Mars Observer Radar Altimeter Radiometer (MORAR)

The Mars Observer Project will permit the advancement of the state of the topographic and hypsometric knowledge of Mars to a level of 10 m or better over the surface of the planet Mars, the measurement of microwave surface brightness temperature of Mars with an accuracy of 15 to 20 K over 24 hours, and the measurement, globally, of surface returned power related to radar cross section with an accuracy of 1 dB and a repeatability of .5 dB. The MORAR Hardware Development, Ground Data Processing, and the Mission Operations will allow the accomplishment of these scientific objectives to define globally the topography of Mars at sufficient vertical resolution and spatial scale to address both large-scale geophysical and small-scale geologic problems, and to obtain global surface electrical and scattering properties of the upper several centimeters of the Martian surface for assessment of the composition, physical state, and volatile distribution of the surface

Topography Experiment (TOPEX) Software Document Series Volume 7: TOPEX Mission Radar Altimeter Engineering Assessment Report, February 1994

This document describes the GSFC/WFF analysis of the on-orbit engineering data from the TOPEX radar altimeter, to establish altimeter performance. In accordance with Project guidelines, neither surface truth nor precision orbital data are used for the engineering assessment of the altimeter. The use of such data would imply not only a more intensive and complete performance evaluation, but also a calibration. Such evaluations and.calibrations are outside the scope of this document and will be presented in a separate Verification Report

Circumpolar Diversity and Geographic Differentiation of mtDNA in the Critically Endangered Antarctic Blue Whale (Balaenoptera musculus intermedia)

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work.\ud This is the publisher’s final pdf. The published article is copyrighted by the Public Library of Science and can be found at: http://www.plosone.org/home.action.The Antarctic blue whale (Balaenoptera musculus intermedia) was hunted to near extinction between 1904 and 1972, declining from an estimated initial abundance of more than 250,000 to fewer than 400. Here, we describe mtDNA control region diversity and geographic differentiation in the surviving population of the Antarctic blue whale, using 218 biopsy samples collected under the auspices of the International Whaling Commission (IWC) during research cruises from 1990-2009. Microsatellite genotypes and mtDNA sequences identified 166 individuals among the 218 samples and documented movement of a small number of individuals, including a female that traveled at least 6,650 km or 131 degrees longitude over four years. mtDNA sequences from the 166 individuals were aligned with published sequences from 17 additional individuals, resolving 52 unique haplotypes from a consensus length of 410 bp. From this minimum census, a rarefaction analysis predicted that only 72 haplotypes (95% CL, 64, 86) have survived in the contemporary population of Antarctic blue whales. However, haplotype diversity was relatively high (0.968 +/- 0.004), perhaps as a result of the longevity of blue whales and the relatively recent timing of the bottleneck. Despite the potential for circumpolar dispersal, we found significant differentiation in mtDNA diversity (F-ST = 0.032, p<0.005) and microsatellite alleles (F-ST = 0.005, p<0.05) among the six Antarctic Areas historically used by the IWC for management of blue whales

Empirical study of BIM implementation–based perceptions among Chinese practitioners

The global movement of building information modeling (BIM) is spreading the implementation of BIM from developed countries to other developing countries. Practitioners’ perceptions of BIM implementation in these developing countries, such as China, a giant building market that is increasing the application of BIM in the industry, have not been thoroughly understood. This research used the questionnaire method to survey 94 randomly recruited Chinese BIM professionals to investigate BIM practice and its related perceptions. Reductions in design errors and resultant construction rework were considered the top benefits of using BIM. The most important factor in achieving BIM value was noted as interoperability among various BIM tools. A comprehensive evaluation of BIM at the company level was considered a major difficulty of implementing BIM. The owner was considered the party that received the most benefits from BIM. Subgroup differences based on two major categories (i.e., participants’ profession and BIM proficiency level) were analyzed in the survey sections related to BIM implementation. Statistical analysis revealed that, generally, neither the profession nor BIM proficiency level affected participants’ perceptions of the benefits, factors, challenges, or benefited parties in BIM implementation

