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Ecologists working with a range of organisms and environments have carried out manipulative field experiments that enable us to ask questions about the interaction between competition and predation (including herbivory) and about the relative strength of competition and predation in the field. Evaluated together, such a collection of studies can offer(More)
Volatile organic compounds play a central role in the processes that generate both urban photochemical smog and tropospheric ozone. For successful and accurate prediction of these pollution episodes, identification of the dominant reactive species within the volatile organic carbon pool is needed. At present, lack of resolution inherent in single-column(More)
Ancient eclipse observations are proving of considerable value in modern geophysics. These seemingly crude observations enable variations in the length of the day--produced by tides and other mechanisms--to be investigated in some detail over more than two millennia. The main attraction of the early data is the long time scale which they cover. They reveal(More)
Objective: To evaluate the negative fetal fibronectin (fFN) assay in patients with twin gestations who are symptomatic for preterm labor (PTL).Study Design: Fetal fibronectin expression in 955 symptomatic patients combined from two prospective multicenter trials was studied. Of the 955 patients, 43 had twin gestations in PTL with intact amniotic membranes(More)
The imaging characteristics for X-ray wavelengths in the "water window" under incoherent imaging conditions (large detector aperture) are examined for the King's College London scanning transmission X-ray microscope with zone-plate objective installed at the Daresbury (UK) synchrotron. The principal consideration was to express image theory, incorporating(More)