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Cell-generated mechanical forces drive many cellular and tissue-level movements and rearrangements required for the tissue or organ to develop its shape. The prevalent view of tissue morphogenesis relies on epithelial folding resulting in compressed epithelial monolayers, overlooking the involvement of stroma in morphogenesis. Here, we report a giant web-like network formation of stromal cells in the epithelium-stroma interface, resulting from a multi-scale mechano-reciprocity between migrating cells and their extracellular environment. In multi-layered tissues, surface wrinkles form by a stromal cell-mediated tensional force exerted at the basement membrane. The topographical cue is transmitted to the stromal cell, directing its protrusion and migration along the wrinkles. This inductive movement of the cells conveys traction forces to its surrounding extracellular matrix, remodeling the local architectures of the stroma. In this manner, stromal cells and wrinkles communicate recursively to generate the cellular network. Our observation provides a rational mechanism for network formation in living tissues and a new understanding of the role of cellular-level tensional force in morphogenesis.

Background According to the recent coronavirus disease 2019 (COVID-19) pandemic experience, many emergency departments experience difficulties in responding to emerging infectious diseases and this has led to a public health crisis. Our emergency department (ED) is designed to respond to mass outbreaks of infection. Three major preparations were taken to respond to infectious disease; first, to improve the emergency department facilities; second, to created programs to respond to each phase of an epidemic of COVID-19; lastly, to implemented education and training to promote the safety of medical staff. We would like to share the actual responses and statistics of patients visiting emergency department during COVID-19 periods of pandemic. Materials and methods This research was conducted through a retrospective chart analysis provided by a public medical center with 502 beds since the first report of a COVID-19 confirmed case on January 19, 2020 to June 15, 2020 in Seoul, the capital of Korea. Our emergency department was designed based on Korean Regional Emergency Center Facility Standards, and modified throughout each phases of COVID-19 outbreak. Patients suspected to be infectious are screened in the triage, separating them from general patients, and then receive isolation treatment in isolated wards. Results A total of 4,352 patients visited the ED. 3,202 screenings were conducted with 5 confirmed cases. Another 1,150 patients were treated with general emergent symptoms. There were no problems such as closure of the emergency department or isolation of medical staff while managing COVID-19 confirmed patients. Conclusion Improving emergency department facilities, create an operational program to respond to each phase of COVID-19 outbreak and implement educational programs enabled large number of screening tests and hospitalization for COVID-19 suspected patients while maintaining general medical services. Research in emergency department designs and operational programs should increase to combine research data with better ideas to respond not only during regular periods but also during periods of pandemic.

Objective To investigate the effect of parental involvement in the manual reduction of pulled elbow in children. Methods We conducted a prospective case-control study from January to December 2018. The patients were under 6 years old with suspected radial head subluxation and were randomly assigned to two groups (an intervention group with a physician's and a parent's finger placed on the patient's radial head and a control group with the physician's finger only placed on the patient's radial head) according to the method of reduction. The results of a questionnaire given to the parent and physician were analyzed. Results A total of 150 patients were included in the study: 75 in the intervention group and 75 in the control group. There were no significant differences between the groups. The average number of attempts at manual reduction was 1.29 ± 0.73 in the intervention group and 1.31 ± 0.72 in the control group (P = 0.91) and the success rate of manual reduction was 96.0 and 94.7% (P = 0.70), respectively. The ease of conducting the procedure by the doctors did not show a significant difference between the two groups. However, the parents' understanding and satisfaction was significantly higher in the intervention group. Conclusion Parental involvement did not affect the procedure of physician, but it improved the understanding and satisfaction of the parents.

Background Bicycling is an increasingly popular recreation and mode of transportation in korea. Head injury is the leading cause of death and permanent disability in bicycle-related crashes. So, the bicycle helmet is crucial protective equipment for bicyclists. Aims This study aimed to measure the protective effects of bicycle helmet use on intracranial injury, in-hospital mortality and clinical important injury in bicycle-related crashes. Methods This is a cross-sessional study based on the Emergency Department(ED)-based Injury In-depth Surveillance(EDIIS) database from 23 EDs in Korea. All of injured bicyclists between January 1, 2011. and December 31, 2016. were eligible, excluding cases with unknown helmet use and outcomes. The primary outcome was intracranial injury and the secondary outcomes were in-hospital mortality and clinical important injury (admission or in-hospital death). We calculated adjusted odds ratios (AORs) of helmet use for study outcomes after adjusting for potential confounders. Results Among 24,306 eligible patients, 2,547(10.5%) patients were wearing helmets at the time of injury. 910(3.7%) patients had intracranial injuries, 198(0.8%) patients had in-hospital death and 3,745(15.4%) had clinical important injury. The helmeted group was less likely to have a injury in Head & Face(37.9% vs 47.1, p Discussion and conclusions Wearing helmets in bicycle-related crashes had a significant preventive effects to reduce intracranial injury, in-hospital mortality and clinical important injury. But the rate of wearing helmet was very low. Public health efforts to increase bicycle helmet use are needed to reduce health burden from Injuries caused by bicycle crashes.

