Timothy Kwa

Timothy Kwa


Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 November 2021 in Clinical Lymphoma Myeloma and Leukemia
Verified
Journal Article
Closed access
kokeb Desekokeb Dese
kokeb Dese
HRHakkins Raj
Hakkins Raj
GAGelan Ayana
Gelan Ayana
TYTilahun Yemane
Tilahun Yemane
WAWondimagegn Adissu
Wondimagegn Adissu
TKTimothy Kwa
Timothy Kwa

4 October 2022 in Cancer Control
Verified
Journal Article
Open access
BWBeshatu Debela Wako
Beshatu Debela Wako
kokeb Desekokeb Dese
kokeb Dese
RURoba Elala Ulfata
Roba Elala Ulfata
TNTilahun Alemayehu Nigatu
Tilahun Alemayehu Nigatu
STSolomon Kebede Turunbedu
Solomon Kebede Turunbedu
TKTimothy Kwa
Timothy Kwa
Objectives: Now a days, squamous cell carcinoma (SCC) margin assessment is done by examining histopathology images and inspection of whole slide images (WSI) using a conventional microscope. This is time-consuming, tedious, and depends on experts’ experience which may lead to misdiagnosis and mistreatment plans. This study aims to develop a system for the automatic diagnosis of skin cancer margin for squamous cell carcinoma from histopathology microscopic images by applying deep learning techniques. Methods: The system was trained, validated, and tested using histopathology images of SCC cancer locally acquired from Jimma Medical Center Pathology Department from seven different skin sites using an Olympus digital microscope. All images were preprocessed and trained with transfer learning pre-trained models by fine-tuning the hyper-parameter of the selected models. Results: The overall best training accuracy of the models become 95.3%, 97.1%, 89.8%, and 89.9% on EffecientNetB0, MobileNetv2, ResNet50, VGG16 respectively. In addition to this, the best validation accuracy of the models was 94.7%, 91.8%, 87.8%, and 86.7% respectively. The best testing accuracy of the models at the same epoch was 95.2%, 91.5%, 87%, and 85.5% respectively. From these models, EfficientNetB0 showed the best average training and testing accuracy than the other models. Conclusions: The system assists the pathologist during the margin assessment of SCC by decreasing the diagnosis time from an average of 25 minutes to less than a minute.

30 March 2022 in Diagnostics
Verified
Journal Article
Open access
PDF file
Gelan AyanaGelan Ayana
Gelan Ayana
kokeb Desekokeb Dese
kokeb Dese
HRHakkins Raj
Hakkins Raj
JKJanarthanan Krishnamoorthy
Janarthanan Krishnamoorthy
TKTimothy Kwa
Timothy Kwa
The ultrasonic technique is an indispensable imaging modality for diagnosis of breast cancer in young women due to its ability in efficiently capturing the tissue properties, and decreasing nega-tive recognition rate thereby avoiding non-essential biopsies. Despite the advantages, ultrasound images are affected by speckle noise, generating fine-false structures that decrease the contrast of the images and diminish the actual boundaries of tissues on ultrasound image. Moreover, speckle noise negatively impacts the subsequent stages in image processing pipeline, such as edge detec-tion, segmentation, feature extraction, and classification. Previous studies have formulated vari-ous speckle reduction methods in ultrasound images; however, these methods suffer from being unable to retain finer edge details and require more processing time. In this study, we propose a breast ultrasound de-speckling method based on rotational invariant block matching non-local means (RIBM-NLM) filtering. The effectiveness of our method has been demonstrated by com-paring our results with three established de-speckling techniques, the switching bilateral filter (SBF), the non-local means filter (NLMF), and the optimized non-local means filter (ONLMF) on 250 images from public dataset and 6 images from private dataset. Evaluation metrics, including Self-Similarity Index Measure (SSIM), Peak Signal to Noise Ratio (PSNR), and Mean Square Error (MSE) were utilized to measure performance. With the proposed method, we were able to record average SSIM of 0.8915, PSNR of 65.97, MSE of 0.014, RMSE of 0.119, and computational speed of 82 seconds at noise variance of 20dB using the public dataset, all with p-value of less than 0.001 compared against NLMF, ONLMF, and SBF. Similarly, the proposed method achieved av-erage SSIM of 0.83, PSNR of 66.26, MSE of 0.015, RMSE of 0.124, and computational speed of 83 seconds at noise variance of 20dB using the private dataset, all with p-value of less than 0.001 compared against NLMF, ONLMF, and SBF.

