129 results on '"M. H. Nguyen"'
Search Results
2. Joint Self-Supervised Image-Volume Representation Learning with Intra-inter Contrastive Clustering.
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Duy M. H. Nguyen, Hoang Nguyen, Truong Thanh Nhat Mai, Tri Cao, Binh T. Nguyen 0001, Nhat Ho, Paul Swoboda, Shadi Albarqouni, Pengtao Xie, and Daniel Sonntag
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- 2023
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3. Recycling of Waste Oyster Shells for the Treatment of Acidified Water toward Stabilization of Aquaculture Environment
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Hoan T. Phan, Kiet Q. Dinh, Sinh H. Nguyen, Yen M. H. Nguyen, Khoa D. Nguyen, Ha V. Le, and Nam H. Nguyen
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Chemical engineering ,TP155-156 ,Computer engineering. Computer hardware ,TK7885-7895 - Abstract
Oyster shells are one of the most abundant seafood wastes in Vietnam which have not been deposed efficiently, causing many negative effects on the ecosystem and the quality of human life. In this study, the recycling of waste oyster shells was investigated to provide a calcium carbonate-rich material for improving and stabilizing the pH value of acidified water. Characterization of the recycled shells using various techniques proved that the thermal treatments at temperatures from 120 to 220 °C led to no significant changes in the chemical composition and calcite-based layer structure of oyster shells. Testing the performance of the recycled oyster shells in the adjustment of the aqueous pH value was conducted in a solution containing NH4Cl (0.5 g/L) as a simulation of the acidified aquaculture phase. As expected, using 1 g of the 220 °C -calcinated oyster shell for 2 L of the simulated solution, the solution pH rapidly increased from 6.3 to 7.7 in the first 2 h, reached the extreme value (~ 7.8) after 24 h and slowly decreased to the stabilized pH range of ~ 7.2 after 5-6 d. It was proved out that the oyster shell amount significantly affected the solution pH value. Importantly, the elemental analysis showed that the content of toxic transition metals including Cd, Pb, As, and Cr in the oyster shell was below the detection limit of each other, implying great potential for the application in the real aquaculture environment in Vietnam.
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- 2023
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4. LMGP: Lifted Multicut Meets Geometry Projections for Multi-Camera Multi-Object Tracking.
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Duy M. H. Nguyen, Roberto Henschel, Bodo Rosenhahn, Daniel Sonntag, and Paul Swoboda
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- 2022
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5. Gaussian Process-based Amortization of Variational Message Passing Update Rules.
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Hoang M. H. Nguyen, Semih Akbayrak, Magnus T. Koudahl, and Bert de Vries
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- 2022
6. Efficient Model Evidence Computation in Tree-structured Factor Graphs.
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Hoang M. H. Nguyen, Bart van Erp, Ismail Senöz, and Bert de Vries
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- 2022
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7. LVM-Med: Learning Large-Scale Self-Supervised Vision Models for Medical Imaging via Second-order Graph Matching.
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Duy M. H. Nguyen, Hoang Nguyen, Nghiem Tuong Diep, Tan Ngoc Pham, Tri Cao, Binh T. Nguyen 0001, Paul Swoboda, Nhat Ho, Shadi Albarqouni, Pengtao Xie, Daniel Sonntag, and Mathias Niepert
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- 2023
8. Self-supervised Domain Adaptation for Diabetic Retinopathy Grading Using Vessel Image Reconstruction.
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Duy M. H. Nguyen, Truong Thanh Nhat Mai, Ngoc T. T. Than, Alexander Prange, and Daniel Sonntag
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- 2021
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9. Automatically Generate Hymns Using Variational Attention Models.
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Han K. Cao, Duyen T. Ly, Duy M. H. Nguyen, and Binh T. Nguyen 0001
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- 2019
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10. Project AutoVision: Localization and 3D Scene Perception for an Autonomous Vehicle with a Multi-Camera System.
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Lionel Heng, Benjamin Choi, Zhaopeng Cui, Marcel Geppert, Sixing Hu, Benson Kuan, Peidong Liu, Rang M. H. Nguyen, Ye Chuan Yeo, Andreas Geiger 0001, Gim Hee Lee, Marc Pollefeys, and Torsten Sattler
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- 2019
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11. OASIS: An Active Framework for Set Inversion.
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Binh T. Nguyen 0001, Duy M. H. Nguyen, Lam Si Tung Ho, and Vu C. Dinh
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- 2018
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12. CVM-Net: Cross-View Matching Network for Image-Based Ground-to-Aerial Geo-Localization.
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Sixing Hu, Mengdan Feng, Rang M. H. Nguyen, and Gim Hee Lee
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- 2018
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13. 3D-Brain Segmentation Using Deep Neural Network and Gaussian Mixture Model.
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Duy M. H. Nguyen, Huy T. Vu, Quang Huy Ung, and Binh T. Nguyen 0001
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- 2017
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14. CO2 partial pressure and CO2 emission along the lower Red River (Vietnam)
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T. P. Q. Le, C. Marchand, C. T. Ho, N. D. Le, T. T. Duong, X. Lu, P. K. Doan, T. K. Nguyen, T. M. H. Nguyen, and D. A. Vu
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Ecology ,QH540-549.5 ,Life ,QH501-531 ,Geology ,QE1-996.5 - Abstract
The Red River (Vietnam) is representative of a south-east Asian river system, strongly affected by climate and human activities. This study aims to quantify the spatial and seasonal variability of CO2 partial pressure and CO2 emissions of the lower Red River system. Water quality monitoring and riverine pCO2 measurements were carried out for 24 h at five stations distributed along the lower Red River system during the dry and the wet seasons. The riverine pCO2 was supersaturated relative to the atmospheric equilibrium (400 ppm), averaging about 1589±43 ppm and resulting in a water–air CO2 flux of 530.3±16.9 mmol m−2 d−1 for the lower Red River. pCO2 and CO2 outgassing rates were characterized by significant spatial variation along this system, with the highest values measured at Hoa Binh station, located downstream of the Hoa Binh Dam, on the Da River. Seasonal pCO2 and CO2 outgassing rate variations were also observed, with higher values measured during the wet season at almost all sites. The higher river discharges, enhanced external inputs of organic matter from watersheds and direct inputs of CO2 from soils or wetland were responsible for higher pCO2 and CO2 outgassing rates. The difference in pCO2 between the daytime and the night-time was not significant, suggesting weak photosynthesis processes in the water column of the Red River due to its high sediment load.
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- 2018
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15. Fast learning rates with heavy-tailed losses.
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Vu C. Dinh, Lam Si Tung Ho, Binh T. Nguyen 0001, and Duy M. H. Nguyen
