2,704 research outputs found
Road pricing as a citizen-candidate game
We construct a political economy model to analyze the political acceptability of road pricing policies.
We use a citizen-candidate framework with a population composed by three groups differing for their income level. We show that road pricing policies are never applied when there is no redistribution of the resources in favour of other modes of transport or when the congestion of these types of transport is relatively high. The results suggest that the efficiency of the redistribution of resources from road to the alternative types of transport as well as the fraction of the population that uses the road transport are key factors in explaining the adoption of road pricing schemes
Effect of three nucleon forces in p-3He scattering
The effect of the inclusion of different models of three nucleon (3N) forces
in p-3He elastic scattering at low energies is studied. Two models have been
considered: one derived from effective field theory at next-to-next-to-leading
order and one derived from a more phenomenological point of view -- the
so-called Illinois model. The four nucleon scattering observables are
calculated using the Kohn variational principle and the hyperspherical harmonic
technique and the results are compared with available experimental data. We
have found that with the inclusion of both 3N force models the agreement with
the experimental data is improved, in particular for the proton vector
analyzing power A_y.Comment: 8 pages, 4 figures, talk presented at the 20th International IUPAP
Conference on Few-Body Problems in Physics, 20 - 25 August, 2012, Fukuoka,
Japa
Comparative study of three-nucleon force models in systems
Using modern nucleon-nucleon interactions in the description of the
nuclei, it is not possible to reproduce both the three- and four-nucleon
binding energies simultaneously. This is one manifestation of the necessity of
including a three-nucleon force in the nuclear Hamiltonian. In this paper we
will perform a comparative study of some, widely used, three-nucleon force
models. We will analyze their capability to describe the aforementioned binding
energies as well as the doublet scattering length. A correct description
of these quantities can be considered a stringent requirement for a nuclear
Hamiltonian containing two- and three-nucleon interaction terms. As we will
show, this requirement is not fulfilled by several of the models available in
the literature. To satisfy it, we propose modifications in the parametrization
of the three-nucleon forces and we study their effects on few selected
low energy scattering observables.Comment: 30 pages, 10 figure
The astrophysical -factor and its implications for Big Bang Nucleosynthesis
The \alpha+d\rightarrow\, ^6{\rm Li}+\gamma radiative capture is studied in
order to predict the Li primordial abundance. Within a two-body framework,
the particle and the deuteron are considered the structureless
constituents of Li. Five potentials are used to solve the
two-body problem: four of them are taken from the literature, only one having
also a tensor component. A fifth model is here constructed in order to
reproduce, besides the Li static properties as binding energy, magnetic
dipole and electric quadrupole moments, also the -state asymptotic
normalization coefficient (ANC). The two-body bound and scattering problem is
solved with different techniques, in order to minimize the numerical
uncertainty of the present results. The long-wavelength approximation is used,
and therefore only the electric dipole and quadrupole operators are retained.
The astrophysical -factor is found to be significantly sensitive to the ANC,
but in all the cases in good agreement with the available experimental data.
The theoretical uncertainty has been estimated of the order of few % when the
potentials which reproduce the ANC are considered, but increases up to % when all the five potential models are retained. The effect of this
-factor prediction on the Li primordial abundance is studied, using the
public code PArthENoPE. For the five models considered here we find H, with the baryon density parameter in
the 3- range of Planck 2015 analysis, .Comment: 26 pages, 9 figure
Effect of three-nucleon interaction in p-3He elastic scattering
We present a detailed study of the effect of different three-nucleon
interaction models in p-3He elastic scattering at low energies. In particular,
two models have been considered: one derived from effective field theory at
next-to-next-to-leading order and one derived from a more phenomenological
point of view -- the so-called Illinois model. The four-nucleon scattering
observables are calculated using the Kohn variational principle and the
hyperspherical harmonics technique and the results are compared with available
experimental data. We have found that the inclusion of either one of the other
force model improves the agreement with the experimental data, in particular
for the proton vector analyzing power.Comment: 4 pages, 3 figure
Implication of the proton-deuteron radiative capture for Big Bang Nucleosynthesis
The astrophysical -factor for the radiative capture He in
the energy-range of interest for Big Bang Nucleosynthesis (BBN) is calculated
using an {\it ab-initio} approach. The nuclear Hamiltonian retains both two-
and three-nucleon interactions - the Argonne and the Urbana IX,
respectively. Both one- and many-body contributions to the nuclear current
operator are included. The former retain for the first time, besides the
leading order contribution ( is the nucleon mass), also the next-to-leading
order term, proportional to . The many-body currents are constructed in
order to satisfy the current conservation relation with the adopted Hamiltonian
model. The hyperspherical harmonics technique is applied to solve the
bound and scattering states. A particular attention is used in this second case
in order to obtain, in the energy range of BBN, an uncertainty on the
astrophysical -factor of the order or below 1 %. Then, in this energy
range, the -factor is found to be 10 % larger than the currently
adopted values.Part of this increase (1-3 %) is due to the one-body
operator, while the remaining is due to the new more accurate scattering wave
functions. We have studied the implication of this new determination for the
He -factor on deuterium primordial abundance. We find that
the predicted theoretical value for H/H is in excellent agreement with its
experimental determination, using the most recent determination of baryon
density of Planck experiment, and with a standard number of relativistic
