1,721,188 research outputs found
Percorso sostenibile dalle emissioni industriali alle foreste per la compensazione della CO2.
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ACCELERATION SCHEMES FOR AB-INITIO MOLECULAR-DYNAMICS SIMULATIONS AND ELECTRONIC-STRUCTURE CALCULATIONS
No full textWe study the convergence and the stability of fictitious dynamical methods for electrons. First, we show that a particular damped second-order dynamics has a much faster rate of convergence to the ground state than first-order steepest-descent algorithms while retaining their numerical cost per time step. Our damped dynamics has efficiency comparable to that of conjugate gradient methods in typical electronic minimization problems. Then, we analyze the factors that limit the size of the integration time step in approaches based on plane-wave expansions. The maximum allowed time step is dictated by the highest frequency components of the fictitious electronic dynamics. These can result either from the large wave vector components of the kinetic energy or from the small wave vector components of the Coulomb potential giving rise to the so called charge sloshing problem. We show how to eliminate large wave vector instabilities by adopting a preconditioning scheme in the context of Car-Parrinello ab initio molecular-dynamics simulations of the ionic motion. We also show how to solve the charge sloshing problem when this is present. We substantiate our theoretical analysis with numerical tests on a number of different silicon and carbon systems having both insulating and metallic character
Continuous fake media detection: Adapting deepfake detectors to new generative techniques
Full text linkGenerative techniques continue to evolve at an impressively high rate, driven by the hype about these technologies. This rapid advancement severely limits the application of deepfake detectors, which, despite numerous efforts by the scientific community, struggle to achieve sufficiently robust performance against the ever-changing content. To address these limitations, in this paper, we propose an analysis of two continuous learning techniques on a Short and a Long sequence of fake media. Both sequences include a complex and heterogeneous range of deepfakes (generated images and videos) from GANs, computer graphics techniques, and unknown sources. Our experiments show that continual learning could be important in mitigating the need for generalizability. In fact, we show that, although with some limitations, continual learning methods help to maintain good performance across the entire training sequence. For these techniques to work in a sufficiently robust way, however, it is necessary that the tasks in the sequence share similarities. In fact, according to our experiments, the order and similarity of the tasks can affect the performance of the models over time. To address this problem, we show that it is possible to group tasks based on their similarity. This small measure allows for a significant improvement even in longer sequences. This result suggests that continual techniques can be combined with the most promising detection methods, allowing them to catch up with the latest generative techniques. In addition to this, we propose an overview of how this learning approach can be integrated into a deepfake detection pipeline for continuous integration and continuous deployment (CI/CD). This allows you to keep track of different funds, such as social networks, new generative tools, or third-party datasets, and through the integration of continuous learning, allows constant maintenance of the detectors
Relationship between pre-slaughter handling and carcass bruising in calves
Full text linkSono stati esaminati i tempi di svolgimento delle operazioni di carico, scarico, sosta e attesa pre-stordimento di 105 vitelli a carne bianca di razza Frisona. Inoltre, durante tali operazioni è stata rilevata la frequenza di eventi quali la caduta, l’inversione, la testata, la monta, il rifiuto di movimento, il salto, la scivolata, l’evacuazione e la vocalizzazionenonché il numero di applicazioni di pungolo elettrico. Sulle carcasse si è poi proceduto all’individuazione e alla classificazione delle lesioni superficiali utilizzando una scala a tre classi (1=assente, 2=leggera, 3=grave) allo scopo di esaminarne le relazioni con la durata delle operazioni pre-macellazione e con la frequenza degli eventi comportamentali. I tempi di svolgimento delle operazioni di scarico e di sosta hanno influenzato significativamente(P<0,01) la distribuzione delle carcasse nelle tre classi di lesioni. Inoltre, lesioni sia leggere che gravi sono risultate presenti nelle carcasse provenienti da soggetti che, in media, hanno presentato una maggior frequenza di cadute o di monte e una minor frequenza d’evacuazioni durante le operazioni pre-macellazione
Economics and finance of lead fast reactors: A systematic literature review
Full text linkGeneration IV (Gen-IV) nuclear reactor designs are receiving increasing attention because of their potential to achieve key goals in terms of sustainability, safety, reliability, and economics. One of the six technologies selected in the Gen-IV program is the lead-cooled fast reactor (LFR). This work focuses on LFRs, examining both pure lead and lead-bismuth eutectic designs. Through two systematic literature reviews, we consolidate the state-of-the-art in economics and finance for LFRs. The first review considers scientific literature and retrieves 12 articles. The second focuses instead on industrial literature, resulting in 12 additional documents. Economics literature is very scarce and sometimes of low quality. Economic estimations for the specific capital cost [/MWh] can vary by an order of magnitude (1500–25000 /MWh, respectively), while design organizations typically do not publicly share financial details. Finance literature is almost nonexistent. We report, in the final part of the work, notable knowledge gaps and further possible research areas
Relationship between pre-slaughter handling and carcass bruising in calves
Full text linkRelazione tra le operazioni pre-macellazione e le lesioni sulla carcassa di vitello. Sono stati esaminati i tempi di svolgimento delle operazioni di carico, scarico, sosta e attesa pre-stordimento di 105 vitelli a carne bianca di razza Frisona. Inoltre, durante tali operazioni è stata rilevata la frequenza di eventi quali la caduta, l’inversione, la testata, la monta, il rifiuto di movimento, il salto, la scivolata, l’evacuazione e la vocalizzazione nonché il numero di applicazioni di pungolo elettrico. Sulle carcasse si è poi proceduto all’individuazione e alla classificazione delle lesioni superficiali utilizzando una scala a tre classi (1=assente, 2=leggera, 3=grave) allo scopo di esaminarne le relazioni con la durata delle operazioni pre-macellazione e con la frequenza degli eventi comportamentali. I tempi di svolgimento delle operazioni di scarico e di sosta hanno influenzato significativamente (P<0,01) la distribuzione delle carcasse nelle tre classi di lesioni. Inoltre, lesioni sia leggere che gravi sono risultate presenti nelle carcasse provenienti da soggetti che, in media, hanno presentato una maggior frequenza di cadute o di monte e una minor frequenza d’evacuazioni durante le operazioni pre-macellazion
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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