Studies of CMS data access patterns with machine learning techniques

This thesis presents a study of the Grid data access patterns in distributed analysis in the CMS experiment at the LHC accelerator. This study ranges from the deep analysis of the historical patterns of access to the most relevant data types in CMS, to the exploitation of a supervised Machine Learning classification system to set-up a machinery able to eventually predict future data access patterns - i.e. the so-called dataset “popularity” of the CMS datasets on the Grid - with focus on specific data types. All the CMS workflows run on the Worldwide LHC Computing Grid (WCG) computing centers (Tiers), and in particular the distributed analysis systems sustains hundreds of users and applications submitted every day. These applications (or “jobs”) access different data types hosted on disk storage systems at a large set of WLCG Tiers. The detailed study of how this data is accessed, in terms of data types, hosting Tiers, and different time periods, allows to gain precious insight on storage occupancy over time and different access patterns, and ultimately to extract suggested actions based on this information (e.g. targetted disk clean-up and/or data replication). In this sense, the application of Machine Learning techniques allows to learn from past data and to gain predictability potential for the future CMS data access patterns. Chapter 1 provides an introduction to High Energy Physics at the LHC. Chapter 2 describes the CMS Computing Model, with special focus on the data management sector, also discussing the concept of dataset popularity. Chapter 3 describes the study of CMS data access patterns with different depth levels. Chapter 4 offers a brief introduction to basic machine learning concepts and gives an introduction to its application in CMS and discuss the results obtained by using this approach in the context of this thesis

Gcn5 histone acetyltransferase is present in the mitoplasts

In Saccharomyces cerevisiae the Lysine-acetyltransferase Gcn5 (KAT2) is part of the SAGA complex and is responsible for histone acetylation widely or at specific lysines. In this paper we report that GCN5 deletion differently affects the growth of two strains. The defective mitochondrial phenotype is related to a marked decrease in mtDNA content, which also involves the deletion of specific regions of the molecule. We also show that in wild-type mitochondria the Gcn5 protein is present in the mitoplasts, suggesting a new mitochondrial function independent from the SAGA complex and possibly a new function for this protein connecting epigenetics and metabolism

Inclusive Universities. Evidence from the Erasmus Program

The Erasmus Program is the main international mobility program in Europe and worldwide. Since its launch in 1987, it has been growing both in terms of participants and budget devoted to its activities. However, despite the possibility to obtain additional funding, the participation of students with special needs to the program remains extremely low. This work quantifies the participation of these students to Erasmus and explores the network of universities involved in their mobility, along the period 2008-2013. In addition, it proposes a novel index to measure the level of inclusiveness of universities welcoming international students with disabilities. Quantifying and analyzing this aspect could be the basis for better designing targeted policies and for widening the participation of students with impairments to international mobility.Comment: 23 pages, 5 figure

Gender bias in the Erasmus students network

The Erasmus Program (EuRopean community Action Scheme for the Mobility of University Students), the most important student exchange program in the world, financed by the European Union and started in 1987, is characterized by a strong gender bias. Girls participate to the program more than boys. This work quantifies the gender bias in the Erasmus program between 2008 and 2013, using novel data at the university level. It describes the structure of the program in great details, carrying out the analysis across fields of study, and identifies key universities as senders and receivers. In addition, it tests the difference in the degree distribution of the Erasmus network along time and between genders, giving evidence of a greater density in the female Erasmus network with respect to the one of the male Erasmus network

On the coherent rotation of diffuse matter in numerical simulations of galaxy clusters

We present a study on the coherent rotation of the intracluster medium and dark matter components of simulated galaxy clusters extracted from a volume-limited sample of the MUSIC project. The set is re-simulated with three different recipes for the gas physics: $(i)$ non-radiative, $(ii)$ radiative without AGN feedback, and $(iii)$ radiative with AGN feedback. Our analysis is based on the 146 most massive clusters identified as relaxed, 57 per cent of the total sample. We classify these objects as rotating and non-rotating according to the gas spin parameter, a quantity that can be related to cluster observations. We find that 4 per cent of the relaxed sample is rotating according to our criterion. By looking at the radial profiles of their specific angular momentum vector, we find that the solid body model is not a suitable description of rotational motions. The radial profiles of the velocity of the dark matter show a prevalence of the random velocity dispersion. Instead, the intracluster medium profiles are characterized by a comparable contribution from the tangential velocity and the dispersion. In general, the dark matter component dominates the dynamics of the clusters, as suggested by the correlation between its angular momentum and the gas one, and by the lack of relevant differences among the three sets of simulations.Comment: 12 pages, updated to match the MNRAS versio

Pratiche collezionistiche: dai musei a Facebook. Osservazioni filosofiche e antropologiche.

Il lavoro parte da alcune osservazioni sulle metodologie che si trovano alla base dell'interesse occidentale per le culture non occidentali, per arrivare a definire come queste metodologie si ritrovino anche nel singolo individuo contemporaneo e nel suo approccio con la cultura. Si nota come alla base di entrambe le situazioni si possano riscontrare dei caratteri tipici del collezionismo: dall'appropriazione alla decontestualizzazione e immedesimazione

Search for scalar and vector doubly charged bosons with Run2 data collected by the ATLAS experiment at LHC

Il lavoro riportato in questa tesi si svolge nell’ambito delle teorie oltre il Modello Standard e riguarda la ricerca di bosoni scalari e vettoriali doppiamente carichi predetti nel Bilepton Model e nel Left-Right Symmetric Model (LRSM). Lo studio impiega i dati delle collisioni protone-protone raccolti dal rivelatore ATLAS durante il Run 2 del Large Hadron Collider a un’energia del centro di massa di 13 TeV, corrispondente a 139 fb−1 di luminosità integrata. L’analisi condotta sfrutta il canale multileptonico pp → H±±H∓∓(∆±±∆∓∓,Y±±Y∓∓) → `±`±`′∓`′∓ caratterizzato da uno stato finale formato da leptoni leggeri (`,`′=e,μ), di alta energia, isolati e prodotti direttamente dai bosoni provenienti dal vertice primario. Lo scopo è quello di estendere una precedente analisi includendo per la prima volta la presenza di bosoni vettoriali doppiamente carichi. Non osservando un eccesso rispetto alle predizioni del Modello Standard, è statocalcolato un limite di esclusione al 95% di CL per le masse dei bosoni interessati

CMB Polarization Systematics, Cosmological Birefringence and the Gravitational Waves Background

Cosmic Microwave Background experiments must achieve very accurate calibration of their polarization reference frame to avoid biasing the cosmological parameters. In particular, a wrong or inaccurate calibration might mimic the presence of a gravitational wave background, or a signal from cosmological birefringence, a phenomenon characteristic of several non-standard, symmetry breaking theories of electrodynamics that allow for \textit{in vacuo} rotation if the polarization direction of the photon. Noteworthly, several authors have claimed that the BOOMERanG 2003 (B2K) published polarized power spectra of the CMB may hint at cosmological birefringence. Such analyses, however, do not take into account the reported calibration uncertainties of the BOOMERanG focal plane. We develop a formalism to include this effect and apply it to the BOOMERanG dataset, finding a cosmological rotation angle $\alpha=-4.3^\circ\pm4.1^\circ$. We also investigate the expected performances of future space borne experiment, finding that an overall miscalibration larger then $1^\circ$ for Planck and $0.2\circ$ for EPIC, if not properly taken into account, will produce a bias on the constraints on the cosmological parameters and could misleadingly suggest the presence of a GW background.Comment: 10 pages, 3 figure