Network analysis of complex biological systems : boundedness of weakly reversible chemical reaction networks and conditions for synchronisation of coupled oscillators

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Paved with Good Intentions: The Failure of Passive Disability Policy in Canada

It is common in the disability community to speak of unfulfilled aspirations for full citizenship and participation in the mainstream of Canadian society. In Canada, as in much of the developed world, many adults with disabilities remain outside the mainstream, especially in regard to economic opportunities. Unfortunately, many of the disability policies currently pursued by Canadian governments are unlikely to improve this situation, and may in fact make it worse. This paper offers a critical analysis of a common instrument of current disability policy, the passive cash benefit. I will focus, in particular, on the effects of passive transfers on prospects for adults with disabilities to reach their full income potential through employment. I will attempt to establish that passive income support strategies – for adults with disabilities and for low-income people in general – force their intended beneficiaries to sacrifice employment prospects for help with short-term income needs, a trade-off that reinforces poverty and dependency over the longer term

A view on the iconic turn from a semiotic perspective

Media are not only a means of communication. From a cognitive perspective, they may be viewed as components of an external, auxiliary memory system (Schönpflug 1997), and contemporary cognitive science “construes cognition as a complex system in which cognitive processes are ‘embodied, situated’ in environments, and ‘distributed’ across people and artifacts” (Nersessian 2007: 2). In man-machine communication, man-man-communication via digital machinery and especially in the World Wide Web (Heintz 2006, Steels 2006) the “external” components of this system have taken on more and more of the characteristics of our individual, “internal”, living and active memory with its richness of sensual and symbolic formats. The intellectual challenge in the drafts of the “masterminds” of hypertext (Eisenstein) and multimedia (Lintsbakh) was the detection of temporal/spatial, mathematical and linguistic correspondences between such different sensual and symbolic representations (Bulgakova 2007, Tsivian 2007). The so called “iconic” or “pictorial turn” was pulled along by the digital turn, and it may in turn have stimulated and accelerated the digital turn

The Tilting Theory of Contraction Algebras

To every minimal model of a complete local isolated cDV singularity Donovan--Wemyss associate a finite dimensional symmetric algebra known as the contraction algebra. We construct the first known standard derived equivalences between these algebras and then use the structure of an associated hyperplane arrangement to control the compositions, obtaining a faithful group action on the bounded derived category. Further, we determine precisely those standard equivalences which are induced by two-term tilting complexes and show that any standard equivalence between contraction algebras (up to algebra isomorphism) can be viewed as the composition of our constructed functors. Thus, for a contraction algebra, we obtain a complete picture of its derived equivalence class and, in particular, of its derived autoequivalence group.Comment: 36 pages, proof of Lemma 4.11 corrected and other minor change

Simulations of Clusters of Galaxies

The degree of complexity and, to a somewhat lesser degree, realism in simulations has advanced rapidly in the past few years. The simplest approach - modeling a cluster as collisionless dark matter and collisonal, non--radiative gas is now fairly well established. One of the most fruitful results of this approach is the {\sl morphology--cosmology connection} for X-ray clusters. Simulations have provided the means to make concrete predictions for the X-ray morphologies of clusters in cosmologies with different $\Omega_o$, with the result that low $\Omega_o$ cosmologies fair rather poorly when compared to observations. Another result concerns the accuracy of \xray binding mass estimates. The standard, hydrostatic, isothermal model estimator is found to be accurate to typically better than $50\%$ at radii where the density contrast is between $10^2$ and $10^3$. More complicated approaches, which attempt to explicitly follow galaxy formation within the proto--cluster environment are slowly being realized. The key issue of {\sl dynamical biasing} of the galaxy population within a cluster is being probed, but conclusive answers are lacking. The dynamics of multi--phase gas, including conversion of cold, dense gas into stars and the feedback therefrom, is the largest obstacle hindering progress. An example demonstrating the state--of--the--art in this area is presented.Comment: to appear in Proceedings of the XIVth Moriond Astrophysics Meeting. 10 pages, uuencoded, compressed postscript file includes figures (~1 Mb after unpacked