3,881 research outputs found

    From urban to national heat island: The effect of anthropogenic heat output on climate change in high population industrial countries

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    The project presented here sought to determine whether changes in anthropogenic thermal emission can have a measurable effect on temperature at the national level, taking Japan and Great Britain as type examples. Using energy consumption as a proxy for thermal emission, strong correlations (mean r2 = 0.90 and 0.89, respectively) are found between national equivalent heat output (HO) and temperature above background levels Δt averaged over 5‐ to 8‐yr periods between 1965 and 2013, as opposed to weaker correlations for CMIP5 model temperatures above background levels Δmt (mean r2 = 0.52 and 0.10). It is clear that the fluctuations in Δt are better explained by energy consumption than by present climate models, and that energy consumption can contribute to climate change at the national level on these timescales

    Origin of the Heavy Fermion Behavior in Ca_{2-x}Sr_{x}RuO_{4}: Roles of Coulomb Interaction and the Rotation of RuO_{6} octahedra

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    We study the electronic states for Ca_{2-x}Sr_{x}RuO_{4} in 0.5x20.5\leq x \leq 2 within the Gutzwiller approximation (GA) on the basis of the three-orbital Hubbard model for the Ru t_{2g} orbitals. The main effects of the Ca substitution are taken account as the changes of the dpdp hybridizations between the Ru 4d and O 2p orbitals. Using the numerical minimization of the energy obtained in the GA, we obtain the renormalization factor (RF) of the kinetic energy and total RF, which estimates the inverse of the mass enhancement, for three cases with the effective models of x=2 and 0.5 and a special model. We find that the inverse of the total RF becomes the largest for the case of x=0.5, and that the van Hove singularity, which is located on (below) the Fermi level for the special model (the effective model of x=0.5), plays a secondary role in enhancing the effective mass. Our calculation suggests that the heavy fermion behavior around x=0.5 comes from the cooperative effects between moderately strong Coulomb interaction compared to the total bandwidth and the modification of the electronic structures due to the rotation of RuO_{6} octahedra (i.e., the variation of the dpπdp\pi hybridizations and the downward shift for the dxyd_{xy} orbital). We propose that moderately strong electron correlation and the orbital-dependent modifications of the electronic structures due to the lattice distortions play important roles in the electronic states for Ca_{2-x}Sr_{x}RuO_{4}.Comment: 16 pages, 13 figures, 1 table, accepted for publication in Physical Review B; added the discussions both about the validity of the present treatment and about Hund's metal in this allo

    Branching mechanism of intergranular crack propagation in three dimensions

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    We investigate the process of slow intergranular crack propagation by the finite element method model, and show that branching is induced by partial arresting of crack front owing to the geometrical randomness of grain boundaries. A possible scenario for branching instability of crack propagation in disordered continuum medium is also discussed.Comment: 4 pages, submitted to Phys.Rev.E; v2:corrected typos v3: final version to be publishe

    Multiscale modeling of the moist-convective atmosphere — A review

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    AbstractMultiscale modeling of the moist-convective atmosphere is reviewed with an emphasis on the recently proposed approaches of unified parameterization and Quasi-3D (Q3D) Multiscale Modeling Framework (MMF). The cumulus parameterization problem, which was introduced to represent the multiscale effects of moist convection, has been one of the central issues in atmospheric modeling. After a review of the history of cumulus parameterization, it is pointed out that currently there are two families of atmospheric models with quite different formulations of model physics, one represented by the general circulation models (GCMs) and the other by the cloud-resolving models (CRMs). Ideally, these two families of models should be unified so that a continuous transition of model physics from one kind to the other takes place as the resolution changes. This paper discusses two possible routes to achieve the unification. ROUTE I unifies the cumulus parameterization in conventional GCMs and the cloud microphysics parameterization in CRMs. A key to construct such a unified parameterization is to reformulate the vertical eddy transport due to subgrid-scale moist convection in such a way that it vanishes when the resolution is sufficiently high. A preliminary design of the unified parameterization is presented with supporting evidence for its validity. ROUTE II for the unification follows the MMF approach based on a coupled GCM/CRM, originally known as the “super-parameterization”. The Q3D MMF is an attempt to broaden the applicability of the super-parameterization without necessarily using a fully three-dimensional CRM. This is accomplished using a network of cloud-resolving grids with gaps. The basic Q3D algorithm and highlights of preliminary results are reviewed. It is suggested that the hierarchy of future global models should form a “Multiscale Modeling Network (MMN)”, which combines these two routes. With this network, the horizontal resolution of the dynamics core and that of the physical processes can be individually and freely chosen without changing the formulation of model physics. Development of such a network will represent a new phase of the history of numerical modeling of the atmosphere that can be characterized by the keyword “unification”

