1,720,967 research outputs found
Deficits in memory consolidation induced by bacterial endotoxin in mice coincide with elevated cytokine and chemokine levels, but diminished expression of brain-derived neurotrophic factor
No full textLipopolysaccharide induces the synthesis and release of pro-inflammatory cytokines and chemokines in the periphery and the central nervous system. It has previously been reported that peripheral LPS administration in rats disrupts contextual fear memory consolidation processes, potentially due to elevated cytokine expression. We used a similar, but predominantly olfactory based, paradigm to characterize the behavioral effects of LPS administration in mice. As hypothesized, LPS administered immediately or 2 h, but not 12 h, post-training impaired memory consolidation processes that support the storage of the conditioned contextual fear memory. Consistent with the behavioral findings, 4 h post-injection, cytokine and chemokine levels were heightened in LPS-treated animals, with a simultaneous decrease in brain-derived neurotrophic factor (BDNF) mRNA. Collectively, these data reinforce and extend prior work, and suggest that contextual fear conditioning, with the addition of olfactory cues, offers a promising way to study cognitive deficits induced by peripheral immune activation in mice
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
Decomposing Differences in Coronavirus disease 2019-related Case-Fatality Rates across Seventeen Nations
Full text linkAs of 1 November 2020, estimated case-fatality rates associated with coronavirus disease 2019 are not uniformly patterned across the world and differ substantially in magnitude. Given the global spatial heterogeneity in case-fatality rates, we applied the Blinder-Oaxaca regression decomposition technique to identify how putative sociodemographic, structural, and environmental sources influence variation in case-fatality rates. We show that compositional and associational differences in country-level risk factors explain a substantial proportion of the coronavirus disease 2019-related case-fatality rate gap across nations. Asian countries fair better vis-à-vis case-fatality rate differences mainly due to variation in returns to sociodemographic, structural, and environmental sources among their citizens, relative to those who share similar attributes but live in Europe or North America. The variation in case-fatality rate is driven by Asian populations being better able to buffer the harmful effects of the very risk factors purported to exacerbate the risk of coronavirus disease 2019-related death. The dire circumstances in which we find ourselves demand better understanding of how preexisting conditions across countries contribute to observed disparities in case-fatality rates
Updated Prevalence Estimates of Obesity Among Adults in the United States, 2005–2018
No full textIntroduction
Body mass index is an imperfect measure of excess adiposity but is ingrained in both research and clinical practice to define and diagnose adult obesity. The addition of waist circumference measure is recommended to fully capture obesity-related health risks at a population level. The latest reframing of obesity by the Lancet Commission relies on body mass index and waist circumference, as well as organ dysfunction and functional limitations, to differentiate between preclinical and clinical obesity. Methods
Using data from the National Health and Nutrition Examination Survey (2005–2018), we adhere to the proposed redefinition to examine obesity trends in the adult U.S. population. Results
In line with previously published estimates of obesity defined solely by body mass index, we show that the prevalence of both preclinical and clinical obesity increased between 2005 and 2018. However, the prevalence of preclinical obesity calculated by BMI plus WC is lower than the estimates derived from using BMI or WC as the sole metrics. Conclusion
Using the Commission’s added measures yields refined population estimates for two categories—preclinical and clinical obesity. These updated estimates separate preclinical cases—at elevated risk and eligible for prevention—from those meeting clinical-obesity criteria, who require intervention
County-Level Factors That Influenced the Trajectory of COVID-19 Incidence in the New York City Area
Full text linkMore than a century of research has shown that sociodemographic conditions affect infectious disease transmission. In the late spring and early summer of 2020, reports of the effects of sociodemographic variables on the spread of COVID- 19 were used in the media with minimal scientific proof attached. With new cases of COVID-19 surging in the United States at that time, it became essential to better understand how the spread of COVID-19 was varying across all segments of the population. We used hierarchical exponential growth curve modeling techniques to examine whether community socioeconomic characteristics uniquely influence the incidence of reported COVID-19 cases in the urban built environment. We show that as of July 19, 2020, confirmed coronavirus infections in New York City and surrounding areas— one of the early epicenters of the COVID-19 pandemic in the United States—were concentrated along demographic and socioeconomic lines. Furthermore, our data provides evidence that after the onset of the pandemic, timely enactment of physical distancing measures such as school closures was essential to limiting the extent of the coronavirus spread in the population. We conclude that in a pandemic, public health authorities must impose physical distancing measures early on as well as consider community-level factors that associate with a greater risk of viral transmission
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