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Synthesis, characterization and applications of highly stable pyrazolate-based metal-organic frameworks.
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Spectroscopic signatures of sub-parsec massive black hole.
No full textThe focus of this thesis is on the electromagnetic signatures associated with massive black hole (MBH) binaries (MBHBs). In current models of structure formation, galaxies assemble in a bottom-up hierarchical fashion. Observations show that MBHs are hosted in the nuclei of almost all nearby massive galaxies. The existence of close MBHBs is therefore expected as the result of galaxy mergers, although clear observational evidences of MBHBs remain elusive. Most of the current sub-pc MBHB candidates have been spectroscopically selected through the Doppler-shift technique. This method consists in the identification of broad emission lines (BELs) shifted with respect to the galaxy reference frame, as traced by the set of narrow lines (NELs). This shift is due to the hypothesized motion of the active MBH orbiting in a close binary. However velocity off-sets between BELs and NELs are not a unique feature of close MBHBs, and cannot be searched for beyond z ∼ 0.8 since most NELs fall out of the wavelength range covered by current optical surveys.
This work presents our contribution to (i) the prediction of new spectroscopic features associated with MBHBs at different evolutionary stages in the aftermath of a gas-rich merger, and to (ii) the search for new secure candidates at different redshifts, ruling out other possible interpretations of their physical nature.
In the first part of this thesis we discuss a MBHB model envisaging a set of narrow lines characterized by the same Doppler-shift displayed by the BELs.
This additional NEL system originates from the lower density gas orbiting in the so called gap region excavated by the gravitational interaction between the sub-pc MBHB and a surrounding thin circum-binary disk. We propose this model to interpret the features observed in the spectrum of the quasar SDSSJ092712.65+294344.0 (SDSSJ0927 hereafter). For the case of this peculiar source we show that the binary hypothesis is favored against the other possible physical scenarios of a recoiling AGN or of a chance superposition of two distinct objects in a galaxy cluster. However further follow up observations are mandatory to monitor on longer timescales (∼ > 10 yr) the periodic drift of the BELs expected over the binary orbital period, and to gather additional information on the quasar host galaxy and its close environment. Our study on SDSSJ0927 contributed to the realization of a systematic search for MBHB candidates at z ∼ < 0.8 through the development of automatic procedures by different groups including ours. The new algorithm implemented by our group will be also adapted to look for new candidates at higher redshifts based on the presence of two displaced peaks in the profile of the broad CIV line interpreted in terms of two active binary MBHs.
In the second part of this work, we devise a new spectroscopic approach to select MBHBs based on peculiarly reduced flux ratios between broad lines of lower and higher ionization potentials. In particular, we show that MBHBs can display anomalously small flux ratios between the MgII and CIV BELs, i.e. FMgII/FCIV ∼ < 0.15, in a limited range of sub-pc separations due to the erosion of the BEL emitting material bound to the secondary active MBH. This erosion is due to the tidal field of the more massive binary companion.
The advantage of our newly proposed technique is twofold: (i) it can select new candidates at higher redshifts, z ∼ 2, where both the considered BELs are visible in the optical spectrum, and (ii) the detection of a reduced FMgII/FCIV would be a strong indication of the presence of a sub-pc MBHB since it is not expected in the other physical scenarios alternative to the binary hypothesis.
We show that it is possible to use our flux ratio criterion to select peculiar AGN spectra at z ∼ 2 from the database of the Sloan Sky Digital Survey.
These peculiar sources can be observed again in the IR band to look for a shift between the broad lines of Hβ, MgII and CIV and the narrow [OIII]λ5007.
We start this new MBHB search with a small sample of 9 targets observed in the NIR-H band with the Very Large Telescope. Two sources are selected as binary candidates because the lower ionization lines of the MgII and of the Hβ have reduced fluxes relative respectively to the higher ionization line of the CIV and of the [OIII], and the three observed BELs show moderate shifts up to 1000 kms−1 relative to the narrow [OIII]. Hence we plan to perform new optical observations of these two sources to confirm and monitor the measured shifts, and to complete the search for MBHBs at z ∼ 2 to check the reliability of our newly proposed spectroscopic approach
Caratterizzazione del trasportatore vescicolare delle monoamine di tipo 2 (VMAT2) nei linfociti umani.
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Methylation profiles of exocrine and neuroendocrine colorectal carcinomas using methylation-specific multiple ligation-dependent probe amplification.
No full textIn this study, we employed Methylation-Specific Multiple Ligation-dependent Probe Amplification (MS-MLPA) to evaluate the methylation status of 34 genes in a series 104 formalin-fixed and paraffin-embedded specimens, including 83 exocrine adenocarcinomas (CRCs) and 21 neuroendocrine cancers (NECs), previously examined for clinico-pathological and molecular features, as well as in 25 colorectal mucosae from 13 CRC patients and from12 non-neoplastic patients.
We found higher levels of promoter methylation in normal colonic tissue of CRC-patients with respect to the control group. The CpG Island Methylation Phenotype (CIMP) was observed with similar frequency in exocrine CRCs and in NECs, but different methylation profiles were present in the two tumour types. Microsatellite instability was the marker most strongly associated with CIMP. In both CRCs and NECs, CIMP+/MSI+ tumours represented a homogeneous clinicopathological entity, associated with a very good prognosis compared with the other three classes of cancers.
