Biomedical subjects
Publications and source records attributed to J Buttet.
Ag19 cluster ions are mass selected and deposited on a Pt(111) surface covered by five monolayers of Kr. Almost monodispersed hexagonal shaped Ag islands are observed after Kr evaporation at 125 K. The identification of the island shape and the exact number of atoms has been successful by decorating the clusters with Kr atoms which can be counted by high resolution scanning tunneling microscopy.
The fluorescence of Ag8 in an argon matrix and in argon droplets is reported. This is the first unambiguous assignment of the fluorescence of a metal cluster larger than the tetramer, indicating that the excited state lifetime is longer than previously thought. It is discussed as a possible result of a matrix cage effect. The excitation spectrum is compared with two-photon-ionization measurements of Ag8 in helium droplets and to known absorption data. The agreement is excellent. We propose that the excited states relax rapidly through vibrational coupling to a long-lived state, from which the fluorescence occurs.
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Variable-temperature scanning tunneling microscopy was used to study the effect of kinetic cluster energy and rare-gas buffer layers on the deposition process of size-selected silver nanoclusters on a platinum(111) surface. Clusters with impact energies of </=1 electron volt per atom could be landed nondestructively on the bare substrate, whereas at higher kinetic energies fragmentation and substrate damage were observed. Clusters with elevated impact energy could be soft-landed via an argon buffer layer on the platinum substrate, which efficiently dissipated the kinetic energy. Nondestructive cluster deposition represents a promising method to produce monodispersed nanostructures at surfaces.
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A bilingual virtuoso piano teacher developed aphasia and amusia, probably due to cerebral embolism. The perfectly demarcated and unique lesion was located in the left posterior temporoparietal region. Language examinations in French and Italian demonstrated entirely comparable difficulties in both languages. The linguistic course was favorable after a period of auditory agnosia and global aphasia. Language became fluent again 3 months after the onset, with a marked vocabulary loss and phonemic paraphasias with attempts at self-correction. Repetition was altered markedly with a deficit in auditory comprehension but no remaining elements of auditory agnosia. Reading was possible, but with some difficulty and total agraphia and acalculia persisted. Musical ability was better conserved, particularly with respect to repetition and above all to writing, the sparing of the latter constituting a fairly uncommon dissociation in relation to agraphia. Findings are discussed in relation to data in the literature concerning hemispheric participation in various musical tasks.
The ambiguity in the literature concerning cerebral dominance for voice recognition, has been investigated with a monaural go-no go task, using male and female voices. A left ear advantage for the male, and a right ear advantage for the female voice was found, suggesting that both hemispheres can perform voice recognition. A monaural word recognition test showed the expected left hemisphere dominance.
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A method is described for provoking conflict between prosody and syntax in orally enounced phrases. The results obtained in a group of normal subjects show that there is restructuring of syntax organization in a phrase heard with abnormal intonation.