9,694 research outputs found

    Dimensional crossover of the fundamental-measure functional for parallel hard cubes

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    We present a regularization of the recently proposed fundamental-measure functional for a mixture of parallel hard cubes. The regularized functional is shown to have right dimensional crossovers to any smaller dimension, thus allowing to use it to study highly inhomogeneous phases (such as the solid phase). Furthermore, it is shown how the functional of the slightly more general model of parallel hard parallelepipeds can be obtained using the zero-dimensional functional as a generating functional. The multicomponent version of the latter system is also given, and it is suggested how to reformulate it as a restricted-orientation model for liquid crystals. Finally, the method is further extended to build a functional for a mixture of parallel hard cylinders.Comment: 4 pages, no figures, uses revtex style files and multicol.sty, for a PostScript version see http://dulcinea.uc3m.es/users/cuesta/cross.p

    Pattern recognition- iv. sequential operations in digital picture processing

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    Sequential approach to digital picture processin

    The Changing Narratives of Death, Dying, and HIV in the United Kingdom

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    Death and infection were closely linked from the start of the HIV epidemic, until successful treatments became available. The initial impact of mostly young, gay men dying from HIV was powerful in shaping UK responses. Neoliberal discourses developed at the same time, particularly focusing on how citizens (rather than the state) should take responsibility to improve health. Subsequently “successful ageing” became an allied discourse, further marginalising death discussions. Our study reflected on a broad range of meanings around death within the historical UK epidemic, to examine how dying narratives shape contemporary HIV experiences. Fifty-one participants including people living with HIV, professionals, and activists were recruited for semistructured interviews. Assuming a symbolic interactionist framework, analysis highlighted how HIV deaths were initially experienced as not only traumatic but also energizing, leading to creativity. With effective antiretrovirals, dying changed shape (e.g., loss of death literacy), and better integration of palliative care was recommended

    Pattern recognition. v- samp - a computer program for estimating surface area from contour maps

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    Fortran computer program for computing linear approximation of surface area for any given portion of digitized contour ma

    Phase behaviour of additive binary mixtures in the limit of infinite asymmetry

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    We provide an exact mapping between the density functional of a binary mixture and that of the effective one-component fluid in the limit of infinite asymmetry. The fluid of parallel hard cubes is thus mapped onto that of parallel adhesive hard cubes. Its phase behaviour reveals that demixing of a very asymmetric mixture can only occur between a solvent-rich fluid and a permeated large particle solid or between two large particle solids with different packing fractions. Comparing with hard spheres mixtures we conclude that the phase behaviour of very asymmetric hard-particle mixtures can be determined from that of the large component interacting via an adhesive-like potential.Comment: Full rewriting of the paper (also new title). 4 pages, LaTeX, uses revtex, multicol, epsfig, and amstex style files, to appear in Phys. Rev. E (Rapid Comm.

    Comprehensive structural model of the mechanochemical cycle of a mitotic motor highlights molecular adaptations in the kinesin family

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    Kinesins are responsible for a wide variety of microtubule-based, ATP-dependent functions. Their motor domain drives these activities but the molecular adaptations that specify these diverse and essential cellular activities are poorly understood. It has been assumed that the first identified kinesin - the transport motor kinesin-1 – is the mechanistic paradigm for the entire superfamily, but accumulating evidence suggests that this is not the case. To address the deficits in our understanding of the molecular basis of functional divergence within the kinesin superfamily, we studied kinesin-5s, which are essential mitotic motors whose inhibition blocks cell division. Using cryo-electron microscopy and subnanometer resolution structure determination, we have visualised conformations of microtubule-bound human kinesin-5 motor domain at successive steps in its ATPase cycle. Following ATP hydrolysis, nucleotide-dependent conformational changes in the active site are allosterically propagated into rotations of the motor domain and uncurling of the drugbinding loop L5. In addition, the mechanical neck-linker element that is crucial for motor stepping undergoes discrete, ordered displacements. We also observed large reorientations of the motor N-terminus that indicate its importance for kinesin-5 function through control of neck-linker conformation. A kinesin-5 mutant lacking this N-terminus is enzymatically active, and ATP-dependent neck-linker movement and motility is defective although not ablated. All these aspects of kinesin-5 mechanochemistry are distinct from kinesin-1. Our findings directly demonstrate the regulatory role of the kinesin-5 N-terminus in collaboration with the motor’s structured neck-linker, and highlight the multiple adaptations within kinesin motor domains that tune their mechanochemistries according to distinct functional requirements
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