Influence of Blood Compressibility on Pulse Wave Propagation Properties Based on Elastic Thin-Walled Tube Theory

Pulse wave carries abundant physiological and pathological data about the human body. Understanding the effect of blood compressibility on the transmission qualities of pulse waves is necessary to detect, cure, and prevent cardiovascular problems. In this research, the fluid–solid coupling finite element analysis model of artery system was developed using COMSOL MultiPhysics software. The influence of blood compressibility on pulse wave propagation properties in the brachial artery was investigated using the blood volume compression modulus. Results show that the influence of blood compressibility on pulse wave propagation is relatively weak and may be ignored when evaluating the compressibility of blood and that the volume compression modulus swings 2GPa over and beyond the typical range of the human body. The influence of blood compressibility on the peak value of pressure pulse wave is minor. The attenuation amplitude of the peak value of a pulse wave is bigger for the case with compressible blood than those of case with incompressible blood, and the difference between compressible and incompressible models is less than 1%. But blood compressibility has a clear impact on pulse wave velocity. It is found that the pulse wave velocity is greater than that of blood flow velocity. These findings will be valuable to investigate deeply for evaluating pressure and velocity pulse waves, as well as in providing a waveform-based preliminary diagnosis of symptoms in human body

Benefits of prompting students to generate summaries during pauses in segmented multimedia lessons

Background: How to improve learning with online multimedia lessons has attracted widespread concern. Prior studies have attempted to help students learn by breaking a video lesson into several segments. However, there has been a debate about whether learners can use pause time effectively and whether prompting them to engage in different types of generative learning activities during pauses can better facilitate learning. Objectives: This study aimed to explore how to maximize learning by asking students to engage in generative processing activities during pauses in segmented narrated video lessons. Methods: Three experiments explored the effectiveness of segmenting, and whether adding summaries between segments can improve learning performance. In Experiment 1, participants were asked to view a segmented video or a continuous video. In Experiment 2, we examined whether adding summarizing activities during pauses can improve the effects of segmenting. In Experiment 3, we further investigated the effects of adding different types of summarizing activities during pauses. Results and Conclusions: In Experiment 1, segmenting improved performance on retention tests, but not on transfer tests. In Experiment 2, the effects of segmenting on the retention and transfer tests were enhanced when learners were asked to produce written summaries during the pauses. In Experiment 3, asking participants to imagine or write summaries during the pauses in segmented lessons improved retention and transfer test performance, but providing a summary only helped on retention. Takeaways: Adding generative learning activities (i.e., summarizing) during pauses prompted learners to learn the material more deeply. Results are consistent with the ICAP framework and the cognitive theory of multimedia learning

Operating flow of live operation of transmission line with series of special tools

In view of the current characteristics of live operation of transmission lines and the problems of the use of series of special appliances without stipulations, etc. In this paper, the operation flow of live operation of transmission line using a series of special tools is presented.This article elaborates the operation process from seven aspects: scope of application, operation method, labor combination, operation process, safety measures, dangerous points, control measures and necessary tools.It solves a series of problems in carrying out live operation of transmission lines with a series of special tools

Development and Application of Live Replacement of Insulator Suspension Tool Components for Transmission Lines

Transmission line insulators will reduce the insulation level and become low-value insulators because of lightning flashover. Toughened glass insulators are used in 500kV Tongfeng 1 and 2 lines in Tonghua area. Most umbrella skirts will break and fall off after lightning flashover, which greatly reduces the insulation performance. It needs to be replaced in time, but frequent blackouts will bring great losses and reduce the reliability of power supply. Aiming at the frequent lightning hazards and lightning strikes on transmission lines in Tonghua area, a tool assembly for live replacement of insulators for transmission lines is developed. Through the application of this tool, the live operation mode is adopted to eliminate such defects. The operation time can be arranged and implemented in a very timely manner, which avoids the threat of long-term defects, effectively reduces the outage time of equipment, enhances the stability of power grid, and greatly improves the reliability of power supply of lines. Finally, taking the live line insulator suspension tool as an example, the economic benefit analysis is given, and the feasibility and correctness of the tool are verified.

A novel animal model for bone metastasis in human lung cancer.

Metastases account for 90% of lung cancer mortalities, frequently target the skeleton and lead to rapid deterioration in quality of life. The molecular mechanism underlying bone metastases is largely unknown. Development of xenograft mouse models, such as the severe combined immunodeficient (SCID) CB-17 mouse and the non-obese diabetic (NOD)/SCID mouse, both of which lack functional B- and T-cells and are able to host allogeneic or xenogeneic tumor cells, has made great contributions in this area. However, residual natural killer (NK) cells in these models are able to significantly modify local tumor growth and metastasis. Treatment with anti-murine IL-2 receptor β chain Ab (TM-β1) antibody can abrogate NK cell activity in vivo; however, the antibody treatment may result in unexpected effects and the stability is hard to control. To overcome these shortcomings, we evaluated xenografts in NOD-scid IL2Rγ(null) immunodeficient mice that lacked mature T cells, B cells and functional NK cells. We compared the target tissue distribution of the human small cell lung cancer cell lines SBC-5 and SBC-3. Gross necropsy and whole skeletal X-ray film examination of the host mice were conducted 30 days post-tail vein injection. The SBC-5 cells colonized bone and formed lytic lesions. The cells also colonized liver, spleen and, less frequently, the pancreas, ovary and kidney. The SBC-3 cell xenografts formed easily visible tumor foci in the liver, pancreas, ovary/uterus and kidney, but not bone metastases. Our results showed that SBC-5 cells in NOD-scid IL2Rγ(null) immunodeficient mice provide a suitable xenograft model system for bone metastasis of human lung cancer. This novel animal model may therefore be used to study the molecular pathway of bone metastases and to evaluate targets for effective therapies