11,971 research outputs found

    Multimode Phonon Cooling via Three Wave Parametric Interactions with Optical Fields

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    We discuss the possible cooling of different phonon modes via three wave mixing interactions of vibrational and optical modes. Since phonon modes exhibit a variety of dispersion relations or frequency spectra with diverse spatial structures, depending on the shape and size of the sample, we formulate our theory in terms of relevant spatial mode functions for the interacting fields in any given geometry. We discuss the possibility of Dicke like collective effects in phonon cooling and present explicit results for simultaneous cooling of two phonon modes via the anti-Stokes up conversions. We show that the bimodal cooling should be observable experimentally

    Lattice quantum gravity with scalar fields

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    We consider the four-dimensional Euclidean dynamical triangulations lattice model of quantum gravity based on triangulations of S4S^{4}. We couple it minimally to a scalar field in the quenched approximation. Our results suggest a multiplicative renormalization for the mass of the scalar field which is consistent with the shift symmetry of the discretized lattice action. We discuss the possibility of measuring the mass anomalous dimension and the gravitational binding energy between two scalar test particles, where a negative bound state energy would imply that this model has an attractive gravitational force.Comment: 1+6 pages, proceedings for the 36th International Symposium on Lattice Field Theory (22-28 July 2018). v2 -- Added one reference and fixed a typo. Comments welcome

    Notes on Quantum Computation and Information

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    We discuss fundamentals of quantum computing and information - quantum gates, circuits, algorithms, theorems, error correction, and provide collection of QISKIT programs and exercises for the interested reader.Comment: v2: 86 pages, 97 references. Refined the text, fixed several typos, added some text on continuous variables, and added few solved example problems. v1: 72 pages, 76 references. Suggestions, comments, and corrections are very welcome

    Water Leasing: Opportunities and Challenges for Colorado's South Platte Basin

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    Agricultural water is a preferred source for meeting growing demands, but permanent transfers often require formerly irrigated land to be fallowed, removing a key industry from the regional economy. One alternative allows farmers to lease water to cities by fallowing their land on a rotational basis or limiting irrigation to reduce the consumptive use of their cropping operations. A survey of irrigators in Colorado’s South Platte Basin examines the remuneration needed for a farmer to enter into a lease agreement; the amount of water the farmer will release; the provisions desired in a lease agreement; and the characteristics shared by farmers who are willing to lease.water leases, alternatives to permanent water transfers, economic health of rural communities, Community/Rural/Urban Development,

    Is there Evidence for a Hubble bubble? The Nature of Type Ia Supernova Colors and Dust in External Galaxies

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    We examine recent evidence from the luminosity-redshift relation of Type Ia Supernovae (SNe Ia) for the 3σ\sim 3 \sigma detection of a ``Hubble bubble'' -- a departure of the local value of the Hubble constant from its globally averaged value \citep{Jha:07}. By comparing the MLCS2k2 fits used in that study to the results from other light-curve fitters applied to the same data, we demonstrate that this is related to the interpretation of SN color excesses (after correction for a light-curve shape-color relation) and the presence of a color gradient across the local sample. If the slope of the linear relation (β\beta) between SN color excess and luminosity is fit empirically, then the bubble disappears. If, on the other hand, the color excess arises purely from Milky Way-like dust, then SN data clearly favors a Hubble bubble. We demonstrate that SN data give β2\beta \simeq 2, instead of the β4\beta \simeq 4 one would expect from purely Milky-Way-like dust. This suggests that either SN intrinsic colors are more complicated than can be described with a single light-curve shape parameter, or that dust around SN is unusual. Disentangling these possibilities is both a challenge and an opportunity for large-survey SN Ia cosmology.Comment: Further information and data at http://qold.astro.utoronto.ca/conley/bubble/ Accepted for publication in ApJ

    Optical Spectroscopy of Type Ia Supernovae

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    We present 432 low-dispersion optical spectra of 32 Type Ia supernovae (SNe Ia) that also have well-calibrated light curves. The coverage ranges from 6 epochs to 36 epochs of spectroscopy. Most of the data were obtained with the 1.5m Tillinghast telescope at the F. L. Whipple Observatory with typical wavelength coverage of 3700-7400A and a resolution of ~7A. The earliest spectra are thirteen days before B-band maximum; two-thirds of the SNe were observed before maximum brightness. Coverage for some SNe continues almost to the nebular phase. The consistency of the method of observation and the technique of reduction makes this an ideal data set for studying the spectroscopic diversity of SNe Ia.Comment: Accepted for publication in the Astronomical Journal, 109 pages (including data table), 44 figures, full resolution figures at http://www.noao.edu/noao/staff/matheson/Iaspec.ps.g

    Socioeconomic Differences in the Impact of Smoking Tobacco and Alcohol Prices on Smoking in India

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    The threat posed by smoking to health in India is severe. Already 1 in 5 of all adult male deaths and 1 in 20 of all adult female deaths at ages 30-69 are due to smoking and India will soon have 1 million smoking deaths a year. Increasing tobacco prices has been found to be the single most effective method to reduce smoking. Yet, bidis, the most common form of smoked tobacco in India, are largely untaxed, while cigarettes are taxed at about 40% of retail price, well below the 65–80% rate noted by the World Bank in countries with effective tobacco control policies. Moreover, low and stagnant tax rates have occurred in a period in which all tobacco products have become more affordable with income growth. First, we use data from the most recent three consecutive quinquennial National Sample Survey (NSS) rounds (NSS 50, 55 and 61 conducted in 1993/94, 1999/00 and 200/05) and a two-equation system of budget shares and unit values that attempts to correct for quality and measurement error. Second, we pool data from the most recent nine rounds of NSS (NSS 55-57, 59-64, conducted between 1999/00 to 2007/08). Our analyses of single and repeated cross-sections yield own-price elasticity for bidis that are roughly in keeping with existing evidence. We find that a 10% increase in bidi prices would reduce the demand for bidis by about 6 to 9.5%. We find, however, that own-price elasticity for cigarettes in India is substantially larger than previously thought. Our estimates suggest that cigarette users are at least as responsive as bidi users to price changes. On the whole, our analyses suggest that low SES households are likely more responsive to price changes than high SES households. Our analyses also uncovers important and policy-relevant cross-prices effects. Findings from this study provide additional evidence of the effectiveness of tobacco prices at reducing tobacco use.
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