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- Quan-Hoang Vuong (27)
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Contactless measurement of cardio-vascular pulse acts an essential role in clinical medical sectors. Estimating cardio-vascular pulses based on continuous-wave (CW) Doppler radar in limited time while maintaining the accuracy is a challenging task. In this paper, we propose a signal processing method that combines empirical mode decomposition (EMD) and continuous wavelet transform (CWT) for a short time estimation of heart rate (HR) and inter-beat-interval from radar signals. We evaluate performance of the proposed method using 85 patients with dengue fever and 40 healthy subjects. Subsequently, the estimated contactless HR is compared to that of a commercial contact-type medical device. The result shows that the HR can be estimated within a period of 5 s with an accuracy of 96.2 ± ... |
This study aimed to evaluate the impact of institutional research promoting policies and organizational characteristics on research productivity in Vietnam universities. The authors employed a dataset surveying faculty staff from 115 universities across the country and used multivariate data analysis to analyse data and test hypotheses. It was found that institutional characteristics such as size, time in operation and advantageous location were positively associated with research productivity. Specifically, universities located in the big cities with longer time in operation and larger size had higher level of international publication. Institutional policies such as management and infrastructure had a positive impact on research productivity while human resource policies had a pos... |
In this paper, we extend our investigation of the validity of the cosmic no-hair conjecture within non-canonical anisotropic inflation. As a result, we are able to figure out an exact Bianchi type I solution to a power-law k-inflation model in the presence of unusual coupling between scalar and electromagnetic fields as −f2(ϕ)FμνFμν/4. Furthermore, stability analysis based on the dynamical system method indicates that the obtained solution does admit stable and attractive hairs during an inflationary phase and therefore violates the cosmic no-hair conjecture. Finally, we show that the corresponding tensor-to-scalar ratio of this model turns out to be highly consistent with the observational data of the Planck 2018. |
In recent decades, there has been an increased demand for the processing of electrocardiogram (ECG) signals because of its significant role in diagnosing cardiac diseases. The QRS complex is the dominant feature of the ECG signal. The detection of QRS complexes is thus an essential part of almost any ECG signal processing systems. This paper presents a developed QRS complex detection method using dominant peak extraction and Shannon energy envelope for useful ECG signal analysis. The algorithm is divided into three main stages: pre-processing, searching for dominant peaks, and removing false R peaks. The proposed algorithm is validated in static ECG recordings from the MIT-BIH Arrhythmia Database (MITDB) and noise-contaminated ECG stress tests from the Glasgow University Database (G... |
α-Fe2O3 and Fe3O4 nanoplates and nanorices were synthesized by hydrothermal reaction and used for organic pollutant adsorption and removal studies. The effect of size and morphology of α-Fe2O3 and Fe3O4 nanoplates and nanorices on the dye adsorption efficiency were investigated systematically. The adsorption studies showed a good selectivity and high adsorption capacity (~93%) of the α-Fe2O3 nanoplates towards congo red (C.R.) dye, due to the formation of hydrogen bonding between amine group (─ NH2) of C.R. and surface carboxylate group (─ COOH), and adsorbed ─ OH groups of α-Fe2O3 nanoplates. The α-Fe2O3 nanoplates also showed excellent recyclability with negligible loss of the adsorption capacity, owing to their stable morphology and crystal structure. The excellent C.R. adsorptio... |
The use of magnetic nanoparticles in the treatment of cancer using alternating current hyperthermia therapy has shown the potential to replace or supplement conventional cancer treatments, radiotherapy and chemotherapy, which have severe side effects. Though the nearly spherical sub-10 nm iron oxide nanoparticles have their approval from the US Food and Drug Administration, their low heating efficiency and removal from the body after hyperthermia treatment raises serious concerns. The majority of magnetic hyperthermia research is working to create nanomaterials with improved heating efficiency and long blood circulation time. Here, we have demonstrated a simple strategy to enhance the heating efficiency of sub-10 nm Fe3O4 nanoparticles through the replacement of Fe+2 ions with Co+2 ... |
This study investigated the structure evolution, surface morphology, dielectric properties, ferroelectric properties, piezoelectric properties, and electromechanical strain properties of lead-free (Bi0.5−xLax)(Na0.41K0.09)TiO3 piezoelectric ceramics. All samples were fabricated by a traditional solid-state synthesis. The effects of La3+-isovalent substituted on Bi3+-site of the Bi0.5Na0.41K0.09TiO3 system were examined. The addition of La doping in the Bi0.5Na0.41K0.09TiO3 ceramics induced the second phase of K4Ti3O8 and a crystal structural change from the rhombohedral and tetragonal phase to a pseudocubic phase. All samples show similar grain morphology and dense microstructure with the average grain size around 1.33 to 1.61 μm. The dielectric curves and field-induced polarization... |
Effect of non-canonical scalar fields on the CMB imprints of the anisotropic inflation will be discussed in details in this paper. In particular, we are able to obtain the general formalism of the angular power spectra in the scalar perturbations, tensor perturbations, cross-correlations, and linear polarization in the context of the anisotropic inflation model involving non-canonical scalar fields. Furthermore, some significant numerical spectra will be plotted using the most recent data of Planck as well as the BICEP2 and Keck array. As a result, we find a very interesting point that the TT spectra induced by the tensor perturbations as well as by the linear polarization will increase when the speed of sound decreases. |
Nanofibers of ZnO-SnO2 nanocomposites doped with Au crystals were synthesized by an electrospinning method for enhancement of H2S gas sensing performance. The mixed solution of zinc acetate dihydrate and tin(II) chloride dihydrate, dissolved in ethanol/DMF solvent, was spun directly on the interdigital Pt electrodes for sensor fabrication. Thermal treatment was carried out to convert the spun nanofibers into ZnO-SnO2 nanocomposites doped with Au crystals. SEM and TEM observation confirmed the formation of porous nanofibers with an average diameter of about 120 nm. X-ray diffraction studies revealed that the nanocomposites of ZnO and SnO2 phases were formed, but not ZnSnO3, despite the precursor solution being mixed on the atomic scale from the starting solution. Doping with 0.001, 0... |
On average, one person dies by suicide every 40 s. However, extant studies have largely focused on the risk factors for suicidal behaviors, not so much on the formation of suicidal thoughts. Therefore, we attempt to explain how suicidal thoughts arise and persist inside one’s mind using a multifiltering information mechanism called Mindsponge. Bayesian analysis with Hamiltonian Markov Chain Monte Carlo (MCMC) technique was run on a dataset of multinational students (N = 268) of an international university in Japan. Item 9 in the PHQ-9 was used to survey suicidal ideation. The associations among four main variables, namely, (i) suicidal ideation, (ii) help-seeking willingness (informal and formal sources), (iii) sense of connectedness, and (iv) information inaccessibility (represente... |
