盐度变化对携带白斑综合症病毒(WSSV)的凡纳滨对虾(Litopenaeus vannamei)的影响

研究盐度渐变和突变对WSSV在凡纳滨对虾(Litopenaeus vannamei)体内增殖的影响。结果表明,盐度由起始盐度(23±1)往高盐度(32±1)和低盐度(14±1)突变在整个实验中对凡纳滨对虾的累积死亡率和对虾体内病毒增殖的影响显著(P0.05),先感染WSSV实验,高盐度、起始盐度、低盐度累积死亡率分别为(61.1±10.7)%、(48.9±1.9)%、(63.3±12.0)%,病毒含量分别为6.0×107、3.7×106、5.3×107 copy/g;后感染WSSV实验,分别为(75.6±3.8)%、(52.2±13.4)%、(63.3±3.3)%;病毒含量分别为5.7×107、2.3×106、2.8×107 copy/g。盐度渐变实验各组至24h对虾死亡率低于18.9%,48h出现死亡高峰,72—96h存在显著差异(P0.05),先感染WSSV实验,高盐度、起始盐度、低盐度最大死亡率分别为(75.6±5.1)%、(38.9±5.1)%、(69.3±6.9)%,病毒含量分别为7.6×107、5.3×106、2.4×106copy/g;后感染WSSV实验分别为(46.7±10)%、(45.6±18.9)%、(74.4±13.9)%;病毒含量分别为5.1×106、4.8×105、1.0×107 copy/g。因此盐度变化会影响对虾的抗病能力,可造成对虾体内WSSV快速增殖;对携带WSSV对虾,盐度变化会大大提高WSSV从潜伏感染转为急性感染的可能,盐度是引起WSSV从潜伏感染转为急性感染的关键影响因子之一。     

Treatment of a potential soil capping for open-cut mines (Part 1): Influence of prior management on responses to a phyto-organic amendment

Extraction of mineral ores, and some projects in engineering geology commonly entail removal of large tracts of valuable topsoil called overburden. A potential mine overburden capping material from an Alfisol with different management histories was treated to assess its physical responses to phyto-organic amendments during storage. Although there were small inceases in hydraulic conductivity, phyto-organic amendments did not greatly improve the physical properties of the Alfisol which had previously been cultivated for several years, as changes in stability and water retention were generally not statistically significant. However, very substantial increases of stability (about 25%) and water retention about 40%) occurred in the same soil which had previously been under a long-term permanent pasture regime. As topsoils can quickly deteriorate when removed and stored, prior soil management should be taken into account where topsoil is to be removed and replaced as a capping after operations such as ore extraction.     

Geotechnical characterisation of stratocone crater wall sequences, White Island Volcano, New Zealand

Geotechnical characterisation is undertaken for 3 broad units comprising the bulk of the stratigraphy identified on White Island Volcano, Bay of Plenty, New Zealand, an active island stratovolcano. Field and laboratory measurements were used to describe rock mass characteristics for jointed lava flow units, and ring shear tests were undertaken to derive residual strength parameters for joint infilling materials within the lavas. Rock Mass Rating (RMR) and Geological Strength Index (GSI) values were calculated and converted to Mohr-Coulomb strength parameters using the Hoek-Brown criterion. Backanalysis of known landslide scarps was used to derive strength parameters for brecciated rock masses and hydrothermally altered rock masses. Andesite lava flows have high intact strength (σ_ci = 184 ± 50 MN m^− 2; γ = 24.7 ± 0.3 kN m^− 3) and typically 3 wide, infilled joint sets, one parallel to flow direction and two steeply inclined, with spacings of 0.3-1.7 m. Joints are rough, with estimated friction angles for clean joints of ?_j = 42-47°. Joint infill materials are clayey silts derived from weathering of wall rocks and primary volcanic sources; they have low plastic (54%) and liquid (84%) limits and residual strength values of c_r = 0 kN m^− 2 and ?_r = 23.9 ± 3.1°. RMR values range from 70 to 73, giving calculated strength parameters of c′ = 1161-3391 kN m^− 2 and ?′ = 50.5-62.3°. Backanalysis suggests brecciated rock masses have c′ = 0 kN m^− 2 and ?′ = 35.4°, whereas GSI observations in the field suggest higher cohesion (c′ = 306-719 kN m^− 2) and a range of friction angles bracketing the backanalysed result (?′ = 30.6-41.7°). Hydrothermally altered rock masses have c′ = 369 kN m^− 2 and ?′ = 14.9°, indicating considerable loss of strength, especially frictional resistance, compared with the fresh lava units. Values measured at outcrop scale in this study are in keeping with other published values for similar volcanic edifices; backanalysed data suggest weaker rock mass properties than those determined at outcrop. This is interpreted as a scale issue, whereby rock mass characteristics of a large rock mass (crater wall scale) are weaker than those of small outcrops, due in part to the overestimation of friction angle from measurements on small exposures.     

