Common methodological issues and suggested solutions in bone research

Tuan V. Nguyen 대한골다공증학회 2020 Osteoporosis and Sarcopenia Vol.6 No.4

Bone research is a dynamic area of scientific investigation that usually encompasses multidisciplines. Virtually all basic cellular research, clinical research and epidemiologic research rely on statistical concepts and methodology for inference. This paper discusses common issues and suggested solutions concerning the application of statistical thinking in bone research, particularly in clinical and epidemiological investigations. The issues are sample size estimation, biases and confounders, analysis of longitudinal data, categorization of continuous data, selection of significant variables, over-fitting, P-values, false positive finding, confidence interval, and Bayesian inference. It is hoped that by adopting the suggested measures the scientific quality of bone research can improve.

Individualized fracture risk assessment: State-of-the-art and room for improvement

Tuan V. Nguyen 대한골다공증학회 2018 Osteoporosis and Sarcopenia Vol.4 No.1

Fragility fracture is a serious clinical event, because it is associated with increased risk of mortality and reduced quality of life. The risk of fracture is determined by multiple risk factors, and their effects may be interactional. Over the past 10 years, a number of predictive models (e.g., FRAX, Garvan Fracture Risk Calculator, and Qfracture) have been developed for individualized assessment of fracture risk. These models use different risk profiles to estimate the probability of fracture over 5- and 10-year period. The ability of these models to discriminate between those individuals who will and will not have a fracture (i.e., area under the receiver operating characteristic curve [AUC]) is generally acceptable-to-good (AUC,0.6 to 0.8), and is highly variable between populations. The calibration of existing models is poor, particularly in Asian populations. There is a strong need for the development and validation of new prediction models based on Asian data for Asian populations. We propose approaches to improve the accuracy of existing predictive models by incorporating new markers such as genetic factors, bone turnover markers, trabecular bone score, and time-variant factors. New and more refined models for individualized fracture risk assessment will help identify those most likely to sustain a fracture, those most likely to benefit from treatment, and encouraging them to modify their risk profile to decrease risk.

Association between Fat Mass and Obesity-Related Transcript Polymorphisms and Osteoporosis Phenotypes

Tuan V. Nguyen 대한골대사학회 2024 대한골대사학회지 Vol.31 No.1

Background: Common variants in the fat mass and obesity-related transcript (FTO) gene are related to body mass index and obesity, suggesting its potential association with bone mineral density (BMD) and fracture risk. This study sought to define the association between FTO gene variants and the following phenotypes: (1) BMD; (2) bone loss; and (3) fracture risk. Methods: This analysis was based on the Dubbo Osteoporosis Epidemiology Study that included 1,277 postmenopausal women aged ≥60 years living in Dubbo, Australia. BMD at the femoral neck and lumbar spine was measured biennially by dual energy X-ray absorptiometry (GE Lunar). Fractures were radiologically ascertained. Six single nucleotide polymorphisms (SNPs; rs1421085, rs1558902, rs1121980, rs17817449, rs9939609, and rs9930506) of the FTO gene were genotyped using TaqMan assay. Results: Women homozygous for the minor allele (GG) of rs9930506 had a significantly higher risk of hip fracture (adjusted hazard ratio, 1.93; 95% confidence interval, 1.15–3.23) than those homozygous for the major allele (AA) after adjusting for potential confounding effects. Similar associations were also observed for the minor allele of rs1121980. However, there was no significant association between the FTO SNPs and BMD or the rate of bone loss. Conclusions: Common variations in the FTO gene are associated with a hip fracture risk in women, and the association is not mediated through BMD or bone loss.

Precoder Design for Signal Superposition in MIMO-NOMA Multicell Networks

Nguyen, V.,Tuan, H. D.,Duong, T. Q.,Poor, H. V.,Shin, O. IEEE INSTITUTE OF ELECTRICAL AND ELECTRONICS 2017 IEEE journal on selected areas in communications Vol.35 No.12

Microprocessor depends on hemin to recognize the apical loop of primary microRNA

Nguyen, Tuan ,Anh,Park, Joha,Dang, Thi ,Lieu,Choi, Yeon-Gil,Kim, V ,Narry Oxford University Press 2018 Nucleic acids research Vol.46 No.11

<P><B>Abstract</B></P><P>Microprocessor, which consists of a ribonuclease III DROSHA and its cofactor DGCR8, initiates microRNA (miRNA) maturation by cleaving primary miRNA transcripts (pri-miRNAs). We recently demonstrated that the DGCR8 dimer recognizes the apical elements of pri-miRNAs, including the UGU motif, to accurately locate and orient Microprocessor on pri-miRNAs. However, the mechanism underlying the selective RNA binding remains unknown. In this study, we find that hemin, a ferric ion-containing porphyrin, enhances the specific interaction between the apical UGU motif and the DGCR8 dimer, allowing Microprocessor to achieve high efficiency and fidelity of pri-miRNA processing <I>in vitro</I>. Furthermore, by generating a DGCR8 mutant cell line and carrying out rescue experiments, we discover that hemin preferentially stimulates the expression of miRNAs possessing the UGU motif, thereby conferring differential regulation of miRNA maturation. Our findings reveal the molecular action mechanism of hemin in pri-miRNA processing and establish a novel function of hemin in inducing specific RNA-protein interaction.</P>

On a Riesz-Feller space fractional backward diffusion problem with a nonlinear source

Tuan, N.H.,Hai, D.N.D.,Long, L.D.,Nguyen, V.T.,Kirane, M. Koninklijke Vlaamse Ingenieursvereniging ; Elsevie 2017 Journal of computational and applied mathematics Vol.312 No.-

