4,735 research outputs found
THE CAP REFORM AND EC-US RELATIONS: THE GATT AS A "CAP" ON THE CAP
Reform of the Common Agricultural Policy has entailed the substitution of new income support instruments for the former price based instruments, mainly in the cash crop sector. Our first point is that the domestic political balance was unable to generate such a large change in policy design, in spite of inefficiencies and inbalances. The pressure of the US has been a major factor in the design of the reform. We argue that trade interests have been crucial to catalyze international collective action in order to countervail domestic pressure groups. The pursuit of an agreement in the GATT is therefore a means to place a cap on the CAP and foster some reform and control over sectors such as sugar and dairy in other countries. We do not foresee the disappearance of sources of tensions between the two countries, as EC animal products become more competitive and as the working of the CAP in the vicinity of world prices will make trade flows sensitive to world macro-economic and agricultural shocks. The Uruguay Round, should not be considered as fully satisfactory, and the long-run objective of further decoupling of payments from production incentives should be pursued.Agricultural and Food Policy,
Interacting Two-Level Systems as a Source of 1/f Charge Noise in Quantum Dot Qubits
Charge noise in semiconducting quantum dots has been observed to have a 1/f
spectrum. We propose a model in which a pair of quantum dots are coupled to a
2D bath of fluctuating two level systems (TLS) that have electric dipole
moments and that interact with each other, i.e., with the other fluctuators.
These interactions are primarily via the elastic strain field. We use a 2D
nearest-neighbor Ising spin glass to represent these elastic interactions and
to simulate the dynamics of the bath of electric dipole fluctuators in the
presence of a ground plane representing metal gates above the oxide layer
containing the fluctuators. The interactions between the TLS cause the energy
splitting of individual fluctuators to change with time. We calculate the
resulting fluctuations in the electric potential at the two quantum dots that
lie below the oxide layer. We find that 1/f electric potential noise spectra at
the quantum dots and cross correlation in the noise between the two quantum
dots are in qualitative agreement with experiment. Our simulations find that
the cross correlations decrease exponentially with increasing quantum dot
separation.Comment: 14 pages, 11 figure
Evaluation of the effect of Miller cycle on the main parameters of a diesel engine using mathematical modeling
The influence of the angles of closure of the intake valves on the technical, economic and ecological parameters of a diesel engine was studied by numerical simulation. The study was carried out in the program complex Diesel-RK developed by the MGTU named after N. E. Bauman. Diesel 12DM-185 was chosen as the base engine for the study. It is shown that application of the Miller cycle (early valve closing) has a significant impact on the performance of diesel. It is established that the optimum closing angles of the intake valves for the diesel when using the Miller cycle is 25 degrees before BDC.В данной статье на основе численного моделирования было исследовано влияние углов закрытия впускных клапанов на технико-экономические и экологические показатели дизельного двигателя. Исследование выполнено в программном комплексе Дизель-РК, разработанном в МГТУ имени Н. Э. Баумана. В качестве базового двигателя для исследования был выбран дизель 12ДМ-185. Показано, что применение цикла Миллера (раннее закрытие клапана) оказывает существенное влияние на показатели дизеля. Установлено, что оптимальные углы закрытия впускных клапанов для исследуемого дизеля при использовании цикла Миллера составляют 25 градусов до НМТ
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Crystallization studies of poly(vinylidene fluoride) and related copolymers without and with static electric field/
An HST/WFPC2 Survey for Brown Dwarf Binaries in the alpha Per and the Pleiades Open Clusters
We present the results of a high-resolution imaging survey for brown dwarf
(BD) binaries in two open clusters. The observations were carried out with
WFPC2 onboard HST. Our sample consists of 8 BD candidates in the alpha Per
cluster and 25 BD candidates in the Pleiades. We have resolved 4 binaries in
the Pleiades with separations in the range 0".094--0".058, corresponding to
projected separations between 11.7~AU and 7.2~AU. No binaries were found among
the alpha Per targets. Three of the binaries have proper motions consistent
with cluster membership in the Pleiades cluster, and for one of them we report
the detection of Halpha in emission and LiI absorption obtained from
Keck~II/ESI spectroscopy. One of the binaries does not have a proper motion
consistent with Pleiades membership. We estimate that BD binaries wider than
12~AU are less frequent than 9% in the alphaPer and Pleiades clusters. This is
consistent with an extension to substellar masses of a trend observed among
stellar binaries: the maximum semimajor axis of binary systems decreases with
decreasing primary mass. We find a binary frequency of 2 binaries over 13 BDs
with confirmed proper motion membership in the Pleiades, corresponding to a
binary fraction of 15%(1 sigma error bar +15%/-5%). These binaries are limited
to the separation range 7-12~AU and their mass ratios are larger than 0.7. The
relatively high binary frequency (>10%), the bias to separations smaller than
about 15 AU and the trend to high mass ratios (q>0.7) are fundamental
properties of BDs. Current theories of BD formation do not appear to provide a
good description of all these properties.Comment: Accepted by ApJ (scheduled publication in volume 594, September 1,
2003
Farmers’ Accessibility to Pesticides and Generalization of Farming Practices besides the Legal Framework in Northern Bafou, in the Bamboutos Mountains (West Cameroon)
The use of pesticides improves farmers’ potential yield, but handling them with inexperienced hands increases the risk of human contamination and environmental pollution, and also reduces any prospect of sustainable agricultural development. Based on semi-structured interviews with pesticides dealers and other resource persons on the one hand, and a questionnaire administered to 120 households in the locality of Northern Bafou, this study highlights the environmental challenges posed by the widespread uncontrolled use of plant protection products. There is a wide range of pesticides found in Northern Bafou, marketed by dealers in different categories, ranging from authorized and unauthorized shops to unskilled street vendors, whose essentially mercantile objective has led to the availability of these products even to peasants not always aware of the dangers incurred by their misuse. This dysfunction contrasts with the existence of an expanded legal and institutional framework in Cameroon for the management of pesticides, that is not implemented effectively
A New Probe of the Planet-Forming Region in T Tauri Disks
We present new observations of the FUV (1100-2200 Angstrom) radiation field
and the near- to mid-IR (3--13.5 micron) spectral energy distribution (SED) of
a sample of T Tauri stars selected on the basis of bright molecular disks (GM
Aur, DM Tau, LkCa15). In each source we find evidence for Ly alpha induced H2
fluorescence and an additional source of FUV continuum emission below 1700
Angstroms. Comparison of the FUV spectra to a model of H2 excitation suggests
that the strong continuum emission is due to electron impact excitation of H2.
The ultimate source of this excitation is likely X-ray irradiation which
creates hot photo-electrons mixed in the molecular layer. Analysis of the SED
of each object finds the presence of inner disk gaps with sizes of a few AU in
each of these young (~1 Myr) stellar systems. We propose that the presence of
strong H2 continuum emission and inner disk clearing are related by the
increased penetration power of high energy photons in gas rich regions with low
grain opacity.Comment: 5 pages, 3 figures, accepted by ApJ Letter
The EDELWEISS Experiment : Status and Outlook
The EDELWEISS Dark Matter search uses low-temperature Ge detectors with heat
and ionisation read- out to identify nuclear recoils induced by elastic
collisions with WIMPs from the galactic halo. Results from the operation of 70
g and 320 g Ge detectors in the low-background environment of the Modane
Underground Laboratory (LSM) are presented.Comment: International Conference on Dark Matter in Astro and Particle Physics
(Dark 2000), Heidelberg, Germany, 10-16 Jul 2000, v3 minor revision
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