莺总科鸟类的系统分类进展评述(英文)

本文评述了莺总科鸟类的系统分类,并重点探讨科间、属内系统发育关系以及种级分类地位。基于已发表的 DNA 序列数据,对马岛莺科(Bernieridae)和柳莺科(Phylloscopidae)重新进行了分析。大量的分子水平的研究让我们对鸟类系统发育的认识有了很大提高。但是,由于一些主要进化分支(科)的快速分化,使得这些科之间的相互关系依然不明确。同样,分子标记和(或)鸣声及其他生活史资料在大量研究中的应用,大大提高了种级水平的分类可靠性。我们推测,随着人们运用现代的整合方法对新类群的不断研究,物种数量会不断增加。     

Rare earth intensifying screens in veterinary radiology

Radiation dose to personnel and low capacity X–ray equipment are obstacles to the optimal use of veterinary radiology. In order to find means to lower radiation dose and improve the quality of the radiographic image in veterinary radiology the authors have tested the so–called rare earth intensifying screens under experimental and clinical conditions. Of the basis of their findings they recommend the use of predominantly green light–emitting screen with lanthanum oxysulphide crystals activated with terbium, in combination with orthochromatic film. This combination was shown to give the best ratio image–screen noise. Considerable dose reduction was obtained with this system, and the image quality improved due to less blurring by motion.     

Simulated effects of browsing on the production and economic values of Scots pine (Pinus sylvestris) stands

Effects of browsing damage on Scots pine (Pinus sylvestris) production and economic value were simulated on sites ranging in fertility from relatively poor to relatively high. Effects of browsing damage on growth and survival after trees had exceeded browsing-height were estimated using data from a browsing study. Stem lists were produced when stems had reached a height of about 4?m. Individual tree data were then imported into the Heureka simulation system to generate predictions about stand production and economic value. Six browsing levels were simulated: 0, 2, 5, 10, 15 and 27% browsing damage annually. The 2% and 5% browsing levels had only minor effects on production, whilst higher browsing levels significantly reduced production. However, the effect on economic value was more pronounced and even the 2% browsing level had significant effects on estimated land expectation values. Results from this simulation may support discussions about acceptable browsing levels in young Scots pine stands.     

Inhibitory effect of flowering and early fruit growth on leaf photosynthesis in mango

Carbohydrate and nitrogen contents, chlorophyll fluorescence and gas exchange were measured in leaves from both vegetative and reproductive terminal shoots of 12-year-old flowering mango trees. Reproductive shoot leaves were close to swelling floral buds, inflorescences or panicles bearing set fruits. Leaves close to inflorescences had lower rates of mitochondrial respiration (Rd) and net photosynthesis (Anet), and lower stomatal conductance (gs) and quantum efficiency of photosystem II under actinic light than vegetative shoot leaves. Leaf nitrogen concentration, which decreased from the beginning until the end of flowering, was lower in leaves close to inflorescences than in vegetative shoot leaves. However, these differences and changes were counterbalanced by an increase in leaf mass-to-area ratio so that leaf nitrogen per unit leaf area (Na) remained nearly constant during the whole flowering period, except in leaves close to panicles bearing set fruits. Net CO2 assimilation rate simulated by a biochemical model of leaf photosynthesis (Urban et al. 2003) was much higher than Anet measured at an ambient CO2 partial pressure (Ca) of either 36 or 70 Pa. The overestimation of Anet was more pronounced in leaves close to inflorescences, to panicles bearing set fruits and to reversing inflorescences (characterized by the appearance of leaves in terminal positions on inflorescences) than in vegetative shoot leaves. It is concluded that low Anet in leaves close to inflorescences was probably due neither to changes in Na nor to a decrease in Rubisco activity induced by low gs, but rather to a decrease in electron flow in photosystem II. This decrease was not directly associated with higher starch or soluble sugar contents.     

基于景观格局分析的局地土地利用突变情景识别——以重庆市沙坪坝区为例

以重庆市沙坪坝区为研究区,采用土地利用现状数据库,运用GIS的空间分析功能,从景观组分贡献率入手,剖析景观组分对局地景观格局变化的贡献程度,实现对土地利用突变情景识别,其结果表明:农业景观与城市等人为景观竞相作用、农业比较效益差异与农业市场竞争、农户宜人和宜居的生存空间土地利用意识逐步成熟是导致研究区土地利用突变最主要的驱动力.     

Climate sensitivity estimated from temperature reconstructions of the Last Glacial Maximum

Assessing the impact of future anthropogenic carbon emissions is currently impeded by uncertainties in our knowledge of equilibrium climate sensitivity to atmospheric carbon dioxide doubling. Previous studies suggest 3 kelvin (K) as the best estimate, 2 to 4.5 K as the 66% probability range, and nonzero probabilities for much higher values, the latter implying a small chance of high-impact climate changes that would be difficult to avoid. Here, combining extensive sea and land surface temperature reconstructions from the Last Glacial Maximum with climate model simulations, we estimate a lower median (2.3 K) and reduced uncertainty (1.7 to 2.6 K as the 66% probability range, which can be widened using alternate assumptions or data subsets). Assuming that paleoclimatic constraints apply to the future, as predicted by our model, these results imply a lower probability of imminent extreme climatic change than previously thought.     

Restorative effects of visits to urban and forest environments in patients with exhaustion disorder

This experimental study investigated differences in perceived restorativeness, mood, attention capacity and physiological reactions when visiting city and forest environments. Twenty female patients diagnosed with exhaustion disorder visited three different forest environments and one city environment in randomized order. They performed a standardized 90-min test procedure in each of these environments. Evaluation of the environments and psychological effects in mood were studied with self-administered questionnaires. Attention capacity was studied with Necker Cube Pattern Control task. Physiological responses were measured with regularly scheduled controls of heart rate and blood pressure, and a single test of heart rate recovery. Visits to the forest environments were perceived as significantly more restorative, enhancing mood and attention capacity compared to the city. This also applies to the results of heart rate and to some extent to the results of the diastolic blood pressure. The results from this experimental study support our hypothesis that short visits to forest environments enhance both psychological and physiological recovery and that visits to forest environments are likely to be beneficial when suffering from exhaustion disorder.     

Development of Myelination in the Bovine Fetal Brain: an Immunohistochemical Study

In this study, the development of myelination in the fetal bovine brain (age-range: between 1–2 and 8–9 months) was examined applying: 1. Immunohistochemical staining methods and antibodies against bovine proteolipid protein (PLP), synthetic tridecapeptide of bovine PLP, human myelin basic protein (MBP), human myelin-associated glycoprotein (MAG); and 2. Using the Luxol fast-blue (LFB) technique.     

Selenium and the health status,production results,and product quality in poultry

A Selenium (Se) is an element belonging to the nonmetallic group. It was first discovered in 1817 by J.J. Berzelius. Until the 1950s, it was considered to be toxic to animals. However, with increasing research conducted on laboratory animals, it is now clear that Se is necessary for the proper functioning of both plants and animals. Recent studies indicate that Se is necessary for the proper functioning of metabolic pathways in animals. It was evidenced that Se is a component of about 100 proteins involved in the immune system, antioxidant homeostasis, or release of an inflammatory mediator. Therefore, it is of key interest to find the appropriate dosage for the supplementation of Se in the diet of farm animals and thereby eliminate physiological disorders in the body associated with Se imbalance. In this study, we present a literature review on the importance and appropriate dosage of Se in the diet of poultry concerning their health status, production results, and the quality of animal-origin products.