scholarly journals Sensitive detection of cell-derived force and collagen matrix tension in microtissues undergoing large-scale densification

2021 ◽  
Vol 118 (36) ◽  
pp. e2106061118
Author(s):  
Xiang Wang ◽  
Qiang Gao ◽  
Xiaoning Han ◽  
Bing Bu ◽  
Longfei Wang ◽  
...  

Mechanical forces generated by cells and the tension of the extracellular matrix (ECM) play a decisive role in establishment, homeostasis maintenance, and repair of tissue morphology. However, the dynamic change of cell-derived force during large-scale remodeling of soft tissue is still unknown, mainly because the current techniques of force detection usually produce a nonnegligible and interfering feedback force on the cells during measurement. Here, we developed a method to fabricate highly stretchable polymer-based microstrings on which a microtissue of fibroblasts in collagen was cultured and allowed to contract to mimic the densification of soft tissue. Taking advantage of the low-spring constant and large deflection range of the microstrings, we detected a strain-induced contraction force as low as 5.2 µN without disturbing the irreversible densification. Meanwhile, the microtissues displayed extreme sensitivity to the mechanical boundary within a narrow range of tensile stress. More importantly, results indicated that the cell-derived force did not solely increase with increased ECM stiffness as previous studies suggested. Indeed, the cell-derived force and collagen tension exchanged dramatically in dominating the microtissue strain during the densification, and the proportion of cell-derived force decreased linearly as the microtissue densified, with stiffness increasing to ∼500 Pa. Thus, this study provides insights into the biomechanical cross-talk between the cells and ECM of extremely soft tissue during large-extent densification, which may be important to guide the construction of life-like tissue by applying appropriate mechanical boundary conditions.

2021 ◽  
Vol 13 (15) ◽  
pp. 3044
Author(s):  
Mingjie Liao ◽  
Rui Zhang ◽  
Jichao Lv ◽  
Bin Yu ◽  
Jiatai Pang ◽  
...  

In recent years, many cities in the Chinese loess plateau (especially in Shanxi province) have encountered ground subsidence problems due to the construction of underground projects and the exploitation of underground resources. With the completion of the world’s largest geotechnical project, called “mountain excavation and city construction,” in a collapsible loess area, the Yan’an city also appeared to have uneven ground subsidence. To obtain the spatial distribution characteristics and the time-series evolution trend of the subsidence, we selected Yan’an New District (YAND) as the specific study area and presented an improved time-series InSAR (TS-InSAR) method for experimental research. Based on 89 Sentinel-1A images collected between December 2017 to December 2020, we conducted comprehensive research and analysis on the spatial and temporal evolution of surface subsidence in YAND. The monitoring results showed that the YAND is relatively stable in general, with deformation rates mainly in the range of −10 to 10 mm/yr. However, three significant subsidence funnels existed in the fill area, with a maximum subsidence rate of 100 mm/yr. From 2017 to 2020, the subsidence funnels enlarged, and their subsidence rates accelerated. Further analysis proved that the main factors induced the severe ground subsidence in the study area, including the compressibility and collapsibility of loess, rapid urban construction, geological environment change, traffic circulation load, and dynamic change of groundwater. The experimental results indicated that the improved TS-InSAR method is adaptive to monitoring uneven subsidence of deep loess area. Moreover, related data and information would provide reference to the large-scale ground deformation monitoring and in similar loess areas.


1993 ◽  
Vol 5 (4) ◽  
pp. 203-212 ◽  
Author(s):  
Roger A Fay ◽  
David A Ellwood

Originally all low birthweight infants were considered to be premature. When prematurity was redefined in terms of gestational age (SGA) and not preterm. With the large scale collection of obstetric data the distributions of birthweight at different gestational ages were described and from these, infants who were SGA could be defined. SGA became synonymous with terms such as growth retardation, but it soon became appearent that the two were not necessarily interchangeable. Scott and Usher found that it was the degree of soft tissue wasting rather than birthweight that related to poor perinatal outcome. Miller and Hassanein stated that: “birthweight by itself is not a valid measure of fetal growth impairment”. They used Rorher’s Ponderal Index (weight (g) × 100/length (cm)) to diagnose the malnourished or excessively wasted infants with reduced soft tissue mass. Most studies of intrauterine growth retardation (IUGR) still use low birthweight for gestational age centile as their only definition of IUGR or only study infants who have a low birthweight. Altman and Hytten expressed disquiet about this definition and stated: “There is now an urgent need to establish true measures of fetal growth from which deviations indicating genuine growth retardation can be derived” and that “it is particularly important that some reliable measures of outcome should be established”. In large series of term deliveries published recently, two groups of IUGR infants with different growth patterens have been identified. These studies confirm that birthweight alone is inadequate to define the different types of IUGR. They established that low Ponderal Index (PI) is a measure of IUGR associated with an increased incidence of perinatal problems and that it is time to re-evaluate IUGR in terms of the different types of aberrant fetal growth.


2016 ◽  
Vol 113 (17) ◽  
pp. 4688-4693 ◽  
Author(s):  
H. Clark Barrett ◽  
Alexander Bolyanatz ◽  
Alyssa N. Crittenden ◽  
Daniel M. T. Fessler ◽  
Simon Fitzpatrick ◽  
...  

