20 research outputs found

    An Approach to Study Groundwater Flow Field Evolution Time Scale Effects and Mechanisms

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    The temporal scale effect is an important issue for groundwater system evolution research. The selection of an appropriate time scale will enhance the understanding of the characteristics and mechanisms of groundwater flow field evolution. In this study, a methodology was provided to analyze the groundwater system evolution, focusing on the choice of the suitable time step for identifying the distinct stages of evolution, characterized by different behavior linked to the management of the groundwater system. The evolution trend of the groundwater level in the center of the cone of depression at different time scales, combined with the F test and the groundwater system balance index (Re) categories, were used for the choice of the time step and the division of the evolution stages. Based on the transformed groundwater level time series using the selected best time step, the main factors controlling the groundwater evolution were assessed for the different stages. Our results show that the methodology can exactly identify the different important stages of the evolution, and they can be used to individually study these stages, which can help to reveal the mechanisms of the groundwater evolution more easily. Therefore, it is useful to obtain an increased knowledge of the regional groundwater dynamics

    Efficacy of an Omaha system-based remote ergonomic intervention program on self-reported work-related musculoskeletal disorders (WMSDs) — A randomized controlled study

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    Purpose: Heavy biomechanical loadings at workplaces may lead to high risks of work-related musculoskeletal disorders. This study aimed to explore the efficacy of an Omaha System-based remote ergonomic intervention program on self-reported work-related musculoskeletal disorders among frontline nurses. Materials and methods: From July to October 2020, 94 nurses with self-reported pain in one of the three body parts, i.e., neck, shoulder, and low back, were selected and were randomly divided into two groups. The intervention group received a newly developed remote program, where the control group received general information and guidance on health and life. Program outcome was evaluated by a quick exposure check approach. Results: After 6 weeks, the intervention group exhibited significantly less stress in the low back, neck, and shoulder/forearms, compared to the control group (p < 0.05). In addition, the occurrence of awkward postures, such as extreme trunk flexion or twisting, was also significantly reduced (p < 0.05). Conclusions: The newly developed Omaha System-based remote intervention program may be a valid alternative to traditional programs for frontline nurses during the COVID-19 pandemic, reducing biomechanical loadings and awkward postures during daily nursing operations

    Dynamic equivalent magnetic network model and drive system of permanent magnet synchronous motor with double V-shaped magnet structure

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    In order to improve the driving performance of electric vehicles (EV), a permanent magnet synchronous motor with double V-shaped magnet structure (DVMPMSM) and its driving system are studied in this paper. A 150kW DVMPMSM for EV is designed firstly, and the design parameters of the motor are determined. In order to overcome the drawbacks of the finite element analysis (FEA), especially the issue on calculating time, a dynamic equivalent magnetic network (EMN) model of the DVMPMSM is constructed, by which the air gap flux density, back electromotive force, electromagnetic torque and winding inductance parameters of the motor can be solved. Compared with the FEA, the dynamic EMN model constructed in this paper greatly increases the calculation speed while the calculation accuracy is maintained well. This paper also introduces the stator winding switching method to replace the field-weakening control method. Then, a vector control method of DVMPMSM based on dynamic EMN model and stator winding switching is proposed. The demands brought forward by EV for high torque output under low speed and high upper limit of speed can be well satisfied. Finally, the accuracy of the dynamic EMN model and the effectiveness of the proposed control method is validated through prototype experiments

    Assessing the groundwater deficit for agriculture requirements under precipitation change while achieving food and water security in the North China Plain

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    Groundwater resources are closely related to climate change. Evaluating the groundwater deficit and its variation characteristics under climate change is necessary to understand the risk associated with enhanced groundwater recovery solutions and to provide supporting information for choosing the best technology and risk-reducing measures to implement. In this study, by using the CROPWAT model and copula theory, (1) we developed a groundwater deficit index (Gsci) for agricultural requirements that assesses the risk to groundwater resources imposed by precipitation changes on the North China Plain (NCP), and the four grades of Gsci were high deficit, moderate deficit, low deficit, and no deficit. (2) We estimated Gsci on the NCP for the period 1971–2020 by applying the climatic, soil, crop phenological, and hydrogeology data to the developed index. (3) The occurrence probability of each Gsci grade was evaluated. In the years with abundant precipitation, the occurrence probabilities of no-deficit events were 1, 0, 0, 0, 0.36, 0.56, and 0 on the Yanshan Plain, Taihang-Hebei Plain, Taihang-Henan Plain, Central-Hebei Plain, Central-Shandong Plain, Central-Henan Plain, and Coastal Plain, respectively. (4) The effective precipitation threshold for the occurrence of each Gsci grade was calculated, and the effective precipitation thresholds for the occurrence of no-deficit events were 495 mm, 595 mm, 525 mm, 400 mm, 455 mm, and 555 mm on the Taihang-Hebei Plain, Taihang-Henan Plain, Central-Hebei Plain, Central-Henan Plain, Central-Shandong Plain, and Coastal Plain, respectively. Our findings are useful for assessing the impacts of precipitation changes on groundwater resources and provide a further basis for the design of groundwater resource management strategies with respect to climate change, especially in water‐limited arid agricultural regions

    p53 promotes peroxisomal fatty acid beta-oxidation to repress purine biosynthesis and mediate tumor suppression

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    The metabolic pathways through which p53 functions as a potent tumor suppressor are incompletely understood. Here we report that, by associating with the Vitamin D receptor (VDR), p53 induces numerous genes encoding enzymes for peroxisomal fatty acid β-oxidation (FAO). This leads to increased cytosolic acetyl-CoA levels and acetylation of the enzyme 5-Aminoimidazole-4-Carboxamide Ribonucleotide Formyltransferase/IMP Cyclohydrolase (ATIC), which catalyzes the last two steps in the purine biosynthetic pathway. This acetylation step, mediated by lysine acetyltransferase 2B (KAT2B), occurs at ATIC Lys 266, dramatically inhibits ATIC activity, and inversely correlates with colorectal cancer (CRC) tumor growth in vitro and in vivo, and acetylation of ATIC is downregulated in human CRC samples. p53-deficient CRCs with high levels of ATIC is more susceptible to ATIC inhibition. Collectively, these findings link p53 to peroxisomal FAO, purine biosynthesis, and CRC pathogenesis in a manner that is regulated by the levels of ATIC acetylation
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