254,756 research outputs found
In-flight Diagnostics in LISA Pathfinder
No full textLISA PathFinder (LPF) will be flown with the objective to test in space key technologies
for LISA. However its sensitivity goals are, for good reason, one order of magnitude less than those which LISA will have to meet, both in drag-free and optical metrology requirements, and in the observation frequency band. While the expected success of LPF will of course be of itself a major step forward to LISA, one might not forget that a further improvement by an order of
magnitude in performance will still be needed. Clues for the last leap are to be derived from proper disentanglement of the various sources of noise which contribute to the total noise, as measured in flight during the PathFinder mission. This paper describes the principles, workings and requirements of one of the key tools to serve the above objective: the diagnostics subsystem. This consists in sets of temperature, magnetic field, and particle counter sensors, together with generators of controlled thermal and magnetic perturbations. At least during the commissioning phase, the latter will be
used to identify feed-through coefficients between diagnostics sensor readings and associated actual noise contributions. A brief progress report of the current state of development of the diagnostics subsystem will be given as well.Peer Reviewe
LISA Pathfinder: First steps to observing gravitational waves from space
No full textLISA Pathfinder, the European Space Agency's technology demonstrator mission for future spaceborne gravitational wave observatories, was launched on 3 December 2015, from the European space port of Kourou, French Guiana. After a short duration transfer to the final science orbit, the mission has been gathering science data since. This data has allowed the science community to validate the critical technologies and measurement principle for low frequency gravitational wave detection and thereby confirming the readiness to start the next generation gravitational wave observatories, such as LISA.This paper will briefly describe the mission, followed by a description of the science operations highlighting the performance achieved.Details of the various experiments performed during the nominal science operations phase can be found in accompanying papers in this volume
Review of "Anne Clifford���s autobiographical writing, 1590���1676" by Jessica Malay, ed.
No full textJessica Malay, ed. Anne Clifford���s autobiographical writing, 1590���1676: Manchester University Press, 2018. x + 323 pp. + 11 illus. $30.00. Review by Lisa J. Schnell, University of Vermon
Methylphosphonium methylcarbonate, ylide precursor for halyde- and base-free Wittig reactions
No full textThe phosphonium salt triphenylmethylphosphonium methylcarbonate [PΦ,Φ,Φ,1][OCOOCH3] was obtained by methylation of triphenylphosphine (Ph3P) with dimethylcarbonate, adopting a green and sustainable procedure1.
The [PΦ,Φ,Φ,1][OCOOCH3] phosphonium salt was observed to possess significant P-CH3 proton acidity, and deuterium exchange experiments showed the formation of the analogous PhP3-CD3 phosphonium salt. Spontaneous deprotonation of the methyl group lead therefore to formation of the corresponding phosphorus ylide, Ph3P=CH2.
This Ph3P=CH2 ylide was tested for the Wittig reaction with benzaldehyde PhCHO, generating the desired PhC=CH2 olefination product. It was noteworthy that this Wittig reaction protocol did not require an alkyl halide or a strong base for the formation of the ylide, and could be conducted in air, making it a greener procedure.
The scope of the olefination reaction was extended to a number of carbonyl substrates, both aldehydes and ketones, with high conversions and selectivity. It was performed under mild conditions (34 – 80 °C), using a ratio ylide:carbonyl between 1.0 -3.0, in 2-methyl tetrahydrofuran (2-Me-THF) as solvent.