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- 2016
16. Learning from Non-iid Data: Fast Rates for the One-vs-All Multiclass Plug-in Classifiers.
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Vu C. Dinh, Lam Si Tung Ho, Viet Cuong Nguyen, Duy M. H. Nguyen, and Binh T. Nguyen 0001
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- 2015
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17. Hypolipidaemic Effects of (24R)-4α-methyl-5α-stigmasta-7,22-dien-3β-ol Derived from Aurantiochytrium mangrovei BT3 in the HEPG2 Cell Line
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T. M. H. Hoang, T. T. Luu, T. H. T. Ngo, T. M. H. Nguyen, H. G. Tran, T. T. O. Nguyen, V. M. Chau, and Dang Diem Hong
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Applied Microbiology and Biotechnology ,Biochemistry - Published
- 2022
18. Changing incidence of reported viral hepatitis in China from 2004 to 2016: an observational study
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Yanhang Gao, Ruihong Wu, Mingyuan Zhang, Hongqin Xu, Julia Uhanova, Robert Gish, Xiaoyu Wen, Qinglong Jin, Minuk Y Gerald, M H Nguyen, and J Niu
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Medicine - Abstract
Objective China’s national hepatitis burden is high. This study aims to provide a detailed national-level description of the reported incidence of viral hepatitis in China during 2004–2016.Design Observational study.Setting Data were obtained from China’s National Notifiable Disease Reporting System, and changing trends were estimated by joinpoint regression analysis.Participants In this system, 16 927 233 reported viral hepatitis cases occurring during 2004–2016 were identified.Primary outcome measure Incidence rates per 100 000 person-years and changing trends were calculated.Results There were 16 927 233 new cases of viral hepatitis reported in China from 2004 to 2016. Hepatitis B (HBV) (n=13 543 137, 80.00%) and hepatitis C (HCV) (n=1 844 882, 10.90%) accounted for >90% of the cases. The overall annual percent change (APC) in reported cases of viral hepatitis and HBV were 0.3%(95% CI −2.0 to 0.8, p=0.6) and −0.2% (95% CI −1.6 to 1.2, p=0.8), respectively, showing a stable trend. HBV rates were highest in the 20–29 year old age group and lowest in younger individuals, likely resulting from the universal HBV vaccination. The reported incidence of HCV and hepatitis E (HEV) showed increasing trends; the APCs were 14.5% (95% CI 13.1 to 15.9, p
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- 2019
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19. Competence of healthcare professionals in diagnosing and managing obstetric complications and conducting neonatal care: a clinical vignette-based assessment in district and subdistrict hospitals in northern Bangladesh
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Ruihong Wu, Mingyuan Zhang, Hongqin Xu, Julia Uhanova, Robert Gish, Xiaoyu Wen, Qinglong Jin, Minuk Y Gerald, M H Nguyen, and J Niu
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Medicine - Abstract
BackgroundThis study assesses the competency of maternal and neonatal health (MNH) professionals at district-level and subdistrict-level health facilities in northern Bangladesh in managing maternal and newborn complications using clinical vignettes. The study also examines whether the professional’s characteristics and provision of MNH services in health facilities influence their competencies.Methods134 MNH professionals in 15 government hospitals were interviewed during August and September 2016 using structured questionnaire with clinical vignettes on obstetric complications (antepartum haemorrhage and pre-eclampsia) and neonatal care (low birthweight and immediate newborn care). Summative scores were calculated for each vignette and median scores were compared across different individual-level and health facility-level attributes to examine their association with competency score. Kruskal-Wallis test was performed to identify the significance of association considering a p value75% of total) in maternal and neonatal vignettes, respectively. Medical doctors had higher competency than nurses and midwives (score=11 vs 8 out of 19, respectively; p=0.0002) for maternal vignettes, but similar competency for neonatal vignettes (score=30.3 vs 30.9 out of 50, respectively). Professionals working in health facilities with higher use of normal deliveries had better competency than their counterparts. Professionals had higher competency in newborn vignettes (significant) and maternal vignettes (statistically not significant) if they worked in health facilities that provided more specialised newborn care services and emergency obstetric care, respectively, in the last 6 months.ConclusionsDespite the overall low competency of MNH professionals, exposure to a higher number of obstetric cases at the workplace was associated with their competency. Arrangement of periodic skill-based and drill-based in-service training for MNH professionals in high-use neighbouring health facilities could be a feasible intervention to improve their knowledge and skill in obstetric and neonatal care.
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- 2019
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20. Late-Stage C–H Functionalization of Azines
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Celena M. Josephitis, Hillary M. H. Nguyen, and Andrew McNally
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General Chemistry - Published
- 2023
21. Blind Signature Protocol Based on Hidden Discrete Logarithm Problem Set in a Commutative Algebra
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M. H. Nguyen, D. N. Moldovyan, N. A. Moldovyan, M. Q. Le, and G. L. Nguyen
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General Mathematics ,General Physics and Astronomy ,General Earth and Planetary Sciences ,General Chemistry ,General Agricultural and Biological Sciences - Published
- 2022
22. Associations between lean mass and leptin in men with chronic spinal cord injury: Results from the FRASCI-muscle study.
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Andrew J Park, Ricardo A Battaglino, Nguyen M H Nguyen, and Leslie R Morse
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Medicine ,Science - Abstract
Leptin is an adipo-myokine that regulates appetite and energy expenditure by a neuroendocrine feedback loop. Leptin levels are positively correlated with BMI in the spinal cord injury population and leptin levels are greater in individuals with spinal cord injury compared to uninjured controls. Leptin is produced in multiple tissues, including fat, bone, and skeletal muscle and is a putative biomarker of sedentary behavior in older adults. We assessed body composition leptin, adiponectin, and IL-6 levels in 205 men with chronic spinal cord injury. We found no association between age, injury duration, injury level, injury completeness, or walking status and leptin. There was a significant positive association between lean mass and leptin in men with SCI that was independent of fat. Adjusting for body composition, leptin levels were positively associated with IL-6 and negatively associated with adiponectin levels. When considering men with SCI and sarcopenic obesity, only fat mass remained positively associated with leptin. We found no association between IL-6, adiponectin, or lean mass and leptin in the sarcopenic obesity group. Our findings suggest that lean mass is an under recognized, but substantial, source of circulating leptin. Furthermore, SCI-related sarcopenic obesity may result in dysregulated adipo-myokine metabolism with local and systemic physiologic effects.
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- 2018
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23. 603 CHALLENGES IN THE MANAGEMENT OF SEVERE ORTHOSTATIC HYPOTENSION ASSOCIATED WITH SUPINE HYPERTENSION IN A PATIENT WITH AUTONOMIC DYSFUNCTION ON BACKGROUND OF NASOPHARYNGEAL CARCINOMA AND TYPE II DIABETES MELLITUS
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Q M N Rachel, M H Nguyen, and Kaysar Mamun
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Aging ,medicine.medical_specialty ,Supine hypertension ,business.industry ,General Medicine ,medicine.disease ,Type ii diabetes ,Orthostatic vital signs ,Nasopharyngeal carcinoma ,Internal medicine ,medicine ,Cardiology ,Geriatrics and Gerontology ,business - Abstract
Introduction Combined chemotherapy and radiotherapy increases long term survival in patients with nasopharyngeal carcinoma. However, radiotherapy of the carotid sinus or brain stem can evolve labile hypertension and orthostatic intolerance from chronic baroreflex failure. Diabetes would also cause this neuropathy. Management of patients with Supine hypertension-Orthostatic hypotension can be very challenging. Methods A case report was done on a 71-year-old man with metastatic nasopharyngeal carcinoma status post radiation therapy who was admitted with severe supine hypertension-orthostatic hypotension. Patient was managed with both non-pharmacological and pharmacological methods, and monitored for postural symptoms, complications of severe supine hypertension—which has been linked to left ventricular hypertrophy and kidney dysfunction, and placed on 24 hour ambulatory blood pressure monitoring to aid in management so as to prevent hypertension induced organ damage. Results This review outlines the pathophysiology of Supine hypertension-Orthostatic hypotension, treatment complications and potential management strategies recommendations for this group of patients. It revealed the benefit of having a 24 hour ambulatory blood pressure monitoring, which provides insight on the timing and magnitude of an individual’s blood pressure fluctuations throughout the day so as to further guide management. Conclusion Chronic baroreflex failure is a late sequela of neck irradiation for naso-pharyngeal carcinoma due to accelerated atherosclerosis in the region of the carotid sinus baroreceptor. Treatment goal is achieved with adequate control of pre-syncopal symptoms and prevention of long term complications. Non-pharmacological interventions remain the first line of therapy, followed by pharmacological interventions as necessary. Nonetheless, management of blood pressure in these elderly patients with baroreflex dysfunction remains challenging and should be individualized. Moving forward, a prospective study on the incidence of late onset, iatrogenic baroreflex failure as a late complication of neck irradiation and its particular relationship to carotid arterial rigidity should be conducted to increase awareness, timely diagnosis and management of the condition among physicians.
