The new generation of gravitational waves detectors require unprecedented levels of isolation from seismic noise. This article reviews the seismic isolation strategy and instrumentation developed for ...the Advanced LIGO observatories. It summarizes over a decade of research on active inertial isolation and shows the performance recently achieved at the Advanced LIGO observatories. The paper emphasizes the scientific and technical challenges of this endeavor and how they have been addressed. An overview of the isolation strategy is given. It combines multiple layers of passive and active inertial isolation to provide suitable rejection of seismic noise at all frequencies. A detailed presentation of the three active platforms that have been developed is given. They are the hydraulic pre-isolator, the single-stage internal isolator and the two-stage internal isolator. The architecture, instrumentation, control scheme and isolation results are presented for each of the three systems. Results show that the seismic isolation sub-system meets Advanced LIGO's stringent requirements and robustly supports the operation of the two detectors.
The two-stage vibration isolation and positioning platform provides passive and active isolation in all directions and translation. It uses a unique combination of position sensors, geophones and ...broadband seismometers to provide unprecedented levels of isolation.
•The paper presents the two-stage vibration isolation and positioning platform used in Advanced LIGO gravitational waves detectors.•The system can support a 1000kg of sensitive equipment and operate in ultra-high vacuum.•Each of the two stages provide passive and active isolation in all directions of translation and rotation (12 axis).•The active control strategy uses a unique combination of relative sensors, geophones and broadband seismometers.•The system reduces the motion to the level of 10−11 m/Hz at 1Hz and 10−12 m/Hz at 10Hz.
New generations of gravity wave detectors require unprecedented levels of vibration isolation. This paper presents the final design of the vibration isolation and positioning platform used in Advanced LIGO to support the interferometer's core optics. This five-ton two-and-half-m wide system operating in ultra-high vacuum. It features two stages of isolation mounted in series. The stages are imbricated to reduce the overall height. Each stage provides isolation in all directions of translation and rotation. The system is instrumented with a unique combination of low noise relative and inertial sensors. The active control provides isolation from 0.1Hz to 30Hz. It brings the platform motion down to 10−11 m/Hz at 1Hz. Active and passive isolation combine to bring the platform motion below 10−12 m/Hz at 10Hz. The passive isolation lowers the motion below 10−13 m/Hz at 100Hz. The paper describes how the platform has been engineered not only to meet the isolation requirements, but also to permit the construction, testing, and commissioning process of the fifteen units needed for Advanced LIGO observatories.
The two-stage vibration isolation and positioning platform (BSC-ISI) provides three orders of magnitude of isolation at all frequencies above 1Hz.
•The paper presents near a decade of research on the ...two-stage twelve-axis vibration isolation platforms developed for Advanced LIGO.•This system positions and isolates 1000kg of very sensitive equipment in all directions of translation and rotation.•The system provides more than three orders of magnitude of isolation over a very large bandwidth.•We show how results from the prototyping phases have been used for the production and commissioning of 15 units.•Isolation results show that the system brings the motion below 10−11m/Hz at 1Hz and 10−12 m/Hz at 10Hz.
This paper presents the results of the past seven years of experimental investigation and testing done on the two-stage twelve-axis vibration isolation platform for Advanced LIGO gravity waves observatories. This five-ton two-and-half-meter wide system supports more than a 1000kg of very sensitive equipment. It provides positioning capability and seismic isolation in all directions of translation and rotation. To meet the very stringent requirements of Advanced LIGO, the system must provide more than three orders of magnitude of isolation over a very large bandwidth. It must bring the motion below 10−11 m/Hz at 1Hz and 10−12 m/Hz at 10Hz. A prototype of this system has been built in 2006. It has been extensively tested and analyzed during the following two years. This paper shows how the experimental results obtained with the prototype were used to engineer the final design. It highlights how the engineering solutions implemented not only improved the isolation performance but also greatly simplified the assembly, testing, and commissioning process. During the past two years, five units have been constructed, tested, installed and commissioned at each of the two LIGO observatories. Five other units are being built for an upcoming third observatory. The test results presented show that the system meets the motion requirements, and reach the sensor noise in the control bandwidth.
Les facteurs de risque de mortalité modifiables sont peu étudiés dans la SEP. La défavorisation socioéconomique et une mauvaise accessibilité aux soins sont deux facteurs de risque avérés dans ...d’autres pathologies.
L’objectif était d’examiner l’influence de la défavorisation socioéconomique ainsi que de l’accessibilité aux soins primaires et neurologiques spécialisés sur la mortalité en excès de patients atteints de SEP.
Les patients de 18 centres experts participant à l’OFSEP ont été recrutés entre 1960 et 2015. La défavorisation mesurée grâce à l’EDI (European Deprivation Index), le temps de trajet au centre expert et l’accessibilité aux soins primaires (mesurée par l’indice SCALE (Spatial accessibility multiscalar)) ont été intégrés afin d’estimer la mortalité en excès (mortalité uniquement liée à la SEP). L’utilisation de splines pénalisées a permis de modéliser des effets non-proportionnels et non-linéaires.
