526 research outputs found
An aircraft Earth station for general aviation
While the focus has been international commercial air traffic, an opportunity exists to provide satellite communications to smaller aircraft. For these users equipment cost and weight critically impact the decision to install satellite communications equipment. Less apparent to the operator is the need for a system infrastructure that will be supported both regionally and internationally and that is compatible with the ground segment being installed for commercial aeronautical satellite communications. A system concept is described as well as a low cost terminal that are intended to satisfy the small aircraft market
Quantum Multibaker Maps: Extreme Quantum Regime
We introduce a family of models for quantum mechanical, one-dimensional
random walks, called quantum multibaker maps (QMB). These are Weyl
quantizations of the classical multibaker models previously considered by
Gaspard, Tasaki and others. Depending on the properties of the phases
parametrizing the quantization, we consider only two classes of the QMB maps:
uniform and random. Uniform QMB maps are characterized by phases which are the
same in every unit cell of the multibaker chain. Random QMB maps have phases
that vary randomly from unit cell to unit cell. The eigenstates in the former
case are extended while in the latter they are localized. In the uniform case
and for large , analytic solutions can be obtained for the time
dependent quantum states for periodic chains and for open chains with absorbing
boundary conditions. Steady state solutions and the properties of the
relaxation to a steady state for a uniform QMB chain in contact with
``particle'' reservoirs can also be described analytically. The analytical
results are consistent with, and confirmed by, results obtained from numerical
methods. We report here results for the deep quantum regime (large ) of
the uniform QMB, as well as some results for the random QMB. We leave the
moderate and small results as well as further consideration of the
other versions of the QMB for further publications.Comment: 17 pages, referee's and editor's comments addresse
Roma e la storia del Canada francese sino alla guerra dei Sette Anni
Presentation of the documents concerning New France and Canada in the Vatican Archive
State Transition Algorithm
In terms of the concepts of state and state transition, a new heuristic
random search algorithm named state transition algorithm is proposed. For
continuous function optimization problems, four special transformation
operators called rotation, translation, expansion and axesion are designed.
Adjusting measures of the transformations are mainly studied to keep the
balance of exploration and exploitation. Convergence analysis is also discussed
about the algorithm based on random search theory. In the meanwhile, to
strengthen the search ability in high dimensional space, communication strategy
is introduced into the basic algorithm and intermittent exchange is presented
to prevent premature convergence. Finally, experiments are carried out for the
algorithms. With 10 common benchmark unconstrained continuous functions used to
test the performance, the results show that state transition algorithms are
promising algorithms due to their good global search capability and convergence
property when compared with some popular algorithms.Comment: 18 pages, 28 figure
StarBorn : Towards making in-situ land cover data generation fun with a location-based game
University Research Priority Program: Language and Space, University of ZurichPeer reviewedPublisher PD
Experimental and Theoretical Study of Bound and Quasibound States of CE-
The negative ion of cerium is investigated experimentally with tunable infrared laser photodetachment spectroscopy and theoretically with relativistic configuration interaction in the continuum formalism. The relative cross section for neutral atom production is measured with a crossed ion-beam–laser-beam apparatus over the photon energy range of 0.54–0.75 eV. A rich resonance spectrum is revealed near the threshold with, at least, 12 peaks observed due to transitions from bound states of [formula] to either bound or quasibound excited states of the negative ion. Theoretical calculations of the photodetachment cross sections enable identification of the transitions responsible for the measured peaks. Two of the peaks are due to electric dipole-allowed bound-bound transitions in [formula], making cerium only the second atomic negative ion that has been demonstrated to support multiple bound states of opposite parity. In addition, combining the experimental data with the theoretical analysis determines the electron affinity of cerium to be 0.628(10) eV and the fine structure splitting of the ground state of [formula] ([formula]) to be 0.097 75(4) eV
Charged black holes: Wave equations for gravitational and electromagnetic perturbations
A pair of wave equations for the electromagnetic and gravitational
perturbations of the charged Kerr black hole are derived. The perturbed
Einstein-Maxwell equations in a new gauge are employed in the derivation. The
wave equations refer to the perturbed Maxwell spinor and to the shear
of a principal null direction of the Weyl curvature. The whole
construction rests on the tripod of three distinct derivatives of the first
curvature of a principal null direction.Comment: 12 pages, to appear in Ap.
