| 1. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 2. |
- Liu, Dan, et al.
(författare)
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Nutraceutical potentials of algal ulvan for healthy aging
- 2022
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier. - 0141-8130 .- 1879-0003. ; 194, s. 422-434
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Forskningsöversikt (refereegranskat)abstract
- Several theories for aging are constantly put forth to explain the underlying mechanisms. Oxidative stress, DNA dysfunction, inflammation, and mitochondrial dysfunction, along with the release of cytochrome c are some of these theories. Diseases such as type 2 diabetes mellitus, intestinal dysfunction, cardiovascular diseases, hepatic injury, and even cancer develop with age and eventually cause death. Ulva polysaccharides, owing to their special structures and various functions, have emerged as desirable materials for keeping healthy. These polysaccharide structures are found to be closely related to the extraction methods, seaweed strains, and culture conditions. Ulvan is a promising bioactive substance, a potential functional food, which can regulate immune cells to augment inflammation, control the activity of aging-related genes, promote tumor senescence, enhance mitochondrial function, maintain liver balance, and protect the gut microbiome from inflammatory attacks. Given the desirable physiochemical and gelling properties of ulvan, it would serve to improve the quality and shelf-life of food.
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| 3. |
- Ouyang, Yuezhen, et al.
(författare)
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Cancer-fighting potentials of algal polysaccharides as nutraceuticals
- 2021
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Ingår i: Food Research International. - : Elsevier. - 0963-9969 .- 1873-7145. ; 147
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Tidskriftsartikel (refereegranskat)abstract
- Cancer has been listed as one of the world's five incurable diseases by the World Health Organization and causes tens of thousands of deaths every year. Unfortunately, anticancer agents either show limited efficacy or show serious side effects. The algae possess high nutritional value and their polysaccharides have a variety of biological activities, especially anti-cancer and immunomodulatory properties. Algal polysaccharides exert anticancer effects by inducing apoptosis, cell cycle arrest, anti-angiogenesis, and regulating intestinal flora and immune function. Algal polysaccharides can be combined with nanoparticles and other drugs to reduce the side effects caused by chemotherapy and increase the anticancer effects. This review shows the signal pathways related to the anti-cancer mechanisms of algal polysaccharides, including their influence on intestinal flora and immune regulation, the application of nanoparticles, and the effects on combination therapy and clinical trials of cancer treatments.
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| 4. |
- Shi, Tianyue, et al.
(författare)
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Efficient BiSAR PFA Wavefront Curvature Compensation for Arbitrary Radar Flight Trajectories
- 2023
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892. ; 61, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- The polar format algorithm (PFA) is a popular choice for general bistatic synthetic aperture radar (BiSAR) imaging due to its computational efficiency and adaptability to situations with complicated geometries or arbitrary flight trajectories. However, efficient and accurate compensation of 2-D residual phase errors induced by the wavefront curvature remains challenging when obtaining high-quality BiSAR PFA images. In this article, an analytical expression for the phase errors in the wavenumber domain is derived. With this, the inherent structural characteristics of the phase errors are formulated, where the 2-D phase errors can be reduced to 1-D phase errors for an optimal coordinate system. Moreover, the mapping relationship between distorted point targets in the optimal imaging coordinates and their actual point targets in the original imaging coordinates is investigated. By exploiting the structural characteristics and the mapping relationship, a highly efficient BiSAR PFA wavefront curvature compensation method is proposed. This allows a reduced-dimensional space-variant filter to be constructed to mitigate the 2-D defocusing effect without compromising the compensation accuracy, with the distortion correction being performed using interpolation. The proposed method significantly reduces the complexity required for residual 2-D phase error compensation while simplifying the distortion correction, resulting in notable robustness. The effectiveness of the method is demonstrated using point target and scene target simulations.
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| 5. |
- Shi, Tianyue, et al.
