A unifying 2D action for integrable $$sigma $$σ-models from 4D Chern–Simons theory

Letters in Mathematical Physics - In the approach recently proposed by K. Costello and M. Yamazaki, which is based on a four-dimensional variant of Chern–Simons theory, we derive a simple and...     

Automated self-organising vehicles for Barclays Cycle Hire

Self-organisation is a distributed and asynchronous process in which global pattern or behaviour emerge from local components of the system. Neither central control nor external intervention is necessary during this process. Self-organising systems are adaptive and robust, which are appealing properties from a design and engineering point of view. In this paper, we present an innovative self-organisation approach for a dynamic vehicle routing problem, the Barclay Cycle Hire truck dispatch. In addition, we introduce an evolutionary algorithm capable of automatically configuring the “self-organising trucks”. Experimental results show the evolutionary algorithm improves the overall fitness of the self-organising trucks; and we observe global emergent behaviour in the way trucks self-organise.     

Three-dimensional electric field visualization utilizing electric-field-induced second-harmonic generation in nematic liquid crystals

An electric-field-induced second-harmonic-generation signal in a nematic liquid crystal is used to map the electric field in an integrated-circuit-like sample. Since the electric-field-induced second-harmonic-generation signal intensity exhibits a strong dependence on the polarization of the incident laser beam, both the amplitude and the orientation of the electric field vectors can be measured. Combined with scanning second-harmonic-generation microscopy, three-dimensional electric field distribution can be easily visualized with high spatial resolution of the order of 1 microm.     

Norbornane: an investigation into its valence electronic structure using electron momentum spectroscopy, and density functional and Green's function theories

We report on the results of an exhaustive study of the valence electronic structure of norbornane (C(7)H(12)), up to binding energies of 29 eV. Experimental electron momentum spectroscopy and theoretical Green's function and density functional theory approaches were all utilized in this investigation. A stringent comparison between the electron momentum spectroscopy and theoretical orbital momentum distributions found that, among all the tested models, the combination of the Becke-Perdew functional and a polarized valence basis set of triple-zeta quality provides the best representation of the electron momentum distributions for all of the 20 valence orbitals of norbornane. This experimentally validated quantum chemistry model was then used to extract some chemically important properties of norbornane. When these calculated properties are compared to corresponding results from other independent measurements, generally good agreement is found. Green's function calculations with the aid of the third-order algebraic diagrammatic construction scheme indicate that the orbital picture of ionization breaks down at binding energies larger than 22.5 eV. Despite this complication, they enable insights within 0.2 eV accuracy into the available ultraviolet photoemission and newly presented (e,2e) ionization spectra, except for the band associated with the 1a(2) (-1) one-hole state, which is probably subject to rather significant vibronic coupling effects, and a band at approximately 25 eV characterized by a momentum distribution of "s-type" symmetry, which Green's function calculations fail to reproduce. We note the vicinity of the vertical double ionization threshold at approximately 26 eV.     

Temporally and spatially heterogeneous distribution of mTHPC in a murine tumor observed by two-color confocal fluorescence imaging and spectroscopy in a whole-mount model

Efficient intratumor delivery of anticancer drugs and photosensitizers is an important factor in the success of chemotherapy and photodynamic therapy, respectively. Unfortunately, their adequate and uniform intratumor distribution is impeded by several physiological barriers and by binding to tissue components. Measurement of gross tumor drug accumulation is a routine method of investigating the uptake and clearance of chemotherapy agents and photosensitizers but tells little about their extravascular spatial distribution. We use whole-mount two-color confocal fluorescence imaging and imaging spectroscopy of unprocessed excised murine tumor fragments to investigate the intratumor distribution of the photosensitizer meso-tetrahydroxyphenyl chlorin (mTHPC) as a function of distance from blood vessels perfused with 0.2 mum diameter fluorescent microspheres. Significant mismatches between drug and perfused vasculature are caused by heterogeneities in tumor blood supply. We describe complex microscopic mTHPC gradients that reverse dramatically relative to the perfused vasculature with time after injection. This imaging technique can be applied to screen the dynamic intratumor distribution of other fluorescent photosensitizers and anticancer drugs.     

Propriétés électriques des gels aqueux d'amphiphile

Summary This paper deals with the calculation of electrical conductivity in soap-water-systems. Two models are discussed and compared with experimental data.

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Zusammenfassung In der vorliegenden Arbeit werden zwei Modelle zur Berechnung der Leitf?higkeit in Seifen-Wasser-Mischungen beschrieben und mit experimentellen Daten verglichen.

     

Solvation and dissociation of the carbanionic barium salt of the double 1,1′diphenylethylene in tetrahydrofuran

Mono- and dicarbanionic derivatives of 4,4bis(1-phenylethylene)1,1-biphenyl) (BPB): are prepared by addition of cumyl-barium or polystyryl-barium to BPB in tetrahydrofuran (THF). Spectroscopic and conductimetric measurements on monoadduct solutions were carried out in a temperature range from –105 to 25°C. At low temperature these solutions show a large spectral shift, due to the equilibrium between tight and solvent separated ion pairs. The thermodynamic parameters of this two step ion pair solvation were determined and the corresponding dissociation constant was found to be K _d =1×10^–6 mol-dm^–3 at 20°C. Once the first addition completed, the remaining double bond of the monoadduct seems to be less reactive than those of the original BPB. The diadduct has been prepared in the presence of an excess of cumyl-barium, and characterized spectroscopically.     

Dissociative ionization of the H2O molecule bombarded by swift singly charged and slow highly charged ions

Fragment ion energy spectra of the water molecule have been measured in conventional crossed-beam experiments by the impact of 46 keV/u energy, singly charged ions (SCIs) and 4.3 keV/u energy, highly charged ions (HCIs). Double differential cross sections have been determined and a comparative analysis has been performed. We found that the fragmentation spectra for SCIs and HCIs are very similar, indicating that both collisions lead to the same fragmentation channels. This suggests that the Coulomb explosion of the water molecule is dominantly determined by the charge state of the transient molecular ions, and it is almost independent from the primary ionization mechanism. Differences were observed not only between the SCI and HCI impact-induced fragmentation cross sections, but between those obtained by the 60 keV N⁶⁺ and 70 keV O⁷⁺ projectiles. The differences were attributed to the selectivity of the electron capture process for HCIs. Multiple target ionization cross sections have been deduced from the fragment ion spectra. We found contributions of up to fivefold ionization for SCIs and up to sixfold ionization for HCIs.