Reputation in Long-Run Relationships

We model a long-run relationship as an infinitely repeated game played by two equally patient agents. In each period, the agents play an extensive-form game of perfect information. There is incomplete information about the type of player 1 while player 2’s type is commonly known. We show that a sufficiently patient player 1 can leverage player 2’s uncertainty about his type to secure his highest payoff in any perfect Bayesian equilibrium of the repeated game.Repeated Games, Reputation, Equal Discount Factor, Long-run Players. JEL Classification Numbers: C73, D83

Reputation in the Long-Run with Imperfect Monitoring

We study an infinitely repeated game where two players with equal discount factors play a simultaneous-move stage game. Player one monitors the stagegame actions of player two imperfectly, while player two monitors the pure stagegame actions of player one perfectly. Player one’s type is private information and he may be a “commitment type,” drawn from a countable set of commitment types, who is locked into playing a particular strategy. Under a full-support assumption on the monitoring structure, we prove a reputation result for games with locally nonconflicting interests or games with strictly conflicting interests: if there is positive probability that player one is a particular type whose commitment payoff is equal to player one’s highest payoff, consistent with the players’ individual rationality, then a patient player one secures this type’s commitment payoff in any Bayes-Nash equilibrium of the repeated game. In contrast, if the type’s commitment payoff is strictly less than player one’s highest payoff consistent with the players’ individual rationality, then the worst perfect Bayesian equilibrium payoff for a patient player one is equal to his minimax payoff.Repeated Games, Reputation, Equal Discount Factor, Long-run Players,imperfect Observation, Complicated Types, Finite Automaton JEL Classification Numbers: C73, D83

Bargaining and Reputation in Search Markets

In a two-sided search market agents are paired to bargain over a unit surplus. The matching market serves as an endogenous outside option for agents in a bargaining relationship. Behavioral agents are (strategically inflexible) commitment types that demand a constant portion of the unit surplus. The steady state frequency of behavioral types in the market is determined in equilibrium. We show, even if behavioral types are negligible, they substantially effect the terms of trade and efficiency. In an unbalanced market where the entering flow of one side is short, bargaining follows equilibrium play in a bargaining game with one-sided reputation, the terms of trade are determined by the commitment types on the short side, and commitment types improve efficiency. In a balanced market where the entering flows of the two sides are equal, bargaining follows equilibrium play in a bargaining game with two-sided reputation and commitment types cause inefficiency. An inefficient equilibrium with persistent delays and break-ups is constructed. The magnitude of inefficiency is determined by the inflexible demands of the commitment types and is independent of the fraction of the commitment types entering the market.Bargaining, Reputation, Search, Dynamic Matching, War-of-Attrition. JEL Classification Numbers: C78, D83

Reputation with long run players and imperfect observation

Previous work shows that reputation results may fail in repeated games between two long-run players with equal discount factors. We restrict attention to an infinitely repeated game where two players with equal discount factors play a simultaneous move stage game where actions of player 2 are imperfectly observed. The set of commitment types for player 1 is taken as any (countable) set of finite automata. In this context, for a restricted class of stage games, we provide a one sided reputation result. If player 1 is a particular commitment type with positive probability and player 2's actions are imperfectly observed, then player 1 receives his highest pay-off, compatible with individual rationality, in any Bayes-Nash equilibria, as agents become patient

A two-sided reputation result with long run

Cripps et al. (2005) conjectured that in an infinitely repeated game with two equally patient players, if there is positive probability that the players could be Stackelberg types, then equilibrium behavior would resemble a war of attrition, i.e., a two-sided reputation result would hold. In this note we show that this conjecture is indeed true for a wide set of stage games for which the one-sided reputation result of Atakan and Ekmekci (2008) holds

Auctions, actions, and the failure of information aggregation

We study a market in which k identical and indivisible objects are allocated using a uniform-price auction where n > k bidders each demand one object. Before the auction, each bidder receives an informative but imperfect signal about the state of the world. The good that is auctioned is a common-value object for the bidders, and a bidder's valuation for the object is determined jointly by the state of the world and an action that he chooses after winning the object but before he observes the state. We show that there are equilibria in which the auction price is completely uninformative about the state of the world and aggregates no information even in an arbitrarily large auction. In the equilibrium that we construct, because prices do not aggregate information, agents have strict incentives to acquire costly information before they participate in the market. Also, market statistics other than price, such as the amount of rationing and bid distributions contain extra information about the state. Our findings sharply contrast with past work which shows that in large auctions where there is no ex-post action, the auction price aggregates information

Bargaining and reputation in search markets

In a two-sided search market agents are paired to bargain over a unit surplus. The matching market serves as an endogenous outside option for a bargaining agent. Behavioral agents are commitment types that demand a constant portion of the surplus. The frequency of behavioral types is determined in equilibrium. Even if the frequency of behavioral types is negligible, they affect the terms of trade and efficiency. In an unbalanced market where the entering flow of one side is short, there is one-sided reputation building in bargaining, and commitment types on the short side determine the terms of trade. In a balanced market where the entering flows are equal, there is twosided reputation building in bargaining, and reputation concerns lead to inefficiency. An equilibrium with persistent delays is constructed. The magnitude of inefficiency is determined by the demands of the commitment types and is independent of their frequency. Access to the market exacerbates bargaining inefficiencies caused by behavioral types, even at the frictionless limit of complete rationality

Reputation with long run players and imperfect

We model a long-run relationship as an infinitely repeated game played by two equally patient agents. In each period, the agents play an extensive-form game of perfect information. There is incomplete information about the type of player 1 while player 2's type is commonly known. We show that a sufficiently patient player 1 can leverage player 2's uncertainty about his type to secure his highest payoff in any perfect Bayesian equilibrium of the repeated game