Our results demonstrated that MS-MLPA is a rapid and sensitive method to analyse the methylation status of multiple genes simultaneously and presents innovative aspects that may have important scientific and clinical implications. The use of DNA methylation alterations as a molecular marker system could potentially be a powerful approach to population-based screening for the early detection and for risk assessment of colorectal cancer
Un'analisi del modello di sviluppo brasiliano: cambiamento strutturale, specializzazione commerciale e le politiche per l'innovazione.
No full textThe dissertation deals with the Brazilian economic model and the role of the State in managing the economy through industrial and innovation policies.
The first part of the dissertation is dedicated to the analysis of the productive structure and the international competitiveness of the Brazilian economy, while the second part focuses on the industrial and innovation policies implemented by the Brazilian government.
An analysis of the economy‟s structural change is conducted, pointing out which sectors have gained importance in terms of manufacturing value added during the economic reforms of the „90s and later on. A broad analysis of trade specialization is also conducted, and an investigation on the relationships between Brazil and its main trade partners is carried out, specifically focusing on China, currently its main trade partner. The trend in Foreign Direct Investments (FDI) flows is analysed, pointing out the increasing importance of the Brazilian multinationals in the international markets.
In order to evaluate the sustainability of the economic model, a broad evaluation of the government industrial and innovation policies is conducted to assess the consistency of those policies with the structural problems of the economy. In particular, policies to improve the international trade performance are analysed. Furthermore, programmes and policies to strengthen the National Innovation System (NIS) are evaluated, and an in depth analysis of the NIS is also carried out. In addition, one chapter deals with an important agent of the Brazilian NIS: the National Development Bank (BNDES) and its role in the credit market.
The increasing role of the State in managing the economy through industrial policies after several years of just “free markets” policies is positively evaluated, although some structural economic problems still remain
Self-adjointe extensions for symmetric Laplacians on polygons.
No full textBy the results contained in the paper by Birman and Skvortsov “On the square summability of the highest derivatives of the solution to the Dirichlet problem in a region with piecewise smooth boundary" the Laplace operator o on a plane curvilinear polygon with domain the Sobolev space H2() and homogeneous Dirichlet boundary conditions is a closed symmetric operator with deficiency indices (n, n), where n is the number of non-convex corners. Therefore on a non-convex polygon, o has infinite self-adjoint extensions. Such extensions have been recently determined by means of Kreǐn's resolvent formula. The purpose of this thesis is to extend such results to the case of different, more general, boundary conditions. In the first part of the thesis we consider the case of mixed Dirichlet-Neumann conditions, thus allowing each side j of the polygon boundary to support either a Dirichlet or a Neumann homogeneous boundary condition. In this case, building on results by Grisvard, while in the pure Neumann case the dimensions of the defect spaces is the same as in the case of the pure Dirichlet case already studied by Birman and Skvortsov, the mixed case has a different behavior, allowing both convex cases and non-convex cases with double vertex contribution. After explicitly characterizing the defect sub- space we determined the self-adjoint extensions by a Kreǐn's resolvent formula proceeding analogously to the pure Dirichlet case, however taking into account the double contribution due to the vertices with mixed boundary conditions.
In the second part of the thesis we further extend our analysis by allowing some sides j to support Robin boundary conditions. While this is a deformation of the case considered in the first part, some not completely trivial calculations are necessary in order to get results similar to the ones concerning the mixed Dirichlet-Neumann case. By such calculations, one can recover results anologous to the ones in the first part. However also different behaviors are possible:
1. for any > 0, for any 0 < j < , there are parameter values which give dj = 1;
2. for any x < j (3/2) , x 1.43, there are parameter values which give dj = 2.
Moreover, as expected, the dj 's converge to the ones corresponding to the mixed Dirichlet-Neumann case as the j 's converge to either 0 or 1 accordingly to the different possible cases and as in the mixed Dirichlet-Neumann a Kreǐn's formula giving the classification of all the self-adjoint extension is provided in Chapter 4
Trophic diversity and carbon sources fueling the pelagic food web on a deep, subalpine lake: the role of seasonality studied with stable isotope analysis.
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Pulse shaping and ultrashort laser pulse filamentation for applications in extreme nonlinear optics.
No full textThis thesis deals with numerical studies of the properties and applications of spatio-temporally coupled pulses, conical wavepackets and laser filaments, in strongly nonlinear processes, such as harmonic generation and pulse reshaping.
We study the energy redistribution inside these wavepackets propagating in gases and condensed media, in the linear and nonlinear regime. The energy flux constitutes a diagnostic for space-time couplings that we applied to actual experimental results. We analyze the spectral evolution of filaments in gases and derive the conditions for the generation of ultrashort pulses in the UV range. We study high harmonic generation in a gas from ultrashort conical wavepackets. In particular, we show how their propagation properties influence the harmonic output. We also study the interference of different electron trajectories. Finally, we derive the shape of stationary Airy beams in the nonlinear regime. For each topic, we present experimental results that motivated our works or were motivated by our simulations
