3,571 research outputs found
Analysis of the Soil Foodweb Structure on Organic- and Conventional Dairy Farms
The below ground biodiversity of soil organisms plays an important role in the functioning of the soil ecosystem, and consequently the efficiency of the above ground plant production on dairy farms. However, for farmers, soil biology remains a black box. It is difficult to interpret soil biology on dairy farms and to identify management measures to improve it. The objective of this study was to investigate if it is possible to classify the soil foodweb structure on a dairy farm in relation to management practice
The Einstein 3-form G_a and its equivalent 1-form L_a in Riemann-Cartan space
The definition of the Einstein 3-form G_a is motivated by means of the
contracted 2nd Bianchi identity. This definition involves at first the complete
curvature 2-form. The 1-form L_a is defined via G_a = L^b \wedge #(o_b \wedge
o_a). Here # denotes the Hodge-star, o_a the coframe, and \wedge the exterior
product. The L_a is equivalent to the Einstein 3-form and represents a certain
contraction of the curvature 2-form. A variational formula of Salgado on
quadratic invariants of the L_a 1-form is discussed, generalized, and put into
proper perspective.Comment: LaTeX, 13 Pages. To appear in Gen. Rel. Gra
Transmission properties of a single metallic slit: From the subwavelength regime to the geometrical-optics limit
In this work we explore the transmission properties of a single slit in a
metallic screen. We analyze the dependence of these properties on both slit
width and angle of incident radiation. We study in detail the crossover between
the subwavelength regime and the geometrical-optics limit. In the subwavelength
regime, resonant transmission linked to the excitation of waveguide resonances
is analyzed. Linewidth of these resonances and their associated electric field
intensities are controlled by just the width of the slit. More complex
transmission spectra appear when the wavelength of light is comparable to the
slit width. Rapid oscillations associated to the emergence of different
propagating modes inside the slit are the main features appearing in this
regime.Comment: Accepted for publication in Phys. Rev.
A formal framework for a nonlocal generalization of Einstein's theory of gravitation
The analogy between electrodynamics and the translational gauge theory of
gravity is employed in this paper to develop an ansatz for a nonlocal
generalization of Einstein's theory of gravitation. Working in the linear
approximation, we show that the resulting nonlocal theory is equivalent to
general relativity with "dark matter". The nature of the predicted "dark
matter", which is the manifestation of the nonlocal character of gravity in our
model, is briefly discussed. It is demonstrated that this approach can provide
a basis for the Tohline-Kuhn treatment of the astrophysical evidence for dark
matter.Comment: 13 pages RevTex, no figures; v2: minor corrections, reference added,
matches published versio
Device for multi phase and single phase contacting
A multiphase contacting stage is provided that includes a first rotatable disc having a hollow disc-shaped cavity, an input port and an output port, and a second rotatable disc, where the second rotatable disc has a channeled cavity, an input port and an output port, and is disposed in the hollow disc-shaped cavity of the first rotatable disc, where the first rotatable disc and said second rotatable disc are concentric about an axis, where the multiphase contacting stage operates to integrate centrifugal separation and countercurrent mass transfer of a material for separation
Device for multiphase and single phase contacting
A multiphase contacting stage is provided that includes a first rotatable disc having a hollow disc-shaped cavity, an input port and an output port, and a second rotatable disc, where the second rotatable disc has a channeled cavity, an input port and an output port, and is disposed in the hollow disc-shaped cavity of the first rotatable disc, where the first rotatable disc and said second rotatable disc are concentric about an axis, where the multiphase contacting stage operates to integrate centrifugal separation and countercurrent mass transfer of a material for separation
Low-crosstalk bifurcation detectors for coupled flux qubits
We present experimental results on the crosstalk between two AC-operated
dispersive bifurcation detectors, implemented in a circuit for high-fidelity
readout of two strongly coupled flux qubits. Both phase-dependent and
phase-independent contributions to the crosstalk are analyzed. For proper
tuning of the phase the measured crosstalk is 0.1 % and the correlation between
the measurement outcomes is less than 0.05 %. These results show that
bifurcative readout provides a reliable and generic approach for multi-partite
correlation experiments.Comment: Copyright 2010 American Institute of Physics. This article may be
downloaded for personal use only. Any other use requires prior permission of
the author and the American Institute of Physics. The following article
appeared in Applied Physics Letters and may be found at
http://link.aip.org/link/?apl/96/12350
Poisson structures for reduced non-holonomic systems
Borisov, Mamaev and Kilin have recently found certain Poisson structures with
respect to which the reduced and rescaled systems of certain non-holonomic
problems, involving rolling bodies without slipping, become Hamiltonian, the
Hamiltonian function being the reduced energy. We study further the algebraic
origin of these Poisson structures, showing that they are of rank two and
therefore the mentioned rescaling is not necessary. We show that they are
determined, up to a non-vanishing factor function, by the existence of a system
of first-order differential equations providing two integrals of motion. We
generalize the form of that Poisson structures and extend their domain of
definition. We apply the theory to the rolling disk, the Routh's sphere, the
ball rolling on a surface of revolution, and its special case of a ball rolling
inside a cylinder.Comment: 22 page
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