Archivio Istituzionale della Ricerca - Università degli Studi di Pavia
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Neural networks unleashed: joint SPX/VIX calibration has never been faster
No full textJoint calibration to the Standard & Poor’s 500 (SPX) and Chicago Board Options Exchange (CBOE) Volatility Index (VIX) market data can be computationally burdensome, especially when the standard course of action for pricing volatility derivatives is nested Monte Carlo simulation, as is the case for the four-factor Markov path-dependent volatility model of Guyon and Lekeufack. A crucial boost to solving the joint problem was developed by Gazzani and Guyon, who trained a neural network to learn to model VIX as a random variable: the network replaces the inner simulation, and the pricing of VIX derivatives is reduced to a standard Monte Carlo computation. This is a step in the right direction but it is not sufficient. In this paper, Fabio Baschetti, Giacomo Bormetti and Pietro Rossi aim to further accelerate calibration by training neural networks to learn SPX implied volatilities, VIX futures and call option prices as a function of model parameters and contract specifications. As a result, pricing boils down to a matrix-vector product that can be calculated in real time, while calibration only takes a few seconds
Audio‐guided exercise at home: Preliminary findings from a pilot study on physical activity for people with low vision
No full textBackground: Individuals with severe visual impairments frequently refrain from regular physical activity due to multiple barriers, including transportation difficulties, financial constraints, and limited availability of exercise programs tailored to their needs. These factors often contribute to a gradual decline in mobility and independence.
Objective: To evaluate the feasibility of a self-administered, audio-guided training protocol designed to improve mobility in people with severe visual impairments.
Design: Nonrandomized controlled clinical trial (number: NCT05956730).
Participants: Nineteen adults (55.5 ± 14.8 years, 52% females) with severe low vision or blindness, met the inclusion criteria and completed all the assessments.
Interventions: Participants were assigned to an audio-guided (AUD) group performing a 3-month home-based training or a supervised (SUP) group performing identical training in a gym.
Outcome measures: Mobility assessment, including Timed Up and Go Low Vision version (TUG-LV), 1-minute sit-to-stand (1-MSTS), the 3-minute step (3-MSTEP), and Sit and Reach (SR) tests, was conducted every 4 weeks. Physical activity level, satisfaction profile, visual functioning, and caregiver burden were recorded.
Results: Participants reported no injuries or physical issues, and adherence was >95%. Both AUD and SUP showed enhancements in TUG-LV, 1-MSTS, 3-MSTEP, and SR (time, p <.001), with differences between groups in 1-MSTS and 3-MSTEP (time × group, p = .04). Physical activity level and satisfaction in physical functioning increased over time (p = .002; p = .03), with no time per group interaction (p = .76; p = .37). No significant changes were noted in visual functioning or caregiver burden.
Conclusions: Although supervised training showed slightly greater improvements in some outcomes, audio-guided training is feasible, offering a valuable alternative to enhance mobility when supervision is not viable
The lived experience of persons who attempt suicide: a bottom‐up review co‐designed, co‐produced and co‐written by experts by experience and academics
No full textThis is the first bottom-up review of the lived experience of persons who attempt suicide. The study has been co-designed, co-conducted and co-written by experts by experience and academics, focusing on first-person narratives within and outside the medical field. The lived world of individuals who attempt suicide is characterized by experiences related to the attempt itself (“contemplating suicide as a deliberate death”, “contemplating suicide as an escape route”, “looking for online answers about suicide”, “planning suicide”, “finding rest between the suicidal decision and the final act”, “changing one’s mind during the suicide attempt”, “acting on suicidal impulses”); experiences related to the self and time (“feeling unworthy”, “feeling detached from oneself or the world and lacking a sense of agency”, “splitting the self between the decision to live or die”, “perceiving an abortive and doomed future”); and experience of emotions and the body (“feeling overwhelmed by hopelessness and despair”, “feeling empty and drained of energy”, “feeling alone”). The lived experience of individuals who attempt suicide is also described in terms of the social and cultural context, including the experience of others (“feeling that no one cares”, “feeling like a burden to