Direct inscription and evaluation of fiber Bragg gratings in carbon-coated optical sensor glass fibers for harsh environment oil and gas applications.

In this research work, we show the successful inscription of fiber Bragg gratings into carbon-coated pure silica as well as germanium-doped glass fibers by applying the pulsed laser point-by-point manufacturing technique. First, the parameters used for the Ti:sapphire femtosecond laser process are demonstrated. Without removing the polymeric carbon coating, destruction-free formation of highly reflective Bragg gratings is performed with selected types of hermetically enclosed fibers.

Cladding waveguide gratings in standard single-mode fiber for 3D shape sensing.

Femtosecond laser pulses were used for the direct point-by-point inscription of waveguides into the cladding of standard single-mode fibers. Homogeneous S-shaped waveguides have been processed as a bundle of overlapping lines without damaging the surrounding material. Within these structures, FBGs have been successfully inscribed and characterized.

Point-by-point inscription of phase-shifted fiber Bragg gratings with electro-optic amplitude modulated femtosecond laser pulses.

Femtosecond laser pulses were used for the direct point-by-point inscription of phase-shifted fiber Bragg gratings (FBGs) in a single fabrication step without postprocessing. An electro-optic amplitude modulator is used in the setup to generate a defined delay between two identical laser pulse trains for the grating inscription. The grating structure with a central phase shift is formed by focusing the modulated laser pulses into the core of a fiber, while the fiber is translated with a constant velocity.

Information theory based approaches to cellular signaling.

Background: Cells interact with their environment and they have to react adequately to internal and external changes such changes in nutrient composition, physical properties like temperature or osmolarity and other stresses. More specifically, they must be able to evaluate whether the external change is significant or just in the range of noise. Based on multiple external parameters they have to compute an optimal response.

Signal integration in budding yeast.

A complex signalling network governs the response of Saccharomyces cerevisiae to an array of environmental stimuli and stresses. In the present article, we provide an overview of the main signalling system and discuss the mechanisms by which yeast integrates and separates signals from these sources. We apply our classification scheme to a simple semi-quantitative model of the HOG (high-osmolarity glycerol)/FG (filamentous growth)/PH (pheromone) MAPK (mitogen-activated protein kinase) signalling network by perturbing its signal integration mechanisms under combinatorial stimuli of osmotic stress, starvation and pheromone exposure in silico.

G1 and G2 arrests in response to osmotic shock are robust properties of the budding yeast cell cycle.

Boolean modeling has been successfully applied to the budding yeast cell cycle to demonstrate that both its structure and its timing are robustly designed. However, from these studies few conclusions can be drawn how robust the cell cycle arrest upon osmotic stress and pheromone exposure might be. We therefore implement a compact Boolean model of the S.

Robustness and fragility in the yeast high osmolarity glycerol (HOG) signal-transduction pathway.

Cellular signalling networks integrate environmental stimuli with the information on cellular status. These networks must be robust against stochastic fluctuations in stimuli as well as in the amounts of signalling components. Here, we challenge the yeast HOG signal-transduction pathway with systematic perturbations in components' expression levels under various external conditions in search for nodes of fragility.

Spontaneous synchronization of coupled circadian oscillators.

In mammals, the circadian pacemaker, which controls daily rhythms, is located in the suprachiasmatic nucleus (SCN). Circadian oscillations are generated in individual SCN neurons by a molecular regulatory network. Cells oscillate with periods ranging from 20 to 28 h, but at the tissue level, SCN neurons display significant synchrony, suggesting a robust intercellular coupling in which neurotransmitters are assumed to play a crucial role.