483 research outputs found

    Attosecond transient absorption spectroscopy of helium above the N=2 ionization threshold

    Full text link
    Attosecond transient absorption spectroscopy (ATAS) allows for the study of electron dynamics in atoms and molecules with attosecond time resolution. Previous works reported in the literature have made use of ATAS to image and control such dynamics in the single-channel ionization continuum of helium; in particular, in the vicinity of the doubly excited autoionizing states lying between the N=1 and N=2 thresholds. In this work, we have extended these studies to autoionizing states lying above the N=2 threshold, where several ionization channels are open. From an accurate solution of the time-dependent Schrödinger equation, we predict the appearance of pronounced one-photon beatings between the 3snp states and the adjacent 1Se and 1De resonances, as well as, more surprisingly, two-photon beatings between the 3s3p doubly excited state and the 1Po nonresonant continuum. Both effects lead to a significant distortion of the 3snp Fano profiles and to a strong variation of these profiles with the pump-probe delay, thus demonstrating control of the corresponding multichannel two-electron correlated wave packets, in the same way as reported for resonances lying below the N=2 thresholdWe would like to acknowledge allocation of computer time at Mare Nostrum BSC and CCC-UAM. This work was supported by the European Research Council Advanced Grant No. XCHEM 290853, the MINECO Projects No. FIS2013-42002-R and No. FIS2016-77889-R, the European COST Action XLIC CM1204, and the CAM project NANOFRONTMAG. L.A. acknowledges support from the TAMOP NSF Grant No. 1607588, as well as UCF funding

    Functional needs, emotions, and perceptions of coffee consumers and non-consumers

    Get PDF
    Coffee is one of the most consumed beverages worldwide. Over the last decades coffee has become a specialty product. Drinking a coffee beverage entails several mixed factors, such as pleasure, experience, lifestyle, and social status. It can also provide an emotional pick-up, both mentally and physically. Only a few studies have explored the motives and emotions of coffee consumption and not consumption. There is limited understanding of consumers' emotional approach towards coffee, and what influences a positive and negative inclination towards coffee consumption. This research fills the current research gaps by addressing three main questions: (i) What are the emotions and habits of coffee consumption? (ii) What are the motives of coffee consumption and non-consumption? and (iii) How relevant is the coffee health impact perception of consuming or not consuming coffee? The research activities include 467 face-to-face interviews with consumers. Interviews are performed in two different countries, Italy and Portugal. Data elaboration includes a principal component analysis carried out to identify latent factors on motives and emotions of consumption in both national groups, and to explore the relationship between the main emotions and consumers' habits and socio-economic characteristics. Results support that consumers have positive emotions from coffee consumption. Perceived emotions are energy, satisfaction, and pleasure. Non-consumption is mainly driven by taste and fear of coffee's health impacts. There are limited differences in the countries analysed. Socio-economic characteristics limitedly influence perceived emotions and consumption motives. To conclude, consumers are increasingly interested in new coffee products. Understanding the functional and emotional factors of coffee consumption contributes to supporting new coffee product development and commercialisation

    A Deep Learning Approach to Ancient Egyptian Hieroglyphs Classification

    Get PDF
    Nowadays, advances in Artificial Intelligence (AI), especially in machine and deep learning, present new opportunities to build tools that support the work of specialists in areas apparently far from the information technology field. One example of such areas is that of ancient Egyptian hieroglyphic writing. In this study, we explore the ability of different convolutional neural networks (CNNs) to classify pictures of ancient Egyptian hieroglyphs coming from two different datasets of images. Three well-known CNN architectures (ResNet-50, Inception-v3 and Xception) were taken into consideration and trained on the available images. The paradigm of transfer learning was tested as well. In addition, modifying the architecture of one of the previous networks, we developed a specifically dedicated CNN, named Glyphnet, tailoring its complexity to our classification task. Performance comparison tests were carried out and Glyphnet showed the best performances with respect to the other CNNs. In conclusion, this work shows how the ancient Egyptian hieroglyphs identification task can be supported by the deep learning paradigm, laying the foundation for information tools supporting automatic documents recognition, classification and, most importantly, the language translation task

    Multi-polariton control in attosecond transient absorption of autoionizing states

    Full text link
    Tunable attosecond transient absorption spectroscopy is an ideal tool for studying and manipulating autoionization dynamics in the continuum. We investigate near-resonant two-photon couplings between the bright 3s^-1 4p and dark 3s^-1 4f autoionizing states of argon that lead to Autler-Townes like interactions, forming entangled light-matter states, or polaritons. We observe that one-photon couplings with intermediate dark states play an important role in this interaction, leading to the formation of multiple polaritonic branches whose energies exhibit avoided crossings as a function of the dressing-laser frequency. Our experimental measurements and theoretical essential-state simulations show good agreement and reveal how the delay, frequency, and intensity of the dressing pulse govern the properties of autoionizing polariton multiplets. These results demonstrate new pathways for quantum control of autoionizing states with optical fields.Comment: 8 pages, 6 figure

    Feeding evaluation of spontaneous species used by wild ungulates

    Get PDF
    Abandonment of traditional agricultural practices can produce remarkable effects on land use and on the vegetal composition of marginal areas. This is particularly true in the once grazed zones in the mountain environments, that are now affected by encroachment of shrubby vegetation. The conservation of these open areas and the preservation of a correct ratio pasture/wood are of extremely importance for wild animals. In this note we describe the effectiveness of agronomical intervention carried out to enhance pasture quality in a protected area of central Italy. Data collection concerned botanical composition, floristic richness and biodiversity of vegetation, before and after the intervention efforts. Moreover, data on utilization of single species were collected in order to evaluate the real consumption of each plant species by wild animals. Results confirmed the efficiency of the improvement of the studied area in terms of botanical composition and of pastoral value and they provided useful indications about the actual utilization of non forage plants by wild ungulates

    Butterflies as bioindicators of metal contamination

    Get PDF
    Anthropogenic trace metal contamination has significantly increased and has caused many hazardous consequences for the ecosystems and human health. The Terni basin valley (Central Italy) shows a heavy load of pollutants from industrial activities, while the characteristic orography structure of the valley favours air stagnation, thus limiting air pollution dispersal. The present study conducted in 2014 aimed to determine the concentration of ten metals in five species of butterflies at nine sites in the Terni valley along a 21-km-long transect, including both relatively pristine and industrial areas. At sites where soil contamination was high for a given metal, such as for chromium as in the case of site 4 (the closest to the steel plant) and for lead as in the case of site 2 (contaminated by a firing range), higher levels of contamination were observed in the tissues of butterflies. We found a correlation between soil contamination and the concentration of Cr, Al and Sr in the tissues of some species of butterflies. The sensitivity to contamination differed among the five species; in particular, Coenonympha pamphilus was generally the species that revealed the highest concentrations of all the ten trace metals at the sites closer to the industrial area. It is known that C. pamphilus is a sedentary species and that its host plants are the Poaceae, capable of accumulating high quantities of metals in their rhizosphere region, thus providing the link with soil contamination. Therefore, monitoring the metal concentration levels in butterflies might be a good indicator and a control tool of environmental quality, specifically in areas affected by high anthropogenic pollution loads linked to a specific source
    corecore