When a company decides to outsource a service, the most important reasons for doing so usually are to focus on core business, to be able to access high-quality services at lower costs, or to benefit from risk sharing. However, service contracts typically follow a structure whereby both owner and contractor attempt to maximize expected profits in a noncoordinated way. Previous research has considered supply chain coordination by means of contracts but is based on unrealistic assumptions such as perfect maintenance and infinite time-span contracts. In this work, these limitations are overcome by defining the supply chain through a preventive maintenance strategy that maximizes the total expected profit for both parties in a finite time-span contract. This paper presents a model to establish such conditions when maintenance is imperfect, and the contract duration is fixed through a number of preventive maintenance actions along a significant part of the asset life cycle under consideration. This formulation leads to a win-win coordination under a set of restrictions that can be evaluated a priori. The proposed contract conditions motivate stakeholders to continually improve their maintenance services to reach channel coordination in which both parties obtain higher rewards.where t represents time, k corresponds to the index of the k-th preventive action, and˛is the maintenance improvement factor, 0 6˛6 1 3. Corrective maintenance is minimal. 4. Direct (spare+labor) costs and length of PM are C p (money units, mu) and T p (time units, tu), respectively. 5. Direct costs and length of corrective maintenance are, respectively, C r (mu) and T r (tu). 6. The interval between PM is T (tu).

The distribution of ABO blood groups and color vision deficiency have been determined in a sample of 827 inhabitants of Valparaiso city (males and females), aged 12 through 18 years. Analysis of these data is based upon geographic subdivisions of the city known to differ ethnically and socio-economically. The association of these latter variables with the two genetic markers can be seen in the variation between the subgroups in the ABO gene frequencies and in the color blindness frequency. Some subgroups have gene frequencies with respect to these attributes similar to Caucasoid populations while others are similar to Indian Chilean populations. Clearly subdivisions of this nature must be considered in any genetic analysis of a mixed Chilean population.

Dental characteristics were studied on 60 skulls that belong to a population of Diaguitas Indians of approximately the Tenth Century. Mesiodistal crown diameters of permanent teeth were as follows: central incisors (8.77 mm), lateral incisors (7.23 mm), canines (8.40 mm), first maxillary molars (10.77 mm), second maxillary molars (10.71 mm), first mandibular molars (11.13 mm), and second mandibular molars (10.17 mm).Also determined was the frequency of shovel shaped incisors (80.30% ), groove and cusp patterns of mandibular molars (Y5 73.40%), groove and cusp patterns of maxillary molars (H4 87.25%), and mesiopalatal version of maxillary incisors (66.20%). No skull showed Carabelli's cusp. The findings were compared with those for different populations past and living. The results suggest that the affiliation of the population analyzed was mongoloid.

The frequency of Carabelli's cusp (27.24%) and shovel‐shaped incisors (45.72%) were determined in a sample of students from the city of Valparaíso. These values are intermediate between those found in Caucasian and Mongolian populations. A sexual dimorphism was observed for shovel‐shaped incisors; the relation of this trait to a socio‐economic index and occlusal type is indicated. Carabelli's cusp is found to vary with the number of foreign ancestors of an individual and his or her ABO blood group and color vision. There is also evidence that Carabelli's cusp serves better as an ethnic marker in a mixed population such as ours than does shovel‐shaped incisors. This is thought to be due to the less complicated genetic basis of the former. It is also shown that the two traits are independent in their expression.