563 research outputs found

    A Topological Reconstruction Theorem for D∞D^{\infty}-Modules

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    In this paper, we prove that any perfect complex of D∞D^{\infty}-modules may be reconstructed from its holomorphic solution complex provided that we keep track of the natural topology of this last complex. This is to be compared with the reconstruction theorem for regular holonomic DD-modules which follows from the well-known Riemann-Hilbert correspondence. To obtain our result, we consider sheaves of holomorphic functions as sheaves with values in the category of ind-Banach spaces and study some of their homological properties. In particular, we prove that a K\"{u}nneth formula holds for them and we compute their Poincar\'{e}-Verdier duals. As a corollary, we obtain the form of the kernels of ``continuous'' cohomological correspondences between sheaves of holomorphic forms. This allows us to prove a kind of holomorphic Schwartz' kernel theorem and to show that D∞=RHomtop(O,O)D^{\infty}=RHomtop(O,O). Our reconstruction theorem is a direct consequence of this last isomorphism. Note that the main problem is the vanishing of the topological Ext's and that this vanishing is a consequence of the acyclicity theorems for DFN spaces which are established in the paper.Comment: 36 pages, LaTeX + AMS and Xy-pic macros. To appear in Duke Math. Journa

    Elucidation of the RamA Regulon in Klebsiella pneumoniae Reveals a Role in LPS Regulation

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    Klebsiella pneumoniae is a significant human pathogen, in part due to high rates of multidrug resistance. RamA is an intrinsic regulator in K. pneumoniae established to be important for the bacterial response to antimicrobial challenge; however, little is known about its possible wider regulatory role in this organism during infection. In this work, we demonstrate that RamA is a global transcriptional regulator that significantly perturbs the transcriptional landscape of K. pneumoniae, resulting in altered microbe-drug or microbe-host response. This is largely due to the direct regulation of 68 genes associated with a myriad of cellular functions. Importantly, RamA directly binds and activates the lpxC, lpxL-2 and lpxO genes associated with lipid A biosynthesis, thus resulting in modifications within the lipid A moiety of the lipopolysaccharide. RamA-mediated alterations decrease susceptibility to colistin E, polymyxin B and human cationic antimicrobial peptide LL-37. Increased RamA levels reduce K. pneumoniae adhesion and uptake into macrophages, which is supported by in vivo infection studies, that demonstrate increased systemic dissemination of ramA overexpressing K. pneumoniae. These data establish that RamA-mediated regulation directly perturbs microbial surface properties, including lipid A biosynthesis, which facilitate evasion from the innate host response. This highlights RamA as a global regulator that confers pathoadaptive phenotypes with implications for our understanding of the pathogenesis of Enterobacter, Salmonella and Citrobacter spp. that express orthologous RamA proteins

    Parent form for higher spin fields on anti-de Sitter space

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    We construct a first order parent field theory for free higher spin gauge fields on constant curvature spaces. As in the previously considered flat case, both Fronsdal's and Vasiliev's unfolded formulations can be reached by two different straightforward reductions. The parent theory itself is formulated using a higher dimensional embedding space and turns out to be geometrically extremely transparent and free of the intricacies of both of its reductions.Comment: 39 pages, LaTeX; misprints corrected, references adde

    Moregrasp: Restoration of Upper Limb Function in Individuals with High Spinal Cord Injury by Multimodal Neuroprostheses for Interaction in Daily Activities

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    The aim of the MoreGrasp project is to develop a noninvasive, multimodal user interface including a brain-computer interface (BCI) for intuitive control of a grasp neuroprosthesis to support individuals with high spinal cord injury (SCI) in everyday activities. We describe the current state of the project, including the EEG system, preliminary results of natural movements decoding in people with SCI, the new electrode concept for the grasp neuroprosthesis, the shared control architecture behind the system and the implementation of a user-centered design

    Early Scottish Monasteries and Prehistory: A Preliminary Dialogue

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    Reflecting oil the diversity of monastic attributes found in the east and west of Britain, the author proposes that prehistoric ritual practice was influential on monastic form. An argument is advanced that this was not based solely oil inspiration Front the landscape, nor oil conservative tradition, but oil the intellectual reconciliation of Christian and non-Christian ideas, with disparate results that account. for the differences in monumentality. Among more general matters tentatively credited with a prehistoric root are the cult of relics, the tonsure and the date of Easter
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