Infall near clusters of galaxies: comparing gas and dark matter velocity profiles

We consider the dynamics in and near galaxy clusters. Gas, dark matter and galaxies are presently falling into the clusters between approximately 1 and 5 virial radii. At very large distances, beyond 10 virial radii, all matter is following the Hubble flow, and inside the virial radius the matter particles have on average zero radial velocity. The cosmological parameters are imprinted on the infall profile of the gas, however, no method exists, which allows a measurement of it. We consider the results of two cosmological simulations (using the numerical codes RAMSES and Gadget) and find that the gas and dark matter radial velocities are very similar. We derive the relevant dynamical equations, in particular the generalized hydrostatic equilibrium equation, including both the expansion of the Universe and the cosmological background. This generalized gas equation is the main new contribution of this paper. We combine these generalized equations with the results of the numerical simulations to estimate the contribution to the measured cluster masses from the radial velocity: inside the virial radius it is negligible, and inside two virial radii the effect is below 40%, in agreement the earlier analyses for DM. We point out how the infall velocity in principle may be observable, by measuring the gas properties to distance of about two virial radii, however, this is practically not possible today.Comment: 7 pages, 3 figures, to appear in MNRA

Knowledge in process? Exploring barriers between epidemiological research and local health policy development

The Redes de Trueque (RT) thrived during the economic crisis of 2001 – 2002 in Argentina and still stand out as one of the largest Complementary Currency System in the world. These local exchange networks reach a large scale during times of severe economic distress, but as large non-state initiatives, they pose a governance problem. Four types of governance systems were structured within the Argentine RT, of varying degrees of sustainability: a) loosely regulated market systems, b) hierarchies, c) associational regional networks, and d) local communities. Based on a four dimensional analytical framework, this paper discusses the rules of governance and sustainability of the governance systems in the RT. It found that some became more sustainable than others in terms of achieving combinations of scale and organisational modes

Price vs Quantity in Duopoly Supergames with Close Substitutes

We model the non-cooperative choice between quantity and price in order to stabilize collusion with horizontally differentiated goods, through two meta-games where each firm alternatively considers its payoff in the market supergame as directly related to its own or the rivals ability to collude. In the first setting, firms collude in prices irrespective of the degree of differentiation, so that initially a Prisoners Dilemma is observed, while for very close substitutes the outcome is Pareto-efficient. In the second setting, the Nash equilibrium is unique and Pareto-efficient for the most part of the substitutability range, while two asymmetric equilibria obtain when products are very close substitutes

Making better use of information to drive improvement in local public services: A report for the Audit Commission

This report on making better use of information to drive improvement in local public services was commissioned from the School of Public Policy at the University of Birmingham, by the Audit Commission. It explores how decision makers use information when making decisions. These decision makers can be politicians, top managers, operational managers, planners etc. The focus of this report is not on the use of performance indicators sensu stricto, but on the use of information more generally. Rather than studying how existing information is used or not used in decision making, this report is looking at how decision makers go about searching, analysing, summarising, processing and interpreting information when they need to make a decision. The report consists of three main chapters. - A summary of key government policy initiatives in the UK to stimulate the use of information in decision making - A review of the relevant research literature. This is the main section of the report. In it, we review the role of information in decision making theories, the organisational and structural context of information use, and psychological factors in the use of information in decision making - A presentation of a number of international perspectives on the use of information in public sector decision makin

Climate Policy Innovation:Developing An Evaluation Perspective

A key dimension of the debate about policy innovation is the extent to which new policies achieve significant and lasting effects on the problems they purport to address. However, little is known about such effects. We break new ground by investigating how far current evaluation practices in a policy system with relatively ambitious climate policies – the European Union – identify the most effective (carbon-reducing) policies. We find that a small number of policy instruments are projected to deliver the lion’s share of emission reductions. Setting aside the special case of emissions trading, these instruments are not particularly innovative. If significant practical and political obstacles can be addressed, more (detailed) evaluations could enhance the evidence base and also the political prospects for delivering deeper emissions cuts through to 2050. An evaluation perspective could also offer a very different way to consider policy innovation dynamics