The effect of hydrodynamics on the succession of autotrophic and heterotrophic organisms of biofilms in river ecosystems

Biofilms were cultivated for a 68-day period under different hydrodynamic conditions, and the effect of hydrodynamics on the succession of autotrophic and heterotrophic organisms of biofilms was investigated. Five obvious stages were observed during biofilm formation. At Stage I, the attachment of algae was delayed, especially under turbulent conditions. After Stage II, algal density and heterotrophic biomass of biofilms increased, which were obvious under turbulent flow. Therefore, the algal density and heterotrophic biomass of biofilms were largest under turbulent condition, followed by laminar condition, and then transitional condition. Diatoms were dominant in all flumes and were most abundant under turbulent conditions. The proportion of cyanobacteria was highest under laminar conditions. The ratio of aerobic to anaerobic bacteria decreased and their co-existence could facilitate the nitrification and denitrification in the biofilm. The ratio of monounsaturated fatty acids to saturated fatty acids was highest under turbulent conditions on the 15th day. While the ratio was highest under laminar condition on the 48th day, the high ratio indicates the high ability of biofilm to obtain nutrients, which affect the growth of algae. The regulation of hydrodynamics is a useful technology which can affect the growth of the microorganisms of biofilm, and further improve water quality.

Understanding online anonymity

Whenever we navigate the Web, we leave a trace through our IP address, which can in turn be used to establish our identity – for instance, by cross-checking it with a user’s Internet subscription. By using software such as VPN and Tor, however, it might be possible to avoid leaving such traces. A lively debate among policymakers, security professionals, hacker communities, and human rights associations has recently ensued regarding the question if such anonymity is acceptable and in which form. This article introduces the Crosscurrent special section dedicated to this topic by providing a brief overview of this debate and by pointing to the necessity of considering online anonymity from multiple, interrelated perspectives. By taking into account both technical and social dimensions, we argue that online anonymity should not be conceptualized in absolute terms but as an inherently fluid and transitional condition that characterizes any kind of social interaction online.

NOMADISM AS A WAY OF BEING OF THE IMMIGRANTS AND INTERNALLY DISPLACED PERSONS

The article presents the innovatory understanding of the nomadic strategy of human being in the transitional condition. The aim of the article is to determine the role of the nomadic being way in the social group of internal migrants. It is substantiated, that aims and actions of a nomad are directed on creating new ways of realization and conceptualization of variants of nomadic being. It is explained, that a nomad doesn’t go by the way, offered by traditional types of activity, but searches innovatory ways of realization, doesn’t stop on deciphering of traditionally existing being senses, but produces them him/herself. A subject, living in a space of “boundaries” is deprived of the settled comfort, he/she searches for a possibility of balance and harmony, social recognition and improvement of own life conditions in the movement and change. The culture of choice, formed by the logic of the modern market, gives a nomad resources for regulating the own freedom degree. Nomadic instruments correspond to the migrants’ way of life. Digital nomadism creates stimuli for the active life and adaptation to new conditions of different groups of migrants.