In order to better facilitate scaling up of classroom innovations, two complementary strategies have often been discussed. The community-based strategy emphasizes the necessity for professional ...learning communities and their embedding in institutional settings. The material-based strategy starts from well-designed teaching materials, which are considered catalysts for bringing teaching approaches to many classrooms. The implementation project reported on in this study systematically combines both strategies and takes a third strategy into account: the systemic strategy of addressing higher levels of the school system, such as the school and district levels. The goal of the project is to help teachers to better support low-achieving students at the beginning of German secondary schools (grades 5 and 6). The results of the accompanying research in a quasi-experimental study, reported in this article, show that a combination of strategies can be effective: the participating low-achieving students had higher learning gains than a control group did. The deeper analysis provides insights into the complexities of the interplay of community aspects, institutional backgrounds, and the power of substantial teaching materials.
Purpose
Traditional phase‐contrast MRI is affected by displacement artifacts caused by non‐synchronized spatial‐ and velocity‐encoding time points. The resulting inaccurate velocity maps can affect ...the accuracy of derived hemodynamic parameters. This study proposes and characterizes a 3D radial phase‐contrast UTE (PC‐UTE) sequence to reduce displacement artifacts. Furthermore, it investigates the displacement of a standard Cartesian flow sequence by utilizing a displacement‐free synchronized‐single‐point‐imaging MR sequence (SYNC‐SPI) that requires clinically prohibitively long acquisition times.
Methods
3D flow data was acquired at 3T at three different constant flow rates and varying spatial resolutions in a stenotic aorta phantom using the proposed PC‐UTE, a Cartesian flow sequence, and a SYNC‐SPI sequence as reference. Expected displacement artifacts were calculated from gradient timing waveforms and compared to displacement values measured in the in vitro flow experiments.
Results
The PC‐UTE sequence reduces displacement and intravoxel dephasing, leading to decreased geometric distortions and signal cancellations in magnitude images, and more spatially accurate velocity quantification compared to the Cartesian flow acquisitions; errors increase with velocity and higher spatial resolution.
Conclusion
PC‐UTE MRI can measure velocity vector fields with greater accuracy than Cartesian acquisitions (although pulsatile fields were not studied) and shorter scan times than SYNC‐SPI. As such, this approach is superior to traditional Cartesian 3D and 4D flow MRI when spatial misrepresentations cannot be tolerated, for example, when computational fluid dynamics simulations are compared to or combined with in vitro or in vivo measurements, or regional parameters such as wall shear stress are of interest.
A new species of the whip spider genus Sarax Simon, 1892 from Cebu Island in the Philippines is described: Sarax huberi sp. nov. With the description of this species, the diversity of the genus is ...increased to three species in the Philippines. Some additional data on their natural environment and their specific habitat are presented and compared with sibling species. The synonymization of Sarax mediterraneus Delle Cave, 1986 with Sarax buxtoni (Gravely, 1915) is carried out.
We present data and remarks on the history and contents of the whip spider collection housed in the Natural History Museum of Vienna, Austria. The collection comprises a total of 167 specimens from 4 ...families, 10 genera and 27 species. It includes types of four species: Charinus ioanniticus (Kritscher, 1959), Damon brachialis Weygoldt, 1999, Phrynus parvulus (Pocock, 1902) and Paraphrynus mexicanus (Bilimek, 1867). Short notes on interesting objects and former curators are provided as well as an appendix with a list of species kept alive by Michael Seiter.
