Hoekzema N.M.,MPS |
Garcia-Comas M.,MPS |
Garcia-Comas M.,Institute Astrofisica Of Andalucia Csic |
Stenzel O.J.,MPS |
And 4 more authors.
Earth and Planetary Science Letters | Year: 2010
We measured the optical depth of the Martian atmosphere as a function of altitude above two opposing scree walls of the Valles Marineris, from stereo images that were taken with the High Resolution Stereo Camera (HRSC) of Mars Express on June 3, 2004, during orbit 471. The optical depths were measured from contrast differences between the stereo images with the so called "stereo method". For 7 regions in the northern wall of the Valles, we estimated the optical depth and found values between 1.0 and 1.6. These regions span more than 6km in altitude and the results show a clear relation with altitude. A fit on these results yielded a scale-height for the optical depth of 14.0. km. +. 1.3/?1.1. km. The expected local pressure-scale height is smaller: 11.5-12.0. km. The difference is most likely explained by small (around 1.5%) offset errors in the intensity calibration of HRSC images. We also selected 9 regions in the opposing southern wall and from these we measured values of optical depth in the range 1.3-1.5. Our result suggests the presence of clouds above this part of the Valles because the optical depth appears almost independent of the surface altitude. Possibly these are banner clouds, forming at the edge of the canyon, that contain dust that is blown over the canyon by winds from the high plains to the South. © 2010 Elsevier B.V.
Paranicas C.,APL |
Roussos E.,MPS |
Krupp N.,MPS |
Kollmann P.,MPS |
And 8 more authors.
Planetary and Space Science | Year: 2012
We characterize the relative importance of energetic electrons and protons to the weathering of five of the inner satellites of Saturn. To do this, we present data from the Magnetospheric Imaging Instrument on the Cassini spacecraft, some of which is averaged over the whole mission to date. We also compute averaged proton and electron energy spectra relevant to the distances of these inner satellites. Where data are available, we estimate the power per unit area into a satellites surface. For electron energy deposition into satellite leading hemispheres, we find the power per unit area is greatest at Mimas and falls off with distance from Saturn. Using fluxes of 150 MeV protons detected within the sweeping corridors of Mimas and Enceladus, we find the corresponding deposition would be about 2×10 8 and 3.7×10 7 eV/cm 2 s. © 2011 Elsevier Ltd. All rights reserved.
Ulamec S.,German Aerospace Center |
Biele J.,German Aerospace Center |
Fantinati C.,German Aerospace Center |
Fronton J.-F.,French National Center for Space Studies |
And 8 more authors.
Acta Astronautica | Year: 2012
Rosetta is a Cornerstone Mission of the ESA Horizon 2000 programme. It is going to rendezvous with comet 67P/Churyumov-Gerasimenko after a 10 year cruise and will study both its nucleus and coma with an orbiting spacecraft and a landed platform. The latter, named Philae, has been designed to land softly on the comet nucleus and is equipped with 10 scientific instruments to perform in-situ studies of the cometary material. Philae has been provided by a large international consortium. Rosetta was successfully launched on March 2, 2004 from Kourou in French Guyana. Philae is operated by the Lander Control Centre (LCC) at DLR, Cologne and the Science Operations and Navigation Centre (SONC) at CNES, Toulouse via the European Spacecraft Operations Centre (ESOC) in Darmstadt. The scientific lead is at the Max Planck Institute for Solar System Science (Katlenburg-Lindau, Germany) and the Institut d'Astrophysique Spatiale (Paris). Since launch, the Lander has been operational during commissioning, several checkouts, two planetary swing-bys at the Earth and one at Mars, fly-bys at asteroids Steins and Lutetia as well as some additional activities for calibration and failure investigation. Payload checkout PC13 was the last Lander activation prior to a deep space hibernation phase of Rosetta, which started in June 2011 and will last until approaching the comet in 2014. The paper describes the various Lander activities over the past seven years and gives an outlook of near- and on-comet operations. Landing is foreseen in November 2014 at a heliocentric distance of 3 AU. Prior to that, detailed characterization of the comet nucleus has to be performed with the Rosetta Orbiter instruments. © 2012 Elsevier Ltd. All rights reserved.
Sirey J.A.,New York Medical College |
Halkett A.,New York Medical College |
Chambers S.,New York Medical College |
Salamone A.,Mps |
And 3 more authors.