La population d’étude incluait 33 697 patients (88 % de forme rémittente et 12 % de forme progressive). Pour les formes rémittentes, la défavorisation socioéconomique et le temps de trajet au centre spécialisé étaient associés à une augmentation de la mortalité en excès, alors qu’un déficit d’accès aux soins primaire n’était associé à aucune surmortalité. Pour les formes progressives, aucune variable mesurant les inégalités socio-territoriales n’était associée à la mortalité en excès (Fig. 1 et Fig. 2).
La défavorisation socioéconomique est associée à un risque de mortalité liée à la SEP plus élevé pour les formes rémittentes et ce dès le début de la maladie. La diminution de la mortalité en excès avec l’augmentation du temps de trajet au centre expert suggère une sélection potentielle de patients suivis en centre expert, plus motivés et/ou en meilleure santé et de ce fait une perte de chance pour les patients les plus isolés géographiquement.
Nos résultats suggèrent que l’environnement socioterritorial doit être considéré comme un facteur potentiellement péjoratif pour la survie des patients et devrait être considéré dans la prise en charge.
Privatisation of utilities in emerging countries is impeded by informational problems. We analyse privatisation of utilities as
a process, focusing on the creation of information that arises both ...before and after the transfer of property. We take the example of the privatisation of electricity in Delhi (
Section 1). We examine the interest in creating as much information as possible before the transfer of property, and propose a model based on a trade-off between the potential benefits of creating information prior to selling of assets, vs. facing the costs of delays associated with the risks of a state's failure in creating this information prior to privatisation. We operationalise the model in the case of Delhi and argue that, in similar conditions, it is reasonable and profitable to invest a few years in information building (
Section 2). We test the robustness of this model with what risks to be the most stringent critique: the inefficiency of the state (
Section 3). We conclude that this simple model is fit for a clear and transparent decision-making on privatisation and reforms.
Lesaffre R., Ruet L., Lépinay Ph. Technique chirurgicale de la transplantation de tendon. In: Bulletin de l'Académie Vétérinaire de France tome 128 n°4-5, 1975. pp. 169-174.
Cytotoxicity is an important function of the immune system that results in the destruction of cellular targets by humoral and/or cellular mechanisms. We wanted to assess the possibility of targeting ...the lytic function of immune cells toward cancer cells, which express the gene coding for a known tumor antigen (Ag) (GA733-2/epithelial cell adhesion molecule), using a viral vector encoding a monoclonal antibody (mAb) specific for said tumor Ag (CO17-1A). To this end, we have constructed recombinant vaccinia viruses expressing the sequences corresponding to mAb CO17-1A, which recognizes a specific Ag (GA733-2) that is present on the surface of most gastrointestinal carcinomas. The recombinant vectors encoding either a secreted or membrane-anchored form of CO17-1A mAb were used to infect effector cells, which were subsequently assessed for their cytotoxic activity. The recombinant viruses were able to infect both granulocyte-macrophage colony-stimulating factor-activated human macrophages and Ag-stimulated murine cytotoxic T lymphocytes. Infected granulocyte-macrophage colony-stimulating factor-activated macrophages were found to be able to kill GA733-2-expressing tumor cells. Likewise, infected cytotoxic T lymphocytes, although conserving their original alloreactivity, gained the capability of killing GA733-2-expressing cancer cells.
Fifteen floor litter samples were collected from each of 60 broiler chicken houses in Nova Scotia. Salmonella was recovered from 270 litter samples (30%) in 33 of 60 (55%) houses. All isolates were ...serotyped. Salmonella heidelberg and S. infantis were the most common of the 13 serotypes found. Isolates of selected serotypes were phage typed. Most isolates were susceptible to all common antimicrobial agents.
Isolating ground-based interferometric gravitational wave observatories from environmental disturbances is one of the great challenges of the advanced detector era. In order to directly observe ...gravitational waves, the detector components and test masses must be highly inertially decoupled from the ground motion not only to sense the faint strain of space-time induced by gravitational waves, but also to maintain the resonance of the very sensitive 4 km interferometers. This article presents the seismic isolation instrumentation and strategy developed for Advanced LIGO interferometers. It reviews over a decade of research on active isolation in the context of gravitational wave detection, and presents the performance recently achieved with the Advanced LIGO observatory. Lastly, it discusses prospects for future developments in active seismic isolation and the anticipated benefits to astrophysical gravitational wave searches. Beyond gravitational wave research, the goal of this article is to provide detailed isolation strategy guidelines for sensitive ground-based physics experiments that may benefit from similar levels of inertial isolation.
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