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- 2021
24. Structural Characterization of the D179N and D179Y Variants of KPC-2 β-Lactamase: Ω-Loop Destabilization as a Mechanism of Resistance to Ceftazidime-Avibactam
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T. A. Alsenani, S. L. Viviani, V. Kumar, M. A. Taracila, C. R. Bethel, M. D. Barnes, K. M. Papp-Wallace, R. K. Shields, M. H. Nguyen, C. J. Clancy, R. A. Bonomo, and F. van den Akker
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Pharmacology ,Meropenem ,Microbial Sensitivity Tests ,biochemical phenomena, metabolism, and nutrition ,bacterial infections and mycoses ,Ceftazidime ,beta-Lactamases ,Anti-Bacterial Agents ,Drug Combinations ,Klebsiella pneumoniae ,Infectious Diseases ,Bacterial Proteins ,Mechanisms of Resistance ,polycyclic compounds ,Pharmacology (medical) ,beta-Lactamase Inhibitors ,Azabicyclo Compounds - Abstract
Klebsiella pneumoniae carbapenemases (KPC-2 and KPC-3) present a global clinical threat, as these β-lactamases confer resistance to carbapenems and oxyimino-cephalosporins. Recent clinically identified KPC variants with substitutions at Ambler position D179, located in the Ω loop, are resistant to the β-lactam/β-lactamase inhibitor combination ceftazidime-avibactam, but susceptible to meropenem-vaborbactam. To gain insights into ceftazidime-avibactam resistance conferred by D179N/Y variants of KPC-2, crystal structures of these variants were determined. The D179N KPC-2 structure revealed that the change of the carboxyl to an amide moiety at position 179 disrupted the salt bridge with R164 present in wild-type KPC-2. Additional interactions were disrupted in the Ω loop, causing a decrease in the melting temperature. Shifts originating from N179 were also transmitted toward the active site, including ∼1-Å shifts of the deacylation water and interacting residue N170. The structure of the D179Y KPC-2 β-lactamase revealed more drastic changes, as this variant exhibited disorder of the Ω loop, with other flanking regions also being disordered. We postulate that the KPC-2 variants can accommodate ceftazidime because the Ω loop is displaced in D179Y or can be more readily displaced in D179N KPC-2. To understand why the β-lactamase inhibitor vaborbactam is less affected by the D179 variants than avibactam, we determined the crystal structure of D179N KPC-2 in complex with vaborbactam, which revealed wild-type KPC-2-like vaborbactam-active site interactions. Overall, the structural results regarding KPC-2 D179 variants revealed various degrees of destabilization of the Ω loop that contribute to ceftazidime-avibactam resistance, possible substrate-assisted catalysis of ceftazidime, and meropenem and meropenem-vaborbactam susceptibility.
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- 2022
25. Multicenter Registry of Patients Receiving Systemic Mold-Active Triazoles for the Management of Invasive Fungal Infections
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L. Ostrosky-Zeichner, M. H. Nguyen, J. Bubalo, B. D. Alexander, M. H. Miceli, P. G. Pappas, J. Jiang, Y. Song, and G. R. Thompson
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Microbiology (medical) ,Isavuconazole ,Prevention ,Clinical Trials and Supportive Activities ,Clinical Sciences ,Immunology ,Mold infection ,Pharmacology and Pharmaceutical Sciences ,Infectious Diseases ,Emerging Infectious Diseases ,Real-world ,Invasive fungal infections ,Clinical Research ,Prospective observational study ,Antifungal treatment ,Triazole ,Voriconazole ,Posaconazole ,Disease registry ,Infection - Abstract
Introduction'Real-world' data for mold-active triazoles (MATs) in the treatment of invasive fungal infections (IFIs) are lacking. This study evaluated usage of MATs in a disease registry for the management of IFIs.MethodsData were collected for this multicenter, observational, prospective study from 55 US centers, between March 2017 and April 2020. Eligible patients received isavuconazole, posaconazole, or voriconazole as MAT monotherapy (one MAT) or multiple/sequenced MAT therapy (more than one MAT) for prophylaxis or treatment. Patients were enrolled within 60days of MAT initiation. The primary objective was to characterize patients receiving a MAT and their patterns of therapy. The full analysis set (FAS) included eligible patients for the relevant enrollment protocol, and the safety analysis set (SAF) included patients who received ≥ 1 MAT dose.ResultsOverall, 2009 patients were enrolled in the SAF. The FAS comprised 1993 patients (510 isavuconazole; 540 posaconazole; 491 voriconazole; 452 multiple/sequenced MAT therapies); 816 and 1177 received treatment and prophylaxis at study index/enrollment, respectively. Around half (57.8%) of patients were male, and median age was 59years. Among patients with IFIs during the study, the most common pathogens were Aspergillus fumigatus in the isavuconazole (18.2% [10/55]) and voriconazole (25.5% [12/47]) groups and Candida glabrata in the posaconazole group (20.9% [9/43]); the lungs were the most common infection site (58.2% [166/285]). Most patients were maintained on MAT monotherapy (77.3% [1541/1993]), and 79.4% (1520/1915) completed their MAT therapies. A complete/partial clinical response was reported in 59.1% (591/1001) of patients with a clinical response assessment. Breakthrough IFIs were reported in 7.1% (73/1030) of prophylaxis patients. Adverse drug reactions (ADRs) were reported in 14.7% (296/2009) of patients (3.9% [20/514] isavuconazole; 11.3% [62/547] posaconazole; 14.2% [70/494] voriconazole).ConclusionsIn this 'real-world' study, most patients remained on their initial therapy and completed their MAT therapy. Over half of patients receiving MATs for IFIs had a successful response, and most receiving prophylaxis did not develop breakthrough IFIs. ADRs were uncommon.
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- 2022
26. Kinetic Characteristics of the Process of Synthesis of Nickel Nanopowder by the Chemical Metallurgy Method
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H. V. Nguyen, X. D. Tang, M. H. Nguyen, V. M. Nguyen, V. N. Danchuk, and T. H. Nguyen
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Materials science ,Aqueous solution ,Hydrogen ,Nickel oxide ,Thermal decomposition ,Non-blocking I/O ,Metallurgy ,General Engineering ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Isothermal process ,0104 chemical sciences ,chemistry.chemical_compound ,Nickel ,chemistry ,Hydroxide ,General Materials Science ,0210 nano-technology - Abstract
The kinetic characteristics of the process of synthesis of Ni nanopowder (NP) by the chemical metallurgy method are studied. Nickel NP is obtained by reduction of NiO nanopowder with hydrogen in a tubular furnace at temperatures in the range from 240 to 280°C. Nickel oxide nanopowder is prepared by thermal decomposition of nickel hydroxide Ni(OH)2 at 300°C, which has been synthesized in advance by chemical precipitation from aqueous solutions of nickel nitrate 10 wt % and alkali NaOH 10 wt % with pH 9 at room temperature. It is found that NiO NP is more readily reduced at temperatures above 250°C. The rate constant of the reduction process at 280°C is about 2.5 times higher than in the case of reduction at 240°C. The duration of the reduction process at 280°C is shorter by a factor of more than two in comparison with the case of reduction at 240°C. Based on the results of calculation of the activation energy of the reduction process from isothermal data, an assumption is made about the kinetically controlled rate-limiting regime of the reduction of NiO NP. It is revealed that Ni nanoparticles obtained by hydrogen reduction of nickel oxide have an average size in the range of 60–120 nm, and each of them is connected to several adjacent particles by necks.
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- 2020
27. Antibiotic use during pregnancy and the risk of preterm birth : a population-based Swedish cohort study
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M H Nguyen, R Fornes, N Kamau, H Danielsson, S Callens, E Fransson, L Engstrand, R Bruyndonckx, N. Brusselaers, Brusselaers, Nele/0000-0003-0137-447X, NGUYEN, Minh Hanh, Fornes, R., KAMAU, Njeri, Danielsson, H., Callens, S., Fransson, E., Engstrand, L., BRUYNDONCKX, Robin, and Brusselaers, N.
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Sweden ,Pharmacology ,Microbiology (medical) ,Pharmacology. Therapy ,Infant, Newborn ,WOMEN ,Anti-Bacterial Agents ,Cohort Studies ,DELIVERY ,Infectious Diseases ,Pregnancy ,Pregnancy Trimester, Second ,BACTERIAL VAGINOSIS ,INFECTION ,Medicine and Health Sciences ,Humans ,Premature Birth ,EPIDEMIOLOGY ,Female ,Pharmacology (medical) ,Human medicine ,Biology - Abstract
Objectives To assess the impact of gestational antibiotics on the risk of preterm birth, since a healthy maternal microbiome may be protective. Methods Population-based cohort study including all first pregnancies in Sweden (2006–16). The association between gestational and recent pre-conception systemic antibiotics and preterm birth was assessed by multivariable logistic regression presented as ORs and 95% CIs, adjusted for comorbidities (hypo- and hyperthyroidism, hypertension, or diabetes mellitus pre-gestation), trimester, antibiotic class and treatment duration. Results Compared with non-users, antibiotic exposure was associated with increased risks of preterm birth in mothers with comorbidities (OR = 1.32, 95% CI 1.18–1.48) and without (OR = 1.09, 95% CI 1.06–1.13). Pre-conception use showed no association, while risk was increased for first and second trimester use and decreased for third trimester use. The increased risks were seen for the following antibiotic groups in mothers without and with comorbidities, respectively: macrolides, lincosamides and streptogramins (OR = 1.63, 95% CI 1.45–1.83; OR = 2.48, 95% CI 1.72–3.56); quinolones (OR = 1.60, 95% CI 1.32–1.94; OR = 2.11, 95% CI 1.12–4.03); non-penicillin β-lactams (OR = 1.15, 95% CI 1.07–1.24; OR = 1.39, 95% CI 1.07–1.83); other antibacterials (OR = 1.09, 95% CI 1.03–1.14; 1.38, 95% CI 1.16–1.63); and penicillins (OR = 1.04, 95% CI 1.01–1.08; 1.23, 95% CI 1.09–1.40). Antibiotic indications were not available, which could also affect preterm birth. Conclusions Antibiotic use during pregnancy was associated with an increased risk of preterm birth, especially in mothers with chronic diseases.
