1,716 research outputs found
A novel protocol for the one-pot borylation/Suzuki reaction provides easy access to hinge-binding groups for kinase inhibitors
The one-pot borylation/Suzuki reaction is a very efficient means of accessing cross-coupling products of two aryl-halide partners that generally requires the use of specific catalysts or ligands and/or relatively long reaction times. This new microwave-assisted method provides a quick one-pot borylation/Suzuki reaction protocol that we applied to the synthesis of various bi- or poly-aryl scaffolds, including a variety of aryl and heteroaryl ring systems and the core frameworks of kinase inhibitors vemurafenib and GDC-0879
Nonadiabatic effects in the dynamics of atoms confined in a cylindric time-orbiting-potential magnetic trap
In a time-orbiting-potential magnetic trap the neutral atoms are confined by
means of an inhomogeneous magnetic field superimposed to an uniform rotating
one. We perform an analytic study of the atomic motion by taking into account
the nonadiabatic effects arising from the spin dynamics about the local
magnetic field. Geometric-like magnetic-fields determined by the Berry's phase
appear within the quantum description. The application of a variational
procedure on the original quantum equation leads to a set of dynamical
evolution equations for the quantum average value of the position operator and
of the spin variables. Within this approximation we derive the
quantum-mechanical ground state configuration matching the classical adiabatic
solution and perform some numerical simulations.Comment: 12 pages, 4 figure
Performance indicators for roadway bridges
Publicado em "Maintenance, monitoring, safety, risk and resilience of bridges and bridge networks". ISBN 978-1-138-02851-7The performance indicators should, by its definition, allow capturing the life-cycle degradation
processes affecting maintenance plans or the remaining lifetime. The qualitative or quantitative performance
indicators are obtained through visual inspections, non-destructive tests or monitoring systems. After their
quantification and the comparison with the respective performance goals and thresholds, a Quality Control
plan should be accomplished. The COST TU1406 Action aims to uniform the European performance indicators, systemize the knowledge on the Quality Control plans for bridges, establish quality specifications and finally to develop the guideline and recommendations for the assessment of performance indicators. This contribution focuses on the current work of the first Working Group, WG1, where the first step is a collection of the key performance indicators at a European level. First those key performance indicators which capture mechanical and technical properties and its degradation behavior are assessed, while the further consideration reflect on the natural aging, quality of the material, service life design methods, and sustainable, environmental, economic and social based indicators.COST (European Cooperation in Science and Technology)Project “LeCIE – Life-cycle assessment for railway construction – strategies and methods
Spectrophotometric properties of dwarf planet Ceres from the VIR spectrometer on board the Dawn mission
We study the spectrophotometric properties of dwarf planet Ceres in the
VIS-IR spectral range by means of hyper-spectral images acquired by the VIR
imaging spectrometer on board the NASA Dawn mission. Disk-resolved observations
with a phase angle within the interval were used
to characterize Ceres' phase curve in the 0.465-4.05 m spectral range.
Hapke's model was applied to perform the photometric correction of the dataset,
allowing us to produce albedo and color maps of the surface. The -band
magnitude phase function of Ceres was fitted with both the classical linear
model and H-G formalism. The single-scattering albedo and the asymmetry
parameter at 0.55m are and ,
respectively (two-lobe Henyey-Greenstein phase function); the modeled geometric
albedo is ; the roughness parameter is
. Albedo maps indicate small variability
on a global scale with an average reflectance of . Isolated
areas such as the Occator bright spots, Haulani, and Oxo show an albedo much
higher than average. We measure a significant spectral phase reddening, and the
average spectral slope of Ceres' surface after photometric correction is
and at VIS and IR wavelengths, respectively.
