Objective. The prevalence of symptoms associated with gastroesophageal reflux disease (GERD) in patients with abnormal results of pH monitoring has been investigated in adults and infants. A questionnaire suitable for...Objective. The prevalence of symptoms associated with gastroesophageal reflux disease (GERD) in patients with abnormal results of pH monitoring has been investigated in adults and infants. A questionnaire suitable for children between 7 and 16 years of age has been proposed, but this tool has so far not been validated. In the present study the items of the questionnaire are validated against results from an esophageal 24h study of pH. Material and methods. Ninety-nine children aged from 7 to 16 years referred from two outpatient clinics for suspected GERD completed the 7-point questionnaire regarding symptoms during the week prior to a pH study. The frequency of symptoms was investigated in patients with abnormal versus normal pH (reflux index >/< 5.0). A group of healthy children (n = 284) served as controls to estimate the frequency of symptoms in the normal population. Results. It was found that 37/99 (37%) of patients had an abnormal pH study result. Regurgitation/ vomiting yielded the best symptom discrimination, and was reported by 46%with abnormal versus 24%with normal pH-study results (p =0.029). A weighted score including the five best discriminating symptoms was positive in 75%versus 44%(OR 3.78, CI 1.52-9.37, p =0.006). In a comparison of children with abnormal pH studies and healthy controls, a correct diagnosis based on five symptoms could be obtained in 75%and 94%, respectively. Conclusions. A relatively weak association was found between reflux symptoms and a positive pH study in 7-16-year-old children referred for pH monitoring. Thus, the questionnaire is not a diagnostic tool, and its potential use is limited to epidemiological studies.展开更多
文摘Objective. The prevalence of symptoms associated with gastroesophageal reflux disease (GERD) in patients with abnormal results of pH monitoring has been investigated in adults and infants. A questionnaire suitable for children between 7 and 16 years of age has been proposed, but this tool has so far not been validated. In the present study the items of the questionnaire are validated against results from an esophageal 24h study of pH. Material and methods. Ninety-nine children aged from 7 to 16 years referred from two outpatient clinics for suspected GERD completed the 7-point questionnaire regarding symptoms during the week prior to a pH study. The frequency of symptoms was investigated in patients with abnormal versus normal pH (reflux index >/< 5.0). A group of healthy children (n = 284) served as controls to estimate the frequency of symptoms in the normal population. Results. It was found that 37/99 (37%) of patients had an abnormal pH study result. Regurgitation/ vomiting yielded the best symptom discrimination, and was reported by 46%with abnormal versus 24%with normal pH-study results (p =0.029). A weighted score including the five best discriminating symptoms was positive in 75%versus 44%(OR 3.78, CI 1.52-9.37, p =0.006). In a comparison of children with abnormal pH studies and healthy controls, a correct diagnosis based on five symptoms could be obtained in 75%and 94%, respectively. Conclusions. A relatively weak association was found between reflux symptoms and a positive pH study in 7-16-year-old children referred for pH monitoring. Thus, the questionnaire is not a diagnostic tool, and its potential use is limited to epidemiological studies.
文摘加权分数傅里叶变换(Weighted fractional Fourier transform,WFRFT)技术可以极大地改变信号的特性,使信号的统计特性多样化,从而有效地保障通信信息安全。为解决单参数WFRFT通信抗扫描能力不足的问题,以单参数WFRFT为切入点,深入研究单参数分数域的形成机理,分析其潜在的微观特征和暗特征,从而提出了一种基于跳转向量的隐性WFRFT通信方法(Implicit WFRFT communication method of jump vector,IWVJ)。利用调制阶数与星座图的关系,建立了跳变矩阵和跳变向量,并以此制定了控制规则。此外,通过跳变向量控制获得动态调制阶数,从而达到安全通信的目的。仿真结果表明,IWVJ方法对授权接收机具有较高的反变换解调相似度和较低的误码率,相比于具有普适扫描能力的非授权接收机性能更优。同时对解调阶数误差、基础调制阶数和跳转频率等参数的设置给出了适用的建议,使IWVJ方法能够更好地应用于通信系统,为具有抗干扰、抗截获和抗欺骗能力的保密通信提供技术依据。
