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Studies on optimization problems with dynamically arriving information
Get PDFIn real-time environments like transportation planning, e-commerce, smart manufacturing, or emergency services, dynamically arriving information must be integrated on-the-fly into decision-making. This dissertation proposes effective online algorithms using classical and innovative analytical and computational evaluation methods, performance bounds, and comparisons to optimal solutions. It focuses on two dynamic optimization problems: the Online Order Batching, Sequencing, and picker Routing Problem(OOBSRP) in warehousing and the Traveling Salesman Problem with a Truck and a Drone under Incomplete Information(TSP-DI), for disaster relief. For the OOBSRP with manual and robotic carts, we prove that Reopt is asymptotically optimal with probability one under broad stochastic conditions. From a worst-case perspective, no policy can improve Reopt by more than 50%, as we show its asymptotical two-competitiveness. A computational study validates Reopt’s small gaps to the complete-information optimum (e.g. averaging at most 5% for a cost-minimization objective). A pattern analysis of Complete-Information Optimal Solutions (CIOSs), generated with dynamic programming algorithms, identifies simple algorithmic enhancements – like eliminating waiting, intervention, or strategic relocation – that further reduce costs and delivery times. These findings suggest limited benefits of anticipatory (including AI-based) algorithms in OOBSRP. Conversely, for TSP-DI with dynamically revealing road blockages, we prove that Reopt performs poorly in the worst case, with an exponentially growing competitive ratio. We propose policies delaying deliveries for drone surveillance that are significantly superior in competitive ratio and average results. Scheduling replenishment of battery-limited drones introduces a challenging static subproblem within these policies, which we address with a novel Very Large-Scale Neighborhood Search(VLNS) and an exact method. VLNS efficiently explores exponential-sized neighborhoods in polynomial runtime, making it an attractive subroutine for online policies and metaheuristics. This dissertation underscores the importance of analytical guarantees and comparisons to optima in online algorithm design, as policy effectiveness often diverges from intuition and varies significantly across problems
Reversibility for concurrent memory models
Get PDFReversibility in concurrent programming languages has been extensively studied in message-passing systems, but has not been studied in concurrent shared memory models. In this work, we explore causal consistent reversibility in shared memory models, addressing the challenges of making shared memory reversible, particularly when weak and non-standard memory models are involved. We begin by extending reversible Erlang to handle shared memory constructs, highlighting the difficulties that arise from non-standard memory operations, such as reading entire maps. Next, we propose a structured, two-step approach. First, we introduce a meta-model framework that defines memory models as synchronous products of labeled transition systems (LTSs), incorporating three components: threads, memory, and scheduler. This framework can describe various memory models, including sequential consistency, write buffer, and transactional. Second, we develop a compositional theory to make the product of LTSs reversible, ensuring causal consistency. We apply this theory to a sequential consistency memory model, comparing it to an automatic approach and showing that our method avoids capturing unwanted dependencies
Histological findings in assigned female at birth (AFAB) transgender individuals undergoing testosterone therapy
Get PDFCONTESTO: Il rischio oncologico dell’esposizione al testosterone (T) di organi genitali in transgender AFAB non è noto.
SCOPO: valutazione istologica di utero, cervice, salpingi e ovaia asportati in corso di intervento chirurgico di affermazione di genere (GAS) in AFAB che assumevano testosterone.
MATERIALI E METODI: valutazione dei dati istologici condotta retrospettivamente tramite la consultazione di 187 cartelle cliniche di soggetti transgender AFAB sottoposti a GAS presso la Ginecologia dell’IRCCS Sant’Orsola, Bologna.
