Control of spiral waves and turbulent states in a cardiac model by travelling-wave perturbations

We propose a travelling-wave perturbation method to control the spatiotemporal dynamics in a cardiac model. It is numerically demonstrated that the method can successfully suppress the wave instability (alternans in action potential duration) in the one-dimensional case and convert spiral waves and turbulent states to the normal travelling wave states in the two-dimensional case. An experimental scheme is suggested which may provide a new design for a cardiac defibrillator.Comment: 9 pages, 5 figure

Secondary Metabolites from Pepper (Piper Nigrum) and Tahitian Noni (Morinda Citrifolia) and Their Biological Activities

Piper nigrum from the Piperaceae family and Morinda citrifolia from the Rubiaceae family were researched in this study. Detailed phytochemical investigations on the roots of these plants afforded ten pure compounds, which consists mainly of alkaloids and anthraquinones, and an acid. The structures of these compounds were elucidated based on 1H NMR, 13C NMR, COSY, DEPT, 2D NMR (HSQC and HMBC), mass spectrometry (MS), and Infrared spectroscopy (FTIR) analysis. Meanwhile, mixtures of compounds were identified through GCMS (gas chromatography-mass spectrometry). From the roots of Piper nigrum, the alkaloids obtained are piperine, pellitorine and aristolactam AII. Besides that, the acid, 3,4-methylenedioxy benzoic acid was also present in the roots of this plant. Meanwhile, anthraquinones and their derivatives such as 1-hydroxy-2-methylanthraquinone, damnacanthal, nordamnacanthal, 2-formyl-1-hydroxyanthraquinone, 2-ethoxy-1-hydroxyanthraquinone and morindone-6-methylether were obtained from the roots of Morinda citrifolia. Among these anthraquinones, 2-ethoxy-1-hydroxyanthraquinone is a new anthraquinone, while morindone-6-methylether is reported for the first time from the plant. In the larvicidal test against the larvae of Aedes aegypti, the ethyl acetate extract of the roots of Piper nigrum showed good activity against the larvae. Pellitorine, on the other hand, gave a significant activity followed by piperine which only gave a moderate activity. The acid and aristolactam AII gave negative results which indicated that they are not biologically active towards the larvae of Aedes aegypti. For Morinda citrifolia, only the chloroform extract and the two anthraquinones, 1-hydroxy-2-methylanthraquinone and damnacanthal are strongly active. From the cytotoxic activity, where tests were conducted using the HL-60 (Acute Promyelocytic Leukaemia) and MCF7 cell lines (Human Breast Adenocarcinoma), the ethyl acetate extract of Piper nigrum gave weak activity with an IC50 value of more than 30 μg/ml against the HL-60 cell line. However, in the tests against the same cell line using piperine and pellitorine, IC50 value of 7.5 μg/ml and 1.5 μg/ml, respectively, were obtained indicating the individual compounds to be strongly cytotoxic. Aristolactam AII gave weak activity with an IC50 value of more than 30 μg/ml when tested on the MCF-7. Compared to the extract and alkaloids from Piper nigrum, the extracts and anthraquinones from Morinda citrifolia gave better results against both HL-60 and MCF7 cell lines. Three extracts amongst the five tested showed significant bioactivity against the HL-60 cell. These are the hexane extract, chloroform extract and petroleum ether extract, with IC50 values of 1.70 μg/ml, 9.3 μg/ml and 11.0 μg/ml, respectively. The methanol and acetone extracts showed moderate activities against the same cell line (HL-60). Damnacanthal, nordamnacanthal and 1-hydroxy-2-methylanthraquinone which were from the hexane and chloroform extracts gave IC50 values of 1.6 μg/mL, 4.4 μg/mL and 15.0 μg/mL, respectively, against the same cell line (HL-60). A comparison of the IC50 values of different extracts against the two cell lines indicated that these extracts did not give satisfying results against the MCF7 cell lines with only the chloroform and petroleum ether extracts giving a moderate activity. The antifungal and antibacterial activities of the extracts and some compounds from the two plants were also evaluated. Fungi such as Aspergilius ochraceaus and Sacchoromyces cerevisiae were used in the antifungal screening. Meanwhile, MRSA, Pseudomonas aeruginosa, Salmonella choleraesuis and Bacillus subtilis were the microbes used in the antibacterial screenings. None of the extracts or alkaloids from Piper nigrum showed any inhibition in both screening. As for Morinda citrifolia, only the chloroform and methanol extracts, and damnacanthal exhibited medium inhibition for Bacillus subtilis in the antibacterial screening. However, in the screening against Salmonella choleraesuis, only the chloroform extract and damnacanthal showed weak inhibition. Meanwhile, nordamnacanthal is the only sample tested that showed a very weak inhibition. In the antifungal screening, the two microbes were shown to be lightly susceptible to the chloroform extract and damnacanthal

