On the Construction of Quintessential Inflation Models

Attention has been recently drawn towards models in which inflation and quintessence schemes are unified. In such `quintessential inflation' models, a unique scalar field is required to play both the role of the inflaton and of the late-time dynamical cosmological constant. We address the issue of the initial conditions for quintessence in this context and find that, in the two explicit examples provided, inflation can uniquely fix them to be in the allowed range for a present day tracking.Comment: LaTex; 14 pages, 1 figure. V2: improved version, some points clarifie

Breakthroughs on the Dark Matter Issue

Last year observations had a profound impact on our views on the amount and nature of dark matter in the universe. We give a brief review of the recent history of dark matter models beyond the pure cold dark matter universe. In view of the most recent cosmological data, we then go on to discuss models with a positive cosmological constant. Finally we explicitly analyse a class of particle physics models for a dynamical cosmological component with negative pressure (``quintessence''), in the context of supersymmetric theories.Comment: 13 pages; Talk given by Antonio Masiero at the 8^th International Workshop on Neutrino Telescopes, 23-26 Feb. 1999, Venice, Italy. To be published in the Proceeding

Dark Energy and the Dark Matter relic abundance

Two mechanisms by which the Quintessence scalar could enhance the relic abundance of dark matter particles are discussed. This effect can have an impact on supersymmetric candidates for dark matter.Comment: 6 pages; to appear in the Proceedings of "Phi in the Sky - the quest for cosmological scalar fields", 8-10 July 2004, Porto (PT

A machine learning approach for stride speed estimation based on a head-mounted IMU

Walking speed in real-life conditions is typically estimated through wearable inertial sensors mounted on waist, lower limbs, or wrists. Very recently, head-mounted inertial sensors are emerging for gait assessment. The present study explores the feasibility of measuring the stride speed with a head-mounted inertial sensor in both laboratory and real-world settings. The developed algorithm exploits a Temporal Convolutional Network for the detection of the gait events and a Gaussian Process Regression for the stride speed estimation. The experimental evaluation was carried out on healthy young participants during both standardised indoor and real-world walking trials. For indoor trials, errors were smaller than previous studies (0.05 m/s). As expected, errors increased at lower speed regimes due to a reduced signals amplitude. During 2.5-hours real-world evaluation, errors were slightly larger but acceptable (0.1 m/s). Reported results are encouraging and show the feasibility of estimating gait speed with a single head-worn inertial sensor

Quintessence, Supersymmetry and Inflation

Recent data point in the direction of a $\Lambda$ dominated universe. We briefly review ``Quintessence'' as a model for a dynamical cosmological term and analyse the role of Susy QCD as a possible particle physics candidate. The multiscalar content of the theory is fully taken into account and interaction with other cosmological fields is discussed. Finally, the possibility of constructing a unified scheme for quintessence and inflation is mentioned.Comment: 5 LaTex pages, no figures; Talk given at the International Workshop on "Particles in Astrophysics and Cosmology: from Theory to Observations" (Valencia99), 3-8 May 1999, Valencia, Spain. To appear on Nucl. Phys. B, Proc. Supp