10,760 research outputs found
Organic Farming Scenarios: Operational Analysis and Costs of implementing Innovative Technologies
The objective of this study has been to design a number of farm scenarios representing future plausible and internally consistent organic farming enterprises based on milk, pig, and plant production and use these farm scenarios as the basis for the generation of generalised knowledge on labour and machinery input and costs. Also, an impact analysis and feasibility study of introducing innovative technologies into the organic
production system has been invoked.
The labour demand for the production farms ranged from 61 to 253hha1 and from 194 to 396hLU1 (LU is livestock units) for work in the animal houses. Model validation results showed that farm managerial tasks amount to 14–19% of the total labour requirement. The impact of introducing new technologies and work methods related to organic farming was evaluated using two innovative examples of weed control: a
weeding robot and an integrated system for band steaming. While these technologies increased the capital investment required, the labour demand was reduced by 83–85% in sugar beet and 60% in carrots, which would improve profitability by 72–85% if fully utilised. Profitability is reduced, if automation efforts result in insufficient weed removal compared to manual weeding. Specifically, the benefit gained by robotic weeding
was sensitive to the weed intensity and the initial price of the equipment, but a weeding efficiency of under 25% is required to make it unprofitable.
This approach demonstrates the feasibility of applying and testing operational models in organic farming systems in the continued evaluation and documentation of labour and machinery inputs
Panel Discussion - Management of Eurasian watermilfoil in the United States using native insects: State regulatory and management issues
While researchers have evaluated the potential of native
insect herbivores to manage nonindigenous aquatic plant
species such as Eurasian watermilfoil (
Myriophyllum spicatum
L.), the practical matters of regulatory compliance and implementation
have been neglected. A panel of aquatic nuisance
species program managers from three state natural
resource management agencies (Minnesota, Vermont and
Washington) discussed their regulatory and policy concerns.
In addition, one ecological consultant attempting to market
one of the native insects to manage Eurasian watermilfoil
added his perspective on the special challenges of distributing
a native biological control agent for management of Eurasian
watermilfoil
High Q Cavity Induced Fluxon Bunching in Inductively Coupled Josephson Junctions
We consider fluxon dynamics in a stack of inductively coupled long Josephson
junctions connected capacitively to a common resonant cavity at one of the
boundaries. We study, through theoretical and numerical analysis, the
possibility for the cavity to induce a transition from the energetically
favored state of spatially separated shuttling fluxons in the different
junctions to a high velocity, high energy state of identical fluxon modes.Comment: 8 pages, 5 figure
Magnetoresistence engineering and singlet/triplet switching in InAs nanowire quantum dots with ferromagnetic sidegates
We present magnetoresistance (MR) experiments on an InAs nanowire quantum dot
device with two ferromagnetic sidegates (FSGs) in a split-gate geometry. The
wire segment can be electrically tuned to a single dot or to a double dot
regime using the FSGs and a backgate. In both regimes we find a strong MR and a
sharp MR switching of up to 25\% at the field at which the magnetizations of
the FSGs are inverted by the external field. The sign and amplitude of the MR
and the MR switching can both be tuned electrically by the FSGs. In a double
dot regime close to pinch-off we find {\it two} sharp transitions in the
conductance, reminiscent of tunneling MR (TMR) between two ferromagnetic
contacts, with one transition near zero and one at the FSG switching fields.
These surprisingly rich characteristics we explain in several simple resonant
tunneling models. For example, the TMR-like MR can be understood as a
stray-field controlled transition between singlet and a triplet double dot
states. Such local magnetic fields are the key elements in various proposals to
engineer novel states of matter and may be used for testing electron spin-based
Bell inequalities.Comment: 7 pages, 6 figure
Measuring the effective phonon density of states of a quantum dot
We employ detuning-dependent decay-rate measurements of a quantum dot in a
photonic-crystal cavity to study the influence of phonon dephasing in a
solid-state quantum-electrodynamics experiment. The experimental data agree
with a microscopic non-Markovian model accounting for dephasing from
longitudinal acoustic phonons, and identifies the reason for the hitherto
unexplained difference between non-resonant cavity feeding in different
nanocavities. From the comparison between experiment and theory we extract the
effective phonon density of states experienced by the quantum dot. This
quantity determines all phonon dephasing properties of the system and is found
to be described well by a theory of bulk phonons.Comment: 5 pages, 3 figures, submitte
Magnetometry with entangled atomic samples
We present a theory for the estimation of a scalar or a vector magnetic field
by its influence on an ensemble of trapped spin polarized atoms. The atoms
interact off-resonantly with a continuous laser field, and the measurement of
the polarization rotation of the probe light, induced by the dispersive
atom-light coupling, leads to spin-squeezing of the atomic sample which enables
an estimate of the magnetic field which is more precise than that expected from
standard counting statistics. For polarized light and polarized atoms, a
description of the non-classical components of the collective spin angular
momentum for the atoms and the collective Stokes vectors of the light-field in
terms of effective gaussian position and momentum variables is practically
exact. The gaussian formalism describes the dynamics of the system very
effectively and accounts explicitly for the back-action on the atoms due to
measurement and for the estimate of the magnetic field. Multi-component
magnetic fields are estimated by the measurement of suitably chosen atomic
observables and precision and efficiency is gained by dividing the atomic gas
in two or more samples which are entangled by the dispersive atom-light
interaction.Comment: 8 pages, 11 figure
Geometric phases in open tripod systems
We first consider stimulated Raman adibatic passages (STIRAP) in a closed
four-level tripod system. In this case, the adiabatic eigenstates of the system
acquire real geometric phases. When the system is open and subject to
decoherence they acquire complex geometric phases that we determine by a Monte
Carlo wave function approach. We calculate the geometric phases and the state
evolution in the closed as well as in the open system cases and describe the
deviation between these in terms of the phases acquired. When the system is
closed, the adiabatic evolution implements a Hadamard gate. The open system
implements an imperfect gate and hence has a fidelity below unity. We express
this fidelity in terms of the acquired geometric phases.Comment: 10 pages 7 figure
Strong Orientation Effects in Ionization of H by Short, Intense, High-Frequency Light Sources
We present three dimensional time-dependent calculations of ionization of
arbitrarily spatially oriented H by attosecond, intense, high-frequency
laser fields. The ionization probability shows a strong dependence on both the
internuclear distance and the relative orientation between the laser field and
the internuclear axis.Comment: 4 pages, 4 figure
Private Property Rights and Local Government Land Use Control: 42 U.S.C. § 1983 as a Remedy Against Unconstitutional Deprivations of Property
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