1,236 research outputs found
DEVELOPMENT POLICIES IN SOUTHERN ITALY BETWEEN GOVERNMENT AND GOVERNANCE
The paper has analysed outputs generated by the development policies implemented in last decades in the South of Italy, starting from the Extraordinary Intervention (since 1950, until 1992) to the European cohesion policy (since 1996). The first one was a high-centralized development policy. Differently, the European cohesion policy is based on multilevel governance, and follows a bottom-up approach oriented to stimulate local stakeholders’ participation. The analysis, exposed in previous paragraphs, has described these two different policy experiences, the related effects on local development and on convergence between North and South of Italy and among European regions. The paper has tried to answer to a fundamental question: what factors have negatively affected the implementation of these policies, generating unexpected effects
Occlusion points identification algorithm
In this paper a very simple and efficient algorithm is proposed, to calculate the invisible regions of a
scene, or shadowed side of a body, when it is observed from a pre-set point. This is done by applying a
deterministic numerical procedure to the portion of scene in the field of view, after having been projected
in the observer reference frame. The great advantage of this approach is its generality and suitability for
a wide number of applications. They span from real time renderings, to the simulation of different types
of light sources, such as diffused or collimated, or simply to calculate the effective visible surface for a
camera mounted on board of an aircraft, in order to optimize its trajectory if remote sensing or aerial
mapping task should be carried out. Optimizing the trajectory, by minimizing at any time the occluded
surface, is also a powerful solution for a search and rescue mission, because a wider area in a shorter time
can be observed, particularly in situations where the time is a critical parameter, such as, during a forest
fire or in case of avalanches. For its simplicity of implementation, the algorithm is suitable for real time
applications, providing an extremely accurate solution in a fraction of a millisecond. In this paper, the
algorithm has been tested by calculating the occluded regions of a very complex mountainous scenario,
seen from a gimbal-camera mounted on board of a flying platform
Le reti di impresa nella politica industriale. I contratti di rete e i contratti di sviluppo.
Le reti di impresa si sono affermate come un modello organizzativo e competitivo compiutamente alternativo sia al mercato sia alla gerarchia, superando una visione teorica che tendeva a confinarle come modello imperfetto o immaturo del capitalismo. I contributi raccolti nel volume, frutto di un lavoro di ricerca multidisciplinare, analizzano i presupposti teorici delle reti e si concentrano su due principali strumenti di politica industriale – i contratti di rete e i contratti di sviluppo – avvalendosi dei risultati emersi dai percorsi di attuazione di casi selezionati in quattro regioni italiane
Optimization of graphene-based materials outperforming host epoxy matrices
The degree of graphite exfoliation and edge-carboxylated layers can be controlled and balanced to design lightweight materials characterized by both low electrical percolation thresholds (EPT) and improved mechanical properties. So far, this challenging task has been undoubtedly very hard to achieve. The results presented in this paper highlight the effect of exfoliation degree and the role of edge-carboxylated graphite layers to give self-assembled structures embedded in the polymeric matrix. Graphene layers inside the matrix may serve as building blocks of complex systems that could outperform the host matrix. Improvements in electrical percolation and mechanical performance have been obtained by a synergic effect due to finely balancing the degree of exfoliation and the chemistry of graphene edges which favors the interfacial interaction between polymer and carbon layers. In particular, for epoxy-based resins including two partially exfoliated graphite samples, differing essentially in the content of carboxylated groups, the percolation threshold reduces from 3 wt% down to 0.3 wt%, as the carboxylated group content increases up to 10 wt%. Edge-carboxylated nanosheets also increase the nanofiller/epoxy matrix interaction, determining a relevant reinforcement in the elastic modulus
Adolescent sleep and the foundations of prefrontal cortical development and dysfunction
