小流域的综合治理

1984年以来,舒城县采取工程和生物措施相结合的办法,对胡家河等6个小流域进行了综合治理。本文扼要地将在治理和管护工作中积累的经验、方法以及其成效、研究资料介绍给大家,以供参考。     

高良姜叶枯病病原菌的分离和鉴定

[目的]明确高良姜叶枯病病原菌.[方法]病原菌从高良姜感病组织上分离并依据柯赫氏法则进行致病性测定,病原菌的鉴定主要通过形态鉴定和ITS序列分析.[结果]高良姜叶枯病病原菌确定为可可毛色二孢（Lasiodiplodia theobromae）,属子囊菌门（Ascomycota）,座囊菌纲（Dothideomycetes）,葡萄座腔菌目（Botryosphaeriales）,葡萄座腔菌科（Botryosphaeriaceae）,毛色二孢属（Lasiodiplodia）.[结论]首次报道高良姜叶枯病病原菌为可可毛色二孢.     

MAGNETIC RESONANCE IMAGING CHARACTERISTICS OF THE FOOT IN HORSES WITH PALMAR FOOT PAIN AND CONTROL HORSES

Palmar foot pain is a common cause of lameness. Magnetic resonance imaging (MRI) has the potential to detect damage in all tissues of the equine foot, but an understanding of the differences in magnetic resonance (MR) images between feet from horses with and without palmar foot pain is required. This study aimed to describe MR findings in feet from horses with no history of foot-related lameness, and to compare these with MR findings in horses with lameness improved by palmar digital local analgesia. Thirty-four limbs from horses euthanized with a clinical diagnosis of navicular syndrome (ameness >2 months duration, positive response to palmar digital nerve blocks and absence of other forelimb problems) (Group L), and 25 feet from age-matched horses with no history of foot pain (Group N) were examined. For each anatomic structure, MR signal intensity and homogeneity, size, definition of margins, and relationships with other structures were described. Alterations in MR signal intensity and homogeneity were graded as mild, moderate, or severe and compared between Groups L and N. Results revealed that there were significant differences in MR images between Groups N and L. Multiple moderate-severe MR signal changes were present in 91% of limbs from Group L and moderate (none were graded severe) in 27% of limbs from Group N. In most Group L limbs, more than three structures and frequently six to eight structures were abnormal. Concomitant abnormalities involved most frequently the deep digital flexor tendon, distal sesamoidean impar ligament, navicular bone, collateral sesamoidean ligament, and navicular bursa (with significant associations in severity grade between these structures), sometimes with involvement of the distal interphalangeal joint and/or its collateral ligaments. It was concluded that findings on MR images were different between horses with and without foot pain, and that pain localized to the foot was associated with MR changes in a variety of structures, indicating that damage to several structures may occur concurrently and that MR imaging was useful for evaluation of foot pain.     

Infectious dermatitis in a ball python (Python regius) colony.

Seven wild-caught ball pythons (Python regius), including six gravid females and one male, were obtained from Africa and were housed in a government animal facility in Research Triangle Park, North Carolina. Upon arrival, the snakes were found to be infested with ticks (Aponomma latus), which were manually removed. Four weeks following arrival, vesicular skin lesions began to appear on the snakes. Despite treatment of all affected female snakes with amikacin (5 mg/kg i.m., every 3 days) and cefotaxime (25 mg/kg i.m., every 3 days), the condition progressed and five of the female snakes died 7 wk after arrival. The remaining male and one female improved after an increase in environmental temperature, with ecdysis followed by healing. Physiologic stress, ectoparasites, and shipping may have predisposed the snakes to sepsis.     

基于线性价格机制的多认知无线网络资源配置框架

在异构多认知无线网络共存场景中,资源配置是共存协调的关键之一.构建了一种基于线性价格机制的多认知无线网络资源配置框架:将用户带宽需求差异用信道传输特性描述,运用线性价格函数表征认知用户效用和认知无线网络收益,将资源配置抽象为博弈模型,包括三阶段动态博弈:第一阶段,认知无线网络确定向主无线网络租用带宽;第二阶段,认知无线网络确定认知用户使用带宽单价;第三阶段,认知用户通过比较接入不同网络时自身效用,选择能最大化效用的网络接入.阐述了该动态博弈纳什均衡存在的条件和均衡点特性,仿真验证了该框架的合理性和有效性.     

