Loop formation and stability of self-avoiding polymer chains

Using 3-dimensional Langevin dynamics simulations, we investigated the dynamics of loop formation of chains with excluded volume interactions, and the stability of the formed loop. The mean looping time τ _l scales with chain length N and corresponding scaling exponent α increases linearly with the capture radius scaled by the Kuhn length a/l due to the effect of finite chain length. We also showed that the probability density function of the looping time is well fitted by a single exponential. Finally, we found that the mean unlooping time τ _u hardly depends on chain length N for a given a/l and that the stability of a formed loop is enhanced with increasing a/l.     

Selective adsorption of metronidazole on conjugated microporous polymers

Conjugated microporous polymers (CMPs) have recently received extensive attention in oil/organic solvent-water separation field as a kind of ideal porous absorbents with tunable porosity, large surface areas, and super-hydrophobicity. However, reports on the application of CMPs in adsorption of hydrophilic contaminants from water are very few. In this work, we studied the adsorption of metronidazole (MNZ), a polar antibiotic, by two kinds of CMPs. The adsorption characteristics of MNZ by the CMPs, including adsorption kinetics, mechanism, and isotherm parameters were calculated. The adsorption kinetics of MNZ was well expressed by the pseudo-second-order model, and the adsorption process was found to be mainly controlled by film diffusion. The adsorption isotherm data agreed well with the Langmuir isotherm model, and the values of free energy E indicated that the adsorption nature of MNZ on the CMPs was physisorption. Increasing dispersion degree of the CMPs in MNZ solution resulted in greater adsorption. This work may provide fundamental guidance for the removal of antibiotics by CMPs.     

On the manipulability of competitive equilibrium rules in many-to-many buyer–seller markets

We analyze the manipulability of competitive equilibrium allocation rules for the simplest many-to-many extension of Shapley and Shubik’s (Int J Game Theory 1:111–130, 1972) assignment game. First, we show that if an agent has a quota of one, then she does not have an incentive to manipulate any competitive equilibrium rule that gives her her most preferred competitive equilibrium payoff when she reports truthfully. In particular, this result extends to the one-to-many (respectively, many-to-one) models the Non-Manipulability Theorem of the buyers (respectively, sellers), proven by Demange (Strategyproofness in the assignment market game. École Polytechnique, Laboratoire d’Économetrie, Paris, 1982), Leonard (J Polit Econ 91:461–479, 1983), and Demange and Gale (Econometrica 55:873–888, 1985) for the assignment game. Second, we prove a “General Manipulability Theorem” that implies and generalizes two “folk theorems” for the assignment game, the Manipulability Theorem and the General Impossibility Theorem, never proven before. For the one-to-one case, this result provides a sort of converse of the Non-Manipulability Theorem.     

Flow auctions

Flow goods (like electricity) are sold through auctions in a dynamic framework. An important design question is the frequency of such auctions. We use a simple dynamic auction model in continuous time to answer this question. We focus on the relationship between the persistency of bidders’ valuations and the optimal choice of frequency. If the seller focuses on the equilibrium in which bidders follow a repeated static Nash strategy, then the frequency of auctions should typically increase when persistency declines. However, accounting for the fact that bidders can follow different equilibria that are collusive in nature, the comparative statics are reversed, forcing the seller to reduce the frequency when bidders’ valuations are less persistent. The argument builds on the fact that high frequency auctions are more conducive to collusion among bidders.     

Mechanism design for land acquisition

We consider the issue of designing Bayesian incentive-compatible, efficient, individually rational and balanced mechanisms for Land Acquisition. This is a problem of great practical importance in developing countries. Several sellers, each with one unit of land, are located at the nodes of a graph. Two sellers are contiguous if they are connected by an edge in the graph. The buyer realizes a positive value only if he can purchase plots that constitute a path of given length. Our main result is that there is a robust set of priors for which successful mechanisms exist when there are at least two distinct feasible sets of contiguous sellers. The analysis also identifies the role of critical sellers who lie on all such feasible sets.     

Optimal signaling with cheap talk and money burning

We study Sender-optimal signaling equilibria with cheap talk and money-burning. Under general assumptions, the Sender never uses money-burning to reveal all states, but always wants to garble information for at least some states. With quadratic preferences and any log-concave density of the states, optimal communication is garbled for all states: money-burning, if used at all, is used to adjust pooling intervals. This is illustrated by studying in depth the well-known uniform-quadratic case. We also show how the presence of a cost of being “caught unprepared” that gives rise to a small change in a common assumption on the Receiver’s utility function makes full revelation through money-burning Sender-optimal.     

Correlation and unmediated cheap talk in repeated games with imperfect monitoring

This paper studies n-player \((n\ge 3)\) undiscounted repeated games with imperfect monitoring. We prove that all uniform communication equilibrium payoffs of a repeated game can be obtained as Nash equilibrium payoffs of the game extended by unmediated cheap talk. We also show that all uniform communication equilibrium payoffs of a repeated game can be reached as Nash equilibrium payoffs of the game extended by a pre-play correlation device and a cheap-talk procedure that only involves public messages; furthermore, in the case of imperfect public and deterministic signals, no cheap talk is conducted on the equilibrium path.     

Efficiency in a forced contribution threshold public good game

We contrast and compare three ways of predicting efficiency in a forced contribution threshold public good game. The three alternatives are based on ordinal potential, quantal response and impulse balance theory. We report an experiment designed to test the respective predictions and find that impulse balance gives the best predictions. A simple expression detailing when enforced contributions result in high or low efficiency is provided.     

Multiple solutions for non-homogeneous degenerate Schrödinger equations in cone Sobolev spaces

The present paper deals with the study of semilinear and non-homogeneous Schrödinger equations on a manifold with conical singularity. We provide a suitable constant by Sobolev embedding constant and for p ∈ (2, 2?) with respect to non-homogeneous term g(x) ∈ L ₂ ^n/2 (B), which helps to find multiple solutions of our problem. More precisely, we prove the existence of two solutions to the problem 1.1 with negative and positive energy in cone Sobolev space H _2,0 ^1,n/2 (B). Finally, we consider p = 2 and we prove the existence and uniqueness of Fuchsian-Poisson problem.     

On commutativity of near-rings with generalized derivations

In this paper we prove some theorems of commutativity for near-rings with generalized derivations. As a consequence of the results obtained, we generalize some published results. Also, we give some examples to show that some conditions in some results obtained are not redundant.