Uniform Steiner bundles

In this work we study $k$-type uniform Steiner bundles, being $k$ the lowest degree of the splitting. We prove sharp upper and lower bounds for the rank in the case $k=1$ and moreover we give families of examples for every allowed possible rank and explain which relation exists between the families. After dealing with the case $k$ in general, we conjecture that every $k$-type uniform Steiner bundle is obtained through the proposed construction technique.Comment: 23 pages, to appear at Annales de l'Institut Fourie

Political participation of unemployed youth: the moderator effect of associational membership

<span class="abs_content">This article discusses how associational membership can compensate for that lack of opportunities and motivation necessary for political participation that unemployment usually provokes. We investigate such a moderator effect of associational membership by means of a CATI survey of young people realized in two different cities: Turin in Italy and Kielce in Poland. The survey was part of a larger research on youth unemployment funded by the EU FP7 program (Younex). We propose an exploratory analysis allowing us to assess at a low level of abstraction and through a local level comparison, how far associational membership performs even across different contexts as a promoter of political engagement of a specific group of young, deprived, individuals.</span><br /

The Direction of Technical Change in Capital-Resource Economies

We analyze a multi-sector growth model with directed technical change where man-made capital and exhaustible resources are essen- tial for production. The relative profitability of factor-specific inno- vations endogenously determines whether technical progress will be capital- or resource-augmenting. We show that convergence to bal- anced growth implies zero capital-augmenting innovations: in the long run, the economy exhibits purely resource-augmenting technical change. This result provides sound microfoundations for the broad class of models of exogenous/endogenous growth where resource-aug- menting progress is required to sustain consumption in the long run, contradicting the view that these models are conceptually biased in favor of sustainability.Endogenous Growth, Directed Technical Change, Exhaustible Resources, Sustainability

The Direction of Technical Change in Capital-Resource Economies

We analyze a multi-sector growth model with directed technical change where man-made capital and exhaustible resources are essential for production. The relative profitability of factor-specific innovations endogenously determines whether technical progress will be capital- or resource-augmenting. We show that convergence to balanced growth implies zero capital-augmenting innovations: in the long run, the economy exhibits purely resource-augmenting technical change. This result provides sound microfoundations for the broad class of models of exogenous/endogenous growth where resource-augmenting progress is required to sustain consumption in the long run, contradicting the view that these models are conceptually biased in favor of sustainability.Endogenous Growth; Directed Technical Change; Exhaustible Resources; Sustainability

Analytic formulas for the rapid evaluation of the orbit response matrix and chromatic functions from lattice parameters in circular accelerators

Measurements and analysis of orbit response matrix have been providing for decades a formidable tool in the detection of linear lattice imperfections and their correction. Basically all storage- ring-based synchrotron light sources across the world make routinely use of this technique in their daily operation, reaching in some cases a correction of linear optics down to 1% beta beating and 0.1% coupling. During the design phase of a new storage ring it is also applied in simulations for the evaluation of magnetic and mechanical tolerances. However, this technique is known for its intrinsic slowness compared to other methods based on turn-by-turn beam position data, both in the measurement and in the data analysis. In this paper analytic formulas are derived and discussed that shall greatly speed up this second part. The mathematical formalism based on the Lie algebra and the resonance driving terms is extended to the off-momentum regime and explicit analytic formulas for the evaluation of chromatic functions from lattice parameters are also derived. The robustness of these formulas, which are linear in the magnet strengths, is tested with different lattice configurations

Is Torsion a Fundamental Physical Field?

The local Lorentz group is introduced in flat space-time, where the resulting Dirac and Yang-Mills equations are found, and then generalized to curved space-time: if matter is neglected, the Lorentz connection is identified with the contortion field, while, if matter is taken into account, both the Lorentz connection and the spinor axial current are illustrated to contribute to the torsion of space-time.Comment: 3 pages, proceedings of the XI Marcel Grossmann meeting on Relativistic Astrophysics, July 23-29, 2006, Berli