130,488 research outputs found
Association Between Severe Vitamin D Deficiency, Lung Function and Asthma Control
No full textIntroduction: To examine the relationship between severe vitamin D deficiency, asthma control, and pulmonary function in Turkish adults with asthma. Methods: One hundred six asthmatic patients underwent pulmonary function tests skin prick test, peripheral blood eosinophil counts, IgE, body mass index and vitamin D levels were determined. Patients were divided into 2 subgroups according to vitamin D levels (vitamin D level < 10 ng/ml and vitamin D level >= 10 ng/ml). Asthma control tests were performed. Results: The mean age of subgroup I (vitamin D level < 10) was 37 +/- 10 and the mean age of subgroup II (vitamin D level >= 10 ng/ml) was 34 +/- 8. Sixty-six percent of patients had severe vitamin D deficiency (vitamin D level < 10 ng/m1). There was a significant trend towards lower absolute FEV1 (L) values in patients with lower vitamin D levels (P=.001). Asthma control test scores were significantly low in the severe deficiency group than the other group (P=.02). There were a greater number of patients with uncontrolled asthma (asthma control test scores < 20) in the severe vitamin D deficiency group (P=.040). Patients with severe vitamin D deficiency had a higher usage of inhaled corticosteroids than the group without severe vitamin D deficiency (P=.015). There was a significant trend towards lower absolute FEV1 (L) (P=.005, r =.272) values in patients with lower vitamin D levels. Vitamin D levels were inversely related with body mass index (P=.046). Conclusion: The incidence of severe vitamin D deficiency was high in adult Turkish asthmatics. In addition,lower vitamin D levels were associated with poor asthma control and decreased pulmonary function.(C) 2016 SEPAR. Published by Elsevier Espana, S.L.U. All rights reserved
Increased D-dimer is associated with disease progression and increased mortality in Turkish COVID-19 patients
No full textObjective: Coagulopathy is thought to play an important role in the development of severe COVID-19. High D-dimer levels have been reported in Chinese cohort studies. However, ethnicity has significant implications for thrombotic risk. Our aim in this study is to determine the effect of D-dimer measurements on disease prognosis and mortality in Turkish patients with COVID-19. Patients and Methods: The study was designed retrospectively. Patients over the age of 18 who were admitted to our hospital were included in the study. Results: The study included 226 patients. According to the World Health Organization staging, 75(33.2%) patients, according to the staging of Siddiqi et al., 67 (29.7%) patients progressed. In the ROC analysis performed to predict mortality, AUC value for D-dimer was found to be 82.25% (95%CI 74.8%-89.71%). When the cut-off value for D-dimer was accepted as ≥3.25mg/L, specificity was 94.15%, correctly classified rate 88.5%, positive likelihood ratio as (LR):5.69, negative LR:0.71. Conclusion: As a result, similar to the Chinese cohorts, elevated D-dimer measurements increase disease progression and mortality in Turkish patients with COVID-19. D-dimer levels of 3.25 mg/L and above, strongly determine the risk of increased mortality in the Turkish Caucasian ethnic group
Analytical calculations on content-based networks
No full textBu makalede içerik-temelli ağlar üzerinde, ağın topolojik özelliklerini belirlemek için, ortalama-alan yaklaşımlarıyla yapılan analitik hesapların güvenilirliği tartışılacaktır. İçerik-temelli ağları, “tanıma ve bağlanma” mekanizmalarının belirleyici olduğu kontrol çizgelerinin topolojik özelliklerini tasvir etmek için önermiştik. Birçok karmaşık ağ yapısının bu tür enformasyon paylaşımına dayalı bir prensibe göre inşa edildiğini söyleyebiliriz. Örneğin gen ifadesinin düzenlemesinde, anahtar/kilit olarak niteleyebileceğimiz elemanların özelleşmiş etkileşimleri söz konusudur. Bu sebeple modelimizin biyolojik çizgeler de dahil olmak üzere, birçok gerçek ağ yapısının tasviri için uygun olduğunu düşünüyoruz. İçerik-temelli ağımızda, ağın düğümlerini bir ya da birden fazla rastgele dizi ile eşleştirip, düğümler arasındaki etkileşimleri onlara atanan dizilerin birbirleri içinde tekrarlanma koşulu altında inşa ediyoruz. Böylece, bu dizilerin uzunlukları ve içerikleri, ortaya çıkacak olan çizgenin tüm topolojik özelliklerini belirlemektedir. Düğüm çiftleri arasındaki bağlanma olasılıklarının hesabında yapılan ortalama-alan yaklaşımlarının ise, dizilerin uzunluk dağılımlarına bağlı olarak, varılan sonuçlarda ağın gerçek özelliklerinden önemli farklılaşmalara yol açabileceği görülüyor. Bu yaklaşımlarda, dizilerin farklı enformasyon içerikleri ihmal edilmekte ve olasılıklar sadece dizilerin uzunlukları cinsinden elde edilmektedir. Halbuki her sonlu dizi için, dizinin içerdiği farklı sembol sayısı ek bir enformasyon içermektedir. Burada sergilemeye çalışacağımız, kabalaştırılmış ortalama-alan türünden yaklaşımların, belli ekstrem durumlarda, tasvir etmeyi amaçladıkları ağın özelliklerinden uzak sonuçlar verebileceğidir. Ancak gerçek biyolojik ağ yapılarının modellenmesinde karşımıza çıkan uzunluk dağılımlarında ortaya çıkan hatalar hiçbir zaman burada sergileyeceğimiz örneklerde olduğu kadar büyük olmamış, bilakis ortalama-alan yaklaşımı simülasyon sonuçlarına oldukça yakın sonuçlar vermiştir. Anahtar Kelimeler: Karmaşık ağ yapıları, içerik-temelli ağlar, ortalama-alan yaklaşımı.Content-based networks have been proposed (Balcan and Erzan, 2004; Mungan et al., 2005) to model the topological properties of complex networks built on the principle of information sharing, where the interactions between system components assume the simultaneous fulfillment of a series of constraints (Mezard et al., 2002). In content-based networks, the constraint-satisfaction problem is realized by means of a sequence-matching rule between sequences associated with the nodes of a network. In the case of transcriptional gene regulation, the transcription factors recognize special subsequences of DNA and bind them. This is one instance of constraint-satisfaction, which can be realized with a sequence-matching rule between two different classes of sequences (Balcan et al., 2006). Another example is the so called the RNA interference (Balcan and Erzan, 2004), where sequence-specific gene silencing occurs at the level of post-transcriptional gene regulation. In our content-based networks, n linear codes are associated with each node of the network. For n=2, one of the sequences associated with the node represents the key-sequence through which the node recognizes other nodes, whereas the second sequence represents the lock-sequence through which the same node is recognized. An interaction between a pair of nodes is established if the key-sequence associated with the first node is repeated as an uninterrupted subsequence in the lock-sequence associated with the second node. Thus, the length distributions of these sequences are the most important parameters determining the topological properties of the content-based networks. In this article we will discuss the validity of analytical calculations performed on the topological properties of content-based networks in the mean-field approximation (Balcan and Erzan, 2007), by means of two examples. In this mean field approach (Mungan et al., 2005) the pair-wise connectivity probabilities are only functions of the respective lengths of the sequences which must satisfy an inclusion requirement, and of the size r of the alphabet from which the symbols are drawn. This approximation ignores the correlations between the overlapping subsequences within a sequence. Moreover the fluctuations in the information content of finite sequences are neglected. In Balcan and Erzan (2007), the correlations between the edges co-incident on the same node were also ignored. In the first example, the key- sequences of unit length (thus, they consist of single letters) are searched in lock-sequences of an arbitrary fixed length. Via this simple example it is possible to show that the probability that lock-sequences will be recognized by a key-sequence depends not only on the length of the lock-sequence but also on the number of distinct subsequences embedded in it. At this point the coarse grained approximation neglecting the fluctuations in the information content of the finite lock sequences about their mean information content, misses the behavior of the in-degree distribution. This error is in fact identical to neglecting the correlations between edges incident upon a given node. In the second example, the lengths of the key sequences are fixed at an arbitrary value l, and the lock-sequences are chosen to be of length k=l+1, one character longer than the key-sequences. In this example, it is clear that the correlations between the two subsequences of length l cannot be neglected. It has already been shown (Guibas and Odlyzko, 1981; Mungan et al., 2005; Mungan, 2007; Bilge et al., 2004) that the connection probability of a key-sequence depends on the ?shift-match number? which measures the auto-correlations within a sequence, in other words, the degree to which successive subsequences are correlated with each other. We show here by an explicit and rather transparent calculation that, neglecting this correlation yields out- and in-degree distributions that are totally in error. The mean-field approximations used in the calculation of the topological properties of the double-string model (Balcan and Erzan, 2007) yield results that are in good agreement with the simulations, since i) the lengths k of the lock sequences far exceed r, ii) the number of distinct substrings contained in any given lock string is large ( k-l >> rl ) and iii) the fine structure of the topological properties are determined by the fact that there is a disribution of lock- and key-string lengths. Keywords: Complex networks, content-based networks, mean-field approach
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
"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.
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
The R&D Tax Incentives
No full textThis article sets out some background information and reflections of the author on the R&D tax incentive schemes included in the Common Corporate Tax Base (CCTB) Proposal. In particular the author analyzes the stimulus to private R&D through ad hoc tax incentives included in the CCTB Proposal and dives into the actual provisions included in the Proposal highlighting the most relevant issues connected with their design and interpretation. Moreover, the author explores the interaction between the CCTB Proposal and the granting by Member States of domestic R&D tax incentives
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