Sure, some of the binary math rooted in doubling in various African societies can be found elsehwere in the world, but what struck me the most about Eglash's work is his claim for an African origin of 'geomancy' or divination that reached medieval...
The signaling system is a fundamental part of the cell, as it regulates essential functions including growth, differentiation, protein synthesis, and apoptosis. A malfunction in this subsystem can disrupt the cell significantly, and is believed to be involved in certain diseases, with cancer being a very important example. While the information available about intracellular signaling networks is constantly growing, and the network topology is actively being analyzed, the modeling of the dynamics of such a system faces difficulties due to the vast number of parameters, which can prove hard to estimate correctly. As the functioning of the signaling system depends on the parameters in a complex way, being able to make general statements based solely on the network topology could be especially appealing. We study a general kinetic model of the signaling system, giving results for the asymptotic behavior of the system in the case of a network with only activatory interactions. We also investigate the possible generalization of our results for the case of a more general model including inhibitory interactions too. We find that feedback cycles made up entirely of activatory interactions (which we call dynamically positive) are especially important, as their properties determine whether the system has a stable signal-off state, which is desirable in many situations to avoid autoactivation due to a noisy environment. To test our results, we investigate the network topology in the Signalink database, and find that the human signaling network indeed has only significantly few dynamically positive cycles, which agrees well with our theoretical arguments.
A new theory and simulations have been developed that describe a spinning optical soliton whose propagation spontaneously excites knotted and linked optical vortices. The nonlinear phase of the self-trapped light beam breaks the wave front into a sequence of optical vortex loops around the soliton, which, through the soliton's orbital angular momentum and spatial twist, tangle on propagation to form links and knots. Similar spontaneous knot topology should be a universal feature of waves whose phase front is twisted and nonlinearly modulated, including superfluids and trapped matter waves.
Modular organization in biological networks has been suggested as a natural mechanism by which a cell coordinates its metabolic strategies for evolving and responding to environmental perturbations. To understand how this occurs, there is a need for developing computational schemes that contribute to integration of genomic-scale information and assist investigators in formulating biological hypotheses in a quantitative and systematic fashion. In this work, we combined metabolome data and constraint-based modeling to elucidate the relationships among structural modules, functional organization, and the optimal metabolic phenotype of Rhizobium etli, a bacterium that fixes nitrogen in symbiosis with Phaseolus vulgaris. To experimentally characterize the metabolic phenotype of this microorganism, we obtained the metabolic profile of 220 metabolites at two physiological stages: under free-living conditions, and during nitrogen fixation with P. vulgaris. By integrating these data into a constraint-based model, we built a refined computational platform with the capability to survey the metabolic activity underlying nitrogen fixation in R. etli. Topological analysis of the metabolic reconstruction led us to identify modular structures with functional activities. Consistent with modular activity in metabolism, we found that most of the metabolites experimentally detected in each module simultaneously increased their relative abundances during nitrogen fixation. In this work, we explore the relationships among topology, biological function, and optimal activity in the metabolism of R. etli through an integrative analysis based on modeling and metabolome data. Our findings suggest that the metabolic activity during nitrogen fixation is supported by interacting structural modules that correlate with three functional classifications: nucleic acids, peptides, and lipids. More fundamentally, we supply evidence that such modular organization during functional nitrogen fixation is a robust property under different environmental conditions.
Resendis-Antonio O, Hernández M, Mora Y, Encarnación S. (2012). PLoS Comput Biol. 2012 Oct;8(10):e1002720.
Winton was founded by David Harding in 1997 with an absolute commitment to employing advanced mathematical, statistical and computational techniques to develop systematic, quantitative, trading strategies for global futures and equity markets, a...
"The connection between mathematics and art goes back thousands of years. Mathematics has been used in the design of Gothic cathedrals, Rose windows, oriental rugs, mosaics and tilings. Geometric forms were fundamental to the cubists and many abstract expressionists, and award-winning sculptors have used topology as the basis for their pieces. Dutch artist M.C. Escher represented infinity, Möbius bands, tessellations, deformations, reflections, Platonic solids, spirals, symmetry, and the hyperbolic plane in his works.
"Mathematicians and artists continue to create stunning works in all media and to explore the visualization of mathematics--origami, computer-generated landscapes, tesselations, fractals, anamorphic art, and more."
A geometric enigma, a convoluted mind-bender dropped upon us from the wonderful extra-dimensional realm of topology, the Klein Bottle is perhaps even popular with artists and architects than the ubiquitous Moebius strip. In fact, the Klein Bottle is what happens when you merge two Moebius Strips together: the resulting shape will still have only one side - with its inside and outside merging into one!
The concept of topology isn’t something that every spatially enabled person fully understands. That is OK, because I too had to learn (and relearn) how spatial topology works over the years, especially early on back in the ArcView 3.X days. I think this experience is fairly typical of someone who uses GIS. If one is taking a GIS course or a course that uses GIS it is not very often that the concept of spatial topology is covered in-depth or at all. Spatial topology also may not be something that people are overly concerned about during their day-to-day workflow, meaning they may let their geospatial topology skills slide from time to time. As a public service here is a basic overview of geospatial topology.
First question: What is topology?
You have probably heard the term topology before, whether it was in a GIS course where the instruction lightly glazed over the topic, or in a geometry /mathematics course.
Technically speaking, topology is a field of mathematics/geometry/graph theory, that studies how the properties of a shape remain under a number of different transformations, like bending, stretching, or twisting. The field of topology is well established within mathematics and far more complicated than I wish to get in this post.
IDS: An intrusion detection system can be software-based or hardware-based and is used to monitor network packets or systems for malicious activity and do a specific action if such activity is detected.
Boing Boing Profile of math-inspired 3D printing sculptor Bathsheba Grossman Boing Boing I was originally a math major interested in geometry and topology, when as a college senior I met the remarkable sculptor Erwin Hauer, and suddenly it was...