7 results on '"Raghu Gowda"'
Search Results
2. Effects of Particle Surface Charge, Species, Concentration, and Dispersion Method on the Thermal Conductivity of Nanofluids
- Author
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Raghu Gowda, Hongwei Sun, Pengtao Wang, Majid Charmchi, Fan Gao, Zhiyong Gu, and Bridgette Budhlall
- Subjects
Mechanical engineering and machinery ,TJ1-1570 - Abstract
The purpose of this experimental study is to evaluate the effects of particle species, surface charge, concentration, preparation technique, and base fluid on thermal transport capability of nanoparticle suspensions (nanofluids). The surface charge was varied by changing the pH value of the fluids. The alumina ( Al 2 O 3 ) and copper oxide (CuO) nanoparticles were dispersed in deionized (DI) water and ethylene glycol (EG), respectively. The nanofluids were prepared using both bath-type and probe sonicator under different power inputs. The experimental results were compared with the available experimental data as well as the predicted values obtained from Maxwell effective medium theory. It was found that ethylene glycol is more suitable for nanofluids applications than DI water in terms of thermal conductivity improvement and stability of nanofluids. Surface charge can effectively improve the dispersion of nanoparticles by reducing the (aggregated) particle size in base fluids. A nanofluid with high surface charge (low pH) has a higher thermal conductivity for a similar particle concentration. The sonication also has a significant impact on thermal conductivity enhancement. All these results suggest that the key to the improvement of thermal conductivity of nanofluids is a uniform and stable dispersion of nanoscale particles in a fluid.
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- 2010
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3. Stereotactic body radiation therapy for early hepatocellular carcinoma: a retrospective analysis of the South Australian experience
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Mohamed A. Chinnaratha, Raghu Gowda, Edmund Tse, John W. Chen, Alan Wigg, Ivan Iankov, Sumudu K. Narayana, and Hien Le
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Male ,medicine.medical_specialty ,Carcinoma, Hepatocellular ,Percutaneous ,medicine.medical_treatment ,Stereotactic radiation therapy ,Radiosurgery ,law.invention ,03 medical and health sciences ,0302 clinical medicine ,Randomized controlled trial ,law ,South Australia ,Humans ,Medicine ,Early Hepatocellular Carcinoma ,Aged ,Retrospective Studies ,business.industry ,Liver Neoplasms ,Common Terminology Criteria for Adverse Events ,General Medicine ,Middle Aged ,medicine.disease ,Tumor Burden ,Treatment Outcome ,030220 oncology & carcinogenesis ,Hepatocellular carcinoma ,Toxicity ,Female ,030211 gastroenterology & hepatology ,Surgery ,Liver function ,Radiology ,business - Abstract
Background Stereotactic body radiation therapy (SBRT) is an emerging treatment option for liver tumours unsuitable for established curative treatment such as ablation or surgery. The aim of the study is to evaluate the efficacy and safety of SBRT in the treatment of small hepatocellular carcinoma (HCC) in South Australia. Methods From 2014 to 2018, 13 HCC patients were treated with SBRT. Eligibility criteria for SBRT included: unsuitable for standard curative therapies (resection or percutaneous ablation), lack of complete response to prior transarterial chemoembolization, Child-Pugh classification ≤B7, tumours ≤5 cm and minimum of up to 6 months follow-up post-SBRT. The prescribed radiation dose was determined by liver function with doses ranging from 40 to 45 Gy in three or five fractions. Records for all patients were reviewed, and treatment response was scored according to the modified response evaluation criteria in solid tumours. Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 4.0. Results The median follow-up time was 22.7 months, and the median tumour size was 40 mm. The 1 year local control was 92.3%, recurrence-free survival was 67.7% and overall survival was 86.4% at end of study. Three patients underwent liver transplant. No grade ≥3 non-haematological toxicities were observed. One patient experienced acute grade ≥3 haematological toxicity. Conclusion SBRT is a safe, effective and non-invasive alternative treatment option for patients with small HCCs, unsuitable for standard, evidence-based therapies and lacking complete response to transarterial chemoembolization. Randomized controlled trials are required to further investigate the role of SBRT in HCC.
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- 2019
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4. Quality indicators and technique for analyzing permanent I-125 prostate seed implants: Seven years postimplant dosimetry evaluation
- Author
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Raghu Gowda, Loredana G. Marcu, Thomas P. Rutten, and John M. Lawson
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Contouring ,Dose-volume histogram ,medicine.medical_specialty ,Urinary retention ,business.industry ,medicine.medical_treatment ,Brachytherapy ,PID controller ,General Medicine ,Low-Dose Rate Brachytherapy ,Medical imaging ,medicine ,Dosimetry ,Radiology ,medicine.symptom ,Nuclear medicine ,business - Abstract
Purpose: The roles of postimplant dosimetry (PID) after permanent I-125 implant are to identify and rectify inadequate implants, assess the dosimetric quality indicators, and evaluate dose to the organs at risk. The aim of the current work was to assess the progress of prostate implant quality via postimplant dosimetry over seven years. Methods : The following factors were investigated to assess the PID results obtained over seven years: the improvement in implant technique, the computed tomography(CT) delineation-based PID versus ultrasound-CT (US-CT) fusion-based PID, and the evolution of parameters such as D90 and NDR (natural dose ratio). The correlation between dosimetric parameters and clinical outcomes were also evaluated. Results : The seven years PID learning curve shows clear changes in dosimetric trend for the 265 patients studied. Manual target contouring on CT was shown to overestimate the prostate volume when compared to ultrasound data, translating to CT-based D90 values being lower than US-CT D90. It was found that NDR does not contribute with additional dosimetric information to postimplant dosimetry evaluation. Patient follow-up data show that 4.7% patients have relapsed, and urinary retention was reported in 2.7% of the patients. Conclusions : CT-based PID was found less reliable than US-CT fusion-based PID due to target volume overestimation. This result shows the biased interpretation of low D90 values based on CT-based targeting, providing unreliable correlations between D90 and relapse probability. The low urinary retention statistics are in accordance with the PID data for the organ, as only 5.2% of patients had their PID D10 > 218 Gy, i.e., above the recommended GEC-ESTRO guidelines. Besides the “learning” component, the PID D90 curve is influenced by the PID technique.
