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Simulation of optical observables for space missions to small bodies
Get PDFThe navigation of deep space spacecraft requires accurate measurement of the probe’s state and attitude with respect to a body whose ephemerides may not be known with good accuracy. The heliocentric state of the spacecraft is estimated through radiometric techniques (ranging, Doppler, and Delta-DOR), while optical observables can be introduced to improve the uncertainty in the relative position and attitude with respect to the target body. In this study, we analyze how simulated optical observables affect the estimation of parameters in an orbit determination problem, considering the case of the ESA’s Hera mission towards the binary asteroid system composed of Didymos and Dimorphos. To this extent, a shape model and a photometric function are used to create synthetic onboard camera images. Then, using a stereophotoclinometry technique on some of the simulated images, we create a database of maplets that describe the 3D geometry of the surface around a set of landmarks. The matching of maplets with the simulated images provides the optical observables, expressed as pixel coordinates in the camera frame, which are fed to an orbit determination filter to estimate a certain number of solve-for parameters. The noise introduced in the output optical observables by the image processing can be quantified using as a metric the quality of the residuals, which is used to fine-tune the maplet-matching parameters. In particular, the best results are obtained when using small maplets, with high correlation coefficients and occupation factors
A Unified Model for XVA, including Interest Rates and Rating
Get PDFWe start in Chapter 2 to investigate linear matrix-valued SDEs and the Itô-stochastic Magnus expansion.
The Itô-stochastic Magnus expansion provides an efficient numerical scheme to solve matrix-valued
SDEs. We show convergence of the expansion up to a stopping time τ and provide an asymptotic estimate of the cumulative distribution function of τ. Moreover, we show how
to apply it to solve SPDEs with one and two spatial dimensions by combining it with the method of lines with high accuracy. We will see that the Magnus expansion allows us to use GPU techniques leading to major performance improvements compared to a standard Euler-Maruyama scheme.
In Chapter 3, we study a short-rate model in a Cox-Ingersoll-Ross (CIR) framework for
negative interest rates. We define
the short rate as the difference of two independent CIR processes and add a deterministic shift to guarantee a perfect fit to the market term structure. We show how to use the Gram-Charlier expansion to efficiently calibrate the model to the market swaption surface and price Bermudan swaptions with good accuracy.
We are taking two different perspectives for rating transition modelling. In Section 4.4, we study inhomogeneous
continuous-time Markov chains (ICTMC) as a candidate for a rating model with deterministic rating transitions. We extend this model by taking a Lie group perspective in Section 4.5, to allow for stochastic rating transitions.
In both cases, we will compare the most popular choices for a change of measure technique and show how to efficiently calibrate both models to the available historical rating data and market default probabilities.
At the very end, we apply the techniques shown in this thesis to minimize the collateral-inclusive Credit/ Debit Valuation Adjustments under the constraint of small collateral postings by using a collateral account dependent on rating trigger
Development of sexing systems functional to mass production of Aedes albopictus sterile males
Get PDFAedes albopictus is a vector able to transmit several arboviruses. Due to its high impact on human health, it is important to develop an efficient control strategy for this pest. Nowadays, control based on chemical insecticides is limited by the number of available active principles and the occurrence of resistance. A valuable alternative to the conventional control strategies is the sterile insect technique (SIT) which relies on releasing sterile males of the target insect. Mating between wild females and sterile males results in no viable offspring. A crucial aspect of SIT is the production of a large number of sterile males with a low presence of females that can bite and transmit viruses.
The present thesis aimed to find, implement and study the most reliable mechanical sex sorter and protocol to implement male productivity and reduce female contamination. In addition, I evaluated different variables and sorting protocols to enable female recovery for breeding purposes. Furthermore, I studied the creation of a hyper-protandric strain potentially able to produce only males. I also assessed the integration of artificial intelligence with an optical unit to identify sexes at the adult stage. All these applications helped to realise a mass production model in Italy with a potential weekly production of 1 million males.
Moreover, I studied and applied for aerial sterile male release in an urban environment. This technology could allow the release of males in a wide area, overcoming environmental and urban obstacles. However, the development and application of drone technologies in a metropolitan area close to airports, such as in Bologna area, must fit specific requirements.
