4,665 research outputs found
On the nature of amorphous polymorphism of water
We report elastic and inelastic neutron scattering experiments on different
amorphous ice modifications. It is shown that an amorphous structure (HDA')
indiscernible from the high-density phase (HDA), obtained by compression of
crystalline ice, can be formed from the very high-density phase (vHDA) as an
intermediate stage of the transition of vHDA into its low-density modification
(LDA'). Both, HDA and HDA' exhibit comparable small angle scattering signals
characterizing them as structures heterogeneous on a length scale of a few
nano-meters. The homogeneous structures are the initial and final transition
stages vHDA and LDA', respectively. Despite, their apparent structural identity
on a local scale HDA and HDA' differ in their transition kinetics explored by
in situ experiments. The activation energy of the vHDA-to-LDA' transition is at
least 20 kJ/mol higher than the activation energy of the HDA-to-LDA transition
Globular Clusters around Galaxies in Groups
We have obtained deep photometry of NGC 1199 (in HCG 22) and NGC 6868 (in the
Telescopium group). Both galaxies are the optically brightest galaxies of their
groups. Our analysis of B and R images taken with the Keck II and the VLT/ESO
telescopes, detected a population of globular clusters around both galaxies,
with total specific frequencies S_N=1.7\pm0.6 for NGC 1199 and S_N = 1.3\pm0.6
for NGC 6868. The color distributions of the globular cluster systems shows
bimodal peaks centered at (B-R)_0 = 1.13\pm0.10 and 1.42\pm0.10 (NGC 1199) and
(B-R)_0=1.12\pm0.10 and 1.42\pm0.10 (NGC 6868).Comment: 3 pages, 1 figure. To appear in the proceedings of IAU Symp. 207,
"Extragalactic Star Clusters", eds. E. Grebel, D. Geisler, D. Minnit
Hydrophilic polymer embolism identified in brain tumor specimens following Wada testing: A report of 2 cases
Hydrophilic polymers are commonly used as coatings on intravascular medical devices. As intravascular pro-cedures continue to increase in frequency, the risk of embolization of this material throughout the body has become evident. These emboli may be discovered incidentally but can result in serious complications includ-ing death. Here, we report the first two cases of hydrophilic polymer embolism (HPE) identified on brain tu-mor resection following Wada testing. One patient experienced multifocal vascular complications and diffuse cerebral edema, while the other had an uneventful postoperative course. Wada testing is frequently per-formed during preoperative planning prior to epilepsy surgery or the resection of tumors in eloquent brain regions. These cases demonstrate the need for increased recognition of this histologic finding to enable fur-ther correlation with clinical outcomes
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