Son dönem böbrek hastalarında gelişen sekonder hiperparatiroidizmin cerrahi tedavisi: Cerrahi yaklaşımlar ve olgu sunumları

Amaç: Son dönem böbrek hastalığı dünya çapında bir sağlık problemidir. Bu hastaların yaşam süreleri uzadıkça sekonder hiperparatiroidizm gibi ek patolojiler de gelişmektedir. Bu çalışmanın amacı sekonder hiperparatiroidizme cerrahi yaklaşımları gözden geçirmek ve kendi tecrübelerimizi sunmaktır. Hastalar ve Yöntemler: Bu retrospektif çalışmaya 2004 ve 2008 yılları arasında kronik böbrek hastalığı tanısıyla ameliyat edilen beş erkek hasta (ort. yaş 38.6) dahil edildi. Hasta bilgileri hastane kayıtlarından toplandı. Bulgular: Hastaların ortalama hemodiyaliz süresi 106.8 aydı. Bütün hastalar ameliyat öncesi dönemde ultrasonografi ve sintigrafi ile incelendi. Hastaların ameliyat öncesi ve sonrası dönemde ortalama serum PTH değeri 2097 ng/ ml ve 36.5 ng/dl, Ca 11.48 mg/dl ve 6.2 mg/dl, P 7.5 mg/dl ve 4.4 mg/dl, ALP 527 IU/L ve 89 IU/L idi. Bütün hastalara total paratiroidektomi ve sternokleidomastoid kasa ototransplantasyon yapılırken bir hastaya ek olarak sağ tiroidektomi yapıldı. Ameliyat sonrası dönemde tüm hastalar oral kalsiyum karbonat ve kalsitriol kullandılar. Hiçbir hastada ciddi komplikasyon görülmedi. Ortalama hastanede kalış süresi 4.6 gündü. Hastaların hepsinde serum PTH düzeyleri 300 ng/dl altında seyretti ve hiçbir hastada takipler esnasında nüks hiperparatiroidizm görülmedi. Sonuç: Sekonder hiperparatiroidizmin cerrahi tedavisi için birçok yöntem olsa da total paratiroidektomi ve ototransplantasyon düşük nüks ve komplikasyon oranları ile son dönem böbrek hastalarında gelişen sekonder hiperparatiroidizmin için en kabul edilen tedavi metotlarındandır.Objectives: End-stage renal disease is a worldwide public health problem. While the survival time of the patients extends, additional pathologies such as secondary hyperparathyroidism occurs. The aim of the study is to review the surgical approaches to secondary hyperparathyroidism and present our experiences. Patients and Methods: This retrospective study included five male patients (mean age 38.6 years) who were operated on for chronic renal failure between 2004 and 2008. The data of patients were collected from hospital records. Results: The mean duration of hemodialysis was 106.8 months. All patients had ultrasonography and scintigraphy preoperatively. The mean value of preoperative and postoperative serum PTH was 2097 ng/ml and 36.5 ng/dl, Ca 11.48 mg/dl and 6.2 mg/dl, P 7.5 mg/dl and 4.4 mg/dl, ALP 527 IU/L and 89 IU/L. Total parathyroidectomy and sternocleidomastoid muscle autotransplantation was performed in all patients and one patient had right thyroidectomy in addition. Postoperatively, all patients received oral calcium carbonate and calcitriol. No serious postoperative complications occurred in any of these cases. The duration of hospitalization was 4.6 days on the average. Serum PTH was kept constantly below 300 ng/L in all cases in follow-up and no recurrent hyperparathyroidism was detected. Conclusion: Although there are many types of surgery techniques in treatment of secondary hyperparathyroidism, total parathyroidectomy with autografting is the most accepted procedure with low recurrent and complication rate in end-stage renal disease patients

Photorefractive keratectomy after descemet membrane endothelial keratoplasty

Introduction: A 26 year old female ,who had undergone descemet membrane endothelial keratoplasty(dmek) a yer ago on her left eye, was evaluated for photorefractive keratectomy(prk) due to residual refractive errors. Purpose: To evaluate the efficacy of prk for refractive errors in a patient who had undergone dmek surgery a year ago Methods: Prior to surgery a total ophthalmic examinations was conducted. Corneal topography, specular microscopy and optical coherence tomography for macular evaluation was evaluated. Prk was performed with 26 micron total ablation depth and 236 pulses. All opththalmic examinations were repeated after surgery at post operatively Results: The uncorrected visual acuity (UCVA) was 0.2 and best corrected visual acuity (BCVA) was 0.7 (with 2.75 – 4.00 *90) before surgery. The K1-K2 values were 37,5 - 41.2 D and the axis was 179 and the calculated astigmatism was 3.7D . The pre surgical keratometry was 560 microns (thinnest).The corneal endothelial values with specular microscopy was 1901.8 (maximum size)µm2 and cell density was 1155 (/mm2) preoperatively. After surface ablation was performed, the calculated thinnest keratometry was decreased to 498 microns at first month and increased to 560 microns at 5th month. The K1 – K2 values were 39.2- 40.0 D and the axis was 154 at first month. The UCVA was 0.5 and BCVA was 0.8 ( with -1.00- 0.75 *16) After 30 days ,endothelial specular values were 1870.3 µm2 (max size) and 1102(/ mm2) ( cell density) The central macular thickness was measured 231 microns preoperatively and 256 microns after first month. Conclusion: Surface ablation procedures seems to be safe and effective for correcting refractive errors in patients those had dmek surgery for other reasons. Precise pre opereative measurements and careful ophthalmic examination is a must. Further long follow time included studies need to be done