An Examination of the Productivity of Irish Agriculture in a Decoupled Policy Environment

End of project reportThe Single Farm Payment (SFP) scheme came into effect in the EU from the first of January 2005. This scheme replaced the many ‘coupled’ livestock and arable aid schemes available to farmers and was heralded as a significant move towards decoupling. This thesis explores the initial effects of this policy on total factor productivity (TFP) and its components (technical efficiency change, technical change, and scale efficiency change) in the main farming sectors in Ireland

A Comparison of Stochastic Frontier Approaches to Estimating Inefficiency and Total Factor Productivity: An Application to Irish Dairy Farming

This paper compares standard stochastic frontier models for panel data with a number of recently developed models designed to remove unobserved heterogeneity from the inefficiency component. Results are used to construct a generalised Malmquist total factor productivity (TFP) index. We conclude that the choice of approach makes little difference where the purpose of the study is to analyse aggregate trends in TFP and its components. However, where inefficiency estimates and their dispersion are of interest, attention should be paid to how the analyst’s interpretation of inefficiency relates to the underlying assumptions of the model that is used.Efficiency, panel data, total factor productivity, stochastic production frontier, ‘true’ effects models, dairy sector

Reverberation Mapping of the Accretion Discs in the Quasars 3C 273 and 1H 2106-099

The main aim of this thesis is to perform the first accretion disc reverberation mapping analysis on the AGN 3C 273 and 1H 2106-099 using the modern reverberation mapping algorithms Javelin, PyceCREAM and PyROA. This is with the intention of obtaining useful physical insights into these AGN and to compare the performance of the algorithms. Through spectral, photometric and reverberation mapping measurements we find evidence to suggest the accretion disc spectrum in 3C 273 follows a power law with a slightly shallower exponent β ∼ 1 than expected from the approximated thin disc model (β = 4/3 ). However the difference does not seem very significant and good agreement was found with the more physically meaningful unapproximated thin disc model simulated with a boundary condition at the radius of innermost stable circular orbit. We therefore conclude 3C 273 likely conforms to the thin disc model and displays the ’accretion disc size problem’ with a scale ∼ 2 − 3 larger than expected. For 1H 2106-099, we found an unexpected discontinuity in the PyROA and Javelin lag estimates which is reflected in the spectrum and which we cannot identify with any specific contamination. Investigating the possibility that the discontinuity is anomalous, we obtain corrected Javelin and PyROA lag estimates in near perfect agreement with the thin disc model without an up-scaled accretion disc. Our PyceCREAM RM results also indicate that the discontinuity is anomalous but differ from PyROA and Javelin in suggesting the accretion disc in 1H 2106-099 is up-scaled by a factor ∼ 2. A secondary aim of the thesis was to investigate how the uncertainties on lag estimates returned by the algorithms depends on the length of the observing period and cadence of the light-curve data. Analysis on two dust reverberation mapping campaigns returned results which suggest that the length of the light-curve relative to the expected lag has a more significant effect on the size of the uncertainties than the cadence relative to the lag. We then estimate the optimum light-curve length to be ∼ 10× the expected lag and the optimum cadence to be ∼ 6× smaller than the expected lag which had associated lag uncertainties of ∼ 11% and ∼ 10% respectively

Visualizing Interstellar's Wormhole

Christopher Nolan's science fiction movie Interstellar offers a variety of opportunities for students in elementary courses on general relativity theory. This paper describes such opportunities, including: (i) At the motivational level, the manner in which elementary relativity concepts underlie the wormhole visualizations seen in the movie. (ii) At the briefest computational level, instructive calculations with simple but intriguing wormhole metrics, including, e.g., constructing embedding diagrams for the three-parameter wormhole that was used by our visual effects team and Christopher Nolan in scoping out possible wormhole geometries for the movie. (iii) Combining the proper reference frame of a camera with solutions of the geodesic equation, to construct a light-ray-tracing map backward in time from a camera's local sky to a wormhole's two celestial spheres. (iv) Implementing this map, for example in Mathematica, Maple or Matlab, and using that implementation to construct images of what a camera sees when near or inside a wormhole. (v) With the student's implementation, exploring how the wormhole's three parameters influence what the camera sees---which is precisely how Christopher Nolan, using our implementation, chose the parameters for \emph{Interstellar}'s wormhole. (vi) Using the student's implementation, exploring the wormhole's Einstein ring, and particularly the peculiar motions of star images near the ring; and exploring what it looks like to travel through a wormhole.Comment: 14 pages and 13 figures. In press at American Journal of Physics. Minor revisions; primarily insertion of a new, long reference 15 at the end of Section II.