Background Bicycling is an increasingly popular recreation and mode of transportation in korea. Improved understanding of sex and gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries could help to understand bicycle-related injuries and develop preventative strategies. Aims This study aimed to investigate sex and gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries. Methods This is a cross-sessional study based on the Emergency Department(ED)–based Injury In-depth Surveillance(EDIIS) database from 23 EDs in Korea. All of injured bicyclists between January 1, 2011. and December 31, 2016. were eligible, excluding cases with unknown outcomes. The primary outcome was intracranial injury and the secondary outcomes were in-hospital mortality and clinical important injury (admission or in-hospital death). We calculated adjusted odds ratios (AORs) of gender(male) for study outcomes after adjusting for potential confounders. Results Among 24 306 eligible patients, 19 286 (79.3%) patients were male and 5 020 (20.7%) were female. The rate of helmets use was no diferrence(10.6% in male and 10.2% in female, respectively). Bicycling injuries of male occurred more in child and adolescent, evening and night(all p Discussion and conclusions There were gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries. Bicycling injuries of male occurred more in child and adolescent and had more severe outcomes than female. Preventative strategies to reduce the bicycling injuries targeting male (esp, child and adolescent male) are needed.

This paper presents an intelligent IGBT module for a quasi-resonant converter, widely used topology in induction heating (IH) applications. The proposed module is composed of an IGBT and the integrated gate drive circuit which provides dedicated protective and control functions to IH applications: soft start during load detection, long turn-on prevention, hard turn-on disabling, retention of minimum turn-off duration, and overvoltage protection for the IGBT. Conventional functions of under and over supply voltage protection, over temperature protection, temperature monitoring, and fault indication are implemented as well. Hence, the proposed module enables easy and compact design of the converter improving robustness and reliability. The design consideration and performance of the proposed functions are described in detail. The module is evaluated in the practical IH cooker to show its effectiveness.

This paper presents the effect of dithering on both harmonics and interharmonics in adjustable speed drives (ASDs). Using a voltage source configuration, a six-pulse rectifier and a sinusoidal pulse width modulated (SPWM) inverter are modeled in the PSCAD/EMTDC simulation platform. The pulse width modulated (PWM) signal for the inverter is modified by means of the additive dither noise. The dither randomizes the timing of rising and falling edges of PWM signals, which eventually reduces periodic harmonics of the inverter output voltage. The reduced harmonics also affect the source voltage of the rectifier and ultimately reduce interharmonics. The mitigated harmonics and interharmonics in the ASD are quantified in conventional power spectrum. Furthermore, frequency coupling is also analyzed using cross bicoherence to investigate causes of interharmonics.

In this paper, we utilize joint time-frequency analysis to inspect frequency-varying currents at the grid connection of a variable speed wind turbine system. Through simulation experiments based on a PSCAD dynamic model, frequency-varying characteristics of the currents are investigated and compared with the wind speed. Of particular note is the appearance of nonharmonic frequencies when the wind speed drops below a certain critical value, which is potentially harmful to the grid power quality. A comparison method based on joint time-frequency analysis is also provided to estimate the onset wind speed corresponding to the appearance of the extraneous frequencies.

In this paper, we propose a novel condition monitoring method for adjustable speed drives (ASD) and ASD-driven motors. The key idea is to diagnose the status of the load side of an ASD from observations made at the source side. The use of a higher-order spectral metric, the cross bicoherence, is proposed for the detection and analysis of anomalies associated with nonlinear devices in ASD systems. In this paper, we apply our method to detect phase imbalance at the load side of an ASD. Our experimental results demonstrate that the proposed method provides a unique signature of phase imbalance for detection and classification of asymmetric impedance associated with the phase imbalance. Furthermore, the proposed method shows a more sensitive detection performance compared to the conventional imbalance measurement method, which enables early detection of potential faults.