others”, “facing others’ difficulty in understanding”); cultural, gender and age differences (“experiencing geographical, cultural and religious taboos about suicide”, “feeling inadequate in relation to gender stereotypes”, “feeling abandoned in old age”); and the perception of stigma (“facing social stigma”, “experiencing a stigmatized self”, “silencing suicidal behaviors”). The lived experience of persons after an attempted suicide is characterized as a complex process of self-acceptance and rediscovery (“living with suicidal thoughts”, “navigating the challenges of recovery”, “gaining new perspectives during recovery”, “restoring interpersonal relationships to recover”). Finally, the lived experience of individuals who attempt suicide is described with respect to their access to general health care (“seeking help before the suicide attempt”, “feeling abandoned after a suicide attempt”) and mental health care (“experiencing shame as a barrier to care”, “fearing mental disorder label”, “feeling accepted and listened to”, “facing economic difficulties in accessing support”, “coping with distress during hospitalization”). The experiences described in this paper hold educational and social value, informing medical and psychological practices and research, public health approaches, and promotion of social change. This research overcomes embarrassment, fear and stigma, and helps us to understand the fragile nature of our emotions and feelings, our immersion in the social world, and our sense of meaning in life
Il respiro come l'anima (Prud. apoth. 833-842)
No full textCommento contenutistico e stilistico di Prud. apoth. 833-842 e valorizzazione di eventuali suggestioni in direzione di Lucrezio
An Integrative Framework for EWAS in Challenging Environmental Contexts: Application to Chronic Hypobaric Hypoxia
No full textAbstract
Background: Over the past decade, Epigenome-Wide Association Studies (EWAS) have emerged as a powerful approach to link environmental exposures, gene regulation, and phenotypes beyond genetic variation, but their ability to explain complex adaptations remains limited, highlighting the need for integrative strategies.
Aims: This Thesis aimed to investigate DNA methylation alterations associated with chronic hypobaric hypoxia at high altitude, considering environmental, lifestyle, genetic and socio-psychological influences, through the development of an integrative framework combining genetic, epigenetic, and clinical data to clarify the role of DNA methylation in the manifestation of adaptive phenotypes.
Material and Methods: The study population was a subcohort of the HIGHCARE-LAPS project, including 192 subjects from Peru, equally divided between Lowlanders (Lima, sea level) and Highlanders (Cerro de Pasco, 4,400 m). Genomic and epigenomic data (array-based) were collected from blood, together with lifestyle, socio-psychological, and clinical variables. A replication cohort from a public dataset was used when available. The framework included all key steps (data import, quality control, preprocessing, and normalization) and introduced alternative approaches to traditional EWAS, including adapted differential methylation analysis, sensitivity checks, detection of stochastic epigenetic mutations, rare epivariation, exploration of altitude–methylation–phenotype links, and the use of epigenetic clocks.
Results and Conclusions: The application of this alternative framework has proven effective in reducing noise and strengthening traditional analyses, enabling the identification of new sites and regions potentially involved in hypoxia-related biological processes. It has also emerged that some adaptive phenotypes are mediated by DNA methylation in genes already known for such phenotypes, but not previously associated with chronic high-altitude hypoxia. Other metrics, such as epigenetic age acceleration, have shown an increase without negative associations with phenotypes, opening up new avenues for research. Overall, these findings highlight the value of adopting refined analytical strategies to better capture the complexity of environmental adaptation.Abstract
Background: Over the past decade, Epigenome-Wide Association Studies (EWAS) have emerged as a powerful approach to link environmental exposures, gene regulation, and phenotypes beyond genetic variation, but their ability to explain complex adaptations remains limited, highlighting the need for integrative strategies.
Aims: This Thesis aimed to investigate DNA methylation alterations associated with chronic hypobaric hypoxia at high altitude, considering environmental, lifestyle, genetic and socio-psychological influences, through the development of an integrative framework combining genetic, epigenetic, and clinical data to clarify the role of DNA methylation in the manifestation of adaptive phenotypes.
