130,865 research outputs found
Application of the Solid-Phase Julia–Lythgoe Olefination in Vitamin D Side-Chain Construction
No full textexample of the Julia–Lythgoe attachment of the vitamin D side chain to a solid-phase linked Inhoffen–Lythgoe diol derived CD-ring fragment is reported
Application of the Solid-Phase Julia–Lythgoe Olefination in Vitamin D Side-Chain Construction
No full textAn example of the Julia–Lythgoe attachment of the vitamin D side chain to a solid-phase linked Inhoffen–Lythgoe diol derived CD-ring fragment is reported
Is HIV short-sighted? Insights from a multistrain nested model
No full textAn important component of pathogen evolution at the population level is evolution within hosts. Unless evolution within hosts is very slow compared to the duration of infection, the composition of pathogen genotypes within a host is likely to change during the course of an infection, thus altering the composition of genotypes available for transmission as infection progresses. We develop a nested modeling approach that allows us to follow the evolution of pathogens at the epidemiological level by explicitly considering within-host evolutionary dynamics of multiple competing strains and the timing of transmission. We use the framework to investigate the impact of short-sighted within-host evolution on the evolution of virulence of human immunodeficiency virus (HIV), and find that the topology of the within-host adaptive landscape determines how virulence evolves at the epidemiological level. If viral reproduction rates increase significantly during the course of infection, the viral population will evolve a high level of virulence even though this will reduce the transmission potential of the virus. However, if reproduction rates increase more modestly, as data suggest, our model predicts that HIV virulence will be only marginally higher than the level that maximizes the transmission potential of the virus
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
sj-docx-1-jop-10.1177_02698811221099643 – Supplemental material for The association between N-methyl-d-aspartate receptor availability and glutamate levels: A multi-modal PET-MR brain imaging study in first-episode psychosis and healthy controls
No full textSupplemental material, sj-docx-1-jop-10.1177_02698811221099643 for The association between N-methyl-d-aspartate receptor availability and glutamate levels: A multi-modal PET-MR brain imaging study in first-episode psychosis and healthy controls by Katherine Beck, Atheeshaan Arumuham, Stefan Brugger, Robert A McCutcheon, Mattia Veronese, Barbara Santangelo, Colm J McGinnity, Joel Dunn, Stephen Kaar, Nisha Singh, Toby Pillinger, Faith Borgan, Teresa Sementa, Radhouene Neji, Sameer Jauhar, Franklin Aigbirhio, Istvan Boros, Federico Turkheimer, Alexander Hammers, David Lythgoe, James Stone and Oliver D Howes in Journal of Psychopharmacology</p
"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.
Cardiopulmonary exercise variables are associated with postoperative morbidity after major colonic surgery: a prospective blinded observational study
No full textBACKGROUND: Postoperative complications are associated with reduced fitness. Cardiopulmonary exercise testing (CPET) has been used in risk stratification. We investigated the relationship between preoperative CPET and in-hospital morbidity in major colonic surgery.METHODS: We prospectively studied 198 patients undergoing major colonic surgery (excluding neoadjuvant cancer therapy), performing preoperative CPET (reported blind to clinical state), and recording morbidity (assessed blind to CPET), postoperative outcome, and length of stay.RESULTS: Of 198 patients, 62 were excluded: 11 had emergency surgery, 25 had no surgery, 23 had incomplete data, and three were unable to perform CPET. One hundred and thirty-six (89 males, 47 females) were available for analysis. The median age was 71 [inter-quartile range (IQR) 62-77] yr. Sixty-five patients (48%) had a complication at day 5 after operation. Measurements significantly lower in patients with complications than those without were O2 uptake () at estimated lactate threshold () [median 9.9 (IQR 8.3-12.7) vs 11.2 (9.5-14.2) ml kg-1 min-1, P<0.01], at peak [15.2 (12.6-18.1) vs 17.2 (13.7-22.5) ml kg-1 min-1, P=0.01], and ventilatory equivalent for CO2 (/) at [31.3 (28.0-34.8) vs 33.9 (30.0-39.1), P<0.01]. A final multivariable logistic regression model contained at {one-point change odds ratio (OR) 0.77 [95% confidence interval (CI) 0.66-0.89], P<0.0005; two-point change OR 0.61 (0.46-0.81) and gender [OR 4.42 (1.78-9.88), P=0.001]}, and was reasonably able to discriminate those with and without complications (AUC 0.71, CI 0.62-0.80, 68% sensitivity, 65% specificity).CONCLUSIONS: CPET variables are associated with postoperative morbidity. A multivariable model with at and gender discriminates those with complications after colonic surgery.<br/
Comparison of oxygen uptake during arm or leg cardiopulmonary exercise testing in vascular surgery patients and control subjects
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