10,197 research outputs found

    Optimization of Cutaneous Electrically Mediated Plasmid DNA Delivery Using Novel Electrode

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    The easy accessibility of skin makes it an excellent target for gene transfer protocols. To take advantage of skin as a target for gene transfer, it is important to establish an efficient and reproducible delivery system. Electroporation is an established technique for enhancing plasmid delivery to many tissues in vivo. A critical component of this technique is the electrode configuration. Electroporation parameters were optimized for transgene expression with minimal tissue damage with a novel electrode. The highest transgene expression and efficiency of individual cell transformation with minimal damage was produced with eight 150 ms pulses at field strength of 100 V/cm. This electrode design offers the potential for easier and more reproducible electrically mediated cutaneous plasmid delivery than the simple electrodes currently commercially available. This electrode can be a valuable tool in determining the applicability of electrically mediated cutaneous gene transfer

    Towards a paradigm SWITCH: Integrating urban water management in Belo Horizonte, Brazil.

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    A prime objective of an integrated, holistic approach is to deliver more effective provision of water resource services carrying minimum risks and improved sustainability. This is the core mission of the 6th EU Framework project, “Sustainable Water Management to Improve Tomorrow’s Cities’ Health” (SWITCH). The focus of the innovative management approach will be centred in demonstration cities such as Belo Horizonte in Brazil, through the formation of strategic Learning Alliances (LAs) comprising organisations having a shared interest in and vision of future urban water management. The paper explores both the LA formation and the challenges to be faced in the negotiating process which will be concerned with expected issues and “pay-offs”, as well as opportunities and difficulties especially related to feasibility as opposed to sustainability

    Antiferromagnetic Order in MnO Spherical Nanoparticles

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    We have performed unpolarized and polarized neutron diffraction experiments on monodisperse 8 nm and 13 nm antiferromagnetic MnO nanoparticles. For the 8 nm sample, the antiferromagnetic transition temperature TNT_N (114 K) is suppressed compared to the bulk material (119 K) while for the 13 nm sample TNT_N (120 K) is comparable to the bulk. The neutron diffraction data of the nanoparticles is well described using the bulk MnO magnetic structure but with a substantially reduced average magnetic moment of 4.2±\pm0.3 μB\mu_B/Mn for the 8 nm sample and 3.9±\pm0.2 μB\mu_B/Mn for the 13 nm sample. An analysis of the polarized neutron data on both samples shows that in an individual MnO nanoparticle about 80% of Mn ions order. These results can be explained by a structure in which the monodisperse nanoparticles studied here have a core that behaves similar to the bulk with a surface layer which does not contribute significantly to the magnetic order.Comment: 7 pages, 5 figure

    Heavy-Light Decay Constants: Conclusions from the Wilson Action

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    We report on the results of a MILC collaboration calculation of fBf_B, fBsf_{B_s}, fDf_D, fDsf_{D_s} and their ratios. We discuss the most important errors in more detail than we have elsewhere.Comment: LATTICE98(heavyqk) 3 latex pages and 3 postscript figures. The perturbative correction calculated by Kuramashi has been adjusted to take into account the fact that we match to the continuum at the kinetic mass of the heavy meson, not the pole mass. This produces a 2 to 4 MeV change in final results for decay constants, and has negligible effect on decay constant ratio

    Государственная поддержка малого бизнеса

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    Выпускная квалификационная работа содержит 90, 3 рисунка, 20 таблицы, 77 источников, приложений. Ключевые слова: малый бизнес, методы стимулирования, государственная поддержка. Объектом исследования является малый бизнес. Цель работы - оценка эффективности государственной поддержки В процессе исследования проанализирован, малый бизнес в современной экономике и опыт зарубежных стран, статистические данные, рассмотрены и выявлены основные, наиболее часто встречаемые проблемы при управлении и малого бизнеса рубежом, а также методы повышения эффективности управления с современной экономике В результате исследования охарактеризована экономическая сущность малых предприятий, изучены ее формы, проанализированы проблемы эффективного использования малого бизнеса в РФ и за рубежом, изучены особеFinal qualifying work contains 90, 3 figures, 20 tables, 77 sources, applications. Keywords: small business, promotion methods, the state support. The object of this study is the small business. Purpose - to estimate the effectiveness of state support The study analyzed a small business in today's economy and foreign experience, statistics, examined and identified the main, the most frequently encountered problems in the management and small business abroad, as well as methods to improve management efficiency with the modern economy The study characterized the economic essence of small enterprises, studied its shape, analyzed the problem of effective use of the small business in Russia and abroad, studied management features small Russian business, explored ways and methods to improve th

