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Abstract  

The use of 14 MeV neutrons for the analysis of ancient pottery was investigated. Clay pieces from Arezzo and Northern Italy were quantitatively analysed in a completely nondestructive way. A comparison technique using Al-foils as a standard was introduced. The main components Si, Al, Mg and Fe could be evaluated within a short time with an error of a few percent. The grouping resulting from impressed seals on the clay pieces was in full agreement with that resulting from the chemical composition for the potsherds from Arezzo. An analysis of trace elements was also performed for a few samples, but it needs more time for irradiation and measurements.

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Abstract  

Neptunium is sorbed, together with plutonium, uranium and iron on Bio Rad AG 1×4 anion exchange resin from 9 mol/1 HCl, eluted with 7 mol/l HNO3 and 1.2 mol/l HCl, purified on a second, identical column and electrodeposited on stainless steel discs.237Np is determined by -spectrometry,239Np by -spectrometry with a Ge detector, or via its 14.3 keV L X-rays in a Si(Li) measurement. The neptunium yield is determined from the count rate of the 13.6 keV L X rays of the tracer235Np in a later Si(Li) measurement. The average chemical yield is 78±11%. The detection limit for237Np is 1 mBq. The procedure allows the sequential determination of neptunium, together with plutonium, strontium, uranium and iron from one sample. The method was applied to air and total deposition samples from Munich-Neuherberg and to sediment samples from the Irish sea.

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Abstract  

Myocardial uptake and turnover of 17-(123I)-iodoheptadecanoic acid, injected i.v., was studied in rats. Kinetics of radioactivity incorporated into myocardial tissue and heart lipids as well as myocardial radioactivity recovered as123I iodide were determined. Maximal heart uptake of IHA (7.9% dose/g heart) was observed as early as 30 sec., p.i., followed by mono-component elimination period. Already 10 to 30 sec p.i. 70 to 80% of total myocardial radioactivity was recovered as123I iodide. IHA was incorporated only in modest amounts into myocardial phospholipids and triglycerides. Time course of total myocardial radioactivity grossly paralleled that recovered as123I iodide. These findings indicate stringent limitations in utility of IHA as a tracer for assessment of β-oxidation.

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Abstract  

A chemical separation procedure is described which allows the direct determination of low241Pu activities in environmental samples with a windowless gas-flow proportional counter. While current separation schemes based on anion exchange yield counting sources of sufficient purity for subsequent -spectrometry, for -counting of241Pu additional purification steps are required. A combination of anion exchange from 9 mol/l HCl, LaF3 precipitation and TTA extraction was found to be suitable even for the analysis of long-range Chernobyl fallout samples which contained interfering radionuclides with -activities at least 3 to 4 orders of magnitude higher than usually encountered. No difference is detectable between the results of the present, direct procedure and the results of the conventional indirect method based on the build-up of241Am. Average241Pu/239+240Pu ratios in air and deposition samples taken at Neuherberg near Munich were 70±6 with the present procedure and 66±9 from241Am build-up.

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Journal of Thermal Analysis and Calorimetry
Authors:
E. A. Gómez Pineda
,
A. D. Martins Ferrarezi
,
J. G. Ferrarezi
, and
A. A. Winkler Hechenleitner
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Learning & Perception
Authors:
Tamás M. Bőhm
,
Lidia Shestopalova
,
Alexandra Bendixen
,
Andreas G. Andreou
,
Julius Georgiou
,
Guillame Garreau
,
Philippe Pouliquen
,
Andrew Cassidy
,
Susan L. Denham
, and
István Winkler

The human auditory system is capable of grouping sounds originating from different sound sources into coherent auditory streams, a process termed auditory stream segregation. Several cues can influence auditory stream segregation, but the full set of cues and the way in which they are integrated is still unknown. In the current study, we tested whether auditory motion can serve as a cue for segregating sequences of tones. Our hypothesis was that, following the principle of common fate, sounds emitted by sources moving together in space along similar trajectories will be more likely to be grouped into a single auditory stream, while sounds emitted by independently moving sources will more often be heard as two streams. Stimuli were derived from sound recordings in which the sound source motion was induced by walking humans. Although the results showed a clear effect of spatial separation, auditory motion had a negligible influence on stream segregation. Hence, auditory motion may not be used as a primitive cue in auditory stream segregation.

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Learning & Perception
Authors:
Tamás M. Bőhm
,
Lidia Shestopalova
,
Alexandra Bendixen
,
Andreas G. Andreou
,
Julius Georgiou
,
Guillame Garreau
,
Philippe Pouliquen
,
Andrew Cassidy
,
Susan L. Denham
, and
István Winkler

The human auditory system is capable of grouping sounds originating from different sound sources into coherent auditory streams, a process termed auditory stream segregation. Several cues can influence auditory stream segregation, but the full set of cues and the way in which they are integrated is still unknown. In the current study, we tested whether auditory motion can serve as a cue for segregating sequences of tones. Our hypothesis was that, following the principle of common fate, sounds emitted by sources moving together in space along similar trajectories will be more likely to be grouped into a single auditory stream, while sounds emitted by independently moving sources will more often be heard as two streams. Stimuli were derived from sound recordings in which the sound source motion was induced by walking humans. Although the results showed a clear effect of spatial separation, auditory motion had a negligible influence on stream segregation. Hence, auditory motion may not be used as a primitive cue in auditory stream segregation.

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