RISULTATI: 187 transgender AFAB sono stati sottoposti a isteroannessiectomia bilaterale. Nessun paziente sottoposto a ovariectomia, chemioterapia o radioterapia prima della chirurgia. La mediana della durata di assunzione di T era di 36 mesi (12 mesi-14 anni). 96/187 (51.4%) uteri presentavano endometrio ipoattivo/atrofico, mentre 1 caso di iperplasia senza atipie cellulari è stato identificato (0.5%), 8/187 (4.3%) endometrio polipoide e 4/187 (2.2%) secretivo. Il più comune riscontro istologico cervicale è stata la cervicite cronica (n=174, 93%) associata a metaplasia (n=131,76%). Le salpingi sono risultate indenni in 90/187 (48.1%) casi e con infiammazione cronica in 91/187 (48,7%) casi. La maggior parte delle ovaie analizzate mostravano follicoli in diversi stati di maturazione (n=117, 62.5%). In 20 analisi istologiche sono stati identificati corpi lutei/corpi lutei emorragici (10.7%).
CONCLUSIONI: Nessuna lesione premaligna o maligna è stata riscontrata in questi 187 soggetti che assumevano testosterone fino a un massimo di 168 mesi prima della chirurgia. La presenza di follicoli in vari stadi di sviluppo e di corpi lutei suggerisce la possibilità di cicli ovulatori in corso di terapia con testosterone. I risultati di questo studio confermano la sicurezza dell'uso prolungato di T sugli organi genitali di transgender AFAB. Seppur ancora limitate, le evidenze suggeriscono sempre più la mancanza di necessità assoluta di rimuovere utero e ovaia nei soggetti trasgender in terapia con T con il solo fine di prevenire patologie oncologiche.BACKGROUND: Little is known about the safety of long-term testosterone (T) intake on the genital organs of AFAB transgender individuals.
OBJECTIVES: histological results of genital organs removed during gender- affirming hysteroannexectomy in AFAB-people exposed to long-term T treatment.
METHODS: histological data were collected through retrospective consultation of medical records from 187 AFAB patients which underwent hysterectomy with bilateral salpingo-oophorectomy at the Gynecological Clinic of IRCCS S. Orsola Hospital, Bologna.
RESULTS: 187 AFAB person who had undergone gender affirming surgery (GAS) were included in this analysis. No patient had had ovariectomy, chemotherapy or radiotherapy before GAS. All patients received androgen treatment for a median of 36 months (12 months-14 years). 96/187 (51.4%) uterus presented hypoactive/atrophic endometrium, while endometrial hyperplasia without cellular atypia was identified in 1 case (0.5%%), polypoid endometrium in 8 transmen (4.3%) and secretory endometrium in 4 patients (2.2%). The most frequent cervical histological finding was chronic cervicitis (n=174, 93%) associated with different type of metaplasia (n=131, 76%). The majority of tube tissue was uninjured (n=90, 48.1%) or shows chronic inflammation (n=91, 48.7%). The majority of ovarian tissue shows follicles in various stages of maturation (n=117, 62.5%). In 20 histologic analyses has been identified corpus luteum/ hemorrhagic corpus luteum (10.7%).
CONCLUSIONS: No case of premalignant or malignant pathology was found in these 187 subjects who took T for a maximum of 168 months before surgery. We found ovaries with follicles at various stages of maturation including corpus luteum, suggesting the possibility of ovulatory cycles during T therapy. In conclusion, the results of our study confirm the safety of long-term T administration in transgender AFAB subjects on genital organs. Although limited, evidence is growing on the lack of an absolute necessity of removal of uterus and ovaries to prevent cancer in transgender people on T, unless requested by the subject
Endometriosis related ovarian cancer
Get PDFIl carcinoma ovarico correlato all'endometriosi è un argomento poco esplorato caratterizzato dalla coesistenza di carcinoma ovarico ed endometriosi. Lo scopo di questo studio è individuare le differenze tra il carcinoma ovarico senza endometriosi (non-EROC), il carcinoma ovarico associato all'endometriosi (EAOC) caratterizzato da carcinoma ovarico ed endometriosi senza una transizione istologica e il carcinoma ovarico correlato all'endometriosi (EROC) con transizione istologica. Si tratta di uno studio osservazionale, prospettico, monocentrico. Novantaquattro pazienti sono state arruolate da novembre 2021 a giugno 2023. I criteri di inclusione erano la diagnosi istologica di carcinoma ovarico, l'esecuzione di ecografia e chirurgia nel centro, un'età compresa tra 18 e 90 anni e il consenso informato scritto. Delle 94 pazienti, 48 (51%) hanno ricevuto una diagnosi di carcinoma ovarico non-EROC, 17 (18%) di EAOC e 29 (31%) di EROC. L'età alla diagnosi era inferiore in EROC ed EAOC rispetto a non-EROC. Due caratteristiche ecografiche differenziavano EROC ed EAOC da non-EROC: la presenza di una lesione unilaterale (66,7% e 69% dei casi contro il 41,3%) e l'assenza di liquido libero nel Douglas (69% e 88,2% contro il 52,1%). Lo spessore endometriale era maggiore in EROC rispetto ad EAOC e non-EROC; infatti, la patologia dell'endometrio era più frequente in EROC (48% dei casi) rispetto ad EAOC e non-EROC (17,6% e 10,5%). Il CA 19.9 era più elevato in EROC (media di 756 U/ml), mentre negli altri due gruppi era più frequentemente nella norma (<30 U/ml).