degrees of freedom during primordial nucleosynthesis.Comment: 5 pages, 2 figures, submitted to Phys. Rev. Let
DESIGN OF A STATED RANKING EXPERIMENT TO STUDY INTERACTIVE FREIGHT BEHAVIOUR: AN APPLICATION TO ROME'S LTZ
City logistics policies require an understanding of several issues (e.g. freight distribution context, preferences and relationship among agents) seldom accounted for in current research. Policies run the risk of producing unsatisfactory results because behavioural and contextual aspects are not considered. The acquisition of relevant data is crucial to test hypothesis and forecast agents' reactions to policy changes. Despite recent methodological advances in modelling interactive behaviour the development of apt survey instruments is still lacking to test innovative policies acceptability. This paper expands and innovate the methodological literature by describing a stated ranking experiment to study freight agent interactive behaviour and discusses the experimental design implemented to incorporate agent-specific priors when efficient design techniques are employed.urban freight distribution, group decision making, agent-specific interaction, stated preference, stated ranking experiments
Navigating Unfamiliar Terrain: Reconciling Conflicting Impressions of China’s Intellectual Property Regime in an Effort to Aid Foreign Right Holders
While imperial China was a notably inventive place, formal intellectual property protections analogous to those in the West failed to emerge there of their own accord. The deep influence of Confucianism on imperial Chinese society brought about a culture that subordinated individual desires to group harmony and perceived original creations as products not of individual people but of the society to which they belonged. Moreover, Confucianism\u27s influence on education and literature rendered verbatim copying not merely an accepted practice but a fundamental aspect of scholarship. Buddhism\u27s close connection to the emergence of printing in China also served to delay by centuries the first claims by authors of ownership interests in their works. Accordingly, the impetus for China\u27s modern intellectual property regime came from abroad. After China\u27s defeat in the Opium War, foreign investment in China increased dramatically and Western commercial interests began to press China for the legal recognition of their intellectual property rights. An effective enforcement regime, however, eluded China until the birth of the PRC. Since the late 1970s, the PRC has taken efforts to integrate China\u27s intellectual property regime with international institutions. China acceded to TRIPS in 1999 and joined the WTO in 2001. In tandem with these legal developments, China\u27s economy has rapidly become the world\u27s second largest, a fact attributable largely to foreign direct investment. China\u27s economic rise especially affects foreign holders of intellectual property rights. Commentators, however, differ starkly in their assessments of the ability of China\u27s intellectual property institutions to combat infringement. On the one hand, China\u27s apologists claim that such institutions are -- or imminently will be -- sufficient to provide for the just and efficient resolution of disputes arising out of infringement. On the other hand, China\u27s critics, particularly those in the United States, contend that China\u27s intellectual property regime fails to deter and remedy infringement. Ultimately, the views of China\u27s apologists are misleading. China\u27s specialized intellectual property tribunals have proven to be relatively effective, but insufficient resources, judicial corruption, and the inability of judges to act independent of the Chinese Communist Party hinder the effectiveness of China\u27s judiciary. China\u27s fragmented administrative enforcement bureaucracy, which handles the overwhelming majority of disputes arising out of infringement, suffers from a host of problems that work to the detriment of right holders. Criminal enforcement almost always results in convictions, yet procedural inefficiencies render such convictions frustratingly difficult to achieve. These shortcomings may be attributed to certain historical phenomena. Specifically, the Chinese state, in administering China\u27s intellectual property regime, has adopted an approach that comports with Confucianism\u27s elevation of state prerogatives at the expense of individual interests. Trends in patent law reform, trade secret litigation, and trademark enforcement bolster this conception of the Chinese state\u27s motivations. Foreign right holders, therefore, cannot reasonably expect China\u27s intellectual property regime to serve their interest in combating infringement. Consequently, foreign victims of infringement should seek to reverse the trend of anemic foreign litigation in China and employ China\u27s courts, especially the intellectual property tribunals, to vindicate their rights. Indeed, the Chinese government appears disinclined to take foreign perspectives under consideration in drafting new intellectual property legislation, a trend that may render the courts the only venue where foreign right holders can air their grievances. Finally, foreign right holders might also attempt to initiate private criminal prosecutions against infringers, although this avenue of enforcement is less likely to deliver favorable results
Tritium -decay in chiral effective field theory
We evaluate the Fermi and Gamow-Teller (GT) matrix elements in tritium
-decay by including in the charge-changing weak current the corrections
up to one loop recently derived in nuclear chiral effective field theory
( EFT). The trinucleon wave functions are obtained from
hyperspherical-harmonics solutions of the Schrodinger equation with two- and
three-nucleon potentials corresponding to either EFT (the N3LO/N2LO
combination) or meson-exchange phenomenology (the AV18/UIX combination). We
find that contributions due to loop corrections in the axial current are, in
relative terms, as large as (and in some cases, dominate) those from one-pion
exchange, which nominally occur at lower order in the power counting. We also
provide values for the low-energy constants multiplying the contact axial
current and three-nucleon potential, required to reproduce the experimental GT
matrix element and trinucleon binding energies in the N3LO/N2LO and AV18/UIX
calculations.Comment: 19 pages,6 figures, corrections to Text as suggested by Referee
added; Erratum: 4 pages, 3 figures, corrections to Eq.(20), Tables I, II,
III, Figures 4, 5, conclusions unchange
- …