513225 research outputs found
Sort by
Estimation of morbidity indicators in population-based cancer studies: methodological developments
No full textCancer survival analysis in population-based settings relies on the relative survival framework, which enables the estimation of survival specific to the disease of interest in the absence of information on the individual cause of death. Within this framework, the overall hazard is decomposed into the excess hazard due to cancer and hazard due to the other competing causes of death, the latter derived from routine sources such as national or regional life tables. The survival function associated only with the excess hazard corresponds to the estimand of interest, known as net survival. Non-parametric estimators of this quantity, including Ederer I, Ederer II, Hakulinen, and Pohar-Perme, have been widely used in cancer epidemiology, yet their application has been the subject of long-standing methodological debates regarding bias, variability, and consistency. Researchers have also increasingly emphasized the value of model-based approaches, which allow flexible modeling, improved interpretability, and the ability to compare different demographic groups.
This thesis begins by introducing the relative survival framework and providing the necessary mathematical background to understand the main non-parametric estimators and their statistical properties. We also review the historical development and discussion of these methods over the past decades.
We then focus on the estimation of cure fractions in cancer populations and propose two novel mixture cure models. The first is a cure model with Weibull components, where the number of components is chosen using model selection criteria. The second is a Weibull mixture cure model in which the cure fraction is modeled as a flexible function of the covariates using smoothing splines and neural networks. The performances of these models are evaluated separately through simulation studies under different scenarios, including varying sample sizes and covariate distributions. Finally, we apply these novel methodologies to a cohort of colon cancer patients diagnosed in the municipality of Varese, Italy, between 1993 and 2013, providing relevant insights into colon cancer survival outcomes.
Then, the thesis addresses prevalence estimation and projection using an illness-death model, in which incidence and net survival are combined in a forward calculation method to estimate this quantity of interest. We improve the state-of-the-art procedure by applying regularization techniques for incidence model selection and estimating net survival within the framework of flexible parametric relative survival cure models. We conducted a simulation study to compare the proposed model selection algorithm with the classical stepwise selection procedure. The combined novel and classical pipelines for estimating prevalence are then compared using data from colon cancer patients diagnosed in Sweden between 1958 and 2019.
The thesis concludes with a summary of the main findings and a discussion of directions for future research
Electronic structure reconstruction for √3x√3 charge density wave in heavily Cu-intercalated TiSe2 revealed by spatially resolved photoemission spectroscopy
No full textScanning photoemission microscopy (SPEM) and angle-resolved photoemission spectroscopy (ARPES) are used to investigate the electronic structure of Cu0.33TiSe2 across the charge density wave (CDW) transition.
The electronic structure is found to be largely homogeneous in the normal state above the CDW transition. The ARPES measurements using a submicron beam size reveal a large electronlike pocket due to the Ti 3d band at
the M point while the Se 4p band at the point is absent due to electron doping by the intercalated Cu. We have observed √3× √3 Fermisurfacereconstruction below the CDW transition, in which Ti 3d bands are folded into
a reconstructed BZ rotated by 30◦ ,making the and K points equivalent. The results demonstrate the presence of a √3× √3 CDW phase in the electronic structure of heavily Cu-intercalated Cu0.33TiSe2. The findings reveal
a platform for investigating the two-dimensional electronic phase in 1T-TiSe2 chalcogenides, which exhibit a unique interplay between CDW, superconductivity, and excitonic/lattice instabilities
Submodular maximization subject to a knapsack constraint: Combinatorial algorithms with near-optimal adaptive complexity
No full textSubmodular maximization is a classic algorithmic problem with multiple applications in data mining and machine learning; there, the growing need to deal with massive instances motivates the design of algorithms balancing the quality of the solution with applicability. For the latter, an important measure is the adaptive complexity, which captures the number of sequential rounds of parallel computation needed by an algorithm to terminate. In this work, we obtain the first constant factor approximation algorithm for non-monotone submodular maximization subject to a knapsack constraint with near-optimal O(log n) adaptive complexity. Low adaptivity by itself, however, is not enough: a crucial feature to account for is represented by the total number of function evaluations (or value queries). Our algorithm asks O ̃(n2) value queries but can be modified to run with only O ̃(n), while retaining a low adaptive complexity of O(log2n). Besides the above improvement in adaptivity, this is also the first combinatorial approach with sublinear adaptive complexity for the problem and yields algorithms comparable to the state-of-the-art even for the special cases of cardinality constraints or monotone objectives
Indagine sulle malattie odontostomatologiche e sulla qualità dei trattamenti odontoiatrici in un campione rappresentativo della popolazione albanese
No full textIntroduzione: Nel quadro della salute pubblica albanese, la salute orale resta un indicatore essenziale di benessere: la carie dentaria persiste come principale determinante di perdita dentaria nelle età adulte e anziane, con marcate disuguaglianze territoriali e socioeducative.
