160 research outputs found
An unusual cause of difficult weaning in a patient with newly diagnosed small cell lung cancer
AbstractWe describe a patient with acute respiratory insufficiency and difficult ventilator weaning in the ICU ward, leading to diagnosis of small cell lung cancer with superior vena cava superior syndrome. Bilateral vocal cord paralysis caused his respiratory distress and weaning difficulties. Thyroidectomy and neurological problems (such as Parkinson disease and Guillain Barré syndrome) are more common causes of bilateral vocal cord paralysis. Lung cancer patients are also at risk due to mediastinal invasion. The left recurrent laryngeal nerve is more prone to paralysis because of the typical anatomy. In contrary, bilateral vocal cord paralysis is rare and doesn't result in speech problems but rather breathing difficulties. Tracheostomy is the classic therapy, but laser cordectomy and Botulinum toxin injection in the laryngeal muscles are alternatives
Noncollinear magnetic ordering in small Chromium Clusters
We investigate noncollinear effects in antiferromagnetically coupled clusters
using the general, rotationally invariant form of local spin-density theory.
The coupling to the electronic degrees of freedom is treated with relativistic
non-local pseudopotentials and the ionic structure is optimized by Monte-Carlo
techniques. We find that small chromium clusters (N \le 13) strongly favor
noncollinear configurations of their local magnetic moments due to frustration.
This effect is associated with a significantly lower total magnetization of the
noncollinear ground states, ameliorating the disagreement between Stern-Gerlach
measurements and previous collinear calculations for Cr_{12} and Cr_{13}. Our
results further suggest that the trend to noncollinear configurations might be
a feature common to most antiferromagnetic clusters.Comment: 9 pages, RevTeX plus .eps/.ps figure
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