Broadband color indices are and . H-G
modeling of the -band magnitude phase curve for gives
and , while the classical linear model provides
and . The comparison with
spectrophotometric properties of other minor bodies indicates that Ceres has a
less back-scattering phase function and a slightly higher albedo than comets
and C-type objects. However, the latter represents the closest match in the
usual asteroid taxonomy.Comment: 14 pages, 20 figures, published online on Astronomy and Astrophysics
on 13 February 2017. Revised to reflect minor changes in text and figures
made in proofs, updated value of V-R and R-
Impact of SST and surface waves on Hurricane Florence (2018): a coupled modeling investigation
Author Posting. © American Meteorological Society , 2021. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Zambon, J. B., He, R., Warner, J. C., & Hegermiller, C. A. Impact of SST and surface waves on Hurricane Florence (2018): a coupled modeling investigation. Weather and Forecasting, 36(5), (2021): 1713–1734, https://doi.org/10.1175/WAF-D-20-0171.1.Hurricane Florence (2018) devastated the coastal communities of the Carolinas through heavy rainfall that resulted in massive flooding. Florence was characterized by an abrupt reduction in intensity (Saffir–Simpson category 4 to category 1) just prior to landfall and synoptic-scale interactions that stalled the storm over the Carolinas for several days. We conducted a series of numerical modeling experiments in coupled and uncoupled configurations to examine the impact of sea surface temperature (SST) and ocean waves on storm characteristics. In addition to experiments using a fully coupled atmosphere–ocean–wave model, we introduced the capability of the atmospheric model to modulate wind stress and surface fluxes by ocean waves through data from an uncoupled wave model. We examined these experiments by comparing track, intensity, strength, SST, storm structure, wave height, surface roughness, heat fluxes, and precipitation in order to determine the impacts of resolving ocean conditions with varying degrees of coupling. We found differences in the storm’s intensity and strength, with the best correlation coefficient of intensity (r = 0.89) and strength (r = 0.95) coming from the fully coupled simulations. Further analysis into surface roughness parameterizations added to the atmospheric model revealed differences in the spatial distribution and magnitude of the largest roughness lengths. Adding ocean and wave features to the model further modified the fluxes due to more realistic cooling beneath the storm, which in turn modified the precipitation field. Our experiments highlight significant differences in how air–sea processes impact hurricane modeling. The storm characteristics of track, intensity, strength, and precipitation at landfall are crucial to predictability and forecasting of future landfalling hurricanes.This work has been supported by the U.S. Geological Survey Coastal/Marine Hazards and Resources Program, and by Congressional appropriations through the Additional Supplemental Appropriations for Disaster Relief Act of 2019 (H.R. 2157). The authors also wish to acknowledge research support through NSF Grant OCE-1559178 and NOAA Grant NA16NOS0120028. We also wish to thank Chris Sherwood from the U.S. Geological Survey for his help in deriving wave length from WAVEWATCH III data
The valuation of European financial firms
We extend the recent literature concerning accounting based valuation models to investigate financial firms from six European countries with substantial financial sectors: France, Germany, Italy, Netherlands, Switzerland and the UK. Not only are these crucial industries worthy of study in their own right, but unusual accounting practices, and inter-country differences in those accounting practices, provide valuable insights into the accounting-value relationship. Our sample consists of 7,714 financial firm/years observations from 1,140 companies drawn from 1989-2000. Sub-samples include 1,309 firm/years for banks, 650 for insurance companies, 1,705 for real estate firms, and 3,239 for investment companies. In most countries we find that the valuation models work as well or better in explaining cross-sectional variations in the market-to-book ratio for financial firms as they do for industrial and commercial firms in the same countries, although Switzerland is an exception to this generalization. As expected, the results are sensitive to industrial differences, accounting regulation and accounting practices. In particular, marking assets to market value reduces the relevance of earnings figures and increases that of equity
Integration of Dirac-Jacobi structures
We study precontact groupoids whose infinitesimal counterparts are
Dirac-Jacobi structures. These geometric objects generalize contact groupoids.
We also explain the relationship between precontact groupoids and homogeneous
presymplectic groupoids. Finally, we present some examples of precontact
groupoids.Comment: 10 pages. Brief changes in the introduction. References update
A supergeometric approach to Poisson reduction
This work introduces a unified approach to the reduction of Poisson manifolds
using their description by graded symplectic manifolds. This yields a
generalization of the classical Poisson reduction by distributions
(Marsden-Ratiu reduction). Further it allows one to construct actions of strict
Lie 2-groups and to describe the corresponding reductions.Comment: 40 pages. Final version accepted for publicatio
The quantum non-linear Schrodinger model with point-like defect
We establish a family of point-like impurities which preserve the quantum
integrability of the non-linear Schrodinger model in 1+1 space-time dimensions.
We briefly describe the construction of the exact second quantized solution of
this model in terms of an appropriate reflection-transmission algebra. The
basic physical properties of the solution, including the space-time symmetry of
the bulk scattering matrix, are also discussed.Comment: Comments on the integrability and the impurity free limit adde
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