Tracking Magnetic

All y-ray spectra were collected on 7-track magnetic tape, and the spectra analyzed by FOURIER, a computer program for computing nuclide activities, elemental concentrations and statistical parameters of the analytical results. Corrections for the Se interference in the ° Hg 280 KeV y-ray were made as described by Filby, et The Cu... 

Calamante, F., D.G. Gadian, A. Connelly, Quantification of perfusion using bolus tracking magnetic resonance imaging in stroke assumptions, limitations, and potential implications for clinical use. Stroke, 2002. 33(4) p. 1146-51. 

Figure Bl.19.22. Magnetic force microscopy image of an 8 pm wide track on a magnetic disk. The bit transitions are spaced every 2 pm along the track. Arrows point to the edges of the DC-erased region. (Taken from [109], figure 7.)...

Cheeseman, J. R., Tracks, G. W., Keith, T. A., Frisch, M. J., 1996, A Comparison of Models for Calculating Nuclear Magnetic Resonance Shielding Tensors , J. Chem. Phys., 104, 5497. 

We see that the models which best reproduce the location of all the six data points are the tracks which do not fit the solar location. The models whose convection is calibrated on the 2D simulation make a poor job, as the FST models and other models with efficient convection do therefore this result can not be inputed to the fact that we employ local convection models. A possibility is that we are in front of an opacity problem, more that in front of a convection problem. Actually we would be inclined to say that opacities are not a problem (we have shown this in Montalban et al. (2004), by comparing models computed with Heiter et al (2002) or with AH97 model atmospheres), but something can still be badly wrong, as implied by the recent redetermination of solar metallicity (Asplund et al., 2004). A further possibility is that the inefficient convection in PMS requires the introduction of a second parameter -linked to the stellar rotation and magnetic field, as we have suggested in the past (Ventura et al., 1998 D Antona et al., 2000), but this remains to be worked out. 

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