| 1. |
- Yaghootkar, Hanieh, et al.
(författare)
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Genetic Studies of Leptin Concentrations Implicate Leptin in the Regulation of Early Adiposity
- 2020
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 69:12, s. 2806-2818
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Tidskriftsartikel (refereegranskat)abstract
- Leptin influences food intake by informing the brain about the status of body fat stores. Rare LEP mutations associated with congenital leptin deficiency cause severe early-onset obesity that can be mitigated by administering leptin. However, the role of genetic regulation of leptin in polygenic obesity remains poorly understood. We performed an exome-based analysis in up to 57,232 individuals of diverse ancestries to identify genetic variants that influence adiposity-adjusted leptin concentrations. We identify five novel variants, including four missense variants, in LEP, ZNF800, KLHL31, and ACTL9, and one intergenic variant near KLF14. The missense variant Val94Met (rs17151919) in LEP was common in individuals of African ancestry only, and its association with lower leptin concentrations was specific to this ancestry (P = 2 × 10-16, n = 3,901). Using in vitro analyses, we show that the Met94 allele decreases leptin secretion. We also show that the Met94 allele is associated with higher BMI in young African-ancestry children but not in adults, suggesting that leptin regulates early adiposity.
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| 2. |
- Al-Shami, Qahtan, et al.
(författare)
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Efficient numerical simulations on the forest barrier for seismic wave attenuation: engineering safe constructions
- 2024
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Ingår i: Frontiers in Built Environment. - : Frontiers Media S.A.. - 2297-3362. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- This paper aims to elucidate the clear visibility of attenuating seismic waves (SWs) with forest trees as natural metamaterials known as forest metamaterials (FMs) arranged in a periodic pattern around the protected area. In analyzing the changeability of the FM models, five distinct cases of “metawall” configurations were considered. Numerical simulations were conducted to study the characteristics of bandgaps (BGs) and vibration modes for each model. The finite element method (FEM) was used to illustrate the generation of BGs in low frequency ranges. The commercial finite element code COMSOL Multiphysics 5.4a was adopted to carry out the numerical analysis, utilizing the sound cone method and the strain energy method. Wide BGs were generated for the Bragg scattering BGs and local resonance BGs owing to the gradual variations in tree height and the addition of a vertical load in the form of mass to simulate the tree foliage. The results were promising and confirmed the applicability of FEM based on the parametric design language ANSYS 17.2 software to apply the boundary conditions of the proposed models at frequencies below 100 Hz. The effects of the mechanical properties of the six layers of soil and the geometric parameters of FMs were studied intensively. Unit cell layouts and an engineered configuration for arranging FMs based on periodic theory to achieve significant results in controlling ground vibrations, which are valuable for protecting a large number of structures or an entire city, are recommended. Prior to construction, protecting a region and exerting control over FM characteristics are advantageous. The results exhibited the effect of the ‘trees’ upper portion (e.g., leaves, crown, and lateral bulky branches) and the gradual change in tree height on the width and position of BGs, which refers to the attenuation mechanism. Low frequency ranges of less than 100 Hz were particularly well suited for attenuating SWs with FMs. However, an engineering method for a safe city construction should be proposed on the basis of the arrangement of urban trees to allow for the shielding of SWs in specific frequency ranges.
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| 3. |
- Feng, Na, et al.
(författare)
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Predictive compensator based event-triggered model predictive control with nonlinear disturbance observer for unmanned surface vehicle under cyber-attacks
- 2022
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Ingår i: Ocean Engineering. - : Elsevier. - 0029-8018 .- 1873-5258. ; 259
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Tidskriftsartikel (refereegranskat)abstract
- The trajectory tracking problem of unmanned surface vehicles (USVs) with external disturbances and input constraints, under denial of service (DoS) is addressed in this paper. We propose a predictive compensator based event-triggered model predictive control with nonlinear disturbance observer (PC-ETMPC with NDO) strategy. A model predictive controller (MPC) based on a nominal USV model is combined with a nonlinear disturbance observer (NDO) to estimate and compensate external disturbances. A predictive compensator (PC) is used to compensate network attack signals, which reduces the adverse impact of cyber-attack on the system, and an event-triggered mechanism is used to save computational resources of the calculation of the MPC. The proposed strategy is feasible for implementation, and its stability is proved to ensure the stable operation of the system. Numerical simulations and comparison are performed to demonstrate the effectiveness and superiority of the proposed control strategy.
