169,967 research outputs found
Margaret L. Ahrendt (1907-1979) and Fred C. Ahrendt (1902-), purchased by Fred C. Ahrendt on July 3, 1980
No full textAn order for two monuments, one for Margaret L. and the other for Fred C. Ahrendt, purchased by Fred Ahrendt for himself and his wife. The markers, made of ""Balfour Pink"" granite, will be inscribed with ""Margaret L. Ahrendt; 1907-1979"" on the one and ""Fred C. Ahrendt; 1902-"" on the other. A cross is to be etched between the birth and death years on both stones. The stones are to be installed on lot 56, section 28, graves 10 & 12 in Toledo Memorial Park in Sylvania, Ohio
Lettie Head, (1870-1961), purchased by Mr. C. Ahrendt on May 3, 1962.
No full textDocuments regarding the headstone for Lettie Head, (1870-1961), purchased by Mr. C. Ahrendt. The marker was placed at Morenci Cemetery, Toledo, Michigan. The stone is made of Ruby Red with Sandblast letters
Age and degree of metamorphism and time of nappe emplacement along the southern margin of the Damara Orogen/Namibia (SW-Africa)
No full textK/Ar Age Determinations on very low grade Metasediments of the Rheinisches Schiefergebirge
No full textDer Metamorphosegrad der devonischen und karbonischen Gesteine des Rheinischen Schiefergebirges entspricht dem "very low grade" sensu WINKLER (1976) bzw. der "Anchimetamorphose" sensu KUBLER (1969). Dies ergibt sich aus Untersuchungen der Illit-Kristallinität, der Inkohlung sowie nach mineralfaziellen Kriterien. Nach letzteren sind die mitteldevonischen Gesteine des Ostsauerländer Hauptsattels, Teile der Lahn-Dill Mulde, der Moselmulde, des Hunsrück und Taunus in die Pumpellyit-Prehnit-Quarz Fazies zu stellen, ausgenommen die etwas höher metamorphen Gesteine des "Taunus-Vordevons". Auf einem N-S Profil vom Ostsauerländer Hauptsattel bis zum Taunus-Südrand wurde das radiometrische Alter dieser Metamorphose mit der K/Ar-Methode bestimmt. Für die Altersbestimmungen wurden solche Gesteine ausgewählt, bei denen angenommen werden kann, daß ihr Phyllosilikatbestand weitgehend metamorph entstanden ist. Zum Teil handelt es sich dabei um reine Serizitschiefer, die vermutlich aus sauren bis intermediären Glastuffen entstanden sind, zum anderen sind es Serizit- und Seladonit-führende extrem feinkörnige Tuffe, die vermutlich zum mitteldevonischen Hauptgrünsteinvulkanismus gehören. Da aufgrund des sehr geringen Metamorphosegrades angenommen werden kann, daß bei den Hellglimmern die Schließungstemperatur für das System K/Ar nicht überschritten wurde - ausgenommen im "Taunus-Vordevon" - ergeben die Datierungen kein Abkühlungsalter, sondern das Alter des Höchststandes der Metamorphose. Danach liegt das Metamorphosealter im nordöstlichen Rheinischen Schiefergebirge um 300 Mio. Jahre, während es nach Süden hin über 315 Mio. bis auf etwa 330 Mio. Jahre im Taunus ansteigt. Das südlich anschließende "Taunus-Vordevon" zeigt etwas jüngere Alter, die wegen der hier höher temperierten Metamorphose als Abkühlungsalter gedeutet werden. Die Alterswerte um 330 Mio. Jahre in der Lahnmulde wurden an phyllitischen Tonschiefern bestimmt, die wahrscheinlich durch Deckentransport vom Südrand des Schiefergebirges in ihre heutige Position gelangten und daher noch die höheren Alter dieses Südrandes zeigen. Der Alterssprung am Nordrand des Schiefergebirges von 300 Mio. auf etwa 340 Mio. Jahre ist problematisch und wird gegenwärtig näher untersucht. Da in bezug auf die Faltung und erste Schieferung die Metamorphose synkinematisch erfolgte, geben die Alter nicht nur den Höchststand der Metamorphose im östlichen Rheinischen Schiefergebirge an, sondern datieren gleichzeitig den Zeitpunkt der Deformation. Allerdings hat die Deformation den Höchststand der Metamorphose überdauert, wie sich aus der großen Verbreitung der post-kristallinen zweiten Schieferung ergibt.The metamorphic grade of the Devonian and Carboniferous rocks of the Rheinisches Schiefergebirge corresponds to the "very low grade" sensu WINKLER (1976) respectively to the "anchi-zone" sensu KUBLER (1969). This follows from investigations of illite-cristallinity, coalification and of metamorphic mineral parageneses. According to these date the Middle Devonian rocks of the Ostsauerländer Anticline, parts of the Lahn-Dill Syncline, the Mosel Syncline, the Hunsrück and the Taunus Mountains belong to the pumpellyite-prehnite-quartz facies, excepting the somewhat higher grade metamorphic rocks of the "Taunus Pre-Devonian". Along a N-S cross-section from the Ostsauerländer Anticline to the southern border of the Taunus the radiometric age of this metamorphism was determined by the K/Ar-method. For the age determinations only such rock samples containing phyllosilicate fabrics of presumably metamorphic origin were selected. These samples are either pure sericite slates, probably derived from acid to intermediate glass-tuffs, or sericite- and celadonite-bearing extremely fine-grained tuffs which probably belong to the Middle Devonian volcanism. The