1,721,073 research outputs found
A purge and trap method for the analysis of volatile organic compounds in human oral fluid
No full textA dual mode breath sampler for the collection of the end-tidal and dead space fractions
Full text linkThis work presents a breath sampler prototype automatically collecting end-tidal (single and multiple breaths) or dead space air fractions (multiple breaths). This result is achieved by real time measurements of the CO2 partial pressure and airflow during the expiratory and inspiratory phases. Suitable algorithms, used to control a solenoid valve, guarantee that a Nalophan® bag is filled with the selected breath fraction even if the subject under test hyperventilates. The breath sampler has low pressure drop (< 0.5 kPa) and uses inert or disposable components to avoid bacteriological risk for the patients and contamination of the breath samples. A fully customisable software interface allows a real time control of the hardware and software status. The performances of the breath sampler were evaluated by comparing a) the CO2 partial pressure calculated during the sampling with the CO2 pressure measured off-line within the Nalophan® bag; b) the concentrations of four selected volatile organic compounds in dead space, end-tidal and mixed breath fractions.Results showed negligible deviations between calculated and off-line CO2 pressure values and the distributions of the selected compounds into dead space, end-tidal and mixed breath fractions were in agreement with their chemical-physical properties
Determination of total and unbound warfarin and warfarin alcohols in human plasma by high performance liquid chromatography with fluorescence detection
No full texttTwo analytical procedures are presented for the determination of the total content and unbound fractionof both warfarin and warfarin alcohols in human plasma. Chromatographic separation was carried outin isocratic conditions at 25◦C on a C-18 reversed-phase column with a mobile phase consisting of a 70%buffer phosphate 25 mM at pH = 7, 25% methanol and 5% acetonitrile at a flow rate of 1.2 mL/min. Fluores-cence detection was performed at 390 nm (excitation wavelength 310 nm). Neither method showed anydetectable interference or matrix effect. Inter-day recovery of the total warfarin and warfarin alcoholsat a concentration level of 1000 ng/mL was 89 ± 3% and 73 ± 3%, respectively, whereas for their unboundfraction (at a concentration level of 10 ng/mL) was 66 ± 8% and 90 ± 7%, respectively. The intra- and inter-day precision (assessed as relative standard deviation) was <10% for both methods. The limits of detectionwere 0.4 and 0.2 ng/mL for warfarin and warfarin alcohols, respectively. The methods were successfullyapplied to a pooled plasma sample obtained from 69 patients undergoing warfarin therapy
Effect of EDA-driven sympathetic responses on the central processing of faces cued by hedonic odors: a preliminary ERP study
Full text linkOlfactory stimuli are powerful cues capable of modulating behavioral and physiological responses to other stimuli, such as visual stimuli. In this study, we investigated the integration of autonomic-driven information into the central nervous system dynamics during a contextual presentation of neutral faces and hedonic odors. To this aim, we simultaneously acquired the electrodermal activity (EDA) and EEG signals from a group of 20 healthy volunteers. We applied a novel methodological approach to identify event-related potentials (ERPs) with and without a concomitant EDA-related sympathetic response. Then, we investigated the effect of both sympathetic responses and contextual odors on ERP components involved in the processing of faces. Preliminary results showed a significant increase of the N170 amplitude in the left parieto-temporal region when a sympathetic response was present, compared to ERPs associated with no sympathetic responses, irrespective of odors' valence. This may suggest that sympathetic responses identified from EDA have an effect on the early central processing of faces with background odors, possibly reflecting enhanced arousal triggered by salient features of the stimuli
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
Determinazione del warfarin in campioni di saliva e plasma raccolti da pazienti in terapia anticoagulante
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