Lo stadio FIGO alla diagnosi era iniziale (I-II) nel 75,8% di EROC, nel 29,4% di EAOC e nel 25% di non-EROC. Sono state osservate diverse caratteristiche cliniche ed istopatologiche in EROC, EAOC e non-EROC. EAOC appare come un'entità distinta dagli altri due gruppi e talvolta mostra somiglianze con EROC, in altri casi con non-EROC.Endometriosis related ovarian cancer is an underexplored topic characterized by the coexistence of ovarian carcinoma and endometriosis. The aim of this study is to find differences between ovarian carcinoma without endometriosis (non-EOC), endometriosis-associated ovarian carcinoma (EAOC) characterized by ovarian cancer and endometriosis without a histological transition and endometriosis-related ovarian carcinoma (EROC) with histological transition.
This is an observational, prospective, monocentric study. 94 patients were enrolled from November 2021 to June 2023. Inclusion criteria were histological diagnosis of ovarian carcinoma, ultrasound and surgery performed in the center, age between 18 and 90 years, written informed consent.
Out of 94 patients, 48 (51%) were diagnosed with non-EOC, 17 (18%) with EAOC and 29 (31%) with EROC. Age at diagnosis was lower in EROC and EAOC (57 years and 61 years) compared to non-EOC (65 years). Two ultrasound features differentiated EROC and EAOC from non-EOC: the presence of a unilateral lesion (66.7% and 69% of cases vs 41.3%) and the absence of free fluid in the pouch of Douglas (69% and 88.2% vs 52.1%). The endometrial thickness was greater in EROC (mean 8 mm) compared to EAOC and non-EOC (<5 mm), in fact endometrial pathology was more frequent in EROC (48% of cases) compared to EAOC and non-EOC (17.6% and 10.5%). CA 19.9 was higher in EROC (mean 756 U/ml) while in the other two group it was in range (<30 U/ml). Most common histotypes in EROC were clear cell, endometrioid and mesonephric-like adenocarcinomas. FIGO stage at diagnosis was initial (I-II) in 75.8% of EROC, 29.4% of EAOC and 25% of non-EOC.
Different clinical and histopathological characteristics were observed in EROC, EAOC, and non-EOC. EAOC appears as a distinct entity and sometimes it shows similarities with EROC, in other instances with non-EOC
Beyond pairwise interaction: the cubic mean-field Ising model
Get PDFThe system under consideration comprises Ising spins, a homogeneous magnetic field, and a constant two-spin interaction, augmented by a constant three-spin interaction term. Employing large deviation methods, this thesis explores the thermodynamic properties of the system. The equilibrium measure for large volumes exhibits three pure states when the magnetic field is absent, corresponding to phases of the system, encompassing two with opposite magnetisation and an unpolarized state with zero magnetisation, converging at the critical point. Analysis of the system with three-spin interaction and an external field reveals two coexistence curves, indicative of two distinct second-order phase transitions contingent on the interaction parameter domain. The critical exponents of the magnetic order parameter are calculated in all directions of the phase space and show their agreement with the mean-field universality class. While the Central Limit Theorem holds for a suitably rescaled magnetization, its violation of the typical quartic behaviour appears at the critical point.
