29,146 research outputs found
Bayesian analysis of spatially distorted cosmic signals from Poissonian data
Reconstructing the matter density field from galaxy counts is a problem
frequently addressed in current literature. Two main sources of error are shot
noise from galaxy counts and insufficient knowledge of the correct galaxy
position caused by peculiar velocities and redshift measurement uncertainty.
Here we address the reconstruction problem of a Poissonian sampled log-normal
density field with velocity distortions in a Bayesian way via a maximum a
posteriory method. We test our algorithm on a 1D toy case and find significant
improvement compared to simple data inversion. In particular, we address the
following problems: photometric redshifts, mapping of extended sources in coded
mask systems, real space reconstruction from redshift space galaxy distribution
and combined analysis of data with different point spread functions.Comment: 19 pages, 10 figures, accepte
The Secret Science of Synchronicity Paper
Several metaphysical/philosophical concepts are developed as tools by which we may further understand the essence, structure, and events/symbols of “Complex” Synchronicity, and how these differ from “Chain of Events” Synchronicity. The first tool is the concept of Astronomical vs Cultural time. This tool is to be the basis of distinguishing Simple from Complex Synchronicity as Complex Synchronicities are chunks of time that have several coincidences in common with each other. We will also look at the nature of the perspective of the time being quantized. The next tool is a particular case study of two movies, The Matrix and Black Swan, that may be viewed as an example of a Complex Synchronicity in the collective conscious of popular culture (as opposed to Simple Synchronicity or a single coincidence). And the final tool is the concept of “Chain of Events” synchronicity as a separate concept from Simple or Complex synchronicities. This 3rd tool is developed using a mathematical metaphor of foreshadowing (an element of storytelling) in the seemingly random pattern of prime numbers. The purpose of this paper is to distinguish and develop these concepts and to lay a foundation for the further study of the concept of Synchronicity first illuminated by Carl Jung as an acausal connecting principle between coincidences
Origin of the photoemission final-state effects in Bi2Sr2CaCu2O8 by very-low-energy electron diffraction
Very-low-energy electron diffraction with a support of full-potential band
calculations is used to achieve the energy positions, K// dispersions,
lifetimes and Fourier compositions of the photoemission final states in
Bi2Sr2CaCu2O8 at low excitation energies. Highly structured final states
explain the dramatic matrix element effects in photoemission. Intense c(2x2)
diffraction reveals a significant extrinsic contribution to the shadow Fermi
surface. The final-state diffraction effects can be utilized to tune the
photoemission experiment on specific valence states or Fermi surface replicas.Comment: 4 pages, 3 Postscript figures, submitted to Phys. Rev. Lett; major
revision
Multiobjective Lagrangian duality for portfolio optimization with risk measures
In this paper we present an application for a multiobjective optimization problem. The objective functions of the primal problem are the risk and the expected pain associated to a portfolio vector. Then, we present a Lagrangian dual problem for it. In order to formulate this problem, we introduce the theory about risk measures for a vector of random variables. The definition of this kind of measures is a very evolving topic; moreover, we want to measure the risk in the multidimensional case without exploiting any scalarization technique of the random vector. We refer to the approach of the image space analysis in order to recall weak and strong Lagrangian duality results obtained through separation arguments. Finally, we interpret the shadow prices of the dual problem providing new definitions for risk aversion and non-satiability in the linear case.Multivariate risk measures, Vector Optimization, Lagrangian Duality, Shadow prices, Image Space Analysis.
Finite Element Analysis of Electromagnetic Waves in Two-Dimensional Transformed Bianisotropic Media
We analyse wave propagation in two-dimensional bianisotropic media with the
Finite Element Method (FEM). We start from the Maxwell-Tellegen's equations in
bianisotropic media, and derive some system of coupled Partial Difference
Equations (PDEs) for longitudinal electric and magnetic field components.
Perfectly Matched Layers (PMLs) are discussed to model such unbounded media. We
implement these PDEs and PMLs in a finite element software. We apply
transformation optics in order to design some bianisotropic media with
interesting functionalities, such as cloaks, concentrators and rotators. We
propose a design of metamaterial with concentric layers made of homogeneous
media with isotropic permittivity, permeability and magneto-electric parameters
that mimic the required effective anisotropic tensors of a bianisotropic cloak
in the long wavelength limit (homogenization approach). Our numerical results
show that well-known metamaterials can be transposed to bianisotropic media.Comment: 26 pages, 8 figure
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