Reactions of a Be-10 beam on proton and deuteron targets
The extraction of detailed nuclear structure information from transfer
reactions requires reliable, well-normalized data as well as optical potentials
and a theoretical framework demonstrated to work well in the relevant mass and
beam energy ranges. It is rare that the theoretical ingredients can be tested
well for exotic nuclei owing to the paucity of data. The halo nucleus Be-11 has
been examined through the 10Be(d,p) reaction in inverse kinematics at
equivalent deuteron energies of 12,15,18, and 21.4 MeV. Elastic scattering of
Be-10 on protons was used to select optical potentials for the analysis of the
transfer data. Additionally, data from the elastic and inelastic scattering of
Be-10 on deuterons was used to fit optical potentials at the four measured
energies. Transfers to the two bound states and the first resonance in Be-11
were analyzed using the Finite Range ADiabatic Wave Approximation (FR-ADWA).
Consistent values of the spectroscopic factor of both the ground and first
excited states were extracted from the four measurements, with average values
of 0.71(5) and 0.62(4) respectively. The calculations for transfer to the first
resonance were found to be sensitive to the size of the energy bin used and
therefore could not be used to extract a spectroscopic factor.Comment: 16 Pages, 10 figure
Antibodies to squalene in US Navy Persian Gulf War veterans with chronic multisymptom illness. Vaccine
a b s t r a c t Since the end of the 1991 Gulf War, there have been reports of unexplained, multisymptom illnesses afflicting veterans who consistently report more symptoms than do nondeployed veterans. One of the many possible exposures suspected of causing chronic multisymptom illnesses Gulf War veterans is squalene, thought to be present in anthrax vaccine. We examined the relationship between squalene antibodies and chronic symptoms reported by Navy construction workers (Seabees), n = 579. 30.2% were deployers, 7.4% were defined as ill, and 43.5% were positive for squalene antibodies. We found no association between squalene antibody status and chronic multisymptom illness (p = 0.465). The etiology of Gulf War syndrome remains unknown, but should not include squalene antibody status. Published by Elsevier Ltd
Recommended from our members
Testing of Large-Scale ICV Glasses with Hanford LAW Simulant
Preliminary glass compositions for immobilizing Hanford low-activity waste (LAW) by the in-container vitrification (ICV) process were initially fabricated at crucible- and engineering-scale, including simulants and actual (radioactive) LAW. Glasses were characterized for vapor hydration test (VHT) and product consistency test (PCT) responses and crystallinity (both quenched and slow-cooled samples). Selected glasses were tested for toxicity characteristic leach procedure (TCLP) responses, viscosity, and electrical conductivity. This testing showed that glasses with LAW loading of 20 mass% can be made readily and meet all product constraints by a far margin. Glasses with over 22 mass% Na2O can be made to meet all other product quality and process constraints. Large-scale testing was performed at the AMEC, Geomelt Division facility in Richland. Three tests were conducted using simulated LAW with increasing loadings of 12, 17, and 20 mass% Na2O. Glass samples were taken from the test products in a manner to represent the full expected range of product performance. These samples were characterized for composition, density, crystalline and non-crystalline phase assemblage, and durability using the VHT, PCT, and TCLP tests. The results, presented in this report, show that the AMEC ICV product with meets all waste form requirements with a large margin. These results provide strong evidence that the Hanford LAW can be successfully vitrified by the ICV technology and can meet all the constraints related to product quality. The economic feasibility of the ICV technology can be further enhanced by subsequent optimization
- …