DC conductivity, ω → 0, where σ(ω) tends to infinity in this limit of ω.
Anisotropic Lattice QCD Studies of Penta-quark Anti-decuplet
Ishii, N; Iida, H; Oka, M; Okiharu, F; Suganuma, H
2004-01-01
Anti-decuplet penta-quark baryon is studied with the quenched anisotropic lattice QCD for accurate measurement of the correlator. Both the positive and negative parity states are studied using a non-NK type interpolating field with I=0 and J=1/2. After the chiral extrapolation, the lowest positive parity state is found at m_{Theta} \\simeq 2.25 GeV, which is too massive to be identified with the experimentally observed Theta^+(1540). The lowest negative parity state is found at m_{Theta}\\simeq 1.75 GeV, which is rather close to the empirical value. To confirm that this state is a compact 5Q resonance, a new method with ``hybrid boundary condition (HBC)'' is proposed. The HBC analysis shows that the observed state in the negative parity channel is an NK scattering state.
Renormalisation of gauge theories on general anisotropic lattices and high-energy scattering in QCD
Giordano, Matteo
2015-01-01
We study the renormalisation of $SU(N_c)$ gauge theories on general anisotropic lattices, to one-loop order in perturbation theory, employing the background field method. The results are then applied in the context of two different approaches to hadronic high-energy scattering. In the context of the Euclidean nonperturbative approach to soft high-energy scattering based on Wilson loops, we refine the nonperturbative justification of the analytic continuation relations of the relevant Wilson-loop correlators, required to obtain physical results. In the context of longitudinally-rescaled actions, we study the consequences of one-loop corrections on the relation between the $SU(N_c)$ gauge theory and its effective description in terms of two-dimensional principal chiral models.
Phase transition in 2-d system of quadrupoles on square lattice with anisotropic field
Monte Carlo method is used to study a simple model of two-dimensional interacting quadrupoles on ionic square lattice with anisotropic strength provided by the ionic lattice. Order parameter, susceptibility and correlation function data, show that this system form an ordered structure with p(2×1) symmetry at low temperature. The p(2×1) structure undergoes an order-disorder phase transition into disordered (1×1) phase at 8.3K. The two-point correlation function show exponential dependence on distance both above and below the transition temperature. At Tc the two-point correlation function shows a power law dependence on distance, e.g. C(r) ∼ 1η. The value of the exponent η at Tc shows small deviation from the Ising value and indicates that this system falls into the same universality class as the XY model with cubic anisotropy. This model can be applied to prototypical quadrupoles physisorbed systems as N2 on NaCl(100)
Magnetic phases of spin-(3/2) fermions on a spatially anisotropic square lattice
We study the magnetic phase diagram of spin-(3/2) fermions in a spatially anisotropic square optical lattice at quarter filling (corresponding to one particle per lattice site). In the limit of the large on-site repulsion the system can be mapped to the so-called Sp(N) Heisenberg spin model with N=4. We analyze the Sp(N) spin model with the help of the large-N field-theoretical approach and show that the effective theory corresponds to the Sp(N) extension of the CPN-1 model, with the Lorentz invariance generically broken. We obtain the renormalization flow of the model couplings and show that although the Sp(N) terms are seemingly irrelevant, their presence leads to a renormalization of the CPN-1 part of the action, driving a phase transition. We further consider the influence of the external magnetic field (the quadratic Zeeman effect) and present the qualitative analysis of the ground-state phase diagram.
For high-temperature superconductors the shape of a NMR spectrum line is built regarding for variation of inhomogeneity of irregular vortex lattice magnetic field near superconductor surface. It is shown that the shape of a NMR line is not simply widened but noticeably varies depending on the degree of irregularity of a superconductor vortex lattice. This variation is associated with a local symmetry decrease in an irregular vortex lattice of the superconductor. Taking into account these circumstances may considerably change conclusions about the type of a vortex lattice and superconductor parameters which are commonly gained from NMR line shape analysis
Finite Temperature Lattice QCD - Baryons in the Quark-Gluon Plasma
Aarts, Gert; De Boni, Davide; Hands, Simon; Jäger, Benjamin; Praki, Chrisanthi; Skullerud, Jon-Ivar
2016-01-01
Baryonic correlation functions provide an ideal tool to study parity doubling and chiral symmetry using lattice simulations. We present a study using $2+1$ flavors of anisotropic Wilson clover fermions on the FASTSUM ensembles and find clear evidence that parity doubling emerges in the quark-gluon plasma. This result is confirmed on the level of spectral functions, which are obtained using a MEM reconstruction. We further highlight the importance of Gaussian smearing in this study.
Makino, Kotaro; Saito, Yuta; Fons, Paul; Kolobov, Alexander V.; Nakano, Takashi; Tominaga, Junji; Hase, Muneaki
2016-01-01
Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is parallel to the c–axis of the sample, while the pump polarization dependence is negligible when the probe polarization angle is perpendicular to the c–axis. The enhancement of phonon oscillation amplitude due to pump polarization rotation for a specific probe polarization angle is only found in the early time stage (≤2 ps). These results indicate that the origin of the pump and probe polarization dependence is dominantly attributable to the anisotropically-formed photo-excited carriers which cause the directional lattice dynamics. PMID:26805401
Makino, Kotaro; Saito, Yuta; Fons, Paul; Kolobov, Alexander V.; Nakano, Takashi; Tominaga, Junji; Hase, Muneaki
2016-01-01
Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is parallel to the c-axis of the sample, while the pump polarization dependence is negligible when the probe polarization angle is perpendicular to the c-axis. The enhancement of phonon oscillation amplitude due to pump polarization rotation for a specific probe polarization angle is only found in the early time stage (≤2 ps). These results indicate that the origin of the pump and probe polarization dependence is dominantly attributable to the anisotropically-formed photo-excited carriers which cause the directional lattice dynamics.
WANG Xian-Zhi
2001-01-01
Using the numerical results and some results from the renormalization group theory, we extend our previous approach of determining the Yang-Lee edge singularities of Ising ferromagnets on square, triangular and honeycomb lattices (Phys. Rev. Lett. 78 (1997) 413; Phys. Rev. E56 (1998) 2793; E57 (1998) 5013) and obtain accurate closed-form approximations of the critical lines of anisotropic Ising ferromagnets on these lattices.
Phil Diamond
2003-01-01
Full Text Available Sensitivity of output of a linear operator to its input can be quantified in various ways. In Control Theory, the input is usually interpreted as disturbance and the output is to be minimized in some sense. In stochastic worst-case design settings, the disturbance is considered random with imprecisely known probability distribution. The prior set of probability measures can be chosen so as to quantify how far the disturbance deviates from the white-noise hypothesis of Linear Quadratic Gaussian control. Such deviation can be measured by the minimal Kullback-Leibler informational divergence from the Gaussian distributions with zero mean and scalar covariance matrices. The resulting anisotropy functional is defined for finite power random vectors. Originally, anisotropy was introduced for directionally generic random vectors as the relative entropy of the normalized vector with respect to the uniform distribution on the unit sphere. The associated a-anisotropic norm of a matrix is then its maximum root mean square or average energy gain with respect to finite power or directionally generic inputs whose anisotropy is bounded above by a≥0. We give a systematic comparison of the anisotropy functionals and the associated norms. These are considered for unboundedly growing fragments of homogeneous Gaussian random fields on multidimensional integer lattice to yield mean anisotropy. Correspondingly, the anisotropic norms of finite matrices are extended to bounded linear translation invariant operators over such fields.
Photorefractive writing and probing of anisotropic linear and non-linear lattices
Allio, Raphaël; Cantillano, Camilo; Morales-Inostroza, Luis; Lopez-Gonzalez, Dany; Etcheverry, Sebastián; Vicencio, Rodrigo A; Armijo, Julien
2014-01-01
We experimentally study the writing of one- and two-dimensional photorefractive lattices and the propagation of linear and nonlinear waves inside them. Using plane waves, we perform a time-resolved study of lattice writing and find good agreement with transient and steady-state photorefractive theory. In particular, the ratio of the drift to diffusion terms is proportional to the lattice period. We then analyze various wave propagation schemes. For focussed linear waves with broad transverse spectrum, we note that both the intensity distributions in real space ("discrete diffraction") and Fourier space ("Brillouin zone spectroscopy") reflect the Bragg planes and band structure. For non-linear waves, we observe modulational instability and time-domain discrete solitons formation. We discuss also the non-ideal effects inherent to the photo-induction technique : anisotropy, parasitic nonlinearity, diffusive term, and non-stationarity.
Anisotropic Fast-Marching on cartesian grids using Lattice Basis Reduction
Mirebeau, Jean-Marie
2012-01-01
We introduce a modification of the Fast Marching Algorithm, which solves the generalized eikonal equation associated to an arbitrary continuous riemannian metric, on a two or three dimensional box domain. The algorithm has a logarithmic complexity in the maximum anisotropy ratio of the riemannian metric, which allows to handle extreme anisotropies for a reduced numerical cost. We establish that the output of the algorithm converges towards the viscosity solution of continuous problem, as the discretization step tends to zero. The algorithm is based on the computation at each grid point of a reduced basis of the unit lattice, with respect to the symmetric positive definite matrix encoding the desired anisotropy at this point.
In this work we study the critical behavior of the quantum spin-1/2 anisotropic Heisenberg antiferromagnet in the presence of a longitudinal field on a body centered cubic (bcc) lattice as a function of temperature, anisotropy parameter (Δ) and magnetic field (H), where Δ=0 and 1 correspond the isotropic Heisenberg and Ising models, respectively. We use the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). The staggered ms=(mA−mB)/2 and total m=(mA+mB)/2 magnetizations are numerically calculated, where in the limit of ms→0 the critical line TN(H,Δ) is obtained. The phase diagram in the T−H plane is discussed as a function of the parameter Δ for all values of H∈[0,Hc(Δ)], where Hc(Δ) correspond the critical field (TN=0). Special focus is given in the low temperature region, where a reentrant behavior is observed around of H=Hc(Δ)≥Hc(Δ=1)=8J in the Ising limit, results in accordance with Monte Carlo simulation, and also was observed for all values of Δ∈[0,1]. This reentrant behavior increases with increase of the anisotropy parameter Δ. In the limit of low field, our results for the Heisenberg limit are compared with series expansion values. - Highlights: ► In the lat decade there has been a great interest in the physics of the quantum phase transition in spins system. ► Effective-field theory in cluster with N=4 spins is generalized to treat the quantum spin-1/2 Heisenberg model. ► We have obtained phase diagram at finite temperature for the quantum spin-1/2 antiferromagnet Heisenberg model as a bcc lattice.
Wang, H. P.; Wu, D. S.; Shi, Y. G.; Wang, N. L.
2016-07-01
We present anisotropic transport and optical spectroscopy studies on EuCd2As2 . The measurements reveal that EuCd2As2 is a low carrier density semimetal with moderate anisotropic resistivity ratio. The charge carriers experience very strong scattering from Eu magnetic moments, resulting in a Kondo-like increase of resistivity at low temperature. Below the antiferromagnetic transition temperature at TN=9.5 K, the resistivity drops sharply due to the reduced scattering from the ordered Eu moments. Nevertheless, the anisotropic ratio of ρc/ρa b keeps increasing, suggesting that the antiferromagnetic coupling is along the c axis. The optical spectroscopy measurement further reveals, besides an overdamped reflectance plasma edge at low energy, a strong coupling between phonon and electronic continuum. Our study suggests that EuCd2As2 is a promising candidate displaying intriguing interplay among charge, magnetism, and the underlying crystal lattice.
We have studied the quantum spin-1/2 frustrated Heisenberg model with two ferromagnetic interactions: nearest-neighbor (NN) with different coupling strengths J1 and J1′ along x and y directions, respectively, competing with a next-nearest-neighbor (NNN) with coupling J2. Using the effective-field theory we obtain the ground-state phase diagram in the (λ,α) space, where λ=J1′/J1 and α=J2/J1. Depending on the values of λ and α we observe three different states: ferromagnetic (F), collinear ferromagnetic (CF) and quantum paramagnetic (QP). We observe a QP state between the ordered F and CF phases in the region λ1<λ<1 (λ1≃0.62). - Highlights: • We study the ferromagnetic J1−J1′−J2 model on an anisotropic square lattice by using effective-field theory. • We obtain the ground phase diagram in the λ−α plane (λ=J1′/J1 and α=J2/J1). • A comparison with the results of the antiferromagnetic J1−J1′−J2 model. • We propose a functional for the free energy
Lapa, Rodrigo S.; Mendonça, Griffith [Departamento de Fi' sica, Universidade Federal de Minas Gerais, CP 702, 30161-970 Belo Horizonte, MG (Brazil); Universidade Federal do Amazonas, Departamento de Fi' sica, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Roberto Viana, J. [Universidade Federal do Amazonas, Departamento de Fi' sica, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Ricardo de Sousa, J., E-mail: jsousa@ufam.edu.br [Universidade Federal do Amazonas, Departamento de Fi' sica, 3000, Japiim, 69077-000 Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, Universidade Federal do Amazonas, Departamento de Fisica, 3000, Japiim, 69077-000 Manaus, AM (Brazil)
2014-11-15
We have studied the quantum spin-1/2 frustrated Heisenberg model with two ferromagnetic interactions: nearest-neighbor (NN) with different coupling strengths J{sub 1} and J{sub 1}{sup ′} along x and y directions, respectively, competing with a next-nearest-neighbor (NNN) with coupling J{sub 2}. Using the effective-field theory we obtain the ground-state phase diagram in the (λ,α) space, where λ=J{sub 1}{sup ′}/J{sub 1} and α=J{sub 2}/J{sub 1}. Depending on the values of λ and α we observe three different states: ferromagnetic (F), collinear ferromagnetic (CF) and quantum paramagnetic (QP). We observe a QP state between the ordered F and CF phases in the region λ{sub 1}<λ<1 (λ{sub 1}≃0.62). - Highlights: • We study the ferromagnetic J{sub 1}−J{sub 1}{sup ′}−J{sub 2} model on an anisotropic square lattice by using effective-field theory. • We obtain the ground phase diagram in the λ−α plane (λ=J{sub 1}{sup ′}/J{sub 1} and α=J{sub 2}/J{sub 1}). • A comparison with the results of the antiferromagnetic J{sub 1}−J{sub 1}{sup ′}−J{sub 2} model. • We propose a functional for the free energy.
The texture-induced anisotropic mechanical behavior of a highly textured AA 7020-T6 (maximum orientation density of 29.7 multiple random distribution), was characterized by the lattice strain evolution along rolling direction (RD), 45° to RD and 90° to RD, respectively, under uniaxial tension using high energy X-ray diffraction. The uniaxial tensile tests were done till ultimate tensile strength (UTS), which show different yield strengths (YS), UTS and elongations along the three directions on a macroscopic level. On micromechanical level, the lattice strain evolution explains the correlation between crystallite orientation and different mechanical behavior, leading to the macroscopic anisotropy. In the elastic region, the sample 45° to RD has the lowest lattice plane dependent Young's modulus compared to the other two directions. In the elastic plastic transition region, lattice strain differences among different {hkl} lattice planes are highest for sample 45° to RD and lowest for sample 0° to RD. Moreover, the 45° to RD sample has the lowest lattice dependent YS. In the plastic region, the work hardening behavior of different {hkl} lattice planes in all three directions can be divided into two groups, corresponding to two types of dislocation combinations. However, {200} planes of samples 45° and 90° to RD behave abnormally due to the stress along <110> of the {200} planes and the orientation density of {200} planes parallel and perpendicular to the loading direction (LD)
Dürr, Stephan; Hoelbling, Christian; Krieg, Stefan; Lellouch, Laurent; Lippert, Thomas; Rae, Thomas; Schäfer, Andreas; Scholz, Enno E; Szabó, Kálmán K; Varnhorst, Lukas
2016-01-01
We present a calculation of the leptonic decay-constant ratio $f_K/f_\\pi$ in 2+1 flavor QCD, performed via a series of lattice studies, which allows us to quantify all sources of systematic uncertainty. Our final result is $f_K/f_\\pi=1.182(28)$, and with isospin breaking corrections from ChPT the charged decay-constant ratio reads $f_{K^\\pm}/f_{\\pi^\\pm}=1.178(28)$. With $V_\\mathrm{ud}$ from super-allowed nuclear beta decays, the CKM matrix element $V_\\mathrm{us}=0.2282(54)$ is perfectly compatible with the first-row unitarity constraint of the Standard Model.
Neto, Minos A., E-mail: minos@pq.cnpq.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); Roberto Viana, J., E-mail: vianafisica@bol.com.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); Ricardo de Sousa, J., E-mail: jsousa@edu.ufam.br [Departamento de Fisica, Universidade Federal do Amazonas, 3000, Japiim, Manaus, 69077-000 AM (Brazil); National Institute of Science and Technology for Complex Systems, 3000, Japiim, Manaus, 69077-000 AM (Brazil)
2012-08-15
In this work we study the critical behavior of the quantum spin-1/2 anisotropic Heisenberg antiferromagnet in the presence of a longitudinal field on a body centered cubic (bcc) lattice as a function of temperature, anisotropy parameter ({Delta}) and magnetic field (H), where {Delta}=0 and 1 correspond the isotropic Heisenberg and Ising models, respectively. We use the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). The staggered m{sub s}=(m{sub A}-m{sub B})/2 and total m=(m{sub A}+m{sub B})/2 magnetizations are numerically calculated, where in the limit of m{sub s}{yields}0 the critical line T{sub N}(H,{Delta}) is obtained. The phase diagram in the T-H plane is discussed as a function of the parameter {Delta} for all values of H Element-Of [0,H{sub c}({Delta})], where H{sub c}({Delta}) correspond the critical field (T{sub N}=0). Special focus is given in the low temperature region, where a reentrant behavior is observed around of H=H{sub c}({Delta}){>=}H{sub c}({Delta}=1)=8J in the Ising limit, results in accordance with Monte Carlo simulation, and also was observed for all values of {Delta} Element-Of [0,1]. This reentrant behavior increases with increase of the anisotropy parameter {Delta}. In the limit of low field, our results for the Heisenberg limit are compared with series expansion values. - Highlights: Black-Right-Pointing-Pointer In the lat decade there has been a great interest in the physics of the quantum phase transition in spins system. Black-Right-Pointing-Pointer Effective-field theory in cluster with N=4 spins is generalized to treat the quantum spin-1/2 Heisenberg model. Black-Right-Pointing-Pointer We have obtained phase diagram at finite temperature for the quantum spin-1/2 antiferromagnet Heisenberg model as a bcc lattice.
Quark propagators at finite temperature with the clover action
Hamada, M; Nakamura, A; Saitô, T; Yahiro, M; Hamada, Masatoshi; Kouno, Hiroaki; Nakamura, Atsushi; Saito, Takuya; Yahiro, Masanobu
2006-01-01
We study properties of the finite temperature quark propagator by using the SU(3) quenched lattice simulation in the Landau gauge and report numerical results of the standard Wilson quark case as well as the improved clover one. The mass function in the deconfinement phase is different from that of the confinement phase, especially at low momentum regions.
