The decay ρ0→π0π0γ\rho^{0}\to \pi^{0}\pi^{0}\gamma and the role of σ\sigma-meson

We study the radiative decay $\rho^{0}\to\pi^{0}\pi^{0}\gamma$ within the framework of a phenomenological approach in which the contributions of $\sigma$-meson and $\omega$-meson intermediate states and of the pion-loops are considered. We conclude that the $\sigma$-meson amplitude provides the dominant contribution.Comment: 12 pages, LATEX, 3 PS figure

The ϕa0γ\phi a_0\gamma- and ϕσγ\phi\sigma\gamma-vertices in light cone QCD

We study $\phi a_0\gamma$- and $\phi\sigma\gamma$-vertices in the framework of the light cone QCD sum rules and we estimate the coupling constants g$_{\phi a_0\gamma}$ and g$_{\phi\sigma\gamma}$ utilizing $\omega\phi$-mixing. We compare our results with the previous estimations of these coupling constants in the literature obtained from phenomenological considerations.Comment: 8 pages, RevTex, 2 figure

Orthogonal polynomials for the weakly equilibrium Cantor sets

Let $K(\gamma)$ be the weakly equilibrium Cantor type set introduced in [10]. It is proven that the monic orthogonal polynomials $Q_{2^s}$ with respect to the equilibrium measure of $K(\gamma)$ coincide with the Chebyshev polynomials of the set. Procedures are suggested to find $Q_{n}$ of all degrees and the corresponding Jacobi parameters. It is shown that the sequence of the Widom factors is bounded below

The a0K+K−a_0K^+K^--vertex in light cone QCD sum rules

We investigate the $a_0K^+K^-$-vertex in the framework of light cone QCD sum rules. We estimate the coupling constant g$_{a_0K^+K^-}$ which is an essential ingredient in the analysis of physical processes involving $a_0(980)$ meson. Our result is somewhat larger than the previous determinations of this coupling constant.Comment: 8 pages, 1 figur

Sponge Aquaculture Trials in the East-Mediterranean Sea: New Approaches to Earlier Ideas

Aquaculture trials were conducted in the East Aegean Sea with Dysidea avara and Chondrosia reniformis to test the possibility of growing these sponges in the vicinity of sea-based fish farms. Culturing sponges in the vicinity of fish farms may have two benefits: the sponges may grow faster due to an increased availability of organic food and the pollution caused by the fish farms is remediated by the filtering activities of the sponges. An initial trial was conducted to compare growth of the two sponge species under floating fish cages to growth in a natural, pristine environment. Explants of D. avara were grown suspended on nylon threads, explants of C. reniformis were grown in cages constructed of stainless steel. After being one year in culture, nearly 100% of all explants of D. avara survived. Growth was highest underneath the fish cages, but growth rates were low compared to earlier studies. For C. reniformis survival at the pristine site was 100%, and growth was estimated at 800% per year. All explants cultured underneath the fish cages died due to smothering with sediment. After the initial trial, a new, cost-saving and growth promoting method for D. avara was tested at the fish farm location. Explants were grown on PVC pins that were mounted into a metal frame. Growth of the sponges on the pins was eight times faster than that of sponges growing on threads. We conclude that culturing D. avara under floating fish cages is feasible when using the new methodolog

The ωσγ\omega\sigma\gamma-vertex in light cone QCD sum rules

We investigate the $\omega\sigma\gamma$-vertex and estimate the coupling constant g$_{\omega\sigma\gamma}$ in the framework of the light cone QCD sum rules. We compare our result with the values of this coupling constant deduced from a phenomenological analysis of $\omega\to\pi\pi\gamma$ decays.Comment: 5 pages, RevTex, 1 Figur

Designing temperature sensors for rocket engine: Organisational change through technological innovation in a french SME.

organisational change

Creating Knowledge in a High-Tech French SME.

This paper deals with organizational learning and knowledge creation in Allcapt, a high-tech French SME, through two different experiences : A technological innovation, dealing with the design of temperature sensors for Ariane V launcher, and an organizational innovation, dealing with human resource management. The paper results from a field research conducted in Allcapt’s plant between 1996-2000. The various stages and steps of the technological and organizational dimensions of problem solving are presented in order to add to existing case studies on organizational learning and knowledge creation, as they are useful to make comparative studies. The same data is also used to propose a deconstruction of the concept of organizational learning and knowledge creation in its different components according to the case in hand. For Allcapt, the proposed relevant deconstruction is the “technological” and the “organizational” aspects of learning and knowledge creation. Allcapt succeeded in the technological innovation challenge, but has been less successful in the organizational aspects, as demonstrated by attempts at innovative experiences in human resource management. This supports the notion that the success in one aspect will not guarantee success in the second aspect, and some of the reasons explaining this divergence are presented in the paper.organizational learning, knowledge creation

The coupling constants g_{\rho\pi\gamma} and g_{\omega\pi\gamma} as derived from QCD sum rules}

We employ QCD sum rules to calculate the coupling constants g$_{\rho\pi\gamma}$ and g$_{\omega\pi\gamma}$ by studying the three point ${\rho\pi\gamma}$- and ${\omega\pi\gamma}$-correlation functions. Our results for the decay widths $\Gamma(\rho^0\to \pi^0\gamma)$ and $\Gamma(\omega\to \pi^0\gamma)$ calculated using the obtained coupling constants are in good agreement with the experimental values of these decay widths

Investigating the relation between optimum guard interval and channel delay spread for a MC-CDMA system

This paper demonstrates a novel approach to determining the optimum guard interval for a multicarrier code division multiple access (MC-CDMA) system. Analytical expressions for useful and interference power are derived as a basis for comparison. From these, an expression for the signal-to-noise ratio of a detected bit is derived and used to determine the optimum guard interval for a given channel profile and system parameters. In contrast to other works, we use channel models based on actual measurements and we highlight important differences from theoretical models to support our approach. From our results, we propose an empirical rule for optimum guard intervals given prevailing channel parameters. We show that the optimum guard interval can be selected as the delay window that includes 95% and 99% multipath power for Es /N0 = 10 dB and Es /N0 = 20 dB, respectively. In our case, the optimum guard interval was between 2 τrms and 4 τrms for Es /N0 = 10 dB and between 3 τrms and 6.4 τrms for Es/N0 = 20 dB