172,044 research outputs found
Du hast uns gerufen
No full textDu hast uns gerufen : Messe für Kinder. - Freiburg i. Br. : Christophorus-Verl., 1970 ca. - Schallpl. : 45 UpM, stereo, 17 c
Du hast uns gerufen
No full textDu hast uns gerufen : Messe für Kinder. - Freiburg i. Br. : Christophorus-Verl., 1970 ca. - Schallpl. : 45 UpM, stereo, 17 c
A 300°C High Reliability HALT/HAST Screening/Sorting Procedure for Ceramic Capacitors
No full textAbstract
A highly accelerated life test (HALT) and highly accelerated stress test (HAST) procedure for ceramic capacitors developed by the author in the mid 1980's to early 1990's, and published in 1994, consists of a 400 Volt biased six (6) hour stress sort at 150°C (423K), a methanol current leakage test that located mechanical and structural cracks, a visual inspection at ten times (10×) magnification, and a capacitance and dissipation measurement before and after the test. In over thirty (30) years of use, there has never been a user reported in-circuit failure in industrial, military, and aerospace application at temperatures as high as 500°C (773K). However, reviewing user feedback, two concerns with the original sorting procedure are the stress is performed at 150°C (423K), and the lack of a more detailed ceramic capacitor electrical model. To address the first, the low aging temperature, the stress temperature was increased from 150°C to 300°C, in order to age ceramic solid state crystal mineral phases that may change with temperature. The test results for X7R and NP0/COG multilayer ceramic capacitors (MLCC) at 300°C, are compared to the test results using the original HALT/HAST procedure at 150°C. Differences between X7R/NP0/COG and porcelain capacitors are discussed when applicable. Further, a more detailed ceramic capacitor electrical model that represents the physical and electrical characteristics of the ceramic capacitors is presented, including the electrical current leakage effects with temperature, and the carbonized residue effects from the manufacturing process.</jats:p
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
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Wie hast Du’s mit der Klassenführung? Die Auseinandersetzung von Lehrkräften mit einer zentralen Dimension der Unterrichtsqualität
No full textObermeier A-C, Frey K, Bonsen M. Wie hast Du’s mit der Klassenführung? Die Auseinandersetzung von Lehrkräften mit einer zentralen Dimension der Unterrichtsqualität. Presented at the Arbeitsgruppe Empirische Pädagogische Forschung (AEPF), Hamburg
Wie hast Du‘s mit der Klassenführung? Die Auseinandersetzung von Lehrkräften mit einer zentralen Dimension der Unterrichtsqualität
No full textFrey K, Bonsen M, Obermeier A-C. Wie hast Du‘s mit der Klassenführung? Die Auseinandersetzung von Lehrkräften mit einer zentralen Dimension der Unterrichtsqualität. In: Prinz D, ed. Der Forschung – der Lehre – der Bildung. Aktuelle Entwicklungen der Empirischen Bildungsforschung. Waxmann; 2016
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
hAST are involved in mediating hBMVEC survival.
No full text<p><b>a</b>. Exposure of hBMVECs to T&I in the presence of conditioned medium from hAST (ACM) that were also exposed to T&I in the presence of S1P modulators (S1P 50 nM, pFTY 50 nM), reduces hBMVEC death. <b>b-d</b> Direct treatment of hBMVEC with S1P (50 nM, <b>b</b>) and AUY (50 nM, <b>d</b>) is compared to the effect of ACM exposed to the same compounds. Direct treatment of hBMVEC with S1P or AUY was more effective in preventing hBMVEC death after T&I if compared to treatment with ACM. hBMVEC were equally protected from cell death by T&I challenge when exposed to either pFTY or ACM derived from hAST treated with pFTY (<b>c</b>). Data are the mean ±S.E.M. of three independent experiments, each run in triplicate, in which three to five fields per well were counted. *p< 0.05 vs T&I, ** p<0.01 vs T&I, # p<0.05 vs direct treatment on hBMVEC.</p
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