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| 4. |
- Ji, Cheng, et al.
(författare)
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Crystallography of low Z material at ultrahigh pressure : Case study on solid hydrogen
- 2020
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Ingår i: Matter and Radiation at Extremes. - : American Institute of Physics (AIP). - 2468-2047 .- 2468-080X. ; 5:3
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Tidskriftsartikel (refereegranskat)abstract
- Diamond anvil cell techniques have been improved to allow access to the multimegabar ultrahigh-pressure region for exploring novel phenomena in condensed matter. However, the only way to determine crystal structures of materials above 100 GPa, namely, X-ray diffraction (XRD), especially for low Z materials, remains nontrivial in the ultrahigh-pressure region, even with the availability of brilliant synchrotron X-ray sources. In this work, we perform a systematic study, choosing hydrogen (the lowest X-ray scatterer) as the subject, to understand how to better perform XRD measurements of low Z materials at multimegabar pressures. The techniques that we have developed have been proved to be effective in measuring the crystal structure of solid hydrogen up to 254 GPa at room temperature [C. Ji et al., Nature 573, 558–562 (2019)]. We present our discoveries and experiences with regard to several aspects of this work, namely, diamond anvil selection, sample configuration for ultrahigh-pressure XRD studies, XRD diagnostics for low Z materials, and related issues in data interpretation and pressure calibration. We believe that these methods can be readily extended to other low Z materials and can pave the way for studying the crystal structure of hydrogen at higher pressures, eventually testing structural models of metallic hydrogen.
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| 5. |
- Law, Andrew M. K., et al.
(författare)
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ALTEN: A High‐Fidelity Primary Tissue‐Engineering Platform to Assess Cellular Responses Ex Vivo
- 2022
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Ingår i: Advanced Science. - : John Wiley & Sons. - 2198-3844. ; 9:21
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Tidskriftsartikel (refereegranskat)abstract
- To fully investigate cellular responses to stimuli and perturbations within tissues, it is essential to replicate the complex molecular interactions within the local microenvironment of cellular niches. Here, the authors introduce Alginate-based tissue engineering (ALTEN), a biomimetic tissue platform that allows ex vivo analysis of explanted tissue biopsies. This method preserves the original characteristics of the source tissue's cellular milieu, allowing multiple and diverse cell types to be maintained over an extended period of time. As a result, ALTEN enables rapid and faithful characterization of perturbations across specific cell types within a tissue. Importantly, using single-cell genomics, this approach provides integrated cellular responses at the resolution of individual cells. ALTEN is a powerful tool for the analysis of cellular responses upon exposure to cytotoxic agents and immunomodulators. Additionally, ALTEN's scalability using automated microfluidic devices for tissue encapsulation and subsequent transport, to enable centralized high-throughput analysis of samples gathered by large-scale multicenter studies, is shown.
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| 6. |
- Zhang, Tengfei, et al.
(författare)
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A fault reconfiguration strategy based on adjustable space operator discrete state transition algorithm for ship microgrid system
- 2022
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Ingår i: Electric power systems research. - : Elsevier. - 0378-7796 .- 1873-2046. ; 205
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Tidskriftsartikel (refereegranskat)abstract
- As an independent power supply network, when the ship ring microgrid system (SRMS) fails or is damaged, the power-loss load can be reasonably distributed to other power sources through the control switch, thereby improving the reliability of the power grid. We consider the maximum power load, minimum switching action and generator efficiency as the reconfiguration goals. In order to complete the reconfiguration quickly, we present an optimization strategy based on an adjustable space operator (ASO) and the discrete state transition algorithm (DSTA), the ASODSTA. The main idea of DSTA is to use four spatial geometric operators to find the optimal solution. The optimization is completed by combining the operators with the sigmoid function, and an ASO is proposed as the variable of the sigmoid function. The spatial distribution of the candidate solutions is more widespread through the unification of the four operators. The introduction of the sigmoid function and the ASO improves the quality of the global optimal solution and shortens the running time of the algorithm. The simulation results show that the proposed method can solve the SRMS reconfiguration problem faster and more effectively by comparing with the algorithms EO, WOA, GWO and BPSO in the references.
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