In the period 1950* 2020, international migration in Europe changed significantly. One of the most char-- acteristic features was the change in net migration from negative to positive. At the beginning of the twenty first century, Poland belonged to the minority of countrie s in this respect that is, it experienced strong emigration but only minor immigration. However, migration in Poland has also been changing. In the second decade of this century, the outflow of people has weakened, the inflow of migrants has increased an d the migration balance has become positive. I analyse these phenomena from the theoretical perspective of the migration transition that was experienced in the second half of the twentieth century by most countries in Western, Northern and Southern Europe. I attempt to answer the question of whether the latest migration phenomena prove that this transition is also occurring in Poland. In conclusion, I argue that the available toKeywords: migra date evidence provides an affirmative answer to this question.

This article is about the Brazilian aid programme called Programa Bolsa Família. The programme has generated the interest of international institutions, the media, and the academic world on account of its scale, which provides an opportunity for fundamental social reform; and its measurable success, which is clearly visible in the poverty statistics; and above all, on account of participation being dependent on the fulfillment of specific requirements in the field of education, health, and social care. The author undertakes to go beyond an analysis based on statistics and to look at the functioning of the programme from the level of the participants. On the basis of his own research—that is, freely-conducted interviews with the inhabitants of favelas and rural settlements—he describes what lies behind the terminology and poverty statistics. His analysis of the situation of over a dozen participants in the programme makes it possible to see the immediate improvement of their material situation; the author claims, however, that a complete diagnosis will be possible only after the passage of a dozen or more years, by comparing the human capital (and labor market position) of the children of families taking part in the programme with the socio-economic position of those families today.

The paper presents the mathematical modelling of selected isothermal separation processes of gaseous mixtures, taking place in plants using membranes, in particular nonporous polymer membranes. The modelling concerns membrane modules consisting of two channels - the feeding and the permeate channels. Different shapes of the channels cross-section were taken into account. Consideration was given to co-current and counter-current flows, for feeding and permeate streams, respectively, flowing together with the inert gas receiving permeate. In the proposed mathematical model it was considered that pressure of gas changes along the length of flow channels was the result of both - the drop of pressure connected with flow resistance, and energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel. The literature on membrane technology takes into account only the drop of pressure connected with flow resistance. Consideration given to energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel constitute the essential novelty in the current study. The paper also presents results of calculations obtained by means of a computer program which used equations of the derived model. Physicochemical data concerning separation of the CO2/CH4 mixture with He as the sweep gas and data concerning properties of the membrane made of PDMS were assumed for calculations.