Structure and temporal dynamics of marine biodiversity in the Terra Nova Bay area (Ross Sea, Antarctica) analysed through DNA barcoding and metabarcoding: A standardized and systematic approach for the construction of a \u201cDNA Barcode\u201d library.

Aims and structure of the thesis: The firs objective of this thesis consisted in the quantification of the reference library completeness for the Cytochrome c oxidase subunit I (COI) barcode of metazoan species occurring in the Ross Sea MPA and in identifying which taxonomic groups in the last decades were investigated by using \u201cDNA barcode\u201d techniques performed in the Southern Ocean. In order to do that, all the available sequence data on major public repositories were gathered and analyzed. A collection of COI sequences amplified from specimen of the Italian National Antarctic Museum (MNA) was produced and aggregated to the latter to assemble the first global Ross Sea reference library of metazoan COI barcoding sequences. The potentialities of \u201cDNA metabarcoding\u201d techniques applied to the analysis of Antarctic biological communities were also evaluated in Terra Nova Bay (TNB) by focusing on the development of macrozoobenthic pioneering communities colonizing artificial structures over a period of three years and on nanoplankton temporal short-term dynamics in two consecutive years. These studies were conducted using innovative sampling methodologies and experiments and differed not only for the investigated community, but also for the sampling frequency, timing and study purposes. Due to the peculiarities of the three analyses, these will be detailed in three separate chapters. Each chapter is composed by its specific \u201cIntroduction\u201d to the concepts discussed in that study, followed by a section on \u201cMaterials and Methods\u201d and a joint section with the \u201cResults and Discussion\u201d. Considering that the different chapters, notwithstanding the fact that they pertain to the same, general topic of research, greatly differs in the overall design, as mentioned earlier, no general Discussion for the entire thesis was produced. Instead, an Introduction, discussing the most general topics covered by the entire thesis, is presented at first (i.e. the \u201cThesis Introduction\u201d), whereas the thesis\u2019 Conclusions, considering all the outcomes reported in the different chapters, will be presented at the end of the whole thesis (\u201cThesis Conclusions\u201d)

Attempts at memory control induce dysfunctional brain activation profiles in Generalized Anxiety Disorder: An exploratory fMRI study

Suppression of aversive memories through memory control has historically been proposed as a central psychological defense mechanism. Inability to suppress memories is considered a central psychological trait in several psychiatric disorders, including Generalized Anxiety Disorder (GAD). Yet, few studies have attempted the focused identification of dysfunctional brain activation profiles when patients with Generalized Anxiety Disorders attempt memory control. Using a well-characterized behavioral paradigm we studied brain activation profiles in a group of adult GAD patients and well-matched healthy controls (HC). Participants learned word-association pairs before imaging. During fMRI when presented with one word of the pair, they were instructed to either suppress memory of, or retrieve the paired word. Subsequent behavioral testing indicated both GAD and HC were able to engage in the task, but attempts at memory control (suppression or retrieval) during fMRI revealed vastly different activation profiles. GAD were characterized by substantive hypo-activation signatures during both types of memory control, with effects particularly strong during suppression in brain regions including the dorsal anterior cingulate and the ventral prefrontal cortex. Attempts at memory control in GAD fail to engage brain regions to the same extent HC, providing a putative neuronal signature for a well-established psychological characteristic of the illness

The Bryozoa collection of the Italian National Antarctic Museum, with an updated checklist from Terra Nova Bay, Ross Sea

This study provides taxonomic and distributional data of bryozoan species from the Ross Sea area, mainly around Terra Nova Bay, based on specimens curated at the Italian National Antarctic Museum (MNA, Section of Genoa). Bryozoan specimens were collected at 75 different sampling stations in the Ross Sea and in the Magellan Strait, in a bathymetric range of 18–711 meters, during 13 expeditions of the Italian National Antarctic Research Program (PNRA) conducted between 1988 and 2014. A total of 282 MNA vouchers corresponding to 311 specimens and 127 morphospecies have been identified and included in the present dataset. 62% of the species were already reported for the Terra Nova Bay area, where most of the Italian samples come from, with a 35% of samples representing new records classified at the specific level, and 3% classified at the genus level. These new additions increase to 124 the total number of species known to occur in Terra Nova Bay. Four 3D-models of Antarctic bryozoans from the Ross Sea are also presented and will be released for research and educational purposes on the Museum website