Recently, we have described a panel of metastasis-associated antigens in the rat, i.e., of molecules expressed on metastasizing, but not on nonmetastasizing tumor lines. One of these molecules, ...recognized by the monoclonal antibody D6.1 and named accordingly D6.1A, was found to be abundantly expressed predominantly on mesenchyme-derived cells. The DNA of the antigen has been isolated and cloned. Surprisingly, the gene product proved to interfere strongly with coagulation. The 1.182-kb cDNA codes for a 235-amino acid long molecule with a 74.2% homology in the nucleotide and a 70% homology in the amino acid sequence to CO-029, a human tumor-associated molecule. According to the distribution of hydrophobic and hydrophilic amino acids, D6.1A belongs to the tetraspanin superfamily. Western blotting of D6.1A-positive metastasizing tumor lines revealed that the D6.1A, like many tetraspanin molecules, is linked to further membrane molecules, one of which could be identified as α6β1 integrin. Transfection of a low-metastasizing tumor cell line with D6.1A cDNA resulted in increased metastatic potential and provided a clue as to the functional role of D6.1A. We noted massive bleeding around the metastases and, possibly as a consequence, local infarctions predominantly in the mesenteric region and all signs of a consumption coagulopathy. By application of the D6.1 antibody the coagulopathy was counterregulated, though not prevented. It has been known for many years that tumor growth and progression is frequently accompanied by thrombotic disorders. Our data suggest that the phenomenon could well be associated with the expression of tetraspanin molecules.
We have described recently a panel of metastasis-associated antigens expressed on a rat pancreatic tumor. One of these molecules, recognized by the monoclonal antibody C4.4 and named accordingly ...C4.4A, was under physiological conditions expressed only in the gravid uterus and on epithelial of the upper gastrointestinal tract. The cDNA of the antigen has been isolated and cloned. The 1,637 b cDNA codes for a 352 amino acid long glycosylphosphatidyl-inositol (GP) anchored molecule, whose molecular weight varies in different cells between 94-98 kD according to the degree of N- and O-glycosylation. Data base searches have revealed a low degree of homology to the receptor for the plasminogen activator (uPAR). After intrafootpad and intravenous application of C4.4A transfected and mock-transfected tumor cells, an increased number of lung nodules was detected with the former, whereby the individual metastatic nodules amalgamated without any encapsulation of the tumor tissue. Furthermore, C4.4A is involved in adhesion to laminin and, although transfection of a non-metastasizing tumor line with the molecule was not sufficient, constitutively C4.4A-positive tumor cells penetrated through matrigel. This process could be completely prevented by C4.4. Finally, we could demonstrate that uPA, albeit weakly, bound to the C4.4A molecule. In view of the observed influence of C4.4A on metastasis formation and matrix penetration it is tempting to speculate that this newly described metastasis-associated molecule may exert functional activity similar to the uPAR, i.e. via activation of matrix degrading enzymes. By the very restricted expression of the molecule in the adult organism, modulation of C4.4A could well be of therapeutic interest.
Modeling languages such as SysML provide various description means for a precise specification of the desired system. As a system model typically uses multiple diagram types focusing on different ...aspects, it is crucial to keep them consistent to each other. In this paper, we propose a verification methodology which ensures the consistency between activity diagrams as blueprints for the implementation and their contracts from a block definition diagram. For this purpose, activity diagrams are transformed to OCL constraints that can be checked against pre- and postconditions. The proposed approach is evaluated in a case study based on an industrial specification.
Because the lack of some adhesion molecules induced by site-directed mutagenesis has been described to be lethal, whereas the lack of others apparently has no effect, we were interested in seeing ...whether the developing organism might gradually adapt to the absence of adhesion molecules. Therefore, we chose a form of transient interference by i.v. injection of antibody into pregnant rats. As a model, we selected CD44, which has been reported to play a key role during embryogenesis. Rats received either an antibody recognizing an epitope on the CD44 standard isoform (CD44s) or on exon v6 (CD44v6). In the presence of anti-CD44s, delivery was frequently delayed, and intrauterine abortions were often observed. The fetuses were smaller, particularly the anlage of the hair follicle of the whisker, and the formation of alveoli in the lung, of the tubular system of the kidney, and of villi in the gut was delayed. The development of fetuses receiving anti-CD44v6 was hampered until days 16-18 of gestation. Immunodetection revealed a weaker expression of the target molecules at the implantation site and the complete absence of CD44s and CD44v6 expression in fetal tissue until day 12. During the late stages of gestation, the expression pattern of CD44 resembled that of 2-3-day-younger fetuses of untreated rats. Interestingly, degradation of hyaluronate was also delayed, particularly in the kidney. Thus, the diaplacental antibody passage was very efficient and should make it possible to obtain a clearly defined and differentiated concept of the requirements for the CD44 molecule during ontogeny and also for fail-safe mechanisms. Both experiences may be missed in the knockout proper.
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