Ciclo di Conferenze dei corsi di Laurea in Fisica del Dipartimento di Matematica e Fisica
Comitato organizzatore: D. Meloni, F. La Franca, L. Lupi, S. Lauro, S. Mari, F. Paolucci
Edizione 2024
Nicola Menci
INAF – Osservatorio Astronomico di Roma
High-redshift Galaxies from Early JWST Observations: Constraints on Cosmological Models
Link identifier #identifier__196331-1Locandina – 16 gennaio 2024 ore 14:30 Aula C
Early observations with JWST have led to the discovery of an unexpectedly large density of massive galaxies at extremely early epochs in the history of the Universe.
Such results have a strong impact on cosmology. Here we show that—under the most conservative assumptions and independently of the baryon physics involved in galaxy formation—such galaxy abundance is not only in tension with the standard CDM cosmology but provides extremely tight constraints on the expansion history of the universe and on the growth factors corresponding to a wide class of Dynamical Dark Energy models. The implications of such results in terms of fundamental of cosmological models are discussed.
Letizia Chiodo
Research Unit Nonlinear Physics and Mathematical Models, Department of Engineering, Campus Bio-Medico University of Rome
Computational study of non-coding rna structures and their interaction with proteins
Link identifier #identifier__68532-2Locandina – 6 febbraio ore 14:30 Aula B
The non-coding RNAs (ncRNAs) have recently emerged as protagonists of molecular biology, with profound implications in the regulation of complex mechanisms underlying physiological conditions, and whose dysregulation can induce a wide range of diseases.
The ncRNAs molecular functioning is based on their interaction with other biomolecules, therefore the knowledge of their structures is highly relevant in the framework of the structure-function paradigm. The lack of massive experimental structural data makes the in-silico prediction of RNA secondary and tridimensional structure of pivotal importance. Yet, these predictions are extremely challenging, especially for large RNA molecules. Here we present a comparison of computational tools to predict secondary structure, assessed on a sample of ncRNAs (e.g. HCV Ires domain). We developed a dedicated protocol, to obtain reliable structures starting from primary sequences, and demonstrate its usage in the case of the human lncRNA DLEU2.
DLEU2 is expressed in the liver, with increased expression in human hepatocellular carcinoma. This lncRNA physiologically interacts with the protein zeste homolog 2 (EZH2) in the PRC2 complex for transcription repression. In the presence of the hepatitis B virus, the HBX protein expressed by the virus activates DLEU2 expression in the host and directly binds it to modulate transcription and boost HBV replication. By modeling the molecular complexes of DLEU2/EZH2/HBx it has been predicted a protein competition, experimentally confirmed, that impacts EZH2/PRC2 functions.
This investigation is an example of the successful application of in-silico protocols to guide and interpret biomolecular and cellular biological assays.
References:
Salerno D, Chiodo L, Alfano, et al., “Hepatitis B protein HBx binds the DLEU2 lncRNA to sustain cccDNA and host cancer-related gene transcription”, Gut 69, 2016-2024 (2020). doi: 10.1136/gutjnl-2019-319637.
Matarrese MAG, Loppini A, Nicoletti M, Filippi S, Chiodo L, “Assessment of tools for RNA secondary structure prediction and extraction: a final-user perspective”, Journal of Biomolecular Structure and Dynamics, 41, 6917-6936 (2023). doi: 10.1080/07391102.2022.2116110
David T. Chuss
Department of Physics, Villanova University
The Magnetic Field in the Galactic Center: Results from the Stratospheric Observatory for Infrared Astronomy
Link identifier #identifier__91791-3Locandina – 12 marzo 2024 ore 14:30 Aula C
Understanding the physics at work in our Milky Way’s center is crucial to our understanding of Galactic dynamics. In addition, the proximity of our own Galactic center to Earth enables the most detailed means for probing the physics of galactic nuclei in general. The central 150 parsecs of our Galaxy are commonly known as the “Central Molecular Zone (CMZ)”. This region is known for conditions that are unique in our Galaxy. Cloud masses and velocity dispersions are larger than in the disk. There are numerous supernova remnants, and co-incident with the cool material is a hot ionized phase. Amidst this hot phase exists a series of long thin synchrotron structures known as the “Non-thermal Filaments (NTFs)”. These structures are understood to trace a magnetic field that is oriented predominantly perpendicular to the plane. Despite having been discovered 40 years ago, neither the origins of the NTFs nor the dynamics of their associated magnetic field are well understood. Measurement of polarized emission from magnetically-aligned dust at far-infrared wavelengths provides an additional important tool for addressing these questions. In this talk, I will describe polarimetric results from NASA’s SOFIA (Stratospheric Observatory for Infrared Astronomy) mission, focusing on the large survey project entitled the Far-InfraREd Polarimetric Large-Area CMZ Exploration (FIREPLACE).
