2,064 research outputs found

    Welcome to Fabulous Las Vegas: The Nevada Gaming Regulatory Response to Sovereign Wealth Fund Investment

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    The bulk of recent scholarly work surrounding sovereign wealth funds ( SWFs ) is dedicated to assessing the federal regulatory systems’ adequacy—or likely, inadequacy—in dealing with issues unique to SWF investment. However, the federal regulatory system has not been the only regulatory body to deal with SWF investment in the United States. In 2008, one of the United Arab Emirates’ (“UAE”) SWFs, Dubai World, made a large investment into the Nevada gaming industry and was found suitable to purchase up to twenty percent of MGM Mirage’s stock. This article will address how the Nevada gaming regulatory system has found an effective way to deal with SWF investment in a manner that maintains an open market welcoming to foreign direct investment yet avoids compromising Nevada’s stringent gaming investment standards

    Clinical ophthalmic ultrasound improvements

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    The use of digital synthetic aperture techniques to obtain high resolution ultrasound images of eye and orbit was proposed. The parameters of the switched array configuration to reduce data collection time to a few milliseconds to avoid eye motion problems in the eye itself were established. An assessment of the effects of eye motion on the performance of the system was obtained. The principles of synthetic techniques are discussed. Likely applications are considered

    Molecular cavity optomechanics: a theory of plasmon-enhanced Raman scattering

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    The conventional explanation of plasmon-enhanced Raman scattering attributes the enhancement to the antenna effect focusing the electromagnetic field into sub-wavelength volumes. Here we introduce a new model that additionally accounts for the dynamical and coherent nature of the plasmon-molecule interaction and thereby reveals an enhancement mechanism not contemplated before: dynamical backaction amplification of molecular vibrations. We first map the problem onto the canonical model of cavity optomechanics, in which the molecular vibration and the plasmon are \textit{parametrically coupled}. The optomechanical coupling rate, from which we derive the Raman cross section, is computed from the molecules Raman activities and the plasmonic field distribution. When the plasmon decay rate is comparable or smaller than the vibrational frequency and the excitation laser is blue-detuned from the plasmon onto the vibrational sideband, the resulting delayed feedback force can lead to efficient parametric amplification of molecular vibrations. The optomechanical theory provides a quantitative framework for the calculation of enhanced cross-sections, recovers known results, and enables the design of novel systems that leverage dynamical backaction to achieve additional, mode-selective enhancement. It yields a new understanding of plasmon-enhanced Raman scattering and opens a route to molecular quantum optomechanics.Comment: Extensively revised and improved version thanks to the hard work and constructive comments of a careful Referee. Includes Supplemental Materia

    Constraints on Association of Single-pulse Gamma-ray Bursts and Supernovae

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    We explore the hypothesis, similar to one recently suggested by Bloom and colleagues, that some nearby supernovae are associated with smooth, single-pulse gamma-ray bursts, possibly having no emission above ~ 300 keV. We examine BATSE bursts with durations longer than 2 s, fitting those which can be visually characterized as single-pulse events with a lognormal pulse model. The fraction of events that can be reliably ascertained to be temporally and spectrally similar to the exemplar, GRB 980425 - possibly associated with SN 1998bw - is 4/1573 or 0.25%. This fraction could be as high as 8/1573 (0.5%) if the dimmest bursts are included. Approximately 2% of bursts are morphologically similar to GRB 980425 but have emission above ~ 300 keV. A search of supernova catalogs containing 630 detections during BATSE's lifetime reveals only one burst (GRB 980425) within a 3-month time window and within the total 3-sigma BATSE error radius that could be associated with a type Ib/c supernova. There is no tendency for any subset of single-pulse GRBs to fall near the Supergalactic Plane, whereas SNe of type Ib/c do show this tendency. Economy of hypotheses leads us to conclude that nearby supernovae generally are not related to smooth, single-pulse gamma-ray bursts.Comment: 25 pages, 5 figure

    Events in the life of a cocoon surrounding a light, collapsar jet

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    According to the collapsar model, gamma-ray bursts are thought to be produced in shocks that occur after the relativistic jet has broken free from the stellar envelope. If the mass density of the collimated outflow is less than that of the stellar envelope, the jet will then be surrounded by a cocoon of relativistic plasma. This material would itself be able to escape along the direction of least resistance, which is likely to be the rotation axis of the stellar progenitor, and accelerate in approximately the same way as an impulsive fireball. We discuss how the properties of the stellar envelope have a decisive effect on the appearance of a cocoon propagating through it. The relativistic material that accumulated in the cocoon would have enough kinetic energy to substantially alter the structure of the relativistic outflow, if not in fact provide much of the observed explosive power. Shock waves within this plasma can produce gamma-ray and X-ray transients, in addition to the standard afterglow emission that would arise from the deceleration shock of the cocoon fireball.Comment: 16 pages, 5 figures, slightly revised version, accepted for publication in MNRA

    Evaluation of music-theatre suitable for non-professional production published in the years 1950-1960

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    Thesis (M.M.)--Boston UniversityIt was the purpose of this study to construct criteria for use as a guide for the evaluation of the dramatic and musical contents of operas, operettas, musical comedies, and other music-dramatic productions, as well as their sustainability for production in non-professional situations; and to apply these criteria to publications written or revised within the period 1950-1960

