The acoustic cut-off frequency of the Sun and the solar magnetic activity cycle

The acoustic cut-off frequency -the highest frequency for acoustic solar eigenmodes- is an important parameter of the solar atmosphere as it determines the upper boundary of the p-mode resonant cavities. At frequencies beyond this value, acoustic disturbances are no longer trapped but traveling waves. Interference amongst them give rise to higher-frequency peaks -the pseudomodes- in the solar acoustic spectrum. The pseudomodes are shifted slightly in frequency with respect to p modes making possible the use of pseudomodes to determine the acoustic cut-off frequency. Using data from GOLF and VIRGO instruments on board the SOHO spacecraft, we calculate the acoustic cut-off frequency using the coherence function between both the velocity and intensity sets of data. By using data gathered by these instruments during the entire lifetime of the mission (1996 till the present), a variation in the acoustic cut-off frequency with the solar magnetic activity cycle is found.Comment: Paper accepted in ApJ. 26 Pages, 9 figure

Strangeness on the nucleon

Observables from parity violation in elastic electron-nucleon scattering and neutral current quasi-elastic neutrino-nucleus scattering are employed as tools to improve the current knowledge on the strangeness content in the nucleon.Comment: Proceedings of International Scientific Meeting on Nuclear Physics, 9-13th September 2012. La R\'abida, Huelva, Spai

Spike-based control monitoring and analysis with Address Event Representation

Neuromorphic engineering tries to mimic biological information processing. Address-Event Representation (AER) is a neuromorphic communication protocol for spiking neurons between different chips. We present a new way to drive robotic platforms using spiking neurons. We have simulated spiking control models for DC motors, and developed a mobile robot (Eddie) controlled only by spikes. We apply AER to the robot control, monitoring and measuring the spike activity inside the robot. The mobile robot is controlled by the AER-Robot tool, and the AER information is sent to a PC using the USBAERmini2 interface.Junta de Andalucía P06-TIC-01417Ministerio de Educación y Ciencia TEC2006-11730-C03-0

Pion production within the hybrid relativistic plane wave impulse approximation model at MiniBooNE and MINERvA kinematics

The hybrid model for electroweak single-pion production (SPP) off the nucleon, presented in [Gonz\'alez-Jim\'enez et al., Phys. Rev. D 95, 113007 (2017)], is extended here to the case of incoherent pion-production on the nucleus. Combining a low-energy model with a Regge approach, this model provides valid predictions in the entire energy region of interest for current and future accelerator-based neutrino-oscillation experiments. The Relativistic Mean-Field model is used for the description of the bound nucleons while the outgoing hadrons are considered as plane waves. This approach, known as Relativistic Plane-Wave Impulse Approximation (RPWIA), is a first step towards the development of more sophisticated models, it is also a test of our current understanding of the elementary reaction. We focus on the charged-current $\nu$($\bar\nu$)-nucleus interaction at MiniBooNE and MINERvA kinematics. The effect on the cross sections of the final-state interactions, which affect the outgoing hadrons on their way out of the nucleus, is judged by comparing our results with those from the NuWro Monte Carlo event generator. We find that the hybrid-RPWIA predictions largely underestimate the MiniBooNE data. In the case of MINERvA, our results fall below the $\nu$-induced 1$\pi^0$ production data, while a better agreement is found for $\nu$-induced 1$\pi^+$ and $\bar\nu$-induced 1$\pi^0$ production.Comment: 13 pages, 10 figure

The effect of pension rules on retirement monetary incentives with an application to pension reforms in Spain

In this work we theoretically disentangle the effects of pension provisions on a variety of financial incentives to retirement, trying to reconcile them with some key Spanish retirement patterns. We find that the "average" individual, who is never affected by any cap of contributions or benefits, has weak incentives to retire early and strong incentives to retire at the normal retirement age. Alternatively, individuals at the bottom of the wage distribution have strong incentives to retire as early as possible, because ot the interaction between age-related penalties and the minimun pension. Both findings perfectly accommodate the retirement hazard of medium and low earners respectively. In contrast, high earners (those that have their contributions capped) despite having strong incentives to retire at the Early Retirement Age, do not do so. This is because, for those workers, financial incentives are not a good proxy for the marginal utility from working. Finally, we analyze the reasons behind the failure of the 1997 reform in improving the sustainability of the Spanish public pension system

