Feedback linearization of antagonistically actuated variable stiffness joints with twisted string actuators

The work of this thesis is on the implementation of a variable stiffness joint antagonistically actuated by a couple of twisted-string actuator (TSA). This type of joint is possible to be applied in the field of robotics, like UB Hand IV (the anthropomorphic robotic hand developed by University of Bologna). The purposes of the activities are to build the joint dynamic model and simultaneously control the position and stiffness. Three different control approaches (Feedback linearization, PID, PID+Feedforward) are proposed and validated in simulation. To improve the properties of joint stiffness, a joint with elastic element is taken into account and discussed. To the end, the experimental setup that has been developed for the experimental validation of the proposed control approaches.

String inflationary models with non-monotonic slow-roll and detectable tensor modes

The first chapter of this work has the aim to provide a brief overview of the history of our Universe, in the context of string theory and considering inflation as its possible application to cosmological problems. We then discuss type IIB string compactifications, introducing the study of the inflaton, a scalar field candidated to describe the inflation theory. The Large Volume Scenario (LVS) is studied in the second chapter paying particular attention to the stabilisation of the Kähler moduli which are four-dimensional gravitationally coupled scalar fields which parameterise the size of the extra dimensions. Moduli stabilisation is the process through which these particles acquire a mass and can become promising inflaton candidates. The third chapter is devoted to the study of Fibre Inflation which is an interesting inflationary model derived within the context of LVS compactifications. The fourth chapter tries to extend the zone of slow-roll of the scalar potential by taking larger values of the field φ. Everything is done with the purpose of studying in detail deviations of the cosmological observables, which can better reproduce current experimental data. Finally, we present a slight modification of Fibre Inflation based on a different compactification manifold. This new model produces larger tensor modes with a spectral index in good agreement with the date released in February 2015 by the Planck satellite.

Research on the vocal culture of Orcinus orca in the Loro Parque, Tenerife: a pilot study

This research is focussed on the study of Orcinus orca's communication system. The analysis of vocalizations emitted by marine mammals has started in the '80s and most studies have been carried out in the wild. In this regard the most studied animal has been common dolphin (Tursiops truncatus) as the numerous presence of captive individuals worldwide made researches easier to be carried out. Studies about Orcinus orca's vocalizations have mainly been carried out in the wild (most in British Columbia) because its maintenance in a controlled environment results to be very difficult, only 17 among parks and oceanaria worldwide have some Orcinus orca (45 overall among which 64% born in captivity). These researches showed that Orcinus orca emit three main different types of sounds, classified as: whistles, clicks and calls. Besides, it was discovered that different groups (pods) produce sounds belonging only to the relevant pod (dialects). It is rare to find two pods sharing some calls. The two pods usually live in adjacent areas and can form a clan. This study was carried out in a controlled environment in the Orca ocean structure (Loro Parque, Tenerife, Spain) where, at the moment (March 2012) 6 individuals are hosted. Here it was developed an automatic sound recording system. Thanks to the use of suitable mathematical algorithms that allow to isolate only "interesting" sound events that differ from the "background noise", it was possible to create a database. The visualization of the sound events collected in the database is carried out with the use of a software. By looking at this output and at the observation register we could match the animal to the sound produced. Three situations were detected and studied: 1) Chosen alone: the animal chooses to go to the recording pool but it is free to move to another pool with other individuals. 2) Put alone: the animal is put alone in the recording pool. 3) With other orcas: more animals are together in the recording pool. The statistic analysis show that animals emit more vocalizations when they are in the situation "Chosen alone". The research will continue in order to observe eventual differences in the individual repertoire of each Orcinus orca.

Moduli stabilisation and soft supersymmetry breaking in string compactifications

In this thesis, we shall work in the framework of type IIB Calabi-Yau flux compactifications and present a detailed review of moduli stabilisation studying in particular the phenomenological implications of the LARGE-volume scenario (LVS). All the physical relevant quantities such as moduli masses and soft-terms, are computed and compared to the phenomenological constraints that today guide the research. The structure of this thesis is the following. The first chapter introduces the reader to the fundamental concepts that are essentially supersymmetry-breaking, supergravity and string moduli, which represent the basic framework of our discussion. In the second chapter we focus our attention on the subject of moduli stabilisation. Starting from the structure of the supergravity scalar potential, we point out the main features of moduli dynamics, we analyse the KKLT and LARGE-volume scenario and we compute moduli masses and couplings to photons which play an important role in the early-universe evolution since they are strictly related to the decay rate of moduli particles. The third chapter is then dedicated to the calculation of soft-terms, which arise dynamically from gravitational interactions when moduli acquire a non-zero vacuum expectation value (VeV). In the last chapter, finally, we summarize and discuss our results, underling their phenomenological aspects. Moreover, in the last section we analyse the implications of the outcomes for standard cosmology, with particular interest in the cosmological moduli problem.

That Female Sound: Uptalk and Vocal Fry

This paper presents an analysis of women's voices, with a particular focus on how they are often criticized, and a discussion about two linguistic trends popular among them: uptalk and vocal fry

Axion-like particles and the 3.5 keV line in 4D string models

This work is focused on axions and axion like particles (ALPs) and their possible relation with the 3.55 keV photon line detected, in recent years, from galaxy clusters and other astrophysical objects. We focus on axions that come from string compactification and we study the vacuum structure of the resulting low energy 4D N=1 supergravity effective field theory. We then provide a model which might explain the 3.55 keV line through the following processes. A 7.1 keV dark matter axion decays in two light axions, which, in turn, are transformed into photons thanks to the Primakoff effect and the existence of a kinetic mixing between two U(1)s gauge symmetries belonging respectively to the hidden and the visible sector. We present two models, the first one gives an outcome inconsistent with experimental data, while the second can yield the desired result.