Journal of Elder Abuse and Neglect | Year: 2015
The goal of this pilot program was to test the usefulness of adapted Problem-Solving Therapy (PST) and anxiety management, called PROTECT, integrated into elder abuse services to reduce depression and improve self-efficacy. Depressed women victims were randomized to receive elder abuse resolution services combined with either PROTECT or a mental health referral. At follow-up, the PROTECT group showed greater reduction in depressive symptoms and endorsed greater improved self-efficacy in problem-solving when compared to those in the Referral condition. These preliminary findings support the potential usefulness of PROTECT to alleviate depressive symptoms and enhance personal resources among abused older women. © 2015, Routledge. All rights reserved.
Modolo R.,French National Center for Scientific Research |
Chanteur G.M.,Ecole Polytechnique - Palaiseau |
Geophysical Research Letters | Year: 2012
Simulation studies of the Martian environment are usually restricted to stationary situations under various steady conditions of the solar wind and solar radiation. Dynamic transients and their implications have so far attracted little attention although global simulation models can provide valuable insights to understand disagreements between simulations and in situ observations. We make use of a three dimensional multispecies hybrid simulation model to investigate the response of the Martian plasma environment to a sudden rotation of the IMF. The simulation model couples charged and neutral species via three ionisation mechanisms: the absorption of solar extreme ultraviolet radiation, the impact of solar wind electrons, and the charge exchange between ions and neutral atoms. When a rotational discontinuity conveyed by the solar wind reaches the Martian environment the bow shock adapts quickly to the new solar wind conditions in contrast to the induced magnetosphere, especially the magnetic lobes in the wake. Timescales necessary to recover a stationary state can be estimated from such simulations and have some implications for space observations especially in the use of magnetic field proxies and for organizing particle measurements made by a spacecraft like Mars Express without an onboard magnetometer. Copyright 2012 by the American Geophysical Union.
Villanueva G.L.,NASA |
Altieri F.,National institute for astrophysics |
Clancy R.T.,SSI |
Encrenaz T.,University of Paris Descartes |
And 11 more authors.
Publications of the Astronomical Society of the Pacific | Year: 2016
In this paper, we summarize the main capabilities of the James Webb Space Telescope (JWST) for performing observations of Mars. The distinctive vantage point of JWST at the Sun–Earth Lagrange point (L2) will allow sampling the full observable disk, permitting the study of short-term phenomena, diurnal processes (across the east–west axis), and latitudinal processes between the hemispheres (including seasonal effects) with excellent spatial resolutions (0." 07 at 2 μm). Spectroscopic observations will be achievable in the 0.7–5 μm spectral region with NIRSpec at a maximum resolving power of 2700 and with 8000 in the 1–1.25 μm range. Imaging will be attainable with the Near-Infrared Camera at 4.3 μm and with two narrow filters near 2 μm, while the nightside will be accessible with several filters in 0.5 to 2 μm. Such a powerful suite of instruments will be a major asset for the exploration and characterization of Mars. Some science cases include the mapping of the water D/H ratio, investigations of the Martian mesosphere via the characterization of the non-local thermodynamic equilibrium CO2 emission at 4.3 μm, studies of chemical transport via observations of the O2 nightglow at 1.27 μm, high-cadence mapping of the variability dust and water-ice clouds, and sensitive searches for trace species and hydrated features on the Martian surface. In-flight characterization of the instruments may allow for additional science opportunities. © 2016. The Astronomical Society of the Pacific. All rights reserved.
Sterken V.J.,University of Stuttgart |
Sterken V.J.,Max Planck Institute for Nuclear Physics |
Sterken V.J.,TU Braunschweig |
Altobelli N.,ESA |
And 8 more authors.
Astronomy and Astrophysics | Year: 2013
Context. Theoretical predictions demonstrate that small (<0.1 μm) interstellar grains are mostly excluded from reaching the planetary system by electromagnetic interactions in the heliopause region and in the inner heliosphere. Bigger interstellar grains have been recorded in the planetary system by dust measurements on board Ulysses and other spacecraft. It was found that the interstellar dust flux is modulated by the interplanetary magnetic field. Aims. The objective of this study is to analyze the heliospheric filtering of the interstellar dust flow through the solar system and throughout the solar cycle. In the heliosphere the dynamics of interstellar dust is governed by the gravitational pull of the Sun, by the repulsion of solar radiation, and by the deflection caused by the interaction of the charged interstellar dust (ISD) grains with the interplanetary magnetic field. These interactions are described by the parameters of the radiation pressure constant β and the charge-to-mass ratio Q/m, which depend on the particle's size, physical properties, and composition. A previous paper studied the flow characteristics of ISD moving through the solar system were studied. In this follow-up paper, we focus on how the ISD size distribution varies during its passage through the solar system. Methods. In a parametric study of 70 different β and Q/m values, we calculated interstellar dust trajectories starting at the boundary of the heliosphere with starting times spread over a complete solar cycle of 22 years. Results. As a result we obtained the interstellar dust flux and dust speed for these times and positions and demonstrate the effects of the filtering on the dust size distributions. The size distribution of ISD observed at any time and at any position in the planetary system is strongly modified from when it entered the heliosphere. Peaks in relative flux of 10 times the original flux possibly depend on the grain size and place and time in the solar system. We did a detailed study of three cases of the flux and size distribution of interstellar grains reaching the planets Saturn, Jupiter, and the main-belt asteroid Ceres. These cases are used to get a first idea of what a dust detector or collector on a mission to these bodies might see of ISD. © 2013 ESO.
