Testing of pear trees on their own roots in comparison with important used rootstocks under organic farming conditions with special regard to fire blight (E. amylovora)

Pear trees on their own roots are tested in comparison to grafted trees in growth and yield characteristics and with special regard to the tolerance to diseases, above all fire blight (Erwinia amylovora). In spring 2004 15 randomized trees of the cultivar 'Williams' from three variants (self rooted in vitro, self rooted long cuttings, grafted on Quince A) were planted in a pear orchard, which was heavily infected with fire blight (Erwinia amylovora) the previous years. The trees were left untreated. Growth and yield characteristics, plant diseases and tree losses were observed. After four years the in vitro self rooted trees were significantly more vigorous in growth than those grafted on quince A. The self rooted long cuttings were comparable in growth with grafts on quince, but showed high tree losses probably due to frost damages in the first winter one year after planting. However no infections with Erwinia amylovora could be observed so far. In a field trial with more cultivars and rootstock variants planted in 2006 at two organically managed sites more significant effects are expected in the next years

An Introduction to Conformal Ricci Flow

We introduce a variation of the classical Ricci flow equation that modifies the unit volume constraint of that equation to a scalar curvature constraint. The resulting equations are named the Conformal Ricci Flow Equations because of the role that conformal geometry plays in constraining the scalar curvature. These equations are analogous to the incompressible Navier-Stokes equations of fluid mechanics inasmuch as a conformal pressure arises as a Lagrange multiplier to conformally deform the metric flow so as to maintain the scalar curvature constraint. The equilibrium points are Einstein metrics with a negative Einstein constant and the conformal pressue is shown to be zero at an equilibrium point and strictly positive otherwise. The geometry of the conformal Ricci flow is discussed as well as the remarkable analytic fact that the constraint force does not lose derivatives and thus analytically the conformal Ricci equation is a bounded perturbation of the classical unnormalized Ricci equation. That the constraint force does not lose derivatives is exactly analogous to the fact that the real physical pressure force that occurs in the Navier-Stokes equations is a bounded function of the velocity. Using a nonlinear Trotter product formula, existence and uniqueness of solutions to the conformal Ricci flow equations is proven. Lastly, we discuss potential applications to Perelman's proposed implementation of Hamilton's program to prove Thurston's 3-manifold geometrization conjectures.Comment: 52 pages, 1 figur

Long-range beam-beam experiments in the relativistic heavy ion collider

Long-range beam-beam effects are a potential limit to the LHC performance with the nominal design parameters, and certain upgrade scenarios under discussion. To mitigate long-range effects, current carrying wires parallel to the beam were proposed and space is reserved in the LHC for such wires. Two current carrying wires were installed in RHIC to study the effect of strong long-range beam-beam effects in a collider, as well as test the compensation of a single long-range interaction. The experimental data were used to benchmark simulations. We summarize this work.Comment: 12 pages, contribution to the ICFA Mini-Workshop on Beam-Beam Effects in Hadron Colliders, CERN, Geneva, Switzerland, 18-22 Mar 201

Deployable antenna demonstration project

Test program options are described for large lightweight deployable antennas for space communications, radar and radiometry systems

Beyond density functional theory: the domestication of nonlocal potentials

Due to efficient scaling with electron number N, density functional theory (DFT) is widely used for studies of large molecules and solids. Restriction of an exact mean-field theory to local potential functions has recently been questioned. This review summarizes motivation for extending current DFT to include nonlocal one-electron potentials, and proposes methodology for implementation of the theory. The theoretical model, orbital functional theory (OFT), is shown to be exact in principle for the general N-electron problem. In practice it must depend on a parametrized correlation energy functional. Functionals are proposed suitable for short-range Coulomb-cusp correlation and for long-range polarization response correlation. A linearized variational cellular method (LVCM) is proposed as a common formalism for molecules and solids. Implementation of nonlocal potentials is reduced to independent calculations for each inequivalent atomic cell.Comment: Accepted for publication in Modern Physics Letters B (2004

Radiant heat exchange in a space environment Scientific technical report, 1 Feb. - 31 Jul. 1970

Spectral and directional surface property effects on radiant heat transfer in space environmen

Metastability and uniqueness of vortex states at depinning

We present results from numerical simulations of transport of vortices in the zero-field cooled (ZFC) and the field-cooled (FC) state of a type-II superconductor. In the absence of an applied current $I$, we find that the FC state has a lower defect density than the ZFC state, and is stable against thermal cycling. On the other hand, by cycling $I$, surprisingly we find that the ZFC state is the stable state. The FC state is metastable as manifested by increasing $I$ to the depinning current $I_{c}$, in which case the FC state evolves into the ZFC state. We also find that all configurations acquire a unique defect density at the depinning transition independent of the history of the initial states.Comment: 4 pages, 4 figures. Problem of page size correcte