4,534 research outputs found
The Solvating Power of Anhydrous Magnesium Bromide as a Possible Function of Its Preparation Temperature
Before undertaking a study of the solvates of magnesium bromide, a method for preparing a reproducibly active anhydrous salt must be found. A suitable method is by the direct union of magnesium and bromine in ether, according to the procedure of Zelinsky. This results in the formation of etherates, from which the anhydrous salt can be obtained by desolvating at a moderately high temperature in a vacuum. It is known that if too high a temperature is used in the preparation of anhydrous aluminum oxide or calcium sulfate, the resulting product will not recombine with water. It is conceivable that the solvating power of anhydrous magnesium bromide, prepared from its etherates, might in an analogous way be a function of the preparation temperature. To test the possible effect of temperature on the solvating property of magnesium bromide, samples were desolvated under reduced pressure at 100°, 200°, 300° and 400° C. A constant stream of air saturated with ether at 20° was then passed over the samples, which were kept at 25° and weighed at intervals. The rates of solvation for the various samples were found to be equal within experimental error. It is conceded that the necessity of using interchangeable ground-glass joints permitted the entrance of traces of moisture, but within the temperature ranges studied, we feel justified in stating that the solvating power of anhydrous magnesium bromide is not a function of its preparation temperature
Density Matrix Renormalization for Model Reduction in Nonlinear Dynamics
We present a novel approach for model reduction of nonlinear dynamical
systems based on proper orthogonal decomposition (POD). Our method, derived
from Density Matrix Renormalization Group (DMRG), provides a significant
reduction in computational effort for the calculation of the reduced system,
compared to a POD. The efficiency of the algorithm is tested on the one
dimensional Burgers equations and a one dimensional equation of the Fisher type
as nonlinear model systems.Comment: 12 pages, 12 figure
Fusion barrier distributions in systems with finite excitation energy
Eigen-channel approach to heavy-ion fusion reactions is exact only when the
excitation energy of the intrinsic motion is zero. In order to take into
account effects of finite excitation energy, we introduce an energy dependence
to weight factors in the eigen-channel approximation. Using two channel
problem, we show that the weight factors are slowly changing functions of
incident energy. This suggests that the concept of the fusion barrier
distribution still holds to a good approximation even when the excitation
energy of the intrinsic motion is finite. A transition to the adiabatic
tunneling, where the coupling leads to a static potential renormalization, is
also discussed.Comment: 9 pages, 4 figures, Submitted to Physical Review
RNA-Containing Cytoplasmic Inclusion Bodies in Ciliated Bronchial Epithelium Months to Years after Acute Kawasaki Disease
Kawasaki Disease (KD) is the most common cause of acquired heart disease in children in developed nations. The KD etiologic agent is unknown but likely to be a ubiquitous microbe that usually causes asymptomatic childhood infection, resulting in KD only in genetically susceptible individuals. KD synthetic antibodies made from prevalent IgA gene sequences in KD arterial tissue detect intracytoplasmic inclusion bodies (ICI) resembling viral ICI in acute KD but not control infant ciliated bronchial epithelium. The prevalence of ICI in late-stage KD fatalities and in older individuals with non-KD illness should be low, unless persistent infection is common.Lung tissue from late-stage KD fatalities and non-infant controls was examined by light microscopy for the presence of ICI. Nucleic acid stains and transmission electron microscopy (TEM) were performed on tissues that were strongly positive for ICI. ICI were present in ciliated bronchial epithelium in 6/7 (86%) late-stage KD fatalities and 7/27 (26%) controls ages 9-84 years (p = 0.01). Nucleic acid stains revealed RNA but not DNA within the ICI. ICI were also identified in lung macrophages in some KD cases. TEM of bronchial epithelium and macrophages from KD cases revealed finely granular homogeneous ICI.These findings are consistent with a previously unidentified, ubiquitous RNA virus that forms ICI and can result in persistent infection in bronchial epithelium and macrophages as the etiologic agent of KD
On the decay of deformed actinide nuclei
decay through a deformed potential barrier produces significant
mixing of angular momenta when mapped from the nuclear interior to the outside.
Using experimental branching ratios and either semi-classical or
coupled-channels transmission matrices, we have found that there is a set of
internal amplitudes which are essentially constant for all even--even actinide
nuclei. These same amplitudes also give good results for the known anisotropic
particle emission of the favored decays of odd nuclei in the same mass
region.
PACS numbers: 23.60.+e, 24.10.Eq, 27.90.+bComment: 5 pages, latex (revtex style), 2 embedded postscript figures
uuencoded gz-compressed .tar file To appear in Physical Review Letter
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