11,857,494 research outputs found
Activation of the coagulation system in coronary artery bypass grafting operation: comparison between on-pump and off-pump techniques
No full textObjective: Comparing peri-operative activation of the coagulation and fibrinolytic systems and platelet function in patients receiving CABG operation by means of on pump or off pump techniques. Methods: 32 consecutive patients requiring elective CABG were enrolled in the study and assigned in a randomized fashion to: on pump group or off pump group. Heparin was given at the same dose (300 U/kg) and antifibrinolytic drugs were not administered. Activation of the coagulation system was evaluated by means of Prothrombin Fragment 1.2 (PF-1.2) and Tissue Factor (TF) measurements; fibrinolysis was evaluated measuring Tissutal Plasminogen Activator (TPA), Plasminogen Activator Inhibitor-1 (PAI-1) and D-Dimer (D-D) formation. Platelets function was evaluated by means of the Platelet Function Analyzer (PFA-100®). Blood samples were collected at T0 (during induction of anesthesia), T1 (45 min after heparin administration), T2 (15 min after protamine administration), T3 (3 h after the end of the operation), T4 (postoperative day (POD) 1), T5 (POD4), and T6 (POD6). Results were corrected for haemodilution. Results: No statically significative differences were found in pre, peri and post-operative clinical characteristics between the two groups, except for heparinization time (on pump group 159.6±40.4 min; off pump group 121.6±35.7; P<0.05) and hemoglobin value at POD6 (on pump group 9.3±2.34 g/dl; off pump group 10.9±1.35 g/dl; P<0.05). The coagulation system was activated during cardiopulmonary bypass (CPB) and highest levels of PF-1.2 were measured at T1, T2 and T3 (P<0.05 compared with off pump group); a trend towards increased levels of PF-1.2 was observed in both groups at T4,T5 and T6. TF production was similar in the two groups and no statistically significative differences were found at any sample time. The fibrinolytic system was more activated in the on pump group as demonstrated by TPA levels at T1 (P<0.05), PAI-1 levels at T2 (P<0.05) and D-D levels at T2 and T3 (P<0.05). Not surprisingly, CPB induces platelet dysfunction; PFA-100 bleeding times were significantly elevated in on pump group at T1, T2 and T3 (P<0.05). PFA-100 bleeding postoperative times were not prolonged in both groups despite aspirin administration. Conclusions: Off-pump patients produce less activation of the coagulation system and do not activate fibrinolysis during the operation; their platelet function is preserved during and after the operation. This may explain the reported reduced rate of postoperative bleeding associated with this technique. The absence of fibrinolysis together with functioning platelets and increased thrombin formation postoperatively suggest that off pump patients may experience a pro-thrombotic state
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Document: Charles D. Drake
No full textExtract from speech of Charles D. Drake, chairman of Committee of Seventy, delivered at St. Louis, October 17, 186
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Variations on the Author
No full text“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
Preeclampsia risk, maternal 25-hydroxyvitamin D concentration, and variation in vitamin D metabolism pathway genes
No full textOBJECTIVE: Our objectives were to study the relationships between 25-hydroxyvitamin D (25(OH)D) and preeclampsia risk, maternal genetic variation in 3 vitamin D metabolism genes (GC, CYP27B1, VDR) and preeclampsia risk, and variation in the same genes and 25(OH)D. METHODS: We used two racially diverse pregnancy cohorts (EVITA and Collaborative Perinatal Project (CPP)) to achieve these objectives. We estimated the association between log-transformed 25(OH)D and preeclampsia risk in EVITA by using log-binomial regression with restricted cubic splines. In EVITA and CPP, we used multivariable logistic and linear regression models to estimate the associations between allelic variation and preeclampsia risk, and genotype and log-transformed 25(OH)D, respectively. Meta-analyses were conducted to calculate estimates of association between and within cohorts. RESULTS: Dose-response associations of 25(OH)D were observed for both severe and mild preeclampsia. Trends of associations were observed in genetic variation and preeclampsia risk. Compared with major allele carriers, Black mothers in EVITA who carried the minor allele for rs11732451 GC single nucleotide polymorphism (SNP) and 2 VDR SNPs (rs4340112, rs10459217) had increased odds of preeclampsia, while the odds were lowered for those who carried the minor allele for 1 GC SNP (rs1099028) and 2 VDR SNPs(rs757344, rs12721364). In the meta-analysis, two VDR SNPs (rs886441 and rs2853561) had trends of decreased odds of preeclampsia for all Black mothers. For the 25(OH)D analysis, statistically significant associations were observed. Compared with those with major allele genotypes, mothers with minor allele genotypes of rs1844885 (GC) and rs11168275 (VDR) had increased 25(OH)D and of rs11732451 (GC) had lowered 25(OH)D. In the meta-analysis on all Black mothers, rs1844885 (GC) was associated with increased 25(OH)D while there was a trend of decreased 25(OH)D for rs10877016 (CYP27B1). CONCLUSIONS: Low 25(OH)D may be enough to reduce risk of preeclampsia. If our findings are confirmed in a replication study, genetic variation may be an independent risk factor for maternal 25(OH)D, making the findings of this research relevant to public health
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
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