Index proposal and basic estimator study for quantification of oscillation of the secondary flow pattern in tortuous vessels

The development of atherosclerosis has been shown to correlate with regions of low wall shear stress and seemingly reduced mass transport. The local tortuosity of the arteries and local secondary flow oscillation also seem to be negatively correlated with the local occurrence of the disease. However there is currently no tool or physiological parameter that can be measured non-invasively to assess the local oscillation of the flow. Standard Colour Doppler imaging of secondary flow patterns during the blood pulse is studied and illustrated, and the local oscillation of the secondary flow pattern is proposed as an index, which could be an indicator of the likelihood of future disease development. Preliminary results are presented using a basic estimator developed for the proof of concept in the case of swirling flow, and based on colour-coded video signals collected in different configurations. In vitro results show that there is a correspondence between the Doppler patterns and the secondary flow patterns, the repeatability of the measures, and that the proposed index and its estimator reflect a joint influence of the local oscillation of the secondary flow pattern and of the flow rate. On another hand, while in vivo results still suffer from instabilities, noise and from scanners and processing limitations, they demonstrate that it is possible to use Colour Doppler imaging to image and characterize in vivo the secondary flow patterns and their oscillations non-invasively, and that it is possible for a trained clinician to perform manually such Doppler measurements for processing.     

A zirconium dichloro complex supported by an ancillary stereorigid tetradentate bis(phenoxo-imino) Schiff-base-donor ligand: Evidence for a conformational equilibrium between two solution stereoisomers

Reaction of the dilithium salt of the Schiff-base N,N′-o-phenylene-bis(3,5-di-tert-butyl-salicylidene-imine) (^tBu₄salophenH₂) with 1 equiv. of ZrCl₄(THF)₂ in toluene at −78 °C affords the dichloro complex ZrCl₂[C₆H₄-1,2-{NCH-(3,5-^tBu₂C₆H₂-2-O)}₂], isolated as a mixture of the C_2v-(3a) and C₂-(3b) symmetry isomers. Thermodynamic and kinetic parameters for the equilibrium between 3a and 3b have been determined and studied by ¹H NMR spectroscopy. Reactions of ZrCl₂[C₆H₄-1,2-{NCH-(3,5-^tBu₂C₆H₂-2-O)}₂] with alkylating reagents gave an intractable, unidentified mixture of products from which the NMR spectra in C₆D₆ solution are unusable.     

A k-Sample Test for Functional Data Based on Generalized Maximum Mean Discrepancy

Lithuanian Mathematical Journal - In this paper, we deal with the problem of testing the equality of k probability distributions. We introduce a generalization of the maximum mean discrepancy that...     

Phase synchronization of bursting neural networks with electrical and delayed dynamic chemical couplings

Diffusive electrical connections in neuronal networks are instantaneous, while excitatoryor inhibitory couplings through chemical synapses contain a transmission time-delay.Moreover, chemical synapses are nonlinear dynamical systems whose behavior can bedescribed by nonlinear differential equations. In this work, neuronal networks withdiffusive electrical couplings and time-delayed dynamic chemical couplings are considered.We investigate the effects of distributed time delays on phase synchronization of burstingneurons. We observe that in both excitatory and Inhibitory chemical connections, the phasesynchronization might be enhanced when time-delay is taken into account. This distributedtime delay can induce a variety of phase-coherent dynamical behaviors. We also study thecollective dynamics of network of bursting neurons. The network model presents theso-called Small-World property, encompassing neurons whose dynamics have two time scales(fast and slow time scales). The neuron parameters in such Small-World network, aresupposed to be slightly different such that, there may be synchronization of the bursting(slow) activity if the coupling strengths are large enough. Bounds for the criticalcoupling strengths to obtain burst synchronization in terms of the network structure aregiven. Our studies show that the network synchronizability is improved, as itsheterogeneity is reduced. The roles of synaptic parameters, more precisely those of thecoupling strengths and the network size are also investigated.     

Synthesis of a Negative Photochrome with High Switching Quantum Yields and Capable of Singlet-Oxygen Production and Storage

A dimethyldihydropyrene (DHP) photochromic unit has been functionalized by donor (triphenylamine group) and acceptor (methylpyridinium) substituents. This compound was characterized by NMR, absorption and emission spectroscopies as well as cyclic voltammetry, and its properties were rationalized by theoretical calculations. The incorporation of both electron-donor and -withdrawing groups at the photochromic center allows i) an efficient photo-isomerization of the system when illuminated at low energy (quantum yield: Φ_c-o=13.3 % at λ_ex=660 nm), ii) the reversible and quantitative formation of two endoperoxyde isomers when illuminated under aerobic conditions at room temperature, and iii) the storage and production of singlet oxygen. The photo-isomerization mechanism was also investigated by spin-flip TD-DFT (SF-TD-DFT) calculations.     

Solution versus solid-state electropolymerization of regioregular conjugated fluorenone–thienylene vinylene macromonomers—voltammetric and spectroelectrochemical investigations

We present detailed voltammetric and spectroelectrochemical studies of poly(2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)ethylene])-fluoren-9-one) (PTVF)—a conjugated polymer consisting of thienylene, vinylene, and fluorenone subunits. PTVF can be easily obtained either by electropolymerization of its monomer ((2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)ethylene])-fluoren-9-one) [TVF]) dissolved in the electrolytic solution or via solid-state electropolymerization of a thin film of the monomer deposited on the electrode. UV-vis-NIR spectroscopic data indicate that the latter method leads to a polymer of a smaller degree of polymerization (DP). The possibility of the formation of a polymeric conductor on a transparent conductive substrate such as indium tin oxide, in situ, via solid-state electropolymerization, combined with its postpolymerization transformation into an organic semiconductor by electrochemical dedoping, is technologically very attractive and makes TVF and its polymer very promising materials for applications in organic electronics. Contribution to the International Workshop on Electrochemistry of Electroactive Materials (WEEM-2006), Repino, Russia, 24–29 June 2006.     

Geometric inequalities via a general comparison principle for interacting gases

The article builds on several recent advances in the Monge- Kantorovich theory of mass transport which have, among other things, led to new and quite natural proofs for a wide range of geometric inequalities such as the ones formulated by Brunn-Minkowski, Sobolev, Gagliardo- Nirenberg, Beckner, Gross, Talagrand, Otto-Villani and their extensions by many others. While this paper continues in this spirit, we however propose here a basic framework to which all of these inequalities belong, and a general unifying principle from which many of them follow. This basic inequality relates the relative total energy - internal, potential and interactive - of two arbitrary probability densities, their Wasserstein distance, their barycentres and their entropy production functional. The framework is remarkably encompassing as it implies many old geometric - Gaussian and Euclidean - inequalities as well as new ones, while allowing a direct and unified way for computing best constants and extremals. As expected, such inequalities also lead to exponential rates of convergence to equilibria for solutions of Fokker-Planck and McKean-Vlasov type equations. The principle also leads to a remarkable correspondence between ground state solutions of certain quasilinear - or semilinear - equations and stationary solutions of nonlinear Fokker-Planck type equations.     

Recent developments in the use of isotope ratio mass spectrometry in sports drug testing

According to the annual report of the World Anti-Doping Agency, steroids are the most frequently detected class of doping agents. Detecting the misuse of endogenously occurring steroids, i.e. steroids such as testosterone that are produced naturally by humans, is one of the most challenging issues in doping control analysis. The established thresholds for urinary concentrations or concentration ratios such as the testosterone/epitestosterone quotient are sometimes inconclusive owing to the large biological variation in these parameters.