1,210 research outputs found
The 737 graphite composite flight spoiler flight service evaluation
The flight-service experience of 110 graphite-epoxy spoilers on 737 transport aircraft and related ground-based environmental exposure of graphite-epoxy material specimens is reported. Spoilers were installed on each of 27 aircraft representing seven major airlines operating throughout the world. Based on visual, ultrasonic, and destructive testing, there is no evidence of moisture migration into the honeycomb core and no core corrosion. Tests of removed spoilers and of ground-based exposure specimens after the second year of service indicate modest changes in composite strength
The 737 graphite composite flight spoiler flight service evaluation
The flight service experience of 108 graphite-epoxy spoilers on 737 transport aircraft, and related ground-based environmental exposure of graphite-epoxy material specimens were evaluated. Four spoilers were installed on each of 27 aircraft for a 5-year study. As of February 28, 1975, a total of 294,280 spoiler flight-hours and 460,686 spoiler landings were accumulated. Based on visual, ultrasonic, and destructive testing, no moisture migration into the honeycomb core and no core corrosion has occurred. Tests of removed spoilers and of ground-based exposure specimens after the first year of service indicate no significant changes in composite strength
New theoretical method for calculating the radiative association cross section of a triatomic molecule: Application to N2-H-
We present a new theoretical method to treat the atom diatom radiative
association within a time independent approach. This method is an adaptation of
the driven equations method developed for photodissociation. The bound states
energies and wave functions of the molecule are calculated exactly and used to
propagate the overlap with the initial scattering wave function. In the second
part of this paper, this approach is applied to the radiative association of
the N2H- anion. The main features of the radiative association cross sections
are analysed and the magnitude of the calculated rate coefficient at 10 Kelvin
is used to discuss the existence of the N2H- in the interstellar medium which
could be used as a tracer of both N2 and H-
Preliminary design of graphite composite wing panels for commercial transport aircraft
Subjectively assessed practical and producible graphite/epoxy designs were subjected to a multilevel screening procedure which considered structural functions, efficiency, manufacturing and producibility, costs, maintainability, and inspectability. As each progressive screening level was reviewed, more definitive information on the structural efficiency (weight), manufacturing, and inspection procedures was established to support the design selection. The configuration features that enhance producibility of the final selected design can be used as a generic base for application to other wing panel designs. The selected panel design showed a weight saving of 25 percent over a conventional aluminum design meeting the same design requirements. The estimated cost reduction in manufacturing was 20 percent, based on 200 aircraft and projected 1985 automated composites manufacturing capability. The panel design background information developed will be used in the follow-on tasks to ensure that future panel development represents practical and producible design approaches to graphite/epoxy wing surface panels
Le trafic dâenfants albanais comme dĂ©ficit de citoyennetĂ©
Le trafic dâĂȘtres humains Ă©merge de profondes mutations sociales et Ă©conomiques, qui interdisent de naturaliser le phĂ©nomĂšne en lâattribuant Ă une « mentalité » particuliĂšre. Sortie du totalitarisme, lâAlbanie expĂ©rimente une libĂ©ralisation rapide guĂšre favorable Ă lâĂ©mergence dâacteurs collectifs et de pratiques citoyennes. Parmi les consĂ©quences du dĂ©ficit de participation dĂ©mocratique, le trafic dâenfants appelle des mĂ©diations sociales. Lâarticle privilĂ©gie les dimensions sociales du trafic et la perspective de lâacteur social comme complĂ©ment de lâapproche lĂ©gale dominante.Trafficking human beings stems from deep social and economical transformations, and the phenomenon cannot be attributed to a particular âmentalityâ. After its totalitarian period, Albania faces a rapid liberalisation hardly conducive to collective actors and practices linked to citizenship. Among the consequences of the deficit of democratic participation, child trafficking calls for social mediations. The article emphasizes the social dimensions of trafficking and the perspective of the social actor as a complement to the legal dominant approach
RĂŽle des leucocytes infectĂ©s du sperme dans la transmission muqueuse du VIH : modĂšle expĂ©rimental de lâinfection par le SIVmac251 de Macaca fascicularis
