Resonance behavior of liquid bridges under axial and lateral oscillating total body forces

Cylindrical liquid bridges that are magnetically levitated in air against gravity are subjected to either axial or lateral oscillations of the total body force. It was found that the frequency of the first resonance peak is maximum when the total body force is zero and decreases with increasing total body force for both axial and lateral oscillations. The experimental results for the axially symmetric case are compared to theoretical calculations using the one-dimensional slice model.     

Highly anisotropic elasticity of a dendrimeric liquid crystal

Magnetic and electrical Freedericksz measurements were performed on the second generation monodendritic liquid crystal G₂(OH). The deduced elastic constants were found to be exceptionally anisotropic: the splay elastic constant K₁₁ is more than an order of magnitude larger than the bend elastic constant K₃₃, and the twist constant K₂₂ is approximately twice K₃₃. The results are discussed in terms of molecular conformations. Received: 23 February 1998 / Revised and Accepted: 26 May 1998     

An approximate maximum likelihood estimation for non-Gaussian non-minimum phase moving average processes

An approximate maximum likelihood procedure is proposed for the estimation of parameters in possibly nonminimum phase (noninvertible) moving average processes driven by independent and identically distributed non-Gaussian noise. Under appropriate conditions, parameter estimates that are solutions of likelihood-like equations are consistent and are asymptotically normal. A simulation study for MA(2) processes illustrates the estimation procedure.     

Equivalent invariant measures

LetG be a finitely-generated group of non-singular measurable transformations of a measure space (X, β,p). FixA∈β withp(A)>0. A general technique for groups gives sufficient conditions for there to exist aG-invariant measure ν equivalent top with ν((A)=1. These conditions are phrased in terms of the growth behavior ofg→p(gB) forB∈β. The question of necessity is handled in some special cases.     

Electrical nanoprobing of semiconducting carbon nanotubes using an atomic force microscope

We use an atomic force microscope (AFM) tip to locally probe the electronic properties of semiconducting carbon nanotube transistors. A gold-coated AFM tip serves as a voltage or current probe in three-probe measurement setup. Using the tip as a movable current probe, we investigate the scaling of the device properties with channel length. Using the tip as a voltage probe, we study the properties of the contacts. We find that Au makes an excellent contact in the p region, with no Schottky barrier. In the n region, large contact resistances were found which dominate the transport properties.