3,265 research outputs found
An Economic Evaluation of Research into the Improved Management of the Annual Grass Weed Vulpia in Temperate Pastures in South-Eastern Australia
NSW Agriculture has a history of research investment in managing weed problems in the temperate pasture areas. One focus of that research has been on the development of improved management practices for the major annual grass weed vulpia. Recent surveys have found that weeds comprised up to 80% of pasture biomass in some temperate areas and that typical vulpia contents are between 30 and 40% of pasture biomass. Temperate pasture degradation is recognised as being a major contributor to the wider environmental problems of soil erosion, salinity and acidity. This evaluation related to a project (1996-2002) that focussed on the vulpia problem in the New South Wales temperate pasture areas. The benefits of that research were measured as the difference in the economic returns from the project (the with-research scenario) and those that would have resulted if the project had not been initiated (the without-research scenario). The results indicated high levels of economic benefits from the vulpia project. The annual net project benefit had a mean value of 196.9 million and a mean BCR of 22.2. These results demonstrate that research by NSW Agriculture into the improved management of vulpia has the potential to generate substantial long-term economic benefits. Other socio-economic aspects of the results showed that wool producers outside the New South Wales temperate areas lost economic surplus (from a mean -47.8 million) because they were unable to adopt the cost-reducing technology and faced a reduced wool price. All wool consumers gained from vulpia research because of expanded wool production and lower wool prices. Improved vulpia management is also considered to produce important environmental benefits by encouraging a greater use of deep-rooted perennial grasses and the beneficial effects of these on mitigating soil problems and reducing water table discharges.benefit cost analysis, research evaluation, annual grass weeds, vulpia, Research and Development/Tech Change/Emerging Technologies, Q160,
A Bootstrapping Approach for Generating Maximally Path-Entangled Photon States
We propose a bootstrapping approach to generation of maximally path-entangled
states of photons, so called ``NOON states''. Strong atom-light interaction of
cavity QED can be employed to generate NOON states with about 100 photons;
which can then be used to boost the existing experimental Kerr nonlinearities
based on quantum coherence effects to facilitate NOON generation with
arbitrarily large number of photons all within the current experimental state
of the art technology. We also offer an alternative scheme that uses an
atom-cavity dispersive interaction to obtain sufficiently high
Kerr-nonlinearity necessary for arbitrary NOON generation
Quantum reflection of atoms from a solid surface at normal incidence
We observed quantum reflection of ultracold atoms from the attractive
potential of a solid surface. Extremely dilute Bose-Einstein condensates of
^{23}Na, with peak density 10^{11}-10^{12}atoms/cm^3, confined in a weak
gravito-magnetic trap were normally incident on a silicon surface. Reflection
probabilities of up to 20 % were observed for incident velocities of 1-8 mm/s.
The velocity dependence agrees qualitatively with the prediction for quantum
reflection from the attractive Casimir-Polder potential. Atoms confined in a
harmonic trap divided in half by a solid surface exhibited extended lifetime
due to quantum reflection from the surface, implying a reflection probability
above 50 %.Comment: To appear in Phys. Rev. Lett. (December 2004)5 pages, 4 figure
On Approximation of the Eigenvalues of Perturbed Periodic Schrodinger Operators
This paper addresses the problem of computing the eigenvalues lying in the
gaps of the essential spectrum of a periodic Schrodinger operator perturbed by
a fast decreasing potential. We use a recently developed technique, the so
called quadratic projection method, in order to achieve convergence free from
spectral pollution. We describe the theoretical foundations of the method in
detail, and illustrate its effectiveness by several examples.Comment: 17 pages, 2 tables and 2 figure
Optical interface created by laser-cooled atoms trapped in the evanescent field surrounding an optical nanofiber
Trapping and optically interfacing laser-cooled neutral atoms is an essential
requirement for their use in advanced quantum technologies. Here we
simultaneously realize both of these tasks with cesium atoms interacting with a
multi-color evanescent field surrounding an optical nanofiber. The atoms are
localized in a one-dimensional optical lattice about 200 nm above the nanofiber
