SZ scaling relations in Galaxy Clusters: results from hydrodynamical N-body simulations

Observations with the SZ effect constitute a powerful new tool for investigating clusters and constraining cosmological parameters. Of particular interest is to investigate how the SZ signal correlates with other cluster properties, such as the mass, temperature and X-ray luminosities. In this presentation we quantify these relations for clusters found in hydrodynamical simulations of large scale structure and investigate their dependence on the effects of radiative cooling and pre-heating.Comment: 10 pages, 3 figures, LaTeX. To appear in proceedings of the JENAM 2002 conference. For a more detailed analysis see astro-ph/0308074, whose simulations supersede those presented at this conferenc

A stochastic spreadsheet model analysing investment options for the development of pasture on beef cattle farms : a dissertation submitted in partial fulfilment of the requirements for the degree of Master in Applied Science at Massey University

The decision to proceed with farm development to increase animal production is complex. Standalone personal computer software to study either the financial or physical aspects of farm development is available, but models which integrate these components and account for the risks associated with the investment are not. A stochastic spreadsheet (Microsoft Excel®) model was therefore developed to predict the profitability, feasibility and risk of pasture development for two case farms: one in southern Brazil and the other near Wanganui in New Zealand. Pasture was developed at different rates for each farm and the model was used to predict the associated physical and financial changes over-time and a probability distribution of the net present values (NPV) of the net operating profit after tax and before interest (NOPAT) relative to the status quo situation. The extra pasture was used solely for increasing beef cattle production. On the Brazilian case farm the development of 2,263 ha at two rates was studied. The continuation of the status quo had first degree stochastic dominance in terms of the NPV over both development rates; it was superior by about NZ$46.000 for the 200 ha/y option and ca. NZ$ 110.000 for the 500 ha/y option at a 16% discount rate. However, at a 6% discount rate the 500 ha/y development rate had first degree stochastic dominance in terms of the NPV over both the continuation of the status quo (by about NZ$960.000) and the 200 ha/y option (ca. NZ$ 120.000). This indicates that pasture development could proceed profitability if interest rates continue to fall in Brazil as predicted. For the New Zealand case farm the development of 247 ha at 50 ha/y had first degree stochastic dominance over the 25 ha/y (ca. NZ$24,000) and continuation of the status quo (ca. NZ$ 208.000) at a 6% discount rate. Pasture development should therefore continue. Stochastic analysis of the pasture development investment options gave a better insight into the likely outcomes for a project, and provides the farmer with more information for making a decision on whether, and how. to proceed with farm development. The model could easily be adapted for studying farm development with respect to other types of livestock enterprises Keywords: pastures, development, risk, feasibility, profitability, model

OPTIMAL INTERNATIONAL RESERVES HOLDINGS IN EMERGING MARKETS ECONOMIES: THE BRAZILIAN CASE

This paper discusses the optimal international reserves holding for Brazilian economy. The optimal is determined with the buffer stock (inventory) model, using a time series approach. This paper differs from traditional approaches that run cross-section analysis. We evaluate Brazilian's reserves holdings with the model and discuss the role of IMF accord in the reserves holdings. The paper also presents evidence to support the idea of fewer needs to hold international reserves in a floating foreign exchange rate regime than in a fixed one. Conclusions highlight that Brazilians' foreign reserves are slightly above the optimal level and the model may allow the country to evaluate the needs of IMF accord renew.

Model studies of fluctuations in the background for jets in heavy ion collisions

Jets produced in high energy heavy ion collisions are quenched by the production of the quark gluon plasma. Measurements of these jets are influenced by the methods used to suppress and subtract the large, fluctuating background and the assumptions inherent in these methods. We compare the measurements of the background in Pb+Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV by the ALICE collaboration to calculations in TennGen (a data-driven random background generator) and PYTHIA Angantyr. The standard deviation of the energy in random cones in TennGen is approximately in agreement with the form predicted in the ALICE paper, with deviations of 1-6 $\%$. The standard deviation of energy in random cones in Angantyr exceeds the same predictions by approximately 40 $\%$. Deviations in both models can be explained by the assumption that the single particle $d^2N/dydp_T$ is a Gamma distribution in the derivation of the prediction. This indicates that model comparisons are potentially sensitive to the treatment of the background