Obiettivo: Determinare la prevalenza e la distribuzione di carie dentale, lesioni periradicolari, edentulismo, restauri e anomalie dentarie, nonché valutare la qualità delle cure odontoiatriche attraverso indici radiologici standardizzati a livello internazionale.
Materiali e Metodi: È stata condotta un’analisi trasversale su 1.455 ortopantomografie digitali (OPT) e 402 Cone Beam CT (CBCT) provenienti da soggetti adulti residenti in tutte le regioni dell’Albania, per un totale di 46.560 denti esaminati. Il campionamento è stato effettuato con tecnica a grappolo e stratificazione per sesso, area geografica (Nord, Centro, Sud, urbano), livello di istruzione (basso, medio, alto) e classe di età (≤ 30; 31–45; 46–60; > 60 anni), al fine di garantire una rappresentatività adeguata. Ogni dente è stato valutato secondo gli indici DMFT, PAI e R-PBL. La raccolta dei dati è stata svolta da due esaminatori indipendenti, con verifica dell’affidabilità inter-operatore (κ = 0,92).
Risultati: L’indice DMFT medio è risultato pari a 7,7. Le carie non trattate (D) sono state rilevate nel 13,5% dei denti, con frequenza maggiore nei soggetti sotto i 45 anni. I denti mancanti o da estrarre (EX+E) rappresentano il 38,1%, superando il 53,7% nei soggetti oltre i 60 anni. I restauri di I–II classe corretti (A) rappresentano il 12,04 % del totale, mentre la diffusione degli impianti (P) rimane contenuta (< 1%). DMFT più elevato al Nord, mentre la prevalenza di carie (D) risulta maggiore al Centro (p<0,01).
Conclusioni: I risultati evidenziano un notevole carico di malattia dentale nella popolazione adulta albanese, con marcate disuguaglianze regionali e socioeconomiche. Tali evidenze sottolineano la necessità di potenziare le misure di prevenzione e implementare un sistema nazionale digitale di sorveglianza della salute orale.
Ringraziamenti: Dipartimento di Scienze Odontostomatologiche e Maxillo-Facciali, Sapienza Università di Roma.Introduction: In the Albanian public health context, oral health remains a vital marker of well-being; dental caries continues to be the leading cause of tooth loss in adult and older populations, with pronounced geographic and socio-educational disparities.
Objective: To determine the prevalence and distribution of dental caries, periradicular lesions, edentulism, restorations, and dental anomalies, and to assess the quality of dental care through internationally standardized radiological indices.
Materials and Methods: A cross-sectional analysis was conducted on 1,455 digital orthopantomograms (OPT) and 402 cone-beam computed tomography (CBCT) scans from adult residents across all regions of Albania, for a total of 46,560 teeth examined. Sampling used a cluster design with stratification by sex, geographic area (North, Center, South, urban), educational level (low, medium, high), and age class (≤ 30; 31–45; 46–60; > 60 years), to ensure adequate representativeness. Each tooth was assessed according to the DMFT, PAI, and R-PBL indices. Data collection was performed by two independent examiners, with verification of inter-examiner reliability (κ = 0.92).
