Using a 2D Model of the Io Plasma Torus to Investigate the Effects of Density Variations on the Morphology and Intensity of the Io Footprint

Poster (2012, December 06)

Io is the primary source of plasma in the Jovian magnetosphere, continuously releasing approximately 1 ton/s of SO2 from volcanic eruptions. The interaction of Io with Jupiter’s magnetosphere is strongly ... [more ▼]

Io is the primary source of plasma in the Jovian magnetosphere, continuously releasing approximately 1 ton/s of SO2 from volcanic eruptions. The interaction of Io with Jupiter’s magnetosphere is strongly influenced by the density structure of the resulting plasma torus and the position of Io relative to the center of the torus [Bonfond et al. 2008]. This unusual interaction produces a complex auroral feature on Jupiter’s ionosphere known as the Io footprint. Hubble Space Telescope (HST) observations of Jupiter’s far-UV aurora during spring 2007 showed an increased number of isolated auroral blobs along with a continuous expansion of Jupiter’s main auroral oval over a few months. These blobs were associated with several large injections of hot plasma between 9 and 27 Jovian radii. These events coincided with a large volcanic eruption of the Tvashtar Paterae on Io, as observed by the New Horizons spacecraft [Spencer et al., 2007]. This, in turn, may have resulted in a significant increase in the plasma torus density. Besides, on June 7th, 2007, the Io footprint momentarily became so faint that it disappeared under a diffuse patch of emission remaining from an injection blob [Bonfond et al., 2012]. The goal of the present study is to examine the relationship between the increased density of the plasma torus and the dimming of the Io footprint. We implement a 2D model of the Io plasma torus that treats the variable-density torus as being composed of discrete layers of uniform density. As the co-rotating plasma in the plasma torus impinges on Io, Alfvén waves are launched at a pushback angle obtained from Gurnett and Goertz [1981]. The waves propagate inside the plasma torus through reflection and refraction at density discontinuities where they lose some of their initial energy. Using the above model, we can track the Alfvén wave fronts in the plasma torus and determine the longitude at which they exit the torus along with the corresponding remaining energy. Since Alfvén waves are capable of accelerating charged particles along magnetic field lines, we assume that the discrete Io footprint features are created at these longitudes, and that the intensity of each of these features is positively correlated to the energy transported by the wave front as it exits the plasma torus. Therefore, the model allows us to investigate both the effects of density changes and of Io’s position in the plasma torus on the intensity and the morphology of the Io footprint. In this context, the model enables us to determine the density increase in the plasma torus required to explain the apparent disappearance of Io footprint given its position at that time. [less ▲]

Characterization of Volatile Organic Compounds from Human Analogue Decomposition Using Thermal Desorption Coupled to Comprehensive Two-Dimensional Gas Chromatography-Time-of-Flight Mass Spectrometry

in Analytical Chemistry (2012), 85

Complex processes of decomposition produce a variety of chemicals as soft tissues, and their component parts are broken down. Among others, these decomposition byproducts include volatile organic ... [more ▼]

Complex processes of decomposition produce a variety of chemicals as soft tissues, and their component parts are broken down. Among others, these decomposition byproducts include volatile organic compounds (VOCs) responsible for the odor of decomposition. Human remains detection (HRD) canines utilize this odor signature to locate human remains during police investigations and recovery missions in the event of a mass disaster. Currently, it is unknown what compounds or combinations of compounds are recognized by the HRD canines. Furthermore, a comprehensive decomposition VOC profile remains elusive. This is likely due to difficulties associated with the nontarget analysis of complex samples. In this study, cadaveric VOCs were collected from the decomposition headspace of pig carcasses and were further analyzed using thermal desorption coupled to comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (TD-GC × GC−TOFMS). Along with an advanced data handling methodology, this approach allowed for enhanced characterization of these complex samples. The additional peak capacity of GC × GC, the spectral deconvolution algorithms applied to unskewed mass spectral data, and the use of a robust data mining strategy generated a characteristic profile of decomposition VOCs across the various stages of soft-tissue decomposition. The profile was comprised of numerous chemical families, particularly alcohols, carboxylic acids, aromatics, and sulfides. Characteristic compounds identified in this study, e.g., 1-butanol, 1-octen-3-ol, 2-and 3-methyl butanoic acid, hexanoic acid, octanal, indole, phenol, benzaldehyde, dimethyl disulfide, and trisulfide, are potential target compounds of decomposition odor. This approach will facilitate the comparison of complex odor profiles and produce a comprehensive VOC profile for decomposition. [less ▲]

Durabilité de lots de bois de peuplier modifié thermiquement

Conference (2012, December 05)

Coronary heart disease: the MONICA-BELLUX Register

Conference (2012, December 05)

Background : Cardiovascular diseases contribute to 42% of overall mortality in the European Union. Over a third of deaths from CVD are from coronary heart disease and just over a quarter are from ... [more ▼]

Background : Cardiovascular diseases contribute to 42% of overall mortality in the European Union. Over a third of deaths from CVD are from coronary heart disease and just over a quarter are from cerebrovascular disease (stroke). Standardized death rates for heart disease have fallen dramatically in the last 25 years in Western Europe, both for men and for women. Multinational MONItoring of trends and determinants in CArdiovascular disease The MONICA Project : A major source of information on cardiovascular diseases established in the early 1980s under the auspices of WHO, to monitor trends in cardiovascular diseases and to relate these to risk factor changes over a ten year period. There were a total of 37 MONICA Collaborating Centres in 21 countries (including 29 populations in 16 European countries). The ten year data collection was completed in the late 1990s, though several Centres are still active today. Conclusions : CVD registers remain nevertheless an invaluable source for monitoring levels and trends in incidence and case fatality. Trends in incidence rates and in case fatality rates can significantly differ from one another. This situation requires better detection of individuals at risk. The intervention component of the BELLUX register is well-suited for this task. [less ▲]

Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

in Atmospheric Measurement Techniques (2012), 5(2012), 3007-3027

Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ... [more ▼]

Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle. [less ▲]

Pédologie II : Notions de base (Fertilité des sols - Éléments nutritifs - Biologie et biodiversité des sols - Menaces qui pèsent sur les sols)

Conference given outside the academic context (2012)

"Qui a peur de la normalisation?" Les réseaux d'aide en matière d'assuétudes, entre judiciaire et thérapeutique - réflexions à partir de Michel Foucault et Bruno Latour

Conference given outside the academic context (2012)

Liquidity Shocks and Global Imbalances

Conference (2012, December 04)

ENMG et expertise

Conference (2012, December 04)

Future surface mass balance contribution of the Antarctic ice-sheet to sea level rise

Scientific conference (2012, December 04)

Most of the IPCC-AR4 global circulation models predict an increase of the Antarctic Surface Mass Balance (SMB) during the 21st century that would mitigate global sea level rise. High-resolution modeling ... [more ▼]

Most of the IPCC-AR4 global circulation models predict an increase of the Antarctic Surface Mass Balance (SMB) during the 21st century that would mitigate global sea level rise. High-resolution modeling is necessary to adequately capture the Antarctic SMB, that is why we present here a downscaling method leading to 15-km SMB resolution for century time-scales over Antarctica. Our first results show that a higher resolution induce at the same time more run-off but a significantly higher mitigation of sea level rise for the next centuries. [less ▲]