Design development and implementation of an irradiation station at the neutron time-of-flight facility at CERN

A new parasitic, mixed-field, neutron-dominated irradiation station has been recently commissioned at the European Laboratory for Particle Physics (CERN). The station is installed within the neutron time-of-flight (n_TOF) facility, taking advantage of the secondary radiation produced by the neutron spallation target, with neutrons ranging from 0.025 eV to several hundreds of MeV. The new station allows radiation damage studies to be performed in irradiation conditions that are closer to the ones encountered during the operation of particle accelerators; the irradiation tests carried out in the station will be complementary to the standard tests on materials, usually performed with gamma sources. Samples will be exposed to neutron-dominated doses in the MGy range per year, with minimal impact on the n_TOF facility operation. The station has 24 irradiation positions, each hosting up to 100 cm3 of sample material. In view of its proximity to the n_TOF target, inside protective shielding, the irradiation station and its operating procedures have been carefully developed taking into account the safety of personnel and to avoid any unwanted impact on the operation of the n_TOF facility and experiments. Due to the residual radioactivity of the whole area around the n_TOF target and of the irradiated samples, access to the irradiation station is forbidden to human operators even when the n_TOF facility is not in operation. Robots are used for the remote installation and retrieval of the samples, and other optimizations of the handling procedures were developed in compliance with radiation protection regulations and the aim of minimizing doses to personnel. The sample containers were designed to be radiation tolerant, compatible with remote handling, and subject to detailed risk analysis and testing during their development. The whole life cycle of the irradiated materials, including their post-irradiation examinations and final disposal, was considered and optimized

Serum Albumin Is Inversely Associated With Portal Vein Thrombosis in Cirrhosis

We analyzed whether serum albumin is independently associated with portal vein thrombosis (PVT) in liver cirrhosis (LC) and if a biologic plausibility exists. This study was divided into three parts. In part 1 (retrospective analysis), 753 consecutive patients with LC with ultrasound-detected PVT were retrospectively analyzed. In part 2, 112 patients with LC and 56 matched controls were entered in the cross-sectional study. In part 3, 5 patients with cirrhosis were entered in the in vivo study and 4 healthy subjects (HSs) were entered in the in vitro study to explore if albumin may affect platelet activation by modulating oxidative stress. In the 753 patients with LC, the prevalence of PVT was 16.7%; logistic analysis showed that only age (odds ratio [OR], 1.024; P = 0.012) and serum albumin (OR, -0.422; P = 0.0001) significantly predicted patients with PVT. Analyzing the 112 patients with LC and controls, soluble clusters of differentiation (CD)40-ligand (P = 0.0238), soluble Nox2-derived peptide (sNox2-dp; P < 0.0001), and urinary excretion of isoprostanes (P = 0.0078) were higher in patients with LC. In LC, albumin was correlated with sCD4OL (Spearman's rank correlation coefficient [r(s)], -0.33; P < 0.001), sNox2-dp (r(s), -0.57; P < 0.0001), and urinary excretion of isoprostanes (r(s), -0.48; P < 0.0001) levels. The in vivo study showed a progressive decrease in platelet aggregation, sNox2-dp, and urinary 8-iso prostaglandin F2 alpha-III formation 2 hours and 3 days after albumin infusion. Finally, platelet aggregation, sNox2-dp, and isoprostane formation significantly decreased in platelets from HSs incubated with scalar concentrations of albumin. Conclusion: Low serum albumin in LC is associated with PVT, suggesting that albumin could be a modulator of the hemostatic system through interference with mechanisms regulating platelet activation

Étude expérimentale et simulation des événements singuliers induits par des neutrons issus d’accélérateurs et impacts sur la qualification

