Square triangle tilings are relevant models for quasicrystals. We introduce a new self-similar tile-substitution which yields the well-known nonperiodic square triangle tilings of Schlottmann. It is shown that the new tilings are locally derivable from Schlottmann’s, but not vice versa, and that they are mutually locally derivable with the undecorated square triangle tilings. Furthermore, the r...

It is well-known that fundamental performance limitations exist when using linear feedback control for linear systems. In this note, we present an example of a nonlinear control strategy that can achieve a time-domain performance specification that cannot be obtained by any linear controller. In particular, we present a variable-gain control approach that meets an overshoot requirement that can...

. T W O techn iques a r e presented here t o enable q u a n t i t a t i v e comparison o f t i m e domain fundamental f requency e s t i m a t i o n a l g o r i t h m s a g a i n s t a r e fe rence , t h a t makes use o f t h e o u t p u t f rom a laryngograph. These measures a re c a r r i e d o u t on t h e p u l s a t i l e ou tpu t s produced by t h e dev ices, where each pu lse corresponds...

The n+ 1-dimensional Milne Universe with extra free directions is used to construct simple FRW cosmological string models in four dimensions, describing expansion in the presence of matter with p = κρ, κ = (4 − n)/3n. We then consider the n = 2 case and make SL(2,Z) orbifold identifications. The model is surprisingly related to the null orbifold with an extra reflection generator. The study of ...

It is generally assumed, both in common-sense argumentations and scientific concepts, that brains and neurons represent late evolutionary achievements which are present only in more advanced animals. Here we overview recently published data clearly revealing that our understanding of bacteria, unicellular eukaryotic organisms, plants, brains and neurons, rooted in the Aristotelian philosophy is...

This paper has a twofold purpose. The first is to compute the Euler characteristics of hyperbolic Coxeter groups WS of level 1 or 2 by a mixture of theoretical and computer aided methods. For groups of level 1 and odd values of jSj, the Euler characteristic is related to the volume of the fundamental region of WS in hyperbolic space. Secondly we note two methods of imbedding such groups in each...

We use an elliptic differential equation of Ţiţeica (or Toda) type to construct a minimal Lagrangian surface in CH from the data of a compact hyperbolic Riemann surface and a cubic holomorphic differential. The minimal Lagrangian surface is equivariant for an SU(2, 1) representation of the fundamental group. We use this data to construct a diffeomorphism between a neighbourhood of the zero sect...

As usual, there is associated to gQ a connected algebraic group G of linear transformations of VC = VQ ⊗ QC. If H is some lattice in VQ satisfying (i) M = ∑ λ∈L M ∩ V (λ), (ii) (X α/n!)M ⊆ M for all α, then we let GZ = {g ∈ G | gM = M}. Let ω be a left invariant form on GR of highest degree which takes the value ±1 on (∧i=1H1) ∧ (∧α>0Xα) and let [dg] be the Haar measure associated to ω. Our pur...