Bilateral Matching Research Articles

Neuromuscular dysfunction with the experimental arm acting as its own reference following eccentric and isometric exercise

Eccentric exercise has been extensively used as a model to study muscle damage-induced neuromuscular impairment, adopting mainly a bilateral matching task between the reference (unexercised) arm and the indicator (exercised) arm. However, little attention has been given to the muscle proprioceptive function when the exercised arm acts as its own reference. This study investigated muscle proprioception and motor control, with the arm acting both as reference and indicator, following eccentric exercise and compared them with those observed after isometric exercise. Fourteen young male volunteers were equally divided into two groups and performed an eccentric or isometric exercise protocol with the elbow flexors of the non-dominant arm on an isokinetic dynamometer. Both exercise protocols induced significant changes in indicators of muscle damage, that is, muscle soreness, range of motion and maximal isometric force post-exercise (p < 0.05–0.001), and neuromuscular function was similarly affected following both protocols. Perception of force was impaired over the 4-day post-exercise period (p < 0.001), with the applied force being systematically overestimated. Perception of joint position was significantly disturbed (i.e., target angle was underestimated) only at one elbow angle on day 4 post-exercise (p < 0.05). The misjudgements and disturbed motor output observed when the exercised arm acted as its own reference concur with the view that they could be a result of a mismatch between the central motor command and an impaired motor control after muscle damage.

Altruistic Donor Triggered Domino-Paired Kidney Donation for Unsuccessful Couples from the Kidney-Exchange Program

Between January 2000 and July 2009, 132 individuals inquired about altruistic kidney donation to strangers. These donors were willing to donate to genetically and emotionally unrelated patients. Some altruistic donors wished to donate to a specific person, but most wished to donate anonymously. In domino-paired donation, the altruistic donor donates to the recipient of an incompatible couple; the donor of that couple (domino-donor) donates to another couple or to the waiting list. In contrast to kidney-exchange donation where bilateral matching of couples is required, recipient and donor matching are unlinked in domino-paired donation. This facilitates matching for unsuccessful couples from the kidney-exchange program where blood type O prevails in recipients and is under-represented in donors. Fifty-one altruistic donors (39%) donated their kidney and 35 domino-donors were involved. There were 29 domino procedures, 24 with 1 altruistic donor and 1 domino-donor, 5 with more domino-donors. Eighty-six transplantations were performed. Donor and recipient blood type distribution in the couples limited allocation to blood type non-O waiting list patients. The success rate of domino-paired donation is dependent on the composition of the pool of incompatible pairs, but it offers opportunities for difficult to match pairs that were unsuccessful in the kidney-exchange program.

Over-the-Counter Loans, Adverse Selection, and Stigma in the Interbank Market

It is often the case that banks in the US are willing to borrow in the fed funds market (the interbank market for funds) at higher rates than the ones they could obtain by borrowing at the Fed's discount window. This phenomenon is commonly explained as the consequence of the existence of a stigma effect attached to borrowing from the window. Most policymakers and empirical researchers consider the stigma hypothesis plausible. Yet, no formal treatment of the issue has ever been provided in the literature. In this paper, we fill that gap by studying a model of interbank credit where: (1) banks benefit from engaging in intertemporal trade with other banks and with outside investors; and (2) physical and informational frictions limit those trade opportunities. In our model, banks obtain loans in an over-the-counter market (involving search, bilateral matching, and negotiations over the terms of the loan) and hold assets of heterogeneous qualities which in turn determine their ability to repay those loans. When asset quality is not observable by outside investors, information about the actions taken by a bank in the credit market may influence the price at which it can sell its assets. In particular, under some conditions, discount window borrowing may be regarded as a negative signal about the quality of the borrower's assets. In such cases, some of the banks in our model, just as in the data, are willing to accept loans in the interbank market at higher rates than the ones they could obtain at the discount window.

Bilateral matching and bargaining with private information

We study equilibria of a dynamic matching and bargaining game (DMBG) with two-sided private information bilateral bargaining. The model is a private information replica of Mortensen and Wright (2002). There are two kinds of frictions: time discounting and explicit search costs. A simple necessary and sufficient condition on parameters for existence of a nontrivial equilibrium is obtained. This condition is the same regardless whether the information is private or not. In addition, it is shown that when the discount rate is sufficiently small, the equilibrium is unique and has the property that every meeting results in trade.