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- 2022
28. Multivariate phenomenological models for real-time short-term forecasts of hospital capacity for COVID-19 in Belgium from March to June 2020
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M. H. Nguyen, T. Braeye, N. Hens, C. Faes, NGUYEN, Minh Hanh, BRAEYE, Toon, HENS, Niel, and FAES, Christel
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0303 health sciences ,Original Paper ,Science & Technology ,Epidemiology ,COVID-19 ,3. Good health ,modelling ,03 medical and health sciences ,0302 clinical medicine ,Infectious Diseases ,statistics ,EPIDEMIC ,public health emerging infections ,030212 general & internal medicine ,Human medicine ,Life Sciences & Biomedicine ,030304 developmental biology ,Public, Environmental & Occupational Health - Abstract
Phenomenological models are popular for describing the epidemic curve. We present how they can be used at different phases in the epidemic, by modelling the daily number of new hospitalisations (or cases). As real-time prediction of the hospital capacity is important, a joint model of the new hospitalisations, number of patients in hospital and in intensive care unit (ICU) is proposed. This model allows estimation of the length of stay in hospital and ICU, even if no (or limited) individual level information on length of stay is available. Estimation is done in a Bayesian framework. In this framework, real-time alarms, defined as the probability of exceeding hospital capacity, can be easily derived. The methods are illustrated using data from the COVID-19 pandemic in March–June 2020 in Belgium, but are widely applicable.
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- 2021
29. Variational Bayes on manifolds
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Duy M. H. Nguyen, Dang H. Nguyen, and Minh-Ngoc Tran
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FOS: Computer and information sciences ,Statistics and Probability ,Wishart distribution ,Discrete mathematics ,Computer Science - Machine Learning ,Order (ring theory) ,Machine Learning (stat.ML) ,Parameter space ,Riemannian manifold ,Upper and lower bounds ,Manifold ,Machine Learning (cs.LG) ,Theoretical Computer Science ,Methodology (stat.ME) ,Computational Theory and Mathematics ,Statistics - Machine Learning ,Probability distribution ,Information geometry ,Statistics, Probability and Uncertainty ,Statistics - Methodology ,Mathematics - Abstract
Variational Bayes (VB) has become a widely-used tool for Bayesian inference in statistics and machine learning. Nonetheless, the development of the existing VB algorithms is so far generally restricted to the case where the variational parameter space is Euclidean, which hinders the potential broad application of VB methods. This paper extends the scope of VB to the case where the variational parameter space is a Riemannian manifold. We develop an efficient manifold-based VB algorithm that exploits both the geometric structure of the constraint parameter space and the information geometry of the manifold of VB approximating probability distributions. Our algorithm is provably convergent and achieves a convergence rate of order $\mathcal O(1/\sqrt{T})$ and $\mathcal O(1/T^{2-2\epsilon})$ for a non-convex evidence lower bound function and a strongly retraction-convex evidence lower bound function, respectively. We develop in particular two manifold VB algorithms, Manifold Gaussian VB and Manifold Neural Net VB, and demonstrate through numerical experiments that the proposed algorithms are stable, less sensitive to initialization and compares favourably to existing VB methods., Comment: 30 pages, 5 figures
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- 2021
30. A Study of Fluid-Structure Interaction of Unsteady Flow in the Blood Vessel Using Finite Element Method
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M. D. Nguyen, T. D. Nguyen, M. H. Nguyen, V. C. Vu, and S. T. Ha
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Physics::Fluid Dynamics ,Computer simulation ,Discretization ,Incompressible flow ,Computer science ,Quantitative Biology::Tissues and Organs ,Physics::Medical Physics ,Constitutive equation ,Fluid–structure interaction ,Tetrahedron ,Mechanics ,Kinematics ,Finite element method - Abstract
The paper presents a numerical simulation for fluid-structure interaction (FSI) of unsteady blood flow interacting with the vessel wall. The present work aims to provide a simple approach for very large deformation of the wall. The implementation of the method is straightforward and can be employed for a large scale problem with a cheap computational cost. The classical finite element discretization is adopted both for fluid and solid domains on tetrahedral elements. The monolithic scheme is used for the strong coupling of fluid and structure to satisfy kinematic and dynamic equilibrium conditions at the interface. The Navier-Stokes equations of an incompressible flow are solved by using the integrated method based on the Arbitrary Lagrangian-Eulerian (ALE) formula for the moving grid, and the total Lagrangian formulation is used for the non-linear hyper-elastic material of the vessel wall with the Mooney-Rivlin material model adopted as a constitutive equation for the solid domain. The numerical solutions for the FSI of blood vessel problem are quite similar to the experimental data. After validation the code, two problems of the blood vessel walls are considered: The carotid bifurcation and the aortic valve problems. The simulation results can be used for predicting the risk of cardiovascular diseases.
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- 2021
31. A Note on Categorification and Spherical Harmonics
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Oded Yacobi, Suntharan Arunasalam, Suo Jun Tan, Joshua Ciappara, and Diana M. H. Nguyen
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Weyl algebra ,Verma module ,General Mathematics ,Polynomial ring ,Categorification ,010102 general mathematics ,0211 other engineering and technologies ,Spherical harmonics ,021107 urban & regional planning ,02 engineering and technology ,01 natural sciences ,Action (physics) ,Combinatorics ,Matrix (mathematics) ,Simple (abstract algebra) ,Mathematics::Category Theory ,Mathematics::Quantum Algebra ,0101 mathematics ,Mathematics::Representation Theory ,Mathematics - Abstract
Using Khovanov’s categorification of the Weyl algebra, we investigate categorical structures arising from spherical harmonics. We categorify the $\mathfrak {s}\mathfrak {l}(2,\mathbb {C})$ -action on the polynomial ring in n variables, and use this to categorify certain simple Verma modules. On the way we also categorify the standard action of matrix units $E_{ij}\in \mathfrak {g}\mathfrak {l}(n,\mathbb {C})$ on the polynomial ring.
- Published
- 2019
32. Diagnostic values of different cytokines in identifying tuberculous pleural effusion
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M H, Nguyen, Q M, Dao, T T H, Bui, and V H T, Le
- Subjects
Adult ,Male ,Tumor Necrosis Factor-alpha ,Interleukin-1beta ,Tuberculosis, Pleural ,Middle Aged ,Sensitivity and Specificity ,Pleural Effusion ,Interferon-gamma ,Cross-Sectional Studies ,Vietnam ,Predictive Value of Tests ,Area Under Curve ,Cytokines ,Humans ,Interleukin-2 ,Female ,Biomarkers ,Aged - Abstract
Interleukin (IL)-1 beta (IL-1β), IL-2, Interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) in the pleural fluid are valuable biomarkers in early diagnosis of Tuberculous Pleural Effusion (TPE). This study aimed to analyze the diagnostic values of some cytokines (IFN-γ, TNF-α, IL-1β, and IL-2) in pleural fluid for identifying TPE in Vietnam. We performed a cross-sectional study on tuberculosis (TB) patients with pleural effusion. Pleural IFN-γ, TNF-α, IL-1β, IL-2 were measured by ELISA® Kit (Abcam, USA) on Biotek system. Receiver operating characteristic curves (ROC), an area under the curve (AUC), sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) and accuracy (ACC) of IFN-γ, TNF-α, IL-1β, IL-2 in identifying TBE were assessed. Among 386 patients, 234 (60,6%) had TPE, and 152 (39,4%) did not have TPE. The median of IL-2, TNF-α, and IFN-γ levels were significantly higher in TPE compared to the non-TPE group (p0.05). AUC for IL-1β, IL-2, TNF-α, and IFN-γ were 0.54, 0.57, 0.62. 0.84 (p0.05), respectively. The sensitivity of IL-1β, IL-2, TNF-α, and IFN-γ in the diagnosis of TPE were 82.1, 53.4, 77.8, and 80.3, while the specificity was 28,4, 69.7, 47.4, and 80.9, respectively. IFN-γ and TNF-α are potential biomarkers in diagnosing TPE.
