The Economic Value of Remote Sensing of Earth Resources from Space: An ERTS Overview and the Value of Continuity of Service. Volume 1: Summary

An overview of the ERTS program is given to determine the magnitude of the benefits that can be reasonably expected to flow from an Earth Resources Survey (ERS) Program, and to assess the benefits foregone in the event of a one or two-year gap in ERS services. An independent evaluation of the benefits attributable to ERS-derived information in key application areas is presented. These include two case studies in agriculture-distribution, production and import/export, and one study in water management. The cost-effectiveness of satellites in an ERS system is studied by means of a land cover case study. The annual benefits achieveable from an ERS system are measured by the in-depth case studies to be in the range of $430 to$746 million. Benefits foregone in the event of a one-year gap in ERS service are estimated to be $147 to$220 million and $274 to$420 million for a two-year gap in ERS service

Shell Structures and Chaos in Deformed Nuclei and Large Metallic Clusters

A reflection-asymmetric deformed oscillator potential is analysed from the classical and quantum mechanical point of view. The connection between occurrence of shell structures and classical periodic orbits is studied using the ''removal of resonances method'' in a classical analysis. In this approximation, the effective single particle potential becomes separable and the frequencies of the classical trajectories are easily determined. It turns out that the winding numbers calculated in this way are in good agreement with the ones found from the corresponding quantum mechanical spectrum using the particle number dependence of the fluctuating part of the total energy. When the octupole term is switched on it is found that prolate shapes are stable against chaos whereas spherical and oblate cases become chaotic. An attempt is made to explain this difference in the quantum mechanical context by looking at the distribution of exceptional points which results from the matrix structure of the respective Hamiltonians. In a similar way we analyse the modified Nilsson model and discuss its consequences for nuclei and metallic clusters.Comment: to appear in Physica Scripta., CNLS-94-02, a talk given at the Nobel sponsored conference SELMA 94 "New Nuclear Phenomena in the Vicinity of Closed Shell" (Stockholm and Uppsala, 29 Aug.- 3 Sept. 1994

Resonance scattering and singularities of the scattering function

Recent studies of transport phenomena with complex potentials are explained by generic square root singularities of spectrum and eigenfunctions of non-Hermitian Hamiltonians. Using a two channel problem we demonstrate that such singularities produce a significant effect upon the pole behaviour of the scattering matrix, and more significantly upon the associated residues. This mechanism explains why by proper choice of the system parameters the resonance cross section is increased drastically in one channel and suppressed in the other channel.Comment: 4 pages, 3 figure

Deformation of Quantum Dots in the Coulomb Blockade Regime

We extend the theory of Coulomb blockade oscillations to quantum dots which are deformed by the confining potential. We show that shape deformations can generate sequences of conductance resonances which carry the same internal wavefunction. This fact may cause strong correlations of neighboring conductance peaks. We demonstrate the relevance of our results for the interpretation of recent experiments on semiconductor quantum dots.Comment: 4 pages, Revtex, 4 postscript figure

Orbital Magnetism in Small Quantum Dots with Closed Shells

It is found that various kind of shell structure which occurs at specific values of the magnetic field leads to the disappearance of the orbital magnetization for particular magic numbers of small quantum dots with an electron number $A < 30$.Comment: 4 pages, latex file, four figures as postscript files, to appear at JETP Letters, December 199

Instabilities, nonhermiticity and exceptional points in the cranking model

A cranking harmonic oscillator model, widely used for the physics of fast rotating nuclei and Bose-Einstein condensates, is re-investigated in the context of PT-symmetry. The instability points of the model are identified as exceptional points. It is argued that - even though the Hamiltonian appears hermitian at first glance - it actually is not hermitian within the region of instability.Comment: 4 pages, 1 figur

Collectivity, Phase Transitions and Exceptional Points in Open Quantum Systems

Phase transitions in open quantum systems, which are associated with the formation of collective states of a large width and of trapped states with rather small widths, are related to exceptional points of the Hamiltonian. Exceptional points are the singularities of the spectrum and eigenfunctions, when they are considered as functions of a coupling parameter. In the present paper this parameter is the coupling strength to the continuum. It is shown that the positions of the exceptional points (their accumulation point in the thermodynamical limit) depend on the particular type and energy dependence of the coupling to the continuum in the same way as the transition point of the corresponding phase transition.Comment: 22 pages, 4 figure

Chaos in Axially Symmetric Potentials with Octupole Deformation

Classical and quantum mechanical results are reported for the single particle motion in a harmonic oscillator potential which is characterized by a quadrupole deformation and an additional octupole deformation. The chaotic character of the motion is srongly dependent on the quadrupole deformation in that for a prolate deformation virtually no chaos is discernible while for the oblate case the motion shows strong chaos when the octupole term is turned on.Comment: 6 pages LaTex plus 4 figures available by contacting the authors directly, published in PHYS.REV.LETT. 72(1994) 235

The economic value of remote sensing by satellite: An ERTS overview and the value of continuity of service. Volume 2: Source document

The economic value of an ERS system with a technical capability similar to ERTS, allowing for increased coverage obtained through the use of multiple active satellites in orbit is presented. A detailed breakdown of the benefits achievable from an ERS system is given and a methodology for their estimation is established. The ECON case studies in agriculture, water use, and land cover are described along with the current ERTS system. The cost for a projected ERS system is given

IV-VI resonant cavity enhanced photodetectors for the midinfrared

A resonant-cavity enhanced detector operating in the mid-infrared at a wavelength around 3.6 micron is demonstrated. The device is based on a narrow-gap lead salt heterostructure grown by molecular beam epitaxy. Below 140 K, the photovoltage clearly shows a single narrow cavity resonance, with a relative line width of only 2 % at 80 K.Comment: 2 figure