Decay constants of the pion and its excitations on the lattice.
Mastropas, Ekaterina V. [William and Mary College, JLAB; Richards, David G. [JLAB
2014-07-01
We present a calculation using lattice QCD of the ratios of decay constants of the excited states of the pion, to that of the pion ground state, at three values of the pion mass between 400 and 700 MeV, using an anisotropic clover fermion action with three flavors of quarks. We find that the decay constant of the first excitation, and more notably of the second, is suppressed with respect to that of the ground-state pion, but that the suppression shows little dependence on the quark mass. The strong suppression of the decay constant of the second excited state is consistent with its interpretation as a predominantly hybrid state.
Ghorbani, Elaheh; Tocchio, Luca F.; Becca, Federico
2016-02-01
By using variational wave functions and quantum Monte Carlo techniques, we investigate the complete phase diagram of the Heisenberg model on the anisotropic triangular lattice, where two out of three bonds have superexchange couplings J and the third one has instead J'. This model interpolates between the square lattice and the isotropic triangular one, for J'/J ≤1 , and between the isotropic triangular lattice and a set of decoupled chains, for J /J'≤1 . We consider all the fully symmetric spin liquids that can be constructed with the fermionic projective-symmetry group classification (Zhou and Wen, arXiv:cond-mat/0210662) and we compare them with the spiral magnetic orders that can be accommodated on finite clusters. Our results show that, for J'/J ≤1 , the phase diagram is dominated by magnetic orderings, even though a spin-liquid state may be possible in a small parameter window, i.e., 0.7 ≲J'/J ≲0.8 . In contrast, for J /J'≤1 , a large spin-liquid region appears close to the limit of decoupled chains, i.e., for J /J'≲0.6 , while magnetically ordered phases with spiral order are stabilized close to the isotropic point.
Evidence for a bound H-dibaryon from lattice QCD
Beane, S R; Detmold, W; Lin, H W; Luu, T C; Orginos, K; Parreno, A; Savage, M J; Torok, A; Walker-Loud, A
2011-04-01
We present evidence for the existence of a bound H-dibaryon, an I = 0, J = 0, s = -2 state with valence quark structure uuddss, at a pion mass of m_\\pi < 389 MeV. Extrapolating the results of lattice QCD calculations performed on four ensembles of anisotropic clover gauge-field configurations, with spatial extents of L < 2.0, 2.5, 3.0 and 3.9 fm at a spatial lattice spacing of b_s < 0.123 fm, we find an H-dibaryon bound by B_ ^H = 16.6±2.1±4.6 MeV at a pion mass of m_\\pi < 389 MeV.
Kotaro Makino; Yuta Saito; Paul Fons; Kolobov, Alexander V.; Takashi Nakano; Junji Tominaga; Muneaki Hase
2016-01-01
Optical excitation of matter with linearly-polarized femtosecond pulses creates a transient non-equilibrium lattice displacement along a certain direction. Here, the pump and probe pulse polarization dependence of the photo-induced ultrafast lattice dynamics in (GeTe)2/(Sb2Te3)4 interfacial phase change memory material is investigated under obliquely incident conditions. Drastic pump polarization dependence of the coherent phonon amplitude is observed when the probe polarization angle is para...
A successive continual description of dislocations and crowdions as intrinsic structure defects in 2D crystals is proposed. The both types of defects have been studied within the framework of a unified approach: the crystal is considered as a strictly two-dimensional elastic anisotropic medium and the defects as point carriers of plastic deformation and singular sources of elastic deformation fields, each being characterized by crystal geometric and topological properties. The continual description is preceded by the discussion of simple atomic lattice schemes illustrate the microscopic structure of the defects. Each type of the defects is related to the plastic distortion tensor which correlates with its crystal geometric characteristics. Based on the linear theory of elasticity of the 2D medium, equations are derived that determine the distribution of elastic fields round the centers of unit defects as well as for continuous distribution of defects in the crystal. The general solutions of these equations for fixed dislocations and crowdions in an infinitely extended elastic anisotropic 2D continuum are obtained.
庄飞; 吴良; 何赛灵
2002-01-01
The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystalformed by a hexagonal structure of anisotropic cylinders. Two cylindrical inclusions in the unit cell have two differentradii, R1 and R2 (Ri＜R2). By reducing the symmetry of the structure and choosing appropriately parameters R2and s = R1/R2 (s＜1), we obtain six large complete bandgaps, among which three are over 0.05 ωe (where ωe = 2πc/a)in the high region of the normalized frequency (however, one of these over 0.065 ωe is not stable). There are two otherstable complete bandgaps in the low-frequency region.
庄飞; 吴良; 等
2002-01-01
The plane-wave expansion method is used to calculate the band structure of a two-dimensional photonic crystal formed by a hexagonal structure of anisotropic cylinders.Two cylindrical inclusions in the unit cell have two different radii,R1 and R2(R1
Eriksen, Jørgen; Askegaard, Margrethe; Søegaard, Karen
2014-01-01
three-species swards of ryegrass–white clover with red clover (Trifolium pratense L.). Five different managements represented cutting, grazing and combinations thereof, with different slurry fertilization treatments in 1- to 4-year-old swards. The three-species mixture out-yielded the two......-species mixture in years 1 and 2. Across all 4 years, yields were 8–10% higher in cut swards. Inclusion of red clover increased the yields of clover across the 4 years by 51% without fertilizer and by 90% when fertilized. Responses to slurry fertilization were similar in both mixtures and were mainly independent...... of sward age. There was a complementary effect over the season and across managements. Red clover dominated in the first and third cuts; white clover dominated in the second and fourth cuts. Red clover dominated in cut swards and white clover in grazed swards. Future prospects of the inclusion of red...
Murshed, M. Mangir, E-mail: murshed@uni-bremen.de [Chemische Kristallographie fester Stoffe, Institut für Anorganische Chemie, Universität Bremen, Leobener Straße, D-28359 Bremen (Germany); Mendive, Cecilia B.; Curti, Mariano [Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Dean Funes 3350, B7600AYL, Mar del Plata (Argentina); Nénert, Gwilherm [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France); Kalita, Patricia E. [Department of Physics and Astronomy and High-Pressure Science and Engineering Center, University of Nevada Las Vegas, Box 4002, Las Vegas, NV 89154-4002 (United States); Lipinska, Kris [Department of Mechanical Engineering, University of Nevada Las Vegas, 4505 Maryland Parkway, Box 454009, Las Vegas, NV 89154-4009 (United States); Cornelius, Andrew L. [Department of Physics and Astronomy and High-Pressure Science and Engineering Center, University of Nevada Las Vegas, Box 4002, Las Vegas, NV 89154-4002 (United States); Huq, Ashfia [Chemical and Engineering Materials Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6475 (United States); Gesing, Thorsten M. [Chemische Kristallographie fester Stoffe, Institut für Anorganische Chemie, Universität Bremen, Leobener Straße, D-28359 Bremen (Germany)
2014-11-15
Highlights: • Mullite-type PbFeBO{sub 4} shows uni-axial negative coefficient of thermal expansion. • Anisotropic thermal expansion of the metric parameters was modeled using modified Grüneisen approximation. • The model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy. • DFT calculation, temperature- and pressure-dependent Raman spectra help understand the phonon decay and associated anharmonicity. - Abstract: The lattice thermal expansion of mullite-type PbFeBO{sub 4} is presented in this study. The thermal expansion coefficients of the metric parameters were obtained from composite data collected from temperature-dependent neutron and X-ray powder diffraction between 10 K and 700 K. The volume thermal expansion was modeled using extended Grüneisen first-order approximation to the zero-pressure equation of state. The additive frame of the model includes harmonic, quasi-harmonic and intrinsic anharmonic potentials to describe the change of the internal energy as a function of temperature. The unit-cell volume at zero-pressure and 0 K was optimized during the DFT simulations. Harmonic frequencies of the optical Raman modes at the Γ-point of the Brillouin zone at 0 K were also calculated by DFT, which help to assign and crosscheck the experimental frequencies. The low-temperature Raman spectra showed significant anomaly in the antiferromagnetic regions, leading to softening or hardening of some phonons. Selected modes were analyzed using a modified Klemens model. The shift of the frequencies and the broadening of the line-widths helped to understand the anharmonic vibrational behaviors of the PbO{sub 4}, FeO{sub 6} and BO{sub 3} polyhedra as a function of temperature.
Highlights: • Mullite-type PbFeBO4 shows uni-axial negative coefficient of thermal expansion. • Anisotropic thermal expansion of the metric parameters was modeled using modified Grüneisen approximation. • The model includes harmonic, quasi-harmonic and intrinsic anharmonic contributions to the internal energy. • DFT calculation, temperature- and pressure-dependent Raman spectra help understand the phonon decay and associated anharmonicity. - Abstract: The lattice thermal expansion of mullite-type PbFeBO4 is presented in this study. The thermal expansion coefficients of the metric parameters were obtained from composite data collected from temperature-dependent neutron and X-ray powder diffraction between 10 K and 700 K. The volume thermal expansion was modeled using extended Grüneisen first-order approximation to the zero-pressure equation of state. The additive frame of the model includes harmonic, quasi-harmonic and intrinsic anharmonic potentials to describe the change of the internal energy as a function of temperature. The unit-cell volume at zero-pressure and 0 K was optimized during the DFT simulations. Harmonic frequencies of the optical Raman modes at the Γ-point of the Brillouin zone at 0 K were also calculated by DFT, which help to assign and crosscheck the experimental frequencies. The low-temperature Raman spectra showed significant anomaly in the antiferromagnetic regions, leading to softening or hardening of some phonons. Selected modes were analyzed using a modified Klemens model. The shift of the frequencies and the broadening of the line-widths helped to understand the anharmonic vibrational behaviors of the PbO4, FeO6 and BO3 polyhedra as a function of temperature
Managing Ladino Clover in Vermont 1956
US Fish and Wildlife Service, Department of the Interior — The management practices discussed in this bulletin will help farmers to get top value from ladino clover. Information and conclusions are based on a state-wide...
Renormalisaton of composite operators in lattice QCD. Perturbative versus nonperturbative
The perturbative and nonperturbative renormalisation of quark-antiquark operators in lattice QCD with two flavours of clover fermions is investigated within the research programme of the QCDSF collaboration. Operators with up to three derivatives are considered. The nonperturbative results based on the RI-MOM scheme are compared with estimates from one- and two-loop lattice perturbation theory. (orig.)
Hansen, Nis Hauke; May, Falk; Kälblein, Daniel; Schmeiler, Teresa; Lennartz, Christian; Sanchez-Carrera, Roel; Steeger, Alexander; Burschka, Christian; Stolte, Matthias; Würthner, Frank; Brill, Jochen; Pflaum, Jens
2015-01-01
The anisotropic electron transport in the (001) plane of sublimation-grown Cl$_{2}$-NDI (naphthalene diimide) single crystals is analysed over a temperature range between 175 K and 300 K. Upon cooling from room temperature to 175 K the electron mobility along the direction of preferred transport monotonously increases from 1.5 cm$^{2}$/Vs to 2.8 cm$^{2}$/Vs according to a distinct temperature relation of $~T^{-1.3}$. At first glance, these characteristics allude to a coherent, i.e. band-like ...
Clover Action for Blue Gene-Q and Iterative solvers for DWF
Sivalingam, Karthee
2014-01-01
In Lattice QCD, a major challenge in simulating physical quarks is the computational complexity of these simulations. In this proceeding, we describe the optimisation of Clover fermion action for Blue gene-Q architecture and how different iterative solvers behave for Domain Wall Fermion action. We find that the optimised Clover term achieved a maximum efficiency of 29.1% and 20.2% for single and double precision respectively for iterative Conjugate Gradient solver. For Domain Wall Fermion action (DWF) we found that Modified Conjugate Residual(MCR) as the most efficient solver compared to CG and GCR. We have developed a new multi-shift MCR algorithm that is 18.5% faster compared to multi-shift CG for the evaluation of rational functions in RHMC.
Thermal architecture of the Clover cryostats
Grainger, William F.; Ade, Peter A. R.; Hargrave, Peter; Chase, Simon; Kiernan, Brian; North, Chris E.
2010-07-01
We discuss the Clover cryostats, which are dry cryostats containing three stages of cooling; a pulse tube cooler, a sorption fridge and a continuous miniature dilution refrigerator. We describe the thermal architecture of the system and present thermal data for the various stages including its performance when tilted.
We have studied the anisotropic three-dimensional nearest-neighbor Ising model with competitive interactions in an uniform longitudinal magnetic field H. The model consists of ferromagnetic interactions Jz=λ2Jx in the x(z) direction and antiferromagnetic interactions Jy=λ1Jx in the y direction (Ising superantiferromagnet). For the particular case λ1=λ2=1 we obtain the phase diagram in the H−T plane, using the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). It was observed first- and second-order transitions in the low and high temperature limits, respectively, with the presence of a tricritical point and a reentrant behavior is observed at low temperature. The critical curve in the classical approach is also obtained and the results are compared
Renormalisation and off-shell improvement in lattice perturbation theory
We discuss the improvement of flavour non-singlet point and one-link lattice quark operators, which describe the quark currents and the first moment of the DIS structure functions respectively. Suitable bases of improved operators are given, and the corresponding renormalisation factors and improvement coefficients are calculated in one-loop lattice perturbation theory, using the Sheikholeslami-Wohlert (clover) action. To this order we achieve off-shell improvement by eliminating the effect of contact terms. We use massive fermions, and our calculations are done keeping all terms up to first order in the lattice spacing, for arbitrary m2/p2, in a general covariant gauge. We also compare clover fermions with fermions satisfying the Ginsparg-Wilson relation, and show how to remove O(a) effects off-shell in this case too, and how this is in many aspects simpler than for clover fermions. Finally, tadpole improvement is also considered. (orig.)
Ricardo de Sousa, J. [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil); National Institute of Science and Technology for Complex Systems, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Neto, Minos A., E-mail: minos@pq.cnpq.br [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil); Padilha, Igor T.; Salmon, Octavio D.R.; Viana, J. Roberto [Universidade Federal do Amazonas, Departamento de Física, 3000, Japiim, 69077-000 Manaus, AM (Brazil)
2013-12-15
We have studied the anisotropic three-dimensional nearest-neighbor Ising model with competitive interactions in an uniform longitudinal magnetic field H. The model consists of ferromagnetic interactions J{sub z}=λ{sub 2}J{sub x} in the x(z) direction and antiferromagnetic interactions J{sub y}=λ{sub 1}J{sub x} in the y direction (Ising superantiferromagnet). For the particular case λ{sub 1}=λ{sub 2}=1 we obtain the phase diagram in the H−T plane, using the framework of the differential operator technique in the effective-field theory with finite cluster of N=4 spins (EFT-4). It was observed first- and second-order transitions in the low and high temperature limits, respectively, with the presence of a tricritical point and a reentrant behavior is observed at low temperature. The critical curve in the classical approach is also obtained and the results are compared.
Detmold, William; Meinel, Stefan
2016-04-01
Using (2 +1 )-flavor lattice QCD, we compute the 10 form factors describing the Λb→Λ matrix elements of the b →s vector, axial vector, and tensor currents. The calculation is based on gauge field ensembles generated by the RBC and UKQCD Collaborations with a domain-wall action for the u , d , and s quarks and the Iwasaki gauge action. The b quark is implemented using an anisotropic clover action, tuned nonperturbatively to the physical point, and the currents are renormalized with a mostly nonperturbative method. We perform simultaneous chiral, continuum, and kinematic extrapolations of the form factors through modified z expansions. Using our form factor results, we obtain precise predictions for the Λb→Λ (→p+π-)μ+μ- differential branching fraction and angular observables in the Standard Model.
Nuclear structure and Indian Clover array
H C Jain
2001-07-01
A brief description of the nuclear structure studies performed with the 14-UD pelletron at TIFR has been presented. The experimental facilities developed for these studies are described. Some of the interesting results obtained for mass 70 to 80 nuclei are presented. The development of a recoil mass spectrometer and an Indian clover array for the study of high spin states in nuclei near drip lines is discussed.
Geant4 simulation of a large volume segmented clover detector
The simulation for the energy spectra, efficiency and add back factor for the large volume segmented clover detector at VECC has been performed in the Geant4 platform. The details about the segmented clover detector and its comparison of measured efficiency with a INGA clover detector has been reported earlier. Geometry construction. The size of each crystal in this detector is 9 cm (length) x 6 cm (diameter), which is larger than a normal clover detector used in INGA array, having typical size of 7 cm (length) x 5 cm (diameter). The detector is housed inside an aluminium vacuum chamber
Using plaquette and Symanzik improved gauge action and stout link clover fermions we determine the improvement coefficient cSW in one-loop lattice perturbation theory from the off-shell quark-quark-gluon three-point function. In addition, we compute the coefficients needed for the most general form of quark field improvement and present the one-loop result for the critical hopping parameter κc. We discuss mean field improvement for cSW and κc and the choice of the mean field coupling for the actions we have considered. (orig.)
CHARACTERISTICS OF POLYPHENOL OXIDASES FROM RED CLOVER (TRIFOLIUM PRATENSE)
Polyphenol oxidase (PPO, EC 1.14.18.1 or EC 1.10.3.1) catalyzes the oxidation of o-diphenols to o-quinones which cause browning reactions in many wounded fruits, vegetables, and plants including the forage crop red clover (Trifolium pratense). Production of o-quinones in red clover inhibits post-har...
I = 1 and I = 2 π-π scattering phase shifts from Nf = 2 + 1 lattice QCD
Bulava, John; Fahy, Brendan; Hörz, Ben; Juge, Keisuke J.; Morningstar, Colin; Wong, Chik Him
2016-09-01
The I = 1 p-wave and I = 2 s-wave elastic π-π scattering amplitudes are calculated from a first-principles lattice QCD simulation using a single ensemble of gauge field configurations with Nf = 2 + 1 dynamical flavors of anisotropic clover-improved Wilson fermions. This ensemble has a large spatial volume V =(3.7 fm) 3, pion mass mπ = 230 MeV, and spatial lattice spacing as = 0.11 fm. Calculation of the necessary temporal correlation matrices is efficiently performed using the stochastic LapH method, while the large volume enables an improved energy resolution compared to previous work. For this single ensemble we obtain mρ /mπ = 3.350 (24), gρππ = 5.99 (26), and a clear signal for the I = 2 s-wave. The success of the stochastic LapH method in this proof-of-principle large-volume calculation paves the way for quantitative study of the lattice spacing effects and quark mass dependence of scattering amplitudes using state-of-the-art ensembles.
