Non-Flat Power Spectra in the CDM Model

Standard inflation with one scalar field produces primordial perturbations with a nearly flat ('Harrison-Zeldovich') power spectrum. Here we consider first, a double inflation spectrum, and second, a massive scalar field with an interaction potential which mimics an early quartic interaction, but fading away at a characteristic scale. We solve numerically the linear perturbation equations with initial conditions due to scalar field quantum fluctuations at the initial horizon crossing. The resulting power spectra are shown to be non-flat, exhibiting either a break or a valley. Using the transfer function of cold dark matter model we study the influence of the shape of primordial power spectra on observations of large scale structure in the universe. We compare the power spectra in redshift space with reconstructed power spectra from the IRAS catalogue. Further we discuss the variances of galaxy counts in cells, and the mass function of galaxy clusters. Comparison with standard CDM demonstrates the advantages and benefits of the more complicated initial spectra.Comment: gzip-compressed postscript file including figure

Dynamical light vector mesons in low-energy scattering of Goldstone bosons

We present a study of Goldstone boson scattering based on the flavor SU(3) chiral Lagrangian formulated with vector mesons in the tensor field representation. A coupled-channel channel computation is confronted with the empirical s- and p-wave phase shifts, where good agreement with the data set is obtained up to about 1.2 GeV. There are two relevant free parameters only, the chiral limit value of the pion decay constant and the coupling constant characterizing the decay of the rho meson into a pair of pions. We apply a recently suggested approach that implements constraints from micro- causality and coupled-channel unitarity. Generalized potentials are obtained from the chiral Lagrangian and are expanded in terms of suitably constructed conformal variables. The partial-wave scattering amplitudes are defined as solutions of non-linear integral equations that are solved by means of an N/D ansatz.Comment: 15 pages, 8 figures, typos corrected, accepted for publication in Physics Letters

Coastal permafrost landscape development since the Late Pleistocene in the western Laptev Sea, Siberia

The palaeoenvironmental development of the western Laptev Sea is understood primarily from investigations of exposed cliffs and surface sediment cores from the shelf. In 2005, a core transect was drilled between the Taymyr Peninsula and the Lena Delta, an area that was part of the westernmost region of the non-glaciated Beringian landmass during the late Quaternary. The transect of five cores, one terrestrial and four marine, taken near Cape Mamontov Klyk reached 12km offshore and 77m below sea level. A multiproxy approach combined cryolithological, sedimentological, geochronological (C-14-AMS, OSL on quartz, IR-OSL on feldspars) and palaeoecological (pollen, diatoms) methods. Our interpretation of the proxies focuses on landscape history and the transition of terrestrial into subsea permafrost. Marine interglacial deposits overlain by relict terrestrial permafrost within the same offshore core were encountered in the western Laptev Sea. Moreover, the marine interglacial deposits lay unexpectedly deep at 64m below modern sea level 12km from the current coastline, while no marine deposits were encountered onshore. This implies that the position of the Eemian coastline presumably was similar to today's. The landscape reconstruction suggests Eemian coastal lagoons and thermokarst lakes, followed by Early to Middle Weichselian fluvially dominated terrestrial deposition. During the Late Weichselian, this fluvial landscape was transformed into a poorly drained accumulation plain, characterized by widespread and broad ice-wedge polygons. Finally, the shelf plain was flooded by the sea during the Holocene, resulting in the inundation and degradation of terrestrial permafrost and its transformation into subsea permafrost

How Would 'Tempo Policies' Work? Exploring the Effect of School Reforms on Period Fertility in Europe

Governments and NGOs in many industrialized countries are concerned about the long-term demographic impacts of low fertility levels. We discuss how "tempo policies," reforms that shift the timing of childbearing, affect period and possibly cohort fertility levels. One such policy is a school reform that decreases the educational completion age, which could be achieved through an earlier school entrance age and compression of the school duration. Such policies are currently in focus in several low fertility countries, although for reasons not related to family issues. We show that a younger initiation of childbearing would have a rejuvenating effect on the age composition and increase the size of the population. Even if just the timing and not the levels of fertility increase, a younger timing of fertility could soften the trends of shrinking and ageing populations

Zigzag transitions and nonequilibrium pattern formation in colloidal chains

Paramagnetic colloidal particles that are optically trapped in a linear array can form a zigzag pattern when an external magnetic field induces repulsive interparticle interactions. When the traps are abruptly turned off, the particles form a nonequilibrium expanding pattern with a zigzag symmetry, even when the strength of the magnetic interaction is weaker than that required to break the linear symmetry of the equilibrium state. We show that the transition to the equilibrium zigzag state is always potentially possible for purely harmonic traps. For anharmonic traps that have a finite height, the equilibrium zigzag state becomes unstable above a critical anharmonicity. A normal mode analysis of the equilibrium line configuration demonstrates that increasing the magnetic field leads to a hardening and softening of the spring constants in the longitudinal and transverse directions, respectively. The mode that first becomes unstable is the mode with the zigzag symmetry, which explains the symmetry of nonequilibrium patterns. Our analytically tractable models help to give further insight into the way that the interplay of such factors as the length of the chain, hydrodynamic interactions, thermal fluctuations affect the formation and evolution of the experimentally observed nonequilibrium patterns.Comment: 16 pages, 8 figures; to appear in the Journal of Chemical Physic

Quasi-deterministic transport of Brownian particles in an oscillating periodic potential

We consider overdamped Brownian dynamics in a periodic potential with temporally oscillating amplitude. We analyze the transport which shows effective diffusion enhanced by the oscillations and derive approximate expressions for the diffusion coefficient. Furthermore we analyze the effect of the oscillating potential on the transport if additionally a constant force is applied. We show the existence of synchronization regimes at which the deterministic dynamics is in resonance with the potential oscillations giving rise to transport with extremely low dispersion. We distinguish slow and fast oscillatory driving and give analytical expressions for the mean velocity and effective diffusion.Comment: submitted: Feb 12th, 201

How Education Drives Demography and Knowledge Informs Projections

This paper makes the case for systematically adding education to age and sex as a third standard demographic dimension. It directly addresses the question whether the pervasive association of education with demographic outcomes reflects a causal relationship. Based on the notion of functional causality, the paper reviews theoretical and empirical approaches for assessing this question according to three criteria. It also explores possible alternative explanations such as reverse causality and self-selection, concluding that a functional causal relationship between education and health- and fertility-related outcomes is supported by the evidence. The paper then describes the book's expert argument-based approach for defining assumptions for population projections and compare this approach with how European national statistical offices now make and use their assumptions for population projections. Against this background the approach chosen for this study combines a structured substantive inquiry among hundreds of international experts with formal statistical models

Is Heavy Baryon Approach Necessary?

It is demonstrated that using an appropriately chosen renormalization condition one can respect power counting within the relativistic baryon chiral perturbation theory without appealing to the technique of the heavy baryon approach. Explicit calculations are performed for diagrams including two-loops. It is argued that the introduction of the heavy baryon chiral perturbation theory was useful but not necessary.Comment: 9 pages, 2 figures, minor changes, references adde