6,130 research outputs found
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 âpopularityâ 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 âjobsâ) 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: non-radiative, radiative
without AGN feedback, and 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 nellâambito 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 unâenergia del centro di massa di 13 TeV, corrispondente a 139 fbâ1 di luminositĂ integrata. Lâanalisi condotta sfrutta il canale multileptonico pp â H±±Hââ(â±±âââ,Y±±Yââ) â `±`±`âČâ`âČâ caratterizzato da uno stato finale formato da leptoni leggeri (`,`âČ=e,ÎŒ), di alta energia, isolati e prodotti direttamente dai bosoni provenienti dal vertice primario. Lo scopo Ăš 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, Ăš statocalcolato un limite di esclusione al 95% di CL per le masse dei bosoni interessati
Quando Assisi non era serafica. La facciata della cattedrale di San Rufino nel contesto storico-artistico di una città-stato del XIII secolo
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 . We also
investigate the expected performances of future space borne experiment, finding
that an overall miscalibration larger then for Planck and
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
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