Christ, Norman H; Izubuchi, Taku; Kawanai, Taichi; Lehner, Christoph; Soni, Amarjit; Van de Water, Ruth S; Witzel, Oliver
2014-01-01
We calculate the B-meson decay constants f_B, f_Bs, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ~ 0.11, 0.086 fm with unitary pion masses as light as M_pi ~ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also impr...
Highly anisotropic elements for acoustic pentamode applications.
Layman, Christopher N; Naify, Christina J; Martin, Theodore P; Calvo, David C; Orris, Gregory J
2013-07-12
Pentamode metamaterials are a class of acoustic metafluids that are characterized by a divergence free modified stress tensor. Such materials have an unconventional anisotropic stiffness and isotropic mass density, which allow themselves to mimic other fluid domains. Here we present a pentamode design formed by an oblique honeycomb lattice and producing customizable anisotropic properties. It is shown that anisotropy in the stiffness can exceed 3 orders of magnitude, and that it can be realistically tailored for transformation acoustic applications. PMID:23889408
The guided wave (GW) field excited by a wedge-shaped, anisotropic piezocomposite transducer, surface-bonded on an isotropic substrate is investigated with applications to large area structural health monitoring. This investigation supports the development of the composite long-range variable-direction emitting radar (CLoVER) transducer. The analysis is based on the three-dimensional equations of elasticity, and the solution yields expressions for the field variables that are able to capture the multimodal nature of GWs. The assumption of uncoupled dynamics between the actuator and substrate is used, and their interaction is modeled through shear tractions along the transducer's radial edges. A similar problem is modeled using three-dimensional finite element simulations to assess the spatial and transient accuracy of the solution. Experimental tests are also conducted on pristine structures to validate the accuracy of the theoretical approach. The experimental studies employ CLoVER transducers developed in-house, and their manufacturing procedure is briefly described. Frequency response experiments based on piezoelectric sensors are conducted to assess the performance of the solution in the frequency domain. These tests are complemented by laser vibrometer measurements that allow the spatial and temporal evolution of the solution to be evaluated. The numerical simulations and experimental tests show that the wave time of arrival, radial attenuation, and azimuthal distribution are well captured by the theoretical solution
Moment of pion parton distribution function from lattice
We are studying the second moment of the pion quark distribution function in lattice QCD. Our simulations are based on dynamical Nf=2 in Wilson -Clover fermions with pion mass down to 160 MeV. We compare our preliminary data to previous results using the quenched approximation.
Tests of Electric Polarizability on the Lattice
Guerrero, V X; Christensen, J
2008-01-01
Using clover fermions on CP-PACS dynamical configurations, we consider a number of ways of measuring hadronic electric polarizability, an $|\\mathbf{E}|^{2}$ effect in hadron masses, using lattice techniques. We consider the effects of periodic and Dirichlet boundary conditions, the field linearization postulate as well as a quantized electric field. We also consider two ways of formulating the classical vector potential which describes a uniform electric field in combination with the other possibilities.
Production of N2O in grass-clover pastures
Thyme, Mette; Ambus, Per
2002-01-01
In organic as well as conventional dairy farming, grass-clover pastures is an important component of the cropping system. This is because grass-clover is an excellent cattle fodder, and because clover has the ability of fixing atmospheric N2. When budgets for N2O emissions are made accord-ing to the IPCC guidelines it is assumed that 1.25 % of added nitrogen is emitted as N2O. This emission factor is used for all nitrogen inputs although the factor relies on experiments with fertilizer and ma...
Production of N2O in grass-clover pastures
Carter, Mette S.
2005-01-01
Agricultural soils are known to be a considerable source of the strong greenhouse gas nitrous oxide (N2O), and in soil N2O is mainly produced by nitrifying and denitrifying bacteria. In Denmark, grass-clover pastures are an important component of the cropping system in organic as well as conventional dairy farming, and on a European scale grass-clover mixtures represent a large part of the grazed grasslands. Biological dinitrogen (N2) fixation in clover provides a major N input to these syste...
Isoflavones in several clover species and in milk from goats fed clovers.
Sakakibara, Hiroyuki; Viala, Didier; Ollier, Alain; Combeau, André; Besle, Jean-Michel
2004-01-01
Isoflavones that exist in forages such as clover can move in milk, and may have beneficial effects on human health. We measured the isoflavones in subterranean (cv Yarloop, Geraldton, Dinninup and Dwalganup) and red (cv Merviot and Hamua) clovers, grown in a mountain environment, and in the milk of two goats fed a fresh mixture of the four subterranean clovers gathered at flowering stage. Isoflavone glycosides were hydrolysed with an improved beta glycosidase method. Free aglycones (FA) and the hydrolysed glycosides + free aglycones fraction (HF) were analysed by HPLC. In milk, the methanol extracted compounds were deconjugated and similarly analysed. Total HF was highest in Yarloop (19 g kg(-1) dry matter) and was three times lower in Merviot. Formononetin was the major compound (46-64% of total HF). FA varied from 30 to 73% of HF. Milk contained formononetin (50 microg L(-1)), similar amounts of equol and p ethylphenol (about 250 microg L(-1)), and equol like compounds (1120 microg L(-1)). Equol, which has estrogenic activity, and p ethylphenol were produced by biotransformation of formononetin, and biochanin A or genistein, respectively. The modulation of isoflavone amounts in milk and the estimation of their interests for human health warrant further investigation. PMID:15630289
Wanda Truszkowska
2014-11-01
Full Text Available Knowledge of fungal communities within cultures of clover planted into barley and clover with cocksfoot grass may be used to evaluate the antiphytopathogenic potential of the environment. Observation of the lack of common pathogenic fungi and the sensitivity of Fusarium oxysporum populations to agroecological conditions indicates the possibility of influencing the healthiness of the clover by agrotechnical methods.
Importance of Clover (Trifolium sp.) Genus for Black Sea Region
Özlem Önal Aşcı
2016-01-01
There is a high level of forage deficit in Turkey. It is necessary that cultivation and productivity of forage plant should be increase to close forage deficit in a short time, further, pastures should also be improved. Clover genus involves both annual and perennial species, it has some species are grown different soil conditions. Clover species are grown in cool temperate and humid regions have thin stem and abundant leaf, thus, their hay is very nutritive feed for animals. They can use bot...
Evangelist Marketing of the CloverETL Software
Štýs, Miroslav
2011-01-01
The Evangelist Marketing of the CloverETL Software diploma thesis aims at proposing a new marketing strategy for an ETL tool - CloverETL. Theoretical part comprises chapters two and three. In chapter two, the thesis attempts to cover the ETL term, which - as a separate component of the Business Intelligence architecture - is not given much space in literature. Chapter three introduces evangelist marketing, explains its origins and best practices. Practical part involves introducing the Javlin...
Semileptonic Decays of Heavy Mesons with the Fat Clover Action
Bernard, C W; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; McNeile, C; Orginos, K; Sugar, R L; Toussaint, D
2000-01-01
We are studying a variety of semileptonic decays of heavy-light mesons in an effort to improve the determination of the heavy-quark Standard-Model CKM matrix elements. Our fermion action is a novel, improved ``fat'' clover action that promises to reduce problems with exceptional configurations. Dynamical sea quarks are included in a mixed approach, i.e. we use staggered sea quarks and fat-clover valence quarks. Here we report preliminary results.
Source of variation of isoflavone concentrations in perennial clover species
Bronislava Butkute; Butkute Lemeziene; Giedre Dabkeviciene; Valdas Jakstas; Egidijus Vilcinskas; Valdimaras Janulis
2014-01-01
Introduction: Clover has attracted considerable interest not only as a valuable livestock forage plant, but also as an important source of isoflavones. The current study was aimed to assess the variation of concentration of three isoflavones in clover species grown under a cool temperate climate environment in Lithuania. Materials and Methods: Isoflavone contents were quantified in the plant parts of 21 accessions belonging to five perennial species of genus Trifolium (T. pratense, T. repens,...
$I=1$ and $I=2$ $\\pi-\\pi$ scattering phase shifts from $N_{\\mathrm{f}} = 2+1$ lattice QCD
Bulava, John; Hörz, Ben; Juge, Keisuke J; Morningstar, Colin; Wong, Chik Him
2016-01-01
The $I=1$ $p$-wave and $I=2$ $s$-wave elastic $\\pi$-$\\pi$ scattering amplitudes are calculated from a first-principles lattice QCD simulation using a single ensemble of gauge field configurations with $N_{\\mathrm{f}} = 2+1$ dynamical flavors of anisotropic clover-improved Wilson fermions. This ensemble has a large spatial volume $V=(3.7\\mathrm{fm})^3$, pion mass $m_{\\pi} = 230\\mathrm{MeV}$, and spatial lattice spacing $a_s = 0.11\\mathrm{fm}$. Calculation of the necessary temporal correlation matrices is efficiently performed using the stochastic LapH method, while the large volume enables an improved energy resolution compared to previous work. For this single ensemble we obtain $m_{\\rho}/m_{\\pi} = 3.350(24)$, $g_{\\rho\\pi\\pi} = 5.99(26)$, and a clear signal for the $I=2$ $s$-wave. The success of the stochastic LapH method in this proof-of-principle large-volume calculation paves the way for quantitative study of the lattice spacing effects and quark mass dependence of scattering amplitudes using state-of-the-...
Perturbative and nonperturbative renormalization in lattice QCD
Goeckeler, M. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Horsley, R. [University of Edinburgh (United Kingdom). School of Physics and Astronomy; Perlt, H. [Leipzig Univ. (DE). Institut fuer Theoretische Physik] (and others)
2010-03-15
We investigate the perturbative and nonperturbative renormalization of composite operators in lattice QCD restricting ourselves to operators that are bilinear in the quark fields (quark-antiquark operators). These include operators which are relevant to the calculation of moments of hadronic structure functions. The nonperturbative computations are based on Monte Carlo simulations with two flavors of clover fermions and utilize the Rome-Southampton method also known as the RI-MOM scheme. We compare the results of this approach with various estimates from lattice perturbation theory, in particular with recent two-loop calculations. (orig.)
Kochhar, M.
1974-01-01
An effort was made to look at the effects of fescue and/or ozone on clover decline in the grass-clover mixture. The objectives of this study were to determine (1) if chemical interactions play a role in clover decline from a clover-fescue mixture, (2) if ozone affects the growth of clover, and (3) if ozone modifies plant-plant interactions between clover and fescue.
Pion structure from the lattice
In this thesis, we have discussed several aspects of the pion structure that are accessible with lattice QCD. In our introduction, we briefly mentioned QCD phenomenology for the pion that is obtained from experiments, namely the electromagnetic form factor connected to the charge radius, and the parton distribution functions (PDFs) which provide probabilities of finding a parton with a certain momentum fraction. These are embedded in the more general framework of generalised parton distributions (GPDs) which from the basis of this work. Special attention was paid to Mellin moments of GPDs that are parametrised in generalised form factors relevant for lattice calculations. The two subsequent Chapters were devoted to an introduction to lattice QCD and the lattice techniques we used. Here we started from the QCD Lagrangian and the path integral, to then explain our lattice gauge and fermion action, both going back to Wilson. For the latter we used the clover improved version for our dynamical two flavour simulations. We then gave details of the calculation of two- and three-point functions on the lattice, as well as the operators involved and how the matrix elements are extracted from the lattice data by building suitable ratios. The pion form factor was used for an exhaustive explanation of our methods to analyse the data. We investigated the momentum dependence of the form factor and its extrapolation to physical pion masses. We also payed attention to the lattice artifacts appearing in any lattice simulation. We also tried to estimate the size of finite volume corrections. We applied the established methods to the analysis of higher moments of the forward distributions and the second moment of the non-forward case. Finally, we gave an outlook on the densities of polarised quarks in the pion. (orig.)
Bond diluted anisotropic quantum Heisenberg model
Effects of the bond dilution on the critical temperatures, phase diagrams and the magnetization behaviors of the isotropic and anisotropic quantum Heisenberg model have been investigated in detail. For the isotropic case, bond percolation threshold values have been determined for several numbers of two (2D) and three (3D) dimensional lattices. In order to investigate the effect of the anisotropy in the exchange interaction on the results obtained for the isotropic model, a detailed investigation has been made on a honeycomb lattice. Some interesting results, such as second order reentrant phenomena in the phase diagrams have been found. - Highlights: • Anisotropic quantum Heisenberg model with bond dilution investigated. • Bond percolation threshold values given for 2D and 3D lattices in isotropic case. • Phase diagrams and ground state magnetizations investigated in detail. • Variation of the bond percolation threshold values with anisotropy determined
Kochhar, M.; Reinert, R.A.; Blum, U.
1982-08-01
Clover Trifolium repens and tall fescue Festuca arundinacea plants were exposed to ozone and inoculated with Rhizoctonia solani separately and in combination to investigate ozone/R. solani interactions on clover and tall fescue biomass, in the presence of clover and/or tall fescue debris or fescue leaf leachate. Ozone reduced biomass in clover. Rhizoctonia solani alone reduced clover biomass but the amount of this reduction was significantly greater in the presence of a single acute O/sub 3/ exposure. In the presence of multiple O/sub 3/ exposures the synergistic effect on clover biomass disappeared and the stress from R. solani was lost. The effects of O/sub 3/ and R. solani were not as pronounced on fescue as they were on clover. The debris treatments increased biomass of both clover and fescue, but the magnitude of change depended on the debris type. Leachate from fescue modified the effects of R. solani and O/sub 3/, but debris from clover and/or fescue did not. Clover plants treated with R. solani and O/sub 3/ had less biomass than control plants when stressed by leachate from fescue, but significantly greater biomass in the presence of leachate from O/sub 3/-treated fescue leaves.
Impact on Clover-Grass Yield from Wheel Load and Tyre Pressure
Green, Ole; Jørgensen, Rasmus Nyholm; Sørensen, Claus Aage Grøn
2009-01-01
Traffic intensities have been shown to have a negative influence on the yield of grass and clover. A full scale grass-clover field trial was established to estimate the effect on clover-grass yields as a function of different wheel loads and tire pressures. The trial comprised 16 different traffi...
White and red clover in highly productive short-lasting grassland mixtures
Søegaard, Karen; Nielsen, K A
2012-01-01
With the aim of increasing home-grown crude protein production, a plot experiment was carried out on two dairy farms with five different seed mixtures of red clover (Trifolium pratense) and/or white clover (Trifolium repens) together with grass. The clover constituted in total 20% of the seed...
Removal of Pyrene from Contaminated Soils by White Clover
XU Sheng-You; CHEN Ying-Xu; LIN Kuang-Fei; CHEN Xin-Cai; LIN Qi; LI Feng; WANG Zhao-Wei
2009-01-01
Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons (PAHs),ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes,in the last decade.In this study,a pot experiment was conducted to investigate the potential of phytoremediation of pyrcne from spiked soils planted with white clover (Trifolium repens) in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1.The results showed that growth of white clover on pyrenecontaminated soils was not affected.The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils.At the end of the experiment (60 d),the average removal ratio of pyrene in the spiked soils with white clover was 77%,which was 31% and 57% higher than those of the controls with or without micobes,respeetivcly.Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration.However,the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation.Bioconcentration factors of pyrene (BCFs,ratio of pyrene,on a dry weight basis,in the plant to that in the soil) tended to decrease with increase in the residual soil pyrene concentration.Therefore,removal of pyrene in the contaminated soils was feasible using white clove.
Resummation of Cactus Diagrams in Lattice QCD, to all Orders
Panagopoulos, H
2000-01-01
We show how to perform a resummation, to all orders in perturbation theory, of a certain class of gauge invariant tadpole-like diagrams in Lattice QCD. These diagrams are often largely responsible for lattice artifacts. Our resummation leads to an improved perturbative expansion. Applied to a number of cases of interest, e.g. the lattice renormalization of some two-fermion operators, this expansion yields results remarkably close to corresponding nonperturbative estimates. We consider in our study both the Wilson and the clover action for fermions.
Resummation of cactus diagrams in lattice QCD, to all orders
We show how to perform a resummation, to all orders in perturbation theory, of a certain class of gauge invariant tadpole-like diagrams in Lattice QCD. These diagrams are often largely responsible for lattice artifacts. Our resummation leads to an improved perturbative expansion. Applied to a number of cases of interest, e.g. the lattice renormalization of some two-fermion operators, this expansion yields results remarkably close to corresponding nonperturbative estimates. We consider in our study both the Wilson and the clover action for fermions
Effective medium theory for anisotropic metamaterials
Zhang, Xiujuan
2015-01-20
Materials with anisotropic material parameters can be utilized to fabricate many fascinating devices, such as hyperlenses, metasolids, and one-way waveguides. In this study, we analyze the effects of geometric anisotropy on a two-dimensional metamaterial composed of a rectangular array of elliptic cylinders and derive an effective medium theory for such a metamaterial. We find that it is possible to obtain a closed-form analytical solution for the anisotropic effective medium parameters, provided the aspect ratio of the lattice and the eccentricity of the elliptic cylinder satisfy certain conditions. The derived effective medium theory not only recovers the well-known Maxwell-Garnett results in the quasi-static regime, but is also valid beyond the long-wavelength limit, where the wavelength in the host medium is comparable to the size of the lattice so that previous anisotropic effective medium theories fail. Such an advance greatly broadens the applicable realm of the effective medium theory and introduces many possibilities in the design of structures with desired anisotropic material characteristics. A real sample of a recently theoretically proposed anisotropic medium, with a near-zero index to control the flux, is achieved using the derived effective medium theory, and control of the electromagnetic waves in the sample is clearly demonstrated.
Gasification of corn and clover grass in supercritical water
Pedro D' Jesus; Nikolaos Boukis; Bettina Kraushaar-Czarnetzki; Eckhard Dinjus [Chemisch-Physikalische Verfahren (ITC-CPV), Forschungszentrum Karlsruhe (Germany). Institut fuer Technische Chemie
2006-05-15
The influence of pressure, temperature, residence time, and alkali addition on the gasification of corn starch, clover grass and corn silage in supercritical water was investigated. Changing the pressure did not alter the gasification yield. An increase in the temperature notably improved the conversion of biomass. Residence time variations revealed that with longer residence time, gasification yield was improved until a maximum was reached. Gas composition changed with residence time and temperature. Potassium addition affected the gasification yield of corn starch, but did not influence the gasification yield of the potassium-containing natural products of clover grass and corn silage. 22 refs., 5 figs., 3 tabs.
P. Kolařík
2013-12-01
Full Text Available The clover seed weevils, Apion trifolii and Protapion apricans, members of the genus Apion, are responsible for causing serious economic damage in clover. In 2010-2012, the effectiveness of some insecticides against clover seed weevils in the genus Apion were tested in red clover stands. The efficacy of different products was evaluated on the basis of analyses of specimens trapped in the herb layer of red clover using a sweep net and red clover heads sampled in individual plots. Over the course of these trials, the applications of the products tested resulted in a marked reduction in their numbers (particularly of adults and, to a lesser extent, also of larvae. The highest efficacy was observed with Biscaya 240 (A.I. thiacloprid and Mospilan 20 SP (A.I. acetamiprid. Results obtained in this study corroborated the low efficacy of the insecticide Karate Zeon Technology 5 CS against seed weevils of the genus Apion.