Furthermore, the thesis solves the inverse problem for the model, reconstructing the system's free parameters from configuration data generated according to the model's distribution. The robustness of this inversion procedure is tested within both unique solution regions and regions with multiple thermodynamic phases. Lastly, a multi-populated system with three-spin interaction is solved, serving as a paradigm for modelling complex systems comprising human and AI agents. Notably, the study underscores that for suitable values of the interaction parameters, arbitrarily small values of the relative size of the AI agents may trigger dramatic changes in the system
Experimental characterization and modeling of GaN-based power devices reliability
Get PDFPower electronics plays a fundamental role in enhancing energy efficiency and promoting sustainable development, which is crucial for a more environmentally conscious future. Power electronics deals with the conversion and the control of electric power, using high-efficiency, reliable and even more compact electronic converters based on switching mode semiconductor power devices. In this scenario, GaN-on-Si devices showed capability to operate at high-voltage and -frequency with higher efficiency and comparable cost of the silicon counterparts. Although GaN transistors demonstrate impressive characteristics, there are degradation mechanisms affecting the device performance and reliability that need further investigation.
This PhD dissertation is focused on the identification, characterization, and modeling of the root causes that limit the gate reliability of AlGaN/GaN HEMTs featuring pGaN gate technology, by accelerated life tests and electro-thermal simulations. The thesis main contributions are:
Gate biases, temperatures, and device geometry dependencies of time-dependent gate breakdown (TDGB) in GaN-based power HEMTs with p-type gate under DC stress conditions are analyzed. Two failure mechanisms have been identified, hence, accurate field-acceleration fitting models are adopted to estimate gate lifetime.
Combined experimental/simulation analysis was performed to study the TDGB under pulse stress conditions. Thanks to this investigation, reliability issues introduced by the switching operation have been highlighted.
An extensive analysis on the role of both switching frequency and duty cycle on the TDGB of GaN-HEMTs with Schottky metal to p-GaN gate. Findings of this analysis are useful both for further technology improvement and for GaN-based power circuit designers.
Additionally, storage/release mechanisms within the buffer layers responsible for Ron degradation were investigated by means of back-gating I-DLTS and TCAD simulations. A genetic algorithm has been employed to fit the experiments allowing to understand the work conditions dependence of DRon. Moreover, devices featuring different buffer layers composition are compared, providing useful information for the epi-stack optimization
Impact of 68Ga-PSMA PET/CT in patients with metastatic castration-resistant prostate cancer (mCRPC) treated with enzalutamide
Get PDFBackground We evaluated the impact of 68Ga prostate specific membrane antigen positron emission tomography/computed tomography (68Ga-PSMA PET/CT) in patients treated with enzalutamide as first-line therapy for mCRPC.
Methods In an observational prospective study, 67 consecutive mCRPC patients were treated with enzalutamide in first-line for mCRPC. 68Ga-PSMA PET/CT was performed at baseline, after 1 and 3 months and at progression. We measured the sum of metabolic total volume (SMTV), mean standardized uptake volume (SSUVmean), maximum standardized uptake volume (SSUVmax) and total lesion activity (STLA), which is the product of SMTV and SSUVmean, for a maximum of 20 lesions. These parameters together with PSA level, Eastern Cooperative Oncology Group performance status (ECOG PS), Gleason Score (GS) and age were analyzed by univariate and multivariate Cox regression models as potential predictors of progression-free survival (PFS) and overall survival (OS).
