Flutter is an extremely violent instability that may result in catastrophic failure. Thus, flutter clearance test is one of the critical phases in qualification of an aircraft's airworthiness. During design and development process of an aircraft, flutter problems were experienced on an aerodynamic surface (horizontal tail). In order to tackle the observed problem, a number of approaches to optimize the design for flutter speed were computationally and experimentally studied and evaluated. This paper presents and discusses the outcomes of these studies. A hybrid approach based on evaluations and design change constraints has been proposed to suppress the flutter of the horizontal tail.
Objective: To determine important errors in initial Gram staining of clinical specimens and evaluate the types of Gram-stain errors.
Study Design: Cross-sectional study.
Place and Duration of Study: Microbiology Department, Armed Forces Institute of Pathology, Rawalpindi Pakistan, from Aug 2018 to Feb 2019.
Methodology: Gram staining and culture inoculation of all specimens were performed per recommended guidelines. The Gram stain results on day-0 were compared with the results of the culture on day-2. There was no discrepancy if similar organisms were obtained on culture as on Gram stain. Nevertheless, if the Gram stain and culture results were not similar, it was termed a discrepancy. The consultant microbiologist reviewed all discrepant slides, and if not resolved, possible causes of error were sought, and the results documented.
Results: Of the total 300 clinical specimens, errors were observed in the initial gram staining of 29 specimens (9.7%), whereas 271(90.3%) specimens were error-free. Upon evaluating these 29 errors, 11(38.0%) were observer errors which were resolved when reviewed by a consultant microbiologist. 14(48.0%) were technical errors, and 4(14.0%) results were discrepant due to the presence of anaerobic organisms, missed on initial aerobic cultures.
Conclusion: The frequency of Gram stain errors in our study (9.7%) is not very high; nevertheless, it can have severe consequences in critical samples from seriously ill patients if wrong empirical antimicrobial treatment is begun based on a wrong initial Gram stain result.
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