MOTION VECTOR CORRECTION AND REFINEMENT EFFECT IN FRAME UP-RATE CONVERSION

The paper applies the motion vector (MV) correction and refinement algorithm to frame up-rate conversion (FRUC) in order to enhance the quality of the interpolated frame. The motion compensated frame interpolation (MCFI) methods using bilateral motion estimation and hierarchical block matching algorithm are used to form the interpolated frame. Simulation results show that MV correction algorithm provides true motion vectors and MV refinement helps reducing the blocking artifact.

Bilateral matching of frequency tuning in neural cross-correlators of the owl

Sound localization requires comparison between the inputs to the left and right ears. One important aspect of this comparison is the differences in arrival time to each side, also called interaural time difference (ITD). A prevalent model of ITD detection, consisting of delay lines and coincidence-detector neurons, was proposed by Jeffress (J Comp Physiol Psychol 41:35-39, 1948). As an extension of the Jeffress model, the process of detecting and encoding ITD has been compared to an effective cross-correlation between the input signals to the two ears. Because the cochlea performs a spectrotemporal decomposition of the input signal, this cross-correlation takes place over narrow frequency bands. Since the cochlear tonotopy is arranged in series, sounds of different frequencies will trigger neural activity with different temporal delays. Thus, the matching of the frequency tuning of the left and right inputs to the cross-correlator units becomes a 'timing' issue. These properties of auditory transduction gave theoretical support to an alternative model of ITD-detection based on a bilateral mismatch in frequency tuning, called the 'stereausis' model. Here we first review the current literature on the owl's nucleus laminaris, the equivalent to the medial superior olive of mammals, which is the site where ITD is detected. Subsequently, we use reverse correlation analysis and stimulation with uncorrelated sounds to extract the effective monaural inputs to the cross-correlator neurons. We show that when the left and right inputs to the cross-correlators are defined in this manner, the computation performed by coincidence-detector neurons satisfies conditions of cross-correlation theory. We also show that the spectra of left and right inputs are matched, which is consistent with predictions made by the classic model put forth by Jeffress.

Fashion statement

We study bilateral matching under private information about agents' characteristics. Assortative matching is the only equilibrium outcome in the absence of private information. When an information friction is present, the matching process can be improved if a payoff-irrelevant variable which we term “fashion” is introduced. Informed agents choose to adopt fashion as a signaling device. If success in matching is observed, other agents can imitate the signal. Thus, for fashion to be useful, it must constantly change. If there are more than two types of agents, both “high” and “low” fashion are needed to facilitate assortative matching.

Prediction of athletes performance using neural networks: An application in cricket team selection

Team selection for international sports competitions requires predicting performance of individual athletes. We explore the use of neural networks to rate players and select specific players for a competition. We take cricket as an example. Cricket is a game with mass following in British Commonwealth Countries as well as some other countries. National teams visit other countries for bilateral matches as well as play in World Cup tournaments. We employ neural networks to predict each cricketer’s performance in the future based upon their past performance. We classify cricketers into three categories – performer, moderate and failure. We collected data on cumulative player performance from 1985 onwards until the 2006–2007 season. The neural network models were progressively trained and tested using four sets of data. The trained neural network models were then applied to generate a forecast of the cricketer’s near term performance. Based on the ratings generated and by applying heuristic rules we recommend cricketers to be included in the World Cup 2007. We evaluate the actual performance of the cricketers in the World Cup to validate the applicability of neural networks. The results show that the neural networks can indeed provide valuable decision support in a team selection process.

On the Recognizability of Money

This paper develops a model of currency circulation under asymmetric information. Agents are heterogeneous and trade in bilateral matches. Coins are intrinsically valuable and are available in two weights, light and heavy. We characterize the equilibrium under complete information and under imperfect information about the quality of coins. We determine a set of conditions under which the two currencies circulate and are traded according to different terms of trade. We study how output, welfare, and the velocity of currency are affected by the recognizability of coins. We show that society.s welfare increases as coins become more easily recognizable.

