18,898 research outputs found
Surface-wave group-delay and attenuation kernels
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
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
, 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 -collider, proposing to search in channels
with associated Higgs productions, with the neutral and charged Higgs further
decaying into and , respectively. In the case of neutral Higgs we are
able to probe for the so far uncovered wedge region via . Additionally, we cover the the high range with . The combination of these searches with channels dedicated to
the low region, such as and potentially covers the full range. The search for charged
Higgs has a slightly smaller sensitivity for the moderate region,
but additionally probes for the higher and lower regions with even
greater sensitivity, via . While the LHC will be able
to probe the whole range for Higgs masses of O(1) TeV by combining
these channels, we show that a future 100 TeV -collider has a potential to
push the sensitivity reach up to 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
(, , , , etc.) are also presented.Comment: published versio
A dual catalytic strategy for carbon-phosphorus cross-coupling via gold and photoredox catalysis.
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
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
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
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 m in
diameter), heavier (up to 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.
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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