Sources recovery from boundary data: A model related to electroencephalography

We are concerned with an inverse problem related to sources detection from boundary data in a 2D medium with piecewise constant conductivity. It stands as a 2D version of the inverse problem of electroencephalography, where pointwise sources model epilepsy foci, with the so-called multi-layer spherical model of the head (scalp, skull, brain). When overdetermined electrical measurements (potential and current flux) are available on the scalp, one wants to recover the current sources (conductivity defaults) located in the brain (inner boundary). This recovery issue reduces to a number of inverse problems, where the sources identification process makes use of best rational approximation in the disk, whereas the preliminary cortical mapping step (Cauchy type issue) relies on best constrained harmonic or analytic approximation in an annulus (bounded extremal problems).     

Enneper immersions

We describe a method to construct minimal surfaces inR ³ which has many computational simplicities and prove that any immersed minimal surface inR ³ may be constructed by using that method. We also show that under certain finite hypotheses on the orders of the coordinate functions, among all conformal minimal immersions of the plane with Gauss mapg=e ^az+b only the parametrizations of helicoids and planes are proper embeddings.     

Laminar boundary layers of co-current gas-liquid stratified flows—II. Velocity measurements

An experimental investigation of the velocity distribution in the laminar boundary layer at a moving interface in co-current gas-liquid flow has been made. The velocity profiles were measured by hot wire technique at different distances from the initial phase interaction location. The experimental results compare well with theoretical predictions which are solutions of the Prandtl's equations.     

Coordination of guidance and stabilization tasks for bicycle rider modelling

Learning to ride a bicycle requires practice and endurance fundamental to interpret the dynamics of a bicycle to control it. Modelling a virtual bicycle rider as a controller considering basic human characteristics is a similar demanding task. One approach for a virtual bicycle rider model is presented here, capable to stabilize the bicycle and follow a given course. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Eiwei?, Aminos?uren

Ohne Zusammenfassung     

Synthesis and Stereochemistry of Some New 1,3-Dioxane Derivatives of 1,4-Diacetylbenzene

Summary.  The synthesis and stereochemistry of new 1,3-dioxane derivatives of 1,4-diacetylbenzene are reported. The anancomeric structure of these compounds, the axial orientation of the aryl group for both 1,3-dioxane rings, and the cis and trans isomerism of some of these compounds is discussed considering data of conformational analysis, NMR investigations, and single crystal X-ray diffractometry. Received September 12, 2001. Accepted (revised) November 5, 2001     

Nanostructuration of soft hydrogels: synthesis and characterization of saccharidic methacrylate gels

With the tremendous development of biosensors, there is a strong need in new biocompatible materials avoiding possible denaturing of biological species, which can be easily processed with already existing technologies. The scope of this study was to develop new hydrogels which could be nanostructured by common lithographic methods. Therefore, new methacrylate hydrogels are described, which include functionalized monomers bearing either neutral groups, such as saccharidic moieties, anionic, or cationic groups. The gels have been synthesized by redox or photochemical-initiated radical polymerization. Their porosity has been characterized by thermoporometry, AFM, and electronic microscopy. The kinetics of the photocross-linking has been analyzed by piezorheometry on some of the materials and has been shown to be compatible with technological process time range. Although the obtained hydrogels are soft, their nanostructuration into 500-nm patterns could be performed by nanoimprint photolithography process, and these patterns were observed to be stable for several months.     

Raman spectroscopic study of a hydroxy-arsenate mineral containing bismuth-atelestite Bi2O(OH)(AsO4)

The Raman spectrum of atelestite Bi2O(OH)(AsO4), a hydroxy-arsenate mineral containing bismuth, has been studied in terms of spectra-structure relations. The studied spectrum is compared with the Raman spectrum of atelestite downloaded from the RRUFF database. The sharp intense band at 834 cm(-1) is assigned to the ν1 AsO4(3-) (A1) symmetric stretching mode and the three bands at 767, 782 and 802 cm(-1) to the ν3 AsO4(3-) antisymmetric stretching modes. The bands at 310, 324, 353, 370, 395, 450, 480 and 623 cm(-1) are assigned to the corresponding ν4 and ν2 bending modes and BiOBi (vibration of bridging oxygen) and BiO (vibration of non-bridging oxygen) stretching vibrations. Lattice modes are observed at 172, 199 and 218 cm(-1). A broad low intensity band at 3095 cm(-1) is attributed to the hydrogen bonded OH units in the atelestite structure. A weak band at 1082 cm(-1) is assigned to δ(BiOH) vibration.     

Solid state fluorescence of Pigment Yellow 101 and derivatives: a conserved property of the individual molecules

The optical properties of the bisazomethine pigments Pigment Yellow 101 (P.Y.101) and three derivatives are investigated employing density functional theory (DFT) and time-dependent DFT (TDDFT). P.Y.101 and one of its derivatives exhibit unusual solid state fluorescence, although both possess OH groups and the latter pigment has particularly small intermolecular distances in its crystal, which are both properties that contradict common empirical rules for fluorescent pigments. Here it is shown that the OH groups are indeed essential for molecular fluorescence of the pigments due to the necessary formation of an intramolecular hydrogen bond with the lone pairs of the bisazomethine nitrogens. Furthermore, the quenching mechanism of molecular fluorescence in the non-fluorescent derivatives is analyzed in detail and a CNN bending motion of the central bisazomethine substructure is identified to be the relevant reaction coordinate along which efficient fluorescence quenching occurs in the individual molecule as well as in the crystal. Electron transfer quenching, which usually is expected to be an important quenching mechanism in aggregated media (here the crystals), is ruled out for the studied bisazomethine pigments. The solid state fluorescence properties of the pigments can finally be understood as conserved molecular properties of the individual pigment molecules.     

Thermal behaviour and photoluminescence properties of Er- and Nd-doped yttrium aluminate glasses

Journal of Thermal Analysis and Calorimetry - Yttrium aluminate glasses (76.8 mol% of Al2O3, 23.2 mol% of Y2O3) doped with Er3+ and Nd3+ ions at different concentration levels...