Synergistic effects of total ionizing dose and displacement damage on bipolar and BiCMOS circuits in high energy physics applications

openAt CERN, the functionality of the accelerator complex depends significantly on the reliability of electronic control devices. The environment inside the structures hosting particle accelerators is particularly hostile to electronic components due to the presence of ionizing and non-ionizing radiation, as well as high-energy particles, which degrade the performance of devices. Ionizing radiation induces charge trapping in gate oxide and dielectric materials with possible formation of interface traps at the oxide/semiconductor interface. Non-ionizing radiation, such as neutrons, displaces semiconductor atoms within the crystal lattice, thus generating punctual or cluster of defects. Additionally, high-energy particles induce the formation of charge in sensitive regions of devices, which can lead to single-event effects. In these challenging environments, the high demand for components and the prohibitive cost of rad-hard solutions have led to the widespread use of Commercial Off-The-Shelf (COTS) systems. However, these systems must be qualified to ensure their tolerance to radiation. In certain applications, bipolar devices are preferred over CMOS devices due to their resilience to latchup, a destructive event that compromises the functionality of CMOS systems. Nonetheless, bipolar devices suffer from displacement damage, which is typically negligible in MOSFETs. Consequently, the combination of ionizing and non-ionizing radiation can produce synergistic effects in bipolar devices, where the overall damage cannot be predicted by simply summing the individual contributions of each radiation type. These effects complicate the qualification of highly distributed systems within the Large Hadron Collider (LHC), as radiation levels vary significantly in terms of the ratio between displacement damage and total ionizing dose. Within this context, the thesis aims to investigate the synergistic effects of ionizing and non-ionizing radiation on various types of bipolar and BiCMOS integrated circuits. It also explores the impact of these effects on the radiation qualification of components for highly distributed systems in the LHC

Machine and Deep Learning Applications for Inventory Replenishment Optimization

openInventory replenishment is the process of obtaining the items, components, and raw materials required to make and sell products. It guarantees that items and resources are acquired and delivered in an efficient and timely manner. Poorly managed inventory replenishment can have a severe influence on customers and the overall health of a business, which may result in lost revenue, reduced profits and damaged reputation. Implementing the correct inventory replenishment helps manufacturers and sellers in avoiding major issues such as stock-outs, delayed deliveries and overstocking. Accuracy of forecasting is therefore crucial to retailers' profitability. Fashion businesses need precise and accurate sales forecasting tools to prevent stock-outs and maintain a high inventory fill rate. This thesis navigates the complex landscape of fashion retail forecasting, addressing the challenges posed by intermittent time series data and stock management. Advanced forecasting models have been implemented to account for the intermittent nature of fashion product demand, resulting in predictions more accurate and reliable.The study extends also to stock replenishment strategies, emphasizing the importance of the reorder point, the Cycle Service Level and the safety stock. Lastly, it culminates in the development of a replenishment algorithm aimed at reducing stock-outs, which is a modified version of the Periodic Review Policy: Order-Up-To-Level, now tailored to the sporadic nature of intermittent demand.Inventory replenishment is the process of obtaining the items, components, and raw materials required to make and sell products. It guarantees that items and resources are acquired and delivered in an efficient and timely manner. Poorly managed inventory replenishment can have a severe influence on customers and the overall health of a business, which may result in lost revenue, reduced profits and damaged reputation. Implementing the correct inventory replenishment helps manufacturers and sellers in avoiding major issues such as stock-outs, delayed deliveries and overstocking. Accuracy of forecasting is therefore crucial to retailers' profitability. Fashion businesses need precise and accurate sales forecasting tools to prevent stock-outs and maintain a high inventory fill rate. This thesis navigates the complex landscape of fashion retail forecasting, addressing the challenges posed by intermittent time series data and stock management. Advanced forecasting models have been implemented to account for the intermittent nature of fashion product demand, resulting in predictions more accurate and reliable.The study extends also to stock replenishment strategies, emphasizing the importance of the reorder point, the Cycle Service Level and the safety stock. Lastly, it culminates in the development of a replenishment algorithm aimed at reducing stock-outs, which is a modified version of the Periodic Review Policy: Order-Up-To-Level, now tailored to the sporadic nature of intermittent demand

Study of material activation in nanosatellites for gamma-ray astrophysics

For satellite gamma astrophysics, new missions have been proposed to investigate the Compton regime. The predecessors demonstrated as material activation is an important problem at these energies, because of the irradiation received from cosmic rays. We have quantified the material activation in a nanosatellite Compton in LEO with some Monte Carlo simulations. In this work we focused on primary protons, estimating the produced radioisotopes and in particular those that give gamma rays in out energetic range.ope

