86,688 research outputs found
Studio retrospettivo delle intossicazioni accidentali in una Divisione Pediatrica del Lazio: casi di ingestione di detergenti in ambiente domestico.
No full textCalcareous nannofossil fluctuations during the late Hauterivian in the Cismon core (Venetian Alps, northeastern Italy) and in selected sections of the Umbria-Marche Basin (central Italy) : paleoceanographic implications of the Faraoni Level
No full textCalcareous nannofossil quantitative analyses were carried out on upper Hauterivian sediments from the Cismon core and results from the uppermost Hauterivian "Faraoni Level" were compared to nannofloral fluctuations in abundance and composition recorded in the S.S. Arceviese road and Palazzo D'Arcevia sections, Umbria-Marche Basin (central Italy). Fragile taxa are generally absent since the preservation is poor in all lithologies analyzed, but dissolution-resistant taxa show remarkable fluctuations. Smear-slide investigations reveal that limestones are characterized by high abundances of nannoconids (principally narrow-canal nannoconids) suggesting oligotrophic conditions throughout the interval investigated. Conversely, nannoconids are rare or absent in black shales, whereas Assipetra infracretacea and Rucinolithus terebrodentarius are prevailing. In addition, high abundances of pentaliths are recorded in limestones through the interval preceding the deposition of the Faraoni Level. This finding possibly suggests a decrease in salinity of surface waters. Different paleoceanographic regimes seem to have triggered repetitive changes in abundance and composition of nannofloral assemblages. Limestones were plausibly deposited under oligotrophic conditions, whilst black shales may suggest increasing primary productivity. Thin section investigations show a drop in abundance of pentaliths and a marked decrease of narrow-canal nannoconids starting definitively before and reaching a minimum in the Faraoni Level. In the black shales bounding the ammonite-rich Guide Bed, A. infracretacea and R. terebrodentarius become dominant. Such nannofloral changes may suggest enhanced primary productivity and more arid conditions associated with dysoxic bottom waters. We stress the fact that nannofloral variations recorded in the Faraoni Level are not exclusive, but match the repetitive nannofloral-lithological fluctuations preceding and following it. Perhaps, the paleoenvironmental changes triggering the Faraoni event were not affecting calcareous phytoplankton or represent the over-reaching of threshold conditions after gradual and progressive modifications in nutrient availability
Averaging inhomogeneities in scalar-tensor cosmology
No full textThe backreaction of inhomogeneities on the cosmic dynamics is studied in the context of scalar-tensor gravity. Due to terms of indefinite sign in the non-canonical effective energy tensor of the Brans-Dicke-like scalar field, extra contributions to the cosmic acceleration can arise. Brans-Dicke and metric f(R) gravity are presented as specific examples. Certain representation problems of the formalism peculiar to these theories are pointed out
Beyond Einstein Gravity: A Survey of Gravitational Theories for Cosmology and Astrophysics
No full textBeyond Einstein’s Gravity is a graduate level introduction to extended theories of gravity and cosmology, including variational principles, the weak-field limit, gravitational waves, mathematical tools, exact solutions, as well as cosmological and astrophysical applications. The book provides a critical overview of the research in this area and unifies the existing literature using a consistent notation. Although the results apply in principle to all alternative gravities, a special emphasis is on scalar-tensor and f(R) theories. They were studied by theoretical physicists from early on, and in the 1980s they appeared in attempts to renormalize General Relativity and in models of the early universe. Recently, these theories have seen a new lease of life, in both their metric and metric-affine versions, as models of the present acceleration of the universe without introducing the mysterious and exotic dark energy. The dark matter problem can also be addressed in extended gravity. These applications are contributing to a deeper understanding of the gravitational interaction from both the theoretical and the experimental point of view. An extensive bibliography guides the reader into more detailed literature on particular topics
Is de Sitter space always excluded in semiclassical f(R) gravity?
No full textIt is shown that the recent corpuscular description of gravity generically excludes de Sitter spacetime in any semiclassical version of f(R) gravity. A phantom phenomenology of the cosmic dynamics is also naturally excluded
Effects of the social context on the neurophysiological correlates of observed error monitoring
No full textMonitoring the motor performance of others, including the correctness of their actions, is crucial for the human
behavior. However, while performance (and error) monitoring of the own actions has been studied extensively at
the neurophysiological level, the corresponding studies on monitoring of others’ errors are scarce, especially for
ecological actions. Moreover, the role of the context of the observed action has not been sufficiently explored. To
fill this gap, the present study investigated electroencephalographic (EEG) indices of error monitoring during
observation of images of interrupted reach-to-grasp actions in social (an object held in another person’s hand)
and non-social (an object placed on a table) contexts. Analysis in time- and time-frequency domain showed that,
at the level of conscious error awareness, there were no effects of the social context (observed error positivity was
present for erroneous actions in both contexts). However, the effects of the context were present at the level of
hand image processing: observing erroneous actions in the non-social context was related to larger occipito-
temporal N1 and theta activity, while in the social context this pattern was reversed, i.e., larger N1 and theta
activity were present for the correct actions. These results suggest that, in case of easily predictable ecological
actions, action correctness is processed as early as at the level of hand image perception, since the hand posture
conveys information about the action (e.g., motor intention). The social context of actions might make the
correct actions more salient, possibly through the saliency of the correctly achieved common goal
The big data-business strategy interconnection: a grand challenge for knowledge management. A review and future perspectives
No full textPurpose: Designing knowledge management (KM) systems capable of transforming big data into information characterised by strategic value is a major challenge faced nowadays by firms in almost all industries. However, in the managerial field, big data is now mainly used to support operational activities while its strategic potential is still largely unexploited. Based on these considerations, this study proposes an overview of the literature regarding the relationship between big data and business strategy. Design/methodology/approach: A bibliographic coupling method is applied over a dataset of 128 peer-reviewed articles, published from 2013 (first year when articles regarding the big data-business strategy relationship were published) to 2019. Thereafter, a systematic literature review is presented on 116 papers, which were found to be interconnected based on the VOSviewer algorithm. Findings: This study discovers the existence of four thematic clusters. Three of the clusters relate to the following topics: big data and supply chain strategy; big data, personalisation and co-creation strategies and big data, strategic planning and strategic value creation. The fourth cluster concerns the relationship between big data and KM and represents a ‘bridge’ between the other three clusters. Research limitations/implications: Based on the bibliometric analysis and the systematic literature review, this study identifies relevant understudied topics and research gaps, which are suggested as future research directions. Originality/value: This is the first study to systematise and discuss the literature concerning the relationship between big data and firm strategy
I siti web dei partiti
No full textI siti web dei partiti: strategie di comunicazione e scelte linguistiche in occasione della campagna elettorale che ha preceduto le elezioni politiche del 2016
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