3,080 research outputs found
Head, trunk and in between: the evolution and development of muscles in the head/trunk interface of vertebrates
The vertebrate head is often regarded as a discrete developmental unit, distinct from the trunk and governed by a different patterning mechanism. The head is patterned according to the branchial arches with patterning information primarily derived from the endoderm, a principle called “branchiomerism”. The trunk in contrast is patterned according to the somites, segmented blocks of mesoderm, a principle called “somitomerism”. The region of the vertebrate body where these two distinct patterning mechanisms meet is termed the head/trunk interface. The co-existence of two fundamentally different developmental patterning principles at the same axial level of the body is unique to vertebrates. As far as we know, the body architecture of all other animals is always based on one underlying patterning principle. The vertebrate head/trunk interface therefore offers a unique model to study how two different patterning principles interact in development and if this interaction might have played a special role in the evolutionary diversification of vertebrates
Enhancing of catalytic properties of vanadia via surface doping with phosphorus using atomic layer deposition
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Vac. Sci. Technol. A 34, 01A135 (2016) and may be found at https://doi.org/10.1116/1.4936390.Atomic layer deposition is mainly used to deposit thin films on flat substrates. Here, the authors deposit a submonolayer of phosphorus on V2O5 in the form of catalyst powder. The goal is to prepare a model catalyst related to the vanadyl pyrophosphate catalyst (VO)2P2O7 industrially used for the oxidation of n-butane to maleic anhydride. The oxidation state of vanadium in vanadyl pyrophosphate is 4+. In literature, it was shown that the surface of vanadyl pyrophosphate contains V5+ and is enriched in phosphorus under reaction conditions. On account of this, V2O5 with the oxidation state of 5+ for vanadium partially covered with phosphorus can be regarded as a suitable model catalyst. The catalytic performance of the model catalyst prepared via atomic layer deposition was measured and compared to the performance of catalysts prepared via incipient wetness impregnation and the original V2O5 substrate. It could be clearly shown that the dedicated deposition of phosphorus by atomic layer deposition enhances the catalytic performance of V2O5 by suppression of total oxidation reactions, thereby increasing the selectivity to maleic anhydride.DFG, 53182490, EXC 314: Unifying Concepts in Catalysi
The biogenetic law and the Gastraea theory: From Ernst Haeckel's discoveries to contemporary views
More than 150 years ago, in 1866, Ernst Haeckel published a book in two volumes called Generelle Morphologie der Organismen ( General Morphology of Organisms ) in the first volume of which he formulated his biogenetic law, famously stating that ontogeny recapitulates phylogeny. Here, we describe Haeckel's original idea as first formulated in the Generelle Morphologie der Organismen and later further developed in other publications until the present situation in which molecular data are used to test the “hourglass model,” which can be seen as a modern version of the biogenetic law. We also tell the story about his discovery, while traveling in Norway, of an unknown organism, Magosphaera planula , that was important in that it helped to precipitate his ideas into what was to become the Gastraea theory. We also follow further development and reformulations of the Gastraea theory by other scientists, notably the Russian school. Elias Metchnikoff developed the Phagocytella hypothesis for the origin of metazoans based on studies of a colonial flagellate. Alexey Zakhvatin focused on deducing the ancestral life cycle and the cell types of the last common ancestor of all metazoans, and Kirill V. Mikhailov recently pursued this line of research further
First experiences with the implementation of the European standard EN 62304 on medical device software for the quality assurance of a radiotherapy unit
BACKGROUND: According to the latest amendment of the Medical Device Directive standalone software qualifies as a medical device when intended by the manufacturer to be used for medical purposes. In this context, the EN 62304 standard is applicable which defines the life-cycle requirements for the development and maintenance of medical device software. A pilot project was launched to acquire skills in implementing this standard in a hospital-based environment (in-house manufacture). METHODS: The EN 62304 standard outlines minimum requirements for each stage of the software life-cycle, defines the activities and tasks to be performed and scales documentation and testing according to its criticality. The required processes were established for the pre-existent decision-support software FlashDumpComparator (FDC) used during the quality assurance of treatment-relevant beam parameters. As the EN 62304 standard implicates compliance with the EN ISO 14971 standard on the application of risk management to medical devices, a risk analysis was carried out to identify potential hazards and reduce the associated risks to acceptable levels. RESULTS: The EN 62304 standard is difficult to implement without proper tools, thus open-source software was selected and integrated into a dedicated development