RESUMO
The seismo-electrical coupling is critical to understand the mechanism of geoelectrical precursors to earthquakes. A novel seismo-electrical model, called Chen-Ouillon-Sornette (COS) model, has been developed by combining the Burridge-Knopoff spring-block system with the mechanisms of stress-activated charge carriers (i.e., electrons and holes) and pressure-stimulated currents. Such a model, thus, can simulate fracture-induced electrical signals at a laboratory scale or earthquake-related geoelectrical signals at a geological scale. In this study, by using information measures of time series analysis, we attempt to understand the influence of diverse electrical conditions on the characteristics of the simulated electrical signals with the COS model. We employ the Fisher-Shannon method to investigate the temporal dynamics of the COS model. The result showed that the electrical parameters of the COS model, particularly for the capacitance and inductance, affect the levels of the order/disorder in the electrical time series. Compared to the field observations, we infer that the underground electrical condition has become larger capacitance or smaller inductance in seismogenic processes. Accordingly, this study may provide a better understanding of the mechanical-electrical coupling of the earth's crust.
RESUMO
This study was undertaken to investigate the relationship between cerebrospinal fluid abnormalities and prognosis in pediatric refractory purulent meningitis. Ninety cases of pediatric refractory purulent meningitis were stratified into "good" (n=33) or "poor" (n=57) prognosis groups according to the Glasgow clinical outcome scores. The symptoms, laboratory results, and prognosis were compared by using univariate and multivariate logistic regression analyses. Univariate analysis showed that poor prognosis was associated with: unequal pupil size in both eyes; positive Babinski sign; CSF-WBC >500×106/L, CSF protein concentration >1.0g/L, CSF glucose content <1.5mmol/L; initial procalcitonin result >0.1ng/dL on admission; hemoglobin <90g/L during hospitalization; abnormal head imaging, and abnormal electroencephalogram. On multivariate analysis only unequal pupil size in both eyes and CSF glucose content <1.5mmol/L remained significant. The CSF protein concentration was significantly different between groups at discharge. The cutoff value was 0.68g/L. We recommend that discharged patients meet the following criteria: full antibiotic course and over 1 week of defervesce, disappearance of acute phase symptoms, CSF-WBC ≤28×106/L, CSF glucose >1.75mmol/L, and protein <0.68g/L. The patient may be discharged for follow-up if no relapse occurs during 3-5 days of observation after drug withdrawal.