779 research outputs found

    Property Taxation of Multifamily Housing: An Empirical Analysis of Vertical and Horizontal Equity and Assessment Methods

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    This study used the hedonic price technique to focus on a housing characteristic that has been studied infrequently: whether a home is site-built or manufactured. Two hedonic price regression models were used to determine the predictive power of construction type on home price. The ?rst, which controlled for factors found to relate to home prices in previous research, showed a signi?cant difference between the prices of the two types of homes. The second, which also included other variables through a stepwise regression, found that the type of construction had more predictive power than any other explanatory variable in the model.

    Landau Zener method to study quantum phase interference of Fe8 molecular nanomagnets

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    We present details about an experimental method based on the Landau Zener model which allows to measure very small tunnel splittings Δ\Delta in molecular clusters Fe8. The measurements are performed with an array of micro-SQUIDs. The observed oscillations of Delta as a function of the magnetic field applied along the hard anisotropy axis are explained in terms of topological quantum interference of two tunnel paths of opposite windings. Transitions between M = -S and (S - n), with n even or odd, revealed a parity (symmetry) effect which is analogous to the suppression of tunneling predicted for half integer spins. This observation is the first direct evidence of the topological part of the quantum spin phase (Berry phase) in a magnetic system. The influence of intermolecular dipole interactions on the measured tunnel splittings Δ\Delta are shown.Comment: 6 pages, 14 figures, conference proceedings of MMM 1999, San Jose, 15-18 Nov., session number CD-0

    The effects of nuclear spins on the quantum relaxation of the magnetization for the molecular nanomagnet Fe_8

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    The strong influence of nuclear spins on resonant quantum tunneling in the molecular cluster Fe_8 is demonstrated for the first time by comparing the relaxation rate of the standard Fe_8 sample with two isotopic modified samples: (i) 56_Fe is replaced by 57_Fe, and (ii) a fraction of 1_H is replaced by 2_H. By using a recently developed "hole digging" method, we measured an intrinsic broadening which is driven by the hyperfine fields. Our measurements are in good agreement with numerical hyperfine calculations. For T > 1.5 K, the influence of nuclear spins on the relaxation rate is less important, suggesting that spin-phonon coupling dominates the relaxation rate at higher temperature.Comment: 4 pages, 5 figure

    Journalists in the UK

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    Based on one of the most comprehensive surveys of UK journalists ever carried out, this report describes journalists’ personal characteristics, employment conditions, and working routines. It also analyses journalists’ opinions on: ethics, influences on their work, the trustworthiness of institutions such as parliament and the police, their role in society, and changes in journalism over time. The report includes findings on UK journalism’s: lack of ethnic diversity and of women in senior positions; modest pay, especially for young journalists; and changing employment patterns and working routines in the digital age. It also reveals how journalists, while believing their profession is changing significantly, remain committed to traditional journalistic values; that although they adhere closely to professional codes and standards, UK journalists push ethical boundaries more than some of their international colleagues; and that rather than living up to the stereotype of the cynical hack, journalists in the UK are relatively trusting

    Microwave photon detectors based on semiconducting double quantum dots

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    Detectors of microwave photons find applications in different fields ranging from security to cosmology. Due to the intrinsic difficulties related to the detection of vanishingly small energy quanta ¯hω, significant portions of the microwave electromagnetic spectrum are still uncovered by suitable techniques. No prevailing technology has clearly emerged yet, although different solutions have been tested in different contexts. Here, we focus on semiconductor quantum dots, which feature wide tunability by external gate voltages and scalability for large architectures. We discuss possible pathways for the development of microwave photon detectors based on photon-assisted tunneling in semiconducting double quantum dot circuits. In particular, we consider implementations based on either broadband transmission lines or resonant cavities, and we discuss how developments in charge sensing techniques and hybrid architectures may be beneficial for the development of efficient photon detectors in the microwave range

    Food Price Volatility over the Last Decade in Niger and Malawi: Extent, Sources and Impact on Child Malnutrition

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    Recently, considerable attention has rightly been paid to the nutritional impact of the sharp hikes in international food prices which took place in 2007-8 and, again, in 2010-11. While sacrosanct, this growing focus has somewhat obscured the effect of other factors which do affect malnutrition in the Sub-Saharan Africa context, i.e. the long term impact of agricultural policies, huge and persistent seasonal variation in domestic food prices, and the impact of famines which still regularly stalk the continent. This paper focuses on the relative weight of these factors in explaining child malnutrition (proxied by the number of child admissions to feeding centers) in Malawi and Niger, two prototypical countries in the region. The analysis shows that the drivers of domestic food staple prices and of the ensuing child malnutrition have to be found not only – or not primarily – in the changes of international food prices but mainly in the impact of agricultural policies on food production, the persistence of a strong food price seasonality, and recurrent and often poorly attended famines. Indeed, even during years of declines in international food prices, these factors often exert a huge upward pressures on domestic food prices and child malnutrition

    Macroscopic Quantum Tunneling in Small Antiferromagnetic Particles: Effects of a Strong Magnetic Field

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    We consider an effect of a strong magnetic field on the ground state and macroscopic coherent tunneling in small antiferromagnetic particles with uniaxial and biaxial single-ion anisotropy. We find several tunneling regimes that depend on the direction of the magnetic field with respect to the anisotropy axes. For the case of a purely uniaxial symmetry and the field directed along the easy axis, an exact instanton solution with two different scales in imaginary time is constructed. For a rhombic anisotropy the effect of the field strongly depends on its orientation: with the field increasing, the tunneling rate increases or decreases for the field parallel to the easy or medium axis, respectively. The analytical results are complemented by numerical simulations.Comment: 11 pages, 6 figure

    Franck-Condon Blockade in a Single-Molecule Transistor

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    We investigate vibron-assisted electron transport in single-molecule transistors containing an individual Fe4 Single-Molecule Magnet. We observe a strong suppression of the tunneling current at low bias in combination with vibron-assisted excitations. The observed features are explained by a strong electron-vibron coupling in the framework of the Franck-Condon model supported by density-functional theory
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