High volume colour image processing with massively parallel embedded processors

Currently Oc´e uses FPGA technology for implementing colour image processing for their high volume colour printers. Although FPGA technology provides enough performance it, however, has a rather tedious development process. This paper describes the research conducted on an alternative implementation technology: software defined massively parallel processing. It is shown that this technology not only leads to a reduction in development time but also adds flexibility to the design

Fluctuations in the Cosmic Microwave Background I: Form Factors and their Calculation in Synchronous Gauge

It is shown that the fluctuation in the temperature of the cosmic microwave background in any direction may be evaluated as an integral involving scalar and dipole form factors, which incorporate all relevant information about acoustic oscillations before the time of last scattering. A companion paper gives asymptotic expressions for the multipole coefficient $C_\ell$ in terms of these form factors. Explicit expressions are given here for the form factors in a simplified hydrodynamic model for the evolution of perturbations.Comment: 35 pages, no figures. Improved treatment of damping, including both Landau and Silk damping; inclusion of late-time effects; several references added; minor changes and corrections made. Accepted for publication in Phys. Rev. D1

An Isocurvature Mechanism for Structure Formation

We examine a novel mechanism for structure formation involving initial number density fluctuations between relativistic species, one of which then undergoes a temporary downward variation in its equation of state and generates superhorizon-scale density fluctuations. Isocurvature decaying dark matter models (iDDM) provide concrete examples. This mechanism solves the phenomenological problems of traditional isocurvature models, allowing iDDM models to fit the current CMB and large-scale structure data, while still providing novel behavior. We characterize the decaying dark matter and its decay products as a single component of ``generalized dark matter''. This simplifies calculations in decaying dark matter models and others that utilize this mechanism for structure formation.Comment: 4 pages, 3 figures, submitted to PRD (rapid communications

Cosmic Strings Lens Phenomenology: Model of Poisson Energy Distribution

We present a novel approach for investigating lens phenomenology of cosmic strings in order to elaborate detection strategies in galaxy deep field images. To account for the complexity of the projected energy distribution of string networks we assume their lens effects to be similar to those of a straight string carrying a {\em random} lineic energy distribution. In such a model we show that, unlike the case of uniform strings, critical phenomena naturally appear. We explore the properties of the critical lines and caustics. In particular, assuming that the energy coherence length along the string is much smaller than the observation scale, we succeeded in computing the total length of critical lines per unit string length and found it to be $4/\sqrt{3} {\bf E}(3/4)$. The length of the associated caustic lines can also be computed to be $16/(\pi \sqrt{3}) {\bf E}(3/4)$. The picture we obtain here for the phenomenology of cosmic string detection is clearly at variance with common lore.Comment: 10 pages, 5 figures. Minor correction

Gauge-ready formulation of the cosmological kinetic theory in generalized gravity theories

We present cosmological perturbations of kinetic components based on relativistic Boltzmann equations in the context of generalized gravity theories. Our general theory considers an arbitrary number of scalar fields generally coupled with the gravity, an arbitrary number of mutually interacting hydrodynamic fluids, and components described by the relativistic Boltzmann equations like massive/massless collisionless particles and the photon with the accompanying polarizations. We also include direct interactions among fluids and fields. The background FLRW model includes the general spatial curvature and the cosmological constant. We consider three different types of perturbations, and all the scalar-type perturbation equations are arranged in a gauge-ready form so that one can implement easily the convenient gauge conditions depending on the situation. In the numerical calculation of the Boltzmann equations we have implemented four different gauge conditions in a gauge-ready manner where two of them are new. By comparing solutions solved separately in different gauge conditions we can naturally check the numerical accuracy.Comment: 26 pages, 9 figures, revised thoroughly, to appear in Phys. Rev.

