Recent studies have demonstrated the high frequency exponential relaxation of a viscoelastic modulus of lipid membranes. It is shown that the temperature dependence of the relaxation time can be ...extracted from published data on the relevant modulus for solvent-free bilayer lipid membranes of glycerol monoöleate. The relaxation is fastest close to the membrane transition temperature, where the time scale is approximately 20 mus. Possible causes of the transitional minimum of this time scale are discussed.
Measles occurred in 3,220 Air Force recruits between January 1976 and July 1979 and was complicated by pneumonia in 106 cases (3.3 percent). Although no deaths occurred, the illness was characterized ...as clinically severe with high fever and prolonged hospitalization (mean, 14.5 days). Bacterial superinfection as documented by transtracheal aspiration occurred in 35 cases (30.3 percent) and was caused by Hemophilus influenzae (18), Hemophilus parainfluenzae (two), Neisseria meningitidis (nine), Streptococcus pneumoniae (three), Streptococcus pyogenes (two) and Moraxella kingae (one). Clinical evidence of bronchospasm was present in 18 patients (17 percent) and required bronchodilators in six. Other complications included liver function abnormalities (31 percent), otitis media (29 percent) and sinusitis (25 percent). Measles pneumonia in adolescents is clinically severe with a generally benign outcome.
Thermotropic phase transitions in single planar bilayers of glycerol mono-oleate have been investigated using quasi-elastic light scattering from thermally excited membrane fluctuations. In certain ...cases both spectroscopic and intensity information were derived from the observations. For solvent-free bilayers transitional changes were observed in several membrane parameters: in tension, viscosity and thickness, in a combination of lipid orientational order parameter and dielectric anisotropy, and in the lateral compression modulus. These changes, particularly those in membrane thickness and in the anisotropy/order combination, were clearly indicative of a chain-melting transition in the lipid molecules. The chain-melting transition temperature was identified as 16.6 +/- 0.03 degrees C (delta T 1/2 = 1.5 degrees C). The other changes tended to cluster around 12.5 and 16.6 degrees C, suggesting that a two-stage transition was involved. Analysis of pretransitional fluctuations in membrane viscosity, based on a Landau approach, suggested that at the transition the membrane was close to a critical point (T = 12.7 degrees C). Less information was accessible for membranes containing n-decane within their structure. In this case, the change in membrane tension was much smaller than in the solvent-free case and the transition was considerably broadened. These effects accord with an increase in 'interactive volume' within the bilayer due to solvent inclusion.
The safety of attenuated viral vaccines against measles and rubella and their efficacyin controlling a massive outbreak of these two diseases in air force recruits at Lackland Air Force Base, Texas, ...were studied. Recorded cases of measles declined from a high of 1,345 in 1976 to a low of 227 in 1979. Similarly, rubella cases declined from a peak before the immunization program of 1,361 in 1977 to a low of 67 in 1979. A controlled study of morbidity related to immunization revealed that there is less immediate local morbidity from immunizations against measles and rubella than with other routine immunizations. Recruits who received the attenuated viral vaccines reported fever, myalgias, and diarrhea only slightly more frequently than did recruits in the concurrent control group. The present data indicate that measles and rubella, increasingly consequential diseases among young adults, can be safelyand effectively controlled with attenuated viral vaccines.
Photon correlation spectroscopy has been applied to study phase transitions of planar bilayer membranes. The membrane tension and one specific membrane viscosity are probed. Difficulties arising in ...the measurement of the temperature dependence of these properties are discussed and a servo-control system to overcome them is described. Typical data are presented for monoglyceride bilayers. Membranes incorporating cholesterol display effects below the lipid transition temperature which are interpreted in terms of separation within the membrane into cholesterol-rich fluid regions and regions of lipid in the gel phase. Some of the cholesterol-rich regions are apparently of macroscopic extent.
Ammopiptanthus nanus is an endangered evergreen shrub endemic to the deserts of central Asia and plays an important role in delaying further desertification. We examined allozyme variation and AFLP ...diversity in A. nanus populations and investigated the mating system of this species using progeny arrays assayed for polymorphic allozyme loci. Mating system analysis in the Keyi＇eryongke＇er population showed low levels of outcrossing, and strong inbreeding depression. Low levels of genetic variation were detected at both population （allozyme, Pp=14.0%, A=l.14, He=0.031; AFLP, Pp=14.5%, Shannon＇s information index I=0.063） and species （allozyme, Pp=21.1%, A=1.21, He=0.040; AFLP, Pp=20.9%, I=0.083） levels; while moderate genetic differentiation existed among populations, as indicated by allozymes （Gsa-=0.081） and AFLP （GST=0.151-0.193）. Founder effect, bottlenecks in evolutionary history, the mixed mating system and co-ancestry may have influenced the level of genetic diversity in A. nanus. Markers of both types provide new insights for conservation management, indicating that the Biao＇ertuokuoyi and Keyi＇eryongke＇er populations should be given priority for in situ conservation and regarded as seed sources for ex situ conservation.
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