- Published
- 2021
33. Learning Embedding for Knowledge Graph Completion with Hypernetwork
- Author
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Bac Le, Thanh Le, and Duy M. H. Nguyen
- Subjects
business.industry ,Computer science ,Deep learning ,Link (geometry) ,Machine learning ,computer.software_genre ,Convolutional neural network ,Task (project management) ,Embedding ,Graph (abstract data type) ,Artificial intelligence ,business ,Focus (optics) ,computer ,Strengths and weaknesses - Abstract
Link prediction in Knowledge Graph, also called knowledge completion, is a significant problem in graph mining and has many applications for large companies. The more accurate the link prediction results will bring satisfaction, reduce and avoid risks, and commercial benefits. Almost all state-of-the-art models focus on the deep learning approach, especially using convolutional neural networks (CNN). By analysing the strengths and weaknesses of the CNN based models, we proposed a better model to improve the performance of the link prediction task. Specifically, we apply a CNN with specific filters generated through the Hypernetwork architecture. Moreover, we increase the depth of the model more than baseline models to help learn more helpful information. Experimental results show that the proposed model gets better results when compared to CNN-base models.
- Published
- 2021
34. The Effects of Rhizobium Inoculation On The Growth Of Rice (Oryza Sativa L.) and White Radish (Raphanus Sativus L.)
- Author
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P M Nguyen, H T Nguyen, H T T Le, L B Nguyen, P H Tran, Y B Dinh, T K N Nguyen, and M H Nguyen
- Abstract
The utilization of chemical fertilizers in agriculture production could cause harmful effects on human health and the environment, therefore the development and application of biofertilizers produced from beneficial microorganisms like plant growth-promoting rhizobacteria have been increasingly encouraged. The present study investigated the effects of the inoculation of the two Rhizobium pusense strains (R. pusense GCB108 and R. pusense GCB117) on the growth of the young rice plant (Oryza sativa L.) and white radish (Raphanus sativus L.). The results showed that the inoculation of the two R. pusense strains affected the growth of rice and white radish considerably. On day 7, the shoot length of Oryza sativa L. grown on the medium inoculated with the R. pusense GCB108 and GCB117 was 22.3 ± 0.42 cm and 21.6 ± 2.26 cm, respectively, while that recorded in the control sample (without bacterial inoculation) was only 18.25 ± 1.06 cm. On day 9, the shoot length of Raphanus sativus L. grown under the hydroponic condition and inoculated with the R. pusense GCB108 and GCB117 was 12.68 ± 1.22 cm and 13.69 ± 1.47 cm, respectively, while that recorded in the control sample was much lower (9.04 ± 1.86 cm). Moreover, the inoculation of R. pusense GCB108 and GCB117 also restricted the growth of the rice pathogen Pseudomonas oryzihabitans RL01 in the rice rhizosphere. Furthermore, the results from the biophysiological assay showed that both two strains R. pusense GCB108 and GCB117 could grow under a salinity environment (salt concentration of 3%) and a wide range of pH conditions (pH 5 – 11). The study demonstrates the importance of the R. pusense GCB108 and GCB117 inoculation in the growth of rice and white radish and suggests the potential application of those two strains in biofertilizer production to improve soil quality and stimulate plant growth, contributing to sustainable agriculture development.
- Published
- 2022
35. Monodromy in Prolate Spheroidal Harmonics
- Author
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Diana M. H. Nguyen, Holger R. Dullin, and Sean R. Dawson
- Subjects
Physics ,Integrable system ,Applied Mathematics ,010102 general mathematics ,Spectrum (functional analysis) ,37J15, 37J35, 53D20, 53D22, 81Q20 ,FOS: Physical sciences ,Mathematical Physics (math-ph) ,Dynamical Systems (math.DS) ,Eigenfunction ,Mathematics::Spectral Theory ,Quantum number ,01 natural sciences ,010305 fluids & plasmas ,Monodromy ,Special functions ,0103 physical sciences ,Quantum system ,FOS: Mathematics ,0101 mathematics ,Mathematics - Dynamical Systems ,Wave function ,Mathematical Physics ,Mathematical physics - Abstract
We show that spheroidal wave functions viewed as the essential part of the joint eigenfunction of two commuting operators of $L_2(S^2)$ has a defect in the joint spectrum that makes a global labelling of the joint eigenfunctions by quantum numbers impossible. To our knowledge this is the first explicit demonstration that quantum monodromy exists in a class of classically known special functions. Using an analogue of the Laplace-Runge-Lenz vector we show that the corresponding classical Liouville integrable system is symplectically equivalent to the C. Neumann system. To prove the existence of this defect we construct a classical integrable system that is the semi-classical limit of the quantum integrable system of commuting operators. We show that this is a semi-toric system with a non-degenerate focus-focus point, such that there is monodromy in the classical and the quantum system., 26 pages, 11 figures
- Published
- 2020
36. A Visually Explainable Learning System for Skin Lesion Detection Using Multiscale Input with Attention U-Net
- Author
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Abraham Obinwanne Ezema, Daniel Sonntag, Fabrizio Nunnari, and Duy M. H. Nguyen
- Subjects
Task (computing) ,Computer science ,business.industry ,Computation ,Feature extraction ,Segmentation ,Pattern recognition ,Artificial intelligence ,Transfer of learning ,Skin lesion ,business ,Mobile device ,Implementation - Abstract
In this work, we propose a new approach to automatically predict the locations of visual dermoscopic attributes for Task 2 of the ISIC 2018 Challenge. Our method is based on the Attention U-Net with multi-scale images as input. We apply a new strategy based on transfer learning, i.e., training the deep network for feature extraction by adapting the weights of the network trained for segmentation. Our tests show that, first, the proposed algorithm is on par or outperforms the best ISIC 2018 architectures (LeHealth and NMN) in the extraction of two visual features. Secondly, it uses only 1/30 of the training parameters; we observed less computation and memory requirements, which are particularly useful for future implementations on mobile devices. Finally, our approach generates visually explainable behaviour with uncertainty estimations to help doctors in diagnosis and treatment decisions.