On the Segmentation of Markets

This paper endogenizes the market structure of an economy with heterogeneous agents who want to form bilateral matches in the presence of search frictions and when utility is nontransferable. There exist infinitely many marketplaces, and each agent chooses which marketplace to be in: agents get to choose not only whom to match with but also whom they meet with. Perfect segmentation is obtained in equilibrium, where agents match with the first person they meet. All equilibria have the same matching pattern. Although perfect assortative matching is not obtained in equilibrium, the degree of assortativeness is greater than in standard models.

Bargaining and the value of money

Search models of monetary exchange have typically relied on Nash [1950. The bargaining problem. Econometrica 18, 155–162] bargaining, or strategic games that yield an equivalent outcome, to determine the terms of trade. By considering alternative axiomatic bargaining solutions in a search model with divisible money, we show that the properties of the bargaining solutions do matter both qualitatively and quantitatively for questions of first-degree importance in monetary economics such as: (i) the efficiency of monetary equilibrium; (ii) the optimality of the Friedman rule and (iii) the welfare cost of inflation.

Bilateral matching with Latin squares

We develop a general procedure to construct pairwise meeting processes characterized by two features. First, in each period the process maximizes the number of matches in the population. Second, over time agents meet everybody else exactly once. We call this type of meetings “absolute strangers.” Our methodological contribution to economics is to offer a simple procedure to construct a type of decentralized trading environments usually employed in both theoretical and experimental economics. In particular, we demonstrate how to make use of the mathematics of Latin squares to enrich the modeling of matching economies.

Endogenous Dynamic Matching and Fashion

We study bilateral matching under private information about agents' characteristics. Assortative matching is assumed to maximize total welfare and is the only equilibrium outcome in the absence of private information. When an information friction is present, the matching process can be improved if a payoff-irrelevant (sunspot) variable which we term fashion is introduced. Informed agents choose to adopt fashion as a signaling device. If success in matching is observed, other agents can imitate the signal. Thus, for fashion to be useful, it must constantly change. If there are more than two types of agents, both high fashion and low fashion are needed to facilitate efficiency in matching.

Bargaining and the Value of Money

Search models of monetary exchange have typically relied on Nash (1950) bargaining or strategic games that yield an equivalent outcome to determine the terms of trade. By considering alternative axiomatic bargaining solutions in a simple search model with divisible money, we show how this choice matters for important results such as the ability of the optimal monetary policy to generate an efficient allocation. We show that the quantities traded in bilateral matches are always inefficiently low under the Nash (1950) and Kalai-Smorodinsky (1975) solutions, whereas under strongly monotonic solutions such as the egalitarian solution (Luce and Raiffa, 1957; Kalai, 1977), the Friedman Rule achieves the first best allocation. We evaluate quantitatively the welfare cost of inflation under the different bargaining solutions, and we extend the model to allow for endogenous market composition.

Matching and Money

In Corbae, Temzelides, and Wright (2001) (hereafter, CTW) we proposed a new version of the framework that uses bilateral matching to model the exchange process, and in particular to model the use of money as a medium of exchange. Our version does not have agents meeting exogenously and at random, but rather has agents meeting endogenously. That is, agents are matched at each date subject to a stability condition that requires, roughly, that no agents prefer to be paired with each other or to be unmatched, rather than to be paired with the partners they get along the equilibrium path. While similar in spirit to the cooperative matching concept introduced by David Gale and Lloyd Shapley (1962), we had to generalize their framework to dynamic models because we are interested in monetary economics. Here we present a version of the solution concept in CTW, specialized in some ways but also generalized to include extrinsic uncertainty (sunspots). We then discuss some applications of endogenous matching models to issues that have previously been addressed using random matching, including the existence of sunspot equilibria and the efficiency of inside versus outside money. One of our main goals is to show how endogenous matching is a useful alternative to random matching. This may be interesting to those who think that bilateral trade is a reasonable friction upon which to build a theoretical foundation for monetary economics but perhaps think that random matching is an extreme and unrealistic simplification. Another goal is to provide examples where it makes a difference for substantive results how we model the matching process, and also examples where it does not. I. Endogenous Matching

Money and Price Dispersion

We relax restrictions on the storage technology in a prototypical monetary search model to study price dispersion. In this case, buyers and sellers enter matches with potentially different willingness to trade. Across the distribution of possible bilateral matches, prices generally will differ even though agents have identical preferences and technologies. We provide existence conditions for a particularly simple equilibrium pattern of exchange. We prove that in the limiting case where search frictions are eliminated, equilibrium prices are uniform. We also show that a higher initial money stock can raise the average price level and increase price dispersion.