Human Immunodeficiency Virus (HIV) infection mostly spreads by the mucosal route: sexual transmission is the dominant mode of transmission, responsible for between 85% and 90% of cases of infection worldwide. These epidemiological data indicate that semen is one of the major sources of HIV-1 transmission. Semen, like other bodily secretions involved in HIV sexual transmission, contains the virus as two forms: cell-free viral particles and cell-associated virus, mostly in infected leukocytes. Although cell-to-cell HIV transmission has been extensively described as more efficient, rapid and resistant to host immune responses, very few studies have investigated the role in vivo of infected leukocytes in virus mucosal transmission. One such study has been recently conducted in our lab, and demonstrated that SIV-infected splenocytes are able to transmit infection to female macaques after vaginal exposure. However, all these studies used immune cells from peripheral blood or lymphoid tissues, such as spleen, and none have investigated the capacity of infected leukocytes in semen to transmit the infection in vivo. Indeed, nature, phenotype and infectivity of HIV associated with semen leukocytes may be different from that of HIV from other sources.Therefore, the objectives of this work are, first, to study of semen leukocytes and their dynamics during SIVmac251 infection in detail, then to investigate seminal factors that may influence semen infectiousness, and finally to test semen leukocyte infectivity in vitro and in vivo, using a model of mucosal exposure in cynomolgus macaques.Macaque semen contains all the target cells for HIV/SIV: CD4+ T cells, macrophages and dendritic cells in lower proportions. Semen CD4+ T cells and macrophages display an activation, differenciation and expression of migration markers profile which is typical of mucosal leucocytes. SIV infection induces significant changes in their phenotype and dynamics. Both cell types can be productively infected and are found in the semen at all stages of infection. These observations suggest that semen CD4+ T cells and macrophages may be able to transmit infection after mucosal exposure.If the role of semen infected leukocytes in HIV/SIV mucosal transmission is confirmed in vivo, this mechanism will be important to consider for further preventive strategies design, like microbicides.Aujourdâhui, plus de 80% des nouvelles infections par le virus de lâimmunodĂ©ficience humaine (VIH) se produisent au cours dâun rapport sexuel, avec une transmission du virus par voie muqueuse. Le sperme constitue donc une source majeure de virus Ă lâĂ©chelle mondiale. Le sperme dâhommes infectĂ©s par le VIH contient le virus sous deux formes : des particules virales libres et des cellules infectĂ©es, principalement des leucocytes.Plusieurs hypothĂšses ont Ă©tĂ© proposĂ©es afin dâexpliquer le passage du virus Ă travers la barriĂšre muqueuse, quâil sâagisse dâune muqueuse gĂ©nitale (cervico-vaginale, pĂ©nienne ou urĂ©trale) ou intestinale (muqueuse anale ou rectale). Toutefois, une grande majoritĂ© des Ă©tudes qui ont Ă©tĂ© menĂ©es jusquâĂ prĂ©sent se sont concentrĂ©es sur le rĂŽle des particules virales libres, et celui des cellules infectĂ©es demeure mal compris. Une Ă©tude menĂ©e dans notre laboratoire a montrĂ© que des leucocytes infectĂ©s par le virus de lâimmunodĂ©ficience simienne (VIS) sont capables de transmettre lâinfection aprĂšs inoculation vaginale.Le projet de cette thĂšse est dâĂ©tudier le rĂŽle des leucocytes infectĂ©s prĂ©sents dans le sperme de macaque dans la transmission muqueuse du VIS/VIH. Ainsi, trois axes dâĂ©tude principaux ont Ă©tĂ© dĂ©finis: 1) lâĂ©tude des leucocytes prĂ©sents dans le sperme de macaque cynomolgus, et de lâinfluence que peut avoir lâinfection par le VIS sur eux ; 2) lâidentification des cellules immunitaires infectĂ©es prĂ©sentes dans le sperme de macaque, et lâĂ©tude de leur dynamique au cours de lâinfection par le VIS. ; 3) lâĂ©tude du pouvoir infectieux des deux principales cellules cibles pour le VIS/VIH : les lymphocytes CD4+ (LT CD4+) et les macrophages, in vitro et in vivo, aprĂšs inoculation rectale et vaginale Ă des macaques cynomolgus.Le sperme de macaque contient toutes les cellules cibles du VIS/VIH : des lymphocytes T CD4+ (LTCD4+), des macrophages et des cellules dendritiques dans une moindre proportion). Les LTCD4+ et les macrophages du sperme prĂ©sentent un phĂ©notype dâactivation, de diffĂ©renciation et dâexpression de marqueurs de migration typique des leucocytes rĂ©sidant dans les tissus muqueux. Lâinfection par le VIS induit des changements significatifs dans leur phĂ©notype et leur dynamique. Ces deux types cellulaires peuvent ĂȘtre infectĂ©s de façon productive et sont prĂ©sents dans le sperme Ă tous les stades de lâinfection. Ces donnĂ©es suggĂšrent que les LTCD4+ et les macrophages du sperme seraient capables de transmettre lâinfection par voie muqueuse.Si le rĂŽle des leucocytes infectĂ©s du sperme est confirmĂ© in vivo, il sera important Ă lâavenir de prendre en compte ce mĂ©canisme de transmission dans le dĂ©veloppement de nouvelles stratĂ©gies prĂ©ventives de lâinfection par le VIH, notamment les microbicides
Electron-impact rotational and hyperfine excitation of HCN, HNC, DCN and DNC
Rotational excitation of isotopologues of HCN and HNC by thermal
electron-impact is studied using the molecular {\bf R}-matrix method combined
with the adiabatic-nuclei-rotation (ANR) approximation. Rate coefficients are
obtained for electron temperatures in the range 56000 K and for transitions
among all levels up to J=8. Hyperfine rates are also derived using the
infinite-order-sudden (IOS) scaling method. It is shown that the dominant
rotational transitions are dipole allowed, that is those for which . The hyperfine propensity rule is found to be stronger
than in the case of HeHCN collisions. For dipole allowed transitions,
electron-impact rates are shown to exceed those for excitation of HCN by He
atoms by 6 orders of magnitude. As a result, the present rates should be
included in any detailed population model of isotopologues of HCN and HNC in
sources where the electron fraction is larger than 10, for example in
interstellar shocks and comets.Comment: 12 pages, 4 figures, accepted in MNRAS (2007 september 3
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