    Delayed soft X-ray emission lines in the afterglow of GRB 030227

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    Strong, delayed X-ray line emission is detected in the afterglow of GRB 030227, appearing near the end of the XMM-Newton observation, nearly twenty hours after the burst. The observed flux in the lines, not simply the equivalent width, sharply increases from an undetectable level (<1.7e-14 erg/cm^2/s, 3 sigma) to 4.1e-14 erg/cm^2/s in the final 9.7 ks. The line emission alone has nearly twice as many detected photons as any previous detection of X-ray lines. The lines correspond well to hydrogen and/or helium-like emission from Mg, Si, S, Ar and Ca at a redshift z=1.39. There is no evidence for Fe, Co or Ni--the ultimate iron abundance must be less than a tenth that of the lighter metals. If the supernova and GRB events are nearly simultaneous there must be continuing, sporadic power output after the GRB of a luminosity >~5e46 erg/s, exceeding all but the most powerful quasars.Comment: Submitted to ApJL. 14 pages, 3 figures with AASLaTe

    Fireballs Loading and the Blast Wave Model of Gamma Ray Bursts

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    A simple function for the spectral power P(Ï”,t)â‰ĄÎœL(Îœ)P(\epsilon,t) \equiv \nu L(\nu) is proposed to model, with 9 parameters, the spectral and temporal evolution of the observed nonthermal synchrotron power flux from GRBs in the blast wave model. Here Ï”=hÎœ/\epsilon = h\nu/me_ec2^2 is the observed dimensionless photon energy and tt is the observing time. Assumptions and an issue of lack of self-consistency are spelled out. The spectra are found to be most sensitive to the baryon loading, expressed in terms of the initial bulk Lorentz factor Γ0\Gamma_0, and an equipartition term qq which is assumed to be constant in time and independent of Γ0\Gamma_0. Expressions are given for the peak spectral power Pp(t)=P(Ï”p,t)P_p(t) = P(\epsilon_p,t) at the photon energy Ï”=Ï”p(t)\epsilon = \epsilon_p(t) of the spectral power peak. A general rule is that the total fireball particle kinetic energy E0∌Π0tdE_0 \sim \Pi_0 t_d, where td∝Γ0−8/3t_d \propto \Gamma_0^{-8/3} is the deceleration time scale and Π0≡P(Ï”p,td)∝Γ08/3\Pi_0 \equiv P(\epsilon_p,t_d) \propto \Gamma_0^{8/3} is the maximum measured bolometric power output in radiation, during which it is carried primarily by photons with energy E0=Ï”p(td)∝qΓ04{\cal E}_0 = \epsilon_p(t_d) \propto q\Gamma_0^4.Comment: 26 pages, including 4 figures, uses epsf.sty, rotate.sty; submitted to ApJ; revised version with extended introduction, redrawn figures, and correction

    Heralded single phonon preparation, storage and readout in cavity optomechanics

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    We analyze theoretically how to use the radiation pressure coupling between a mechanical oscillator and an optical cavity field to generate in a heralded way a single quantum of mechanical motion (a Fock state), and release on-demand the stored excitation as a single photon. Starting with the oscillator close to its ground state, a laser pumping the upper motional sideband leads to dynamical backaction amplification and to the creation of correlated photon-phonon pairs. The detection of one Stokes photon thus projects the macroscopic oscillator into a single-phonon Fock state. The non-classical nature of this mechanical state can be demonstrated by applying a readout laser on the lower sideband (i.e. optical cooling) to map the phononic state to a photonic mode, and by performing an autocorrelation measurement on the anti-Stokes photons. We discuss the relevance of our proposal for the future of cavity optomechanics as an enabling quantum technology.Comment: Accepted for publication in Physical Review Letters. Added References 42,4

    Measurement and control of a mechanical oscillator at its thermal decoherence rate

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    In real-time quantum feedback protocols, the record of a continuous measurement is used to stabilize a desired quantum state. Recent years have seen highly successful applications in a variety of well-isolated micro-systems, including microwave photons and superconducting qubits. By contrast, the ability to stabilize the quantum state of a tangibly massive object, such as a nanomechanical oscillator, remains a difficult challenge: The main obstacle is environmental decoherence, which places stringent requirements on the timescale in which the state must be measured. Here we describe a position sensor that is capable of resolving the zero-point motion of a solid-state, nanomechanical oscillator in the timescale of its thermal decoherence, a critical requirement for preparing its ground state using feedback. The sensor is based on cavity optomechanical coupling, and realizes a measurement of the oscillator's displacement with an imprecision 40 dB below that at the standard quantum limit, while maintaining an imprecision-back-action product within a factor of 5 of the Heisenberg uncertainty limit. Using the measurement as an error signal and radiation pressure as an actuator, we demonstrate active feedback cooling (cold-damping) of the 4.3 MHz oscillator from a cryogenic bath temperature of 4.4 K to an effective value of 1.1±\pm0.1 mK, corresponding to a mean phonon number of 5.3±\pm0.6 (i.e., a ground state probability of 16%). Our results set a new benchmark for the performance of a linear position sensor, and signal the emergence of engineered mechanical oscillators as practical subjects for measurement-based quantum control.Comment: 24 pages, 10 figures; typos corrected in main text and figure
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