1,138 research outputs found

    Cross sections for production of closed superstrings at high energy colliders in brane world models

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    In brane world string models with large extra dimensions, there are processes where fermion and antifermion (or two gluons) can annihilate producing a light particle (e.g. gluon) carrying transverse momentum and a Kaluza-Klein graviton or an excited closed string that propagates in the extra dimensions. In high energy colliders, this process gives a missing momentum signature. We compute the total cross section for this process within the context of type II superstring theory in the presence of a D brane. This includes all missing energy sources for this string theory model up to s=8M_s^2, and it can be used to put new limits on the string scale M_s.Comment: 18 pages, 3 figures. Reference adde

    Efficient Syntheses of Biobased Terephthalic Acid, p-Toluic Acid, and p-Methylacetophenone via One-Pot Catalytic Aerobic Oxidation of Monoterpene Derived Bio-p-cymene.

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    An efficient elevated-pressure catalytic oxidative process (2.5 mol % Co(NO3)2, 2.5 mol % MnBr2, air (30 bar), 125 °C, acetic acid, 6 h) has been developed to oxidize p-cymene into crystalline white terephthalic acid (TA) in ∼70% yield. Use of this mixed Co2+/Mn2+ catalytic system is key to obtaining high 70% yields of TA at relatively low reaction temperatures (125 °C) in short reaction times (6 h), which is likely to be due to the synergistic action of bromine and nitrate radicals in the oxidative process. Recycling studies have demonstrated that the mixed metal catalysts present in recovered mother liquors could be recycled three times in successive p-cymene oxidation reactions with no loss in catalytic activity or TA yield. Partial oxidation of p-cymene to give p-methylacetophenone (p-MA) in 55-60% yield can be achieved using a mixed CoBr2/Mn(OAc)2 catalytic system under 1 atm air for 24 h, while use of Co(NO3)2/MnBr2 under 1 atm O2 for 24 h gave p-toluic acid in 55-60% yield. Therefore, access to these simple catalytic aerobic conditions enables multiple biorenewable bulk terpene feedstocks (e.g., crude sulfate turpentine, turpentine, cineole, and limonene) to be converted into synthetically useful bio-p-MA, bio-p-toluic acid, and bio-TA (and hence bio-polyethylene terephthalate) as part of a terpene based biorefinery

    T Cell Migration from Inflamed Skin to Draining Lymph Nodes Requires Intralymphatic Crawling Supported by ICAM-1/LFA-1 Interactions.

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    T cells are the most abundant cell type found in afferent lymph, but their migration through lymphatic vessels (LVs) remains poorly understood. Performing intravital microscopy in the murine skin, we imaged T cell migration through afferent LVs in vivo. T cells entered into and actively migrated within lymphatic capillaries but were passively transported in contractile collecting vessels. Intralymphatic T cell number and motility were increased during contact-hypersensitivity-induced inflammation and dependent on ICAM-1/LFA-1 interactions. In vitro, blockade of endothelial cell-expressed ICAM-1 reduced T cell adhesion, crawling, and transmigration across lymphatic endothelium and decreased T cell advancement from capillaries into lymphatic collectors in skin explants. In vivo, T cell migration to draining lymph nodes was significantly reduced upon ICAM-1 or LFA-1 blockade. Our findings indicate that T cell migration through LVs occurs in distinct steps and reveal a key role for ICAM-1/LFA-1 interactions in this process

    Water-Quality and -Quantity Data for Abandoned Underground Coal Mines in Eastern Kentucky

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    Water-quality and -quantity analyses were performed between 1997 and 2003 by the Kentucky Geological Survey under contract from the Kentucky River Authority and the Kentucky Infrastructure Authority to study abandoned underground coal mines as possible water supplies for communities in the Eastern Kentucky Coal Field. The steep terrain of the coal field limits surface-water supplies, and groundwater systems are difficult to locate and often have too low a yield to provide community water supplies. KGS has been working with the Kentucky River Authority, the Kentucky Infrastructure Authority, and local government officials to search for water supplies in abandoned underground coal mines. The data in the appendices of this report are interpreted in Cumbie and others (2006)

    Quantum Theories of Dilaton Gravity

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    Quantization of two-dimensional dilaton gravity coupled to conformal matter is investigated. Working in conformal gauge about a fixed background metric, the theory may be viewed as a sigma model whose target space is parameterized by the dilaton ϕ\phi and conformal factor ρ\rho. A precise connection is given between the constraint that the theory be independent of the background metric and conformal invariance of the resulting sigma model. Although the action is renormalizable, new coupling constants must be specified at each order in perturbation theory in order to determine the quantum theory. These constants may be viewed as initial data for the beta function equations. It is argued that not all choices of this data correspond to physically sensible theories of gravity, and physically motivated constraints on the data are discussed. In particular a recently constructed subclass of initial data which reduces the full quantum theory to a soluble Liouville-like theory has energies unbounded from below and thus is unphysical. Possibilities for modifying this construction so as to avoid this difficulty are briefly discussed.Comment: 20 pages (Major additions made, including 5 pages on the relation between conformal invariance and background independence.

    Targeted muscle reinnervation for the management of pain in the setting of major limb amputation

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    The life altering nature of major limb amputations may be further complicated by neuroma formation in up to 60% of the estimated 2 million major limb amputees in the United States. This can be a source of pain and functional limitation of the residual limb. Pain associated with neuromas may limit prosthetic limb use, require reoperation, lead to opioid dependence, and dramatically reduce quality of life. A number of management options have been described including excision alone, excision with repair, excision with transposition, and targeted muscle reinnervation. Targeted muscle reinnervation has been shown to reduce phantom limb and neuroma pain for patients with upper and lower extremity amputations. It may be performed at the time of initial amputation to prevent pain development or secondarily for the treatment of established pain. Encouraging outcomes have been reported, and targeted muscle reinnervation is emerging as a leading surgical technique for pain prevention in patients undergoing major limb amputations and pain management in patients with pre-existing amputations
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