The Skipping Behavior of Users of Music Streaming Services and its Relation to Musical Structure

The behavior of users of music streaming services is investigated from the point of view of the temporal dimension of individual songs; specifically, the main object of the analysis is the point in time within a song at which users stop listening and start streaming another song ("skip"). The main contribution of this study is the ascertainment of a correlation between the distribution in time of skipping events and the musical structure of songs. It is also shown that such distribution is not only specific to the individual songs, but also independent of the cohort of users and, under stationary conditions, date of observation. Finally, user behavioral data is used to train a predictor of the musical structure of a song solely from its acoustic content; it is shown that the use of such data, available in large quantities to music streaming services, yields significant improvements in accuracy over the customary fashion of training this class of algorithms, in which only smaller amounts of hand-labeled data are available

Study and development of a reliable fiducials-based localization system for multicopter UAVs flying indoor

openThe recent evolution of technology in automation, agriculture, IoT, and aerospace fields has created a growing demand for mobile robots capable of autonomous operation and movement to accomplish various tasks. Aerial platforms are expected to play a central role in the future due to their versatility and swift intervention capabilities. However, the effective utilization of these platforms faces a significant challenge due to localization, which is a vital aspect for their interaction with the surrounding environment. While GNSS localization systems have established themselves as reliable solutions for open-space scenarios, the same approach is not viable for indoor settings, where localization remains an open problem as it is witnessed by the lack of extensive literature on the topic. In this thesis, we address this challenge by proposing a dependable solution for small multi-rotor UAVs using a Visual Inertial Odometry localization system. Our KF-based localization system reconstructs the pose by fusing data from onboard sensors. The primary source of information stems from the recognition of AprilTags fiducial markers, strategically placed in known positions to form a “map”. Building upon prior research and thesis work conducted at our university, we extend and enhance this system. We begin with a concise introduction, followed by a justification of our chosen strategies based on the current state of the art. We provide an overview of the key theoretical, mathematical, and technical aspects that support our work. These concepts are fundamental to the design of innovative strategies that address challenges such as data fusion from different AprilTag recognition and the elimination of misleading measurements. To validate our algorithms and their implementation, we conduct experimental tests using two distinct platforms by using localization accuracy and computational complexity as performance indices to demonstrate the practical viability of our proposed system. By tackling the critical issue of indoor localization for aerial platforms, this thesis tries to give some contribution to the advancement of robotics technology, opening avenues for enhanced autonomy and efficiency across various domains.The recent evolution of technology in automation, agriculture, IoT, and aerospace fields has created a growing demand for mobile robots capable of autonomous operation and movement to accomplish various tasks. Aerial platforms are expected to play a central role in the future due to their versatility and swift intervention capabilities. However, the effective utilization of these platforms faces a significant challenge due to localization, which is a vital aspect for their interaction with the surrounding environment. While GNSS localization systems have established themselves as reliable solutions for open-space scenarios, the same approach is not viable for indoor settings, where localization remains an open problem as it is witnessed by the lack of extensive literature on the topic. In this thesis, we address this challenge by proposing a dependable solution for small multi-rotor UAVs using a Visual Inertial Odometry localization system. Our KF-based localization system reconstructs the pose by fusing data from onboard sensors. The primary source of information stems from the recognition of AprilTags fiducial markers, strategically placed in known positions to form a “map”. Building upon prior research and thesis work conducted at our university, we extend and enhance this system. We begin with a concise introduction, followed by a justification of our chosen strategies based on the current state of the art. We provide an overview of the key theoretical, mathematical, and technical aspects that support our work. These concepts are fundamental to the design of innovative strategies that address challenges such as data fusion from different AprilTag recognition and the elimination of misleading measurements. To validate our algorithms and their implementation, we conduct experimental tests using two distinct platforms by using localization accuracy and computational complexity as performance indices to demonstrate the practical viability of our proposed system. By tackling the critical issue of indoor localization for aerial platforms, this thesis tries to give some contribution to the advancement of robotics technology, opening avenues for enhanced autonomy and efficiency across various domains

Vegetative incompatibility and potential involvement of a mycovirus in the Italian population of Geosmithia morbida

