A functional calculus in hilbert space based on operator valued analytic functions

A homomorphic map is defined from the algebra of norm bounded analyticN-operator valued functions in the unit disc into the algebra of bounded operators in Hilbert spaces represented as left invariant subspaces ofH ²(N), and the spectral properties of the map are studied. The subclass of functions having norm bound one in the disc is characterized in terms of the power series coefficients. This paper was partially supported by the National Science Foundation under contract NSF GP-5455.     

The Pionic Hydrogen Experiment at PSI

The measurement of the strong-interaction effects in pionic hydrogen gives access to fundamental properties of the pion–nucleon interaction. Methods developed within the framework of Heavy-Baryon Chiral Perturbation Theory allow calculations with an accuracy of a few per cent, which should be tested by experiment. Techniques advanced for recent experiments on the precision spectroscopy of X-rays from antiprotonic and pionic atoms will be used in a new series of measurements for pionic hydrogen. The aim is to achieve finally an accuracy of 0.2% for the hadronic shift ∈_1s and most important of about 1% for the broadening Γ_1s . An essential part of the experimental program is an improved understanding of the atomic cascade. At first, the value of ∈_1s has to be proven not to be influenced by molecular formation. Secondly, a more accurate determination of Γ_1s requires a detailed study of Coulomb deexcitation. This revised version was published online in August 2006 with corrections to the Cover Date.     

Surface thermometry in combustion diagnostics by sputtered thin films of thermographic phosphors

The accuracy and robustness of the thermographic phosphors (TP) technique relies in the use of coatings with low thickness, high-intensity luminescent emission and high adhesion to the surfaces. Sputter deposition has been evaluated as an alternative for coating preparation of TPs for surface thermometry in combustion diagnostics. Thin films of \(\hbox {Gd}_{3}\hbox {Ga}_{5}\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) have been deposited on fused silica and stainless steel substrates by radio frequency magnetron sputtering. Physical, chemical, and temperature-dependent luminescence properties of the phosphor films have been evaluated using X-ray diffraction, X-ray photoelectron spectroscopy and laser-induced luminescence, respectively. The results showed that the luminescence features of the thin films must be activated by heat treatment after sputter deposition. The \(\hbox {Gd}_{3}\hbox {Ga}_{5}\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) films exhibited appropriate temperature sensitivity with adequate precision of the temperature determination, proving to be suitable for pointwise (0D) surface thermometry. An evaluation of the spatial homogeneity of the luminescence properties, which has not been yet addressed in the literature for thin films of TPs, revealed that thin \(\hbox {Gd}_3\hbox {Ga}_5\hbox {O}_{12}{:}\hbox {Cr}^{3+}\) films deposited on fused silica can be used for spatially resolved surface thermometry while those deposited on stainless steel require improvements to overcome spatial inhomogeneities of the luminescence lifetimes.     

Surface Wrinkling Induced by Photofluidization of Low Molecular Azo Glasses

Photoinduced surface wrinkling is demonstrated for a low molecular azo compound confined between a substrate and a thin inorganic elastic layer. The wrinkling process is investigated by time‐resolved light scattering as well as by two‐dimensional autocorrelation analysis of microscopic images. It is shown that the temporal evolution of the wrinkling pattern is directly controlled by the amount of photons absorbed by the sample and that there is no significant dependence of the equilibrium wavelength on irradiation intensity. Finally, the comparison of thermal and photoinduced wrinkling revealed that photoinduced wrinkles are characterized by a narrower mode distribution and less coarsening.     

On Duality in Some Problems of Geometric Control

The paper focuses on the analysis of duality theory in the functional, or module theoretic, approach to geometric control. Various results, previously obtained, on the characterization of controlled and conditioned invariant subspaces are related by duality. The duality is not a simple using adjoint maps. The difficulties stem from the fact that we want all characterizations to be based on left matrix fractions. Such characterizations are close to autoregressive representations of behaviors. To obtain all characterizations to be based on left matrix fractions we have to recourse to a two step process involving isomorphisms of polynomial and rational models as well as the use of dual spaces. Doubly coprime factorizations play a significant role and help to illuminate the role of behaviors in this duality theory.*Partially supported by ISF under Grants No. 235/01 and 1282/05. ^†Earl Katz Family Chair in Algebraic System Theory.     

A comparison of three random disciplines

Consider a general system (or subsystem) with a single queue. In this context, we compare three different disciplines:ROS (Random Order of Service),RI (Random Insertion), andRAP (Randomly Assigned Priorities). The first of these (ROS) is a classical discipline; the other two are introduced in this paper. It turns out that the waiting time distributions for two of these disciplines are exactly the same, while the third discipline has strikingly different characteristics.Work done by this author while he was with IBM Zurich Research Laboratory.     

Electrical field-effect of polyvinylidenefluoride (PVF2)

Summary By means of modified field-effect measurements the properties of space charge distribution in polymers at the polymer-metal interface have been investigated. In general, these properties are due to excess charge and/or dipole orientation. The superposition of both effects is investigated in PVF₂ (phase-II) in order to show whether the conformational PVF₂ properties in the crystalline or in the noncrystalline regions control the space charge distribution. In the temperature region 60 °C <T < 90 °C and for times greater than 60 sec the space charge properties are significant influenced by additional dipole relaxations which result from the beginning chain mobility within the crystallites of PVF₂. In the time interval 1 sec <t < 60 sec charge carrier injection at the PVF₂-gold contact can be described by the Richardson-Schottky theory. Based on this theory, a plot of reduced current versus reduced field is presented displaying all experimental data obtained at various temperatures and field-strength on a single curve. No clear distinction can be given in this case between bulk-limited and electrode-limited processes.With 6 figures     

High-resolution analytical electron microscopy of catalytically etched silicon nanowires

We report on the characterization of hexagonally ordered, vertically aligned silicon nanowires (SiNW) by means of analytical transmission electron microscopy. Combining colloidal lithography, plasma etching, and catalytic wet etching arrays of SiNW of a sub-50 nm diameter with an aspect ratio of up to 10 could be fabricated. Scanning transmission electron microscopy has been applied in order to investigate the morphology, the internal structure, and the composition of the catalytically etched SiNW. The analysis yielded a single-crystalline porous structure composed of crystalline silicon, amorphous silicon, and SiO _x with x≤2.