Bilal Ashfaq Ahmed

Drusen detection from colored fundus images for diagnosis of age related Macular degeneration

Age related Macular degeneration (AMD) is an ocular disease caused by the extracellular material deposit at retinal pigment level known as drusen. AMD is the major cause of gradual vision loss. Early detection of the disease can be helpful to prevent blindness. Automatic fundus image analysis plays an important role for early diagnose of AMD. In this paper a novel method is presented for the detection of soft and hard drusen. After the preprocessing step the proposed method computes color and Gabor filter based features for each pixel to classify and extract all possible drusen pixels. Connected component labeling removes the suspicious pixels from drusen region and at the end optic disk is removed to avoid false positive pixels. The performance of proposed system was evaluated on publically available database STARE and it achieves 96% accuracy for drusen detection over STARE. The proposed algorithm shows significant improvement in detecting drusen for diagnosing AMD at earlier stage.

Urinary Excretion and Renal Clearance of Allopurinol in Female Gout Patients

Drugs removed from the body either without changing from its original form or in the form of its metabolite. Allopurinol drug decreases uric acid level in blood and it is used for the treatment of gout and tumor lysis syndrome. Allopurinol and its active metabolite oxipurinol stop the function of xanthine oxidase which forms uric acid from xanthine and hypoxanthine. In this study a quantitative assay using high-performance liquid chromatography (HPLC) with UV-detection was used as a method for quantification of allopurinol and oxipurinol in human serum and urine samples of gout patients after allopurinol administration. The urinary excretion and renal clearance was determined in male gout patients. Blood and urine samples of the human male patients of gout (n=10) after the oral administration of 300mg drug were taken at different time intervals. Results of this study show that there is slow metabolism of allopurinol inside body due to its extensive bonding with blood proteins. Statistical analysis was performed by expressing all the data as mean and ± standard error of mean. The effect of pH and diuresis on renal clearance of allopurinol was studied by regression analysis.

Proportional Load Sharing and Stability of DC Microgrid with Distributed Architecture Using SM Controller

DC microgrids look attractive in distribution systems due to their high reliability, high efficiency, and easy integration with renewable energy sources. The key objectives of the DC microgrid include proportional load sharing and precise voltage regulation. Droop controllers are based on decentralized control architectures which are not effective in achieving these objectives simultaneously due to the voltage error and load power variation. A centralized controller can achieve these objectives using a high speed communication link. However, it loses reliability due to the single point failure. Additionally, these controllers are realized through proportional integral (PI) controllers which cannot ensure load sharing and stability in all operating conditions. To address limitations, a distributed architecture using sliding mode (SM) controller utilizing low bandwidth communication is proposed for DC microgrids in this paper. The main advantages are high reliability, load power sharing, and precise voltage regulation. Further, the SM controller shows high robustness, fast dynamic response, and good stability for large load variations. To analyze the stability and dynamic performance, a system model is developed and its transversality, reachability, and equivalent control conditions are verified. Furthermore, the dynamic behavior of the modeled system is investigated for underdamped and critically damped responses. Detailed simulations are carried out to show the effectiveness of the proposed controller.

Production and Characterization of Streptokinase Enzyme by Using Streptococcus mutans Strain in Liquid State Fermentation through Corn Steep Liquor (CSL) Substrate

Background: Enzymes play a very important and central role in the chemical reactions, occurring in biological systems. The study of enzymes has an immense practical importance. They have high catalytic power, many times greater than the synthetic catalysts. Vascular blockage can cause serious consequences leading to death by a thrombus (blood clot) developed in the circulatory system. Streptokinase is an extracellular protein Trans-located by many strains of beta-hemolytic Streptococci. By converting the plasminogen, to fibrin lytic enzyme, plasmin, it favor’s the blood clot lysis. Results: The main objective of this research was the production of streptokinase in liquid state fermentation using CSL substances as substrate from Streptococcus species which was grown on blood agar media. Streptococcus mutans was selected for streptokinase production using corn steep liquor as substrate. Corn steep liquor (CSL) was applied in different concentrations ranging from 0.1% to 0.8% in liquid state fermentation culture medium and fibrin clot lysis method was used for enzyme assay. Conclusion: Among different concentrations of CSL 0.3% was selected as optimum concentration, 44% blood lysis was observed by CSL in liquid state fermentation culture medium for streptokinase production.

Drusen exudate lesion discrimination in colour fundus images

Automatic screening and diagnosis of ocular disease through fundus images are in place and considered worldwide. One of the leading sight loosing disease known as age related macular degeneration (AMD) has many proposed automatic screening systems. These systems detect yellow bright lesion and through the number of lesion and their size the disease is graded as advance and earlier stage. It becomes difficult for these systems to differentiate drusens from exudates another bright lesion associated with Diabetic retinopathy. These two lesions look similar on retinal surface. Differentiating these two lesions can improve the performance of any automatic system. In this paper we proposed a novel approach to discriminate these lesions. The approach consists of two stage procedure. The first stage after pre-processing detects all bright pixels from the image. The suspicious pixels are removed from the detected region. On the second stage bright regions are classified as drusen and exudates through Support Vector Machine (SVM). Proposed method was evaluated on publically available dataset STARE. The system achieve 92% accuracy.