SeLINA: a Self-Learning Insightful Network Analyzer

Understanding the behavior of a network from a large scale traffic dataset is a challenging problem. Big data frameworks offer scalable algorithms to extract information from raw data, but often require a sophisticated fine-tuning and a detailed knowledge of machine learning algorithms. To streamline this process, we propose SeLINA (Self-Learning Insightful Network Analyzer), a generic, self-tuning, simple tool to extract knowledge from network traffic measurements. SeLINA includes different data analytics techniques providing self-learning capabilities to state-of-the-art scalable approaches, jointly with parameter auto-selection to off-load the network expert from parameter tuning. We combine both unsupervised and supervised approaches to mine data with a scalable approach. SeLINA embeds mechanisms to check if the new data fits the model, to detect possible changes in the traffic, and to, possibly automatically, trigger model rebuilding. The result is a system that offers human-readable models of the data with minimal user intervention, supporting domain experts in extracting actionable knowledge and highlighting possibly meaningful interpretations. SeLINA's current implementation runs on Apache Spark. We tested it on large collections of realworld passive network measurements from a nationwide ISP, investigating YouTube and P2P traffic. The experimental results confirmed the ability of SeLINA to provide insights and detect changes in the data that suggest further analyse

Transcriptome-wide expression profiling in skin fibroblasts of patients with joint hypermobility syndrome/ehlers-danlos syndrome hypermobility type

Joint hypermobility syndrome/Ehlers-Danlos syndrome hypermobility type (JHS/EDS-HT), is likely the most common systemic heritable connective tissue disorder, and is mostly recognized by generalized joint hypermobility, joint instability complications, minor skin changes and a wide range of satellite features. JHS/EDS-HT is considered an autosomal dominant trait but is still without a defined molecular basis. The absence of (a) causative gene(s) for JHS/EDS-HT is likely attributable to marked genetic heterogeneity and/or interaction of multiple loci. In order to help in deciphering such a complex molecular background, we carried out a comprehensive immunofluorescence analysis and gene expression profiling in cultured skin fibroblasts from five women affected with JHS/EDS-HT. Protein study revealed disarray of several matrix structural components such as fibrillins, tenascins, elastin, collagens, fibronectin, and their integrin receptors. Transcriptome analysis indicated perturbation of different signaling cascades that are required for homeostatic regulation either during development or in adult tissues as well as altered expression of several genes involved in maintenance of extracellular matrix architecture and homeostasis (e.g., SPON2, TGM2, MMP16, GPC4, SULF1), cell-cell adhesion (e.g., CDH2, CHD10, PCDH9, CLDN11, FLG, DSP), immune/inflammatory/pain responses (e.g., CFD, AQP9, COLEC12, KCNQ5, PRLR), and essential for redox balance (e.g., ADH1C, AKR1C2, AKR1C3, MAOB, GSTM5). Our findings provide a picture of the gene expression profile and dysregulated pathways in JHS/EDS-HT skin fibroblasts that correlate well with the systemic phenotype of the patients

Design and verification of a micro wells turbine for Mediterranean operations

In the framework of the Poseidone Project we have designed a Wells turbine for Mediterranean operations. Here we present RANS computations carried out with OpenFOAM at different operating conditions. Rotor-stator interaction was synthetized with MRF approach and RANS closure relied on the cubic eddy viscosity closure of Lien et al. The virtual test rig reproduced the ISO conditions of the laboratory and was able to correctly predict torque and efficiency at different operations. Computations moreover allowed to acquire information on the threedimensional velocity and pressure field that develops inside the Wells turbine. The aim was to have an insight on the secondary motions and on the possible stall mechanism that characterize the device at low flow rates. Results were successfully validated against experimental measures

Ageing and performance studies of drift chamber prototypes for the MEG II experiment

We present the tests aimed at verifying the proper functioning of the tracking systems of MEG II on small prototypes, estimating the achievable resolutions and evaluating the gain loss experienced by the chamber during its operation