Material and Methods: The study population was a subcohort of the HIGHCARE-LAPS project, including 192 subjects from Peru, equally divided between Lowlanders (Lima, sea level) and Highlanders (Cerro de Pasco, 4,400 m). Genomic and epigenomic data (array-based) were collected from blood, together with lifestyle, socio-psychological, and clinical variables. A replication cohort from a public dataset was used when available. The framework included all key steps (data import, quality control, preprocessing, and normalization) and introduced alternative approaches to traditional EWAS, including adapted differential methylation analysis, sensitivity checks, detection of stochastic epigenetic mutations, rare epivariation, exploration of altitude–methylation–phenotype links, and the use of epigenetic clocks.
Results and Conclusions: The application of this alternative framework has proven effective in reducing noise and strengthening traditional analyses, enabling the identification of new sites and regions potentially involved in hypoxia-related biological processes. It has also emerged that some adaptive phenotypes are mediated by DNA methylation in genes already known for such phenotypes, but not previously associated with chronic high-altitude hypoxia. Other metrics, such as epigenetic age acceleration, have shown an increase without negative associations with phenotypes, opening up new avenues for research. Overall, these findings highlight the value of adopting refined analytical strategies to better capture the complexity of environmental adaptation
Improved HDL, LDL and total cholesterol levels following a 3-month administration of Mentha spicata leaf extract and Amaranthus caudatus seed flour extracts, flavonoids and B vitamins. A placebo-controlled, double-blind, randomized clinical trial
No full textBackground and aims: We have evaluated the efficacy and tolerability of two food supplements (FS) containing flavonoids (naringin and hesperidin); same doses of B3, B6, B9 and B12 vitamins, and two different doses of a blend of Mentha spicata leaf extract and Amaranthus caudatus seed flour, in subjects with borderline high total (TC) and low-density lipoprotein cholesterol (LDL-C) levels. Methods and results: 114 Participants (18–70 years) with TC levels 200–239 mg/dL, (5.18–6.19 mmol/L) and LDL-C (<159 mg/dL) were randomised into three groups to receive for 90 days the lowest (n = 38, Treatment A), the highest dose of the FS (n = 38 – Treatment B), or placebo (n = 38). Treatment B was associated with a significant reduction in LDL-C (∼31.5 mg/dL;-22%) and TC (∼19.5 mg/dL; -9%), along with an increase in high-density lipoprotein cholesterol (HDL-C). The greater efficacy of Treatment B containing the highest dose of vegetable extracts is likely attributable to its higher M. spicata extract content, as judged by high-resolution mass spectrometry analysis of the preparation. Conclusion: The combination of different FS ingredients with different mechanisms of action can be a valuable strategy for improving lipid profiles in subjects with borderline high TC and LDL-C levels
Modulazione della crescita cristallina per celle solari ibride a perovskite efficienti
No full textL’aumento continuo della domanda energetica globale, trainato dalla crescita della popolazione e dall’espansione industriale, ha comportato un corrispondente incremento delle emissioni di CO2, evidenziando l’urgente necessità di una rapida transizione verso fonti energetiche sostenibili. Tra le opzioni disponibili, l’energia solare si distingue come una delle soluzioni più promettenti grazie alla sua abbondanza e al rapido avanzamento delle tecnologie fotovoltaiche. Sebbene le celle solari al silicio dominino attualmente il mercato, i loro processi produttivi ad alta intensità energetica e i tempi di ritorno energetico relativamente lunghi sottolineano l’importanza di individuare materiali alternativi. In questo contesto, le perovskiti alogenuri ibride (HHP) sono emerse come una classe di materiali altamente interessante, grazie alle eccellenti proprietà optoelettroniche, alla processabilità in soluzione a bassa temperatura e al rapido aumento delle efficienze di conversione di potenza, ormai paragonabili a quelle delle tecnologie al silicio mature. Questa tesi esplora la relazione tra le condizioni di processo e le conseguenti proprietà strutturali e optoelettroniche dei materiali perovskitici, sia in forma di film sottili sia all’interno di dispositivi fotovoltaici completi. Particolare enfasi è posta sulla comprensione di come parametri quali l’ambiente solvente, i protocolli