722 research outputs found
Environments of coal formation in the Pleistocene lignite at Megalopolis, Peloponnesus (Greece) - reconstructions from palynological and petrological investigations
No full textThree groups of seams can be distinguished in the thick lignite-bearing sequence of the Pleistocene Khoremi Formation (Marathousa member) near Megalopolis. In the Thoknia open mine the basal 14 m of the lower group of seams (Elias group) have been studied with regard to sedimentology, palynology and organic petrology in order to reconstruct the ecological conditions existing during the initial phase of coal formation. The sedimentary sequence has been established by setting up a macropetrographic seam section. Palynology and organic petrology were studied from identical samples. Macropetrographically the section can be divided into four zones mainly based on the relative frequency of matrix-dominated lithotypes. Xylitic and tissue-rich lithotypes occur in only a few thin bands. The five palynological zones do not coincide with the macropetrographic zones. They reflect an increasing aridity and reduction of the forest vegetation outside the swamp as well as large scale fluctuations of the water table of the lake in the basin centre. On a smaller scale alternations of open lake conditions and encroaching vegetation fringes can be observed.In der mächtigen pleistozänen Lignit-führenden Khoremi Formation (Marathousa Member) können bei Megalopolis (Peloponnes) drei Gruppen von Flözen unterschieden werden. Davon werden im Tagebau Thoknia die untersten 14 m der unteren Gruppe (Elias Gruppe) sedimentologisch, palynologisch und kohlenpetrographisch untersucht. Makropetrographisch kann das Profil in vier Zonen unterteilt werden, die hauptsächlich auf der relativen Häufigkeit der Matrix-dominierten Lithotypen beruhen. Xylitische und Gewebe-reiche Lithotypen kommen nur als vereinzelte dünne Bänder vor. Die fünf ausgeschiedenen palynologischen Zonen stimmen nicht mit den makropetrographischen Zonen überein. Sie zeigen zunehmende Trockenheit und eine Abnahme der Waldvegetation außerhalb des Moores sowie bedeutende Schwankungen des Wasserspiegels im Seebecken an
Deep sequencing of small RNAs confirms an annelid affinity of Myzostomida
No full textMyzostomida comprise a group of marine worms associated mainly with echinoderms since the Carboniferous. Due to their unusual morphology the phylogenetic position in relation to other Lophotrochozoa is discussed since their description. According to different morphological and molecular markers the Myzostomida are either close to Platyzoa or Annelida. Here we investigated small non-coding RNAs of Myzostoma cirriferum to infer the phylogenetic position of myzostomids. Based on transcriptomic data collected by Illumina Deep Sequencing we analyzed the microRNA (miRNA) families occurring in M. cirriferum. Phylogenetic analysis revealed the presence of 13 miRNA-families exclusively shared by Annelida (including Sipuncula) and Myzostomida, as such highly significantly supporting an annelid origin of myzostomids. Furthermore, using a mapping-approach and secondary structure models we predicted several miRNA-candidates unique for myzostomids
Effects of dietary supplementation of nickel and nickel-zinc on femoral bone structure in rabbits
No full textAbstract Background Nickel (Ni) and zinc (Zn) are trace elements present at low concentrations in agroecosystems. Nickel, however, may have toxic effects on living organisms and is often considered as a contaminant. This study reports the effect of peroral administrated Ni or a combination of Ni and Zn on femoral bone structure in rabbits. Methods One month-old female rabbits were divided into three groups of five animals each. Group 1 rabbits were fed a granular feed mixture with addition of 35 g NiCl2 per 100 kg of mixture for 90 days. In group 2, animals were fed a mixture containing 35 g NiCl2 and 30 g ZnCl2 per 100 kg of mixture. Group 3 without administration of additional Ni or Zn served as control. After the 90-day experimental period, femoral length, femoral weight and histological structure of the femur were analyzed and compared. Results The results did not indicate a statistically significant difference in either femoral length or weight between the two experimental groups and the control group. Also, differences in qualitative histological characteristics of the femora among rabbits from the three groups were absent, except for a fewer number of secondary osteons found in the animals of groups 1 and 2. However, values for vascular canal parameters of primary osteons were significantly lower in group 1 than in the control one. Peroral administration of a combination of Ni and Zn (group 2) led to a significant decreased size of the secondary osteons. Conclusions The study indicates that dietary supplementation of Ni (35 g NiCl2 per 100 kg of feed mixture) and Ni-Zn combination (35 g NiCl2 and 30 g ZnCl2 per 100 kg of the mixture) affects the microstructure of compact bone tissue in young rabbits.</p
Oligocene microflora of Obernhausen/Rhön (Germany)
No full textOligocene microflora of Obernhausen/Rhön (Germany
Mirror Landing - As Remembered by Birgit Hult
No full textNotes - This account, Memories Mirror Landing by Birgit Hult, was compiled by Birgit's daughter, Jean Elvira Male, it documents the Hult family's experiences in Mirror Landing from 1912 - 1916. The Hults, who were originally from Sweden, arrived in Mirror Landing with two young children, a third child was born during their stay in Mirror Landing. Upon arriving in the area, the Hults made friends with the Gauthier family. The wives became good friends and would swap piano lessons for English lessons. Details of the log home where the family lived and the surrounding landscape were recalled. A memory about a large forest fire that occurred near the family home and dances that were attended in the town are discussed. Jean recalls her mother's memories regarding the animosity towards the North West Mounted Police that was felt by the people of Mirror Landing. The Hult family retained a strong connection to the Swedish heritage and practised many Swedish traditions, such as flying the Swedish flag and eating hot cross buns stuffed with Swedish Marzipan soaked in warm milk. Photos and a postcard written in 1915 are included in this article (10 pages
