Vegetation,herbivores and fires in savanna ecosystems: A network perspective

The dynamics of savanna ecosystems depends on the interplay between multiple factors such as grazing, browsing, fires, rainfall regime and interactions between grass and woody vegetation. In most modelling applications this interplay may not be fully understood because some of these drivers enter the models as dynamically independent factors. In this paper we consider such factors as dynamic variables. To analyze their interplay we focus on the structure of the interactive network of variables and exploit the properties of signed digraphs using the algorithm of Loop Analysis. Qualitative signed digraphs for the savanna ecosystem are developed and their predictions used to interpret patterns of abundance observed in case studies selected from the literature. The outcomes of this exercise unveil that: 1) the structure of the interactions is appropriate locus for the explanation of patterns observed in savannas; 2) signed digraph can help disentangling causative mechanisms by linking correlation patterns, source of change and network structure. This study highlights that central to the understanding of savanna dynamics is our ability to diagram the important relationships and understand how they interrelate with sources of variations to cause ecosystem change.     

4490例创伤伤员致伤原因分析

目的:探讨创伤伤员的致伤原因,为院前急救和预检分诊提供依据,为提出预防创伤发生的策略和措施奠定基础。方法:对4490例创伤伤员的资料进行统计分析,分析不同性别、年龄和地区创伤伤员的致伤原因的异同。结果:4490例创伤伤员中中,男女比例为2.81:1。年龄特点:12～60岁组发生创伤达75.16%。6岁以下以烧伤为主要原因,占41.08%;大于60岁以上以跌落/摔伤为主要原因,占63.79%;骨折多发生于12～60岁。致伤原因:跌落/摔伤(占28.69%)、道路交通伤(占28.53%)、锐器/切割伤(占13.23%)。结论:创伤伤员的致伤原因在不同性别、年龄和地区间有着明显特点,可根据具体情况采取相应的防范措施,以减少其发生,同时为创伤伤员的院前急救和预检分诊提供依据。     

Evaluating prognostic accuracy of biomarkers under competing risk

To develop more targeted intervention strategies, an important research goal is to identify markers predictive of clinical events. A crucial step toward this goal is to characterize the clinical performance of a marker for predicting different types of events. In this article, we present statistical methods for evaluating the performance of a prognostic marker in predicting multiple competing events. To capture the potential time-varying predictive performance of the marker and incorporate competing risks, we define time- and cause-specific accuracy summaries by stratifying cases based on causes of failure. Such definition would allow one to evaluate the predictive accuracy of a marker for each type of event and compare its predictiveness across event types. Extending the nonparametric crude cause-specific receiver operating characteristics curve estimators by Saha and Heagerty (2010), we develop inference procedures for a range of cause-specific accuracy summaries. To estimate the accuracy measures and assess how covariates may affect the accuracy of a marker under the competing risk setting, we consider two forms of semiparametric models through the cause-specific hazard framework. These approaches enable a flexible modeling of the relationships between the marker and failure times for each cause, while efficiently accommodating additional covariates. We investigate the asymptotic property of the proposed accuracy estimators and demonstrate the finite sample performance of these estimators through simulation studies. The proposed procedures are illustrated with data from a prostate cancer prognostic study.     

国外松衰退病原因的研究

对安徽省国外松大面积衰退和枯死原因的调查研究表明,造成这种衰退和枯死的现象是多方面因素共同作用的结果,是一种林木衰退病.该衰退病的发生原因:1)诱发因素:温度年较差较大、年降雨量分布不均匀、土壤粘重板结或容重过大、地势低洼积水、土壤瘠薄、林分密度过大;2)激化因素:干旱严重重复发生、割脂过早过度、霜冻、食叶害虫等害虫危害;松针褐斑病等病害侵害;3)促进因素:松枯梢病菌、根腐病菌、立木腐朽病菌、天牛、小蠹虫等病虫害危害.     

糖尿病足治疗新进展

糖尿病足溃烂是糖尿病的常见慢性并发症,以高发生率、高致残率、经济负担重,治疗时间长及高死亡率严重影响病人的生活质量甚至威胁生命,我国糖尿病协会于2010年11月14公布我国糖尿病的患病者已达9240万,除此之外糖尿病前期患者已达1.482亿。而在糖尿病患者中糖尿病足的发病率达到1.7%-11.9%;糖尿病患者中有15%的患者一生中有患糖尿病足的倾向,因此对于糖尿病足的治疗显得尤为重要,本文从糖尿病足的病因、机制,微环境变化着手,重点阐述糖尿病足传统的中西医疗法及目前的手术、介入及干细胞治疗方法的近况,旨在探讨各种方法的优点和不足及可开拓的空间,为进一步治疗糖尿病足提供一定的理论依据,为糖尿病足新方法的研究提供一些新的思维方式。     

引起AECOPD 精神神经异常的原因及治疗对策

目的：探讨引起慢性阻塞性肺疾病合并精神神经异常的原因,以制订有针对性的治疗对策。方法：回顾性分析我院自2010 年1 月到2013 年1 月期间收治的250 例慢性阻塞性肺疾病急性发作期患者的临床资料。结果：32 例患者出现精神神经异常症 状,占12.80%。其中17 例为肺性脑病,占53.13%（17/32）,8 例为低渗性脑病,占25.00%（8/32）,5 例为药物的不良反应,占15.63% （5/32）,2 例为脑梗死,占6.25%（2/32）。所有患者均给予慢性阻塞性肺疾病急性发作的常规治疗方案进行治疗,同时肺性脑病患 者给予积极纠正二氧化碳潴留;低渗性脑病患者给予积极纠正电解质紊乱;脑梗死的患者根据情况给予溶栓、脱水、营养脑神经、 抗凝、抗血小板聚集等治疗;药物不良反应的患者则给予停止应用相应的药物。经过治疗后,29 例症状恢复,占90.63%,3 例最终 死亡,死亡率为9.38%,其中2 例为肺性脑病患者,1 例为低渗性脑病患者。结论：对于慢性阻塞性肺疾病急性发作合并精神神经 异常的治疗,应根据患者的症状、体征以及辅助检查结果,尽早明确诊断,及时干预,尽快控制病情,防止病情恶化。