T cell activation by lipopeptide antigens

Unlike major histocompatibility proteins, which bind peptides, CD1 proteins display lipid antigens to T cells. Here, we report that CD1a presents a family of previously unknown lipopeptides from Mycobacterium tuberculosis, named didehydroxymycobactins because of their structural relation to mycobactin siderophores. T cell activation was mediated by the alphabeta T cell receptors and was specific for structure of the acyl and peptidic components of these antigens. These studies identify a means of intracellular pathogen detection and identify lipopeptides as a biochemical class of antigens for T cells, which, like conventional peptides, have a potential for marked structural diversity.     

Structural studies in azolylmethanes

The crystal structures of a number of fungicidal azolylmethanes are compared. In the benzyl compounds [1-aryl-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ones, the corresponding pentan-3-ols, and 1-(4-chlorophenyl)-3-(2-fluorophenyl)-2-(1,2,4-triazol-1-yl)propan-1-one], the benzyl and tert-butyl groups (or 4-chlorophenyl group) are trans, whereas in the analogous phenoxy compounds [1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-one and the corresponding butan-2-ol], the tert-butyl groups are trans to the triazole and gauche to the phenoxy group. Coupling constants, determined by nuclear magnetic resonance (n.m.r.) spectroscopy, suggest that for some compounds there is one dominant solution conformation. Intramolecular hydrogen bonding, observed by infrared spectroscopy in two of the compounds, supports the findings by n.m.r. For some compounds, the crystal and solution conformations appear to be very similar, whereas in others they are quite different. Published data on the relative activity of the enantiomers of the benzyl- and phenoxy-compounds are discussed, but differences in the relative activity of enantiomers in the two series cannot be readily rationalised. It is concluded that different enantiomers may have different modes of binding at the active site.     

Biotic and abiotic influences on rocky intertidal biomass and richness in the southern Benguela region

Species richness and biomass of 12 rocky shores subject to various conditions of substratum type, sea temperature regime, and degree of wave exposure around the Cape of Good Hope were analysed. Zonation and characteristic dominant species are described. Richness values were high (total of 310 species) and were influenced by substratum stability and temperature regime (being highest where the south and west coast biota overlapped) but not rock type or exposure. Richness was greatest where the biomass of either filter-feeders or macroalgae was high otherwise declining upshore. High limpet biomass in the cochlear zone resulted in low algal biomass owing to grazing and an interruption of this vertical gradient. Biomass was influenced by substratum stability and exposure, but not temperature regime. Forty-five species (of which 37 were macroalgae, cirripeds or molluscs) accounted for an average of over 92% of total biomass on each shore. Twenty-one of these favoured exposed conditions resulting in significantly higher total biomass on exposed shores. Biomass also showed an upshore decrease interrupted in the cochlear zone. Herbivore biomass was related to beach slope and was greatest on gently sloping shores. Biotic interactions, particularly grazing and competition for space, are discussed within this framework of abiotic factors.     

Linking Northeast Pacific recruitment synchrony to environmental variability

We investigated the hypothesis that synchronous recruitment is due to a shared susceptibility to environmental processes using stock–recruitment residuals for 52 marine fish stocks within three Northeast Pacific large marine ecosystems: the Eastern Bering Sea and Aleutian Islands, Gulf of Alaska, and California Current. There was moderate coherence in exceptionally strong and weak year‐classes and correlations across stocks. Based on evidence of synchrony from these analyses, we used Bayesian hierarchical models to relate recruitment to environmental covariates for groups of stocks that may be similarly influenced by environmental processes based on their life histories. There were consistent relationships among stocks to the covariates, especially within the Gulf of Alaska and California Current. The best Gulf of Alaska model included Northeast Pacific sea surface height as a predictor of recruitment, and was particularly strong for stocks dependent on cross‐shelf transport during the larval phase for recruitment. In the California Current the best‐fit model included San Francisco coastal sea level height as a predictor, with higher recruitment for many stocks corresponding to anomalously high sea level the year before spawning and low sea level the year of spawning. The best Eastern Bering Sea and Aleutian Islands model included several environmental variables as covariates and there was some consistent response across stocks to these variables. Future research may be able to utilize these across‐stock environmental influences, in conjunction with an understanding of ecological processes important across early life history stages, to improve identification of environmental drivers of recruitment.