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Investigating the role of water in the protein dynamic transition
No full textProteins undergo a dynamic transition at approximately 220 K, also called protein ’glass’ transition, below which temperature proteins lose their conformational flexibility and become biologically inactive. The protein dynamic transition has been observed for several proteins utilizing different techniques, such as inelastic neutron scattering, infrared spectroscopy and X-ray crystallography. Water seems to play a role in this transition, especially in relation to the hydration layer surrounding the protein, termed hydration water, whose molecules interact with the protein surface. Despite various interpretations that have been advanced, the origin of the protein dynamic transition is still elusive.
Here, we investigate the protein ’glass’ transition by means of infrared spectroscopy and X-ray diffraction, focusing on the enzyme lysozyme over the temperature range 160-295 K. Starting with the experimental implementation of the protein powder hydration setup, we study different levels of hydration of the protein, comparing them with the dry lysozyme as well as with protein solutions of different concentrations. We find a crossover in the lysozyme structure that occurs near 230 K, enhanced by the presence of hydration water
GRAVITATIONAL WAVES FROM PRIMORDIAL BLACK HOLE FORMATION IN ALTERNATIVE THEORIES OF GRAVITY
No full textations of general relativity. Primordial black holes provide important information about the early Universe complementary to large-scale cosmological observations.
In the standard picture, primordial black holes are formed, during the epoch of radiation domination at early times, by (non-standard) enhancements in the power spectrum of primordial
perturbations generated during inflation over some scale ranges. An alternative mechanism for describing the generation of primordial black holes is currently under active development. It is based on non-standard gravitational effects at sub-millimetre scales in the early Universe, for which we expect deviations from general relativity to become significant. In this approach to the primordial black hole formation, the power spectrum of primordial fluctuations is assumed to be of the standard, nearly scale-invariant form set by inflation, while the evolution of the fluctuations after inflation results in enhancements of the power spectrum, providing a new mechanism for generating primordial black holes. In this project we study the latter scenario: a non-inflationary mechanism for producing primordial black holes. The aim of this work is to investigate the physical consequences of this scenario in order to be able to set constraints on Alternative Theories of Gravity. In particular, we study the production of scalar induced gravitational waves from primordial black hole formation in this newly proposed framework for the production of primordial
black holes.
The study of the production of scalar induced gravitational waves, which is the main original contribution of this thesis work, could help to better understand and constrain the non-inflationary mechanism proposed in a work in progress by Akrami, Patil, Vardanyan et al., to which I have been exposed, for producing primordial black holes and, as a consequence, modifi
Le società benefit: come bilanciare lo scopo di lucro con scopi di utilità sociale secondo la normativa italiana
Get PDFStudy of mitigation strategies of beam-induced background and Higgs boson couplings measurements at a muon collider.
Get PDFAbstract in english:
The goals of the scientific program of the Higgs boson physics at Future Colliders are: the improvement of the precision on the fermions and bosons coupling measurements, as deviation from the Standard Model could reveal New Physics, and measurement of Higgs boson self-couplings, that enable to determine the Higgs boson potential.
The muon collider is a possible future machine in which these physics goals can be reached with enough precision. Indeed, at the high center of mass energies, in the regime of multi-TeV and with the luminosity conditions that are foreseen for such a machine, the single, double and triple Higgs bosons production rates will be high enough to meet the required precision and determine the Higgs potential.
However, physics measurements at muon collider can be strongly affected by the huge amount of background that comes from the muon decays along the beam line.
The purpose of this thesis is two fold. The first one is to study the properties of the beam-induced background and the proposed mitigation strategies that are necessary to reduce it, with full detector simulation, at a muon collider. In this environment the reconstruction of physical objects, like hadronic jets produced by the fragmentation of quarks is studied.
The second one is the evaluation of the sensitivity on the Standard Model double Higgs production cross section measurement at 3 TeV center of mass energy. This analysis is the foundation for the evaluation of the sensitivity on the determination of the Higgs boson trilinear self-coupling at a muon collider.
Abstract in italiano:
Gli obiettivi del programma scientifico riguardante la fisica del bosone di Higgs ai collisori futuri sono: un aumento della precisione nelle misure degli accoppiamenti ai fermioni e ai bosoni, poiché deviazioni dal Modello Standard possono rivelare nuova fisica, e le misure degli auto-accoppiamenti del bosone di Higgs, che permettono di determinare il potenziale del bosone di Higgs.
Il collisore di muoni è un possibile collisore futuro in cui tali obiettivi possono essere raggiunti con sufficiente precisione. Infatti ad energie del centro di massa, nel range del Multi-TeV, e alle condizioni di luminosità previste per tale collisore, i rate di produzione di singolo, doppio e triplo Higgs sono sufficienti per raggiungere le precisioni richieste e determinare il potenziale di Higgs.
Tuttavia, le misure di fisica a un collisore di muoni possono essere affette dall’alto livello di fondo indotto dal fascio che deriva dal decadimento dei muoni lungo la linea di fascio.