Estimating the content of clover and grass in the sward using a consumer camera and image processing
Mortensen, Anders Krogh; Karstoft, Henrik; Søegaard, Karen;
the dry matter ratio of clover and grass in clover grass fields from sparse close up images. First, the light conditions is determined, which is used for selecting model parameters to estimate the coverage of both clover and grass. Next, the clover and grass coverage are transformed to give the dry...
INFLUENCE OF SOME TECHNOLOGY FACTORS ON FEEDING RED CLOVER HEIGHT
IULIA NIłU
2013-12-01
Full Text Available The plants height is one of the most important red clover features which give us, in a large measure, the explanation about the crop production. Thus, a biggest height could mean a high number of ramifications and leaves, as well as, high crop production and feeding good quality.
Neutron-antineutron oscillations on the lattice
Buchoff, Michael I; Wasem, Joseph
2012-01-01
One possible low energy process due to beyond the Standard Model (BSM) physics is the neutron-antineutron transition, where baryon number changes by two units. In addition to providing a source of baryon number violation in the early universe, interactions of this kind are natural in grand unified theories (GUTs) with Majorana neutrinos that violate lepton number. Bounds on these oscillations can greatly restrict a variety of GUTs, while a non-zero signal would be a "smoking gun" for new physics; however, to make a reliable prediction, the six-quark nucleon-antinucleon matrix elements must first be calculated non-perturbatively via lattice QCD. We review the current understanding of this quantity, describe the lattice formalism, and present preliminary results from $32^3\\times256$ clover-Wilson lattices with a pion mass of 390 MeV.
Wilson flow and scale setting from lattice QCD
We give a determination of the phenomenological value of the Wilson (or gradient) flow scales t0 and w0 for 2+1 flavours of dynamical quarks. The simulations are performed keeping the average quark mass constant, which allows the approach to the physical point to be made in a controlled manner. O(a) improved clover fermions are used and together with four lattice spacings this allows the continuum extrapolation to be taken.
Quasiparticle anisotropic hydrodynamics for central collisions
Alqahtani, Mubarak; Strickland, Michael
2016-01-01
We use quasiparticle anisotropic hydrodynamics to study an azimuthally-symmetric boost-invariant quark-gluon plasma including the effects of both shear and bulk viscosities. In quasiparticle anisotropic hydrodynamics, a single finite-temperature quasiparticle mass is introduced and fit to the lattice data in order to implement a realistic equation of state. We compare results obtained using the quasiparticle method with the standard method of imposing the equation of state in anisotropic hydrodynamics and viscous hydrodynamics. Using these three methods, we extract the primordial particle spectra, total number of charged particles, and average transverse momentum for various values of the shear viscosity to entropy density ratio eta/s. We find that the three methods agree well for small shear viscosity to entropy density ratio, eta/s, but differ at large eta/s. We find, in particular, that when using standard viscous hydrodynamics, the bulk-viscous correction can drive the primordial particle spectra negative...
Nucleon wave function from lattice QCD
Warkentin, Nikolaus
2008-04-15
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Nucleon wave function from lattice QCD
In this work we develop a systematic approach to calculate moments of leading-twist and next-to-leading twist baryon distribution amplitudes within lattice QCD. Using two flavours of dynamical clover fermions we determine low moments of nucleon distribution amplitudes as well as constants relevant for proton decay calculations in grand unified theories. The deviations of the leading-twist nucleon distribution amplitude from its asymptotic form, which we obtain, are less pronounced than sometimes claimed in the literature. The results are applied within the light cone sum rule approach to calculate nucleon form factors that are compared with recent experimental data. (orig.)
Bond diluted anisotropic quantum Heisenberg model
Akıncı, Ümit
2013-01-01
Effects of the bond dilution on the critical temperatures, phase diagrams and the magnetization behaviors of the isotropic and anisotropic quantum Heisenberg model have been investigated in detail. For the isotropic case, bond percolation threshold values have been determined for several numbers of two (2D) and three (3D) dimensional lattices. In order to investigate the effect of the anisotropy in the exchange interaction on the results obtained for the isotropic model, a detailed investigat...
Highly-anisotropic elements for acoustic pentamode applications
Christopher N. Layman; Christina J. Naify; Martin, Theodore P.; Calvo, David C.; Orris, Gregory J.
2012-01-01
Pentamode metamaterials are a class of acoustic metafluids that are characterized by a divergence free modified stress tensor. Such materials have an unconventional anisotropic stiffness and isotropic mass density, which allow themselves to mimic other fluid domains. Here we present a pentamode design formed by an oblique honeycomb lattice and producing customizable anisotropic properties. It is shown that anisotropy in the stiffness can exceed three orders of magnitude, and that it can be re...
Vegetative propagation of kura clover on mine spoils
Kura clover has an extensive root and rhizome system that makes it well adapted to grazing. However, kura clover is difficult to establish because of low seedling vigor and initial partitioning of photosynthate to rhizome production. A split plot design was used to evaluate kura clover establishment by vegetative propagation. Whole plots were mulched or not mulched with straw and subplots consisted of sprigs incorporated by disking, cult packing, disking plus cultipacking, or conventional seeding. A water converging-mycorrhizal coating treatment of sprigs incorporated by disking plus cultipacking was added in 1998. Stand counts were taken during establishment and plots were harvested for yield the year following establishment. Mulching increased plant density in the sprigged treatments in both years (P2 in Trial 1 and 42 and 18 plants/m2 in Trial 2. In the spring following the seeding year the conventionally seeded plots had a plant density of 69 plants/m2 compared to 5 plants in -2 for the sprigged treatments. The conventionally-seeded treatment always had higher plant densities (P<0.01). Separate analysis of the sprigged treatment always had higher plant densities (P<0.01). Separate analysis of the sprigged treatments indicated that treatments involving disking had greater stand densities (P<0.03) than those achieved by cultipacking alone. In Trial 1 only the mulched, conventionally-seeded treatment had satisfactory stands one year after seeding
Flynn, J M; Kawanai, T; Lehner, C; Soni, A; Van de Water, R S; Witzel, O
2015-01-01
We calculate the form factors for B->pi l nu & Bs->K l nu decay in lattice QCD. We use the (2+1)-flavor RBC-UKQCD gauge field-ensembles generated with the domain-wall fermion and Iwasaki gauge actions. For the b quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation. We analyze data at 2 lattice spacings a~0.11, 0.086 fm with pion masses as light as M_pi~290 MeV. We extrapolate our numerical results to the physical light-quark masses and to the continuum and interpolate in the pion/kaon energy using SU(2) "hard-pion" chiral perturbation theory. We provide complete systematic error budgets for the vector & scalar form factors f+(q^2) & f0(q2) for B->pi l nu & Bs ->K l nu at 3 momenta that span the q^2 range accessible in our numerical simulations. Next we extrapolate these results to q^2 = 0 using a model-independent z-parameterization based on analyticity & unitarity. We present our final results for f+(q^2) & f0(q^2) as the z coefficients and matr...
Fate in Soil of Flavonoids Released from White Clover (Trifolium repens L.)
Carlsen, Sandra C. K.; Pedersen, Hans A.; Spliid, Niels H.; Fomsgaard, Inge S.
2012-01-01
presence in soil of bioactive secondary metabolites from clover has received limited attention. In this paper we examine for the first time the release of flavonoids both from field-grown white clover and from soil-incorporated white clover plants of flavonoids, as analyzed by LC-MS/MS. The dominant...... flavonoid aglycones were formononetin, medicarpin, and kaempferol. Soil-incorporated white clover plants generated high concentrations of the glycosides kaempferol-Rha-Xyl-Gal and quercetin-Xyl-Gal. Substantial amounts of kaempferol persisted in the soil for days while the other compounds were degraded...
Grass-clover undersowing affects nitrogen dynamics in a grain legume–cereal arable cropping system
Hauggaard-Nielsen, Henrik; Mundus, Simon; Jensen, Erik Steen
2012-01-01
after grain legumes had a higher grass proportion before incorporation as compared to grass-clover after oat, which had the greatest clover proportion. The dynamic response of interspecific interactions in the catch crop to the soil mineral N levels is moderating the preceding effect of main crops in...... observed. A higher soil mineral N content in the soil profile without undersown grass-clover increased the spring wheat yield. This effect was circumvented in the subsequent winter triticale, where yields in the treatments with catch crops undersown were significantly greater. The grass-clover catch crop...
Production of N2O in grass-clover pastures
Agricultural soils are known to be a considerable source of the strong greenhouse gas nitrous oxide (N2O), and in soil N2O is mainly produced by nitrifying and denitrifying bacteria. In Denmark, grass-clover pastures are an important component of the cropping system in organic as well as conventional dairy farming, and on a European scale grass-clover mixtures represent a large part of the grazed grasslands. Biological dinitrogen (N2) fixation in clover provides a major N input to these systems, but knowledge is sparse regarding the amount of fixed N2 lost from the grasslands as N2O. Furthermore, urine patches deposited by grazing cattle are known to be hot-spots of N2O emission, but the mechanisms involved in the N2O production in urine-affected soil are very complex and not well understood. The aim of this Ph.D. project was to increase the knowledge of the biological and physical-chemical mechanisms, which control the production of N2O in grazed grass-clover pastures. Three experimental studies were conducted with the objectives of: 1: assessing the contribution of recently fixed N2 as a source of N2O. 2: examining the link between N2O emission and carbon mineralization in urine patches. 3: investigating the effect of urine on the rates and N2O loss ratios of nitrification and denitrification, and evaluating the impact of the chemical conditions that arise in urine affected soil. The results revealed that only 3.2 ± 0.5 ppm of the recently fixed N2 was emitted as N2O on a daily basis. Thus, recently fixed N released via easily degradable clover residues appears to be a minor source of N2O. Furthermore, increased N2O emission following urine application at rates up to 5.5 g N m-2 was not caused by enhanced denitrification stimulated by labile compounds released from scorched plant roots. Finally, the increase of soil pH and ammonium following urine application led to raised nitrification rate, which appeared to be the most important factor explaining the high
Improving the lattice axial vector current
Horsley, R; Perlt, H; Rakow, P E L; Schierholz, G; Schiller, A; Zanotti, J M
2015-01-01
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order $O(a)$ effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.
Fránová, Jana; Jakešová, H.
2014-01-01
Roč. 50, č. 3 (2014), s. 113-118. ISSN 1212-2580 R&D Projects: GA MZe QH71145 Institutional support: RVO:60077344 Keywords : Red clover mottle virus * White clover mosaic virus * DAS-ELISA Subject RIV: EE - Microbiology, Virology Impact factor: 0.597, year: 2014
Anisotropic Stars II Stability
Dev, K; Dev, Krsna; Gleiser, Marcelo
2003-01-01
We investigate the stability of self-gravitating spherically symmetric anisotropic spheres under radial perturbations. We consider both the Newtonian and the full general-relativistic perturbation treatment. In the general-relativistic case, we extend the variational formalism for spheres with isotropic pressure developed by Chandrasekhar. We find that, in general, when the tangential pressure is greater than the radial pressure, the stability of the anisotropic sphere is enhanced when compared to isotropic configurations. In particular, anisotropic spheres are found to be stable for smaller values of the adiabatic index $\\gamma$.
Quark-gluon plasma phenomenology from the lattice
The FASTSUM Collaboration has calculated several quantities relevant for QCD studies at non-zero temperature using the lattice technique. We report here our results for the (i) interquark potential in charmonium; (ii) bottomonium spectral functions; and (iii) electrical conductivity. All results were obtained with 2+1 flavours of dynamical fermions on an anisotropic lattice which allows greater resolution in the temporal direction
Cezary PURWIN
2011-07-01
Full Text Available The effects of the following factors were analyzed in the study: wilting degree, genetic form of red clover (2n – 4n, cultivars within the genetic form: 2n (Krynia, Parada, 4n (Jubilatka, Bona and DM x form, DM x 2n, DM x 4n. Fermentation and proteolysis during the ensilage of red clover were affected primarily by wilting, whereas genetic factors (genetic form, cultivar exerted a lesser effect. However, the genetic form of red clover affected the true protein content of silage and the extent of proteolysis during the ensiling process. The effect of the genetic form of red clover on the extent of proteolysis in silage (at similar levels of water-soluble carbohydrates and buffering capacity suggests that diploid and tetraploid red clover cultivars differ with respect to chemical properties (poliphenol oxidase activity, polyphenol content affecting proteolysis.
On the systematic position of Red Clover (Trifolium Pratense L.
Ioan PUIA
1977-08-01
Full Text Available During about two centuries, Trifolium pratense L. has been growing in Romania turning from a spontaneous plant to an intensely cultivated species. Parallelly with the intense cultivation, with breeding and variability studies, there have been formed and differentiated under cultivation - within the ecological conditions of Transylvania -, some valuable ecotypes, characteristic to specific climatic and geographic zones. The local populations taken under cultivation from the spontaneous flora, as well as from seed imported from abroad, have contributed, beginning with the end of the 19-th century, to the formation of these ecotypes generally and collectively known under the name of "Transylvanian Red Clover" (7.
Roxana - a new variety of diploid red clover
Mircea SAVATTI
1997-08-01
Full Text Available Roxana is a synthetic red clover variety, made up of fourteen families. It was obtained by the breeding team of Prof. dr. M. Savatti and released as a new variety in 1995. Roxana is 3-5 days earlier than Select 1, has a very good yielding capacity in the second year and a satisfactory one in the third year of vegetation. Raw protein yield is 8% higher than in Select 1 while seed yield exceed that of Select 1 with 15.3-35.3%. It is recommended mainly in Transylvania where it meets the most favourable ecological conditions.
The so-called doubling problem in the lattice description of fermions led to a proof that under certain circumstances chiral gauge theories cannot be defined on the lattice. This is called the no-go theorem. It implies that if Γ/sub/A is defined on a lattice then its infrared limit, which should correspond to the quantum description of the classical action for the slowly varying fields on lattice scale, is inevitably a vector like theory. In particular, if not circumvented, the no-go theorem implies that there is no lattice formulation of the Standard Weinberg-Salam theory or SU(5) GUT, even though the fermions belong to anomaly-free representations of the gauge group. This talk aims to explain one possible attempt at bypassing the no-go theorem. 20 refs
Uptake of Organic Phosphorus by Arbuscular Mycorrhizal Red Clover
无
2002-01-01
The capacities of two arbuscular mycorrhizal (AM) fungi, Glomus mosseae and Glomus versiforme, to mineralize added organic P were studied in a sterilized calcareous soil. Mycorrhizal (inoculated with either of the AM fungi) and non-mycorrhizal red clover (Trifolium pratense L.) plants were grown for eight weeks in pots with upper root, central hyphal and lower soil compartments. The hyphal and soil compartments received either organic P (as Na-phytate) or inorganic P (as KH2PO4) at the rate of 50 mg P kg-1. No P was added to the root compartments. Control pots received no added P. Yields were higher in mycorrhizal than in non-mycorrhizal clover. Mycorrhizal inoculation doubled shoot P concentration and more than doubled total P uptake of plants in P-amended soil, irrespective of the form of applied P. The mycorrhizal contribution to inorganic P uptake was 80% or 76% in plants inoculated with G. mosseae or G. versiforme, respectively.Corresponding values were 74% and 82% when Na-phytate was applied. In the root compartments of the mycorrhizal treatments, the proportion of root length infected, hyphal length density and phosphatase activity were all higher when organic P was applied than when inorganic P was added.
Andersen, C; Nielsen, T S; Purup, S; Kristensen, T; Eriksen, J; Søegaard, K; Sørensen, J; Fretté, X C
2009-01-01
A grazing experiment was carried out to study the concentration of phyto-oestrogens in herbage for cattle and in milk during two periods (May and June). Forty-eight Danish Holstein cows were divided into four groups with four treatment diets; white clover, red clover, lucerne and chicory...... clover and 238 to 466 mg/kg DM for the other three herbages mainly due to a much higher concentration of biochanin A, formononetin and glycitein in red clover. In the milk, the total concentration of phyto-oestrogens was 253 to 397 μg/l for red clover milk and 56 to 91 μg/l in the milk from the other...... three treatments. This was especially due to a higher concentration of equol, daidzein and formononetin in the red clover milk. The concentration of biochanin A was significantly higher in milk from the red clover treatment in May while no differences were observed in June. Enterodiol was similar across...
A definition of lattice BRS invariance is given. The requirement of lattice BRS invariance successfully replaces that of local gauge invariance as a principle for selecting allowed actions. This replacement also works to any finite order in perturbation theory, but, on the nonperturbative level one encounters an obstacle reflecting the existence of an even number of solutions to the gauge fixing problem. The problem of latticizing the classical action for open bosonic strings discovered by Witten is discussed and a possible direction for dealing with it is pointed out. 3 refs
Anisotropic dynamic mass density for fluidsolid composites
Wu, Ying
2012-10-01
By taking the low frequency limit of multiple-scattering theory, we obtain the dynamic effective mass density of fluidsolid composites with a two-dimensional rectangular lattice structure. The anisotropic mass density can be described by an angle-dependent dipole solution, to the leading-order of solid concentration. The angular dependence vanishes for the square lattice, but at high solid concentrations there is a structure-dependent factor that contributes to the leading-order solution. In all cases, Woods formula is found to be accurately valid for the effective bulk modulus, independent of the structures. Numerical evaluations from the solutions are shown to be in excellent agreement with finite-element simulations. © 2012 Elsevier B.V.
Turnover of microbial biomass in rhizosphere soils of clover and ryegrass
The turnover rate of microbial biomass nitrogen in the rhizosphere of clover (Trifolium prafensel) and ryegrass (Lolium perence) was investigated with 15N isotopic technique. The results showed that the activity of soil protease was higher in rhizosphere during the growth period of clover and ryegrass. It also indicated that the activity of soil protease of clover was higher than that of ryegrass. Turnover rate of biomass 15N was in the following order: root zone > 0-2 mm > 15-25 mm > 25-40 mm. It is suggested that the principal function of microbe in rhizosphere is to accelerate the nutrient cycling compared to non-rhizosphere soil
Averaging anisotropic cosmologies
We examine the effects of spatial inhomogeneities on irrotational anisotropic cosmologies by looking at the average properties of anisotropic pressure-free models. Adopting the Buchert scheme, we recast the averaged scalar equations in Bianchi-type form and close the standard system by introducing a propagation formula for the average shear magnitude. We then investigate the evolution of anisotropic average vacuum models and those filled with pressureless matter. In the latter case we show that the backreaction effects can modify the familiar Kasner-like singularity and potentially remove Mixmaster-type oscillations. The presence of nonzero average shear in our equations also allows us to examine the constraints that a phase of backreaction-driven accelerated expansion might put on the anisotropy of the averaged domain. We close by assessing the status of these and other attempts to define and calculate 'average' spacetime behaviour in general relativity
Anisotropic Metamaterial Optical Fibers
Pratap, Dheeraj; Pollock, Justin G; Iyer, Ashwin K
2014-01-01
Internal physical structure can drastically modify the properties of waveguides: photonic crystal fibers are able to confine light inside a hollow air core by Bragg scattering from a periodic array of holes, while metamaterial loaded waveguides for microwaves can support propagation at frequencies well below cutoff. Anisotropic metamaterials assembled into cylindrically symmetric geometries constitute light-guiding structures that support new kinds of exotic modes. A microtube of anodized nanoporous alumina, with nanopores radially emanating from the inner wall to the outer surface, is a manifestation of such an anisotropic metamaterial optical fiber. The nanopores, when filled with a plasmonic metal such as silver or gold, greatly increase the electromagnetic anisotropy. The modal solutions in anisotropic circular waveguides can be uncommon Bessel functions with imaginary orders.
