The Development of an Information Society and Electronic Commerce in the European Union in the Context of Selected Documents of the EU and International Organisations

In this article, the author presents selected documents on electronic commerce published by the United Nations Commission on International Trade Law, the World Trade Organization, the Organisation for Economic Cooperation and Development, the International Chamber of Commerce and the European Union since 1994.W niniejszym artykule autor prezentuje wybrane dokumenty dotyczące handlu elektronicznego opublikowane przez Komisję ONZ ds. Prawa Handlu Międzynarodowego, Światową Organizację Handlu OECD, Międzynarodową Izbę Handlu oraz Unię Europejską od roku 1994

Prediction of force coefficients for labyrinth seals

The development of a linear model for the prediction of labyrinth seal forces and on its comparison to available stiffness data is presented. A discussion of the relevance of fluid damping forces and the preliminary stages of a program to obtain data on these forces are examined. Fluid-dynamic forces arising from nonuniform pressure patterns in labyrinth seal glands are known to be potentially destablizing in high power turbomachinery. A well documented case in point is that of the space Shuttle Main Engine turbopumps. Seal forces are also an important factor for the stability of shrouded turbines, acting in that case in conjunction with the effects of blade-tip clearance variations

Correlating Cell Shape and Cellular Stress in Motile Confluent Tissues

Collective cell migration is a highly regulated process involved in wound healing, cancer metastasis and morphogenesis. Mechanical interactions among cells provide an important regulatory mechanism to coordinate such collective motion. Using a Self-Propelled Voronoi (SPV) model that links cell mechanics to cell shape and cell motility, we formulate a generalized mechanical inference method to obtain the spatio-temporal distribution of cellular stresses from measured traction forces in motile tissues and show that such traction-based stresses match those calculated from instantaneous cell shapes. We additionally use stress information to characterize the rheological properties of the tissue. We identify a motility-induced swim stress that adds to the interaction stress to determine the global contractility or extensibility of epithelia. We further show that the temporal correlation of the interaction shear stress determines an effective viscosity of the tissue that diverges at the liquid-solid transition, suggesting the possibility of extracting rheological information directly from traction data.Comment: 12 pages, 9 figure

We want to sort! Assessing households' preferences for sorting waste

Support of Polish Ministry of Science and Higher Education as well as Foundation for Polish Science is gratefully acknowledged.There are two major ways in which solid waste can be sorted and recycled - at the household level, when households are required to sort waste into a given number of categories, or in specialised sorting facilities. Traditionally, it has been thought that sorting at the household level is an inconvenience, as it uses space and requires time and effort. Our study provides empirical evidence to the contrary, indicating that home sorting is a net source of utility for some people. Through a carefully designed choice experiment we collected stated choices from members of a Polish municipality with respect to the way their waste is sorted and how often it is collected. In the hypothetical scenario employed, respondents were informed that waste will be sorted anyway - if not at the household level then at a specialised sorting facility. Interestingly, analysis shows that a large group of people are willing to sort waste at the household level even if unsorted waste would be collected at no extra cost. For a minority, increased home sorting of waste would, however, impose a loss of utility. Overall, our results indicate that most respondents preferred to sort waste themselves if given the choice. We provide a few possible explanations of this perhaps surprising result, including the desire to promote a green external image, and a concern about the effectiveness of separation activities performed by others.PostprintPeer reviewe