Colgajo libre córtico-perióstico de la arteria genicular descendente en el tratamiento de la seudoartritis distal de tibia

Presentamos un caso de un varón de 35 años con pseudoartrosis aséptica de tibia distal con escaso defecto óseo, intervenido previamente mediante recambio del material de osteosíntesis e injerto de cresta iliaca, que fracasó. Tras estudio de las diferentes opciones de tratamiento, se le propuso estabilizar el foco mediante enclavado endomedular y aumentar la capacidad osteogénica con un colgajo córtico-perióstico de la arteria genicular descendente, según la técnica de Sakai. Discusión: El manejo terapéutico de la pseudoartrosis distal de tibia no está del todo resuelto. Cuando otras opciones no han sido efectivas, el clavo endomedular asociado al colgajo libre córtico-perióstico de la arteria genicular descendente puede ser una opción válida para el tratamiento. Esta técnica quirúrgica supone un trabajo coordinado entre los especialistas en traumatología y cirugía plástica.We present a case of 35 years old man presented with aseptic distal tibial nonunion without bone defect. Previous unsuccessful surgical attempt, consisting on revision of the internal fixation and iliac crest bone grafting, was performed. After studying the different treatment options, we suggested him to carry out an endomedular nail stabilization of the nonunion site in combination with a descending genicular corticoperiosteal free flap to provide osteogenetic enhancement, as described by Sakai. Discussion: The treatment protocol of the distal tibial nonunion still remains controversial. When other surgical attempts are unsuccessful, the combination of endomedular nailing and descending genicular corticoperiosteal free flap, may be useful. This surgical technique may require a coordinated work between orthopaedic and plastic surgeons

Competition in the Supply Option Market

This paper develops a multiattribute competition model for procurement of short life-cycle products. In such an environment, the buyer installs dedicated production capacity at the suppliers before demand is realized. Final production orders are decided after demand materializes. Of course, the buyer is reluctant to bear all the capacity and inventory risk, and thus signs flexible contracts with several suppliers. We model the suppliers' offers as option contracts, where each supplier charges a reservation price per unit of capacity and an execution price per unit of delivered supply. These two parameters illustrate the trade-off between total price and flexibility of a contract, which are both important to the buyer. We model the interaction between suppliers and the buyer as a game in which the suppliers are the leaders and the buyer is the follower. Specifically, suppliers compete to provide supply capacity to the buyer, and the buyer optimizes its expected profit by selecting one or more suppliers. We characterize the suppliers' equilibria in pure strategies for a class of customer demand distributions. In particular, we show that this type of interaction gives rise to cluster competition. That is, in equilibrium suppliers tend to be clustered in small groups of two or three suppliers each, such that within the same group all suppliers use similar technologies and offer the same type of contract. Finally, we show that in equilibrium, supply chain inefficiencies—i.e., the loss of profit due to competition—are at most 25% of the profit of a centralized supply chain.United States. Office of Naval Research (contract N00014-95-1-0232)United States. Office of Naval Research (contract N00014-01-1-0146)National Science Foundation (U.S.) (contract DMI-0085683)National Science Foundation (U.S.) (DMI-0245352)National Science Foundation (U.S.) (CMMI-0758069)Massachusetts Institute of Technology. Center for Digital BusinessUniversity of Navarra. IESE Business School (CIIL International Center for Logistics Research

Sourcing Flexibility, Spot Trading, and Procurement Contract Structure

We analyze the structure and pricing of option contracts for an industrial good in the presence of spot trading. We combine the analysis of spot trading and buyers' disparate private valuations for different suppliers' products, and we jointly endogenize the determination of three major dimensions in contract design: (i) sales contracts versus options contracts, (ii) flat-price versus volume-dependent contracts, and (iii) volume discounts versus volume premia. We build a model in which a supplier of an industrial good transacts with a manufacturer who uses the supplier's product to produce an end good with an uncertain demand. We show that, consistent with industry observations, volume-dependent optimal sales contracts always demonstrate volume discounts (i.e., involve concave pricing). However, options are more complex agreements, and optimal option contracts can involve both volume discounts and volume premia. Three major contract structures commonly emerge in optimality. First, if the seller has a high discount rate relative to the buyer and the seller's production costs or the production capacity is low, the optimal contracts tend to be flat-price sales contracts. Second, when the seller has a relatively high discount rate compared to the buyer but production costs or production capacity are high, the optimal contracts are sales contracts with volume discounts. Third, if the buyer's discount rate is high relative to the seller's, then the optimal contracts tend to be volume-dependent options contracts and can involve both volume discounts and volume premia. However, when the seller's production capacity is sufficiently low, it is possible to observe flat-price option contracts. Furthermore, we provide links between production and spot market characteristics, contract design, and efficiency.National Science Foundation (U.S.) (contract CMMI-0758069)National Science Foundation (U.S.) (contract DMI-0245352

