The outer epithelial layer of zebrafish retinae contains a crystalline array of cone photoreceptors, called the cone mosaic. As this mosaic grows by mitotic addition of new photoreceptors at the rim of the hemispheric retina, topological defects, called “Y-Junctions”, form to maintain approximately constant cell spacing. The generation of topological defects due to growth on a curved surface is a distinct feature of the cone mosaic not seen in other well-studied biological patterns like the R8 photoreceptor array in the _ Drosophila compound eye. Since defects can provide insight into cell-cell interactions responsible for pattern formation, here we characterize the arrangement of cones in individual Y-Junction cores (see Set of images for Figures 1 and 2 and 6 and Supplementary Figure 7) as well as the spatial distribution of Y-junctions across entire retinae (see Dataset for analyzing spatial distribution of Y-junctions in flat-mounted retinae). We find that for individual Y-junctions, the distribution of cones near the core corresponds closely to structures observed in physical crystals (see Set of images for Figures 1 and 2 and 6 and Supplementary Figure 7). In addition, Y-Junctions are organized into lines, called grain boundaries, from the retinal center to the periphery (see Dataset for analyzing spatial distribution of Y-junctions in flat-mounted retinae and Dataset for measuring tendency of Y-junctions to line up into grain boundaries during incorporation into retinae). In physical crystals, regardless of the initial distribution of defects, defects can coalesce into grain boundaries via the mobility of individual particles. By imaging in live fish, we demonstrate that grain boundaries in the cone mosaic instead appear during initial mosaic formation, without requiring defect motion (see Dataset for measuring tendency of Y-junctions to line up into grain boundaries during incorporation into retinae and Dataset for analyzing Y-junction motion in live fish retinae). Motivated by this observation, we show that a computational model of repulsive cell-cell interactions generates a mosaic with grain boundaries (see Code and example simulations of phase-field crystal model (for cone mosaic formation)). In contrast to paradigmatic models of fate specification in mostly motionless cell packings (see Code and accompanying input data for simulating lateral inhibition on motionless cell packing), this finding emphasizes the role of cell motion, guided by cell-cell interactions during differentiation, in forming biological crystals. Such a route to the formation of regular patterns may be especially valuable in situations, like growth on a curved surface, where the resulting long-ranged, elastic, effective interactions between defects can help to group them into grain boundaries.
This collection concerns the CRIMSON (CardiovasculaR Integrated Modelling and SimulatiON) software environment. CRIMSON provides a powerful, customizable and user-friendly system for performing three-dimensional and reduced-order computational haemodynamics studies via a pipeline which involves: 1) segmenting vascular structures from medical images; 2) constructing analytic arterial and venous geometric models; 3) performing finite element mesh generation; 4) designing, and 5) applying boundary conditions; 6) running incompressible Navier-Stokes simulations of blood flow with fluid-structure interaction capabilities; and 7) post-processing and visualizing the results, including velocity, pressure and wall shear stress fields. , The minimum specifications to run CRIMSON are: Any AMD64 CPU (note: Intel Core i series are AMD64), Windows (only tested on Windows 10 but might work on Windows 7), 8 GB of RAM
, If you are running non-trivial models you will want to have: Quad core CPU or higher, Solid state drive for storing data, Windows, 16 GB of RAM, Dedicated discrete GPU for rendering models.
, and Software in this collection is a snapshot; please visit https://github.com/carthurs/CRIMSONGUI & www.crimson.software for more general information and the most up to date version of the software.
CRIMSON: An Open-Source Software Framework for Cardiovascular Integrated Modelling and Simulation C.J. Arthurs, R. Khlebnikov, A. Melville, et al. bioRxiv 2020.10.14.339960; doi: https://doi.org/10.1101/2020.10.14.339960
This is a collection of photos of villages located primarily in Central Mali. These photos are primarily of Dogon villages, but there are village photos of other nearby ethnicities, including Bangande, Fulbe, Tuareg, Songay, and Bozo.These photos were taken to document the villages Professor Jeffrey Heath worked in and people he worked with while documenting languages throughout the region. For interactive geographical maps involving these villages see: http://dogonlanguages.org/geography.cfm.
Short documentary videos of practical activities and cultural events of Dogon, Fulbe, Songhay, and Bangande ethnic groups of eastern Central Mali. The videos were byproducts of linguistic research on the local language. They are presented here in three formats: wmv, avi, and either qt or mov. See the "readme" files in each work for a summary of the videos in it. and The footage was shot with various digital cameras. The oldest videos (2010 and one or two from 2011) were edited using iMovie. The later videos were edited using AVS editing software. Several of the 2010 videos, referred to as "compilations," are simple sequences of short clips that combine to illustrate a complex activity such as extracting oil from nuts. The later videos are in more flowing documentary form with overlaid titles in English. In some cases, vocabulary from the relevant native language is included in the titles.
This is a collection of mostly short documentary-style videos related to linguistic fieldwork in southwestern Burkina Faso. The initial batch consists of videos produced in 2023, and others will be added. Versions of some of these videos overdubbed in native languages will also be produced for local consumption in Burkina. Most of the videos document everyday practical activities; some also feature useful native plants and insects. This collection is parallel to collections of videos from neighboring Mali: see "Central Mali documentary videos" (with documentaries produced up to 2018) and "Mali documentary videos from 2023 on" for the newer ones. A small collection from north-central Côte d'Ivoire is also in the works. Within each collection, the videos are organized into "works" based on the general type of activity documented.