Phelan, P; Casey, I A; Humphreys, J
2013-03-01
White clover (Trifolium repens) is an important legume for grazed grassland that can increase the profitability and environmental sustainability of milk production. Previous experiments on mown grass-clover plots suggest that low postgrazing heights (PGH) can increase sward clover content and herbage production. However, this has not been tested in actual strip or rotational grazing systems with dairy cows. Furthermore, lowering PGH in grass-only swards (typically perennial ryegrass without white clover) has previously been associated with reduced milk yields per cow. The objective of this experiment was to investigate the effect of PGH by dairy cows on clover content, herbage production, and milk production from strip-grazed grass-white clover swards in Ireland. Three target PGH treatments of 4, 5, and 6 cm were in place for entire grazing seasons (February to November) for 3 consecutive years (2007 to 2009). Each treatment had a mean of 21 Holstein-Friesian dairy cows that strip-grazed a mean annual area of 10.2 ha. Postgrazing height was measured twice a day with a rising plate meter, and cows were moved to the next strip once the target PGH was reached. Annual fertilizer nitrogen input was 90 kg of N/ha for each treatment. The PGH treatment did not significantly affect annual milk yield (6,202 kg/cow), solids-corrected milk yield (6,148 kg/cow), fat, protein, or lactose yields (265, 222, and 289 kg/cow, respectively), cow liveweight (592 kg) or body condition score (3.01). The PGH treatment also had no significant effect on sward white clover content (196 g/kg). However, herbage production of both grass and clover were significantly higher with the 4-cm PGH treatment compared with the 6-cm treatment. Mean annual herbage yields were 11.1, 10.2, and 9.1 t of organic matter (OM)/ha for the 4-, 5-, and 6-cm PGH treatments, respectively. The lower herbage production in the 6-cm PGH treatment resulted in lower annual silage production, greater housing requirements
Hwu, Chyanbin
2010-01-01
As structural elements, anisotropic elastic plates find wide applications in modern technology. The plates here are considered to be subjected to not only in plane load but also transverse load. In other words, both plane and plate bending problems as well as the stretching-bending coupling problems are all explained in this book. In addition to the introduction of the theory of anisotropic elasticity, several important subjects have are discussed in this book such as interfaces, cracks, holes, inclusions, contact problems, piezoelectric materials, thermoelastic problems and boundary element a
Pérez-Nadal, Guillem
2016-01-01
We consider a non-relativistic free scalar field theory with a type of anisotropic scale invariance in which the number of coordinates "scaling like time" is generically greater than one. We propose the Cartesian product of two curved spaces, with the metric of each space parameterized by the other space, as a notion of curved background to which the theory can be extended. We study this type of geometries, and find a family of extensions of the theory to curved backgrounds in which the anisotropic scale invariance is promoted to a local, Weyl-type symmetry.
Quark helicity flip generalized parton distributions from two-flavor lattice QCD
We present an initiatory study of quark helicity flip generalized parton distributions (GPDs) in nf=2 lattice QCD, based on clover-improved Wilson fermions for a large number of coupling constants and pion masses. Quark helicity flip GPDs yield essential information on the transverse spin structure of the nucleon. In this work, we show first results on their lowest moments and dipole masses and study the corresponding chiral and continuum extrapolations
Quark helicity flip generalized parton distributions from two-flavor lattice QCD
We present an initiatory study of quark helicity flip generalized parton distributions (GPDs) in nf = 2 lattice QCD, based on clover-improved Wilson fermions for a large number of coupling constants and pion masses. Quark helicity flip GPDs yield essential information on the transverse spin structure of the nucleon. In this work, we show first results on their lowest moments and dipole masses and study the corresponding chiral and continuum extrapolations. (orig.)
Reactions of clover plants to soil contamination with zinc salts
H. M. Denchilja-Sakal
2012-07-01
Full Text Available It is studied the influence of zinc ions on growth, weight, and pigment system state of leaves of Trifolium pratense L. It is revealed that the root development of seedlings is suppressed more than above-ground parts. It is shown that under tenfold excess of MAC the leaves area decreased by 65–70 %in comparison with the control. It is ascertained the regularities of accumulation and distribution of zinc in the clover organs. It was found that with increasing concentration of the element in soil, its concentration in the plant grows to a certain extent, but under low concentrations it increases linearly. Thus, under the concentrations of zinc in soil (1, 5 and 10 MAC its content in the roots increases 2–3 times and in the above-ground parts – by 1.5–2 times.
Report on the intercomparison run IAEA-156 radionuclides in clover
This report contains the results of the intercomparison IAEA-156 on the determination of radionuclides in clover. Initially participants were requested to determine the levels of 134Cs, 137Cs, 40K, 90Sr and invited to provide data for other radionuclides. The participants included 46 laboratories located in 25 countries, and statistical evaluation of their data yield recommended values for these four radionuclides. Additional radionuclides reported were 210Pb, 239Pu and 125Sb; however, insufficient data exists to statistically determine recommended values for these radionuclides. The following are the recommended values, with confidence intervals, for the most frequently measured radionuclides (reference date: 1 August 1986): 134Cs 132.1 Bq/kg (126.4-137.7); 137Cs 264 Bq/kg (254-274); 40K 657 Bq/kg (637-676); 90Sr 14.8 Bq/kg (13.4-16.3). Figs and tabs
Characteristics of GRIFFIN high-purity germanium clover detectors
Rizwan, U.; Garnsworthy, A. B.; Andreoiu, C.; Ball, G. C.; Chester, A.; Domingo, T.; Dunlop, R.; Hackman, G.; Rand, E. T.; Smith, J. K.; Starosta, K.; Svensson, C. E.; Voss, P.; Williams, J.
2016-06-01
The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei, GRIFFIN, is a new experimental facility for radioactive decay studies at the TRIUMF-ISAC laboratory. The performance of the 16 high-purity germanium (HPGe) clover detectors that will make up the GRIFFIN spectrometer is reported. The energy resolution, efficiency, timing resolution, crosstalk and preamplifier properties of each crystal were measured using a combination of analog and digital data acquisition techniques. The absolute efficiency and add-back factors are determined for the energy range of 80-3450 keV. The detectors show excellent performance with an average over all 64 crystals of a FWHM energy resolution of 1.89(6) keV and relative efficiency with respect to a 3 in . × 3 in . NaI detector of 41(1)% at 1.3 MeV.
Reduction in clover-grass yield caused by different traffic intensities
Green, Ole; Jørgensen, Rasmus Nyholm; Kristensen, Kristian;
yield in fresh grass was analysed in a linear model that had as explanatory variables the traffic intensities, a block effect describing the history of the field, the harvest date, the trial coordinates, the average altitude, the average of the EM38-meausremnt and the distance to trees and hedges......Different traffic intensities have been shown to have a negative influence on the yield of grass and clover. A full scale grass-clover field trial was established to estimate the effect on clover-grass yields as a function of different wheel loads and tire pressures. The trial comprised 16...... different traffic intensities with 35 replicates and 1 traffic free treatment with 245 replicates, totalling 17 treatments randomized in a framework of 840 net parcels. The aim of this paper is to present the initial results concerning the impact on clover-grass yield caused by traffic intensities. The...
Concentrations of rare elements in soil and clover, taken from a refuse reclaimed site (Y-area) and a control area (T-area), were determined by radioactivation analysis. Concentrations of many rare elements (fourteen out of twenty six elements) in Y-area soil were larger than those in the control area. However, the magnitude of each element was not judged to be large enough to show the environmental contamination related to human activities. Concentrations of rare earth elements in clover were very low. Therefore these elements are assumed to be stable in insoluble form in soil and be hardly taken up by the root of clover. Homologues of essential elements showed higher concentrations in clover. This suggests that the homologues, which are clearly related to human activities, may become promising indications for monitoring environmental pollution. (author)
Christ, Norman H. [Columbia Univ., New York, NY (United States); Flynn, Jonathan M. [Univ. of Southampton, Southampton (United Kingdom); Izubuchi, Taku [Brookhaven National Lab. (BNL), Upton, NY (United States); Kawanai, Taichi [RIKEN, Wako (Japan); Brookhaven National Lab. (BNL), Upton, NY (United States); Lehner, Christoph [Brookhaven National Lab. (BNL), Upton, NY (United States); Soni, Amarjit [Brookhaven National Lab. (BNL), Upton, NY (United States); Van de Water, Ruth S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Witzel, Oliver [Boston Univ., Boston, MA (United States)
2015-03-10
We calculate the B-meson decay constants f_{B}, f_{B}s, and their ratio in unquenched lattice QCD using domain-wall light quarks and relativistic b-quarks. We use gauge-field ensembles generated by the RBC and UKQCD collaborations using the domain-wall fermion action and Iwasaki gauge action with three flavors of light dynamical quarks. We analyze data at two lattice spacings of a ≈ 0.11, 0.086 fm with unitary pion masses as light as M_{π} ≈ 290 MeV; this enables us to control the extrapolation to the physical light-quark masses and continuum. For the b-quarks we use the anisotropic clover action with the relativistic heavy-quark interpretation, such that discretization errors from the heavy-quark action are of the same size as from the light-quark sector. We renormalize the lattice heavy-light axial-vector current using a mostly nonperturbative method in which we compute the bulk of the matching factor nonperturbatively, with a small correction, that is close to unity, in lattice perturbation theory. We also improve the lattice heavy-light current through O(α_{s}a). We extrapolate our results to the physical light-quark masses and continuum using SU(2) heavy-meson chiral perturbation theory, and provide a complete systematic error budget. We obtain f_{B0} = 196.2(15.7) MeV, f_{B+} = 195.4(15.8) MeV, f_{Bs} = 235.4(12.2) MeV, f_{Bs}/f_{B0} = 1.193(59), and f_{Bs}/f_{B+} = 1.220(82), where the errors are statistical and total systematic added in quadrature. In addition, these results are in good agreement with other published results and provide an important independent cross check of other three-flavor determinations of B-meson decay constants using staggered light quarks.
On the Newtonian anisotropic configurations
Shojai, F. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Institute for Research in Fundamental Sciences (IPM), Foundations of Physics Group, School of Physics, Tehran (Iran, Islamic Republic of); Fazel, M.R.; Stepanian, A. [University of Tehran, Department of Physics, Tehran (Iran, Islamic Republic of); Kohandel, M. [Alzahra University, Department of Sciences, Tehran (Iran, Islamic Republic of)
2015-06-15
In this paper we are concerned with the effects of an anisotropic pressure on the boundary conditions of the anisotropic Lane-Emden equation and the homology theorem. Some new exact solutions of this equation are derived. Then some of the theorems governing the Newtonian perfect fluid star are extended, taking the anisotropic pressure into account. (orig.)
B B Bhowmik; A Rajput
2004-06-01
Anisotropic Bianchi Type-I cosmological models have been studied on the basis of Lyra's geometry. Two types of models, one with constant deceleration parameter and the other with variable deceleration parameter have been derived by considering a time-dependent displacement field.
Anisotropic Ambient Volume Shading.
Ament, Marco; Dachsbacher, Carsten
2016-01-01
We present a novel method to compute anisotropic shading for direct volume rendering to improve the perception of the orientation and shape of surface-like structures. We determine the scale-aware anisotropy of a shading point by analyzing its ambient region. We sample adjacent points with similar scalar values to perform a principal component analysis by computing the eigenvectors and eigenvalues of the covariance matrix. In particular, we estimate the tangent directions, which serve as the tangent frame for anisotropic bidirectional reflectance distribution functions. Moreover, we exploit the ratio of the eigenvalues to measure the magnitude of the anisotropy at each shading point. Altogether, this allows us to model a data-driven, smooth transition from isotropic to strongly anisotropic volume shading. In this way, the shape of volumetric features can be enhanced significantly by aligning specular highlights along the principal direction of anisotropy. Our algorithm is independent of the transfer function, which allows us to compute all shading parameters once and store them with the data set. We integrated our method in a GPU-based volume renderer, which offers interactive control of the transfer function, light source positions, and viewpoint. Our results demonstrate the benefit of anisotropic shading for visualization to achieve data-driven local illumination for improved perception compared to isotropic shading. PMID:26529745
Dynamics of Anisotropic Universes
Pérez, J
2006-01-01
We present a general study of the dynamical properties of Anisotropic Bianchi Universes in the context of Einstein General Relativity. Integrability results using Kovalevskaya exponents are reported and connected to general knowledge about Bianchi dynamics. Finally, dynamics toward singularity in Bianchi type VIII and IX universes are showed to be equivalent in some precise sence.
Non-perturbative phenomena are essential to understanding quantum chromodynamics (QCD), the theory of the strong interactions. The particles observed are mesons and baryons, but the fundamental fields are quarks and gluons. Most properties of the hadrons are inaccessible in perturbation theory. Aside from their mere existence, the most blatant example is the mass spectrum. The lack of an accurate, reasonably precise, calculation of the mass spectrum is a major piece of unfinished business for theoretical particle physics. In addition, a wide variety of other non-perturbative calculations in QCD are necessary to interpret ongoing experiments. For example, it is impossible to extract the Cabibbo-Kobayashi-Maskawa angles without knowing matrix elements of operators in the K, D and B mesons. Furthermore, non-perturbative analyses of quarkonia can determine the strong coupling constant with uncertainties already comparable to perturbative analyses of high-energy data. These lectures cover lattice field theory, the only general, systematic approach that can address quantitatively the non-perturbative questions raised above. Sects. 2--8 explain how to formulate quantum field theory on a lattice and why lattice field theory is theoretically well-founded. Sect. 9 sketches some analytic calculations in scalar lattice field theory. They serve as an example of how lattice field theory can contribute to particle physics without necessarily using computers. Sect. 10 turns to the most powerful tool in lattice field theory: large-scale Monte Carlo integration of the functional integral. Instead of discussing algorithms in gory detail, the general themes of computational field theory are discussed. The methods needed for spectroscopy, weak matrix elements, and the strong coupling constant are reviewed. 52 refs., 7 figs., 1 tab
Measured and Simulated Performance of a Four-Segmented Clover Detector
Gamma rays with energies between 80 keV and 1500 keV produced by 133Ba and 152Eu standard sources are measured with the clover detector. Relative efficiencies and add-back factors are determined in both crystals and full clover modes. The add-back characteristics have been calculated using Monte-Carlo simulation code Geant4. The simulation and measurements agree very well. (nuclear physics)
A method of isoflavones isolation from red clover as standards for analyses
Piotr M. Górski; Stanisław Burda; Marian Jurzysta; Michał Płoszyński
2013-01-01
Five compounds having an isoflavone structure were isolated from the tops of red clover (Trifolium pratense). On the basis of spectral (UV, MS) and chromatographic (TLC, HPLC) analyses the compounds were identified as biochanin A, formononetin, pratensein, genistein and daidzein. Biochanin A and formononetin - two main clover estrogens - were obtained in crystalline forms in the amounts of 50 mg and 15 mg, respectively (per 250 g of D. W.). Homogenous fractions of pratensein, genistein, and d...
Wenhua Du; Xinhui Tian; Yan Yue; Juan Lu
2013-01-01
Red clover (Trifoliumpratense L.) as a dietary supplement is currently used to treat menopausal symptoms because of its high concentrations of mildly estrogenic isoflavone. The application rate of N and P fertilizer has a huge influence on the isoflavone content (IC) in red clover. Trifolium pratense 'Minshan' is a unique plant resource in the alpine pasture region of northwest China. It plays a very important role in livestock production and the pharmaceutical industry because of its high nu...
Herrmann, Dorris; Boller, Beat; Studer, Bruno; Widmer, Franco; Kölliker, Roland
2008-01-01
Cultivars of red clover (Trifolium pratense L.) often suffer from low persistence, leading to insufficient legume proportions in pluriannual forage stands. Persistence is a complex trait often negatively correlated with other important traits and its phenotyping is laborious. Consequently....... Moreover, length of stem may present a candidate character for indirect selection of these two traits. The QTLs and the indirect selection criteria identified in this study may substantially assist future breeding efforts for the improvement of persistence in red clover...
Polyphenol oxidase affects normal nodule development in red clover (Trifolium pratense L.)
Webb, K Judith; Cookson, Alan; Allison, Gordon; Sullivan, Michael L.; Winters, Ana L.
2014-01-01
Polyphenol oxidase (PPO) may have multiple functions in tissues depending on its cellular or tissue localization. Here we use PPO RNAi transformants of red clover (Trifolium pratense) to determine the role PPO plays in normal development of plants, and especially in N2-fixing nodules. In red clover, PPO was not essential for either growth or nodule production, or for nodule function in plants grown under optimal, N-free conditions. However, absence of PPO resulted in a more reduced environmen...
In field N transfer, build-up, and leaching in ryegrass-clover mixtures
Rasmussen, J.; Eriksen, J.; Jensen, E.S.; Høgh-Jensen, H.
2008-01-01
Two field experiments investigating dynamics in grass-clover mixtures were conducted, using 15N- and 14C-labelling to trace carbon (C) and nitrogen (N) from grass (Lolium perenne L.) and clover (Trifolium repens L. and Trifolium pratense L.). The leaching of dissolved inorganic nitrogen (DIN), as measured in pore water sampled by suction cups, increased during the autumn and winter, whereas the leaching of dissolved organic nitrogen (DON) was fairly constant during this period. Leaching of 15...
