Modularity, Vertical Integration, and Open Access Policies: Towards A Convergence of Antitrust and Regulation In The Internet Age

This article aims to help regulators and commentators incorporate both Chicago School and post-Chicago School arguments in assessing whether regulation should mandate open access to information platforms. The authors outline three alternative models that the FCC could adopt to guide its regulation of information platforms in the future and facilitate a true convergence between antitrust and regulatory policy.

Pencil-Beam Surveys for Faint Trans-Neptunian Objects

We have conducted pencil-beam searches for outer solar system objects to a limiting magnitude of R ~ 26. Five new trans-neptunian objects were detected in these searches. Our combined data set provides an estimate of ~90 trans-neptunian objects per square degree brighter than ~ 25.9. This estimate is a factor of 3 above the expected number of objects based on an extrapolation of previous surveys with brighter limits, and appears consistent with the hypothesis of a single power-law luminosity function for the entire trans-neptunian region. Maximum likelihood fits to all self-consistent published surveys with published efficiency functions predicts a cumulative sky density Sigma(<R) obeying log10(Sigma) = 0.76(R-23.4) objects per square degree brighter than a given magnitude R.Comment: Accepted by AJ, 18 pages, including 6 figure

Modularity, Vertical Integration, and Open Access Policies: Towards a Convergence of Antitrust and Regulation in the Internet Age

Antitrust law and telecommunications regulation have long adopted different stances on whether to mandate open access to information platforms. This article aims to help regulators and commentators incorporate both Chicago School and post-Chicago School arguments in evaluating this basic policy choice, suggesting how they can be integrated in an effective manner. In particular, the authors outline three alternative models that the FCC could adopt to guide its regulation of information platforms and facilitate a true convergence between antitrust and regulatory policy

Histology and affinity of anaspids, and the early evolution of the vertebrate dermal skeleton

The assembly of the gnathostome bodyplan constitutes a formative episode in vertebrate evolutionary history, an interval in which the mineralized skeleton and its canonical suite of cell and tissue types originated. Fossil jawless fishes, assigned to the gnathostome stem-lineage, provide an unparalleled insight into the origin and evolution of the skeleton, hindered only by uncertainty over the phylogenetic position and evolutionary significance of key clades. Chief among these are the jawless anaspids, whose skeletal composition, a rich source of phylogenetic information, is poorly characterized. Here we survey the histology of representatives spanning anaspid diversity and infer their generalized skeletal architecture. The anaspid dermal skeleton is composed of odontodes comprising spheritic dentine and enameloid, overlying a basal layer of acellular parallel fibre bone containing an extensive shallow canal network. A recoded and revised phylogenetic analysis using equal and implied weights parsimony resolves anaspids as monophyletic, nested among stem-gnathostomes. Our results suggest the anaspid dermal skeleton is a degenerate derivative of a histologically more complex ancestral vertebrate skeleton, rather than reflecting primitive simplicity. Hypotheses that anaspids are ancestral skeletonizing lampreys, or a derived lineage of jawless vertebrates with paired fins, are rejected

Microwave System for Detecting Ice on Aircraft

A microwave-based system has been developed as a means of detecting ice on aircraft surfaces, with enough sensitivity to provide a warning before the ice accretes to a dangerous thickness. The system can measure the thickness of ice from a few mils (1 mil = 0.0254 mm) to about 1/4 in. (.6 mm) and can distinguish among (1) ice, (2) water (or deicing fluid), and (3) a mixture of ice and water (or deicing fluid). Sensors have been ruggedized to withstand the rain erosion environment

Design and implementation issues for Stewart Platform configuration machine tools

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.Includes bibliographical references (leaves 56-57).by Philip J. Houdek, II.M.S

SOAR 89: Space Station. Space suit test program

The elements of the test program for the space suit to be used on Space Station Freedom are noted in viewgraph form. Information is given on evaluation objectives, zero gravity evaluation, mobility evaluation, extravehicular activity task evaluation, and shoulder joint evaluation

The Management of Extrahepatic Portal Vein Aneurysms: Observe or Treat?

A case of a 70 year old man who was found to have an extrahepatic portal vein aneurysm during an evaluation for hematuria is reported. Extrahepatic portal vein aneurysms are rare with only twenty cases reported in the literature. Typically, patients present with hemorrhage requiring surgical exploration or the aneurysm is discovered during evaluation of another abdominal process. Management includes careful follow-up in the asymptomatic patient without underlying liver disease or portal hypertension