精神病临床高危(clinical high-risk for psychosis,CHR-P)人群的症状和功能发展存在异质性,澄清这个群体症状和功能的改变及联系,有利于精神病早期预防。元分析纳入54篇文献,探究CHR-P人群各维度临床症状和功能的纵向改变、基线症状对随访功能的预测作用、调节效应。结果发现,CHR-P人群轻微阳性症状、阴性症状、瓦解症状、情感症状、一般精神病理症状、整体功能和角色功能随时间显著改善,社会功能没有显著改善;基线阴性症状显著负向预测随访的整体功能、社会功能、角色功能,基线的瓦解症状、情感症状、一般精神病理症状与随访的整体功能显著负相关;受教育程度显著调节轻微阳性症状和阴性症状的纵向变化,年龄、轻微阳性症状亚组比例和短暂间歇性精神病性症状亚组比例显著调节情感症状的纵向变化。这揭示阴性症状改善少和社会功能损害是CHR-P人群的核心特征,提示未来可针对阴性症状研发干预措施,进而改善社会功能。
Two-level totem-pole power factor correction(PFC)converters in critical conduction mode(CRM)suffer from the wide regulation range of switching frequency.Besides,in highfrequency applications,the number of switching times increases,resulting in significant switching losses.To solve these issues,this paper proposes an improved modulation strategy for the single-phase three-level neutral-point-clamped(NPC)converter in CRM with PFC.By optimizing the discharging strategy and switching state sequence,the switching frequency and its variation range have been efficiently reduced.The detailed performance analysis is also presented regarding the switching frequency,the average switching times,and the effect of voltage gain.A 2 k W prototype is built to verify the effectiveness of the proposed modulation strategy and analysis results.Compared with the totem-pole PFC converter,the switching frequency regulation range of the three-level PFC converter is reduced by 36.48%and the average switching times is reduced by 45.10%.The experimental result also shows a 1.2%higher efficiency for the three-level PFC converter in the full load range.
Ning LiYujie CaoXiaokang LiuYan ZhangRuotong WangLin JiangXiao-Ping Zhang
