Effect of Cilia Orientation in Metachronal Transport of Microparticles

A biomimetic approach is used to generate a directed transversal transportation of micron-sized particles in liquids based on the principle of cilia-type arrays in coordinated motion. Rows of flaps mimicking planar cilia are positioned off-centre along an array of cavities covered with membranes that support the flaps. These membranes are deflected from a concave to a convex shape and vice versa by pneumatic actuation applying positive and negative pressures (relative to the ambient) inside the cavities. As a result, the flap on top of the membrane tilts to the left or right within such a pressure cycle, performing a beat stroke. Since each cavity can be addressed in the device individually and in rapid succession, waves of coordinated flap motion can be run along the wall. Such metachronal waves are generated and transport of particles along the cilia surface is achieved in both symplectic and antiplectic direction. It is shown that the initial tilt of the flaps relative to the wall-normal determines the direction of transport

Incomplete and Asymmetric Surplus Information in Labor Relations

Numerous laboratory experiments show that workers reciprocate to high wages with high effort, when there is perfect information on the surplus created. Recent field experiments, however, suggest that trust and reciprocity may be lower or absent when the information is incomplete.We report a laboratory experiment with symmetric and asymmetric incomplete surplus information in a bilateral gift exchange setting.We find that trust and reciprocity have a significant positive effect on wages, effort and efficiency.But, all three are substantially lower under incomplete than under complete information.The negative impact on wages and efficiency is even greater with information asymmetry.incomplete information;industrial relations;trusts;efficiency

Archives, Undergraduates, and Inquiry-Based Learning: Case Studies from Yale University Library

This article discusses the integration of primary sources into the teaching of undergraduate courses through the application of specific learning theories. Creative assignments and inquiry-based learning exercises illustrate how librarians and archivists can collaborate with faculty to integrate collections into the curriculum. Through several case studies from Yale University, the article examines how learning theory can provide inspiration for partnerships with faculty and new outreach approaches

Single stage experimental evaluation of compressor blading with slots and vortex generators. Part 1 - Analysis and design of stages 4 and 5

Analysis and design of compressor blading with slots and vortex generator

Collusion under Yardstick Competition: An Experimental Study

The effectiveness of relative performance evaluation schemes, such as yardstick competition, can be undermined by collusion.The degree to which the regulated agents manage to collude will be affected by the particulars of the scheme.We hypothesize that in a repeated game setting schemes will be more prone to collusion the smaller are the rents to the agents in case they behave non-cooperatively.We illustrate the relevance of this hypothesis by means of an economic experiment in which we compare the efficiency of two performance evaluation schemes.performance evaluation;competition;efficiency;games;collusion;yardstick

Pneumatically actuated biomimetic particle transporter

To prevent the adhesion of particles at surfaces by transporting them along the surface, a new type of pneumatically actuated particle transporter is introduced. The biomimetic approach is based on the transportation principle of particles by cilia arrays due to the generation of metachronal waves. Rows of flaps, which mimic the cilia, are asymmetrically positioned on flexible membranes. The membranes are individually deflected by applying a well-defined pressure profile to achieve a metachronal wave. Detailed simulations of the membrane and flap deflections as well as a description of the proof-of-concept by applying metachronal waves to the flap arrays are presented

Collusion under yardstick competition:An experimental study

The effectiveness of relative performance evaluation schemes, such as yardstick competition, can be undermined by collusion.The degree to which the regulated agents manage to collude will be affected by the particulars of the scheme.We hypothesize that in a repeated game setting schemes will be more prone to collusion the smaller are the rents to the agents in case they behave non-cooperatively.We illustrate the relevance of this hypothesis by means of an economic experiment in which we compare the efficiency of two performance evaluation schemes

Fluid transport via pneumatically actuated waves on a ciliated wall

To manipulate fluids actively a pneumatically actuated micro membrane device is developed to generate a directed transversal fluid transport in a liquid layer next to the wall. The biomimetic approach is based on the principle of cilia-type arrays that generate a mean flow by travelling wave activation. Rows of long flaps, which mimic the comb row of a ctenophore, are positioned off-centre along a row of cavities. Each cavity is covered by a flexible membrane that supports the flaps. The membranes with the flaps on top are deflected by applying a well-defined pressure profile to the cavities under the membranes such that an individual beat can be generated for each flap. Flow visualization experiments were carried out under the conditions of travelling waves. The results show a mean velocity profile that resembles that of a wall-jet. Mixing effects with increased retention times of the fluid occur in the vicinity of the membrane surfaces