On Preservation Theorems for Two-Variable Logic

We show that the existential preservation theorem fails for two-variable first-order logic FO². It is known that for all k ≥ 3, FO^k does not have an existential preservation theorem, so this settles the last open case, answering a question of Andreka, van Benthem, and Németi. In contrast, we prove that the homomorphism preservation theorem holds for FO².     

Stability of Liquid Layers on Solid Materials

For a class of disjoining pressure potentials the existence of stable liquid layers on solid surfaces is studied. In some cases of solid configurations with simple geometries explicit results are obtained, in particular for a single cylindrical or spherical cavity. No smallness for the thickness of the layer is assumed.     

Ultrashort pulse generation and measurement techniques

The first section will discuss the generation of picosecond and femtosecond laser pulses, their propagation and compression in optical fibers, and their amplification for nonlinear spectroscopic applications. Laser systems for different wavelength regimes and pulse measurement techniques will be described. The second section will extend the discussion of picosecond and femtosecond measurement to studies of ultrafast processes in materials. Pump-probe and transient four-wave-mixing methods will be analyzed. Examples of application to both molecular and solid state systems will be presented.     

Novel Thermostable Flavin‐binding Fluorescent Proteins from Thermophilic Organisms

Flavin‐binding fluorescent proteins (FbFPs) are small, oxygen‐independent in vivo reporters, derived from Light Oxygen Voltage (LOV) domains of photoreceptors. Here, we investigated the thermostability of existing, as well as novel FbFPs, whose genes were identified in genome sequences of various thermophilic bacteria as well as metagenomic libraries from hot springs in the Yellowstone National Park. Detailed in vitro analyses revealed that two of those fluorescent reporter proteins were highly thermostable, exhibiting melting temperatures above 75°C.