1,721,244 research outputs found
Comparison between effects of Ringer′s and Ringer′s lactate irrigating solutions on corneal endothelium during phacoemulsfication
No full textPurpose
The aim of this study was to compare the effect of phacoemulsification on the corneal endothelium using Ringer′s and Ringer′s lactate as the intraocular irrigating solution.
Setting
Mansoura Ophthalmic Centre, Faculty of Medicine, Mansoura University, Egypt.
Design
Prospective randomized comparative study.
Materials and methods
A total of 102 eyes of 102 patients with senile cataract were randomized to have phacoemulsification with foldable intraocular lens implantation performed using Ringer′s (group 1) or Ringer′s lactate (group 2) as the intraocular irrigating solution. Specular microscopy was done preoperatively, 1 week and 3 months postoperatively to evaluate endothelial cell density (ECD), coefficient of variation (CV), and central corneal thickness. Data were analyzed using the t-test, the Mann-Whitney U-test, and the Pearson correlation coefficient.
Results
Mean ECD was 2532 cells/mm 2 preoperatively, 2345 cells/mm 2 1 week, and 2284 cells/mm 2 3 months postoperatively in group 1, and 2526, 2374, and 2322 cells/mm 2 , respectively, in group 2. There was a statistically significant difference between preoperative ECD and each of 1 week and 3 months postoperative ECD in each group. No significant difference was found between 1-week mean ECD reduction in group 1 (7.35%) and group 2 (6.05%) or between 3-month mean ECD reduction in group 1 (9.69%) and group 2 (8.07%).
Conclusion
Ringer′s and Ringer′s lactate solutions are associated with minimal changes in corneal ECD, morphology, and function during uncomplicated phacoemulsification with foldable intraocular lens implantation in patients with normal endothelial cell counts. There is no clinically significant difference in endothelial cell preservation and polymegathism and corneal swelling between Ringer′s and Ringer′s lactate solutions
Interactions between the volume effects of hydroxyethyl starch 130/0.4 and Ringer´s acetate
Get PDFINTRODUCTION: The turnover of Ringer´s solutions is greatly dependent on the physiological situation, such as the presence of dehydration or anaesthesia. The present study evaluates whether the kinetics is affected by previous infusion of colloid fluid. METHODS: Ten male volunteers with a mean age of 22 years underwent three infusion experiments, on separate days and in random order. The experiments included 10 mL/kg of 6% hydroxyethyl starch 130/0.4 (Voluven™), 20 mL/kg of Ringer's acetate, and a combination of both, where Ringer´s was administered 75 minutes after the starch infusion ended. The kinetics of the volume expansion was analysed by non-linear least- squares regression, based on urinary excretion and serial measurement of blood haemoglobin concentration for up to 420 minutes. RESULTS: The mean volume of distribution of the starch was 3.12 L which agreed well with the plasma volume (3.14 L) estimated by anthropometry. The volume expansion following the infusion of starch showed monoexponential elimination kinetics with a half-life of two hours. Two interaction effects were found when Ringer´s acetate was infused after the starch. First, there was a higher tendency for Ringer´s acetate to distribute to a peripheral compartment at the expense of the plasma volume expansion. The translocated amount of Ringer´s was 70% higher when HES had been infused earlier. Second, the elimination half-life of Ringer´s acetate was five times longer when administered after the starch (88 versus 497 minutes, P <0.02). CONCLUSIONS: Starch promoted peripheral accumulation of the later infused Ringer´s acetate solution and markedly prolonged the elimination half-life
Sulfur Hexafluoride 20% versus Lactated Ringer′s solution for Prevention of Early Postoperative Vitreous Hemorrhage after Diabetic Vitrectomy
No full textPurpose: To compare the hemostatic effect of sulfur hexafluoride 20% (SF6 20%) with lactated Ringer′s solution for prevention of early postoperative vitreous hemorrhage following diabetic vitrectomy.
Methods: In a prospective randomized clinical trial, 50 eyes undergoing diabetic vitrectomy were divided into two groups. At the conclusion of surgery, in one group the vitreous cavity was filled with SF6 20% while in the other group lactated Ringer′s solution was retained in the vitreous cavity. The two groups were compared for the rate of early postoperative vitreous hemorrhage.
Results: The incidence of vitreous hemorrhage was lower in the SF6 group than the Ringer′s group 4 days (20% vs 68%, P=0.001), 7 days (24% vs 60%, P=0.01) and 4 weeks (16% vs 40%, P=0.059) after vitrectomy.
Conclusion: In comparison with lactated Ringer′s solution, SF6 20% had a significant hemostatic effect especially in the early postoperative period after diabetic vitrectomy and reduced the incidence of vitreous hemorrhage
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Corrosion behavior of Ti-xNb-13Zr alloys in Ringer`s solution
No full textTi-6Al-4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V-free alloys and both V- and Al-free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti-13Nb-13Zr alloy is promising due to its better biomechanical compatibility than Ti-6Al-4V. In this work, the corrosion behavior of Ti, Ti-6Al-4V, and Ti-xNb-13Zr alloys (x=5, 13, and 20) was evaluated in Ringer`s solution (pH 7.5) at 37 degrees C through open-circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10(-7) A/cm(2)) and high impedance values (in the order of 10(5) Omega cm(2) at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti-xNb-13Zr alloys were more corrosion resistant than both Ti and Ti-6Al-4V in Ringer`s solution.CNPq (Conselho Nacional de Desenvolvimento e Pesquisa-Brazil)PIBI
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
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