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Dual-mirror Schwarzschild-Couder (SC) telescopes are based on highly aspherical optics, and they represent a novel design in the world of very high energy astrophysics. This work addresses the realization and the qualification of the secondary mirror for an SC telescope, named ASTRI, developed in the context of the Cherenkov Telescope Array Observatory. The discussion surveys the overall development from the early design concept to the final acceptance optical tests.

Ultraviolet light causes DNA lesions that are removed by nucleotide excision repair (NER). The efficiency of NER is conditional to transcription and chromatin structure. UV induced photoproducts are repaired faster in the gene transcribed strands than in the non-transcribed strands or in transcriptionally inactive regions of the genome. This specificity of NER is known as transcription-coupled repair (TCR). The discovery of pervasive non-coding RNA transcription (ncRNA) advocates for ubiquitous contribution of TCR to the repair of UV photoproducts, beyond the repair of active gene-transcribed strands. Chromatin rules transcription, and telomeres form a complex structure of proteins that silences nearby engineered ectopic genes. The essential protective function of telomeres also includes preventing unwanted repair of double-strand breaks. Thus, telomeres were thought to be transcriptionally inert, but more recently, ncRNA transcription was found to initiate in subtelomeric regions. On the other hand, induced DNA lesions like the UV photoproducts must be recognized and repaired also at the ends of chromosomes. In this study, repair of UV induced DNA lesions was analyzed in the subtelomeric regions of budding yeast. The T4-endonuclease V nicking-activity at cyclobutene pyrimidine dimer (CPD) sites was exploited to monitor CPD formation and repair. The presence of two photoproducts, CPDs and pyrimidine (6,4)-pyrimidones (6-4PPs), was verified by the effective and precise blockage of Taq DNA polymerase at these sites. The results indicate that UV photoproducts in silenced heterochromatin are slowly repaired, but that ncRNA transcription enhances NER throughout one subtelomeric element, called Y’, and in distinct short segments of the second, more conserved element, called X. Therefore, ncRNA-transcription dependent TCR assists global genome repair to remove CPDs and 6-4PPs from subtelomeric DNA.

The Extremely Large Telescopes (ELTs), thanks to their large apertures and cutting-edge Multi-Conjugate Adaptive Optics (MCAO) systems, promise to deliver sharper and deeper data even than the JWST. SHARP is a concept study for a near-IR (0.95-2.45 \\(\\mu\\)m) spectrograph conceived to fully exploit the collecting area and the angular resolution of the upcoming generation of ELTs. In particular, SHARP is designed for the 2nd port of MORFEO@ELT. Composed of a Multi-Object Spectrograph, NEXUS, and a multi-Integral Field Unit, VESPER, MORFEO-SHARP will deliver high angular (\\(\\sim\\)30 mas) and spectral (R\\(\\simeq\\)300, 2000, 6000, 17000) resolution, outperforming NIRSpec@JWST (100 mas). SHARP will enable studies of the nearby Universe and the early Universe in unprecedented detail. NEXUS is fed by a configurable slit system deploying up to 30 slits with \\(\\sim\\)2.4 arcsec length and adjustable width, over a field of about 1.2\"\\(\\times\\)1.2\" (35 mas/pix). Each slit is fed by an inversion prism able to rotate by an arbitrary angle the field that can be seen by the slit. VESPER is composed of 12 probes of 1.7\"\\(\\times\\)1.5\" each (spaxel 31 mas) probing a field 24\"\\(\\times\\)70\". SHARP is conceived to exploit the ELTs apertures reaching the faintest flux and the sharpest angular resolution by joining the sensitivity of NEXUS and the high spatial sampling of VESPER to MORFEO capabilities. This article provides an overview of the scientific design drivers, their solutions, and the resulting optical design of the instrument achieving the required optical performance.

The next generation of Extremely Large Telescopes (ELTs), with their wide apertures and advanced Multi-Conjugate Adaptive Optics (MCAO) systems, will provide unprecedented sharp and deep observations, even surpassing the capabilities of James Webb Space Telescope (JWST). SHARP, a near-infrared (0.95-2.45 {\\mu}m) spectrograph, is designed to optimally exploit the collecting area and angular resolution of these forthcoming ELTs, and specifically optimized for the MCAO unit MORFEO at the ELT. SHARP includes two main units: NEXUS, a Multi-Object Spectrograph (MOS), and VESPER, a multi-Integral Field Unit. This paper outlines the opto-mechanical design of SHARP based on the scientific requirements of the project. The optical design is engineered to meet project specifications, featuring a compact mechanical structure that minimizes the required cryogenic power while ensuring ease of access for maintenance and straightforward assembly procedures.

