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Effective quantum gravitational collapse in a polymer framework
Get PDFWe study how the presence of an area gap, different than zero, affects the gravitational collapse of a dust ball. The implementation of such discreteness is achieved through the framework of polymer quantization, a scheme inspired by loop quantum gravity (LQG). We study the collapse using variables which represent the area, in order to impose the non-zero area gap condition. The collapse is analyzed for both the flat and spherical Oppenheimer-Snyder models. In both scenarios the formation of the singularity is avoided, due to the inversion of the velocity at finite values of the sphere surface. This happens due to the presence of a negative pressure, with origins at a quantum level. When the inversion happens inside the black hole event horizon, we achieve a geometry transition to a white hole. When the inversion happens outside the event horizon, we find a new possible astrophysical object. A characterization of such hypothetical object is done. Some constraints on the value for the area gap are also imposed in order to maintain the link with our already established physical theories
Climate Change and Soil Health: Explainable Artificial Intelligence Reveals Microbiome Response to Warming
Get PDFClimate change presents an unprecedented global challenge, demanding collective action to both mitigate its effects and adapt to its consequences. Soil health and function are profoundly impacted by climate change, particularly evident in the sensitivity of soil microbial respiration to warming, known as Q10. Q10 measures the rate of microbial respiration’s increase with a temperature rise of 10 degrees Celsius, playing a pivotal role in understanding soil carbon dynamics in response to climate change. Leveraging machine learning techniques, particularly explainable artificial intelligence (XAI), offers a promising avenue to analyze complex data and identify biomarkers crucial for developing innovative climate change mitigation strategies. This research aims to evaluate the extent to which chemical, physical, and microbiological soil characteristics are associated with high or low Q10 values, utilizing XAI approaches. The Extra Trees Classifier algorithm was employed, yielding an average accuracy of (Formula presented.), an average AUCROC of (Formula presented.), and an average AUCPRC of (Formula presented.). Additionally, through XAI techniques, we elucidate the significant features contributing to the prediction of Q10 classes. The XAI analysis shows that the temperature sensitivity of soil respiration increases with microbiome variables but decreases with non-microbiome variables beyond a threshold. Our findings underscore the critical role of the soil microbiome in predicting soil Q10 dynamics, providing valuable insights for developing targeted climate change mitigation strategies
Scaling transition of turbulent flame speed for thermodiffusively unstable flames
Get PDFThis work presents an experimental set of Bunsen flames characterized by a moderate Reynolds number and a variable turbulence intensity. Ten lean hydrogen-enriched methane-air mixtures at three turbulence levels are investigated, ranging from methane-air to hydrogen-air mixtures. Such mixtures are selected to have an almost constant laminar flame speed while inducing the onset of thermal-diffusive (TD) instability by gradually increasing the hydrogen content of the blend. The flames' global consumption speed, stretch factor, and flame surface area are investigated and discussed as functions of the effective Lewis number of the mixture. As the interplay between TD instability and turbulence enhances the overall flame propagation, below a transitional Lewis number, flames are observed to be particularly sensitive to external turbulent forcing. This synergistic interaction is discussed in terms of Karlovitz and Lewis numbers. A parameterization of the turbulent flame speed is thus proposed, based on a functional form depending, concurrently, on both Karlovitz and Lewis numbers. The proposed form is shown to fit the experimental results at different turbulence levels and to capture the flame speed enhancement across the transitional Lewis number
Turning climate-related information into added value for traditional Mediterranean grape, olive, and durum wheat food systems