Results: The mean DMFT index was 7.7. Untreated caries (D) were detected in 13.5% of teeth, with higher frequency among subjects under 45 years. Missing teeth or teeth indicated for extraction (EX+E) accounted for 38.1%, exceeding ≥ 53,7% among subjects over 60 years. Correct Class I–II restorations (A) represented 12,04 % of teeth, while the prevalence of implants (P) remained low (< 1%). DMFT was higher in the North, whereas the prevalence of caries (D) was higher in the Center (p<0.01).
Conclusions: The findings indicate a substantial burden of dental disease among Albanian adults, with marked regional and socio-economic inequalities. These results underscore the need to strengthen preventive measures and to implement a national digital oral-health surveillance system.
Acknowledgments: Department of Oral and Maxillofacial Sciences, Sapienza University of Rome
Quantifying the Priceless: A Methodological Approach to the Evaluation of Historical-Architectural Heritage
No full textThat humor is invaluable is absolutely evident, but that it is also a characteristic of a property, given the advances in the discipline of Real Estate Appraisal, is today more difficult to sustain. Today, the valuation of historical-architectural properties requires rigorous methodologies that go beyond merely qualitative and subjective approaches, moving toward valuation models capable of precisely quantifying the contribution that elements of historical value bring to the overall worth. The historical-architectural heritage of Italian cities, conceived as a resource to be preserved for future generations, requires adequate appraisal tools that recognize its intrinsic complexity, connected not only to the physical characteristics of the property but also to its cultural context and its ability to generate positive externalities. The methodological challenge consists of integrating both tangible and intangible aspects into the valuation analysis, developing models that can be applied with consistency and scientific rigor even in contexts characterized by high variability and specificity, such as properties used for tourism and hospitality. This research analyzes the impact of historical-architectural value on the market value of properties used for tourism and hospitality, with specific regard to the city of Rome. Unlike previous studies, where econometric models were implemented with reference to samples of historical price data, in this case the analysis will reference samples of forecast data concerning the profitability of hospitality structures characterized by different historical-architectural values. The adopted methodology integrates the Analytic Hierarchy Process (AHP) with multiple linear regression models, allowing consideration of both qualitative and quantitative variables in real estate valuation
The Gut Microbiota–Mast Cell Axis in Intestinal Homeostasis and Food Allergy Pathogenesis
No full textFood allergy is an increasing global health burden, particularly in industrialized countries, with rising prevalence in both pediatric and adult populations. It is characterized by exaggerated immune responses to innocuous dietary antigens, leading to clinical manifestations ranging from mild gastrointestinal symptoms to life-threatening anaphylaxis. Mast cells are central effectors in the pathophysiology of food allergy, initiating and amplifying allergic inflammation through the release of a broad array of mediators upon activation. Recent studies have revealed that the intestinal microbiota plays a critical role in shaping immune responses, including the regulation of mast cell development, maturation, and activation. Moreover, dysbiosis has been associated with increased susceptibility to allergic sensitization and heightened mast cell reactivity. This review explores the molecular mechanisms underlying the microbiota–mast cell axis in the context of intestinal homeostasis and food allergy with a particular emphasis on the regulation of mast cell effector functions by TLR signaling and microbial metabolites. We also discuss the therapeutic potential of targeting the microbiota–mast cell axis as novel strategies to restore immune tolerance. Understanding this complex crosstalk opens new avenues for translational approaches in the prevention and treatment of food allergy
DIGITALIZZAZIONE PER IL PATRIMONIO COSTRUITO STORICO E RISCHIO DI PERDITA. Problematiche, scenari operativi e un'applicazione al contesto vesuviano
No full textThe distinction between intangible and tangible heritage highlights the specific conservation needs of the la6er, which are closely tied to its material nature. These needs become particularly complex, especially when they must be managed in emergency situations caused, for example, by natural disasters. Such challenges are to be examined in light of technological advancements that enable them to be addressed in new ways. Digital tools, in fact, can serve as valuable aids in coordinating the expertise of the various institutions involved in heritage
