Automatic computation of data-set definitions

Mathematical method for the construction of a computer program data set description from a computer program contains detailed declarative information. Cartesian products and disjoint-union operators are used to yield a series of recursive group equations

Variability in Plio-Pleistocene climates, habitats, and ungulate biomass in southern Africa

Vrba, and deMenocal and Bloemendal have emphasised the importance of climatic change, particularly temperature, in the context of evolution on the African continent within the past 5 million years. There is no doubt that long-term changes in climate would have affected African habitats, which in turn would have affected the distribution and abundance of populations of various mammalian taxa, including ungulates and hominids. In this study we explore relationships between oxygen isotope ratios (as determined from Shackleton's analysis of foraminifera from deep-sea cores), and estimates of ungulate biomass as determined from faunal assemblages from Plio-Pleistocene sites in southern Africa, using an approach outlined previously. We go further to assess temporal variability in ungulate biomass in terms of changes in habitat, gene pools and hominid evolutio

Apollo telescope mount: A partial listing of scientific publications, supplement 2

Reports are compilations of bibliographies from the principal investigator groups of the Apollo Telescope Mount (Skylab solar observatory facility) that gathered data from May 28, 1973, to February 8, 1974. The analysis of these data is presently under way and is expected to continue for several years. The publications listed in this report are divided into the following categories: (1) Journal Publications, (2) Journal Publications Submitted, (3) Other Publications, (4) Presentations--National and International Meetings, and (5) Other Presentations. An author index is included together with errata for the first report

Apollo telescope mount. A partial listing of scientific publications and presentations, supplement 1

Compilations of bibliographies from the principal investigator groups of the Apollo Telescope Mount (Skylab solar observatory facility) are presented. The publications listed are divided into the following categories: (1) journal publications, (2) journal publications submitted, (3) other publications, (4) presentations - national and international meetings; and (5) other presentations

A Search for Ionized Gas in the Draco and Ursa Minor Dwarf Spheroidal Galaxies

The Wisconsin H Alpha Mapper has been used to set the first deep upper limits on the intensity of diffuse H alpha emission from warm ionized gas in the Local Group dwarf spheroidal galaxies (dSphs) Draco and Ursa Minor. Assuming a velocity dispersion of 15 km/s for the ionized gas, we set limits for the H alpha intensity of less or equal to 0.024 Rayleighs and less or equal to 0.021 Rayleighs for the Draco and Ursa Minor dSphs, respectively, averaged over our 1 degree circular beam. Adopting a simple model for the ionized interstellar medium, these limits translate to upper bounds on the mass of ionized gas of approximately less than 10% of the stellar mass, or approximately 10 times the upper limits for the mass of neutral hydrogen. Note that the Draco and Ursa Minor dSphs could contain substantial amounts of interstellar gas, equivalent to all of the gas injected by dying stars since the end of their main star forming episodes more than 8 Gyr in the past, without violating these limits on the mass of ionized gas.Comment: 10 pages, 2 figures, AASTeX two-column format. Accepted for publication in The Astrophysical Journa

The matter content of the jet in M87: evidence for an electron-positron jet

Recent observations have allowed the geometry and kinematics of the M87 jet to be tightly constrained. We combine these constraints with historical Very Long Baseline Interferometry (VLBI) results and the theory of synchrotron self-absorbed radio cores in order to investigate the physical properties of the jet. Our results strongly suggest the jet to be dominated by an electron-positron (pair) plasma. Although our conservative constraints cannot conclusively dismiss an electron-proton plasma, the viability of this solution is extremely vulnerable to further tightening of VLBI surface brightness limits. The arguments presented, coupled with future high-resolution multi-frequency VLBI studies of the jet core, will be able to firmly distinguish these two possibilities.Comment: 8 pages, 1 ps figure. Revised and accepted for publication in MNRA