The finite-element method enables us to convert the operator differential equations of a quantum field theory into operator difference equations. These difference equations are consistent with the requirements of quantum mechanics and they do not exhibit fermion doubling, a problem that frequently plagues lattice treatments of fermions. Guage invariance can also be incorporated into the difference equations. On a finite lattice the operator difference equations can be solved in closed form. For the case of the Schwinger model the anomaly is computed and results in excellent agreement are obtained with the known continuum value
Scaling Lattice QCD beyond 100 GPUs
Babich, R; Joó, B; Shi, G; Brower, R C; Gottlieb, S
2011-01-01
Over the past five years, graphics processing units (GPUs) have had a transformational effect on numerical lattice quantum chromodynamics (LQCD) calculations in nuclear and particle physics. While GPUs have been applied with great success to the post-Monte Carlo "analysis" phase which accounts for a substantial fraction of the workload in a typical LQCD calculation, the initial Monte Carlo "gauge field generation" phase requires capability-level supercomputing, corresponding to O(100) GPUs or more. Such strong scaling has not been previously achieved. In this contribution, we demonstrate that using a multi-dimensional parallelization strategy and a domain-decomposed preconditioner allows us to scale into this regime. We present results for two popular discretizations of the Dirac operator, Wilson-clover and improved staggered, employing up to 256 GPUs on the Edge cluster at Lawrence Livermore National Laboratory.
Qcd Thermodynamics On A Lattice
Levkova, L A
2004-01-01
Numerical simulations of full QCD on anisotropic lattices provide a convenient way to study QCD thermodynamics with fixed physics scales and reduced lattice spacing errors. We report results from calculations with two flavors of dynamical staggered fermions, where all bare parameters and the renormalized anisotropy are kept constant and the temperature is changed in small steps by varying only the number of time slices. Including results from zero- temperature scale setting simulations, which determine the Karsch coefficients, allows for the calculation of the Equation of State at finite temperatures. We also report on studies of the chiral properties of dynamical domain-wall fermions combined with the DBW2 gauge action for different gauge couplings and fermion masses. For quenched theories, the DBW2 action gives a residual chiral symmetry breaking much smaller than what was found with more traditional choices for the gauge action. Our goal is to investigate the possibilities which this and further improvemen...
Kidane, Alemayehu; Sørheim, Kristin; Eik, Lars Olav; Steinshamn, Håvard
2014-01-01
We report results from trials on chicory growth (experiment 1) and lamb growth on chicory (experiment 2). In experiment 1, we assessed yield and chemical composition on swards established under organic conditions as perennial ryegrass/red clover, perennial ryegrass/chicory, chicory/red clover (CHRC), pure perennial ryegrass (RG-alone) and pure chicory (CHalone) over two years. Chicory/red clover and CH-alone showed improved crude protein, Ca, Mg, P, Cu and net energy contents comp...
Nielsen, Bea; Thamsborg, Stig Milan; Hansen, Hanne; Ranvig, Hans; Høgh-Jensen, Henning
2009-01-01
Two trials were conducted to examine the effect of chicory included in or as additional plots of the ryegrass–white clover pastures on growth, naturally acquired nematode infections and selectivity of chicory by lambs. In Experiment 1, 31 weaned Texel lambs (36±7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover–hicory pastures (CHIC). In Experiment 2, 30 weaned Shropshire lambs (32±7 kg) grazed either ryegrass–white clover (CTRL) or ryegrass–white clover with access to...
Fractures in anisotropic media
Shao, Siyi
Rocks may be composed of layers and contain fracture sets that cause the hydraulic, mechanical and seismic properties of a rock to be anisotropic. Coexisting fractures and layers in rock give rise to competing mechanisms of anisotropy. For example: (1) at low fracture stiffness, apparent shear-wave anisotropy induced by matrix layering can be masked or enhanced by the presence of a fracture, depending on the fracture orientation with respect to layering, and (2) compressional-wave guided modes generated by parallel fractures can also mask the presence of matrix layerings for particular fracture orientations and fracture specific stiffness. This report focuses on two anisotropic sources that are widely encountered in rock engineering: fractures (mechanical discontinuity) and matrix layering (impedance discontinuity), by investigating: (1) matrix property characterization, i.e., to determine elastic constants in anisotropic solids, (2) interface wave behavior in single-fractured anisotropic media, (3) compressional wave guided modes in parallel-fractured anisotropic media (single fracture orientation) and (4) the elastic response of orthogonal fracture networks. Elastic constants of a medium are required to understand and quantify wave propagation in anisotropic media but are affected by fractures and matrix properties. Experimental observations and analytical analysis demonstrate that behaviors of both fracture interface waves and compressional-wave guided modes for fractures in anisotropic media, are affected by fracture specific stiffness (controlled by external stresses), signal frequency and relative orientation between layerings in the matrix and fractures. A fractured layered medium exhibits: (1) fracture-dominated anisotropy when the fractures are weakly coupled; (2) isotropic behavior when fractures delay waves that are usually fast in a layered medium; and (3) matrix-dominated anisotropy when the fractures are closed and no longer delay the signal. The
Anisotropic progressive photon mapping
Liu, XiaoDan; Zheng, ChangWen
2014-01-01
Progressive photon mapping solves the memory limitation problem of traditional photon mapping. It gives the correct radiance with a large passes, but it converges slowly. We propose an anisotropic progressive photon mapping method to generate high quality images with a few passes. During the rendering process, different from standard progressive photon mapping, we store the photons on the surfaces. At the end of each pass, an anisotropic method is employed to compute the radiance of each eye ray based on the stored photons. Before move to a new pass, the photons in the scene are cleared. The experiments show that our method generates better results than the standard progressive photon mapping in both numerical and visual qualities.
A first look at maximally twisted mass lattice QCD calculations at the physical point
Abdel-Rehim, A. [The Cyprus Institute, Nicosia (Cyprus). CaSToRC; Boucaud, P. [Paris XI Univ., Orsay (France). Laboratoire de Physique Theorique; Carrasco, N. [Valencia-CSIC Univ. (Spain). Dept. de Fisica Teorica; IFIC, Valencia (Spain); and others
2013-11-15
In this contribution, a first look at simulations using maximally twisted mass Wilson fermions at the physical point is presented. A lattice action including clover and twisted mass terms is presented and the Monte Carlo histories of one run with two mass-degenerate flavours at a single lattice spacing are shown. Measurements from the light and heavy-light pseudoscalar sectors are compared to previous N{sub f}=2 results and their phenomenological values. Finally, the strategy for extending simulations to N{sub f}=2+1+1 is outlined.
The decay constants f(B) and f(D+) from three-flavor lattice QCD
Bernard, C.; /Washington U., St. Louis; DeTar, C.; /Utah U.; Di Pierro, M.; /NONE - DEPAUL U CHICAGO; El-Khadra, A.X.; Evans, R.T.; /Illinois U., Urbana; Freeland, E.; /Illinois U., Chicago /Fermilab; Gamiz, E.; /Illinois U., Urbana; Gottlieb, Steven; /Indiana U.; Heller, U.M.; /APS, New York; Hetrick, J.E.; /U. Pacific, Stockton; Jain, R.; /Illinois U., Urbana /Fermilab /Fermilab /Washington U., St. Louis
2007-01-01
We present new preliminary results for the leptonic decay constants f{sub B} and f{sub D+} determined in 2+1 flavor lattice QCD at lattice spacings a = 0.09, 0.12 and 0.15 fm. Results are obtained using the MILC Collaboration gauge configuration ensembles, clover heavy quarks in the Fermilab interpretation and improved staggered light quarks. Decay constants, computed at partially quenched combinations of the valence and sea light quark masses, are used to determine the low-energy parameters of staggered chiral perturbation theory. The physical decay constants are found in an extrapolation using the parameterized chiral formula.
Molecular anisotropic magnetoresistance
Otte, Fabian; Heinze, Stefan; Mokrousov, Yuriy
2015-01-01
Using density functional theory calculations, we demonstrate that the effect of anisotropic magnetoresistance (AMR) can be enhanced by orders of magnitude with respect to conventional bulk ferromagnets in junctions containing molecules sandwiched between ferromagnetic leads. We study ballistic transport in metal-benzene complexes contacted by $3d$ transition-metal wires. We show that the gigantic AMR can arise from spin-orbit coupling effects in the leads, drastically enhanced by orbital-symm...
Anisotropic mass density by two-dimensional acoustic metamaterials
Torrent Martí, Daniel; Sánchez-Dehesa Moreno-Cid, José
2008-01-01
We show that specially designed two-dimensional arrangements of full elastic cylinders embedded in a nonviscous fluid or gas define ( in the homogenization limit) a new class of acoustic metamaterials characterized by a dynamical effective mass density that is anisotropic. Here, analytic expressions for the dynamical mass density and the effective sound velocity tensors are derived in the long wavelength limit. Both show an explicit dependence on the lattice filling fraction, the elastic prop...
Extremely Anisotropic Scintillations
Walker, Mark; Bignall, Hayley
2008-01-01
A small number of quasars exhibit interstellar scintillation on time-scales less than an hour; their scintillation patterns are all known to be anisotropic. Here we consider a totally anisotropic model in which the scintillation pattern is effectively one-dimensional. For the persistent rapid scintillators J1819+3845 and PKS1257-326 we show that this model offers a good description of the two-station time-delay measurements and the annual cycle in the scintillation time-scale. Generalising the model to finite anisotropy yields a better match to the data but the improvement is not significant and the two additional parameters which are required to describe this model are not justified by the existing data. The extreme anisotropy we infer for the scintillation patterns must be attributed to the scattering medium rather than a highly elongated source. For J1819+3845 the totally anisotropic model predicts that the particular radio flux variations seen between mid July and late August should repeat between late Au...
Dimerized Mott insulators in hexagonal optical lattices
We study bosonic atoms in optical honeycomb lattices with anisotropic tunneling and find dimerized Mott insulator (MI) phases with fractional filling. These incompressible insulating phases are characterized by an interaction-driven localization of particles in respect to the individual dimers and large local particle-number fluctuations within the dimers. We calculate the ground-state phase diagrams and the excitation spectra using an accurate cluster mean-field method. The cluster treatment enables us to probe the fundamental excitations of the dimerized MI where the excitation gap is dominated by the intra-dimer tunneling amplitude. This allows the distinction from normal Mott insulating phases gapped by the on-site interaction. In addition, we present analytical results for the phase diagram derived by a higher-order strong-coupling perturbative expansion approach. By computing finite lattices with large diameters the influence of a harmonic confinement is discussed in detail. It is shown that a large fraction of atoms forms the dimerized MI under experimental conditions. The necessary anisotropic tunneling can be realized either by periodic driving of the optical lattice or by engineering directly a dimerized lattice potential. The dimers can be mapped to their antisymmetric states creating a lattice with coupled p-orbitals. (paper)
Ishikawa, K; Maeda, N.
2001-01-01
Physical properties of anisotropic compressible quantum Hall states and their implications to integer quantum Hall effect are studied based on a mean field theory on the von Neumann lattice. It is found that the Hall gas has unusual thermodynamic properties such as negative pressure and negative compressibility and unusual transport properties. Transport properties and density profile of Hall gas states at half fillings agree with those of anisotropic states discovered experimentally in highe...
DNA-nanoparticle superlattices formed from anisotropic building blocks
Jones, Matthew R; Macfarlane, Robert John; Lee, B.; Zhang, Jian; Young, Kaylie L; Senesi, Andrew J; Mirkin, Chad
2010-10-03
Directional bonding interactions in solid-state atomic lattices dictate the unique symmetries of atomic crystals, resulting in a diverse and complex assortment of three-dimensional structures that exhibit a wide variety of material properties. Methods to create analogous nanoparticle superlattices are beginning to be realized, but the concept of anisotropy is still largely underdeveloped in most particle assembly schemes. Some examples provide interesting methods to take advantage of anisotropic effects, but most are able to make only small clusters or lattices that are limited in crystallinity and especially in lattice parameter programmability. Anisotropic nanoparticles can be used to impart directional bonding interactions on the nanoscale, both through face-selective functionalization of the particle with recognition elements to introduce the concept of valency, and through anisotropic interactions resulting from particle shape. In this work, we examine the concept of inherent shape-directed crystallization in the context of DNA-mediated nanoparticle assembly. Importantly, we show how the anisotropy of these particles can be used to synthesize one-, two- and three-dimensional structures that cannot be made through the assembly of spherical particles.
Perfect Actions and Operators for Lattice QCD
Wiese, Uwe-Jens
1996-05-01
Wilson's renormalization group implies that lattice actions located on a renormalized trajectory emanating from a fixed point represent perfect discretizations of continuum physics. With a perfect action the spectrum of a lattice theory is identical with the one of the continuum theory even at finite lattice spacing. Similarly, perfect operators yield cut-off independent matrix elements. Hence, continuum QCD can in principle be reconstructed from a lattice with finite spacing. In practice it is difficult to construct perfect actions and perfect operators explicitly. Here perturbation theory is used to derive perfect actions for quarks and gluons by performing a block renormalization group transformation directly from the continuum. The renormalized trajectory for free massive quarks is identified and a parameter in the renormalization group transformation is tuned such that for 1-d configurations the perfect action reduces to the nearest neighbor Wilson fermion action. Then the 4-d perfect action turns out to be extremely local as well, which is vital for numerical simulations. The fixed point action for free gluons is also obtained by blocking from the continuum. For 2-d configurations it reduces to the standard plaquette action, and for 4-d configurations it is still very local. With interactions between quarks and gluons switched on the perfect quark-gluon and 3-gluon vertex functions are computed analytically. In particular, a perfect clover term can be extracted from the quark-gluon vertex. The perturbatively perfect action is directly applicable to heavy quark physics. The construction of a perfect QCD action for light quarks should include nonperturbative effects, which is possible using numerical methods. Classically perfect quark and gluon fields are constructed as well. They allow to interpolate the continuum fields from the lattice data. In this way one can obtain information about space-time regions between lattice points. The classically perfect fields
Momentum transport in strongly coupled anisotropic plasmas in the presence of strong magnetic fields
Finazzo, Stefano Ivo; Rougemont, Romulo; Noronha, Jorge
2016-01-01
We present a holographic perspective on momentum transport in strongly coupled, anisotropic non-Abelian plasmas in the presence of strong magnetic fields. We compute the anisotropic heavy quark drag forces and Langevin diffusion coefficients and also the anisotropic shear viscosities for two different holographic models, namely, a top-down deformation of strongly coupled $\\mathcal{N} = 4$ Super-Yang-Mills (SYM) theory triggered by an external Abelian magnetic field, and a bottom-up Einstein-Maxwell-dilaton (EMD) model which is able to provide a quantitative description of lattice QCD thermodynamics with $(2+1)$-flavors at both zero and nonzero magnetic fields. We find that, in general, energy loss and momentum diffusion through strongly coupled anisotropic plasmas are enhanced by a magnetic field being larger in transverse directions than in the direction parallel to the magnetic field. Moreover, the anisotropic shear viscosity coefficient is smaller in the direction of the magnetic field than in the plane pe...
Effect of toasting field beans and of grass-clover
Mogensen, Lisbeth; Vestergaard, Jannie Steensig; Fretté, Xavier; Lund, Peter; Weisbjerg, Martin Riis; Kristensen, Troels
The effect of toasting field beans and of grass-clover: maize silage ratio on milk production, milk composition and the sensory quality of the milk was investigated in a 2 2 factorial experiment. Toasting of field beans resulted in lower milk contents of both fat (44.2 versus 46.1 g/kg, P = 0.......02) and protein (33.5 versus 34.2 g/kg, P = 0.008), whereas milk production, urea and somatic cell contents were unaffected compared with the untreated field beans. Increasing the proportion of maize silage (from 9 to 21% of DM) in the ration decreased the content of urea in milk (P = 0.002), whereas milk......-β-carotene (P = 0.04) and β-carotene (P = 0.05). Toasting of field beans compared with untreated field beans did not affect the milk content of carotenoids and had only small effects on fatty acid composition. Regarding the sensory quality, the four treatments resulted in milk being characterized by a...
Nitrous oxide emissions from clover in the Mediterranean environment
Iride Volpi
2016-06-01
Full Text Available Introducing nitrogen N2-fixing crops into cereal-based crop rotations reduces N-fertiliser use and may mitigate soil emissions of nitrous oxide (N2O. However, the effect of the cultivation of N2-fixing crops on N2O emissions is still not well understood. N2O from N2-fixing crops can be emitted in two ways: during biological N2 fixation itself and when legume residues are returned to the soil. A field trial was carried out on clover (Trifolium squarrosum Savi to test the role of leguminous crops on N2O emissions in the Mediterranean environment. Monitoring was performed from December 2013 to September 2014. Cumulated N-N2O fluxes were calculated for the growing season (Phase 1 and the post-harvest period (Phase 2 in order to assess the importance of each phase. Our results did not show statistically significant differences between the two phases in term of contribution to the total cumulative N-N2O emissions, in fact Phase 1 and Phase 2 accounted respectively for 43 and 57% of the total.
Quark propagator and vertex: systematic corrections of hypercubic artifacts from lattice simulations
Boucaud, P; Leroy, J P; Le Yaouanc, A; Micheli, J; Moutarde, H; Pène, O; Rodríguez-Quintero, J; Boucaud, Ph.
2003-01-01
This is the first part of a study of the quark propagator and the vertex function of the vector current on the lattice in the Landau gauge and using both Wilson-clover and overlap actions. In order to be able to identify lattice artifacts and to reach large momenta we use a range of lattice spacings. The lattice artifacts turn out to be exceedingly large in this study. We present a new and very efficient method to eliminate the hypercubic (anisotropy) artifacts based on a systematic expansion on hypercubic invariants which are not SO(4) invariant. A simpler version of this method has been used in previous works. This method is shown to be significantly more efficient than the popular ``democratic'' methods. It can of course be applied to the lattice simulations of many other physical quantities. The analysis indicates a hierarchy in the size of hypercubic artifacts: overlap larger than clover and propagator larger than vertex function. This pleads for the combined study of propagators and vertex functions via...
Quantum transport in Dirac materials: Signatures of tilted and anisotropic Dirac and Weyl cones
Trescher, Maximilian; Sbierski, Björn; Brouwer, Piet W.; Bergholtz, Emil J.
2015-03-01
We calculate conductance and noise for quantum transport at the nodal point for arbitrarily tilted and anisotropic Dirac or Weyl cones. Tilted and anisotropic dispersions are generic in the absence of certain discrete symmetries, such as particle-hole and lattice point group symmetries. Whereas anisotropy affects the conductance g , but leaves the Fano factor F (the ratio of shot noise power and current) unchanged, a tilt affects both g and F . Since F is a universal number in many other situations, this finding is remarkable. We apply our general considerations to specific lattice models of strained graphene and a pyrochlore Weyl semimetal.
Model anisotropic quantum Hall states
Qiu, R. -Z.; Haldane, F.D.M.; Wan, Xin; Yang, Kun; Yi, Su
2012-01-01
Model quantum Hall states including Laughlin, Moore-Read and Read-Rezayi states are generalized into appropriate anisotropic form. The generalized states are exact zero-energy eigenstates of corresponding anisotropic two- or multi-body Hamiltonians, and explicitly illustrate the existence of geometric degrees of in the fractional quantum Hall effect. These generalized model quantum Hall states can provide a good description of the quantum Hall system with anisotropic interactions. Some numeri...