samples are therefore assumed to be practically free from detrital phyllosilicates. Because of the very low degree of metamorphism it can be assumed that the blocking temperature for the K/Ar system of white micas was not exceeded-except in the "Taunus-Pre-Devonian". Therefore these age determinations do not give cooling ages but date the peak of metamorphism. According to these datings the age of metamorphism in the northeastern Rheinisches Schiefergebirge is about 300 m.y. whereas it increases towards the south to 315 m. y. and up to 330 m. y. in the Taunus. The "Taunus Pre-Devonian" rocks, following to the south, have yielded younger ages which are interpreted as cooling ages because during metamorphism the temperatures in this area axceeded the blocking temperature for the K/Ar system of the micas. The ages of about 330 m.y. in the Lahn Syncline were measured on phyllitic slates. These rocks probably were emplaced by nappe movement from the southern margin of the Schiefergebirge into their present position and therefore have preserved the higher ages of the southern margin. The sudden transition from 300 m.y. to about 340 m.y. at the northern margin of the Schiefergebirge is still problematical and a matter of present investigations. The metamorphism is synkinematic with respect to the folding and associated first cleavage. For that reason the ages do not only give the peak of metamorphism, but also date the time of deformation. The deformation, however, outlasted the peak of metamorphism, as shown by the widespread distribution of a post-crystalline second cleavage
Migration of Folding and Metamorphism in the Rheinische Schiefergebirge Deduced from K-Ar and Rb-Sr Age Determinations
No full textn the very low- to low-grade metamorphic Rhenohercynian Zone of the Variscides a migration of folding has been postulated which was deduced from the shifting of flysch sedimentation.
In order to get an idea of the time span which the “wave” of folding and metamorphism has needed to pass through the Rheinische Schiefergebirge, isotopic investigations by K-Ar and Rb-Sr methods were carried out. For these measurements the fine mineral fractions <2μm from pure sericite slates probably derived from acid to intermediate glass-tuffs were analyzed. Furthermore extremely fine-grained sericite- and celadonite-bearing tuffs were taken which probably belong to the Middle Devonian volcanism.
Because of the very low degree of metamorphism in the Rheinische Schiefergebirge it can be assumed, that the blocking temperatures for the K-Ar and Rb-Sr systems of white micas were not exceeded — except for the K-Ar system in the “Taunus-Pre-Devonian”. Therefore most of the age determinations are indicative of the peak of metamorphism.
A determination of the age of folding was only possible on the proved assumption that:
The metamorphism is syntectonic with respect to folding. Therefore a determination of the metamorphic ages includes the determination of the age of folding.
The samples used for the isotopic investigations were not allowed to contain old sedimentary — not recrystallized — white micas. Only rock samples containing phyllosilicate fabrics of metamorphic origin were selected.
According to the K-Ar and Rb-Sr age determinations the age of metamorphism and folding in the Rheinische Schiefergebirge decreases from about 330 Ma in the Taunus towards the north to 300 Ma at the northern border.
Three exceptions modify this evolutionary history from the south to the north:
Lower ages in the “Taunus-Pre-Devonian” rocks have to be interpreted as cooling ages because the temperatures in this area exceeded the blocking temperature for the K-Ar system of the micas during metamorphism.
Higher ages in the Lahn Syncline of about 330 to 340 Ma which belong to rocks emplaced into their present position by nappe movement from the southern margin of the Schiefergebirge. They therefore preserved the higher metamorphic ages of the southern margin.
The high K-Ar age of about 340 Ma at the northern margin of the Schiefergebirge is interpreted as an influence of the North European Caledonian orogeny.
The synmetamorphic “wave” of folding passed through the Rheinische Schiefergebirge from the northern border of the Mid-German Crystalline Rise to the present northern border in approx. 30 Ma. This would correspond to a “velocity of crustal shortening” of about 0,5 cm/year, if one assumes a mean tectonic shortening of about 50% in the Rheinische Schiefergebirge resulting from compression during deformation. These values have to be regarded as minimum values
Geochronological cross section through northern Thailand
No full textlsotopic age determinations were carried out on seven different localities along a cross section through northern Thailand. First results of U-Pb investigations on zircons of rocks from the crystalline basement west
of Tak indicates a maximum age of some 200 Ma for the last amphibolite facies overprint instead of Precambrian.
