23,695 research outputs found

    Rabies on the Last Frontier: A Phylogeographical Look at Red (Vulpus vulpus) and Arctic (Vulpus lagopus) Fox with Respect to Mitochondrial DNA and the Spatial Diffusion of Rabies

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    Vulpus vulpus and Vulpus lagopus are terrestrial animals that live in Alaska. They are also common carriers of the rabies virus. It has been determined that there are three different clades of rabies in Alaska being vectored by these two species of fox, but it is not clear why there are no endemic rabies in the Interior. We are interested in the migration patterns of Vulpus vulpus and Vulpus lagopus, the spread and maintenance of the rabies virus as a function of climate warming. We hypothesize that there is some element, whether biological or geographical, that restricts the virus from spreading into the interior and maintaining itself as much as it does in the coastal regions of Alaska. This research provides a model for determining how the virus spreads under retreating Arctic conditions, as the globe warms

    The Physician and the Sacraments (Extreme Unction)

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    The Physician and the Sacrament of Extreme Unction

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    Inter-CubeSat Communication with V-band "Bull's eye" antenna

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    We present the study of a simple communication scenario between two CubeSats using a V-band “Bull's eye” antenna that we designed for this purpose. The return loss of the antenna has a -10dB bandwidth of 0.7 GHz and a gain of 15.4dBi at 60 GHz. Moreover, the low-profile shape makes it easily integrable in a CubeSat chassis. The communication scenario study shows that, using 0.01W VubiQ modules and V-band “Bull’s eye” antennas, CubeSats can efficiently transmit data within a 500 MHz bandwidth and with a 10-6 BER while being separated by up to 98m, under ideal conditions, or 50m under worst case operating conditions (5° pointing misalignment in E- and H-plane of the antenna, and 5° polarisation misalignment)

    Compaction and mobility in randomly agitated granular assemblies

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    We study the compaction and mobility properties of a dense granular material under weak random vibration. By putting in direct contact millimetric glass beads with piezoelectric transducers we manage to inject energy to the system in a disordered manner with accelerations much smaller than gravity, resulting in a slow compaction dynamics and no convection. We characterize the mobility inside the medium by pulling through it an intruder grain at constant velocity. We present an extensive study of the relation between drag force and velocity for different vibration conditions and sizes of the intruder.Comment: 4 pages, 6 figures, to appear in the proceedings of Powders and Grains 200

    Simulations of Pattern Formation in Vibrated Granular Media

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    We present simulations of peak pattern formation in vibrated two-dimensional (2D) granulates and measure the dispersion relation of the pattern for various frequencies, accelerations, cell sizes, and layer heights. We report the first quantitative data from numerical simulations showing an interesting dependence of the pattern wavelength on the acceleration and the system size. Our results are related to recent experimental findings and theoretical predictions for gravity waves.Comment: 6 pages PS-file including figures, (version accepted at Europhys. Lett. 26.10.96

    Gas core reactors for actinide transmutation and breeder applications

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    This work consists of design power plant studies for four types of reactor systems: uranium plasma core breeder, uranium plasma core actinide transmuter, UF6 breeder and UF6 actinide transmuter. The plasma core systems can be coupled to MHD generators to obtain high efficiency electrical power generation. A 1074 MWt UF6 breeder reactor was designed with a breeding ratio of 1.002 to guard against diversion of fuel. Using molten salt technology and a superheated steam cycle, an efficiency of 39.2% was obtained for the plant and the U233 inventory in the core and heat exchangers was limited to 105 Kg. It was found that the UF6 reactor can produce high fluxes (10 to the 14th power n/sq cm-sec) necessary for efficient burnup of actinide. However, the buildup of fissile isotopes posed severe heat transfer problems. Therefore, the flux in the actinide region must be decreased with time. Consequently, only beginning-of-life conditions were considered for the power plant design. A 577 MWt UF6 actinide transmutation reactor power plant was designed to operate with 39.3% efficiency and 102 Kg of U233 in the core and heat exchanger for beginning-of-life conditions

    Simulations of dense granular flow: Dynamic Arches and Spin Organization

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    We present a numerical model for a two dimensional (2D) granular assembly, falling in a rectangular container when the bottom is removed. We observe the occurrence of cracks splitting the initial pile into pieces, like in experiments. We study in detail various mechanisms connected to the `discontinuous decompaction' of this granular material. In particular, we focus on the history of one single long range crack, from its origin at one side wall, until it breaks the assembly into two pieces. This event is correlated to an increase in the number of collisions, i.e. strong pressure, and to a momentum wave originated by one particle. Eventually, strong friction reduces the falling velocity such that the crack may open below the slow, high pressure `dynamic arch'. Furthermore, we report the presence of large, organized structures of the particles' angular velocities in the dense parts of the granulate when the number of collisions is large.Comment: Submitted to J. Phys.

    Spatially democratic pedagogy: a pedagogical interventionto support children’s design and co-creation of classroomspace. a new trajectory for Froebel’s kindergarten spaces?

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    The Foundation Phase curriculum framework was introduced by the Welsh Government in 2010 (and revised in 2015). It applies to all children aged 3 to 7 years in Wales and includes a number of additional pedagogies and rights based approaches which support more participatory understandings of learning and the child (WG, 2015). However, these additional pedagogies are expected to be played out within existing constructions of space. Dominated by continuous provision, spaces are to include sand, water, writing, construction and role-play. Recently rebranded as "Learning Zones" (Taylor et al, 2015), these spaces are becoming increasingly structured around a centralised concept of space, activity and outcome, creating a paradox by framing both space and pedagogy as prescribed and not participatory. In response this PhD explores Spatially Democratic Pedagogy (Clement, 2017) as an alternative approach to the construction of classroom space. Using Froebel's (1899) communal gardens as the pedagogical blueprint and reflecting them through recent sociomaterial (Fenwick, 2011) and democratic (Moss, 2014) understandings of learning and space, this research aims to support children in the design and co-creation of their classroom space. Its Design Based Research frame (Reimann, 2011) aims to, “solve real-world problems through the design, enactment and analysis of an intervention” (DBR Collective, 2003). Current constructions of classroom space within the Foundation Phase were found to be complicit in restricting children and teachers' ability to participate in learning. Notably, co-creating space with children, based on their designs, appeared to offer opportunities to support participatory practice. This research contends it is the construction of space that is important when considering participatory practice within the Foundation Phase
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