692 resultados para 1019


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Let M be the completion of the polynomial ring C(z) under bar] with respect to some inner product, and for any ideal I subset of C (z) under bar], let I] be the closure of I in M. For a homogeneous ideal I, the joint kernel of the submodule I] subset of M is shown, after imposing some mild conditions on M, to be the linear span of the set of vectors {p(i)(partial derivative/partial derivative(w) over bar (1),...,partial derivative/partial derivative(w) over bar (m)) K-I] (., w)vertical bar(w=0), 1 <= i <= t}, where K-I] is the reproducing kernel for the submodule 2] and p(1),..., p(t) is some minimal ``canonical set of generators'' for the ideal I. The proof includes an algorithm for constructing this canonical set of generators, which is determined uniquely modulo linear relations, for homogeneous ideals. A short proof of the ``Rigidity Theorem'' using the sheaf model for Hilbert modules over polynomial rings is given. We describe, via the monoidal transformation, the construction of a Hermitian holomorphic line bundle for a large class of Hilbert modules of the form I]. We show that the curvature, or even its restriction to the exceptional set, of this line bundle is an invariant for the unitary equivalence class of I]. Several examples are given to illustrate the explicit computation of these invariants.

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Catalytic activity of a series of potent amide- and amine-based organoselenium compounds are studied in the presence of various aromatic thiols having electron donating and electron withdrawing substituents on the phenyl ring. This study suggests that the antioxidant activities of the synthetic GPx mimics can be significantly increased by the incorporation of a suitable electron donating group on the phenyl ring of an aromatic thiol.

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Compared to our extensive knowledge about the navigation and homing abilities of ants and bees, we know rather little about these phenomena in social wasps. Here, we report the homing abilities of the tropical primitively eusocial wasp Ropalidia marginata and the factors that affect their homing success. To determine from how far these wasps can return to their nests, we transported foragers blindfold and released them at gradually increasing distances from their nests in four cardinal directions. Their homing success was determined by checking their presence on their nests on three consecutive nights. All foragers (56 individuals, 115 releases) returned back from an area of 0.73 +/- A 0.25 km(2) on the day of release (minimal homing area), whereas 83.8 % of the foragers (217 individuals, 420 releases) returned when we enlarged the area of release to 6.22 +/- A 0.66 km(2) around their nests (maximal homing area). Of 66 releases, no wasps returned from beyond the maximal homing area. The minimal homing area might be familiar to the foragers because they probably routinely forage in this area and the maximal homing area represents the maximum distances from which the wasps are capable of returning to their nests, with or without familiarity.

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选择素(selectin)与配体相互作用在诸如炎症反应、肿瘤转移等生物学过程中具有重要作用;作用力影响受体-配体键解离.本文发展了基于光阱技术的新实验方法,用于考察P-选择素(P-selectin)与P-选择素糖蛋白配体-1(P-selectin Glycoprotein Ligand 1, PSGL-1)相互作用的解离过程.采用黏滞力法对光阱刚度系数进行标定,并通过分子在玻璃小球表面的功能化表征,研究力作用下P-selectin/PSGL-1键的解离,得到了在较低加载率(<25 pN/s)下键解离的断裂力分布,发现键的最可几断裂力随加载率而增加.实验结果在较低加载率下补充和验证了已有的结论.

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Este trabajo ha sido realizado dentro del Grupo de Investigación GIU 10–19 “LITTERARVM. Grupo de Investigación en Literatura, Retórica y Tradición Clásica” de la UPV/EHU.

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用温度梯度法生长了直径为75mm大尺寸的Nd:YAG激光晶体,通过退火排除了生长过程中进入晶体的碳原子.用正交偏光显微镜观察了晶体的核心分布以及生长条纹.测试了室温下的吸收谱并利用吸收谱研究了Nd离子在YAG晶体中的分布.比较了温度梯度法与提拉法生长晶体的区别.

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Modern dinoflagellate cysts in surface sediments collected on Santa Cruz Island, Galapagos, are described, along with other palynomorphs such as microforaminiferal linings, tintinnid loricae, copepod eggs and acritarchs including Domasiella-like micro-remains and Halodinium spp. The dinoflagellate cyst assemblages mainly consisted of Spiniferites cf. scabratus (gonyaulacoid) followed by Brigantedinium spp. and Selenopemphix quanta (peridinioids). No gymnodinioid cysts were found. No remarkable differences in cyst composition and densities were recognized between stations. The cyst assemblages were characterized by low species diversity and low cyst concentrations in comparison with the Pacific coast of Guatemala and Peru. CDF Contribution Number 1019.

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