Full-Duplex Digital Communication on a Single Laser Beam

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end

Epstein–Barr virus-associated inflammatory pseudotumor of the spleen: report of two cases and review of the literature

We report two rare examples of Epstein–Barr virus (EBV)-associated inflammatory pseudotumor of the spleen. One patient presented with night sweats, abdominal pain, and weight loss and was found to have a splenic mass on CT scan suspected of lymphoma. The splenic mass in second patient was found incidentally at the time of work up for kidney stones. The pathologic examination of these splenectomy specimens showed similar histologic features. However, the spindle cells were composed of EBV-infected follicular dendritic cells in one case whereas the second case lacked significant follicular dendritic cell proliferation and showed only focal EBV-infected cells suggesting that these proliferations are heterogenous in nature

Using State Space Exploration to Determine How Gene Regulatory Networks Constrain Mutation Order in Cancer Evolution

Cancer develops via the progressive accumulation of somatic mutations, which subvert the normal operation of the gene regulatory network of the cell. However, little is known about the order in which mutations are acquired in successful clones. A particular sequence of mutations may confer an early selective advantage to a clone by increasing survival or proliferation, or lead to negative selection by triggering cell death. The space of allowed sequences of mutations is therefore constrained by the gene regulatory network. Here, we introduce a methodology for the systematic exploration of the effect of every possible sequence of oncogenic mutations in a cancer cell modelled as a qualitative network. Our method uses attractor identification using binary decision diagrams and can be applied to both synchronous and asynchronous systems. We demonstrate our method using a recently developed model of ER-negative breast cancer. We show that there are differing levels of constraint in the order of mutations for different combinations of oncogenes, and that the effects of ErbB2/HER2 over-expression depend on the preceding mutations

Analyse par chromatographie en phase gazeuse couplée au spectromètre de masse d'hydrocarbures bicycliques et tricycliques isolés dans une coupe pétrolière

International audienceL'amélioration de certaines techniques de raffinage, en particulier l'optimisation des chargesde « reforming» [IJ demande une meilleure connaissance de la composition chimique d'un pétrolebrut. Celle-ci est relativement bien connue pour les fractions légères jusqu'à IS0 oC ; elle l'est moinspour les fractions au-delà de cette température. En particulier les alcanes bicycliques et tricycliquesde ces fractions ont été peu étudiés, bien que ces cyclanes puissent parfois constituer une fractionimportante (20 à 30 %) des coupes 150-225 oC provenant d'huiles naphténiques. Il est importantd'identifier ces substances afin de déterminer la composition de la coupe examinée. Si cet intérêtjustifie la recherche entreprise, les résultats pourraient également être utiles aux problèmes de corré-lations car ces alcanes bicycliques et tricycliques proviennent sans doute soit de dérivés ou de frag-ments de terpènes naturels, soit de substances à structures spécifiques: en conséquence certainspourraient se révéler être des marqueurs biologiques intéressants [3J ou des indicateurs de l'étatde diagénèse d'une matière organique donnée

Imaging spectrometer based on an acousto-optic tunable filter

International audienceThis article describes an imaging spectrometer developed for remote sensing applications. The instrument consists of an acousto-optic tunable filter (AOTF), a high sensitive charged coupled device camera and optic lens. The selected AOTF was designed to have a large entrance aperture and to diffract light between 600 and 900 nm with a high spectral resolution. The signal was digitized by the camera and acquired with a developed WINDOWS executable software which drives the instrument. The spectrometer has been operated in a classical mode and in an imaging mode for its evaluation. In the imaging mode, images including different types of targets were acquired in reflection and transmission mode and were used to investigate image homogeneity, spatial resolution, chromatic and geometric aberrations, sensitivity and reliability. Spectra have been extracted from images and were successfully compared with spectra from the same sample area obtained with classical nonimaging spectrometers. This confirms the ability of this instrument to clear up many problems in surface analysis, particularly in the case of laboratory and field measurements used in remote sensing studies

Immunohistochemistry in gastrointestinal pathology

Parmi les progrès récents réalisés en anatomie pathologique, l'immunohistochimie est au premier plan. Grâce aux nombreux anticorps monoclonaux utilisables sur coupes de tissus fixés. Elle est devenue très performante en pratique courante et particulièrement en pathologie digestive. La pathologie tumorale est son principal champ d'application (typage d'une tumeur maligne indifférenciée, diagnostic et typage d'un infiltrat lymphoïde, investigation d'un processus métastatique, évaluation de la prolifération cellulaire, appréciation des oncogènes...). Par ailleurs, en pathologie non tumorale, elle facilite l'étude des populations cellulaires et la reconnaissance des viru