Vergleich identischer Beatmungsgeräte desselben Herstellers in Bezug auf abgegebenen Druck und abgegebenes Tidalvolumen an einem Lungenmodell

Ziel der vorliegenden Gerätestudie war es, unter standardisierten Bedingungen an einem Lungenmodell mit volumetrischer Messung und zwischengeschalteter Flussanalyse, verschiedene Geräte einer gleichen Serie, aber auch Geräte verschiedener Hersteller bei identischen Einstellungsvorgaben in Bezug auf Druckverlauf bzw. die Volumenabgabe vergleichend zu untersuchen

Vergleich identischer Beatmungsgeräte desselben Herstellers in Bezug auf abgegebenen Druck und abgegebenes Tidalvolumen an einem Lungenmodell

Ziel der vorliegenden Gerätestudie war es, unter standardisierten Bedingungen an einem Lungenmodell mit volumetrischer Messung und zwischengeschalteter Flussanalyse, verschiedene Geräte einer gleichen Serie, aber auch Geräte verschiedener Hersteller bei identischen Einstellungsvorgaben in Bezug auf Druckverlauf bzw. die Volumenabgabe vergleichend zu untersuchen

Modern brackish bryostromatolites (“bryoliths”) from Zeeland (Netherlands)

Bryostromatolites are found in stressed environments from the Paleozoic to the Recent. They are formed by alternating layers of bryozoans and microbes. This study investigates recent bryostromatolites in brackish ponds in the Netherlands to better understand ancient analogues and the environments which hosted them. They formed a fringing reef at the site Ronde Weel and a barrier reef at Kaaskenswater. The ponds had low biodiversity with only one bivalve species, two gastropod species, one ostracod species, and three diatom species comprising most of the easily fossilizable taxa; one isopod species, one decapod species, and two polychaete species were also present. Observations of microbial layers and cementation practices indicate that an alternation of bryozoan-favouring conditions and microbe-favouring conditions is essential to forming bryostromatolites. The collected bryostromatolites only had tiny living bryozoan patches. Water tests confirmed a brackish environment but with enriched arsenic and titanium concentrations and periodic euxinia. The extreme environment explains the lack of biodiversity and may provide information about the environments in which past bryostromatolites formed.Friedrich-Alexander-Universität Erlangen-Nürnberg (1041

Microfacies analysis and 3D reconstruction of bioturbated sediments in the calcarenite di Gravina formation (southern Italy)

The Calcarenite di Gravina is a poorly lithified, heterogeneous bio-lithoclastic Plio-Pleistocene limestone formed in a temperate shallow-water setting. Since prehistoric times it has been used for construction, as witnessed by the “Sassi”, the old city center of Matera (southern Italy). Here, the relatively distal, fine-grained bioclastic grain- packstone is characterized by large bioturbation structures of crustaceans. The aim of this work is to understand how bioturbation controls texture, porosity, permeability, and the cementation of the calcarenite. Crustaceans such as Callianassa are known to produce vertical burrows and sort grains. A bioturbated calcarenite level, outcropping in the Parco Scultura- Cava Paradiso in La Palomba (Matera northern area), has been selected as case study. Large rock samples including fossil traces and surrounding rocks have been analysed. Optical mi- croscope and SEM observations show a close connection between sediment sorting and cementation, and 3D analyses by means of CT scans indicate that the internal structure and the connected porosity of the samples is a function of the cementation. Moreover, the porosity network is reconstructed in 3D in order to derive the real connected porosity variations and their implications for the evolution in terms of diagenesis and alteration of the rocks. Indeed, a cementation gradient from the external lining of the burrows to the internal part of the trace fossil is observed. Cementation is less pronounced outside of the trace fossil. Cluster analysis of point-counting results allows to identify four sub-facies characterized by differences in composition, cementation and porosity. One of them is present in the interior of the burrows while the other two characterize the external lining (crust) and storage chamber of crustacean burrows. The last sub-facies occurs in the area surrounding the trace fossils and shows a weaker cementation. The presence of a cementation gradient inside the trace fossil is explained through a diagenetic model that considers the contribution of different factors. The geochemical environments allow the CaCO3 precipitation inside the burrows starting from the lining to the internal area thanks to the microbial actions, water circulation and relative oxygenation of fluids. Dissolution of aragonitic components probably represents the principal source of CaCO3. Variation in cementation and porosity are quite moderate, but capable of generating major differences in the resistance to weathering. From this study it emerges how the diagenetic processes lead to significant changes in the bioturbated fabric, making the burrows less permeable than the surrounding sediment. This is confirmed by the selective erosion that brings to light very well-preserved traces of Callianassidae even on building stones

