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Probing the Quark-Gluon Plasma properties through Heavy Quarks' dynamics: transport coefficients and elliptic flow
No full textQuantum Chromodynamics (QCD) is the non-abelian gauge field theory that within the Standard Model describes the strong interaction between quarks and gluons. QCD exhibits two main properties:confinement and asymptotic freedom. The former implies that in ordinary matter quarks and gluons are bounded within colorless hadrons. The latter is related to the decrease of the QCD strength coupling with increasing characteristic energy of the process. Asymptotic freedom implies that under extreme conditions of high temperature and density the interaction affecting quarks and gluons is so weakly that they are released from the bounding state to form a deconfined phase of matter known as the Quark-Gluon Plasma (QGP). Numerical solutions of QCD equations on lattice (lQCD) predict that such transition is properly a crossover at almost zero baryon density and with a critical temperature Tc=155 MeV. The study of nuclear matter under extreme conditions is the main program of the experiments at the Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) where ultrarelativistic Heavy-Ion Collisions (HICs) are conducted to create an almost baryon free QGP with initial T = 3Tc. In this scenario Heavy Quarks (HQs), mainly charm and bottom, play a unique role. Due to their large masses HQs are created at the initial stage of HICs by hard perturbative QCD scattering processes. Moreover, their thermalization time is comparable with the QGP lifetime. Hence HQs can probe the entire evolution of the fireball carrying more information about their initial properties. The most important observables in the HQ sector are the nuclear modification factor RAA and the elliptic flow v2. The challenge of each theoretical framework is to provide a simultaneous description of these two observables that have been measured both at RHIC and LHC energies.
In this thesis we study the HQ dynamics within the QGP by means of a relativistic Boltzmann transport approach. In this framework we treat non-perturbative QCD effects by prescription of a Quasi-Particle Model (QPM) in which light quarks and gluons of the bulk are dressed with effective masses and the T dependence of the strength coupling is fitted to lQCD thermodynamics.
In the first part of this thesis we discuss HQ transport coefficients by performing simulations in static QCD medium. We compare our extracted drag and diffusion coefficients with results obtained through a Montecarlo integration. Afterwards, we investigate charm suppression and compare the results among various theoretical models.
In the second part, we focus on the dynamical evolution of HQs within the QGP by carrying out simulations of realistic HICs. We observe that within our QPM interaction, which implies a T-dependent drag coefficient almost constant near Tc, we are able to describe simultaneously the RAA and v2 of D mesons both at RHIC and LHC energies. In order to compare with the experimental measurements we couple the final HQ spectra to a hybrid coalescence plus fragmentation hadronization model which is suitable to describe the large magnitude of the observed charmed baryon-to-meson ratio.
In the same framework, we provide our predictions for B meson RAA and v2 and compare our results with the available experimental data.
A goal of this work is to include the effect of enhanced baryon production in HICs on the nuclear modification factor.
Finally, we present our estimate of the HQ spatial diffusion coefficient Ds(T) within our Boltzmann approach. We show that our phenomenological predictions of Ds for charm quark are in agreement with lQCD expectations, meaning that through the study of HQ thermalization we can probe the QCD interaction within the present uncertainties of lQCD. We point out also that the possibility to calculate transport coefficients at the bottom mass scale allows to reduce uncertainties coming from the adopted transport model and to bring the estimate of Ds closer to the quenched lQCD
Ricostruzioni digitali e GIS 3D applicati all archeologia: il modello 3D della Necropoli di Porta Nocera (Pompei)
No full textIl presente lavoro illustra i risultati di un indagine volta alla definizione delle potenzialità, dei limiti e delle eventuali criticità connesse con utilizzo di oggetti digitali tridimensionali, inerenti il patrimonio culturale, come sistema informativo, valutandone le reali possibilità d'impiego come strumento di archiviazione, analisi, e condivisione dei risultati di una ricerca, condotta per la risoluzione di questioni storico-archeologiche. A tal fine si è indagato, pertanto, il ruolo del rilievo e della restituzione grafica come strumento di documentazione archeologica, soffermandosi sui cambiamenti che la diffusione di software per il disegno assistito sia 2D, che 3D, ha prodotto e da cui derivano la maggior parte degli oggetti digitali utilizzati nelle attività di ricerca. Un indagine volta a chiarirne la natura e le peculiarità, rispetto ad altre forme di documentazione, mostra come l iconicità, definita dal grado di similarità fra l oggetto reale e la corrispondente copia digitale, ne rappresenti l elemento di maggiore interesse.
