Revisiting Individual Evolutionary Learning in the Cobweb Model – An Illustration of the Virtual Spite-Effect

We examine the Cournot oligopoly model in the context of social and individual learning. In both models of learning, firms update their decisions about how much to produce via variants of the genetic algorithm updating procedure. Arifovic (1994) found that both models of social and individual learning converged to the Walrasian, competitive equilibrium. Vriend (2000) reports that the model of social learning converges to the Walrasian equilibrium outcome, while the model of individual learning converges to the Cournot–Nash equilibrium. We revisit the issue and conduct simulations varying elements of the updating algorithms, as well as of the underlying economic model. In the analysis of the outcomes of our simulations, we conclude that the convergence to the Cournot–Nash equilibrium is due to two things: the specific way in which production rules’ performance is evaluated coupled with a specific cost function specification.      

Continuous control as alternative route for wear monitoring by measuring penetration depth during linear reciprocating sliding of Ti6Al4V alloy

Continuous wear monitoring during linear reciprocating sliding was investigated. Tribological tests with Ti6Al4V alloy against alumina, at nanotribometer, on microscale, were realised in dry conditions over a range of loads (100-1000 mN) and velocities (4-12 mm/s). Wear factors were calculated, for each conducted test, in two different ways. Wear factors calculated according to observed geometry of the worn tracks (according to ASTM G133 standard) were compared to values calculated according to penetration depth parameter continuously recorded by nanotribometer and results were highly correlated. Penetration depth curves and wear factor curves were obtained and analysed. Wear mechanisms based on examinations of worn surfaces by optical microscopy, were analysed in comparison with trends of penetration depth curves. Development of wear mechanism over time was further investigated. The obtained results showed that the wear factor values are strongly influenced by the applied load.     

Materials and Manufacturing Methods for EWOD Devices: Current Status and Sustainability Challenges

Electrowetting-on-dielectric (EWOD) devices have proven to be effective tools for precise microfluidic manipulation or in liquid lenses that surpass conventional solid lenses in versatility. However, the fabrication of these devices presents many challenges, such as their scalability or the growing concern on their environmental impact due to materials used in their fabrication. This review provides a comprehensive analysis of the materials currently used in the fabrication of EWOD devices and the characteristics they must meet. In addition, a discussion of future challenges in the fabrication of EWOD devices is presented, in particular the environmental problems presented by some of the materials currently in use.     

A Single-Cell Raman Spectroscopy Analysis of Bone Marrow Mesenchymal Stem/Stromal Cells to Identify Inter-Individual Diversity

The heterogeneity of stem cells represents the main challenge in regenerative medicine development. This issue is particularly pronounced when it comes to the use of primary mesenchymal stem/stromal cells (MSCs) due to a lack of identification markers. Considering the need for additional approaches in MSCs characterization, we applied Raman spectroscopy to investigate inter-individual differences between bone marrow MSCs (BM-MSCs). Based on standard biological tests, BM-MSCs of analyzed donors fulfill all conditions for their characterization, while no donor-related specifics were observed in terms of BM-MSCs morphology, phenotype, multilineage differentiation potential, colony-forming capacity, expression of pluripotency-associated markers or proliferative capacity. However, examination of BM-MSCs at a single-cell level by Raman spectroscopy revealed that despite similar biochemical background, fine differences in the Raman spectra of BM-MSCs of each donor can be detected. After extensive principal component analysis (PCA) of Raman spectra, our study revealed the possibility of this method to diversify BM-MSCs populations, whereby the grouping of cell populations was most prominent when cell populations were analyzed in pairs. These results indicate that Raman spectroscopy, as a label-free assay, could have a huge potential in understanding stem cell heterogeneity and sorting cell populations with a similar biochemical background that can be significant for the development of personalized therapy approaches.     

Dynamik realer Gase

Ohne Zusammenfassung     

On the equilibrium conditions of curved interfaces

The equilibrium of a curved interface formed between two fluid phases, which are exposed to an external action is examined. The external action is shown to result in an energy jump across the interface thereby affecting the phase equilibrium. If stated in terms of an energy density of the phases, this action appears in both the Laplace and the Thomson equation as additional term.     

Kondensation von Dampfgemischen—Teil 2

Zusammenfassung Bei der Kondensation str?mender Dampfgemische liegen im Vergleich zu reinen D?mpfen zwei wesentliche Unterschiede vor. Zum einen ?ndern sich bei der Kondensation eines Dampfgemisches die Zusammensetzungen und damit auch die Stoffwerte sowohl des Dampfes als auch des Kondensats l?ngs der Kondensationsstrecke, zum anderen kontrolliert der Stofftransport in der Gasphase meistens die gesamte Kondensationskinetik. Im Gegensatz hierzu ist die Kondensation eines reinen Dampfes nur durch W?rmetransport im Kondensat bestimmt. Die vorliegende Arbeit befa?t sich mit der Kondensation von Mehrstoffgemischen auf der Grundlage des Filmmodells. Die Analyse des Stofftransports und der Wechselwirkungen zwischen den Gemischkomponenten in der Gasphase beruht auf den Maxwell-Stefan-Gleichungen. Neben der exakten L?sung dieser Gleichungen werden in die Betrachtungen auch einige N?herungsl?sungen einbezogen und durch Experimente getestet. Die auf dem Filmmodell beruhenden Rechenergebnisse stimmen mit den experimentellen Werten aus der Literatur meist gut überein, wenn eine einfache Str?mungsführung vorliegt, wie beispielsweise bei der Kondensation in einem senkrechten Rohr. Die exakte L?sung der Maxwell-Stefan-Gleichungen schneidet dabe besser als die N?herungsl?ungen ab. Bei komplexen Str?mungsführungen, wie in einem Rohrbündel mit Umlenkblechen, ist die übereinstimmung im allgemeinen schlechter. Hier sind Verfeinerungen sowohl bezüglich der Wechselwirkungen zwischen den Gemischkomponenten als auch der Berechnungen der für das Filmmodell ben?tigen bin?ren Stoffübergangskoeffizienten erforderlich.     

Hydrogen desorption properties of MgH2/LiAlH4 composites

The hydrogen desorption properties of MgH₂–LiAlH₄ composites obtained by mechanical milling for different milling times have been investigated by Thermal Desorption Spectroscopy (TDS) and correlated to the sample microstructure and morphology analysed by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The MgH₂–LiAlH₄ composites show improved hydrogen desorption properties in comparison with both as-received and ball-milled MgH₂. Mixing of MgH₂ with small amount of LiAlH₄ (5 wt.%) using short mechanical milling (15 min) shifts, in fact, the hydrogen desorption peak to lower temperature than those observed with both as-received and milled MgH₂ samples. Longer mixing times of the MgH₂–LiAlH₄ composites (30 and 60 min) reduce the catalytic activity of the LiAlH₄ additive as revealed by the shift of the hydrogen desorption peak to higher temperatures.