Lastly, at Réunion Island, during a Short Term Scientific Mission France (AIM-COST Action), Indian Ocean, I studied the Boosted SIT application. Coating sterile males with Pyriproxyfen may help spread the insecticide into the larval breeding sites
Rotational and ro-vibrational analyses of molecules of astrochemical interest
Get PDFThe rotational and ro-vibrational spectroscopy analysis of selected molecules of astrophysical importance, namely formaldehyde, mono-deuterated hydrogen sulfide, cyanoacetylene, deuterated cyanoacetylene, aminoacetonitrile, allylimine, and 2-aza-1,3-butadiene, has been presented in this thesis. For formaldehyde and mono-deuterated hydrogen sulfide, which are well-known interstellar molecules, a detailed Measured Active Rotational–Vibrational Energy Levels (MARVEL) analysis has been performed. For both of them, the MARVEL approach has been used to accurately derive the rotational and ro-vibrational energy levels from the experimental data available in the literature combined with new millimeter-wave measurements. Overall, the MARVEL analysis span a huge frequency range, from millimeter-wave to infrared (IR). For allylimine and 2-aza-1,3-butadiene, the pure rotational spectrum has been extended to the millimeter-wave region. The outcome of these two studies is the derivation of very accurate spectroscopic parameters that allow the accurate prediction of their rotational transitions over a large frequency range. For allylimine, this line catalog allowed the tentative detection of two isomers of allylimine (Ta and Ts) towards the G+0.693 molecular cloud. In addition to rotational spectroscopy, high-resolution IR spectra of interstellar molecules play also of pivotal role for the exploration of astromomical objects. For these reasons, high-resolution IR spectra of cyanoacetylene, deuterated cyanoacetylene, and aminoacetonitrile have been investigated. The precise spectroscopic constants of several vibrational excited states of these three molecules have been derived from the assignment of newly recorded IR spectra. Given the fact that all these three molecules are potentially present in Titan’s atmosphere, their ro-vibrational transitions can be considered unvaluable tools for their search, which might also be extended to other planetary atmospheres
Risk assessment to improve food safety along different food chains
Get PDFThe great challenges of today pose great pressure on the food chain to provide safe and nutritious food that meets regulations and consumer health standards. In this context, Risk Analysis is used to produce an estimate of the risks to human health and to identify and implement effective risk-control measures.
The aims of this work were 1) describe how QRA is used to evaluate the risk for consumers health, 2) address the methodology to obtain models to apply in QMRA; 3) evaluate solutions to mitigate the risk.
The application of a QCRA to the Italian milk industry enabled the assessment of Aflatoxin M1 exposure, impact on different population categories, and comparison of risk-mitigation strategies. The results highlighted the most sensitive population categories, and how more stringent sampling plans reduced risk.
The application of a QMRA to Spanish fresh cheeses evidenced how the contamination of this product with Listeria monocytogenes may generate a risk for the consumers. Two risk-mitigation actions were evaluated, i.e. reducing shelf life and domestic refrigerator temperature, both resulting effective in reducing the risk of listeriosis.
A description of the most applied protocols for data generation for predictive model development, was provided to increase transparency and reproducibility and to provide the means to better QMRA.
The development of a linear regression model describing the fate of Salmonella spp. in Italian salami during the production process and HPP was described.
Alkaline electrolyzed water was evaluated for its potential use to reduce microbial loads on working surfaces, with results showing its effectiveness.
This work showed the relevance of QRA, of predictive microbiology, and of new technologies to ensure food safety on a more integrated way. Filling of data gaps, the development of better models and the inclusion of new risk-mitigation strategies may lead to improvements in the presented QRAs
Statistical learning of random probability measures
Get PDFThe study of random probability measures is a lively research topic that has
attracted interest from different fields in recent years. In this thesis, we consider
random probability measures in the context of Bayesian nonparametrics,
where the law of a random probability measure is used as prior distribution,
and in the context of distributional data analysis, where
the goal is to perform inference given avsample from the law of a random probability measure.