Gravitational Lensing by Spinning Black Holes in Astrophysics, and in the Movie Interstellar

Interstellar is the first Hollywood movie to attempt depicting a black hole as it would actually be seen by somebody nearby. For this we developed a code called DNGR (Double Negative Gravitational Renderer) to solve the equations for ray-bundle (light-beam) propagation through the curved spacetime of a spinning (Kerr) black hole, and to render IMAX-quality, rapidly changing images. Our ray-bundle techniques were crucial for achieving IMAX-quality smoothness without flickering. This paper has four purposes: (i) To describe DNGR for physicists and CGI practitioners . (ii) To present the equations we use, when the camera is in arbitrary motion at an arbitrary location near a Kerr black hole, for mapping light sources to camera images via elliptical ray bundles. (iii) To describe new insights, from DNGR, into gravitational lensing when the camera is near the spinning black hole, rather than far away as in almost all prior studies. (iv) To describe how the images of the black hole Gargantua and its accretion disk, in the movie \emph{Interstellar}, were generated with DNGR. There are no new astrophysical insights in this accretion-disk section of the paper, but disk novices may find it pedagogically interesting, and movie buffs may find its discussions of Interstellar interesting.Comment: 46 pages, 17 figure

Optimal Continuous-Thrust Orbit Transfers

The minimum time orbital transfer problem for spacecraft with steerable, continuous thrust of constant magnitude may be solved using Euler-Lagrange theory, which leads to the optimal control law in terms of Lagrange multipliers. However, the initial values of the Lagrange multipliers are not known from the orbital boundary conditions. Using analytical and empirical results, the optimal initial costates are modeled as functions of the problem parameters which are the initial thrust acceleration, A, and the final orbit radius, H, in canonical units. For circle to circle, coplanar orbit transfers, these approximate initial costate models lead to convergence in the shooting method for all practical values of A and H. The models also lead to convergence for a wide range of other problems, including circle to hyperbola transfers and non-coplanar transfers. To counter the extreme sensitivity to small changes in the initial costate conditions, a dynamic step limiter is introduced which improve the convergence properties

Calf scours

"Calf scours is not a single disease; it is a clinical sign associated with several diseases characterized by diarrhea. Regardless of cause, diarrhea prevents intestines from absorbing fluids. In addition, body fluids pass from the scouring calf's body into the intestines. Calves are approximately 70 percent water at birth. Scouring calves lose fluids and rapidly dehydrate. Dehydration is also associated with loss of sodium and potassium, which are essential body chemicals (electrolytes). The buildup of acidacidosis-also follows dehydration. To implement effective preventive measures, it is essential to identify infectious agents that cause scours."--First page.James G. Thorne, DVM, PhD (College of Veterinary Medicine)New 7/85/7

Estimating the spatial and temporal distribution of species richness within Sequoia and Kings Canyon National Parks.

Evidence for significant losses of species richness or biodiversity, even within protected natural areas, is mounting. Managers are increasingly being asked to monitor biodiversity, yet estimating biodiversity is often prohibitively expensive. As a cost-effective option, we estimated the spatial and temporal distribution of species richness for four taxonomic groups (birds, mammals, herpetofauna (reptiles and amphibians), and plants) within Sequoia and Kings Canyon National Parks using only existing biological studies undertaken within the Parks and the Parks' long-term wildlife observation database. We used a rarefaction approach to model species richness for the four taxonomic groups and analyzed those groups by habitat type, elevation zone, and time period. We then mapped the spatial distributions of species richness values for the four taxonomic groups, as well as total species richness, for the Parks. We also estimated changes in species richness for birds, mammals, and herpetofauna since 1980. The modeled patterns of species richness either peaked at mid elevations (mammals, plants, and total species richness) or declined consistently with increasing elevation (herpetofauna and birds). Plants reached maximum species richness values at much higher elevations than did vertebrate taxa, and non-flying mammals reached maximum species richness values at higher elevations than did birds. Alpine plant communities, including sagebrush, had higher species richness values than did subalpine plant communities located below them in elevation. These results are supported by other papers published in the scientific literature. Perhaps reflecting climate change: birds and herpetofauna displayed declines in species richness since 1980 at low and middle elevations and mammals displayed declines in species richness since 1980 at all elevations

Update of MRST parton distributions.

We discuss the latest update of the MRST parton distributions in response to the most recent data. We discuss the areas where there are hints of difficulties in the global fit, and compare to some other updated sets of parton distributions, particularly CTEQ6. We briefly discuss the issue of uncertainties associated with partons