Plant physiology in theory and practice: An analysis of the WBE model for vascular plants

The theoretical model of West, Brown and Enquist (hereafter WBE) proposed the fractal geometry of the transport system as the origin of the allometric scaling laws observed in nature. The WBE model has either been criticized for some restrictive and biologically unrealistic constraints or its reliability debated on the evidence of empirical tests. In this work, we revised the structure of the WBE model for vascular plants, highlighting some critical assumptions and simplifications and discuss them with regard to empirical evidence from plant anatomy and physiology. We conclude that the WBE model had the distinct merit of shedding light on some important features such as conduit tapering. Nonetheless, it is over-simplistic and a revised model would be desirable with an ontogenetic perspective that takes some important phenomena into account, such as the transformation of the inner sapwood into heartwood and the effect of hydraulic constraints in limiting the growth in height.     

Safety zones for a Sclerotinia sclerotiorum-based mycoherbicide: Accounting for regional and yearly variation in climate

Variation in the width of 'safety zones' for sheep and dairy pasture treated with a Sclerotinia sclerotiorum (Lib.) de Bary-based mycoherbicide was quantified using 10 years of climate data from each of five regions in New Zealand. Acceptable and risk-averse zones were defined as the maximum distances in any direction from a treated pasture where 'added:natural' ratios of air-borne S. sclerotiorum spores are 1:1 and 1:10, respectively. The 10-year mean 1:1 safety zone had zero width for sheep pasture at all locations, and was at most, 50 m wide for dairy pasture. The width of the 10-year mean 1:10 zone varied regionally from 314 to 443 m for sheep and from 175 to 280 m for dairy pasture, and the 90th percentile 1:10 zones were up to 41% wider. Linear relationships between safety zone width and mean wind speed were evident and these could be used to derive region-specific safety zones.     

广东省生态农业建设及其发展对策

介绍了广东生态农业的产生和发展的背景及生态农业建设的基本情况,并着重对目前广东省生态农业建设的9种主要模式及其经济和生态效益以及存在的问题进行了较详细的分析,在此基础上提出了广东生态农业发展的主要对策。     

Poplar genomics is getting popular: the impact of the poplar genome project on tree research

Trees, due to their long life-span, have characteristics that distinguish them from annual, herbaceous plants. It is likely that many of these properties are based on a tree-specific genetic foundation. The U.S. Department of Energy initiated a genome-sequencing project for Populus, a model perennial plant. Through international collaboration and input to the sequencing effort, the annotated whole genome sequence of Populus trichocarpa will be released to the public in early 2004. This genomic resource will, for the first time, allow comparison between a perennial and an annual plant on a whole genome basis and therefore provide clues for molecular research on tree-specific questions like dormancy, development of a secondary cambium, juvenile-mature phase change, or long-term host-pest interactions. The approximately 520 Mbp of annotated genomic sequence will complement and expand the knowledge provided so far by the 125,000 ESTs from poplar that are available in public databases. This article introduces the international poplar research programmes and points out the significance of the poplar genome project for plant research.     

原发性肝癌患者术后癌因性疲乏的影响因素及其预测模型构建

摘要 目的：分析原发性肝癌患者术后癌因性疲乏（CRF）的影响因素并构建预测模型。方法：选取2020年1月～2023年1月湖南师范大学附属第一医院收治接受手术治疗的200例原发性肝癌患者,根据术后3个月是否存在CRF将患者分为CRF组（124例）和非CRF组（76例）。单因素和多因素Logistic回归分析影响原发性肝癌患者术后CRF的因素并构建其预测模型。通过受试者工作特征（ROC）曲线分析预测模型对原发性肝癌患者术后CRF的预测价值。结果：单因素分析显示,CRF组病程长于非CRF组,Child-Pugh分级B级、美国东部肿瘤协作组功能状态（ECOG）评分1～2分、辅助化疗、医疗付费方式自费、抑郁/焦虑比例高于非CRF组,文化程度高中及以上、家庭月收入＞3000元、高度社会支持度比例低于非CRF组（P＜0.05）。多因素Logistic回归分析显示,病程延长、Child-Pugh分级B级、ECOG评分1～2分、辅助化疗、医疗付费方式自费、抑郁/焦虑为影响原发性肝癌患者术后CRF的独立危险因素,家庭月收入＞3000元、高度社会支持为独立保护因素（P＜0.05）。原发性肝癌患者术后CRF的预测模型方程：Logit（P）=P/1-P=-1.252+0.409×病程+0.839×Child-Pugh分级+1.378×ECOG评分+1.055×辅助化疗+1.476×医疗付费方式-0.793×家庭月收入+0.883×抑郁/焦虑-1.260×社会支持度。霍斯默-莱梅肖检验P＞0.05。ROC曲线分析显示,模型预测原发性肝癌患者术后CRF的曲线下面积为0.910,敏感度为87.10%,特异度为85.53%。结论：病程、Child-Pugh分级、ECOG评分、辅助化疗、医疗付费方式、抑郁/焦虑、家庭月收入、社会支持度为影响原发性肝癌患者术后CRF的因素,基于此构建的预测模型对原发性肝癌患者术后CRF的预测价值较高,可能有助于临床早期发现和干预原发性肝癌患者术后CRF,以改善患者预后。     

