Aneides hardii

Number of pages=23Geological SciencesIntegrative Biolog

Reformas laborales de mercado y desempleo: enseñanzas de la experiencia de los países de la OCDE

(Disponible en idioma inglés únicamente) El mercado laboral de la OCDE ha experimentado cambios importantes en las últimas dos décadas. El más evidente de esos cambios ha sido el aumento del número de personas en busca de empleo. En 1997 hubo más de 35 millones de personas desempleadas en la zona de la OCDE en total; alrededor de seis millones más que a mediados de los 80 y casi 25 millones más que a comienzos de los 70. Estas cifras ocultan profundas diferencias de un país a otro. En los principales países europeos, el desempleo ha aumentado considerablemente en las últimas dos décadas y en algunos de ellos, incluidos Italia, España y Francia, incrementos que en un principio fueron cíclicos han tendido a hacerse estructurales con el tiempo.

Associative memory of phase-coded spatiotemporal patterns in leaky Integrate and Fire networks

We study the collective dynamics of a Leaky Integrate and Fire network in which precise relative phase relationship of spikes among neurons are stored, as attractors of the dynamics, and selectively replayed at differentctime scales. Using an STDP-based learning process, we store in the connectivity several phase-coded spike patterns, and we find that, depending on the excitability of the network, different working regimes are possible, with transient or persistent replay activity induced by a brief signal. We introduce an order parameter to evaluate the similarity between stored and recalled phase-coded pattern, and measure the storage capacity. Modulation of spiking thresholds during replay changes the frequency of the collective oscillation or the number of spikes per cycle, keeping preserved the phases relationship. This allows a coding scheme in which phase, rate and frequency are dissociable. Robustness with respect to noise and heterogeneity of neurons parameters is studied, showing that, since dynamics is a retrieval process, neurons preserve stablecprecise phase relationship among units, keeping a unique frequency of oscillation, even in noisy conditions and with heterogeneity of internal parameters of the units

Neural Avalanches at the Critical Point between Replay and Non-Replay of Spatiotemporal Patterns

We model spontaneous cortical activity with a network of coupled spiking units, in which multiple spatio-temporal patterns are stored as dynamical attractors. We introduce an order parameter, which measures the overlap (similarity) between the activity of the network and the stored patterns. We find that, depending on the excitability of the network, different working regimes are possible. For high excitability, the dynamical attractors are stable, and a collective activity that replays one of the stored patterns emerges spontaneously, while for low excitability, no replay is induced. Between these two regimes, there is a critical region in which the dynamical attractors are unstable, and intermittent short replays are induced by noise. At the critical spiking threshold, the order parameter goes from zero to one, and its fluctuations are maximized, as expected for a phase transition (and as observed in recent experimental results in the brain). Notably, in this critical region, the avalanche size and duration distributions follow power laws. Critical exponents are consistent with a scaling relationship observed recently in neural avalanches measurements. In conclusion, our simple model suggests that avalanche power laws in cortical spontaneous activity may be the effect of a network at the critical point between the replay and non-replay of spatio-temporal patterns

Generalized Uncertainty Principle from Quantum Geometry

The generalized uncertainty principle of string theory is derived in the framework of Quantum Geometry by taking into account the existence of an upper limit on the acceleration of massive particles.Comment: 9 pages, LATEX file, to appear in Int. Jou. Theor. Phy

The Driving Forces of Economic Growth: Panel Data Evidence for the OECD Countries

This paper discusses links between policy settings, institutions and economic growth in OECD countries on the basis of pooled cross-country time-series regressions. The novel econometric approach used in the paper allows short-term adjustments and convergence speeds to vary across countries, in accordance with most theoretical models, while imposing restrictions only on the long-run coefficients. In addition to the "primary" influences of physical and human capital accumulation, the results confirm the importance for growth of R&D activity, the macroeconomic environment, trade openness and well developed financial markets. They also confirm that many of the policy influences operate not only via the overall efficiency of factor use but also indirectly via the mobilisation of resources for fixed investment.Growth; Institutions

Boosting productivity via innovation and adoption of new technologies : any role for labor market institutions?

The authors present empirical evidence on the determinants of industry-level multifactor productivity growth. They focus on"traditional factors,"including the process of technological catch up, human capital, and research and development (R&D), as well as institutional factors affecting labor adjustment costs. Their analysis is based on harmonized data for 17 manufacturing industries in 18 industrial economies over the past two decades. The disaggregated analysis reveals that the process of technological convergence takes place mainly in low-tech industries, while in high-tech industries, country leaders tend to pull ahead of the others. The link between R&D activity and productivity also depends on technological characteristics of the industries: while there is no evidence of R&D boosting productivity in low-tech industries, the effect is strong in high-tech industries, but the technology leaders tend to enjoy higher returns on R&D expenditure compared with followers. There is also evidence in the data that high labor adjustment costs (proxied by the strictness of employment protection legislation) can have a strong negative impact on productivity. In particular, when institutional settings do not allow wages or internal training to offset high hiring and firing costs, the latter reduce incentives for innovation and adoption of new technologies, and lead to lower productivity performance. Albeit drawn from the experience of industrial countries, this result may have relevant implications for many developing economies characterized by low relative wage flexibility and high labor adjustment costs.Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Labor Policies,Public Health Promotion,Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Health Monitoring&Evaluation,Economic Growth

Maximal Acceleration Limits on the Mass of the Higgs Boson

Caianiello's quantum geometrical model with maximal acceleration places the upper limit $\mu\leq 719.5$ GeV on the mass of the Higgs boson. The model also provides an equation linking the mass of the W boson to the Higgs mass $\mu$ and independent symmetry breaking and mass generating mechanisms. These may further restrict the value of $\mu$.Comment: LaTex file, 13 pages, to be published in Il Nuovo Cimento