652 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,
Economic benefits of public investment in weed management: the case of vulpia in south-eastern Australiaâs temperate pasture areas
The present paper reports an economic evaluation of the long-term benefits to Australia of research by the Cooperative Research Centre for Weed Management Systems (CRC) into the improved management of vulpia , the major annual grass weed of temperate pastures in New South Wales and Victoria. Vulpia reduces livestock production by competition with more desirable pasture species, by the production of low quality feed at critical times of the grazing cycle, and by injury to animals. A 20-year stochastic benefit-cost analysis indicated that reducing the impacts of vulpia in these pastures produced a mean net present value of # A58.3 million and a mean benefit-cost ratio of 33:1. Temperate pasture zone wool producers would capture the largest shares of these benefits, Australian consumers would gain, but wool producers in the rest of Australia would suffer welfare losses from vulpia reductions in the temperate pasture zones.Agricultural and Food Policy, Farm Management,
Sheep CRC Renewal Proposal: Economic Evaluation of the Proposed Scientific Themes
The Australian sheep industry and its associated research and development agencies have developed a proposal for the CRC for Sheep Industry Innovation. âTop-downâ and âbottomupâ procedures were used to assess the expected economic benefits from this proposal. Formal âwith-CRCâ and âwithout-CRCâ scenarios were defined for each product and each research theme. Relevant costs were similarly defined. The requested investment by the Commonwealth and the Australian sheep industry in the CRC is assessed relative to a scenario where an alternative, lower cost research program into this industry is implemented. These extra resources have a discounted value of about 518 million in present value terms, which is far in excess of the marginal investment. Thus every 15.30 to the industry in present value terms.wool, sheep meat, research and development, economic, evaluation, Australia, Agribusiness, Livestock Production/Industries, Production Economics, Research and Development/Tech Change/Emerging Technologies, Q160,
On the positive eigenvalues and eigenvectors of a non-negative matrix
The paper develops the general theory for the items in the title, assuming
that the matrix is countable and cofinal.Comment: Version 2 allows the matrix to have zero row(s) and rows with
infinitely many non-zero entries. In addition the introduction has been
rewritte
A Random Point Field related to Bose-Einstein Condensation
The random point field which describes the position distribution of the
system of ideal boson gas in a state of Bose-Einstein condensation is obtained
through the thermodynamic limit. The resulting point field is given by
convolution of two independent point fields: the so called boson process whose
generating functional is represented by inverse of the Fredholm determinant for
an operator related to the heat operator and the point field whose generating
functional is represented by a resolvent of the operator. The construction of
the latter point field in an abstract formulation is also given.Comment: 21 page
Dynamic general equilibrium analysis of improved weed management in Australia's winter cropping systems
A recent analysis indicated that the direct financial cost of weeds to Australiaâs winter grain sectorwas approximately 50m of R&D spread over five years is targeted at reducing the additional costs and reduced yields arising from weeds in various broadacre crops. Following this R&D effort, one-tenth of the losses arising from weeds is temporarily eliminated, with a diminishing benefit in succeeding years. At the national level, there is a welfare increase of $700m in discounted net present value terms. The regions with relatively high concentrations of winter crops experience small temporary macroeconomic gains.CGE modelling, dynamics, weed management, Crop Production/Industries,
Bath's law Derived from the Gutenberg-Richter law and from Aftershock Properties
The empirical Bath's law states that the average difference in magnitude
between a mainshock and its largest aftershock is 1.2, regardless of the
mainshock magnitude. Following Vere-Jones [1969] and Console et al. [2003], we
show that the origin of Bath's law is to be found in the selection procedure
used to define mainshocks and aftershocks rather than in any difference in the
mechanisms controlling the magnitude of the mainshock and of the aftershocks.
We use the ETAS model of seismicity, which provides a more realistic model of
aftershocks, based on (i) a universal Gutenberg-Richter (GR) law for all
earthquakes, and on (ii) the increase of the number of aftershocks with the
mainshock magnitude. Using numerical simulations of the ETAS model, we show
that this model is in good agreement with Bath's law in a certain range of the
model parameters.Comment: major revisions, in press in Geophys. Res. Let
Invariant theory for singular -determinants
From the irreducible decompositions' point of view, the structure of the
cyclic -module generated by the -determinant degenerates when
. In this paper, we show that
-determinant shares similar properties which the ordinary determinant
possesses. From this fact, one can define a new (relative) invariant called a
wreath determinant. Using -duality in the sense of Howe, we
obtain an expression of a wreath determinant by a certain linear combination of
the corresponding ordinary minor determinants labeled by suitable rectangular
shape tableaux. Also we study a wreath determinant analogue of the Vandermonde
determinant, and then, investigate symmetric functions such as Schur functions
in the framework of wreath determinants. Moreover, we examine coefficients
which we call -sign appeared at the linear expression of the wreath
determinant in relation with a zonal spherical function of a Young subgroup of
the symmetric group .Comment: 26 page
On the influence of time and space correlations on the next earthquake magnitude
A crucial point in the debate on feasibility of earthquake prediction is the
dependence of an earthquake magnitude from past seismicity. Indeed, whilst
clustering in time and space is widely accepted, much more questionable is the
existence of magnitude correlations. The standard approach generally assumes
that magnitudes are independent and therefore in principle unpredictable. Here
we show the existence of clustering in magnitude: earthquakes occur with higher
probability close in time, space and magnitude to previous events. More
precisely, the next earthquake tends to have a magnitude similar but smaller
than the previous one. A dynamical scaling relation between magnitude, time and
space distances reproduces the complex pattern of magnitude, spatial and
temporal correlations observed in experimental seismic catalogs.Comment: 4 Figure
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