The memory consistency model in a language defines the order in which the results of write operations maybe observed through read operations. The behavior of a UPC program may depend on the timing of accesses to shared variables, so a program defines a set of possible executions, rather than a single execution. The memory consistency model constrains the set of possible executions for a given program; the user may then rely on properties that are true of all of those executions. The memory consistency model is defined in terms of the read and write operations issued by each thread in naive translation of the code, i.e., without any code transformations by the compiler, with each thread issuing operations as defined by the abstract machine defined in ISO C 5.1.2.3. A UPC compiler or run time system may perform various code transformations to improve performance, so long as they are not visible to the programmer - i.e., provided the set of externally-visible behaviors (the input/output dynamics and volatile behavior defined in ISO C 5.1.2.3) from any execution of the transformed program are identical to those of the original program executing on the abstract machine and adhering to the consistency model defined in this document.

BACKGROUND: This study evaluated in a rigorous 18-month randomized controlled trial the efficacy of an enhanced vocational intervention for helping individuals with a recent first schizophrenia episode to return to and remain in competitive work or regular schooling. METHODS: Individual Placement and Support (IPS) was adapted to meet the goals of individuals whose goals might involve either employment or schooling. IPS was combined with a Workplace Fundamentals Module (WFM) for an enhanced, outpatient, vocational intervention. Random assignment to the enhanced integrated rehabilitation program (N = 46) was contrasted with equally intensive clinical treatment at UCLA, including social skills training groups, and conventional vocational rehabilitation by state agencies (N = 23). All patients were provided case management and psychiatric services by the same clinical team and received oral atypical antipsychotic medication. RESULTS: The IPS-WFM combination led to 83% of patients participating in competitive employment or school in the first 6 months of intensive treatment, compared with 41% in the comparison group (p < 0.005). During the subsequent year, IPS-WFM continued to yield higher rates of schooling/employment (92% v. 60%, p < 0.03). Cumulative number of weeks of schooling and/or employment was also substantially greater with the IPS-WFM intervention (45 v. 26 weeks, p < 0.004). CONCLUSIONS: The results clearly support the efficacy of an enhanced intervention focused on recovery of participation in normative work and school settings in the initial phase of schizophrenia, suggesting potential for prevention of disability.