platform. The control measures yielded by the risk analysis were independently implemented and verified, and a script-based test automation was retrofitted to reduce the associated test effort. After all documents facilitating the traceability of the specified requirements to the corresponding tests and of the control measures to the proof of execution were generated, the FDC was released as an accessory to the HIT facility. CONCLUSIONS: The implementation of the EN 62304 standard was time-consuming, and a learning curve had to be overcome during the first iterations of the associated processes, but many process descriptions and all software tools can be re-utilized in follow-up projects. It has been demonstrated that a standards-compliant development of small and medium-sized medical software can be carried out by a small team with limited resources in a clinical setting. This is of particular relevance as the upcoming revision of the Medical Device Directive is expected to harmonize and tighten the current legal requirements for all European in-house manufacturers
The connection between teaching and learning. Linking teaching quality and metacognitive strategy use in primary school
Background: In order for teaching to be successful, students need to be actively involved in learning. However, research on teaching effectiveness often neglects students\u27 learning activities. Although it is assumed that effective teaching promotes the use of beneficial learning activities, empirical evidence for this connection is still limited. Aims: This study aimed to investigate the connection between effective teaching and reported learning activities. We hypothesize specific relations between a three-dimensional model of teaching quality (i.e., cognitive activation, supportive climate, and classroom management) and students\u27 reported use of metacognitive strategies. Students\u27 intrinsic motivation is considered as a mediator and a moderator of this connection. Sample: N = 1,052 students from 53 German primary school classes and their science teachers participated. Methods: Data were collected through classroom or video observation and questionnaires over a period of approximately 2 months. Multilevel analysis was utilized to test our hypotheses. Results: Each dimension of teaching quality positively predicted students\u27 reported use of metacognitive strategies. For supportive climate, this connection was mediated by students\u27 intrinsic motivation. Cognitive activation negatively predicted the slopes between students\u27 reported metacognitive strategy use and motivation. Conclusions: The results support the notion that effective teaching is connected to learning activities and stress the importance of students\u27 learning motivation. Results from the cross-level interaction could indicate that especially less motivated students\u27 reported metacognitive strategy use might be supported by cognitively activating teaching. (DIPF/Orig.
LIME : Software for 3-D visualization, interpretation, and communication of virtual geoscience models
Parts of LIME have been developed to address research requirements in projects funded by the Research Council of Norway (RCN) through the Petromaks and Petromaks 2 programs. The following grants are acknowledged: 153264 (VOG [Virtual Outcrop Geology]; with Statoil ASA), 163316 (Carbonate Reservoir Geomodels [IRIS (International Research Institute of Stavanger)]), 176132 (Paleokarst Reservoirs [Uni Research CIPR]), 193059 (EUSA; with FORCE Sedimentology and Stratigraphy Group), 234152 (Trias North [University of Oslo]; with Deutsche Erdoel AG, Edison, Lundin, Statoil, and Tullow), 234111 (VOM2MPS [Uni Research CIPR]; with FORCE Sedimentology and Stratigraphy Group), as well as SkatteFUNN (RCN) project 266740. In addition, the SAFARI project consortium (http://safaridb.com) is thanked for its continued support. The OSG and wxWidgets communities are acknowledged for ongoing commitment to providing mature and powerful software libraries. All authors thank colleagues past and present for studies culminating in the presented figures: Kristine Smaadal and Aleksandra Sima (Figs. 1 and 4); Colm Pierce (Fig. 2A); Eivind Bastesen, Roy Gabrielsen and Haakon Fossen (Fig. 3); Christian Haug Eide (Fig. 7); Ivar Grunnaleite and Gunnar Sælen (Fig. 8); and Magda Chmielewska (Fig. 9). Isabelle Lecomte contributed to discussions on geospatial-geophysical data fusion. Bowei Tong and Joris Vanbiervliet are acknowledged for internal discussions during article revision. The lead author thanks Uni Research for providing a base funding grant to refine some of the presented features. Finally, authors Buckley and Dewez are grateful to Institut Carnot BRGM for the RADIOGEOM mobility grant supporting the writing of this paper. Corbin Kling and one anonymous reviewer helped improve the final manuscript.Peer reviewedPublisher PD
Microcharacterization of Interface Oxide Layer on Laser-Structured Silicon Surfaces of Plated Ni–Cu Solar Cells
Impact of a Major Inflow Event on the Composition and Distribution of Bacterioplankton Communities in the Baltic Sea
Major Baltic inflow (MBI) events carry highly saline water from the North Sea to
the central Baltic Sea and thereby affect both its environmental conditions and its
biota. While bacterioplankton communities in the Baltic Sea are strongly structured by
salinity, how MBIs impact the composition and distribution of bacteria is unknown.