THE EFFECT OF PENSION RULES ON RETIREMENT MONETARY INCENTIVES WITH AN APPLICATION TO PENSION REFORMS IN SPAIN

In this work we theoretically disentangle the effects of pension provisions on a variety of financial incentives to retirement, trying to reconcile them with some key Spanish retirement patterns. We find that the “average” individual, who is never affected by any cap of contributions or benefits, has weak incentives to retire early and strong incentives to retire at the normal retirement age. Alternatively, individuals at the bottom of the wage distribution have strong incentives to retire as early as possible, because ot the interaction between age-related penalties and the minimun pension. Both findings perfectly accommodate the retirement hazard of medium and low earners respectively. In contrast, high earners (those that have their contributions capped) despite having strong incentives to retire at the Early Retirement Age, do not do so. This is because, for those workers, financial incentives are not a good proxy for the marginal utility from working. Finally, we analyze the reasons behind the failure of the 1997 reform in improving the sustainability of the Spanish public pension system.

An evaluation of the life-cycle effects of minimum pensions on retirement behavior

In this paper we explore the effects of the minimum pension program on welfare and retirement in Spain. This is done with a stylized life-cycle model which provides a convenient analytical characterization of optimal behavior. We use data from the Spanish Social Security to estimate the behavioral parameters of the model and then simulate the changes induced by the minimum pension in aggregate retirement patterns. The impact is substantial: there is threefold increase in retirement at 60 (the age of first entitlement) with respect to the economy without minimum pensions, and total early retirement (before or at 60) is almost 50% larger.Retirement, life cycle model, minimum pension, structural estimation

Cosmic magnetic fields and dark energy in extended electromagnetism

We discuss an extended version of electromagnetism in which the usual gauge fixing term is promoted into a physical contribution that introduces a new scalar state in the theory. This new state can be generated from vacuum quantum fluctuations during an inflationary era and, on super-Hubble scales, gives rise to an effective cosmological constant. The value of such a cosmological constant coincides with the one inferred from observations as long as inflation took place at the electroweak scale. On the other hand, the new state also generates an effective electric charge density on sub-Hubble scales that produces both vorticity and magnetic fields with coherent lengths as large as the present Hubble horizon.Comment: 4 pages, 2 figures. Contribution to the proceedings of Spanish Relativity Meeting 2010, Granada, Spain, 6-10 September 201

The onset of solar cycle 24: What global acoustic modes are telling us

We study the response of the low-degree, solar p-mode frequencies to the unusually extended minimum of solar surface activity since 2007. A total of 4768 days of observations collected by the space-based, Sun-as-a-star helioseismic GOLF instrument are analyzed. A multi-step iterative maximum-likelihood fitting method is applied to subseries of 365 days and 91.25 days to extract the p-mode parameters. Temporal variations of the l=0, 1, and 2 p-mode frequencies are then obtained from April 1996 to May 2009. While the p-mode frequency shifts are closely correlated with solar surface activity proxies during the past solar cycles, the frequency shifts of the l=0 and l=2 modes show an increase from the second half of 2007, when no significant surface activity is observable. On the other hand, the l=1 modes follow the general decreasing trend of the solar surface activity. The different behaviours between the l=0 and l=2 modes and the l=1 modes can be interpreted as different geometrical responses to the spatial distribution of the solar magnetic field beneath the surface of the Sun. The analysis of the low-degree, solar p-mode frequency shifts indicates that the solar activity cycle 24 started late 2007, despite the absence of activity on the solar surface.Comment: To be accepted by A&A (with minor revisions), 4 pages, 3 figures, 1 tabl

Rábade Romeo, S.: Teoría del conocimiento.

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