Some properties of C(X), I

By a result of A.V. Arhangel'skiǐ and E.G. Pytkeiev, the space C(X) of the continuous real functions on X with the topology of pointwise convergence has tightness ω iff Xⁿ is Lindelöf for every n ∈ ω. In this paper we describe other convergence properties of C(X) (e.g. the Fréchet-Urysohn properly) in terms of covering properties of X.In some cases the equivalence between these properties turn out to be dependent on the set theory we choose. Some open problems are also stated.     

Optical constants of gold in MOM tunnel junction

The angular distribution of light emitted by Al-AlO-Au diodes was studied. Fast surface plasmon oscillations (SPO) were found in the top metal film above the d-band absorption edge. From the dispersion curve of SPO the optical constants of the Au film were determined and found to differ from literature data.     

Minimal colorings for properly colored subgraphs

We give conditions on the minimum numberk of colors, sufficient for the existence of given types of properly edge-colored subgraphs in ak-edge-colored complete graph. The types of subgraphs we study include families of internally pairwise vertex-disjoint paths with common endpoints, hamiltonian paths and hamiltonian cycles, cycles with a given lower bound of their length, spanning trees, stars, and cliques. Throughout the paper, related conjectures are proposed.Research supported by a European Union PECO grant under identification number CIPA3510PL929589, while on leave at University Paris-XI     

Spatially inhomogeneous saturation of gain in organic solutions caused by amplified spontaneous emission

A theoretically predicted phenomenon, the spatially inhomogeneous saturation of the gain caused by amplified spontaneous emission, was investigated. The direct measurements of the population of excited states are in good qualitative agreement with the theoretical calculations.     

Left and right negatively orderable semigroups where every element has a left and a right identity

We study two classes of modules for order preserving symplectic and order preserving even special orthogonal rook monoids. The first class of modules are indexed by admissible sets, and the second are the regular representations. For the first class we show that every submodule is cyclic and completely reducible, and for each irreducible component when restricted to a module over a proper submonoid we explore its module properties. For the second we provide explicitly their decompositions into irreducible submodules using admissible sets.     

Generation of stable, low-divergence electron beams by laser-wakefield acceleration in a steady-state-flow gas cell

Laser-driven, quasimonoenergetic electron beams of up to approximately 200 MeV in energy have been observed from steady-state-flow gas cells. These beams emitted within a low-divergence cone of 2.1+/-0.5 mrad FWHM display unprecedented shot-to-shot stability in energy (2.5% rms), pointing (1.4 mrad rms), and charge (16% rms) owing to a highly reproducible gas-density profile within the interaction volume. Laser-wakefield acceleration in gas cells of this type provides a simple and reliable source of relativistic electrons suitable for applications such as the production of extreme-ultraviolet undulator radiation.     

Analytical Calculation of Sensitivity for Capacitive Pressure Transducers

Calculation of sensitivity for capacitive pressure transducers requires the integration of the deflection function of a clamped‐edge thin diaphragm. For typical square‐formed diaphragms we integrated analytically a closed form deflection function obtained by the Ritz‐method. This exact integration enables fast and accurate simulation.