18,476 research outputs found

    Surface-wave group-delay and attenuation kernels

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    We derive both 3-D and 2-D Fréchet sensitivity kernels for surface-wave group-delay and anelastic attenuation measurements. A finite-frequency group-delay exhibits 2-D off-ray sensitivity either to the local phase-velocity perturbation δc/c or to its dispersion ω(∂/∂ω)(δc/c) as well as to the local group-velocity perturbation δC/C. This dual dependence makes the ray-theoretical inversion of measured group delays for 2-D maps of δC/C a dubious procedure, unless the lateral variations in group velocity are extremely smooth

    Heavy Higgs Bosons at 14 TeV and 100 TeV

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    Searching for Higgs bosons beyond the Standard Model (BSM) is one of the most important missions for hadron colliders. As a landmark of BSM physics, the MSSM Higgs sector at the LHC is expected to be tested up to the scale of the decoupling limit of O(1) TeV, except for a wedge region centered around tanβ310\tan\beta \sim 3 -10, which has been known to be difficult to probe. In this article, we present a dedicated study testing the decoupled MSSM Higgs sector, at the LHC and a next-generation pppp-collider, proposing to search in channels with associated Higgs productions, with the neutral and charged Higgs further decaying into tttt and tbtb, respectively. In the case of neutral Higgs we are able to probe for the so far uncovered wedge region via ppbbH/Abbttpp\to bb H/A \to bbtt. Additionally, we cover the the high tanβ\tan\beta range with ppbbH/Abbττpp\to bb H/A \to bb\tau\tau. The combination of these searches with channels dedicated to the low tanβ\tan\beta region, such as ppH/Attpp\to H/A \to tt and ppttH/Attttpp\to tt H/A \to tttt potentially covers the full tanβ\tan\beta range. The search for charged Higgs has a slightly smaller sensitivity for the moderate tanβ\tan\beta region, but additionally probes for the higher and lower tanβ\tan\beta regions with even greater sensitivity, via pptbH±tbtbpp\to tb H^\pm \to tbtb. While the LHC will be able to probe the whole tanβ\tan\beta range for Higgs masses of O(1) TeV by combining these channels, we show that a future 100 TeV pppp-collider has a potential to push the sensitivity reach up to O(10)\sim \mathcal O(10) TeV. In order to deal with the novel kinematics of top quarks produced by heavy Higgs decays, the multivariate Boosted Decision Tree (BDT) method is applied in our collider analyses. The BDT-based tagging efficiencies of both hadronic and leptonic top-jets, and their mutual fake rates as well as the faking rates by other jets (hh, ZZ, WW, bb, etc.) are also presented.Comment: published versio

    A dual catalytic strategy for carbon-phosphorus cross-coupling via gold and photoredox catalysis.

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    A new method for the P-arylation of aryldiazonium salts with H-phosphonates via dual gold and photoredox catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives, and offers an efficient approach to arylphosphonates. The reaction is proposed to proceed through a photoredox-promoted generation of an electrophilic arylgold(III) intermediate that undergoes coupling with the H-phosphonate nucleophile

    COMMODITY ADVERTISING, IMPORTS AND THE FREE RIDER PROBLEM

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    Advertising without supply control in the U.S. orange juice industry illustrates the import dimension of the free rider problem. Estimates of supply response to advertising are offered for "Florida-grown" orange juice, as well as for U.S. orange juice imports into both Florida and other U.S. ports.International Relations/Trade, Marketing,

    CITRUS EXPORT MARKET DEVELOPMENT AND MAINTENANCE

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    The marketing of agricultural commodities and food products has assumed an international dimension over the past two decades. Increased funding of export development programs by the federal government and commodity organizations suggest the need for improved understanding of U.S. export development programs and of the issues associated with export market development and maintenance. The lesson to be learned from the citrus industry experience is that unless the commodity or food product being promoted can be differentiated from other competitive products, or unless the product is priced lower than competitive products, or unless the product is priced lower than competitive products, the long-run effectiveness of export promotion programs will be limited.International Relations/Trade,

    Simultaneous cooling of coupled mechanical oscillators using whispering gallery mode resonances

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    We demonstrate simultaneous center-of-mass cooling of two coupled oscillators, consisting of a microsphere-cantilever and a tapered optical fiber. Excitation of a whispering gallery mode (WGM) of the microsphere, via the evanescent field of the taper, provides a transduction signal that continuously monitors the relative motion between these two microgram objects with a sensitivity of 3 pm. The cavity enhanced optical dipole force is used to provide feedback damping on the motion of the micron-diameter taper, whereas a piezo stack is used to damp the motion of the much larger (up to 180μ180\,\mum in diameter), heavier (up to 1.5×1071.5\times 10^{-7}\,kg) and stiffer microsphere-cantilever. In each feedback scheme multiple mechanical modes of each oscillator can be cooled, and mode temperatures below 10 K are reached for the dominant mode, consistent with limits determined by the measurement noise of our system. This represents stabilization on the picometer level and is the first demonstration of using WGM resonances to cool the mechanical modes of both the WGM resonator and its coupling waveguide.Comment: 10 pages, 8 figure

    Episodic neurologic disorders: syndromes, genes, and mechanisms.

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    Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities
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