Dynamically forced cells of a viscoelastic fluid over an array of rollers

Our fluid dynamics video shows the response of a layer of viscoelastic fluid to an array of four-roll mills steadily rotating underneath. When the relaxation time of the fluid is sufficiently long, the fluid divides into "cells" with a convex free surface above the site of each roller. This is reminiscent of the rod-climbing effect. On this relaxation time-scale, the flow also transitions from being initially Newtonian-like to one where the fluids' elasticity plays a dynamical role: The fluid cells oscillate with regularity in position and shape on a timescale much longer than the relaxation time. As the relaxation time is further increased, the cells become less localized to the underlying rollers, and their now irregular oscillations reflect the presence of many frequencies

Lattices of hydrodynamically interacting flapping swimmers

Fish schools and bird flocks exhibit complex collective dynamics whose self-organization principles are largely unknown. The influence of hydrodynamics on such collectives has been relatively unexplored theoretically, in part due to the difficulty in modeling the temporally long-lived hydrodynamic interactions between many dynamic bodies. We address this through a novel discrete-time dynamical system (iterated map) that describes the hydrodynamic interactions between flapping swimmers arranged in one- and two-dimensional lattice formations. Our 1D results exhibit good agreement with previously published experimental data, in particular predicting the bistability of schooling states and new instabilities that can be probed in experimental settings. For 2D lattices, we determine the formations for which swimmers optimally benefit from hydrodynamic interactions. We thus obtain the following hierarchy: while a side-by-side single-row "phalanx" formation offers a small improvement over a solitary swimmer, 1D in-line and 2D rectangular lattice formations exhibit substantial improvements, with the 2D diamond lattice offering the largest hydrodynamic benefit. Generally, our self-consistent modeling framework may be broadly applicable to active systems in which the collective dynamics is primarily driven by a fluid-mediated memory

The milliped family Tingupidae (Chordeumatida) on Kodiak Island, Alaska, USA, a geographically remote record of indigenous Diplopoda

With documentation of an unidentifiable adult female and juvenile Tingupidae (Chordeumatida), Kodiak Island, Alaska, becomes the westernmost indigenous diplopod locality in North America including continental islands. The northernmost and most proximate locality, Yakutat, lies ca. 935 mi (1,496 km) to the eastnortheast, while Haines, the type locality of Tingupa tlingitorum Shear and Shelley, some 1,196 mi (1,914 km) in this direction, is the most proximate familial site. Kodiak is also one of the most remote indigenous milliped localities in the Pacific, the most proximate ones to the west and south, Kamchatka, Russia, and the Hawaiian Islands, United States, being over 3,300 mi (5, 280 km) distant. Tingupidae is recorded for the first time from Canada excluding the Queen Charlotte Islands, and geographically remote, ostensibly indigenous records from the North Pacific Ocean and environs are tabulated

The development of an analysis tool to categorize

There has been much discussion within the areas of media effects and journalism that has been focused on the issue of framing. Framing occurs when journalists employ various tactics in order to connect to their audience and enhance the understanding of a certain topic or event. These tactics include using particular grammar and vocabulary within the text that sets the tone for the story. The tactics can also include choosing particular visual imagery to engage the reader, although this is rarely discussed within media research. Graphic design research, which includes the study of iconography, semiotics and social semiotics, has determined that images carry vast amounts of information and meaning. This suggests that images can also lead to the promotion of a particular frame. When the frame of the image does not support the frame of the text the audience can receive a confusing or even contradicting message. This study combines media-framing research with that of graphic design in order to determine ways that visual framing can best be identified and analyzed. The result is a categorizing tool that informs the journalist how an image can play a part in the framing of a subject and emphasizes the importance of the decision concerning which image should accompany the text. This categorizing tool, which is proposed in the form of a brochure, guides the journalist through the process of identifying and rating the presence of visual framing components in order to determine whether or not an image is appropriate for the text. This process would be valuable when choosing images prior to print, or as a way of reflecting on how images have been used in past coverage