Accurate and efficient waveforms for compact binaries on eccentric orbits

Compact binaries that emit gravitational waves in the sensitivity band of ground-based detectors can have non-negligible eccentricities just prior to merger, depending on the formation scenario. We develop a purely analytic, frequency-domain model for gravitational waves emitted by compact binaries on orbits with small eccentricity, which reduces to the quasi-circular post-Newtonian approximant TaylorF2 at zero eccentricity and to the post-circular approximation of Yunes et al. (2009) at small eccentricity. Our model uses a spectral approximation to the (post-Newtonian) Kepler problem to model the orbital phase as a function of frequency, accounting for eccentricity effects up to ${\cal{O}}(e^8)$ at each post-Newtonian order. Our approach accurately reproduces an alternative time-domain eccentric waveform model for eccentricities $e\in [0, 0.4]$ and binaries with total mass less than 12 solar masses. As an application, we evaluate the signal amplitude that eccentric binaries produce in different networks of existing and forthcoming gravitational waves detectors. Assuming a population of eccentric systems containing black holes and neutron stars that is uniformly distributed in co-moving volume, we estimate that second generation detectors like Advanced LIGO could detect approximately 0.1-10 events per year out to redshift $z\sim 0.2$, while an array of Einstein Telescope detectors could detect hundreds of events per year to redshift $z \sim 2.3$.Comment: 12 pages, 6 figures, 1 appendix. Submitted to Phys. Rev. D. v2: affiliations updated, one reference corrected. Accepted to Phys. Rev.

EU pension reform - An overview of the debate and an empirical assessment of the main policy reform options

This paper on European Union (EU) pension reform provides an overview of the debate and, on the basis of a series of model simulations, makes an empirical assessment of the main pension policy reform options at the EU, not the Member State, level. It estimates what it would take to bring the public PAYG pension system back into equilibrium and assesses the case for a shift to funding. The main conclusion of this paper is that the EU pension system should in the very long run (i.e. over more than one generation) be fully funded, with this being achieved using a two-stage optimal transition path. Stage one of this transition process should concentrate on stabilising the PAYG system and achieving a partial shift to funding, with stage two only occurring once circumstances permit. The fully funded system, once established, should have public and private pillars, with the public system in effect replacing the old PAYG system with a similar compulsory, defined benefit, system and with the private pillar being a voluntary, defined contribution, system.pension reform, policy reform options, ageing model, Mc Morrow, R�ger,

Decision-support method for profitable residential energy retrofitting based on energy-related occupant behaviour

Low-carbon energy retrofitting in buildings plays an important role because 75% of European buildings are considered inefficient and more than 40% are currently over 50 years old. The economic reinvestment of energy retrofit actions through reduced energy bills, as energy directives promote, greatly depends upon the energy consumption patterns. In support of the decision-making process towards a low-carbon energy transition in multi-family buildings, this paper introduces a novel assessment method that evaluates the profitability of energy efficiency measures, according to standard operating conditions derived from energy performance certificate procedures and real occupant energy consumption scenarios, through a parametric analysis. The aim is to assess the real energy and economic savings of retrofitting actions, depending on different energy-related occupant scenarios, and to enable comparisons with other buildings, providing a valuable model to identify the most feasible and low-carbon energy strategies in residential energy retrofitting. A Spanish multi-family building from 1942 is taken as the reference case study. The results show that energy savings for dwellings vary up to 80%, and the net present value per dwelling differs by up to 20,000V between different energy consumption patterns. The most appropriate energy efficiency measures according to low, medium or high consumption scenarios are highlighted