1,362 research outputs found
Noncommutativity in Effective Loop Quantum Cosmology
We construct a noncommutative extension of the Loop Quantum Cosmology
effective scheme for the open FLRW model with a free scalar field via a theta
deformation. Firstly, a deformation is implemented in the configuration sector,
among the holonomy variable and the matter degree of freedom. We show that this
type of noncommutativity retain, to some degree, key features of the Loop
Quantum Cosmology paradigm for a free field. Secondly, a deformation is
implemented in the momentum sector, among the momentum associated to the
holonomy variable and the momentum associated to the matter field. We show that
in this latter case the scalar field energy density is bounded and has the same
maximum as in standard Loop Quantum Cosmology, signaling a higher degree of
compatibility
Properties of flavonoids isolated from the bark of eysenhardtia polystachya and their effect on oxidative stress in streptozotocin-induced diabetes mellitus in mice
"Six new flavonoids 2′,4′-dihydroxychalcone-6′-O-β-D-glucopyranoside (1), α,3,2′,4′-tetrahydroxy-4-methoxy-dihydrochalcone-3′-C-β-glucopyranosy-6′-O-β-D-glucopyranoside (2), 7-hydroxy-5,8′-dimethoxy-6′α-L-rhamnopyranosyl-8-(3-phenyl-trans-acryloyl)-1-benzopyran-2-one (3), 6′7-dihydroxy-5,8-dimethoxy-8(3-phenyl-trans-acryloyl)-1-benzopyran-2-one (4), 9-hydroxy-3,8-dimethoxy-4-prenylpterocarpan (5), and α,4,4′-trihydroxydihydrochalcone-2′-O-β-D-glucopyranoside (6) were isolated from bark of Eysenhardtia polystachya.Antidiabetic activity of compounds 1–5 in terms of their cellular antioxidant and free radical scavenging and also in streptozotocin- (STZ-) induced diabetic mice was evaluated on liver transaminases, lipid peroxidation, total bilirubin, total protein, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (CSH-Px), and glutathione reductase (GSH). Results indicated that 1–5 scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (), nitric oxide radicals (), superoxide anion radical (), radical cation (), and hydrogen peroxide (H2O2) radical, and protection against H2O2 induced BSA damage was also observed. Furthermore, 1–5 showed ability to decrease the oxidative stress in H9c2 cell. Diabetic mice present high levels of lipid peroxide, total protein, SGPT, SGOT, ALP, and TB. However, treatment of STZ-induced diabetes in mice with 1–5 reduced levels of these enzymes leading to protector effect of liver. In addition, with treatment with 1–5, increases in radical scavenging enzymes of CSH-Px, SOD, GSH, and CAT have also been observed in diabetic mice. The antioxidant properties of compounds 1–5 are a promising strategy for ameliorating therapeutic effects by avoiding disorders in the normal redox reactions in healthy cells which consequently could alleviate complications of diabetes.
Variable-Angle Phase-Shifted PWM for Multilevel Three-Cell Cascaded H-bridge Converters
Multilevel cascaded H-bridge converters have become a mature technology for applications where high-power medium ac voltages are required. Normal operation of multilevel cascaded H-bridge converters assumes that all power cells have the same dc voltage, and each power cell generates the same voltage averaged over a sampling period using a conventional phase-shifted pulse width modulation (PWM) technique. However, this modulation method does not achieve good results under unbalanced operation per H-bridge in the power converter, which may happen in grid-connected applications such as photovoltaic or battery energy storage systems. In the paper, a simplified mathematical analysis of the phase-shifted PWM technique is presented. In addition, a modification of this conventional modulation method using variable shift angles between the power cells is introduced. This modification leads to the elimination of harmonic distortion of low-order harmonics due to the switching (triangular carrier frequency and its multiples) even under unbalanced operational conditions. The analysis is particularized for a three-cell cascaded H-bridge converter, and experimental results are presented to demonstrate the good performance of the proposed modulation method
Noncommutative effective LQC: A (pre-)inflationary dynamics investigation
We conduct a (pre-)inflationary dynamics study within the framework of a
simple noncommutative extension of effective loop quantum cosmology -- put
forward recently by the authors -- which preserves its key features (in
particular, the quantum bounce is maintained). A thorough investigation shows
that the (pre-)inflationary scenario associated to the chaotic quadratic
potential is in the overall the same as the one featured in standard loop
quantum cosmology (which reinforces the conclusion reached by the authors in a
preliminary analysis). Hence, this (pre-)inflationary scenario does not easily
distinguish between standard loop quantum cosmology and the aforementioned
noncommutative scheme. It is argued that a particular tuning of the
noncommutativity parameter could accommodate for subtle effects at the level of
primordial perturbations (the hybrid quantization framework being a tentative
route of analysis).Comment: 22 pages, 18 figures, 1 tabl
Automatic vehicle counting area creation based on vehicle deep learning detection and DBSCAN
Deep learning and high-performance computing have augmented and speed-up the scope of video-based vehicles' massive counting. The automatic vehicle counts result from the detection and tracking of the vehicles in certain areas or Regions of Interest (ROI). In this paper, we propose a technique to create a counting area with different traffic-flow directions based on YOLO and DBSCAN You Only Look Once version five (YOLOv5) and Density-Based Spatial Clustering of Applications with Noise (DBSCAN). We compare the performance of the method against the manually counted ground truth. The proposed method showed that it is possible to generate the ROIs (counting areas) according to the traffic flow using deep learning techniques with relatively good accuracy (less than 5 % error). These results are promising but we need to explore the limits of this method with more street-view configurations, time and other detection and tracking algorithms, and in an HPC environment.Peer ReviewedPostprint (author's final draft
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