Questa tesi ha un duplice obiettivo: il primo è di studiare le proprietà del fondo indotto dal fascio e le strategie necessarie per ridurlo tramite una simulazione dell’intero detector del collisore di muoni.
In tale contesto la ricostruzione di oggetti fisici come jets adronici prodotti dalla frammentazione dei quark sono studiati.
Il secondo è la stima della sensitività sulla misura della sezione d’urto di produzione del doppio Higgs all’energia del centro di massa di 3 TeV. Questa analisi è la base per la stima della sensitività nella determinazione dell’ auto-accoppiamento trilineare del bosone di Higgs a un collisore di muon
Modelling of plasma expansion and interpretation of measured profiles in a negative ion source.
Get PDFITER is an international project aiming to demonstrate the feasibility of energy production through controlled thermonuclear fusion. In order to trigger the required
fusion reactions, an extremely hot plasma has to be confined for a sufficiently long time. One of the primary methods for plasma heating is the Neutral Beam Injection
(NBI), which amounts to depositing additional power in the plasma by means of a highly energetic neutral beam, obtained through the neutralization of a precursor ion
beam. The ITER NBI will employ radiofrequency (RF) driven ion sources to generate and extract negative ions; this kind of source displays some important advantages,
such as low need for maintenance and moderate energy consumption, even though the research on the application of this technology to fusion experiments is less mature
than the more consolidated arc-filament discharge. In this framework, the main purpose of this thesis project is the investigation of the most important physical
processes underlying the plasma generation and expansion in a RF negative ion source, with a particular focus on plasma uniformity: indeed, the presence of a magnetic
filter field inevitably introduces drift motions inside the source, ultimately affecting several properties of the extracted beam such as current intensity, stability
and convergence. A pre-existent Particle-In-Cell simulation code was adapted and developed so as to study the plasma generation and expansion mechanisms in the SPIDER
source. The numerical results have been compared with recent experimental measurements obtained with movable electrostatic probes, with the intention of both
validating the code and providing an interpretation for the experimental trends, clarifying the relations between plasma properties and variations of the background
gas pressure, of the magnetic field and of the voltages of the plasma-facing electrodes.
SOMMARIO:
ITER è un progetto internazionale volto a dimostrare la fattibilità della produzione di energia tramite fusione nucleare termocontrollata. Affinché le reazioni di
fusione possano avere luogo, è necessario confinare un plasma ad alta temperatura per un tempo sufficientemente lungo. Gli iniettori di neutri sono uno dei metodi
più diffusi per il riscaldamento del plasma: in questo caso si utilizza un fascio di neutri ad alta energia, ottenuto tramite neutralizzazione di un fascio precursore
di ioni, per depositare potenza nel plasma stesso. Il progetto di ITER prevede sorgenti a radiofrequenza (RF) per la produzione e l'estrazione di ioni negativi;
questa tecnologia porta molti vantaggi, come il ridotto bisogno di manutenzione e un moderato consumo di energia ma, d'altra parte, la ricerca sulla sua applicazione
a esperimenti di fusione nucleare è ancora in evoluzione. In questo contesto, l'obiettivo principale di questo lavoro di tesi è lo studio dei processi fisici alla
base della generazione ed espansione del plasma in una sorgente di ioni negativi a radiofrequenza, con particolare attenzione all'uniformità di plasma: infatti, la
presenza di un filtro magnetico introduce inevitabilmente dei moti di deriva all'interno della sorgente e, di conseguenza, comporta l'alterazione di alcune proprietà
del fascio come l'intensità di corrente, la stabilità ed anche la convergenza. Un codice Particle-In-Cell già esistente è stato adattato e sviluppato con l'obiettivo
di studiare i meccanismi di generazione ed estrazione di plasma nella sorgente SPIDER. I risultati numerici sono stati confrontati con misure sperimentali ottenute
tramite sonde elettrostatiche mobili, con l'obiettivo di validare il codice e di analizzare le correlazioni tra le proprietà del plasma e variazioni della pressione
del gas di background, del campo magnetico e del potenziale della griglie esposte al plasma
Testing a specific Generalized Brans-Dicke model with the unified Effective Field Theory approach.
Get PDFOne of the most intriguing puzzle of modern Cosmology resides in the late time accelerated expansion of our Universe. Our standard model of Cosmology, the LCDM model, based on the General Relativity theory of gravity, explains this phenomenon in terms of a cosmological constant added into the Einstein equations. Despite the successful agreement of the LCDM model with cosmological data, some issues and internal inconsistencies are still without a satisfactory explanation. This motivates the quest for alternative cosmological model and the necessity of probing gravity at cosmic scales. This Master Thesis is about studying a specific modified gravity model, dubbed as Generalized Brans-Dicke theory, employing the unified language offered by the Effective Field Theory approach to dark energy. Implementing the Generalized Brans-Dicke theory in the EFTCAMB cosmological code, we study the model from a phenomenological point of view. We focus in particular on stability criteria, cosmological perturbations and we perform a Monte Carlo Markov Chain likelihood analysis to estimate parameters using recent cosmological datasets
