10,717 research outputs found
The resonance amplitude associated with the Gamow states
The Gamow states describe the quasinormal modes of quantum systems. It is
shown that the resonance amplitude associated with the Gamow states is given by
the complex delta function. It is also shown that under the near-resonance
approximation of neglecting the lower bound of the energy, such resonance
amplitude becomes the Breit-Wigner amplitude. This result establishes the
precise connection between the Gamow states, Nakanishi's complex delta function
and the Breit-Wigner amplitude. In addition, this result provides another
theoretical basis for the phenomenological fact that the almost-Lorentzian
peaks in cross sections are produced by intermediate, unstable particles
On the Robustness of the h-index: a mathematical approach
The h-index is an index recently proposed by Hirsch (2005) to measure scientific achievement by individual scholars. It is a compound measure of publications and citations. We show the robustness of this index. This means that h-index increases with both the number of publications and the number of citations only when these numbers are significant.
The tradeoff between growth and redistribution: ELIE in an overlapping generations model
education, growth, redistribution, Kolm
The Tradeoff Between Growth and Redistribution: ELIE in an Overlapping Generations Model
The ELIE scheme of Kolm taxes labour capacities instead of labour income in order to circumvent the distortionary effect of taxation on labour supply. Still, Kolm does not study the impact of ELIE on human capital formation and investment. In this paper, we build an overlapping generations (OLG) model with heterogenous agents and endogenous growth driven by investment in human capital. We study the effect of ELIE on education investment and other aggregate economic variables. Calibrating the model to French data, we highlight a tradeoff between growth and redistribution. With a perfect credit market, ELIE is successful in reducing inequalities and poverty, but it is at the expense of lower investment in education and slower growth. In an economy with an imperfect credit market where individuals cannot borrow to educate, the tradeoff between growth and redistribution is not overturned but is less severe. However, it is possible to overturn completely that trade-off simply by changing the base of taxation for the young generation which is equivalent to subsidising education.Education, Growth, Redistribution, Kolm
On Mpc-structures and Symplectic Dirac Operators
We prove that the kernels of the restrictions of symplectic Dirac or
symplectic Dirac-Dolbeault operators on natural subspaces of polynomial valued
spinor fields are finite dimensional on a compact symplectic manifold. We
compute those kernels for the complex projective spaces. We construct
injections of subgroups of the symplectic group (the pseudo-unitary group and
the stabilizer of a Lagrangian subspace) in the group Mpc and classify
G-invariant Mpc-structures on symplectic spaces with a G-action. We prove a
variant of Parthasarathy's formula for the commutator of two symplectic
Dirac-type operators on a symmetric symplectic space
Comparison and Assessment of Two Emission inventories for the Madrid Region
Emission inventories are databases that aim to describe the polluting activities that occur across a certain geographic domain. According to the spatial scale, the availability of information will vary as well as the applied assumptions, which will strongly influence its quality, accuracy and representativeness. This study compared and contrasted two emission inventories describing the Greater Madrid Region (GMR) under an air quality simulation approach. The chosen inventories were the National Emissions Inventory (NEI) and the Regional Emissions Inventory of the Greater Madrid Region (REI). Both of them were used to feed air quality simulations with the CMAQ modelling system, and the results were compared with observations from the air quality monitoring network in the modelled domain. Through the application of statistical tools, the analysis of emissions at cell level and cell – expansion procedures, it was observed that the National Inventory showed better results for describing on – road traffic activities and agriculture, SNAP07 and SNAP10. The accurate description of activities, the good characterization of the vehicle fleet and the correct use of traffic emission factors were the main causes of such a good correlation. On the other hand, the Regional Inventory showed better descriptions for non – industrial combustion (SNAP02) and industrial activities (SNAP03). It incorporated realistic emission factors, a reasonable fuel mix and it drew upon local information sources to describe these activities, while NEI relied on surrogation and national datasets which leaded to a poorer representation. Off – road transportation (SNAP08) was similarly described by both inventories, while the rest of the SNAP activities showed a marginal contribution to the overall emissions
Cybercars : Past, Present and Future of the Technology
Automobile has become the dominant transport mode in the world in the last
century. In order to meet a continuously growing demand for transport, one
solution is to change the control approach for vehicle to full driving
automation, which removes the driver from the control loop to improve
efficiency and reduce accidents. Recent work shows that there are several
realistic paths towards this deployment : driving assistance on passenger cars,
automated commercial vehicles on dedicated infrastructures, and new forms of
urban transport (car-sharing and cybercars). Cybercars have already been put
into operation in Europe, and it seems that this approach could lead the way
towards full automation on most urban, and later interurban infrastructures.
The European project CyberCars has brought many improvements in the technology
needed to operate cybercars over the last three years. A new, larger European
project is now being prepared to carry this work further in order to meet more
ambitious objectives in terms of safety and efficiency. This paper will present
past and present technologies and will focus on the future developments
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