Growth Interruptions in Arctic Rhodoliths Correspond to Water Depth and Rhodolith Morphology

Coralline algae that form rhodoliths are widespread globally and their skeletal growth patterns have been used as (paleo-) environmental proxies in a variety of studies. However, growth interruptions (hiati) within their calcareous skeletons are regarded as problematic in this context. Here we investigated how hiati in the growth of Arctic rhodoliths from the Svalbard archipelago correspond to their environment and morphology. Using X-ray micro-computed tomography and stepwise model selections, we found that rhodoliths from deeper waters are subject to more frequent hiatus formation. In addition, rhodoliths with a higher sphericity (i.e., roundness) are less often affected by such growth interruptions. We conclude that these correlations are mainly regulated by hydrodynamics, because, in deeper waters, rhodoliths are not turned frequently enough to prevent a dieback of coralline algal thalli forming on the underside of the rhodolith. In this coherence, spheroidal rhodoliths are turned more easily, therefore shortening the amount of time between turnover events. Moreover, the incidence of light is more advantageous in shallower waters where rhodoliths exhibit a greater share of their surface to diffused ambient light, thus enabling thallus growth also on the down-facing surface of the rhodoliths. In consequence, information on the frequency of hiatus formation combined with rhodolith morphology might serve as a valuable proxy for (paleo-)environmental reconstructions in respect to light availability and the hydrodynamic regime

Biostratigraphy and sequence stratigraphy of the Toarcian Ludwigskanal section (Franconian Alb, Southern Germany)

Extensive construction work at the canal cutting of the Ludwigskanal near Dörlbach, Franconian Alb, provided the opportunity to re-investigate a scientific-historical and biostratigraphically important reference section of the South-German Toarcian. The 16 m thick section, described bed by bed with respect to lithology and macrofossils, starts within the Upper Pliensbachian Amaltheenton Formation, covers the Toarcian Posidonienschiefer and Jurensismergel Formation, and ends in basal parts of the Opalinuston Formation. Carbonate contents are high in the Posidonienschiefer and successively decline within the Jurensismergel to basal parts of the Opalinuston. The high carbonate contents in the Posidonienschiefer are associated with comparatively low organic carbon contents. However, organic carbon contents normalized to the silicate fraction are similarily high if compared to other regions in Germany. Only the persistence of high organic carbon levels into middle parts of the Upper Toarcian differs from those of most regions in central Europe. Ammonite biostratigraphy indicates a thickness of >9 m for the Upper Pliensbachian, 1.15–1.20 m for the Lower Toarcian, 5.04 m for the Upper Toarcian, and >0.5 m for the Lower Aalenian. Despite the low sediment thickness, all Toarcian ammonite zones and almost all subzones are present, except for major parts of the Tenuicostatum Zone and the Fallaciosum Subzone. On the basis of discontinuities, condensed beds, and correlations with neighbouring sections in Southern Germany, a sequence stratigraphic interpretation is proposed for the Toarcian of this region: (i) The Posidonienschiefer Formation corresponds to one 3rd order T-R sequence, from the top of the Hawskerense Subzone to a fucoid bed at the top of the Variabilis Subzone, with a maximum flooding surface at the top of the Falciferum Zone. (ii) The Jurensismergel Formation exhibits two 3rd order T-R sequences: The first ranges from the basis of the Illustris Subzone (i.e., the Intra-Variabilis-Discontinuity) to the top of the Thouarsense Zone, with a maximum flooding surface within the Thouarsense Zone. The “belemnite battlefield” reflects a transgressive “ravinement surface” within the first Jurensismergel Sequence, not a maximum regression surface at its basis. The second sequence extents from the erosive basis of the Dispansum Zone to the top of the Aalensis Subzone, with a maximum flooding surface at the Pseudoradiosa-Aalensis Zone boundary. Finally, the Opalinuston starts with a new sequence at the basis of the Torulosum Subzone. Transgressive system tracts of these 3rd order T-R sequences are commonly phosphoritic, while some regressive system tracts show pyrite preservation of ammonites. The maximum regression surfaces at the basis of the Toarcian and within the Variabilis Zone reflect a significant submarine erosion and relief formation by seawater currents, while this effect is less pronounced at the basis of the Dispansum Zone and basis of the Torulosum Subzone (i.e., the boundary Jurensismergel-Opalinuston Formation)