Les composants et systèmes électroniques qui fonctionnent dans l'accélérateur Grand collisionneur de hadrons (LHC) au CERN sont soumis à un environnement radiatif à champ mixte, composé principalement de neutrons ayant des énergies allant des énergies thermiques jusqu'à quelques GeV. Cette thèse vise à déterminer l'impact des neutrons thermiques et d'énergie intermédiaire (0.2-20 MeV) par rapport aux particules hautement énergétiques sur les taux de Single Event Upset (SEU) et de Latch-up (SEL) induits dans des composants COTS (Commercial-Off-The-Shelf), généralement utilisés dans les systèmes d'accélérateurs.Les environnements radiatifs dans l'accélérateur sont décrits en différents endroits. Ils sont caractérisés et comparés aux spectres au niveau du sol et de l'atmosphère à différentes altitudes. Les processus nucléaires inélastiques et élastiques par lesquels des neutrons de différentes énergies induisent des événements singuliers (SEE) sont largement étudiés par le biais de simulations Monte Carlo, en termes de particules secondaires produites et de leurs propriétés. Les composants électroniques sont caractérisés expérimentalement dans des installations mono-énergétiques et de spallation, et les sections efficaces aux SEE sont comparées avec les simulations Monte Carlo, pour lesquelles le dépôt d'énergie est associé à la probabilité de SEE.À partir de ces études, le taux des SEE est estimé pour des applications d'accélérateur et atmosphérique et mis dans le contexte des approches de qualification au niveau des composants et des systèmes utilisés dans ces environnements. Les implications de qualification sont dérivées de la simulation et de l'étude expérimentale combinées. Cela permet de déterminer l'approche pour quantifier les contributions des neutrons thermiques et d'énergie intermédiaire. Au final, la méthodologie permet tenue des composants aux radiations (RHA) en se basant sur des résultats expérimentaux à champ mixte et mono-énergétiques et des connaissances consolidées de l'environnement opérationnel et des effets associés.Electronic components and systems operating in the Large Hadron Collider (LHC) accelerator at CERN are subjected to a particle radiation environment, mainly composed of neutrons with energies ranging from thermal up to a few GeV.This thesis aims at determining the impact of thermal and intermediate energy neutrons (0.2-20 MeV) with respect to highly energetic particles on the Single Event Upset (SEU) and Latch-up (SEL) rates induced in advanced Commercial-Off-The-Shelf (COTS) components, typically used in accelerator systems.The radiation environments of several locations in the accelerator are described, characterized and compared to the ground level and atmospheric spectra at varying altitude.Inelastic and elastic nuclear processes through which neutrons of different energies induce Single Event Effects (SEEs) are extensively studied through Monte Carlo simulations, in terms of produced secondaries and their properties.Electronic components are experimentally characterized in monoenergetic and spallation facilities, and the SEE cross sections benchmarked with Monte Carlo simulations, where the energy deposition is associated with the SEE probability.From these studies, the SEE rate is estimated for accelerator and atmospheric applications and put in the context of the qualification approaches at component and system level used in these environments. The qualification implications are derived from the combined simulation and experimental study, in order to determine the approach for quantifying the thermal and intermediate energy neutron contributions. Several solutions are proposed aiming towards a radiation hardness assurance (RHA) methodology based on mixed-field and monoenergetic experimental results, besides the consolidated knowledge of the operational environments and the associated effects

Impact of thermal and intermediate energy neutrons on the semiconductor memories for the CERN accelerators