L utilizzo dei modelli 3D realizzati dall IBAM-CNR nell ambito delle attività di rilievo e documentazione della necropoli di Porta Nocera e di Via Nucerina a Pompei, condotte a supporto delle attività di restauro previste dal Pompeii Sustainable Preservation Project (PSPP), progetto di ricerca internazionale sul restauro architettonico e archeologico, ha fornito il materiale per creare, tramite l utilizzo di PostgreSQL e di PostGIS, una banca dati con estensione geospaziale, denominata PSPP-Db , per la gestione integrata, in ambiente GIS e tramite l utilizzo di modelli 3D, dei dati relativi a tutte le attività di studio e ricerca condotte nell ambito del progetto. I risultati ottenuti hanno mostrato le grandi potenzialità dell utilizzo di modelli 3D non solo per la documentazione di oggetti e contesti archeologici, ma anche come veri e propri sistemi informativi
Innovative strategie computazionali per l'identificazione di nuovi target terapeutici nel melanoma e nel cancro alla tiroide.
No full textCancer signaling pathways have been extensively investigated. However, how cross-talk processes and integrates pathway responses in cancer is still far from being completely elucidated. Genetic and epigenetic alterations lead cells to aberrant proliferation and escapement from physiological mechanism controlling cell growth, survival and migration. In this context, specific mutations transform cellular proto-oncogenes to oncogenes, triggering hyperactivation of signaling pathways, whereas inactivation of tumor suppressors removes critical negative regulators of signaling. MAPK and PI3K/AKT pathways often present mutated genes in different types of cancer, and are strongly involved in intensive cross-talk.
There is an ever-increasing awareness that computational modeling and simulation are more than helpful in improving the understanding at cellular and molecular levels, in speeding-up the drug discovery process through the identification of alternative strategies with the aim to overcome drug resistance in cancer.
The main objective of this thesis is to reveal biochemical and genetic mechanisms underlying drug resistance in melanoma and thyroid cancer through the application of ordinary differential equations based models coupled with algorithmic approaches. These tumors share both MAPK and PI3K/AKT signaling pathway, with the presence of BRAF V600E mutation. Computational approaches developed in this PhD project were demonstrated to be able to find novel therapeutic targets and prognostic biomarkers for a more effective treatment in melanoma and thyroid cancer
An overdamped multimodal adaptive nonlinear static procedure for seismic assessment of rc infilled frames
No full textThe seismic assessment of existing structures is considered the fundamental step to (i) estimate the seismic capacity of the initial structure (ii) predict the collapse mechanism and the structural weakness, (iii) select the most appropriate seismic retrofitting technique and determine the improved capacity of the upgraded building.
Nonlinear dynamic analysis is widely recognised as the most accurate tool to predict the seismic behaviour of structures. However, this type of analysis has a high computational cost, and it is not an approach that can be extensively applied for professional purposes yet. To provide a tool that predicts the seismic behaviour of structures with a good accuracy but with a lower computational burden, nonlinear static methods of analysis were developed. The Capacity Spectrum Method (CSM) proposed by Freeman and the N2 Method proposed by Fajfar were pioneering methods and were recommended by the American and the European seismic code, respectively. Although these methods of analysis are generally reliable for the assessment of plane frames, however they neglect the contribution of higher modes of vibration to the seismic response and do not consider the progressive reduction of the structural stiffness due to the nonlinear behaviour of the structure. To improve the level of accuracy, advanced nonlinear static methods of analysis were developed, such as the Multimodal Pushover Analysis by Chopra et al., the Displacement Adaptive Puhover by Pinho et al. and the Advanced N1 method by Ghersi et al. Despite the innovative character of these methods, however they still present shortcomings.
Another important aspect regarding existing structures is the presence of infill panels. Although infill panels provide the structure with a much larger stiffness and their location and mechanical properties influence the dissipative mechanism of the structure, however they are considered nonstructural elements, and their contribution to the seismic response is neglected.
