Time maintenance of user clocks via the tracking and data relay satellite system

A system is described which uses the Tracking and Data Relay Satellite System (TDRSS) itself to compare the user satellite clock with a clock at the White Sands station that is referenced to Universal Time Coordinated (UTC). No command of the spacecraft by the system is required, and actual on-board clock corrections are made by the spacecraft control center at its discretion. Computer models were constructed using basic orbital parameters for user and TDRS satellites. With only first-order corrections and simple averaging techniques for constant clock rates, error measurement precision of better than one microsecond was obtained. More sophisticated computations should allow considerable improvement over this

Diffusion and Vision: A Case Study of the Ebenezer Doan House in Sharon, Ontario

This case study of the 1819 Ebenezer Doan house in Sharon, Ontario, illustrates ways in which a seemingly simple, straightforward building may be analyzed to yield information about its architectural antecedents and its builder's background and attitudes. It suggests how British and Germanic traditions were interwoven on the Pennsylvania frontier, modified, and brought to Upper Canada by American settlers. In the Doan house, the very traditional hall/kitchen, which was the focal point of family life, reflects the Doan family's concern for maintaining close ties with family and friends from Pennsylvania despite the disruption of migration to a distant land. The conservatism of vernacular builders like Ebenezer Doan, however, did not preclude vision or the will to innovate. The temple and study Doan built for a religious sect known as the Children of Peace attest to that. Résumé Cette recherche effectuée sur la maison Ebenezer Doan, qui fut érigée en 1819 à Sharon (Ontario), montre comment une construction qui semble ordinaire peut livrer des renseignements à propos des courants qui en ont influencé l'architecture et des informations sur le caractère et la formation de l'entrepreneur. On y reconnaît l'influence britannique et germanique particulière aux maisons de la Pennsylvanie. Les loyalistes avaient introduit et modifié ce style dans le territoire qui deviendra le Haut-Canada. La grande cuisine de type traditionnel de la maison Doan, centre de la vie familiale, indique à quel point la famille désirait préserver des relations étroites avec les parents et amis restés en Pennsylvanie, malgré l'obstacle de la distance créé par l'émigration. Les constructeurs comme Ebenezer faisaient preuve de conformisme, mais ceci ne les empêchait pas d'avoir une imagination créatrice et la volonté de l'exprimer. A preuve, nous pouvons nous référer au Temple et à la salle de travail que Doan construisit pour une secte religieuse appelée «-Les enfants de la Paix»

Cytotoxic Lymphocytes in Viral Hepatitis: a Thesis

The immunological mechanisms involved in virus-induced hepatitis were examined by measuring the cytotoxic capabilities and the morphological and antigenic phenotypes of leukocytes isolated from the livers of virus-infected mice. Large granular lymphocytes (LGL) of both natural killer (NK) cell and cytotoxic T lymphocyte (CTL) phenoytpes [phenotypes] accumulated in livers of mice infected with lymphocytic choriomeningitis virus (LCMV) of either the nonhepatotropic Armstrong strain (LCMV-ARM) or the hepatotropic WE strain (LCMV-WE). NK cell activity and LGL number increased 3- to 4-fold between days 1 and 5 postinfection (p.i.). These LGL were characterized as NK cells on the basis of cell surface antigens, kinetics of appearance, target cell range, and morphology. By day 7 p.i., virus-specific, H-2-restricted, Thy-1+, Lyt-2+CTL activity was present in the liver, and its appearance correlated with a second wave of LGL accumulation. Total CTL activity, leukocyte numbers, and CTL/LGL numbers were at least 5-fold higher in the livers of LCMV-WE-infected mice than in the livers of LCMV-ARM-infected mice. Mice infected with the cytopathic viruses, mouse hepatitis virus and murine cytomegalovirus, experienced greater increases in NK/LGL by day 3 p.i. than did mice either infected with LCMV or injected with poly I:C. The early and late accumulations of LGL in the virus-infected liver were associated with the appearance of two waves of LGL with blast cell morphology expressing the phenotypes of NK cells and CTL, respectively. Thus, the organ-associated accumulation, blastogenesis, and in situ proliferation of cytotoxic LGL provide a means for the localization and site-specific augmentation of a host\u27s cell-mediated antiviral defenses. The mechanism of inhibition of virus synthesis in vivo by immune splenocytes containing virus-specific CTL was examined in mice dually infected with two different viruses and then adoptively immunized with spleen cells immune to one of the two viruses. Only the titer of the virus to which the splenocytes were immune was reduced in titer, and no nonspecific antiviral effect was seen on the titer of the \u27bystander\u27 heterologous virus. These data are consistent with an in vivo mechanism of CTL-mediated antiviral resistance involving direct cytotoxicity rather than release and dissemination of antigen-nonspecific antiviral factors, such as interferon, following recognition of appropriate viral antigen

From Workshop To Factory: The Furnituremaker

This paper examines the working life of Ontario's nineteenth-century furniture workers. It begins with a consideration of the early craftsman who often held a variety of jobs in order to survive economically and who produced a wide variety of wooden items in addition to furniture. Training and apprenticeship often were arrangedinformally. Competition was keen, particularly by the 1830s when strong competition was felt from the United States and when Canadian manufacturers could order inexpensive parts from American factories. In Ontario, large-scale factory production began with Jacques and Hay's factories in Toronto and New Lowell in the 1850s. Further changes came at the turn of the century with the amalgamation of most major furniture factories in Ontario under the banner of Canada Furniture Manufacturers Limited. Traditional skills declined in the face of mass production and mechanization. Changes came gradually, however, and it would be a mistake to romanticize the life and work of the early craftsman. Résumé Cet article examine la vie professionnelle des travailleurs du meuble en Ontario, au XIXe siècle. Il étudie d'abord le cas des premiers artisans qui devaient, pour vivre, exercer souvent divers métiers et qui fabriquaient, outre les meubles, un large éventail d'objets en bois. La formation et l'apprentissage se faisaient souvent de façon informelle. La concurrence était forte, surtout à partir des années 1830, époque à laquelle les produits américains arrivèrent sur le marché et que les fabricants canadiens purent commander aux usines américaines des pièces bon marché. L'ouverture des usines Jacques et Hay à Toronto et à New Lowell, dans les années 1850, marqua le début de la production industrielle à grande échelle en Ontario. Un autre changement eut lieu à la fin du siècle dernier avec la fusion de la plupart des grandes usines de meuble ontariennes en une seule société, la Canada Furniture Manufacturers Limited. Les techniques traditionnelles cédèrent le pas à la production en série et à la mécanisation. Toutefois, les changements se firent graduellement et on aurait tort d'idéaliser la vie des premiers artisans

Self-pulsing dynamics in a cavity soliton laser

The dynamics of a broad-area vertical-cavity surface-emitting laser (VCSEL) with frequency-selective feedback supporting bistable spatial solitons is analyzed experimentally and theoretically. The transient dynamics of a switch-on of a soliton induced by an external optical pulse shows strong self-pulsing at the external-cavity round-trip time with at least ten modes excited. The numerical analysis indicates an even broader bandwidth and a transient sweep of the center frequency. It is argued that mode-locking of spatial solitons is an interesting and viable way to achieve three-dimensional, spatio-temporal self-localization and that the transients observed are preliminary indications of a transient cavity light bullet in the dynamics, though on a non negligible background