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5. Elastic Behavior of a Two-dimensional Crystal near Melting

Author

von Grünberg, H. H., Keim, P., Zahn, K., and Maret, G.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

Using positional data from video-microscopy we determine the elastic moduli of two-dimensional colloidal crystals as a function of temperature. The moduli are extracted from the wave-vector-dependent normal mode spring constants in the limit $q\to 0$ and are compared to the renormalized Young's modulus of the KTHNY theory. An essential element of this theory is the universal prediction that Young's modulus must approach $16 \pi$ at the melting temperature. This is indeed observed in our experiment., Comment: 4 pages, 3 figures

Published
2004
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6. Elastic properties of 2D colloidal crystals from video microscopy

Author

Zahn, K., Wille, A., Maret, G., Sengupta, S., and Nielaba, P.

Subjects
Condensed Matter
Abstract

Elastic constants of two-dimensional (2D) colloidal crystals are determined by measuring strain fluctuations induced by Brownian motion of particles. Paramagnetic colloids confined to an air-water interface of a pending drop are crystallized under the action of a magnetic field, which is applied perpendicular to the 2D layer. Using video-microscopy and digital image-processing we measure fluctuations of the microscopic strain obtained from random displacements of the colloidal particles from their mean (reference) positions. From these we calculate system-size dependent elastic constants, which are extrapolated using finite-size scaling to obtain their values in the thermodynamic limit. The data are found to agree rather well with zero-temperature calculations., Comment: 4 pages, Latex, 4 eps figures

Published
2002
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19. Thoracoscopic versus open repair of CDH in cardiovascular stable neonates

Author

Costerus, S.A. (Sophie), Zahn, K. (K.), Ven, K. (Kees) van de, Vlot, J. (John), Wessel, L., Wijnen, R.M.H. (René), Costerus, S.A. (Sophie), Zahn, K. (K.), Ven, K. (Kees) van de, Vlot, J. (John), Wessel, L., and Wijnen, R.M.H. (René)

Abstract

Background: Thoracoscopic surgery is an increasingly popular surgical technique to repair congenital diaphragmatic hernia (CDH). However, acidosis during surgery and the higher recurrence rate are considerable risk factors. The aim of this retrospective study is to compare the outcome of open versus thoracoscopic repair of the diaphragm in neonates with CDH with the same degree of cardiovascular and pulmonary illness who meet the criteria for thoracoscopic repair. Methods: Retrospective analysis of all patients of two large national reference centers for CDH born in the years 2008 through 2012, and meeting the criteria for surgical repair on cardiopulmonary and physiological criteria according to the CDH EURO consortium consensus and meeting the criteria for thoracoscopic repair according to the review by Vijfhuize et al. The surgical technical aspects were comparable in both centers. Results: 108 patients were included, of whom 75 underwent thoracoscopic repair and 34 underwent open repair. The gestational age and lung-to-head ratio were significantly lower and stay on the ICU significantly longer in the open-repair group. The operation time was longer (178 vs. 150 min, p = .012) and the recurrence rate higher (18.9 vs. 5.9 %, p = .036) in the thoracoscopic-repair group. The arterial pH, pO2, pCO2 and base excess before and after thoracoscopic repair were all significantly different. Conclusion: After critical selection for thoracoscopic repair of left-sided CDH based on the patient’s preoperative condition, the outcomes of open repair were almost identical to those of thoracoscopic repair. A notable exception is the recurrence rate, which was significantly higher in the thoracoscopic-repair group. For the time being, thoracoscopic primary closure seems a safe and effective procedure, but efficacy of thoracoscopic patch repair has not been established.

Published
2016
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27. Einsatz eines Dermisersatzes (Matriderm ® ) bei thermischen Verletzungen der kindlichen Hand

Author

Königs, I, Zahn, K, Reinshagen, K, Göppl, M, and Wessel, LM

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Einleitung: Insbesondere im Kindesalter ist die vollständige Wiederherstellung der Funktion der Hand nach thermischer Verletzung ein entscheidendes Ziel der modernen Verbrennungsmedizin. Nach Transplantationen bei drittgradigen Verbrennungen kommt es oft zu einer ausgedehnten Narbenbildung mit [for full text, please go to the a.m. URL], 127. Kongress der Deutschen Gesellschaft für Chirurgie

Published
2010
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