1,720,985 research outputs found
METODO PER LA VALUTAZIONE, LA SCELTA E L'OTTIMIZZAZIONE DELLE TRASFORMATE TEMPO-FREQUENZA BILINEARI PER LO STUDIO DEI RESPONSI OTTICI ULTRAVELOCI
No full textMETODO PER LA VALUTAZIONE, LA SCELTA E L'OTTIMIZZAZIONE DELLE TRASFORMATE TEMPO-FREQUENZA BILINEARI PER LO STUDIO DEI RESPONSI OTTICI ULTRAVELOC
Innovative Strategies in Coherent Multidimensional Electronic Spectroscopy
Full text linkRecent experimental evidences of long-lived quantum electronic coherences in photosynthetic systems have focused the attention on the possible role of quantum phenomena in enhancing biologically relevant functions and the performance of man-made energy devices.
Two-dimensional electronic spectroscopy (2DES) provided several compelling evidences that sparked the discussion, but we are far from achieving clear statements.
The technique is little more than a decade old and active research is progressing on setup development and data-analysis procedures.
A high-performance setup has been built and advanced calibration procedure and acquisition schemes have been designed, in order to tackle the challenges of current instrumental implementations.
Time-frequency decomposition techniques, borrowed from the signal-processing field, have been adapted and applied to the analysis of 2DES coherent oscillating signals. Moreover, a global analysis method based on the variable projection algorithm has been developed for robust and quantitative analysis of coherence signatures. The dynamics of the relevant beating components is resolved with unmatched clarity, supplying a valuable help in their interpretation.
An oligomeric porphyrin based model system has been investigated with the developed tools. Vibrational coherences with drastically different behaviors have been analyzed bringing out the role of the disorder in modulating the coherent dynamics
Time-frequency methods for coherent spectroscopy
Full text linkTime-frequency decomposition techniques, borrowed from the signal-processing field, have been adapted and applied to the analysis of 2D oscillating signals. While the Fourier-analysis techniques available so far are able to interpret the information content of the oscillating signal only in terms of its frequency components, the time-frequency transforms (TFT) proposed in this work can instead provide simultaneously frequency and time resolution, unveiling the dynamics of the relevant beating components, and supplying a valuable help in their interpretation. In order to fully exploit the potentiality of this method, several TFTs have been tested in the analysis of sample 2D data. Possible artifacts and sources of misinterpretation have been identified and discussed
Optimization and selection of time-frequency transforms for wave-packet analysis in ultrafast spectroscopy
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Global analysis of coherence and population dynamics in 2D electronic spectroscopy
Full text link2D electronic spectroscopy is a widely exploited tool to study excited state dynamics. A high density of information is enclosed in 2D spectra. A crucial challenge is to objectively disentangle all the features of the third order optical signal. We propose a global analysis method based on the variable projection algorithm, which is able to reproduce simultaneously coherence and population dynamics of rephasing and non-rephasing contributions. Test measures at room temperature on a standard dye are used to validate the procedure and to discuss the advantages of the proposed methodology with respect to the currently employed analysis procedures
Edge level of aligners and periodontal health: a clinical perspective study in young patients
Full text linkIntroduction: Although the superiority of clear aligners over multi-bracket appliances in keeping gingiva healthy has been suggested, the possible benefits of one aligner design over another have not yet been investigated, especially with regard to the vestibular edge. Objective: The aim of this study was to measure several periodontal indexes in adolescents undergoing orthodontic treatment with aligners, comparing two different types of rim. Methods: The study involved 43 patients aged between 14 and 18 years. The periodontal health was assessed using plaque index (PI), gingival index (GI), and gingival bleeding index (GBI), at the start of the treatment with aligners (T0), with a vestibular rim (VR) reaching up to 3 mm beyond the gingival margin. Three months later (T1), aligners were set to obtain a juxtagingival rim (JR) on the second quadrant and VR on the first quadrant. The periodontal indexes were measured again, both at T1 and then three months later (T2). Results: Intra-quadrant comparisons revealed a statistically significant worsening of the periodontal indexes only for the second quadrant (p<0.05), at T1 (GI), and especially at T2 (PI, GI, GBI), while no statistically significant changes were found for the first quadrant. Conclusions: More severe mechanical irritation, especially during insertion and removal of the aligner, can explain the worsening inflammatory indexes with the JR. In addition, the pressure exerted by the JR on the gingival sulcus seemed to facilitate plaque deposition, whereas the VR had a protective effect, reducing the risk of mechanical trauma
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
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