TASI Lectures on Gravitational Waves from the Early Universe

These lectures discuss how the direct detection of gravitational waves can be used to probe the very early Universe. We review the main cosmological mechanisms which could have produced relic gravitational waves, and compare theoretical predictions with capabilities and time scales of current and upcoming experiments.Comment: 37 pages, 8 figures; typos correcte

Crime, Education and Peer Pressure

We present a dynamic two-period model of individual behaviour with heterogeneous agents in which individuals decide how to allocate their disposable time between education, crime and work in the legal sector. Education has a multiple role: it implies higher expected wages in the legal sector, increasing the opportunity cost of committing crime and it has a sort of “civilization” effect that makes more costly to engage in criminal activities. We model this effect by introducing a peer pressure function.Crime, Education, Peer Pressure

Identifying the Effect of Education on Crime. Evidence from the Italian Regions

In this paper we develop an econometric approach aimed at estimating the impact of education on the rate of criminality for the twenty Italian regions over the period 1980-1985. Starting from a simple model in which we clearly identify the relationship between the level of education and the rate of criminality, we propose to test our theoretical model and to identify the characteristics of crime behaviour in Italy. In particular, we test which features of our theoretical model are confirmed by the econometric estimates and which features need a more careful analysis determined by the peculiarities of the Italian regions. The primary objective of our econometric estimates is to assess the existence of the relationship between crime and education. But in order to study the Italian reality we account for its peculiarities (slowness in reaching a final judgement, presence of organized crime in Italy, economic dichotomy between the North and the South of Italy).Crime, Education

Understanding the EU Policy Portfolio: Conceptualising a Dynamic Model of Integration

This paper suggests that EU‘s policy portfolio resembles the outcome of interstate bargaining predicted by federalist theory. We conclude that federalist theory, when combined with economic integration theory, is a robust tool for conceptualizing the EU policy portfolio. The result is a dynamic model, which we call 'federal integration‘

The equations of medieval cosmology

In Dantean cosmography the Universe is described as a series of concentric spheres with all the known planets embedded in their rotation motion, the Earth located at the centre and Lucifer at the centre of the Earth. Beyond these "celestial spheres", Dante represents the "angelic choirs" as other nine spheres surrounding God. The rotation velocity increases with decreasing distance from God, that is with increasing Power (Virtu'). We show that, adding Power as an additional fourth dimension to space, the modern equations governing the expansion of a closed Universe (i. e. with the density parameter \Omega_0>1) in the space-time, can be applied to the medieval Universe as imaged by Dante in his Divine Comedy. In this representation the Cosmos acquires a unique description and Lucifer is not located at the centre of the hyperspheres.Comment: 3 pages, 1 figur

Effective action and tension renormalization for cosmic and fundamental strings

We derive the effective action for classical strings coupled to dilatonic, gravitational, and axionic fields. We show how to use this effective action for: (i) renormalizing the string tension, (ii) linking ultraviolet divergences to the infrared (long-range) interaction between strings, (iii) bringing additional light on the special cancellations that occur for fundamental strings, and (iv) pointing out the limitations of Dirac's celebrated field-energy approach to renormalization.Comment: 13 pages, RevTex, one paragraph added at the en

Modeling dynamical scalarization with a resummed post-Newtonian expansion

Despite stringent constraints set by astrophysical observations, there remain viable scalar-tensor theories that could be distinguished from general relativity with gravitational-wave detectors. A promising signal predicted in these alternative theories is dynamical scalarization, which can dramatically affect the evolution of neutron-star binaries near merger. Motivated by the successful treatment of spontaneous scalarization, we develop a formalism that partially resums the post-Newtonian expansion to capture dynamical scalarization in a mathematically consistent manner. We calculate the post-Newtonian order corrections to the equations of motion and scalar mass of a binary system. Through comparison with quasi-equilibrium configuration calculations, we verify that this new approximation scheme can accurately predict the onset and magnitude of dynamical scalarization.Comment: 24 pages, 8 figures; recolored figures, fixed typos, added emai

Explaining the EU's Policy Portfolio: Applying a Federal Integration Approach to EU Cohesion Policy. Bruges Political Research Paper No. 20, December 2011

This paper engages with the debate about why the nature of the EU's policy portfolio is as it is. It does so by taking cohesion policy and asking the question, why has it come to occupy so important a position in the EU‟s policy portfolio? It is argued that the two most common conceptually-based approaches applied to cohesion policy – intergovernmentalism and multilevel governance – do not adequately explain either the timing or the dynamic of cohesion policy. A model that combines economic integration approaches and federal approaches is developed in the paper to provide a basis for a new explanatory framework for the prominent position of cohesion in the portfolio. We suggest that our approach – which we call a federal integration approach – has the potential to be applied to other policy areas

The dynamics of precessing binary black holes using the post-Newtonian approximation

We investigate the (conservative) dynamics of binary black holes using the Hamiltonian formulation of the post-Newtonian (PN) equations of motion. The Hamiltonian we use includes spin-orbit coupling, spin-spin coupling, and mass monopole/spin-induced quadrupole interaction terms. In the case of both quasi-circular and eccentric orbits, we search for the presence of chaos (using the method of Lyapunov exponents) for a large variety of initial conditions. For quasi-circular orbits, we find no chaotic behavior for black holes with total mass 10 - 40 solar masses when initially at a separation corresponding to a Newtonian gravitational-wave frequency less than 150 Hz. Only for rather small initial radial distances, for which spin-spin induced oscillations in the radial separation are rather important, do we find chaotic solutions, and even then they are rare. Moreover, these chaotic quasi-circular orbits are of questionable astrophysical significance, since they originate from direct parametrization of the equations of motion rather than from widely separated binaries evolving to small separations under gravitational radiation reaction. In the case of highly eccentric orbits, which for ground-based interferometers are not astrophysically favored, we again find chaotic solutions, but only at pericenters so small that higher order PN corrections, especially higher spin PN corrections, should also be taken into account.Comment: 18 pages, 26 figure