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Search Results: 1 - 10 of 208712 matches for " L. Pagani "
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Geologic constraints on earth system sensitivity to CO2 during the Cretaceous and early Paleogene
D. L. Royer,M. Pagani,D. J. Beerling
Earth System Dynamics Discussions , 2011, DOI: 10.5194/esdd-2-211-2011
Abstract: Earth system sensitivity (ESS) is the long-term (>103 yr) equilibrium temperature response to doubled CO2. ESS has climate policy implications because global temperatures are not expected to decline appreciably for at least 103 yr, even if anthropogenic greenhouse-gas emissions drop to zero. We report quantitative ESS estimates of 3 °C or higher for much of the Cretaceous and early Paleogene based on paleo-reconstructions of CO2 and temperature. These estimates are generally higher than climate sensitivities simulated from global climate models for the same ancient periods (~3 °C). We conclude that climate models do not capture the full suite of positive climate feedbacks during greenhouse worlds. These absent feedbacks are probably related to clouds, trace greenhouse gases, seasonal snow cover, and/or vegetation, especially in polar regions. Continued warming in the coming decades as anthropogenic greenhouse gases accumulate in the atmosphere ensures that characterizing and quantifying these positive climate feedbacks will become a scientific challenge of increasing priority.
Direct evidence of dust growth in L183 from MIR light scattering
J. Steinacker,L. Pagani,A. Bacmann,S. Guieu
Physics , 2009, DOI: 10.1051/0004-6361/200912835
Abstract: Theoretical arguments suggest that dust grains should grow in the dense cold parts of molecular clouds. Evidence of larger grains has so far been gathered in near/mid infrared extinction and millimeter observations. Interpreting the data is, however, aggravated by the complex interplay of density and dust properties (as well as temperature for thermal emission). We present new Spitzer data of L183 in bands that are sensitive and insensitive to PAHs. The visual extinction AV map derived in a former paper was fitted by a series of 3D Gaussian distributions. For different dust models, we calculate the scattered MIR radiation images of structures that agree agree with the AV map and compare them to the Spitzer data. The Spitzer data of L183 show emission in the 3.6 and 4.5 micron bands, while the 5.8 micron band shows slight absorption. The emission layer of stochastically heated particles should coincide with the layer of strongest scattering of optical interstellar radiation, which is seen as an outer surface on I band images different from the emission region seen in the Spitzer images. Moreover, PAH emission is expected to strongly increase from 4.5 to 5.8 micron, which is not seen. Hence, we interpret this emission to be MIR cloudshine. Scattered light modeling when assuming interstellar medium dust grains without growth does not reproduce flux measurable by Spitzer. In contrast, models with grains growing with density yield images with a flux and pattern comparable to the Spitzer images in the bands 3.6, 4.5, and 8.0 micron.
Noncommutative de Rham cohomology of finite groups
L. Castellani,R. Catenacci,M. Debernardi,C. Pagani
Physics , 2002, DOI: 10.1142/S0217751X04018403
Abstract: We study de Rham cohomology for various differential calculi on finite groups G up to order 8. These include the permutation group S_3, the dihedral group D_4 and the quaternion group Q. Poincare' duality holds in every case, and under some assumptions (essentially the existence of a top form) we find that it must hold in general. A short review of the bicovariant (noncommutative) differential calculus on finite G is given for selfconsistency. Exterior derivative, exterior product, metric, Hodge dual, connections, torsion, curvature, and biinvariant integration can be defined algebraically. A projector decomposition of the braiding operator is found, and used in constructing the projector on the space of 2-forms. By means of the braiding operator and the metric a knot invariant is defined for any finite group.
?Se puede ser una empresa socialmente responsable sin comunicar?
Cuadernos del Centro de Estudios en Dise?±o y Comunicaci?3n. Ensayos , 2012,
Abstract: the present article proposes to focus on some concepts tied to social corporate responsibility and corporate communications with the aim of showing that the communication is a constituent element of a social responsible way of doing businesses.
Urban energy efficiency: a breakthrough vs. the global crisis
Roberto Pagani
Techne : Journal of Technology for Architecture and Environment , 2011,
Abstract: The environmental design and its complex multi-disciplinary consequences are central in the thinking of the responsibilities, which the Institutes of Knowledge are based on. It is no longer a battle to the forefront, just for the explorers. It is an acquired and consolidated culture, but from an operational standpoint there are many areas of innovation, development, affirmation still to develop. The article focuses on four central aspects of the new culture of energy efficiency in urban systems: the new global/local decision making, the sustainability in urban processes, the new skills for research and development, the growing interest of industries in innovative urban technologies. It provides the main trends in Europe and a vision of a possible exit from the complex socio-economic situation of today: a culture of complexity and energy innovation as factors of development.
Top quark forward-backward asymmetry at the Tevatron: the electroweak contribution
Davide Pagani
Physics , 2012,
Abstract: Recent CDF and D0 measurements of the top quark forward-backward asymmetry at the Tevatron present deviations between 1-sigma and 2-sigma from QCD predictions and a cut M_inv > 450 GeV on the events increases this deviation to 3.4 sigma in the CDF measurement. The inclusion of electroweak contributions of order alpha^2 and order alpha alphas^2 enlarges the theoretical prediction from QCD by a factor ~ 1.2 and diminishes the observed deviations. The calculation method is shortly discussed and numerical results are compared to the experimental data.
On the equation $Du+Xu=0$ and its relation to Schroedinger ground states
Kurt Pagani
Physics , 2013,
Abstract: We present some simple relations between the absolute minimizers of the functional $||Du+Xu||$, where $X$ is a vector field on $R^n$, and ground state solutions to the (non-relativistic) Schroedinger equation. This article is a byproduct of the study of the more general functional $||ADu+F'(u)X||$.
On the definiteness of associated energy-momentum tensors to a class of general variation problems
Kurt Pagani
Physics , 2013,
Abstract: We show the point-wise definiteness and some other properties of the energy-momentum tensor for a certain class of Euler-Lagrange equations under quite general conditions.
The electroweak contribution to top quark pair production: cross sections and asymmetries
Davide Pagani
Physics , 2012,
Abstract: In this talk we review the electroweak contribution to top quark pair production at hadron colliders. We discuss the phenomenological impact of these corrections on the cross sections and on the charge asymmetries at the Tevatron and the LHC.
Some Properties of a Class of QM Phase Space Measures
Kurt Pagani
Physics , 2013,
Abstract: We have a look at the probability measures induced by Schrodinger wave functions on phase space.
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