Get PDFThe MED-GOLD project (https://doi.org/10.3030/776467) excee- ded expectations significantly. As a research and innovation project, MED-GOLD was expected to co-develop climate services at proof-of- concept (i.e., prototype) rather than real market level. By contrast, not only was MED-GOLD able to demonstrate the added value of the pilot climate services, but it also addressed the replicability and marketability side of the services to the point that major European and international institutions showed interest in the MED-GOLD climate services and ICT platform, creating real business opportunities during the project life- cycle and beyond the duration of the project. MED-GOLD was a 54-month research and innovation project with the initial goal of demonstrating the proof-of-concept for climate ser- vices in agriculture using three hallmarks of the Mediterranean food system: grape and wine, olive and olive oil, and durum wheat and pasta. The project sought to prototype climate services by developing case studies for these three major Mediterranean traditional systems. This MED-GOLD Special Issue provides evidence of the added value resulting from the co-development of pilot climate services in agricul- ture, using case studies co-developed with Sogrape (https://sogrape. com/en) for grape and wine in the Douro region of Portugal, with DCOOP (https://www.dcoop.es/) for olive and olive oil in the Andalusia region of Spain, and with Barilla G. e R. Fratelli S.p.A. (https://www. barilla.com/en-us) for durum wheat and pasta in Ital
The CRILIN calorimeter: gamma radiation resistance of crystals and SiPMs
Get PDFThe Crilin calorimeter is a semi-homogeneous calorimetric system based on Lead Fluoride (PbF2) crystals with UV-extended Silicon Photomultipliers (SiPMs) proposed for the Muon Collider. This study investigates the radiation resistance of crystals and SiPMs, subjected to 10 kGy gamma irradiation, equivalent to a 10-year service life in the Muon Collider. Our findings indicate that while PbF2 crystals exhibit a decrease in transmittance post-irradiation with partial recovery over time, the alternative PbWO4-Ultra Fast (PWO-UF) demonstrates exceptional radiation hardness, maintaining stable transmittance. SiPMs showed an increase in dark current and breakdown voltage post-irradiation, with less degradation observed in the SiPM biased during the exposure to radiation compared to the unbiased component. These results underscore the viability of PbF2 for radiation-tolerant calorimeters, though improvements in production homogeneity are needed. The superior performance of PWO-UF crystals suggests they are a promising alternative for high-radiation applications, but their higher cost must be carefully considered
Modello semianalitico per il calcolo della dose tridimensionale depositata in acqua da un fascio di protoni a sezione gaussiana
Get PDFNell’ambito del progetto TOP-IMPLART, è in fase di sviluppo e collaudo un prototipo di acceleratore lineare di protoni a radiofrequenza e modulazione attiva destinato a un utilizzo per terapia adronica. In previsione dell’elaborazione di piani di trattamento ideati ad hoc per testare le prestazioni del linac, è desiderabile disporre di uno strumento snello per il design di picchi di Bragg allargati nelle tre dimensioni spaziali. La possibilità di sfruttare una rappresentazione matematica analitica del volume di dose depositato in acqua dal fascio di protoni emesso dal linac permette, in linea di principio, una realizzazione più agevole di tale strumento. A tale scopo, in questa relazione si illustra la derivazione di una formula analitica per il calcolo approssimato della distribuzione spaziale di dose nelle tre dimensioni utilizzando i modelli analitici di Bortfeld e di Preston-Koehler. I risultati ottenuti con tale formula vengono confrontati con simulazioni Monte Carlo condotte in FLUKA.As part of the TOP-IMPLART project, a prototype of a radiofrequency proton linear accelerator with active modulation is currently being developed and tested for use in hadron therapy. In anticipation of designing tailored treatment plans to test the linac's performance, it is desirable to have a streamlined tool for designing expanded Bragg peaks in three spatial dimensions. The ability to utilize an analytical mathematical representation of the dose volume deposited in water by the proton beam emitted from the linac facilitates, in principle, the creation of such a tool. To this end, this report presents the derivation of an analytical formula for the approximate calculation of the three-dimensional spatial dose distribution using the analytical models of Bortfeld and Preston-Koehler. The results obtained with this formula are compared with Monte Carlo simulations conducted in FLUKA
Dynamical downscaling of CMIP6 scenarios with ENEA-REG: an impact-oriented application for the Med-CORDEX region
