Is fine needle aspiration cytology a useful tool for the diagnosis of tuberculous lymphadenitis

Objective: To study the role of fine needle aspiration cytology (FNAC) in the diagnosis of tuberculous lymphadenitis and find a place for FNAC as laboratory diagnostic method in tuberculosis (TB) control programmes. Design: Prospective laboratory study. Method: Duplicate smears from 127 lymphnode aspiration were prepared. Both slides were air-dried. Giemsa stain for cytological examination and Ziehl-Neelsen stain for demonstration of acid fast bacillus(AFB) were used and examined by a pathologist and laboratory technologist respectively. Setting: Tigrai Regional Health Research and Laboratory Centre which is the only unit with microbiological and cytopathological service in the region. Subjects: Patients with one or more enlarged lymph nodes who were sent for FNAC were included. Results: The AFB positivity among the cytologically diagnosed cases of TB lymphadenitis was 56.77%. If we had used culture media for Mycobacterium spp, the positivity would have probably been higher. The positivity rate varied depending on the type of the aspirate. Caseous aspirate showed a higher positivity rate of 60.47% whereas no AFBs were detected in haemorrhagic aspirates. Conclusion: This study has demonstrated the usefulness of FNAC in the diagnosis of TB lymphadenitis and the national TB and leprosy control programmes should encompass FNAC as a diagnostic means instead of biopsy which is more invasive and costly.East African Medical Journal, May 1999, 260-26

Applications of Polynomial Chaos-Based Cokriging to Aerodynamic Design Optimization Benchmark Problems

In this work, the polynomial chaos-based Cokriging (PC-Cokriging) is applied to a benchmark aerodynamic design optimization problem. The aim is to perform fast design optimization using this multifidelity metamodel. Multifidelity metamodels use information at multiple levels of fidelity to make accurate and fast predictions. Higher amount of lower fidelity data can provide important information on the trends to a limited amount of high-fidelity (HF) data. The PC-Cokriging metamodel is a multivariate version of the polynomial chaos-based Kriging (PC-Kriging) metamodel and its construction is similar to Cokriging. It combines the advantages of the interpolation-based Kriging metamodel and the regression-based polynomial chaos expansions (PCE). In the work the PC-Cokriging model is compared to other metamodels namely PCE, Kriging, PC-Kriging and Cokriging. These metamodel are first compared in terms of global accuracy, measured by root mean squared error (RMSE) and normalized RMSE (NRMSE) for different sample sets, each with an increasing number of HF samples. These metamodels are then used to find the optimum. Once the optimum design is found computational fluid dynamics (CFD) simulations are rerun and the results are compared to each other. In this study a drag reduction of 73.1 counts was achieved. The multifidelity metamodels required 19 HF samples along with 1,055 low-fidelity to converge to the optimum drag value of 129 counts, while the single fidelity models required 155 HF samples to do the same

Dynamic Current and Power Distributions in a Submerged Arc Furnace

Most submerged arc furnaces used for the production of ferroalloys run on three-phase alternating current. This affects the electrical operation of the furnace and thus it is of interest to study alternating current distributions in the system. This work presents computations of alternating electric current distributions inside an industrial submerged arc furnace for silicon production. A 3D model has been developed in ANSYS Maxwell using the eddy current solver. In each phase, electrode, central arc, crater, crater wall and side arcs that connect electrode and crater wall are taken into account. In this paper, the dynamic current distributions in different parts of the furnace, as well as skin and proximity effects in and between electrodes are presented. Moreover, active and reactive power distributions in various components of the furnace are quantified