[1] A potential function using spherical harmonics up to degree and order 90 was derived from a selection of Mars Global Surveyor vector data. These included all three components of those taken below 200 km altitude during the two aerobraking phases (AB1 and AB2), the Science Phase Orbits (SPO), and the higher-altitude (367-435 km) data taken on the nightside during the Mapping Phase Orbits (MPO). The merger of these sets of data provided total global coverage. The technique used was a least squares minimization developed for Earth field analysis whereby the relative weighting of each data source was determined by the width of a Gaussian fit to the residual distribution about the potential function. Also, data selection by area and area weight functions were used to improve normalization. The residual misfit distributions for the vertical component for different data sources are (nT) AB1, 6.5; AB2 (in shadow), 6.7; AB2 (sunlit), 10.3; SPO, 6.4; and MPO, 5.9. The horizontal component misfits are about the same for MPO and AB2 in shadow, but for data taken in sunlight the scatter of horizontal component residuals increases by 50% for AB1, a factor of two for SPO, and 30% for AB2. The energy density spectrum evaluated at 3535 km radius (the mean altitude of the AB and SPO data) decreased from a high of 0.2 J/km 3 near n = 20 to an order of magnitude less at n = 90. Most of the power in the spectrum lies between n = 15 and n = 40. The dipole moment was only 8 Â 10 16 A Á m 2 , which is likely close to the noise of the coefficients. This spectrum is 40 times greater than that of Earth at the scale sizes represented by values of n from 20 to 40. Comparisons with other published maps and models for Mars show general agreement with the field representations at MPO altitudes, but disagreements up to several hundred nT in components calculated for areodetic altitudes below 200 km.
[1] More than four years of data taken from Mars Global Surveyor during its Mapping Phase Orbits (360-420 km altitude) over low field regions were examined. The nightside magnetic field data were binned according to a proxy solar wind pressure calculated from the dayside measurements. When the crustal field contribution calculated from the internal field model (FSU90) is removed, the distribution of residuals is bi-valued in the sunward component. Pass-by-pass inspections of the data sometimes show a sudden reversal of field, which occur on successive passes. Analysis indicates that for these orbits MGS traverses a current sheet that separates the two lobes of Mars' magnetotail. These results indicate that on the nightside the major contributor to the external field is the draping of the Interplanetary Magnetic Field about the planet and that care must be taken when utilizing such data for modeling Mars' internal field. Citation:
\s=b\A total of 34 samples of human milk from 15 donors was analyzed for nicotine content, using a new method of sample preparation and subsequent quantification by gas chromatography. Nicotine was not found in the six samples of milk from non-smokers. The 28 samples from smokers contained an average of 91 parts per billion (ppb) nicotine (ranging from < 20 ppb to 512 ppb).While no adverse effects to the infant due to nicotine in human milk have been documented, this method of analysis will allow systematic monitoring of nicotine concentrations in the milk of lactating women. These results should not be used to deter breast-feeding; rather, they offer another reason for mothers to reduce or cease smoking.(Am J Dis Child 130: [837][838][839] 1976) It has been estimated that 20% to 25% of women smoke during preg¬ nancy.1""031 Several investigations have demonstrated that such women deliver smaller infants than nonsmokers,1(pp103·122' and that neonatal mortality is notably higher among
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