Get PDFIn the framework of the coordinated regional modeling initiative Med-CORDEX (Coordinated Regional Climate Downscaling Experiment), we present an updated version of the regional Earth System Model ENEA-REG designed to downscale, over the Mediterranean basin, the models used in the Coupled Model Intercomparison Project phase 6 (CMIP6). The regional ESM includes coupled atmosphere (WRF), ocean (MITgcm), land (Noah-MP, embedded within WRF), and river (HD) components with spatial resolution of 12 km for the atmosphere, 1/12° for the ocean and 0.5° for the river rooting model. For the present climate, we performed a hindcast (i.e. reanalysis-driven) and a historical simulation (GCM-driven) over the 1980–2014 temporal period. The evaluation shows that the regional ESM reliably reproduces the mean state, spatial and temporal variability of the relevant atmospheric and ocean variables. In addition, we analyze the future evolution (2015–2100) of the Euro-Mediterranean climate under three different scenarios (SSP1-2.6, SSP2-4.5, SSP5-8.5), focusing on several relevant essential climate variables and climate indicators for impacts. Among others, results highlight how, for the scenarios SSP2-4.5 and SSP5-8.5, the intensity, frequency and duration of marine heat waves continue to increase until the end of the century and anomalies of up to 2 °C, which are considered extreme at the beginning of this century, will be so frequent to become the norm in less than a hundred years under the SSP5-8.5 scenario. Overall, our results demonstrate the improvement due to the high-resolution air–sea coupling for the representation of high impact events, such as marine heat waves, and sea-level height
Rapid Non-Contact Detection of Chemical Warfare Agents by Laser Photoacoustic Spectroscopy
Get PDFNerve agents have recently been used in battlefield operations, espionage wars, and terrorist attacks. These compounds, like some pesticides, cause organophosphate poisoning. The rapid, noncontact detection of a sarin simulant in the liquid phase has been demonstrated at the Diagnostics and Metrology Laboratory of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development using laser photoacoustic spectroscopy, an infrared absorption technology. The first measurements, carried out with an experimental system based on a quantum cascade laser and developed for the assessment of food authenticity in the “fingerprint region”, show that a detection limit of one nanolitre is within the reach of the instrument when chemometric analysis is applied
An overview of the evolution of the modeling of reflectometry diagnostics in fusion plasmas using finite-difference time-domain codes
Get PDFMicrowave reflectometry, having its origins in ionosphere probing techniques to evaluate electronic density, has become one of the most important diagnostics for the same quantity in fusion plasmas. Reflectometry will play a major role in next-generation machines, in particular in DEMO, where it is expected to provide plasma positioning, shaping, and tracking data. The ability to have an ever-increasing comprehensive description of reflectometry is particularly important since it allows us to assess the measuring capabilities of existing experimental systems and to predict the performance of new diagnostic concepts based on probing waves. Furthermore, wave propagation in a thermonuclear plasma with fluctuating electronic densities is far from straightforward and the need for a numerical full-wave treatment becomes fundamental. We will present the reader with the fundamentals of this technique and introduce the usage and evolution of FDTD in reflectometry, using as an example, the synthetic diagnostics setup that uses the family of REFMUL* codes, which is employed in the assessment of the performance of several reflectometry systems in different fusion machines
Predicting the impact of public events and mobility in Smart Cities
Get PDFThe ubiquitous presence of smartphones and the ever-expanding Internet of Things are generating a treasure trove of data on human movement. We harness the power of Artificial Intelligence to extract knowledge within this data, in particular for predicting people flows and density in a Smart City. This predictive ability holds immense potential for a multitude of applications, from optimising people flow to streamlining event planning, while offering a powerful tool for pre-emptive identification of situations that may lead to crowd disasters. In this paper, we tackle two crucial aspects of people mobility using data from public events and an Italian mobile phone network: to predict both event attendance and future crowd density in specific areas. The event details (location, time etc.) are automatically gathered and stored in a structured format. Next, we handle these problems are treated in a “supervised learning” setting, and various state-of-art Machine Learning techniques are tested to find the best model for each task. The obtained models will be encapsulated into a Policy Support System contributing to foster planning actions of mobility services