Davide Picca
Department of Physics, Villanova University
Reimagining Human Knowledge in the Age of LLMs: Bridging AI with Human Reasoning and Creativity
Link identifier #identifier__52354-4Locandina – 12 aprile 2024 ore 14:00 Aula B
This talk seeks to discuss how the impact of large language models (LLMs) such as GPT is likely to change conceptions regarding intelligence and timeless values of human insight. We will probe the philosophical and practical consequences of such a delineation between data, information, knowledge, and wisdom, questioning the paradigms that so far have been holding force and calling for the necessity of these definitions to be somehow changed with the advent of AI. The current LLMs have critically looked at limitations and exposed the inherent biases that they possess; the present discourse only brings out a paradigm that is not only inclusive of human wisdom but has space for cultural nuances to be in the lead. We advocate for AI systems, which should go beyond computational efficiency, embody a deeper sense of human reasoning and experiences by advocating integration with humanistic principles. So, the talk is an attempt to provoke reflection on the question of the future role of humans in an AI-dominated era and to what extent there will be the necessity of fostering AI technologies that augment rather than degrade human unique attributes of understanding and creativity.
Federico Meloni
DESY
Towards a muon collider
Link identifier #identifier__162579-5Locandina – 17 maggio 2024 ore 14:00 Aula B
Muon colliders are an unprecedented opportunity for high-energy physics. They can provide collisions of point-like particles at very high energies and open the path to a vast physics programme. Their strong physics potential is accompanied by intriguing technological challenges, due to the fact that muons are unstable particles. For example, the muon decay products can interact with the machine elements and produce an intense flux of background particles that eventually reach the detectors and might degrade their performance. Addressing these challenges requires the development of innovative detector and accelerator technologies. In this talk, I will introduce the collider, its potential and challenges, together with an overview of the path to being able to take data at a center of mass energy of 10 TeV.
Francesca Esposito
INAF
Back to the Moon – A window of opportunity for frontier Science
Link identifier #identifier__176976-6Locandina – 5 giugno 2024 ore 14:30 Aula C
In 2018, Space Agencies around the world published the Global Exploration Roadmap (GER), where they shared the common intent to expand the human presence into the Solar System with the surface of Mars as a driving goal and the Moon as a necessary intermediate step. About 30 robotic and 4 crewed space missions to the Moon (from 13 Countries and from both Space Agencies and private companies) have been already approved to be launched in the 2023 – 2028 time frame, while ~ 20 more missions are under evaluation. The goal of this space effort is to establish a sustainable human presence on the Moon and, in the future, also on Mars.
This seminar will discuss the strong effort ongoing worldwide and the important opportunities that could be offered in several sectors of science, technology, economics. The return to the Moon will revolutionize the relation of mankind to Space exploration. Experiments and facilities on the Moon, including new structures and devices for the observation of the Earth and the Universe, will boost planetary science, life science, physiology and medicine, radio, optical, infrared and cosmic ray astronomy, and more. The Moon has the potential to become the test ground for human capability to survive and operate in space, as well as a launch base for future planetary missions.
The role that Italy is playing in this context and the one it could play in the next future will be also discussed, with emphasis on ideas and proposals coming from its scientific community and on the recent PNRR project “Earth Moon Mars”, led by INAF and approved by the Italian Ministry of Research.
Alessandra De Rosa
IAPS/INAF – National Institute for Astrophysics
The quest for dual and binary supermassive black holes
Link identifier #identifier__109221-7Locandina – 27 giugno 2024 ore 14:30 Aula C
Hierarchical models of galaxy formation predict that galaxy mergers represent a key transitional stage of rapid Supermassive Black Holes (SMBHs) growth. However, the lack of a census of AGN pairs over cosmic time prevents us from firmly connecting BH triggering and merging processes.
Detecting dual AGN – active SMBHs at projected separations larger than several parsecs – and binary AGN – active SMBHs bound in a Keplerian binary – is an observational and theoretical challenge. These systems encode crucial information about the formation and accretion history of SMBHs across cosmic ages and are among the loudest gravitational waves emitters at low-frequencies.
The talk will review the observational efforts, across the electromagnetic spectrum, on the detection and study of dual and binary SMBHs and will reflect on broader implications of these findings when considering the current simulations of merging BH.