- Published
- 2020
37. Estimating the health impact of vaccination against ten pathogens in 98 low-income and middle-income countries from 2000 to 2030: a modelling study
- Author
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Hira Tanvir, T. Papadopoulos, Yvonne Tam, Petra Klepac, Emilia Vynnycky, Kaja Abbas, Michael L. Jackson, Mark Jit, Katy A. M. Gaythorpe, Andrew Clark, Amy Winter, Nicholas C. Grassly, Quan Minh Tran, Colin Sanderson, Homie Razavi, Xiang Li, Caroline Trotter, Andromachi Karachaliou, Sean M. Moore, Matthew J. Ferrari, Stephen Sy, Duy M. H. Nguyen, Steven Sweet, Kirsten Eilertson, Justin Lessler, Christinah Mukandavire, Devin Razavi-Shearer, Stephen C Resch, Emily D Carter, Wes Hinsley, Ivane Gamkrelidze, Tini Garske, Shaun A. Truelove, Susy Echeverria Londono, Shevanthi Nayagam, Neil M. Ferguson, Kévin Jean, Hannah E. Clapham, Kevin van Zandvoort, Timothy B. Hallett, Hope L. Johnson, Margaret J. de Villiers, Zulma M. Cucunubá, Kim Woodruff, Stéphane Verguet, Xi Li, Neff Walker, Marc Brisson, Imperial College London, London School of Hygiene and Tropical Medicine (LSHTM), National University of Singapore (NUS), Oxford University Clinical Research Unit [Ho Chi Minh City] (OUCRU), University of Oxford, The University of Hong Kong (HKU), Public Health England [London], Gavi Alliance, University of Southampton, Université Laval [Québec] (ULaval), Johns Hopkins Bloomberg School of Public Health [Baltimore], Johns Hopkins University (JHU), Colorado State University [Fort Collins] (CSU), Pennsylvania State University (Penn State), Penn State System, Center for Disease Analysis Foundation [Lafayette, CO, États-Unis], Kaiser Permanente Washington Health Research Institute [Seattle] (KPWHRI), Laboratoire Modélisation, épidémiologie et surveillance des risques sanitaires (MESuRS), Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Pasteur-Cnam Risques infectieux et émergents (PACRI), Institut Pasteur [Paris] (IP)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Université Paris Cité (UPCité), University of Cambridge [UK] (CAM), University of Notre Dame [Indiana] (UND), Dublin City University [Dublin] (DCU), Harvard T.H. Chan School of Public Health, Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation., Bill & Melinda Gates Foundation, World Health Organization, and Medical Research Council (MRC)
- Subjects
Male ,Cost-Benefit Analysis ,CHILDREN ,030204 cardiovascular system & hematology ,Global Health ,DISEASE ,0302 clinical medicine ,Global health ,030212 general & internal medicine ,11 Medical and Health Sciences ,Vaccines ,Vaccination ,General Medicine ,Articles ,IMMUNIZATION ,Child, Preschool ,Income ,Female ,Quality-Adjusted Life Years ,BURDEN ,Life Sciences & Biomedicine ,Vaccine Impact Modelling Consortium ,medicine.medical_specialty ,Rubella ,Measles ,Communicable Diseases ,03 medical and health sciences ,Medicine, General & Internal ,Environmental health ,General & Internal Medicine ,BENEFITS ,medicine ,Humans ,Mortality ,Poverty ,Developing Countries ,Disease burden ,Science & Technology ,business.industry ,Immunization Programs ,Public health ,GAVI ,Models, Theoretical ,medicine.disease ,TRENDS ,Quality-adjusted life year ,Immunization ,Communicable Disease Control ,[SDV.SPEE]Life Sciences [q-bio]/Santé publique et épidémiologie ,[SDV.IMM.VAC]Life Sciences [q-bio]/Immunology/Vaccinology ,business - Abstract
Summary Background The past two decades have seen expansion of childhood vaccination programmes in low-income and middle-income countries (LMICs). We quantify the health impact of these programmes by estimating the deaths and disability-adjusted life-years (DALYs) averted by vaccination against ten pathogens in 98 LMICs between 2000 and 2030. Methods 16 independent research groups provided model-based disease burden estimates under a range of vaccination coverage scenarios for ten pathogens: hepatitis B virus, Haemophilus influenzae type B, human papillomavirus, Japanese encephalitis, measles, Neisseria meningitidis serogroup A, Streptococcus pneumoniae, rotavirus, rubella, and yellow fever. Using standardised demographic data and vaccine coverage, the impact of vaccination programmes was determined by comparing model estimates from a no-vaccination counterfactual scenario with those from a reported and projected vaccination scenario. We present deaths and DALYs averted between 2000 and 2030 by calendar year and by annual birth cohort. Findings We estimate that vaccination of the ten selected pathogens will have averted 69 million (95% credible interval 52–88) deaths between 2000 and 2030, of which 37 million (30–48) were averted between 2000 and 2019. From 2000 to 2019, this represents a 45% (36–58) reduction in deaths compared with the counterfactual scenario of no vaccination. Most of this impact is concentrated in a reduction in mortality among children younger than 5 years (57% reduction [52–66]), most notably from measles. Over the lifetime of birth cohorts born between 2000 and 2030, we predict that 120 million (93–150) deaths will be averted by vaccination, of which 58 million (39–76) are due to measles vaccination and 38 million (25–52) are due to hepatitis B vaccination. We estimate that increases in vaccine coverage and introductions of additional vaccines will result in a 72% (59–81) reduction in lifetime mortality in the 2019 birth cohort. Interpretation Increases in vaccine coverage and the introduction of new vaccines into LMICs have had a major impact in reducing mortality. These public health gains are predicted to increase in coming decades if progress in increasing coverage is sustained. Funding Gavi, the Vaccine Alliance and the Bill & Melinda Gates Foundation.
- Published
- 2019
38. Dynamic Kinetic Resolution of Aldehydes by Hydroacylation
- Author
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Vy M. Dong, Zhiwei Chen, Yusuke Aota, and Hillary M. H. Nguyen
- Subjects
Acylation ,chemistry.chemical_element ,Hydroacylation ,Cyclopentanes ,Alkenes ,010402 general chemistry ,01 natural sciences ,Aldehyde ,C−H activation ,Article ,Catalysis ,Enamine ,Rhodium ,Kinetic resolution ,dynamic kinetic resolution ,chemistry.chemical_compound ,Organic chemistry ,C-H activation ,chemistry.chemical_classification ,Olefin fiber ,Aldehydes ,hydroacylation ,Molecular Structure ,010405 organic chemistry ,Hydrolysis ,Organic Chemistry ,Cationic polymerization ,Stereoisomerism ,General Chemistry ,General Medicine ,0104 chemical sciences ,Kinetics ,chemistry ,dual catalysis ,rhodium ,Chemical Sciences ,Thermodynamics - Abstract
We report a dynamic kinetic resolution (DKR) of chiral 4-pentenals by olefin hydroacylation. A primary amine racemizes the aldehyde substrate via enamine formation and hydrolysis. Then, a cationic rhodium catalyst promotes hydroacylation to generate α,γ-disubstituted cyclopentanones with high enantio- and diastereoselectivities.
- Published
- 2019
39. Automatically Generate Hymns Using Variational Attention Models
- Author
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Duy M. H. Nguyen, Binh T. Nguyen, Han K. Cao, and Duyen T. Ly
- Subjects
Computer science ,business.industry ,02 engineering and technology ,010501 environmental sciences ,Machine learning ,computer.software_genre ,01 natural sciences ,Musicology ,0202 electrical engineering, electronic engineering, information engineering ,Entropy (information theory) ,020201 artificial intelligence & image processing ,Edit distance ,Artificial intelligence ,business ,computer ,0105 earth and related environmental sciences ,BLEU - Abstract
Building an intelligent system for automatically composing music like human beings has been actively investigated during the last decade. In this work, we propose a new approach for automatically creating hymns by training a variational attention model from a large collection of religious songs. We compare our method with two other techniques by using Seq2Seq and attention models and measure the corresponding performance by BLEU-N scores, the entropy, and the edit distance. Experimental results show that the proposed method can achieve a promising performance that is able to give an additional contribution to the current study of music formulation. Finally, we publish our dataset online for further research related to the problem.
- Published
- 2019
40. Phytoplankton diversity and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)
- Author
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T. M. H. Nguyen, Pablo Navarro, Robert Arfi, Jean-Pascal Torréton, Thierry Bouvier, T. T. T. Cao, Emma Rochelle-Newall, Xavier Mari, Olivier Pringault, T. T. Pham, Yvan Bettarel, Sylvain Ouillon, Patrice Got, V. T. Chu, David Amouroux, T. N. Duong, and Corinne Bouvier
- Subjects
Wet season ,geography ,geography.geographical_feature_category ,Ecology ,fungi ,chemistry.chemical_element ,Estuary ,Particulates ,Mercury (element) ,Oceanography ,Productivity (ecology) ,chemistry ,Dry season ,Phytoplankton ,Environmental science ,Ecosystem - Abstract
The factors controlling estuarine phytoplankton diversity and production are relatively well known in temperate systems. Less however is known about the factors affecting phytoplankton community distribution in tropical estuaries. This is surprising given the economic and ecological importance of these large, deltaic ecosystems, such as are found in South East Asia. Here we present the results from an investigation into the factors controlling phytoplankton distribution and phytoplankton-bacterial coupling in the Bach Dang Estuary, a sub-estuary of the Red River system, in Northern Vietnam. Phytoplankton diversity and primary and bacterial production, nutrients and metallic contaminants (mercury and organotin) were measured during two seasons: wet (July 2008) and dry (March 2009). Phytoplankton community composition differed between the two seasons with only a 2% similarity between July and March. The large spatial extent and complexity of defining the freshwater sources meant that simple mixing diagrams could not be used in this system. We therefore employed multivariate analyses to determine the factors influencing phytoplankton community structure. Salinity and suspended particulate matter were important factors in determining phytoplankton distribution, particularly during the wet season. We also show that phytoplankton community structure is probably influenced by the concentrations of mercury species (inorganic mercury and methyl mercury in both the particulate and dissolved phases) and of tri-, di, and mono-butyl tin species found in this system. Freshwater phytoplankton community composition was associated with dissolved methyl mercury and particulate inorganic mercury concentrations during the wet season, whereas, during the dry season, dissolved methyl mercury and particulate butyl tin species were important factors for the discrimination of the phytoplankton community structure. Phytoplankton-bacterioplankton coupling was also investigated during both seasons. In the inshore, riverine stations the ratio between bacterial production and dissolved primary production was high supporting the hypothesis that bacterial carbon demand is supported by allochthonous riverine carbon sources. The inverse was true in the offshore stations, where BP:DPP values were less than 1, potentially reflecting differences in primary production due to shifting phytoplankton community diversity.
