16 research outputs found
Evidence of currents and unstable particle distributions in an extended region around the lunar plasma wake
We report observations of electrostatic ion acoustic waves and Langmuir waves during a recent lunar encounter by the Wind spacecraft. These waves are observed when Wind is magnetically connected to the nominal wake and at distances greater than 8 lunar radii from the wake. When interpreted in the context of a simple timeâofâflight model, these observations imply the existence of a system of currents and disturbed particle distributions that extends far into solar wind
OSS (Outer Solar System): A fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt
The present OSS mission continues a long and bright tradition by associating
the communities of fundamental physics and planetary sciences in a single
mission with ambitious goals in both domains. OSS is an M-class mission to
explore the Neptune system almost half a century after flyby of the Voyager 2
spacecraft. Several discoveries were made by Voyager 2, including the Great
Dark Spot (which has now disappeared) and Triton's geysers. Voyager 2 revealed
the dynamics of Neptune's atmosphere and found four rings and evidence of ring
arcs above Neptune. Benefiting from a greatly improved instrumentation, it will
result in a striking advance in the study of the farthest planet of the Solar
System. Furthermore, OSS will provide a unique opportunity to visit a selected
Kuiper Belt object subsequent to the passage of the Neptunian system. It will
consolidate the hypothesis of the origin of Triton as a KBO captured by
Neptune, and improve our knowledge on the formation of the Solar system. The
probe will embark instruments allowing precise tracking of the probe during
cruise. It allows to perform the best controlled experiment for testing, in
deep space, the General Relativity, on which is based all the models of Solar
system formation. OSS is proposed as an international cooperation between ESA
and NASA, giving the capability for ESA to launch an M-class mission towards
the farthest planet of the Solar system, and to a Kuiper Belt object. The
proposed mission profile would allow to deliver a 500 kg class spacecraft. The
design of the probe is mainly constrained by the deep space gravity test in
order to minimise the perturbation of the accelerometer measurement.Comment: 43 pages, 10 figures, Accepted to Experimental Astronomy, Special
Issue Cosmic Vision. Revision according to reviewers comment
Quasi-periodic acceleration of electrons by a plasmoid-driven shock in the solar atmosphere
Cosmic rays and solar energetic particles may be accelerated to relativistic
energies by shock waves in astrophysical plasmas. On the Sun,
shocks and particle acceleration are often associated with the eruption
of magnetized plasmoids, called coronal mass ejections (CMEs).
However, the physical relationship between CMEs and shock particle
acceleration is not well understood. Here, we use extreme ultraviolet,
radio and white-light imaging of a solar eruptive event on 22 September
2011 to show that a CME-induced shock (Alfvén Mach number 2:4+0:7
-0:8) was coincident with a coronal wave and an intense metric radio burst
generated by intermittent acceleration of electrons to kinetic energies
of 2{46 keV (0.1{0.4 c). Our observations show that plasmoid-driven
quasi-perpendicular shocks are capable of producing quasi-periodic acceleration
of electrons, an effect consistent with a turbulent or rippled
plasma shock surface
Mutation Analysis of Five Candidate Genes in Familial Breast Cancer
Most of the known breast cancer susceptibility genes (BRCA1, BRCA2, CHEK2 and ATM) are involved in the damage response pathway. Other members of this pathway are therefore good candidates for additional breast cancer susceptibility genes. ATR, along with ATM, plays a central role in DNA damage recognition and Chk1 relays checkpoint signals from both ATR and ATM. PPP2R1B and PPP2R5B code for subunits of protein phosphatase 2A (PP2A), which regulates autophosphorylation of ATM. In addition, EIF2S6/Int-6, which was originally identified as a common integration site for the mouse mammary tumour virus in virally induced mouse mammary tumours, is a candidate breast cancer susceptibility gene because of its putative role in maintaining chromosome stability. To investigate the role of ATR, CHK1, PPP2R1B, PPP2R5B and EIF2S6/Int-6, we carried out mutation analysis of these genes in the index cases from non-BRCA1/BRCA2 breast cancer families. We also screened sporadic breast tumours for somatic mutations in PPP2R1B and PPP2R5B. Although we identified many novel variants, we found no evidence that highly penetrant germline mutations in these five genes contribute to familial breast cancer susceptibility