The contributions contained in this thesis can be subdivided according to three
different topics: (i) the use of almost surely discrete repulsive random measures
(i.e., whose support points are well separated) for Bayesian model-based
clustering, (ii) the proposal of new laws for collections of random probability
measures for Bayesian density estimation of partially
exchangeable data subdivided into different groups, and (iii) the study
of principal component analysis and regression models for probability distributions
seen as elements of the 2-Wasserstein space. Specifically, for point
(i) above we propose an efficient Markov chain Monte Carlo algorithm for
posterior inference, which sidesteps the need of split-merge reversible jump
moves typically associated with poor performance, we propose a model for
clustering high-dimensional data by introducing a novel class of anisotropic
determinantal point processes, and study the distributional properties of the
repulsive measures, shedding light on important theoretical results which enable
more principled prior elicitation and more efficient posterior simulation
algorithms. For point (ii) above, we consider several models suitable for clustering
homogeneous populations, inducing spatial dependence across groups of
data, extracting the characteristic traits common to all the data-groups, and
propose a novel vector autoregressive model to study of growth
curves of Singaporean kids. Finally, for point (iii), we propose a novel class of
projected statistical methods for distributional data analysis for measures
on the real line and on the unit-circle
Skin as a promising biomatrix for the early detection of misfolded proteins by RT-QuIC in neurodegenerative diseases
Get PDFReal-Time Quaking-Induced Conversion (RT-QuIC) is an ultrasensitive assay capable of detecting pathological aggregates of misfolded proteins in biospecimens. In recent years, efforts have been made to find a more feasible and convenient biomatrix as an alternative to CSF, and skin biopsy may be a suitable candidate. This project aimed to evaluate the diagnostic performance of skin RT-QuIC in 3 different cohorts of patients: 1. Creutzfeldt-Jakob disease (CJD), 2. Lewy body disease (LBD), and 3. Isolated REM sleep behavior disorder (iRBD).
We studied 71 punch skin samples of 35 patients with CJD, including five assessed in vitam, using 2 two different substrates: Bank vole 23-230 (Bv23-230) and Syrian hamster 23-231 (Ha23-231) recombinant prion protein. Skin prion RT-QuIC showed a 100% specificity with both substrates and a higher sensitivity with the Bv23-230 than Ha23-231 (87.5% vs. 65.6%, respectively). Forty-one patients underwent both lumbar puncture (LB) and skin biopsy; CSF and skin RT-QuIC showed a high level of concordance (38/41, 92.7%).
Then, we analyzed samples taken in vitam (n=69) or postmortem (n=49) from patients with Parkinson’s disease (PD), dementia with Lewy bodies (DLB), incidental Lewy body pathology, and neurological controls. Skin α-syn RT-QuIC distinguished LBD patients with an overall accuracy of 94.1% in the two cohorts (sensitivity, 89.2%; specificity, 96.3%). Seventy-nine patients underwent both CSF and skin α-syn RT-QuIC, and the two assays yielded similar diagnostic accuracy (skin, 97.5%; CSF, 98.7%).
Finally, we studied 91 iRBD patients and 41 control. In the skin, RT-QuIC showed a sensitivity of 76.9%, specificity of 97.6%, and 82.0% accuracy. 128 participants (88 patients plus 40 controls) underwent both CSF and skin RT-QuIC. The two protocols showed 99.2% of concordance.
These works confirmed that skin punch biopsies might represent a valid and convenient alternative to CSF analysis for an early diagnosis of prion diseases and LB-related pathologies
Bycatch and discard issues in the Adriatic demersal fisheries
Get PDFCommercial fisheries exploiting the demersal resources of Western Adriatic Sea produce high bycatch and discard rates; the most important are bottom trawls, hydraulic dredges and passive nets. The five papers here published assess these fisheries’ impacts and investigate the potential of specific solutions to promote more sustainable exploitation. Papers I, II, III focused on bottom trawl fishery. Paper I compared the catch performance of the two legal codends by accounting for the entire species community in trawl catches. 50% of the catch in weight and 80% in count numbers consisted of discarded species, highlighting the severe impact of this fishery. Paper II estimated the selectivity of experimental codend having meshes turned 90° (T90) and of traditional diamond mesh codend with same mesh size. The T90 codend improved the size selection for all the target species. Paper III investigated the use of T90 meshes in the extension piece together with a reduction in mesh number at extension circumference. Results revealed that both these changes applied in the extension piece did not improve the selectivity of the main target species. Paper IV focused on hydraulic dredge fishery targeting the striped venus clam by assessing the clams’ size selection process operated by the dredge. 25% of the clams caught were not size selected due to clogging phenomenon in the dredge. The clam length with 50% retention probability was 18.9 mm, highlighting that the additional size selection process of sorting sieve is necessary to land only the legal clams >22 mm. Paper V compared the catch performance of innovative fish pots and of traditional trammel net. A similar catch efficiency between the two gears for the commercial portion was observed, while the trammel net produced significantly more discards in terms of species number and weight. All the results are discussed in fisheries management perspective
Methods and tools to foster territorial approaches for the assessment of food supply chains
Get PDFThe challenges of the current global food systems are often framed around feeding the world's growing population while meeting sustainable development for future generations. Globalization has brought to a fragmentation of food spaces, leading to a flexible and mutable supply chain. This poses a major challenge to food and nutrition security, affecting also rural-urban dynamics in territories. Furthermore, the recent crises have highlighted the vulnerability to shocks and disruptions of the food systems and the eco-system due to the intensive management of natural, human and economic capital.