The homonormalisation of white heterosexual leisure spaces in Bloemfontein, South Africa

The paper comprises a response to the overwhelming lack of geographical research into South African gay male leisure space development and augments the first detailed analyses of white gay leisure space development in this country by redirecting the geographic focus to a smaller provincial city. The image of gay leisure space that emerges in Bloemfontein is different from those identified and described in large metropolitan complexes. What emerges in this city is the development of gay-coded spaces in which heterosexual leisure spaces are queered, but not with the intent or outcome of generating exclusively gay spaces. Homonormalised spaces are created. It is contended that much of the current debates approach the so-called homonormalistion of gay leisure space from an unhelpful “gay/queer-disempowered” perspective which is inadequate to explain the development of a range of leisure spaces certain gay/queer cohorts created and/or seek out. It is suggested that homonormalised spaces are far more than heteronormativity infiltrating the gay (leisure) world through a range of consumption-led processes/events, or gay male capitulation to such normative hegemonies. It is argued that “homonormalisation” should be understood more reflexively.     

广西维罗沉积型超微细高岭土的选矿研究

通过对维罗沉积型超微细高岭土矿进行捣浆─分散沉淀除铁、除钛和氧化破坏腐植酸的脱色处理,把维罗高岭土的白度从６０．６％提高到８２．１％,满足了作为涂布级高岭土白度大于８０％的工业指标要求。精土经轻工业部北京造纸研究所试验,除粘度较大外,其余达到刮刀涂布级要求。     

分形脉冲反褶积方法

解地震反演问题的脉冲反褶积方法是基于反射系数白噪和子波为最小相位的假设下提出的．近几年的研究证明反射系数并不都是白噪,而是某种分形噪声,如果用一类分形反褶积方法,则将地震反演问题化为难以求解的非线性方程组．本文用反射系数的分形性质,推导出一个更为简单易解的线性方程组,称为分形脉冲反褶积．数值计算表明,本文的方法是有效的．     

Coral Diseases in the Indo-Pacific: A First Record

Abstract. . The so-called "band" diseases of reef corals, the White Band Disease (WBD) and the Black Band Disease (BBD), were observed in the Red Sea and in the Philippines. Since they were previously known only from the western Atlantic, this is the first record for the Indo-Pacific region. WBD is neither infectious nor contagious and the pathogen is unknown. BBD is highly infectious and contagious and is caused by the cyanophyte Phormidium corallyticum. Susceptibility to WBD occurs throughout the order Scleractinia, but the effects of the disease are most severe among Acroporidae. Susceptibility to BBD seems to be restricted to Faviidae, with Platygyra and Goniastrea species the most heavily afflicted. WBD cannot be influenced by any parameter tested so far. BBD can be enhanced by light and by water eutrophication, and its advance can be stopped by antibiotics. An active WBD seems to be a precondition for the origin of BBD.     

感染溶藻弧菌及白斑综合症病毒后凡纳滨对虾不同组织的Toll样受体基因表达变化研究

为研究不同类型Toll样受体基因在凡纳滨对虾免疫调控机制中的作用,实验首先通过荧光定量PCR方法检测了凡纳滨对虾3种Toll样受体基因在不同组织中的表达情况。结果表明凡纳滨对虾3种Toll样受体基因m RNA在各组织中均有表达。其中,Toll1基因在肌肉,血淋巴,心脏和鳃均有较高表达,心脏表达量最高;Toll2基因在血淋巴,心脏和鳃均有较高表达,其中在鳃表达量最高;Toll3基因在鳃和心脏有较高表达,其中在鳃表达量最高。实验还对人工感染溶藻弧菌及白斑综合症病毒后凡纳滨对虾3种Toll样受体基因在不同免疫组织的表达变化差异进行研究。感染白斑综合症病毒后凡纳滨对虾血淋巴及鳃中3种Toll样受体基因表达量均显著提高,并在各自达到表达峰值后逐渐下降直至恢复到感染前水平。感染溶藻弧菌后凡纳滨对虾血淋巴中3种Toll样受体基因表达量均显著提高;鳃中Toll1及Toll3表达量分别于感染后3h和12h有显著提高,而Toll2表达量无显著提高。由此推测3种Toll样受体基因均可能参与白斑综合症病毒感染所引起的免疫调控;而在溶藻弧菌感染所引起的免疫调控中,除了Toll1,Toll3参与鳃的免疫调控外,Toll2基因还参与血淋巴中的先天性免疫调控。长期感染白斑综合症病毒或溶藻弧菌后,凡纳滨对虾3种Toll样受体基因在血淋巴与鳃中的表达量均显著升高,这可能与虾体在长期感染过程中,需要不断保持较高免疫水平有关。     

Use of a three‐dimensional laser scanner to digitally capture the topography of sand dunes in high spatial resolution

We herein report the results of a ?eld study that was designed to test the feasibility of using ground‐based LIDAR to map the topography of a sand dune in high spatial resolution. A portable Cyrax 2500 three‐dimensional (3D) laser scanner was used to digitally capture the topography of a barchan, roughly 4 m tall and 50 m long, located in the White Sands National Monument, New Mexico. We performed eleven scans around the barchan and obtained the elevation relative to the inter‐dune ?at at roughly ¹/₄ million points on the dune surface. The elevation point data were then interpolated to yield a continuous surface model of the dune topography with c. 10 cm spatial resolution and c. 6 mm position accuracy. The results from this ?eld study clearly demonstrate the potential of ground‐based LIDAR as a mapping tool for use in aeolian research and other earth science applications. The 3D surface model of the dune can describe the morphology with hitherto unprecedented detail. Moreover, the surface of the dune is mapped with a minimum of foot traf?c on the dune itself. Copyright © 2004 John Wiley & Sons, Ltd.