目的探讨糖尿病患者早期视网膜病变时视网膜功能的变化。方法对中心视力正常、眼底正常或为轻度非增生性糖尿病性视网膜病变的糖尿病患者分别行多焦视网膜电图(multifocal electroretinogram,mf- ERG)一、二阶kernel反应(first and seco...目的探讨糖尿病患者早期视网膜病变时视网膜功能的变化。方法对中心视力正常、眼底正常或为轻度非增生性糖尿病性视网膜病变的糖尿病患者分别行多焦视网膜电图(multifocal electroretinogram,mf- ERG)一、二阶kernel反应(first and second order kernel,FOK&SOK)检查。将结果正常同龄对照组比较。结果与对照组相比,糖尿病组1环(黄斑中心凹)的FOK P_1波振幅密度值降低,后极部30°视网膜总合反应的N_1、P_1波峰时延迟,差异有统计学意义(t=2.5492,P=0.0136；t=2.1124,P=0.0391和t=2.0241,P=0.0477)；糖尿病视网膜病变组1环(黄斑中心凹)的SOK P_1波振幅密度值降低,峰时延迟,后极部30°视网膜总合反应的P_1波振幅密度值降低,差异有统计学意义(t=2.7200,P=0.0086；t=2.5515,P=0.0136和t=2.7990,P=0.0070)。结论糖尿病眼中心视力尚正常时,由mf-ERG检得的黄斑中心凹和后极部视网膜功能已有异常；kernel反应异常表明早期糖尿病视网膜病变的内、外层视网膜功能均已受到损害,kernel反应的振幅和峰时是观察糖尿病视网膜病变的独立指标。展开更多
目的观察早期糖尿病患者视网膜功能。方法对视力正常、眼底正常或为轻度非增殖性糖尿病性视网膜病变的糖尿病患者共60眼行多焦视网膜电图二阶 kernel 反应(second order kernel,SOK)检查,将检查结果与36眼正常同龄对照组比较。结果与正...目的观察早期糖尿病患者视网膜功能。方法对视力正常、眼底正常或为轻度非增殖性糖尿病性视网膜病变的糖尿病患者共60眼行多焦视网膜电图二阶 kernel 反应(second order kernel,SOK)检查,将检查结果与36眼正常同龄对照组比较。结果与正常对照组相比,糖尿病组后极部视网膜 SOK 总合反应的 P_1波振幅密度值降低、峰时延迟,差异均有统计学意义(t=2.6000.P=0.0109和 t=2.3657,P=0.0201);与无糖尿病性视网膜病组相比,轻度糖尿病性视网膜病组后极部视网膜 SOK 总合反应的 P_1波峰时延迟,差异有统计学意义(t=2.5080,P=0.0150)。结论糖尿病患者中心视力尚正常时,由 SOK 检测到的内层视网膜功能已有异常;轻度糖尿病性视网膜病眼峰时异常更明显;SOK 可作为早期糖尿病性视网膜病变检测的指标。(中国眼耳鼻喉科杂志,2005,5:358～360)展开更多
We study support vector machines （SVM） for which the kernel matrix is not specified exactly and it is only known to belong to a given uncertainty set. We consider uncertainties that arise from two sources： （i） da...We study support vector machines （SVM） for which the kernel matrix is not specified exactly and it is only known to belong to a given uncertainty set. We consider uncertainties that arise from two sources： （i） data measurement uncertainty, which stems from the statistical errors of input samples; （ii） kernel combination uncertainty, which stems from the weight of individual kernel that needs to be optimized in multiple kernel learning （MKL） problem. Much work has been studied, such as uncertainty sets that allow the corresponding SVMs to be reformulated as semi-definite programs （SDPs）, which is very computationally expensive however. Our focus in this paper is to identify uncertainty sets that allow the corresponding SVMs to be reformulated as second-order cone programs （SOCPs）, since both the worst case complexity and practical computational effort required to solve SOCPs is at least an order of magnitude less than that needed to solve SDPs of comparable size. In the main part of the paper we propose four uncertainty sets that meet this criterion. Experimental results are presented to confirm the validity of these SOCP reformulations.展开更多
文摘目的探讨糖尿病患者早期视网膜病变时视网膜功能的变化。方法对中心视力正常、眼底正常或为轻度非增生性糖尿病性视网膜病变的糖尿病患者分别行多焦视网膜电图(multifocal electroretinogram,mf- ERG)一、二阶kernel反应(first and second order kernel,FOK&SOK)检查。将结果正常同龄对照组比较。结果与对照组相比,糖尿病组1环(黄斑中心凹)的FOK P_1波振幅密度值降低,后极部30°视网膜总合反应的N_1、P_1波峰时延迟,差异有统计学意义(t=2.5492,P=0.0136；t=2.1124,P=0.0391和t=2.0241,P=0.0477)；糖尿病视网膜病变组1环(黄斑中心凹)的SOK P_1波振幅密度值降低,峰时延迟,后极部30°视网膜总合反应的P_1波振幅密度值降低,差异有统计学意义(t=2.7200,P=0.0086；t=2.5515,P=0.0136和t=2.7990,P=0.0070)。结论糖尿病眼中心视力尚正常时,由mf-ERG检得的黄斑中心凹和后极部视网膜功能已有异常；kernel反应异常表明早期糖尿病视网膜病变的内、外层视网膜功能均已受到损害,kernel反应的振幅和峰时是观察糖尿病视网膜病变的独立指标。
文摘目的观察早期糖尿病患者视网膜功能。方法对视力正常、眼底正常或为轻度非增殖性糖尿病性视网膜病变的糖尿病患者共60眼行多焦视网膜电图二阶 kernel 反应(second order kernel,SOK)检查,将检查结果与36眼正常同龄对照组比较。结果与正常对照组相比,糖尿病组后极部视网膜 SOK 总合反应的 P_1波振幅密度值降低、峰时延迟,差异均有统计学意义(t=2.6000.P=0.0109和 t=2.3657,P=0.0201);与无糖尿病性视网膜病组相比,轻度糖尿病性视网膜病组后极部视网膜 SOK 总合反应的 P_1波峰时延迟,差异有统计学意义(t=2.5080,P=0.0150)。结论糖尿病患者中心视力尚正常时,由 SOK 检测到的内层视网膜功能已有异常;轻度糖尿病性视网膜病眼峰时异常更明显;SOK 可作为早期糖尿病性视网膜病变检测的指标。(中国眼耳鼻喉科杂志,2005,5:358～360)
基金supported in part by the National Natural Science Foundation of China under Grant No.60678049Natural Science Foundation of Tianjin under Grant No.07JCYBJC14600
文摘We study support vector machines （SVM） for which the kernel matrix is not specified exactly and it is only known to belong to a given uncertainty set. We consider uncertainties that arise from two sources： （i） data measurement uncertainty, which stems from the statistical errors of input samples; （ii） kernel combination uncertainty, which stems from the weight of individual kernel that needs to be optimized in multiple kernel learning （MKL） problem. Much work has been studied, such as uncertainty sets that allow the corresponding SVMs to be reformulated as semi-definite programs （SDPs）, which is very computationally expensive however. Our focus in this paper is to identify uncertainty sets that allow the corresponding SVMs to be reformulated as second-order cone programs （SOCPs）, since both the worst case complexity and practical computational effort required to solve SOCPs is at least an order of magnitude less than that needed to solve SDPs of comparable size. In the main part of the paper we propose four uncertainty sets that meet this criterion. Experimental results are presented to confirm the validity of these SOCP reformulations.