A piranha-like Pycnodontiform fish from the Late Jurassic

Pycnodontiformes are an extinct order of ray-finned fishes from the Triassic to Eocene [1, 2] , with a characteristic crushing dentition reflecting a highly specialized diet [3] . However, our discovery of a new pycnodontiform from the Late Jurassic (ca. 152 Ma) Plattenkalk deposits of the Solnhofen Archipelago revealed long, pointed teeth along the vomer and triangular teeth with cutting edges along the prearticulars. This is the earliest evidence of specialized flesh cutting in a ray-finned fish. The dentition pattern, tooth shape, jaw morphology, and mechanics are all indicative of a feeding apparatus suitable for slicing flesh or fins, thus pioneering a new ecological niche. Evidence suggests that it may have exploited aggressive mimicry in a striking parallel to the feeding patterns of modern piranha. Remarkably, fossil fishes recovered from the same deposits as the new pycnodontiform show injuries to fins and fin bases. As a marine piranha-like fish contemporary with dinosaurs, it is the oldest known flesh-eating actinopterygian, revealing remarkable convergent evolution with modern piranhas

Modern brackish bryostromatolites (“bryoliths”) from Zeeland (Netherlands)

<jats:title>Abstract</jats:title><jats:p>Bryostromatolites are found in stressed environments from the Paleozoic to the Recent. They are formed by alternating layers of bryozoans and microbes. This study investigates recent bryostromatolites in brackish ponds in the Netherlands to better understand ancient analogues and the environments which hosted them. They formed a fringing reef at the site Ronde Weel and a barrier reef at Kaaskenswater. The ponds had low biodiversity with only one bivalve species, two gastropod species, one ostracod species, and three diatom species comprising most of the easily fossilizable taxa; one isopod species, one decapod species, and two polychaete species were also present. Observations of microbial layers and cementation practices indicate that an alternation of bryozoan-favouring conditions and microbe-favouring conditions is essential to forming bryostromatolites. The collected bryostromatolites only had tiny living bryozoan patches. Water tests confirmed a brackish environment but with enriched arsenic and titanium concentrations and periodic euxinia. The extreme environment explains the lack of biodiversity and may provide information about the environments in which past bryostromatolites formed.</jats:p&gt

Ultrastructure of the epidermal gland system of Tetranchyroderma suecicum Boaden, 1960 (Gastrotricha: Macrodasyida) indicates a defensive function of its exudate

Although the phylum Gastrotricha is known and studied for more than 150 years, some cell types, tissues and organ systems are still not well understood in terms of their morphology, ultrastructure, function and role. One of these features is the epidermal gland system (EGS). As yet, there is just a single detailed electron microscopic investigation of the epidermal glands of the species Turbanella cornuta Remane, 1925, plus scattered ultrastructural data of few additional species. We comprehensively investigated the epidermal glands of Tetranchyroderma suecicum Boaden, 1960 by means of serial sectioning and transmission electron microscopy (TEM) and with scanning electron microscopy. Furthermore, light microscopical, confocal laser scanning microscopical and micro-computed tomographical (mu CT) techniques were additionally used for this investigation. Computer programs for 3D-reconstructions were used to analyse the data obtained by TEM and mu CT. Tetranchyroderma suecicum possesses up to 100, mostly pairwise arranged, glandulocytes. Each single-celled gland contains a large anastomosing secretory cistern with granular content, has a very electron-dense cytoplasm, a basally positioned nucleus, peripherally arranged mitochondria and a cuticulated, 'chimney-like' apical neck, which carries the cellular pore. Each merocrine glandulocyte is associated with an adjacent ciliated sensory cell. There is currently no coherent hypothesis of the glandulocytes' functional role, but different ideas are discussed. We refer to evidence that the secretory product of the EGS of Tetranchyroderma suecicum most likely acts as a repellent against potential predators