A Case of Lodgment of a Breech-Pin in the Brain; Recovery:

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Spin fluctuations and superconductivity in a 3D tight-binding model for BaFe2As2

Despite the wealth of experimental data on the Fe-pnictide compounds of the KFe2As2-type, K = Ba, Ca, or Sr, the main theoretical work based on multiorbital tight-binding models has been restricted so far to the study of the related 1111 compounds. This can be ascribed to the more three dimensional electronic structure found by ab initio calculations for the 122 materials, making this system less amenable to model development. In addition, the more complicated Brillouin zone (BZ) of the body-centered tetragonal symmetry does not allow a straightforward unfolding of the electronic band structure into an effective 1Fe/unit cell BZ. Here we present an effective 5-orbital tight-binding fit of the full DFT band structure for BaFeAs including the kz dispersions. We compare the 5-orbital spin fluctuation model to one previously studied for LaOFeAs and calculate the RPA enhanced susceptibility. Using the fluctuation exchange approximation to determine the leading pairing instability, we then examine the differences between a strictly two dimensional model calculation over a single kz cut of the BZ and a completely three dimensional approach. We find pairing states quite similar to the 1111 materials, with generic quasi-isotropic pairing on the hole sheets and nodal states on the electron sheets at kz = 0 which however are gapped as the system is hole doped. On the other hand, a substantial kz dependence of the order parameter remains, with most of the pairing strength deriving from processes near kz = pi. These states exhibit a tendency for an enhanced anisotropy on the hole sheets and a reduced anisotropy on the electron sheets near the top of the BZ.Comment: 12 pages, 15 figure

Session E8: Efficiency Measurements as Tool in Evaluating Fishways

Abstract: The awareness of the importance of free fish migration in the Netherlands is reflected in the increasing number of fishways that has been built in the past decade. The intention is that all the bottlenecks will be solved before 2027. Equally important as the realization of fishways, is the evaluation of the design. In other words, are all species and size classes that want to pass, truly able to pass the structure. The challenge in this type of research is to avoid interference of the measuring tools with the fish migrants. The conventional monitoring fyke, does not meet this requirement. Migration is obstructed and the gear is highly selective for small fish. Emerging electronic techniques offer this opportunity and makes it possible to watch fish migration behaviour on the road through the fishway. The use of a resistivity Fish Counter will be illustrated by means of a case study. The counter detects the swimming direction and size of the passing fish. Species identification is achieved by the application of a camera, triggered by the passing fish. The placement of a counter station at both sides of the fishway, gives the unique opportunity to determine the efficiency in terms of the ratio between the number of fish entering the downstream side and the number of fish exiting at the upstream side. An example will be given of a fishway that originally was reviewed as a good functioning construction. However, measurements of the efficiency showed that only a small part of the fish community was able to pass. The results also uncovered the weak spot in the design. This was not regarded as a failure, but as an opportunity to make use of the hidden potential of this fishway. It also contributed to the improvement of this type of design in general

CV-7A Transport Aircraft Modification to Provide an Augmentor-Wing Jet STOL Research Aircraft. Volume 1 - Design Study

Design study data for CV-7A transport aircraft modification to provide augmentor wing jet STOL research aircraf