Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

Sensor systems testbed for telerobotic navigation

A testbed has been developed for the study of sensor systems to be used in telerobotic operations. The program, conducted in conjunction with Johnson Space Center of NASA, addresses the navigational problems associated with target acquisition and rendezvous for teleoperated robotic work stations. The program will utilize a mobile platform which will support various sensor systems during their development and testing in an earth-based environment. The testbed has been developed in support of a program to develop sensor systems that will aid in rendezvous and docking operations to be conducted as a part of the space station program. A mobile platform has been used to permit testing of these components in a conventional laboratory environment with consequent savings in cost and complexity. The sensor systems, while representative of devices currently in use for robotic applications, are not considered prototypical of the ones that will be used in the final applications. The test program provided information that will support the design of system augmentations and will lead to a comprehensive test program for sensor development

Gaze-dependent topography in human posterior parietal cortex.

The brain must convert retinal coordinates into those required for directing an effector. One prominent theory holds that, through a combination of visual and motor/proprioceptive information, head-/body-centered representations are computed within the posterior parietal cortex (PPC). An alternative theory, supported by recent visual and saccade functional magnetic resonance imaging (fMRI) topographic mapping studies, suggests that PPC neurons provide a retinal/eye-centered coordinate system, in which the coding of a visual stimulus location and/or intended saccade endpoints should remain unaffected by changes in gaze position. To distinguish between a retinal/eye-centered and a head-/body-centered coordinate system, we measured how gaze direction affected the representation of visual space in the parietal cortex using fMRI. Subjects performed memory-guided saccades from a central starting point to locations “around the clock.” Starting points varied between left, central, and right gaze relative to the head-/body midline. We found that memory-guided saccadotopic maps throughout the PPC showed spatial reorganization with very subtle changes in starting gaze position, despite constant retinal input and eye movement metrics. Such a systematic shift is inconsistent with models arguing for a retinal/eye-centered coordinate system in the PPC, but it is consistent with head-/body-centered coordinate representations

Dynamic unbinding transitions and deposition patterns in dragged meniscus problems

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.We sketch main results of our recent work on the transfer of a thin liquid film onto a flat plate that is extracted from a bath of pure non-volatile liquid. Employing a long-wave hydrodynamic model, that incorporates wettability via a Derjaguin (disjoining) pressure, we analyse steady-state meniscus profiles as the plate velocity is changed. We identify four qualitatively different dynamic transitions between microscopic and macroscopic coatings that are out-of-equilibrium equivalents of equilibrium unbinding transitions. The conclusion briefly discusses how the gradient dynamics formulation of the problem allows one to systematically extend the employed one-component model into thermodynamically consistent two-component models as used to describe, e.g., the formation of line patterns during the Langmuir-Blodgett transfer of a surfactant layer

Preispolitische Spielräume für regional erzeugte ökologische Produkte: Analyse und Umsetzung einer Marketingstrategie bei Biomilchprodukten

Dieses Projekt zeigt anhand eines Fallbeispiels, welche Zahlungsbereitschaften und potentiellen Preisspielräume in der regionalen Vermarktung von Öko-Produkten existieren und wie eine Umsetzung in eine nachhaltig erfolgreiche Marketingstrategie erfolgen kann. Die Erhebung der Zahlungsbereitschaften für regionale Öko-Milch bei über 800 Verbrauchern am POS im LEH und im Naturkosthandel ergab, dass zwar hohe Zahlungsbereitschaften aber auch hohe Preiselastizitäten bei regionaler Öko-Milch existieren. Die Vorabbefragungen zeigten aber auch, dass das Hauptmotiv für die Akzeptanz eines Preisaufschlags die Unterstützung der heimischen Öko-Milcherzeuger ist. Vor diesem Hintergrund wurde als Kern der Marketingstrategie die „Regional- und Sozialqualität“ als dominante Profilierungsdimension gewählt und die Öko-Milch der Upländer Bauernmolkerei aus Hessen wird als „ErzeugerfairMilch“ seit Januar 2005 in den regionalen Testmärkten mit einem Preisaufschlag von 5 Cent je Liter verkauft. Die Abverkaufszahlen in den 60 Naturkosthandelsgeschäften und den 12 Geschäften des LEH zeigten - über den allgemeinen Anstieg der Öko-Milchumsätze im Jahr 2005 hinaus - in den meisten Märkten deutlich ansteigende Abverkäufe und eine hohe Verbraucherakzeptanz. Erfolgsunterschiede zwischen den Testmärkten sind zu erklären durch Faktoren wie Ladengröße, Kundenstruktur, Lage des Geschäfts, Präsentation des Projektes am Kühlregal und im Laden sowie Informationen zu dem Projekt. Bei den Käufern der ErzeugerfairMilch dominieren als Kaufmotive egoistische Motive (Geschmack, Convenience, Frische) vor altruistischen Motiven (kurze Transporte, Erhalt der Landwirtschaft, Einkommen der Landwirte, Erhalt von Arbeitsplätzen). Dies ist bei der Bildung von Motivallianzen und der Ausgestaltung von regionalen Marketingstrategien zu beachten. Insgesamt zeigt dieses Pilotprojekt, dass erhebliche preispolitische Spielräume für regional erzeugte ökologische Produkte existieren, aber dass die Ausgestaltung der Marketingstrategie entscheidend für deren Erschließung ist. Die erfolgreiche Übertragung des Projektes auf andere Regionen und auch viele Nachahmerprojekte untermauern diese Aussagen. Verbraucher und Lebensmittelhändler leisten damit einen direkten Beitrag zur Unterstützung der regionalen Öko-Landwirte

