Measuring the effects of heterogeneity on distributed systems

Distributed computer systems in daily use are becoming more and more heterogeneous. Currently, much of the design and analysis studies of such systems assume homogeneity. This assumption of homogeneity has been mainly driven by the resulting simplicity in modeling and analysis. A simulation study is presented which investigated the effects of heterogeneity on scheduling algorithms for hard real time distributed systems. In contrast to previous results which indicate that random scheduling may be as good as a more complex scheduler, this algorithm is shown to be consistently better than a random scheduler. This conclusion is more prevalent at high workloads as well as at high levels of heterogeneity

A distributed scheduling algorithm for heterogeneous real-time systems

Much of the previous work on load balancing and scheduling in distributed environments was concerned with homogeneous systems and homogeneous loads. Several of the results indicated that random policies are as effective as other more complex load allocation policies. The effects of heterogeneity on scheduling algorithms for hard real time systems is examined. A distributed scheduler specifically to handle heterogeneities in both nodes and node traffic is proposed. The performance of the algorithm is measured in terms of the percentage of jobs discarded. While a random task allocation is very sensitive to heterogeneities, the algorithm is shown to be robust to such non-uniformities in system components and load

Role of Melatonin and/or Vitamin B Complex against Hormonal Changes in Epinephrine-Stressed Rats

Abstract The current study aimed to investigate the effect of intramuscular injection of melatonin (MT)(1mg / kg) and/or vitamin Bcomplex (Tri-B) (20 mg/kg) on the hormonal changes induced by Epinephrine (Epi) (0.02 mg/kg) in male albino rats. Intramuscular administration of Epi induced significant elevations in adrenocorticotropic hormone (ACTH), corticosterone (CORT),2 2 T triiodothyronine 2 2 T (TR 3 R) and thyroxine (TR 4 R) levels after the two experimental durations. On the other hand, luetinizing hormone (2 2 T LH)2 2 T , testosterone , prolactin (PRL) and growth hormone (GH) levels were decreased under the same conditions. Melatonin treatment seems to constitute a selection therapy, by improving ATCH, CORT, TR 3 R ,TR 4 R and GH levels but has no effect on the low levels of LH , testosterone and PRL. Also, the data suggested that Tri-B injection partially improved the different endocrinological changes of Epi