3,738 research outputs found
Future Facilities Summary
For the session on future facilities at DIS09 discussions were organized on
DIS related measurements that can be expected in the near and medium - or
perhaps far - future, including plans from JLab, CERN and FNAL fixed target
experiments, possible measurements and detector upgrades at RHIC, as well as
the plans for possible future electron proton/ion colliders such as the EIC and
the LHeC project.Comment: Summary of the parallel sessions on future facilities and the plenary
discussion session on possible future electron proton/ion colliders such as
the EIC and the LHeC project at the Deep Inelastic Scattering workshop in
Madrid, April 200
Model of large scale man-machine systems with an application to vessel traffic control
Mathematical models are discussed to deal with complex large-scale man-machine systems such as vessel (air, road) traffic and process control systems. Only interrelationships between subsystems are assumed. Each subsystem is controlled by a corresponding human operator (HO). Because of the interaction between subsystems, the HO has to estimate the state of all relevant subsystems and the relationships between them, based on which he can decide and react. This nonlinear filter problem is solved by means of both a linearized Kalman filter and an extended Kalman filter (in case state references are unknown and have to be estimated). The general model structure is applied to the concrete problem of vessel traffic control. In addition to the control of each ship, this involves collision avoidance between ship
The WFPC2 Archival Parallels Project
We describe the methods and procedures developed to obtain a near-automatic
combination of WFPC2 images obtained as part of the WFPC2 Archival Pure
Parallels program. Several techniques have been developed or refined to ensure
proper alignment, registration, and combination of overlapping images that can
be obtained at different times and with different orientations. We quantify the
success rate and the accuracy of the registration of images of different types,
and we develop techniques suitable to equalize the sky background without
unduly affecting extended emission. About 600 combined images of the 1,500
eventually planned have already been publicly released through the STScI
Archive. The images released to date are especially suited to study star
formation in the Magellanic Clouds, the stellar population in the halo of
nearby galaxies, and the properties of star-forming galaxies at .Comment: 12 pages, 7 figures, to appear in the PAS
Radiative corrections for (e,e′p) reactions at GeV energies
A general framework for applying radiative corrections to (e,e′p) coincidence reactions at GeV energies is presented, with special emphasis to higher-order bremsstrahlung effects, radiation from the scattered hadron, and the validity of peaking approximations. The sensitivity to the assumptions made in practically applying radiative corrections to (e,e′p) data is extensively discussed. The general framework is tested against experimental data of the 1H(e,e′p) reaction at momentum transfer values larger than 1.0 (GeV/c)^2, where radiative processes become a dominant source of uncertainty. The formulas presented here can easily be modified for any other electron-induced coincidence reaction
The He(e, ed)p Reaction in q-constant Kinematics
The cross section for the He(e, ed)p reaction has been measured as a
function of the missing momentum in q -constant kinematics at
beam energies of 370 and 576 MeV for values of the three-momentum transfer
of 412, 504 and 604 \mevc. The L(+TT), T and LT structure functions have been
separated for = 412 and 504 \mevc. The data are compared to three-body
Faddeev calculations, including meson-exchange currents (MEC), and to
calculations based on a covariant diagrammatic expansion. The influence of
final-state interactions and meson-exchange currents is discussed. The
-dependence of the data is reasonably well described by all calculations.
However, the most advanced Faddeev calculations, which employ the AV18
nucleon-nucleon interaction and include MEC, overestimate the measured cross
sections, especially the longitudinal part, and at the larger values of .
The diagrammatic approach gives a fair description of the cross section, but
under(over)estimates the longitudinal (transverse) structure function.Comment: 17 pages, 7 figure
Q^2 Evolution of Generalized Baldin Sum Rule for the Proton
The generalized Baldin sum rule for virtual photon scattering, the
unpolarized analogy of the generalized Gerasimov-Drell-Hearn integral, provides
an important way to investigate the transition between perturbative QCD and
hadronic descriptions of nucleon structure. This sum rule requires integration
of the nucleon structure function F_1, which until recently had not been
measured at low Q^2 and large x, i.e. in the nucleon resonance region. This
work uses new data from inclusive electron-proton scattering in the resonance
region obtained at Jefferson Lab, in combination with SLAC deep inelastic
scattering data, to present first precision measurements of the generalized
Baldin integral for the proton in the Q^2 range of 0.3 to 4.0 GeV^2.Comment: 4 pages, 3 figures, one table; text added, one figure replace
Ultramafic geoecology of South and Southeast Asia
Globally, ultramafic outcrops are renowned for hosting floras with high levels of endemism, including plants with specialised adaptations such as nickel or manganese hyperaccumulation. Soils derived from ultramafic regoliths are generally nutrient-deficient, have major cation imbalances, and have concomitant high concentrations of potentially phytotoxic trace elements, especially nickel. The South and Southeast Asian region has the largest surface occurrences of ultramafic regoliths in the world, but the geoecology of these outcrops is still poorly studied despite severe conservation threats. Due to the paucity of systematic plant collections in many areas and the lack of georeferenced herbarium records and databased information, it is not possible to determine the distribution of species, levels of endemism, and the species most threatened. However, site-specific studies provide insights to the ultramafic geoecology of several locations in South and Southeast Asia. The geoecology of tropical ultramafic regions differs substantially from those in temperate regions in that the vegetation at lower elevations is generally tall forest with relatively low levels of endemism. On ultramafic mountaintops, where the combined forces of edaphic and climatic factors intersect, obligate ultramafic species and hyperendemics often occur. Forest clearing, agricultural development, mining, and climate change-related stressors have contributed to rapid and unprecedented loss of ultramafic-associated habitats in the region. The geoecology of the large ultramafic outcrops of Indonesia’s Sulawesi, Obi and Halmahera, and many other smaller outcrops in South and Southeast Asia, remains largely unexplored, and should be prioritised for study and conservation
- …