This article aims at verifying the findings by Richard g. Wilkinson and Kate e. Pickett (2009) which point to a strong correlation between the income gap and the escalation of social problems. Wilkinson and Pickett’s thesis, described here as ‘the Spirit level concept’, states that all kinds of social problems (ranging from drug abuse to lack of trust among people) are directly connected with the scale of social inequality in a given country. In this article we test this concept by analyzing the relation between the income gap in a particular country and four important problems: health condition, trust, social activity and cultural activity. We investigate this relation in european union countries.

A Stirling cycle was developed by Rallis considering the adiabatic behaviour instead of isothermal behaviour of working fluid inside the expansion/compression volume, since the isothermal processes are very difficult to be realised in actual practice due to irreversibilities. In order to increase the performance of Rallis Stirling cycle engine, two modified versions of Rallis Stirling cycle engine model have been proposed and developed, called as Rallis modified Stirling cycle engine (RMSE). In this paper, the thermodynamic analysis of the developed models have been carried out and the simulated results are compared with the Rallis ideal model of Stirling cycle engine, as this model describes more accurately the thermodynamic cycle of practical Stirling machines. The results reveal the fact that the thermal efficiency of RMSE I model is enhanced by 38.06% and that of RMSE II model by 48.42%, whereas the power output is increased by 58.05% and 78.19% in case of RMSE I and RMSE II model respectively, when compared with the Rallis ideal adiabatic model of Stirling engine.