440 research outputs found

    Some Algae of the Upper Cuyahoga River System in Ohio

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    Author Institution: Department of Biological Sciences, Kent State University, Kent, Ohio 44240A qualitative survey of algae was made during June and September, 1967, in three tributaries of the Cuyahoga River in Geauga County: West Branch, East Branch, and Tare Creek. Sixty-four species of algae found in this survey are reported here. Eight species which were collected at the majority of the 14 stations sampled are Cladophora glomerata, Aphanochaete repens, Rhizoclonium hieroglyphicum, Euglena gracilis, Vaucheria sessilis, Tribonema bombycinum, Oscillatoria nigra, and O. limosa

    Temozolomide induces apoptosis and senescence in glioma cells cultured as multicellular spheroids

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    Temozolomide is an alkylating cytostatic drug that finds increasing application in the treatment of melanoma, anaplastic astrocytoma and glioblastoma multiforme. The compound is a prodrug that decomposes spontaneously, independent of an enzymatic activation step. DNA methylation induces futile mismatch repair cycles and depletion of the DNA repair enzyme O6-methylguanine-DNA methyltransferase should then initiate programmed cell death. We show drug-dependent inhibition of tumour growth in a three-dimensional cell culture model of the glioma cell lines U87MG and GaMG. Migrational behaviour of the glioblastoma cells remained unaltered. However, coincubation of tumour spheroids with primary brain aggregates showed reduced tumour cell invasion into brain tissue in the presence of temozolomide. This was not achieved by slowing cellular migration, as temozolomide-treated cells displayed no reduced motility. By transferase-mediated dUTP nick-end labelling (TUNEL) of apoptotic nuclei, we found that the drug was able to induce apoptosis throughout the tumour cell spheroids. Apoptosis was highest in the core region of the spheroids. Repetitive application of sublethal doses of temozolomide to multicellular spheroids resulted in the development of drug resistance in GaMG cells. We suggest that temozolomide is a strong initiator of apoptosis in glioblastoma tumour cells in a spheroid cell culture system, when cells are already in a stressful environment

    Ordering of apolar and polar solutes in nematic solvents

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    The quadrupolar splittings of deuteriated para- and ortho-dichlorobenzene (1,4-DCB and 1,2-DCB, respectively) are measured by nuclear magnetic resonance(NMR) in the nematic solvents hexyl- and pentyloxy-substituted diphenyl diacetylene (DPDA-C6 and DPDA-OC5, respectively). Measurements are taken for all four combinations of the nominally apolar (1,4-DCB) and polar (1,2-DCB) solutes in the apolar (DPDA-C6) and polar (DPDA-OC5) solvents, and throughout the entire nematic temperature range of the solutions. The temperature dependence of the second-rank orientational order parameters of the solutes are obtained from these measurements and the respective order parameters of the mesogenic cores of solvent molecules are obtained independently from carbon-13 NMR measurements. The order parameter profiles of the two solutes are found to be very different but show little variation from one solvent to the other. The results are analyzed and interpreted in terms of the underlying molecular interactions using atomistic solvent–solute potentials. The influence of electrostaticinteractions on solute ordering is directly evaluated by computing the order parameters with and without the electrostatic component of the atomistic potential. It is observed to be small. It is also found that the important interactions in these solvent–solute systems are operative over short intermolecular distances for which the representation of the partial charge distributions in terms of overall molecular dipole and quadrupole moments is not valid

    Инновационные подходы в проектировании городских и районных общественных пространств («Живая лаборатория», г. Томск)

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    Выпускная квалификационная работа рассматривает инновационные подходы в проектировании общественных пространств. Проанализирован российский и зарубежный опыт партисипаторного проектирования и применения геоинформационных систем в городском планировании. На основе исследования сформированы рекомендации для администрации города.The graduate qualification work is dedicated to the innovative approaches in the design of public spaces. The Russian and foreign experience of participatory design and application of geoinformation systems in city planning were analyzed. Guidelines, based on research, have been formed for the city administration

    A Mononuclear and a Mixed-Valence Chain Polymer Arising from Copper(II) Halide Chemistry and the Use of 2,2′-Pyridil

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    Reactions of 2,2′-pyridil (pyCOCOpy) with CuCl2 · 2H2O and CuBr2 in EtOH yielded the mononuclear complex [Cu(pyCOOEt)2Cl2] · H2O (1) and the one-dimensional, mixed-valence complex [Cu2ICuII(pyCOOEt)2Br4]n (2), respectively. Both complexes crystallize in the triclinic space group P 1¯. The lattice constants are a = 8.382(2), b = 9.778(2), c = 7.814(2), α = 101.17(1), β = 114.55(1), γ = 94.14(1)° for 1 and a = 8.738(1), b = 9.375(2), c = 7.966(1), α = 79.09(1), β = 64.25(1), γ = 81.78(1)° for 2. 2,2′-pyridil undergoes a metal-assisted alcoholysis and oxidation leading to decomposition and yielding the ethyl picolinate (pyCOOEt) ligand. The autoredox process associated with the reduction of copper(II) to copper(I) in the case of complex 2 is discussed in terms of the increased redox activity of the copper(II) bromide system relative to the copper(II) chloride system

    An electron correlation originated negative magnetoresistance in a system having a partly flat band

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    Inspired from an experimentally examined organic conductor, a novel mechanism for negative magnetoresistance is proposed for repulsively interacting electrons on a lattice whose band dispersion contains a flat portion (a flat bottom below a dispersive part here). When the Fermi level lies in the flat part, the electron correlation should cause ferromagnetic spin fluctuations to develop with an enhanced susceptibility. A relatively small magnetic field will then shift the majority-spin Fermi level to the dispersive part, resulting in a negative magnetoresistance. We have actually confirmed the idea by calculating the conductivity in magnetic fields, with the fluctuation exchange approximation, for the repulsive Hubbard model on a square lattice having a large second nearest-neighbor hopping.Comment: RevTex, 5 figures in Postscript, to be published in Phys. Rev.

    The future of enterprise groupware applications

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    This paper provides a review of groupware technology and products. The purpose of this review is to investigate the appropriateness of current groupware technology as the basis for future enterprise systems and evaluate its role in realising, the currently emerging, Virtual Enterprise model for business organisation. It also identifies in which way current technological phenomena will transform groupware technology and will drive the development of the enterprise systems of the future

    Towards Canonical Quantum Gravity for G1 Geometries in 2+1 Dimensions with a Lambda--Term

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    The canonical analysis and subsequent quantization of the (2+1)-dimensional action of pure gravity plus a cosmological constant term is considered, under the assumption of the existence of one spacelike Killing vector field. The proper imposition of the quantum analogues of the two linear (momentum) constraints reduces an initial collection of state vectors, consisting of all smooth functionals of the components (and/or their derivatives) of the spatial metric, to particular scalar smooth functionals. The demand that the midi-superspace metric (inferred from the kinetic part of the quadratic (Hamiltonian) constraint) must define on the space of these states an induced metric whose components are given in terms of the same states, which is made possible through an appropriate re-normalization assumption, severely reduces the possible state vectors to three unique (up to general coordinate transformations) smooth scalar functionals. The quantum analogue of the Hamiltonian constraint produces a Wheeler-DeWitt equation based on this reduced manifold of states, which is completely integrated.Comment: Latex 2e source file, 25 pages, no figures, final version (accepted in CQG
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