- Published
- 2018
41. An active learning framework for set inversion
- Author
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Vu Dinh, Duy M. H. Nguyen, Lam Si Tung Ho, and Binh T. Nguyen
- Subjects
Information Systems and Management ,Set inversion ,Computer science ,Active learning (machine learning) ,02 engineering and technology ,Management Information Systems ,Interval arithmetic ,Set (abstract data type) ,Data point ,Artificial Intelligence ,Control theory ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Algorithm ,Software - Abstract
Set inversion is a classical problem in control theory that has many important applications in various fields of science and engineering. The state-of-the-art method for solving this problem, Set Inverter Via Interval Analysis (SIVIA), usually does not work well in high dimensions and often fails to recover sets with complicated structures. In this work, we propose a new approach to the problem of set inversion, which employs techniques from machine learning to resolve these issues. Our algorithm can handle problems in high dimensions and achieve the same level of accuracy with fewer data points compared to SIVIA. We illustrate the performance of our method in various simulation studies and apply it to investigate the dynamics of the 17th-century plague in Eyam village, England.
- Published
- 2019
42. Association of Health Care Utilization With Rates of Perforated Appendicitis in Children 18 Years or Younger
- Author
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Mark L. Wulkan, Mehul V. Raval, Katherine J. Baxter, and Hannah T. M. H. Nguyen
- Subjects
Male ,Pediatrics ,medicine.medical_specialty ,Adolescent ,Perforation (oil well) ,03 medical and health sciences ,0302 clinical medicine ,030225 pediatrics ,Health care ,Outpatient clinic ,Medicine ,Appendectomy ,Humans ,Child ,Retrospective Studies ,Original Investigation ,National Insurance ,Insurance, Health ,business.industry ,Incidence (epidemiology) ,Incidence ,Retrospective cohort study ,Patient Acceptance of Health Care ,medicine.disease ,Appendicitis ,United States ,030220 oncology & carcinogenesis ,Acute Disease ,Surgery ,Female ,Diagnosis code ,business ,Follow-Up Studies - Abstract
The pediatric perforated appendix rate is a quality metric measured by the Agency for Healthcare Research and Quality (AHRQ) that reflects access to care. The association of health care utilization prior to presentation with appendicitis is unknown.To determine whether increased health care utilization prior to presentation with appendicitis is associated with lower perforated appendicitis rates in children.Retrospective cohort study of privately insured children drawn from large employer and insurance company administrative data found in the Truven MarketScan national insurance claims database. Cases of appendicitis were identified among 38 348 children 18 years or younger from January 1, 2010, through December 31, 2013, with corresponding primary health care encounters from January 1, 2009, through December 31, 2012. In all, 19 109 eligible children were identified using International Classification of Diseases, Ninth Revision (ICD-9) diagnosis codes for appendicitis after excluding those patients who did not have continuous insurance coverage during the study period. Statistical analysis was performed from September 1, 2016, to October 15, 2017.Health care utilization was determined by the number of outpatient clinic encounters for each patient in the 1 to 12 months before presentation with appendicitis.Perforated appendicitis was defined according to the AHRQ by using ICD-9 codes for perforation and hospital length of stay of 3 or more days. Logistic regression models were used for perforated appendicitis after adjustment for age, sex, income, gastrointestinal comorbidities, geographic region, and insurance type.We identified 38 348 children 18 years or younger with ICD-9 diagnosis codes for appendicitis, and 19 109 children remained for analysis after applying exclusion criteria. Of these, 11 422 were boys (59.8%); the mean (SD) age was 12.4 (3.9) years. Of the 19 109 children identified who underwent appendectomy, 5509 (28.8%) presented with perforated appendicitis. Children with perforation had lower outpatient health care utilization in the year before presentation compared with those diagnosed with acute appendicitis (4554 of 5509 children [82.7%] vs 11 937 of 13 600 [87.8%]; P .001). In the adjusted model, outpatient health care utilization before presentation was associated with lower odds of perforated appendicitis (odds ratio [OR], 0.63; 95% CI, 0.58-0.69; P .001). This association increased with visit frequency in the year before presentation (OR, 0.86; 95% CI, 0.77-0.95 for 1-2 visits, P = .003; OR, 0.61; 95% CI, 0.55-0.67 for 3-6 visits, P .001; and OR, 0.43; 95% CI, 0.38-0.48 for ≥7 visits [5-18 years], P .001). Covariates associated with perforation included younger age, geographic region, family income, and higher out-of-pocket insurance plans.Among insured children 18 years or younger, increased health care utilization was associated with lower rates of perforated appendicitis. Primary health care relationships may facilitate timely presentation or serve as a marker for health-related self-efficacy, thereby contributing to outcomes for acute surgical conditions.
- Published
- 2018
43. An extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3) for free vibration analysis of cracked Reissner-Mindlin shells
- Author
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Trung Nguyen-Thoi, L. Le-Anh, V. Ho-Huu, M. H. Nguyen-Thoi, and H. Dang-Trung
- Subjects
Commercial software ,Engineering ,business.industry ,Structural engineering ,Finite element method ,Vibration ,Shear (geology) ,Architecture ,Smoothed finite element method ,business ,Softening ,Civil and Structural Engineering ,Cell based ,Extended finite element method - Abstract
A cell-based smoothed discrete shear gap method (CS-FEM-DSG3) was recently proposed and proven to be robust for free vibration analyses of Reissner-Mindlin shell. The method improves significantly the accuracy of the solution due to softening effect of the cell-based strain smoothing technique. In addition, due to using only three-node triangular elements generated automatically, the CS-FEM-DSG3 can be applied flexibly for arbitrary complicated geometric domains. However so far, the CS-FEM-DSG3 has been only developed for analyzing intact structures without possessing internal cracks. The paper hence tries to extend the CS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells by integrating the original CS-FEM-DSG3 with discontinuous and crack–tip singular enrichment functions of the extended finite element method (XFEM) to give a so-called extended cell-based smoothed discrete shear gap method (XCS-FEM-DSG3). The accuracy and reliability of the novel XCS-FEM-DSG3 for free vibration analysis of cracked Reissner-Mindlin shells are investigated through solving three numerical examples and comparing with commercial software ANSYS.
- Published
- 2015
44. An improved constrained differential evolution using discrete variables (D-ICDE) for layout optimization of truss structures
- Author
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L. Le-Anh, M. H. Nguyen-Thoi, Trung Nguyen-Thoi, and V. Ho-Huu
- Subjects
Continuous optimization ,Mathematical optimization ,Optimization problem ,Quantitative Biology::Tissues and Organs ,Reliability (computer networking) ,General Engineering ,Truss ,Continuous design ,Computer Science Applications ,Artificial Intelligence ,Differential evolution ,Discrete optimization ,Convergence (routing) ,Physics::Atomic and Molecular Clusters ,Mathematics - Abstract
A discrete variable technique is integrated into ICDE to give Discrete-ICDE.Discrete-ICDE is then applied for the truss layout optimization problems.Numerical results show that Discrete-ICDE is robust, effective and reliable. Recently, an improved (µ+λ) constrainted differential evolution (ICDE) has been proposed and proven to be robust and effective for solving constrainted optimization problems. However, so far, the ICDE has been developed mainly for continuous design variables, and hence it becomes inappropriate for solving layout truss optimization problems which contain both discrete and continuous variables. This paper hence fills this gap by proposing a novel discrete variables handling technique and integrating it into original ICDE to give a so-called Discrete-ICDE (D-ICDE) for solving layout truss optimization problems. Objective functions of the optimization problems are minimum weights of the whole truss structures and constraints are stress, displacement and buckling limitations. Numerical examples of five classical truss problems are carried out and compared to other state-of-the-art optimization methods to illustrate the reliability and effectiveness of the proposed method. The D-ICDE's performance shows that it not only successfully handles discrete variables but also significantly improves the convergence of layout truss optimization problem. The D-ICDE is promising to extend for determining the optimal solution of other structural optimization problems which contain both discrete and continuous variables.