<P>In this paper, a backward diffusion problem for a space-fractional diffusion equation with a nonlinear source in a strip is investigated. This problem is obtained from the classical diffusion equation by replacing the second-order space derivative with a Riesz-Feller derivative of order alpha is an element of (0, 2]. A nonlinear problem is severely ill -posed, therefore we propose two new modified regularization solutions to solve it. We further show that the approximated problems are well-posed and their solutions converge if the original problem has a classical solution. In addition, the convergence estimates are presented under a priori bounded assumption of the exact solution. For estimating the error of the proposed method, a numerical example has been implemented. (C) 2016 Elsevier B.V. All rights reserved.</P>

Low Cost Motor Drive Technologies for ASEAN Electric Scooter

V. Tran Tuan,S. Kreuawan,P. Somsiri,P. Nguyen Huy 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.4

This work investigates two different motor drive technologies, switched reluctance motor (SRM) and induction motor (IM). They are designed optimally to meet the desired performances for electric scooters. The comparison of both motors is described in terms of performances and material cost. With the similar constraint, induction motor performs slightly better than switched reluctance motor. But this must be traded-off with higher weight and cost. Both drive systems are, however, suitable for electric scooter application. Finally, the range simulations are conducted on a European urban driving cycle, ECE15 driving cycle and a more realistic cycle, Bangkok driving cycle. The escooter ranges are varied from 36 to 109 km depending on driving cycle, motor technology and number of passengers.

Lean mass and peak bone mineral density

Huy G. Nguyen,Minh TD. Pham,Lan T. Ho-Pham,Tuan V. Nguyen 대한골다공증학회 2020 Osteoporosis and Sarcopenia Vol.6 No.4

Objectives: The association between body composition parameters and peak bone mineral density is not well documented. The aim of this study is to assess the relative contributions of lean mass and fat mass on peak bone mineral density (BMD). Methods: The study involved 416 women and 334 men aged between 20 and 30 years who were participants in the population-based Vietnam Osteoporosis Study. Whole body composition parameters (eg, fat mass and lean mass) and BMD at the lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. The association between lean mass and fat mass and BMD was analyzed by the linear regression model using the Least Absolute Shrinkage and Selection Operator (LASSO). Results: Peak BMD in men was higher than women, and the difference was more pronounced at the femoral neck (average difference: 0.123 g/cm2; 95% confidence interval [CI] 0.105–0.141 g/cm2) than at the lumbar spine (average difference 0.019 g/cm2; 95% CI, 0.005–0.036 g/cm2). Results of LASSO regression indicated that lean mass was the only predictor of BMD for either men or women. Each kilogram increase in lean mass was associated with ∼0.01 g/cm2 increase in BMD. Lean mass alone explained 16% and 36% of variation in lumbar spine and femoral neck BMD, respectively. Conclusions: Lean mass, not fat mass, is the main determinant of peak bone mineral density. This finding implies that good physical activity during adulthood can contribute to the maximization of peak bone mass during adulthood.

Influences of annealing and wire geometry on the giant magnetoimpedance effect in a glass-coated microwire LC-resonator

Le, Anh-Tuan,Phan, Manh-Huong,Kim, Chong-Oh,Vá,zquez, Manuel,Lee, Heebok,Hoa, Nguyen Quang,Yu, Seong-Cho Institute of Physics [etc.] 2007 Journal of Physics. D, Applied Physics Vol.40 No.15

<P>The influence of annealing and of wire geometry on the giant magnetoimpedance (GMI) effect in a glass-coated microwire LC-resonator were systematically investigated. It was found that annealing magnetic microwires significantly varied the permeability and hence the GMI ratio, whereas the magnetoimpedance response was sensitively altered with varying wire geometry of the LC-resonator. The magnitude of GMI is determined by the soft magnetic characteristics of the microwire and the effect of LC-resonance, while the multiple-peak GMI feature can be attributed to the LC-resonance circuit and the formation of standing magnetic waves within the sample. Interestingly, the GMI ratio reached the largest values of 400 000% and 270 000% at the resonance frequencies of 518.51 MHz and 146.32 MHz for Co<SUB>83.2</SUB>B<SUB>3.3</SUB>Si<SUB>5.9</SUB>Mn<SUB>7.6</SUB> and Co<SUB>67</SUB>Fe<SUB>3.8</SUB>Ni<SUB>1.4</SUB>B<SUB>11.5</SUB>Si<SUB>14.6</SUB>Mo<SUB>1.7</SUB> samples, respectively. The corresponding magnetic-field sensitivities of GMI are about 218 000%/Oe and 135 000%/Oe. These results are interesting for the development of a new family of ultra-sensitive and high-frequency magnetic sensors. The feature of a LC-resonance circuit can be used for improving the sensitivity of GMI-based magnetic sensors while selecting the working frequency.</P>

The plate on the nonlinear dynamic foundation under moving load

Phuoc T. Nguyen,Thieu V. Vi,Tuan T. Nguyen,Van T. Vu Techno-Press 2023 Coupled systems mechanics Vol.12 No.1

First introduced in 2016, the dynamic foundation model is an interesting topic in which the foundation is described close to reality by taking into account the influence of the foundation mass in the calculation of oscillation and is an important parameter that should be considered. In this paper, a follow-up investigation is conducted with the object of the Mindlin plate on a nonlinear dynamic foundation under moving loads. The base model includes nonlinear elastic springs, linear Pasternak parameters, viscous damping, and foundation mass. The problem is formulated by the finite element analysis and solved by the Newmark-β method. The displacement results at the center of the plate are analyzed and discussed with the change of various parameters including the nonlinear stiffness, the foundation mass, and the load velocity. The dynamic response of the plate sufficiently depends on the foundation mass.