基于分量替换高分辨率遥感图像融合方法的对比研究

基于分量替换的高分辨率遥感图像融合是一种十分重要的融合方法,但对该方法的融合原理的深入分析在国内还鲜有报道。为此对分量替换融合方法进行原理探究和实验对比分析。首先从线性代数的角度来阐述分量替换融合算法的实质,并对两种典型的构造可替换波段的分量替换方法（基于光谱响应函数模拟低分辨率全色波段的Gram-Schmidt融合法（GS1）和基于多元一次线性回归拟合低分辨率全色波段的Gram-Schmidt（GS2）融合法进行原理说明;其次,选取QuickBird全色与多光谱图像数据,进行三种有代表性的基于分量替换的融合方法（PCA,GS1,GS2）的对比分析。通过对比融合前后典型地物的光谱特性变化来评价融合影像的光谱保真性也是该研究的一大特色。结果表明:3种融合方法都具有很高的光谱保真性,GS2融合方法具有最优的光谱保真性,PCA和GS1融合算法次之,尤其是GS1融合处理后的图像存在部分光谱失真的现象,GS2算法的光谱保真性明显优于GS1。从基于分量替换融合方法的实质可以诠释出造成GS1融合图像光谱失真的根本原因,GS1融合算法使用的只是实验室理想环境下所获取的名义上的光谱响应特征。传感器的实际成像过程受到诸多因素的影响,如传感器在轨工作环境、大气、观测角度不同等的影响。GS1算法单纯通过不同波段光谱响应函数的线性组合来模拟低分辨率全色波段并不十分准确,GS2直接利用MS和Pan波段像元灰度值进行线性回归,克服了上述不确定性问题。通过以上对比研究发现,如何利用多光谱数据准确地模拟低分辨率全色波段,直接影响到融合后影像的光谱保真性,是目前高分辨率遥感图像融合的关键技术。     

夏季高温环境下3个矾根品种的光合特性比较

在夏季高温环境中对3个矾根(Heuchera)品种进行光合特性研究。结果表明:3个矾根品种对强光利用能力较强,大小排序为:‘巴黎’（‘Paris’)＞‘好莱坞’（‘Hollywood’)＞‘草莓漩涡’（‘Strawberry+Swirls’);在3个矾根品种中,具有明显的光合“午休”现象,’巴黎’具有最高的净光合速率（P_n）;3个品种的水分利用率(WUE)在上午较高,于11:00后WUE维持在较低水平,其大小排序为:‘巴黎’（1.13 mmol·mol^-1）＞‘草莓漩涡’（0.93 mmol·mol^-1）＞‘好莱坞’（0.62 mmol·mol^-1）;蒸腾速率（T_r）、气孔导度（G_s）与P_n呈现相似的双峰曲线变化,胞间二氧化碳浓度（C_i）则与P_n相反。相关性分析表明,植物光合作用与其生理环境因子存在着复杂的相互关系。     

土壤淹水条件下香附子光响应过程的模型比较

利用直角双曲线模型、非直角双曲线模型和直角双曲线修正模型对三峡库区消落带土壤淹水条件下香附子光响应过程的测量数据进行了重新拟合,分析了不同光响应模型对香附子的适用性及香附子主要光响应参数对土壤淹水的适应规律。结果表明,非直角双曲线模型对常规水分管理组（CK）香附子植株光响应过程的拟合效果要优于直角双曲线模型和直角双曲线修正模型,而直角双曲线修正模型对淹水组（T1）香附子植株光合响应过程的拟合效果要优于其他2种模型。光响应参数的拟合效果则表现为:非直角双曲线模型对LCP和R_d的拟合效果最佳,直角双曲线修正模型对LSP和P_nmax的拟合效果最佳,而直角双曲线模型对这些光响应参数的拟合效果最差。受水淹影响,香附子的光合能力以及光适应能力减弱,出现了不同程度的光抑制现象,水淹90 d后,T1处理香附子植株叶片LCP和R_d分别比对照增加了56.9%和43.1%,而叶片LSP和P_nmax分别比对照降低了52.3%和 47.4%。     

