Initial spreading of low-viscosity drops on partially wetting surfaces

Liquid drops start spreading directly after brought into contact with a partial wetting substrate. Although this phenomenon involves a three-phase contact line, the spreading motion is very fast. We study the initial spreading dynamics of low-viscosity drops, using two complementary methods: Molecular Dynamics simulations and high-speed imaging. We access previously unexplored length- and time-scales, and provide a detailed picture on how the initial contact between the liquid drop and the solid is established. Both methods unambiguously point towards a spreading regime that is independent of wettability, with the contact radius growing as the square root of time

The influence of family and school On the constitution of the self during adolescence

In einer kulturvergleichenden Untersuchung wird ein theoretisches Modell zur Konstituierung des Selbst bei Jugendlichen, in Anlehnung an ein Modell von Kreutz (1989), empirisch geprüft. Schule und Familie als Institutionen und deren Interaktionsordnungen werden in ihrer Wirkung auf das Selbst von Jugendlichen untersucht. Grundlage der Prüfung waren Daten aus drei Stichprobenerhebungen einer Ost-West-Studie bei 12- bis 16jährigen Schuljugendlichen. Dabei konnte die Grundstruktur des Modells repliziert werden. (DIPF/Orig.)In a cross-cultural comparative study a theoretical model for the constitution of the self among adolescents is tested empirically; in this, the authors refer to a model developed by Kreutz (1989). School and family as institutions and networks of interaction are examined as to their impact on the self of adolescents. The investigation is based on data provided by three sample surveys which were part of an East/West study among 12- to 16 year- old students. In this, the basic structure of the model could be replicated. (DIPF/Orig.

Bubble formation during the collision of a sessile drop with a meniscus

The impact of a sessile droplet with a moving meniscus, as encountered in processes such as dip-coating, generically leads to the entrapment of small air bubbles. Here we experimentally study this process of bubble formation by looking through the liquid using high-speed imaging. Our central finding is that the size of the entrapped bubble crucially depends on the location where coalescence between the drop and the moving meniscus is initiated: (i) at a finite height above the substrate, or (ii) exactly at the contact line. In the first case, we typically find bubble sizes of the order of a few microns, independent of the size and speed of the impacting drop. By contrast, the bubbles that are formed when coalescence starts at the contact line become increasingly large, as the size or the velocity of the impacting drop is increased. We show how these observations can be explained from a balance between the lubrication pressure in the air layer and the capillary pressure of the drop

Telecommunication carrier selection under volume discounts: a case study.

During 2001 many of the European mobile phone markets have reached saturation, and hence mobile phone operators have shifted their attention from growth and market share to cutting costs. One way of doing so is to reduce spending on international calls which are routed via network operating companies (carriers). These carriers charge per call-minute for each destination and may use a joint business volume discount to price their services. We developed a software system that supports the decision of allocating destinations to carriers. The core of this system is a min-cost flow routine that is embedded in a branch-and-bound framework. Our system not only solves the operational problem to optimality, it is also capable of performing what-if analyses and sensitivity analysis. It has been implemented at a major telecommunication services provider. The main benefits realized are twofold: the business process of allocating carriers to destinations has been structured and the costs arising from routing international calls have significantly decreased.Selection; Case studies; Studies; Markets; Market; Costs; International; Companies; Software; Decision; Framework; Sensitivity; Processes;

Использование метода анализа иерархий для оценки факторов эффективности маркетингового менеджмента туристско-оздоровительных комплексов

Обосновывается целесообразность использования метода анализа иерархий для оценки факторов, способствующих повышению эффективности маркетингового менеджмента туристических предприятий.Обґрунтовується доцільність використання методу аналізу ієрархії для оцінювання чинників, які сприяють підвищенню ефективності маркетингового менеджменту туристичних підприємств.The expediency of applying the method of analysis of hierarchies for the estimation of the factors which provide the effectiveness of marketing management of tourist enterprises is grounded