不同剂量阿加曲班联合丁苯酞对急性脑梗死患者效果及预后的影响因素分析

摘要 目的：本研究旨在探讨不同剂量阿加曲班联合丁苯酞对急性脑梗死患者效果及预后的影响因素。方法：以自2019年6月到2022年8月在我院收治的90例急诊急性脑梗死为研究对象,采用随机数字表法将其分为高剂量组（给予高剂量阿加曲班联合丁苯酞治疗）和低剂量组（给予低剂量阿加曲班联合丁苯酞治疗）各45例。对比治疗7 d后两组临床疗效及预后,分析治疗前及治疗7 d后两组神经功能[中国卒中量表（CSS）评分、神经功能（NIHSS）评分],根据不同预后将患者分为预后良好组和预后不良组,采用单/多因素Logisitic回归分析急性脑梗死预后的影响因素。结果：（1）将两组的临床疗效纳入研究并实施组间差异性比较,结果显示,高剂量组总有效率高于低剂量组（P＜0.05）。（2）将两组的神经功能采用CSS评分、NIHSS评分评估纳入研究并实施组间差异性比较,结果显示治疗前,两组采用CSS评分、NIHSS评分比较（P＞0.05）;治疗7 d后,高剂量组采用CSS评分、NIHSS评分高于低剂量组（P＜0.05）。（3）将两组的预后采用mRS评分评估纳入研究并实施组间差异性比较,结果显示,高剂量组预后良好2.22%（1/45）高于低剂量组15.56%（7/45）（P＜0.05）。（4）预后良好组患者年龄、治疗前CSS评分及治疗前NIHSS评分与预后不良组存在差异（P＜0.05）。（5）以急性脑梗死预后为因变量,以单因素中对比有差异的指标为自变量,经多因素Logisitic回归分析急性脑梗死预后的影响因素为治疗前CSS评分及治疗前NIHSS 评分。结论：高剂量阿加曲班联合丁苯酞能够有效治疗急性脑梗死患者,而急性脑梗死预后的影响因素为治疗前CSS评分及治疗前NIHSS 评分。     

Assessing differential gene expression with small sample sizes in oligonucleotide arrays using a mean-variance model

The identification of the genes that are differentially expressed in two-sample microarray experiments remains a difficult problem when the number of arrays is very small. We discuss the implications of using ordinary t-statistics and examine other commonly used variants. For oligonucleotide arrays with multiple probes per gene, we introduce a simple model relating the mean and variance of expression, possibly with gene-specific random effects. Parameter estimates from the model have natural shrinkage properties that guard against inappropriately small variance estimates, and the model is used to obtain a differential expression statistic. A limiting value to the positive false discovery rate (pFDR) for ordinary t-tests provides motivation for our use of the data structure to improve variance estimates. Our approach performs well compared to other proposed approaches in terms of the false discovery rate.     

Thermal effects in stretching of Go-like models of titin and secondary structures

The effect of temperature on mechanical unfolding of proteins is studied using a Go-like model with a realistic contact map and Lennard-Jones contact interactions. The behavior of the I27 domain of titin and its serial repeats is contrasted to that of simple secondary structures. In all cases, thermal fluctuations accelerate the unraveling process, decreasing the unfolding force nearly linearly at low temperatures. However, differences in bonding geometry lead to different sensitivity to temperature and different changes in the unfolding pattern. Due to its special native-state geometry, titin is much more thermally and elastically stable than the secondary structures. At low temperatures, serial repeats of titin show a parallel unfolding of all domains to an intermediate state, followed by serial unfolding of the domains. At high temperatures, all domains unfold simultaneously, and the unfolding distance decreases monotonically with the contact order, that is, the sequence distance between the amino acids that form the native contact.     

Passive restoration in Araucaria Forest: useful ecological indicators in monitoring successional advancement in exotic tree plantation landscapes

Monitoring successional advancement is a complex field involving a constant search for applied ecological indicators which facilitate monitoring of secondary forests for both active and passive restoration. In this study, the authors investigate the successional advancement of floristics and tree structure within Araucaria Forest (AF) fragments under passive restoration in a context where exotic tree plantations (mainly Pinus L. genus) dominate the landscape. The ecological indicators used were floristic dissimilarity (β‐diversity inferences), indicator species, ecological groups of species, basal area, and species abundance distribution (SAD) models (α‐diversity inferences). A total of 182 tree species belonging to 91 genera and 43 botanical families were identified. A high β diversity was verified for which each site has indicator species (for the locations CD—Dicksonia sellowiana; CO—Cryptocarya aschersoniana; and PG—Pinus taeda), where pioneer species contributed to much of the abundance. Different SAD models are useful for describing passive restoration sites in exotic tree plantation landscapes, namely Lognormal, Mandelbrot, and Zipf. SAD models together with basal area, taxonomic group (e.g. Myrtaceae assemblage), and tree abundance in ecological groups are strategic ecological indicators for monitoring successional advancement in AF.