Marcello Petitta
Dipartimento di Matematica e Fisica, Università Roma Tre
Atmospheric symmetric circulation: how Cristoforo Colombo discovered America and why there are rainy winter in Europe
Link identifier #identifier__24570-8Locandina – 10 settembre 2024 ore 14:30 Aula C
This talk describes the main physical mechanisms of the symmetric atmospheric circulation, focusing on the dynamics of the tropical circulation and the mid-latitude circulation in the context of the Hadley and Ferrel cells. In this talk, we will also describe the impact of the symmetric circulation on historical events and present-day climate patterns. We will begin by examining the Hadley cell, which is characterized by rising warm air at the equator and descending cool air at subtropical latitudes. We move on to the Ferrel cell and examine its role in shaping Europe’s rainy winters. The Ferrel cell, which lies between the Hadley cell and the polar cell, generates the mid-latitude westerly winds that bring moist air from the Atlantic to Europe. This discussion analyses how the interaction between the Hadley cell and the Ferrel cell contributes to the North Atlantic Oscillation (NAO), which significantly influences European weather patterns. By linking the physical mechanisms of the Hadley and Ferrel cells to climate phenomena, this lecture emphasizes the crucial role of the different physical mechanisms responsible for atmospheric circulation. The insights gained relate to our understanding of the complex interplay between atmospheric dynamics and climatic events and emphasize the importance of atmospheric circulation for the interpretation of past and the prediction of future climate conditions.
Flaminia Giacomini
ETH Zurigo
Quantum effects in gravity from a delocalised quantum source
Link identifier #identifier__132322-9Locandina – 1 ottobre 2024 ore 14:30 Aula C
Understanding the fundamental nature of gravity at the interface with quantum theory is a major open question in theoretical physics. Recently, the study of gravitating quantum systems, for instance a massive quantum system prepared in a quantum superposition of positions and sourcing a gravitational field, has attracted a lot of attention: experiments are working towards realising such a scenario in the laboratory, and measuring the gravitational field associated to a quantum source is expected to give some information about quantum aspects of gravity. However, there are still open questions concerning the precise conclusions that these experiments could draw on the nature of gravity, such as whether experiments in this regime will be able to test more than the Newtonian part of the gravitational field. In my talk, I will first motivate why quantum information tools such as communication protocols can contribute to identifying quantum aspects of gravity in the low-energy regime. I will then present a new result, where a delocalised quantum source gives rise to effects that cannot be reproduced using the Newton potential nor with a known classical model of gravity. These effects can in principle be measured by performing an interference experiment, and are independent of graviton emission. Identifying stronger quantum aspects of gravity than those reproducible with the Newton potential is crucial to prove the non classicality of the gravitational field and to plan a new generation of experiments testing quantum aspects of gravity in a broader sense than what proposed so far.
Maria Grazia Izzo
Ca’ Foscari University of Venice, Department of Molecular Sciences and Nanosystems
A ferroelectric phase transition underlying the liquid-liquid phase transition in supercooled water
Link identifier #identifier__18877-10Locandina – 18 dicembre 2024 ore 14:30 Aula G
A liquid-liquid phase transition (LLPT) between a High-Density Liquid (HDL) and a Low-Density Liquid (LDL) below water’s freezing point, in the so-called supercooled regime, has emerged as a compelling hypothesis for explaining its equilibrium thermodynamic anomalies, which sets it apart from other liquids. Its origin has been so-far not clarified. On the other hand, water is a polar liquid and, as such, can, in principle, undergo a ferroelectric phase transition. This research introduces an original and far-reaching proposal: The LLPT can be driven by a ferroelectric phase transition. These results grounds on both analysis of extensive molecular dynamics simulations and a classical density functional theory in mean-field approximation valid for polar liquids. The theory reveals how the functional form of the dipolar interaction potential, which underpins density-polarization coupling, and the positional disorder in the liquid are essential for establishing this scenario. This study not only characterizes but shed light on the origin of the LLPT and thermodynamic anomalies in water. Understanding the origin of water’s peculiar behavior holds the key to uncovering fundamental mechanisms driving life and Earth’s processes. Explaining the peculiarities of water while treating it as a generic polar liquid, this study raises significant questions: Could the ferroelectric properties of water influence the natural selection of organisms and Earth’s geological evolution? Is water ‘merely’ a polar liquid with the microscopic characteristics suitable to allow a ferroelectric phase transition close to Earth’s environmental conditions? And what contribute to shaping its microscopic characteristics?