1,720,957 research outputs found
Advancements in the recycling of organocatalysts: From classical to alternative approaches
No full textHomogenous catalysis is a fundamental tool in chemistry and holds a key role to build a sustainable future. This review covers a range of different approaches that have been devised, in the past couple of years, to recycle and reuse the homogenous catalysts, to improve the environmental and economic footprint. The organic catalysts have been supported on organic, inorganic and magnetic matrixes, to allow easy separation and recycle. Additional ingenious solutions have been designed; researchers exploited supramolecular interactions, change of phase, pH, temperature or membranes to address some of the issues that arise with heterogenous catalysis and to facilitate the recovery process
Modulation of heartbeat-evoked oscillations and connectivity by respiration and focus of attention
No full textHeartbeat evoked potentials (HEPs) are EEG voltage fluctuations that reflect the cortical processing of cardiac signals. In the time-frequency domain, recent studies have observed significant heartbeat evoked oscillations (HEOs) and connectivity at rest and during a task involving bodily self-consciousness.1,2 In the time domain, we recently found higher HEP positivity during exhalation compared to inhalation in a task focused on attending to cardiac sensations, likely reflecting heightened cardiac interoceptive attention.3 Here, we aimed to investigate whether HEOs and functional connectivity can be modulated by cardiac interoceptive attention and the respiratory phase. We assessed HEOs (heartbeat-related power and inter-trial coherence) and network connectivity across the respiratory cycle in 28 healthy volunteers at rest, during a cardiac interoceptive task (Heartbeat Counting Task), and during its exteroceptive control condition (Cardiac-Tone Counting Task). We found a significant increase in power, inter-trial coherence, and synchronization between cortical regions evoked by the heartbeat in theta and alpha bands during exhalation compared to inhalation, specifically during the cardiac interoceptive task. These data corroborate previous results highlighting the capability of respiration to modulate cardiac interoception, offering significant insights for clinical interventions to improve self-regulation. These results also suggest that changes in HEOs and functional connectivity in the alpha band may be related to the selective inhibition or disengagement from competing or distracting exteroceptive stimuli that are outside the focus of attention, particularly during exhalation
Attention to cardiac sensations enhances the heartbeat-evoked potential during exhalation
Full text linkRespiration and cardiac activity intricately interact through complex physiological mechanisms. The heartbeat-evoked potential (HEP) is an EEG fluctuation reflecting the cortical processing of cardiac signals. We recently found higher HEP amplitude during exhalation than inhalation during a task involving attention to cardiac sensations. This may have been due to reduced cardiac perception during inhalation and heightened perception during exhalation through attentional mechanisms. To investigate relationships between HEP, attention, and respiration, we introduced an experimental setup that included tasks related to cardiac and respiratory interoceptive and exteroceptive attention. Results revealed HEP amplitude increases during the interoceptive tasks over fronto-central electrodes. When respiratory phases were taken into account, HEP increases were primarily driven by heartbeats recorded during exhalation, specifically during the cardiac interoceptive task, while inhalation had minimal impact. These findings emphasize the role of respiration in cardiac interoceptive attention and could have implications for respiratory interventions to fine-tune cardiac interoception
The influence of respiratory phases on interoceptive and exteroceptive perception
No full textAbstract: Recent literature about interoception suggests that interoceptive accuracy and its related neural correlates (e.g., the heartbeat evoked potential) are enhanced during exhalation, while inhalation optimizes the processing of exteroceptive information. We herein investigated the relationship between respiratory activity and the perception of anticipated interoceptive and exteroceptive stimuli, which were signaled by a visual cue (i.e., a white cross turning red). We tested whether and to what extent the presence of a cue would prompt participants to actively modulate their breathing to enhance task performance. Forty-one participants engaged in both an interoceptive and an exteroceptive task, while their respiratory and cardiac activity were recorded. The interoceptive task was the Heartbeat Discrimination Task, where participants were instructed to judge the simultaneity of a sequence of three tones with their heartbeat. In the exteroceptive task, participants were asked to detect a near-threshold tactile stimulation over their left index finger. This paradigm allowed us to determine whether participants actively align inhalation and exhalation to the expected (i.e., cued) exteroceptive and interoceptive trial onset, respectively. By applying Signal Detection Theory, we assessed task performance and discrimination indices. We observed a significantly better performance during exhalation compared to inhalation in both tasks, indicating a modulation of perceptual processing by the respiratory cycle. Moreover, circular statistics revealed strong phaselocking of respiration to the expected (i.e., cued) stimuli onset during both the interoceptive and exteroceptive tasks. Generally, participants showed a tendency to align inhalation with trial onset. Additional analysis, including measures like inter-trial coherence, is required to better understand the role of respiration as an active sensing mechanism, optimizing the perceptual processing of both the interoceptive and exteroceptive domains, and its contribution to the understanding of how bodily rhythms shape and optimize human perception
Asymmetric Organocatalysis Accelerated via Self-Assembled Minimal Structures
Full text linkSelf-assembling minimalistic peptides embedded with an organocatalytic moiety were designed. By controlling the formation of fibrils via external intervention, it was shown that the activation is accelerated when the organocatalyst is in its supramolecular state. The effect of the accelerated catalysis was demonstrated in a Michael benchmark reaction
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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