The Beam Expander Testing X-ray facility (BEaTriX) is a unique X-ray apparatus now operated at the Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Brera (OAB), in Merate, Italy. It has been specifically designed to measure the point spread function (PSF) and the effective area (EA) of the X-ray mirror modules (MMs) of the Advanced Telescope for High-ENergy Astrophysics (ATHENA), based on silicon pore optics (SPO) technology, for verification before integration into the mirror assembly. To this end, BEaTriX generates a broad, uniform, monochromatic, and collimated X-ray beam at 4.51 keV. [...] In BEaTriX, a micro-focus X-ray source with a titanium anode is placed in the focus of a paraboloidal mirror, which generates a parallel beam. A crystal monochromator selects the 4.51 keV line, which is expanded to the final size by a crystal asymmetrically cut with respect to the crystalline planes. [...] After characterization, the BEaTriX beam has the nominal dimensions of 170 mm x 60 mm, with a vertical divergence of 1.65 arcsec and a horizontal divergence varying between 2.7 and 3.45 arcsec, depending on the monochromator setting: either high collimation or high intensity. The flux per area unit varies from 10 to 50 photons/s/cm2 from one configuration to the other. The BEaTriX beam performance was tested using an SPO MM, whose entrance pupil was fully illuminated by the expanded beam, and its focus was directly imaged onto the camera. The first light test returned a PSF and an EA in full agreement with expectations. As of today, the 4.51 keV beamline of BEaTriX is operational and can characterize modular X-ray optics, measuring their PSF and EA with a typical exposure of 30 minutes. [...] We expect BEaTriX to be a crucial facility for the functional test of modular X-ray optics, such as the SPO MMs for ATHENA.

A deep understanding of the life-cycle of galaxies, particularly those of high mass, requires clarifying the mechanisms that regulate star formation (SF) and its abrupt shutdown (quenching), often capable of stopping SF rates of hundreds of solar masses per year. What initially triggers quenching, and what sustains the quiescent state thereafter, especially given the frequent presence of large gas reservoirs or even massive gas inflows, are unsolved key issues. Ultimately, the crucial connection between the galaxy life-cycle and the surrounding Intergalactic (IGM) and Circumgalactic (CGM) Medium remains largely unclear. Addressing these issues requires studying star formation, chemical enrichment, and quenching homogeneously up to high redshift. The upcoming AO-assisted Extremely Large Telescope (ELT), will deliver sharper and deeper data than the JWST. SHARP is a concept study for a near-IR (0.95-2.45 mu) spectrograph designed to fully exploit the capabilities of ELT. Designed for multi-object slit spectroscopy and multi-Integral Field spectroscopy, SHARP points to achieve angular resolutions (~30 mas) far superior to NIRSpec at JWST(100 mas) to decipher and reconstruct the life-cycle oa galaxies.

In the first part of this thesis, we examine the influence of green and producer lobbies on the determination of the trade and environmental policies adopted by large countries that are linked by trade flows and transboundary pollution. In Chapter 2, we show that the impact of green lobbying on the relative efficiency of unilateral and cooperative environmental policy outcomes depends crucially on the magnitude of the 'pollution leakages' and on the type of trade policy regime. Our analysis suggests that environmental policy coordination might be more beneficial under a free trade regime.In Chapter 3, we examine the case where both producer and environmental groups are organized. We find that the nature of the relationship between the two lobbies and the relative efficiency of alternative policy outcomes depend on the type of policy regime, whether governments act unilaterally or cooperatively, and the size of the 'pollution leakages' and the emission spillovers.The second part of the thesis looks at the formation of international trade and environmental agreements. In Chapter 4, we describe a model of multi-dimensional international negotiations, where countries can enter separate agreements with different partners along different policy dimensions. We examine the implications of negotiation tie-in - the requirement that agreements must span multiple dimensions of interaction - for the viability of multilateral cooperation, when countries are linked by international trade flows and transboundary pollution. We show that, while in some cases a tie-in rule has either no effect or can make multilateral cooperation more viable, in others it can make an otherwise viable joint multilateral agreement unstable.In Chapter 5, we examine international trade negotiations when markets are imperfectly competitive and governments use import tariffs and export subsidies to alter the strategic interaction between oligopolistic firms. Using a simple model of intra-industry trade between three ex-ante symmetric countries, we find that partial agreements involving the coordinated use of both tariffs and subsidies might be stumbling blocs against multilateral trade cooperation. We show that the introduction of an international ban on export subsidies might help to sustain global free trade. Chapter 6 contains some concluding remarks.

Aims. We report on ESPRESSO high-resolution transmission spectroscopic observations of two primary transits of the highly-irradiated, ultra-hot Jupiter-size planet WASP-76b. We investigate the presence of several key atomic and molecular features of interest that may reveal the atmospheric properties of the planet. Methods. We extracted two transmission spectra of WASP-76b with R approx 140,000 using a procedure that allowed us to process the full ESPRESSO wavelength range (3800-7880 A) simultaneously. We observed that at a high signal-to-noise ratio, the continuum of ESPRESSO spectra shows wiggles that are likely caused by an interference pattern outside the spectrograph. To search for the planetary features, we visually analysed the extracted transmission spectra and cross-correlated the observations against theoretical spectra of different atomic and molecular species. Results. The following atomic features are detected: Li I, Na I, Mg I, Ca II, Mn I, K I, and Fe I. All are detected with a confidence level between 9.2 sigma (Na I) and 2.8 sigma (Mg I). We did not detect the following species: Ti I, Cr I, Ni I, TiO, VO, and ZrO. We impose the following 1 sigma upper limits on their detectability: 60, 77, 122, 6, 8, and 8 ppm, respectively. Conclusions. We report the detection of Li I on WASP-76b for the first time. In addition, we found the presence of Na I and Fe I as previously reported in the literature. We show that the procedure employed in this work can detect features down to the level of ~ 0.1 % in the transmission spectrum and ~ 10 ppm by means of a cross-correlation method. We discuss the presence of neutral and singly ionised features in the atmosphere of WASP-76b.