Establishing Nash equilibrium of the manufacturer-supplier game in supply chain management

We study a game model of multi-leader and one-follower in supply chain optimization where n suppliers compete to provide a single product for a manufacturer. We regard the selling price of each supplier as a pre-determined parameter and consider the case that suppliers compete on the basis of delivery frequency to the manufacturer. Each supplier’s profit depends not only on its own delivery frequency, but also on other suppliers’ frequencies through their impact on manufacturer’s purchase allocation to the suppliers. We first solve the follower’s (manufacturer’s) purchase allocation problem by deducing an explicit formula of its solution. We then formulate the n leaders’ (suppliers’) game as a generalized Nash game with shared constraints, which is theoretically difficult, but in our case could be solved numerically by converting to a regular variational inequality problem. For the special case that the selling prices of all suppliers are identical, we provide a sufficient and necessary condition for the existence and uniqueness of the Nash equilibrium. An explicit formula of the Nash equilibrium is obtained and its local uniqueness property is proved

Estudio comparativo del rendimiento académico y la actividad física en dos institutos de enseñanza secundaria de Andalucía (España)

Objective: To assess whether there is some relationship between academic performance and physical condition, a study based on two schools with similar features. Methodology and Method: Quantitative experimental study, in which participated 144 pupils of both sexes and aged between 14 and 18 years who were in the 4th year of Obligatory Secondary Education (ESO). It was analyzed using standardized physical fitness test and have collected data on resistance (Cooper test), speed (50 meters sprint test), flexibility (test of deep trunk flexion) and abdominal strength (abs test for minute). Results and conclusion: There is a significant relationship between academic performance and physical activity of students in the data of resistance, speed and flexibility, although there is no significant relationship between academic performance and test Abs per minute.Objetivo: Valorar si existe alguna relación entre el rendimiento académico y la condición física en un estudio realizado en dos centros educativos con características similares. Material y Método: Estudio experimental cuantitativo, en el que han participado 144 alumnos de ambos sexos de edades comprendidas entre los 14 y los 18 años que cursan 4o curso de Enseñanza Secundaria Obligatoria (ESO). Se ha analizado la condición física mediante test estandarizados donde se han recogido datos referentes a la resistencia (test de Cooper), velocidad (test de 50 metros lisos), flexibilidad (test de flexión profunda de tronco) y fuerza abdominal (test de abdominales por minuto). Resultados y Conclusiones: Los resultados muestran una relación estadísticamente significativa entre el rendimiento académico y la actividad física de los alumnos en las pruebas de resistencia, velocidad y flexibilidad, aunque los mismos no han determinado relación significativa entre el rendimiento académico y la prueba de abdominales por minuto

Outsourcing and financial performance: A negative curvilinear effect

This study asks how a firm's degree of outsourcing across all activities influences financial performance. We argue there is an optimal degree of outsourcing, where firms outsource some activities yet integrate others, and that deviations lower performance in a negatively curvilinear fashion. We find empirical support, using 1995 and 1998 data on a sample of manufacturing businesses in the Netherlands, and show that the steepness of the curve increases under conditions of high uncertainty. We show the magnitude of the uncertainty effect on performance outcomes through a post hoc scenario analysis. Thus we provide a specific, theoretically and empirically grounded prediction of how outsourcing affects performance with implications for theory and practice

Coordination in closed-loop supply chain with price-dependent returns

This paper proposes two Closed-loop Supply Chain (CLSC) games in which a manufacturer sets some green activity programs efforts and a retailer sets the selling price. Both strategies influence the return rate, which is a state variable. The pricing strategy plays a key role in the identification of the best contract to achieve coordination as well as in achieving environmental objectives. The pricing strategy influences the return rate negatively, as consumers delay the return of their goods when the purchasing (and repurchasing) price is high. We then compare a wholesale price contract (WPC) and a revenue sharing contract (RSC) mechanism as both have interesting pricing policy implications. Our result shows that firms coordinate the CLSC through a (WPC) when the sharing parameter is too low while the negative effect of pricing on returns is too severe. In that case, the low sharing parameter deters the manufacturer to accept any sharing agreements. Further, firms coordinate the CLSC when the sharing parameter is medium independent of the negative impact of pricing on returns. When the sharing parameter is too high the retailer never opts for an RSC. We find that the magnitude of pricing effect on returns determines the contract to be adopted: For certain sharing parameter, firms prefer an RSC when the price effect on return is low and a WPC when this effect is high. In all other cases, firms do not have a consensus on the contract to be adopted and coordination is then not achieved