Results and perspectives of the MEG and MEG II experiments

Charged-lepton-flavour–violating decays are prohibited in the framework of the Standard Model of elementary particles, but many of its extensions predict measurable values for such decays. Several experiments are running or being designed to measure (or to set a limit on) such processes. Among these, the MEG experiment has recently set a new upper limit on the μ → eγ branching ratio B < 5.7 × 10 −13 at 90% CL. The process has a simple kinematics but very good resolutions are needed for discarding the huge background. In order to improve its sensitivity, an upgrade of the experiment is under development, and will start taking data in 2016. The foreseen sensitivity of the upgraded apparatus will be about 5 × 10−14 on the branching ratio of the process

Longitudinal Single-Bunch Instability in the ILC Damping Rings: Estimate of Current Threshold

Characterization of single-bunch instabilities in the International Linear Collider (ILC) damping rings (DRs) has been indicated as a high-priority activity toward completion of an engineering design. In this paper we report on a first estimate ofthe current thresholds for the instability using numerical and analytical models of the wake potentials associated with the various machine components. The numerical models were derived (upon appropriate scaling) from designs of the correspondingcomponents installed in existing machines. The current thresholds for instabilities were determined by numerical solution of the Vlasov equation for the longitudinal dynamics. For the DR baseline lattice as of Feb. 2007 we find the critical current forinstability to be safely above the design specifications leaving room for further optimization of the choice of the momentum compaction

Equilibrium of an Arbitrary Bunch Train in Presence of a Passive Harmonic Cavity: Solution through Coupled Ha\" issinski Equations

We study the effect of a passive harmonic cavity, introduced to cause bunch lengthening, in an electron storage ring. We derive a formula for the induced voltage from such a cavity with high $Q$, excited by a a sequence of bunches, allowing for arbitrary gaps in the sequence and arbitrary currents. Except for a minor term that can be determined iteratively, the voltage is given in terms of a single mode of the Fourier transforms of the bunch forms, namely the mode at the resonant frequency of the cavity. Supposing that the only wake field is from the harmonic cavity, we derive a system of coupled Ha\"issinski equations which determine the bunch positions and profiles in the equilibrium state. The number of unknowns in the system is only twice the number of bunches, and it can be solved quickly by a Newton iteration, starting with a guess determined by path-following from a solution at weak current. We explore the effect of the fill pattern on the bunch lengthening, and also the dependence on the shunt impedance and detuning of the cavity away from the third harmonic of the main accelerating cavity. We consider two measures to reduce the effects of gaps: 1) distribution of the gaps around the ring to the greatest extent allowed, and 2) "guard bunches" with higher charges adjacent to the gaps, compensating for the charge missing in gaps. Results for parameters of the forthcoming ALS-U light source are presented

Modeling Microbunching from Shot Noise Using Vlasov Solvers

Unlike macroparticle simulations, which are sensitive to unphysical statistical fluctuations when the number of macroparticles is smaller than the bunch population, direct methods for solving the Vlasov equation are free from sampling noise and are ideally suited for studying microbunching instabilities evolving from shot noise. We review a 2D (longitudinal dynamics) Vlasov solver we have recently developed to study the microbunching instability in the beam delivery systems for x-ray FELs and present an application to FERMI{at}Elettra. We discuss, in particular, the impact of the spreader design on microbunching

Shot-Noise Seeded Microbunching Instability: Second-Order Correction to the Gain Function

We determine the second-order correction to the gain function of the microbunching instability in single-pass systems of interest for the next generation of light sources. The calculation applies to the case where the instability is seeded by shot noise. We examine an analytically treatable model of beam dynamics where collective forces are active only in non-dispersive sections of the linac. We find that the second order term can augment the linear gain significantly while affecting the spectrum of the overall gain only marginally. The weight of the second-order correction relative to the linear gain is found to scale quadratically with respect to R56. The qualitative behavior predicted by the model is consistent with exact numerical solutions of the Vlasov equations for realistic lattices

Ageing and performance studies of drift chamber prototypes for the MEG experiment upgrade.