We characterized the transiting planetary system orbiting the G2V star K2-38 using the new-generation echelle spectrograph ESPRESSO. We carried out a photometric analysis of the available K2 photometric light curve of this star to measure the radius of its two known planets. Using 43 ESPRESSO high-precision radial velocity measurements taken over the course of 8 months along with the 14 previously published HIRES RV measurements, we modeled the orbits of the two planets through a MCMC analysis, significantly improving their mass measurements. Using ESPRESSO spectra, we derived the stellar parameters, \\(T_{\\rm eff}\\)=5731\\(\\pm\\)66, \\(\\log g\\)=4.38\\(\\pm\\)0.11~dex, and \\([Fe/H]\\)=0.26\\(\\pm\\)0.05~dex, and thus the mass and radius of K2-38, \\(M_{\\star}\\)=1.03 \\(^{+0.04}_{-0.02}\\)~M\\(_{\\oplus}\\) and \\(R_{\\star}\\)=1.06 \\(^{+0.09}_{-0.06}\\)~R\\(_{\\oplus}\\). We determine new values for the planetary properties of both planets. We characterize K2-38b as a super-Earth with \\(R_{\\rm P}\\)=1.54\\(\\pm\\)0.14~R\\(_{\\rm \\oplus}\\) and \\(M_{\\rm p}\\)=7.3\\(^{+1.1}_{-1.0}\\)~M\\(_{\\oplus}\\), and K2-38c as a sub-Neptune with \\(R_{\\rm P}\\)=2.29\\(\\pm\\)0.26~R\\(_{\\rm \\oplus}\\) and \\(M_{\\rm p}\\)=8.3\\(^{+1.3}_{-1.3}\\)~M\\(_{\\oplus}\\). We derived a mean density of \\(\\rho_{\\rm p}\\)=11.0\\(^{+4.1}_{-2.8}\\)~g cm\\(^{-3}\\) for K2-38b and \\(\\rho_{\\rm p}\\)=3.8\\(^{+1.8}_{-1.1}\\)~g~cm\\(^{-3}\\) for K2-38c, confirming K2-38b as one of the densest planets known to date. The best description for the composition of K2-38b comes from an iron-rich Mercury-like model, while K2-38c is better described by a rocky model with a H2 envelope. The maximum collision stripping boundary shows how giant impacts could be the cause for the high density of K2-38b. The irradiation received by each planet places them on opposite sides of the radius valley. We find evidence of a long-period signal in the radial velocity time-series whose origin could be linked to a 0.25-3~M\\(_{\\rm J}\\) planet or stellar activity.

ESPRESSO is the new high-resolution spectrograph of ESO's Very-Large Telescope (VLT). It was designed for ultra-high radial-velocity precision and extreme spectral fidelity with the aim of performing exoplanet research and fundamental astrophysical experiments with unprecedented precision and accuracy. It is able to observe with any of the four Unit Telescopes (UT) of the VLT at a spectral resolving power of 140,000 or 190,000 over the 378.2 to 788.7 nm wavelength range, or with all UTs together, turning the VLT into a 16-m diameter equivalent telescope in terms of collecting area, while still providing a resolving power of 70,000. We provide a general description of the ESPRESSO instrument, report on the actual on-sky performance, and present our Guaranteed-Time Observation (GTO) program with its first results. ESPRESSO was installed on the Paranal Observatory in fall 2017. Commissioning (on-sky testing) was conducted between December 2017 and September 2018. The instrument saw its official start of operations on October 1st, 2018, but improvements to the instrument and re-commissioning runs were conducted until July 2019. The measured overall optical throughput of ESPRESSO at 550 nm and a seeing of 0.65 arcsec exceeds the 10% mark under nominal astro-climatic conditions. We demonstrate a radial-velocity precision of better than 25 cm/s during one night and 50 cm/s over several months. These values being limited by photon noise and stellar jitter show that the performanceis compatible with an instrumental precision of 10 cm/s. No difference has been measured across the UTs neither in throughput nor RV precision. The combination of the large collecting telescope area with the efficiency and the exquisite spectral fidelity of ESPRESSO opens a new parameter space in RV measurements, the study of planetary atmospheres, fundamental constants, stellar characterisation and many other fields.