Richer E.,Ecole Polytechnique - Palaiseau |
Chanteur G.M.,Ecole Polytechnique - Palaiseau |
Modolo R.,LATMOS |
Geophysical Research Letters | Year: 2012
The reflection of solar wind protons on the Martian bow shock (BS) is investigated by means of three-dimensional simulation models. A two steps approach is adopted to allow a detailed analysis of the reflected population. Firstly, the 3-dimensional hybrid model of Modolo et al. (2005) is used to compute a stationary state of the interaction of the solar wind (SW) with Mars. Secondly, the motion of test particles is followed in the electromagnetic field computed by the hybrid simulation meanwhile detection criteria defined to identify reflected protons are applied. This study demonstrates some effects of the large curvature of a planetary BS on the structure of the foreshock. Reflected protons encounter the BS in a region encompassing parts of the quasi-perpendicular and quasi-parallel shocks, and exit the shock mainly from the quasi-parallel region. The energy spectrum of all reflected protons extends from 0 to almost 15keV. A virtual omnidirectional detector (VOD) is used to compute the local omnidirectional flux of reflected protons at various locations upstream of the BS. Spatial variations of this omnidirectional flux indicate the location and spatial extent of the proton foreshock and demonstrate its shift, increasing with the distance downstream, in the direction opposite to the motional electric field of the SW. Local energy spectra computed from the VOD observations demonstrate the existence of an energy gradient along the direction of the convection electric field. © 2012. American Geophysical Union. All Rights Reserved.
PubMed | MPS and University of North Carolina at Chapel Hill
Type: Journal Article | Journal: Biological psychiatry | Year: 2014
To make appropriate decisions, organisms must evaluate the risks and benefits of action selection. The nucleus accumbens (NAc) has been shown to be critical for this processing and is necessary for appropriate risk-based decision-making behavior. However, it is not clear how NAc neurons encode this information to promote appropriate behavioral responding.Here, rats (n = 17) were trained to perform a risky decision-making task in which discrete visual cues predicted the availability to respond for a smaller certain (safer) or larger uncertain (riskier) reward. Electrophysiological recordings were made in the NAc core and shell to evaluate neural activity during task performance.At test, animals exhibited individual differences in risk-taking behavior; some displayed a preference for the risky option, some the safe option, and some did not have a preference. Electrophysiological analysis indicated that NAc neurons differentially encoded information related to risk versus safe outcomes. Further, during free choice trials, neural activity during reward-predictive cues reflected individual behavioral preferences. In addition, neural encoding of reward outcomes was correlated with risk-taking behavior, with safe-preferring and risk-preferring rats showing differential activity in the NAc core and shell during reward omissions.Consistent with previously demonstrated alterations in prospective reward value with effort and delay, NAc neurons encode information during reward-predictive cues and outcomes in a risk task that tracked the rats preferred responses. This processing appears to contribute to subjective encoding of anticipated outcomes and thus may function to bias future risk-based decisions.
Moal E.,MPF |
44th International Conference on Large High Voltage Electric Systems 2012 | Year: 2012
Composite housings are becoming the preferred solutions for most of the EHV and UHV applications due to their many advantages especially in severe environment. Specific reference is made in the paper to composite housings with extruded sheds: a technology which guarantees the maximum flexibility and adaptability to the different applications. Results of experimental investigations are reported to confirm the good performance of the solution in laboratory with special attention to severe environment. The laboratory god experience is confirmed by the experience in test stations and by the return of service experience. Field feed-back indicates that composite insulators, correctly dimensioned according to laboratory test results and taking correctly into account the site pollution, present a satisfactory short and long term performance. Then the design optimization aspect is analyzed both in AC and DC with particular reference to pollution. It is shown that pollution determines the design especially in DC, thus needing a specific detailed accurate design approach. From the analysis the benefits of the composites over the ceramic solution clearly appear, especially for applications in the UHVDC range.