    Optimistic Managers & Their Influence on Productivity & Employee Engagement in a Technology Organization

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    The objective of this study is to investigate whether teams are more engaged and productive when led by an optimistic manager. Furthermore, we hypothesize that optimistic managers embody positive leadership—employing a strengths-based approach, maintaining a positive perspective, and frequently providing recognition and encouragement—which increases the engagement and productivity of their employees. In a cross-sectional study of 86 employees and 17 managers in an Information Technology (IT) organization, positive leadership correlated with employee optimism, engagement, and project performance. When we looked at a subset of this data prospectively, with 39 employees and 14 managers, manager optimism predicted project performance. Our data support the claim that positive leadership is correlated with employee engagement and performance, and further extends the importance of optimism in the workplace

    Circularly-Polarized Light Emission from Semiconductor Planar Chiral Photonic Crystal

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    We proposed and demonstrated a scheme of surface emitting circularly polarized light source by introducing strong imbalance between left- and right-circularly polarized vacuum fields in an on-waveguide chiral grating structure. We observed circularly polarized spontaneous emission from InAs quantum dots embedded in the wave guide region of a GaAs-based structure. Obtained degree of polarization reaches as large as 25% at room temperature. Numerical calculation visualizes spatial profiles of the modification of vacuum field modes inside the structure with strong circular anisotropy.Comment: REVTeX4.1, 6pages, 3figure

    Toward unification of the multiscale modeling of the atmosphere

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    As far as the representation of deep moist convection is concerned, only two kinds of model physics are used at present: highly parameterized as in the conventional general circulation models (GCMs) and explicitly simulated as in the cloud-resolving models (CRMs). Ideally, these two kinds of model physics should be unified so that a continuous transition of model physics from one kind to the other takes place as the resolution changes. With such unification, the GCM can converge to a global CRM (GCRM) as the grid size is refined. This paper suggests two possible routes to achieve the unification. ROUTE I continues to follow the parameterization approach, but uses a unified parameterization that is applicable to any horizontal resolutions between those typically used by GCMs and CRMs. It is shown that a key to construct such a unified parameterization is to eliminate the assumption of small fractional area covered by convective clouds, which is commonly used in the conventional cumulus parameterizations either explicitly or implicitly. A preliminary design of the unified parameterization is presented, which demonstrates that such an assumption can be eliminated through a relatively minor modification of the existing mass-flux based parameterizations. Partial evaluations of the unified parameterization are also presented. ROUTE II follows the "multi-scale modeling framework (MMF)" approach, which takes advantage of explicit representation of deep moist convection and associated cloud-scale processes by CRMs. The Quasi-3-D (Q3-D) MMF is an attempt to broaden the applicability of MMF without necessarily using a fully three-dimensional CRM. This is accomplished using a network of cloud-resolving grids with large gaps. An outline of the Q3-D algorithm and highlights of preliminary results are reviewed

    Direct observation of acoustic phonon mediated relaxation between coupled exciton states in a single quantum dot molecule

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    We probe acoustic phonon mediated relaxation between tunnel coupled exciton states in an individual quantum dot molecule in which the inter-dot quantum coupling and energy separation between exciton states is continuously tuned using static electric field. Time resolved and temperature dependent optical spectroscopy are used to probe inter-level relaxation around the point of maximum coupling. The radiative lifetimes of the coupled excitonic states can be tuned from ~2 ns to ~10 ns as the spatially direct and indirect character of the wavefunction is varied by detuning from resonance. Acoustic phonon mediated inter-level relaxation is shown to proceed over timescales comparable to the direct exciton radiative lifetime, indicative of a relaxation bottleneck for level spacings in the range $\Delta E\$ ~3-6 meV.Comment: 6 pages, 4 figures, submitted for publicatio

    Electrospray ionization mass spectrometric observation of ligand exchange of zinc pyrithione with amino acids

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    ArticleRAPID COMMUNICATIONS IN MASS SPECTROMETRY. 23(14):2161-2166 (2009)journal articl

    Optimistic Managers & Their Influence on Productivity & Employee Engagement in a Technology Organization

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    The objective of this study is to investigate whether teams are more engaged and productive when led by an optimistic manager. Furthermore, we hypothesize that optimistic managers embody positive leadership—employing a strengths-based approach, maintaining a positive perspective, and frequently providing recognition and encouragement—which increases the engagement and productivity of their employees. In a cross-sectional study of 86 employees and 17 managers in an Information Technology (IT) organization, positive leadership correlated with employee optimism, engagement, and project performance. When we looked at a subset of this data prospectively, with 39 employees and 14 managers, manager optimism predicted project performance. Our data support the claim that positive leadership is correlated with employee engagement and performance, and further extends the importance of optimism in the workplace
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