Hence, a sustainable and resilient transition of the food systems is required through a multi-faceted approach that tackles the causes of unsustainability and promotes sustainable practices at all levels of the food system. In this respect, a territorial approach becomes a relevant entry point of analysis for the food system’s multifunctionality and can support the evaluation of sustainability by quantifying impacts associated with quantitative methods and understanding the territorial responsibility of different actors with qualitative ones.
Against this background the present research aims to i) investigate the environmental, costing and social indicators suitable for a scoring system able to measure the integrated sustainability performance of food initiatives within the City/Region territorial context; ii) develop a territorial assessment framework to measure sustainability impacts of agricultural systems; and iii) define an integrated methodology to match production and consumption at a territorial level to foster a long-term vision of short food supply chains.
From a methodological perspective, the research proposes a mixed quantitative and qualitative research method. The outcomes provide an in-depth view into the environmental and socio-economic impacts of food systems at the territorial level, investigating possible indicators, frameworks, and business strategies to foster their future sustainable development
Studies on women as active subjects of crime in Roman law
Get PDFLa ricerca si prefigge di indagare sulla donna che commette reato nel corso dell’intera esperienza giuridica romana. Attraverso l’analisi delle fonti, con speciale riferimento a quelle letterarie, vengono analizzati i singoli illeciti in cui la donna stessa poteva assumere la qualifica di soggetto attivo, che danno luogo a un nutrito catalogo di fattispecie attinenti alla sfera sessuale, per quanto non manchino casi di maiestas e, più in generale, di cospirazione contro il principe. Nella presente ricerca si tenta dunque di investigare, proprio a partire dalla peculiare condizione riconosciuta alla donna all’interno della società romana, la sua dimensione ‘pubblica’, che sarebbe stata lesa con la commissione dell’illecito giacché la rea, in questo modo, avrebbe sovente compromesso un valore superindividuale, ossia la pudicitia. È proprio la lesione di siffatto principio, tale da assumere un ruolo centrale nel quadro dell’etica sessuale degli antichi romani, a giustificare la repressione degli illeciti femminili nella forma del crimen: non deve dunque meravigliare che la mulier, venuta meno all’onore familiare, sia sanzionata pubblicamente, potendosi intendere i reati dalla stessa commessi alla stregua di ‘attentati alla res publica’.The research aims to investigate the woman who commits a crime during the entire Roman legal experience. Through the analysis of the sources, with special reference to the literary ones, are analyzed the single illicit ones in which the woman herself could assume the qualification of active subject, which give rise to a large catalogue of cases related to the sexual sphere, although there are cases of ‘maiestas’ and, more generally, of conspiracy against the prince. In the present research, therefore, an attempt is made to investigate, starting from the particular condition recognized to women within Roman society, their ‘public’ dimension, which would have been damaged by the commission of the offence since the real, in this way, it would often compromise a superindividual value, namely modesty. It is precisely the violation of such a principle, such as to assume a central role in the sexual ethics of the ancient Romans, to justify the repression of female offences in the form of the crimen: it is therefore no wonder that the mulier, which has failed the family honour, is publicly sanctioned, being understood as crimes committed by the same as ‘attacks on the res publica’