conservation at a time when the effectiveness of safeguarding efforts depends on the timeliness of targeted, informed, and synergistic actions
Corporate Governance Mechanisms and Innovation Efficiency in the U.S. Healthcare Sector
No full textThis paper investigates how board level corporate governance mechanisms affect innovation efficiency in the U.S. healthcare industry. Drawing on agency and stewardship theory, we conceptualize innovation efficiency as the firm’s ability to convert R&D inputs into patenting outputs and operationalize it as the ratio of patents to R&D expenditure. We assemble a balanced panel of 63 NASDAQ listed healthcare firms over the 2020-2024 period. Using fixed effects panel regressions, we examine the role of board mechanisms in shaping innovation efficiency. Our findings show that board size is negatively and significantly associated with innovation efficiency. Average board tenure and CEO duality also exhibit negative and marginally significant effects, consistent with director entrenchment, weakened monitoring and increased risk aversion. By contrast, board independence does not display a significant relationship with innovation efficiency, while gender diversity shows a positive yet statistically weak association. The study advances corporate governance and innovation research by shifting attention from innovation intensity to innovation efficiency, providing sector specific evidence from a highly regulated and knowledge intensive industry, and questioning compliance oriented governance metrics in favor of board structures that strengthen information processing, monitoring and strategic agility
Processi partecipativi e welfare a Roma: i casi dei Piani Urbani Integrati a Corviale e Tor Bella Monaca
No full textLa tesi analizza il rapporto tra processi partecipativi e welfare locale a Roma attraverso lo studio comparato dei Piani Urbani Integrati (PUI) nei quartieri di Corviale e Tor Bella Monaca. Inserito nel quadro dei recenti cambiamenti normativi – in particolare la Legge 328/2000 e il Codice del Terzo Settore – il lavoro indaga se e in che misura co‐programmazione e co‐progettazione contribuiscano a trasformare la governance dei servizi sociali, ridefinendo ruoli, identità organizzative e confini della cittadinanza sociale.
Dal punto di vista teorico, la ricerca adotta una prospettiva neo‐istituzionalista integrata con la letteratura sulla network governance e sull’innovazione sociale, ponendo al centro due variabili: il grado di istituzionalizzazione delle procedure partecipative e il livello di integrazione/coesione del tessuto associativo locale. Metodologicamente, lo studio si basa su un approccio qualitativo e process‐tracing, che combina osservazione partecipante ai tavoli di co‐programmazione, interviste semistrutturate a amministratori e rappresentanti del terzo settore, analisi documentale dei prodotti generati e ricostruzione dei contesti urbani e di welfare.
La comparazione tra Corviale e Tor Bella Monaca mostra come l’istituzionalizzazione delle procedure non sia sufficiente, in assenza di reti associative coese e di una leadership politico‐amministrativa capace di legare partecipazione e decisione, a produrre esiti deliberativi robusti. Dove il capitale sociale è più denso, la co‐programmazione accelera coordinamento e capacità di iniziativa; nei contesti più frammentati richiede invece investimenti maggiori in facilitazione, mediazione e “vittorie intermedie”. La tesi conclude che i percorsi esaminati, pur segnati da rischi di ritualizzazione e disillusione, rappresentano laboratori significativi di amministrazione condivisa, nei quali si intravedono potenzialità di innovazione istituzionale e di rafforzamento della cittadinanza societaria nelle periferie urbane.This thesis analyses the relationship between participatory processes and local welfare in Rome through a comparative study of the Integrated Urban Plans (PUI) in the neighbourhoods of Corviale and Tor Bella Monaca. Set within the framework of recent regulatory changes – in particular Law 328/2000 and the Third Sector Code – the work investigates whether and to what extent co-programming and co-design contribute to transforming the governance of social services, redefining roles, organisational identities and the boundaries of social citizenship.
From a theoretical standpoint, the research adopts a neo-institutionalist perspective integrated with the literature on network governance and social innovation, focusing on two main variables: the degree of institutionalisation of participatory procedures and the level of integration/cohesion of the local associative fabric. Methodologically, the study is based on a qualitative, process-tracing approach that combines participant observation at co-programming tables, semi-structured interviews with public officials and third-sector representatives, documentary analysis of the outputs produced, and reconstruction of the urban and welfare contexts.
