608 research outputs found
Managing Spent Mushroom Compost
End of Project ReportThis project addressed how to manage spent mushroom compost (SMC), an
issue of critical importance to the continued development of the Irish mushroom
industry. The most important aim of the project was to devise a feasible strategy
for the management of this material on an industry wide basis. There were two
main components of the project, which were conducted in parallel. One analysed
the structure of the mushroom industry and the logistics of handling, transporting
and processing SMC. The other studied the agronomic properties of SMC in an
effort to develop improved guidelines on the best use of SMC in crop production.
Our analysis of the SMC management problem led us to conclude that a
centralised approach should be taken when developing the solution strategy. The
model solution that was formulated is based on the establishment of centrally
located depots for SMC collection, temporary storage and possible processing.
This approach facilitates a variety of environmentally acceptable SMC end uses
ranging from land application to incineration.
We examined a variety of possible end uses for SMC, including its use as an
alternative fuel. In the immediate future, we believe the predominant end use for
SMC will be as an organic manure for field crop production and as a soil
conditioner in the landscaping industry. Uses of this type are in line with both
Irish and EU legislation regarding waste management. Our analysis suggests that tillage and horticulture offer the best promise for realising the beneficial
properties of SMC.
We have tested SMC on field crops such as winter and spring wheat and
potatoes and on glasshouse crops such as tomatoes. These experiments have
shown that SMC increases soil organic matter and improves soil structure.
SMC is a very effective source of K and P and also provides trace elements. It
makes a contribution to N nutrition but most of the N does not become available
to the crop in the first year. For best results therefore, supplementary N must be
applied.
Overall, our results indicate that SMC can be used with beneficial effects in field
crop production.
The mushroom industry should move forward with establishing centralised SMC
handling facilities to enable the efficient collection, temporary storage, further
processing and transportation of SMC to end users.
An education and awareness campaign should be conducted amongst farmers,
in areas removed from mushroom production, to introduce them to the benefits of
SMC and ways to effectively utilise this material.Department of Agriculture, Food and the MarineEuropean Union Structural Funds (EAGGF
Coupled KdV equations of Hirota-Satsuma type
It is shown that the system of two coupled Korteweg-de Vries equations passes
the Painlev\'e test for integrability in nine distinct cases of its
coefficients. The integrability of eight cases is verified by direct
construction of Lax pairs, whereas for one case it remains unknown
Understanding the Global Problem of Drug Addiction is a Challenge for IDARS Scientists
IDARS is an acronym for the International Drug Abuse Research Society. Apart from our scientific and educational purposes, we communicate information to the general and scientific community about substance abuse and addiction science and treatment potential. Members of IDARS are research scientists and clinicians from around the world, with scheduled meetings across the globe. IDARS is developing a vibrant and exciting international mechanism not only for scientific interactions in the domain of addiction between countries but also ultimately as a resource for informing public policy across nations. Nonetheless, a lot more research needs to be done to better understand the neurobiological basis of drug addiction â A challenge for IDARS scientists
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Determinants of species richness in the Park Grass experiment
The Park Grass Experiment at Rothamsted in southeast England was started in 1856, making it the longest-running experiment in plant ecology anywhere in the world. Experimental inputs include a range of fertilizers (nitrogen, phosphorus, potassium, and organic manures) applied annually, with lime applied occasionally, and these have led to an increase in biomass and, where nitrogen was applied in the form of ammonium sulfate, to substantial decreases in soil pH. The number of species per plot varies from three to 44 per 200 m2, affording a unique opportunity to study the determinants of plant species richness and to estimate the effect sizes attributable to different factors. The response of species richness to biomass depends on the amount and type of nitrogen applied; richness declined monotonically with increasing biomass on plots receiving no nitrogen or receiving nitrogen in the form of sodium nitrate, but there was no relationship between species richness and biomass on plots acidified by ammonium sulfate application. The response to lime also depended on the type of nitrogen applied; there was no relationship between lime treatment and species richness, except in plots receiving nitrogen in the form of ammonium sulfate, where species richness increased sharply with increasing soil pH. The addition of phosphorus reduced species richness, and application of potassium along with phosphorus reduced species richness further, but the biggest negative effects were when nitrogen and phosphorus were applied together. The analysis demonstrates how multiple factors contribute to the observed diversity patterns and how environmental regulation of species pools can operate at the same spatial and temporal scale as biomass effects
