Urban green spaces (UGS) play an important role in the structure of urbanized areas. Providing adequate access to them may contribute to shaping more pro-health behaviours among city residents. There are many proven benefits of access to UGS. They can have a significant impact on improving mental and physical health. The proximity of green areas in a city has a positive impact on basic environmental indicators: they improve air quality, contribute to reducing the urban heat island effect and are places conducive for socializing. In a world dominated by cars and a sedentary lifestyle, it is difficult to find time to be physically active. Therefore, the presence of park spaces can significantly affect the provision of the required minimum levels of physical activity. The subject of interest of this article is a review of selected academic publications, whose authors attempted to create objective tools for measuring the accessibility of green spaces in an urban environment. The study contains a tabular list of selected research methods and defines the basic purpose of each study and data source. Green area accessibility indices can be an important tool in shaping the spatial policy of cities. Summarizing the academic achievements in this field may constitute an incentive to conduct research of a similar nature and significance in Poland. Effective mapping of accessibility indices may become a clear tool for communication between local governments responsible for making key decisions in cities and the Polish academic community.

Being more sensitive to economic fluctuations, childbearing postponement increased during the second demographic transition and was accompanied by a moderate decline in the number of children per woman and the progressive rise of mother’s age at first birth. Under the hypothesis that recessions have a marked influence on population dynamics, the present study investigates spatial changes in mother’s age at birth in Greece with the aim to assess the differential impact of economic crisis along the urban-rural gradient. The percent composition of births by mother's age class – considered a gross indicator of fertility under a changing socioeconomic context – was studied at 4 spatial scales (the whole country, administrative regions, prefectures and metropolitan areas or specific economic districts) over an economic cycle from expansion to recession (1980–2016). While stimulating childbearing postponement observed since the early 1980s, empirical results of this study indicate that the 2007 recession was quite neutral on fertility trends in Greece, consolidating the traditional divide between urban and rural areas.

Mineral markets, in spite of many common features with other goods markets, are distinctive. Their functioning sometimes deviates from the rules of the free market. This feature results from the specificity of acquiring the good being an object of trade. In general, changes in the supply of strategic raw materials are indicated earlier (characterized by a lengthy investment cycle from deposit reconnaissance to mining development), develop slowly, andare inelastic. Demand for common mineral raw materials often has a clear and economic character. However, mineral markets as well as markets of other goods have a common feature - the fact that both are a place where an incessant game is being played. In general, two types of strategic behaviours are distinguished: competition or cooperation. This paper recalls an existing model known as the oil market game. Based on a three-entity market of aggregate producers, an attempt has been made to model entrepreneurs' behaviour. The analysis applies n-person game theory. Game theory enables the evaluation of diverse potential coalitions forming. Possible strategies of activity coming from the prospect of cooperation (or its omission) are presented. Expected payoffs are estimated for possible alliances. Proposals for the division of the payoffs among the participants forming the coalition are also suggested.

The paper presents a description of selected models dedicated to steam condensing flow modelling. The models are implemented into an in-house computational fluid dynamics code that has been successfully applied to wet steam flow calculation for many years now. All models use the same condensation model that has been validated against the majority of available experimental data. The state equations for vapour and liquid water, the physical model as well as the numerical techniques of solution to flow governing equations have been presented. For the single-fluid model, the Reynolds-averaged Navier-Stokes equations for vapour/liquid mixture are solved, whereas the two-fluid model solves separate flow governing equations for the compressible, viscous and turbulent vapour phase and for the compressible and inviscid liquid phase. All described models have been compared with relation to the flow through the Laval nozzle.

Four new Antarctic holothuroid species are described for specimens from Admiralty Bay in King George Island. A new genus Dendrelasia O’Loughlin is erected for new cucumariid species Dendrelasia sicinski with dendrochirotid body form and elasipodid type spinous rod ossicles. Cucumariid Staurocucumis krzysztofi has bowl ossicles predominantly with marginal teeth. Provisionally−assigned thyonid Allothyone presleri has table ossicles with spires comprising predominantly four pillars. Molpadiid Molpadia magdae has a prickly cover of irregular table ossicle spires and fusiform table discs in both body wall and tail. Staurocucumis liouvillei (Vaney) is a “species complex”.