Studies carried out during an Italian outbreak of the Thousand Cankers Disease of walnut, demonstrated that non-coalescing cankers on host plants, separated by equidistant uninfected zones, were associated with incompatible strains of Geosmithia morbida. Confirmation of the vegetative incompatibility of paired fungal isolates, randomly collected from black walnuts, was obtained from observations of a clear separation zones and the absence of anastomoses. Pairing tests with two incompatible monoconidial strains indicated differences in morphology and growth rates. Electron microscopy revealed the presence of icosahedral mycovirus-like particles in one of the monoconidial strains that demonstrated low degrees of virulence in planta compared with a particlefree monoconidial strain. The occurrence of a vegetative incompatibility system in recently introduced populations of G. morbida has considerable implications for fungal biology. Incompatibility in G. morbida and potential direct or indirect roles of the observed virus-like particles have potential ecological and epidemiological consequences. \ua9 Firenze University Press

Analysing the relationship between ectomycorrhizal infection and forest decline using marginal models

This statistical survey originates from the problem of discovering which relationship exists between root ectomycorrhizal infection and health status of forest plants. The sampling scheme takes observations from roots that come from sectors around the tree resulting in a hierarchical association structure of the observations. Marginal regression models are used to analyze the mean effect of the ectomycorrhizal state on a response variable proxy for the health degree of the plants

Evaluating the impact of Hymenoscyphus fraxineus in Trentino (Alps, Northern Italy): first investigations

The spread of Hymenoscyphus fraxineus has been causing great concern regarding the survival of European ash (Fraxinus excelsior) throughout Europe since the 1990s. The disease was first recorded in Trentino (southern Alps, Italy) in 2012 and has spread throughout the mountain landscape, where ash trees are scattered in small and isolated stands in different valleys. The status of the disease was checked by monitoring the damage to natural regeneration and adult trees in 90 sites spread over the whole region. The survey confirmed the complete colonization by the pathogen of the whole investigated area, with high levels of damage to both young and adult ash trees. Regeneration (both seedlings and saplings) was observed to be affected by the fungus in 88 plots out of 90. Out of 4486 examined young European ashes, 2261 (50.4%) were affected and 789 (17.6%) were already dead. Ten of the 384 assayed flowering ashes (Fraxinus ornus) showed symptoms on branches and apical stems, similar to those observed for European ash. Isolation and molecular analysis proved the presence of the fungus on both symptomatic European and flowering ashes. The examined 386 adult trees showed different levels of damage, sometimes reaching more than 75% of the crown. Some individual trees (42) growing close to severely damaged trees appeared fully healthy, which suggests the possible existence of some resistant/tolerant individuals in the examined populations

Colored black holes and Kac-Moody algebra

We demonstrate that the near horizon symmetries of black holes in Einstein-Yang-Mills (EYM) theory are generated by an infinite-dimensional algebra that contains, in addition to supertranslations and superrotations, a non-Abelian loop algebra. This means that the Virasoro-Kac-Moody structure of EYM in asymptotically flat spacetimes has an exact analog in the near horizon region.Fil: Giribet, Gaston Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Montecchio, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin

The symmetries of magnetized horizons

We study stationary black holes in the presence of an external strong magnetic field. In the case where the gravitational backreaction of the magnetic field is taken into account, such an scenario is well described by the Ernst-Wild solution to Einstein-Maxwell field equations, representing a charged, stationary black hole immersed in a Melvin magnetic universe. This solution, however, describes a physical situation only in the region close to the black hole. This is due to the following two reasons: Firstly, Melvin spacetime is not asymptotically locally flat; secondly, the non-static Ernst-Wild solution is not even asymptotically Melvin due to the infinite extension of its ergoregion. All this might seem to be an obstruction to address an scenario like this; for instance, it seems to be an obstruction to compute conserved charges as this usually requires a clear notion of asymptotia. Here, we circumvent this obstruction by providing a method to compute the conserved charges of such a black hole by restricting the analysis to the near horizon region. We compute the Wald entropy, the mass, the electric charge, and the angular momentum of stationary black holes in highly magnetized environments from the horizon perspective, finding results in complete agreement with other formalisms.Comment: 17 pages. v2, typos corrected and discussions extende

Ottimizzazione dell'esercizio di un impianto per la distillazione discontinua di una miscela eptano/tetraidrofurano

Questa Tesi di Laurea tratta dell'ottimizzazione di una distillazione discontinua di una miscela di eptano e tetraidrofurano. Il lavoro svolto può essere diviso in un'analisi iniziale dell'esercizio, in modo da individuare come andare a procedere per l'ottimizzazione. In seguito si è pensato di modificare l'esercizio dell'impianto sostituendo tutte le fasi della distillazione con un'unica fase costituita da una distillazione a riflusso totale o a riflusso costante. Entrambi i metodi sono stati sviluppati e state effettuate varie prove per poi andare ad applicare la distillazione a riflusso totale. Per concludere la Tesi si è pensato a come gestire i sottoprodotti che venivano a formarsi nella distillazione e infine si sono teorizzati degli sviluppi futuriope