L’esperimento MEG, attualmente in presa dati presso il Paul Scherrer Institut di Zurigo (Svizzera), ha come scopo la ricerca del decadimento μ → eγ, proibito all’interno del Modello Standard, ma previsto da molte delle sue estensioni. La collaborazione ha appena pubblicato l’analisi dei dati 2009–2011, che porta il limite sul rapporto di decadimento di questo processo a BR(μ → eγ) < 5.7 × 10–13 , un fattore 20 rispetto al limite posto dall’esperimento precedente. La ricerca sperimentale del decadimento si basa sulla misura del quadrimpulso di fotoni e positroni provenienti da decadimenti di muoni fermi. Il quadrimpulso del fotone è misurato da un calorimetro a xenon liquido, mentre l’impulso del positrone è misurato da un insieme di camere a deriva poste in campo magnetico, seguito da barre scintillanti per una precisa determinazione del tempo. L’analisi dei dati raccolti nel 2012 è in corso, mentre un’ultima campagna di presa dati, prevista terminare a fine agosto 2013, permetterà di saturare la sensibilità raggiungibile con il presente apparato sperimentale. La collaborazione ha di recente proposto un upgrade dell’esperimento in cui alla stessa linea del fascio e allo stesso magnete verranno accoppiate una nuova camera a fili e un calorimetro a xenon con maggiore accettanza e granularità. Mediante tale upgrade si vuole migliorare la sensibilità alla ricerca del decadimento di un ulteriore fattore 10 (fino a qualche unità in 10–14 ) dove la maggior parte delle estensioni del Modello Standard prevedono l’esistenza del decadimento. Elemento chiave del nuovo apparato è la nuova camera a deriva, responsabilità dei gruppi italiani che partecipano all’esperimento. Essa è progettata per migliorare l’accettanza del segnale, mantenendo il materiale sulla traiettoria del positrone al minimo, dato che alle energie in gioco la diffusione coulombiana multipla è l’elemento di maggior disturbo per una precisa determinazione dell’impulso della particella. Tale camera, composta da più di 2000 fili con configurazione stereo, ` e riempita di una miscela molto leggera di elio e isobutano, e dovrà sostenere un flusso di particelle tre volte superiore a quella dell’esperimento attuale. In presenza di un così alto flusso di particelle le molecole del gas si scindono e tendono a formare depositi sui fili, riducendo le prestazioni della camera e arrivando a provocare, in casi estremi, danni macroscopici. Diventa di fondamentale importanza, nel momento in cui si va a costruire una nuova camera, studiare nel dettaglio quali siano le sue prestazioni su vari prototipi, e come le prestazioni siano modificate dall’invecchiamento della camera stessa, dato che la carica accumulata sui fili più caldi sarà dell’ordine di una frazione di Coulomb al centimetro. In questa tesi viene affrontato lo studio sperimentale del funzionamento dei primi prototipi, a partire dalla loro progettazione e simulazione (configurazione dei fili e dei campi elettrici, risposta al passaggio di particelle). I prototipi, realizzati all’interno dei laboratori della sezione di Pisa dell’Istituto Nazionale di Fisica Nucleare, sono stati caratterizzati per quanto riguarda le condizioni di lavoro e la risposta a diversi tipi di radiazione (particelle α, elettroni, raggi-X). Dall’analisi dei dati accumulati e da una semplice ricostruzione delle tracce ` e stato possibilie ricavare una stima delle risoluzioni ottenibili nell’apparato in diverse condizioni di lavoro, per orientare il disegno dell’apparato finale. Per lo svolgimento delle misure di invecchiamento è stato necessario allestire un nuovo laboratorio dove è stato possibile accelerare l’accumulo di radiazione mediante irraggiamento da una sorgente intensa di raggi-X, scelta e caratterizzata in base alle esigenze di misura. Si mostrer` a come i prototipi sono effettivamente in grado di misurare le tracce di particelle ionizzanti, e di sostenere un alto flusso di carica, e se ne evidenzieranno le modificazioni indotte dall’invecchiamento. Le misure effettuate per questa tesi hanno permesso di finalizzare il disegno della camera a deriva per l’upgrade dell’esperimento MEG, e di verificare in maniera preliminare le sue prestazioni