RESUMO
The Sichuan-Yunnan region is one of the most seismically vulnerable areas in China. Accordingly, an earthquake early warning (EEW) system for the region is essential to reduce future earthquake hazards. This research analyses the utility of two early warning parameters (τc and Pd) for magnitude estimation using 273 events that occurred in the Sichuan-Yunnan region during 2007-2015. We find that τc can more reliably predict high-magnitude events during a short P-wave time window (PTW) but produces greater uncertainty in the low-magnitude range, whereas Pd is highly correlated with the event magnitude depending on the selection of an appropriate PTW. Here, we propose a threshold-based evolutionary magnitude estimation method based on a specific combination of τc and Pd that both offers more robust advance magnitude estimates for large earthquakes and ensures the estimation accuracy for low-magnitude events. The advantages of the proposed approach are validated using data from 2016-2017 and the Ms 8.0 Wenchuan earthquake in an offline simulation. The proposed concept provides a useful basis for the future implementation of an EEW system in the Sichuan-Yunnan region.
RESUMO
OBJECTIVE: To observe the curative effects of platelet-rich plasma (PRP) combined with negative-pressure wound therapy (NPWT) on patients with sternal osteomyelitis and sinus tract after thoracotomy. METHODS: Sixty-two patients with sternal osteomyelitis and sinus tract after thoracotomy, hospitalized from March 2011 to June 2015, were retrospectively analyzed. Based on whether receiving PRP or not, patients were divided into two groups, group NPWT ( 22 patients hospitalized from March 2011 to December 2012) and combination treatment group (CT, 40 patients hospitalized from January 2013 to June 2015). After debridement, patients in group NPWT were treated with continuous NPWT (negative pressure values from -15.96 to -13.30 kPa), while those in group CT were treated with PRP gel (blood platelet counts in PRP ranged from 1 450×10(9)/L to 1 800×10(9)/L, with 10-15 mL in each dosage) made on the surgery day to fill the sinus tract and wound, followed by NPWT. Negative pressure materials were changed every 5 days until 20 days after surgery in patients of both groups. PRP gel was replenished before changing of negative pressure materials in patients of group CT. The sinus tract sealing time, wound healing time, number of patients who had secondary repair surgery, number of patients who had recurrence of sinus tract within three months after wound healing, and length of hospital stay were recorded. Data were processed with t test, Fisher's exact test, and chi-square test. RESULTS: The sinus tract sealing time, wound healing time, and length of hospital stay in patients of group CT were (16±8), (27±13), and (43±13) d respectively, which were all significantly shorter than those in group NPWT [(29±14), (41±17), and (60±20) d, with t values from 3.88 to 4.67, P values below 0.01]. The number of patients who had secondary repair surgery in group CT was less than that in group NPWT (P<0.01). There was no statistically significant difference in the number of patients who had recurrence of sinus tract between two groups (P>0.05). CONCLUSIONS: Compared with NPWT only, PRP combined with NPWT has great curative effects on patients with sternal osteomyelitis and sinus tract after thoracotomy, for it shortens sinus tract sealing time, wound healing time, and length of hospital stay, and avoids the secondary repair surgery. This method is simple and safe with little injury.