    Instantons revisited: dynamical tunnelling and resonant tunnelling

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    Starting from trace formulae for the tunnelling splittings (or decay rates) analytically continued in the complex time domain, we obtain explicit semiclassical expansions in terms of complex trajectories that are selected with appropriate complex-time paths. We show how this instanton-like approach, which takes advantage of an incomplete Wick rotation, accurately reproduces tunnelling effects not only in the usual double-well potential but also in situations where a pure Wick rotation is insufficient, for instance dynamical tunnelling or resonant tunnelling. Even though only one-dimensional autonomous Hamiltonian systems are quantitatively studied, we discuss the relevance of our method for multidimensional and/or chaotic tunnelling

    The 1/N-expansion, quantum-classical correspondence and nonclassical states generation in dissipative higher-order anharmonic oscillators

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    We develop a method for the determination of thecdynamics of dissipative quantum systems in the limit of large number of quanta N, based on the 1/N-expansion of Heidmann et al. [ Opt. Commun. 54, 189 (1985) ] and the quantum-classical correspondence. Using this method, we find analytically the dynamics of nonclassical states generation in the higher-order anharmonic dissipative oscillators for an arbitrary temperature of a reservoir. We show that the quantum correction to the classical motion increases with time quadratically up to some maximal value, which is dependent on the degree of nonlinearity and a damping constant, and then it decreases. Similarities and differences with the corresponding behavior of the quantum corrections to the classical motion in the Hamiltonian chaotic systems are discussed. We also compare our results obtained for some limiting cases with the results obtained by using other semiclassical tools and discuss the conditions for validity of our approach.Comment: 15 pages, RevTEX (EPSF-style), 3 figs. Replaced with final version (stylistic corrections

    The influence of surface stress on the equilibrium shape of strained quantum dots

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    The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, strained islands with sizes >= 10,000 atoms) grown on a GaAs (001) substrate are studied using a hybrid approach which combines density functional theory (DFT) calculations of microscopic parameters, surface energies, and surface stresses with elasticity theory for the long-range strain fields and strain relaxations. In particular we report DFT calculations of the surface stresses and analyze the influence of the strain on the surface energies of the various facets of the quantum dot. The surface stresses have been neglected in previous studies. Furthermore, the influence of edge energies on the island shapes is briefly discussed. From the knowledge of the equilibrium shape of these islands, we address the question whether experimentally observed quantum dots correspond to thermal equilibrium structures or if they are a result of the growth kinetics.Comment: 7 pages, 8 figures, submitted to Phys. Rev. B (February 2, 1998). Other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

    Reversible Metal-Semiconductor Transition of ssDNA-Decorated Single-Walled Carbon Nanotubes

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    A field effect transistor (FET) measurement of a SWNT shows a transition from a metallic one to a p-type semiconductor after helical wrapping of DNA. Water is found to be critical to activate this metal-semiconductor transition in the SWNT-ssDNA hybrid. Raman spectroscopy confirms the same change in electrical behavior. According to our ab initio calculations, a band gap can open up in a metallic SWNT with wrapped ssDNA in the presence of water molecules due to charge transfer.Comment: 13 pages, 6 figure

    Semiclassical Inequivalence of Polygonalized Billiards

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    Polygonalization of any smooth billiard boundary can be carried out in several ways. We show here that the semiclassical description depends on the polygonalization process and the results can be inequivalent. We also establish that generalized tangent-polygons are closest to the corresponding smooth billiard and for de Broglie wavelengths larger than the average length of the edges, the two are semiclassically equivalent.Comment: revtex, 4 ps figure
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