surface and can be efficiently interrogated with a resonant light field sent
through the nanofiber. Our technique opens the route towards the direct
integration of laser-cooled atomic ensembles within fiber networks, an
important prerequisite for large scale quantum communication schemes. Moreover,
it is ideally suited to the realization of hybrid quantum systems that combine
atoms with, e.g., solid state quantum devices
“I do not consent”: political legitimacy, misinformation, and the compliance challenge in Australia’s Covid-19 policy response
This paper examines the relationship between policy compliance, the emergence of alternate epistemes and authorities in online spaces, and the decline of trust and legitimacy in democratic institutions. Drawing on insights from public policy, regulation theory, and political theory, the paper critically engages with scholarship on “policy-takers” to illuminate the tensions of compliance and legitimacy in liberal states. It proposes a compliance–legitimacy matrix that identifies the features of policy compliance—including consent, legitimacy, expertise, and trust—and their relationship to the disaggregation of policy knowledge. The article applies this framework to a case study of social media posts that respond to policy information during the management of the Covid-19 pandemic in Australia. Through analysis of these posts, the study reveals the distrust in “the science” and experts advocated by government and the calls from skeptic groups for noncompliance with public health measures. The paper argues that public policy faces an epistemic crisis of public confidence, with significant downstream consequences for compliance with public policy initiatives that has been brought on both by the failures of states to cultivate trust in science and the government. The compliance–legitimacy matrix offers a useful tool for policymakers to anticipate and address objections from policy-takers and to preempt and diffuse their fears.Melissa-Ellen Dowling and Tim Legran
Simulations of atomic trajectories near a dielectric surface
We present a semiclassical model of an atom moving in the evanescent field of
a microtoroidal resonator. Atoms falling through whispering-gallery modes can
achieve strong, coherent coupling with the cavity at distances of approximately
100 nanometers from the surface; in this regime, surface-induced Casmir-Polder
level shifts become significant for atomic motion and detection. Atomic transit
events detected in recent experiments are analyzed with our simulation, which
is extended to consider atom trapping in the evanescent field of a microtoroid.Comment: 29 pages, 10 figure
III. Introgressive mtDNA Transfer in Hybrid Lake Suckers (Teleostei, Catostomidae) in Western United States
Hybridization and introgression permitted gene transfer from Catostomus to Lake Suckers in modern and MioPliocene lakes of Western United States. Lake Sucker genera, Chasmistes, Deltistes, and Xyrauchen, were sympatric with species of Catostomus (riverine suckers) in four large modern lakes and many fossil lakes in the Great Basin, Klamath, and Columbia-Snake drainages, and also in the Colorado River. Unique morphological traits in Lake Suckers originally included distinctive lips, jaw bones, neurocranial bones, and gill-rakers, but many of the original traits were lost or partly lost, and the remaining phenotypes are mixtures of intermediate morphological traits grading toward local species of Catostomus.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145184/1/MP 204no3.pdfDescription of MP 204no3.pdf : Main Articl
Correspondences and Quantum Description of Aharonov-Bohm and Aharonov-Casher Effects
We establish systematic consolidation of the Aharonov-Bohm and
Aharonov-Casher effects including their scalar counterparts. Their formal
correspondences in acquiring topological phases are revealed on the basis of
the gauge symmetry in non-simply connected spaces and the adiabatic condition
for the state of magnetic dipoles. In addition, investigation of basic two-body
interactions between an electric charge and a magnetic dipole clarifies their
appropriate relative motions and discloses physical interrelations between the
effects. Based on the two-body interaction, we also construct an exact
microscopic description of the Aharonov-Bohm effect, where all the elements are
treated on equal footing, i.e., magnetic dipoles are described
quantum-mechanically and electromagnetic fields are quantized. This microscopic
analysis not only confirms the conventional (semiclassical) results and the
topological nature but also allows one to explore the fluctuation effects due
to the precession of the magnetic dipoles with the adiabatic condition relaxed
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