273 research outputs found
CMBEASY:: an Object Oriented Code for the Cosmic Microwave Background
We have ported the cmbfast package to the C++ programming language to produce
cmbeasy, an object oriented code for the cosmic microwave background. The code
is available at www.cmbeasy.org. We sketch the design of the new code,
emphasizing the benefits of object orientation in cosmology, which allow for
simple substitution of different cosmological models and gauges. Both gauge
invariant perturbations and quintessence support has been added to the code.
For ease of use, as well as for instruction, a graphical user interface is
available.Comment: 7 pages, 5 figures, matches published version, code at
http://www.cmbeasy.or
Small Business Capitalization Patterns
This study investigates the initial capitalization and financing patterns of recently established (new) and established (old) small businesses in Iowa. Analysis of survey responses indicates that significant differences exist between these two groups of firms. Specifically, new firms are found to have relied more heavily on debt financing than old firms. This suggests that new firms with high debt loads are likely not to survive and become old firms
catena-poly[cyclohexane-1,4-diammonium[[dioxo(sulfato-kappa O-2,O \u27)uranium(VI)]-mu-sulfato]dihydrate]
The Effects of Hydrofluoric Acid Addition on the Hydrothermal Synthesis of Templated Uranium Sulfates
The effects of addition of a second acid source (HF) on the formation of uranium sulfates are described in this article. -- author-supplied description
Early Dark Energy Cosmologies
We propose a novel parameterization of the dark energy density. It is
particularly well suited to describe a non-negligible contribution of dark
energy at early times and contains only three parameters, which are all
physically meaningful: the fractional dark energy density today, the equation
of state today and the fractional dark energy density at early times. As we
parameterize Omega_d(a) directly instead of the equation of state, we can give
analytic expressions for the Hubble parameter, the conformal horizon today and
at last scattering, the sound horizon at last scattering, the acoustic scale as
well as the luminosity distance. For an equation of state today w_0 < -1, our
model crosses the cosmological constant boundary. We perform numerical studies
to constrain the parameters of our model by using Cosmic Microwave Background,
Large Scale Structure and Supernovae Ia data. At 95% confidence, we find that
the fractional dark energy density at early times Omega_early < 0.06. This
bound tightens considerably to Omega_early < 0.04 when the latest Boomerang
data is included. We find that both the gold sample of Riess et. al. and the
SNLS data by Astier et. al. when combined with CMB and LSS data mildly prefer
w_0 < -1, but are well compatible with a cosmological constant.Comment: 6 pages, 3 figures; references added, matches published versio
Structural diversity in organically templated uranium sulfates
The potential of organic amine templates to direct the synthesis of metal sulfate frameworks has been investigated. Eight novel uranyl sulfates have been prepared using a templated uranyl sulfate precursor under hydrothermal conditions. The topologis of the isolated phases vary from the molecular (0-D), to chains (1-D) to layered (2-D) frameworks. [N4C6H 22]2[(UO2)2(SO4) 6] (USO-10) is molecular or zero-dimensional. Two different types of onedimensional uranyl-containing chains have been observed. [N2C 4H12][UO2(H2O)(SO4) 2 (USO-3), [N2C5H14]-[UO 2(H2O)(SO4)2] (USO-4) and [N 2C3H12][UO2(H2O)(SO 4)2 (USO-9) contain chains based upon a [UO 2(SO4)4/2] backbone. [N2C 10H10][UO2(SO4)2· H2O (USO-6) and [N2C6H18][(UO 2)2(H2O)3(SO4) 3] (USO-7) contain chains based upon a [UO2(SO 4)3/3] backbone. Two layered or two-dimensional compounds, [N2C6H14][UO2(H2O) (SO4)2 (USO-5) and [N2C3H 5]2[(UO2)2(SO4) 3] (USO-8) have also been isolated. All the new phases have been characterised using a range of physical techniques including single crystal X-ray structure analysis. © The Royal Society of Chemistry 2003
Observational constraints on the dark energy density evolution
We constrain the evolution of the dark energy density from Cosmic Microwave
Background, Large Scale Structure and Supernovae Ia measurements. While
Supernovae Ia are most sensitive to the equation of state of dark energy
today, the Cosmic Microwave Background and Large Scale Structure data best
constrains the dark energy evolution at earlier times. For the parametrization
used in our models, we find and the dark energy fraction at very
high redshift at 95 per cent confidence level.Comment: 5 pages, 10 figure
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