1,749 research outputs found
The Mere Categorization Effect: How the Presence of Categories Increases Choosers' Perceptions of Assortment Variety
What is the effect of option categorization on choosers’ satisfaction? A combination of field and laboratory experiments reveals that the mere presence of categories, irrespective of their content, positively influences the satisfaction of choosers who are unfamiliar with the choice domain. This “mere categorization effect” is driven by a greater number of categories signaling greater variety amongst the available options, which allows for a sense of self-determination from choice. This effect, however, is attenuated among choosers who are familiar with the choice domain, who do not rely on the presence of categories to perceive the variety available.
Feedback in Online Fanfiction
2016 Jan Rehner Writing Prize Finalists, 2nd Year WinnerWRIT 2004, Writing in Digital Culture
Branching, Capping, and Severing in Dynamic Actin Structures
Branched actin networks at the leading edge of a crawling cell evolve via
protein-regulated processes such as polymerization, depolymerization, capping,
branching, and severing. A formulation of these processes is presented and
analyzed to study steady-state network morphology. In bulk, we identify several
scaling regimes in severing and branching protein concentrations and find that
the coupling between severing and branching is optimally exploited for
conditions {\it in vivo}. Near the leading edge, we find qualitative agreement
with the {\it in vivo} morphology.Comment: 4 pages, 2 figure
Symmetry-Breaking Motility
Locomotion of bacteria by actin polymerization, and in vitro motion of
spherical beads coated with a protein catalyzing polymerization, are examples
of active motility. Starting from a simple model of forces locally normal to
the surface of a bead, we construct a phenomenological equation for its motion.
The singularities at a continuous transition between moving and stationary
beads are shown to be related to the symmetries of its shape. Universal
features of the phase behavior are calculated analytically and confirmed by
simulations. Fluctuations in velocity are shown to be generically
non-Maxwellian and correlated to the shape of the bead.Comment: 4 pages, 2 figures, REVTeX; formatting of references correcte
Growth Velocities of Branched Actin Networks
The growth of an actin network against an obstacle that stimulates branching
locally is studied using several variants of a kinetic rate model based on the
orientation-dependent number density of filaments. The model emphasizes the
effects of branching and capping on the density of free filament ends. The
variants differ in their treatment of side vs. end branching and
dimensionality, and assume that new branches are generated by existing branches
(autocatalytic behavior) or independently of existing branches (nucleation
behavior). In autocatalytic models, the network growth velocity is rigorously
independent of the opposing force exerted by the obstacle, and the network
density is proportional to the force. The dependence of the growth velocity on
the branching and capping rates is evaluated by a numerical solution of the
rate equations. In side-branching models, the growth velocity drops gradually
to zero with decreasing branching rate, while in end-branching models the drop
is abrupt. As the capping rate goes to zero, it is found that the behavior of
the velocity is sensitive to the thickness of the branching region. Experiments
are proposed for using these results to shed light on the nature of the
branching process.Comment: 6 figure
Recommended from our members
Time, Money, and Morality
Money, a resource that absorbs much daily attention, seems to be present in much unethical behavior thereby suggesting that money itself may corrupt. This research examines a way to offset such potentially deleterious effects—by focusing on time, a resource that tends to receive less attention than money but is equally ubiquitous in our daily lives. Across four experiments, we examine whether shifting focus onto time can salvage individuals' ethicality. We found that implicitly activating the construct of time, rather than money, leads individuals to behave more ethically by cheating less. We further found that priming time reduces cheating by making people reflect on who they are. Implications for the use of time versus money primes in discouraging or promoting dishonesty are discussed
Soft Listeria: actin-based propulsion of liquid drops
We study the motion of oil drops propelled by actin polymerization in cell
extracts. Drops deform and acquire a pear-like shape under the action of the
elastic stresses exerted by the actin comet. We solve this free boundary
problem and calculate the drop shape taking into account the elasticity of the
actin gel and the variation of the polymerization velocity with normal stress.
The pressure balance on the liquid drop imposes a zero propulsive force if
gradients in surface tension or internal pressure are not taken into account.
Quantitative parameters of actin polymerization are obtained by fitting theory
to experiment.Comment: 5 pages, 4 figure
Dynamic coordinated control laws in multiple agent models
We present an active control scheme of a kinetic model of swarming. It has
been shown previously that the global control scheme for the model, presented
in \cite{JK04}, gives rise to spontaneous collective organization of agents
into a unified coherent swarm, via a long-range attractive and short-range
repulsive potential. We extend these results by presenting control laws whereby
a single swarm is broken into independently functioning subswarm clusters. The
transition between one coordinated swarm and multiple clustered subswarms is
managed simply with a homotopy parameter. Additionally, we present as an
alternate formulation, a local control law for the same model, which implements
dynamic barrier avoidance behavior, and in which swarm coherence emerges
spontaneously.Comment: 20 pages, 6 figure
- …