The comparison between Corviale and Tor Bella Monaca shows that the institutionalisation of procedures is not sufficient, in the absence of cohesive associative networks and of political–administrative leadership capable of linking participation and decision-making, to produce robust deliberative outcomes. Where social capital is denser, co-programming speeds up coordination and initiative-taking capacity; in more fragmented contexts, it instead requires greater investment in facilitation, mediation and “intermediate victories”. The thesis concludes that the processes examined, although marked by risks of ritualisation and disillusionment, represent significant laboratories of shared administration, in which it is possible to glimpse the potential for institutional innovation and the strengthening of societal citizenship in urban peripheries
Body composition in Liver Cirrhosis and after Transjugular Intrahepatic Portosystemic Shunt: prognostic impact and clinical assessment
No full textMalnutrition is highly prevalent in patients with liver cirrhosis and represents a major determinant of morbidity and mortality. Beyond traditional nutritional assessment, alterations in body composition—particularly sarcopenia, myosteatosis, and adipose tissue redistribution—have emerged as powerful prognostic markers. In patients undergoing transjugular intrahepatic portosystemic shunt (TIPS), nutritional status may both influence post-procedural outcomes and be modified by the intervention itself. However, available evidence is largely retrospective, heterogeneous, and focused mainly on muscle quantity, with limited data on muscle quality and adipose tissue characteristics. The aim of this PhD project was to investigate the prognostic impact of body composition in cirrhosis and to assess longitudinal nutritional changes after TIPS using standardized imaging-based approaches.
Methods
This research included three complementary studies:
a prospective multicenter cohort study evaluating the prognostic role of sarcopenia and myosteatosis in patients with cirrhosis using computed tomography (CT) at the L3 vertebral level;
a systematic review of the literature assessing the impact of TIPS on nutritional status and body composition;
a prospective multicenter study investigating baseline body composition as a predictor of post-TIPS outcomes and longitudinal changes after the procedure.
Muscle mass, muscle attenuation, visceral and subcutaneous adipose tissue, and adipose tissue radiodensity were assessed by CT. Functional performance and frailty were evaluated using validated bedside tests. Clinical outcomes included mortality, hospitalizations, liver decompensation, hepatic encephalopathy (HE), and TIPS failure.
Results
In the multicenter prospective cohort, muscle alterations were highly prevalent, with myosteatosis representing the most frequent abnormality. Myosteatosis, alone or in combination with sarcopenia, was associated with increased mortality, higher hospitalization rates, impaired muscle function, and greater frailty, independently of liver disease severity. Functional tests correlated more closely with muscle quality than with muscle quantity.
The systematic review demonstrated that TIPS placement is generally associated with improvement in nutritional status, particularly increased skeletal muscle mass and a redistribution of adipose tissue characterized by reduced visceral fat and increased subcutaneous fat.
In the prospective TIPS cohort, TIPS was associated with a significant increase in skeletal muscle index and an improvement in visceral-to-subcutaneous adipose tissue ratio at follow-up. Lack of muscle mass improvement and adverse adipose tissue characteristics, particularly high subcutaneous adipose tissue radiodensity, were associated with worse post-TIPS outcomes, including ascites recurrence, TIPS failure, and mortality.
Conclusions
Body composition alterations are highly prevalent in cirrhosis and provide prognostic information beyond traditional clinical scores. Myosteatosis appears to play a central role in disease progression and outcomes, often preceding or accompanying sarcopenia. TIPS placement is associated with favorable changes in muscle mass and adipose tissue distribution, suggesting a potential nutritional benefit in selected patients. However, the absence of muscle gain and persistent adverse adipose tissue features identify patients at higher risk of post-TIPS complications. Comprehensive and integrated assessment of muscle quantity, muscle quality, and adipose tissue should be incorporated into routine clinical evaluation and future prognostic models in cirrhosis and in patients undergoing TIPS