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- 2012
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5. Quality indicators and technique for analyzing permanent I-125 prostate seed implants: seven years postimplant dosimetry evaluation
- Author
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Loredana G, Marcu, John M, Lawson, Thomas, Rutten, and Raghu, Gowda
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Adult ,Male ,Brachytherapy ,Humans ,Prostatic Neoplasms ,Reproducibility of Results ,Radiotherapy Dosage ,Longitudinal Studies ,Middle Aged ,Radiometry ,Sensitivity and Specificity ,United States ,Quality Indicators, Health Care - Abstract
The roles of postimplant dosimetry (PID) after permanent I-125 implant are to identify and rectify inadequate implants, assess the dosimetric quality indicators, and evaluate dose to the organs at risk. The aim of the current work was to assess the progress of prostate implant quality via postimplant dosimetry over seven years.The following factors were investigated to assess the PID results obtained over seven years: the improvement in implant technique, the computed tomography (CT) delineation-based PID versus ultrasound-CT (US-CT) fusion-based PID, and the evolution of parameters such as D90 and NDR (natural dose ratio). The correlation between dosimetric parameters and clinical outcomes were also evaluated.The seven years PID learning curve shows clear changes in dosimetric trend for the 265 patients studied. Manual target contouring on CT was shown to overestimate the prostate volume when compared to ultrasound data, translating to CT-based D90 values being lower than US-CT D90. It was found that NDR does not contribute with additional dosimetric information to postimplant dosimetry evaluation. Patient follow-up data show that 4.7% patients have relapsed, and urinary retention was reported in 2.7% of the patients.CT-based PID was found less reliable than US-CT fusion-based PID due to target volume overestimation. This result shows the biased interpretation of low D90 values based on CT-based targeting, providing unreliable correlations between D90 and relapse probability. The low urinary retention statistics are in accordance with the PID data for the organ, as only 5.2% of patients had their PID D10218 Gy, i.e., above the recommended GEC-ESTRO guidelines. Besides the "learning" component, the PID D90 curve is influenced by the PID technique.
- Published
- 2012
6. Varicella Zoster Vasculopathy
- Author
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Raghu Gowda Hanumaiah, Jyotsna Mareedu, Eyassu Habte-Gabr, and Elizabeth Hale
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Herpesvirus 3, Human ,medicine.medical_specialty ,Immunology ,Acyclovir ,Dermatology ,medicine.disease_cause ,Herpes Zoster ,Histoplasmosis ,Dysarthria ,Chickenpox ,Internal medicine ,Occlusion ,medicine ,Humans ,Stroke ,Palsy ,business.industry ,Varicella zoster virus ,medicine.disease ,Magnetic Resonance Imaging ,Stenosis ,Infectious Diseases ,Cardiology ,medicine.symptom ,Vasculitis ,business - Abstract
Varicella-zoster virus can cause neurological disease in primary and reactivated latent forms, with a wide spectrum of disorders throughout a person’s lifetime. 35-year-old male with AIDS; histoplasmosis; mild, intermittent asthma; and hypertension presented to hospital with left-sided weakness and slurred speech. Exam showed left hemiparesis with left upper motor neurons facial palsy and dysarthria. Acute right basal ganglia infarct was detected in head CT without contrast. A subsequent MRI showed acute non-hemorrhagic infarct, right basal ganglia; fusiform dilatation, and proximal right middle cerebral artery. A CT angiogram of the bilateral carotid arteries revealed occlusion of the right anterior cerebral artery with conical dilatation at the origin; significant stenosis, and dilatation of the right middle cerebral artery. These findings were consistent with vasculitis. Patient was successfully treated with IV acyclovir. Rapid diagnosis of VZV vasculopathy is important because it is a treatable cause of stroke. Mortality rate is 25% without treatment.
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- 2011
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7. Varicella Zoster Vasculopathy.
- Author
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Mareedu, Jyotsna, Hanumaiah, Raghu Gowda, Hale, Elizabeth, and Habte-Gabr, Eyassu
- Abstract
Varicella-zoster virus can cause neurological disease in primary and reactivated latent forms, with a wide spectrum of disorders throughout a person’s lifetime. 35-year-old male with AIDS; histoplasmosis; mild, intermittent asthma; and hypertension presented to hospital with left-sided weakness and slurred speech. Exam showed left hemiparesis with left upper motor neurons facial palsy and dysarthria. Acute right basal ganglia infarct was detected in head CT without contrast. A subsequent MRI showed acute non-hemorrhagic infarct, right basal ganglia; fusiform dilatation, and proximal right middle cerebral artery. A CT angiogram of the bilateral carotid arteries revealed occlusion of the right anterior cerebral artery with conical dilatation at the origin; significant stenosis, and dilatation of the right middle cerebral artery. These findings were consistent with vasculitis. Patient was successfully treated with IV acyclovir. Rapid diagnosis of VZV vasculopathy is important because it is a treatable cause of stroke. Mortality rate is 25% without treatment. [ABSTRACT FROM PUBLISHER]
- Published
- 2011
- Full Text
- View/download PDF
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