1,720,960 research outputs found
Force field evolution during human blood platelet activation
No full textContraction at the cellular level is vital for living organisms. The most prominent type of contractile cells are heart muscle cells, a less-well-known example is blood platelets. Blood platelets activate and interlink at injured blood vessel sites, finally contracting to form a compact blood clot. They are ideal model cells to study the mechanisms of cellular contraction, as they are simple, having no nucleus, and their activation can be triggered and synchronized by the addition of thrombin. We have studied contraction using human blood platelets, employing traction force microscopy, a single-cell technique that enables time-resolved measurements of cellular forces on soft substrates with elasticities in the physiological range (similar to 4 kPa). We found that platelet contraction reaches a steady state after 25 min with total forces of similar to 34 nN. These forces are considerably larger than what was previously reported for platelets in aggregates, demonstrating the importance of a single-cell approach for studies of platelet contraction. Compared with other contractile cells, we find that platelets are unique, because force fields are nearly isotropic, with forces pointing toward the center of the cell area
Automated, semi-automated, and manual analyses of anti-cardiolipin and anti-beta 2-glycoprotein I antibodies in women with a history of miscarriage
No full textIntroduction Anti-cardiolipin and 2-glycoprotein I antibodies represent important diagnostic parameters in routine hematology. In this study, five different automated, semi-automated, and manual immunoassays detecting IgG/IgM anti-cardiolipin and anti-2-glycoprotein I antibodies were tested. Methods A total of 162 samples from women with a history of miscarriage were recruited from 110 different G&O outpatient centers in Germany. Results For both anti-cardiolipin and anti-2-glycoprotein I antibodies, considerable differences in the percentage of positive results were seen between all five methods, and itemization of all positive test results revealed a poor accordance. These findings were confirmed by Cohen's kappa coefficients. Conclusion Our study revealed a moderate to poor accordance between five different test systems for anti-cardiolipin and anti-2-glycoprotein I antibodies. Such deviations may result in clinical misinterpretation of data and may lead to wrong therapeutic consequences. Therefore, further standardization of all tests for anti-phospholipid antibodies should be achieved
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
Anticoagulation in large-volume leukapheresis: comparison between citrate- versus heparin-based anticoagulation on safety and CD34 + cell collection efficiency
No full textBackground aims. Little is known of the effect of anticoagulation on peripheral blood progenitor cell (PBPC) harvest during large-volume leukapheresis (LVL). Because of the interaction of heparin with stromal cell-derived factor (SDF)-1 alpha, it has been proposed that a heparin-based anticoagulation may result in an increased PBPC collection efficiency compared with standard citrate-based anticoagulation. Methods. We conducted a prospective randomized trial to address the effect of both anticoagulation regimes on safety, subjective comfort and CD34(+) collection efficiency in 90 adult patients undergoing standardized LVL. Anticoagulation consisted of either citrate (group C) or a combination of heparin and low-dose citrate (group H). Results. The overall incidence of adverse reactions (AR) during LVL was 17%. AR consisted only of citrate-related AR; no bleeding complications were observed. Determination of parameters of the acid-base balance revealed a higher frequency of metabolic alkalosis in group C. Analysis of serum SDF-1 alpha revealed no differences in SDF-1 alpha plasma levels. There were no differences in the CD34 cell collection efficiency, resulting in the harvest of equal CD34(+) cell yields independent of the anticoagulation used. Conclusions. Our data show no clinical relevant effect of a heparin containing anticoagulation in terms of an increased overall CD34(+) cell collection during LVL,, although this regime shows some benefits in terms of the incidence and subjective tolerance towards AR. Based on our results the decision between a citrate- and heparin-substituted anticoagulation for LVL should be driven by patient-related factors, and should concern potential contraindications of both methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