Knowing Through Popular Music in the Western Pacific Island World
No full textPacific Indigenous scholars have long emphasized the role of relationality for Pacific Islanders’ epistemologies. In this article, the author rethinks music in terms of the procedural knowledge inherent in and specific to popular music-making by exploring the latter as knowledge practices in Micronesia. This approach opens new vistas on the relationality at the heart of Western Pacific music-making. The author calls the musical manifestation of that relational capacity sound ties, suggesting that if, following Epeli Hau‘ofa, Oceania is “humanity rising from the depths of brine”, then it is not least the sound ties of knowing in and through music that mould that very humanity of people who are at home with the sea into aquapelagic assemblages that are, after all, so much more than water and land
The change of normative gender orders in the process of migration. A transnational perspective
No full textJungwirth I. The change of normative gender orders in the process of migration. A transnational perspective. COMCAD Arbeitspapiere - working papers, 48. Bielefeld: COMCAD - Center on Migration, Citizenship and Development; 2008.In this paper, the question of social change for women as actors of migration is examined. Apart from feminist theory and international gender studies, this topic is located in migration studies and social theory as well. It is proposed to analyse the transformation of gender norms in processes of migration in connection with the changes taking place in the domain of labour, namely the increasing tertiarisation in post-industrial societies on the one hand, and a globalising economy and international distribution of labour following from this on the other. A concept for transnational gender orders is outlined, proposing that, along with these economic and structural processes, normative requirements and ascriptions for social actors are emerging as well. They target the gender performance of women as actors of migration, insofar as an assumed universal gender socialisation as women is becoming a qualification and resource in an international distribution of labour
Structural Changes in Femoral Bone Tissue of Rats after Intraperitoneal Administration of Nickel
No full textThe present study investigated the acute effects of nickel (Ni) on macroscopic and microscopic structure of femoral bone tissue in rats. For this purpose, ten 5-month-old male Wistar rats were injected intraperitoneally with a single dose of 15 mg NiCl(2) per kg of body weight. Ten 5-month-old males without Ni supplementation served as a control group. Forty-eight hours after Ni administration, all animals were killed, and their femora were collected for macroscopic and microscopic evaluation. We found that intraperitoneal application of Ni had no significant effect on femoral weight and femoral length in rats. On the other hand, cortical bone thickness was significantly higher in rats administered Ni (P<0.05). Also, a decreased number of primary and secondary stems was observed in the microstructure of these rats' bones. Morphometrical measurements showed a significant increase in all variables (area, perimeter, maximum, and minimum diameter) of the primary osteons' vascular canals, Haversian canals, and secondary ostcons (P<0.05) in rats from the experimental group. Our results suggest that intraperitoneal injection of NiCl(2) at the level used in this study had no impact on the macroscopic structure of femora of adult male rats; however, it significantly influenced the microscopic structure of their compact bone
Structural Changes in Femoral Bone Tissue of Rats after Intraperitoneal Administration of Nickel
No full textThe present study investigated the acute effects of nickel (Ni) on macroscopic and microscopic structure of femoral bone tissue in rats. For this purpose, ten 5-month-old male Wistar rats were injected intraperitoneally with a single dose of 15 mg NiCl(2) per kg of body weight. Ten 5-month-old males without Ni supplementation served as a control group. Forty-eight hours after Ni administration, all animals were killed, and their femora were collected for macroscopic and microscopic evaluation. We found that intraperitoneal application of Ni had no significant effect on femoral weight and femoral length in rats. On the other hand, cortical bone thickness was significantly higher in rats administered Ni (P<0.05). Also, a decreased number of primary and secondary stems was observed in the microstructure of these rats' bones. Morphometrical measurements showed a significant increase in all variables (area, perimeter, maximum, and minimum diameter) of the primary osteons' vascular canals, Haversian canals, and secondary ostcons (P<0.05) in rats from the experimental group. Our results suggest that intraperitoneal injection of NiCl(2) at the level used in this study had no impact on the macroscopic structure of femora of adult male rats; however, it significantly influenced the microscopic structure of their compact bone
High temperature fatigue crack growth in nickel-based alloys joined by brazing and additive manufacturing
No full textGas turbine components, made of nickel-based alloys, undergo material damage due to high temperatures and mechanical stresses. These components need periodic replacement to avoid efficiency loss and failure. Repair of these parts is more cost-effective than replacement. State-of-the-art repair technologies, including different additive manufacturing (AM) and brazing processes, are considered for efficient restoration. Materials properties mismatches and/or internal defects in repaired parts may expedite crack initiation and propagation, reducing fatigue life. To understand the crack growth behavior in joining zones and predict the remaining life of repaired components, fatigue crack growth (FCG) tests were conducted on specimens of nickel-based alloys joined via brazing, pre-sintered preforms and AM. The FCG experimental technique was successfully adapted for joined specimens and results indicate that the investigated braze material provides a lower resistance to crack growth. In AM-sandwich specimens, the crack growth rates are significantly reduced at the interface of AM and cast material
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