Highlighting the threat from current and near-future ozone pollution to clover in pasture
Globally, the legume–rhizobia symbiosis, contained within specialised organs called root nodules, is thought to add at least 30 Tg N annually to agricultural land. The growth and functioning of a modern white clover (Trifolium repens cv. Crusader) and red clover (T. pratense cv. Merviot) cultivar were investigated in current and future ozone scenarios in solardomes. Both cultivars developed leaf injury and had significant reductions in root biomass and root nodule number in response to ozone, with Crusader also displaying a reduced size and mass of nodules. In-situ measurements of N-fixation in Crusader by acetylene reduction assay revealed reduced N-fixation rates in a future scenario with an increased background and moderate peaks of ozone. The implications for the sustainability of temperate pasture are discussed. - Highlights: • Red and white clover cultivars displayed significant increases in foliar injury in increased ozone. • Both cultivars had reductions in total and root biomass and root nodule number. • White clover had a reduced size and mass of root nodules and reduced N-fixation rates. - Ozone effects on the growth and functioning of clover cultivars
Fons, F; Amellal, N; Leyval, C; Saint-Martin, N; Henry, M
2003-06-01
Plant secondary metabolites, such as saponins, have a considerable impact in agriculture because of their allelopathic effects. They also affect the growth of soil microorganisms, especially fungi. We investigated the influence of saponins on rhizosphere bacteria in vitro and in soil conditions. The effects of gypsophila saponins on the growth kinetics of rhizosphere bacteria were studied by monitoring the absorbance of the cultures in microtiter plates. Gypsophila saponins (1%) increased the lag phase of bacterial growth. The impact of gypsophila saponins on subterranean clover rhizosphere was also investigated in a pot experiment. The addition of gypsophila saponins did not modify clover biomass but significantly increased (twofold with 1% saponins) the weight of adhering soil. The number of culturable heterotrophic bacteria of the clover rhizosphere was not affected by the addition of gypsophila saponins. Nevertheless, the phenotypical characterization of the dominant Gram-negative strains of the clover rhizosphere, using the Biolog system, showed qualitative and quantitative differences induced by 1% saponins. With the addition of saponins, the populations of Chryseomonas spp. and Acinetobacter spp., the two dominant culturable genera of control clover, were no longer detectable or were significantly decreased, while that of Aquaspirillum dispar increased and Aquaspirillum spp. became the major genus. Aquaspirillum dispar and Aquaspirillum spp. were also the dominant rhizosphere bacteria of Gypsophila paniculata, which greatly accumulates these saponins in its roots. These results suggest that saponins may control rhizosphere bacteria in soil through rhizodeposition mechanisms. PMID:14569290
Red clover (Trifolium pratense L.), an important feed crop in many parts of the world, is exposed to elevated ozone over large areas. Plants can limit ozone-induced damages by various defence mechanisms. In this work, changes in the concentrations of antioxidant phenolic compounds induced by slightly elevated levels of ozone were determined in red clover leaves by high-performance liquid chromatography and mass spectrometry. 31 different phenolics were identified and the most abundant isoflavones and flavonoids were biochanin A glycoside malonate (G-M), formononetin-G-M and quercetin-G-M. Elevated ozone (mean 32.4 ppb) increased the total phenolic content of leaves and also had minor effects on the concentrations of individual compounds. Elevated ozone increased the net photosynthesis rate of red clover leaves before visible injuries by 21-23%. This study thus suggests that the concentrations of phenolics in red clover leaves change in response to slightly elevated ozone levels. - Concentrations of antioxidant phenolic compounds from red clover can be influenced by elevated ozone.
Saviranta, Niina M.M. [University of Kuopio, Department of Biosciences, Institute of Applied Biotechnology, Box 1627, 70211 Kuopio (Finland); Julkunen-Tiitto, Riitta; Oksanen, Elina [University of Joensuu, Faculty of Biosciences, Natural Product Research Laboratories, Box 111, 80101 Joensuu (Finland); Karjalainen, Reijo O., E-mail: reijo.karjalainen@uku.f [University of Kuopio, Department of Biosciences, Institute of Applied Biotechnology, Box 1627, 70211 Kuopio (Finland); AgriFood Research Finland, 31600 Jokioinen (Finland)
2010-02-15
Red clover (Trifolium pratense L.), an important feed crop in many parts of the world, is exposed to elevated ozone over large areas. Plants can limit ozone-induced damages by various defence mechanisms. In this work, changes in the concentrations of antioxidant phenolic compounds induced by slightly elevated levels of ozone were determined in red clover leaves by high-performance liquid chromatography and mass spectrometry. 31 different phenolics were identified and the most abundant isoflavones and flavonoids were biochanin A glycoside malonate (G-M), formononetin-G-M and quercetin-G-M. Elevated ozone (mean 32.4 ppb) increased the total phenolic content of leaves and also had minor effects on the concentrations of individual compounds. Elevated ozone increased the net photosynthesis rate of red clover leaves before visible injuries by 21-23%. This study thus suggests that the concentrations of phenolics in red clover leaves change in response to slightly elevated ozone levels. - Concentrations of antioxidant phenolic compounds from red clover can be influenced by elevated ozone.
On the Relativistic anisotropic configurations
Shojai, F; Stepanian, A
2016-01-01
In this paper we study anisotropic spherical polytropes within the framework of general relativity. Using the anisotropic Tolman-Oppenheimer-Volkov (TOV) equations, we explore the relativistic anisotropic Lane-Emden equations. We find how the anisotropic pressure affects the boundary conditions of these equations. Also we argue that the behaviour of physical quantities near the center of star changes in the presence of anisotropy. For constant density, a class of exact solution is derived with the aid of a new ansatz and its physical properties are discussed.
The Ds and D+ Leptonic Decay Constants from Lattice QCD
Bazavov, A; DeTar, C; Freeland, E D; Gamiz, E; Gottlieb, Steven; Heller, U M; Hetrick, J E; El-Khadra, A X; Kronfeld, A S; Laiho, J; Levkova, L; Mackenzie, P B; Oktay, M B; Di Pierro, M; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S
2009-01-01
We present the leptonic decay constants fDs and fD+ computed on the MILC collaboration's 2+1 flavor asqtad gauge ensembles. We use clover heavy quarks with the Fermilab interpretation and improved staggered light quarks. The simultaneous chiral and continuum extrapolation, which determines both decay constants, includes partially-quenched lattice results at lattice spacings a ~ 0:09, 0:12 and 0:15 fm. We have made several recent improvements in our analysis: a) we include terms in the fit describing leading order heavy-quark discretization effects, b) we have adopted a more precise input r1 value consistent with our other D and B meson studies, c) we have retuned the input bare charm masses based upon the new r1. Our preliminary results are fDs = 260 +/-10 MeV and fD+ = 217 +/-10 MeV.
Relaxation of Anisotropic Glasses
Deubener, Joachim; Martin, Birgit; Wondraczek, Lothar; Yue, Yuanzheng
2004-01-01
Anisotropic glasses are obtained from uniaxial compressing and pulling of glass forming liquids above the transition temperature range. To freeze-in, at least partly the structural state of the flowing melt, cylindrical samples were subjected to a controlled cooling process under constant load...... differential scanning calorimetry (DSC) and dilatometry. The energy release and expansion-shrinkage behaviour of the glasses are investigated as a function of the applied deformation stress. Structural origins of the frozen-in birefringence induced by viscous flow are discussed and correlation between the...
Anisotropically Inflating Universes
Barrow, J D; Barrow, John D.; Hervik, Sigbjorn
2008-01-01
We show that in theories of gravity that add quadratic curvature invariants to the Einstein-Hilbert action there exist expanding vacuum cosmologies with positive cosmological constant which do not approach the de Sitter universe. Exact solutions are found which inflate anisotropically. This behaviour is driven by the Ricci curvature invariant and has no counterpart in the general relativistic limit. These examples show that the cosmic no-hair theorem does not hold in these higher-order extensions of general relativity and raises new questions about the ubiquity of inflation in the very early universe and the thermodynamics of gravitational fields.
Anisotropic Stars Exact Solutions
Dev, K; Dev, Krsna; Gleiser, Marcelo
2000-01-01
We study the effects of anisotropic pressure on the properties of spherically symmetric, gravitationally bound objects. We consider the full general relativistic treatment of this problem and obtain exact solutions for various form of equations of state connecting the radial and tangential pressures. It is shown that pressure anisotropy can have significant effects on the structure and properties of stellar objects. In particular, the maximum value of 2M/R can approach unity (2M/R < 8/9 for isotropic objects) and the surface redshift can be arbitrarily large.
The Case Study: I'm Looking over a White-Striped Clover--A Case of Natural Selection
Krufka, Alison; Evarts, Susan; Wilson, Chester
2007-01-01
The case presented in this article is an exploration of the process of natural selection using white clover ("Trifolium repens") as an example. In general, two forms of white clover can be found around the world in various habitats. One type has plain green leaves and the other type produces cyanide as a defense against herbivores and signals the…
The effect of tillage prctices on a leek crop's nitrogen utilization from a grass-clover sward
Willekens, Koen; Van Gils, Bert; De Vliegher, Alex; Delanote, Lieven; Beeckman, Annelies; Vandecasteele, Bart
2014-01-01
Adopting conservation agriculture practices in organic agriculture involves some risks and challenges. Nitrogen availability from a grass-clover ley for the subsequent leek crop was clearly affected by mode and timing of destruction of the grass-clover sward. Minor differences were found between a reduced tillage practice and conventional ploughing.
Maria Dorenda
2014-08-01
Full Text Available Compositions of fungi communities in soil, rhizosphere, rhizoplane and roots of red clover and cocksfoot were analysed. All the changes occuring daring four-years, cultivation under mountain conditions were investigated. The effect of saprophytic fungi present in the analysed communitics on chosen red clover pathogens: Fusarium oxysporum f. sp. trifolii and Sclerotinia trifoliorum was also studied.
Three natural-track selected germplasms of Searls' prairie clover (Dalea searlsiae [A. Gray] Barneby [Fabaceae]) have been released for use in revegetation/restoration of semi-arid rangelands in the western US. Searls' prairie clover is a perennial leguminous forb that is native to Utah, Nevada, Ar...
Leaching of cyanogenic glucosides and cyanide from white clover green manure
Bjarnholt, Nanna; Lægdsmand, Mette; Hansen, Hans Chr. Bruun;
2008-01-01
lotaustralin; CGs release toxic hydrogen cyanide (HCN) upon hydrolysis which may be utilized for pest control. We demonstrate that applying CGs in the form of a liquid extract of white clover to large columns of intact agricultural soils can result in leaching of toxic cyanide species to a depth of at least 1......Use of crops for green manure as a substitute for chemical fertilizers and pesticides is an important approach towards more sustainable agricultural practices. Green manure from white clover is rich in nitrogen but white clover also produces the cyanogenic glucosides (CGs) linamarin and...... degradable natural products present in crop plants as defense compounds pose a threat to the quality of groundwater and surface waters. This aspect needs consideration in assessment of the risk associated with use of crops as green manure to replace chemical fertilizers and pesticides as well as in genetic...
Nitrogen fertilization of grass/clover swards under cutting or grazing by dairy cows
Søegaard, Karen
2009-01-01
Intensively managed perennial ryegrass/white clover (Lolium perenne L. and Trifolium repens L.) swards receive relatively high levels of fertilizer N, and high N surpluses can subsequently be found. The N-fertilization effects on growth, yield, and herbage quality were therefore examined on three...... farms over a period of three years. Nitrogen was applied at four rates (0, 75, 150, and 225 kg N year-1) with cutting or grazing regime in Year 1 and Year 2, after establishment. A spring-only application of 150 kg N was compared with four applications during the season, which was the fertilization...... affected. The results indicate different possibilities for strategic fertilization both at farm and field level, and in swards with a high clover content it demonstrates how the clover content can be used as a buffer both for maximizing the N-response and for manipulating the production profile....
Macedonian Genebank: Seed Protein Content of Wild Red Clover (Trifolium pratense L. Accessions
Suzana Kratovalieva
2013-01-01
Full Text Available During this study, the content of crude protein content in seeds of 23 wild red clover (Trifolium pratense L. populations, collected in East part of Macedonia, district Probistip, was assessed. On the basis of the average crude protein content, the collected accessions were divided into 3 groups with the crude protein content ≥ 15.0% (MKD01527, MKD01530, MKD01531, MKD01539, MKD01540, MKD01542, MKD01543; ≥ 16.0% (MKD01525, MKD01528, MKD01529, MKD0538, MKD01541, MKD01553, MKD01554, MKD01560 and ≥ 17.0% (MKD01536, MKD01537, MKD01544. The highest crude protein content of 17.3% was determined for population MKD01535 and the lowest (14.4 % for MKD01526.Information on protein content, as an indicator of wild red clover quality, could be used as a selection tool for identifying accessions to be included in red clover breeding programs.
Physiological function of non-glandular trichomes in red clover (Trifolium pratense L.
Naydenova Galina K.
2013-01-01
Full Text Available The objective of the trial was to study the physiological function and potential ecological significance of non-glandular trichomes in red clover based on their relation to the leaf transpiration intensity. The transpiration rate, relative water content and water deficit of the leaves were recorded in field-grown, high and slightly pubescent genotypes. According to results, the presence of nonglandular epidermal trichomes on the leaf surface of red clover was a micromorphological trait related to the regulation of leaf transpiration in stressful conditions. Non-glandular trichomes significantly enhanced water retention of the leaf tissue at high leaf water deficit. In the environmental conditions, limiting leaf evaporation, the pubescent genotypes displayed higher levels of transpiration. It can be suggested that the non-glandular trichomes in red clover are morphological structures supporting the function of leaf stoma apparatus. A positive relation between the degree of pubescence and resistance to powdery mildew was established under natural conditions.
Optics of anisotropic nanostructures
Rokushima, Katsu; Antoš, Roman; Mistrík, Jan; Višňovský, Štefan; Yamaguchi, Tomuo
2006-07-01
The analytical formalism of Rokushima and Yamakita [J. Opt. Soc. Am. 73, 901-908 (1983)] treating the Fraunhofer diffraction in planar multilayered anisotropic gratings proved to be a useful introduction to new fundamental and practical situations encountered in laterally structured periodic (both isotropic and anisotropic) multilayer media. These are employed in the spectroscopic ellipsometry for modeling surface roughness and in-depth profiles, as well as in the design of various frequency-selective elements including photonic crystals. The subject forms the basis for the solution of inverse problems in scatterometry of periodic nanostructures including magnetic and magneto-optic recording media. It has no principal limitations as for the frequencies and period to radiation wavelength ratios and may include matter wave diffraction. The aim of the paper is to make this formalism easily accessible to a broader community of students and non-specialists. Many aspects of traditional electromagnetic optics are covered as special cases from a modern and more general point of view, e.g., plane wave propagation in isotropic media, reflection and refraction at interfaces, Fabry-Perot resonator, optics of thin films and multilayers, slab dielectric waveguides, crystal optics, acousto-, electro-, and magneto-optics, diffraction gratings, etc. The formalism is illustrated on a model simulating the diffraction on a ferromagnetic wire grating.
Scattering phase shift for elastic two pion scattering and the rho resonance in lattice QCD
In this thesis we use lattice QCD to compute scattering phase shifts for elastic two-pion scattering in the isospin I=1 channel. Using Luescher's formalism, we derive the scattering phase shifts for different total momenta of the two-pion system in a non-rest frame. Furthermore we analyse the symmetries of the non-rest frame lattices and construct 2-pion and rho operators transforming in accordance with these symmetries. The data was collected for a 323 x 64 and a 403 x 64 lattice with Nf=2 clover improved Wilson fermions at a pion mass around 290 MeV and a lattice spacing of about 0.072 fm.
Scattering phase shift for elastic two pion scattering and the rho resonance in lattice QCD
Gutzwiller, Simone
2012-10-08
In this thesis we use lattice QCD to compute scattering phase shifts for elastic two-pion scattering in the isospin I=1 channel. Using Luescher's formalism, we derive the scattering phase shifts for different total momenta of the two-pion system in a non-rest frame. Furthermore we analyse the symmetries of the non-rest frame lattices and construct 2-pion and rho operators transforming in accordance with these symmetries. The data was collected for a 32{sup 3} x 64 and a 40{sup 3} x 64 lattice with N{sub f}=2 clover improved Wilson fermions at a pion mass around 290 MeV and a lattice spacing of about 0.072 fm.
Construction of a consensus linkage map for red clover (Trifolium pratense L.
Klimenko Irina
2009-05-01
Full Text Available Abstract Background Red clover (Trifolium pratense L. is a major forage legume that has a strong self-incompatibility system and exhibits high genetic diversity within populations. For several crop species, integrated consensus linkage maps that combine information from multiple mapping populations have been developed. For red clover, three genetic linkage maps have been published, but the information in these existing maps has not been integrated. Results A consensus linkage map was constructed using six mapping populations originating from eight parental accessions. Three of the six mapping populations were established for this study. The integrated red clover map was composed of 1804 loci, including 1414 microsatellite loci, 181 amplified fragment length polymorphism (AFLP loci and 204 restriction fragment length polymorphism (RFLP loci, in seven linkage groups. The average distance between loci and the total length of the consensus map were 0.46 cM and 836.6 cM, respectively. The locus order on the consensus map correlated highly with that of accession-specific maps. Segregation distortion was observed across linkage groups. We investigated genome-wide allele frequency in 1144 red clover individuals using 462 microsatellite loci randomly chosen from the consensus map. The average number of alleles and polymorphism information content (PIC were 9.17 and 0.69, respectively. Conclusion A consensus genetic linkage map for red clover was constructed for the first time based on six mapping populations. The locus order on the consensus map was highly conserved among linkage maps and was sufficiently reliable for use as a reference for genetic analysis of random red clover germplasms.
Reyes, E.; Krokhin, A. A.; Roberts, J.
2005-01-01
We calculate the static dielectric tensor of a periodic system of aligned anisotropic dielectric cylinders. Exact analytical formulas for the effective dielectric constants for the E- and H- eigenmodes are obtained for arbitrary 2D Bravais lattice and arbitrary cross-section of anisotropic cylinders. It is shown that depending on the symmetry of the unit cell photonic crystal of anisotropic cylinders behaves in the low-frequency limit like uniaxial or biaxial natural crystal. The developed th...
Anisotropic spheres in general relativity
A prescription originally conceived for perfect fluids is extended to the case of anisotropic pressures. The method is used to obtain exact analytical solutions of the Einstein equations for spherically symmetric selfgravitating distribution of anisotropic matter. The solutions are matched to the Schwarzschild exterior metric. (author). 15 refs
Large scale behavior of a two-dimensional model of anisotropic branched polymers.
