6,784 research outputs found

    Wave Profile for Anti-force Waves with Maximum Possible Currents

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    In the theoretical investigation of the electrical breakdown of a gas, we apply a one-dimensional, steady state, constant velocity, three component fluid model and consider the electrons to be the main element in propagation of the wave. The electron gas temperature, and therefore the electron gas partial pressure, is considered to be large enough to provide the driving force. The wave is considered to have a shock front, followed by a thin dynamical transition region. Our set of electron fluid-dynamical equations consists of the equations of conservation of mass, momentum, and energy, plus the Poisson\u27s equation. The set of equations is referred to as the electron fluid dynamical equations; and a successful solution therefor must meet a set of acceptable physical conditions at the trailing edge of the wave. For breakdown waves with a significant current behind the shock front, modifications must be made to the set of electron fluid dynamical equations, as well as the shock condition on electron temperature. Considering existence of current behind the shock front, we have derived the shock condition on electron temperature, and for a set of experimentally measured wave speeds, we have been able to find maximum current values for which solutions to our set of electron velocity, electron temperature, and electron number density within the dynamical transition region of the wave

    Attachment, attraction and communication in real and virtual worlds: a study of massively multiplayer online gamers

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    Potential differences between relationships formed in online versus offline venues were explored using an online survey of massively multiplayer online gamers. Participants (N=1654) provided information about two or more relationships (kin, friends, and romantic relationships), indicating whether these had originated in online or offline venues. Attachment, attraction and communication were assessed for each relationship. Relationship security was predicted by attraction, but the effects of venue were limited to avoidance towards online romantic relationships. Personality, gaming motivation, age and sex all made negligible contributions to relationship security. Limitations, including the correlational nature of the data and the high proportion of male participants, as well as suggestions for how relationship research might proceed in an increasingly online world, are discussed

    Design considerations for Surveyor guidance

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    Design considerations for midcourse guidance and terminal descent system of Surveyor lunar soft landing spacecraf

    ALMA 1.3 Millimeter Map of the HD 95086 System

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    Planets and minor bodies such as asteroids, Kuiper-belt objects and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid- and Kuiper-belt analogs. The location of the Kuiper-belt analog is resolved for the first time. The system can be depicted as a broad (ΔR/R\Delta R/R \sim0.84), inclined (30\arcdeg±\pm3\arcdeg) ring with millimeter emission peaked at 200±\pm6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106±\pm6 to 320±\pm20 au with a surface density distribution described by a power law with an index of --0.5±\pm0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming co-planarity with the observed disk.Comment: accepted for publication in A

    Seed Ecology of \u3cem\u3eMicrolaena stipoides\u3c/em\u3e in Grazing Systems of South-Eastern Australia

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    Microlaena stipoides var. stipoides (Labill.) R.Br. (Microlaena) is a tufted C3 native Australian perennial grass with a short rhizome that can form dense lawns. Microlaena has a wide geographic distribution throughout southern Australia, particularly in the temperate, high-rainfall tableland areas (\u3e 550 mm AAR) of south-eastern and western Australia where is considered to be important for the grazing industries because of its extended growing season in higher rainfall areas, persistence over many years and persistence through drought. Although Microlaena has an important role in the stability of grazed native pastures, little is known about this grass in grazed communities. This study focused on phenology, seed rain, seed bank, seed germination and seedling recruitment. The overall aim was to assess the likely importance of seeds for the maintenance of Microlaena within swards where it already exists

    Guidelines for the use of cell lines in biomedical research

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    Cell-line misidentification and contamination with microorganisms, such as mycoplasma, together with instability, both genetic and phenotypic, are among the problems that continue to affect cell culture. Many of these problems are avoidable with the necessary foresight, and these Guidelines have been prepared to provide those new to the field and others engaged in teaching and instruction with the information necessary to increase their awareness of the problems and to enable them to deal with them effectively. The Guidelines cover areas such as development, acquisition, authentication, cryopreservation, transfer of cell lines between laboratories, microbial contamination, characterisation, instability and misidentification. Advice is also given on complying with current legal and ethical requirements when deriving cell lines from human and animal tissues, the selection and maintenance of equipment and how to deal with problems that may arise
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