61,782 research outputs found
A method for the extraction and quantitation of phycoerythrin from algae
A summary of a new technique for the extraction and quantitation of phycoerythrin (PHE) from algal samples is described. Results of analysis of four extracts representing three PHE types from algae including cryptomonad and cyanophyte types are presented. The method of extraction and an equation for quantitation are given. A graph showing the relationship of concentration and fluorescence units that may be used with samples fluorescing around 575-580 nm (probably dominated by cryptophytes in estuarine waters) and 560 nm (dominated by cyanophytes characteristics of the open ocean) is provided
PACE: Pricing And Cost Estimating handbook
The PACE (Pricing and Cost Estimating) system, its purpose, makeup, use, and capabilities are described
Inflation on Moduli Space and Cosmic Perturbations
We show that a moduli space of the form predicted by string theory, lifted by
supersymmetry breaking, gives rise to successful inflation for large regions of
parameter space without any modification or fine tuning. This natural
realization of inflation relies crucially on the complex nature of the moduli
fields and the multiple points of enhanced symmetry, which are generic features
of moduli space but not usually considered in inflationary model building.
Our scenario predicts cosmic perturbations with an almost exactly flat
spectrum for a wide range of scales with running on smaller, possibly
observable, scales. The running takes the form of either an increasingly steep
drop off of the spectrum, or a rise to a bump in the spectrum before an
increasingly steep drop off.Comment: 23 pages, 4 figures; Added Fig. 1 and re-emphasis on dynamical
selection of desirable initial angles for inflaton modulus. To be published
in JHE
A General Analytic Formula for the Spectral Index of the Density Perturbations produced during Inflation
The standard calculation of the spectrum of density perturbations produced
during inflation assumes that there is only one real dynamical degree of
freedom during inflation. However, there is no reason to believe that this is
actually the case. In this paper we derive general analytic formulae for the
spectrum and spectral index of the density perturbations produced during
inflation.Comment: 10 pages, more explanation and references added, version to be
published in Progress of Theoretical Physic
Theoretical formalism for collective electromagnetic response of discrete metamaterial systems
We develop a general formalism to describe the propagation of a near-resonant
electromagnetic field in a medium composed of magnetodielectric resonators. As
the size and the spatial separation of nanofabricated resonators in a
metamaterial array is frequently less than the wavelength, we describe them as
discrete scatterers, supporting a single mode of current oscillation
represented by a single dynamic variable. We derive a Lagrangian and
Hamiltonian formalism for the coupled electromagnetic fields and oscillating
currents in the length gauge, obtained by the Power-Zienau-Woolley
transformation. The response of each resonator to electromagnetic field is then
described by polarization and magnetization densities that, to the lowest order
in a multipole expansion, generate electric and magnetic dipole excitations. We
derive a closed set of equations for the coherently scattered field and normal
mode amplitudes of current oscillations of each resonator both within the
rotating wave approximation, in which case the radiative decay rate is much
smaller than the resonance frequency, and without such an assumption. The set
of equations includes the radiative couplings between a discrete set of
resonators mediated by the electromagnetic field, fully incorporating recurrent
scattering processes to all orders. By considering an example of a
two-dimensional split ring resonator metamaterial array, we show that the
system responds cooperatively to near-resonant field, exhibiting collective
eigenmodes, resonance frequencies, and radiative linewidths that result from
strong radiative interactions between closely-spaced resonators.Comment: 34 pages, 6 figure
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