di ricottura e l’ottimizzazione della composizione influenzino la stabilità del materiale, la formazione di difetti e le prestazioni del dispositivo. Un obiettivo centrale di questo lavoro è identificare percorsi di fabbricazione che mitighino l’intrinseca sensibilità ambientale dei materiali perovskitici, consentendo dispositivi più stabili e riproducibili. Correlando le dinamiche di cristallizzazione su scala nanometrica al comportamento macroscopico del dispositivo, lo studio fornisce indicazioni sui meccanismi di passivazione dei difetti e di stabilizzazione di fase. In ultima analisi, questa ricerca contribuisce all’avanzamento di celle solari a perovskite scalabili, efficienti e stabili, favorendone l’integrazione nelle tecnologie energetiche sostenibili e rafforzandone il potenziale come valida alternativa nella transizione globale verso le energie rinnovabili.The continuous rise in global energy demand, driven by population growth and industrial expansion, has led to an associated increase in CO2 emissions, underscoring the urgent need for a swift transition to sustainable energy sources. Among the available options, solar energy stands out as one of the most promising solutions due to its abundance and the rapid advancement of photovoltaic technologies. Although silicon-based solar cells currently dominate the market, their energy-intensive production processes and relatively long energy payback times highlight the importance of identifying alternative materials. In this context, hybrid halide perovskites (HHPs) have emerged as a highly attractive class of materials, owing to their excellent optoelectronic properties, low-temperature solution processability, and rapidly increasing power conversion efficiencies, now on par with those of mature silicon technologies. This thesis explores the relationship between processing conditions and the resulting structural and optoelectronic properties of perovskite materials, both as thin films and within complete photovoltaic devices. Particular emphasis is placed on understanding how parameters such as solvent environment, annealing protocols, and compositional tuning affect material stability, defect formation, and device performance. A central objective of this work is to identify fabrication routes that mitigate the intrinsic environmental sensitivity of perovskite materials, enabling more stable and reproducible devices. By correlating nanoscale crystallization dynamics with macroscopic device behavior, the study offers insights into mechanisms of defect passivation and phase stabilization. Ultimately, this research contributes to the advancement of scalable, efficient, and stable perovskite solar cells, supporting their integration into sustainable energy technologies and reinforcing their potential as a viable alternative in the global shift toward renewable energy
Peccata naturae. La naturalità dei mostri secondo Tommaso d’Aquino
No full textL’analisi dei testi di Tommaso d’Aquino e di altri teologi tra XIII e XIV secolo (come Alberto Magno, Enrico di Gand, Remigio de’ Girolami e Giovanni di Napoli) mostra che nel Medioevo scolastico il confine tra “mostruoso” e “normale” è meno rigido di quanto si pensi. Per Tommaso i “mostri” rientrano pienamente nell’ordine naturale: non sono realtà contro natura, ma fenomeni che, proprio in quanto anomalie, confermano la finalità e l’ordinamento provvidenziale della natura. La teratologia scolastica integra l’anomalo nel quadro complessivo della natura: senza deviazioni e irregolarità, la natura sarebbe o immutabile come l’eterno o puramente casuale, priva di ordine causale. Inoltre, Tommaso tende a “desostanzializzare” il mostruoso: in un universo ordinato dalla provvidenza, il male non possiede una consistenza ontologica autonoma. I peccata naturae sono difetti nell’operare della natura, analoghi ai peccati morali o cognitivi nell’agire umano. Il mostruoso consiste soprattutto nel venir meno dell’intenzione particolare dell’agente naturale (carattere preterintenzionale), senza però uscire dall’intenzione dell’agente universale, cioè di Dio. Un altro elemento decisivo è l’assunto aristotelico della rigidità delle specie, che esclude la reale esistenza di ibridi tra specie diverse, inclusi uomo e animale. Ciò che definisce l’essere umano non è l’aspetto esteriore, ma la razionalità. Nicola Oresme osserverà infine che, data la complessità della generazione, è quasi più sorprendente la nascita di individui sani che quella dei “mostri”, e che la vera mostruosità potrebbe consistere nella mancanza di razionalità più che nelle deformità fisiche