Intent and mitigating circumstances play a central role in moral and legal assessments in large-scale industrialized societies. Although these features of moral assessment are widely assumed to be universal, to date, they have only been studied in a narrow range of societies. We show that there is substantial cross-cultural variation among eight traditional small-scale societies (ranging from hunter-gatherer to pastoralist to horticulturalist) and two Western societies (one urban, one rural) in the extent to which intent and mitigating circumstances influence moral judgments. Although participants in all societies took such factors into account to some degree, they did so to very different extents, varying in both the types of considerations taken into account and the types of violations to which such considerations were applied. The particular patterns of assessment characteristic of large-scale industrialized societies may thus reflect relatively recently culturally evolved norms rather than inherent features of human moral judgment.


Author(s):  
Xiaomeng Dong ◽  
Zhijian Zhang ◽  
Zhaofei Tian ◽  
Lei Li ◽  
Guangliang Chen

Multi-physics coupling analysis is one of the most important fields among the analysis of nuclear power plant. The basis of multi-physics coupling is the coupling between neutronics and thermal-hydraulic because it plays a decisive role in the computation of reactor power, outlet temperature of the reactor core and pressure of vessel, which determines the economy and security of the nuclear power plant. This paper develops a coupling method which uses OPENFOAM and the REMARK code. OPENFOAM is a 3-dimension CFD open-source code for thermal-hydraulic, and the REMARK code (produced by GSE Systems) is a real-time simulation multi-group core model for neutronics while it solves diffusion equations. Additionally, a coupled computation using these two codes is new and has not been done. The method is tested and verified using data of the QINSHAN Phase II typical nuclear reactor which will have 16 × 121 elements. The coupled code has been modified to adapt unlimited CPUs after parallelization. With the further development and additional testing, this coupling method has the potential to extend to a more large-scale and accurate computation.


2014 ◽  
Vol 519-520 ◽  
pp. 911-918
Author(s):  
Xin Min Ma ◽  
Xu Qian ◽  
Wen Chao Gao

Force-directed placement method for large scale integration physical design is a very effective and fast method to spread the cell uniformly in the placement region. But this kind of method also create large amount of cell overlap in initial placement. In this paper, we present an effective method to cope with cell spreading and add additional force without damaging the wire length. It mainly takes the following method: Firstly, in the prior period of iteration n we keep limit the cell moving distance using a rectangle structure .Because the prior iteration play a decisive role in the final placement quality. Secondly, after the cell relative order determined we can use a new method to compute the weight of additional force to accelerate converge. Thirdly, a strategy called iterative local refinement is added in the well-distributed placement to further reduce the total wire length.


2019 ◽  
Vol 50 (2) ◽  
pp. 415-428 ◽  
Author(s):  
Ken Quarrie ◽  
Simon Gianotti ◽  
Ian Murphy

Abstract Objectives The Accident Compensation Corporation is a compulsory, 24-h, no-fault personal injury insurance scheme in New Zealand. The purpose of this large-scale retrospective cohort study was to use Accident Compensation Corporation records to provide information about rugby injury epidemiology in New Zealand, with a focus on describing differences in risk by age and gender. Methods A total of 635,657 rugby injury claims were made to the Accident Compensation Corporation for players aged 5–40 years over the period 2005–2017. Information about player numbers and estimates of player exposure was obtained from New Zealand Rugby, the administrative organisation for rugby in New Zealand. Results Over three quarters of claims (76%) were for soft-tissue injuries, with 11% resulting from fractures or dislocations, 6.7% from lacerations, 3.1% from concussions and 2.0% from dental injuries. Body regions injured included shoulder (14%), knee (14%), wrist/hand (13%), neck/spine (13%), head/face (12%), leg (11%) and ankle (10%). The probability of a player making at least one injury claim in a season (expressed as a percentage) was calculated under the assumption that the incidence of claims follows a Poisson distribution. Players aged 5–6 years had a probability of making at least one claim per season of 1.0%, compared to 8.3% for players aged 7–12 years, 35% for age 13–17 years, 53% for age 18–20 years, 57% for age 21–30 years and 47% for age 31–40 years. The overall probability of making at least one claim per season across all age groups was 29%. The relative claim rate for adults (players aged 18 years and over) was 3.92 (90% confidence interval 3.90–3.94) times that of children. Ten percent of players were female, and they sustained 6% of the injuries. Overall, the relative claim rate for female players was 0.57 times that of male players (90% confidence interval 0.56–0.58). The relative claim rate of female to male players tended to increase with age. There were very few female players aged over 30 years; however, those who did play had higher claim rates than male players of the same age group (1.49; 90% confidence interval 1.45–1.53). Conclusions Injuries resulting from rugby are distributed across the body, and most of the claims are for soft-tissue injuries. Rates of injury increase rapidly through the teenage years until the early 20 s; for male players they then decrease until the mid-30 s. For female players, the injury rate does not decrease as players move into their 30 s. Combining Accident Compensation Corporation injury claim data with national player registration data provides useful information about the risks faced by New Zealand’s community rugby players, and the insights derived are used in the development of rugby injury prevention programme content.


Sign in / Sign up

Export Citation Format

Share Document