A wide quantity of SRAM memories are employed along the Large Hadron Collider (LHC), the main CERN accelerator, and they are subjected to high levels of ionizing radiations which compromise the reliability of these devices. The Single Event Effect (SEE) qualification for components to be used in the complex high-energy accelerator at CERN relies on the characterization of two cross sections: 200-MeV protons and thermal neutrons. However, due to cost and time constraints, it is not always possible to characterize the SEE response of components to thermal neutrons, which is often regarded as negligible for components without borophosphosilicate glass (BPSG). Nevertheless, as recent studies show, the sensitivity of deep sub-micron technologies to thermal neutrons has increased owing to the presence of Boron 10 as a dopant and contact contaminant. The very large thermal neutron fluxes relative to high-energy hadron fluxes in some of the heavily shielded accelerator areas imply that even comparatively small thermal neutron sensitivities could dominate the overall Single Event Upset (SEU) rate. For instance, in some locations that host electronic devices, the thermal neutrons fluence can be up to 15 times larger than that of the high-energy hadron. For this reason, in this work I explore the option of measuring the thermal neutron sensitivity through high-energy mixed field irradiations, in conditions with different ratios between the thermal and high-energy hadron fluxes. I studied SEU and SEL SRAM cross sections using the Cern High energy AcceleRator Mixed-field (CHARM) facility, where a wide variety of accelerator environments can be reproduced by combining different test positions and shielding configurations. The mixed-field radiation environment simulated in the past with the FLUKA Monte Carlo tool was investigated in order to select a location with a large thermal neutron fluence compared with the equivalent high-energy hadron fluence. From this perspective, I selected a location with a strong contribution from thermal and intermediate energy neutrons and I characterized it, by combining FLUKA Monte Carlo simulations and the Radiation Monitor (RadMon) measurements. In order to vary the amount of thermal neutrons in the selected position, I designed and built a box of boron carbide, a material that has a high capture cross section for thermal neutrons. After preliminary FLUKA simulations to outline the spectra outgoing the boron carbide absorber, I carried out the RadMon tests-analysis with the purpose of experimentally verifying the results. The former evidences that a large portion of the neutron spectra is fully absorbed below 1 eV and partially cut until 0.01 MeV, while hardly affecting the high-energy flux. Once the neutron test-position was calibrated, I tested and studied the upset and latch-up sensitivities of different SRAM memories to thermal neutrons and high-energy hadron. This investigation was made with differential measurements using the boron carbide box as a thermal neutrons absorber. One of the tested components was the ESA SEU Monitor, an SRAM-based radiation detector employed to prove the effectiveness of the differential approach and to assess the beam spatial uniformity. Moreover, to benchmark the cross sections results retrieved on the neutron-dominated position at CHARM, I tested the same memories in two facilities in Grenoble (France): a 14 MeV mono-energetic neutrons source and a reactor providing a thermal neutron spectrum for testing electronics. Since 14 MeV neutron beams are typically more accessible and cost-efficient than several hundred MeV protons at cyclotron facilities, this work also evaluates their possible use for deriving the saturation cross section, representative of the high-energy hadron response of candidate components. Furthermore I worked on an Americium-Beryllium neutron source at CERN to assess its possible use for SEU testing when CHARM is not available. After the calibration of the facility carried out with FLUKA simulations and ESA Monitor experimental measurements, I proved its potential employment for future tests. Finally, I compared the mono-energetic neutron beam test approach results against those at CHARM, obtaining a highly satisfactory agreement between the memories cross sections measured in these facilities. In this way, CHARM is shown to successfully reproduce the conditions to obtain an SEE qualification compatible with that at standard mono-energetic facilities

Étude expérimentale et simulation des événements singuliers induits par des neutrons issus d’accélérateurs et impacts sur la qualification

