Compaction of Rods: Relaxation and Ordering in Vibrated, Anisotropic Granular Material

We report on experiments to measure the temporal and spatial evolution of packing arrangements of anisotropic, cylindrical granular material, using high-resolution capacitive monitoring. In these experiments, the particle configurations start from an initially disordered, low-packing-fraction state and under vertical vibrations evolve to a dense, highly ordered, nematic state in which the long particle axes align with the vertical tube walls. We find that the orientational ordering process is reflected in a characteristic, steep rise in the local packing fraction. At any given height inside the packing, the ordering is initiated at the container walls and proceeds inward. We explore the evolution of the local as well as the height-averaged packing fraction as a function of vibration parameters and compare our results to relaxation experiments conducted on spherically shaped granular materials.Comment: 9 pages incl. 7 figure

Possible origins of macroscopic left-right asymmetry in organisms

I consider the microscopic mechanisms by which a particular left-right (L/R) asymmetry is generated at the organism level from the microscopic handedness of cytoskeletal molecules. In light of a fundamental symmetry principle, the typical pattern-formation mechanisms of diffusion plus regulation cannot implement the "right-hand rule"; at the microscopic level, the cell's cytoskeleton of chiral filaments seems always to be involved, usually in collective states driven by polymerization forces or molecular motors. It seems particularly easy for handedness to emerge in a shear or rotation in the background of an effectively two-dimensional system, such as the cell membrane or a layer of cells, as this requires no pre-existing axis apart from the layer normal. I detail a scenario involving actin/myosin layers in snails and in C. elegans, and also one about the microtubule layer in plant cells. I also survey the other examples that I am aware of, such as the emergence of handedness such as the emergence of handedness in neurons, in eukaryote cell motility, and in non-flagellated bacteria.Comment: 42 pages, 6 figures, resubmitted to J. Stat. Phys. special issue. Major rewrite, rearranged sections/subsections, new Fig 3 + 6, new physics in Sec 2.4 and 3.4.1, added Sec 5 and subsections of Sec

OBSTRUCTIVE ILEOSTOMY IN TREATMENT OF COMPLEX LARGE INTESTINE FISTULA

The causes of the development of complicated large intestine fistulas can be: tactical and technical errors allowed in both surgical intervention and in the management of the postoperative period, as well as the presence in the abdominal cavity at the time of the pyoinflammatory process. The article presents two clinical cases of successful treatment of complex large intestine fistulas of the colon according to the author’s method. The authors developed a variant of obstructive ileostomy for the treatment of complex large intestine fistulas. A distinctive feature of the method is the complete exclusion of intestinal contents from the passage through the critical zone, which allows achieving positive results in the treatment of complex fistulas of the large intestine and colonic insufficiency. When choosing a method of treatment, in particular, an operational benefit in patients with intestinal fistulas should take into account not only the localization of the process but also its prevalence, the presence of complications. An important factor in the choice of tactics is the age of the patient, as well as the presence of concomitant diseases. The effectiveness of treatment, including surgical, depends on early diagnosis and the application of rational tactics of subsequent intervention. The application of a modified obstructive ileostomy can be used in patients with complex large intestine fistulas

Classification of indicators characterizing properties object of armored vehicles

В статье представлена развитая классификация показателей тактико-технических характеристик объектов БТТ, что позволило обобщить более 150 показателей ТТХ, характеризующих свойства этого класса военной техники.У статті представлена розвинена класифікація показників тактико-технічних характеристик об’єктів бронетанкової техніки, що дозволило узагальнити більше 150 показників ТТХ, що характеризують властивості цього класу військової техніки.The article presents a classification of indicators developed tactical and technical characteristics of the armor pieces that helped to generalize more than 150 indicators of performance characteristics that characterize the properties of this class of military equipment

Nematic Ordering Pattern Formation in the Process of Self-Organization of Microtubules in a Gravitational Field

Papaseit et al. (Proc. Natl. Acad. Sci. U.S.A. 97, 8364, 2000) showed the decisive role of gravity in the formation of patterns by assemblies of microtubules in vitro. By virtue of a functional scaling, the free energy for MT systems in a gravitational field was constructed. The influence of the gravitational field on MT’s self-organization process, that can lead to the isotropic to nematic phase transition, is the focus of this paper. A coupling of a concentration gradient with orientational order characteristic of nematic ordering pattern formation is the new feature emerging in the presence of gravity. The concentration range corresponding to a phase coexistence region increases with increasing g or MT concentration. Gravity facilitates the isotropic to nematic phase transition leading to a significantly broader transition region. The phase transition represents the interplay between the growth in the isotropic phase and the precipitation into the nematic phase. We also present and discuss the numerical results obtained for local MT concentration change with the height of the vessel, order parameter and phase transition properties