Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ)

Performance Analysis of Multiple Input Multiple Output Free Space Optical Communication Systems

The Free Space Optical (FSO) communication i.e. optical communication without fibers is slowly becoming quite popular as fiber and its installation cost as well as difficulties involved becomes zero. The FSO communication is already making its impact in deep space communication and is expected to replace the existing optical fiber communication systems in the near future. In order to further speed up the optical communication, the Multiple Input/Multiple Output (MIMO) technology from microwave MIMO systems is being investigated. The characteristics of the Multiple Input/Multiple Output Free Space Optical communication systems using APD receivers have been discussed. The APD-based receivers for MIMO FSO systems under normal working conditions are designed and the characteristics of the components, such as InGaAs APDs, GaAs MESFET transimpedance amplifiers, a matched filter and an equalizer, etc., are considered. The probabilistic analysis of a FSO channel, APDs and noise in the FSO systems has been carried out. The main contributions in this dissertation are: obtaining the detailed closed-form expressions for the upper bounds of the error probabilities, analyzing the impacts of different parameters in MIMO FSO systems, and thorough analysis of a more complex model of the MIMO FSO system involving Webb distribution for APD-based optical receiver, the probabilistic analysis of the detection for pulse position modulation signaling and the transmitted symbol matrix for MIMO FSO equal gain combining systems. Using this detailed analysis the average symbol error probability, average bit error probability and average pairwise probability are also obtained. The equations have been derived by using the Fourier series analysis method. The modified Gauss-Chebyshev method for error probability calculation is also proposed. Results for average SEP and average BEP under different parameters are obtained and the impact of these parameters on MIMO FSO systems is also discussed

Salivary gland progenitor cells and epithelium in primary Sjögren’s syndrome:Pathology and treatment

Primary Sjögren’s syndrome (pSS) is a proinflammatory systemic autoimmune disease, characterized by dysfunction of exocrine glands (salivary and lacrimal glands) with glandular lymphocytic infiltration and autoantibody production, amongst many other systemic symptoms. The salivary gland (SG) is a primary target of pSS. Dysfunction of SG in pSS not only leads to oral dryness but is often accompanied by other oral difficulties, for example, dental caries, recurrent mouth infections, and problems with eating and speaking. However, the etiology of dry mouth development in pSS remains unresolved. Many current interventions in pSS focus on alleviating patient symptoms, for instance, using pilocarpine to stimulate saliva production. In pSS patient SGs, epithelial cells play a central role in the development of SG dysfunction, not only as primary targets of an inflamed, autoimmune environment, but also by their ability to perform a variety of immunological functions. Salivary gland progenitor cells (SGPCs) are epithelial cells that maintain the homeostasis of SG by self-replication, and differentiation into saliva producing acinar cells. The aims of the studies in this thesis can be described in the following three points: (1) to study whether dysregulated epithelial cells and SGPCs are involved in pSS, (2) to investigate the senescence state of epithelial progenitor cells in pSS and other autoimmune diseases and the possible influence of this senescence on pSS, and (3) to explore the possible pathways that could modulate the proliferation and differentiation abilities of SGPCs, which could be hopefully used for future treatment strategies of pSS