- Published
- 2015
45. An upper-bound limit analysis of Mindlin plates using CS-DSG3 method and second-order cone programming
- Author
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Trung Nguyen-Thoi, M. H. Nguyen-Thoi, P. Phung-Van, and H. Dang-Trung
- Subjects
Applied Mathematics ,Geometry ,Kinematics ,Dissipation ,Upper and lower bounds ,Condensed Matter::Soft Condensed Matter ,Computational Mathematics ,Limit analysis ,Applied mathematics ,von Mises yield criterion ,Second-order cone programming ,Limit load ,Boundary value problem ,Mathematics - Abstract
The paper presents a numerical procedure for kinematic limit analysis of Mindlin plate governed by von Mises criterion. The cell-based smoothed discrete shear gap method (CS-DSG3) is combined with a second-order cone optimization programming (SOCP) for determining the upper bound limit load of the Mindlin plates. The limit analysis problem of Mindlin plates is formulated by minimizing the dissipation power subjected to a set of constraints of boundary conditions and unitary external work. This minimization problem is then transformed into an explicit form suitable for the solution using the SOCP. The numerical results of some benchmark problems show that the proposal procedure can provide the reliable upper bound collapse multipliers for the Mindlin plates. CS-DSG3 is combined with SOCP for determining upper bound limit load of Mindlin plates.Limit analysis problem is transformed into an explicit form suitable for solution using SOCP and CS-DSG3.Numerical results show that CS-DSG3 is free of shear locking and can provide reliable upper bound collapse multipliers for Mindlin plates.
- Published
- 2015
46. A Comparison of Performance of Six and Twelve-Blade Vane Tidal Turbines between Single and Double Blade-row Types
- Author
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C. Yang, J. H. Kim, M. H. Nguyen, and B. K. Kim
- Subjects
Engineering ,Blade (geometry) ,business.industry ,Torque ,Computational fluid dynamics ,business ,Row ,Tidal current ,Turbine ,Tidal power ,Simulation ,Power (physics) ,Marine engineering - Abstract
This paper presents a study on Vane Tidal Turbine (VTT) focusing on analysis of two types of blade arrangement originated from the previous studies where the original design was examined and performance-tested for different numbers of blades (six, eight and twelve). Compared to conventional tidal turbines, VTT has several special features and potential advantages which have been being thoroughly developed. The purpose of this study is to analyze VTT’s capability of extracting and converting the hydrokinetic energy of tidal currents into electricity at given arrangement of blades (single and double rows, six and twelve blades) using CFD. From the calculation results, the six-blade single row turbine shows the best performance, in which the highest power and torque coefficients reach up to about 34 % and 36 %, respectively, at TSR=0.94. However, despite of lower power coefficient, by adding more blades, the torque’s extraction of twelve-blade turbine, especially the double row type, is less fluctuate than that of the six-blade setups.
- Published
- 2015
47. THE INFLUENCE OF EARNING MANAGEMENT AND SURPLUS FREE CASH FLOW ON THE BANKING SECTOR PERFORMANCE.
- Author
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V. H., Thai, V. T., Dinh, V. S., Nguyen, M. H., Nguyen, C. T., Nguyen, and T. L. P., Pham
- Subjects
FREE cash flow ,ASSET-liability management ,FIXED effects model ,EARNINGS management ,FINANCIAL statements - Abstract
Copyright of Polish Journal of Management Studies is the property of Czestochowa University of Technology, Faculty of Management and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2021
- Full Text
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48. Demo
- Author
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Tam Vu, Duy M. H. Nguyen, Nhan Nguyen, Binh Nguyen, Anh Nguyen, Ashwin Ashok, and Bao Pham
- Subjects
Constraint (information theory) ,Mechanism (engineering) ,Acceleration ,Vision based ,Computer science ,business.industry ,Vibration sensing ,business ,Keyboard layout ,Mobile device ,Computer hardware ,Gesture - Abstract
Using touchscreens has largely limited user inputs to small form-factor devices. To address this constraint, we explore a novel input mechanism, dubbed PaperKey, that enables users to interact with mobile devices by performing multi-finger typing gestures on a surface where the device is placed. Using acceleration signals on the device, PaperKey infers the user's type events and then leverages a vision based technique for detecting the exact typing locations on a paper keyboard layout. Compared to single audio, image, or vibration sensing, this work accurately localizes keystrokes with faster processing speed. Additionally, this mechanism keeps the mobility of devices by working without external sensors.
- Published
- 2017
49. 3D-Brain Segmentation Using Deep Neural Network and Gaussian Mixture Model
- Author
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Huy Q. Ung, Huy Vu, Duy M. H. Nguyen, and Binh T. Nguyen
- Subjects
Artificial neural network ,Computer science ,business.industry ,Scale-space segmentation ,Image segmentation ,Mixture model ,computer.software_genre ,030218 nuclear medicine & medical imaging ,Convolution ,03 medical and health sciences ,0302 clinical medicine ,Voxel ,Margin (machine learning) ,Brain segmentation ,Computer vision ,Artificial intelligence ,business ,computer ,030217 neurology & neurosurgery - Abstract
Automatic segmentation of major brain tissues from high-resolution magnetic resonance images (MRIs) plays an important role in clinical diagnostics and neuroscience research. In this paper, we present a novel approach to extract brain tissues including gray matter, white matter and cerebrospinal fluid by using Gaussian mixture models (GMMs), Convolution neural networks (CNNs) and Deep neural networks (DNNs). GMMs are applied to classify voxels which have distinct intensity information and are easy to recognize while DNNs and CNNs are treating voxels which are similar in appearance and usually recognized insufficiently by traditional approaches. The empirical results on IBSR 18 dataset show that the proposed method outperforms 13 state-of-the-art algorithms, surpassing all other methods by a significant margin.
- Published
- 2017
50. Integration and validation of the Geant4-DNA physical models into GATE simulation platform
- Author
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T. M. H. Nguyen and Q. T. Pham
- Subjects
Field (physics) ,Computer science ,Point source ,Monte Carlo method ,Tracking (particle physics) ,Secondary electrons ,Imaging phantom ,030218 nuclear medicine & medical imaging ,Computational science ,03 medical and health sciences ,0302 clinical medicine ,030220 oncology & carcinogenesis ,Logic gate ,Point (geometry) ,Simulation - Abstract
GATE (Geant4 Application for Tomographic Emission) is an open-source Monte-Carlo simulation platform based on Geant4 (GEometry And Tracking) simulation toolkit, widely used for many medical physics applications. Since the Geant4-DNA physical models have been integrated into the version GATE v7.0, the applications of GATE are extended to the field of radiobiology. The latest version GATE v7.2 is based on the Geant4.10.02.p01 version. However, the new Geant4-DNA Physics List with different options (opt1, opt2, opt3, opt4, opt5) of the Geant4.10.02.p01 version have not been incorporated in GATE v7.2; therefore we implemented the integration of the new Geant4-DNA Physics Lists into GATE v7.3-beta based on Geant4.10.02.p01. Also, we combined two different Physics List (Mixed Physics List) in GATE v7.3-beta which can be used in the same simulation. GATE v7.3-beta is a version of GATE that we developed in our work. In order to validate and verify the correct implementation of the Geant4-DNA physical models into GATE v7.3-beta, we used two benchmarks : DPKs (Dose Point Kernels) of 50000 particles of 10 keV electron point source in spherical water phantom with the diameter of 400 mm; and Example_DNA for 3000 particles of 8 MeV proton point source in three different targets made of liquid water with the thickness of 50 pm. A good agreement is found for the DPK calculation in case of 10 keV electrons where differences for eighteen shells are below 5 % between GATE and Geant4.10.02. The conclusions are : the validation of Geant4-DNA physical models by comparing of GATE v7.3-beta DPKs with Geant4.10.02.p01 and EGSnrc, the spectrum of the secondary electrons generated in three targets demonstrated the successful operation of the new Mixed Physics List in GATE v7.3-beta.
- Published
- 2016
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