Improving Agriculture Students' Understanding of Global Production Systems through Distance Learning

Globalization is a fundamental force currently shaping agricultural sector throughout the world. To make sound decisions in a globalised economy, agricultural producers and agribusiness managers must have a high level of understanding of the international dimensions of their industry. To address this need, we are developing a course aimed at helping agricultural students better understand the managerial environment faced by producers worldwide. This course will provide students an opportunity to learn about agricultural production, and the context in which it occurs, by analyzing real-world farm case studies in various countries on four continents in both hemispheres of the globe. Eight case studies are being developed to exemplify the production and managerial environment in five different countries (Russia, Australia, Uruguay, Brazil, and the U.S.). Each case study will include a written description of the case, as well as a video tour of the farm and surrounding region and an interview with the farm manager. The case studies will provide the principal building blocks for the comparative farm management systems course to be taught at each of the four cooperating universities. Through the comparative farm management systems course, students will: (1) obtain a better understanding of the production agriculture sectors of the world, (2) discuss regional agricultural economic issues with instructors who are experts from each country, and (3) gain real-world problems solving experience in international settings through case study analysis. The case studies and course curriculum will be made available to other universities through a project web page and distribution of case study CD-ROMs.globalization, international, comparative farm case studies, distance learning, Teaching/Communication/Extension/Profession,

Exploring the S-Matrix of Massless Particles

We use the recently proposed generalised on-shell representation for scattering amplitudes and a consistency test to explore the space of tree-level consistent couplings in four-dimensional Minkowski spacetime. The extension of the constructible notion implied by the generalised on-shell representation, i.e. the possibility to reconstruct at tree level all the scattering amplitudes from the three-particle ones, together with the imposition of the consistency conditions at four-particle level, allow to rediscover all the known theories and their algebra structure, if any. Interestingly, this analysis seems to leave room for high-spin couplings, provided that at least the requirement of locality is weakened. We do not claim to have found tree-level consistent high-spin theories, but rather that our methods show signatures of them and very likely, with a suitable modification, they can be a good framework to perform a systematic search.Comment: 44 pages, 1 figur

Cauchy Biorthogonal Polynomials

The paper investigates the properties of certain biorthogonal polynomials appearing in a specific simultaneous Hermite-Pade' approximation scheme. Associated to any totally positive kernel and a pair of positive measures on the positive axis we define biorthogonal polynomials and prove that their zeroes are simple and positive. We then specialize the kernel to the Cauchy kernel 1/{x+y} and show that the ensuing biorthogonal polynomials solve a four-term recurrence relation, have relevant Christoffel-Darboux generalized formulae, and their zeroes are interlaced. In addition, these polynomial solve a combination of Hermite-Pade' approximation problems to a Nikishin system of order 2. The motivation arises from two distant areas; on one side, in the study of the inverse spectral problem for the peakon solution of the Degasperis-Procesi equation; on the other side, from a random matrix model involving two positive definite random Hermitian matrices. Finally, we show how to characterize these polynomials in term of a Riemann-Hilbert problem.Comment: 38 pages, partially replaces arXiv:0711.408

Multiple ionization of neon by soft X-rays at ultrahigh intensity

At the free-electron laser FLASH, multiple ionization of neon atoms was quantitatively investigated at 93.0 eV and 90.5 eV photon energy. For ion charge states up to 6+, we compare the respective absolute photoionization yields with results from a minimal model and an elaborate description. Both approaches are based on rate equations and take into acccout a Gaussian spatial intensity distribution of the laser beam. From the comparison we conclude, that photoionization up to a charge of 5+ can be described by the minimal model. For higher charges, the experimental ionization yields systematically exceed the elaborate rate based prediction.Comment: 10 pages, 3 figure

More on integrable structures of superstrings in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds

In this paper we continue the study, initiated in arXiv:1009.3498 and arXiv:1104.1793, of the classical integrability of Green-Schwarz superstrings in AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superbackgrounds whose spectrum contains non-supercoset worldsheet degrees of freedom corresponding to broken supersymmetries in the bulk. We derive an explicit expression, to all orders in the coset fermions and to second order in the non-coset fermions, which extends the supercoset Lax connection in these backgrounds with terms depending on the non-coset fermions. An important property of the obtained form of the Lax connection is that it is invariant under Z_4-transformations of the superisometry generators and the spectral parameter. This demonstrates that the contribution of the non-coset fermions does not spoil the Z_4-symmetry of the super-coset Lax connection which is of crucial importance for the application of Bethe-ansatz techniques. The expressions describing the AdS(4) x CP(3) and AdS(2) x S(2) x T(6) superstring sigma--models and their Lax connections have a very similar form. This is because their amount of target-space supersymmetries complement each other to 32=24+8, the maximal number of 10d type II supersymmetries. As a byproduct, this similarity has allowed us to obtain the form of the geometry of the complete type IIA AdS(2) x S(2) x T(6) superspace to all orders in the coset fermions and to the second order in the non-coset ones.Comment: 28 pages; v2: References adde

Intersecting branes and Supersymmetry

We consider intersecting M-brane solutions of supergravity in eleven dimensions. Supersymmetry turns out to be a powerful tool in obtaining such solutions and their generalizations.Comment: 6 pages, Latex, Presented at Supersymmetry and Quantum Field Theory, International Seminar dedicated to the memory of D. V. Volkov, Kharkov, 199