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was monitored by an in-stream thermocouple which had been previously calibrated against a second thermocouple in the sample position. Automatic peak search and indexing procedures yielded the monoclinic reduced primitive cell The final cell parameters and specific collection parameters are given in Table 7 .The 4143 raw intensity data were converted to structure factor amplitudes and their esd's by correction for scan speed, background, and Lorentz and polarization effects. No correction for crystal decomposition was necessary. Inspection of the azimuthal scan data showed a variation Imln/Imar = 0.75 for the average curve. An empirical correction for absorption, based on the azimuthal scan data, was applied to the intensities since it was not possible to accurately measure the sample crystal. Removal of systematically absent and redundant data left 3775 unique data.The structure was solved by Patterson methods and refined via standard least-squares and Fourier techniques. In a difference Fourier map calculated following refinement of all non-hydrogen atoms with anisotropic thermal parameters, peaks corresponding to the expected positions of most of the hydrogen atoms were found. A difference Fourier map calculated after inclusion of all other hydrogen atoms clearly showed the position of the hydride ligand attached to the metal. All hydrogen atoms were then allowed to refine with isotropic thermal parameters. A secondary extinction parameter was refined in the final cycles of leastsquares. The final residuals for 267 variables refined against the 3100 data for which F2 > 3 1 P 1 were R = 2.04%, wR = 2.53%, and GOF = 1.356. The R value for all 3775 data was 3.49%.The quantity minimized by the least-squares program was w(lFollFC1)* where w is the weight of a given observation. The p factor, used to reduce the weight of intense reflections, was set to 0.025 in the last cycles of the refinement. The analytical forms of the scattering factor tables of the neutral atoms were used, and all non-hydrogen scattering factors were corrected for both the real and imaginary components of anomalous dispersion. Inspection of the residuals ordered in ranges of sin ( B ) / X , IFo[, and parity and value of the individual indices showed no unusual features or trends. The largest peak in the final difference Fourier map had an electron density of 2.14 e-/A3 and was located only 0.74 A from the iridium atom. All other peaks in the final difference Fourier map had densities of less than 1 e-/A3. The positional parameters of the atoms and the estimated standard deviations are given in Table 8. Structure factor amplitudes were provided as supplementary material in the preliminary comm~nication.~ Acknowledgment.Abstract: The transmetalation reaction of trimethylaluminum with the palladium chloride dimer Pd2C1,(p-dppm), (1) (dppm = bis(dipheny1phosphino)methane) at -78 O C gave an intermediate, Pd2C1Me(p-dppm), ( 2 ) , which disproportionated at -10 OC to yield the trans-face-to-face palladium dimer Pd2C12Me2(p-dppm), (3) and a palladium ...

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We discovered a highly virulent variant of subtype-B HIV-1 in the Netherlands. One hundred nine individuals with this variant had a 0.54 to 0.74 log 10 increase (i.e., a ~3.5-fold to 5.5-fold increase) in viral load compared with, and exhibited CD4 cell decline twice as fast as, 6604 individuals with other subtype-B strains. Without treatment, advanced HIV—CD4 cell counts below 350 cells per cubic millimeter, with long-term clinical consequences—is expected to be reached, on average, 9 months after diagnosis for individuals in their thirties with this variant. Age, sex, suspected mode of transmission, and place of birth for the aforementioned 109 individuals were typical for HIV-positive people in the Netherlands, which suggests that the increased virulence is attributable to the viral strain. Genetic sequence analysis suggests that this variant arose in the 1990s from de novo mutation, not recombination, with increased transmissibility and an unfamiliar molecular mechanism of virulence.

Persistent pain after caesarean section and its association with maternal anxiety and socioeconomic background.

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