Tertiary K-Ar ages of around 30 Ma on mica separates of these crystalline rocks must be interpreted as cooling
ages requiring tectonic movements with strong uplift in Tertiary time.
Additional information of the tectono-metamorphic evolution of northern Thailand is given by K-Ar ages on
fine mineral fractions of slates which date the peak of a regional metamorphism and the time of deformation.
The low grade metamorphic overprinting in the eastern parts of northern Thailand covers a range from 250 Ma
to 60 Ma indicating a long lasting deformational history. The obtained data are consistent with the idea of a
continuous transpressive regime since Permian/Triassic time resulting in thin-skinned tectonics in the eastern part and ramping, shearing and strong uplifting especially in Tertiary time in the western parts
Basin analysis and mineral endowment of the proterozoic Itajai' Basin, south- east Brazil
No full textA basin evolution synthesis and an integration of geological and geophysical data, relevant as guides to the exploration of gold and lead–zinc deposits in the Itajaı ́Basin, are presented in this paper. The Itajaı ́Basin is interpreted as a collision-related foreland basin consisting of weakly metamorphosed sediments deposited between the structural front of the Dom Feliciano fold and thrust belt and the proximal flank of the cratonic forebulge. Its sediments represent a second-order depositional sequence deposited during a foreland transgression–regression cycle related to flexural subsidence. After deposition, the basin underwent a main late-collisional compressional deformation phase followed by an extensional post-orogenic relaxation. Known gold and lead–zinc deposits are associated with late-orogenic faulting of the Itajaı ́Basin sediments. The gold-bearing quartz veins are of filonean hydrothermal aYliation, while the lead–zinc deposits were formed by solution-remobilization in a meteoric–connate–magmatic mineralizing fluid. Major trends of favourability for such deposits are recognized. The most favourable sites for lead–zinc deposits are near known mineralized areas and also along a NE-orientated fault at the margin adjacent to the Dom Feliciano metamorphic belt. The higher favourability for gold deposits is assigned to an area along the same NE trend, and also around a small known deposit near the cratonic margin
Palaeobotanical and geochronological evidence for the Alpine age of the metamorphism in the Sesia-Zone
No full textDas Alter der letzten Metamorphose der Sesia-Zone wurde lange Zeit für herzynisch oder älter gehalten. Als Argument dienten Grundgebirgseinschlüsse in den Trachyandesiten bis Andesiten der Sesia-Zone. Diese Vulkanite hielt man in Analogie zu den permischen Vulkaniten der Südalpen für permisch. In jüngster Zeit wurden in Tuffiten der Sesia-Vulkanite Pflanzenreste gefunden, die als oberkarbonisch beschrieben wurden. Diese Schlüsse standen in Diskrepanz zu strukturgeologischen Beobachtungen und zu den zahlreichen radiometrischen Altersbestimmungen in der Sesia-Zone und zwangen zur nochmaligen überprüfung der paläobotanischen Evidenzen. Die von uns gefundene Flora weist sehr moderne Züge auf und läßt sich mit Sicherheit ins Tertiär einstufen. Kein einziges paläozoisches Fossil wurde gefunden. Das durch die Pflanzenreste bestätigte tertiäre Alter der Vulkanite konnte mit radiometrischen K-Ar-Gesamtgesteinsaltern auf 29–33 m.y. präzisiert werden. Die letzte Hochdruck-Metamorphose in der Sesia-Zone fand nach K-Ar-Altersbestimmungen an Glimmern zwischen 60 und 90 m. y. statt. Vor ca. 38 m. y. wurden die alpeneinwärts liegenden Partien der Sesia-Zone von der lepontinischen Kristallisationsphase in Grünschieferfazies überprägt.For a long time the age of the last metamorphism of the Sesia-zone was considered to be Hercynian or older. Basement inclusions in basic volcanics were the main argument for this interpretation. The Trachyandesites — Andesites of the Sesia-zone were regarded as Permian, analogoues to the widespread Permian volcanics of the Southern Alps. Recently, plant remnants have been found in tuffitic interlayers of the Sesia volcanics. These fossils have been described as palaeozoic plants, in contradiction to structual observations and to the numerous radiometric data acquired in the region. To check the age of the fossils a detailed palaeobotanical study was carried out. Our samples contained a very modern flora of definitely Tertiary age. Not one palaeozoic fossil was detected. The Tertiary age found on palaeobotanical evidence proved to be between 29 and 33 m. y. on the basis of total rock K-Ar ages. The last high pressure metamorphism of the Sesia-zone occurred between 90 and 60 m. y. as has been shown by radiometric ages on micas. The external part of the zone was overprinted by the Lepontine phase of metamorphism in greenschist facies 38 m. y. ago
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
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
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