SEDIMENTOLOGICAL ANALYSIS OF DEEP WATER, UPSLOPEMIGRATING CROSS-BEDDED DEPOSITS IN A DISTALLY STEEPENED CARBONATE RAMP (MENORCA, BALEARIC ISLANDS, SPAIN)

The upper Miocene units cropping out along the southern coast of the Island of Menorca (Balearic Islands, Spain), are mainly represented by two carbonate depositional systems: an early Tortonian distally steepened ramp (Lower Bar Unit) and an upper Tortonian – lower Messinian reef-rimmed platform prograding complex (Reef Complex). Within the distally steepened ramp, Pomar et al. (2002) distinguished four facies belts: fan-delta conglomerates passing upwards to bioturbated packstones (inner ramp), cross-bedded grainstones (middle- ramp), clinostratified rhodolithic rudstone (ramp slope) and fine-grained wackestonepackstone with planktonic foraminifera (outer ramp). The backset-bedded units analysed in this work are placed at the transition between toe-of-slope and outer ramp sediments, below the wave-base-level. They infill the axial depression of large slide/slump scars. These scars truncate the gently, 10°- 12° basinward dipping, slope-to-outer ramp clinoforms. Backset beds are cross-bedded forms that dip against the direction of flow of the depositing currents, therefore they present foresets migrating upcurrent (Gary et al., 1972). These sedimentary structures are well known and largely described on the foreset and toeset of Gilbert-type fan delta (Postma, 1984; Massari, 1984, 1996; Nemec, 1990). In carbonate depositional systems these type of bedforms are rarely found and only little described. The backset-bedded units, here analysed, are channel-like, wedge-shaped, 10-12 m thick, pinching out landward and extend laterally for tens of meters. Each unit is formed by several amalgamated set of backset beds, 40 cm to 2 m thick. These units are mainly conglomerates composed by bioclastic coarse-grained grainstone to rudstone. Large components are rhodoliths, bivalves, skeletal and ooid-rich pebbles to boulders, gastropods and corals. Matrix is of a bioclastic coarse-grained sand to fine gravel, made of fragments of bivalves, gastropods, rhodoliths, bryozoans, algae, echinoids, loose ooids and planktonic and benthic foraminifera. Ooids are locally very abundant both in matrix and as main components of pebbles. Pebbles are mainly flattened, elongated, of average size 6-8 cm (a-axis) and sometimes have mollusc borings on their surface: large (20-30 cm) rounded and spherical boulders are locally present. Intergranular and intergranular porosity is very high, cementation low and dolomitization patchy. Foreset laminae dip upslope with varying angles ranging from almost horizontal to 30°; higher angles are mostly found in the basinward part of the unit. Lamination is underline by the orientation along laminae of coarser components especially of bivalves, pebbles and rhodoliths. Grain-size distribution has a particular trend that shows a progressive decrease in size landwards and upwards. Sorting may noticeably vary being high or absent in different bodies. The lower boundary of the backset-bedded units is represented by scour surfaces which, on a parallel-to-flow section are almost concordant with the stratification below, while on a perpendicular-to-flow section are concave-up shaped, presenting the very steep walls. The study of different outcrops along the coast evidenced some important variation in components: moving northward composition changed from almost completely rhodolithic-dominated to rhodolith-bivalve-ooid-pebble-dominated to bivalve-ooid-pebble-dominated with first findings of corals. Upslope bedform migration has been explained as forming when a supercritical flow encounters a local obstruction or a local break on the slope, and a hydraulic jump may occur within the flow, upcurrent from the obstruction. Sediment will be therefore deposited at the obstruction forming an up-flow-dipping slipface that will tend to accrete and migrate in the upflow direction (Nemec, 1990 and reference therein). The backset deposits of Menorca are found in deep-water settings but they are composed of shallow-water sediment. The formation of these backset beds is interpreted to be related to high energy storm-events able to remove sediment from shallow water and to transport it into deeper position. The sediment-rich outgoing flows channalized and accelerated along slide-scar axis, eroding and rapidly infilling up-slope the scours. In this portion of the ramp preservation potential is higher thanks to sediment deposition which buries and preserves these structures. The repetitive occurrence of backset bedded units within the outer-ramp sediments and the progressive variation in composition suggest that those processes where probably active at the transition between the ramp and the reef systems. Therefore the formation of these sedimentary structures is interpreted to be strictly link to concurrence of peculiar morphological features, hydrodynamic energy and grain-size availability. Computational fluid dynamic (CFD) numerical simulation have been performed as an integrated part of this work to improve the understanding of the development of hydraulic jumps within concentrated density flows. The simulated parameters do not refer to the example of Menorca but to turbidity currents for which finer-grain size (sand-size) have been used in a smaller-scale topography compared to the one studied in outcrop. The work presented proposes some new stating points for further simulations to constrain more precisely the main parameters controlling and determining the occurrence of a hydraulic jump and the consequent deposition of sediment with backset bedding

