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D Wortmann

Publications and source records attributed to D Wortmann.

6 recordsLinked to original sources

Resolving complex atomic-scale spin structures by spin-polarized scanning tunneling microscopy.

The spin-polarized scanning tunneling microscope (SP-STM) operated in the constant current mode is proposed as a powerful tool to investigate complex atomic-scale magnetic structures of otherwise chemically equivalent atoms. The potential of this approach is demonstrated by successfully resolving the magnetic structure of Cr/Ag(111), which is predicted on the basis of ab initio vector spin-density calculations to be a coplanar noncollinear periodic 120 degrees Néel structure. Different operating modes of the SP-STM are discussed on the basis of the model of Tersoff and Hamann.

Journal Article↗

Phenomenological diversity of spinal reflexes in brain death.

In brain death, spinal reflexes and automatisms are observed which may cause irritation and even doubt in the diagnosis. In the literature there are no dedicated descriptions of the diversity and of neuroanatomical considerations. In 278 examinations of 235 patients for the determination of brain death, on 42 occasions obvious spinal reflexes and/or spinal automatisms were observed in 27 brain dead bodies. Because they were not systematically searched for, minute forms have probably been missed. The reflexes (R) and automatisms (A) are described according to the time of observation in relation to the development of brain death, the presumable spinal localization and the possible phylogenetical interpretation. Especially disquieting examples are discussed in more detail, e.g. monophasic EndotrachealSuction-ThoracicContraction-R supposedly switched in segments C2-6 or TrapeziusPinch-ShoulderProtrusion-R conveyed by the accessory nerve (terminology according to the scheme: for the reflexes, Trigger-Response-R: for the automatisms, Movement-A). After these experiences a more thorough examination showed frequent observations of rather minute forms of spinal reflexes, as well as automatisms and even the Lazarus sign (in possibly more than two thirds of the examinations). An estimation of the factual frequency would necessitate special attention to those much more frequent but less obvious minute spinal reflexes and automatisms.

Adult↗