Work-related increases in titer of Campylobacter jejuni antibody among workers at a chicken processing plant in Miyazaki prefecture,Japan, independent of individual ingestion of edible raw chicken meat

Workers in poultry abattoirs may be frequently exposed to Campylobacter jejuni, which is a leading cause of bacterial food poisoning in Japan. The present study was conducted to measure the titers of IgG and IgA antibodies against C. jejuni among 104 female workers in a chicken processing plant in Miyazaki prefecture, Japan. Information regarding habitual ingestion of raw chicken meat and potential occupational risk factors was collected using a questionnaire. Acid extracts of four C. jejuni strains representing the genotypes most dominant in Miyazaki were used as antigens. The levels of both immunoglobulins measured by ELISA were not correlated with ingestion of edible raw chicken meat, the amount consumed in one sitting, or its frequency. Although age was correlated with antibody levels, the length of employment was not. Furthermore, the IgG and IgA levels in workers at the evisceration step were significantly higher than those at other locations in the plant. To identify the bacterial proteins recognized by the workers’ IgG and IgA antibodies, Western blotting followed by LC/MS was conducted. Flagellin was identified as the common protein recognized in the sera of workers for whom ELISA demonstrated both the highest and lowest antibody levels. We concluded that the titers of IgG and IgA against C. jejuni in workers at the processing plant had been increased by occupational exposure to Campylobacter, regardless of raw chicken meat ingestion.     

Estimating nocturnal ecosystem respiration from the vertical turbulent flux and change in storage of CO2

Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u_*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u_*-threshold filtering technique. Tellus 59B, 397–403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (F_C) and change in storage (F_S) of CO₂ in the few hours after sundown. The sum of F_C and F_S reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration R_Rmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of F_c + F_s extrapolated to zero light, R_LRC, and (3) with a detailed process-based forest ecosystem model, R_cast. At most sites respiration rates estimated using the u_*-filter, R_ust, were smaller than R_Rmax and R_LRC. Agreement of our approach with independent measurements indicates that R_Rmax provides an excellent estimate of nighttime ecosystem respiration.     

气候变化对我国刺槐、紫丁香始花期的影响

该文探讨了1963—1988年间北京地区刺槐、紫丁香始花期对气温、日照及降水变化的响应以及我国不同地区这两种树木始花期与不同时段气温变化之间的相关关系.结果显示,临近始花期,气温对始花期早晚的影响最显著,日照次之,降水量最弱.气温升高、日照时数增加,始花期提前;而降水量增加,始花期推迟.气温对始花期产生影响的时段主要集中在春季及冬末,影响最显著的时段是始花前2～8旬,即从2月上旬到始花日期之间的时段.春季气温越高,始花期越早,而上年夏、秋、冬季的气温对始花期没有显著性影响.不同地区,春季平均气温、最高气温及最低气温对始花期均有影响,一般而言,最高气温的影响最强,而最低气温的影响最弱,这3种气温的升高使始花期均有提前的效应.     

不同类型鸡新城疫La Sota疫苗的免疫应答比较

A、B、C、D组SPF鸡分别接种La Sota加佐剂活疫苗,未加佐剂活疫苗,氢氧化铝胶佐剂苗和油佐剂灭活疫苗,通过采集血清进行红细胞凝集抑制试验,测定其抗体水平,并进行比较。结果表明,La Sota加佐剂活疫苗组可产生较高的抗体滴度,并持续较长时间;而未加佐剂疫苗组血清阳转较弱,且持续时间较短;油佐剂灭活疫苗组抗体滴度最高,维持时间最长。     

Lysine requirement studies in modern genotype barrows dependent on age,protein deposition and dietary lysine efficiency