29 April 2023 in Sensors
Verified
Journal Article
Open access
PDF file
Bulcha Belay EtanaBulcha Belay Etana
Bulcha Belay Etana
BMBenny Malengier
Benny Malengier
TKTimothy Kwa
Timothy Kwa
JKJanarthanan Krishnamoorthy
Janarthanan Krishnamoorthy
Lieva Van langenhoveLieva Van langenhove
Lieva Van langenhove
Recently, there has been an increase in the number of reports on textile-based dry electrodes that can detect biopotentials without the need for electrolytic gels. However, these textile electrodes have a higher electrode skin interface impedance due to the improper contact between the skin and the electrode, diminishing the reliability and repeatability of the sensor. To facilitate improved skin–electrode contact, the effects of load and holding contact pressure were monitored for an embroidered textile electrode composed of multifilament hybrid thread for its application as a surface electromyography (sEMG) sensor. The effect of the textile’s inter-electrode distance and double layering of embroidery that increases the density of the conductive threads were studied. Electrodes embroidered onto an elastic strap were wrapped around the forearm with a hook and loop fastener and tested for their performance. Time domain features such as the Root Mean Square (RMS), Average Rectified Value (ARV), and Signal to Noise Ratio (SNR) were quantitatively monitored in relation to the contact pressure and load. Experiments were performed in triplicates, and the sEMG signal characteristics were observed for various loads (0, 2, 4, and 6 kg) and holding contact pressures (5, 10, and 20 mmHg). sEMG signals recorded with textile electrodes were comparable in amplitude to those recorded using typical Ag/AgCl electrodes (28.45 dB recorded), while the signal-to-noise ratios were, 11.77, 19.60, 19.91, and 20.93 dB for the different loads, and 21.33, 23.34, and 17.45 dB for different holding pressures. The signal quality increased as the elastic strap was tightened further, but a pressure higher than 20 mmHg is not recommended because of the discomfort experienced by the subjects during data collection.

5 February 2018 in bioRxiv
Verified
Preprint
Open access
PDF file
GPGanesh Kumar Paul
Ganesh Kumar Paul
PAPrashanth Alluvada
Prashanth Alluvada
EAEsayas Alemayehu
Esayas Alemayehu
MHM.S. Shahul Hameed
M.S. Shahul Hameed
WAWasihun Alemayehu
Wasihun Alemayehu
JKJanarthanan Krishnamoorthy
Janarthanan Krishnamoorthy
Log D is one of the important parameters used in Lipinski’s rule to assess the druggability of a molecule in pharmaceutical formulations. It represents the logarithm ( log 10 ) of the distribution coefficient ( D ) of a molecule. The distribution coefficient is defined as the ratio of the concentration of the sum of ionized and unionized species of a molecule distributed between a hydrophobic organic phase and an aqueous buffer phase. Since the pH affects the ionic state of a molecule, log D value (which is dependent on the concentrations of the ionized species) also becomes dependent on pH. In this work, the conventional algebraic method is compared with a more generalized ‘dynamic’ approach to model the distribution coefficient of amphoteric, diamino-monoprotic molecule and monoprotic acid in the presence of salt or co-solvent. Recently reported experimental log D data of amphoteric molecules such as nalidixic acid, mebendazole, benazepril and telmisartan, were analyzed using both these approaches to show their equivalence. GRAPHICAL