This thesis aims at the development of a nonlinear static method of analysis that can accurately estimate the seismic response of RC frames, with and without infill panels, keeping acceptable computation costs. To this end, the thesis proposes a multimodal adaptive procedure named overDamped Displacement Adaptive Procedure (D-DAP). This method has been developed from the combination of the approaches proposed by Pinho et al. and by Ghersi et al. The multimodal adaptive procedure to update the load vector is taken from the first, while the method for the association of the peak ground acceleration to the displacement demand without the SDOF approximation is drawn from the second. In addition, the D-DAP is equipped with an equivalent damping to consider the increase of the energy dissipation due the cumulated damage in the structure. To this end, the value of the equivalent damping is updated at each step according to a new damping law that has been properly calibrated in this work for RC frames with and without infill panels.
The accuracy of the D-DAP in the seismic assessment of rc frames was compared to that of the DAP by Pinho, the MPA by Chopra, the N2 method (EC8) and the CSM (FEMA 440). To this end, a set of 54 RC frames was designed to be representative of existing buildings with various levels of seismic deficiencies, and their seismic responses were predicted by those aforementioned methods of analysis. These comparisons showed that the D-DAP applied with the proposed damping law demonstrated an accuracy in predicting the seismic response of RC frames, with and without infills, generally higher than the other nonlinear static methods of analysis. In particular, the D-DAP provided a significant improvement with respect to the other existing methods in the prediction of the response of RC frames with infill panels
le Digital Humanities come programma di ricerca. Un modello concettuale per il Monastero dei Benedettini di Catania
No full textIl lavoro di ricerca proposto si colloca nel campo delle Digital Humanities, ed ha come oggetto principale un complesso architettonico, il Monastero dei Benedettini di San Nicola l Arena di Catania. Di esso si propone la rappresentazione attraverso le tecnologie semantiche, al fine di potere indagare le relazioni tra uomini, luoghi e testi che ne hanno caratterizzato il contemporaneo cantiere di recupero guidato dall architetto Giancarlo De Carlo. Lo strumento qui fornito, l Ontologia del Monastero dei Benedettini, si pone come base di partenza per metodologie di sperimentazione di semantica dei luoghi , indispensabile per cogliere le dinamiche sociali storicizzate. Grazie alla semantica dei luoghi è possibile cogliere le tensioni del suo passato più recente, quello del suo recupero, a supporto dei processi di restauro e riuso.
La ricerca qui presentata è introdotta da un ampia rassegna sulle metodologie informatiche in ambito umanistico e sulle interazioni uomo-macchina, oltre che un necessario approfondimento sulle tecnologie legate al web semantico. L occasione fornita dal lavoro di ricerca ha permesso di incrementare un recente filone di studi che non riguarda solo le vicende storiche del Complesso ma soprattutto quelle legate al suo riuso come sede universitaria e bene pubblico per la città di Catania
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No full textLa ricerca che s inserisce nell alveo della Scienza Politica si focalizza sulle organizzazioni non profit (ONP) italiane attive nella ricerca sanitaria e, in particolar modo, sulla rappresentanza dei loro interessi presso il sistema politico-istituzionale. Il tema in questione assume, infatti, una particolare rilevanza poiché consente di inquadrare tali organizzazioni come gruppi d interesse al pari di altri attivi nell odierna scena politica. Le domande principali dello studio si incentrano, pertanto, su quali siano in concreto gli interessi delle ONP e, soprattutto, in che modo quest ultimi vengono portati all attenzione dei policy-makers al fine di influenzarne le decisioni. L ipotesi di ricerca principale avanzata considera che le ONP di ricerca sanitaria, in quanto gruppi di interesse pubblico, privilegerebbero strategie di lobbying diretto rispetto a quello indiretto in merito alla policy di riferimento. La metodologia di ricerca intrapresa è di tipo misto, caratterizzata sia da un analisi quantitativa che qualitativa: in particolare, quest ultima (di norma privilegiata) si avvale di interviste all élite delle organizzazioni (quest ultime suddivisibili in ONP nazionali, ONP regionali e reti di ONP) e di un analisi di documenti. L ipotesi si rivela confermata solo in parte: solamente, infatti, alcune organizzazioni rispetto al complesso di quelle coinvolte adotterebbero maggiormente strategie di lobbying diretto rispetto a quello indiretto. Riguardo ai risultati ottenuti, si rileva, inoltre, come le ONP considerate non abbiano solo sviluppato strategie di lobbying distinte tra loro, ma siano protagoniste, più in generale, di linee strategiche differenti
Innovative techniques for conformal doping of semiconductors for applications in micro- and nano-electronics
No full textThis Ph.D. thesis is intended to provide a contribution to understanding some aspects of doping by MD through systematic experimental work.
