Analysis of proliferative activity in oral gingival epithelium in immunosuppressive medication induced gingival overgrowth

BACKGROUND: Drug-induced gingival overgrowth is a frequent adverse effect associated principally with administration of the immunosuppressive drug cyclosporin A and also certain antiepileptic and antihypertensive drugs. It is characterized by a marked increase in the thickness of the epithelial layer and accumulation of excessive amounts of connective tissue. The mechanism by which the drugs cause gingival overgrowth is not yet understood. The purpose of this study was to compare proliferative activity of normal human gingiva and in cyclosporine A-induced gingival overgrowth. METHODS: Gingival samples were collected from 12 generally healthy individuals and 22 Cyclosporin A-medicated renal transplant recipients. Expression of proliferating cell nuclear antigen was evaluated in formalin-fixed, paraffin-embedded gingival samples using an immunoperoxidase technique and a monoclonal antibody for this antigen. RESULTS: There were differences between the Cyclosporin A group and control group in regard to proliferating cell nuclear antigen and epithelial thickness. In addition, the degree of stromal inflammation was higher in the Cyclosporin A group when compared with the control group. CONCLUSION: The results suggest that the increased epithelial thickness observed in Cyclosporin A-induced gingival overgrowth is associated with increased proliferative activity in keratinocytes

Rarefaction Effects on the Outflow Boundary Conditions for External Subsonic Flows

In continuum-flow simulations, subsonic outflow boundary conditions are controlled solely by the Mach number. Such boundary conditions are not suitable for rarefied flows, and it is necessary to include the Knudsen number into them. In the present study, this is done for external flows, by introducing a simple model which adjusts the macroscopic boundary properties (from which the incoming molecules are calculated) according to the local rarefaction. A bridging formula is used between the continuum and free-molecule limits, and the results show considerable improvement in the rarefied-flow simulations

İnşaat projelerinde risklerin ve maliyet artışının analoji kurma yöntemiyle tahmin edilmesi.

Project cost increase is the main concern in international construction projects which usually results in disputes and conflicts among the project participants. The aim of this thesis is to construct a database that represents risk event history regarding international construction projects and construct a cost overrun prediction model. It is hypothesized that magnitudes of project related, company related and country related risk factors can be predicted by assessing the level of vulnerability by analogical reasoning with previous projects. The vulnerability and risk factors can further be used to predict cost overrun in the bid preparation stage of international construction projects. Thus, prediction models that link vulnerability with risk factors and cost are constructed by using a dataset of 166 international construction projects, which consists of 66 real and 100 hypothetical cases. Case-based reasoning (CBR) technique is used to construct the prediction models. After testing the performance of various CBR models using different weight generation and retrieval methods, error rate of +/- 7.15 % cost increase is achieved. The utilization of CBR models in the prediction of potential risk sources and cost overrun is demonstrated by a real case study. Finally, the benefits and pitfalls of using analogical reasoning for risk and cost overrun assessment of construction projects are discussed.M.S. - Master of Scienc

On the outflow boundary conditions for subsonic rarefied external flows

The effects of outflow boundary conditions are investigated on subsonic external flows in the transitional regime. Calculations have been performed for two-dimensional flows over a finite flat plate using the direct simulation Monte Carlo method, concentrating on Knudsen numbers of 0.02 and higher. At the outflow boundaries, the incoming molecules are determined by using a model which adjusts the outflow boundary conditions according to the local rarefaction assuming equilibrium. The results show sensitivity to the model at low Mach numbers but as the speed increases the sensitivity decreases. The effects of domain size, sample size and doing the extrapolations from the adjacent boundary cells rather than following the streamline trajectories are shown

Heat transfer simulation of rarefied laminar flow past a circular cylinder

Direct simulation Monte Carlo calculations are performed to study the heat transfer in laminar, rarefied flows past a circular cylinder. Results are obtained for flows with Knudsen numbers of 0.02 and 0.2; Mach numbers of 0.102 and 0.4, and also several cylinder temperatures are considered. Calculations show that these flows are attached except for the one with a Knudsen number of 0.02 and a Mach number of 0.4 in which separation occurs in the wake of the cylinder. Results are little affected by the changes in the outflow boundary conditions but show sensitivity to the domain size due to the subsonic nature of the flows. Mach number of 0.4 results show that when the cylinder temperature is higher than the free stream temperature by less than 10 degrees C, a net heat transfer occurs from the air stream into the cylinder which indicates that the classical convection heat transfer equation needs to be modified under rarefied conditions. The findings are in agreement with the limited data available in the literature

Numerical Simulation of Rarefied Laminar Flow past a Circular Cylinder

Numerical simulations have been obtained for two-dimensional laminar flows past a circular cylinder in the transitional regime. Computations are performed using the direct simulation Monte Carlo method for Knudsen numbers of 0.02 and 0.2 and Mach numbers of 0.102 and 0.4. For these conditions, Reynolds number ranges from 0.626 to 24.63 and the flows are steady. Results show that separation occurs in the wake region for the flow with Mach number of 0.4 and Knudsen number of 0.02, but for the other eases flows are attached. The effects of flow speed, rarefaction, domain size and the outflow boundary conditions are investigated. Results show sensitivity to the domain size and the outflow boundary conditions in the low Mach number calculations, but as the speed increases the sensitivity decreases. Although no experimental data are available for direct comparison, the present calculations are found to be in very good agreement with the findings of other researchers

DSMC Simulations of low-density choked flows in parallel-plate channels

Rarefied choked flows in parallel-plate channels have been studied using the direct simulation Monte Carlo technique. Calculations are performed for various transitional flows, and results are presented for the computed flowfield quantities, wall pressures and discharge coefficients. Comparisons are made with the available experimental data, and the physical and numerical factors which affect the solutions are discussed. Separate calculations are performed for the "nearly-incompressible" rarefied channel flows in which density variations are small. The calculations of this study indicate that the DSMC simulations are well suited for determining transitional flows from free-molecule limit to laminar flow regime, but become prohibitive for turbulent channel flow simulations with today's computers

A Monte Carlo-based Poisson's equation solver parallelized with Coarray Fortran

Poisson's equation is found in many scientific problems, such as heat transfer and electric field calculations. Although many different techniques are involved in solving Poisson's equation, we focused on the Monte Carlo method (MCM). We preferred the MCM not only because of its simple algorithm but also for its excellent parallel efficiency. Parallelization is one of the most effective techniques for reducing computation time. Among many parallelization paradigms, such as OpenMP (open multiprocessing), MPI (message passing interface), and PGAS (partitioned global address space), we adopted the PGAS-based Coarray Fortran (CAF). In this paper, we demonstrated that parallelization of Poisson's equation solver with CAF was quite painless. After parallelization, we solved Poisson's equation for a nonrectangular domain. We started with a workstation that consisted of 8 cores and we continued with a Cray supercomputer of up to 512 cores. The results of the parallel solvers were validated using exact solutions. We demonstrated that the error was less than 1.6%. Additionally, solution times and speedups of the CAF-based solver were compared with a solver that utilized MPI or OpenMP. OpenMP was not able to compete against CAF and MPI because of the "while" loop restriction. The CAF-based solver performed slightly better (7.5%) than the MPI provided that core numbers were between 2 and 32. However, CAF and MPI performed similarly for higher numbers of cores