Structure and interactions of the STAS domains and of the Myb/SANT domains by means of NMR techniques

The present work is divided in two parts: the first one concerns the STAS domains, while the second one the Myb/SANT domains. The guiding thread linking the two parts is constituted by the method and the aims: these are the study of the structure and of the interactions of these domains by means of NMR techniques. The first family, the STAS (Sulfate Transporter and Anti-Sigma factor antagonist) was originally discovered by similarity with the ASA (Anti Sigma factor Antagonist), bacterial domains contained in proteins involved in the environmental stress response and in the induction of sporulation. The STAS are present in plants, bacteria, fungi and animals, in proteins with different roles, like light/oxygen/cyclic nucleotides sensors, transporters of various kinds, etc… They present a structure with five β-sheets and four α-helices, interspersed in a irregular way. The STAS structures from transporters currently known (Protein Data Bank, January 2013) are currently five: four bacterial one, one of mammal, none vegetal. The only mammalian structure known corresponds to the STAS of prestin from Rattus norvegicus, missing the Intervening Sequence (IVS), a sequence largely variable among the same family of proteins: one of the aims was achieving the full domain. The aforementioned prestin belongs to the SLC26A family, transmembrane anion transporters with a role in maintaining the electrolytic balance in epithelia. However, prestin is an anomalous member of this family, since it does not work as a transporter but as the motor protein responsible of the cochlear sound amplification. Besides the interest in the study of the full STAS domain, the attention was focused also on possible interaction partner. One of them, based on the activity model of an ammonium transporter where its C-terminal domain interacts with a cytoplasmic loop, could have been the so called Saier motif, constituted by a repeated amino acid triplet with a certain degree of conservation. The construct for the Saier motif was modelled on structural data available for the bacterial transporter BicA, a model that demonstrated to be not applicable to prestin, since this construct, cloned and expressed, had severe problems of solubility during the purification, already as a fusion protein. The STAS domain were most of the efforts were focused on was the one belonging to the sulfate transporter SULTR1;2 from Arabidopsis thaliana. This domain presents a 10 amino acid intervening sequence and no STAS structures from plants are currently known. After a trial with a construct already available, five new ones were cloned and tested. Anyway, it has not been possible obtaining a NMR sample but the most promising construct has been chosen for further attempts to optimize the final NMR buffer. The second part of this thesis, carried out at the Structural Genomics Consortium (SGC) in Toronto, Canada, deals with the Myb/SANT domains. These 50 amino acid domains present a three helix structure, where the second and the third helix (the most C-terminal ones) constitute a Helix-Turn-Helix (HTH) motif. Additional elements, such as further helices or β-hairpins, could be present. The difference of this domains stays in the distribution of the superficial charge: positive on the third helix and negative on first one for the Myb, the opposite for the SANT. The Myb are known chiefly as DNA-binding domains with their third helix, even if new evidence support that the first helix can interact with the basic histone tails; the SANT instead bind the histone tails with their third helix. Two domains of this family were solved and presented in this work: the repeat R1 of the DNA-binding domain of hDmp1 and the SANT2 domain of NCoR2. hDmp1 is a tumour suppressor protein with a DNA-binding domain constituted by three imperfect repeats: the structure of the most N-terminal repeat, R1, was solved, which showed the typical three helix structure and the same electrostatic surface properties of the Myb domains. Anyway, this portion of the domain does not bind DNA, tested with known and new sequences. This result is in agreement with what is known about DNA-binding domains of similar structure, where the interaction with DNA concerns only the R2 and R3 repeat, while R1 seems to have a secondary function. The other domain solved is the SANT2 of the protein NCoR2, a protein acting as nuclear receptor repressor in the absence of ligand. This protein has two SANT domains: the structure of the most N-terminal one was already solved (PDB. 1XC5) and studied, in particular as interaction partner of the enzyme histone deacetylase 3 (HDAC3). Nevertheless, the SANT2 domain has shown particular properties: besides a long additional helix at the C-terminal and a region of conformational averaging between these helix and the previous one, it presents electrostatic surface properties typical of the Myb, not of the SANT domains. No DNA interactions are known, but with the H4 histone tails, used for binding experiments monitored by 15N-HSQC. However, the concerned region lies in proximity of a mutation that was detected in the NMR sample during the assignment: the production of the wild-type protein and the repetition of the binding experiments have been planned