In large scale distributed systems, replication is a popular technique for improving the accessibility of information and surviving the unreliability of communication networks. Pessimistic replication and optimistic replication are two contrasting replication models. They represent the two extremes in the availability-consistency. Pessimistic replication favors consistency over availability, wh...

Transactional Memory (TM) is a high-level programming abstraction for concurrency control that provides programmers with the illusion of atomically executing blocks of code, called transactions. TMs come in two categories, optimistic and pessimistic, where in the latter transactions never abort. While this simplifies the programming model, high-performing pessimistic TMs can be complex. In this...

Most software transactional memories employ optimistic concurrency control. A pessimistic semantics, however, is not without its benefits: its programming model is often much simpler to reason about and supports the execution of irreversible operations. We present a programming model that supports both optimistic and pessimistic concurrency control semantics. Our pessimistic transactions, guara...

Weather-related risks can substantially affect the crop volume depending on time and intensity of agricultural operations performed by the farmer. However, decisions under uncertainty are in some way also liable to another risk – that of excessively optimistic or pessimistic estimation of the decision maker. The paper presents results of optimistic and pessimistic farmer’s agricultural operatio...

We report the negative emotional state as pessimistic mood of a case with narcissistic personality disorder during the period of narcissistic decompensation. In addition, we identified the clinical differences between pessimistic mood and depressive disorder. An 28-year-old unmarried woman experienced herself, her life and the external object as futile and disappointing after repeated failure t...

objectives: the present study was aimed to determine the effect of psychological immunization on pessimistic attribution in female students with dyslexia. methods: the study was an experimental one, in which 60 female students with dyslexia were selected randomly from learning disabilities centers in isfahan. subjects  were  assigned to experimental and control groups (15 individuals in each gr...