Matching and Independence Complexes Related to Small Grids

The topology of the matching complex for the $2\times n$ grid graph is mysterious. We describe a discrete Morse matching for a family of independence complexes $\mathrm{Ind}(\Delta_n^m)$ that include these matching complexes. Using this matching, we determine the dimensions of the chain spaces for the resulting Morse complexes and derive bounds on the location of non-trivial homology groups for certain $\mathrm{Ind}(\Delta_n^m)$. Further, we determine the Euler characteristic of $\mathrm{Ind}(\Delta_n^m)$ and prove that several homology groups of $\mathrm{Ind}(\Delta_n^m)$ are non-zero

Charmonium Production from the Secondary Collisions at LHC Energy

We consider the charmonium production in thermalized hadronic medium created in ultrarelativistic heavy ion collisions at LHC energy. The calculations for the secondary $J/\psi$ and $\psi^,$ production by $D\bar D$ annihilation are performed within a kinetic model taking into account the space-time evolution of a longitudinally and transversely expanding medium. We show that the secondary charmonium production appears almost entirely during the mixed phase and it is very sensitive to the charmonium dissociation cross section with co-moving hadrons. Within the most likely scenario for the dissociation cross section of the $J/\psi$ mesons their regeneration in the hadronic medium will be negligible. The secondary production of $\psi^,$ mesons however, due to their large cross section above the threshold, can substantially exceed the primary yield.Comment: ps file 11

Statistical hadronization of charm at SPS, RHIC and LHC

We study the production of charmonia and charmed hadrons for nucleus-nucleus collisions at SPS, RHIC, and LHC energies within the framework of the statistical hadronization model. Results from this model are compared to the observed centrality dependence of J/psi production at SPS energy. We further provide predictions for the centrality dependence of the production of open and hidden charm mesons at RHIC and LHC.Comment: Contribution to Quark Matter 2002, 4 pages, 3 figures; revised version including charmed hyperons (omitted in v1

Particle Production in Heavy Ion Collisions

The status of thermal model descriptions of particle production in heavy ion collisions is presented. We discuss the formulation of statistical models with different implementation of the conservation laws and indicate their applicability in heavy ion and elementary particle collisions. We analyze experimental data on hadronic abundances obtained in ultrarelativistic heavy ion collisions, in a very broad energy range starting from RHIC/BNL ($\sqrt s=200$ A GeV), SPS/CERN ($\sqrt s\simeq 20$ A GeV) up to AGS/BNL ($\sqrt s\simeq 5$ A GeV) and SIS/GSI ($\sqrt s\simeq 2$ A GeV) to test equilibration of the fireball created in the collision. We argue that the statistical approach provides a very satisfactory description of experimental data covering this wide energy range. Any deviations of the model predictions from the data are indicated. We discuss the unified description of particle chemical freeze--out and the excitation functions of different particle species. At SPS and RHIC energy the relation of freeze--out parameters with the QCD phase boundary is analyzed. Furthermore, the application of the extended statistical model to quantitative understanding of open and hidden charm hadron yields is considered.Comment: Invited review for Quark Gluon Plasma 3, eds. R. C. Hwa and Xin-Nian Wang, World Scientific Publishin

Unitarity of the tree approximation to the Glauber AA amplitude for large A

The nucleus-nucleus Glauber amplitude in the tree approximation is studied for heavy participant nuclei. It is shown that, contrary to previous published results, it is not unitary for realistic values of nucleon-nucleon cross-sections.Comment: 15 pages, 1 figure, 1 table. Submitted to Yad. Fi

Global Climate Change and Catholic Responsibility: Facts and Faith Response

Citation: Braun G, Hellwig MK, Byrnes WM (2007) Global Climate Change and Catholic Responsibility: Facts and Faith Response. Journal of Catholic Social Thought 4(2): 373-401. Abstract: The scientific evidence is now overwhelming that human activity is causing the Earth’s atmosphere to grow hotter, which is leading to global climate change. If current rates of greenhouse gas (GHG) emissions continue, it is predicted that there will be dramatic changes, including flooding, more intense heat waves and storms, and an increase in disease. Indigenous peoples and the poor will be most severely affected, as will Earth’s wild animals and plants, a quarter of which could become extinct in fifty years. We urgently need to switch to renewable (non-GHG emitting) energy sources, and try to live in a simpler, more sustainable way. In this article, a renewable energy expert, a biochemist, and a theologian have come together to describe the situation in which we find ourselves, and present ideas for a solution that incorporates Catholic social teaching

The promises and challenges of biofuels for the poor in developing countries: IFPRI 2005-2006 Annual Report Essay

"In the past several years the changing world energy situation has generated intensive discussion about biofuels, much of it promising a source of environment-friendly energy that would also be a boon to the world's farmers. At the same time skeptics argue that biofuel production will threaten food supplies for the poor and fail to achieve the environmental benefits claimed. Based on the analyses below, we conclude that in order to make a difference in the lives of poor people as both energy producers and consumers, and to make strong environmental and economic contributions, biofuel technology needs further advancement, and investments and policies facilitating agricultural innovation and trade will have to be considered." from TextBiofuels, Poor Developing countries, Small farmers,