Self-similarity in a Boundary-layer Flow over a Dynamic Boundary: Flow of Air Induced by a Falling Soap Film

A wide range of dynamical phenomena in nature are self-similar. This remarkable property entails that scaled versions of a phenomenon conform onto themselves. It not only affords simplified mathematical analysis but also reveals the physical underpinnings of the phenomenon. In fluid flows, a textbook example of such phenomena is the boundary-layer flow over a rigid boundary---the Blasius boundary layer flow. In this thesis, we experimentally and theoretically study self-similarity in boundary-layer flow over a dynamic boundary, wherein the flow and the boundary are dynamically coupled. Our experimental setup is a soap-film channel, which is essentially a soapy waterfall---a planar film of soap-water solution falling under gravity. This setup has long been used to study quasi-two-dimensional flows in a laboratory setting. Unlike previous experiments, however, where the focus is on the flow in the film, we train attention on what surrounds the film: air. The falling film drags the surrounding air, inducing flow in a thin layer of air adjacent to the film. This flowing air, in turn, resists the motion of the falling film; thus, the film-air interface is a dynamic boundary. We measure the velocity profile of the airflow in the boundary-layer of this interface using super-resolution Particle Image Velocimetry. (To our knowledge, these are the first experiments to measure airflow induced by a soap film.) The downstream evolution of the air velocity profile manifests self-similarity, which we analyze using the framework of boundary-layer theory. Surprisingly, we find that the conditions of self-similarity of the airflow also shed light on the downstream evolution of the film. Beyond air-film interaction, our findings may bear on a broader class of flows over dynamic boundaries, e.g. ocean-air interaction.Okinawa Institute of Science and Technology Graduate Universit

Aberrant X chromosomal rearrangement through multi‐step template switching during sister chromatid formation in a patient with severe hemophilia A

Abstract Background Hemophilia A (HA) is an X‐linked recessive bleeding disorder caused by pathogenic variants of the coagulation factor VIII gene (F8). Half of the patients with severe HA have a recurrent inversion in the X chromosome, that is, F8 intron 22 or intron 1 inversion. Here, we characterized an abnormal F8 due to atypical complex X chromosome rearrangements in a Japanese patient with severe HA. Methods Recurrent F8 inversions were tested with inverse shifting‐PCR. The genomic structure was investigated using PCR‐based direct sequencing or quantitative PCR. Results The proband's X chromosome had a 119.5 kb insertion, a reverse duplex of an extragenic sequence on the F8 telomere region into the F8 intron 1 with two breakpoints. The telomeric breakpoint was a joining from the F8 intron 1 to the inverted FUNDC2 via a two‐base microhomology, and the centromeric breakpoint was a recombination between F8 intron 1 homologous sequences. The rearrangement mechanism was suggested as a multi‐step rearrangement with template switching such as fork stalling and template switching (FoSTeS)/microhomology‐mediated break‐induced replication (MMBIR) and/or homologous sequence‐associated recombination during a sister chromatid formation. Conclusion We identified the aberrant X chromosome with a split F8 due to a multi‐step rearrangement in a patient with severe HA

Mixed epithelial and stromal tumor of the kidney with long-term imaging follow-up

Mixed epithelial and stromal tumor (MEST) of the kidney is a rare benign tumor with malignant potential, and is characterized by epithelial and stromal proliferation with a variety of cellularity and growth pattern. MEST of the kidney is often depicted as a well-defined, solid mass with a cystic component. However, due to the rarity of the disease, there are no reports of its progression in serial imaging examinations. This report presents the case of a 68-year-old woman with MEST who was followed for 13 years by computed tomography (CT). To the best of our knowledge, this is the first report of image findings of MEST of the kidney over a follow-up period longer than 10 years