Age problem in holographic dark energy

We study the age problem of the universe with the holographic DE model introduced in [21], and test the model with some known old high redshift objects (OHRO). The parameters of the model have been constrained using the SNIa, CMB and BAO data set. We found that the age of the old quasar APM 08 279+5255 at z = 3.91 can be described by the model.Comment: 13 page

The 2010 August 01 type II burst: A CME-CME Interaction, and its radio and white-light manifestations

We present observational results of a type II burst associated with a CME-CME interaction observed in the radio and white-light wavelength range. We applied radio direction-finding techniques to observations from the STEREO and Wind spacecraft, the results of which were interpreted using white-light coronagraphic measurements for context. The results of the multiple radio-direction finding techniques applied were found to be consistent both with each other and with those derived from the white-light observations of coronal mass ejections (CMEs). The results suggest that the Type II burst radio emission is causally related to the CMEs interaction.Comment: 7 pages, 6 figures, Accepted to ApJ: January 16, 201

Borsuk and V\'azsonyi problems through Reuleaux polyhedra

The Borsuk conjecture and the V\'azsonyi problem are two attractive and famous questions in discrete and combinatorial geometry, both based on the notion of diameter of a bounded sets. In this paper, we present an equivalence between the critical sets with Borsuk number 4 in $\mathbb{R}^3$ and the minimal structures for the V\'azsonyi problem by using the well-known Reuleaux polyhedra. The latter lead to a full characterization of all finite sets in $\mathbb{R}^3$ with Borsuk number 4. The proof of such equivalence needs various ingredients, in particular, we proved a conjecture dealing with strongly critical configuration for the V\'azsonyi problem and showed that the diameter graph arising from involutive polyhedra is vertex (and edge) 4-critical

Houston needs a mountain: Towards a new monumentality

Garbage is a global problem. In Texas, soft regulations and landfill closures have made way for the dawn of the mega landfill. The reduction of landfill locations multiplied by extreme suburban sprawl, has forced the landfills to take on a vertical mountainous form to accommodate consumption and land boundaries. Such a metamorphosis has spawned coalitions to fight against the visual and sensory upheavals growing in their own communities; ironically it is only due to their own making. This thesis looks at three new paradigms of garbage organization and disposal that produce alternatives and finds positivity in the inevitable we already face

Acknowledgement of priority - A fractional Helly theorem for boxes

In our recent paper [1] we prove a fractional Helly type theorem for boxes in Rd. This short note is to acknowledge priority: in 1980 Meir Katchalski [4] proved exactly the same result and in 1988 Jürgen Eckhoff [2] proved the same result in much more generality. In fact, Eckhoff established an upper bound theorem for the f -vectors of finite families of boxes in Rd from which his result is derived. Besides apologies for our ignorance we would like to mention that Eckhoff extended his results further in a more recent paper [3]