The Economics of Small Worlds

We examine a simple economic model of network formation where agents benefit from indirect relationships. We show that small-world features—short path lengths between nodes together with highly clustered link structures—necessarily emerge for a wide set of parameters

Vacuum-stripped silicone binder for thermal-control paint

Silicone elastomer is placed in evacuating system, heated to 160 C and held at this temperature for 24 hours. Elastomer is then cooled to room temperature in vacuum, producing upgraded, low outgassing polymer of increased molecular weight

The Economics of Small Worlds

We examine a simple economic model of network formation where agents benefit from indirect relationships. We show that small-world features - -- short path lengths between nodes together with highly clustered link structures --- necessarily emerge for a wide set of parameters.networks, small worlds

Development of S-13G-type coatings as engineering materials Final report, 1 Sep. 1966 - 31 Aug. 1968

S-13G type thermal control coatings for space application

The behavior of several white pigments as determined by in situ reflectance measurements of irradiated specimens

Reflectance measurements of irradiated specimens of zinc oxide and zinc orthotitanate white pigment material

Analysis of a fixed-pitch X-wing rotor employing lower surface blowing

Lower surface blowing (LSB) is investigated as an alternative to the variable blade pitch requirement for the X-wing Circulation Control (CC) rotor concept. Addition trailing edge blowing slots on the lower surfaces of CC airfoils provide a bidirectional lift capability that effectively doubles the control range. The operational requirements of this rotor system are detailed and compared to the projected performance attributes of LSB airfoils. Analysis shows that, aerodynamically, LSB supplies a fixed pitch rotor system with the equivalent lift efficiency and rotor control of present CC rotor designs that employ variable blade pitch. Aerodynamic demands of bidirectional lift production are predicted to be within the capabilities of current CC airfoil design methodology. Emphasis in this analysis is given to the high speed rotary wing flight regime unique to stoppable rotor aircraft. The impact of a fixed pitch restriction in hover and low speed flight is briefly discussed

Development of space stable thermal control coatings Triannual report, Mar. 1 - Jul. 31, 1967

Ultraviolet irradiation effects on space stable thermal control zinc coating

Alternative Paradigms for Structuring Collegiate Flight Programs

Collegiate aviation programs traditionally have been modeled on industry flight training programs, as exemplified by the U. S. Military and the airlines industry. Recently university administrators have been urging a shift in such programs to a more conventional academic paradigm where faculty are required hold doctoral degrees and to publish regularly. Such a transition may not succeed for a number of reasons, including the fact that faculty in aviation programs with extensive experience flying heavy aircraft typically do not hold the PhD degree and often have little or no interest in publishing scholarly papers. At the same time, the need to conduct funded research in aviation universities cannot be ignored. A possible solution to these contradictions lies in allowing some faculty in collegiate programs to teach and provide service to the university, which encouraging others so inclined to accept reduced teaching and service loads in exchange for pursuing funded research grants

Evolution of Small Putative Group I Introns in the SSU rRNA Gene Locus of Phialophora Species

Background: Group I introns (specifically subgroup IC1) are common in the nuclear ribosomal RNA genes of fungi. While most range in length from more than 200 to nearly 1800 nucleotides (nt) in length, several small putative (or degenerate) group I introns have been described that are between 56 and 81 nt. Although small, previously we demonstrated that the PaSSU intron in the rRNA small subunit gene of Phialophora americana isolate Wang 1046 is capable of in vitro splicing using a standard group I intron pathway, thus qualifying it as a functional ribozyme. Findings. Here, we describe eight short putative group I introns, ranging in length from 63 to 75 nt, in the rRNA small subunit genes of Phialophora isolates, a fungal genus that ranges from saprobic to pathogenic on plants and animals. All contain putative pairing regions P1, P7, and P10, as well as a pairing region formed between the middle of the intron and part of the 3\u27 exon. The other pairing regions common in the core of standard group I introns are absent. However, parts of the 3\u27 exon may aid in the stabilization of these small introns. Although the eight putative group I introns were from at least three species of Phialophora, phylogenetic analysis indicated that the eight are monophyletic. They are also monophyletic with the small introns of two lichen-forming fungi, Porpidia crustulata and Arthonia lapidicola. Conclusions: The small putative group I introns in Phialophora have common features that may represent group I introns at their minima. They appear to have a single origin as indicated by their monophyly in phylogenetic analyses. © 2011 Rogers et al; licensee BioMed Central Ltd