Search for a Josephson-like effect in the 116Sn + 60Ni system

openThe pairing interaction, responsible for the two-nucleon correlation, plays a fundamental role in defining the low-energy spectra of atomic nuclei and the properties of their ground state. The effect of pairing correlations in the reaction dynamics can be explored by using heavy-ion reactions, in particular those involving a transfer of few nucleons. In this context, an interesting analogy between the nuclear pairing and the Cooper pairing in superconductors can be investigated through heavy-ion collisions, focusing on nucleon-pair transfer and searching for a possible effect, predicted by a BCS-like theory applied to nuclei: the Josephson Effect. The idea was already suggested in the ’70s, but only recently more quantitative calculations, assisted by promising experimental results, revived the interest on the subject and ignited a more systematic research. The transfer of neutron Cooper pairs was therefore studied through the interaction between two superfluid nuclei, 116Sn and 60Ni, using the Advances Gamma-Ray Tracking Spectrometer AGATA and the large-acceptance magnetic spectrometer PRISMA at Legnaro National Laboratorries, INFN. The work presented in this Master Thesis includes the analysis of the data obtained from the PRISMA magnetic spectrometer and preliminary results for the γ-ray spectra from the AGATA array.The pairing interaction, responsible for the two-nucleon correlation, plays a fundamental role in defining the low-energy spectra of atomic nuclei and the properties of their ground state. The effect of pairing correlations in the reaction dynamics can be explored by using heavy-ion reactions, in particular those involving a transfer of few nucleons. In this context, an interesting analogy between the nuclear pairing and the Cooper pairing in superconductors can be investigated through heavy-ion collisions, focusing on nucleon-pair transfer and searching for a possible effect, predicted by a BCS-like theory applied to nuclei: the Josephson Effect. The idea was already suggested in the ’70s, but only recently more quantitative calculations, assisted by promising experimental results, revived the interest on the subject and ignited a more systematic research. The transfer of neutron Cooper pairs was therefore studied through the interaction between two superfluid nuclei, 116Sn and 60Ni, using the Advances Gamma-Ray Tracking Spectrometer AGATA and the large-acceptance magnetic spectrometer PRISMA at Legnaro National Laboratorries, INFN. The work presented in this Master Thesis includes the analysis of the data obtained from the PRISMA magnetic spectrometer and preliminary results for the γ-ray spectra from the AGATA array

West Nile virus: the Italian national transplant network reaction to an alert in the north-eastern region, Italy 2011

We report four cases of West Nile virus (WNV) transmission following a single multiorgan donation in north-eastern Italy. The transmissions were promptly detected by local transplant centres. The donor had been tested for WNV by nucleic acid amplification test (NAT) prior to transplantation and was negative. There were no detected errors in the nationally implemented WNV safety protocols

The symbolic power of the state: inheritance disputes and litigants' judicial trajectories in Cotonou

peer reviewedOver the last 10 years, scholars have started to focus on African states’ bureaucracies by investigating public servants’ relationships with the state, their professional ethos, how they appropriate reforms, and the way they interact with citizens. With inheritance disputes as a focal point, this article highlights the users’ perspective—which is often overlooked—and asks how litigants in Cotonou (Benin) see the state, appropriate legal reforms, and use the courts. It shows that citizens, despite a general sense that the court system is corrupt and ineffective, continue to use it because state institutions convey a form of authority that allows them either to legitimize or challenge family decisions in inheritance matters

Cobalt(I)-catalyzed regioselective allylic alkylation reactions of tertiary allyl carbonates

