The developmental hourglass model has been used to describe the morphological transitions of related species throughout embryogenesis. Recently, quantifiable approaches combining transcriptomic and evolutionary information provided novel evidence for the presence of a phylotranscriptomic hourglass pattern across kingdoms. As its biological function is unknown it remains speculative whether this...

We show that if G is a 4-connected claw-free graph in which every induced hourglass subgraph S contains two non-adjacent vertices with a common neighbor outside S, then G is hamiltonian. This extends the fact that 4-connected claw-free, hourglass-free graphs are hamiltonian, thus proving a broader special case of a conjecture by Matthews and Sumner.

In 1828, Karl von Baer proposed a set of four evolutionary "laws" pertaining to embryological development. According to von Baer's third law, young embryos from different species are relatively undifferentiated and resemble one another but as development proceeds, distinguishing features of the species begin to appear and embryos of different species progressively diverge from one another. An e...

In this paper, we first describe a simplified scenario observed in mining operations, where trucks are loaded and emptied at different locations. We will then look at ways that we can model this subsystem using timed automata so we may be able to apply model checking techniques on such systems. Specifically, we will look at modifications to the Hourglass Automata and Interrupt Timed Automata to...

The Hourglass Model The hourglass model of layered systems architecture [1] is a visual and conceptual representation of an approach to achieving a design that supports a great diversity of applications and admits a great diversity of implementations. At the center of the hourglass model is a distinguished layer in a stack of abstractions that is chosen as the sole means of accessing the resour...

We observe quasi-static incommensurate magnetic peaks in neutron scattering experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states that have been reported to be paramagnetic. This enables us to measure the magnetic excitations in this highly hole-doped incommensurate regime and compare our results with those found in the low-doped incommensurate regime that exhibit hour...

The hourglass model of embryonic evolution predicts an hourglasslike divergence during animal embryogenesis – with embryos being more divergent at the earliest and latest stages but conserved during a mid-embryonic (phylotypic) period that serves as a source of the basic body plan for animals within a phylum. Morphological observations have suggested hourglass-like divergence in various vertebr...

The Internet protocol stack has a layered architecture that resembles an hourglass. The lower and higher layers tend to see frequent innovations, while the protocols at the waist of the hourglass appear to be “ossified”. We propose EvoArch, an abstract model for studying protocol stacks and their evolution. EvoArch is based on a few principles about layered network architectures and their evolu...

Although computer programs explicitly represent data values, time values are usually implicit. This makes it difficult to analyze and debug real-time programs whose correctness depends partially on the time at which results are computed. This paper shows how to use Hourglass, an instrumented, synthetic real-time application, to make inferences about what is happening on a computer at millisecon...