1,720,993 research outputs found
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
Secretion of soluble VEGF receptor 2 by microvascular endothelial cells derived by human benign prostatic hyperplasia
No full textVascular endothelial growth factor (VEGF) is one of the most potent mitogenic factors stimulating both prostate endothelial and prostate epithelial cells. Recently, some studies reported on the endothelial secretion of a soluble VEGF receptor 2 (sVEGFR-2) that modifies the free VEGF concentration by binding VEGF. For the first time in this study, we report on the secretion and the regulation of the secretion of sVEGFR-2 by microvascular endothelial cells derived from the tissue of human benign prostatic hyperplasia (HPEC). HPEC were isolated and cultured from fresh prostate tissue. The prostate epithelial cell line BPH-1 was cultured with the supernatant of the HPEC cell culture (fractioned by fast protein liquid chromatography) and the VEGF concentration was subsequently measured. HPEC were incubated with VEGF or tumor necrosis factor alpha (TNF-alpha). Afterwards, the concentration of sVEGFR-2 in the supernatant of unstimulated and stimulated HPEC was measured by ELISA. HPEC showed a typical endothelial morphology. Under cell culture conditions sVEGFR-2 binds VEGF: The measured VEGF concentration in the supernatant of BPH-1 cells was reduced when the fractions of HPEC conditioned medium with the highest sVEGFR-2 concentration were incubated with the BPH-1 cells. The sVEGFR-2 secretion of HPEC was stimulated by VEGF and TNF-alpha. For the first time we report on the secretion of sVEGFR-2 by microvascular endothelial cells of prostate origin. The secretion of sVEGFR-2 by HPEC was stimulated by VEGF and TNF-alpha. Our data suggest that sVEGFR-2 secreted by prostate endothelial cells could modify the effect of VEGF on prostate endothelial and prostate epithelial cells
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
Pathogenese des Keratokonus – inflammatorische Komponente durch metabolische Veränderungen?
Full text linkDer Keratokonus (KC) ist eine progressive Erkrankung der Hornhaut. Beim Keratokonus wird die Hornhaut dünner und wölbt sich konisch nach vorne. Die Erkrankung tritt in der Regel im Teenageralter auf. Etwa 1 von 2000 aus der Bevölkerung sind in Europa von der Erkrankung betroffen. Bei einem Teil der Patienten verlangsamt sich die Erkrankung oder die Progression stoppt, bei einem Teil schreitet die Progression immer weiter. Die Behandlung erfolgt zunächst mit harten Kontaktlinsen, um die nachlassende Sehschärfe auszugleichen. Für einige Patienten kommen das Riboflavin-Crosslinking oder die Implantation intrakornealer Ringsegmente als Behandlungsmethode in Frage, um die Progression der Erkrankung zu stoppen. Für einen Teil der Patienten bleibt nur noch die Hornhauttransplantation, um die Sehschärfe zu verbessern.
In der ersten Arbeit wurden Harnstoff, Harnsäure, Prolaktin und fT4 im Kammerwasser von Keratokonuspatienten untersucht. Es konnte gezeigt werden, dass die Harnstoff und Prolaktin Konzentrationen im Kammerwasser von KC-Patienten erniedrigt sind, während fT4 erhöht ist. Da der Harnstoffzyklus bei der Biosynthese von Aminosäuren im Sinne der Kollagensynthese eine entscheidende Rolle spielt, wurde dieser Parameter als Ausgangspunkt für weitere Studien angesehen.
In der zweiten Studie wurde in Zellkulturversuchen gezeigt, dass die Harnstoff Konzentration auch in den Keratozyten von KC-Patienten reduziert ist. Da Harnstoff ein Nebenprodukt bei der Synthese von Prolin und Hydroxyprolin ist, haben wir den Harnstoffzyklus in den Keratozyten genauer untersucht. Die Ergebnisse dieser Arbeit lieferten weitere Hinweise auf eine veränderte Regulation der Kollagensynthese in KC-Keratozyten. Die Studie ergab, dass die Keratokonus Keratozyten eine erniedrigte Arginase Aktivität und eine erniedrigte Hydroxyprolin Konzentration im Vergleich zu den gesunden Kontrollzellen aufweisen.
Die Ergebnisse der dritten Arbeit unterstützen die These einiger Forschungsgruppen, dass die Krankheit mit entzündlichen Prozessen einhergeht. Ein Schlüssel-Gen bei entzündlichen Prozessen ist der Nuklear Faktor kappa B (NF-κB). Als Transkriptionsfaktor aktiviert NF-κB unter anderem das bei entzündlichen Prozessen mitwirkende Enzym Nitric Oxide Synthase (NOS). Die Ergebnisse dieser Arbeit zeigten eine erhöhte NF-κB mRNA und Protein Expression, sowie auch eine erhöhte Stickoxidproduktion und induzierte NOS mRNA Expression in Keratokonus Keratozyten.
Weitere darauf aufbauende Untersuchungen sind notwendig, um mehr Einblick in die Erkrankung und damit auch die Möglichkeit neuer Behandlungsmethoden für die Patienten durch weitere Erkenntnisse hinsichtlich der Pathogenese zu gewinnen. Pathogenesis of Keratoconus – Inflammatory components through metabolic changes?
Keratoconus (KC) is a progressive corneal disease, which is characterized by corneal thinning and conical shape. It usually appears in teenagers and about 1 of 2000 persons is affected in Europe. In some of the patients progression is getting slower with age and then it stops, in some others it accelerates. The stage-related treatment starts with rigid gas permeable contact lenses to compensate corneal irregularities and to improve vision. In case of progression, riboflavin crosslinking or implantation of intracorneal ring segments may be used to stabilize the cornea. In some of the patients, corneal transplantation is performed in order to improve visual acuity.
In the first paper urea, uric acid, prolactin and fT4 concentration were examined in aqueous humor of keratoconus patients. It could be shown that urea and prolactin concentrations are decreased and fT4 concentration is increased in aqueous humor of keratoconus patients. Since the urea cycle plays a decisive role in the biosynthesis of non-essential proteinogenic amino acids in terms of collagen synthesis, this parameter was considered as a crucial starting point for further studies.
In the second study, a reduced urea concentration could be verified in keratoconus keratocyte cultures. Since urea is a by-product in the synthesis of proline and hydroxyproline, we examined the urea cycle in keratocytes more closely. The results of this work provided further evidence for altered regulation of collagen synthesis in KC-keratocytes. Here, a decreased arginase activity and hydroxyproline concentration could be shown in keratoconus keratocytes, compared to normal controls.
The results of the third study supported the hypothesis of some research groups, that keratoconus is associated with inflammatory processes. A key gene in inflammatory processes is the nuclear factor kappa B (NF-κB). As a transcription factor, NF-κB activates the enzyme Nitric Oxide Synthase (NOS), which is involved in inflammatory processes. The results of this work showed an increased NF-κB mRNA and protein expression, as well as increased nitric oxide production and induced NOS mRNA expression in keratoconus keratocytes.
Further investigations based on these results are necessary in order to gain more insight into the pathogenesis of keratoconus and thus, to new treatment modalities for the patients.
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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