Modern life poses many threats to good-quality sleep, challenging brain health across the lifespan. Curtailed or fragmented sleep may be particularly damaging during adolescence, when sleep disruption by delayed chro-notypes and societal pressures coincides with our brains preparing for adult life via intense refinement of neural connectivity. These vulnerabilities converge on the prefrontal cortex, one of the last brain regions to mature and a central hub of the limbic-cortical circuits underpinning decision-making, reward processing, social interactions and emotion. Even subtle disruption of prefrontal cortical development during adolescence may therefore have enduring impact. In this review, we integrate synaptic and circuit mechanisms, glial biology, sleep neurophys-iology and epidemiology, to frame a hypothesis highlighting the implications of adolescent sleep disruption for the neural circuitry of the prefrontal cortex. Convergent evidence underscores the importance of acknowledging, quantifying and optimizing adolescent sleep's contributions to normative brain development and to lifelong mental health
Eroding market stability by proliferation of financial instruments
We contrast Arbitrage Pricing Theory (APT), the theoretical basis for the
development of financial instruments, with a dynamical picture of an
interacting market, in a simple setting. The proliferation of financial
instruments apparently provides more means for risk diversification, making the
market more efficient and complete. In the simple market of interacting traders
discussed here, the proliferation of financial instruments erodes systemic
stability and it drives the market to a critical state characterized by large
susceptibility, strong fluctuations and enhanced correlations among risks. This
suggests that the hypothesis of APT may not be compatible with a stable market
dynamics. In this perspective, market stability acquires the properties of a
common good, which suggests that appropriate measures should be introduced in
derivative markets, to preserve stability.Comment: 26 pages, 8 figure
Compact smallest eigenvalue expressions in Wishart-Laguerre ensembles with or without fixed-trace
The degree of entanglement of random pure states in bipartite quantum systems
can be estimated from the distribution of the extreme Schmidt eigenvalues. For
a bipartition of size M\geq N, these are distributed according to a
Wishart-Laguerre ensemble (WL) of random matrices of size N x M, with a
fixed-trace constraint. We first compute the distribution and moments of the
smallest eigenvalue in the fixed trace orthogonal WL ensemble for arbitrary
M\geq N. Our method is based on a Laplace inversion of the recursive results
for the corresponding orthogonal WL ensemble by Edelman. Explicit examples are
given for fixed N and M, generalizing and simplifying earlier results. In the
microscopic large-N limit with M-N fixed, the orthogonal and unitary WL
distributions exhibit universality after a suitable rescaling and are therefore
independent of the constraint. We prove that very recent results given in terms
of hypergeometric functions of matrix argument are equivalent to more explicit
expressions in terms of a Pfaffian or determinant of Bessel functions. While
the latter were mostly known from the random matrix literature on the QCD Dirac
operator spectrum, we also derive some new results in the orthogonal symmetry
class.Comment: 25 pag., 4 fig - minor changes, typos fixed. To appear in JSTA
Universal correlations and power-law tails in financial covariance matrices
Signatures of universality are detected by comparing individual eigenvalue distributions and level spacings from financial covariance matrices to random matrix predictions. A chopping procedure is devised in order to produce a statistical ensemble of asset-price covariances from a single instance of financial data sets. Local results for the smallest eigenvalue and individual spacings are very stable upon reshuffling the time windows and assets. They are in good agreement with the universal Tracy-Widom distribution and Wigner surmise, respectively.
This suggests a strong degree of robustness especially in the low-lying sector of the spectra, most relevant for portfolio selections.
Conversely, the global spectral density of a single covariance matrix as well as the average over all unfolded nearest-neighbour spacing distributions deviate from standard Gaussian random matrix predictions. The data are in fair agreement with a recently introduced generalised random matrix model, with correlations showing a power-law decay
Statistical distribution of quantum entanglement for a random bipartite state
We compute analytically the statistics of the Renyi and von Neumann entropies
(standard measures of entanglement), for a random pure state in a large
bipartite quantum system. The full probability distribution is computed by
first mapping the problem to a random matrix model and then using a Coulomb gas
method. We identify three different regimes in the entropy distribution, which
correspond to two phase transitions in the associated Coulomb gas. The two
critical points correspond to sudden changes in the shape of the Coulomb charge
density: the appearance of an integrable singularity at the origin for the
first critical point, and the detachement of the rightmost charge (largest
eigenvalue) from the sea of the other charges at the second critical point.
Analytical results are verified by Monte Carlo numerical simulations. A short
account of some of these results appeared recently in Phys. Rev. Lett. {\bf
104}, 110501 (2010).Comment: 7 figure
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