Driving Rydberg-Rydberg transitions from a co-planar microwave waveguide

The coherent interaction between ensembles of helium Rydberg atoms and microwave fields in the vicinity of a solid-state co-planar waveguide is reported. Rydberg-Rydberg transitions, at frequencies between 25 GHz and 38 GHz, have been studied for states with principal quantum numbers in the range 30 - 35 by selective electric-field ionization. An experimental apparatus cooled to 100 K was used to reduce effects of blackbody radiation. Inhomogeneous, stray electric fields emanating from the surface of the waveguide have been characterized in frequency- and time-resolved measurements and coherence times of the Rydberg atoms on the order of 250 ns have been determined.Comment: 5 pages, 5 figure

Willingness-To-Pay for Food of the Own Region: Empirical Estimates from Hypothetical and Incentive Compatible Settings

The ongoing liberalisation of the European food market provides incentives to producers to seek for innovative strategies of product differentiation. One possibility to differentiate the own product from competing ones is its region-of-origin. In this paper, we investigate consumers' willingness-to-pay and underlying preferences for food of the own region. We consider fresh milk as an example. Underlying data stem from a hypothetical contingent valuation and from an incentive compatible experimental setting with real payoffs. We find that consumers perceive fresh milk from local farmers as a trustful, high quality product, and that consumers are interested in supporting local producers. Given that price premiums are small, both methods suggest a substantial demand for local products. However, compared to contingent-valuation estimates, the inclusion of real payoffs leads to a significant decrease in the willingness-to-pay stated. This decrease can mainly be assigned to "pretending altruists": free riding subjects who respond according to social norms as long as no costs are involved.Consumer/Household Economics,

Decomposition driven interface evolution for layers of binary mixtures: I. Model derivation and stratified base states

A dynamical model is proposed to describe the coupled decomposition and profile evolution of a free surface film of a binary mixture. An example is a thin film of a polymer blend on a solid substrate undergoing simultaneous phase separation and dewetting. The model is based on model-H describing the coupled transport of the mass of one component (convective Cahn-Hilliard equation) and momentum (Navier-Stokes-Korteweg equations) supplemented by appropriate boundary conditions at the solid substrate and the free surface. General transport equations are derived using phenomenological non-equilibrium thermodynamics for a general non-isothermal setting taking into account Soret and Dufour effects and interfacial viscosity for the internal diffuse interface between the two components. Focusing on an isothermal setting the resulting model is compared to literature results and its base states corresponding to homogeneous or vertically stratified flat layers are analysed.Comment: Submitted to Physics of Fluid

Perspectives on partnership: Highlights of a literature review

Working in partnership has become central in efforts to address complex environmental, socio-economic, and technological problems. The terms partner or partnership appear more than 100 times in the Paris Declaration on Aid Effectiveness and more than 200 times in the version of the CGIAR's new Strategy and Results Framework presented at the recent Global Conference on Agricultural Research for Development. It is promoted as an effective means to mobilise the resources and capacities needed to generate knowledge, stimulate innovation and influence decision-making. Nevertheless, partnering is often experienced as timeconsuming and frustrating, and it has proved difficult to demonstrate its 'value added'. To improve partnering at the International Potato Center (CIP), we reviewed publications, evaluations and reports dealing with partnership. Rather than a single 'partnership literature' we found several different literatures that approach the subject from different perspectives. Several themes – relating to partnering processes vs. partnership structures, partnership dynamics, types of partnership, incentives for partnering, the key role of trust, power and equity issues, success factors and evaluation – cut across the distinct literatures. This ILAC Brief presents findings in each of these areas, notes some prominent knowledge gaps and identifies areas for future study

Diversifikation und Wachstum landwirtschaftlicher Unternehmen

Trotz der vielfach betonten Bedeutung von Diversifikationsstrategien vor dem Hintergrund zunehmender Liberalisierung vieler Agrarmärkte existieren nur wenige empirische Arbeiten zum Zusammenhang zwischen Diversifikation und dem Erfolg landwirtschaftlicher Unternehmen. Der vorliegende Beitrag basiert auf dem empirischen Ansatz von Oustapassidis (1992), der den Einfluss der Diversifikation in verwandte und unverwandte Produktbereiche auf das Wachstum (als ein Erfolgsmaß) von Unternehmen untersucht und überträgt ihn auf landwirtschaftliche Unternehmen in Schleswig-Holstein. Die Ergebnisse von Fixed- und Random-Effekt-Schätzungen des Wachstums von rd. 3.900 Unternehmen für den Zeitraum von 1988/89 bis 1997/98 zeigen, dass Unternehmen mit hoher Diversifikation in verwandte Produktbereiche ein höheres Wachstum aufweisen, während die Diversifikation in nicht-verwandte Produktbereiche die Wachstumsrate signifikant reduziert. Weiterhin hat die Betriebsgröße zum Ausgangszeitpunkt einen signifikant negativen Einfluss auf das Wachstum, so dass von ß-Konvergenz in den Wachstumsraten auszugehen ist.The liberalisation of agricultural markets has increased the interest of farmers (as well as those working on policies concerned with their welfare) in agricultural diversification strategies. However, empirical research on diversification in European agricultural markets is very limited. This paper follows Oustapassidis (1992) and investigates the relationship between different diversification strategies and farm performance (farm growth rates). The results of fixed- and random-effect models for approx. 3,900 farms in Schleswig-Holstein for the period 1988/89-1997/98 show that diversification into related products increases growth rates whereas the opposite applies for diversification into unrelated products. Initial farm size has a significant and negative impact on the rate of growth which implies ßconvergence of farm sizes