N balance experiments were conducted to derive age‐dependent model parameters for modelling of lysine (Lys) requirements in growing pigs. Modern genotype barrows from 16 litters were utilized (four piglets/litter) at 15, 30, 50, 70, 90 and 110 kg body weight respectively. Six diets provided graded dietary protein supply (40 to 320 g/kg) by a constant mixture of barley, wheat, potato protein, wheat gluten, soybean protein concentrate and crystalline amino acids. Lys was set as the first limiting dietary amino acid. Each age period provided 24 N balance data (n = 4) to derive N maintenance requirement (NMR) and theoretical maximum for daily N retention (NR_maxT) by non‐linear regression analysis. At high dietary Lys efficiency, 17–18 g daily Lys intake was required for 170 g daily protein deposition. To achieve similar daily protein deposition, pigs need 21–23 g Lys if the Lys efficiency is 20% lower. For higher daily protein deposition (195–200 g) and varying dietary Lys efficiency, between 22 and 29 g Lys was required. The Lys requirement data yielded by modelling were in line with current recommendations. Further developments of the approach are discussed to improve age‐independent applications.     

Infection, immunity and the neuroendocrine response

The Central Nervous (CNS) and Immune Systems (IS) are the two major adaptive systems which respond rapidly to numerous challenges that are able to compromise health. The defensive response strictly linking innate to acquired immunity, works continuously to limit pathogen invasion and damage. The efficiency of the innate response is crucial for survival and for an optimum priming of acquired immunity. During infection, the immune response is modulated by an integrated neuro-immune network which potentiates innate immunity, controls potential harmful effects and also addresses metabolic and nutritional modifications supporting immune function. In the last decade much knowledge has been gained on the molecular signals that orchestrate this integrated adaptive response, with focus on the systemic mediators which have a crucial role in driving and controlling an efficient protective response. These mediators are also able to signal alterations and control pathway dysfunctions which may be involved in the persistence and/or overexpression of inflammation that may lead to tissue damage and to a negative metabolic impact, causing retarded growth.This review aims to describe some important signalling pathways which drive bidirectional communication between the Immune and Nervous Systems during infection. Particular emphasis is placed on pro-inflammatory cytokines, immunomodulator hormones such as Glucocorticoids (GCs), Growth hormone (GH), Insulin-like Growth Factor-1 (IGF-1), and Leptin, as well as nutritional factors such as Zinc (Zn).Finally, the review includes up-to-date information on this neuroimmune cross-talk in domestic animals. Data in domestic animal species are still limited, but there are several exciting areas of research, like the potential interaction pathways between mediators (i.e. cytokine-HPA regulation, IL-6-GCS-Zn, cytokines-GH/IGF-1, IL-6-GH-Leptin and thymus activity) that are or could be promising topics of future research in veterinary medicine.     

Growth pattern and partial proteome of Mycobacterium avium subsp. paratuberculosis during the stress response to hypoxia and nutrient starvation

Mycobacterium avium subsp. paratuberculosis is an important pathogen that causes Johne's disease in animals and has been implicated in Crohn's disease in man yet few data exist on its physiological adaptation in either the host or the environment. In this study, the proteomic responses of the two distinct strains of M. a. paratuberculosis, cattle (C) and sheep (S), to hypoxia and starvation were studied in vitro. Nutrient starvation inhibited growth of both strains and was lethal for S strain after 12 weeks. Hypoxia induced a state of very low metabolic activity but rapid resuscitation occurred upon restoration of an aerobic atmosphere, consistent with the dormancy response of other mycobacteria. A total of 55 protein spots differentially expressed in response to starvation and/or hypoxic stress in one or both strains were identified from 2D gels and classified based on biological function. Antioxidant enzymes, oxidoreducatse enzymes and proteins involved in amino acid metabolism, fatty acid metabolism, ATP and purine biosynthesis, proteolysis, cell wall synthesis, protein synthesis, signal recognition and hypothetical proteins with putative functions including dormancy response regulators and universal stress proteins were identified. These proteins are potential screening targets for future diagnosis, prevention and control of M. a. paratuberculosis infection and their identification will assist understanding the pathogenesis of diseases caused by this organism.