Accelerating innovation with prize rewards: History and typology of technology prizes and a new contest design for innovation in African agriculture

"This paper describes how governments and philanthropic donors could drive innovation through a new kind of technology contest. We begin by reviewing the history of technology prizes, which operate alongside private intellectual property rights and public R&D to accelerate and guide productivity growth towards otherwise-neglected social goals. Proportional “prize rewards” would modify the traditional winner-take-all approach, by dividing available funds among multiple winners in proportion to measured achievement. This approach would provide a royalty-like payment for incremental success. The paper provides concludes with a specific example for how such prizes could be implemented to reward and help scale up successful innovations in African agriculture, through payments to innovators in proportion to the value created by their technologies after adoption. " from authors' abstractProductivity growth, Technology adoption, intellectual property, Agricultural R&D, Innovation,

Farmland Allocation along the Rural-Urban Gradient: The Impacts of Urbanization and Urban Sprawl

In the vicinity of a city, farmers are confronted with increasing agricultural land prices and rents along the rural-urban gradient, but they concurrently enjoy the advantages associated with proximity to a larger and wealthier consumer base. We hypothesize that farmers transition from low-value, land-intensive \traditional" crops to high-value, labor-intensive \specialized" crops on parcels located closer to urban centers. Once returns to development of a parcel exceed the profits associated with farming, exurban farmers may sell their land for conversion to urban use. Urban pressure in the rural-urban fringe intensifies as cities expand. We differentiate between a gradual process of urban growth (or urbanization) and urban sprawl. Utilizing farmland fragmentation measures as indicators of sprawl, we hypothesize that urban sprawl burdens \traditional" farms to the extent that they accelerate the transition to specialized crops or convert farmland to urban use. We use crop-specific land cover data at the level of grid cells and a state-of-the-art system of spatially correlated simultaneous equations with data for the metropolitan area of Indianapolis, IN and its immediate hinterland. Our initial empirical results corroborate that accelerated urban development around Indianapolis in the 1990s is associated with land uses characterized by fewer field crops and more idle land.land use, urban sprawl, agriculture, specialized crops, spatial econometrics, Community/Rural/Urban Development, Land Economics/Use, C31, O13, Q15, R14,

Stepwise introduction of model complexity in a generalized master equation approach to time-dependent transport

We demonstrate that with a stepwise introduction of complexity to a model of an electron system embedded in a photonic cavity and a carefully controlled stepwise truncation of the ensuing many-body space it is possible to describe the time-dependent transport of electrons through the system with a non-Markovian generalized quantum master equation. We show how this approach retains effects of an external magnetic field and the geometry of an anisotropic electronic system. The Coulomb interaction between the electrons and the full electromagnetic coupling between the electrons and the photons are treated in a non-perturbative way using "exact numerical diagonalization".Comment: RevTeX, 14 pages with included eps figures, replaced to mend scaling in figure axes for time "t" and current "J

Application of nonlinear deformation algebra to a physical system with P\"oschl-Teller potential

We comment on a recent paper by Chen, Liu, and Ge (J. Phys. A: Math. Gen. 31 (1998) 6473), wherein a nonlinear deformation of su(1,1) involving two deforming functions is realized in the exactly solvable quantum-mechanical problem with P\" oschl-Teller potential, and is used to derive the well-known su(1,1) spectrum-generating algebra of this problem. We show that one of the defining relations of the nonlinear algebra, presented by the authors, is only valid in the limiting case of an infinite square well, and we determine the correct relation in the general case. We also use it to establish the correct link with su(1,1), as well as to provide an algebraic derivation of the eigenfunction normalization constant.Comment: 9 pages, LaTeX, no figure

Photon mediated interaction between distant quantum dot circuits

Engineering the interaction between light and matter is an important goal in the emerging field of quantum opto-electronics. Thanks to the use of cavity quantum electrodynamics architectures, one can envision a fully hybrid multiplexing of quantum conductors. Here, we use such an architecture to couple two quantum dot circuits . Our quantum dots are separated by 200 times their own size, with no direct tunnel and electrostatic couplings between them. We demonstrate their interaction, mediated by the cavity photons. This could be used to scale up quantum bit architectures based on quantum dot circuits or simulate on-chip phonon-mediated interactions between strongly correlated electrons

Nonlinear deformed su(2) algebras involving two deforming functions

The most common nonlinear deformations of the su(2) Lie algebra, introduced by Polychronakos and Ro\v cek, involve a single arbitrary function of J_0 and include the quantum algebra su_q(2) as a special case. In the present contribution, less common nonlinear deformations of su(2), introduced by Delbecq and Quesne and involving two deforming functions of J_0, are reviewed. Such algebras include Witten's quadratic deformation of su(2) as a special case. Contrary to the former deformations, for which the spectrum of J_0 is linear as for su(2), the latter give rise to exponential spectra, a property that has aroused much interest in connection with some physical problems. Another interesting algebra of this type, denoted by ${\cal A}^+_q(1)$, has two series of (N+1)-dimensional unitary irreducible representations, where N=0, 1, 2, .... To allow the coupling of any two such representations, a generalization of the standard Hopf axioms is proposed. The resulting algebraic structure, referred to as a two-colour quasitriangular Hopf algebra, is described.Comment: 8 pages, LaTeX, no figures, submitted to Proc. 5th Int. Coll. ``Quantum Groups and Integrable Systems'', Prague, 20-22 June 1996 (to be published in Czech. J. Phys.

Full control of quadruple quantum dot circuit charge states in the single electron regime

We report the realization of an array of four tunnel coupled quantum dots in the single electron regime, which is the first required step toward a scalable solid state spin qubit architecture. We achieve an efficient tunability of the system but also find out that the conditions to realize spin blockade readout are not as straightforwardly obtained as for double and triple quantum dot circuits. We use a simple capacitive model of the series quadruple quantum dots circuit to investigate its complex charge state diagrams and are able to find the most suitable configurations for future Pauli spin blockade measurements. We then experimentally realize the corresponding charge states with a good agreement to our model.Comment: 4 pages, 3 figure

Going West in the European Union: Migration and EU-Enlargement

Citizens of EU Member States have the fundamental right of free movement within the EU Union, and of freely choosing where to live and work within the EU. However, this right was temporarily constrained for citizens of the new Member States following the enlargement of the EU from 15 to 27 Member States. The severity of restrictions for newcomers varied substantially across the 15 old Member States. This paper analyzes whether the variations in entry restrictions influenced the distribution of migrants across the EU-15 states. To assess the effects of entry restrictions, it models and compares the distribution of migrants across the EU-15 countries prior to the enlargement with that after the enlargement. The analysis uses aggregate data on migrant stocks and migrant flows from the new Member States to the EU-15 states. The results suggest that the migration policies only had a very weak effect and did not create a new migration regime. The destination preferences of past emigrants from the East are by and large replicated by migrants who came after their home countries became members of the EU