An Observational Test of Two-field Inflation

We study adiabatic and isocurvature perturbation spectra produced by a period of cosmological inflation driven by two scalar fields. We show that there exists a model-independent consistency condition for all two-field models of slow-roll inflation, despite allowing for model-dependent linear processing of curvature and isocurvature perturbations during and after inflation on super-horizon scales. The scale-dependence of all spectra are determined solely in terms of slow-roll parameters during inflation and the dimensionless cross-correlation between curvature and isocurvature perturbations. We present additional model-dependent consistency relations that may be derived in specific two-field models, such as the curvaton scenario.Comment: 6 pages, latex with revtex, no figures; v2, minor changes, to appear in Physical Review

Preheating After Modular Inflation

We study (p)reheating in modular (closed string) inflationary scenarios, with a special emphasis on Kahler moduli/Roulette models. It is usually assumed that reheating in such models occurs through perturbative decays. However, we find that there are very strong non-perturbative preheating decay channels related to the particular shape of the inflaton potential (which is highly nonlinear and has a very steep minimum). Preheating after modular inflation, proceeding through a combination of tachyonic instability and broad-band parametric resonance, is perhaps the most violent example of preheating after inflation known in the literature. Further, we consider the subsequent transfer of energy to the standard model sector in scenarios where the standard model particles are confined to a D7-brane wrapping the inflationary blow-up cycle of the compactification manifold or, more interestingly, a non-inflationary blow up cycle. We explicitly identify the decay channels of the inflaton in these two scenarios. We also consider the case where the inflationary cycle shrinks to the string scale at the end of inflation; here a field theoretical treatment of reheating is insufficient and one must turn instead to a stringy description. We estimate the decay rate of the inflaton and the reheat temperature for various scenarios.Comment: 34 pages, 10 figures. Accepted for publication in JCA

On the degree of scale invariance of inflationary perturbations

Many, if not most, inflationary models predict the power-law index of the spectrum of density perturbations is close to one, though not precisely equal to one, |n-1| \sim O(0.1), implying that the spectrum of density perturbations is nearly, but not exactly, scale invariant. Some models allow n to be significantly less than one (n \sim 0.7); a spectral index significantly greater than one is more difficult to achieve. We show that n \approx 1 is a consequence of the slow-roll conditions for inflation and ``naturalness,'' and thus is a generic prediction of inflation. We discuss what is required to deviate significantly from scale invariance, and then show, by explicit construction, the existence of smooth potentials that satisfy all the conditions for successful inflation and give $n$ as large as 2.Comment: 7 pages, 2 figures, submitted to Phys. Rev.

Cosmic Microwave Background Anisotropy with Cosine-Type Quintessence

We study the Cosmic Microwave Background (CMB) anisotropies produced by cosine-type quintessence models. In our analysis, effects of the adiabatic and isocurvature fluctuations are both taken into account. For purely adiabatic fluctuations with scale invariant spectrum, we obtain a stringent constraint on the model parameters using the CMB data from COBE, BOOMERanG and MAXIMA. Furthermore, it is shown that isocurvature fluctuations have significant effects on the CMB angular power spectrum at low multipoles in some parameter space, which may be detectable in future satellite experiments. Such a signal may be used to test the cosine-type quintessence models.Comment: 21 pages, 9 figure

Cosmic Density Perturbations from Late-Decaying Scalar Condensations

We study the cosmic density perturbations induced from fluctuation of the amplitude of late-decaying scalar condensations (called \phi) in the scenario where the scalar field \phi once dominates the universe. In such a scenario, the cosmic microwave background (CMB) radiation originates to decay products of the scalar condensation and hence its anisotropy is affected by the fluctuation of \phi. It is shown that the present cosmic density perturbations can be dominantly induced from the primordial fluctuation of \phi, not from the fluctuation of the inflaton field. This scenario may change constraints on the source of the density perturbations, like inflation. In addition, a correlated mixture of adiabatic and isocurvature perturbations may arise in such a scenario; possible signals in the CMB power spectrum are discussed. We also show that the simplest scenario of generating the cosmic density perturbations only from the primordial fluctuation of \phi (i.e., so-called ``curvaton'' scenario) is severely constrained by the current measurements of the CMB angular power spectrum if correlated mixture of the adiabatic and isocurvature perturbations are generated.Comment: 31pages, 14figure