Results 58 mCRPC patients were considered fully evaluable. Median age was 75 years (range, 47-91), ECOG PS was 0 in 47 cases (81%), GS was 8-10 in 36 (62%), the median baseline PSA was 2.66 µg/L (range 0.09-197), median number of lesion was 3. We observed a median SMTV of 73 cm3, median SSUVmax of 44.85, median SSUVmean of 25.80 and median STLA of 59.66. At the median follow-up of 52 months, median PFS was 28.9 months (95% CI 16.3-43.6), median OS was not reached (95% CI 36.8-not reached). In univariate analysis, SSUVmax and STLA were significant for PFS (p=0.015 and p=0.001, respectively) and OS (p=0.026 and p=0.019, respectively), while SSUVmean and number of lesions were significant only for OS (p=0.028 and p=0.004, respectively). On multivariate analysis, STLA only remained significant for PFS (p=0.0004) and OS (p=0.019).
Conclusions: In he assessment of mCRPC by 68Ga-PSMA PET/CT before enzalutamide, STLA appeared the strongest parameter able to predict PFS and OS
Performance and failure of surgically implanted right ventricle to pulmonary artery (RV-PA) conduit in congenital heart disease
Get PDFIntroduction:
Surgical implantation of right ventricle to pulmonary artery (RV-PA) conduit is an important component of congenital heart disease (CHD) surgery but with limited durability and need for re-intervention. Current single center, retrospective, cohort study is reporting longterm performance of surgically implanted RV-PA conduit in a consecutive series of children and adults with CHD.
Methods:
Patients with CHD referred for RV-PA conduit surgical implantation (October 1997 and January 2022) have been included. Primary outcome was conduit failure defined as peak gradient above 64mmHg/severe regurgitation/ need for conduit-related interventions. Secondary outcome was longitudinal change (increase) of continuous wave Doppler-derived peak gradient across conduit in postoperative echocardiographic studies. Longitudinal echocardiographic studies were available for mixed-effect linear regression analysis.
Results:
Two-hundred and fifty-two patients were initially included. One-hundred and fifty-one patients were available and elegible for follow-up data collection. After a median follow-up time of 49 months the primary study endpoint occurred in 44 (29%) patients. Multivariable Cox regression model identified adult age (>18 years) at implantation and pulmonary homograft as protective factors (HR 0.11, 95% CI 0.02-0.47, p-value 0.003 and HR 0.34, 95% CI 0.16-0.74, p-value 0.006, respectively). Fever within 7 days of surgical conduit implantation was a strong, independent risk factor for early (within 24 months) failure (HR 4.29, 95% CI 1.41-13.01, p-value 0.01). Longterm use of oral anticoagulant was independently associated with slower progression of peak echocardiographic gradient across conduits (p-value 0.027).
Conclusions:
In patients with CHD, surgically implanted RV-PA conduit failure is faster in children and after non-homograft conduit implantation. Early fever after surgery is a strong risk factor for early failure. Longterm anticoagulation seems to exert a protective effect
Advanced design for the extended packaging system. R&I service platform to support circular and sustainable innovation in packaging.
Get PDFLa ricerca indaga l’Extended Packaging System (EPS) attraverso la lente dell’Advanced Design (AD), con l’obiettivo di contribuire progettualmente a ridimensionare il suo impatto in termini di sostenibilità e circolarità, con un approccio One Health. Ipotesi di ricerca è la definizione di un campo problematico esteso, caratterizzato da un complesso sistema di attori, discipline, relazioni, agenti non umani e immateriali nel quale il Design può accelerare gli effetti desiderati, integrandosi ad altri saperi.
La prima parte della ricerca si focalizza sulla definizione dello stato dell'arte e sulla mappatura del campo problematico. Si delineano il contesto contemporaneo incerto e la complessa Value Web. Emerge la figura del Transitional Industrial Packaging Designer (TIPD): dotato di competenze avanzate e sistemiche, può facilitare la transizione dei processi di innovazione verso la circolarità per imprese ed enti.
Successivamente, l'attenzione si sposta sui nodi di intervento del design con un approccio di anticipazione: qui viene concepito e creato sperimentalmente l'Osservatorio Innovazione Packaging, una piattaforma digitale di servizi R&I con approccio AD e un database di 650 casi studio, mirata a diffondere conoscenza nell'EPS e promuovere progetti di innovazione circolare e sostenibile.
