Discrete exterior calculus (DEC) for the surface Navier-Stokes equation

We consider a numerical approach for the incompressible surface Navier-Stokes equation. The approach is based on the covariant form and uses discrete exterior calculus (DEC) in space and a semi-implicit discretization in time. The discretization is described in detail and related to finite difference schemes on staggered grids in flat space for which we demonstrate second order convergence. We compare computational results with a vorticity-stream function approach for surfaces with genus 0 and demonstrate the interplay between topology, geometry and flow properties. Our discretization also allows to handle harmonic vector fields, which we demonstrate on a torus.Comment: 21 pages, 9 figure

Architectural geometry

Around 2005 it became apparent in the geometry processing community that freeform architecture contains many problems of a geometric nature to be solved, and many opportunities for optimization which however require geometric understanding. This area of research, which has been called architectural geometry, meanwhile contains a great wealth of individual contributions which are relevant in various fields. For mathematicians, the relation to discrete differential geometry is significant, in particular the integrable system viewpoint. Besides, new application contexts have become available for quite some old-established concepts. Regarding graphics and geometry processing, architectural geometry yields interesting new questions but also new objects, e.g. replacing meshes by other combinatorial arrangements. Numerical optimization plays a major role but in itself would be powerless without geometric understanding. Summing up, architectural geometry has become a rewarding field of study. We here survey the main directions which have been pursued, we show real projects where geometric considerations have played a role, and we outline open problems which we think are significant for the future development of both theory and practice of architectural geometry

Acute Liver Rejection in a Multiple Myeloma Patient Treated with Lenalidomide

Herein we present a patient that underwent a liver transplant due to primary biliary cholangitis (PBC) and after 9 years developed multiple myeloma. Following the cessation of mycophenolate mofetil and 2 weeks after lenalidomide treatment was started, the patient experienced acute cellular rejection. The patient recovered after treatment with corticosteroids, resumption of mycophenolate mofetil, and cessation of lenalidomide. Lenalidomide-associated allograft rejection has been reported in other organs. However, this is the first case report of liver rejection induced by lenalidomide

Position-based tensegrity design

© 2017 Association for Computing Machinery. We propose a novel framework for the computational design of tensegrity structures, which are constructions made of struts and cables, held rigid by continuous tension between the elements. Tensegrities are known to be difficult to design-existing design methods are often restricted to using symmetric or templated configurations, limiting the design space to simple constructions. We introduce an algorithm to automatically create free-form stable tensegrity designs that satisfy both fabrication and geometric constraints, and faithfully approximate input geometric shapes. Our approach sidesteps the usual force-based approach in favor of a geometric optimization on the positions of the elements. Equipped with this formulation, we provide a design framework to explore the highly constrained space of tensegrity structures. We validate our method with simulations and real-world constructions

Polyhedral Patterns

We study the design and optimization of polyhedral patterns, which are patterns of planar polygonal faces on freeform surfaces. Working with polyhedral patterns is desirable in architectural geometry and industrial design. However, the classical tiling patterns on the plane must take on various shapes in order to faithfully and feasibly approximate curved surfaces. We define and analyze the deformations these tiles must undertake to account for curvature, and discover the symmetries that remain invariant under such deformations. We propose a novel method to regularize polyhedral patterns while maintaining these symmetries into a plethora of aesthetic and feasible patterns

Efeito do ácido ascórbico e da hidrocortisona na cicatrização anastomótica intestinal

OBJETIVO: Comparar a resistência cicatricial de anastomoses jejunais em ratos, submetidos à administração de vitamina C e de hidrocortisona, em distintos períodos pós-operatórios. MÉTODOS: Foram estudados 40 ratos Wistar, submetidos à secção e subsequente anastomose término-terminal de segmento jejunal, a 10 cm da flexura duodenojejunal. Os animais foram distribuídos em quatro grupos (n=10): Grupo I - controle; Grupo II - administração de vitamina C oral 100 mg/kg; Grupo III - administração de hidrocortisona intraperitoneal 10 mg/kg; Grupo IV - administração de vitamina C mais hidrocortisona nas doses e vias de administração acima. Avaliaram-se as pressões de ruptura anastomótica no 5º e 21º dias do pós-operatório. RESULTADOS: Os ratos que receberam vitamina C isolada ou associada a hidrocortisona tenderam a ter pressão de ruptura maior do que os demais grupos, tanto no 5º quanto no 21º dia pós-operatório. CONCLUSÃO: A vitamina C contribui para aumentar a resistência das anastomoses jejunais dos ratos durante os primeiros cinco dias do pós-operatório. A resistência das anastomoses jejunais murinas foi pouco influenciada pela administração de corticóide intraperitoneal