Damped Bogoliubov excitations of a condensate interacting with a static thermal cloud
We calculate the damping of condensate collective excitations at finite
temperatures arising from the lack of equilibrium between the condensate and
thermal atoms. We neglect the non-condensate dynamics by fixing the thermal
cloud in static equilibrium. We derive a set of generalized Bogoliubov
equations for finite temperatures that contain an explicit damping term due to
collisional exchange of atoms between the two components. We have numerically
solved these Bogoliubov equations to obtain the temperature dependence of the
damping of the condensate modes in a harmonic trap. We compare these results
with our recent work based on the Thomas-Fermi approximation.Comment: 9 pages, 3 figures included. Submitted to PR
On the practicality of time-optimal two-qubit Hamiltonian simulation
What is the time-optimal way of using a set of control Hamiltonians to obtain
a desired interaction? Vidal, Hammerer and Cirac [Phys. Rev. Lett. 88 (2002)
237902] have obtained a set of powerful results characterizing the time-optimal
simulation of a two-qubit quantum gate using a fixed interaction Hamiltonian
and fast local control over the individual qubits. How practically useful are
these results? We prove that there are two-qubit Hamiltonians such that
time-optimal simulation requires infinitely many steps of evolution, each
infinitesimally small, and thus is physically impractical. A procedure is given
to determine which two-qubit Hamiltonians have this property, and we show that
almost all Hamiltonians do. Finally, we determine some bounds on the penalty
that must be paid in the simulation time if the number of steps is fixed at a
finite number, and show that the cost in simulation time is not too great.Comment: 9 pages, 2 figure
Thermodynamics of an interacting trapped Bose-Einstein gas in the classical field approximation
We present a convenient technique describing the condensate in dynamical
equilibrium with the thermal cloud, at temperatures close to the critical one.
We show that the whole isolated system may be viewed as a single classical
field undergoing nonlinear dynamics leading to a steady state. In our procedure
it is the observation process and the finite detection time that allow for
splitting the system into the condensate and the thermal cloud.Comment: 4 pages, 4 eps figures, final versio
Unitary Gate Synthesis for Continuous Variable Systems
We investigate the synthesis of continuous-variable two-mode unitary gates in
the setting where two modes A and B are coupled by a fixed quadratic
Hamiltonian H. The gate synthesis consists of a sequence of evolutions governed
by Hamiltonian H interspaced by local phase shifts applied to A and B. We
concentrate on protocols that require the minimum necessary number of steps and
we show how to implement the beam splitter and the two-mode squeezer in just
three steps. Particular attention is paid to the Hamiltonian x_A p_B that
describes the effective off-resonant interaction of light with the collective
atomic spin.Comment: 7 pages, minor text modifications, references adde
Critical number of atoms for attractive Bose-Einstein condensates with cylindrically symmetrical traps
We calculated, within the Gross-Pitaevskii formalism, the critical number of
atoms for Bose-Einstein condensates with two-body attractive interactions in
cylindrical traps with different frequency ratios. In particular, by using the
trap geometries considered by the JILA group [Phys. Rev. Lett. 86, 4211
(2001)], we show that the theoretical maximum critical numbers are given
approximately by . Our results also show that, by
exchanging the frequencies and , the geometry with
favors the condensation of larger number of particles.
We also simulate the time evolution of the condensate when changing the ground
state from to using a 200ms ramp. A conjecture on higher order
nonlinear effects is also added in our analysis with an experimental proposal
to determine its signal and strength.Comment: (4 pages, 2 figures) To appear in Physical Review
Ideal Gases in Time-Dependent Traps
We investigate theoretically the properties of an ideal trapped gas in a
time-dependent harmonic potential. Using a scaling formalism, we are able to
present simple analytical results for two important classes of experiments:
free expansion of the gas upon release of the trap; and the response of the gas
to a harmonic modulation of the trapping potential is investigated. We present
specific results relevant to current experiments on trapped Fermions.Comment: 5 pages, 3 eps figure
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