19,756 research outputs found

    Rotational Quenching of H\u3csub\u3e2\u3c/sub\u3eO by He: Mixed Quantum/Classical Theory and Comparison with Quantum Results

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    The mixed quantum/classical theory (MQCT) formulated in the space-fixed reference frame is used to compute quenching cross sections of several rotationally excited states of water molecule by impact of He atom in a broad range of collision energies, and is tested against the full-quantum calculations on the same potential energy surface. In current implementation of MQCT method, there are two major sources of errors: one affects results at energies below 10 cm−1, while the other shows up at energies above 500 cm−1. Namely, when the collision energy E is below the state-to-state transition energy ΔE the MQCT method becomes less accurate due to its intrinsic classical approximation, although employment of the average-velocity principle (scaling of collision energy in order to satisfy microscopic reversibility) helps dramatically. At higher energies, MQCT is expected to be accurate but in current implementation, in order to make calculations computationally affordable, we had to cut off the basis set size. This can be avoided by using a more efficient body-fixed formulation of MQCT. Overall, the errors of MQCT method are within 20% of the full-quantum results almost everywhere through four-orders-of-magnitude range of collision energies, except near resonances, where the errors are somewhat larger

    Can Social Externalities Solve the Small Coalitions Puzzle in International Environmental Agreements?

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    A puzzle in the literature on the formation of coalitions supporting International Environmental Agreements (IEAs) is that if an IEA leads to substantial gains, then it will not be supported by many countries. The non-cooperative game theoretic literature highlights the “small coalitions†puzzle by which only a small number of countries are willing to sign an environmental convention. In these models, a global coalition comprising all countries and generating significant benefits is not sustainable. Moreover they indicate that greater the number of countries in the coalition, higher the incentive of signatories to not respect their engagement. The present paper resolves this puzzle by introducing social externalities, in order to explain why some treaties can be sustained by nearly all countries, while others can be supported only by a handful.

    Rates of convergence of a transient diffusion in a spectrally negative L\'{e}vy potential

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    We consider a diffusion process XX in a random L\'{e}vy potential V\mathbb{V} which is a solution of the informal stochastic differential equation \begin{eqnarray*}\cases{dX_t=d\beta_t-{1/2}\mathbb{V}'(X_t) dt,\cr X_0=0,}\end{eqnarray*} (β\beta B. M. independent of V\mathbb{V}). We study the rate of convergence when the diffusion is transient under the assumption that the L\'{e}vy process V\mathbb{V} does not possess positive jumps. We generalize the previous results of Hu--Shi--Yor for drifted Brownian potentials. In particular, we prove a conjecture of Carmona: provided that there exists 0<κ<10<\kappa<1 such that E[eκV1]=1\mathbf{E}[e^{\kappa\mathbb{V}_1}]=1, then Xt/tκX_t/t^{\kappa} converges to some nondegenerate distribution. These results are in a way analogous to those obtained by Kesten--Kozlov--Spitzer for the transient random walk in a random environment.Comment: Published in at http://dx.doi.org/10.1214/009117907000000123 the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Oscillating Nernst-Ettingshausen effect in Bismuth across the quantum limit

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    In elemental Bismuth, 105^5 atoms share a single itinerant electron. Therefore, a moderate magnetic field can confine electrons to the lowest Landau level. We report on the first study of metallic thermoelectricity in this regime. The main thermoelectric response is off-diagonal with an oscillating component several times larger than the non-oscillating background. When the first Landau level attains the Fermi Energy, both the Nernst and the Ettingshausen coefficients sharply peak, and the latter attains a temperature-independent maximum. A qualitative agreement with a theory invoking current-carrying edge excitations is observed.Comment: Final published versio

    The Dentist and the Missions

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    A linear Stark shift in dressed atoms as a signal to measure a nuclear anapole moment with a cold atom fountain or interferometer

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    We demonstrate theoretically the existence of a linear dc Stark shift of the individual substates of an alkali atom in its ground state, dressed by a circularly polarized laser field. It arises from the electroweak nuclear anapole moment violating P but not T. It is characterized by the pseudoscalar equal to the mixed product formed with the photon angular momentum and static electric and magnetic fields. We derive the relevant left-right asymmetry with its complete signature in a field configuration selected for a precision measurement with cold atom beams. The 3,3 to 4,3 Cs hyperfine-transition frequency shift amounts to 7 μ\muHz for a laser power of about 1 kW at 877 nm, E=100 kV/cm and B larger than 0.5 G.Comment: Article, 4 pages, 2 figure

    Teaching Political Savvy as a Workforce Skill

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    The theoretical framework for this article is based on Charismatic Leadership Theory. This article reflects recent research (including the popular business press) in the area of political skills. Political skill is defined as political astuteness and social intelligence in the workplace; political savvy assumes the existence and inevitability of “office politics”. Based on this research the case is made for educating our future workforce in political savvy. A basic model for curriculum development is included specifically for teaching political savvy in a classroom
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