10,910 research outputs found

    Dynamics of Quantum Noise in a Tunnel Junction under ac Excitation

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    We report the first measurement of the \emph{dynamical response} of shot noise (measured at frequency ω\omega) of a tunnel junction to an ac excitation at frequency ω0\omega_0. The experiment is performed in the quantum regime, ωω0kBT\hbar\omega\sim\hbar\omega_0\gg k_BT at very low temperature T=35mK and high frequency ω0/2π=6.2\omega_0/2\pi=6.2 GHz. We observe that the noise responds in phase with the excitation, but not adiabatically. The results are in very good agreement with a prediction based on a new current-current correlator.Comment: Theory removed. More experimental details. One extra figur

    Regulating Rare Disease: Safely Facilitating Access to Orphan Drugs

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    While approximately one in ten Americans suffers from a rare disease, only 5 percent of rare diseases have a U.S. Food and Drug Administration (FDA) approved treatment. Congressional and regulatory efforts to stimulate the development of rare-disease treatments, while laudable, have not resolved the fundamental issues surrounding rare-disease treatment development. Indeed, small patient populations, incomplete scientific understanding of rare diseases, and high development costs continually limit the availability of rare-disease treatments. To illustrate the struggle of developing and approving safe rare-disease treatments, this Note begins by discussing the approval of Eteplirsen, the first drug approved for treating a rare disease called Duchenne muscular dystrophy. After exploring the current drug regulation system and how this impacts the availability of rare-disease treatments, this Note examines the 21st Century Cures Act’s patient experience data provisions and the currently pending Trickett Wendler Right to Try Act. Ultimately, the unmet therapeutic needs of rare-disease patients can be met while protecting patient safety, this Note reasons that, if carefully implemented, the 21st Century Cures Act and the Trickett Wendler Right to Try Act could work in tandem to safely facilitate patient access to rare-disease treatments

    Magneto-optical Kramers-Kronig analysis

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    We describe a simple magneto-optical experiment and introduce a magneto-optical Kramers-Kronig analysis (MOKKA) that together allow extracting the complex dielectric function for left- and right-handed circular polarizations in a broad range of frequencies without actually generating circularly polarized light. The experiment consists of measuring reflectivity and Kerr rotation, or alternatively transmission and Faraday rotation, at normal incidence using only standard broadband polarizers without retarders or quarter-wave plates. In a common case, where the magneto-optical rotation is small (below \sim 0.2 rad), a fast measurement protocol can be realized, where the polarizers are fixed at 45^\circ with respect to each other. Apart from the time-effectiveness, the advantage of this protocol is that it can be implemented at ultra-high magnetic fields and in other situations, where an \emph{in-situ} polarizer rotation is difficult. Overall, the proposed technique can be regarded as a magneto-optical generalization of the conventional Kramers-Kronig analysis of reflectivity on bulk samples and the Kramers-Kronig constrained variational analysis of more complex types of spectral data. We demonstrate the application of this method to the textbook semimetals bismuth and graphite and also use it to obtain handedness-resolved magneto-absorption spectra of graphene on SiC.Comment: 11 pages, 4 figur

    Assessing the performance of protective winter covers for outdoor marble statuary: pilot investigation

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    Outdoor statuary in gardens and parks in temperate climates has a tradition of being covered during the winter, to protect against external conditions. There has been little scientific study of the environmental protection that different types of covers provide. This paper examines environmental conditions provided by a range of covers used to protect marble statuary at three sites in the UK. The protection required depends upon the condition of the marble. Although statues closely wrapped and with a layer of insulation provide good protection, this needs to be considered against the potential physical damage of close wrapping a fragile deteriorated surface

    Optimal molecular alignment and orientation through rotational ladder climbing

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    We study the control by electromagnetic fields of molecular alignment and orientation, in a linear, rigid rotor model. With the help of a monotonically convergent algorithm, we find that the optimal field is in the microwave part of the spectrum and acts by resonantly exciting the rotation of the molecule progressively from the ground state, i.e., by rotational ladder climbing. This mechanism is present not only when maximizing orientation or alignment, but also when using prescribed target states that simultaneously optimize the efficiency of orientation/alignment and its duration. The extension of the optimization method to consider a finite rotational temperature is also presented.Comment: 14 pages, 12 figure

    Decrypting the cyclotron effect in graphite using Kerr rotation spectroscopy

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    We measure the far-infrared magneto-optical Kerr rotation and reflectivity spectra in graphite and achieve a highly accurate unified microscopic description of all data in a broad range of magnetic fields by taking rigorously the c-axis band dispersion and the trigonal warping into account. We find that the second- and the forth-order cyclotron harmonics are optically almost as strong as the fundamental resonance even at high fields. They must play, therefore, a major role in magneto-optical and magneto-plasmonic applications based on Bernal stacked graphite and multilayer graphene.Comment: 4 pages, 3 figures + Supplemental Materia
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