On the Efficiency of Decentralized Exchange with Resale Possibilities

This paper studies decentralized exchange by bilateral matching and bargaining when resale is possible. Decentralized exchange involves the risk that goods and services may be allocated inefficiently; if low‐valuation buyers consume while high‐valuation buyers do not, then social welfare is reduced. If resale is possible and transaction costs are negligible, we would nevertheless expect an efficient allocation to result from decentralized exchange. This paper suggests that this depends on the nature of the commodity; while the allocation of a durable good will be efficient, the allocation of a “consumable” good need not.

Asymmetry, imperfectly transferable utility, and the role of fiat money in improving terms of trade

We modify the Kiyotaki and Wright (1991, J. Economic Theory 53, 215–235;1993; Amer. Econom. Rev. 83,63–77) framework so that there is a universal double coincidence of wants in all barter matches. We also introduce divisible service sidepayments into the model and allow agents to bargain over bundles of goods, services and money in bilateral matches. In asymmetric matches, the agent that values the other's good more dearly will typically have to make a substantial service sidepayment to complete the bargain. When sidepayments transfer utility imperfectly, the general equilibrium is inefficient. Agents barter too much. When barter is inefficient, a robust monetary equilibrium may exist which improves welfare. Both robust monetary equilibria and welfare-improving monetary equilibria require asymmetric matches, imperfectly transferable utility, and monetary exchange yields better expected terms of trade than barter. In contrast to other search models, money does not speed up trade.

Anonymous Market and Group Ties in International Trade

When trade involves differentiated products, preferential ties to a group settled abroad facilitate an exporter's entry into the foreign market by providing information and access to distribution channels. This contrasts with the difficulties experienced by an unattached producer unfamiliar with the foreign environment. Inspired by the role of coethnic ties and business groups in East Asia, we build a simple general equilibrium model of trade that formalizes this simple idea. Output is generated through bilateral matching of agents spanning a spectrum of types. Domestic matching is perfect - every trader knows the type of all others and can approach any, but international matching is random - every trader lacks the information to choose a partner's type. Group ties, however, allow perfect matching abroad to a minority of individuals who have access to them and can decide whether or not to exploit them. We show that in the absence of ties the existence of informational barriers reduces the volume of trade. By increasing trade, group ties are beneficial to the economy as a whole, but have significant distributional effects. On average, group members benefit, but some may lose; non-members lose almost without exception, while the largest losses are concentrated among those with the poorest domestic market niches.

The Role of Attention in Visual Bilateral Matching Tasks

The consistent finding of studies employing visual matching tasks has been a reaction time and accuracy advantage for judgements about stimuli presented bilaterally when compared to the average performance of the two unilateral field presentations. As with recent studies showing the influence of attention on reaction times to unilateral presentations, we hypothesized that attentional mechanisms may also play a role in the speed advantage seen with bilateral letter presentations. The present study employed random dot-patterns (“dotprimes”), presented in the upper half of the LVF, RVF, Bilateral VF, or absent, as abrupt onset peripheral cues to attract attention automatically. Letter pairs followed immediately (14 msecs) after the dot-primes in the lower half of the LVF, RVF, or Bilateral VF. The results for unilateral dot-primes, followed by unilateral letter pairs, were consistent with previous studies showing that the field advantage for a particular task can be altered using abrupt onset attentional cues, with the advantage going to the field where the attentional prime is presented. Bilateral dot-primes did reduce latencies to subsequent bilateral letter pairs, but bilateral primes also reduced latencies to both LVF and RVF letter pairs, in nearly the same proportion as for bilateral letter pairs. Latencies for RVF-primes/Bilateral-letters were as fast as for Bilateral-primes/Bilateral-letters, and both of these conditions were significantly faster than LVF-primes/Bilateral-letters. The results suggest that attention plays a relatively minor role in the bilateral field advantage, and that non-attentional factors (i.e. interhemispheric dynamics) account for most of the asymmetric unilateral-prime influence on bilateral performance. Possible interhemispheric factors which may contribute to these results are discussed.