Nella terza parte, l’Osservatorio viene utilizzato come living lab per esperimenti di ricerca applicata per l’innovazione, promuovendo la creazione di un network integrato di attori. Si sviluppa inoltre un sistema di tassonomia per la schedatura dei casi studio, che evidenzia i fattori di innovazione.
Grazie a una Cross-Disciplinary Research, la ricerca ha ottenuto diversi risultati: la piattaforma, 24 mesi di sperimentazioni e una rete internazionale di relazioni, oltre alla curatela di un numero di diid.
La parte finale fornisce esperienze di pratica progettuale, oltre a evidenziare i limiti della ricerca e suggerire possibili sviluppi futuri. In Allegato sono presentati 50 casi-studio, corredati da infografiche che illustrano caratteristiche e relazioni tematiche, identificando leve per la sostenibilità nell'EPS.The research investigates the Extended Packaging System (EPS) through the lens of Advanced Design (AD), with the aim of contributing by design to resizing its impact in terms of sustainability and circularity, with a One Health approach. The research hypothesis is the definition of an extended problem field, characterised by a complex system of actors, disciplines, relations, non-human and immaterial agents in which Design can accelerate the desired effects, integrating with other expertise.
The first part of the research focuses on defining the state of the art and mapping the problem-field. The uncertain contemporary context and the complex Value Web are outlined. The figure of the Transitional Industrial Packaging Designer (TIPD) emerges: with advanced and systemic skills he or she can facilitate the transition of innovation processes towards circularity for companies and institutions.
Subsequently, the focus shifts to design intervention nodes with an anticipation approach: here the Packaging Innovation Observatory is conceived and experimentally created, a digital platform of R&Iservices with an AD approach and a database of 650 case studies, aimed at spreading knowledge in the EPS and promoting circular and sustainable innovation projects.
In the third part, the Observatory is used as a living lab for innovative applied research experiments, promoting the creation of an integrated network of actors. In addition, a taxonomy system is developed for filing case studies, highlighting innovation factors.
Thanks to a Cross-Disciplinary approach, the research achieved several results: the platform, 24 months of experimentation and an international network of relationships, as well as the curation of a diid number.
The final part provides experiences of project practice, as well as highlighting the limitations of the research and suggesting possible future developments. Fifty case studies are presented in the appendix, accompanied by infographics illustrating characteristics and thematic relationships, identifying levers for sustainability in EPS
Governance of alternative food networks through the lenses of experimentalist governance: insights from the city of Bologna
Get PDFThis research comes at a time of concern over the resilience of the current food system. Current practices have proven to be disruptive and have raised international awareness that translated into a complex and lively set of innovations, also known as Alternative Food Networks (AFNs).
Available literature already provides definitions and conceptualizations of AFNs. However, there is still a need for a deeper understanding of the governance of AFNs, which would allow us to gather a holistic vision of the innovations these networks generate. To do this, I make use of rich qualitative data from the study of two farmers market Associations in Bologna.
Two research questions guide the thesis:
RQ1: To what extent and effect does the internal governance of AFNs align with an experimentalist governance framework?
RQ2: What are the relations between modes of internal governance of AFNs and their engagement in municipal food policy?
This research highlighted novel relations and innovations from the two case studies that enrich the debate on AFNs and their governance. Moreover, it unveiled a set of relations among AFNs, and institutional actors that provided novel knowledge of the complex relations and mechanisms related to the interaction of AFNs with policy-makers and their attempts to contribute to the creation of a transformative local food policy.
In the first chapter of this thesis, I provide a literature review of the scholarship on AFNs, highlighting the research gap. In Chapter 2, built on a literature review on experimentalist governance, I present the analytical framework that guided this thesis. In Chapter 3, I describe the methods and methodology used for my study, the context of which is explained in Chapter 4. The empirical analysis of this research is carried out in chapters 5 and 6, where results are presented and later discussed in chapter 7