3,893 research outputs found
Measuring Support to Agriculture in a Transition Economy in the Southern Balkans: The case of FYR Macedonia
As a candidate country to the EU and a member of the WTO there is a need for a comprehensive, transparent and internationally comparable assessment of the support to agriculture in Macedonia. OECD that has been measuring support to agriculture on a yearly basis, in its member countries as well as some other countries since the mid-1980s, offers a good tool for such a task. The method is known for its most important indicator, the Producer Support Estimate (PSE). Using this method, data on Macedonian agricultural policy measures, in place – partly or entirely - for the period 1999 to 2004, have been gathered and categorized in order to arrive at an estimate of the level of support.Producer support estimate (PSE), FYR Macedonia, trade protection, Agricultural and Food Policy,
Impulse approximation in the n p --> d pi^0 reaction reexamined
The impulse approximation (one-body operator) in the n p --> d pi^0 reaction
is reexamined with emphasis on the issues of reducibility and recoil
corrections. An inconsistency when one pion exchange is included in the
production operator is demonstrated and then resolved via the introduction of
"wave function corrections" which nearly vanish for static nucleon propagators.
Inclusion of the recoil corrections to the nucleon propagators is found to
change the magnitude and sign of the impulse production amplitude, worsening
agreement with the experimental cross section by approximately 30%. A cutoff is
used to account for the phenomenological nature of the external wave functions,
and is found to have a significant impact up to approximately 2.5 GeV.Comment: Published versio
Development of an immersive game-based virtual reality training program to teach fire safety skills to children
Injuries from residential fires are often overlooked as a dangerous safety concern for children. While lectures and classroom learning techniques can be effective in mitigating this risk, studies have shown that kids retain information better if they are allowed to practice escape techniques. Virtual Reality (VR) has been used both to simulate situations that are too dangerous to practice in real life and as a tool to help children learn. This thesis presents the two stage development of the Fire Safety Project, a game-based VR training environment to increase children\u27s understanding of fire safety. In the first iteration students help firefighters to identify home fire hazards and then practice escaping from a simulated fire in a virtual environment. Surveys administered show that participants felt that they had learned something during training. Many young participants also wanted to have active control over the virtual environment. In response, the second iteration is more game-based and allows children to explore the environment independently and zap fire hazards with the help of a tracked 6DOF wand. A user study was carried out and results indicate that students enjoyed the program; however there were no concrete learning gains from the use of the VR simulation
Quantum Mechanics of Extended Objects
We propose a quantum mechanics of extended objects that accounts for the
finite extent of a particle defined via its Compton wavelength. The Hilbert
space representation theory of such a quantum mechanics is presented and this
representation is used to demonstrate the quantization of spacetime. The
quantum mechanics of extended objects is then applied to two paradigm examples,
namely, the fuzzy (extended object) harmonic oscillator and the Yukawa
potential. In the second example, we theoretically predict the phenomenological
coupling constant of the meson, which mediates the short range and
repulsive nucleon force, as well as the repulsive core radius.Comment: RevTex, 24 pages, 1 eps and 5 ps figures, format change
Dilepton production in proton-proton and quasifree proton-neutron reactions at 1.25 GeV
We investigate the pp --> pp e+e- and quasifree pn --> pn e+e- reactions
within an effective Lagrangian model at the laboratory kinetic energy of 1.25
GeV for which experimental data have recently been reported by the HADES
Collaboration. The model uses a meson-exchange approximation to describe the
initial nucleon-nucleon (NN) scattering. Contributions to the reaction
amplitudes are included from the NN bremsstrahlung as well as from the
excitation, propagation and radiative decay of the Delta(1230) isobar state. It
is found that the HADES data on the e+e- invariant mass distribution in the pp
--> pp e+e- reaction are reproduced excellently by our model where the Delta
isobar term dominates the spectrum. However, the quasifree pn --> pn e+e- cross
sections are underpredicted in the invariant mass region of 0.40 - 0.55 GeV/c^2
even after including contributions of the eta Dalitz decay and the subthreshold
production and decay of the rho^0 meson via the baryonic resonance N*(1520). In
the case of the quasifree pn --> pn e+e- reaction, a strong sensitivity to the
pion electromagnetic form factor is observed which helps to bring the
calculated cross sections closer to the data in the higher dilepton mass
region.Comment: 12 pages 3, figures, version to appear in Phys. Rev. C (Rapid
Communications
Videoconferencing via satellite. Opening Congress to the people: Technical report
The feasibility of using satellite videoconferencing as a mechanism for informed dialogue between Congressmen and constituents to strengthen the legislative process was evaluated. Satellite videoconferencing was defined as a two-way interactive television with the TV signals transmitted by satellite. With videoconferencing, one or more Congressmen in Washington, D. C. can see, hear and talk with groups of citizens at distant locations around the country. Simultaneously, the citizens can see, hear and talk with the Congressmen
Quark Condensate in the Deuteron
We study the changes produced by the deuteron on the QCD quark condensate by
means the Feynman-Hellmann theorem and find that the pion mass dependence of
the pion-nucleon coupling could play an important role. We also discuss the
relation between the many body effect of the condensate and the meson exchange
currents, as seen by photons and pions. For pion probes, the many-body term in
the physical amplitude differs significantly from that of soft pions, the one
linked to the condensate. Thus no information about the many-body term of the
condensate can be extracted from the pion-deuteron scattering length. On the
other hand, in the Compton amplitude, the relationship with the condensate is a
more direct one.Comment: to appear in Physics Review C (19 pages, 3 figures
Spin distribution of nuclear levels using static path approximation with random-phase approximation
We present a thermal and quantum-mechanical treatment of nuclear rotation
using the formalism of static path approximation (SPA) plus random-phase
approximation (RPA). Naive perturbation theory fails because of the presence of
zero-frequency modes due to dynamical symmetry breaking. Such modes lead to
infrared divergences. We show that composite zero-frequency excitations are
properly treated within the collective coordinate method. The resulting
perturbation theory is free from infrared divergences. Without the assumption
of individual random spin vectors, we derive microscopically the spin
distribution of the level density. The moment of inertia is thereby related to
the spin-cutoff parameter in the usual way. Explicit calculations are performed
for 56^Fe; various thermal properties are discussed. In particular, we
demonstrate that the increase of the moment of inertia with increasing
temperature is correlated with the suppression of pairing correlations.Comment: 12 pages, 8 figures, accepted for publication in Physical Review
NASA rotor system research aircraft flight-test data report: Helicopter and compound configuration
The flight test activities of the Rotor System Research Aircraft (RSRA), NASA 740, from June 30, 1981 to August 5, 1982 are reported. Tests were conducted in both the helicopter and compound configurations. Compound tests reconfirmed the Sikorsky flight envelope except that main rotor blade bending loads reached endurance at a speed about 10 knots lower than previously. Wing incidence changes were made from 0 to 10 deg
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