The exceptional MBI in 2014, which brought saline and oxygenated water into the
basins of the central Baltic Sea, enabled the linkage of microbiological investigations
to hydrographic and modeling studies of this MBI. Using sequence data of 16S
ribosomal RNA (rRNA) and 16S rRNA genes (rDNA), we analyzed bacterioplankton
community composition in the inflowing water and in the uplifted former bottomwater at stations reached by the MBI. Bacterial diversity data were compared with
respective data obtained from previous, non-inflow conditions. Changes in bacterial
community composition following the 2014 MBI were mainly apparent at the genus level.
A number of specific taxa were enriched in the inflowing water, with large changes in the
rRNA/rDNA ratios indicating the different activity levels between of the water masses.
The relative similarity of the bacterial communities in the inflowing and uplifted waters as
well as the results from an inflow-simulating numerical model showed that the inflowing
water did not originate directly from the North Sea but mostly from adjacent areas in
the Baltic Sea. This suggested that the inflow event led to a series of shifts in Baltic Sea
water masses among the Baltic Sea basins and a gradual mixing of the water bodies.
Dramatic changes in the bacterial community composition occurred when the bottomwater inflow reached the anoxic, sulfidic deep basins, resulting in an uplifting of the
formerly anoxic bacterial community, dominated by Epsilonproteobacteria. Our study of
the impact of MBIs on bacterioplankton communities therefore highlights two relevant
underlying mechanisms that impact the distribution and possibly also the activities of
planktonic bacteria in the Baltic Sea: (1) the successive dilution of inflowing North Sea
water with ambient waters and (2) the uplifting of former bottom-water communities to
higher water strata.This work was funded by the Deutsche Forschungsgemeinschaft (DFG) (projects JU367/15-1, JU367/16-1 to KJ and LA1466/8- 1 to ML). DH was supported by the European Regional Development Fund and the Estonian Research Council Mobilitas Plus Top Researcher grant “MOBTT24.” UG was supported by the BMBF project “Hydrodynamic observations and simulations of munition in the sea,” a subproject of the collaborative project “Environmental monitoring for the delaboration of munitions in the sea” (Grant No. #03F0747C).This work was funded by the Deutsche Forschungsgemeinschaft
(DFG) (projects JU367/15-1, JU367/16-1 to KJ and LA1466/8-
1 to ML). DH was supported by the European Regional Development Fund and the Estonian Research Council Mobilitas
Plus Top Researcher grant “MOBTT24.” UG was supported by
the BMBF project “Hydrodynamic observations and simulations
of munition in the sea,” a subproject of the collaborative project
“Environmental monitoring for the delaboration of munitions in
the sea” (Grant No. #03F0747C)
Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES
We present measurements of exclusive ensuremathπ+,0 and η production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of π+ and π0 , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of Δ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp → pp η , since controversial data exist at 2.0GeV; we find \ensuremathσ=0.142±0.022 mb. Using the dielectron channels, the π0 and η Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions
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