Electronic components and systems operating in the Large Hadron Collider (LHC) accelerator at CERN are subjected to a particle radiation environment, mainly composed of neutrons with energies ranging from thermal up to a few GeV.This thesis aims at determining the impact of thermal and intermediate energy neutrons (0.2-20 MeV) with respect to highly energetic particles on the Single Event Upset (SEU) and Latch-up (SEL) rates induced in advanced Commercial-Off-The-Shelf (COTS) components, typically used in accelerator systems.The radiation environments of several locations in the accelerator are described, characterized and compared to the ground level and atmospheric spectra at varying altitude.Inelastic and elastic nuclear processes through which neutrons of different energies induce Single Event Effects (SEEs) are extensively studied through Monte Carlo simulations, in terms of produced secondaries and their properties.Electronic components are experimentally characterized in monoenergetic and spallation facilities, and the SEE cross sections benchmarked with Monte Carlo simulations, where the energy deposition is associated with the SEE probability.From these studies, the SEE rate is estimated for accelerator and atmospheric applications and put in the context of the qualification approaches at component and system level used in these environments. The qualification implications are derived from the combined simulation and experimental study, in order to determine the approach for quantifying the thermal and intermediate energy neutron contributions. Several solutions are proposed aiming towards a radiation hardness assurance (RHA) methodology based on mixed-field and monoenergetic experimental results, besides the consolidated knowledge of the operational environments and the associated effects.Les composants et systèmes électroniques qui fonctionnent dans l'accélérateur Grand collisionneur de hadrons (LHC) au CERN sont soumis à un environnement radiatif à champ mixte, composé principalement de neutrons ayant des énergies allant des énergies thermiques jusqu'à quelques GeV. Cette thèse vise à déterminer l'impact des neutrons thermiques et d'énergie intermédiaire (0.2-20 MeV) par rapport aux particules hautement énergétiques sur les taux de Single Event Upset (SEU) et de Latch-up (SEL) induits dans des composants COTS (Commercial-Off-The-Shelf), généralement utilisés dans les systèmes d'accélérateurs.Les environnements radiatifs dans l'accélérateur sont décrits en différents endroits. Ils sont caractérisés et comparés aux spectres au niveau du sol et de l'atmosphère à différentes altitudes. Les processus nucléaires inélastiques et élastiques par lesquels des neutrons de différentes énergies induisent des événements singuliers (SEE) sont largement étudiés par le biais de simulations Monte Carlo, en termes de particules secondaires produites et de leurs propriétés. Les composants électroniques sont caractérisés expérimentalement dans des installations mono-énergétiques et de spallation, et les sections efficaces aux SEE sont comparées avec les simulations Monte Carlo, pour lesquelles le dépôt d'énergie est associé à la probabilité de SEE.À partir de ces études, le taux des SEE est estimé pour des applications d'accélérateur et atmosphérique et mis dans le contexte des approches de qualification au niveau des composants et des systèmes utilisés dans ces environnements. Les implications de qualification sont dérivées de la simulation et de l'étude expérimentale combinées. Cela permet de déterminer l'approche pour quantifier les contributions des neutrons thermiques et d'énergie intermédiaire. Au final, la méthodologie permet tenue des composants aux radiations (RHA) en se basant sur des résultats expérimentaux à champ mixte et mono-énergétiques et des connaissances consolidées de l'environnement opérationnel et des effets associés

Experimental and Simulation Study of Neutron-Induced Single Event Effects in Accelerator Environment and Implications on Qualification Approach

Electronic components and systems operating in the Large Hadron Collider (LHC) accel- erator at CERN are subjected to a mixed-field radiation environment, mainly composed of neutrons with energies ranging from thermal up to a few GeV. This thesis aims at determining the impact of thermal and intermediate energy neutrons (0.2-20 MeV) with respect to highly energetic particles on the Single Event Upset (SEU) and Latch-up (SEL) rates induced in ad- vanced Commercial-Off-The-Shelf (COTS) components, typically used in accelerator systems. The radiation environments of several locations in the accelerator are described, character- ized and compared to the ground level and atmospheric spectra at varying altitude. Inelastic and elastic nuclear processes through which neutrons of different energies induce Single Event Effects (SEEs) are extensively studied through Monte Carlo simulations, in terms of produced secondaries and their properties. Electronic components are experimentally characterized in monoenergetic and spallation facilities, and the SEE cross sections benchmarked with Monte Carlo simulations, where the energy deposition is associated with the SEE probability. From these studies, the SEE rate is estimated for accelerator and atmospheric applications and put in the context of the qualification approaches at component and system level used in these environments. The qualification implications are derived from the combined simulation and experimental study, in order to determine the approach for quantifying the thermal and intermediate energy neutron contributions. Several solutions are proposed aiming towards a radiation hardness assurance (RHA) methodology based on mixed-field and monoenergetic experimental results, besides the consolidated knowledge of the operational environments and the associated effects