5,919 research outputs found

    Measuring the Cost-effectiveness of Conservation Auctions Relative to Alternate Policy Mechanisms

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    The principle motivation for using price-discriminating conservation auctions is that they are expected to be significantly more cost-effective than fixed-price mechanisms. This paper measures cost effectiveness for tenders from two rounds of the Auction for Landscape Recovery in Western Australia relative to counterfactual fixed-price mechanisms. If we assume that the bid equals the compliance cost, the auction gives a significant cost saving over fixed-price mechanisms. If instead we assume that bids include an element of rent, fixed-price mechanisms can be more cost effective than the auction. The significance of these results is that a fixed price scheme may achieve a similar level of cost effectiveness to a conservation auction, when one or more of the following apply: compliance costs do not vary significantly between producers, auction bids have a significant element of rent and the auction incurs a significant additional administrative cost.Auctions, conservation, bio-diversity, Environmental Economics and Policy, Q57,

    Approximate Canonical Quantization for Cosmological Models

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    In cosmology minisuperspace models are described by nonlinear time-reparametrization invariant systems with a finite number of degrees of freedom. Often these models are not explicitly integrable and cannot be quantized exactly. Having this in mind, we present a scheme for the (approximate) quantization of perturbed, nonintegrable, time-reparametrization invariant systems that uses (approximate) gauge invariant quantities. We apply the scheme to a couple of simple quantum cosmological models.Comment: 16 pages, Latex, accepted for publication in Int. Jou. Mod. Phys.

    Estimating Urban Residential Water-Demand With Increasing Block Prices: The Case of Perth, Western Australia

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    This study uses panel data at suburb level to estimates the elasticity water demands in Perth, Australia from 1995 to 2005. After deriving the consumer’s water demand under a non-linear budget constraint, we estimate the water demand model, which accounts for how water (and other purchased goods) is used to satisfy fundamental desires of the household. We have applied the specification of price that provided the correctly estimated marginal price from the block tariff structure, and employed a maximum likelihood estimation technique to tackle the endogeneity and heteroskedasticity issues. Our estimation of water demand price elasticities are slightly higher (more elastic) than previous study in Perth, but broadly in line with other estimates in the literature.water demand, water pricing, block pricing, water resource management, household model, Demand and Price Analysis, Resource /Energy Economics and Policy, Q21, Q25 and Q23,

    Entanglement of two qubits in a relativistic orbit

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    The creation and destruction of entanglement between a pair of interacting two-level detectors accelerating about diametrically opposite points of a circular path is investigated. It is found that any non-zero acceleration has the effect of suppressing the vacuum entanglement and enhancing the acceleration radiation thereby reducing the entangling capacity of the detectors. Given that for large accelerations the acceleration radiation is the dominant effect, we investigate the evolution of a two detector system initially prepared in a Bell state using a perturbative mater equation and treating the vacuum fluctuations as an unobserved environment. A general function for the concurrence is obtained for stationary and symmetric worldlines in flatspace. The entanglement sudden death time is computed.Comment: v2: Some typo's fixed, figures compressed to smaller filesize and added some references

    NGC 4314. III. Inflowing Molecular Gas Feeding a Nuclear Ring of Star Formation

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    NGC 4314 is an early-type barred galaxy containing a nuclear ring of recent star formation. We present CO(1-0) interferometer data of the bar and circumnuclear region with 2.3 x 2.2 arcsec spatial resolution and 13 km/s velocity resolution acquired at the Owens Valley Radio Observatory . These data reveal a clumpy circumnuclear ring of molecular gas. We also find a peak of CO inside the ring within 2 arcsec of the optical center that is not associated with massive star formation. We construct a rotation curve from these CO kinematic data and the mass model of Combes et al. (1992). Using this rotation curve, we have identified the location of orbital resonances in the galaxy. Assuming that the bar ends at corotation, the circumnuclear ring of star formation lies between two Inner Lindblad Resonances, while the nuclear stellar bar ends near the IILR. Deviations from circular motion are detected just beyond the CO and H-alpha ring, where the dust lanes along the leading edge of the bar intersect the nuclear ring. These non-circular motions along the minor axis correspond to radially inward streaming motions at speeds of 20 - 90 km/s and clearly show inflowing gas feeding an ILR ring. There are bright HII regions near the ends of this inflow region, perhaps indicating triggering of star formation by the inflow.Comment: 25 pages, uses aasms.sty. 7 Postscript figures, 12 JPEG figures. Figures may be retrieved from ftp://clyde.as.utexas.edu/pub/N4314COfigs.tar.g