Knežević, Milan; Knežević, Dragica
2013-10-28
We study critical properties of anisotropic branched polymers modeled by semi-directed lattice animals on a triangular lattice. Using the exact transfer-matrix approach on strips of quite large widths and phenomenological renormalization group analysis, we obtained pretty good estimates of various critical exponents in the whole high-temperature region, including the point of collapse transition. Our numerical results suggest that this collapse transition belongs to the universality class of directed percolation. PMID:24182076
Large scale behavior of a two-dimensional model of anisotropic branched polymers
Knežević, Milan; Knežević, Dragica
2013-10-01
We study critical properties of anisotropic branched polymers modeled by semi-directed lattice animals on a triangular lattice. Using the exact transfer-matrix approach on strips of quite large widths and phenomenological renormalization group analysis, we obtained pretty good estimates of various critical exponents in the whole high-temperature region, including the point of collapse transition. Our numerical results suggest that this collapse transition belongs to the universality class of directed percolation.
Field Theory of Anisotropic Quantum Hall Gas: Metrology and a Novel Quantum Hall Regime
Ishikawa, K; Aoyama, T.; Ishizuka, Y.; Maeda, N.
2003-01-01
The von Neumann lattice representation is a convenient representation for studying several intriguing physics of quantum Hall systems. In this formalism, electrons are mapped to lattice fermions. A topological invariant expression of the Hall conductance is derived and is used for the proof of the integer quantum Hall effect in the realistic situation. Anisotropic quantum Hall gas is investigated based on the Hartree-Fock approximation in the same formalism. Thermodynamic properties, transpor...
Anisotropic diffusion limited aggregation in three dimensions: Universality and nonuniversality
Goold, Nicholas R.; Somfai, Ellák; Ball, Robin C.
2005-09-01
We explore the macroscopic consequences of lattice anisotropy for diffusion limited aggregation (DLA) in three dimensions. Simple cubic and bcc lattice growths are shown to approach universal asymptotic states in a coherent fashion, and the approach is accelerated by the use of noise reduction. These states are strikingly anisotropic dendrites with a rich hierarchy of structure. For growth on an fcc lattice, our data suggest at least two stable fixed points of anisotropy, one matching the bcc case. Hexagonal growths, favoring six planar and two polar directions, appear to approach a line of asymptotic states with continuously tunable polar anisotropy. The more planar of these growths visually resembles real snowflake morphologies. Our simulations use a new and dimension-independent implementation of the DLA model. The algorithm maintains a hierarchy of sphere coverings of the growth, supporting efficient random walks onto the growth by spherical moves. Anisotropy was introduced by restricting growth to certain preferred directions.
Preliminary research on amino acid composition and nutritional value of clover proteins
L. Kłyszejko-Stefanowicz
2015-06-01
Full Text Available The amino acid composition and nutritional value of 5 clover varieties including 3 Polish ones ('Gloria', 'Hruszowska', 'Skrzeszowicka' and 2 of foreign origin ('Rotra' and 'Violetta' were investigated. No significant differences in the total protein content (19.2–20.0% of dry matter as well as in qualitative amino acid composition were found among the clover varieties under examination. EAA index (Essential amino acid index calculated according to Oser for 'Gloria' and 'Hruszowska' showed the highest nutritional value was – 40. The lowest value of EAA index was found for 'Violetta' cvar. – 32, intermediate values however for Rotra and Skrzeszowicka was 37 and 36.
Lucerne (Medicago sativa) or grass-clover as cut-and-carry fertilizers in organic agriculture
Burgt, van der, A.; Eekeren, van, N.J.M.; Scholberg, J.M.S.; Koopmans, C.J.
2013-01-01
On-farm nitrogen fixation is a driving force in organic agriculture. The efficiency with which this nitrogen is used can be increased by using lucerne (Medicago sativa) or grass-clover directly as sources of fertilizer on arable land: cut-and-carry fertilizers. In two arable crops, the use of lucerne and grass-clover as fertilizers was compared with the use of poultry manure and slurry. The nitrogen-use efficiency at crop level was comparable or better for the cut-andcarry fertilizers as comp...
Tzanakakis, Vasileios; Sturite, Ievina; Dörsch, Peter
2016-04-01
Biological nitrogen fixation (BNF) can substantially contribute to N supply in permanent grasslands, improving N yield and forage quality, while reducing inorganic N inputs. Among the factors critical to the performance of BNF in grass-legume mixtures are selected grass and legume species, proportion of legumes, the soil-climatic conditions, in particular winter conditions, and management practices (e.g. fertilization and compaction). In high latitude grasslands, low temperatures can reduce the performance of BNF by hampering the legumés growth and by suppressing N2 fixation. Estimation of BNF in field experiments is not straightforward. Different methods have been developed providing different results. In the present study, we evaluated the performance of BNF, in a newly established field experiment in North Norway over four years. The grassland consisted of white clover (Trifolium repens L.) and red clover (Trifolium pretense L.) sawn in three proportions (0, 15 and 30% in total) together with timothy (Pheum pretense L.) and meadow fescue (Festuca pratensis L.). Three levels of compaction were applied each year (no tractor, light tractor, heavy tractor) together with two different N rates (110 kg N/ha as cattle slurry or 170 kg N/ha as cattle slurry and inorganic N fertilizer). We applied two different methods, the 15N natural abundance and the difference method, to estimate BNF in the first harvest of each year. Overall, the difference method overestimated BNF relative to the 15N natural abundance method. BNF in the first harvest was compared to winter survival of red and white clover plants, which decreased with increasing age of the grassland. However, winter conditions did not seem to affect the grassland's ability to fix N in spring. The fraction of N derived from the atmosphere (NdfA) in white and red clover was close to 100% in each spring, indicating no suppression of BNF. BNF increased the total N yield of the grasslands by up to 75%, mainly due to high
Averaging anisotropic cosmologies
Barrow, J D; Barrow, John D.; Tsagas, Christos G.
2006-01-01
We examine the effects of spatial inhomogeneities on irrotational anisotropic cosmologies by looking at the average properties of pressure-free Bianchi-type models. Adopting the Buchert averaging scheme, we identify the kinematic backreaction effects by focussing on spacetimes with zero or isotropic spatial curvature. This allows us to close the system of the standard scalar formulae with a propagation equation for the shear magnitude. We find no change in the already known conditions for accelerated expansion. The backreaction terms are expressed as algebraic relations between the mean-square fluctuations of the models' irreducible kinematical variables. Based on these we investigate the early evolution of averaged vacuum Bianchi type $I$ universes and those filled with pressureless matter. In the latter case we show that the backreaction effects can modify the familiar Kasner-like singularity and potentially remove Mixmaster-type oscillations. We also discuss the possibility of accelerated expansion due to ...
Thermodynamics of anisotropic branes
Ávila, Daniel; Patiño, Leonardo; Trancanelli, Diego
2016-01-01
We study the thermodynamics of flavor D7-branes embedded in an anisotropic black brane solution of type IIB supergravity. The flavor branes undergo a phase transition between a `Minkowski embedding', in which they lie outside of the horizon, and a `black hole embedding', in which they fall into the horizon. This transition depends on two independent dimensionless ratios, which are formed out of the black hole temperature, its anisotropy parameter, and the mass of the flavor degrees of freedom. It happens either at a critical temperature or at a critical anisotropy. A general lesson we learn from this analysis is that the anisotropy, in this particular realization, induces similar effects as the temperature. In particular, increasing the anisotropy bends the branes more and more into the horizon. Moreover, we observe that the transition becomes smoother for higher anisotropies.
LATTICE: an interactive lattice computer code
LATTICE is a computer code which enables an interactive user to calculate the functions of a synchrotron lattice. This program satisfies the requirements at LBL for a simple interactive lattice program by borrowing ideas from both TRANSPORT and SYNCH. A fitting routine is included
Anisotropic collective motion contributes to nuclear spin relaxation in crystalline proteins.
Lewandowski, Józef R; Sein, Julien; Blackledge, Martin; Emsley, Lyndon
2010-02-01
A model for calculating the influence of anisotropic collective motions on NMR relaxation rates in crystalline proteins is presented. We show that small-amplitude (<10 degrees ) fluctuations may lead to substantial contributions to the (15)N spin-lattice relaxation rates and propose that the effect of domain motions should be included in solid-state NMR analyses of protein dynamics. PMID:19916496
DiMarzio's lattice model is successfully applied to describe the equilibrium partitioning of blocklike molecules between an isotropic mobile phase and an anisotropic stationary phase in various types of fluid chromatography to obtain a retention equation. A linear relationship between the logarithm of the solute distribution coefficient and minimum area is predicted. 44 refs., 8 figs., 2 tabs
Anisotropic Inflation with General Potentials
Shi, Jiaming; Qiu, Taotao
2015-01-01
Anomalies in recent observational data indicate that there might be some "anisotropic hair" generated in an inflation period. To obtain general information about the effects of this anisotropic hair to inflation models, we studied anisotropic inflation models that involve one vector and one scalar using several types of potentials. We determined the general relationship between the degree of anisotropy and the fraction of the vector and scalar fields, and concluded that the anisotropies behave independently of the potentials. We also generalized our study to the case of multi-directional anisotropies.
Monte Carlo lattice program KIM
The Monte Carlo program KIM solves the steady-state linear neutron transport equation for a fixed-source problem or, by successive fixed-source runs, for the eigenvalue problem, in a two-dimensional thermal reactor lattice. Fluxes and reaction rates are the main quantities computed by the program, from which power distribution and few-group averaged cross sections are derived. The simulation ranges from 10 MeV to zero and includes anisotropic and inelastic scattering in the fast energy region, the epithermal Doppler broadening of the resonances of some nuclides, and the thermalization phenomenon by taking into account the thermal velocity distribution of some molecules. Besides the well known combinatorial geometry, the program allows complex configurations to be represented by a discrete set of points, an approach greatly improving calculation speed
Diagnostics of viruses infecting clover and lucerne breeding material in the Czech Republic
Fránová, Jana; Petrzik, Karel; Jakešová, H.; Bečková, M.; Sarkisova, Tatiana
Ljubljana : National Institute of Biology, 2008. s. 45. [Conference of the International Working Group on Legume and Vegetable Viruses/3./. 20.08.2008-23.08.2008, Ljubljana] R&D Projects: GA MZe QH71145 Institutional research plan: CEZ:AV0Z50510513 Keywords : viruses infection * clover * lucerne * Czech Republic Subject RIV: EE - Microbiology, Virology
Investigation of add-back effects in a segmented Clover detector
The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in γ spectroscopic experiments. The measurements have been performed with standard radioactive sources of 152Eu, 133Ba and β-delayed γ-rays from 176Ir decay. The data analytic results, realized by software, are presented in this paper. (authors)
Relationships between Nitrate and Oxygen Supply in Symbiotic Nitrogen Fixation by White Clover
Minchin, F. R.; Ines Minguez, M.; Sheedy, J. E.; Witty, J. E.; Skøt, L.
1986-01-01
Exposure of mature, nodulated plants of white clover (Trifolium repens) cv. Blanca to 330 mg dm−3 NO3-N for 8 d caused nitrogenase activity per plant to decrease by 80%. Total nodulated root respiration was not significantly affected but analysis of its components showed an 81% decrease in nitrog...
Modelling Gene Flow between Fields of White Clover with Honeybees as Pollen Vectors
Løjtnant, Christina; Boelt, Birte; Clausen, Sabine Karin;
2012-01-01
The portion-dilution model is a parametric restatement of the conventional view of animal pollination; it predicts the level of pollinator-mediated gene dispersal. In this study, the model was applied to white clover (Trifolium repens) and its most frequent pollinator, the honeybee (Apis mellifera...
Improving Resilience of Northern Field Crop Systems Using Inter-Seeded Red Clover: A Review
William Deen
2013-02-01
Full Text Available In light of the environmental challenges ahead, resilience of the most abundant field crop production systems must be improved to guarantee yield stability with more efficient use of nitrogen inputs, soil and water resources. Along with genetic and agronomic innovations, diversification of northern agro-ecosystems using inter-seeded legumes provides further opportunities to improve land management practices that sustain crop yields and their resilience to biotic and abiotic stresses. Benefits of legume cover crops have been known for decades and red clover (Trifolium pratense is one of the most common and beneficial when frost-seeded under winter wheat in advance of maize in a rotation. However, its use has been declining mostly due to the use of synthetic fertilizers and herbicides, concerns over competition with the main crop and the inability to fully capture red clover benefits due to difficulties in the persistence of uniform stands. In this manuscript, we first review the environmental, agronomic, rotational and economical benefits associated with inter-seeded red clover. Red clover adaptation to a wide array of common wheat-based rotations, its potential to mitigate the effects of land degradation in a changing climate and its integration into sustainable food production systems are discussed. We then identify areas of research with significant potential to impact cropping system profitability and sustainability.
RUMEN MICROBE ADAPTATION TO RED CLOVER POLYPHENOL OXIDASE PROTEIN AND LIPID PROTECTION
Introduction: Polyphenol oxidase (PPO) has been shown to reduce both proteolysis and lipolysis in incubated red clover (Lee et al. 2004). However it has not been determined whether rumen microbes can adapt to utilize PPO-protected protein and lipid. This study investigated whether rumen inoculum fro...
Wenhua Du
2013-12-01
Full Text Available Red clover (Trifoliumpratense L. as a dietary supplement is currently used to treat menopausal symptoms because of its high concentrations of mildly estrogenic isoflavone. The application rate of N and P fertilizer has a huge influence on the isoflavone content (IC in red clover. Trifolium pratense 'Minshan' is a unique plant resource in the alpine pasture region of northwest China. It plays a very important role in livestock production and the pharmaceutical industry because of its high nutritional value and IC. To date, little information exists on the selection of optimal N and P application rates to maximize the IC in red clover. Therefore, a 3-yr study was conducted to define the optimum N and P application rate to achieve a high IC in 'Minshan'. The results showed that topdressing 50 kg N ha-1 yr-1 with 52-105 kg P ha-1 yr-1 could produce a high level of IC at the branching, flower bud, early flowering, full flowering, pod setting, and mature stages in red clover. Second-year crops produced higher IC than did third-year crops. The IC was highest during the vegetative growing period and started to decline following the reproductive development of the plant until the seeds matured.
Estimating impact on clover-grass yield caused by traffic intensities
Jørgensen, Rasmus Nyholm; Sørensen, Claus Grøn; Green, Ole;
2009-01-01
intensities and 35 replicates was established. Each net parcel measured 9 x 1.3 m and the 24 treatments were randomized onto the 840 net parcels. The grass clover was established in spring 2007 using RTK-GPS auto steered tractors and implements. A Claas Axion tractor equipped with AutoFarm RTK Auto...
The content of isoflavones in red clover (T. pratense L. breeding material
Stanisław Burda
2013-12-01
Full Text Available The contents of four isoflavones: daidzein, genistein, formononetin and biochanin A were analysed in breeding stocks of red clover with the purpose to find stocks with the highest and lowest levels of these compounds. The total content of the isoflavones in twenty nine stocks studied, varied within the range of 0,70 to 1,19% D.M.
Leaf proteins in five varieties of red clover cultivated in Poland
W. Maciejewska-Potapczyk
2015-06-01
Full Text Available Protein fractions: albumins, globulins, gluteins and prolamins were extracted from the leaves of 5 varieties of red clover. 'Skrzeszowicka' and 'Hruszowska' showed the highest content of total protein, 'Rotra' however – the highest globulin level. Globulins were fractionated on DEAE cellulose column into 3 fractions. Globulins from 'Rotra' and 'Hruszowska' varieties were separated into 4 fractions.
Forage yield and persistence of red clover progenies in two environments
Montardo Daniel Portella
2003-01-01
Full Text Available Red clover (Trifolium pratense L. is one of the most important temperate legume species, used to lessen the lack of forage during the critical fall-winter period in Rio Grande do Sul, RS, Brazil. However, its utilization has been restricted mainly because of its lack of persistence. This work evaluates the dry matter yield and persistence of red clover half-sib progenies in two physiographic regions of RS: "Depressão Central", in Eldorado do Sul and "Encosta Superior do Nordeste", in Veranópolis. Experiments were carried out for two growing seasons and results were compared to two red clover commercial checks, Qüiñequeli and Estanzuela 116. The region of Veranópolis was more adequate for red clover forage production, enabling better yield and persistence. The best check for both locations was cultivar Estanzuela 116. At Eldorado do Sul persistence was highly affected and some progenies were superior to the best check. At Veranópolis the best check was very productive, with good persistence. The best progenies at both locations were selected to be propagated and submitted to additional recurrent selection cycles.
Red clover contains high levels of polyphenol oxidase (PPO) activity and o-diphenol substrates resulting in a characteristic post-harvest browning reaction associated with decreased protein degradation during ensiling. To define PPO's role in inhibiting post-harvest proteolysis, we are using both bi...
In situ carbon and nitrogen dynamics in ryegrass-clover mixtures
Rasmussen, J.; Eriksen, J.; Jensen, Erik Steen;
2007-01-01
.4% (±0.1, n=9). 15N-enriched compounds were not detected in percolating pore water, which may be caused by either dilution from irrigation or low availability of leachable N compounds. 14C was found solely as 14CO2 in the pore water indicating that dissolved organic carbon (DOC) did not originate from......Carbon (C) and nitrogen (N) dynamics in a third production year ryegrass–clover mixture were investigated in the field. Cylinders (diameter 29.7 cm) were installed to depths of 20, 40 and 60 cm and equipped with suction cups to collect percolating pore water. Ryegrass and clover leaves were cross......-labelled with 14C- and 15N-enriched urea and the fate of the two tracers was studied for 3 months during summer. Transfer of 14C occurred mainly from ryegrass to clover, whereas the largest transfer of 15N was in the opposite direction. The average transfer of N from clover was 40% (SE±3.1, n=9) of N in...
This experiment was conducted in 2005-2007 to evaluate carcass and meat quality parameters when meat goat kids were finished on alfalfa (Medicago sativa L; ALF); red clover (Trifolium pretense L.; RCG); or orchardgrass (Dactylis glomerata L; OGR) pastures. Final shrunk body weights were similar whe...
Red clover polyphenol oxidase reduces ruminal lipolysis in in vitro batch culture
Introduction. It has been shown that the rate of lipolysis and proteolysis differs significantly between red clover genotypes with different levels of polyphenol oxidase (PPO) activity (Lee et al. 2004). Sullivan and Hatfield, (2006) reported the development of genetically modified isolines of red c...
Polyphenol oxidase (PPO) genes and their corresponding enzyme activity occur in many plants; natural PPO substrates and enzyme/substrate localization are less well characterized. Leaf and root PPO activity in Arabidopsis and five legumes were compared with high-PPO red clover (Trifolium pratense L.)...
Red clover leaves accumulate high levels of two o-diphenols, phasalic acid (caffeoyl ester of malic acid) and clovamide (caffeoyl amide of L-DOPA). Post-harvest oxidation of these o-diphenols by an endogenous polyphenol oxidase (PPO) prevents breakdown of forage protein during storage. Understanding...