5,827 research outputs found
Cooperation and Wealth
No full textWe calculate the equilibrium fraction of cooperators in a population in which payoffs accrue from playing a single-shot prisoner’s dilemma game. Individuals who are hardwired as cooperators or defectors are randomly matched into pairs, and cooperators are able to perfectly find out the type of a partner to a game by incurring a recognition cost. We show that the equilibrium fraction of cooperators relates negatively to the population’s level of wealth.Equilibrium fraction of cooperators, Population's level of wealth, Single-shot prisoner's dilemma game
Christopher Stark, composition, Tuesday, May 1, 2007
No full text"In partial fulfillment of the requirements for the degree of Master of Music
Feedback control of inertial microfluidics using axial control forces
No full textDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Inertial microfluidics is a promising tool for many lab-on-a-chip applications. Particles in channel flows with Reynolds numbers above one undergo cross-streamline migration to a discrete set of equilibrium positions in square and rectangular channel cross sections. This effect has been used extensively for particle sorting and the analysis of particle properties. Using the lattice Boltzmann method, we determined the equilibrium positions in square and rectangular cross sections and classify their types of stability for different Reynolds numbers, particle sizes, and channel aspect ratios. Our findings thereby help to design microfluidic channels for particle sorting. Furthermore, we demonstrated how an axial control force, which slows down the particles and shifts the stable equilibrium position towards the channel center. Ultimately, the particles then stay on the centerline for forces exceeding the threshold value. This effect is sensitive to the particle size and channel Reynolds number and therefore suggests an efficient method for particle separation. In combination with a hysteretic feedback scheme, we can even increase the particle throughput.DFG, SFB 910, Kontrolle selbstorganisierender nichtlinearer Systeme: Theoretische Methoden und Anwendungskonzept
Malcolm Stark Correspondence
No full textEntries include typed correspondence on The Camden Herald Publishing Company stationery concerning the whereabouts of Mr. Stark, a handwritten letter from Stark on plain paper, and a typed letter on receipt of the Maine poet\u27s book Way Out and Close About for the Maine Author Collection
Möglichkeiten der ökologisch und ökonomisch sinnvollen Abgrenzung und Ausgestaltung einer "Regenerativ-Sonderzone" zur ausschließlichen Erzeugung erneuerbarer Energie in strukturschwachen Gebieten Ostdeutschlands
No full textMÖGLICHKEITEN DER ÖKOLOGISCH UND ÖKONOMISCH SINNVOLLEN ABGRENZUNG UND AUSGESTALTUNG EINER "REGENERATIV-SONDERZONE" ZUR AUSSCHLIESSLICHEN ERZEUGUNG ERNEUERBARER ENERGIE IN STRUKTURSCHWACHEN GEBIETEN OSTDEUTSCHLANDS
Möglichkeiten der ökologisch und ökonomisch sinnvollen Abgrenzung und Ausgestaltung einer "Regenerativ-Sonderzone" zur ausschließlichen Erzeugung erneuerbarer Energie in strukturschwachen Gebieten Ostdeutschlands / Stark, Christopher (CC BY-NC-SA) (-
Inequality and Migration: A Behavioral Link
No full textWe provide an analytical-behavioral explanation for the observed positive relationship between income inequality, as measured by the Gini coefficient, and the incentive to migrate. We show that a higher total relative deprivation of a population leads to a stronger incentive to engage in migration for a given level of a population’s income; that total relative deprivation is positively related to the Gini coefficient; and that, consequently, the Gini coefficient and migration are positively correlated, holding the population’s income constant.Income inequality, Relative deprivation, The Gini coefficient, The incentive to migrate
The historical imagination of Christopher Dawson
No full textChristopher Dawson (1889-1970) was one of his generation's most
important historians and religious thinkers, and was a significant
influence on many contemporaries including T.S. Eliot, C.S. Lewis,
and Russell Kirk. This dissertation is a study of his most
fundamental ideas concerning history and culture.
Chapter one examines Dawson’s sociological view of history.
Convinced that history was more than a scientific enterprise, he
believed that the true historian is one who reaches beyond the
material world to understand the essence of history’s dynamics. In
this way, the world can be conceptualized as a united whole,
separated by regional differences as a result of environment, race,
material, psychological, and religious factors. Dawson believed
that the political histories of the past several centuries failed to
grasp the undercurrents of historical change, and that the best way
to understand the past is to appreciate culture as an expression of
primeval religious traditions.
Chapter two treats Dawson’s understanding of progress. Dawson
was convinced that progress had become the “working-religion” of our
age. This secular faith, founded on scientific rationalism, first
pledged to fix the material failures of Western culture, but
unwittingly eroded its faith in God, and eventually, its moral
fiber. Dawson believed that true progress was progress of the soul
in its ordering toward the Creator.
Chapter three is a study of Dawson’s Christian, and more
specifically, his Catholic beliefs. Informed by religion, his
historical and cultural visions are not dogmatic, nor are they
polemical. He conceived of history as the unfolding of a divine
economy in the temporal world. Although Dawson is a proponent of
Roman Catholicism, his scholarship is an objective treatment of
history shaped by an undisguised, Christian worldview.
Additionally, the appendix is an introduction to Dawson’s life
and the circumstances surrounding his conversion to Roman
Catholicism. Particular attention is paid to the development of his
moral and historical imagination — both of which became intertwined to
form the basis of all of his scholarship
Controlling inertial focussing using rotational motion
No full textIn inertial microfluidics lift forces cause a particle to migrate across streamlines to specific positions in the cross section of a microchannel. We control the rotational motion of a particle and demonstrate that this allows to manipulate the lift-force profile and thereby the particle's equilibrium positions. We perform two-dimensional simulation studies using the method of multi-particle collision dynamics. Particles with unconstrained rotational motion occupy stable equilibrium positions in both halfs of the channel while the center is unstable. When an external torque is applied to the particle, two equilibrium positions annihilate by passing a saddle-node bifurcation and only one stable fixpoint remains so that all particles move to one side of the channel. In contrast, non-rotating particles accumulate in the center and are pushed into one half of the channel when the angular velocity is fixed to a non-zero value
Optimal control of particle separation in inertial microfluidics
No full textRecently, inertial mircofluidics has emerged as a promising tool to manipulate complex liquids with possible biomedical applications, for example, to particle separation. Indeed, in experiments different particle types were separated based on their sizes (A.J. Mach, D. Di Carlo, Biotechnol. Bioeng. 107, 302 (2010)). In this article we use a theoretical study to demonstrate how concepts from optimal control theory help to design optimized profiles of control forces that allow to steer particles to almost any position at the outlet of a microfluidic channel. We also show that one specific control force profile is sufficient to guide two types of particles to different locations at the channel outlet, where they can be separated from each other. The particles just differ by their size which determines the strength of the inertial lift forces they experience. Our approach greatly enhances the efficiency of particle separation in the inertial regime
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