Catalysis plays a central role in developing environmentally friendly and efficient chemical processes for the synthesis of chemicals from abundant and renewable feedstocks. On the other hand, many relevant industrial catalytic processes, such as hydrogenation, olefin metathesis and cross-coupling reactions, uses noble transition metals (Pd, Rh, Ir, Ph), which are low abundand, relatively toxic and associated with high costs. To address these sustainability concerns, there has been a resurgence in the use of first-row transition metals, commonly referred to as base metal catalysts (Mn, Fe, Co, Ni), as greener alternatives. Among these metals, cobalt has been widely used in organic synthesis. Currently, cobalt-catalyzed methods for carbon-carbon bond formation are gaining attention as environmentally benign alternatives to methods involving its heavier congeners, Rh and Ir. Low valent cobalt(I) species are often proposed as the active catalytic species, which are formed in situ either through reduction through metal reductants (Zn or Mn) or using photoredox catalysts in reductive quenching cycles. However, for many cobalt-catalyzed reactions, the complete mechanistic scenario remains unclear, with reaction development often relying on empirical screening of catalysts and reaction conditions rather than a more rational design. In this context, previously reported cobalt-catalyzed allylic alkylation methods, which used allyl carbonates as electrophiles under reductive conditions, efficiently afforded branched alkylated products with high regioselectivity. However, the mechanistic understanding of these reactions was very narrow. Thus, the objective of this thesis was to develop allylic alkylation reactions by using well-defined cobalt(I) complexes, and shed light into the mechanism. Thus, a family of well-defined cobalt(I) chloride catalysts bearing commercially available (bis)phosphino ligands was synthesized and tested for their catalytic performance in allylic alkylation reactions. In addition, the isolation of well-defined cobalt(I) complexes facilitates the identification of the active catalytic species, thus facilitating the mechanistic investigations. Thus, a combination of mechanistic experiments and theoretical studies was performed to further elucidate the underlying catalytic cycle. During this work, the synthesis and characterization of a family of well-defined Co(I) complexes bearing commercially available (bis)phosphine ligands was performed. Complexes (P,P)CoCl(PPh3) were prepared in high yields by direct coordination of the (bis)phosphine ligands to the cobalt(I) precursor (PPh3)3CoCl. Moreover, (P,P)CoCl(PPh3) are excellent precursors to synthesize in high yields the corresponding cationic Co(I) arene complexes, [(P,P)Co(η6-C7H8)][BArF4], by reaction with Na[BArF4] in aromatic solvent. The development of a straightforward synthesis for well-defined cobalt(I) complexes has facilitated the investigation of their catalytic activity in allylic alkylation reactions. Thus, the allylic alkylation of tertiary allyl carbonates using 1,3-diesters and 1,3-ketoesters as nucleophiles catalyzed by cobalt(I) complexes under mild conditions was explored. The addition of NaBF4 as additive was crucial for observing moderate to good yields of the alkylated product. The additive might have a dual role, it could facilitate the formation of the cationic cobalt(I) complex by abstracting the chloride or, the sodium cation, could also coordinate to the carbonyl group of the carbonate and increase the electrophilicity of the carbonyl group. Second, in all cases, the branched regioisomer was observed as the major product, which indicates that the reaction is high regioselective. Third, the bite angle of the Co(I) catalytic has an impact on the catalytic activity: Co(I) complexes with a smaller bite angles exhibited higher catalytic activity compare to the one with a larger bite angles. The best catalysts showed to be (dppp)Co(PPh3). The developed base-free methodology showed a broad functional group tolerance, although some limitations were encountered, allyl carbonates bearing azide, aldehyde and pyridine groups are not active in the transformation. In addition, the presence of an ester group at the nucleophile is a prerequisite for achieving the alkylation reaction. Notably, the developed method allows for the allylic alkylation of tertiary allyl carbonates in the presence of secondary ones. This unusual selectivity is complementary not only to the Tsuji-Trost reaction, but also to the dual cobalt/organophotoredox visible light allylic alkylation method reported previously. This difference in selectivity between thermal and photochemical conditions suggests a different catalytic cycle. Mechanistic investigations in combination with theoretical calculations using DFT methods support a Co(I)/Co(III) catalytic cycle for the developed cobalt(I)-catalyzed allylic alkylation reaction. The reductive elimination step at the -allylcobalt(III) is the regioselective determining step, indeed the calculated energy for the transition state that leads to the branched product is lower in energy than the transition state leading to the linear product. NBO analysis Natural Bond Orbital (NBO) analysis suggests that differences on the non-covalent interactions at the two transition states are crucial for the regioselective reductive elimination step, being more favorable for the transition state towards the branched product. This work contributed in the field of Co(I)-catalyzed allylic alkylation reactions, shedding light on the mechanism, on the selectivity and on the development of novel Co(I)-catalyzed allylic alkylation reactions. Future perspectives could be the synthesis and characterizations of a family of well-defined Co (0) complexes for the regioselective allylic alkylations of secondary allyl carbonates