Drivers for spatial modelling of a critically endangered seabird on a dynamic ocean area: Balearic shearwaters are non-vegetarian

1. Spatial modelling is an important research tool to improve our knowledge about the distribution of wildlife in the ocean. Using different modelling techniques (MaxEnt and a generalized linear mixed model), a predictive habitat suitability model was developed for one of the most threatened seabirds in the world: the Balearic shearwater, Puffinus mauretanicus.
2. Models were developed using a 10-year dataset from the Gulf of Cádiz (on the south-western Iberian Peninsula), a key foraging area for Balearic shearwaters during migration and the non-breeding season.
3. Predictive habitat maps strongly matched the observed distribution patterns, pointing to bathymetric features as the main modelling drivers. The species was concentrated on shallow areas (up to approximately 100 m in depth) of the continental shelf, very close to the mouth of the Guadalquivir River. In contrast with previous studies, Balearic shearwater distribution in the highly dynamic Gulf of Cádiz was not correlated with areas of high chlorophyll a concentration.
4. This lack of spatial correlation probably arises from the delay between the phytoplankton bloom and the response of the zooplankton and small fish that are preyed upon by Balearic shearwaters, which may result in important displacements of this trophic chain across the Gulf of Cádiz.
5. The analysis presented contributes to a better understanding of the spatial distribution and ecology of the critically endangered top predator in the Gulf of Cádiz and offers important information to improve management plans.

     

Assessment of the effect of silver nanoparticles on the relevant soil protozoan genus Acanthamoeba

Silver nanoparticles (AgNP) are used in a broad range of consumer products and industrial applications. During the regular product life cycle and disposal, AgNP are continuously released into the environment. Hence, the aim of this study was to investigate the potential ecotoxicological effects of AgNP exposure on amoebae. The Acanthamoeba castellanii ATCC 30234 strain and environmental isolate Acanthamoeba strain C5/2, which are both affiliated with genotype T4, were chosen as representatives of ecologically important soil protozoan organisms. The amoebae were exposed to citrate‐stabilized AgNP (30 and 70 nm in size) for 24 h and 96 h at concentrations ranging from 600 µg L⁻¹ to 20 mg L⁻¹. A newly adopted cell culture based microscopic assay was applied to assess the adherence ability of the amoeba trophozoites. The general metabolic activity of Acanthamoeba was determined to be a second independent endpoint by means of intracellular reduction of the redox dye AlamarBlue®. The fate of AgNP within the amoebae and test solutions was visualized by light‐ and transmission electron microscopy (TEM). Both Acanthamoeba strains showed a significant dose‐dependent decrease of adherence ability (p  < 0.04) and metabolic activity (p < 0.01) after 96 h of AgNP exposure. The environmental Acanthamoeba strain C5/2 lost both its adherence ability and metabolic activity at lower AgNP concentrations than the type strain, indicating a higher sensitivity to ionic silver. This was confirmed by the application of AgNO₃, provoking a higher effect level in strain C5/2. AgNP was visualized intracellularly by transmission electron microscopy within the cytoplasm of Acanthamoeba . This is the first report to show the ecotoxicological effects of short‐term AgNP exposure on the soil protist Acanthamoeba , causing both changes in the adherence ability and metabolic activity of this amoeba. This combined approach may be a powerful tool in the future for predicting potential harmful ecotoxicological effects of AgNP exposure using soil protozoans.     

利用相对电导率和茎尖水势预报落叶松苗木生活力的研究

本文对落叶松在不同晾晒时间中茎尖水势，相对电导率及苗木生活力的动态变化过程进行了测定。结果表明：茎尖水势，相对电导率确实能反映苗木遇到逆境后对其生活力的影响，用于预报造林成活率和初期生长量具有极强的可靠性。     

财务信息对上市公司高层变动的影响分析

上市公司高层变动受多种因素的影响,经营业绩是其中一个重要因素,能有效反映公司经营绩效的财务信息,对高层变动的影响也是不容忽视的.通过对深市样本公司的高层变动与会计信息的实证分析,进一步证明了不同会计信息对高层变动的影响程度及二者的关系,从而为投资者和管理者及其他财务数据使用者提供有效的参考依据.     

