Reducing Soil Phosphorus Buildup from Animal Manure Application

Animal manure is an excellent plant nutrient source for pastures but increasing soil P level over time is a major environmental problem (Sims et al., 1998). The increase in residual soil P is due to the difference in N-P ratio in the manure and forage crop requirements (Robinson, 1996). All the N in animal manure is normally utilised but only from 20 to 40% of the P is taken up. With moderate rates of manure application, nitrogen becomes the limiting nutrient for grasses. The objective of this study was to see if combining commercial N fertiliser with broiler litter would enhance forage yield and P uptake sufficiently to reduce residual soil P levels

IMPACT OF CFTA/NAFTA ON U.S. AND CANADIAN AGRICULTURE

CFTA/NAFTA is estimated annually to add $1,430 million of U.S. agricultural exports to Canada and$1,884 million of Canadian agricultural exports to the United States. Thus CFTA/NAFTA contributed an estimated 25 percent of the $5.8 billion of U.S. agricultural exports to Canada in 1995. Classical welfare analysis was used to estimate the implications of free trade in the dairy, poultry, sugar, and other industries that continue to be protected. In aggregate, consumers benefit from liberalization by nearly$1 billion per year in each country. Losses to Canadian producers are absolutely and relatively greater than to U.S. producers. Overall deadweight gains are positive to each country. The annual combined two-country addition to national income ($292 million) totals a present value of$5.8 billion when discounted in perpetuity at a 5 percent rate.International Relations/Trade,

Zero-frequency anomaly in quasiclassical ac transport: Memory effects in a two-dimensional metal with a long-range random potential or random magnetic field

We study the low-frequency behavior of the {\it ac} conductivity $\sigma(\omega)$ of a two-dimensional fermion gas subject to a smooth random potential (RP) or random magnetic field (RMF). We find a non-analytic $\propto|\omega|$ correction to ${\rm Re} \sigma$, which corresponds to a $1/t^2$ long-time tail in the velocity correlation function. This contribution is induced by return processes neglected in Boltzmann transport theory. The prefactor of this $|\omega|$-term is positive and proportional to $(d/l)^2$ for RP, while it is of opposite sign and proportional to $d/l$ in the weak RMF case, where $l$ is the mean free path and $d$ the disorder correlation length. This non-analytic correction also exists in the strong RMF regime, when the transport is of a percolating nature. The analytical results are supported and complemented by numerical simulations.Comment: 12 pages, RevTeX, 7 figure

The incomplete naturalist. Donald Willower on science and inquiry in educational administration

Considers Willower’s theory of inquiry and his stance on science and epistemology which is derived from Dewey’s pragmatist philosophy. Argues that Willower’s naturalism, following Dewey’s understanding, remains incomplete because Dewey did not have at his disposal the required causal neurobiological detail of human learning and cognition. Such detail has recently become available, and Dewey’s biological metaphors are now being cashed out in relation to the causal mechanisms of inquiry, with interesting consequences for Willower’s theory of inquiry. Concludes the article by exploring the notion of reflective inquiry in relation to human cognition, research methodology and organizational cognition.published_or_final_versio

Strong magnetoresistance induced by long-range disorder

We calculate the semiclassical magnetoresistivity $\rho_{xx}(B)$ of non-interacting fermions in two dimensions moving in a weak and smoothly varying random potential or random magnetic field. We demonstrate that in a broad range of magnetic fields the non-Markovian character of the transport leads to a strong positive magnetoresistance. The effect is especially pronounced in the case of a random magnetic field where $\rho_{xx}(B)$ becomes parametrically much larger than its B=0 value.Comment: REVTEX, 4 pages, 2 eps figure

Nonadiabatic scattering of a quantum particle in an inhomogenous magnetic field

We investigate the quantum effects, in particular the Landau-level quantization, in the scattering of a particle the nonadiabatic classical dynamics of which is governed by an adiabatic invariant. As a relevant example, we study the scattering of a drifting particle on a magnetic barrier in the quantum limit where the cyclotron energy is much larger than a broadening of the Landau levels induced by the nonadiabatic transitions. We find that, despite the level quantization, the exponential suppression $\exp(-2\pi d/\delta)$ (barrier width $d$, orbital shift per cyclotron revolution $\delta$) of the root-mean-square transverse displacement experienced by the particle after the scattering is the same in the quantum and the classical regime.Comment: 4 page

Professional development

Policy and practice around the world are so diverse that they afford very different opportunities (or present varied obstacles) to professional development for those working in drama and citizenship education. This chapter starts therefore from the perspective of teachers and considers the kinds of activities they can pursue to contribute to their own professional development. Dedicating one’s life to a career in politics and arts education is often bound up with one’s identity and sense of belonging, and professional development can arise from life experiences beyond the confines of formal training or accreditation. This chapter considers how meaningful professional development incorporates an affective dimension and reinforces teachers’ sense of vocation and identity. The chapter emphasises that, regardless of organisational and policy frameworks, teachers can exercise a form of situated agency over their own professional development. The chapter discusses how professional learning emerges from a range of experiences, which are subjected to critical reflection, and are often located in networks of practitioners. By addressing issues of identity, purpose, reflective inquiry and collaboration the chapter articulates a view of professional development which develops the drama and citizenship teacher as an agent of change

Dipole-dipole interaction between orthogonal dipole moments in time-dependent geometries

In two nearby atoms, the dipole-dipole interaction can couple transitions with orthogonal dipole moments. This orthogonal coupling accounts for a number of interesting effects, but strongly depends on the geometry of the setup. Here, we discuss several setups of interest where the geometry is not fixed, such as particles in a trap or gases, by averaging over different sets of geometries. Two averaging methods are compared. In the first method, it is assumed that the internal electronic evolution is much faster than the change of geometry, whereas in the second, it is vice versa. We find that the orthogonal coupling typically survives even extensive averaging over different geometries, albeit with qualitatively different results for the two averaging methods. Typically, one- and two-dimensional averaging ranges modelling, e.g., low-dimensional gases, turn out to be the most promising model systems.Comment: 11 pages, 14 figure