Quadrupole effects on the motion of extended bodies in Schwarzschild spacetime

The motion of an extended body up to the quadrupolar structure is studied in the Schwarzschild background following Dixon's model and within certain restrictions (constant frame components for the spin and the quadrupole tensor, center of mass moving along a circular orbit, etc.). We find a number of interesting situations in which deviations from the geodesic motion, due to the internal structure of the particle, can originate measurable effects. However, the standard clock-effect for a pair co/counter-rotating bodies spinning up/down is not modified by the quadrupolar structure of the particle.Comment: 9 pages, latex iopart class document, no figures. Note that the second term in the rhs of Eq. (1.2) was misprinted in the published version of the paper [Classical and Quantum Gravity, Vol. 25, 035005 (2008)]. The results are but correc

Light scattering by radiation fields: the optical medium analogy

The optical medium analogy of a radiation field generated by either an exact gravitational plane wave or an exact electromagnetic wave in the framework of general relativity is developed. The equivalent medium of the associated background field is inhomogeneous and anisotropic in the former case, whereas it is inhomogeneous but isotropic in the latter. The features of light scattering are investigated by assuming the interaction region to be sandwiched between two flat spacetime regions, where light rays propagate along straight lines. Standard tools of ordinary wave optics are used to study the deflection of photon paths due to the interaction with the radiation fields, allowing for a comparison between the optical properties of the equivalent media associated with the different background fields.Comment: 6 pages, 4 figures; published versio

Brain-Computer Interface meets ROS: A robotic approach to mentally drive telepresence robots

This paper shows and evaluates a novel approach to integrate a non-invasive Brain-Computer Interface (BCI) with the Robot Operating System (ROS) to mentally drive a telepresence robot. Controlling a mobile device by using human brain signals might improve the quality of life of people suffering from severe physical disabilities or elderly people who cannot move anymore. Thus, the BCI user is able to actively interact with relatives and friends located in different rooms thanks to a video streaming connection to the robot. To facilitate the control of the robot via BCI, we explore new ROS-based algorithms for navigation and obstacle avoidance, making the system safer and more reliable. In this regard, the robot can exploit two maps of the environment, one for localization and one for navigation, and both can be used also by the BCI user to watch the position of the robot while it is moving. As demonstrated by the experimental results, the user's cognitive workload is reduced, decreasing the number of commands necessary to complete the task and helping him/her to keep attention for longer periods of time.Comment: Accepted in the Proceedings of the 2018 IEEE International Conference on Robotics and Automatio

Sobolev embeddings for kinetic Fokker-Planck equations

We introduce intrinsic Sobolev-Slobodeckij spaces for a class of ultra-parabolic Kolmogorov type operators satisfying the weak H\"ormander condition. We prove continuous embeddings into Lorentz and intrinsic H\"older spaces. We also prove approximation and interpolation inequalities by means of an intrinsic Taylor expansion, extending analogous results for H\"older spaces. The embedding at first order is proved by adapting a method by Luc Tartar which only exploits scaling properties of the intrinsic quasi-norm, while for higher orders we use uniform kernel estimates

The parametrix method for parabolic SPDEs

We consider the Cauchy problem for a linear stochastic partial differential equation. By extending the parametrix method for PDEs whose coefficients are only measurable with respect to the time variable, we prove existence, regularity in H\"older classes and estimates from above and below of the fundamental solution. This result is applied to SPDEs by means of the Ito-Wentzell formula, through a random change of variables which transforms the SPDE into a PDE with random coefficients

Laudato si': the beauty of Pope Francis' vision

The Encyclical Letter of Pope Francis, "Laudato si'", addresses for the first time in the Church's history the subject of the protection of the environment, "the care of our common home". This rich and complex document analyses the causes of today’s ecological challenges, acknowledging the scientific consensus but adding an original analysis of the social, cultural, ethical and spiritual dimensions that are associated with the degradation of the environment. The Pope’s vision is that the ecological crisis is ultimately linked to a crisis of values, a spiritual void that permeates today’s technocratic society. In the authors' analysis, what makes this document particularly innovative is the Pope's appeal to action that, acknowledging the urgency and the immensity of the challenge we face, sees also its beauty, being a unique occasion for humankind to show what it is capable of doing, and that is capable of taking responsibility. This positive narrative has the potential to mobilise people and governments towards a joint action that cannot however be limited to technological fixes, but should be broadened to consider new development models capable of addressing the deep roots of this crisis

Who wins the race for knowledge-based competitiveness? Comparing European and North American FDI patterns

The geographical dispersion of value-added activities triggered by the ‘great unbundling’ of production has made the race for competitiveness increasingly shaped by the capability of multinational corporations (MNCs) to orchestrate global innovation networks at world scale. However, major differences in the distribution of foreign investments across value chain functions undertaken by MNCs based in different economic areas have drawn little attention in the empirical literature. This work attempts to fill this gap by focusing on the FDI patterns of European and North American MNCs, which have historically played a key role in the internationalization of production and innovation. To this aim, we compare outward FDI flows of European and North American MNCs in manufacturing and knowledgeintensive activities over the period 2003–2017. We show that while European MNCs are key players in global networks of production, they do not reach the heights of North American investors in the dispersion of knowledge-based activities. Most importantly, European MNCs rely on emerging economies more to offshore production than to set up R&D labs in these countries; by contrast, US-based MNCs are more prone to engage in knowledgeintensive FDIs towards the most dynamic emerging countries (especially China and India, as well as the Four Asian Tigers). Further, we account for the growing role of new entrants in global FDI markets by comparing the advanced economies’ foreign investment decisions with those from Chinese MNCs. Drawing from the literature on the globalization of R&D and cross-border knowledge transmission, a discussion is finally offered on the potential implications of the detected differences in internationalization patterns, together with possible directions for future research