马尾松剪顶容器苗造林生长效果研究

2000年5月，在贵州省荔波县进行了马尾松剪顶容器苗造林试验，2003年1月调查结果，剪顶马尾松容器苗造林与对照比较，树高生长提高39．74％；地径生长提高34．4％；胸径生长提高89．11％；幼树保存率提高0．91％：冠径生长提高34．74％。     

Prediction of the Line Value of a Genotype from a Top Cross with a Single Cross Hybrid

With the assumption of biallelism it is shown that differences in line values of genotypes from a random mating population can be predicted by the differences of values in top cross progenies with a heterozygous tester. This prediction is also valid in the case of multiallelism with a constant degree of dominance for each pair of alleles and if the tester is heterozygous for the more “distant” alleles. With an arbitrary tester, the efficiency of the prediction is affected by the proportion of the loci which are heterozygous for the more distant alleles. However, with the assumptions considered on multiallelism, with partial to complete dominance, the correlation between line value and combining ability with the tester is expected to be high for a large range of the repartition ot the loci. A two tester top cross design using highly complementary lines, could also be used.     

空心多茎株型短季棉施氮效应研究初报

试验研究高光效空心多茎株型短季棉施N效应结果表明 ,强源是空心多茎株型短季棉施N增产的主要原因 ,扩库对产量的作用有限。低N量即显著提高空心多茎株型短季棉皮棉产量 ,继续增施N肥则空心多茎株型短季棉仅对N素表现出较强适应性 ,而未能充分发挥其产量潜力 ,表明产量潜力的发挥需要配套栽培技术的支撑     

谱模

如果R是一个交换环且M是一个有限生成的拓扑模,则M是一个谱模的充分必要条件是对任意m1,m2∈M,存在一个有限生成子模F(∪)Im1Im2M,使得F ≡ Im1Im2M(那就是对每一个K∈Spec(M),K(∪)F当且反当K(∪)Im1 Im,M),其中ImM=miR,Imi(△)R,i=1,2.     

黄土高原旱地苹果高接模式与品种更新技术研究

在黄土高原旱地进行了苹果高接换种技术试验。结果表明,对每公顷栽植1 260株的高密园,宜采用细长纺锤形整形,每公顷栽植834株的中密园宜采用小冠疏层形结构整形;单枝单芽贴干嫁接宜在4月中下旬进行,单芽腹接和地面蹲靠接应提前到3月下旬至4月上旬。细长纺锤形果树宜采用单枝单芽贴干嫁接,单株宜高接11个头,采用单芽腹接宜接12个头,地面蹲靠接以3个头为宜;小冠疏层形嫁接头数以30个较好。嫁接时砧枝截留长度为5～8 cm,嫁接不同枝段芽体接穗以调整平衡树体长势;依据树龄采用不同嫁接方法,1～5年生树选用单芽腹接,5～10年生树采用单芽枝接,11年生以上树宜采用地面蹲靠接;嫁接后采取封闭切口+套塑料袋的效果较好,单芽腹接芽眼包扎1层接树膜效果明显,地面插接及时包严用土培实保护,嫁接成活率平均在93．5％以上。嫁接后同步成形,树体生长旺,树冠恢复能力强,结果早,产量高,该技术已大面积推广应用,效益十分显著。     

玉米疯顶病的传播与防治研究

通过人工诱发，初步证实了来自玉米疯顶病病田的土壤和植株病残体能够传播病害，是疯顶病在当地持续发生的主要原因；但病害的发生必须依赖于田间土壤具有较高的含水量并在玉米幼苗出土前的萌发期田间发生积水。利用杀菌剂进行玉米种子包衣，对疯顶病具有防治作用，其中甲霜灵锰锌的防治效果达到39．9％～51．3％，杀毒矾也有一定的防效，甲霜灵锰锌是今后开展玉米疯顶病田间防治的主要杀菌剂。利用病田淹水诱发方式，初步评价了37份品种的感病性，发现在多数感病品种中，高度感疯顶病的自交系掖478是其亲本之一。对120份玉米品种在病区自然条件下的发病状况进行调查，为避免感疯顶病品种在病害发生区的推广提供了信息。