The coiling of a thin filament of viscous fluid falling onto a surface is a common and easily reproducible hydrodynamic instability. Here we report for the first time that this instability can generate regular spiral patterns, in which air bubbles are trapped in the coil and then advected horizontally by the fluid spreading on the surface. We present a simple model that explains how these beaut...

We take an in-depth look at Thurston’s combinatorial characterization of rational functions for a particular class of maps we call nearly Euclidean Thurston maps. These are orientation-preserving branched maps f : S2 → S2 whose local degree at every critical point is 2 and which have exactly four postcritical points. These maps are simple enough to be tractable, but are complicated enough to ha...

Recent experiments show that an avalanche initiated from a point source propagates downwards by invading a triangular shaped region. The opening angle of this triangle appears to reach 180o for a critical inclination of the pile, beyond which avalanches also propage upwards. We propose a simple interpretation of these observations, based on an extension of a phenomenological model for surface f...

Cytosol proteins prepared from castor bean endosperm (4-day-old) s stimulate the exchange of [IHlpbosphatidylethanolamine between liposomes and mitochondria. The acceleration of the exchange depends on the quantity of cytosol proteins, the time of incubation, and the respective amounts of liposomes and mitochondria. On a per seeding basis, the active proteins are essentiafly located in the endo...

Suppose Γ1 and Γ2 are two convex co-compact co-infinite volume discrete subgroups of PSL(2,C), so that there exists a C∞ diffeomorphism ψ : Ω(Γ1)/Γ1 → Ω(Γ2)/Γ2 that induces an isomorphism φ : Γ1 → Γ2. For fixed s ∈ C, let Si(s) be the scattering operator on Ω(Γi)/Γi (i = 1, 2). Define Srel(s) = S1(s)− ψ ∗S2(s), where ψ ∗S2(s) is the pull-back of S2(s) to an operator acting on the appropriate co...

commented upon the impact that phylogeny reconstruction has had on systematic botany. We further indicated that we feel that plant systematics is currently in a period of reevaluation of the data we have used as well as the methodology employed to estimate phylogeny. This is not to say that issues such as the use of morphological data versus molecular data or whether or not to combine data for ...

Although Bayesian phylogenetic methodologies were first developed in the 1960s (Felsenstein, 1968, 2004), the approach remained relatively obscure until the initial release of the software application MrBayes (Huelsenbeck and Ronquist, 2001). Since that time, the popularity of Bayesian phylogenetics has increased tremendously, and it now must be considered a primary method of analysis on par wi...

Cs ion exchange in RbTiOPO4 and (Yb,Nb):RTP/RTP(001) has been used to locally increase the refractive indices for waveguide circuit fabrication. Ti masks were fabricated on RTP samples by conventional photolithography. Cs exchange was done using a CsNO3 melt at 698 K during 2 h. Elemental analysis confirms an Cs profile with a variable depth. Apparently the Cs exchange is disfavored in the dope...

We use noncommutative topology to study T-duality for principal torus bundles with H-flux. We characterize precisely when there is a “classical” T-dual, i.e., a dual bundle with dual H-flux, and when the T-dual must be “non-classical,” that is, a continuous field of noncommutative tori. The duality comes with an isomorphism of twisted K-theories, required for matching of D-brane charges, just a...

High amounts of endo-β-mannanase (EC 3.2.1.78) activity were extracted from tomato (Lycopersicon esculentum Mill.) fruits when a high-salt-containing buffer was used. Two pI forms of the fruit enzyme were identified, one being much more basic than the many seed isoforms. The number of isoforms increased if a protease inhibitor was not used during extraction. The enzyme was found in the ripe fru...