Some Useful Coding Techniques for Binary Communication Systems

An introduction to coding theory and a discussion of specific coding techniques are given as applied to digital communication systems. The place of coding in a communication system is illustrated and the various approaches to coding are discussed. The information theory concepts required are presented along with the First and Second Fundamental Theorems of Shannon, The relation between Shannon’s theorems and coding for the noisy and noiseless channel is discussed. For the noiseless channel the techniques of Shannon, Fano, Huffman, Gilbert-More, Karp and others are discussed. For the noisy channel, the techniques of Hamming, Slepian, Elias, Cowell, Bose-Chaudhuri, Reed-Muller, Fire, and Wozencraft are presented. The relationships between the various codes are given and the advantages and disadvantages of each indicated. Numerous examples illustrating the use of the codes are given and areas of further research outlined

Inelastic X-ray scattering from valence electrons near absorption edges of FeTe and TiSe2_2

We study resonant inelastic x-ray scattering (RIXS) peaks corresponding to low energy particle-hole excited states of metallic FeTe and semi-metallic TiSe$_2$ for photon incident energy tuned near the $L_{3}$ absorption edge of Fe and Ti respectively. We show that the cross section amplitudes are well described within a renormalization group theory where the effect of the core electrons is captured by effective dielectric functions expressed in terms of the the atomic scattering parameters $f_1$ of Fe and Ti. This method can be used to extract the dynamical structure factor from experimental RIXS spectra in metallic systems.Comment: 6 pages, 4 figure

Boson-Fermion coherence in a spherically symmetric harmonic trap

We consider the photoassociation of a low-density gas of quantum-degenerate trapped fermionic atoms into bosonic molecules in a spherically symmetric harmonic potential. For a dilute system and the photoassociation coupling energy small compared to the level separation of the trap, only those fermions in the single shell with Fermi energy are coupled to the bosonic molecular field. Introducing a collective pseudo-spin operator formalism we show that this system can then be mapped onto the Tavis-Cummings Hamiltonian of quantum optics, with an additional pairing interaction. By exact diagonalization of the Hamiltonian, we examine the ground state and low excitations of the Bose-Fermi system, and study the dynamics of the coherent coupling between atoms and molecules. In a semiclassical description of the system, the pairing interaction between fermions is shown to result in a self-trapping transition in the photoassociation, with a sudden suppression of the coherent oscillations between atoms and molecules. We also show that the full quantum dynamics of the system is dominated by quantum fluctuations in the vicinity of the self-trapping solution.Comment: 16 pages, 14 figure

Ocean topography experiment (TOPEX) radar altimeter

A spaceflight qualified Radar Altimeter capable of achieving the TOPEX Mission measurement precision requirement of 2-centimeters, is provided and its performance (Engineering Assessment) will be evaluated after launch and continuously during its 3-year mission operational period. Information will be provided to JPL about the calibration of the TOPEX Radar Altimeter. The specifications for the required data processing algorithms which will be necessary to convert the Radar Altimeter mission telemetry data into the geophysical data will also be provided. The stringent 2 cm precision requirement for ocean topography determination from space necessitated examining existing Radar Altimeter designs for their applicability towards TOPEX. As a result, a system configuration evolved using some flight proven designs in conjunction with needed improvements which include: (1) a second frequency or channel to remove the range delay or apparent height bias caused by the electron content of the ionosphere; (2) higher transmit pulse repetition frequencies for correlation benefits at higher sea states to maintain precision; and (3) a faster microprocessor to accommodate two channels of altimetry data. Additionally, examination of past altimeter programs associated data processing algorithms was accomplished to establish the TOPEX-class Radar Altimeter data processing algorithms, and the necessary direction was outlined to begin to generate these for the TOPEX Mission