Properties of holographic dark energy at the Hubble length

We consider holographic cosmological models of dark energy in which the infrared cutoff is set by the Hubble's radius. We show that any interacting dark energy model, regardless of its detailed form, can be recast as a non interacting model in which the holographic parameter $c^{2}$ evolves slowly with time. Two specific cases are analyzed. We constrain the parameters of both models with observational data, and show that they can be told apart at the perturbative level.Comment: 4 pages, 6 figures. Contribution to the Proceedings ERE201

Estimation of the Tropical Cyclone Diurnal Cycle Using Simulated Observations from the NASA TROPICS Earth Venture Mission

No abstract availabl

Holographic dark energy described at the Hubble length

We consider holographic cosmological models of dark energy in which the infrared cutoff is set by the Hubble's radius. We show that any interacting dark energy model with a matter like term able to alleviate the coincidence problem (i.e., with a positive interaction term, regardless of its detailed form) can be recast as a noninteracting model in which the holographic parameter evolves slowly with time. Two specific cases are analyzed. First, the interacting model presented in [1] is considered, and its corresponding noninteracting version found. Then, a new noninteracting model, with a specific expression of the time-dependent holographic parameter, is proposed and analyzed along with its corresponding interacting version. We constrain the parameters of both models using observational data, and show that they can be told apart at the perturbative level.Comment: 15 pages, 6 figure

Estimating the Impact of Highways on Average Travel Velocities and Market Size

In this paper we examine the link between additions to highway infrastructure and development of a market area. We do so by first relating highway travel speeds to added highway-mileage and then relating travel speed to the size of the market area. This approach bypasses issues in the public finance literature that derive from estimates of highway infrastructure spending. Also, rather than examining the effects of improved transportation efficiency on enhancements of productivity, this research examines their effect on enhancements in demand for local production. Our thought, which is borne out in the literature, is that industry-level productivity in a metropolitan area may be improved only marginally by lower delivered prices of inputs due to very localized improvements in the freight transportation system. On the other hand, the market for locally produced goods and services will expand somewhat uniformly across industries due to generally improved traffic movements in a metropolitan area. By applying this approach to data from the Texas Transportation Institute, we find a significant but small positive effect of highways and arterials (as opposed to other roadways) on changes in metropolitan urbanized area and metropolitan population change. This suggests that demand for local production may well be enhanced by expansions of highway and principal arterials infrastructure.

Radial Solutions for Hamiltonian Elliptic Systems with Weights

We prove the existence of infinitely many radial solutions for elliptic systems in Rn with power weights. A key tool for the proof will be a weighted imbedding theorem for fractional-order Sobolev spaces, that could be of independent interest.Comment: 13 page

Three Essays on Women\u27s Land Rights in Rural Peru

This dissertation investigates the relationship between female land rights and cultural, policy, and regional variables, and asks to what degree, and in what ways, the highly contextual nature of the relationships between these variables have determined local-specific causes and effects of female land rights in Peru. This dissertation consists of three essays. The first essay provides the socioeconomic and institutional context for the entire dissertation, introducing a brief historical account of the evolution of female land rights in Peru. This essay pays particular attention to the relationship between property rights and geographical context in the Peruvian countryside, examining the region-specific institutional, social, cultural and economic obstacles that prevent women, particularly in rural areas, from having adequate access to and secure tenure of land. The second essay models the varying patterns of female land ownership in Peru, identifying the main factors that have bearing on women’s acquisition of land, relevant to explain the magnitude and characteristics of the gender-asset gap in Peru. This essay empirically estimates the determinants of female land ownership, and in particular the effect of household wealth and geographic location on women’s likelihoods to acquire formal land rights. Lastly, the third essay tests the hypothesis that land ownership gives women more bargaining power in the household. This essay conducts an empirical evaluation of the effects of female land rights on labor supply decisions of couples in the Peruvian rural household setting. This essay brings to light the complex effects of partnered women’s bargaining power on time use including labor supply in paid employment, which varies in connection with the specific characteristics of female land rights and the size of the farm. By comparing the main features of farm organization in minifundios (farms between ¼ and 3½ hectares) versus small farms (between 3½ and 10 hectares), this essay shows that the differences in the time allocation patterns of couples in these two farm size categories largely emanate from differences (in determinants and characteristics) in women’s land rights

Parabolic dunes in north-eastern Brazil

In this work we present measurements of vegetation cover over parabolic dunes with different degree of activation along the north-eastern Brazilian coast. We are able to extend the local values of the vegetation cover density to the whole dune by correlating measurements with the gray-scale levels of a high resolution satellite image of the dune field. The empirical vegetation distribution is finally used to validate the results of a recent continuous model of dune motion coupling sand erosion and vegetation growth.Comment: 18 pages, 14 figures, aubmitted to Geomorpholog

Ripples in Tapped or Blown Powder

We observe ripples forming on the surface of a granular powder in a container submitted from below to a series of brief and distinct shocks. After a few taps, the pattern turns out to be stable against any further shock of the same amplitude. We find experimentally that the characteristic wavelength of the pattern is proportional to the amplitude of the shocks. Starting from consideration involving Darcy's law for air flow through the porous granulate and avalanche properties, we build up a semi-quantitative model which fits satisfactorily the set of experimental observations as well as a couple of additional experiments.Comment: 7 pages, four postscript figures, submitted PRL 11/19/9