The study was also extended to other alkylphosphonium methylcarbonate ionic liquids ([P8,8,8,1][OCOOCH3] and [P4,4,4,1][OCOOCH3]). It was demonstrated that, depending on the reaction conditions, it was possible to achieve not only the transfer of a =CH2 fragment, but also the selective transfer of the bulkier alkyl group e.g. =CH(CH2)nCH3, giving access to a variety of olefins. Cis-trans selectivity was in the range 20-80
Heliospheric influences on LISA
No full textLaser interferometer space antenna (LISA) is the first interferometer devoted to the detection of low frequency gravitational waves in space. Control of the environment and the study of the effects of energetic particles traversing the LISA apparatus are mandatory for this experiment to be fully successful. Telescopes for solar and cosmic-ray particle monitoring will be placed on board LISA and its precursor mission LISA Pathfinder (LISA-PF). In particular, proton, helium and electron detection is recommended on LISA. In this paper, we report expected incident galactic proton and helium fluxes at the time of LISA and LISA-PF missions. The number of solar events with the fluence ranging between 10^(6) and 10^(11) protons cm^(-2) above 30 MeV occurring during the LISA missions is estimated as well. Finally, we discuss the importance of electron detection on LISA to forecast upcoming solar energetic protons
Adolescent body dissatisfaction and the media
No full textIn this paper, an examination of the correlation between the use of sexual images in advertising and feelings of discontent with body image in adolescent girls will take place. It is this author’s opinion that the over-use of sexual images in advertising negatively effects how young girls perceive their bodies. This author’s research question examined whether the increased use of sex as an advertising tool is associated with the way that an adolescent girl perceives her own body. A literature search was also completed in which it was found that there is significant evidence to support this author’s claim. A broad internet search was done to obtain the most common keywords, and then a more in-depth search was done to find appropriate articles.M.A.L.S.Includes bibliographical referencesby Lisa M. Forber
Ground based 2 DoF test for LISA and LISA pathfinder: A status report.
No full textOn-ground tests are required to study the couplings between LISA test masses and the spacecraft that host them. In order to study couplings that might act between two ore more degrees of freedom in measuring the position and acting on the position of each test mass, a many degrees of freedom facility is needed. Here we present the status of our new 2 DoF double torsion pendulum, that will be used to test LISA Gravitational Reference Sensor (GRS) on the ground
Heliospheric influences on LISA
No full textLaser interferometer space antenna (LISA) is the first interferometer devoted to the detection of low frequency gravitational waves in space. Control of the environment and the study of the effects of energetic particles traversing the LISA apparatus are mandatory for this experiment to be fully successful. Telescopes for solar and cosmic-ray particle monitoring will be placed on board LISA and its precursor mission LISA Pathfinder (LISA-PF). In particular, proton, helium and electron detection is recommended on LISA. In this paper, we report expected incident galactic proton and helium fluxes at the time of LISA and LISA-PF missions. The number of solar events with the fluence ranging between 10(6) and 10(11) protons cm(-2) above 30 MeV occurring during the LISA missions is estimated as well. Finally, we discuss the importance of electron detection on LISA to forecast upcoming solar energetic protons
Interplanetarymedium monitoring with LISA: Lessons from LISA Pathfinder
No full textThe Laser Interferometer Space Antenna (LISA) of the European Space Agency (ESA) will be the first low-frequency gravitational-wave observatory orbiting the Sun at 1 AU. The LISA Pathfinder (LPF) mission, aiming at testing the instruments to be located on board the LISA spacecraft (S/C), hosted, among the others, fluxgate magnetometers and a particle detector as parts of a diagnostics subsystem. These instruments allowed us to estimate the magnetic and Coulomb spurious forces acting on the test masses that constitute the mirrors of the interferometer. With these instruments, we also had the possibility to study the galactic cosmic-ray short term-term variations as a function of the particle energy and the associated interplanetary disturbances. Platform magnetometers and particle detectors will also be placed on board each LISA S/C. This work reports on an empirical method that allowed us to disentangle the interplanetary and onboard-generated components of the magnetic field by using the LPF magnetometer measurements. Moreover, we estimate the number and fluence of solar energetic particle events expected to be observed with the ESA Next Generation Radiation Monitor during the mission lifetime. An additional cosmic-ray detector, similar to that designed for LPF, in combination with magnetometers, would permit to observe the evolution of recurrent and non-recurrent galactic cosmic-ray variations and associated increases of the Interplanetary Magnetic Field at the transit of high-speed solar wind streams and interplanetary counterparts of coronal mass ejections. The diagnostics subsystem of LISA makes this mission also a natural multi-point observatory for space weather science investigations
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