17,852 research outputs found
Measuring H0 from the 6dF Galaxy Survey and future low-redshift surveys
Baryon acoustic oscillations (BAO) at low redshift provide a precise and
largely model-independent way to measure the Hubble constant, H0. The 6dF
Galaxy Survey measurement of the BAO scale gives a value of H0 = 67 +/- 3.2
km/s/Mpc, achieving a 1-sigma precision of 5%. With improved analysis
techniques, the planned WALLABY (HI) and TAIPAN (optical) redshift surveys are
predicted to measure H0 to 1-3% precision.Comment: Proceedings of IAU Symposium 289, "Advancing the Physics of Cosmic
Distances", Richard de Grijs & Giuseppe Bono (eds), 2012, 4p
The Collateral Channel under Imperfect Debt Enforcement
Does a country’s ability to enforce debt contracts affect the sensitivity of economic activity to collateral values? To answer this question, we introduce a novel industry-specific measure of real asset redeployability - the ease with which real assets are transfered to alternative uses - as a proxy for collateral liquidation values. Our measure exploits the heterogeneity of expenditures in new and used capital and the heterogeneity in the composition of real asset holdings across U.S. industries. Using a cross-industry cross-country approach, we find that industry size and growth are more sensitive to collateral values in countries with weaker debt enforcement. Our estimates indicate that the differential effect is sizeable. The sensitivity of economic activity to collateral values is not affected by a country’s financial development once the quality of debt enforcement is accounted for. We then rationalize our empirical findings based on a model of credit under imperfect enforcement and discuss an important implication of our empirical result: macroeconomic volatility generated by fluctuations in collateral values is higher in countries with weaker debt enforcement institutions.
Constraining the relative velocity effect using the Baryon Oscillation Spectroscopic Survey
We analyse the power spectrum of the Baryon Oscillation Spectroscopic Survey
(BOSS), Data Release 12 (DR12) to constrain the relative velocity effect, which
represents a potential systematic for measurements of the Baryon Acoustic
Oscillation (BAO) scale. The relative velocity effect is sourced by the
different evolution of baryon and cold dark matter perturbations before
decoupling. Our power spectrum model includes all -loop redshift-space terms
corresponding to parameterised by the bias parameter . We
also include the linear terms proportional to the relative density,
, and relative velocity dispersion, , which
we parameterise with the bias parameters and . Our data does not support a detection of the relative velocity
effect in any of these parameters. Combining the low and high redshift bins of
BOSS, we find limits of , and with () confidence levels. These constraints
restrict the potential systematic shift in , and ,
due to the relative velocity, to , and , respectively. Given
the current uncertainties on the BAO measurements of BOSS these shifts
correspond to , and for ,
and , respectively
Enzyme Replacement in Gaucher Disease
The development of enzyme replacement therapy for Gaucher disease was a triumph of translational medicine. What were the key steps in its development? What are the controversies surrounding its use
Extending the modeling of the anisotropic galaxy power spectrum to
We present a new model for the redshift-space power spectrum of galaxies and
demonstrate its accuracy in modeling the monopole, quadrupole, and hexadecapole
of the galaxy density field down to scales of .
The model describes the clustering of galaxies in the context of a halo model
and the clustering of the underlying halos in redshift space using a
combination of Eulerian perturbation theory and -body simulations. The
modeling of redshift-space distortions is done using the so-called distribution
function approach. The final model has 13 free parameters, and each parameter
is physically motivated rather than a nuisance parameter, which allows the use
of well-motivated priors. We account for the Finger-of-God effect from centrals
and both isolated and non-isolated satellites rather than using a single
velocity dispersion to describe the combined effect. We test and validate the
accuracy of the model on several sets of high-fidelity -body simulations, as
well as realistic mock catalogs designed to simulate the BOSS DR12 CMASS data
set. The suite of simulations covers a range of cosmologies and galaxy bias
models, providing a rigorous test of the level of theoretical systematics
present in the model. The level of bias in the recovered values of
is found to be small. When including scales to ,
we find 15-30\% gains in the statistical precision of relative to
and a roughly 10-15\% improvement for the
perpendicular Alcock-Paczynski parameter . Using the BOSS DR12
CMASS mocks as a benchmark for comparison, we estimate an uncertainty on that is 10-20\% larger than other similar Fourier-space RSD
models in the literature that use , suggesting
that these models likely have a too-limited parametrization.Comment: Submitted to JCA
On a new approach to the analysis of stationary inventory problems
The intent of this paper is to demonstrate that the theory of stationary point processes is a useful tool for the analysis of stationary inventory systems. In conventional inventory theory, the equilibrium distributions for a specified inventory policy are obtained, whenever possible, by recursive or limiting procedures, or both. A different and more direct approach, based on stationary point processes, is proposed here. The time instants at which stock delivery is effected are viewed as points of the stationary point process, which possesses uniform statistical properties on the entire real axis; hence the equilibrium statistics of the inventory process can be calculated directly. In order to best illustrate this approach, various examples are given, including some that constitute new results.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100322/1/3800160101_ftp.pd
The Perspective of Cow/Calf Producers in the Dakotas: Mandatory Price Reporting for Slaughter Cattle
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