1,721,052 research outputs found
An application of social network analysis to assess virtual innovation team performance
No full textIn this paper we analyze the existing relationship between the structural configuration of a Virtual Innovation Team and its creative performance. The structural configuration of a Virtual Innovation Team is the approach utilised by the group in the management and decision-making phases regarding both the communicative structure and the decisional style. Actually the scientific literature hardly explore the issue of the creative performance in a Virtual Team and contribution regarding Virtual Innovation Team are even more scarce.
In order to analyse the structural configuration we consider: average frequency of communication, two parameters of Social Network Analysis (network degree centralization and flow betweenness centralization), variety and variability in the use of ICT and decisional style. The creative performance is measured through fluency (ability to generate various proposals), flexibility (ability to produce versatile solutions), and originality (ability to identify unique solutions). Our analysis is applied to a real case study based on a Finmeccanica project, consisting in a contest between Virtual Innovation Teams with the aim to improve the portal of the corporate
Effect of frontal 30-Hz-tACS on subjective and objective sleepiness.
No full textTranscranial Current stimulations (tCSs) are non-invasive brain stimulation techniques which are able to modulate cortical excitability and spontaneous brain activity in a safe and quite predictive manner. In tACS protocols, the current is time-varying and the stimulation interfers with the spontaneous brain oscillations, according to the principle of entrainment. Previous studies showed that frontal-5-Hz-tDCS is able to induce an increase in subjective sleepiness associated to an enhancement of the delta EEG activity. Here, we evaluated the ability of high-frequency-tACS to modulate sleepiness in the opposite direction, i.e. to reduce sleepiness and slow-frequency activity.
Ten subjects underwent a within-subject study (Active/Sham), with 30-min session (10-min pre-stimulation EEG; 10-min 30-Hz-tACS; 10-min post-stimulation EEG). During the whole protocol subjects were asked to stay relaxed with eyes closed. Self-reported sleepiness measures were collected before and after each stimulating session. The active stimulation was associated to decreased sleepiness in the post-stimulation interval, while the sham stimulation showed an increase in sleepiness scores. This pattern was coherent with the EEG data, with respect to the delta and gamma bands. In fact, compared to the sham condition, the active stimulation resulted in smaller increases of slow-frequency activity and in an increase of high-frequency activity.
These results show that frontal-30-Hz-tACS is able to contrast the spontaneous increase of sleepiness during resting-state. This sleep-preventing effect, as well as our previous findings, opens up fascinating perspectives for a bidirectional manipulation of sleepiness by tCSs, with possible applications in basic and clinical sleep research
Metodi e tecniche di stimolazione transcranica durante il sonno
No full textIl capitolo presneta una completa, estesa e a aggiornata rassegna degli studi che hanno utilizzato tecniche innovative in Psicofisiologia del sonn
Effects of fronto-temporal 5 Hz-tACS on subjective and objective sleepiness
No full textRecent findings showed that oscillating transcranial Direct Current Stimulation (osc-tDCS) and transcranial Alternating Current Stimulation (tACS) applied during wake and sleep can interact with the ongoing brain activity in a frequency-specific manner. Here, we evaluated the efficacy of a bilateral 5Hz-tACS on fronto-temporal areas in modulating physiological sleepiness during wakefulness, by inducing synchronization in cortical and subcortical structures involved in the sleep onset.
Twenty-six healthy volunteers (18-35 years) participated in two within-subject sessions (Active and Sham), one week apart and in counterbalanced order.
Each session involved: 5-min pre-stimulation EEG; 10-min tACS stimulation; 5-min post-stimulation EEG. The self-reported levels of sleepiness were collected with the Karolinska Sleepiness Scale (KSS) and Visual Analogue Scale (VAS) at the beginning and at the end of the two experimental sessions.
A sinusoidal AC was applied (current intensity: 0.6 mA; max current density=0.531 mA/cm2) by two electrodes, located on FT7 and FT8. Power spectra of the 28 EEG derivations were computed by a fast Fourier transform routine in 2 s epochs across the EEG bands.
Results show that 5Hz-tACS on fronto-temporal area induces an increase (10-15%) of EEG power in lower frequency bands (delta and theta) but fails to induce any effect on subjective sleepiness.
The specific topographic pattern of changes involving frontal increase in the delta band and occipital increase in the theta range seems to simulate the dynamics characterizing an early sleep onset. However, no causal relation can be traced on the basis of the current results between these rhythms and changes on sleepiness
The efficacy of transcranial current stimulation techniques to modulate resting-state EEG, to affect vigilance and to promote sleepiness
No full textTranscranial Current Stimulations (tCSs) are non-invasive brain stimulation techniques which modulate cortical excitability and spontaneous brain activity by the application of weak electric currents through the scalp, in a safe, economic, and well-tolerated manner. The direction of the cortical effects mainly depend on the polarity and the waveform of the applied current. The aim of the present work is to provide a broad overview of recent studies in which tCS has been applied to modulate sleepiness, sleep, and vigilance, evaluating the efficacy of different stimulation techniques and protocols. In recent years, there has been renewed interest in these stimulations and their ability to affect arousal and sleep dynamics. Furthermore, we critically review works that, by means of stimulating sleep/vigilance patterns, in the sense of enhancing or disrupting them, intended to ameliorate several clinical conditions. The examined literature shows the efficacy of tCSs in modulating sleep and arousal pattern, likely acting on the top-down pathway of sleep regulation. Finally, we discuss the potential application in clinical settings of this neuromodulatory technique as a therapeutic tool for pathological conditions characterized by alterations in sleep and arousal domains and for sleep disorders per se
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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