    Dynamical excitations in the collision of 2D Bose-Einstein condensates

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    We carry out simulations of the collision of two components of an adiabatically divided, quasi-2D BEC. We identify under, over and critically damped regimes in the dipole oscillations of the components according to the balance of internal and centre-of-mass (c.m.) energies of the components and investigate the creation of internal excitations. We distinguish the behaviour of this system from previous studies of quasi-1D BEC's. In particular we note that the nature of the internal excitations is only essentially sensitive to an initial phase difference between the components in the overdamped regime.Comment: 17 pages, 9 figure

    Simulating quantum transport for a quasi-one-dimensional Bose gas in an optical lattice: the choice of fluctuation modes in the truncated Wigner approximation

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    We study the effect of quantum fluctuations on the dynamics of a quasi-one-dimensional Bose gas in an optical lattice at zero-temperature using the truncated Wigner approximation with a variety of basis sets for the initial fluctuation modes. The initial spatial distributions of the quantum fluctuations are very different when using a limited number of plane-wave (PW), simple-harmonic-oscillator (SHO) and self-consistently determined Bogoliubov (SCB) modes. The short-time transport properties of the Bose gas, characterized by the phase coherence in the PW basis are distinct from those gained using the SHO and SCB basis. The calculations using the SCB modes predict greater phase decoherence and stronger number fluctuations than the other choices. Furthermore, we observe that the use of PW modes overestimates the extent to which atoms are expelled from the core of the cloud, while the use of the other modes only breaks the cloud structure slightly which is in agreement with the experimental observations [1].Comment: 12 pages, 5 figure

    The Mass of HD 38529 c from Hubble Space Telescope Astrometry and High-Precision Radial Velocities

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    (Abridged) Hubble Space Telescope (HST) Fine Guidance Sensor astrometric observations of the G4 IV star HD 38529 are combined with the results of the analysis of extensive ground-based radial velocity data to determine the mass of the outermost of two previously known companions. Our new radial velocities obtained with the Hobby-Eberly Telescope and velocities from the Carnegie-California group now span over eleven years. With these data we obtain improved RV orbital elements for both the inner companion, HD 38529 b and the outer companion, HD 38529 c. We identify a rotational period of HD 38529 (P_{rot}=31.65 +/- 0.17 d) with FGS photometry. We model the combined astrometric and RV measurements to obtain the parallax, proper motion, perturbation period, perturbation inclination, and perturbation size due to HD 38529 c. For HD 38529 c we find P = 2136.1 +/- 0.3 d, perturbation semi-major axis \alpha =1.05 +/-0.06mas,andinclination mas, and inclination i=48.3deg+/4deg.AssumingaprimarymassM=1.48Msun,weobtainacompanionmassMc=17.61.2+1.5MJup,3sigmaabovea13MJupdeuteriumburning,browndwarflowerlimit.DynamicalsimulationsincorporatingthisaccuratemassforHD38529cindicatethatanearSaturnmassplanetcouldexistbetweenthetwoknowncompanions.Wefindweakevidenceofanadditionallowamplitudesignalthatcanbemodeledasaplanetarymass( 0.17M = 48.3 deg +/- 4 deg. Assuming a primary mass M_* = 1.48 M_{sun}, we obtain a companion mass M_c = 17.6 ^{+1.5}_{-1.2} M_{Jup}, 3-sigma above a 13 M_{Jup} deuterium burning, brown dwarf lower limit. Dynamical simulations incorporating this accurate mass for HD 38529 c indicate that a near-Saturn mass planet could exist between the two known companions. We find weak evidence of an additional low amplitude signal that can be modeled as a planetary-mass (~0.17 M_{Jup}) companion at P~194 days. Additional observations (radial velocities and/or Gaia astrometry) are required to validate an interpretation of HD 38529 d as a planetary-mass companion. If confirmed, the resulting HD 38529 planetary system may be an example of a "Packed Planetary System".Comment: Accepted by The Astronomical Journa

    Dynamics of molecular nanomagnets in time-dependent external magnetic fields: Beyond the Landau-Zener-St\"{u}ckelberg model

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    The time evolution of the magnetization of a magnetic molecular crystal is obtained in an external time-dependent magnetic field, with sweep rates in the kT/s range. We present the 'exact numerical' solution of the time dependent Schr\"{o}dinger equation, and show that the steps in the hysteresis curve can be described as a sequence of two-level transitions between adiabatic states. The multilevel nature of the problem causes the transition probabilities to deviate significantly from the predictions of the Landau-Zener-St\"{u}ckelberg model. These calculations allow the introduction of an efficient approximation method that accurately reproduces the exact results. When including phase relaxation by means of an appropriate master equation, we observe an interplay between coherent dynamics and decoherence. This decreases the size of the magnetization steps at the transitions, but does not modify qualitatively the physical picture obtained without relaxation.Comment: 8 pages, 7 figure
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