laser – Progress in Research

A 4D digital geographical atlas of the Appia Antica Archaeological Park

Posted on 23/06/202206/08/2024 by Erik Franco

The Appia Antica Archaeological Park (PAAA) and the Politecnico di Milano have launched a vast organic and systematic survey and digitization project in the Park area with the aim of giving shape to a modern geographical atlas that is configured as a ‘4D living digital twin’. A model intended for experts, curators and users, to be expanded and monitored over time.

The work is carried out by the GIcarus-ABCLabinterdisciplinary survey and representation laboratory of the Politecnico di Milano with the coordination of the PAAA.

The Appia Antica Archaeological Park was established in 2016 and is the largest protected urban area in Europe, with 4,500 hectares of landscape with archaeological areas that follow one another, along the more than 16 km of the Via Appia Antica ‘Regina Viarum’ .

In less than a year, the first Roman complexes and infrastructures have been digitized: the Claudius-Anio Novus Imperial Aqueduct, an 11.7 km stretch of the Via Appia Antica, the Tomb of Cecilia Metella, the Imperial Villa of the Quintili, as well as some museum sculptures.

The result was a first real 4D digital geographic atlas of over 200,000 images and 20 TB of data and models.

“A digital twin that includes the past and future to n-dimensions, made up of information models to support projects and conservative monitoring, seismic vulnerability plans, that is connectable to IOT WiFi sensors. Implementable, updatable and searchable, it allows synchronic and diachronic correlations, adding knowledge as it grows. Re-usable for the dissemination of contents and interactive, immersive and remote use”, explains Professor Raffaella Brumana of GIcarus ABCLab.

The high-precision survey was carried out using terrestrial and portable laser scanners (TLSs – Terrestrial Laser Scanners, and MMS – Mobile Mapping System), terrestrial and aerial photogrammetry, drones, spherical cameras and multispectral sensors and allowed a 4-dimensional HBIM model (space and time) to be obtained which, when correlated to historical information, materials and sensors for monitoring instability and decay, makes it possible to compare the construction techniques that have occurred over the centuries.

The project also envisages the development of an interactive XR (eXtended Reality) platform for the remote dissemination of all contents, which will be tested as the digitization products become available and which will also allow the virtual relocation of nearby and distant collections. digitized sculptures, and to simulate portions that have disappeared starting from the traces found to help their understanding.

The project team

All activities were coordinated by Architect Simone Quilici, Director of the PAAA, together with the technical and scientific staff of the Park, in particular the Archaeologists Stefano Roascio, Francesca Romana Paolillo, the Architects Luigi Oliva, Clara Spallino, Aura Picchione, Michele Reginaldi and Raffaella Rocchetta, the Restorer Sara Iovine.

The Scientific Coordinators for the Politecnico di Milano are Raffaella Brumana and Mattia Previtali, Fabrizio Banfi. Fabio Roncoroni,Chiara Stanga, Dario Attico, Luca Bertola and Marzia Gabriele also collaborated.

Discovery of a new phase transition in quasi-crystals

Posted on 07/03/202206/08/2024 by Erik Franco

A team of researchers from the Politecnico di Milano and the University of Rostock (Germany) has discovered and observed in the laboratory a new type of phase transition in a quasi-crystal made of laser light.

The discovery of this new phase transition in quasi-crystals represents a breakthrough in the understanding of some fundamental phenomena of quantum matter.

Quasi-crystals are structures that are not perfectly ordered, like crystals, but not completely disordered and are among the rarest structures in nature. In order to study their characteristics, the team of experimental physicists made in the laboratory a quasi-crystal with laser light that propagates in an intertwined manner in kilometre-long optical fibres: the complex dynamics of light in these fibres closely mirrors the quantum motion of electrons in the quasi-crystal. During the experiment, the researchers observed a triple phase transition, in which the topological properties, conductivity, and energy exchange between the quasi-crystal and its surroundings change abruptly but at the exact same time.

The discovery was published in the journal Nature and could pave the way for a holistic understanding of the inner workings of complex or engineered materials and their use in advanced phase-controlled materials-based applications.

The discovery of this new phase transition in quasi-crystals represents a breakthrough in the understanding of some fundamental phenomena of quantum matter. It may also pave the way for the development of a new technology and type of material unlike anything we have seen before, the properties of which we will be able to simultaneously control and modify at will. It would be a new form of matter much more flexible and controllable than the one we currently know about.
Stefano Longhi, professor at the Department of Physics of the Politecnico and co-author of the study

The article published in Nature

Lasers allow discovering how DNA protects itself from sunlight

Posted on 17/01/202206/08/2024 by Erik Franco

A new study published in the prestigious journal Nature Communications explains how DNA is protected from mutations caused by ultraviolet light via its constituent elements, nucleosides. The results, obtained by using extremely short pulses of light, may lead to important applications in nanotechnology and pharmacology, such as fighting skin tumours.

The study was conducted by a team of researchers at the Institute for Photonics and Nanotechnology under the National Research Council (CNR-IFN), the Politecnico di Milano, the Università di Bologna, the Università della Tuscia, and Heinrich Heine Universität Düsseldorf.

Studying how nucleosides interact with light on very short timescales is essential for understanding the complex physical processes that lead to DNA photodamage,
Rocío Borrego-Varillas, first author, researcher at the CNR-IFN and the Politecnico di Milano.

Lasers enable incredibly short pulses of light to be generated with a duration of a few millionths or billionths of a second. They also allow us to observe very quick phenomena, such as the fundamental processes that occur when light interacts with living organisms, for example, in vision or photosynthesis.

DNA, the molecule that encodes the information necessary for building proteins, efficiently absorbs the UV component of sunlight, a property common to many biomolecules. Due to the high energy of UV radiation, its absorption may trigger a chain of chemical reactions, with the resulting corruption of information encoded in the sequence of bases (photodamage) and serious consequences (such as skin tumours). Fortunately, in most cases, DNA molecules are able to efficiently dissipate the energy contained in UV light due to a photoprotective process that inhibits damage.

In nucleosides, these processes are particularly efficient due to the speed with which the absorbed energy is dissipated, but it is precisely this speed which makes their study so difficult, something which has long been debated by scientists; hence the idea to use ultra short pulses of light to trigger these processes and follow all the phases in their evolution. The technique was applied to the study of two nucleosides: uridine and methyluridine. By observing molecular processes on such short timescales, the researchers have been able to understand for the first time the mechanism through which nucelosides dissipate the energy deposited by UV light.

The difficulty with studying such fast molecular processes is similar to taking a picture of a car moving at full speed. To prevent the picture from looking fuzzy, a short exposure time is chosen. If we want to capture images of a molecular process that lasts less than a millionth of a second, we need very short flashes of UV light.