Phase slip in a superfluid Fermi gas near a Feshbach resonance

In this paper, we study the properties of a phase slip in a superfluid Fermi gas near a Feshbach resonance. The phase slip can be generated by the phase imprinting method. Below the superfluid transition temperature, it appears as a dip in the density profile, and becomes more pronounced when the temperature is lowered. Therefore the phase slip can provide a direct evidence of the superfluid state. The condensation energy of the superfluid state can be extracted from the density profile of the phase slip, due to the unitary properties of the Fermi gas near the resonance. The width of the phase slip is proportional to the square root of the difference between the transition temperature and the temperature. The signature of the phase slip in the density profile becomes more robust across the BCS-BEC crossover.Comment: 5 pages, 2 figures, the density profile of a phase slip under experimental conditions was calculate

A smooth fictitious domain/multiresolution method for elliptic equations on general domains

International audienceWe propose a smooth fictitious domain/multiresolution method for enhancing the accuracy order in solving second order elliptic partial differential equations on general bivariate domains. We prove the existence and uniqueness of the solution of corresponding discrete problem and the interior error estimate which justifies the improved accuracy order. Numerical experiments are conducted on a cassini oval

Coupling wavelets/vaguelets and smooth fictitious domain methods for elliptic problems: the univariate case

International audienceThis work is devoted to the definition, the analysis and the implementation in the univariate case of a new numerical method for the approximation of par-tial differential equations solutions defined on complex domains. It couples a smooth fictitious domain method of Haslinger et al. [Projected Schur com-plement method for solving non-symmetric systems arising from a smooth fictitious domain approach, Numer. Linear Algebra 14(2007) 713-739] with multiscale approximations. After the definition of the method, error esti-mates are derived: they allow to control a global error (on the whole domain including the boundary of the initial complex domain) as well as an interior error (for any sub-domain strictly included in the control domain). Nu-merical implementation and tests on univariate elliptic problems are finally described

Income and Happiness across Europe: Do Reference Values Matter?

Using data from the European Social Survey (ESS), we examine the link between income and subjective well-being. We find that, for the whole sample of nineteen European countries, although income is positively correlated with both happiness and life satisfaction, reference income exerts a negative effect on individual well-being, a result consistent with the relative utility hypothesis. Performing separate analyses for some Eastern European countries, we also find some evidence of a ‘tunnel effect’, in that reference income has a positive impact on subjective well-being. Our findings support the view that in environments with stable income and employment, reference income serves as a basis for social comparisons, whereas in relatively volatile environments, it is used as a source of information for forming expectations about future status.comparison income, reference groups, happiness, life satisfaction

Spillover effects of FDI on innovation in China : an analysis of provincial data

We use the provincial data from 1995 to 2000 to test the impact of inward FDI on innovation activity in China. We found a positive effect of FDI on the number of patent applications filed by the domestic firms. This positive relationship persists when we divide the patents by types (invention, utility model and external design) and when we group the provinces into regions (the coastal, central, and the western regions). This positive spillover effect is much stronger for minor innovations such as external design and utility model, highlighting a demonstration effect of FDI. However, FDI into the coastal region has a negative effect on invention, which indicates a crowding-out effect of imported technology on domestic innovation in that region. The effects of technical development personnel/expenses and the export/output share of FDI firms are also significant and positive