700 research outputs found
Investigation of long-lived eddies on Jupiter
Quasi-geostrophic, two layer models of the Jovian atmosphere are under development; these may be used to simulate eddy phemonena in the atmosphere and include tracer dynamics explicitly. The models permit the investigation of the dynamics of quasi-geostrophic eddies under more controlled conditions than are possible in the laboratory. They can also be used to predict the distribution and behavior of tracer species, and hence to discriminate between different models of the mechanisms forcing the eddies, provided suitable observations can be obtained. At the same time, observational strategies are being developed for the Near Infrared Mapping Spectrometer on the Galileo Orbiter, with the objective of obtaining composition measurements for comparison with the models. Maps of features at thermal infrared wavelengths near 5 micron and reflected sunlight maps as a function of wavelength and phase angle will be obtained. These should provide further useful information on the morphology, composition and microstructure of clouds within eddy features. Equilibrium chemistry models which incorporate advection may then be used to relate these results of the dynamical models and provide addtional means of classifying different types of eddies
The Acid Soluble Disulphide and Mixed Disulphide Levels of Some Normal Tissues and Transplanted Tumours
The acid soluble disulphides and mixed disulphides of a range of normal rat and mouse tissues and a number of transplanted rat or mouse tumours were measured. The result were considered in relation to other workers' data. It is noted that more radioresponsive tissues have higher levels than the more radioresistant tissues
Linear dust polarization during the embedded phase of protostar formation
Measuring polarization from thermal dust emission can provide constraints on
the magnetic field structure around embedded protostars. However, interpreting
the observations is challenging without models that consistently account for
both the complexity of the protostellar birth environment and polarization
mechanisms. We aim to provide a better understanding with a focus on
bridge-like structures such as that observed towards the protostellar multiple
IRAS 16293--2422 by comparing synthetic polarization maps of thermal reemission
with observations. We analyze the magnetic field properties associated with the
formation of a protostellar multiple based on ideal MHD 3D zoom-in simulations
carried out with the RAMSES code. To compare with observations, we post-process
a snapshot of a bridge-like structure that is associated with a forming triple
star system with the radiative transfer code POLARIS and produce
multi-wavelength dust polarization maps. In the most prominent bridge of our
sample, the typical density is about 10^(-16) g cm^(-3), and the magnetic field
strength is about 1 to 2 mG. The magnetic field structure has an elongated
toroidal morphology and the dust polarization maps trace the complex
morphology. In contrast, the magnetic field strength associated with the
launching of asymmetric bipolar outflows is significantly more magnetized (~100
mG). At {\lambda}=1.3 mm, the orientation of grains in the bridge is similar
for the case accounting for radiative alignment torques (RATs) compared to
perfect alignment with magnetic field lines. However, the polarization fraction
in the bridge is three times smaller for the RAT scenario compared to assuming
perfect alignment. At shorter wavelengths ({\lambda} < 200 {\mu}m), dust
polarization does not trace the magnetic field because other effects such as
self-scattering and dichroic extinction dominate the orientation of the
polarization.Comment: 18 pages, 12 figures plus 3 figures in the appendix, accepted for
publication in A&
Recommended from our members
Probing Mars’ atmosphere with ExoMars Mars Climate Sounder
The 2016 Mars Trace Gas Mission will carry with it the ExoMars Mars Climate Sounder instrument, a development of the very successful Mars Climate Sounder instrument already in orbit about Mars on NASA's Mars Reconnaissance Orbiter spacecraft. EMCS will continue the monitoring of Mars global temperature/pressure/aerosol field, and will also be able to measure the vertical profile of water vapour across the planet from 0 – 50 km. Key components of EMCS will be provided by Oxford, Reading and Cardiff Universities and the observations will be partly reduced by the instrument team at Oxford. The physical properties retrieved from these observations will be assimilated into Global Circulation Models at Oxford and at The Open University to provide a much clearer picture of the dynamics and transport processes in Mars' atmosphere
- …