In chapter 1, in order to better understand this work, the main aspects of semiconductor properties, the techniques commonly used for doping these materials and the MD are briefly recalled.
In chapter 2 some aspects of MD are discussed. In particular a physico-chemical characterization of molecular precursors in standard conditions, the role of the surface treatments and the role of the dilution of the precursor solution was examined.
In chapter 3, the results about the role of the deposition parameters in MD are discussed, focusing on the role of coating time and sampling time and on the role of the solvent and the molecular precursor.
Chapter 4 examines the results obtained by studying the effects of the post-deposition treatments. The following aspects are discussed in detail: the role of the annealing parameters: Temperature and time, the competition between evaporation and diffusion and the role of the cap layer.
In chapter 5 an example of application of MD to Si nanowires are investigated.
Finally, the results of this work and the perspectives of this activity are discussed and possible experimental approaches for the study of some unclear aspects in this thesis work are proposed.
These aspects were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), transmission electronic microscopy (TEM) and Raman Spectroscopy, electrical measurements were performed by spreading resistance profiles (SRP)
The healthy effects of L. barbarum on in vitro cell models
No full textCancer is a group of diseases characterized by the over proliferation of the cells. Epidemiological studies indicate that about 30-40% types of cancers are directly or indirectly linked to improper diet and related factors. Morover, several reports demonstrate an association between intake of fruits and vegetables and reduced mortality from degenerative diseases, including cancer.
Plants possess a variety of bioactive substances like phenols, flavonoids, carotenes and organo sulphur compounds having anti proliferative activities.
Goji is a native Chinese deciduous shrub with bright red berries. Goji has been utilized in traditional chinese medicine since the first century AD to promote longevity, to sustain the liver and improve the eyesight.
To date, several studies indicate beneficial effects of Goji berries for diabetes, high blood pressure, poor circulation, fever, malaria, inlammatory diseases, eye disorders and cancer.
Goji polysaccharide was shown to inhibit the growth of human leukemia HL-60 and human breast cancer MCF-7 cell lines. In vivo, it could enhance the anti-cancer effect of a chemotherapy on patients with various neoplasias, such as malignant melanoma, renal cell carcinoma, colorectal carcinoma, and lung cancer.
Besides the great variety of association studies, there is a need of studies to unravel its therapeutic effects at the biochemical level.
In our study, we demonstrate that Goji dry extracts do not induce in vitro tumor cell death and do not determine reduction of proliferation, using several tumor cell lines and fibroblasts and lymphocytes as normal cell controls.
Goji dry extract has shown in vitro excellent anti-inflammatory properties in a bidimensional monolayer of differentiated Caco-2 cells, as a model of the intestinal barrier. TNF-alpha-induced increase in intestinal epithelial tight junction (TJ) permeability, proposed as one of the proinflammatory mechanisms contributing to the intestinal inflammation, has been drastically reduced by Goji treatment; moreover, after 24 h incubation with the cytokine, MTT showed a beneficial protective effect when epithelial cells were treated with the Goji extract.
In our study, we have also evaluated the cellular effects by the fecal water (aqueous phase of human feces, FW), a useful biomarker approach to study cancer risks and protective activities of food.
Faecal waters from 5 healthy volunteers consuming their habitual diet were screened for genotoxicity by the single-cell gel electrophoresis (comet) assay and citotoxicity by the MTT assay, using a human cell line models, as target; goji berries supplementation increased the vitality of FW-treated cells and reduced genotoxic damages, confirming the antioxidative properities of goji.
