746 research outputs found
Schumpeter's paradox reconsidered: The need for a theory of circular flow
This study focuses on the well-known theme of Schumpeter’s system of economic theory. Specifically, the study discusses Schumpeter’s paradoxical stance on Walras’ general equilibrium theory, which Louçã (1997) called Schumpeter’s paradox. We reconsider the significance of the notion of circular flow in business cycle theory, after recognising the continuity from static to dynamic theory, and then to business cycle theory that integrates these theories. In doing so, we focus on the fact that Schumpeter called the equilibrium in the cyclical process a circular flow or a stationary process and proposed his own concept of neighbourhoods of equilibrium, which was not found in Walras’ general equilibrium theory. Through such an analysis, we propose that Schumpeter’s paradox is eased to some degree and that the theory of circular
flow should be explored further
Simulations of Wide-Field Weak Lensing Surveys II: Covariance Matrix of Real Space Correlation Functions
Using 1000 ray-tracing simulations for a {\Lambda}-dominated cold dark model
in Sato et al. (2009), we study the covariance matrix of cosmic shear
correlation functions, which is the standard statistics used in the previous
measurements. The shear correlation function of a particular separation angle
is affected by Fourier modes over a wide range of multipoles, even beyond a
survey area, which complicates the analysis of the covariance matrix. To
overcome such obstacles we first construct Gaussian shear simulations from the
1000 realizations, and then use the Gaussian simulations to disentangle the
Gaussian covariance contribution to the covariance matrix we measured from the
original simulations. We found that an analytical formula of Gaussian
covariance overestimates the covariance amplitudes due to an effect of finite
survey area. Furthermore, the clean separation of the Gaussian covariance
allows to examine the non-Gaussian covariance contributions as a function of
separation angles and source redshifts. For upcoming surveys with typical
source redshifts of z_s=0.6 and 1.0, the non-Gaussian contribution to the
diagonal covariance components at 1 arcminute scales is greater than the
Gaussian contribution by a factor of 20 and 10, respectively. Predictions based
on the halo model qualitatively well reproduce the simulation results, however
show a sizable disagreement in the covariance amplitudes. By combining these
simulation results we develop a fitting formula to the covariance matrix for a
survey with arbitrary area coverage, taking into account effects of the
finiteness of survey area on the Gaussian covariance.Comment: 12 pages, 12 figures, accepted for publication in the Astrophysical
Journal. Simulation data (1000 convergence power spectra and cosmic shear
correlation functions for {\xi}+({\theta}) and {\xi}-({\theta})) are
available upon request (contact [email protected]
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