Physiological responses of 12 sorghum (Sorghum bicolor L.) genotypes previously classified as drought resistant and susceptible upon grain yield basis were evaluated under dry and wet moisture treatments at Tucson, Arizona in 1983. In addition, the relationship of these physiological responses and their heritability estimates were also determined. Apparent photosynthesis, transpiration, diffusive resistance, temperature differentials, and leaf temperature were measured under field conditions at three intervals from planting date: 48, 62, and 77 days, respectively. Stomatal density and epicuticular wax content were determined toward the end of the season when full canopy development was reached. Stress significantly affected all characteristics measured for each genotype by a reduction in apparent photosynthesis rates, transpiration, and temperature differentials, and an increase in diffusive resistance, leaf temperature and stomatal density. The wax content response varied among genotypes irrespective of the dry and wet moisture treatments. Except for the wax content and stomatal density, all the other parameters demonstrated a high significant correlation with photosynthesis at .001 level; nevertheless, greater values were observed in the stress treatment. Analysis of variance failed to detect significant differences among the 12 germplasm sources, except for the stomatal density. Multiple regression analysis showed that leaf diffusive resistance was the first variable incorporated for photosynthesis prediction in both the dry and wet treatments. The offspring and mid-parent regression for each characteristic under both treatments provided heritability estimates (h('2) (+OR-) SE), indicating higher heritability values under the dry treatment.

The emergence of platform-independent, mobile code technologies has created big opportunities for Internet-based applications. Mobile agents are being utilized to perform a variety of tasks from personalized computing to business-critical transactions. Unfortunately, these advances were not matched by correspondent research into the reliability of these new technologies. This work has been undertaken to investigate the faulttolerance of this new paradigm. Agent programs' mobility and autonomy of execution has introduced a new class of failures different to that of traditional distributed systems. Therefore, fault tolerance is one of the main problems that must be resolved to improve the adoption of an agents' paradigm. The investigation of mobile agents reliability in this thesis resulted in the development of REMA (REliable Mobile Agents), which guarantees the reliable execution, migration, and communication of mobile agents in the presence of faults that might affect the agents hosts or their communication network. We introduced an algorithm for the transparent detection of faults that might affect agent execution, migration, and communication. A decentralized structure was used to divide the agent dynamic distributed system into network-partitioning proof spaces. Lightweight messaging was adopted as the basic error detection engine, which together with the loosely coupled detection managers provided an efficient, low overhead detection mechanism for agent-based distributed processing. The problem of taking checkpoint of agent execution is hampered by the lack of the accessibility of the underlying structure of the JVM. Thus, an alternative solution has been achieved through the REMA Checkpoint and Recovery (REMA-CR) package. REMA-CR provides the developer with powerful classes and methods that allow for capturing the critical data of agents' execution. The developed recovery protocol offers a communication-pairs, independent checkpointing strategy at a low-cost, that covers all possible faults that might invalidate reliable agent execution, migration and communication and maintains the exactly once execution property. The results and the performance of REMA confirmed our objectives of providing a fault tolerant wrapper for agents and their applications with acceptable overhead cost.

No description available.

No description available.

No description available.

No description available.

This study examined the number of conditioning trials necessary to produce associative nicotine tolerance and the changes in corticosterone levels during the procedures. Six independent groups of rats (N = 355) were run through tolerance acquisition procedures for 1, 5, or 10 conditioning sessions. Treatment groups were comprised of animals that received nicotine-environment pairings, animals that received nicotine explicitly unpaired with the drug administration environment, and control groups that received either saline throughout or no treatment. Three of the groups were tested for nicotine-induced analgesia using the tail-flick and hot-plate assays, and three groups were blood sampled after either nicotine or saline injection. Pairing of environment with nicotine produced greater tolerance for rats after 5 conditioning sessions in the tail flick and after 10 conditioning sessions in the hot-plate. Corticosterone levels were elevated in all rats given nicotine. Rats that received the nicotine-environment pairing showed a conditioned release of corticosterone in response the environment after both 5 and 10 conditioning sessions.

Therapies that promote tolerance will improve outcomes in solid organ transplantation by eliminating the need for long-term immunosuppression. This thesis investigates two possible tolerance induction mechanisms: rapamycin induced expression of regulatory T cells and re-education of the immune system using syngeneic hematopoietic stem cell transplantation. Fibrinogen-like protein 2, a effector molecule of regulatory T cells, was also determined as a key mediator in the tolerance induction pathway as depletion of fibrinogen-like protein 2 lead to allograft rejection. The feasibility of using syngeneic hematopoietic stem cells for inducing allograft tolerance was studied by setting up a murine heart and bone marrow transplant model. Syngeneic T-depleted bone marrow transplantation resulted in a slight prolongation of the graft survival time compared to the animals reconstituted with total bone marrow cells. We provide compelling evidence to suggest that fibrinogen-like protein 2 and syngeneic hematopoietic stem cells can possibly be used to induce transplantation tolerance.

Therapies that promote tolerance will improve outcomes in solid organ transplantation by eliminating the need for long-term immunosuppression. This thesis investigates two possible tolerance induction mechanisms: rapamycin induced expression of regulatory T cells and re-education of the immune system using syngeneic hematopoietic stem cell transplantation. Fibrinogen-like protein 2, a effector molecule of regulatory T cells, was also determined as a key mediator in the tolerance induction pathway as depletion of fibrinogen-like protein 2 lead to allograft rejection. The feasibility of using syngeneic hematopoietic stem cells for inducing allograft tolerance was studied by setting up a murine heart and bone marrow transplant model. Syngeneic T-depleted bone marrow transplantation resulted in a slight prolongation of the graft survival time compared to the animals reconstituted with total bone marrow cells. We provide compelling evidence to suggest that fibrinogen-like protein 2 and syngeneic hematopoietic stem cells can possibly be used to induce transplantation tolerance.

The demands of future computing, as well as the challenges of nanometer-era VLSI design, will require new design techniques and design styles that are simultaneously high performance, energy-efficient, and robust to noise and process variation. One of the emerging problems concerns the communication mechanisms between the increasing number of blocks, or cores, that can be integrated onto a single chip. The bus-based systems and point-to-point interconnection strategies in use today cannot be easily scaled to accommodate the large numbers of cores projected in the near future. Network-on-chip (NoC) interconnect infrastructures are one of the key technologies that will enable the emergence of many-core processors and systems-on-chip with increased computing power and energy efficiency. This dissertation is focused on testing, yield improvement and fault-tolerance of such NoC infrastructures. A fast, efficient test method is developed for NoCs, that exploits their inherent parallelism to reduce the test time by transporting test data on multiple paths and testing multiple NoC components concurrently. The improvement of test time varies, depending on the NoC architecture and test transport protocol, from 2X to 34X, compared to current NoC test methods. This test mechanism is used subsequently to perform detection of NoC link permanent faults, which are then repaired by an on-chip mechanism that replaces the faulty signal lines with fault-free ones, thereby increasing the yield, while maintaining the same wire delay characteristics. The solution described in this dissertation improves significantly the achievable yield of NoC inter-switch channels – from 4% improvement for an 8-bit wide channel, to a 71% improvement for a 128-bit wide channel. The direct benefit is an improved fault-tolerance and increased yield and long-term reliability of NoC based multicore systems.