The results showed remarkable biological activity of goji berries and dry extract and qualify it as a potential resource for food/pharmaceutical applications
Characterisation of the mechanical behaviour of networks and woven fabrics with a discrete homogenization model
No full textIn the past decades there has been an impressive progress in the development of new materials for mechanical related applications. New generations of composites have been developed, that can offer advantages over the unidirectional fibre-reinforced mats commonly used then materials take the name of woven fabrics. The behaviour of this material is strongly
influenced by the micro-structure of the material.
In the thesis mechanical models and a numerical scheme able to model the mechanical
behaviour of woven fabrics and general network materials have been developed. The model
takes in to account the micro-structure by means of a homogenization technique. The fibres
in the network have been treated like microbeams, having both extensional and bending stiffness, with different types of connection, according to the pattern and detail of the network.
The developed procedure was applied for obtaining the homogenized mechanical models for some types of biaxial and quadriaxial networks of fibres, simulating either fibre nets (in
this case rigid connection were assumed among the fibres) or tissues with negligible interaction
between the fibre bundles, and with relative sliding prevented (in this case the connections
were simulated by means of pivots). Different geometries were analysed, including the
cases in which the fibres are not orthogonal.
A first gradient medium is usually obtained but, in some cases, the homogenization procedure
itself indicates that a higher order continuum is better fit to represent the deformation
of the micro-structure. Special results were obtained for the case of fibres connected by
pivots. In this cases an orthotropic material with zero shear modulus was obtained. Such a
material has a not elliptic constitutive tensor, thus it can lead to strain concentrations. However,
it was shown that some considerations about the physical behaviour of such networks
indicated that higher order terms had to be included in the expansion of the internal forces
and deformations, so that a strain gradient material was obtained.
The results obtained can be used for the design of specific materials requiring ad-hoc
properties. Although the reference model is a network material, the results obtained can be
applied to other similar kinds of microstructures, like pantographic materials, micro devices
composed by microbeams etc. They have been limited at the range of linear elasticity, that
is small deformation and linear elastic behaviour.
Then, numerical simulations were focused on extension tests and bias tests. The obtained
deformed configurations are consistent with the literature experimental tests, both for
balanced and unbalanced tissues. Moreover, a comparison between first and second gradient
numerical predictions was performed. It was observed that second gradient predictions
better simulate the experimental evidences
Coupled Kinetic and Electromagnetic approaches for the simulation of complex processes
No full textElectromagnetic fields are often used to manipulate matter in many technological processes including those applied in emerging fields related to nanotechnology. Generalizing this concept, manipulation processes use forces or fields generated by electromagnetic interactions (e.g. a thermal process at constant and uniform temperature uses lamps as heat sources). Often, in the description of the evolution induced by the process it is more convenient to identify a simplified scheme of the driven force/field (i.e. constant high temperature in the previous example).
Of course, these simplifications affect also the theoretical analysis of the material modification promoted by the processes.
Reconsidering the cited example of thermal process, temperature is just a parameter of the diffusion equations used to evaluate the material redistribution activated by the high temperature. In these cases also the experimental control of the process takes advantage of the definition of quasi-equilibrium thermodynamic parameters as process parameters.
However, the effect of the interaction between the electromagnetic field and the material is more difficult to control in some processes where the amount of energy released from the field towards the samples depends dynamically and self-consistently on the material kinetic evolution. The self-consistency makes difficult inferring the manipulation effects on a new system from the previous phenomenology on different systems. In this case, optimized new applications usually need complex and expensive Design of Experiments (DoE) in terms of man power and materials. This PhD dissertation focuses on such processes.
In particular, considering plasma and laser annealing processes, we aim to demonstrate that a reliable process control can be obtained by means of simulation methodologies which consider the full complexity of the process kinetics.
In spite of the differences in terms of machines and role in the manufacturing flow, plasma and laser processes share two striking common features, from the modeling perspective:
The manipulation results critically depend on the structure of the sample (especially if sub-micron structures are processed);
Electromagnetic simulations coupled with many-component kinetic models are the key aspect of the multi-scale / multi-physics formalism implemented in the numerical codes