(författare)
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Extended PGA for Spotlight SAR-Filtered Backprojection Imagery
- 2022
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Ingår i: IEEE Geoscience and Remote Sensing Letters. - 1545-598X. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- The phase gradient autofocus (PGA) is a robust autofocusing approach that can efficiently refocus defocused synthetic aperture radar (SAR) imagery produced by frequency-domain algorithms. However, from a conventional viewpoint, PGA cannot be extended to refocus SAR imagery produced by time-domain algorithms, such as the filtered backprojection (FBP), as the spectrum of the FBP imagery is range ambiguous and azimuth space-variant. In this letter, a novel interpretation of FBP is presented, in which the spectrum structure of the FBP imagery is analyzed in detail. By incorporating the derived spectral information, an efficient spectrum preprocessing is proposed for spectrum restructuring. After this preprocessing, PGA is shown to be able to refocus defocused FBP imagery. The validity and feasibility of the proposed autofocusing approach are demonstrated using both simulated and experimental data.
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| 6. |
- Shi, Tianyue, et al.
(författare)
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Parametric Model-Based 2-D Autofocus Approach for General BiSAR Filtered Backprojection Imagery
- 2022
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Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892. ; 60
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Tidskriftsartikel (refereegranskat)abstract
- The filtered backprojection (FBP) algorithm is viewed as a preferred candidate for general bistatic synthetic aperture radar (BiSAR) imaging since it does not pose any restrictions on SAR configurations or flight paths. However, high-efficient autofocus methods such as phase gradient autofocus (PGA) or Mapdrift (MD) cannot be effectively integrated with the FBP algorithm due to the unknown properties of the BiSAR FBP imagery spectrum. In this article, a novel Fourier-based interpretation of the BiSAR FBP algorithm is presented. Based on the new viewpoint, spectral characteristics of the BiSAR FBP imagery in the wavenumber domain, including range spectral ambiguity, space-variant spectral support, and the structural 2-D phase error, are derived in detail. Using these characteristics, a computationally efficient 2-D autofocus approach is proposed. First, a preprocessing is performed to eliminate the range spectral ambiguity and to align the skewed spectrum support, which facilitates the following phase error estimation and correction. Then, an estimation of the 1-D azimuth phase error (APE) is applied by combining multiple estimation results from different subband data. Finally, the 2-D phase error is computed directly from the estimated APE by exploiting the derived analytical structure of the 2-D phase error, which is then applied to restore the BiSAR FBP image. The simulation results are presented to show the effectiveness of the proposed approach.
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| 7. |
- Xinhua, Liu, et al.
(författare)
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Improved Neural Network Control Approach for a Humanoid Arm
- 2019
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Ingår i: Journal of Dynamic Systems Measurement, and Control. - : ASME Press. - 0022-0434 .- 1528-9028. ; 141:10, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- This study extended the knowledge over the improvement of the control performance for a seven degrees-of-freedom (7DOF) humanoid arm. An improved adaptive Gaussian radius basic function neural network (RBFNN) approach was proposed to ensure the reliability and stability of the humanoid arm control. Considering model uncertainties, the established dynamic model for the humanoid arm was divided into a nominal model and an error model. The error model was approximated by the RBFNN learning to compensate the uncertainties. The contribution of this study mainly concentrates on employing fruit fly optimization algorithm (FOA) to optimize the basic width parameter of the RBFNN, which can enhance the capability of the error approximation speed. Additionally, the output weights of the neural network were adjusted using the Lyapunov stability theory to improve the robustness of the RBFN-based error model. The simulation and experiment results demonstrate that the proposed approach is able to optimize the system state with less tracking errors, regulate the uncertain nonlinear dynamic characteristics, and effectively reduce unexpected interferences.
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| 8. |
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| 9. |
- Zanchetti, Alberto, et al.
(författare)
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Blood pressure and low-density lipoprotein-cholesterol lowering for prevention of strokes and cognitive decline: a review of available trial evidence.
- 2014
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Ingår i: Journal of Hypertension. - 1473-5598. ; 32:9, s. 1741-1750
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Forskningsöversikt (refereegranskat)abstract
- It is well established by a large number of randomized controlled trials that lowering blood pressure (BP) and low-density lipoprotein cholesterol (LDL-C) by drugs are powerful means to reduce stroke incidence, but the optimal BP and LDL-C levels to be achieved are largely uncertain. Concerning BP targets, two hypotheses are being confronted: first, the lower the BP, the better the treatment outcome, and second, the hypothesis that too low BP values are accompanied by a lower benefit and even higher risk. It is also unknown whether BP lowering and LDL-C lowering have additive beneficial effects for the primary and secondary prevention of stroke, and whether these treatments can prevent cognitive decline after stroke.
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| 10. |
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